# Difference between revisions of "January 30, 2014 - Special Theory Meeting"

From Ciswikidb

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: Measure polarimeter systematics with goal <0.5% | : Measure polarimeter systematics with goal <0.5% | ||

− | ; SIMULATION PROGRAM | + | ; OUR SIMULATION PROGRAM |

: Build GEANT4 model of polarimeter and benchmark detector response against measurement | : Build GEANT4 model of polarimeter and benchmark detector response against measurement | ||

: Implement physics (cross-section, Sherman function, spin transfer functions) provided by theory | : Implement physics (cross-section, Sherman function, spin transfer functions) provided by theory | ||

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: By calibrating model to experimental data predict zero-thickness asymmetry with high precision <1% | : By calibrating model to experimental data predict zero-thickness asymmetry with high precision <1% | ||

− | ; THEORY PROGRAM | + | ; DESIRED THEORY PROGRAM |

: Provide physics tables for simulation (cross-section, Sherman function, spin transfer functions) | : Provide physics tables for simulation (cross-section, Sherman function, spin transfer functions) | ||

: Describe theoretical basis, corrections, uncertainties | : Describe theoretical basis, corrections, uncertainties | ||

: Advise which measurements may be best tests on leading corrections or limit absolute knowledge of physics | : 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) == | == Questions (Please follow format shown) == | ||

− | ; Question #1 | + | ; 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 | + | ; 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 | + | ; Question #3 (Who, When) |

: My question is... | : My question is... | ||

; Please copy and paste format, and so on... | ; Please copy and paste format, and so on... |

## Revision as of 22:07, 15 January 2014

## Contents

### Special Theory Meeting

## Meeting Logistics

- 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...