Holley A T, Broussard L J, Davis J L, Hickerson K, Ito T M, Liu C-Y, Lyles J T M, Makela M, Mammei R R, Mendenhall M P, Morris C L, Mortensen R, Pattie R W, Rios R, Saunders A, Young A R
Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA.
Rev Sci Instrum. 2012 Jul;83(7):073505. doi: 10.1063/1.4732822.
The UCNA collaboration is making a precision measurement of the β asymmetry (A) in free neutron decay using polarized ultracold neutrons (UCN). A critical component of this experiment is an adiabatic fast passage neutron spin flipper capable of efficient operation in ambient magnetic fields on the order of 1 T. The requirement that it operate in a high field necessitated the construction of a free neutron spin flipper based, for the first time, on a birdcage resonator. The design, construction, and initial testing of this spin flipper prior to its use in the first measurement of A with UCN during the 2007 run cycle of the Los Alamos Neutron Science Center's 800 MeV proton accelerator is detailed. These studies determined the flipping efficiency of the device, averaged over the UCN spectrum present at the location of the spin flipper, to be ̅ε=0.9985(4).
加州大学北卡罗来纳分校（UCNA）合作团队正在使用极化超冷中子（UCN）对自由中子衰变中的β不对称性（A）进行精确测量。该实验的一个关键组件是绝热快速通过中子自旋翻转器，它能够在约1 T的环境磁场中高效运行。由于需要在高磁场中运行，因此首次有必要构建一个基于鸟笼谐振器的自由中子自旋翻转器。本文详细介绍了该自旋翻转器在洛斯阿拉莫斯中子科学中心800 MeV质子加速器2007运行周期中首次用于用UCN测量A之前的设计、构建和初步测试。这些研究确定，在自旋翻转器所在位置的UCN谱上平均，该装置的翻转效率为̅ε = 0.9985(4)。
