The development of high-performance alkali-hybrid polarized targets for electron scattering
- University of Virginia, Charlottesville, VA (United States); Argonne National Lab., Argonne, IL (United States); Technische Universitat Munchen, Exzellenzcluster Universe, Garching (Germany)
- University of Virginia, Charlottesville, VA (United States)
- College of William and Mary, Williamsburg, VA (United States)
We present the development of high-performance polarized ³He 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 ³He 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 ³He 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 K- ³He spin-exchange rate coefficient $$k^\mathrm{K}_\mathrm{se} = \left ( 7.46 \pm 0.62 \right )\!\times\!10^{-20}\ \mathrm{cm^3/s}$$ over the temperature range 503 K to 563 K.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Nuclear Physics (NP)
- Grant/Contract Number:
- FG02-01ER41168; FG02-96ER41003
- OSTI ID:
- 1182364
- Alternate ID(s):
- OSTI ID: 1182454
- Report Number(s):
- JLAB/PHY-13/1791; DOE/OR/23177-2787; arXiv:1309.4004; PRVCAN
- Journal Information:
- Physical Review C, Nuclear Physics, Vol. 91, Issue 5; ISSN 0556-2813
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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