TY - JOUR
T1 - "hERCULES"
T2 - Design, instrumentation, and performance characteristics of a high-efficiency evaporation-residue counter under a lot of elastic scattering for spectroscopic studies with Gammasphere
AU - Reviol, W.
AU - Sarantites, D. G.
AU - Charity, R. J.
AU - Chiara, C. J.
AU - Elson, J.
AU - Montero, M.
AU - Pechenaya, O. L.
AU - Ryu, S. K.
AU - Sobotka, L. G.
N1 - Funding Information:
The excellent craftsmanship of the staff of the Department of Chemistry Machine Shop at Washington University made the construction of HERCULES possible and is appreciated. The very valuable discussions with Dr. K.H. Maier (HMI) on the radiation damage of the scintillators and other design aspects are acknowledged. The authors also would like to thank Dr. R.V.F. Janssens (ANL) for making the tests at ATLAS possible, Dr. D. Seweryniak (ANL) for assistance during the experiments at ATLAS, Dr. C.J. Lister (ANL) for making available the Phillips fast amplifiers from the decommissioned APEX project, and Mr. J. Greene (ANL) for providing the targets. The help of Drs. A.O. Macchiavelli, P. Fallon, and M. Cromaz (LBNL) during the experiments with GAMMASPHERE is appreciated. This work was supported in part by the U.S. Department of Energy, Division of Nuclear Physics under grant No. DE-FG02-88ER-40406.
PY - 2005/4/11
Y1 - 2005/4/11
N2 - A high-efficiency evaporation-residue counter (named HERCULES) has been designed and constructed. It consists of 64 thin fast-plastic scintillators arranged in four rings covering an angular range of 3.1-19.1° at 30.9 cm from the target. The device design has been optimized for use with GAMMASPHERE. Evaporation residues are well separated from elastic scattering, fission events, and other undesirable reaction debris by time-of-flight and pulse-height analysis. Each detector element can operate at rates up to 0.5 MHz with signal recovery in about 10 ns. The geometry, construction, light-output characteristics, stability of the measured quantities, associated electronics, and in-beam performance of the device are described. For energy-degraded fission fragments with kinetic energies of less than 45 MeV, it is found that (1) the Z dependence of the pulse height disappears and (2) the light output per unit energy increases with decreasing energy. For evaporation residues from two reactions, in which the evaporation channels dominate and in which the residue cross-section is about 100 times smaller than the fission cross-section, angular distributions and sample γ-ray spectra are shown.
AB - A high-efficiency evaporation-residue counter (named HERCULES) has been designed and constructed. It consists of 64 thin fast-plastic scintillators arranged in four rings covering an angular range of 3.1-19.1° at 30.9 cm from the target. The device design has been optimized for use with GAMMASPHERE. Evaporation residues are well separated from elastic scattering, fission events, and other undesirable reaction debris by time-of-flight and pulse-height analysis. Each detector element can operate at rates up to 0.5 MHz with signal recovery in about 10 ns. The geometry, construction, light-output characteristics, stability of the measured quantities, associated electronics, and in-beam performance of the device are described. For energy-degraded fission fragments with kinetic energies of less than 45 MeV, it is found that (1) the Z dependence of the pulse height disappears and (2) the light output per unit energy increases with decreasing energy. For evaporation residues from two reactions, in which the evaporation channels dominate and in which the residue cross-section is about 100 times smaller than the fission cross-section, angular distributions and sample γ-ray spectra are shown.
KW - Evaporation-residue detection
KW - Fission background
KW - Light-output quenching
KW - γ-ray spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=15844388043&partnerID=8YFLogxK
U2 - 10.1016/j.nima.2004.12.028
DO - 10.1016/j.nima.2004.12.028
M3 - Article
AN - SCOPUS:15844388043
VL - 541
SP - 478
EP - 500
JO - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
JF - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
SN - 0168-9002
IS - 3
ER -