Observation of intensified forward γ-ray emission in spontaneous nuclear decay
Shvyd'ko Yu.V., Smirnov G.V., Popov S.L., Hertrich T.
A nuclear target which is an essentially black absorber for resonant χ-ray emission becomes a strong emitter of γ rays in the forward direction after irradiation of this target is ended abruptly. A magnetic-resonance device was used to chop a y-ray beam in order to observe this effect. The operating time of this chopper is much shorter than the time scale of the spontaneous decay of the excited nuclear state.