Difference between revisions of "2008 NSF Proposal"

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=Physics Program=
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[[ForestNSFInterimReport_8-31-10]]
  
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\hspace{0.5in}The <math>Q_{weak}</math> experiment and the measurement of
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[[ForestNSFInterimReport_8-31-11]]
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<math>A_1</math> at large<math> x</math> in Jefferson Lab's Hall B represent the
 
−
main components of the principal investigator's physics program.
 
−
Both components are the continuation of the PI's previous work
 
−
in parity violating electron scattering as a Ph.D. student and
 
−
polarized structure functions as a postdoctoral researcher
 
−
based at Jefferson Lab. 
 
−
While the main goal of the Q<math>_{weak}</math> experiment is to measure
 
−
the weak mixing angle sin<math>^2</math>(<math>\theta_W</math>), the PI has found an
 
−
opportunity to use the same apparatus to measure a new low energy
 
−
fundamental constant known as <math>d_{\Delta}</math> described below.  Such
 
−
an experiment using the Q<math>_{weak}</math> apparatus would require 1 week
 
−
to measure an inelastic parity-violating asymmetry which is an
 
−
order of magnitude larger than the Q<math>_{weak}</math> asymmetry.  While a
 
−
postdoctoral researcher based at Jefferson Lab, the
 
−
PI began developing a program to measure the
 
−
polarized to unpolarized down quark distribution (<math>\frac{\Delta d}{d}</math>) in the nucleon.  The program was recently awarded
 
−
80 days of beam time by Jefferson Lab's PAC 30.  Further details
 
−
of the physics program are given in the subsections below.
 
−
 
 
−
==Q$_{weak}$==
 
−
 
 
−
\hspace{0.5in}The Q$_{weak}$ experiment (E05-008) will use parity violating (PV)
 
−
electron-proton scattering
 
−
at very low momentum transfers $(Q^2 \sim 0.03$~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 at order $Q^4$ from nucleon
 
−
electromagnetic form factors.
 
−
This measurement will provide a precision
 
−
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. 
 
−
The experiment is considered a new initiative
 
−
for the future of Jefferson Lab, about which the JLab Program Advisory
 
−
Committee (PAC) wrote ``The PAC is very impressed with the
 
−
discovery potential
 
−
of this experiment and regards it as an important addition to the
 
−
Jefferson Lab program.''
 
−
The role of the principal investigator in this program is
 
−
described in section~\ref{section:QweakDetector}.  A brief
 
−
description of the physics is given below.
 
−
 
 
−
The PV asymmetry measured by inclusive electron scattering
 
−
reactions is driven by the exchange of a neutral weak Z$^0$
 
−
boson.  The asymmetry is amplified by the interference between
 
−
the weak and electromagnetic interactions, a feature that has been
 
−
exploited as a means for
 
−
determining the strange quark contribution
 
−
to ground state nucleon properties~\cite{Be01}. 
 
−
The asymmetry may be expressed as
 
−
\begin{eqnarray}
 
−
A ~=~ {{\sigma _+ -\sigma _-}\over{\sigma _+ + \sigma _-}}~=~{{G_F}\over{\sqrt{2}}}{{Q^2}\over{\pi \alpha}}{{1}\over{\sigma _p}}\{ \varepsilon G^{\gamma}_{E}
 
−
G^{Z}_{E} + \tau G^{\gamma}_{M} G^{Z}_{M} - {{1}\over{2}}(1-4\sin ^2 \theta _W )\varepsilon ^{\prime}
 
−
G^{\gamma}_{M} G^{Z}_{A}\}~\cite{ReyaSchilcher74},
 
−
\label{eq:PVelasticAsym}
 
−
\end{eqnarray}
 
−
where $\sigma _+(\sigma_-)$ is the cross section for the elastic
 
−
scattering of electrons of positive (negative)
 
