Determinations of photon spectra. Master's thesis
A method is developed to unfold photon spectra from measurements obtained with a sodium iodide counting system. A response matrix is computed by combining photon cross sections with probability distributions of path lengths for incident and internally generated photons in the energy range 0-2.8 MeV. This matrix is inverted and multiplied by a measured pulse height spectrum to obtain the photon energy distribution incident upon the detector. This deconvolution procedure provides improved information about the energy continuum of incident photons and can enhanced the identification of discrete gamma energies. Experiments were performed to verify the unfolding methodology and to evaluate the feasibility and accuracy of this technique. Measured spectra were acquired from indoor and outdoor environments and unfolded. The results show that measured spectra overestimate the number of photons below 240 keV by up to 30 %. When the total exposure was calculated directly from the measured spectra, the low energy contribution was overestimated by a factor of two. This may have implications on the interpretation and calibration of energy dependent dosimeters used for occupational and environmental monitoring.
- Research Organization:
- Air Force Inst. of Tech., Wright-Patterson AFB, OH (USA)
- OSTI ID:
- 6943862
- Report Number(s):
- AD-A-218003/2/XAB; AFIT/CI/CIA-89-152
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DOSEMETERS
CALIBRATION
PHOTONS
SPECTRA
BIOLOGICAL DOSEMETERS
CALCULATION METHODS
COUNTING TECHNIQUES
CROSS SECTIONS
DISTRIBUTION FUNCTIONS
GAMMA RADIATION
HEIGHT
IODIDES
LENGTH
MATRICES
MONITORING
PULSES
RESPONSE FUNCTIONS
SODIUM
SODIUM IODIDES
ALKALI METAL COMPOUNDS
ALKALI METALS
DIMENSIONS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
ELEMENTS
FUNCTIONS
HALIDES
HALOGEN COMPOUNDS
INORGANIC PHOSPHORS
IODINE COMPOUNDS
IONIZING RADIATIONS
MASSLESS PARTICLES
MEASURING INSTRUMENTS
METALS
PHOSPHORS
RADIATIONS
SODIUM COMPOUNDS
440102* - Radiation Instrumentation- Radiation Dosemeters