Response of nuclear emulsions to ionizing radiations

Abstract

Heavy ion tracks in Ilford K-2 emulsion are simulated with a computer program which makes use of the delta-ray theory of track structure, and the special assumption that the response of this emulsion to gamma-rays is 8-or-more hit. The Ilford K-series of nuclear emulsions is produced from a parent stock called K.O emulsion, sensitized to become K. 1 to K. 5, and desensitized to become K-1 to K-3. Our simulations demonstrate that the emulsions K. 5 through K. 0 to K-1 are 1-or-more hit detectors, while K-2 is an 8-or-more hit detector. We have no data for K-3 emulsion. It would appear that emulsions of intermediate hittedness might be produced by an intermediate desensitization, to mimic or match the RBE-LET variations of biological cells, perhaps to produce a “rem-dosimeter”. In the K-2 emulsion no developable grains are produced by stopping H, He, and Li ions. The emulsion has “threshold-like” properties resembling etchable track detectors. It should prove useful in the measurement of high LET dose in a strong low LET background, as for pions or neutrons. Since it can be expected to accumulate and repair “sub-lethal damage”, to display the ion-kill and gamma-kill inactivation modes, the grain-count and track width regimes, it may serve to model biological effects.