−
helicity, $\tau$, $\varepsilon$, and $\varepsilon ^{\prime}$ are
 
−
kinematic factors depending on
 
−
$Q^2$,
 
−
$M$ is the mass of the proton, $G_F$ is the Fermi coupling
 
−
constant, $\alpha$ is the electromagnetic
 
−
coupling constant, $Q^2$ is the square of the four momentum
 
−
transfer, $\sin ^2 \theta _W$ is the weak
 
−
mixing angle, $\theta _e$ is the electron laboratory scattering
 
−
angle, and $\sigma _p$
 
−
is the Mott cross section.  The Sachs electromagnetic and
 
−
neutral weak electric and magnetic form factors <math>$G^{\gamma ,Z}_{E}$</math> and <math>$G^{\gamma ,Z}_{M}$</math>, respectively,
 
−
as well as the nucleon axial vector form factor $G^{Z}_{A}$, can
 
−
each be expressed in terms
 
−
of individual quark distribution functions. A system of
 
−
equations is constructed within this framework which describes
 
−
the extraction of
 
−
the strange quark contribution to the electric and magnetic form
 
−
factors of the nucleon,
 
−
$G^{s}_{E}$ and $G^{s}_{M}$,
 
−
as well as the axial form factor $G_A^Z$~\cite{Kap88} from the
 
−
asymmetry measurements made.
 
−
 
 
−
 
 
−
The limit $\theta
 
−
\rightarrow 0$, $\epsilon \rightarrow 1$, 
 
−
and $\tau \ll 1$, in Eq.~\ref{eq:PVelasticAsym} is taken in order
 
−
to see how a measurement of the PV asymmetry in elastic 
 
−
electron-proton
 
−
scattering at very low $Q^2$ and very small electron scattering
 
−
angles can be used to test the
 
−
Standard Model.
 
−
The resulting asymmetry becomes:
 
−
\begin{eqnarray}
 
−
A = -{{G_F}\over{4\pi \alpha \sqrt{2}}}[Q^2 Q_W^p + F^p (Q^2 ,\theta )] \rightarrow
 
−
-{{G_F}\over{4\pi \alpha \sqrt{2}}}[Q^2 Q_W^p + Q^4 B(Q^2 )],
 
−
\end{eqnarray}
 
−
where $F^p$ is a form factor. Neglecting radiative corrections,
 
−
the leading term in this equation
 
−
is simply $Q_W^p = 1-4\sin ^2 \theta _W$. The $B(Q^2 )$ is the
 
−
leading term in the nucleon
 
−
structure defined in terms of neutron and proton electromagnetic
 
−
and weak form factors.
 
−
The contributions contained in $B(Q^2 )$
 
−
(which enters to order $Q^4$)
 
−
can be reduced by going to lower $Q^2$ values; however, this also
 
−
reduces the sensitivity
 
−
to $Q_W^p$ (which enters to leading order in $Q^2$) making it
 
−
statistically more difficult
 
−
to measure.
 
−
The value of $B(Q^2 )$ can be determined
 
−
experimentally by extrapolating measurements made by
 
−
the ongoing program of forward angle PV experiments at higher
 
−
$Q^2$~\cite{HAPEX,G0,A4}.
 
−
The optimum value of $Q^2$ to minimize hadron structure
 
−
uncertainties and at the same
 
−
time maximize our sensitivity to $Q_W^p$ is estimated to be near
 
−
$Q^2 = 0.03$~(GeV/c)$^2$ 
 
−
\cite{Qweak}.
 
−
 
 
−
\begin{figure}[htbp]
 
−
%\vspace{-1in}
 
−
\centerline{
 
−
\scalebox{0.5} [0.5]{\includegraphics{Graphs/s2w_2004_4_new_2.eps}}}
 
−
\caption{The dependence of $\sin^2 \theta_W$ as a function of
 
−
$Q^2$ cast in the MS bar scheme by reference~\cite{Erler}.  The
 
−
solid line represents the Standard Model prediction.
 
