Measurement of the single-spin asymmetry Ay0 in quasi-elastic 3He↑(e,e′n) scattering at 0.4
Measurement of the single-spin asymmetry Ay0 in quasi-elastic 3He↑(e,e′n) scattering at 0.4
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0.4 准弹性 3He−(e,e−n) 散射中单自旋不对称性 Ay0 的测量
DOI：
10.1016/j.physletb.2019.134875
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发表时间：
2019
影响因子：
4.4
通讯作者：
Allada, K.
中科院分区：
文献类型：
--
作者：
Long, E.;Zhang, Y.W.;Mihovilovič, M.;Jin, G.;Sulkosky, V.;Kelleher, A.;Anderson, B.;Higinbotham, D.W.;Širca, S.;Allada, K.
由于缺乏自由中子靶，中子结构的研究通常通过从²H或³He靶散射电子来进行。为了从<$He靶中提取有用的中子信息，必须通过考虑核效应（如终态相互作用和介子交换流）来理解<$He系统中的中子与自由中子的区别。目标单自旋不对称性A是这种效应的理想探测器，因为任何偏离零的情况都表明超出平面波冲量近似的效应。杰斐逊实验室使用准弹性³He↑（e，e 'n）反应在Q²为0.46和0.96 GeV/c²时对目标单自旋不对称性A进行了新的测量。我们测得的不对称性迅速下降，从Q²= 0.46 GeV/c²的20%下降到Q²= 0.96 GeV/c²的几乎为零，表明随着Q²的增加，反应机制效应下降。我们还观察到，与以前的测量结果相比，A的负相关性略有增加，特别是在中等Q²时。这表明杰斐逊实验室12 GeV计划即将进行的高Q²测量可以使用平面波脉冲近似干净地探测来自极化氦的中子结构。
Due to the lack of free neutron targets, studies of the structure of the neutron are typically made by scattering electrons from either ²H or ³He targets. In order to extract useful neutron information from a ³He target, one must understand how the neutron in a ³He system differs from a free neutron by taking into account nuclear effects such as final state interactions and meson exchange currents. The target single spin asymmetry A⁰ʸ is an ideal probe of such effects, as any deviation from zero indicates effects beyond plane wave impulse approximation. New measurements of the target single spin asymmetry A⁰ʸ at Q² of 0.46 and 0.96 GeV/c² were made at Jefferson Lab using the quasi-elastic ³He↑(e, e'n) reaction. Our measured asymmetry decreases rapidly, from 20% at Q²= 0.46 GeV/c² to nearly zero at Q²= 0.96 GeV/c², demonstrating the fall-off of the reaction mechanism effects as Q² increases. We also observed a small epsiv-dependent increase in A⁰ʸ compared to previous measurements, particularly at moderate Q². This indicates that upcoming high Q² measurements from the Jefferson Lab 12 GeV program can cleanly probe neutron structure from polarized ³He using plane wave impulse approximation.