2011 NSF Proposal
This proposal requests support to continue a program using electromagnetic probes to study hadronic matter on a fundamental level at the Thomas Jefferson National Accelerator Facility. The Nuclear Physics group at Idaho State University has added a new faculty member since the last proposal three years ago. The group has also begun constructing five drift chambers for Jefferson Lab's Hall B upgrade. We are requesting support from the NSF to allow our graduate students to complete their Ph.D. degrees under our current physics program and facilitate the construction of the above equipment for the 12 GeV JLab upgrade.
Project Summary
Intellectual Merit
\begin{center} {\it \underline {The Intellectual Merit of the Proposed Activities}} \end{center}
The intermediate energy nuclear physics group at Idaho State University (ISU) has an established fundamental physics program based at Jefferson Lab. ISU group members Dr.~Dustin McNulty and Dr.~Tony Forest are currently managing the construction and testing of the CLAS12 Region I drift chambers at ISU for Jefferson Lab's 12 GeV upgrade. The group's physics program includes nucleon spin structure and resonance studies, analysis of vector meson and hyperon photoproduction, a precision measurement of the $\pi^0$ lifetime, and precision measurements of parity violating electron scattering. Dr.~Tony Forest and Dr.~Philip Cole are co-spokespersons on approved 12~GeV Hall~B experiments PR12-06-109 and PR12-09-003, respectively. Dr.~Cole and three graduate students are presently focused on comprehensive measurements of vector meson and hyperon photoproduction employing linearly polarized photons to improve our understanding of the underlying symmetry of the quark degrees of freedom in the nucleon, the nature of the parity exchange between the incident photon and the target nucleon, and the mechanism of associated strangeness production in electromagnetic reactions. Dr.~Dan Dale is a spokesperson of the PrimEx Collaboration which is performing a high precision measurement of the $\pi^0$ lifetime as a test of the QCD chiral anomaly plus corrections. This measurement uses photoproduction in the Coulomb field of a nucleus to facilitate a stringent test of the fundamental predictions of quantum chromodynamics in the confinement scale regime. Dr.~Dustin McNulty and Dr.~Tony Forest are collaborators in parity violation experiments PR12-09-005 and E05-008 respectively with a focus on measuring the low energy constant $d_{\Delta}$ using inelastic parity violation.
Broader Impacts
\begin{center} {\it \underline {Broader Impacts of the Proposed Activities}} \end{center}
In addition to the scientific program described here, this proposal represents a major effort in the area of educating future scientists. The present shortage of graduate students in experimental and theoretical nuclear physics is having a detrimental impact on our national laboratories and facilities which posses a plethora of data but limited manpower for analyzing and disseminating the information. The Idaho State University Department of Physics is comprised of nine tenure track faculty, all of whom have research interests which are in some way connected to nuclear physics and are in a position to directly address the shortage of graduate students. With its on campus accelerator and detector laboratories, the Department focuses on experimental and applied physics, giving students a strong hands-on educational experience. ISU's physics program is relatively new and rapidly growing. Last year, ISU physics faculty brought in approximately \$8 million in external research funds. Its Ph.D.~program, established in the Fall of 2005, presently has approximately 30 students with an additional 15 students pursuing research at the M.S.~level.
The PIs are further strengthening the ISU graduate program by recruiting high-caliber students from Latin America. Latin America remains an underutilized intellectual resource. The ISU Group has strong ties to Colombia and has attracted four talented graduate students into nuclear physics at ISU; three are working on JLab-related projects and one graduated in late 2009 and is now an Assistant Professor in Bogot\'{a}, Colombia. The activities delineated within this proposal will provide another avenue through which the program can continue to solidify this mutually beneficial bridge of collaboration among countries in the Americas.
Project Description
File:2011projectDescription.pdf
A Program to Study Hadronic Matter using Electromagnetic Probes at JLab
We are requesting continuing NSF support for our established program studying hadronic matter using electromagnetic probes. This program currently supports four graduate students, three of whom are in mid stride towards completing their Ph.D.s~in experimental nuclear physics. Even though the group was recently formed at Idaho State University, each of the senior-level participants have an established history of intense involvement in the Jefferson Lab (JLab) physics program from their research at their former universities. The PIs, moreover, have a strong record of constructing scientific instrumentation with NSF funding and each has made substantial impacts to the field. The significance of our research and the objectives for the proposed work period are described in section~\ref{section:IntelectMerits}. Through our well established partnership with several universities in the Americas, we discuss in section~\ref{section:BroaderImpacts} our continued recruitment of underrepresented groups in physics. The requested funding will not only enable our graduate students to complete their JLab data analysis in a timely manner and obtain their Ph.D.~degrees, but these monies will further provide the necessary support to enable Idaho State University to construct five of the six inner Region I (R1) drift chambers for the 12~GeV upgrade to Hall~B of JLab; these tracking chambers being a critical-path item for the upgrade.
Intellectual Merit of the Proposed Activity
The ISU Physics Program
Jefferson Lab 12 GeV program
The physics Ph.D.~students at ISU are currently analyzing data, taken by the CLAS collaboration, to elucidate the structure of a nucleon using polarization observables. The extraction of photonuclear asymmetries and measurements of a nucleon's polarized quark distribution functions have been the group's two central objectives. The next step in the pursuit of these objectives will require the use of a 12-GeV energy upgrade to CEBAF. The ISU group has become responsible for the construction of five drift chambers for the Hall-B detector upgrade (CLAS12) as a means to achieve the above objectives and as a service to the intermediate energy nuclear physics community.
CLAS12 Region I Drift Chamber Construction
The ISU group has been contracted by Jefferson Science Associates to construct five drift chambers for the 12 GeV upgrade to Hall~B. Two members of the group, Dr.~Dustin McNulty and Dr.~Tony Forest, constructed a Class-10,000 clean room this past summer for the project. The first chamber is currently being strung with wires, as shown in the figure below, and is expected to be completed by January 2011. Each chamber takes approximately 25~weeks to construct. A team of stringers and a lead stringer have been hired for this task with the ISU group taking the role of management and quality control. We expect to complete the last chamber before October, 2013.
Although Jefferson Lab has provided adequate support for the construction of the chambers, the ISU group has made a commitment to support the quality assessment and testing of the drift chambers. Tension measurements and continuity tests are the first steps of quality assurance that are done during the drift chamber construction phase. The Figure below illustrates a measurement of the drift chamber wire tension after stringing to ensure that it meets specifications. The next steps are to monitor the initial current draw of a powered chamber and measure sense wire signals resulting from cosmic ray induced ionization events in the drift chamber. The ISU group will oversee these quality controls and tests before the chambers are shipped to JLab for installation.
\singlespace \begin{figure} [!hbp] \begin{center} { \scalebox{0.5} [0.5]{\includegraphics[height=6in]{figs/10242011_Pic1.eps}} \scalebox{0.5} [0.5]{\includegraphics[height=6in]{figs/10182011_Tension_SS.eps}} } \caption{The left figure shows a photograph of two technicians constructing one of the R1 drift chambers in the ISU physics clean room. The right figure is an illustration of a wire tension measurement made by comparing the phase of a current induced in a drift chamber wire by a small external magnetic field (Analog $X$) to a driving force generated by a sinusoidal current (Analog $Y$). The driving force is applied for several periods of the drive frequency and then compared to the response observed during an equal time interval~\cite{RothNIM}.} \label{delqJLab} \end{center} \end{figure} \doublespace
The CLAS12 Polarized Structure Function Program
\paragraph{The CLAS12 Polarized Structure Function Program}
Spin structure functions of the nucleon have been measured in deep inelastic lepton scattering (DIS)for nearly 30 years since the first experiments at SLAC. Interest increased substantially in the 80s when the EMC collaboration reported that the quark helicities only made a small contribution to the overall helicity of the proton, according to their data. This ``spin crisis" led to a vigorous theoretical and experimental effort over the next 20 years, with a large data set collected at CERN, SLAC, DESY, and JLab.
Interest in the quark contributions to a nucleon's structure continues unabated. At large Bjorken $X$, new data from JLab address for the first time the question of the helicity structure of the nucleon in a kinematic realm where sea quark and gluon contributions are minimal thereby making one mostly sensitive to valence quarks. An example of these results is shown in Fig.~\ref{deltadJLab}. To extend this region to higher $x$ and moderate $Q^2$, one needs higher beam energies than presently available at JLab. In particular, to test various models of the asymptotic value of the virtual photon asymmetry $A_1(x)$ as $x \rightarrow 1$, one needs the upgraded CEBAF with 12 GeV beam energy.
\singlespace
\begin{figure} [t]
\begin{center}
{
\scalebox{0.4} [0.5]{\includegraphics[height=5in]{figs/DeltaDoverD_CLAS12.eps}}
}
\caption{The expected statistical uncertainty of a $\Delta d/d$ measurement from CLAS12. The dashed line represents a pQCD prediction while the solid line represents the prediction from a hyperfine perturbed constituent quark model. The solid triangles are measurements from X. Zheng et al.~\cite{Zhang}, and the diamond are from A. Airapetian et al.~\cite{AirapetianHERMES}. The squares represent a prediction of the precision obtained by a SIDIS measurement performed using the energy upgraded CEBAF and the upgraded CLAS. The risers represent systematic uncertainty and the error bar lines are statistical uncertainties.}
\label{deltadJLab}
\end{center}
\end{figure}
\doublespace
The comprehensive data set to be collected by experiment PR12-06-109 will contribute substantially to our knowledge of polarized parton distribution functions for all quark flavors and even the polarized gluon distribution $\Delta g$. Through Next-to-Leading Order (NLO) analysis of the world data on inclusive DIS (using the DGLAP evolution equations), one can constrain these distribution functions and their integrals. Existing CLAS data from 6 GeV have already made an impact on these fits. The expected data from the proposed experiment at 11 GeV will yield further dramatic reductions in the errors on these distributions. Semi-inclusive DIS (SIDIS) data will also be collected, where, in addition to the scattered electron, we will also detect some of the leading hadrons produced after the struck quark hadronizes. These data will further constrain the NLO fits and improve the separation of the various quark flavors' contribution to nucleon observables.
N*s at 12 GeV
For the foreseeable future, the CLAS12 detector will be the sole facility worldwide capable of delivering comprehensive information on the $\gamma_{v}NN^*$ transition helicity amplitudes -- and thereby the electrocouplings -- at photon virtualities of $Q^2 >$ 5.0 GeV$^2$ and in the mass range up to 2 GeV. Electrocouplings will be extracted from the electroproduction of the primary meson reaction channels ($n\pi^{+}$, $p\pi^{0}$, $p\eta$, and $p\pi^{+}\pi^{-}$) as is discussed in our approved CLAS12 proposal~\cite{Nstar-12GeV}. Through our recent work~\cite{Az09,Mo09} at $Q^2$ $<$ 5.0 GeV$^2$, we have found consistent results on the $\gamma_{v}NN^*$ electrocouplings in both the single- and double-pion modes as can be seen in the left plot of Fig.~\ref{D13+qmass}. Investigating the evolution of the $\gamma_{v}NN^*$ electrocouplings for several prominent excited states at $Q^2 > 5.0$~GeV$^2$ will offer direct access to the quark structure of the nucleon (see right plot of Fig.~\ref{D13+qmass}). The data for our approved experiment (PR12-09-003)~\cite{Nstar-12GeV} will, for the first time, allow one to study the kinematic regime for momenta running over the quark propagator for momenta $p <$~1.1~GeV, which spans the transition from almost-completely dressed constituent quarks to the almost-completely undressed current quarks. At these distance scales, meson-baryon cloud contributions are expected to be small or negligible. In conjunction with detailed information on the nucleon ground state structure from the other experiments at 12 GeV, a comprehensive data set, allowing us to access quark contributions to the spectrum of nucleon states, will be available for the very first time. The results from our experiment will provide:
\begin{itemize} \item access to the dynamics of nonperturbative strong interactions among dressed quarks and to shed light on their emergence from QCD and the subsequent N$^*$ formation. \item information on how the constituent quark mass arises from a cloud of low-momentum gluons which constitute the dressing to the current quarks. This process of dynamical chiral symmetry breaking accounts for over 97\% of the nucleon mass. \item enhanced capabilities for exploring the behavior of the universal QCD $\beta$-function in the infrared regime. \end{itemize}
As new theoretical developments emerge, we shall certainly follow up on them as we did in documenting the detailed plan on theory support for our proposal in the 62-page White Paper entitled, {\it Theory Support for the Excited Baryon Program at the JLab 12 GeV Upgrade}, which appeared as a preprint~\cite{Wp09}.
\singlespace \begin{figure} [!hbp] \begin{center} { \scalebox{0.5} [0.5]{\includegraphics{figs/A12_CLAS12_NSFProp2011.eps}} \scalebox{0.5} [0.5]{\includegraphics{figs/Mp_CLAS12_NSFProp2011.eps}} } \caption{Left side: Electrocouplings for $D_{13}(1520)$ state determined from the CLAS data on $N\pi$ electroproduction \cite{Az09} (red points) from a combined analysis of the $N\pi$ and $N\pi\pi$ channels. Differences between the data at $Q^2$ $<$ 1.0 GeV$^2$ and quark model \cite{Gia08} calculations (dotted curve) highlight possible contributions from meson-baryon dressing (red dashed curve)~\cite{Suz10}. Right side: Dressed quark mass as a function of momentum for light-quarks, obtained in the Landau gauge: solid curves are the Dyson-Schwinger Equation results, including the chiral-limit~\cite{Bh03,Bh06}; points with error bars are the results from unquenched LQCD~\cite{Bow}.} \label{D13+qmass} \end{center} \end{figure} \doublespace
Primex II
\subsubsection{A Precision Measurement of the Neutral Pion via the Primakoff Effect}
CoPI Dan Dale is a spokesperson for an experiment at Jefferson Lab to perform a precision measurement of the neutral pion lifetime using the Primakoff production mechanism. The PI of this proposal, Dr.~Dustin McNulty, has recently joined the Idaho State University group, and is also an active member of the PrimEx Collaboration. Dr.~McNulty played a major role in the construction and installation of the experiment at JLab, and also led a major data analysis effort.
The $\pi^o \rightarrow \gamma \gamma$ decay represents an important process in the anomaly sector in that it reflects an explicit breaking of a classical symmetry by the quantum fluctuations of the quark fields coupling to the electromagnetic field\cite{book}. In the limit of vanishing quark masses (the chiral limit), the leading order (LO) amplitude is precisely specified in terms of the fine structure constant, the pion decay constant, and the number of colors in QCD. Namely,
\begin{equation} \Gamma(\pi^o\rightarrow \gamma \gamma) = \frac{\alpha^2 M_{\pi}^3}{576 \pi^3 F_{\pi}^2} N_c^2 = 7.73 eV \end{equation}
This prediction contains no unknown low-energy constants or form factors and is in agreement with the currently accepted experimentally determined value for the radiative width of $7.74 \pm 0.46 eV$\cite{PDB}, thus confirming the number of colors in QCD, $N_c$, to be three. Corrrections, however, arise due to the fact that the physical current quark masses are not zero, {\em viz.}, $m_u \simeq 4 MeV$ and $m_d \simeq 7 MeV$. Because of the low level of precision of the current experiments, the NLO theoretical predictions for the $\pi^o\rightarrow \gamma \gamma$ decay width are yet to be tested. The level of precision of $\simeq 1.4\%$, which is the goal of the PrimEx experiment, will satisfy these requirements.
Since the original PrimEx proposal, several new theoretical calculations have been published and are shown in Fig.~\ref{fig:theory}. The calculation labeled NLO in Fig.~\ref{fig:theory} represents an analysis performed in the framework of Chiral Perturbation Theory (ChPT). This result derives from an approach utilizing a combined framework of chiral perturbation theory and the $1/N_c$ expansion up to ${\cal{O}}(p^6)$ and ${\cal{O}}(p^4\times 1/N_c)$ in the decay amplitude\cite{Goity}. As can be seen in the figure, these corrections result in an enhancement of about $4.5\%$ to the $\pi^o$ decay width with respect to the case without state mixing, indicated by LO in the figure. The uncertainty in the ChPT prediction is estimated to be $1\%$. Corrections to the chiral anomaly have also been performed using dispersion relations and QCD sum rules \cite{Ioffe07}, and are indicated by ``Ioffe07 in the figure. Here, the only input parameter in this calculation is the $\eta$ width.
