标题： 卡特林预谱仪中的雷纳德背景过程 显示英文标题

标题： Radon induced background processes in the KATRIN pre-spectrometer

摘要： KArlsruhe TRItium Neutrino（KATRIN）实验是一项新一代、模型无关的大型氚β衰变实验，通过研究氚β衰变的运动学特性，利用MAC-E滤波器技术以200 meV/c²的灵敏度确定有效电子反中微子质量。 为了达到这种灵敏度，需要背景水平为每秒0.01个计数（cps）。 本文描述了在KATRIN预谱仪测试装置上进行的测量结果，说明了MAC-E滤波器中的氡衰变如何产生背景事件。 从KATRIN谱仪真空区域内的材料中释放出的氡（Rn）原子能够深入进入磁通管，因此氡的α衰变会贡献背景。 特别重要的是在氡的α衰变过程中伴随发生的电子发射过程，例如抖动效应、氡子原子激发态的内部转换以及俄歇电子。 低能电子（< 100 eV）会直接对信号区域的背景做出贡献，而高能电子则可以在谱仪体积内被磁性储存。 根据它们的初始能量，它们可以通过与残留气体分子的后续电离过程产生数千个次级电子，由于探测器无法区分这些次级电子和信号电子，因此会在较长时间内产生增加的背景率。 显示英文摘要

摘要： The KArlsruhe TRItium Neutrino (KATRIN) experiment is a next generation, model independent, large scale tritium beta-decay experiment to determine the effective electron anti-neutrino mass by investigating the kinematics of tritium beta-decay with a sensitivity of 200 meV/c2 using the MAC-E filter technique. In order to reach this sensitivity, a low background level of 0.01 counts per second (cps) is required. This paper describes how the decay of radon in a MAC-E filter generates background events, based on measurements performed at the KATRIN pre-spectrometer test setup. Radon (Rn) atoms, which emanate from materials inside the vacuum region of the KATRIN spectrometers, are able to penetrate deep into the magnetic flux tube so that the alpha-decay of Rn contributes to the background. Of particular importance are electrons emitted in processes accompanying the Rn alpha-decay, such as shake-off, internal conversion of excited levels in the Rn daughter atoms and Auger electrons. While low-energy electrons (< 100 eV) directly contribute to the background in the signal region, higher energy electrons can be stored magnetically inside the volume of the spectrometer. Depending on their initial energy, they are able to create thousands of secondary electrons via subsequent ionization processes with residual gas molecules and, since the detector is not able to distinguish these secondary electrons from the signal electrons, an increased background rate over an extended period of time is generated.