engleski

Neutron Dosimetry with the Chlorobenzene-Ethanol-Trimethylpentane Dosimetry

Neutron fields are characterized by the complexity of LET distributions caused by the presence of different secondary charged particles each in turn characterized by a spectrum of energies. In addition to that, neutron radiations are accompanied with various spectra of gamma rays. As far as personal dosemeters are concerned, their response has to be tissue equivalent, as closely as possible, irrespectively of the type of radiation and variability of its energy and LET distributions. This is why it is still a challenging task for neutron dosimetry to find a system capable to satisfy such high requirements. The chlorobenzene-ethanol-trimethylpentane (CET) chemical dosimetry system is currently used for dosimetry calibration work and as a basis for the accident and emergency personal dosemeter DL-M4. In the present work the results of determination of the radiation-chemical yield, G(HCl), for the CET system, as well as the response of DL-M4 in different neutron fields ranging from 0.35 to 19.3 MeV mean energy neutrons, are summarized. The relation of G(HCl) for the CET system to LET of incident heavy charged particles is also evaluated on the basis of the previously published data. It was found that the radiation-chemical yield, G(HCl), is nearly constant in neutron energy range from about 1.7 MeV to 14.5 MeV and equal to 0.39+-0.02 micromol J-1 (or 78% of the value for 60-Co gamma rays). Following this, the response to neutron tissue dose in the same energy range, relative to the same tissue dose of gamma radiation is nearly unity since the CET system contains 14.0% hydrogen, i.e. 4% more than ICRU muscle tissue. For neutrons of 19.3 MeV mean energy, the G value is 12% lower and equals to 0.35 micromol J-1. From the measured dependence of the G value upon LET of heavy charged particles and data about the LET distribution for monoenergetic neutrons, the response of the CET system to monoenergetic neutrons was calculated. A very good agreement between this calculation and the experimental results for neutrons was obtained. These results enable predictions of the response to be made in radiation fields with the known LET distributions.

Chlorobenzene-ethanol-trimethylpentane dosimetry system

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