\singlespace \begin{figure} \centering \includegraphics[height=3.0in]{figs/pdg_data_with_primex_28.eps} \caption{$\pi^o \rightarrow \gamma \gamma$ decay width in eV with theoretical predictions of Ioffe and Goity. The result of PrimEx I is indicated.} \label{fig:theory} \end{figure} \doublespace
The PrimEx experiment seeks to perform a high precision measurement of the neutral pion radiative width to test these state-of-the-art calculations. We are using quasi-monochromatic photons of energy 4.6-5.8~GeV from the Hall~B photon tagging facility to measure the absolute cross section of small angle $\pi^{o}$ photoproduction from the Coulomb field of complex nuclei. The invariant mass and angle of the pion are reconstructed by detecting the $\pi^{o}$ decay photons from the $\pi^{o} \rightarrow \gamma \gamma$ reaction. For unpolarized photons, the Primakoff cross section is given by:
\begin{equation} \frac{d\sigma_P}{d\Omega}= \Gamma_{\gamma \gamma}\frac{8{\alpha}Z^2}{m^3}\frac{\beta^3{E^4}}{Q^4}|F_{e.m.}(Q)|^ 2 \sin^{2}\theta_{\pi} \label{eqn:prim} \end{equation}
\noindent where $\Gamma_{\gamma \gamma}$ is the pion decay width, $Z$ is the atomic number, $m$, $\beta$, $\theta_{\pi}$ are the mass, velocity and production angle of the pion, $E$ is the energy of incoming photon, $Q$ is the momentum transfer to the nucleus, and $F_{e.m.}(Q)$ is the nuclear electromagnetic form factor, corrected for final state interactions of the outgoing pion. As the Primakoff effect is not the only mechanism for pion photoproduction at high energies, some care must be taken to isolate it from competing processes. In particular, the full cross section is given by:
\begin{equation} \frac{d\sigma}{d\Omega_{\pi}} = \frac{d \sigma_P}{d\Omega} + \frac{d\sigma_C}{d \Omega} + \frac{d \sigma_I}{d\Omega}+ 2 \cdot \sqrt{\frac{d\sigma_{P}}{d\Omega} \cdot \frac{d\sigma_{C}}{d\Omega}} cos(\phi_1 + \phi_2) \label{eqn:tot} \end{equation}
\noindent where the Primakoff cross section, $\frac{d \sigma_P}{d\Omega}$, is given by equation \ref{eqn:prim}. The nuclear coherent cross section is given by:
\begin{equation} \frac{d\sigma_C}{d \Omega} = C \cdot A^2 |F_N(Q)|^2 \sin^2\theta_{\pi} \end{equation} and the incoherent cross section is:
\begin{equation} \frac{d \sigma_I}{d\Omega}=\xi A (1-G(Q)) \frac{d \sigma_H}{d\Omega} \end{equation}
where $A$ is the nucleon number, $C \sin^2\theta_{\pi}$ is the square of the isospin and spin independent part of the neutral meson photoproduction amplitude on a single nucleon, $|F_N(Q)|$ is the form factor for the nuclear matter distribution in the nucleus (corrected for final state interactions of the outgoing pion), $\xi$ is the absorption factor of the incoherently produced pions, $1-G(Q)$ is a factor which reduces the cross section at small momentum transfer due to the Pauli exclusion principle, and $\frac{d \sigma_H}{d\Omega}$ is the $\pi^o$ photoproduction cross section on a single nucleon. The relative phase between the Primakoff and nuclear coherent amplitudes without final state interactions is given by $\phi_1$, and the phase shift of the outgoing pion due to final state interactions is given by $\phi_2$. The angular dependence of the Primakoff signal is different from the background processes, allowing $\Gamma(\pi^0\rightarrow \gamma\gamma)$ to be extracted from a fit to the angular distribution of photo-produced neutral pions. Measurements of the nuclear effects at larger angles are necessary to determine the unknown parameters in the production mechanism and thus make an empirical determination of the nuclear contribution in the Primakoff peak region. Consequently, this experiment uses a $\pi^{o}$ detector with good angular resolution to eliminate nuclear coherent production, and good energy resolution in the decay photon detection will enable an invariant mass cut to suppress multi-photon backgrounds.
We submitted our first proposal (E-99-014) to PAC15 in December of 1998. It was approved by PAC15 and reconfirmed in jeopardy review later by PAC22 with an ``A- rating. An NSF MRI proposal for \$970k was awarded (PIs: D.S.~Dale, A.~Gasparian, R.~Miskimen, S.~Dangoulian) for the construction of a multichannel neutral pion calorimeter. This was successfully designed, constructed, and commissioned over the period 2000-2004. The first experiment on two targets ($^{12}$C and $^{208}$Pb) was performed in 2004. A second run (E-08-023, spokespersons: D.~Dale, A.~Gasparian, M.~Ito, R.~Miskimen) was approved by PAC33 with an $A-$ rating for 20 days of running to reach the proposed goal of $\sim 1.4\%$ accuracy. Data were taken for this second phase in the Fall of 2010 on carbon and silicon targets, during which time one of the CoPIs served as run coordinator for the beginning of the run. The CoPI (DSD) of this funding proposal has been involved in all aspects of this program, and has taken primary responsibility for the flux normalization. This has involved the design, construction, and commissioning of the PrimEx pair spectrometer. In addition, along with his students, he has been responsible for the analysis of the resulting data. This has also included a high precision measurement of the absolute cross section of a well known QED process, pair production, to verify that the flux determination was correct.
The PI of this proposal, Dustin McNulty worked extensively on the initial installation of the experiment, and performed a significant portion of the data analysis for PrimEx I. Together, the PI (Dr.~McNulty) and a CoPI (Dr.~Dale) have taken on the responsibility for the aspects of the analysis for PrimEx II which involve the luminosity measurements. This includes analysis of the pair spectrometer data, TAC normalization runs, and electron counting in the photon tagger.
Parity Violation measurements
Parity violation experiments have been performed by two members of the ISU group. The majority of parity violation experiments performed so far have focused on elastic scattering. The group at ISU, as well as other groups, are beginning to look at the parity violating physics of inelastic scattering. PI Forest, in collaboration with S.~Wells and N.~Simicevic, has also outlined a week long experiment to measure $d_{\Delta}$ using the $Q_{weak}$ apparatus~\cite{Qweak} to a statistical precision of less than 0.1 ppm as shown in Figure~\ref{deltadQweak}~\cite{LOIdDelta}. This low energy constant $d_{\Delta}$ was discovered while evaluating the radiative corrections for the PV $N\rightarrow \Delta$ transition~\cite{Zhu012}. The authors in Ref.~\cite{Zhu012} used Siegert's theorem to show the presence of a non-vanishing PV asymmetry at $Q^2=0$ which is proportional to $d_{\Delta}$. The potential implication of a $d_{\Delta}$ measurement to the physics of hyperon decay is described in Reference~\cite{LOIdDelta}. A measurement of the PV asymmetry in the $N\rightarrow \Delta$ transition at the photon point, or at very low $Q^2$ would provide a direct measurement of the low energy constant $d_{\Delta}$.
\singlespace \begin{figure} \centering \includegraphics[height=2.25in]{figs/AdeltaStatErr_Qweak_08312011.eps} \caption{The expected statistical uncertainty for a measurement of $d_{\Delta}$ using the current data set from the last Qweak run and assuming a full week of beam time.} \label{deltadQweak} \end{figure} \doublespace
![]() |
The expected statistical uncertainty for a measurement of $d_{\Delta}$ using the current data set from the last Qweak run and assuming a full week of beam time. |
Results from prior NSF Support
PrimEx I/II
\subsection{Results from Prior NSF Support}
\subsubsection{PrimEx I}
Substantial progress has been made in the PrimEx project during the preceding funding period. First, analysis of the PrimEx I run was completed and the resulting radiative decay width, $\Gamma(\pi^o\rightarrow\gamma\gamma) = 7.82\pm0.14 (stat)\pm0.17(syst.)$ was published in Physical Review Letters\cite{primexIresult}. Figures \ref{minv_elast} and \ref{ang_dist} show elasticity, pion invariant mass, and angular distributions obtained in PrimEx I as an indication of the quality of the data obtained.\\
\singlespace \begin{figure} \centering \includegraphics[height=3in]{figs/minv_elast.eps} \caption{Typical distributions of reconstructed elasticity (left) and $m_{\gamma\gamma}$ (right) for one angular bin.} \label{minv_elast} \end{figure} \doublespace
\singlespace \begin{figure} \begin{center} { \scalebox{0.5} [0.5]{\includegraphics[height=4.5in]{figs/primex1_ang_dist.eps}} \scalebox{0.5} [0.5]{\includegraphics[height=4.5in]{figs/dsdt_lead_partial.eps}} } %\includegraphics[height=3.0in]{figs/primex1_ang_dist.eps} \caption{Differential cross section as a function of $\pi^o$ production angle together with fit results for the different physics processes. Left and right plots are for $^{12}C$ and $^{208}Pb$ targets respectively.} \label{ang_dist} \end{center} \end{figure} \doublespace
Second, a draft of a paper describing the techniques by which the PrimEx Collaboration attained a $1\%$ uncertainty in the luminosity has been prepared by a CoPI (D.~Dale) and is presently circulating in the Collaboration. In 1990, Owens published a paper describing the techniques for analyzing tagged photon experiments\cite{Owens1990}. Building on this work, the PrimEx Collaboration has developed a number of new techniques for luminosity monitoring including the implementation of multi-hit TDCs, electron counting via a sampling method involving clock triggers, and online beam diagnosis with a pair production spectrometer. We expect to submit this paper to NIM in the next couple of months.
\subsection{PrimEx II}
During the Fall of 2010, the PrimEx Collaboration had their second data taking run. In this run, there were several improvements to the experimental setup as compared to PrimEx~I. These included some modifications to the beamline, individual TDCs on the inner modules of the HYCAL pion calorimeter, and increased charged particle veto channels on the pion detector. High quality data were taken on both carbon and silicon targets where approximately 8000 and 20,000 pions were obtained in the two targets, respectively. An example of a preliminary pion angular distribution for the silicon target is shown in Fig.~\ref{figsi}.
\singlespace \begin{figure} \centering \includegraphics[height=2.75in]{figs/silconangulardist.eps} \caption{Preliminary angular distribution as a function of $\pi^o$ production angle for the silicon target in the PrimEx~II run.} \label{figsi} \end{figure} \doublespace
Graduate student analysis results
\subsubsection{Graduate Student Analysis Results}
\medskip \begin{center} \underline{\sf Vector Meson Photoproduction} \end{center}
The probe afforded by a beam of linearly-polarized photons allows one to gain access to several observables in photonucleon reactions, which otherwise would not be measurable. The polarization axis defines a unique direction in space whereby the angular distributions of the final-state particles can be uniquely referenced. The polarization axis of the photon beam breaks the azimuthal symmetry of the reaction, thereby introducing an azimuthal ($\varphi$) dependence to the differential cross section. This additional information on the angular dependence opens the door to the measurement of a host of observables, which are accessible only with a beam of linearly-polarized photons; consequently it provides important constraints on the nature of the photon-nucleon reaction. Such polarization observables are necessary for extracting the spin/parity of the broadly overlapping baryon resonances and measuring such parameters over a large energy range with full angular coverage is crucial for disentangling such contributions.
The scientific purpose of g8~\cite{Cole94,Ted98,FKlein99,Sanabria01,Pasyukg8,g8papers} seeks to improve the understanding of the underlying symmetry of the quark degrees of freedom in the nucleon, the nature of the parity exchange between the incident photon and the target nucleon, and the mechanism of associated strangeness production in electromagnetic reactions. With the high-quality beam of the tagged and collimated linearly-polarized photons afforded by the Coherent Bremsstrahlung Facility (CBF) and the nearly complete angular coverage of the Hall-B spectrometer, we seek to extract the differential cross sections and polarization observables for the photoproduction of vector mesons and kaons at photon energies ranging between 1.10 and 2.20~GeV.
The first phase of the g8 run marked the commissioning of the CBF. It took place in the summer of 2001 (6/04/01 - 8/13/01) in Hall~B of Jefferson Lab and provided the Ph.D.~thesis work for two students~\cite{CGordon, JMelone} and the material for two Master's theses~\cite{APuga, JSalamanca}); g8b followed four years later culminating in four Ph.D~theses~\cite{Paterson-g8b, Collins-g8b, Salamanca-g8b, Hanretty-g8b} and one is on the way~\cite{Martinez-g8b}.
These experiments made use of a beam of linearly-polarized photons produced through coherent bremsstrahlung and marked the first time such a probe was employed at Jefferson Lab. The g8 set of experiments, therefore, was a vital first step in establishing the CBF and this experience paved the way for several subsequent successful runs with linearly polarized photons in Hall B of JLab: g13b ($\vec{\gamma}d$), and g9a/b ($\vec{\gamma}\vec{p}$). At the time of this writing, HDIce (g14) is poised to run; HDIce is a search for N*s using polarized photons directed onto a separably-polarizable proton and deuteron target and will be closing experiment for CLAS6. The lessons learned in calibration and cooking for the earlier g8 experiments have accelerated the analyses for the g13a/b, g9a, and presumably g14. Currently three students at ISU are playing key roles in calibrating detectors for g13 and will continue to give such assistance with g14. Danny Mart\'{i}nez, ($\vec{\gamma}p \rightarrow \omega p$ from g8b), and Olga Cort\'{e}s ($\vec{\gamma}n (p) \rightarrow \omega n (p)$) and Charles Taylor ($\vec{\gamma}n(p) \rightarrow K^{0}_{s}\Lambda (p)$ are analyzing g13 data).
Vector meson photoproduction at high energies, as is well known, proceeds primarily through pomeron exchange rather than by $\pi$ or $\eta$ meson exchange, which are respectively termed natural and unnatural parity exchange. In the baryon resonance energy regime ($E_{\vec{\gamma}}\sim 2.0$ GeV) and at low four-momentum transfer squared, $t$, the peak structure of the coherent $\phi$-meson photoproduction cross section is not well explained at threshold by a pure pomeron-exchange-based model~\cite{mibe}. The extraction of the Spin Density Matrix Elements (SDMEs) from $\phi$-meson decay angular distributions will shed light on the proportion of natural and unnatural parity exchange involved in the reaction mechanism~\cite{schilling} at low $t$, which is further to be compared to the predicted values of the Vector Dominance Model (VDM)~\cite{sakurai}.
In his Ph.D.~thesis~\cite{Salamanca-g8b}, Juli\'{a}n Salamanca, extracted over eight thousand $\phi$s mesons from the g8b data set at both low and high $t$ in the baryon resonance regime of $2.02 < \sqrt{s} < 2.11$ GeV. Extracting the SDMEs for the $\phi$ channel at high $|t|$ holds discovery potential for non-VDM mechanisms at higher four-momentum transfers squared. On the right hand side of Fig.~\ref{g8b-phi}, the fitted $\phi$-meson peaks are shown for two orientations of the polarization vector, $\vec{E}$. And on the left hand side are the respective angular distributions in the rest frame of the $\phi$ meson with the quantization axis pointing opposite the direction of the recoil proton, i.e.~the Helicity frame. Five SDMEs were extracted in this thesis work of Dr.~Salamanca. CLAS requires all analyses to be thoroughly reviewed by expert committee before a paper may be submitted. We have just answered the last few questions from the CLAS review committee. Once this $\phi$ analysis note is approved -- and that should be soon – we will prepare a paper for PRL or PRC on the extracted SDMEs from the photoproduction of $\phi$ mesons off protons with linearly-polarized photons.
