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Title: The determination of the value W̄ for tissue equivalent media, the energy dependence of W̄ and the value for fission fragments from Cf-252
Author: Nutton, David H.
ISNI:       0000 0001 3450 8767
Awarding Body: University of Surrey
Current Institution: University of Surrey
Date of Award: 1979
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The application of the value W, the mean energy expended in the production of an ion-pair, to the ionometric dosimetry of neutron radiation as applied to radiotherapy is discussed. The concept of tissue equivalence is developed and the limitations of its application evaluated; The value of W for alpha particles from Americium-241 in several gases, including two tissue equivalent gases, were measured using a total ionisation current technique. The effect of a dependence of W upon energy, mass and charge is discussed. Protons in the energy range 300 kev to 1.7 MeV were used in order to evaluate any energy dependence of W in an Argon plus Methane gas mixture over that energy range. A dependence was observed, amounting to 17% at 500 Kev compared to the value at 1.7 MeV. Additionally an inversion in the trend as the energy was reduced below 450 KeV was observed. A high mass experiment is described using fission fragments from a Californium-252 source in an Argon plus Methane gas mixture.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available