Speaker
Description
In-situ polarization can provide the highest performance over time for polarized $^3$He over time where $^3$He polarizations in excess of 80% can be maintained. The polarization rates and magnitude achieved are aided by using high performance $^3$He cells produced all in house and techniques such as hybrid spin-exchange optical pumping and chipped volume Bragg grating narrowed laser diode array bars. For the magnetic environments we normally use so called magic boxes which give very high 3He lifetime performance and good isolation from external magnetic fields due to their geometry that creates a magnetic field transverse to the beam propagation direction which also allows decoupling of the the optical pumping light path to the orthogonal neutron beam path. As an example, recently for a user experiment on the ROT effect in $^{235}$U one of our polarizers gave a $^3$He polarization in excess of 81% for over 20 days with a polarization build rate of 7 hours, this corresponded to a neutron polarization of 99.3% at 22% neutron transmission at 1.15 Å.