\singlespace \begin{figure} [t] \begin{center} { \scalebox{0.5} [0.5]{\includegraphics{figs/Julian_NSF2011_1.eps}} \scalebox{0.5} [0.5]{\includegraphics{figs/Julian_NSF2011_2.eps}} } \caption{$\vec{\gamma} p \rightarrow \phi p$ and $1.7 < E_{\gamma} < 1.9$~GeV. Left side: $\phi$-meson distribution fit with a Breit-Wigner convoluted with a Gaussian peak ($\sigma \sim 11$~MeV) and a $2^{\rm nd}$-order polynomial background. Here, the direction of the polarization vector (($vec{E}$): {\sf (a-1)} Parallel and {\sf (a-2)} Perpendicular to the floor in the CLAS lab frame. Right side: Angular distributions of the $\phi$-meson in the Helicity frame. First (second) column is for $\vec{E}_{\parallel}$ ($\vec{E}_{\perp}$. Of especial interest are the angular distributions as a function of $\cos\theta_{Hel}$ showing the expected $\sin^{2}\theta_{Hel}$-like behavior and the modulation as a function of azimuthal ($\phi_{\rm Hel} - \Phi$) angle. Here, $\Phi$ denotes the direction of $\vec{E}$.} \label{g8b-phi} \end{center} \end{figure} \doublespace
\singlespace \begin{figure} [!hbp] \begin{center} { \scalebox{0.5} [0.5]{\includegraphics{figs/Omega-danny.eps}} } \caption{$\vec{\gamma} p \rightarrow \omega p$ and $\omega \rightarrow \pi^+ \pi^- \pi^0$. Plotted are the beam asymmetry parameters, $\Sigma$, for the three separate photon energies: {\sf (a)} $1.81 < E_{\vec{\gamma}} < 1.83$~GeV, {\sf (b)} $1.83 < E_{\vec{\gamma}} < 1.85$~GeV, and {\sf (c)}~$1.85 < E_{\vec{\gamma}} < 1.87$~GeV. For each $\cos\theta_{\rm cm}$ bin there are 18 $\phi$ bins from which $\Sigma$ is extracted. The solid squares correspond to the $\phi$ bin method from ISU and the closed correspond to method of moments from a separate analysis~\cite{Collins-g8b,dugger}. (d) $\omega$ meson signal: Voigtian (Breit Wigner + Gaussian) with a $4^{\rm th}$-degree polynomial for the background.} \label{g8b-omega} \end{center} \end{figure} \doublespace
The analysis of the photoproduction of $\omega$ mesons off hydrogen is an absolute must before this channel may be analyzed from neutrons in deuterium. Danny Mart\'{i}nez has made significant progress in extracting the Beam Asymmetry parameter $\Sigma$ by fitting the correctly normalized ratio of the yields $\frac{N_{\perp} - N_{\parallel}}{N_{\perp} + N_{\parallel}}$ to a $\cos{2\phi}$-like function for each $\cos{\theta}$ bin and $E_{\gamma}$ bin (see Fig.~\ref{g8b-omega})
This $\phi$ bin method compares well with the results from the method of moments~\cite{Collins-g8b,dugger}. The extracted $\Sigma$ will constrain combinations of the SDMEs. Further, this analysis on the proton will be the starting point for the photoproduction of omega mesons off neutrons, which will the Ph.D.~thesis work for Ms.~Cort\'{e}s.
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\medskip \begin{center} %\underline{\sf Tamuna's Exclusive Pion Production Comparison with Joo's et.~al.~ Publication} \underline{\sf Exclusive Pion Production} \end{center}
\singlespace \begin{figure} [!hbp] \begin{center} { \scalebox{0.5} [0.5]{\includegraphics[height=3.0in]{figs/Kinematics_single_pion_electroproduction_1.eps}} \scalebox{0.5} [0.5]{\includegraphics[height=4.0in]{figs/Phi_angle_in_CM_Frame_vs_Relative_Rate_cos_theta_0-4_0-6_W_1-45.eps}} } \caption{Left: An illustration of the kinematic quantities used to describe exclusive single pion production. Right: A comparison of the inclusive pion production measured using and $NH_3$ target to the published results from CLAS experiment E99-107 which used a liquid hydrogen target.} \label{TamunExcusivePionFig} \end{center} \end{figure} \doublespace
Figure~\ref{TamunExcusivePionFig} shows a comparison of the relative exclusive pion production ($\vec{e} p \rightarrow en\pi^+$) rates measured using a liquid hydrogen target in E99-107 to the measurements using a polarized ammonia ($NH_3$) target. The comparison was done as part of T. Didberidze's SIDIS analysis for the purpose of cross checking pion identification methods used in CLAS. The kinematics of single pion electroproduction can be described by five variables: the virtual photon negative four-momentum transferred squared $Q^2$, $W$ invariant mass of the photon-nucleon system, $\theta_{\pi}^*$ the polar and $\phi_{\pi}^*$ the azimuthal angle of the outgoing pion in center of mass frame and $\phi_e$ the scattered electron azimuthal angle. The five-fold differential cross section can be written in the following way for a single pion electroproduction:
\begin{equation} \frac{\partial^5 \sigma}{\partial E_f \partial \Omega_e \partial {\Omega_{\pi}}^*} = \frac{1}{2 \pi} \Sigma \frac{1}{L_{int} A_{cc} \epsilon_{CC} \Delta W \Delta Q^2 \Delta cos {\theta_{\pi}}^{\!*} \Delta {\phi_{\pi}}^{\!*}} \frac{d(W, Q^2)}{d(E_f, cos \theta_e)} \end{equation}
where $L_{int}$ represents the integrated luminosity, $A_{cc}$ is the acceptance factor, $\epsilon_{CC}$ represents the efficiency of the Cerenkov detector and the Jacobian term can be expressed in terms of the initial and final energy of lepton:
\begin{equation} \frac{d(W, Q^2)}{d(E_f, cos \theta_e)} = \frac{2 M_p E_i E_f}{W} \end{equation}
The E99-107 measurement shown in Figure~\ref{TamunExcusivePionFig} used the following kinematic cuts; $0.9 < M_x < 1.1$, invariant mass $1.44 < W < 1.46$ and $0.4 < cos\theta_{\pi}^{CM} < 0.6$. Despite the low statistics available for the kinematic region shared by both experiments, the rate dependence on $\phi_{\pi}^*$ that is reproduced using the NH3 target is an excellent cross check that increases confidence in the standard methods used by CLAS to identify the $\pi^+$.
- Reference
- Park, K., Burkert, V. D., & Kim, W. (The CLAS Collaboration). (2008). Cross sections and beam asymmetries for \vec{e} p->en\pi^+ in the nucleon resonance region for 1.7 < Q^2 < 4.5 (GeV)^2. Phys. Rev., C77, 015208.
Future Use of NSF Funds
Work Plan
\subsection{Future Use of NSF Funds}
\medskip \begin{center} \underline{\sf Work Plan} \end{center}
A timeline for the work undertaken to satisfy the objectives for the funding cycle of this proposal is shown in Table~\ref{table:Timeline}. The drift chamber construction for Hall~B is a critical component in support of the 12 GeV upgrade program at JLab and will support the ISU physics program. The Region~I tracking system is expected to be delivered to JLab during the summer of 2013. Graduate students will continue analyzing the g13 and g8 data sets for their Ph.D.~thesis. At least one Ph.D.~student will graduate during the proposed funding cycle. The group is looking to carve out a physics program beyond the 12~GeV program at JLab that can be directly associate with ISU. Two members of the group are involved in a JLab sponsored project to develop a polarized positron source for JLab. The development of a research program using a polarized positron source for experiments in Hall~B would be a natural direction to proceed and is currently under consideration. Less than 5\% of the group's workload would be spent investigating the physics opportunities of polarized positron beams.
\begin{table}[h]
\caption{Work Plan Timeline}
\begin{center}
\begin{tabular}{ll}
\multicolumn{1}{r}{Date}& \multicolumn{1}{c}{Objective}\\
\hline\hline 3/12 & Complete stringing and testing R1 Drift chamber \#2\\
8/12 & Complete stringing and testing R1 Drift chamber \#3\\
9/12 & Complete stringing and testing R1 Drift chamber \#4\\
2/13 & Complete stringing and testing R1 Drift chamber \#5\\
3/13 & Complete stringing and testing R1 Drift chamber \#6\\
5/13 & Ship drift chambers to Hall B at JLab \\
6/13 & Re-commission the Beowulf cluster \\
8/15 & At least one Ph.D.~graduate \\
8/12 - 7/15 & Continue the broader impact efforts for the Americas \\
\hline
\end{tabular}
\end{center}
\label{table:Timeline} \end{table}
\medskip
\begin{center}
\underline{\sf List of Currently supported students}
\end{center}
\begin{table}[h]
\caption{Currently supported students}
\begin{center}
\begin{tabular}{lll}
\multicolumn{1}{r}{Student}&
\multicolumn{1}{c}{Major (Year of Degree)}&
\multicolumn{1}{c}{Projected}\\
\hline\hline
Tamar Didberidze & Ph.D. & 2011 \\
Danny Mart\'{i}nez & Ph.D. & 2013 \\
Charles Taylor & Ph.D. & 2013 \\
Olga Cort\'{e}s & Ph.D. & 2015 \\
\hline
\end{tabular}
\end{center}
\label{table:Students} \end{table}
Student | Classification | Expected Grad Yr |
Tamar Didbarize | Ph.D. | 2011 |
Danny Mart\'{\i}nez | Ph.D. | 2013 |
Charles Taylor | Ph.D. | 2013 |
Olga Cort\'{e}s | Ph.D. | 2015 |
The Broader Impact of the Idaho State University Nuclear Physics Research Program
The Americas
\section{Broader Impact of the ISU Nuclear Physics Research Program} \label{section:BroaderImpacts}
\subsection{The Americas}
Our broader impacts activities are directed towards the Americas, particularly South America where we especially have good contacts. Over the past eleven years, two of the CoPIs have been active in outreach towards Latin America. CoPIs Dale and Cole can both communicate in Spanish. Speaking Spanish is necessary for our broader impacts activities. South American physics students tend to read English rather well, but speaking good English is entirely another matter. To attract students, one needs to present the many research opportunities in medium energy nuclear physics in the United States while dispelling subtle and not-so-subtle misconceptions, which unfortunately abound. And to communicate these matters effectively, one must speak Spanish at a reasonable level. We seek to promote dialog between faculty members of North-American and Latin-American institutions by finding common interests in research which will allow for coordinating our programs in nuclear physics research. Venues such as the Latin American Symposia on Nuclear Physics and Applications, which convene every two years in alternating countries in Latin America, offer great opportunities for strengthen existing links and forging new ones within the broad scope of the international nuclear physics community. Members of our group have attended every one of these biennial symposia since 1999 and CoPI Cole has been an editor twice on the proceedings and is on the standing organizational executive committee. In the six years that the ISU Physics Department has had a Ph.D., we have attracted four talented students from Colombia to Pocatello, Idaho. We are closing the loop and, in the process, we are strengthening our ties to Colombia. Dr.~Salamanca graduated in December, 2009, our first Ph.D.~in JLab physics at ISU. He recently became an Assistant Professor at Universidad Distrital in Bogot\'{a}, Colombia. We can only expect to draw more students to the ISU graduate physics program from this excellent connection.
\subsection{Graduate Student Training and Marketability}
The role graduate students play in the experiments which take place within our program provide them with marketable skills. In the past three years, the ISU group has graduate a Ph.D.~student and a Masters student. As mentioned in the previous section, Juli\'{a}n Salamanca graduated from ISU's program with a Ph.D.~thesis based on the CLAS and is now an Assistant Professor at Universidad Distrital in Bogot\'{a}, Colombia. Another student, Warren Parsons, graduated from ISU with a masters degree and is now employed in the technology sector. Both graduates have stated that the construction projects undertaken using the facilities at ISU were instrumental to their success after graduation. These two examples are not unique but rather representative of the well-rounded education students receive when doing research which combines projects at ISU and Jefferson Lab. We intend to continue using this bridge as a means to train students with marketable skills that increase their chances for success after graduation.
