MEASUREMENT OF SPECTRAL DISTRIBUTION OF POSITRON FLUX IN AN INFINITE COPPER MEDIUM CONTAINING Cu$sup 64$ (thesis)

Technical Report · Tue Dec 24 04:00:00 EST 1963

DOI:https://doi.org/10.2172/4108255· OSTI ID:4108255

Wilkie, W. H.; Birkhoff, R. D.

The spectral distribution of the flux of positrons inside a beta radioactive medium was experimentally determined using an anthracene coincidence scintillation spectrometer. Positrons leaving a copper cavity source containing Cu/sup 64/ were absorbed in a thin anthracene crystal. The light pulse from the anthracene was recorded in a 256 channel analyzer if a NaI scintillation spectrometer nearby recorded simultaneously a count under the total absorption peak for annihilation radiation. Thus, discrimination against negative and secondary electrons was obtained which permitted observation of the primary positron slowing down flux. Data were corrected for the non-linear pulse height vs energy relationship in anthracene by a semi-empirical theory due to Birks, the validity of which was demonstrated by its use in obtaining a linear Fermi plot of Pm/sup 147/. Positron spectra were corrected also for Compton absorption of the annihilation radiation in the anthracene. Results were compared with the theoretical continuous-slowing-down model. Over the energy range measured (20-- 650 kev) it was concluded that the continuous-slowing-down model gives the correct shape for the primary slowing-down spectrum. 43 references. (auth)

• Research Organization: Oak Ridge National Lab., Tenn.
• DOE Contract Number: W-7405-ENG-26
• NSA Number: NSA-18-007688
• OSTI ID: 4108255
• Report Number(s): ORNL-3469
• Country of Publication: United States
• Language: English

Related Subjects

ABSORPTION
ANNIHILATION
ANTHRACENE
BEAMS
BETA DECAY
BETA PARTICLES
BIBLIOGRAPHY
COINCIDENCE METHODS
COMPTON EFFECT
COPPER 64
CRYSTALS
DISTRIBUTION
ELECTRONS
ENERGY RANGE
FERMI PLOT
KEV RANGE
MEASURED VALUES
PARTICLE SOURCES
PHYSICS
POSITRONS
PROMETHIUM 147
PULSES
RADIOACTIVITY
RECORDING SYSTEMS
SCINTILLATION COUNTERS
SLOWDOWN
SPECTRA
SPECTROMETERS
THICKNESS