Delta ray
As a delta electron or delta radiation, electrons are referred to in particle physics that are solved during the passage of ionizing radiation through matter from the atomic shell and have a relatively large kinetic energy. Delta electrons thus represent a secondary radiation represents the name Delta Ray comes from Joseph John Thomson.
The average energy loss per distance traveled of a particle as it passes through matter is described by the Bethe -Bloch formula. The actual energy loss fluctuates around this mean and follows a Landau distribution with a long spur to high energies, so that in rare cases, a shell electron can experience a very high energy transfer, which is well above the most probable and the average energy transfer.
Delta electrons have sufficiently high energy to cause further ionization of other atoms, thereby leaving visible traces, for example, in cloud chambers. The consequence of the production of delta electrons for the measurement of particles in detectors is that they contribute significantly to one by their great energy to the fluctuations of the energy measurement and the other negatively affect the spatial resolution in trace detection by in the neighborhood of the original generate other signals by particle track ionization of the detector material. The number of triggered delta electrons per path length can be used as a measure for the charge and velocity of high energy particles from cosmic rays or in accelerator experiments.