Performance of low pressure tissue equivalent chambers and a new method for parameterizing the dose equivalent

Technical Report · Mon Sep 01 04:00:00 EDT 1986

DOI:https://doi.org/10.2172/5339402· OSTI ID:5339402

Eisen, Y; Vasilik, D G; Brake, R J; Erkkila, B H; Littlejohn, G J

The performance of spherical tissue equivalent chambers with equivalent diameters between 0.5 and 2..mu.. was tested experimentally using monoenergetic and polyenergetic neutron sources in the energy region of 10 keV to 14.5 MeV. Theoretical calculations were performed in order to obtain a simple algorithm for deriving the dose equivalent from the measured data. The algorithm relates the number of recoil particles to the dose equivalent, rather than having a one-to-one correspondence between the lineal energy and the linear energy transfer of the recoil particles. The calculations took into account neutron interactions with hydrogen atoms in the chamber wall as well as in the gas, and also the finite energy resolution determined by both the detector and the electronic system. Qualitatively, the calculations well dscribe the experimental results. The algorithm that was developed determines the neutron dose equivalent, from the data of the 0.5..mu.. chamber, to better than +-20% over the energy range of 30 keV to 14.5 MeV. The same algorithm also determines the dose equivalent from the data of the 2..mu.. chamber to better than +-20% over the energy of 70 keV to 14.5 MeV. The efficiency of the chambers is low and has an average value of 330 counts per mrem, or equivalently about 0.2 c/s per mrem/h. This efficiency enables the measurement of dose equivalent rates only above 100 mrem/h for an integration period of 3 seconds. However, integrated dose equivalents can be mesured as low as 0.1 mrem.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5339402
• Report Number(s): LA-10770-MS; ON: DE87000802
• Country of Publication: United States
• Language: English

Related Subjects

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ALGORITHMS
DOSE EQUIVALENTS
ENERGY TRANSFER
LET
MATHEMATICAL LOGIC
MEASURING INSTRUMENTS
NEUTRON SOURCES
PARTICLE SOURCES
PERFORMANCE
RADIATION DETECTORS
RADIATION SOURCES
TISSUE-EQUIVALENT DETECTORS