References Cited
\begin{thebibliography}{5} %1 \bibitem{RothNIM} Stephan A. Roth and Reinhard A. Schumacher, Nuclear Instruments and Methods in Physics Research A 369 (1996) 215-221 %2 \bibitem{Nstar-12GeV} {\it Nucleon Resonance Studies with CLAS12}, Jefferson Lab E12-09-003, V.D.~Burkert, P.L.~Cole, R.W.~Gothe, K.~Joo, V.I.~Mokeev, and P.~Stoler, cospokespersons. %3 \bibitem{Az09} I.G.~Aznauryan, V.D.~Burkert {\it et al.} (CLAS Collaboration), Phys.~Rev.~{\bf C80}, 055203 (2009). %4 \bibitem{Mo09} V.I.~Mokeev, V.D.~Burkert {\it et al.}, arXiv:0906.4081 %5 \bibitem{Wp09} Theory Support for the Excited Baryon Program at the Jlab 12 GeV Upgrade, JLAB-PHY-09-993, arXiv:0907.1901[nucl-th], [nucl-ex], [hep-lat]. %6 \bibitem{Gia08} E.~De Sanctis {\it et al.}, Phys.~Rev.~{\bf C76}, 062201 (2007). %7 \bibitem{Suz10} N.~Suzuki, T.~Sato, and T.-S.H.~Lee, Phys.~Rev.~{\bf C82} 045206 (2010). %8 \bibitem{Bh03} M.S.~Bhagwat {\it et al.}, Phys.~Rev.~{\bf C68}, 015203 (2003). %9 \bibitem{Bh06} M.S.~Bhagwat and P.C.Tandy, AIP Conf.~Proc.~{\bf 842}, 225 (2006). %10 \bibitem{Bow} P.O.~Bowman {\it et al.}, Phys.~Rev.~{\bf D71}, 015203 (2005). %11 \bibitem{book} See {\sl e.g.} Dynamics of the Standard Model, J.F. Donoghue, E. Golowich, and B.R. Holstein, Cambridge University Press (1992). %12 \bibitem{PDB} R.M. Barnett {\it et al.}, Review of Particle Physics, Phys. Rev. D {\bf 54},1 (1996). %13 \bibitem{Goity} J. L. Goity, A. M. Bernstein, J. F. Donoghue, and B. R. Holstein, manuscript in preparation; J. L. Goity, talk at Baryons 2002. %14 \bibitem{Ioffe07} B.L. Ioffe and A.G. Oganesian, Phys. Lett.~B {\bf 647}, 389 (2007). %15 \bibitem{primexIresult} I. Larin, D. McNulty {\it et al.}, A New Measurement of the $\pi^0$ Radiative Decay Width Phys. Rev. Lett. 106:162303, 2011 5pp. %16 \bibitem{Owens1990} R.O. Owens, Nucl. Instr. and Meth. A288 (1990) 574. %17 \bibitem{Cole94} {\it Photoproduction of $\rho$ Mesons from the Proton with Linearly Polarized Photons}, Jefferson Lab E-94-109, P.L.~Cole and K.~Livingston, co-spokespersons. %18 \bibitem{Ted98} {\it Photoproduction of $\phi$ Mesons with Linearly Polarized Photons, Jefferson Lab} E-98-109, D.J.~Tedeschi, P.L.~Cole, and J.A.~Mueller, co-spokespersons. %19 \bibitem{FKlein99} {\it Photoproduction of $\omega$ Mesons off Protons with Linearly Polarized Photons}, Jefferson Lab \mbox{E-99-013}, F.J.~Klein and P.L.~Cole, co-spokespersons. %20 \bibitem{Sanabria01} {\it Photoproduction of Associated Strangeness using a Linearly Polarized Beam of Photons}, CLAS Approved Analysis 2001, J.C.~Sanabria, J.~Kellie, and F.J.~Klein, co-spokespersons. %21 \bibitem{Pasyukg8} {\it Proposal for CLAS Approved Analysis (CAA) for Beam Asymmetry in $\eta^{\prime}$, $\pi^{\circ}p$, and $\pi^{+}n$ Photoproduction with g8b Data}, P.~Collins J.~Ball, M.~Dugger, E.~Pasyuk, B.G.~Ritchie, W.J.~Briscoe, I.I.~Strakovsky, and R.L.~Workman. Oct.~27, 2006. %22 \bibitem{g8papers} See: \underline{\sf http://www.jlab.org/exp\_prog/generated/apphallb.html} to view the above approved proposals in pdf and click on the experiment number (\mbox{E-94-109}, \mbox{E-98-109}, and/or \mbox{E-99-013}). These pdf files can also be found in: \underline{\sf http://www.physics.isu.edu/$\sim$cole/g8/experimental-proposals/}. %23 \bibitem{CGordon} Christopher Gordon, {\it $\rho^{\circ}$ Photoproduction using Linearly Polarised Photons with the CLAS Detector}, University of Glasgow, Ph.D.~Thesis, May 2004. %24 \bibitem{JMelone} Joseph Melone, {\it Measurement of the Photon Asymmetry for the $p(\vec{\gamma}K^{+})\Lambda$ Reaction at CLAS from 1.6 to 2.0~GeV}, University of Glasgow, Ph.D.~Thesis, Dec.~2004. %25 \bibitem{APuga} Alejandro Puga, {\it Calibration of the UTEP/Orsay Instrumented Collimator via the LabVIEW-based Data Acquisition System}, University of Texas at El Paso, Master's Thesis, Dec.~2001. %26 \bibitem{JSalamanca} Juli\'{a}n Salamanca, {\it C\'{a}lculo de la aceptancia del detector CLAS para la reacci\'{o}n $\vec{\gamma} p \rightarrow K \Lambda$}, Universidad de los Andes, Bogot\'{a}, Colombia; Master's Thesis: Dec.~2004. The PI was the external committee member and attended the defense in Bogot\'{a} in November, 2004. He also used this opportunity to recruit Mr.~Salamanca to Idaho State University. %27 \bibitem{Paterson-g8b} Craig Paterson, {\it Polarization Observables in Strangeness Photoproduction with CLAS at Jefferson Lab}, Ph.D.~Thesis, University of Glasgow, June~2008. %28 \bibitem{Collins-g8b} Patrick Collins, {\it Beam Asymmetry in Eta(547) and Eta(958) Meson Photoproduction off the Proton}, Ph.D.~Thesis, Arizona State University. Aug.~2009. %29 \bibitem{Salamanca-g8b} Juli\'{a}n Salamanca, {\it $\phi$-Meson Photoproduction with Linearly Polarized Photons at Threshold Energies}, Ph.D.~Thesis, Idaho State University, Dec.~2009. %30 \bibitem{Hanretty-g8b} Charles Hanretty, {\it Measurements of the Polarization Observables I$^{\rm S}$ and I$^{\rm c}$ for $\gamma p \rightarrow p \pi^{+}\pi^{-}$ using the CLAS Spectrometer}, Ph.D.~Thesis, Dec.~2010 %31 \bibitem{Martinez-g8b} Danny Mart\'{\i}nez, {\it Photoproduction of $\omega$-Mesons with Linearly Polarized Photons}, Ph.D.~Thesis, {\it in progress}. %32 \bibitem{mibe} T.~Mibe, {\it Measurement of $\phi$-meson photoproduction near production threshold with linearly polarized~photons}, Ph.D.~thesis, Osaka University, Japan (2004), {\it unpublished}. \\ T.~Mibe {\it et al.} Phys.~Rev.~Lett.~{\bf 95}, 182001 (2005). } %33 \bibitem{schilling} K.~Schilling, P.~Seyboth, and G.~Wolf, Nucl.~Phys.~B {\bf 15}, 397 (1970). %34 \bibitem{sakurai} J.J.~Sakurai, Ann.~Phys. {\bf 11}, 1 (1960). %35 \bibitem{dugger} M.~Dugger, B.G.~Ritchie, P.~Collins, and E.A.~Pasyuk, {\it Beam asymmetry extraction technique for g8b}, CLAS-NOTE 2008-35.
\end{thebibliography}
Budget Justification
File:2011budgetJustification.pdf
\doublespace \Large \centerline{Budget Justification} \normalsize \medskip
The four senior personnel on this project, Dr.~Phil Cole, Dr.~Dan Dale, Dr.~Tony Forest, and Dr.~Dustin McNulty each have established physics programs at Jefferson Lab (JLab) and will continue to pursue those endeavors using the support itemized in the budget. Nearly half of the budget for this proposal is devoted to supporting several graduate students currently pursuing their Ph.D.~degrees within the JLab research program. In addition, the budget accounts for two undergraduate students to be supported by this grant. Undergraduates supported in past years have made substantial contributions to the program while gaining research experience.
To greatly assist in the productivity of the proposed Hall~B, 6 and 12~GeV, research activities, the budget provides three years of funding to support a postdoctoral researcher stationed full-time at JLab. The postdoc is intended to help pave the way for the ISU group to transition electroproduction N* studies in CLAS6 to CLAS12. For additional information, please refer to the Mentoring Plan and the Letter of Support from the Hall-B group leader, Volker Burkert. The significance of the ISU group's involvement in the present and future Hall-B physics programs justifies the need for this expense which represents 22\% of the budget.
Our annual travel budget of \$30,000 is based primarily on the several collaboration meetings we will need to attend at JLab as well as the number of shifts we expect to take. The ISU group will be assigned 16~CLAS shifts for the first half of 2012 which requires at most 4~trips to JLab when the shifts are taken in blocks of 4. Our past experiences indicate that the costs of an individual trip to JLAB from Idaho range between \$1,200 and \$2,000 per trip. We estimate that we will spend approximately \$8,000 per year in order to absorb the market fluctuations as well as the probable increases in travel costs. Each PI expects to attend at least two collaboration meetings per year. The PIs have substantial roles in the CLAS, PRIMEX, Qweak, and MOLLER collaborations. We estimate a cost of \$16,000 for this travel. We also expect to present the results of our work at conferences each year and request \$6,000 to help defray those costs.
A shipping budget for \$100 is requested to support the exchange of materials between JLab and ISU as we continue construction of the RI tracking system for CLAS12. Our Laboratory for Detector Science expends on average \$2000 in consumables each year. We expect to upgrade or replace an average of 1 computer each year which is used for data acquisition or analysis at a cost of \$1000. We will also add to our data acquisition system by purchasing NIM/VME modules at a cost of \$3000. During the first year we plan on purchasing F1 TDCs for the purpose of measuring the performance of Drift Chambers developed as part of the CLAS 12~GeV upgrade. We plan on purchasing several more channels of leading edge discriminators, gate generators, and signal amplifiers in the final two years to increase the number of detector channels we are capable of measuring with our current CODA based DAQ system.
Facilities, Equipment, and Other Resources
File:2011facilitiesEquipmentOther.pdf
\doublespace \Large \centerline{Facilities, Equipment, and Other Resources} \normalsize \medskip
The Idaho State University Department of Physics Strategic Plan identifies the use of experimental nuclear physics techniques as its focus area to addressing problems in both fundamental and applied science. The major efforts of the department include fundamental nuclear and particle physics, nuclear reactor fuel cycle physics, nuclear non-proliferation and homeland security, accelerator applications, radiation effects in materials and devices, and biology. One of the key ingredients to the department's success has been the completion of the Idaho Accelerator Center (IAC) on April 30, 1999. A substantial amount of lab space (4000 sq.~ft.) within the department has become available due to a combination of the IAC and a remodeling of the physics building. A 400 sq.~ft., class 10,000 clean room has been constructed at ISU to build the Region I drift chambers for Hall~B's 12 GeV detector upgrade.
The PIs have created a Laboratory for Detector Science at Idaho State University which houses the groups infrastructure for detector development projects. The 1200 sq.~ft. Laboratory is equipped with flow hoods, a darkroom, and a laminar flow hood used to provide a clean room environment sufficient to construct small prototype detectors. A CODA based data acquisition system with ADC, TDC, and scaler VME modules has been installed to record detector performance measurements. The PIs also established a student machine shop containing a mill, a lathe, drill press, table saw, and band which occupies its own space for the physics department to share. These facilities has a history of being used to construct detectors, measure detector prototype performance, and design electronic circuits.
The Idaho Accelerator Center (IAC) is located less than a mile away from campus and will provide a machining facility for detector construction, an electronics shop for installation of instrumentation, and beamtime for detector performance studies. The IAC houses ten operating accelerators as well as a machine and electronics shop with a permanent staff of 8 Ph.D.s and 6 engineers. Among its many accelerator systems, the Center houses a Linac capable of delivering 20~ns to 2~$\mu$s electron pulses with an instantaneous current of 80 mA up to an energy of 25 MeV at pulse rates up to 1~kHz. The IAC and JLab are currently constructing an accelerator to test a candidate positron source system for JLab. A full description of the facility is available at the web site (www.iac.isu.edu).
A Beowulf Resource for Monte-Carlo Simulations (BREMS) was built for the ISU physics department which had 60 nodes and was a 64 bit system to support the high performance computing needs of the physics research program. The HVAC system for this facility has failed and is currently being reviewed to determine the best configuration to accommodate the cluster's cooling needs. The Beowulf cluster was investment made by NSF award PHYS-987453 which we plan on maintaining. We expect to complete a review of the cooling system and deploy a solution during this NSF award.
Mentoring Plan
\doublespace \Large \centerline{Postdoctoral Researcher Mentoring Plan} \normalsize \medskip
The intermediate energy nuclear physics group at Idaho State University is requesting three years in funding to support a postdoctoral researcher. The postdoctoral researcher will be stationed at Jefferson Lab and will conduct research on excited baryons from the CLAS6 dataset, which will set the stage for future CLAS12 analyses on extracting polarization observables in the $Q^{2}$ evolution of N*s in the transition regime from constituent to asymptotically-free quarks.
The postdoctoral researcher will experience, on a daily basis, the thriving and stimulating scientific atmosphere at Jefferson Lab, and meet and work with world-class nuclear physicists. The postdoctoral researcher will frequently and regularly communicate\footnote{See: letter of support from Hall-B Leader, Volker Burkert.} with Hall-B staff physicist, Dr.~Viktor Mokeev, and the primary adviser, CoPI Cole. Through these means, the postdoctoral researcher will gain the necessary professional experience and expertise for disseminating scientific results by participating and presenting in workshops and conferences and through publishing in conference proceedings and peer-reviewed journals. The postdoctoral researcher will be strongly encouraged to lead the effort in preparing a CLAS12 experimental proposal, which involves a thorough understanding of the science and expert knowledge of how to extract the observables from the detectors. Successfully conducting independent, but coordinated, research, presenting and publishing papers, and leading a CLAS12 research effort will serve the postdoctoral researcher well towards transitioning to a faculty position. It is the goal of the ISU group for the postdoctoral researcher to ultimately become an independent Jefferson Lab collaborator.
The PI and the three CoPIs have themselves been postdoctoral researchers at Jefferson Lab and each deeply appreciates the importance of good mentoring. Besides drawing from their collective personal experiences on best practices on mentoring the postdoctoral researcher, the ISU group will adhere to the three guiding principles delineated in the work: {\it Enhancing the Postdoctoral Experience for Scientists and Engineers: A Guide for Postdoctoral Scholars, Advisers, Institutions, Funding Organizations, and Disciplinary Societies}.\footnote{Reference: National Academy of Sciences, National Academy of Engineering, Institute of Medicine. 212pp (2000), \mbox{ISBN: 978-0-309-06996-0}.} These three principles are:
\begin{enumerate} \item The postdoctoral experience is first and foremost a period of apprenticeship for the purpose of gaining scientific, technical, and professional skills that advance the professional career.
\item Postdocs should receive appropriate recognition (including lead author credit) and compensation (including health insurance and other fringe benefits) for the contributions they make to the research enterprise.
\item To ensure that postdoctoral appointments are beneficial to all concerned, all parties to the appointments -- the postdoc, the postdoc adviser, the host institution, and funding organizations -- should have a clear and mutually-agreed-upon understanding with regard to the nature and purpose of the appointment.
\end{enumerate}
Data Management Plan
File:2011dataManagementPlan.pdf
\doublespace \Large \centerline{Data Management Plan} \normalsize \medskip
\begin{enumerate}
\item{Types of Data} \\
There are various types of data collected and/or generated during the course of experimental particle and nuclear physics research. These data are nearly exclusively produced electronically by Data Acquisition (DAQ) systems and computer programs and are digitally stored on a computer hard drive. The data are initially collected from various electronic devices, e.g. ADCs, TDCs, etc. which convert an electronic signal from an experimental detector or probe into a digitally store-able format. This initial data is referred to as “raw” data and is grouped into unique computer files which share common experimental conditions. These files typically have names which include a “run”-number indicating a chronological progression of collected data. Following the data collection, the raw data is calibrated, mathematically and statistically processed, and then saved into another computer file which also includes the run-number. The processed data is then typically further refined and consolidated to produce plots and/or numerical results which convey the outcome of the experiment. The format of the raw data is typically a custom file format generated by the DAQ system control software (such as CODA or MPANT). The desired data is extracted from the raw data using an “analyzer” C++ program which also processes and/or calibrates the data and typically stores it in a ROOT file (from a standard physics analysis software application called Root).
Along with the raw and processed data files there are typically other axillary data which are organized in a data base (almost exclusively a mySQL database). The database stores various types of data including calibration constants for the detector systems, translation maps to know which DAQ electronic signal pathways correspond to which detectors, and geometrical or spacial survey information indicating where in physical space the detector systems are located. These data are typically entered into the database automatically using C++/perl programs which are developed by members of the research group.
\item{Data and Metadata Standards} \\
The format of the raw data is documented in the DAQ control software documentation which could be a large formal document available online or could be a small simple file in the data repository named “README”. The ROOT file format is more customized to the particular experiment, but typically organizes the data into histograms and/or matrices called Trees or Ntuples. The format of the ROOT files are also documented in README files or simply detailed in a traditional or electronic logbook. As a general rule, the format of the above file types are designed to be consistent for all run-numbers of a given experiment. In addition, some raw data file formats such as those produced by MPANT include a header in the data file which defines the data columns and other information such as time-stamps, etc. However, the main source of information detailing the specific conditions during the run files is maintained and stored in a logbook.
\item{Policies for Access and Sharing and Provisions for Appropriate Protection/Privacy} \\
There are no patent issues bestowing a proprietary nature to the data collected during the outlined research projects, therefore, there are no restrictions to its access. The data will be freely available to other groups internal to Jefferson Lab (JLab) by simply accessing the data repository; to groups outside JLab, the data may be made freely available by verbal or written request. As with most fundamental physics research, groups outside the experiment collaboration may not publish any results without the permission of said collaboration. There are no ethical or privacy issues with any of the data.
\item{Policies and Provisions for Re-Use, Re-Distribution} \\
Since there are no patent issues which restrict access to the data, the data will be made freely available to all with no restrictions or provisions for re-use or re-distribution.
\item{Plans for Archiving and Preservation of Access} \\
The long term strategy for maintaining, curating and archiving the processed data is to store it on a UNIX computer system with a RAID 1 disk storage system which is regularly backed-up to an additional RAID 1 disk on a central server system maintained by the ISU physics department computer administrator. In addition, all raw data, processed root file data, database data, software codes and scripts, and webpage source code will be stored in a robotic tape mass storage system at JLab and will be preserved for a period not less than 20 years after the data was collected. There are no major transformations that are necessary for preparing the data for preservation or for sharing the data. However, any documentation that is not in electronic form will be scanned into a pdf document and stored alongside the data.
