Two-stepγcascades following thermal neutron capture inGd155,157

Abstract

Spectra of two-step $\ensuremath{\gamma}$ cascades following neutron capture in $^{155,157}\mathrm{Gd}$ are measured using the two-Ge-detector facility installed at the thermal neutron beam of the research reactor LVR-15 at \ifmmode \check{R}\else \v{R}\fi{}e\ifmmode \check{z}\else \v{z}\fi{}. The main objective of this experiment is to obtain new information on photon strength functions, with the emphasis on the role of $M1$ scissors-mode vibration. An analysis of accumulated $\ensuremath{\gamma}$-ray spectra, made within the statistical model, leads to the conclusion that the scissors mode significantly affects $\ensuremath{\gamma}$ decay of all states of studied nuclei. Experimental data are compared to photon strength functions deduced from other experiments. Agreement of our results with those obtained from DANCE measurement of $\ensuremath{\gamma}$ spectra following resonance neutron capture is obtained.