−
The results from three experiments
 
−
(APV~\cite{APV}, $Q_W(e)$~\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}. }
 
−
\label{fig:newphysics}
 
−
\end{figure}
 
−
 
 
−
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 \cite{Hin00},
 
−
and 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.
 
−
 
 
−
Shown in Fig.~\ref{fig:newphysics} is 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. To date, 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}, 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
 
−
has determined $\sin ^2 \theta _W$ from PV $\vec e e$ (Moller) scattering (which
 
−
resides in the pure leptonic sector) 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, and 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.
 
−
 
 
−
==Measuring $d_{\Delta}$ using the PV $N\rightarrow \Delta$ Transition  at Low $Q^2$ ==
 
−
 
 
−
Interest in inelastic PV physics has been bolstered by the
 
−
discovery of a
 
−
new
 
−
radiative correction for the PV $N\rightarrow
 
−
\Delta$ transition~\cite{Zhu012} resulting in a $Q^2$
 
−
independent asymmetry 
 
−
that does not contribute to elastic PV electron scattering.
 
−
The result is a non-vanishing PV asymmetry at $Q^2 = 0$ .
 
−
The new correction is the result of a photon coupling to a PV
 
−
hadron vertex and is referred to as the so called ``anapole''
 
−
contribution  which has no analog in the elastic channel.
 
−
The authors in Ref.~\cite{Zhu012} use Siegert's
 
−
theorem to show that the
 
−
$Q^2$ independence is the result of a cancellation of the 1/$Q^2$ term
 
−
from the photon propagator and the leading $Q^2$ dependence from
 
−
the anapole term.
 
−
The leading component from the contribution of this transition amplitude
 
−
is proportional to $\omega ~(\omega = E_f -E_i )$
 
−
times the PV electric dipole matrix element and is characterized
 
−
by a low energy constant $d_{\Delta}$.  A measurement of the PV
 
−
asymmetry in the $N\rightarrow \Delta$ transition at the photon point,
 
−
or at very low $Q^2$, henceforth called the Siegert contribution,
 
−
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 Reference\cite{Zhu012} estimate that this enhancement may
 
−
be as large as a factor of 100, corresponding to an asymmetry of
 
−
$\sim$ 4 ppm, 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.
 
−
 
 
−
The PI submitted a Letter of Intent
 
−
(LOI-03-105) to JLab PAC24 which outlined an experiment to measure $d_{\Delta}$ using the
 
−
$Q_{weak}$ apparatus \cite{Qweak}.
 
−
As shown in Figure~\ref{fig:N2Delta_Asym}, a statistical precision of $<$ 0.1 ppm can be achieved at a $Q^2$
 
−
value of 0.028 GeV$^2$ in less than a week.
 
−
The favorable reviews received have encouraged the PI to submit
 
−
a full proposal once
 
−
the Q$_{weak}$ run schedule has become firm.
 
−
 
 
−
 
 
−
\begin{figure}[htbp]
 
−
\begin{center}{
 
−
%\scalebox{0.4}[0.3]{\rotatebox{-90}{\includegraphics{Graphs/N2Delta_Asym.eps}}}
 
−
\scalebox{0.4} [0.4]{\includegraphics{Graphs/A_d_Delta_Prec.xfig.eps}}
 
−
}
 
−
\caption{Expected precision of the measured asymmetry 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:N2Delta_Asym}
 
−
\end{center}
 
−
\end{figure}
 
−
 
 
−
 
 
−
== The Longitudinal Spin Structure of the Nucleon==
 
−
 
 
−
\hspace{0.5in}Spin structure functions of the nucleon have been measured in deep inelastic (DIS)
 
−
lepton scattering for nearly 30 years since the first
 
−
experiments at SLAC.  Interest increased substantially in the 80's when
 
−
the EMC collaboration reported that the
 
−
quark helicities 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
 
−
Jefferson Lab.
 