\end{enumerate}
--------------------------------------------------------------------------------------------
Previous Proposal
Q_{weak}
The $Q_{weak}$ experiment (E05-008), scheduled for installation in 2010, will use parity violating (PV) electron-proton scattering at very low momentum transfers $(Q^2 \sim 0.03~ \rm{GeV}^2)$ to measure the weak mixing angle $\sin^2(\theta_W)$. The dominant contribution to the PV asymmetry measured by $Q_{weak}$ is given by the weak charge of the proton, $Q_W^p = 1-4\sin ^2 \theta _W$, with small corrections of order $Q^4$ from nucleon electromagnetic form factors. This measurement will be a standard model test of the running of the electroweak coupling constant, sin$^2$($\theta_W$). Any significant deviation of $\sin ^2 \theta _W$ from the standard model prediction at low $Q^2$ would be a signal of new physics, whereas agreement would place new and significant constraints on possible standard model extensions including new physics. A brief description of the physics behind the $Q_{weak}$ experiment and the crucial contributions of this proposal to the $Q_{weak}$ experiment are given below.
An essential prediction of the Standard Model is the variation of $\sin ^2 \theta _W$ with $Q^2$, often referred to as the ``running of $\sin ^2 \theta _W$. Testing this prediction requires a set of precision measurements at a variety of $Q^2$ points, with sufficiently small and well understood theoretical uncertainties associated with the extraction of $\sin ^2 \theta _W$. It also requires a careful evaluation of the radiative corrections to $\sin ^2 \theta _W$ in the context of the renormalization group evolution (RGE) of the gauge couplings. Such tests have been crucial in establishing QCD as the correct theory of strong interactions<ref name="Hin00"> I. Hinchcliffe, Eur. Phys. J. {\bf C 15}, 85 (2000).</ref>~\cite{Hin00} . The RGE evolution of the QED coupling has also been demonstrated experimentally~\cite{TOP97,VEN98,OPAL00,L300}. The gauge coupling of the weak interaction, however, represented at low energies by the weak mixing angle $\sin ^2 \theta _W$, has not yet been studied successfully in this respect.
File:Qweak s2w Precision.eps
File:A-d Delta Prec.xfig.eps
\begin{figure}[htbp] %\vspace{-1in} \begin{center} { \scalebox{0.2} [0.2]{\includegraphics{Graphs/s2w_2004_4_new_2.eps}} \scalebox{0.25} [0.25]{\includegraphics{Graphs/A_d_Delta_Prec.xfig.eps}} } \caption{The dependence of $\sin^2 \theta_W$ as a function of $Q^2$ cast in the MS bar scheme of reference~\cite{Erler}. The solid line represents the Standard Model prediction. The results from four experiments (APV~\cite{APV<ref name="APV">}A. Derevianko { \it et al.}, Phys. Rev. Lett. {\bf 85}, 1618 (2000).</ref>, $Q_W(e)$~\cite{E158}, $\nu$-DIS~\cite{NuTeV}, Z-pole~\cite{Zpole} are shown together with the expected precision from the $Q_{weak}$ experiment (Q$_W(p)$~\cite{Qweak}. Expected precision of an inelastic asymmetry measured in one week using the Q$_{weak}$ apparatus compared with the expected asymmetry for several values of the low energy constant $d_{\Delta}$. The rectangular box indicates both the Q$^2$ bin and the asymmetry uncertainty.} \label{fig:PVAsym} \end{center} \end{figure}
Figure~\ref{fig:PVAsym} shows the Standard Model prediction in a particular scheme~\cite{QweakAp} for $\sin ^2 \theta _W$ versus $Q^2$ along with existing and proposed world data. As seen in this Figure, the very precise measurements near the $Z^0$ pole merely set the overall magnitude of the curve; to test its shape one needs precise off-peak measurements. Presently, there are only three off-peak measurements of $\sin ^2 \theta _W$ which test the running at a significant level: one from APV~\cite{APV}<ref name="APV"/>, one from high energy neutrino-nucleus scattering~\cite{NuTeV}, and the recently completed SLAC experiment E-158(Q$_w$(e))~\cite{E158}. The measurement of $Q_W^p$ described here will be performed with smaller statistical and systematic errors and has a much cleaner theoretical interpretation than existing low $Q^2$ data. In addition, this measurement resides in the semi-leptonic sector, and is therefore complimentary to experiment E-158 at SLAC, which resides in the pure leptonic sector and has determined $\sin ^2 \theta _W$ from PV $\vec e e$ (Moller) scattering to roughly a factor of two less precision at low $Q^2$~\cite{E158}. The total statistical and systematic error anticipated on $Q_W^p$ from these measurements is around 4\%~\cite{Qweak}, corresponding to an uncertainty in $\sin ^2 \theta _W$ of $\pm$0.0007. This would establish the difference in radiative corrections between $\sin ^2 \theta _W (Q^2 \approx 0)$ and $\sin ^2 \theta _W (M_Z )$ as a 10 standard deviation effect.
\medskip \begin{center} \underline{\sf ISU's role in $Q_{weak}$} \end{center}
PI Forest is currently the work package manager of the Region 1 detector and front end electronics for $Q_{weak}$. The Region 1 tracking system detectors are being assembled and will be tested by the end of 2008. This proposal will support the installation of a front end electronics system from CERN to digitize the analog output of the detectors. PI Forest has been using his startup funds to develop the infrastructure needed to implement this system in $Q_{weak}$. A critical milestone in the work plan, outlined in Table~\ref{table:Timeline}, will be the testing of the integrated tracking system during the summer of 2009 at JLab in preparation for the installation of the system in early 2010. Support from this proposal will be used to complete the front end electronics installation and maintain the Region 1 tracking system during the calibration phase of the $Q_{weak}$ experiment currently scheduled to begin installation in JLab's Hall C in early 2010.
In addition to providing a key component to the $Q_{weak}$ tracking system, PI Forest has also outlined a week long experiment to measure $d_{\Delta}$ using the $Q_{weak}$ apparatus~\cite{Qweak} to a statistical precision of less than 0.1 ppm as shown in Figure~\ref{fig:PVAsym}~\cite{LOIdDelta}. This low energy constant $d_{\Delta}$ was discovered while evaluating the radiative corrections for the PV $N\rightarrow \Delta$ transition~\cite{Zhu012}. The authors in Ref.~\cite{Zhu012} used Siegert's theorem to show the presence of a non-vanishing PV asymmetry at $Q^2=0$ which is proportional to $d_{\Delta}$. A measurement of the PV asymmetry in the $N\rightarrow \Delta$ transition at the photon point, or at very low $Q^2$ would provide a direct measurement of the low energy constant $d_{\Delta}$.
The low energy constant $d_{\Delta}$ is a fundamental constant which has implications to other long standing physics questions. The same PV electric dipole matrix element which results in $d_{\Delta}$ also drives the asymmetry parameter ($\alpha_{\gamma}$) in radiative hyperon decays, e.g. $\Sigma ^+ \rightarrow p\gamma$. Although Hara's theorem~\cite{Hara64} predicts that the asymmetry parameter ($\alpha_{\gamma}(\Sigma ^+ \rightarrow p\gamma$)) should vanish in the exact SU(3) limit, the Particle Data Group~\cite{PDGAlphaSigma} reports a measured value of $\alpha_{\gamma}(\Sigma ^+ \rightarrow p\gamma) = -$0.72$\pm$ 0.08. While typical SU(3) breaking effects are of order $(m_s - m_u )/1$GeV $\sim$ 15\%, the above asymmetry parameter is experimentally found to be more than four times larger. A solution proposed by the authors of Ref.~\cite{Bor99} involves including high mass intermediate state resonances $(1/2 ^- )$, where the weak Lagrangian allows the coupling of both the hyperon and daughter nucleon to the intermediate state resonances, driving the asymmetry parameter to large negative values. This same reaction mechanism was also shown to simultaneously reproduce the $s$- and $p$-wave amplitudes in non-leptonic hyperon decays, which has also been a long standing puzzle in hyperon decay physics. If the same underlying dynamics is present in the non-strange sector ($\Delta S = 0$) as in the strangeness changing sector ($\Delta S = 1$), one would expect $d_{\Delta}$ to be enhanced over its natural scale ($g_{\pi}$ = 3.8$\times 10^{-8}$, corresponding to the scale of charged current hadronic PV effects~\cite{Des80,Zhu00}). The authors of Ref.~\cite{Zhu012} estimate that this enhancement may be as large as a factor of 100, corresponding to an asymmetry of $\sim$ 4 ppm. This is comparable to the size of the effects due to the axial response and therefore easily measurable. Thus, a measurement of this quantity could provide a window into the underlying dynamics of the unexpectedly large QCD symmetry breaking effects seen in hyperon decays.
Vector Meson and Hyperon Photoproduction with Linearly Polarized Photons
The probe afforded by a beam of linearly-polarized photons allows one to gain access to several observables in photonucleon reactions, which otherwise would not be measurable. The polarization axis defines a unique direction in space whereby the angular distributions of the final-state particles can be uniquely referenced. The polarization axis of the photon beam breaks the azimuthal symmetry of the reaction, thereby introducing an azimuthal ($\Phi$) dependence to the differential cross section. This additional information on the angular dependence opens the door to the measurement of a host of observables which are accessible only with a beam of linearly-polarized photons; consequently it provides important constraints on the nature of the photon-nucleon reaction. Such polarization observables are necessary for extracting the spin/parity of the broadly overlapping baryon resonances and measuring such parameters over a large energy range with full angular coverage is crucial for disentangling such contributions. CoPI Cole is the contact person of the experiments which comprise the g8 run~\cite{Cole94,Ted98,FKlein99,Sanabria01,Pasyukg8,g8papers}. The scientific purpose of g8 is to improve the understanding of the underlying symmetry of the quark degrees of freedom in the nucleon, the nature of the parity exchange between the incident photon and the target nucleon, and the mechanism of associated strangeness production in electromagnetic reactions. With the high-quality beam of the tagged and collimated linearly-polarized photons and the nearly complete angular coverage of the Hall-B spectrometer, we seek to extract the differential cross sections and polarization observables for the photoproduction of vector mesons and kaons at photon energies ranging between 1.10 and 2.20~GeV.
In preparation for the g8a run, we commissioned the Coherent Bremsstrahlung Facility, which was essentially a new beamline in Hall B for producing a tagged and collimated beam of linearly polarized photons, where the mean polarization in the energy range of 1.8 to 2.2~GeV was 71\%. We enjoyed a reasonably successful two-month run for g8a, which so far, has culminated in two Ph.D. theses~\cite{CGordon, JMelone}, two master's theses~\cite{APuga, JSalamanca}, and one of the two NSF graduate research fellowships~\cite{RMammei} awarded in nuclear physics in 2003. We seek to build upon our earlier work and investigate the nature of resonant baryon states by probing protons with polarized photons. The set of experiments forming the first phase of the g8 run took place in the summer of 2001 (6/04/01 - 8/13/01) in Hall B of Jefferson Lab. These experiments made use of a beam of linearly-polarized photons produced through coherent bremsstrahlung and represents the first time such a probe was employed at Jefferson Lab. The second time this probe was used took place in the summer of 2005 (6/20/05 - 9/01/05) for the second phase of g8 (g8b), followed by g13b (3/08/07 - 6/29/07) and g9a (10/17/07 - 2/11/08). The g8 set of experiments, therefore, was a vital first step for establishing the Coherent Bremsstrahlung Facility and this experience paved the way for the successful runs with linearly polarized photons in Hall B of JLab: g13b ($\vec{\gamma}d$), and g9a ($\vec{\gamma}\vec{p}$). The lessons learned in calibration and cooking for g8b have accelerated the analyses for the g13a/b and g9a. And in the three years since the end of the g8b run, we have or are near completion of three Ph.D. theses: a) Craig Paterson~\cite{Paterson-g8b}, University of Glasgow, $\vec{\gamma}p \rightarrow K\Lambda, K\Sigma^{\circ}$, Aug.~2008), b) Patrick Collins~\cite{Collins-g8b}, Arizona State University, $ \vec{\gamma}p \rightarrow p\eta, p\eta^{\prime}$, Nov.~2008, and c) Juli\'{a}n Salamanca~\cite{Salamanca-g8b,LASNPA-7}, Idaho State University, $\vec{\gamma}p \rightarrow p\phi$, May~2009. \\
\noindent \underline{\bf Photoproduction of the $\phi(1020)$} \\ Vector meson photoproduction at high energies, as is well known, proceeds primarily through pomeron exchange rather than by $\pi$ or $\eta$ meson exchange, which are respectively termed natural and unnatural parity exchange. In the baryon resonance energy regime ($E_{\vec{\gamma}}\sim 2.0$ GeV) and at low four-momentum transfer squared, $t$, the peak structure of the coherent $\phi$-meson photoproduction cross section is not well explained at threshold by a pure pomeron-exchange-based model~\cite{mibe}. The extraction of the Spin Density Matrix Elements (SDMEs) from $\phi$-meson decay angular distributions will shed light on the proportion of natural and unnatural parity exchange involved in the reaction mechanism~\cite{shilling} at low $t$, which is further to be compared to the predicted values of the Vector Dominance Model (VDM)~\cite{sakurai}. We have several thousand $\phi$s mesons at both low and high $t$ in the baryon resonance regime of $2.02 < \sqrt{s} < 2.11$ GeV. With the exception of this g8 dataset, there are no photoproduced phi mesons with linearly polarized photons measured in the central region in the world data set. Extracting the SDMEs for the phi channel at high $|t|$ will therefore hold discovery potential for non-VDM mechanisms at higher four-momentum transfers squared. After making the necessary momentum, timing, particle ID, and Dalitz mass cuts we separate the data into unpolarized (AMO), perpendicular (PERP) polarization, and parallel (PARA) polarization. We fit a Breit-Wigner to the phi meson peak constrained with a decay width $\Gamma$ of 4.26~GeV with a second-order polynomial for fitting the background and a gaussian for representing the detector uncertainties. Below we display the phi peak obtained from extracting the $K^-$ from missing mass and then forming the invariant mass of the $K^+K^-$ separated in PERP and PARA orientations for the cms energy of $2.11 < \sqrt{s} < 2.20$~GeV.
\begin{figure}[h!] \begin{center} \includegraphics[height=.18\textheight]{Graphs/Cole_phi_mass_para_perp.eps} \caption{\small $K^+K^-$ invariant mass in the cms energy range of $2.11 < \sqrt{s} < 2.20$~GeV fit with a Breit-Wigner + Gaussian + 2nd order polynomial. The decay width is fixed at 4.26~GeV. (RHS) parallel (LHS) perpendicular polarizations.} \label{fig:phi_mass} \end{center} \end{figure} Below we plot the combination of parallel (PARA) and perpendicular (PERP) photoproduced phi mesons for all $t$ to obtain the photon beam asymmetry parameter: \\ %\begin{equation} $$\Sigma = (W^{PARA} - W^{PERP})/(W^{PERP} + W^{PARA}).$$ %\end{equation} These values are consistent with what we would expect from the Vector Dominance Model. We are presently working on separating the data into low- and high-$|t|$ regimes, but are not prepared to show it until we have authorization from the CLAS collaboration.
\begin{figure}[h!] \begin{center} \includegraphics[height=.18\textheight]{Graphs/Cole_asym_all.eps} \caption{\small Beam asymmetry for the phi meson channel over the full range of $t$ for (a) $1.9 < E_{\gamma} < 2.1$~GeV and (b) $1.7 < E_{\gamma} <1.9$~GeV. The photon beam polarization is 75\%.} \label{fig:asym} \end{center} \end{figure}
Primakoff
CoPI Dale is a spokesperson for the {\em PrimEx} Collaboration. At present, the scientific goal of the Collaboration is to perform a high precision measurement of the neutral pion lifetime as a test of the chiral anomaly in QCD, along with different approaches to corrections to the anomaly.
