A realistic torso phantom with average body size of Japanese adult males has been developed for the calibration of counting systems used for in-vivo measurements of plutonium and other actinides. The phantom contains removable model organs (lungs, liver, kidneys and heart), model trachea and artificial rib cage, and also includes chest plates that can be placed over the chest to simulate wide range adipose/muscle ratio in the human chest.Tissue substitutes used in the phantom were made of polyurethane with different concentrations of ester of phosphoric acid. Model lungs were made of foamed polyurethane with small quantities of the additive, and the artificial rib cage was made of epoxy resin with calcium carbonate. The experimental data have shown that the phantom can be used as a standard phantom for the calibration.

A realistic torso phantom with average body size of Japanese adult males has been developed for the calibration of counting systems used for in-vivo measurements of plutonium and other actinides. The phantom contains removable model organs (lungs, liver, kidneys and heart), model trachea and artificial rib cage, and also includes chest plates that can be placed over the chest to simulate wide range adipose/muscle ratio in the human chest.Tissue substitutes used in the phantom were made of polyurethane with different concentrations of ester of phosphoric acid. Model lungs were made of foamed polyurethane with small quantities of the additive, and the artificial rib cage was made of epoxy resin with calcium carbonate. The experimental data have shown that the phantom can be used as a standard phantom for the calibration.

No abstract

The sensitivity was obtained by solving a multi-group diffusion equation and by the experiment using monoenergetic neutrons. The neutron energies used were over the range of 0.625 eV to 10 MeV in the calculation and 5 KeV to 6 MeV in the experiments. Moderator thicknesses were 2.7, 4.7, 6.7, 7.9, 11.0 and 14.7 cm in the calculation, and 3.5, 4.5, 6.5, 8.5 and 14.0 cm in the experiments. The results show a good agreement between the experimental and theoretical sensitivities for the energies above 200 KeV, while slight discrepancies appear below this energy.

Neutron spectra and dose equivalent rates were measured with a BF3 proportional counter covered with two, three or five of 0-, 3.5-, 4.5-, 6.5-, 8.5- and 14.0-cm-thickness paraffin moderators. The dose equivalent rates were also measured with a “Remcounter” having two detectors, one of which consists of a BF3 counter centered in 30-cm-diameter paraffin cylinder and the other of three BF3 counters embeded at intervals of 120 degrees along a coaxial 16-cm-diameter cylinder in the same paraffin moderator. The obtained dose equivalent rates for neutrons from a RaD-Be source did not differ by more than 22 per cent from the theoretical values given in the paper II, even when the measured spectra had large negative values at some energy.