−
As of today, the data
 
−
indicate that between 25\% - 35\% of the nucleon spin is carried
 
−
by the quark spins, with the remainder
 
−
being attributed to gluon polarization and orbital angular
 
−
momentum. The world data set however, has yet to resolve
 
−
whether the three valence quark spins ($uud$ in the
 
−
proton) follow the ``naive'' expectation
 
−
of relativistic quark models that 60\% -- 70\% of the nucleon spin
 
−
carried by quark helicities.
 
−
 
 
−
The interest in this field continues unabated as new experiments
 
−
(COMPASS
 
−
%~\cite{COMPASS}
 
−
at CERN 
 
−
and the nucleon spin program at RHIC
 
−
%~\cite{RHIC}
 
−
) are attempting to measure
 
−
the low-$x$ gluon and sea quark
 
−
polarization in a polarized nucleon with high precision. At large-$x$, 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. Examples of these results
 
−
are shown in Fig.~\ref{delqJLab}.
 
−
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.
 
−
 
 
−
\begin{figure} [!hbp]
 
−
\begin{center}{
 
−
\scalebox{0.4} [0.5]{\includegraphics{Graphs/delq_new1.eps}}
 
−
\scalebox{0.4} [0.5]{\includegraphics{Graphs/deltad_CLAS12.eps}}
 
−
}
 
−
\caption{The polarized to unpolarized up and down quark
 
−
distribution ratio. The left figure shows the results
 
−
from recent JLab experiments on the virtual photon asymmetry $A_1$ for
 
−
the proton, Deuteron~\cite{EG2DeltaD} and neutron
 
−
($^3$He)~\cite{HallADeltaD}.  The right figure represents the
 
−
proposed measurements.  The expected data have been draw along
 
−
the pQCD and CQM prediction. }
 
−
\label{delqJLab}
 
−
\end{center}
 
−
\end{figure}
 
−
 
 
−
 
 
−
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.
 
−
In addition, semi-inclusive DIS (SIDIS)
 
−
data will also be collected, where in addition
 
−
to the scattered electron we will detect some of the leading
 
−
hadrons produced when
 
−
the struck quark hadronizes. These data will further constrain
 
−
the NLO fits and improve the
 
−
separation of the various quark flavors' contribution to the nucleon spin.
 
−
 
 
−
 
 
−
 
 
−
==Detector Development==\label{section:QweakDetector}
 
−
 
 
−
 
 
−
 
 
−
 
 
−
\hspace{0.5in}Support from this proposal will be used to
 
−
develop the Region 1 Tracking system for the Q$_{weak}$ experiment
 
−
at Jefferson Lab.  Dr. Forest was
 
−
awarded a grant under the Major
 
−
Research Instrumentation (MRI) program ( Proposal \#PHYS-0321197)
 
−
to develop this tracking system. 
 
−
A prototype detector and a
 
−
detector positioning system have already been built using support
 
−
from a previous NSF grant in combination with the instrumentation
 
−
support from the MRI grant.
 
−
As a result of this work, the final design has been completed
 
−
which will
 
−
construct ionization chambers
 
−
equipped
 
−
with Gas Electron Multipliers (GEM)~\cite{Sauli}
 
−
as the first tracking
 
−
element in the Qweak tracking system.  The use of GEM
 
−
preamplifiers increases the rate capabilities of the chambers
 
−
allowing them to be used close to the target.  As
 
−
work package manager of the Region 1 tracking system, Dr. Forest
 
−
is responsible for the construction, testing and installation of
 
−
this tracking system.
 
−
 
 
−
A prototype detector was built and calibrated by Dr. Forest
 
−
and his physics student Jeremy Dobbins in
 
−
early 2004.  The detector, shown in
 
−
Figure~\ref{fig:QweakProducts} was a 2cm thick ionization chamber
 
−
equipped with three gas electron multiplier preamplification
 
−
stages~\cite{Sauli} and having an active area of 10cm x 10cm.
 
