Development of high-performance alkali-hybrid polarized 3 He targets for electron scattering
Development of high-performance alkali-hybrid polarized 3 He targets for electron scattering
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DOI：
10.1103/physrevc.91.055205
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发表时间：
2013-09
影响因子：
3.1
通讯作者：
J. Singh;P. A. Dolph;W. Tobias;T. Averett;A. Kelleher;Karen Mooney;Karen Mooney;V. Nelyubin;Yunxiao Wang;Yuan Zheng;G. Cates
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文献类型：
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作者：
J. Singh;P. A. Dolph;W. Tobias;T. Averett;A. Kelleher;Karen Mooney;Karen Mooney;V. Nelyubin;Yunxiao Wang;Yuan Zheng;G. Cates
我们介绍了利用碱-混合自旋交换光学泵浦技术的用于电子散射实验的高性能偏振靶的研制。我们包括了在对24个独立的靶细胞进行表征期间获得的数据，每个靶细胞都是在弗吉尼亚州纽波特纽斯的杰斐逊实验室准备四个实验之一时构建的。这里给出的结果记录了极化He靶性能的显著改善，以及使这些改进成为可能的靶特性和操作参数。在我们的测量中包括了所谓的X因子的确定，该因子量化了一种依赖于温度的自旋弛豫机制，该机制将最大可实现的极化限制在远低于100%的范围内。在我们的数据中，这种自旋弛豫机制的存在是显而易见的。我们还给出了碱-氢化物自旋交换光学泵浦过程的模拟结果，该过程旨在为这些靶的设计提供指导。通过考虑非共振光抽运等细节，得到了与实际性能很好的一致性。现在，以实验数据为基准，模拟对于未来目标的设计是有用的。在我们的结果中包括了在503K到563K温度范围内的自旋交换速率系数K-k^\mathm{K}_\mathm{se}=左(7.46\pm 0.62\右)×10^-20}\mathm{cm^3/S}$$的测量。
We present the development of high-performance polarized ³He targets for use in electron scattering experiments that utilize the technique of alkali-hybrid spin-exchange optical pumping. We include data obtained during the characterization of 24 separate target cells, each of which was constructed while preparing for one of four experiments at Jefferson Laboratory in Newport News, Virginia. The results presented here document dramatic improvement in the performance of polarized ³He targets, as well as the target properties and operating parameters that made those improvements possible. Included in our measurements were determinations of the so-called X-factors that quantify a temperature-dependent and as-yet poorly understood spin-relaxation mechanism that limits the maximum achievable ³He polarization to well under 100%. The presence of this spin-relaxation mechanism was clearly evident in our data. We also present results from a simulation of the alkali-hydrid spin-exchange optical pumping process that was developed to provide guidance in the design of these targets. Good agreement with actual performance was obtained by including details such as off-resonant optical pumping. Now benchmarked against experimental data, the simulation is useful for the design of future targets. Included in our results is a measurement of the K- ³He spin-exchange rate coefficient $$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.