测量中子自旋宇称破坏的液氦靶系统
A liquid helium target system for a measurement of parity violation in neutron spin rotation
摘要：
设计并建立了一套液氦靶系统，用于精确测量氦中核子-核子弱相互作用引起的宇称违反中子自旋转动。测量采用了一束低能中子，穿过一个交叉的中子极化器-分析器对，液氦靶系统位于它们之间。目标状态之间的变化产生的差异，在通过偏振器-分析器对的光束传输。宇称违反自旋旋转的量从测量的光束传输不对称性确定。预期的宇称破坏自旋旋转的$10^{-6}$ rad阶对目标设计施加了严格的限制。特别地，自旋旋转的宇称奇分量与由磁场引起的大得多的背景旋转的隔离需要在磁屏蔽内支撑超导低温恒温器和靶系统，同时允许液氦在分离的靶室之间的超导运动。本文详细介绍了液氦靶系统的设计、功能和性能。
英文摘要：
A liquid helium target system was designed and built to perform a precision measurement of the parity-violating neutron spin rotation in helium due to the nucleon-nucleon weak interaction. The measurement employed a beam of low energy neutrons that passed through a crossed neutron polarizer--analyzer pair with the liquid helium target system located between them. Changes between the target states generated differences in the beam transmission through the polarizer--analyzer pair. The amount of parity-violating spin rotation was determined from the measured beam transmission asymmetries. The expected parity-violating spin rotation of order $10^{-6}$ rad placed severe constraints on the target design. In particular, isolation of the parity-odd component of the spin rotation from a much larger background rotation caused by magnetic fields required that a nonmagnetic cryostat and target system be supported inside the magnetic shielding, while allowing nonmagnetic motion of liquid helium between separated target chambers. This paper provides a detailed description of the design, function, and performance of the liquid helium target system.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