The two-photon decay mode of the $\pi^{0}$ reveals one of the most profound symmetry issues in quantum chromodynamics, namely, the explicit breaking of a classical symmetry by the quantum fluctuations of the quark fields coupling to a gauge field~\cite{book}. This phenomenon, called anomalous symmetry breaking, is of pure quantum mechanical origin. The axial anomaly of interest to us involves the corresponding coupling of the quarks to photons~\cite{anomaly}. In the limit of exact isospin symmetry, the $\pi^{o}$ couples only to the isotriplet axial-vector current $\bar{q}I_3\gamma_\mu \gamma_5 q$, where $q=(u,\; d)$, and $I_3$ is the third isospin generator. In the limit of two quark flavors, the electromagnetic current is given by $\bar{q}(1/6+ I_3/2)\gamma_\mu q$. When coupling to the photon, the isosinglet and isotriplet components of the electromagnetic current lead to an anomaly that explicitly breaks the symmetry associated with the axial-vector current
$\bar{q}\;I_3\;\gamma_\mu \gamma_5\;q$, and this in turn directly affects the coupling of the $\pi^{o}$ to two photons. The conservation of the axial U(1) current,
to which the $\eta'$ meson couples, as well as the $\bar{q} \frac{1}{2}\lambda_{8}\gamma_\mu \gamma_5 q$, to which the $\eta$ meson couples, are similarly affected by the electromagnetic field.
For vanishing quark masses, the anomaly leads to the predicted width of the $\pi^{o} \rightarrow \gamma \gamma$ decay: \begin{equation} \Gamma=M_{\pi}^{3}\frac{ \mid A_{\gamma \gamma} \mid^{2}}{64\pi}= 7.725 \pm 0.044 ~\rm{eV}, \end{equation} where the reduced amplitude is \begin{equation} A_{\gamma \gamma} =\frac{\alpha_{em}}{\pi F_{\pi}} = 2.513 \cdot 10^{-2} ~\rm{GeV}^{-1} \end{equation}
In this expression, there are no free parameters. Since the mass of the $\pi^0$ is the smallest in the hadron spectrum, higher order corrections to this prediction are small and can be calculated with sub-percent accuracy. The current experimental value is $7.84 \pm 0.56$ eV~\cite{PDB} and is in good agreement with the predicted value with the chiral limit amplitude. This number is an average of several experiments~\cite{PDB}. Even at the 7\% level quoted by the Particle Data Book~\cite{PDB}, the accuracy is not sufficient for a test of the new calculations which take the finite quark masses into account. The level of precision of $\simeq 1.4\%$, which is the goal of {\em PrimEx}, will satisfy these requirements. Stimulated by the {\em PrimEx} project, several new theoretical calculations have been published in recent years, and are shown in Figure~\ref{fig:theory}. The first two independent
calculations of the chiral corrections were performed in the
combined framework of chiral perturbation theory (ChPT) and the $1/N_c$ expansion up to ${\cal{O}}(p^6)$ and ${\cal{O}}(p^4\times 1/N_c)$ in the decay amplitude~\cite{Goity}~\cite{Mou02}. The $\eta'$ is explicitly included in the analysis as it plays as important a role as the $\eta$ in the mixing effects. It was found that the decay width is enhanced by about 4\% with respect to the value stated in equation (1). This enhancement is almost entirely due to the mixing effects. The result of this next-to-leading order analysis is $\Gamma_{\pi^0\to\gamma\gamma}=8.10~ {\rm eV}$ with an estimated uncertainty of less than 1\%. Another theoretical calculation based on QCD sum rules~\cite{Ioffe07}, also inspired by the {\em PrimEx} experiment, has recently been published with a theoretical uncertainty less than 1.5\%. Here, the only input parameter to the calculation is the $\eta$ width.
File:Pio width new theory prel result.eps
\begin{figure} \begin{center} %\begin{minipage}[t]{0.58\linewidth} \begin{minipage}[t]{0.38\linewidth} \scalebox{0.5} [0.55]{\includegraphics{Graphs/Pio_width_new_theory_prel_result.eps}} %\epsfig{file=Graphs/Pio_width_new_theory_prel_result.eps,width=\linewidth} \end{minipage}\hfill %\begin{minipage}[t]{0.38\linewidth} \begin{minipage}[t]{0.48\linewidth} \vspace*{-10cm}\caption{$\pi^{o} \rightarrow \gamma \gamma$ decay width in eV. The dashed horizontal line is the leading order prediction of the axial anomaly~\cite{book, anomaly}.The left hand side shaded band is the recent QCD sum rule prediction and the right hand side shaded band is the next-to-leading order chiral theory predictions. The experimental results with errors are for : (1)~the direct method~\cite{At85}; (2, 3, 4)~the Primakoff method~\cite{Br74,Bel70,Kr70}; (5)~the preliminary result from the first {\em PrimEx} data set; (6)~the expected error for the final goal of the {\em PrimEx} experiment, arbitrarily plotted to agree with the leading order prediction. prediction.\label{fig:theory}} \end{minipage} \label{fig:Primextheory} \end{center} \end{figure}
We are using quasi-monochromatic photons of energy 4.6-5.7~GeV from the Hall~B photon tagging facility to measure the absolute cross section of small angle $\pi^{o}$ photoproduction from the Coulomb field of complex nuclei. The invariant mass and angle of the pion are reconstructed by detecting the $\pi^{o}$ decay photons from the $\pi^{o} \rightarrow \gamma \gamma$ reaction.
For unpolarized photons, the Primakoff cross section is given by:
\begin{equation} \frac{d\sigma_P}{d\Omega}=\Gamma_{\gamma \gamma}\frac{8{\alpha}Z^2}{m^3}\frac{\beta^3{E^4}}{Q^4}|F_{e.m.}(Q)|^ 2 \sin^{2}\theta_{\pi} \end{equation}
\noindent where $\Gamma_{\gamma \gamma}$ is the pion decay width, $Z$ is the atomic number, $m$, $\beta$, $\theta_{\pi}$ are the mass, velocity and production angle of the pion, $E$ is the energy of incoming photon, $Q$ is the momentum transfer to the nucleus, and $F_{e.m.}(Q)$ is the nuclear electromagnetic form factor, corrected for final state interactions of the outgoing pion.
As the Primakoff effect is not the only mechanism for pion photoproduction at high energies, some care must be taken to isolate it from competing processes. In particular, the full cross section is given by:
\begin{equation} \frac{d\sigma}{d\Omega_{\pi}} = \frac{d \sigma_P}{d\Omega} + \frac{d\sigma_C}{d \Omega} + \frac{d \sigma_I}{d\Omega}+ 2 \cdot \sqrt{\frac{d\sigma_{P}}{d\Omega} \cdot \frac{d\sigma_{C}}{d\Omega}} cos(\phi_1 + \phi_2) \end{equation}
\noindent where the Primakoff cross section, $\frac{d \sigma_P}{d\Omega}$, is given by equation (4). The nuclear coherent cross section is given by: \begin{equation} \frac{d\sigma_C}{d \Omega} = C \cdot A^2 |F_N(Q)|^2 \sin^2\theta_{\pi} \end{equation} and the incoherent cross section is: \begin{equation}
\frac{d \sigma_I}{d\Omega}=\xi A (1-G(Q)) \frac{d
\sigma_H}{d\Omega} \end{equation} where $A$ is the nucleon number, $C \sin^2\theta_{\pi}$ is the square of the isospin and spin independent part of the neutral meson photoproduction amplitude on a single nucleon, $|F_N(Q)|$ is the form factor for the nuclear matter distribution in the nucleus, (corrected for final state interactions of the outgoing pion), $\xi$ is the absorption factor of the incoherently produced pions, $1-G(Q)$ is a factor which reduces the cross section at small momentum transfer due to the Pauli exclusion principle, and $\frac{d \sigma_H}{d\Omega}$ is the $\pi^o$ photoproduction cross section on a single nucleon. The relative phase between the Primakoff and nuclear coherent amplitudes without final state interactions is given by $\phi_1$, and the phase shift of the outgoing pion due to final state interactions is given by $\phi_2$.
The angular dependence of the Primakoff signal is different from the background processes, allowing $\Gamma(\pi^0\rightarrow \gamma\gamma)$ to be extracted from a fit to the angular distribution of photo-produced $\pi^0$. Measurements of the nuclear effects at larger angles are necessary to determine the unknown parameters in the production mechanism and thus make an empirical determination of the nuclear contribution in the Primakoff peak region. Consequently, this experiment uses a $\pi^{o}$ detector with good angular resolution to eliminate nuclear coherent production, and good energy resolution in the decay photon detection will enable an invariant mass cut to suppress multi-photon backgrounds.
%Image:Primex pb cross color.ps
%\begin{figure} %\centerline{\epsfxsize=200pt \epsfbox[200 150 430 500]{pb_cross_color.ps}} %\vspace{1cm} %\caption{Angular behavior of the electromagnetic and nuclear %$\pi^o$ photoproduction cross sections for %$^{208}$Pb in the 6.0~GeV energy range. } %\label{fig3} %\end{figure}
We submitted our first proposal (E-99-014) to PAC15 in December of 1998. It was approved by PAC15 and reconfirmed in jeopardy review later by PAC22 with an ``A rating. An NSF MRI proposal for \$970k was awarded (PIs: D.S.~ Dale, A.~Gasparian, R.~Miskimen, S.~Dangoulian) for the construction of a multichannel neutral pion calorimeter. This was successfully designed, constructed, and commissioned over the period 2000-2004. The first experiment on two targets ($^{12}$C and $^{208}$Pb) was performed in 2004. A second run (E-08-023, spokespersons: D.~Dale, A.~Gasparian, M.~Ito, R.~Miskimen) was approved by PAC33 with an $A-$ rating for 20 days of running to reach the proposed goal of $\sim 1.4\%$ accuracy. While the CoPI of this funding proposal has been involved in all aspects of this program, he has taken primary responsibility for the flux normalization. This has involved the design, construction, and commissioning of the {\em PrimEx} pair spectrometer. In addition, along with his students, he has been responsible for the analysis of the resulting data. This has also included a high precision measurement of the absolute cross section of a well known QED process, pair production, to verify that the flux determination was correct. %To date, the CoPI has supervised to completion one Ph.D. student (A. Teymurazyan) and one M.S. student on this work. One more Ph.D. student (O. Kosinov) is currently working toward his degree.
Prior and Future use of NSF Funds
File:BremFacility.epsFile:PairSpectrometer NSF08.epsFile:AssembledQweakDetector.eps
Prior use of NSF funds
\begin{figure}[htbp] %\vspace{-1in} \begin{center} { \scalebox{0.2} [0.4]{\includegraphics{Graphs/Cole_BremHist.eps}} \scalebox{0.25} [0.25]{\includegraphics{Graphs/DalePairSpect.eps}} \scalebox{0.15} [0.15]{\includegraphics[angle=90]{Graphs/QweakAssembledDetector.eps}} } \caption{The histograms show the improvement to Hall B's linearly polarized photon beam using the collimator designed and calibrated by CoPI Cole. The middle picture shows the pair spectrometer system installed in Hall B by CoPI Dale and his collaborators. The right most picture is of an assembled GEM detector for $Q_{weak}$'s Region 1 tracking system designed, machined and assembled by PI Forest and his students at ISU. } \label{fig:PriorNSFProducts} \end{center} \end{figure}
The PIs in this proposal have a strong record of receiving external funding from the NSF and a history of effectively using those funds to make substantially contributions to the infrastructure of the nuclear physics program described in this proposal, as summarized in Figure~\ref{fig:PriorNSFProducts}. The bremsstrahlung facility in JLab's Hall-B is one example of CoPI Cole's efforts to enhance the capabilities of Hall B's photon physics program. CoPI Dale has used NSF funds to install a pair spectrometer facility in Hall B. The Region 1 tracking system for $Q_{weak}$ was constructed by PI Forest using NSF funds.
Coherent Bremsstrahlung Facility
An instrumented collimator, having an aperture of 2.0 mm in diameter, is installed in the Hall-B beamline downstream of the tagger magnet and is located 22.9 m away from the diamond radiator. The collimator~\cite{collimator-cole}, designed and calibrated by CoPI Cole, forms part of the Coherent Bremstrahlung Facility; it serves to enhance the degree of linear polarization, $P$, within the coherent peak. As shown in Fig~\ref{fig:PriorNSFProducts}, the coherent distribution, peaked at 2.1~GeV, is considerably enhanced by tightly collimating the photon beam to one half of a characteristic angle. The spectra were taken with an electron beam energy of 4.5 GeV. Since the merit function %scales as $1/P_{\gamma}^2$ inversely scales with the photon poloarization squared, the collimation as shown in Figure~\ref{fig:PriorNSFProducts} enhances the quality of the polarization data by at least 30\%.
pair spectrometer
In 2000, an NSF MRI proposal (grant \# PHY-0079840) for \$970k was awarded (PIs: D.S.~Dale, A.~Gasparian, R.~Miskimen, S.~Dangoulian) for the construction of a multichannel neutral pion calorimeter, a pair spectrometer for flux monitoring, as well as a number of other pieces of experimental instrumentation for the {\em PrimEx} experiment. CoPI Dale was involved in all aspects of the experimental design and construction, and was the lead on the design, construction, and testing of the pair spectrometer. This pair spectrometer was successfully commissioned in 2002, and is now a part of the standard beamline instrumentation in Hall B.
Qweak Detector Construction
The design, construction, and testing of the Region 1 tracking system for the $Q_{weak}$ experiment at Jefferson Lab has been the main research activity supported by PI Forest's previous NSF grant. The $Q_{weak}$ Region 1 tracking system is one of three tracking systems designed to measure the $Q^2$ profile of elastically scattered electrons as well as background contributions to the parity violating signal~\cite{Qweak}. The Region 1 tracking system is located behind the first collimator at a distance of about 550 cm from the main torus magnet (200 cm from the target). The high radiation flux and the small detector footprint are two of the biggest challenges facing the Region 1 tracking system. As a result, an ionization chamber equipped with Gas Electron Multipliers (GEM) was chosen in order to accommodate the high radiation flux near the target. The GEM preamplifiers allow smaller ionization cell sizes thereby resulting in ionization chamber rise times of 50 nanoseconds or less. Figure~\ref{fig:PriorNSFProducts} below shows the custom designed GEM detector for the $Q_{weak}$ Region 1 tracking system. Engineers from the Idaho Accelerator Center (IAC) designed the GEM preamplifiers. This is a clear example of how the infrastructure at the IAC can be leveraged in support of our physics mission. The remaining detector design, machining, and assembly was completed using both graduate and undergraduate students.
