January 30, 2014 - Special Theory Meeting
Revision as of 22:07, 15 January 2014 by Grames
Special Theory Meeting
- Thursday, January 30th 9am EST
- JLAB Meeting Room TBD
- Remote call-in information TBD
BACKGROUND FOR THEORISTS
- OUR EXPERIMENTAL PROGRAM
- To precisely measure scattering asymmetry of spin polarized electrons from thin pure Z foils
- Accessible energy range is about 3 to 8 MeV
- Targets on hand are gold, silver, copper foils of varying thickness, but can install others readily
- Measure polarimeter systematics with goal <0.5%
- OUR SIMULATION PROGRAM
- Build GEANT4 model of polarimeter and benchmark detector response against measurement
- Implement physics (cross-section, Sherman function, spin transfer functions) provided by theory
- Develop ab initio simulation dependence of asymmetry on target thickness (multiple scattering, radiation effects, etc) to measurement
- By calibrating model to experimental data predict zero-thickness asymmetry with high precision <1%
- DESIRED THEORY PROGRAM
- Provide physics tables for simulation (cross-section, Sherman function, spin transfer functions)
- Describe theoretical basis, corrections, uncertainties
- Advise which measurements may be best tests on leading corrections or limit absolute knowledge of physics
- Consider calculation to improve uncertainty in physics below 1%
Questions (Please follow format shown)
- Question #1 (Joe 1/13/2014)
- Coulomb screening is a leading effect for electron energies <1 MeV, and finite nuclear size is a leading effect for energies >10MeV (when DeBrogile wavelength is comparable to nuclear radius). Although our polarimeter is optimized for 5MeV we can operate with beam energies typically from about 3-8 MeV. What is the size of the uncertainty on the corrections in this energy range and for Z we use such as gold, silver, copper? Are we sensitive enough in this region to perform a test on the uncertainty of the physics calculations, e.g. using suitable Z or extending the energy reach?
- Question #2 (Joe 1/15/2014)
- Is the biggest uncertainty in the theoretical calculations radiative corrections? Can a sound theoretical calculation be made that calculates this contribution with relative accuracy of ~30%?
- Question #3 (Who, When)
- My question is...
- Please copy and paste format, and so on...