压力下超流氦中多声子过程产生UCN
UCN production by multiphonon processes in superfluid Helium under pressure
摘要：
冷中子在超流氦中通过激发单声子或多声子而转变为超冷中子（UCN）。超流氦的动态散射函数S（q，ω）强烈地依赖于压力，导致依赖于压力的微分UCN产生速率。描述UCN产生的散射函数s（λ）的多声子部分的唯象表达式已来自非弹性中子散射数据。当结合从单声子过程的生产率，这使我们能够计算任何入射中子通量的UCN生产。对于从单声子过程计算UCN产生，我们建议使用S*（SVP）= 0.118（8）和S*（20 bar）= 0.066（6）的值。作为一个例子，我们将计算预期的UCN生产率在冷中子束的基础物理PF1b在劳厄朗之万研究所。我们的结论是，UCN生产超流氦压力下是没有吸引力的。
英文摘要：
Cold neutrons are converted to ultra-cold neutrons (UCN) by the excitation of a single phonon or multiphonons in superfluid helium. The dynamic scattering function S(q, omega) of the superfluid helium strongly depends on pressure, leading to a pressure- dependent differential UCN production rate. A phenomenological expression for the multiphonon part of the scattering function s(lambda) describing UCN production has been derived from inelastic neutron scattering data. When combined with the production rate from single phonon processes this allows us to calculate the UCN production for any incident neutron flux. For calculations of the UCN production from single phonon processes we propose to use the values for S*(SVP) = 0.118(8) and S*(20 bar) = 0.066(6). As an example we will calculate the expected UCN production rate at the cold neutron beam for fundamental physics PF1b at the Institut Laue Langevin. We conclude that UCN production in superfluid helium under pressure is not attractive.
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。
