Modeling

The Mott Group has a GEANT4 simulation of the JLab MeV Mott Polarimeter. This simulation was built from 2014-2016 simultaneous to the upgrade efforts on the polarimeter. The primary purpose of this simulation is to determine, from first principles, the shape of the effective Sherman function with respect to target thickness. This page serves a few purposes: it provides links to the relevant references for simulation users, provides a brief tutorial, and shows results. Additionally, this page may serve as a place to indicate what work is being done or needs to be done on the simulation.

Where To Find the Simulation

• A working version is maintained on the ifarm computers CUE in the directory /group/mottgrp/MottG4/.
• To use this, the user must set the environment variable $MOTTG4DIR to /path/to/MottG4/ before using the simulation.
• Additionally, the user must have access to cmake version 2.8 or later
• The current version is maintained at github for those who want the model on their personal computers. Contact Martin McHugh at mjmchugh@jlab.org for access to this repository.

How It Works

• The Mott Polarimeter team is developing a GEANT4 model of the polarimeter.

To Do List

• Add pre-vertex energy loss Small effect for our targets (~50 keV max in 5 um Au) according to NIST --Mjmchugh (talk) 17:54, 22 April 2015 (EDT)
• Add primary vertex output info:
  • Scattering cross-section
  • Scattering location 3-vector
  • Outgoing polarization 3-vector --Mjmchugh (talk) 19:04, 9 June 2015 (EDT)
• Integrate Xavier's most recent calculations.
• Interactively change angular range for primaries --Mjmchugh (talk) 09:57, 16 June 2015 (EDT)
• Change Random Seed handling to GEANT4 standard a la QweakSimG4. --Mjmchugh (talk) 15:36, 29 June 2015 (EDT)
• Build Mott Physics Class (single scattering based on Xavier's data).
• Build Double-Scattering Generator --Mjmchugh (talk) 15:35, 29 June 2015 (EDT)