Measurement of the neutron lifetime using magnetically trapped neutrons: tSPECT

自由中子的寿命是一个基本物理量，它与粒子物理学和天体物理学的许多不同领域都有关系。在这个项目中，将使用超冷中子的三维磁存储（UCN）进行中子寿命的精确测量。不同方法的实验结果的差异，梁和材料瓶实验，表明在这些实验中仍有一些微妙的和未被理解的影响。磁性捕获的中子在储存过程中不与物质相互作用，而不是依赖于材料壁上的中子反射，在材料壁上中子向上散射和捕获会造成显著的壁上损失。这就是使用磁约束和引力约束的明显吸引力，至少在原则上，中子阱相互作用的动力学是很好理解和控制的。实验tSPECT位于TRIGA美因茨研究堆的脉冲ucn源。它将于2016年底全面投入使用。在要求的3年资助期内，将进行波束时间研究并尽量减少系统影响。计划在资助期结束时（最后三分之一）测量具有~ 1s精度的竞争性中子寿命。我们的目标是在PRISMA II的框架下继续进行tSPECT的升级版本，PRISMA II是卓越集群PRISMA的计划延续。总体精度为delta tn = 0.2-0.3 s。

The lifetime of the free neutron is a basic physical quantity, which is relevant in a variety of different fields of particle and astrophysics. In this project a precise measurement of the neutron lifetime using three-dimensional magnetic storage of ultra-cold neutrons (UCN) will be conducted. The differences in the results of experiments using different methods, beam and material bottle experiments, indicate that there are still some subtle and not understood effects in some of these experiments. Rather than relying on neutron reflection from a material wall, where neutron up-scattering and capture cause significant wall losses, magnetically trapped neutrons do not interact with matter during storage. That is the obvious appeal to the use of magnetic and gravitational confinement, where, at least in principle, the dynamics of the neutron-trap interaction is well understood and under control. The experiment tSPECT is located at the pulsed UCN-source of the TRIGA Mainz research reactor. It will become fully operational end of 2016. In the requested 3 years funding period beam times will be conducted to study and to minimize the systematic effects. A measurement of a competitive neutron lifetime with ~ 1 s accuracy is planned towards the end of the funding period (during the last third). We aim to continue tSPECT in an upgraded version in the framework of PRISMA II, the planned continuation of the excellence cluster PRISMA. An overall accuracy of delta tn = 0.2-0.3 s is envisaged.