Limits to the polarization for spin-exchange optical pumping of 3He
Limits to the polarization for spin-exchange optical pumping of 3He
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DOI：
10.1103/physrevlett.96.083003
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发表时间：
2006-03-03
影响因子：
8.6
通讯作者：
Gentile, TR
中科院分区：
文献类型：
--
作者：
Babcock, E;Chann, B;Gentile, TR
基于对各种自旋交换光泵浦细胞中 He-3 弛豫温度依赖性的测量，我们报告了先前未被识别的表面弛豫过程的证据。研究发现弛豫率与碱金属密度成线性比例，斜率超过自旋交换率，这限制了当前应用的极化，包括中子自旋过滤器、极化目标和极化气体磁共振成像。我们发现，这种过度松弛的幅度在细胞之间差异很大，并且对于表面积与体积比较高的细胞，变化更大。我们观察到 He-3 极化高达 81%，但进一步的改进需要了解这种弛豫的根源。
Based on measurements of the temperature dependence of He-3 relaxation in a wide range of spin-exchange optical pumping cells, we report evidence for a previously unrecognized surface relaxation process. The relaxation rate was found to be linearly proportional to the alkali-metal density with a slope that exceeds the spin-exchange rate, which limits the polarization for current applications, including neutron spin filters, polarized targets, and polarized gas magnetic resonance imaging. We find that the magnitude of this excess relaxation can vary widely between cells, and that the variation is larger for cells of higher surface to volume ratio. We have observed He-3 polarization as high as 81%, but further improvements require understanding the origin of this relaxation.