Miniball: A Gamma-Ray Spectrometer For Exotic Beams

The Miniball array has been developed to meet the new challenges set by the use of post-accelerated exotic-beam facilities. High efficiency is needed as the beam intensities are very low, but high granularity is needed to perform Doppler corrections when working with inverse kinematics. Miniball is the first of a new generation of spectrometer which uses segmentation of the outer electrode of a Ge detector, combined with pulse-shape analysis, to increase this granularity by about two orders of magnitude. Digital electronics have been used to perform on-line pulse-shape analysis. Miniball has been operational at the REX-ISOLDE facility at CERN since Easter.