Difference between revisions of "DV RunGroupC Moller"
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− | :::::<math>\rho_{target}\times l_{target}=\frac{ | + | :::::<math>\rho_{target}\times l_{target}=\frac{2.26 g}{1 cm^3}\times \frac{1 mole}{2.02 g} \times \frac{1000g}{1 kg} \times \frac{6\times10^{23} atoms}{1 mole} \times \frac{1m^3}{(100 cm)^3} \times \frac{1 cm}{ } \times \frac{10^{-24} cm^{2}}{barn} =2.10\times 10^{-2} barns</math> |
Revision as of 16:15, 11 March 2016
need to insert moller shielding into card after moller LUND file is created. (see clas12/beamline)
Simulating the Moller scattering background for EG12
GEANT4 Simulation of Moller Events
Determine the Moller background using an LH2 target to check the physics in GEANT4
Incident electron energy varies from 1-11 GeV.
LH2 target is a cylinder with a 1.5 cm diameter and 1 cm thickness.
(Following dimensions listed on page 8 of File:PHY02-33.pdf)
Numbers Moller electrons per incident electron.
While 2nd and 3rd generations are created, only 2 2nd generation daughter particles are created for 1E6 incident particles. All knock on electrons are not counted.
Momentum distributions in the Lab Frame.
Momentum distributions in the Center of Mass Frame.
Estimated Momentum Distribution
DV_Calculations_of_4-momentum_components
For an incoming electron with momentum of 11GeV, we should find the momentum in the center of mass to be around 53 MeV which is confirmed in the the data/plots.
KEi | Pxi | Pyi | Pzi | xi | yi | z1 | KEf | Pxf | Pyf | Pzf | xf | yf | zf | KEm | Pxm | Pym | Pzm | xm | ym | zm |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
11000 | 0 | 0 | 11000.5 | 0 | 0 | -510 | 10999.1 | 0.433025 | -0.858867 | 10999.6 | 0 | 0 | -509.276 | 0.905324 | -0.433025 | 0.858867 | 0.905366 | 0 | 0 | -509.276 |
Changing the code for the total Energy to
in the lab frame givesAngular Distribution in the Lab Frame
Angular Distribution in the Center of Mass Frame
Comparing experimental vs. theoretical for Møller differential cross section 11GeV
Using the equation from [1]
This can be simplified to the form
Plugging in the values expected for a scattering electron:
Using unit analysis on the term outside the parantheses, we find that the differential cross section for an electron at this momentum should be around
Using the conversion of
We find that the differential cross section scale is
Converting the number of electrons to barns,
where ρtarget is the density of the target material, ltarget is the length of the target, and iscattered is the number of incident particles scattered.
Combining these plots, and rescaling the Final Theta in the Center of Mass for micro-barns, we find
Step 2
Replace the LH2 target with an NH3 target and compare with LH2 target.
The Moller Momentum plot for higher momenta run to increase the number of values
LH2 Vs. NH3
Figure out the offset
Rerunning the GEANT simulation for a target of solo atoms of Carbon 12, with 410 incident 11GeV electrons
Density of target material:
C=2.26 g/cm3
NH3=.86g/cm3
LH2=.07g/cm3
Altering the density of LH2 to be .86g/cm3 we find
Comparing this to the theoretical differential cross section:
As shown above We find that the differential cross section scale is
Converting the number of electrons to barns,
where ρtarget is the density of the target material, ltarget is the length of the target, and iscattered is the number of incident particles scattered.
Step 3
Determine impact of Solenoid magnet on Moller events
Papers used
[1]Farrukh Azfar's Derivation of Moller Scattering
A polarized target for the CLAS detector
An investigation of the spin structure of the proton in deep inelastic scattering of polarized muons on polarized protons
QED Radiative Corrections to Low-Energy Moller and Bhabha Scattering
http://arxiv.org/abs/1602.07609