It. Cheon et al., OBSERVATION OF ENERGY-SHIFTED GAMMA-RAY ABSORPTION BY CS-133 NUCLEUS PLACED IN FINITE SPACE, Journal of the Physical Society of Japan, 63(7), 1994, pp. 2453-2457
We report the first reliable observation of the tiny shifts of energy
levels of a nucleus placed between two parallel metallic plates. We ob
served the absorption of the 81 keV gamma ray from Cs-133 induced by t
he beta-decay of Ba-133 in a BaTiO3 compound. This Mossbauer experime
nt was carried out at 4.2 K with the absorber placed between two silic
on plates with gold coating. The observed shifts are around 0.95 neV (
equivalent to 0.007 mm/s) for the distance of about 2 mm between the t
wo plates.