The photon arm of the Compton polarimeter in Hall A of Jefferson Lab has been upgraded to allow for electron beam polarization measurements with better than 1% accuracy. The data acquisition system (DAQ) now includes an integrating mode, which eliminates several systematic uncertainties inherent in the original counting-DAQ setup. The photon calorimeter has been replaced with a Ce-doped GSO crystal, which has a bright output and fast response, and works well for measurements using the new integrating method at electron beam energies from 1 to 6 GeV.
@article{arxiv.1108.3116,
title = {Upgraded photon calorimeter with integrating readout for Hall A Compton Polarimeter at Jefferson Lab},
author = {M. Friend and D. Parno and F. Benmokhtar and A. Camsonne and M. Dalton and G. B. Franklin and V. Mamyan and R. Michaels and S. Nanda and V. Nelyubin and K. Paschke and B. Quinn and A. Rakhman and P. Souder and A. Tobias},
journal= {arXiv preprint arXiv:1108.3116},
year = {2015}
}