Title :
GAMMASPHERE-elimination of ballistic deficit by using a quasi-trapezoidal pulse shaper
Author :
Goulding, F.S. ; Landis, D.A. ; Madden, N. ; Maier, M. ; Yaver, H.
Author_Institution :
Lawrence Berkeley Lab., CA, USA
fDate :
8/1/1994 12:00:00 AM
Abstract :
Gammasphere uses an spherical array of very large (7.2 cm dia.) germanium detectors and only high-multiplicity events are studied. To achieve a reasonable coincidence rate, the individual detector channels must handle high rates with minimum pile-up losses. Ten microseconds was chosen as the total processing time for a signal which means that the shaped signal peaks in about 4 us. The combination of short pulse shaping and the fluctuating long charge collection times (up to 400 ns) in the detectors exaggerates the energy resolution degradation due to ballistic deficit effects. We describe a method of producing a flat-topped pulse with a simple time-invariant network that satisfies GAMMASPHERE requirements and eliminates ballistic deficit effects
Keywords :
coincidence circuits; detector circuits; nuclear electronics; pulse shaping circuits; scintillation counters; semiconductor counters; 10 mus; 4 mus; 400 ns; BiGeO; GAMMASPHERE; Ge; Ge detectors; ballistic deficit; coincidence rate; energy resolution degradation; flat-topped pulse; fluctuating long charge collection times; minimum pile-up losses; quasi-trapezoidal pulse shaper; shaped signal peaks; short pulse shaping; spherical array; time-invariant network; total processing time; Delay effects; Energy resolution; Gamma ray detection; Gamma ray detectors; Laboratories; Noise figure; Noise shaping; Pulse shaping methods; Signal processing; Spectroscopy;
Journal_Title :
Nuclear Science, IEEE Transactions on
