Neutron Dosimetry with Tissue Equivalent Proportional Counters: Their Limitations and How to Deal with Them
Conference
·
OSTI ID:786819
Low-pressure tissue equivalent proportional counters (TEPCs) are instruments that measure absorbed dose based on the Bragg-Gray cavity theory. By keeping the filling pressure low, the energy loss of individual charged particles crossing the detector cavity corresponds to the energy loss in tissue over distances of the order of a few micrometres. However, the efficacy of the TEPC as a meter for ambient dose equivalent H*(10) deteriorates rapidly below a few hundred keV, reflecting the differences between the TEPC and the artifact used in the definition of H*(10); the typical TEPC has walls roughly 1 to 2 mm thick, whereas H*(10) is defined at a point 10 mm below the surface of the 30-cm-diam ICRU sphere. Several laboratories have investigated approaches to improving the TEPC ambient dose equivalent response, but all have involved modifying the detectors themselves by increasing the wall thickness, reducing the filling pressure, altering the gas composition, or some combination there of. Each of these approaches has positive and negative aspects, but, generally speaking, improving an instrument's ambient dose equivalent response in one energy region tends to degrade the response in other regions. However, National Physical Laboratory has, for several years, been refining analytical methods for improving the H*(10) response of TEPCs, which essentially use the shape of the TEPC spectrum, and how it varies with neutron energy to determine a correction factor for the measured ambient dose equivalent. This is achieved by comparing the measured spectra to a catalog of theoretical spectra, generated by a Monte Carlo code developed by the author over many years.
- Research Organization:
- National Physical Laboratory, Teddington, Middlesex (GB)
- Sponsoring Organization:
- none (US)
- OSTI ID:
- 786819
- Report Number(s):
- none; ISSN 0003-018X; CODEN TANSAO; ISSN 0003-018X; CODEN TANSAO
- Country of Publication:
- United States
- Language:
- English
Similar Records
Neutron dosimetry at commercial nuclear plants: Final report of Subtask D: TEPC (tissue-equivalent proportional counter) feasibility
External gamma dose responses from residual radioactive materials in soil
Use of tissue equivalent proportional counters to characterize radiation quality on the space shuttle
Technical Report
·
Wed Oct 01 00:00:00 EDT 1986
·
OSTI ID:7149597
External gamma dose responses from residual radioactive materials in soil
Conference
·
Sat Dec 31 23:00:00 EST 1988
· Transactions of the American Nuclear Society; (USA)
·
OSTI ID:5233908
Use of tissue equivalent proportional counters to characterize radiation quality on the space shuttle
Conference
·
Tue Mar 31 23:00:00 EST 1992
·
OSTI ID:10140645