Neutron dosimetry with spherical cavity ionization chambers
Thesis/Dissertation
·
OSTI ID:5675599
Succesive steps in the conversion of Q into dose: (1) The energy W needed to produce one ion pair is used to convert Q into dose D/sub g/ in the gas. (2) The dose D/sub W/ in the wall of the ionization chamber is obtained with the dose conversion factor r, which is derived from the stopping powers of the wall and the gas. (3) The ratio of the kermas of the material and the wall is used to obtain absorbed dose in that material are considered. Most of the calculated results show reasonable agreement with the experiments. There is a simple relationship between Q,r, and W: q/m =K/sub w/ (rW) where m is the mass of gas in the ionization chamber. Q,r, and W are calculated for spherical ionization chambers. The most important result of this work is the cavity size dependence (measured in areal density) of q/m. The neutron sensitivity k/sub u/ can be obtained from this information. Cavities in tissue equivalent materials filled with either tissue equivalent gas(TE/TE) or air (TE/air) and graphite chambers filled with carbon dioxide (C/CO/sub 2/) are studied. Chamber sizes ranging from the Bragg-Gray case (infinitesimal) to the infinite cavity are considered. Results for finite cavities of .01, .1, 1, and 10 cm/sup 3/ are given for neutron energies from 0.4 to 14 MeV. Several energies which show strong resonances for the production of heavy charged particles are considered. The experimental part of this thesis studies the cavity size dependence of the ionization chambers described above in three different neutron spectra. Most of the calculated results show reasonable agreement with the experiments.
- Research Organization:
- Washington Univ., Seattle (USA)
- OSTI ID:
- 5675599
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
440102* -- Radiation Instrumentation-- Radiation Dosemeters
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
CARBON
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CONFIGURATION
DATA
DOSE EQUIVALENTS
DOSIMETRY
ELEMENTAL MINERALS
ELEMENTS
ENERGY DEPENDENCE
EXPERIMENTAL DATA
FLUIDS
GASES
GRAPHITE
INFORMATION
IONIZATION CHAMBERS
MEASURING INSTRUMENTS
MINERALS
NEUTRON DOSIMETRY
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
RADIATION DETECTORS
SIZE
SPHERICAL CONFIGURATION
THEORETICAL DATA
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
CARBON
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CONFIGURATION
DATA
DOSE EQUIVALENTS
DOSIMETRY
ELEMENTAL MINERALS
ELEMENTS
ENERGY DEPENDENCE
EXPERIMENTAL DATA
FLUIDS
GASES
GRAPHITE
INFORMATION
IONIZATION CHAMBERS
MEASURING INSTRUMENTS
MINERALS
NEUTRON DOSIMETRY
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
RADIATION DETECTORS
SIZE
SPHERICAL CONFIGURATION
THEORETICAL DATA