Speaker
Description
The JLab Super Bigbite Spectrometer (SBS) program’s primary goal is to determine the elastic nucleon form factors at high momentum transfer. The SBS program includes a measurement of the neutron electric form factor, GEn, using the double-polarization technique with both a polarized electron beam and a polarized $^3$He target (effective neutron target). In order to obtain adequate statistics in the high Q$^2$ region, the polarized $^3$He target has operated with a polarization-weighted luminosity approximately a factor of two above any previous polarized $^3$He target used in an electron-scattering experiment. The world-record-breaking target includes a double-chambered glass cell, filled to approximately 7 atm of $^3$He at room temperature, with the long cylindrical "target chamber" measuring approximately 60 cm in length. In order to maintain high polarization with electron beam currents up to 60 $\mu$A, the target cells contain roughly 6 STP liters of $^3$He, twice the quantity of $^3$He used in previous targets at JLab. This target is polarized using alkali-hybrid spin-exchange optical pumping using up to 200W of near-infrared light from high-powered diode-laser arrays. This talk will cover the cell production process at UVA, an overview of the current polarimetry efforts, and a preliminary breakdown of individual cell performance for the entire GEn-II experiment.
