Photofractions for sodium iodide crystals

Journal Article · Sun Jan 01 00:00:00 EST 1961 · Nuclear Instruments and Methods

DOI:https://doi.org/10.1016/0029-554X(61)90028-3· OSTI ID:4021294

Kreger, W. E.; Brown, R. M.

Measurements of the pulse-height spectra obtained from large crystal Nal(Tl) scintillation spectrometers exposed to monoenergetic gamma rays are used to determine the photofractions (ratio of total-absorption peak area to total spectrum area) for the crystals. The Nal crystals used have geometries such as 4 inch diameter by 4 inch long; 5 inch diameter by 6 inch long with a 3/4 inch diameter by 1 1/2 inch deep well drilled in the end; and 9 3/8 inch diameter by 8 5/8 inch long with a 3/4 inch diameter by 2 1/2 inch deep well drilled in the end. The units are exposed to collimated monoenergetic gamma rays from 0.279 Mev to 2.76 Mev. The dependence of photofraction value on gamma-ray beam diameter is determined for the 4 inch by 4 inch crystal. The photofraction values are fitted to an empirical relationship involving crystal radius and length, with three gamma-ray energy dependent parameters as fitting variables.

• Research Organization: Naval Radiological Defense Lab., San Francisco
• Sponsoring Organization: USDOE
• NSA Number: NSA-15-024995
• OSTI ID: 4021294
• Journal Information: Nuclear Instruments and Methods, Vol. 11, Issue C; Other Information: Orig. Receipt Date: 31-DEC-61; ISSN 0029-554X
• Publisher: Elsevier
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

42 ENGINEERING
BEAMS
CRYSTAL COUNTERS
ENERGY LEVELS
GAMMA RADIATION
MEASURED VALUES
MONOCHROMATORS
PULSE ANALYZERS
SCINTILLATION COUNTERS
SODIUM IODIDES
THALLIUM