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Title: The development of high-performance alkali-hybrid polarized He 3 targets for electron scattering

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.
 [1] ;  [2] ;  [2] ;  [3] ;  [3] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2]
  1. University of Virginia, Charlottesville, VA (United States); Argonne National Lab., Argonne, IL (United States); Technische Universitat Munchen, Exzellenzcluster Universe, Garching (Germany)
  2. University of Virginia, Charlottesville, VA (United States)
  3. College of William and Mary, Williamsburg, VA (United States)
Publication Date:
Report Number(s):
JLAB/PHY-13/1791; DOE/OR/23177-2787; arXiv:1309.4004
Journal ID: ISSN 0556-2813; PRVCAN
Grant/Contract Number:
FG02-01ER41168; FG02-96ER41003
Accepted Manuscript
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 91; Journal Issue: 5; Journal ID: ISSN 0556-2813
American Physical Society (APS)
Research Org:
Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Nuclear Physics (NP) (SC-26)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1182454