NEUTRON DEPTH DOSE FROM ($alpha$, N) AND ($gamma$, N) SOURCES IN A TISSUE- EQUIVALENT PHANTOM.


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Neutron depth-dose behavior in tissue-equivalent phantom exposed to SbBe, PoLi, Po mock fission, and PuBe point sources was examined with respect to existing theoretical and experimental calculations. Dose from exposure to a point source of complex energy spectra can be esti-mated by applying a 1/r/sup 2/ geometric correction to the incident neutron flux and comparing the result with the known monoenergetic behavior of neutrons equivalent to the average energy of the point source neutrons. (auth).




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Helium


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Calculated and Measured Depth Dose Profiles in a Phantom Exposed to Neutron Radiation Fields


Book Description

An accurate evaluation of doses caused by external sources of neutron radiation depends on knowledge of the transport of radiation inside the human body. Health physicists use two primary methods for studying this radiation transport: computer calculations and measurements. Both computer calculations and measurements were performed under well controlled, nearly identical conditions to determine the extent of their agreement. A comparison of the dose profiles predicted by both measurements and calculations was thus possible. The measurements were performed in a cylindrical phantom made of tissue equivalent plastic. The phantom size, 61 cm high and 30 cm in diameter, was chosen to approximate the human torso and to match the dimensions of cylindrical phantoms used by previous calculations. Holes were drilled down through the phantom to accommodate small tissue equivalent proportional counters (TEPCs) at various depths in the phantom. These counters were used to measure the neutron dose inside the phantom when it was exposed to various sources of neutrons. The holes in the phantom could also accommodate miniature Geiger-Mueller detectors to measure the gamma component of the dose. Neutron and gamma dose profiles were measured for two different sources of neutrons: an unmoderated 252Cf source and a 733-keV neutron beam generated by a Van de Graaff accelerator. 14 refs., 13 figs., 11 tabs.