−
The  detector gain of 10$^5$ and a response uniformity
 
−
less than 1\% was observed which is consistent with the findings
 
−
of other groups.  The detectors output signal was observed to have
 
−
a 25ns rise time making it ideal for use in the high rate
 
−
environment expected in the Q$_{weak}$ experiment.  The effect of
 
−
gas pressure on the detector's gain
 
−
and quantum efficiency was then quantified by Louisiana Tech graduate
 
−
student Jena Kraft in her
 
−
M.S. physics thesis of Nov. 2004.  It was discovered during
 
−
operation of the first prototype that the wire bonds used to
 
−
connect the charge collection strips to 24 pin output connectors
 
−
were unreliable and too fragile.
 
−
As a result, the detector was redesigned to eliminate the need
 
−
for these wire bonds.
 
−
Preliminary testing of the new design has shown no degradation of
 
−
detector performance.
 
−
 
 
−
\begin{figure}[htbp]
 
−
\centerline{
 
−
\scalebox{0.3} [0.49]{\rotatebox{0}{\includegraphics{Graphs/Glue2DchargeCollectr_1stPrototype.eps}}}
 
−
\scalebox{0.7} [0.7]{\rotatebox{0}{\includegraphics{Graphs/QweakRotatorPicture.eps}}}
 
−
}
 
−
\caption{A prototype Region 1 ionization chamber (left) and the support
 
−
structure (right) to be used to position the tracking system for
 
−
Qweak.  The left image shows an ionization chamber and
 
−
readout board only.  Rows of black 20 pin connectors are now wave
 
−
soldered directly to the readout board replacing fragile wire
 
−
bonds used previously.  The right image shows the detector
 
−
rotation system composed of a main aluminum rotation ring upon
 
−
which two liner bi-slide systems are mounted.  A oil impregnated
 
−
brass worm gear, underneath the main aluminum ring, is remotely
 
−
controlled to turn the ring to a desired octant.}
 
−
\label{fig:QweakProducts}
 
−
\end{figure}
 
−
 
 
−
===ISU's Role===
 
−
Work Package manager of the Detector and Front End electronics.
 
−
 
 
−
Inelastic PV measurements (<math>d_{\Delta}</math>)
 
−
 
 
−
==Vector Meson and Hyperon Photoproduction with Linearly Polarized Photons==
 
−
 
 
−
== Primakoff==
 
−
== CLAS==
 
−
 
 
−
=== Physics Program===
 
−
==== Polarized Structure Functions====
 
−
<math>\frac{\Delta d}{d}</math>
 
−
 
 
−
=== CLAS 12 DC Design and Construction ===
 
−
 
 
−
 
 
−
List of Currently supported students:
 
