Energy straggling and radiation reaction for magnetic bremsstrahlung

When the average energy of the photon emitted by synchrotron radiation becomes appreciable compared to the energy of the particle, the particle will undergo straggling in its energy loss, which in turn broadens the radiation spectrum. The energy distributions of particles and the emitted photons are calculated using the method of quantum electrodynamics. The results are presented together with effects due to classical radiative reaction for experimental test. The significance of energy straggling in astrophysics is discussed briefly.