Speaker
Description
Since most of the $^{3}He$ spin is carried by the unpaired neutron, polarized $^{3}He$ targets have been widely used as a effective polarized neutron target in electron scattering experiments to study the spin structure of neutron. Over the past a couple of decades, polarized $^{3}He$ targets had been successfully utilized in thirteen electron scattering experiments during JLab 6 GeV era. At JLab, a technique called Spin-Exchange Optical Pumping (SEOP) is used to polarized the $^{3}He$ target. For the past decade, several developments including Rb-K hybrid alkali system and high power narrow line-width diode lasers were implemented to the polarized $^{3}He$ target in order to reach higher 3He polarization with world record luminosity. As JLab completed 12 GeV upgrade in 2017, there are seven upcoming approved polarized $^{3}He$ target experiments. Upgrade of the target with convection cell and Pulse Nulear Magnetic Resonance (PNMR) polarimetry were completed for the first upcoming 12 GeV era experiment $A_{1}^{n}$ (E12-06-110) with collaboration of $d_{2}^{n}$ (E12-06-121) in JLab Hall C. For typical $10^{22}/cm^{2}$ high-density target used in this collaboration experiment, the maximum polarization reached over 50% under $30 \mu A$ electron beam, thus the luminosity of $10^{36}/cm^{2}/s$ will be achieved.
Summary
During JLab 6 GeV era, the polarized 3He target system were successfully implemented in to multiple electron scattering experiments with world-record luminosity. As JLab upgraded to 12 GeV, the upgrades of convection cell and Pulse Nulear Magnetic Resonance polarimetry were done and the target system is ready for the upcoming A1n/d2n collaboration experiment in Hall C which will begin in November, 2019.
