Particle selection using CsI(Ti) crystals and associated experiments on the luminescence of alkali halide crystals

Robertson, James C (1961) Particle selection using CsI(Ti) crystals and associated experiments on the luminescence of alkali halide crystals. PhD thesis, University of Glasgow.

Abstract

The study of n-alpha reactions has been greatly impeded by the lack of suitable counting techniques. The major experimental difficulty in making such a study is to discriminate between the alpha particles and protons which are emitted simultaneously from n-p reactions. Also, measurements on n-p reactions using electronic techniques have been limited to protons of energy greater than 4 MeV due to the very intense electron backgrounds produced in the detector. It is desirable to make measurements on n-alpha reactions and to extend the measurements on n-p reactions to lower energies, since such measurements would yield important information about the mechanism of such neutron induced reactions. Part I of this thesis entitled:- "Particle Selection using CsI(T1) Crystals", gives a description of a novel form of scintillation counting which makes such measurements possible. This technique utilises the fact that the decay time of the luminescence produced in a CsI(T1) crystal is dependent on the ionization density produced by the particle giving rise to the luminescence, and hence on the nature of the particle. Electronic circuits have been designed and constructed which effectively inspect the decay time of the luminescence produced in a OsI(T1) crystal and thereby effect discrimination between the different types of particle producing the luminescence. In this way the elimination of the unwanted backgrounds produced in a CsI(T1) crystal, when it is used as the detector in neutron experiments, has been achieved. In Part II of this thesis entitled:- "Associated Experiments on the Luminescence of Alkali Halide Crystals", several experiments are described which it was hoped might have improved the technique described in Part I. Firstly a systematic search was made in the hope of finding a crystal in which the decay time of the luminescence was more dependent on ionization density. The decay times of the luminescence produced in LiI(Eu), NaI(T1), KI(T1) and CsBr(T1) by particles producing different ionization densities were measured. The dependence of the luminescent efficiencies, Ealpha,p,e, on ionization density was also examined. (The subscripts denote alpha particles, protons and electrons respectively). In a second experiment, the dependence on thallium concentration in CsI(T1) of the luminescent efficiencies, Ealpha,p,e, and the decay times of the luminescence produced by different particles has been examined. Finally the luminescent efficiencies and the decay times of the luminescence in CsBr(T1) and CsI(T1) have been studied as a function of temperature in the range -150

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: P I Dee
• Keywords: Nuclear physics and radiation
• Date of Award: 1961
• Depositing User: Enlighten Team
• Unique ID: glathesis:1961-73587
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jun 2019 08:56
• Last Modified: 14 Jun 2019 08:56
• URI: https://theses.gla.ac.uk/id/eprint/73587