Defining polarised neutron beams in high-precision experiments with PERC

该项目是整个PERC项目的一部分，其目的是确定该仪器内部的极化中子束，用于中子β衰变的研究。在本文中，术语定义包括中子从偏振器到衰变体积的转移，包括反转射束偏振取向的可能性，并且在该过程中保持假定的高极化度以及中子从衰变体积的去耦以及它们在射束阻挡件中的吸收，该射束阻挡件产生辐射背景和低至这是可能的，并允许确定当前的中子通量和透射的极化度。此外，该提案还包括继续开发在空间变化磁场中通过中子自旋共振形成极化中子脉冲的光谱和时间，现在称为MONOPOL项目。一个中子束可以定义在其光谱和时间结构，传统的速度选择器和束斩波器-MONOPOL的替代概念，这是在其初始开发阶段，可以代表一个有吸引力的除了实验的机会，超过了标准解决方案的能力，通过去耦的时间和能量分辨率的中子束。与PERC的测量依赖于高且定义明确的中子极化程度一样，这也是自旋共振器的基本要求。因此，必须设计一种引导装置，该引导装置能够保持中子束从偏振器进入衰变体积的这种高偏振。这是特别重要的，因为在生产和稍后在衰减体积中的极化矢量是垂直的，从而相关磁场的过渡需要得到特别的考虑。此外，它是需要与PERC的实验，以扭转初始中子极化，我们将定义一个适当的宽带自旋翻转器，并优化其位置的光束引导，其中有几个选项是可用的。在衰变体积结束时，必须在后续探测器和光谱仪中捕获中子束，而不会因散射的中子或产生的伽马辐射和次级粒子而产生不必要的事件。同时，必须在中子飞行路径的末端测量透射中子极化和强度，以使实验获得的衰变数据对这些量进行归一化。第一位申请人在项目的第一阶段就被提名为PERC的“时间和项目经理”，并在PERC磁体系统的采购、制造、质量控制和安装过程中代表维也纳集团。

This project is part of the overall PERC project and consists of the aim to define the polarised neutron beam inside this instrument for the investigation of the neutron beta decay. The term definition comprises in this context the transfer of the neutron from the polariser into the decay volume including the possibility of inverting the orientation of the beam polarisation, and in the process to preserve the assumed high degree of polarisation as well as the decoupling of the neutrons from the decay volume and their absorption in a beam stop that produces a radiation background and an amount of secondary particles as low as possible and allows for the determination of the current neutron flux and the transmitted degree of polarisation. Additionally, this proposal includes the continuation of a development for the spectral and temporal forming of polarised neutron pulses by means of neutron spin resonance in spatially varying magnetic fields which is now referred to as the MONOPOL project. A neutron beam may be defined in its spectral and temporal structure conventionally with a velocity selector and a beam chopper – the alternative concept of MONOPOL, which is in its initial development phase, could represent an attractive addition to the experimental opportunities which exceeds the capabilities of the standard solution by decoupling the time and energy resolution for the neutron beam. Like the measurements with PERC depend on a high and well defined degree of neutron polarisation, this is also a basic requirement for the spin resonator. Therefore it is essential to design a guiding which is capable to preserve this high polarisation of the neutron beam from the polariser into the decay volume. This is particularly important since the polarisation vectors at production and later in the decay volume are perpendicular whereby the transition of the related magnetic fields needs to receive special consideration. Additionally, it is required for experiments with PERC to reverse the initial neutron polarisation for which we will define an appropriate broad-band spin flipper and optimise its position in the beam guidance where several options are available. At the end of the decay volume, the neutron beam must be caught without producing unwanted events by scattered neutrons or created gamma radiation and secondary particles in the subsequent detectors and spectrometers. At the same time the measurement of the transmitted neutron polarisation and intensity must be made possible at the end of the neutron flight path to enable normalisation of the experimentally obtained decay data on these quantities. The first applicant was nominated “Time and Project Manager” for PERC already in the first phase of the project and represents the Vienna group during procurement, manufacturing, quality control and installation of the PERC magnet system.