Kündig's experiment on the transverse Doppler shift re-analyzed

In this paper, we re-analyze the ingenious experiment by Kündig (measurement of the transverse Doppler shift by means of the Mössbauer effect) and show that a correct processing of experimental data gives a relative energy shift ΔE/E of the absorption line different from the value of classically assumed relativistic time dilation for a rotating resonant absorber. Namely, instead of the relative energy shift {{\Delta E} / {E = - (1.0065 \pm 0.011){{v^2 } / {2c^2 }}}} reported by Kündig (v being the linear velocity of absorber and c being the light velocity in vacuum), we derive from his results {{\Delta E} / {E = - (1.192 \pm 0.011){{v^2 } / {2c^2 }}}}. We are inclined to think that the revealed deviation of ΔE/E from relativistic prediction cannot be explained by any instrumental error and thus represents a physical effect. In particular, we assume that the energy shift of the absorption resonant line is induced not only by the standard time dilation effect, but also by some additional effect missed at the moment, and related perhaps to the fact that resonant nuclei in the rotating absorber represent a macroscopic quantum system and cannot be considered as freely moving particles.