AbstractsPhysics

Proton induced fission of uranium

by Kenneth Cecil Maclure




Institution: McGill University
Department: Department of Physics.
Degree: MS.
Year: 1950
Keywords: Physics.
Record ID: 1554022
Full text PDF: http://digitool.library.mcgill.ca/thesisfile122831.pdf


Abstract

Ilford Nuclear type plates loaded with uranyl acetate were exposed to 78 Mev. protons inside the vacuum chamber of the McGill cyclotron, and tracks from the resulting uranium fissions observed under high magnification. Bathing the plates in a very weak solution of chromic acid before development materially reduced the background of alpha tracks from the spontaneous disintegration of uranium and of fog due to the proton beam. A concentration of 0.13 mgms. of CrO3 per ml. of water inhibited development of the proton and alpha tracks, but left the fission tracks quite dense. Fission tracks in these plates appeared similar to those in equivalent plates exposed to thermal neutrons from the Chalk River pile. Detailed examination of a sample section of one of the former plates showed a density of 50 fissions per cm2, whose median total range was 23 microns, agreeing with published results for slow neutron fission. A rough estimate of the fission cross-section of uranium to protons of 2.0 x 10^-24 cm was obtained, appearing to be too great by a factor of about four. The main cause of this error was believed to be due to inaccuracy in measuring the density of the proton beam.