A SIMPLE CALIBRATION AND CHECKING FACILITY FOR FAST AND SLOW NEUTRON DETECTORS

Technical Report · Wed Jan 28 04:00:00 EST 1959

OSTI ID:4241003

Redmond, A H

A simple facility is described for checking the sensi-tivity of dose rate instruments for fast neutron detection, and for calibration of thermal neutron detectors. About 7 million plutonium-beryllium neutrons per second give a tolerance flux density of slow neutrons from the walls of a cavity in paraffin or water. Construction drawings of the cavity are given, and for the dimensions specified the constant is given for converting any plutonium-beryllium flux of neutrons to combined thermal and epithermal flux densities, so that instruments can be calibrated in standard flux densities. The fast neutron dose rate detectors use the same source, whieh has been shown to be equivalent to a polonium-beryllium source of the same strength, for a scnsitivity check. A modified procedure using the source in the cavity is shown to give a somewhat lower flux of fast neutrons on the detector, but a rapid check can be made without setting up the source in air. Measurements around the cavity with an additional insert of three inch-thick paraffin surrounding the source-holding tube show that the dose rate from fast neutrons around the cavity used for source storage is less than that around the original shipping container at comparable distances. The slow neutron flux density around the cavity during storage is negligible. (auth)

• Research Organization: Naval Radiological Defense Lab., San Francisco
• NSA Number: NSA-13-012596
• OSTI ID: 4241003
• Report Number(s): USNRDL-TR-302
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

AIR
BERYLLIUM
CONFIGURATION
ENERGY RANGE
FAST NEUTRONS
INSTRUMENTS
MEASURED VALUES
NEUTRON DETECTION
NEUTRON SOURCES
PARAFFIN
PLUTONIUM
RADIATION DETECTORS
SENSITIVITY
STANDARDS
TESTING
THERMAL NEUTRONS
WATER