The Development of High-Performance Alkali-Hybrid Polarized ${}^3\mathrm{He}$ Targets for Electron Scattering

Abstract

We present the development of high-performance polarized ${}^3\mathrm{He}$ targets for use in electron scattering experiments that utilize the technique of alkali-hybrid spin-exchange optical pumping. We include data obtained during the characterization of 24 separate target cells, each of which was constructed while preparing for one of four experiments at Jefferson Laboratory in Newport News, Virginia. The results presented here document dramatic improvement in the performance of polarized ${}^3\mathrm{He}$ targets, as well as the target properties and operating parameters that made those improvements possible. Included in our measurements were determinations of the so-called $X$-factors that quantify a temperature-dependent and as-yet poorly understood spin-relaxation mechanism that limits the maximum achievable ${}^3\mathrm{He}$ polarization to well under 100%. The presence of this spin-relaxation mechanism was clearly evident in our data. We also present results from a simulation of the alkali-hydrid spin-exchange optical pumping process that was developed to provide guidance in the design of these targets. Good agreement with actual performance was obtained by including details such as off-resonant optical pumping. Now benchmarked against experimental data, the simulation is useful for the design of future targets. Included in our results is a measurement of the $\mathrm{K}$-${}^3\mathrm{He}$ spin-exchange rate coefficient $k_{\mathrm{se}}^{\mathrm{K}}=\left(7.46\pm 0.62\right)\times 10^{-20}\mathrm{c}{\mathrm{m}}^3/s$ over the temperature range 503 K to 563 K.

26 pages, 18 figures, includes several revisions based on referee reports, accepted by Phys. Rev. C on 2015-04-20, in press

References in corpus (1)

• Measurements of the Electric Form Factor of the Neutron up to Q2=3.4 GeV2 using the Reaction He3(e,e'n)pp

Cited by in corpus (12)

• Optically Polarized ${}^3$He
• Diquark Correlations in Hadron Physics: Origin, Impact and Evidence
• Synchronous Spin-Exchange Optical Pumping
• Precision Measurements of $A_1^n$ in the Deep Inelastic Regime
• Measurement of the Target-Normal Single-Spin Asymmetry in Quasi-Elastic Scattering from the Reaction ${}^3$He${}^{\uparrow }(e,e^{\prime })$
• Reducing the Solar Neutrino Background Using Polarised Helium-3
• Double Spin Asymmetries of Inclusive Hadron Electroproductions from a Transversely Polarized ${}^3\mathrm{He}$ Target
• Extraction of the Neutron Electric Form Factor from Measurements of Inclusive Double Spin Asymmetries
• Measurement of double-polarization asymmetries in the quasi-elastic ${}^3\overrightarrow{\mathrm{He}}(\vec{\mathrm{e}},{\mathrm{e}}^{\prime }\mathrm{p})$ process
• Enhanced coupling of electron and nuclear spins by quantum tunneling resonances
• Absolute ${}^3$He polarimetry for a double-chambered cell using transmission of thermal neutrons
• Limits on Magnetically Induced Faraday Rotation from Polarized ${}^3$He Atoms