Future Use of NSF funds
\begin{figure} [!hbp] \begin{center}{ \scalebox{0.25} [0.35]{\includegraphics{Graphs/deltad_CLAS12.eps}} \scalebox{0.2} [0.3]{\includegraphics{Graphs/p11_high.eps}} } \caption{ The left figure represents a comparison between the measurement to be made using an energy upgraded JLab with fits of the world data set for $\frac{\Delta d}{d}$. The expected data have been drawn along the pQCD and CQM prediction. The right figure represents the high $Q^2$ measurements that are possible after the upgrade to Hall B. Projected $N^*$ electrocoupling for the Roper $P_{11}(1440)$ as a function of $Q^{2}$ where the open circles with error bars are from our expected experiment~\cite{NSTAR12}, the closed squares are from the available CLAS data on single pion electroproduction~\cite{Aznauryan-2005}, and the solid blue squares are the preliminary data from analysis of e1-6 run overlaid with the results from the combined analysis of single and double pion electroproduction off protons~\cite{Aznauryan-2005-1}.} \label{fig:JLab12GeVPhysics} \end{center} \end{figure}
Work Plan
The work undertaken to satisfy the objectives for the funding cycle of this proposal involves the completion of the Region 1 tracking system for $Q_{weak}$ and the construction of drift chambers for the Hall B 12 GeV upgrade according to the milestones shown in Table~\ref{table:Timeline}. The construction of the $Q_{weak}$ Region 1 tracking system detector will be completed before the current NSF funding cycle expires. The R1 tracking system is expected to be delivered to JLab during the summer of 2009 and be integrated with other tracking system components to test the system before the scheduled installation in early 2010. PI Forest will play a critical role integrating the detector and front end electronics into the rest of the tracking system during the first few months of this proposal as well as during the installation and operation of the system in the two years that follow. During the same time frame, CoPIs Cole and Dale will be responsible for installing a clean room facility at ISU which will be used to construct drift chambers for JLab's Hall B starting in early 2010. The class-10,000 clean room for this project has been designed in collaboration with JLab's drift chamber management group and bids have been received. The drift chamber construction for Hall B is a critical component in support of the 12 GeV upgrade program at JLab and will support the ISU physics program.
\begin{table}[h]
\begin{center}
\begin{tabular}{ll}
\multicolumn{1}{r}{Date}&
\multicolumn{1}{c}{Objective}\\
\hline\hline
06/09 & Begin installing a clean room for constructing Hall B R1 Drift Chambers \\
& at the Idaho Accelerator Center \\
09/09 & Complete testing of the $Q_{weak}$ Region 1 tracking system at JLab \\ 01/10 & Begin Construction of R1 Chambers \\ 03/10 & Complete installation of $Q_{weak}$ Region 1 tracking system in JLab's Hall C \\ 06/10 & Quality Assurance Tests for the First R1 Drift Chambers \\ 10/12 & Install all R1 chambers in Hall-B \\ 08/09 - 07/11 & Continue efforts with the Americas \\ % & in Latin America through the Latin American Symposia for \\ % & Nuclear Physics and Applications and further recruit students \\ % & into areas of research involving JLab physics. \\ 08/09 - 07/11 & Analyze g8b and g13a/b data: omega and charged rho production. \\ \hline \end{tabular} \end{center} \caption{Work Plan Timeline} \label{table:Timeline} \end{table}
ISU's 12 GeV Physics Program
The ISU group is currently the spokespersons on two experiments proposed for a 12 GeV upgraded Hall B. The first experiment, PR12-06-109, will make measurements that contribute substantially to our knowledge of polarized parton distribution functions for all quark flavors and even the polarized gluon distribution $\Delta g$. One particular outcome, shown in Figure~\ref{fig:JLab12GeVPhysics}, will improve our ability to test the high-x prediction made by pQCD and the constituent quark model. While pQCD predicts that $\frac{\Delta d}{d}$ should go to unity at $x_{bjk} =1$, the constituent quark model, with hyperfine interactions, predicts a value closer to $-$1/3. A second component to ISU's 12 GeV program will seek to measure the exclusive single- and double-pion channels produced when 11-GeV electrons are directed onto a proton target with an upgraded CLAS detector. The goal will be to perform measurements of resonances, like the $P_{11}(1440)$ resonance shown in Figure~\ref{fig:JLab12GeVPhysics}, which will be used as input to models describing such transitions. The Excited Baryon Analysis Center (EBAC) at JLab is one such effort which will use an advanced coupled-channel approach in these fits. These studies will afford us the means to sample the transition from the hadronic to partonic regime.
List of Currently supported students
Student | Classification | Expected Grad Yr |
Julian Salamanca | Ph. D. | 2009 |
Tamar Didbarize | Ph. D. | 2010 |
Danny Martinez | Ph. D. | 2012 |
Oleksei Kosinov | Ph. D. | 2012 |
Adrianne Spilker | M.S. | 2009 |
Shadike Saitiniyazi | M.S. | 2009 |
Jordan Keough | BS | 2011 |
Nathan Lebaron | BS | 2012 |
==The Broader Impact of the Idaho State University Nuclear Physics Research Program}\label{section:BroaderImpacts} \subsection{The Americas}==
Our broader impacts activities are directed
towards the Americas, central and south.
Over the past nine years, the two CoPIs have
have been active in outreach towards Latin America.
CoPIs Dale and Cole can both communicate in Spanish. Indeed,
this past year CoPI Cole
successfully completed Spanish 201 and 202 at ISU, as a Freshman
with an undeclared major, and he is presently enrolled in an advanced
Spanish composition course at the 300-level in the effort to attain fluency.
Speaking Spanish is necessary for our broader impacts activities.
South American physics students tend to read English
rather well, but speaking good
English is entirely another matter. To attract students,
one needs to present the many
research opportunities in medium energy nuclear physics in the United States while
dispelling subtle and not-so-subtle misconceptions, which abound.
And to communicate these matters, it is imperative to speak good Spanish.
We seek to promote dialogue between faculty members of North-American and Latin-American institutions by finding common interests in research which will allow for coordinating our programs in nuclear physics research. Through this effort, we expect to strengthen existing links and forge new ones within the broad scope of the international nuclear physics community. CoPI Cole has been a PI four times and a CoPI twice on six separate Americas Program grants, which amounts in \$130k in funding.
\medskip \begin{center} \underline{\sf Funding History} \end{center}
\begin{itemize} \item The {\sf III Latin American Workshop on Nuclear and Heavy Ion Physics} (PI: Phil Cole) NSF-INT-9907453 for \$15,000
\item {\sf A Collaborative Effort between the U.S. and Colombia on the Physics with Linearly Polarized Photons}. (PI: Phil Cole) NSF-OISE-0101815 for \$32,590.
\item {\sf Americas Program: Student Sponsorship at the Fourth Latin American Symposium on Nuclear Physics, Mexico City, Mexico, September 24-28, 2001.} (PI: Phil Cole) NSF-OISE-0117545 for \$23,369
\item {\sf US-Brazil Student Sponsorship at the Fifth Latin American Symposium on Nuclear Physics; Santos, Brazil, September 1-5, 2003}
(PI: Phil Cole, CoPI Jorge Lopez) NSF-OISE-0313656 for \$18,000
\item {\sf U.S.-Argentina Collaborative Workshop in Nuclear Physics and Its Applications} (PI: Chaden Djalali, CoPI: Phil Cole) NSF-OISE-0527110 for \$32,200.
\item {\sf US-Peru Workshop in Nuclear Physics and Its Applications, June 11-16, 2007, Cusco, Peru} (PI: Chaden Djalali, CoPI: Phil Cole) NSF-OISE-0652360 for \$32,200. See: VII Latin American Symposium on Nuclear Physics and Applications, AIP Conference Proceedings 947 (2007), Editors: Ricardo Alarcon, Philip L.~Cole, Chaden Djalali, and Fernando Umeres.
\end{itemize}
Recent outcomes of our links with the Latin American community include Mr. Tulio Rodrigues' visit to Jefferson Lab in August 2004 to work with CoPI Dan Dale on theoretical calculations for the {\em PrimEx} experiment. At the time CoPI Dale was at the University of Kentucky. Mr.~Rodrigues was supervised by Dr.~Arruda-Neto, head of the Nuclear Reactions and Structure Research Group at the Physics Institute of the University of S\~{a}o Paulo and received his Ph.D. in 2006. Dr.~Rodrigues has visited ISU twice in the past two years to work on {\em PrimEx}-related physics. Another graduate student, Mr.~Vladimir Montealegre from the Universidad de los Andes in Bogot\'{a}, Colombia, entered the Ph.D. program at the University of South Carolina. Our recruitment efforts are paying off. Our group now has two strong Ph.D. students, Juli\'{a}n Salamaca and Danny Mart\'{\i}nez, from Colombia and upon processing the necessary paperwork, two more Ph.D. students from Colombia will join us in January, 2009.
\medskip
\begin{center}
\underline{\sf The Need}
\end{center}
Lack of modern equipment is one of the main obstacles to research in the less-developed Latin American countries. There is, however, considerable variation in the size and influence of the physics community by individual countries~\cite{MoranLopez}. A few groups have managed to pursue successful experimental programs in countries with comparatively long traditions in applied and basic research in the nuclear sciences; the chief examples being Argentina, Brazil, Chile, and Mexico, countries where research is fostered through collaborative efforts through annual national nuclear physics conferences. Two of these countries Brazil, site of the V LASNP, and Argentina, site of the VI LASNPA, have launched initiatives to construct large facilities allowing for their use by the wider international nuclear physics community: the Brazilian National Synchrotron Light Laboratory (LNLS) in Campinas (about 70 miles west of S\~{a}o Paulo) and the Tandar heavy ion accelerator in Buenos Aires, Argentina. Other countries in the region which have recently initiated activities aimed to improve their academic and scientific infrastructure in the nuclear sciences include Bolivia, Colombia, Peru and Venezuela.
\medskip \begin{center} \underline{\sf The Opportunity} \end{center}
There is ample room for collaborative overlap between the two hemispheres. Establishing links between the United States and Latin America will provide a means for recruiting high-caliber graduate-level students and post-doctoral fellows to pursue research at US institutions and laboratories such as JLab, RHIC, ORNL, RIA, and IAC. Such an academic relationship between North and South America will further strengthen the scientific endeavors of the nuclear physics communities of both continents. There is at present a dearth of graduate students pursuing advanced degrees in experimental and theoretical nuclear physics at US universities. This shortage is keenly felt at the national laboratories and facilities, where there is an abundance of Ph.D. theses topics and a paucity of graduate students. The goal is to build ties with faculty and students. While attracting students to US graduate programs, we also wish to build new groups and infrastructure in Latin America that would give the students an attractive career option in their home country after graduation.
%\newpage %\medskip \begin{center} \underline{\sf The Means and the Goals} \end{center}
We seek to grow these outreach efforts and our group will continue to write funding grants to the NSF Americas Program for sponsoring students to attend future interactions of the Latin American Symposium for Nuclear Physics and Applications. CoPI Cole was recently elected to the ten-member board International Organizing Committee of the VIII Latin American Symposium on Nuclear Physics and Applications to be held in Santiago, Chile, December 15-19, 2009. As in the past, the Committee's responsibilities include the scientific program, formation of an International Advisory Board, and some key aspects of the overall organization of the Symposium. Of this membership, three members are from Universities in the United States. With a colleague in Argentina, CoPI Cole further will write a grant to the International Atomic Energy Agency to help defray travel expenses for non-U.S.~students in Latin America, where typically funding from the NSF cannot be obtained.
\subsection{Graduate Student Training and Marketability}
\hspace{0.5in} The role graduate students play in the experiments which take place within our program provide them with marketable skill sets. Maria Novovic and Jena Kraft are clear examples of the impact members of this group have had training an underrepresented group in physics. Maria Novovic was trained in data acquisition, scintillator construction, and data analysis. She is currently a staff physicist at the University of Southern Alabama and is responsible for the undergraduate physics laboratories in addition to her undergraduate instructor role. The graduate training and experiences in PI Forest's lab were instrumental in securing her current position. Jena Kraft, who found a position in industry, reported that her design skills acquired while making a high pressure gas chamber for the GEM detector during her thesis were a key ingredient to her current position. The detector construction and instrumentation projects described in this proposal will continue to be effective in training graduate students for the market place. The Intermediate Energy Nuclear Physics Group at Idaho State University currently has three graduate students, listed in Table~\ref{table:Students}, working on JLab physics. Our expectation is that this number will increase with the addition of two faculty with JLab projects and the annual influx of more than 10 incoming graduate students per year.
Facilities
\hspace{0.5in}The Idaho State University Department of Physics Strategic Plan identifies the use of experimental nuclear physics techniques as its focus area to addressing problems in both fundamental and applied science. The major efforts of the department include fundamental nuclear and particle physics, nuclear reactor fuel cycle physics, nuclear non-proliferation and homeland security, accelerator applications, radiation effects in materials and devices, biology and health physics. Because of this focus, the department has been characterized as one of the largest nuclear physics graduate programs in the nation with an average of over 50 graduate students. One of the key ingredients to the department's success has been the completion of the Idaho Accelerator Center (IAC) on April 30, 1999. A substantial amount of lab space (4000 sq. ft.) within the department has become available due to a combination of the IAC and a remodeling of the physics building. A detector lab with the potential to construct proto-type drift chambers in a clean room environment is currently planned as part of the lab space renovation.
The Idaho Accelerator Center (IAC) is located less than a mile away from campus and will provide a machining facility for detector construction, an electronics shop for installation of instrumentation, and beam time for detector performance studies. The IAC houses ten operating accelerators as well as a machine and electronics shop with a permanent staff of 8 Ph.D.'s and 6 engineers. Among its many accelerator systems, the Center houses a Linac capable of delivering 20 ns to 2 $\mu$s electron pulses with an instantaneous current of 80 mA up to an energy of 25 MeV at pulse rates up to 1kHz. The IAC has donated beam time to the Q$_{weak}$ project for the purpose of testing detector performance. One of the goals of these tests will be to evaluate the Q$_{weak}$ detector at high rates. The IAC is well suited for these rate tests as the Q$_{weak}$ calibration rates will be much lower than the electron and photon rates the IAC is capable of generating. A full description of the facility is available at the web site (www.iac.isu.edu).
The Beowulf REsource for Monte-carlo Simulations (BREMS) is a 12 node, 64 bit cluster housed in the ISU physics department which can support the high performance computing needs of the physics research program. This facility is the result of an investment made by NSF award PHYS-987453. This infrastructure will be an effective means for performing GEANT4 simulations of the Q$_{weak}$ experiment as well as Garfield simulations of the Region II drift chamber design. Simulation speed is increased on BREMS by running the simulation in parallel on many CPUs. A version of GEANT4 known as ParGeant4~\cite{ParGeant4} has recently been distributed which will allow these simulations to be run in parallel.
The Broader Impact of the Idaho State University Nuclear Physics Research Program
The Americas
Our broader impacts activities are directed towards the Americas, cental and south. Over the past nine years, the two CoPIs have have been active in outreach towards Latin America. CoPIs Dale and Cole can both communicate in Spanish. Indeed, this past year CoPI Cole successfully completed Spanish 201 and 202 at ISU, as a Freshman with an undeclared major, and he is presently enrolled in an advanced Spanish composition course at the 300-level in the effort to attain fluency. Speaking Spanish is necessary for our broader impacts activities. South American physics students tend to read English rather well, but speaking good English is entirely another matter. To attract students, one needs to present the many research opportunities in medium nuclear physics the United States while dispelling subtle and not-so-suble misconceptions, which abound. And to communicate these matters, it is imperative to speak good Spanish.
We seek to promote dialogue between faculty members of North-American and Latin-American institutions by finding common interests in research which will allow for coordinating our programs in nuclear physics research. Through this effort, we expect to strengthen existing links and forge new ones within the broad scope of the international nuclear physics community. CoPI has been a PI four times and a CoPI twice on six separate Americas Program grants, which amounts in \$130k in funding.
\medskip \begin{center} \underline{\sf Funding History} \end{center}
\begin{itemize} \item The {\sf III Latin American Workshop on Nuclear and Heavy Ion Physics} (PI: Phil Cole) NSF-INT-9907453 for \$15,000
\item {\sf A Collaborative Effort between the U.S. and Colombia on the Physics with Linearly Polarized Photons}. (PI: Phil Cole) NSF-OISE-0101815 for \$32,590.
\item {\sf Americas Program: Student Sponsorship at the Fourth Latin American Symposium on Nuclear Physics, Mexico City, Mexico, September 24-28, 2001.} (PI: Phil Cole) NSF-OISE-0117545 for \$23,369
\item {\sf US-Brazil Student Sponsorship at the Fifth Latin American Symposium on Nuclear Physics; Santos, Brazil, September 1-5, 2003}
(PI: Phil Cole, CoPI Jorge Lopez) NSF-OISE-0313656 for \$18,000
\item {\sf U.S.-Argentina Collaborative Workshop in Nuclear Physics and Its Applications} (PI: Chaden Djalali, CoPI: Phil Cole) NSF-OISE-0527110 for \$32,200.
\item {\sf US-Peru Workshop in Nuclear Physics and Its Applications, June 11-16, 2007, Cusco, Peru} (PI: Chaden Djalali, CoPI: Phil Cole) NSF-OISE-0652360 for \$32,200. See: VII Latin American Symposium on Nuclear Physics and Applications, AIP Conference Proceedings 947 (2007), Editors: Ricardo Alarcon, Philip L.~Cole, Chaden Djalali, and Fernando Umeres.