−
 
 
−
{| border="1"  |cellpadding="20" cellspacing="0
 
−
|-
 
−
|Student|| Classification || Expected Grad Yr
 
−
|-
 
−
|Julian Slamanca|| Ph. D.  || 2009
 
−
|-
 
−
|Tamar Didbarize|| Ph. D.  || 2010
 
−
|-
 
−
|Danny Martinez|| Ph. D.  || 2012
 
−
|-
 
−
|Alexi || Ph. D.  || 2012
 
−
|-
 
−
| Adrianne Spilker || M.S. ||2009
 
−
|-
 
−
|Saitiniyazi Shadike || M.S.  || 2009
 
−
|-
 
−
|Jordan Keonough || BA  || 2011
 
−
|-
 
−
|Nathan Lebaron|| BA  || 2012
 
−
|}
 
−
 
 
−
= Prior and Future use of NSF Funds=
 
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\hspace{0.5in}While at Louisiana Tech University, the PI received three prior NSF awards as a member of the Louisiana Tech Particle Physics Group. The first proposal entitled ``Parity Violating Electron Scattering at Jefferson Lab, was awarded in 2002 for three years in the amount of \$670,230 (NSF Award \#0244998) to Louisiana Tech University. The award supported the groups efforts building triggering electronics for the G0 backward angle measurements and for the initial development of the $Q_{weak}$ experiment. The second proposal, ``Precision Electroweak Measurements at Jefferson Lab, was awarded \$204,594 in 2006 (NSF Award \#0555390) with similar support for the next two years to continuing the Lousiana Group's efforts. Dr. Forest's MRI Proposal (\#PHYS-0321197) entitled {\small ``Collaborative Research:Development of a Particle Tracking System for the Qweak Experiment} was awarded \$131,770 on July 26, 2003 to develop the Region 1 tracking system for the Q$_{weak}$ experiment. The status of the work supported by the above awards which the PI was responsible for is given in section~\ref{section:QweakDetector} and shown in Figure~\ref{fig:QweakProducts}.
 
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=Facilities=
 
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\hspace{0.5in}The Idaho State University Department of Physics Strategic Plan
 
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identifies the use of experimental nuclear physics techniques as
 
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its focus area to addressing problems in both fundamental and
 
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applied science.  The major efforts of the department include
 
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fundamental nuclear and particle physics, nuclear reactor fuel
 
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cycle physics, nuclear non-proliferation and homeland security,
 
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accelerator applications, radiation effects in materials and
 
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devices, biology and health physics.  Because of this focus, the
 
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department has been characterized as one of the largest nuclear
 
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physics graduate programs in the nation with an average of over
 
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50 graduate students.  One of the key
 
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ingredients to the department's success has been the completion
 
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of the Idaho Accelerator Center (IAC) on April 30, 1999.  A substantial
 
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amount of lab space (4000 sq. ft.) within the department has
 
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become available due to a combination of the IAC and a remodeling
 
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of the physics building.  A detector lab with the potential to
 
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construct proto-type drift chambers in a clean room environment
 
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is currently planned as part of the lab space renovation.
 
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The Idaho Accelerator Center (IAC) is located less than a mile
 
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away from campus and will provide a machining facility for
 
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detector construction, an electronics shop for installation of
 
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instrumentation, and beam time for detector performance studies.
 
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The IAC houses ten operating accelerators as well as a machine and
 
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electronics shop with a permanent staff of 8 Ph.D.'s and 6
 
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engineers.  Among its many accelerator systems, the Center
 
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houses a Linac capable of delivering 20 ns to 2 $\mu$s electron
 
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pulses with an instantaneous current of 80 mA up to an energy of 25
 
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MeV at pulse rates up to 1kHz.  The IAC has donated beam time to
 
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the Q$_{weak}$ project for the purpose of testing detector
 
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performance.  One of the goals of these tests will be to evaluate
 
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the Q$_{weak}$ detector at high rates.  The IAC is well suited
 
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for these rate tests as the Q$_{weak}$ calibration rates will be
 
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much lower than the electron and photon rates the IAC is capable of
 
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generating. A full description of the facility is available at
 
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the web site (www.iac.isu.edu). 
 
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The Beowulf REsource for Monte-carlo Simulations (BREMS) is
 
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a 12 node, 64 bit cluster housed in the ISU physics department
 
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which can support the high performance computing needs of
 
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the physics research program.  This facility is the result of an
 
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investment made by NSF award PHYS-987453.  This infrastructure
 
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will be an effective means for performing GEANT4 simulations of
 
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the Q$_{weak}$ experiment as well as Garfield simulations of the
 
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Region II drift chamber design.  Simulation speed is increased on
 
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BREMS by running the simulation in parallel on many CPUs.
 
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A version of GEANT4 known as ParGeant4~\cite{ParGeant4} has recently been
 
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distributed which will allow these simulations to be run in parallel.
 
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=The Broader Impact of the Idaho State University Nuclear Physics Research Program=
 
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[http://www.iac.isu.edu/mediawiki/index.php/NSF Go Back]
 

Latest revision as of 22:02, 23 August 2011