Delta electron
In particle physics, delta electrons or delta radiation are electrons that are released from the atomic shell when ionizing radiation passes through matter and have a comparatively high kinetic energy . Delta electrons therefore represent secondary radiation. The name Delta Ray comes from Joseph John Thomson .
The mean energy loss per distance traveled by a particle when passing through matter is described by the Bethe-Bloch formula . The actual energy loss fluctuates around this mean value and follows a landau distribution with a long tail to high energies, so that in rare cases a shell electron can experience a very high energy transfer, which is significantly above the most likely and the mean energy transfer.
Delta electrons have sufficiently high energies to cause further ionization of other atoms and thereby leave visible traces, for example in cloud chambers . The consequence of generating delta electrons for the measurement of particles in detectors is that, on the one hand, they contribute significantly to the fluctuations in energy measurement due to their high energy and, on the other hand, they also have a negative impact on the spatial resolution in track detectors by being in the vicinity of the original Particle track generate further signals by ionizing the detector material. The number of delta electrons released per distance can be used as a measure of the charge and speed of high-energy particles from cosmic rays or in accelerator experiments.