Measurement of energy deposition distributions produced in cylindrical geometry by irradiation with 15 MeV neutrons
Cellular survival experiments have shown that the biological damage induced by radiation depends on the density of energy deposition along the trajectory of the ionizing particle. The quantity L is defined to measure the density of energy transfer along a charged particle's trajectory. It is equal to sigma/l, where sigma is the energy transferred to a medium and l is the path length along which the transfer takes place. L is the stochastic quantity whose mean value is the unrestricted linear energy transfer, L/sub infinity/. Measurements of the distribution of L in a thin medium by secondary charged particles from fast neutron irradiation were undertaken. A counter operating under time coincidence between two coaxial cylindrical detectors was designed and built for this purpose. Secondary charged particles enter a gas proportional counter and deposit some energy sigma. Those particles traversing the chamber along a radial trajectory strike a CsI scintillator. A coincidence between both detectors' signals selects a known path length for these events, namely the radius of the cavity. Measurements of L distributions for l = 1 ..mu..m in tissue were obtained for 3 and 15 MeV neutron irradiation of a tissue-equivalent target wall and for 15 MeV neutron irradiation of a graphite wall. Photon events were corrected for by measurements with a Pb target wall and 15 MeV neutron irradiation as well as exposure to a pure photon field. The measured TE wall distributions with 15 MeV neutron bombardment show contributions from protons, ..cap alpha..-particles, /sup 9/Be and /sup 12/C recoils. The last three comprise the L distribution for irradiation of the graphite wall. The proton component of the measured L distributions at 3 and 15 MeV was compared to calculated LET distributions.
- Research Organization:
- Wisconsin Univ., Madison (USA)
- OSTI ID:
- 6088079
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GRAPHITE
NEUTRON DOSIMETRY
DEPTH DOSE DISTRIBUTIONS
TISSUE-EQUIVALENT MATERIALS
ALPHA PARTICLES
DISTRIBUTION
ENERGY ABSORPTION
IRRADIATION
MEV RANGE 01-10
MEV RANGE 10-100
NEUTRONS
PROTONS
RECOILS
ABSORPTION
BARYONS
CARBON
CHARGED PARTICLES
DOSIMETRY
ELEMENTAL MINERALS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY RANGE
FERMIONS
HADRONS
MATERIALS
MEV RANGE
MINERALS
NONMETALS
NUCLEONS
RADIATION DOSE DISTRIBUTIONS
SPATIAL DOSE DISTRIBUTIONS
655003* - Medical Physics- Dosimetry