STATISTICAL FLUCTUATIONS IN THE ENERGY LOSS OF 5.8 MEV ALPHA PARTICLES PASSING THROUGH AN ABSORBER OF VARIABLE THICKNESS

摘要

The frequency distributions of energy losses incurred by 5.8 Mev alpha particles traversing a thin absorber of variable thickness were determined experimentally. The measurements were performed with a proportional counter designed to allow a selected portion of the counting gas to serve as the absorber. The important distinction between the amount of energy lost by the ionizing particle in a given traversal of the absorber as compared to the energy deposited in the absorber is discussed and a method described which allows the measurement of the fluctuations of both types of events. The experi mental results are presented as frequency distributions of both energy loss and energy deposition for a series of operating conditions in which the average alpha-particle energy losses varied from 90. 8kevto3. 02 kev. In order to allow comparison between the experi mental results and theory, the problem of counter Kesolution had to be examined in detail. This was done in an experimental study, utilizing monoenergetic x-rays, the results of which are described. The measured energy loss distributions are compared, after properly taking into account the counter resolution, with the theory of Symon, which has for its limiting cases the theories of Bohr and Landau. General agreement between experiment and the Symon theory is good and somewhat improved when a small correction is applied to the theoretical calculations.