Observation of the 22.5-keV resonance in Sm-149 by the nuclear lighthouse effect - art. no. 047601

We have observed coherent nuclear resonant scattering of synchrotron radiat ion at the 22.5-keV resonance of Sm-149. High-speed rotational sample motio n led to an angular deflection of the resonantly scattered radiation off th e nonresonant primary beam. This allowed us to determine the resonance ener gy of the first excited nuclear level of Sm-149 to be 22496(4) eV. Because of the angular deflection of the resonant photons, time spectra of coherent nuclear resonant scattering can be recorded as a function of a spatial coo rdinate. Time resolutions of a few 10 ps can be expected, which are beyond the limits of existing x-ray detection schemes.