The response of scintillators to very heavy ions.

A nano-second time-of-flight system incorporating thin scintillators as transmission detectors and a [252]Cf spontaneous fission source has been developed as a source of very heavy ions. The system is capable of discriminating against unwanted radiations by gating techniques. A study of the response of several scintillators to very heavy ions has been carried out. The total light output was measured as a function of energy and velocity for several scintillators. The variation of the specific luminescence with energy and velocity was investigated for a plastic transmission scintillator. The stopping power of the scintillators used and the effective ionic charge of the fission fragments studied have been calculated as a function of energy from interpolation of existing experimental data and from available theories. The existing theories concerning the response of scintillators to various particles have been tested in the light of the experimental results obtained. A new theory has been developed in order to explain the observed behaviour of the response of scintillators to very heavy ions. A comparison between this theory and the experimental results of this study has shown up the shape and magnitude of a "dark region" around the track of a fragment, which correlates well with the damage zones found for fission track detectors