Sub-picosecond lifetimes from Doppler-shift attenuation measurements following (α,2p) and (α,pn) reactions of 54Fe in singles experiments

Abstract

A procedure is described by which the Doppler-shift attenuation technique is extended to measurement of nuclear-level lifetimes from single experiments following two-nucleon emitting reactions. It is shown that in reactions such as (α,pn) and (α,2p) it is possible to obtain sub-picosecond lifetimes from the careful measurement at several bombardment energies of the line shapes and centroid shifts of γ-rays near and above the threshold for the levels of interest. The values of (100±15) fs, (580±60) fs, and (180±30) fs, (490±50) fs were obtained for the mean lifetimes of levels at 3638.1, 4180.4 keV in 56Co, and 3755.8, 5255.5 keV in 56Fe, respectively.