Instrumentation for fission fragment energy correlation experiments

Abstract

Experiments have been performed at the Oak Ridge National Laboratory in which the kinetic energies of correlated fragment pairs from thermal- and resonance-neutron-induced fission have been measured. In addition, a three-parameter ternary fission experiments has been performed in which the energies of correlated fragments were measured in coincidence with the energy of a third emitted particle, usually a longrange alpha particle. The detectors were large-area silicon surface barrier detectors. The instrumentation associated with these experiments is discussed in detail. The complete system is described, with attention given to the problems of background reduction (fast-coincidence requirements), stability, linearity and resolution. Particular attention is given to the reduction of spectrum distortion by pile-up pulses, e.g., alpha-on-fission pile-up within the amplifier resolving time. Methods and limitations of pile-up detection are discussed. A new method for inspection and removal of pile-up pulses, which may be useful in a wide variety of applications, is presented.