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MEASUREMENT OF STOPPING POWER OF COPPER BY CALORIMETRIC METHODS (thesis)

Technical Report ·
OSTI ID:4193596
The electron stopping power of copper was determined by measuring directly the power dissipated as heat in a copper foil by a transmitted beam of monoenergetic electrons. Monoenergetic electrons from an electron gun were accelerated by a linear accelerator and impinged normally on a 191.8 microgram per square centimeter copper foil. The electron beam was varied from 31.56 to 126.56 kev in steps of 10 kev, and the heating effect was determined at each energy. The power dissipated as heat was measured using a set of six copper- constantan thermocouples. The ratio of this power loss to the current of the electron beam passing through the foil gave the average energy loss, DELTA -barE- bar, for each incident energy. The thermocouple system was calibrated by lowering the beam energy below 2.5 kev so that the beam was completely absorbed in the foil. Foils were prepared by vacuum evaporation onto a water soluble coating on a glass slide. Details of technique of evaporation and mounting are given. The path length for the bombarding electrons corresponded to the foil thickness, DELTA -barx-bar, and was determined by weighing a known area (0.987 cm/sup 2/) of foil. Corrections were made for single and multiple scattering effects, and the stopping power was then given by the ratio DELTA -barE-bar/ DELTA -bar. The probable error was calculated and found to be 3.7%. For all energies examined agreement was found with Bethe's expression for electron stopping power. (auth)
Research Organization:
Oak Ridge National Lab., Tenn.
DOE Contract Number:
W-7405-ENG-26
NSA Number:
NSA-14-004607
OSTI ID:
4193596
Report Number(s):
ORNL-2775
Country of Publication:
United States
Language:
English