RoSiB - a 4 pi silicon ball for charged-particle detection in EUROBALL

Citation
G. Pausch et al., RoSiB - a 4 pi silicon ball for charged-particle detection in EUROBALL, NUCL INST A, 443(2-3), 2000, pp. 304-318
Citations number
20
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences","Instrumentation & Measurement
Journal title
NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT
ISSN journal
0168-9002 → ACNP
Volume
443
Issue
2-3
Year of publication
2000
Pages
304 - 318
Database
ISI
SICI code
0168-9002(20000401)443:2-3<304:R-A4PS>2.0.ZU;2-G
Abstract
A 4 pi silicon bail for detection and identification of light charged parti cles in large multidetector gamma-arrays as EUROBALL is presented. The desi gn is based on a N = 42 ball with 12 pentagons and 30 hexagons as used in t he GASP array. The absorptive material for gamma-rays is minimized to the d etector thickness of 300 or 500 mu m and a 0.63 mm ceramic backing. The geo metrical coverage is designed for about 90% of 4 pi. A pulse shape discrimi nation method with totally depleted detectors working in the reverse mount allows identifying protons and alpha-particles above an energy threshold of about 2 MeV. The performances of the ball were rested at the tandem - boos ter accelerator combination of the MPI Heidelberg in two experiments using the high-recoil reaction of 228 MeV Ni-58 + Ti-46 and the low-recoil reacti on of 95 MeV O-16 + Ni-58. The two-dimensional spectra of zero-crossing (ZC ) versus energy confirmed an excellent discrimination of protons and alpha- particles in all the detectors at different angles. The energy spectra of p rotons and alpha-particles measured in the experiments are presented. too. The gamma-spectra measured in coincidence with various combinations of emit ted particles showed a high selectivity of the ball. The reduced total effi ciency for protons of 59% and 55% and alpha-particles of 44% and 32% measur ed in a nuclear spectroscopy application is analyzed in a Monte-Carlo simul ation (GEANT). It is due to a combined influence of a thick target needed t o stop the recoiling residual nuclei and thick absorbers needed to protect the Si-detectors from scattered beam. The results along with the GEANT extr apolation to optimum experimental conditions confirm that RoSiB is a highly efficient and selective device for identification of rare reaction channel s with heavy ions. (C) 2000 Elsevier Science B.V. All rights reserved.