Richtungskorrelation für Kernresonanzfluoreszenz und Lebensdauer des 412 keV-Niveaus von¹⁹⁸Hg

Abstract

Using the method of thermal Doppler-broadening of the emission line, the effective differential cross sections for nuclear resonance scattering for 412 keV photons by¹⁹⁸Hg has been measured for well defined scattering angles of 120° and 160°. The results indicate a partial mean lifetime for this energy level of τ_γ=(5·12±0·23)·10⁻¹¹ sec. This result differs appreciably from the values reported by other workers. Possible reasons for these discrepancies are discussed. The ratio of the differential cross sections for resonance scattering at angles of 120° and 160° is consistent with a 0-2-0 transition.