Spectrometers based on the magnetic adiabatic collimation followed by an electrostatic filter (MAC-E-filter) principle combine high angular acceptance with an excellent energy resolution. These features make MAC-E-filters very valuable for experiments where the kinetic energy of ions or electrons from rare processes has to be measured with utmost sensitivity and precision. Examples are direct neutrino mass experiments like KATRIN which investigate the energy of electrons in the endpoint region of the tritium \(\beta \)-spectrum. However, the MAC-E-filter is a very sharp energy high-pass filter but not a differential spectrometer. To determine a spectral shape of a charged particle source, different electric retarding potentials have to be used sequentially, reducing the statistics. In a previous work we have shown that the advantages of the standard MAC-E-filter can be combined with a measurement of the time-of-flight (TOF), allowing to determine spectral information over a certain energy range with one retarding potential only, with the corresponding gain in statistics. This TOF method requires one to know the start time of the charged particles, which is not always possible. Therefore, we propose a new method which does not require the determination of the start time and which we call “time-focusing time-of-flight” (tfTOF): by applying a time dependent acceleration and deceleration potential at a subsequent MAC-E-filter, an energy dependent post-bunching of the charged particles is achieved.

基于磁绝热准直的光谱仪再加上静电滤光片（MAC-E滤光片）原理，将高角度接受度与出色的能量分辨率结合在一起。这些特性使MAC-E过滤器对于必须极其灵敏和精确地测量稀有过程中的离子或电子的动能的实验非常有价值。例子是直接中微子质量实验，例如KATRIN，它研究the \（\ beta \）终点区域中电子的能量-光谱。但是，MAC-E滤波器是一种非常尖锐的能量高通滤波器，而不是差分光谱仪。为了确定带电粒子源的光谱形状，必须顺序使用不同的延迟电位，从而减少了统计量。在先前的工作中，我们证明了标准MAC-E滤波器的优势可以与飞行时间（TOF）的测量相结合，从而可以确定某一能量范围内的光谱信息，而仅具有一个延迟电位，并获得相应的统计数据。这种TOF方法要求人们知道带电粒子的开始时间，这并不总是可能的。因此，我们提出了一种不需要确定开始时间的新方法，我们将其称为“时间聚焦飞行时间”（tfTOF）：