Doppler-broadened γ-ray lineshape analysis in multiple Coulomb excitation

Abstract

A procedure is described for extracting nuclear lifetimes from the Doppler-broadened γ-ray lineshapes in multiple Coulomb excitation. It is shown that in the region of deformed nuclei the statistical tensors calculated using rotational matrix elements according to the Winther-de Boer multiple Coulomb excitation computer programme give a lineshape practically independent of the values of the matrix elements used because the inelastic particle angular distribution remains virtually unchanged for variations of about 20% in the values of the matrix elements concerned. It is found that for high recoil velocities (up to 6.5% of the velocity of light) better fits to the experimental lineshapes are obtained using Northcliffe-Schilling electronic stopping power data coupled with Lindhart, Scharff and Schiott (LSS) theoretical nuclear stopping power, compared to those produced using LSS theoretical stopping powers only. The procedure we have used also takes into account the effects of multiple nuclear scattering, photon aberration, and the change in detection efficiency of Ge(Li) with the Dopper shift. Extracted lifetimes of several Coulomb excited states are compared with those independently reported and are found to be in good agreement with them.