Mössbauer experiments in a rotating system, Doppler effect and the influence of acceleration

Abstract.

We address a recent measurement carried out by Friedman et al. (J. Synchrotron Rad. 24, 661 (2017)) that was contingent upon the Mössbauer effect arising from the application of resonant synchrotron radiation on an orbiting resonant absorber, where the authors claim to have detected the influence of the centrifugal acceleration of the absorber on the measured shift of the resonant line. We show that a later attempt to explain the outcome of this experiment via the time-dependent Doppler effect in an accelerated frame (E. Benedetto and A. Feoli, Eur. Phys. J. Plus 133, 53 (2018)) is based on a misinterpretation of the Mössbauer effect and should thenceforth be rejected. We further show that the revealed dependence of the energy shift of the resonant line on the centrifugal acceleration of the resonant absorber could happen solely due to instrumental factors. In this regard, a realistic way to analyze the origin of the extra energy shift between emission and absorption lines in a rotating system is proposed.