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>New technique for the reduction of helicity-correlated instrumental asymmetries in photoemitted beams of spin-polarized electrons
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New technique for the reduction of helicity-correlated instrumental asymmetries in photoemitted beams of spin-polarized electrons
We present a new optical system that significantly reduces helicity-dependent instrumental intensity asymmetries. It is an extension of a previous scheme [Appl. Opt. 47, 2465 (2008)], where one laser beam is split using a polarizing beam splitter into two with orthogonal linear polarizations. The beams are sent through a chopper, allowing only one to pass at a time. The two temporally separated beams are then spatially recombined using a second beam splitter. A liquid crystal retarder preceding the first beam splitter controls the relative intensity of the two oppositely polarized beams, allowing reduction of instrumental asymmetries. This system has been modified to include a spatial filter and a Pockels cell placed after the second beam splitter to act as a second active polarization element. Using this method, we can control instrumental asymmetries to similar to 5 x 10(-7) in 1 h of data taking, which is comparable to the precision achieved in "secondgeneration" high energy electron-nuclear scattering parity violation experiments. (C) 2015 Optical Society of America
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机译：我们提出了一种新的光学系统，该系统显着降低了依赖于螺旋度的仪器强度不对称性。它是先前方案的扩展[Appl。选择。 47，第2465页（2008）]，其中使用偏振分束器将一束激光束分成正交线性偏振的两束。光束通过斩波器发送，一次只能通过一个。然后，使用第二分束器在空间上重组两个时间上分开的光束。在第一分束器之前的液晶延迟器控制两个相反偏振的光束的相对强度，从而减少了仪器的不对称性。该系统已被修改为包括一个空间滤波器和一个放置在第二个分束器之后的Pockels盒，用作第二个有源偏振元件。使用此方法，我们可以在1小时的数据采集过程中将仪器的不对称性控制为类似于5 x 10（-7），这与“第二代”高能电子-核散射奇偶性违规实验中获得的精度相当。 （C）2015年美国眼镜学会
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