Speaker
Description
Polarized $^3$He beam is a crucial capability envisioned for EIC, whose development is underway. Measuring the polarization of the $^3$He beam is thus critical for a productive scientific program. We plan to develop and commission an absolute $^3$He polarimeter based on $^3$He--$^3$He elastic scattering at RHIC, similar to the HJet based proton polarimeter currently in operation, which also uses an atomic beam source (ABS) of polarized H$^-$. This new hadron polarimeter would use a highly polarized ABS of $^3$He as a target. The ABS initially was planned for the neutron electric dipole moment experiment at Oak Ridge National Laboratory. Re-purposing this ABS benefits not only the previous investment into its development, but also provides a far superior target with a high density.
The ABS produces a near-collinear beam of cold $^3$He atoms at $\sim1~$K, with the help of an etched multi-channel plate, and upon passing through a quadrupole magnetic field, polarizes the $^3$He atoms. The upgraded atomic beam source can be mounted in the vertical orientation and has the capacity to actuate the initial direction of the beam of $^3$He atoms. The performance parameters of, and the design challenges involved in upgrading the $^3$He atomic beam source, along with the simulations used in vetting the design process, as well as the development of scattered particle detectors required for absolute polarimetry, will be presented.
