The Stopping Power of Various Substances for Low Energy Protons

Author: Bader, Michel

Year: 1955

Degree: Dissertation (Ph.D.)

Advisor: Whaling, Ward

Committee Member: Unknown, Unknown

Option: Physics; Mathematics

DOI: 10.7907/64N0-E240

Abstract

The stopping cross sections of several substances were measured for protons in the energy range 50 to 600 kev. The substances investigated were lithium, beryllium, copper, gold, lead, lithium fluoride and calcium fluoride.

The energy loss in the substance under investigation was determined by measuring the incident proton beam energy necessary for a given outgoing energy before and after a thin evaporated layer of the substance had been placed in the path of the beam. The areal density of the layer was accurately determined by one of two methods: A chemical analysis or a micro-balance weighing of a known area of the evaporated deposit. The same layer was used in the energy loss as in the density determinations. These absolute measurements were made near 350 kev. Relative energy loss measurements were made over the remainder of the range, and normalized to them. The apparatus was so designed that the evaporations, weighings and energy loss determinations could be performed without removing the substance from the vacuum.

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