The recoil shadow anisotropy method

The Recoil Shadow Anisotropy Method (RSAM) is a new experimental method for identifying isomers in the nanosecond range and measuring their half-lives . This method can be applied to experiments performed with thin targets and gamma -ray multidetector arrays including collimated composite detectors a nd does not require any additional device. It uses the shadow effect impose d by the collimators on the different elements of composite detectors for g amma -rays emitted by recoiling nuclei. RSAM was developed for the clover d etectors of the Eurogam-2 array and tested using several data sets obtained with this array. A number of known isomers with half-lives lying between 0 .9 and 18 ns in Hg-194, Au-191, Gd-148, Gd-149, Pb-193 and Pb-194 have been successfully re-measured, proving the ability of RSAM for lifetime measure ments. (C) 2001 Elsevier Science B.V. All rights reserved.