A novel FPGA-based data acquisition for high-precision asymmetry measurements at low rates in electron scattering

Abstract

Asymmetry measurements in the scattering of polarized electrons on unpolarized targets are powerful tools to study the neutron distribution in nuclei and the multi-photon exchange contribution to the scattering process. Measuring these quantities requires not only precise counting of the scattered electrons, but also simultaneous accurate monitoring of the primary beam in order to correct any non-physical asymmetries. For this purpose, a dedicated data acquisition set-up was developed using FPGAs and fast discriminators for electron counting and voltage-to-frequency converters for beam monitoring. The performance of the new set-up was evaluated in experiments at the Mainz Microtron.