\end{itemize}
Recent outcomes of our links with the Latin American community include Mr. Tulio Rodrigues visit to Jefferson Lab in August 2004 to work with Dr.~Dan Dale on theoretical calculations for the PrimEx experiment. At the time CoPI Dale was at the University of Kentucky. Mr.~Rodrigues was supervised by Dr.~Arruda-Neto, head of the Nuclear Reactions and Structure Research Group at the Physics Institute of the University of S\~{a}o Paulo and received his PhD in 2006. Dr.~Rodrigues has visited ISU twice in the past two years to work on PrimEx-related physics. Another graduate student, Mr.~Vladimir Montealegre from the Universidad de los Andes in Bogot\'{a}, Colombia, entered the PhD program at the University of South Carolina. Our recruitment efforts are paying off. Our group now has two strong PhD students, Juli\'{a}n Salamaca and Danny Mart\'{\i}nez, from Colombia and upon processing the necessary paperwork, two more PhD students from Colombia will join us in January, 2009.
\medskip
\begin{center}
\underline{\sf The Need}
\end{center}
Lack of modern equipment is one of the main obstacles to applied research in the less-developed Latin American countries. There is, however, considerable variation in the size and influence of the physics community by individual countries ~\cite{MoranLopez}. A few groups have managed to pursue successful experimental programs in countries with comparatively long tradition in applied and basic research in the nuclear sciences; the chief examples being Argentina, Brazil, Chile, and Mexico, countries, where research is fostered through collaborative efforts through annual national nuclear physics conferences. Two of these countries Brazil, site of the V LASNP, and Argentina, site of the VI LASNPA, have launched initiatives to construct large facilities allowing for its use by the wider international nuclear physics community: the Brazilian National Synchrotron Light Laboratory (LNLS) in Campinas (about 70 miles west of S\~{a}o Paulo) and the Tandar heavy ion accelerator in Buenos Aires, Argentina. Other countries in the region which have recently initiated activities aimed to improve their academic and scientific infrastructure in the nuclear sciences include Bolivia, Colombia, Peru and Venezuela.
\medskip \begin{center} \underline{\sf The Opportunity} \end{center}
There is ample room for collaborative overlap between the two hemispheres. Establishing links between the United States and Latin America will provide a means for recruiting high-caliber graduate-level students and post-doctoral fellows to pursue research at US institutions and laboratories such as JLab, RHIC, ORNL, RIA, and IAC. Such an academic relationship between North and South America will further strengthen the scientific endeavors of the nuclear physics communities of both continents. There is at present a dearth of graduate students pursuing advanced degrees in experimental and theoretical nuclear physics at US universities. This shortage is keenly felt at the national laboratories and facilities, where there are an abundance of PhD theses topics and a paucity of graduate students. The goal is to build ties with faculty and students. While attracting students to US graduate programs, we also wish to build new groups and infrastructure in Latin America that would give the students an attractive career option in their home country after graduation.
%\newpage \medskip \begin{center} \underline{\sf The Means and the Goals} \end{center}
We seek to grow these outreach efforts and our group will continue to write funding grants to the NSF Americas Program for sponsoring students to attend future interations of the Latin American Symposium for Nuclear Physics and Applications. CoPI Cole was recently elected to the ten-member board International Organizing Committee of the VIII Latin American Symposium on Nuclear Physics and Applications to be held in Santiago, Chile, December 15-19, 2009. As in the past, the Committee's responsibilities include the scientific program, formation of an International Advisory Board, and some key aspects of the overall organization of the Symposium. Of this membership, four members are from Universities in the United States. CoPI Cole further will write a grant to the International Atomic Energy Agency to help defray travel expenses for non-U.S.~students in Latin America, where typically funding from the NSF cannot apply.
Graduate Student Training and Marketability
hspace{0.5in} The role graduate students play in the experiments which take place within our program provide them with marketable skill set. Maria Novovic and Jena Kraft are clear example of the impact member of this group has had train ing an underrepresented goup in physics. Maria Novovic was trained in data acquisition, scintillator construction, and data analysis. She is currently a staff physicist at the University of Southern Alabama and is responsible for the undergraduate physics laboratories in addition to her undergraduate instructor role. The graduate training and experiences in Dr. Forest's lab were instrumental in securing her current position. Jena Kraft, who found a position in industry, reported that her design skills acquired while making a high pressure gas chamber for the GEM detector during her thesis were a key ingredient to her current position. The detector construction and instrumentation projects described in this proposal will continue to be effective in training graduate students for the market place. The Intermediate Energy Nuclear Physics Group at Idaho State University currently has three graduate students, listed in table~\ref{table:currentstudents}, working on JLAB physics. Our expectation is that this number will increase with this years addition of two faculty with JLAB projects and the annual influx of more than 10 incoming graduate students per year.
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``Photoproduction of Associated Strangeness using a Linearly Polarized
Beam of Photons, CLAS Approved Analysis 2001, J.C.~Sanabria, J.~Kellie, and F.J.~Klein, cospokespersons. \bibitem{Pasyukg8} ``Proposal for CLAS Approved Analysis (CAA) for Beam Asymmetry in $\eta^{\prime}$, $\pi^{\circ}p$, and $\pi^{+}n$ Photoproduction with g8b Data, P.~Collins J.~Ball, M.~Dugger,
E.~Pasyuk, B.G.~Ritchie, W.J.~Briscoe, I.I.~Strakovsky, and
R.L.~Workman. Oct.~27, 2006. \bibitem{g8papers} See: \underline{\sf http://www.jlab.org/exp\_prog/generated/apphallb.html} to view the above approved proposals in pdf and click on the experiment number (\mbox{E-94-109}, \mbox{E-98-109}, and/or \mbox{E-99-013}). These pdf files can also be found in: \underline{\sf http://www.physics.isu.edu/$\sim$cole/g8/experimental-proposals/}. \bibitem{CGordon} Christopher Gordon, ``$\rho^{\circ}$ Photoproduction using Linearly Polarised Photons with the CLAS Detector, University of Glasgow, Ph.D. Thesis, May 2004. \bibitem{JMelone} Joseph Melone, ``Measurement of the Photon Asymmetry for the $p(\vec{\gamma}K^{+})\Lambda$ Reaction at CLAS from 1.6 to 2.0~GeV, University of Glasgow, Ph.D. Thesis, Dec.~2004. \bibitem{APuga} Alejandro Puga, ``Calibration of the UTEP/Orsay Instrumented Collimator via the LabVIEW-based Data Acquisition System, University of Texas at El Paso, Master's Thesis, Dec.~2001. \bibitem{JSalamanca} Juli\'{a}n Salamanca, ``C\'{a}lculo de la aceptancia del detector CLAS para la reacci\'{o}n $\vec{\gamma} p \rightarrow K \Lambda$,
Universidad de los Andes, Bogot\'{a}, Colombia;
Master's Thesis: Dec.~2004. The PI was the external committee member and attended the defense in Bogot\'{a} in November, 2004. He also used this opportunity to recruit Mr.~Salamanca to Idaho State University. \bibitem{RMammei} Russell Mammei, NSF Graduate Research Fellowship, 2003. He worked on the calibration of the \mbox{Hall-B} instrumented collimator. Juliette Mammei, NSF Graduate Research Fellowship, 2003. She worked on the Hall-C 12 GeV upgrade. \bibitem{Paterson-g8b} Craig Paterson, ``Polarization Observables in Strangeness Photoproduction with CLAS at Jefferson Lab, Ph.D. thesis, University of Glasgow, Sept.~2008. \bibitem{Collins-g8b} Patrick Collins, ``Beam Asymmetry in Eta(547) and Eta(958) Meson Photoproduction off the Proton, Ph.D. thesis, Arizon State University. Nov.~2008. \bibitem{Salamanca-g8b} Julian Salamanca, ``$\phi$-Meson Photoproduction with Linearly Polarized Photons at Threshold Energies, Ph.D. thesis, Idaho State University, expected: May, 2009. \bibitem{LASNPA-7} Julian Salamanca, Philip L.~Cole, and the CLAS Collaboration, ``$\phi$-Meson Photoproduction with Linearly Polarized Photons at Threshold Energies, VII Latin American Symposium on Nuclear Physics and Applications, AIP Conf.~Proc.~947 (2007). \bibitem{mibe} {T.~Mibe, ``Measurement of $\phi$-meson photoproduction near production threshold with linearly polarized~photons, Ph.D.~thesis, Osaka University, Japan (2004), {\it unpublished}. \\
T.~Mibe {\it et al.} Phys.~Rev.~Lett.~{\bf 95}, 182001 (2005). }
\bibitem{shilling} K.~Schilling, P.~Seyboth, and G.~Wolf, Nucl.~Phys.~B {\bf{15}}, 397 (1970). \bibitem{sakurai} J.J.~Sakurai, Ann.~Phys. {\bf{11}}, 1 (1960). \bibitem{book} See {\sl e.g.} Dynamics of the Standard Model, J.F. Donoghue, E. Golowich, and B.R. Holstein, Cambridge University Press (1992). \bibitem{anomaly} J.S. Bell and R. Jaciw, Nuovo Cimento 60A, 47 (1969). S.L. Adler, Phys. Rev. 177, 2426 (1969). \bibitem{At85} H.W. Atherton {\it et al.}, Phys. Lett.~B {\bf 158} 81 (1985). \bibitem{Br74} A. Browman {\it et al.}, Phys. Rev. Lett. {\bf 33}, 1400 (1974). \bibitem{Bel70} G. Bellettini {\it et al.}, Il Nuovo Cimento, {\bf 66} , 243 (1970). \bibitem{Kr70} V.I. Kryshkin {\it et al.}, Sov. Phys. JETP, { \bf 30}, 1037 (1970). \bibitem{collimator-cole} P.L.~Cole, Design Note (1999) unpublished; A.~Puga, M.S.~thesis, University of Texas at El Paso (2001). The device was designed and constructed by IPN-Orsay and Univ.~of Texas at El Paso under grant NSF-PHY-9874653. \bibitem{NSTAR12} ``Nucleon Resonance Studies with CLAS12 in the Transition from Soft to Partonic Physics, Spokespersons: V.I.~Mokeev, R.W.~Gothe, V.D.~Burkert, P.L.~Cole, K.~Joo, and P.~Stoler. Proposal to be submitted in Jan.~2009. \bibitem{Aznauryan-2005} I.G.~Aznauryan {\it et al.}, Phys. Rev.~C {\bf 71}, 015201 (2005). \bibitem{Aznauryan-2005-1} I.G.~Aznauryan {\it et al.}, Phys. Rev.~C {\bf 72}, 045201 (2005). \bibitem{MoranLopez} Jose Luis Mor\'{a}n-L\'{o}pez, {\it Physics in Latin America Comes of Age}, Physics Today, Oct.~2000 Vol.~53, Number 10, online at \underline{http://www.aip.org/pt/vol-53/iss-10/p38.html}. \bibitem{PDB} R.M. Barnett {\it et al.}, Review of Particle Physics, Phys. Rev. D {\bf 54},1 (1996). \bibitem{Goity} J. L. Goity, A. M. Bernstein, J. F. Donoghue, and B. R. Holstein, manuscript in preparation; J. L. Goity, talk at Baryons 2002. \bibitem{Mou02}B. Ananthanarayan and B. Moussallam, preprint hep-ph/0205232. \bibitem{Ioffe07}B.L. Ioffe and A.G. Oganesian, Phys. Lett.~B {\bf 647}, 389 (2007).
\end{thebibliography}
Budget Justification
The three senior personnel on this project, Dr. Phil Cole, Dr. Dan Dale, and Dr. Tony Forest, each have established physics programs at Jefferson Lab and will continue to pursue those endeavors using the support itemized in the budget. Almost 40% of the budget in this proposal is devoted to supporting several graduate students currently pursuing their Ph. D. degrees within the JLab research program. Two undergraduate students will also continue to be supported by this grant. Undergraduates supported in past years have made substantial contributions to the program while gaining research experience. The support from this grant will be used to extend those experiences to include accelerator operations. We plan to use undergraduates as operators of the accelerators we will be using to provide ionizing radiation for testing the detectors we build.
Our travel budget is based on the number of shifts we expect to take at JLAB as well as several collaboration meetings we will need to attend. The ISU group was assigned 32 CLAS shifts in 2008 which requires at most 8 trips to JLab when the shifts are taken in blocks of 4. Our past experiences indicate that the costs of an individual trip to JLAB from Idaho range between $1,200 and $2,000 per trip. We estimate that we will spend approximately $16,000 per trip in order to absorb the market fluctuations as well as the probably increases in travel costs. Each PI expects to attend at least 3 collaboration meetings per year. The PI's have substantial roles in the Qweak, PRIMEX, and CLAS collaborations. We estimate a cost of $18,000 for this travel. We also expect to present the results of our work at conferences each year and request $4,000 to defray those costs.
A shipping budget for $100 is requested to support the exchange of materials between JLab and ISU as we move towards construction of the RI tracking system for CLAS12. Our Laboratory for Detector Science expends on average $3000 in consumables each year. We expect to upgrade or replace an average of 1 computer each year which is used for data acquisition or analysis at a cost of $2000. We will also add to our data acquisition system by purchasing a NIM/VME modules at a cost of $5000. During the first we plan to purchase two gate generators for digital signal generation and a VME module for producing LVDS signals. The LVDS signal module will be used to test the front end electronics of the Qweak Region 1 tracking system. In year two we plan on purchasing F1 TDC's for the purpose of measuring the performance of Drift Chambers developed as part of the CLAS 12 GeV upgrade. We plan on purchasing several more channels of leading edge discriminators and post amplifiers in the final year to increase the number of detector channels we are capable of measuring with out current CODA based DAQ system.
Project Summary
abstract: 1-2 paragraphs (max), describing research and broader impacts, on jargon or symbols (plain text), at the level of a NY Times science article
The focus of this grant goes towards supporting our continuing research program at the Thomas Jefferson National Accelerator Facility (JLab) using electromagnetic probes to study hadronic matter at the very fundamental and basic levels. Our group has taken crucial roles in three separate experiments that test the nature of particle interactions which falls under the rubric of the "Standard Model". One experiment, Qweak, uses the parity-violating property of the weak interaction to measure a fundamental parameter of the Standard Model known as the Weinberg (or mixing) angle to within a relative error of 0.3%. This angle is related to the ratio of two particle masses, the W and Z bosons, and varies as a function of the momentum transferred to the scattering target. A precise measurement from this experiment, when combined with other experiments, will place strong constraints on proposed extensions to our present version of the Standard Model. In another experiment, a member of our group leads the pion lifetime measurements undertaken in Jefferson Lab's Hall B which seeks to probe the mechanism through which a neutrally charged pion can decay into two photons. In this experiment, neutral pions will be photoproduced from the Coulomb field of nuclei via the Primakoff effect, and will be detected in a highly segmented calorimeter. The experiment measures a fundamental quantity which can be calculated in the context of chiral perturbation theory and represents one of the few stringent experimental tests of QCD that can be made in the confinement scale regime. Our group also conducts experiments to extract polarization observables from vector meson photoproduction with linearly-polarized photons in the g8b (proton) and g13a/b (deuteron) datasets, which is the subject of three ISU PhD theses. Recent CLAS results on the extraction of single- and double-polarization observables in photo- and electroproduction show their high sensitivity to small production amplitudes, which is key in extracting excited baryon state by affording an understanding of the underlying symmetry of the quark degrees of freedom in the nucleon, the nature of the parity exchange between the incident photon and the target nucleon, and the mechanism of associated strangeness production in electromagnetic reactions. As a natural extension to the JLab baryon resonance studies component, we expect to expand our research to the Beijing Electron Positron Collider, where we will extract excited baryons states decaying through charmed mesons at the Beijing Electron Spectrometer (BES). We seek to coordinate this research with BES by analyzing the decay of the J/psi into baryon-antibaryon channels, where we expect a complementary means for probing nucleon resonances (N*) in the mass region up to 2 GeV. Our group is planning to construct a set of six drift chambers to be used as the region 1 particle tracking system in Jefferson Lab's Hall B. This group's research program at JLab, the accelerator facilities at ISU, and continuous detector construction projects in the groups Laboratory for Detector Science, combine in an active program to provide a breadth of experiences in an educational environment which can be used to effectively train the next generation of scientists.
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