Multiple Coulomb Excitation Techniques

The following three techniques have been developed that exploit Gammasphere to study high-fold γ-ray events providing an enormous advance in selectivity and sensitivity for Coulomb excita-tion studies. 1) CHICO detects the ions recoiling out of a thin target in coincidence with the deexcitation γ-rays by Gammasphere. This allows detection of the highest possible spin following Coulomb excitation, e.g spin 40 in 238U [1]; it provides useful low-fold information, and the measured γ-ray yields provide a reliable and sensitive measure of the Eλ matrix elements. The disadvantage is that the γ-ray lines are slightly Doppler broadened due to the finite granularity of Gammasphere. This broadening will be reduced by a factor of four using Gretina plus SuperCHICO. For example, see [2,3,4,5,6]. 2) The thick-target unsafe Coulonb excitation technique developed by Ward [7], does not suffer from Doppler broadening of the γ-ray lines but it is limited to study of longer lived states, i.e. lower spin states, due to the finite stopping time of recoiling ions in the thick target. High-fold events in Gammasphere are used to select collective bands and the γ-ray lines for states that decay after the recoils stop in the thick target to achieve the full energy resolution. This approach complements th