RESUMO
A compact liquid organic neutron spectrometer based on a single NE213 liquid scintillator (5 cm diameter x 5 cm) is described. The spectrometer is designed to measure neutron fluence spectra over the energy range 2-200 MeV and is suitable for use in neutron fields having any type of time structure. Neutron fluence spectra are obtained from measurements of two-parameter distributions (counts versus pulse-height and pulse shape) using the Bayesian unfolding code MAXED. Calibration and test measurements made using a pulsed neutron beam with a continuous energy spectrum are described and the application of the spectrometer to radiation dose measurements is discussed.
Assuntos
Nêutrons , Compostos Orgânicos/química , Compostos Orgânicos/efeitos da radiação , Radiometria/instrumentação , Radiometria/métodos , Análise Espectral/instrumentação , Desenho de Equipamento , Análise de Falha de Equipamento , Miniaturização , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , SoluçõesRESUMO
A NE230 deuterated liquid scintillator detector (25 mm diameter x 25 mm) has been used to investigate neutron energy spectra as a function of position in a water phantom under irradiation by a quasi-monoenergetic 64 MeV neutron beam. Neutron energy spectra are obtained from measurements of pulse height spectra by the NE230 detector using the Bayesian unfolding code MAXED. The experimentally measured energy spectra are compared with spectra calculated by Monte Carlo simulation using the code MCNPX.
Assuntos
Nêutrons , Monitoramento de Radiação/instrumentação , Proteção Radiológica/instrumentação , Contagem de Cintilação/instrumentação , Análise Espectral/instrumentação , Água/química , Desenho de Equipamento , Análise de Falha de Equipamento , Doses de Radiação , Monitoramento de Radiação/métodos , Proteção Radiológica/métodos , Reprodutibilidade dos Testes , Espalhamento de Radiação , Contagem de Cintilação/métodos , Sensibilidade e Especificidade , Análise Espectral/métodosRESUMO
High-resolution neutron fluence spectra have been measured in the National Accelerator Centre's p(66)/Be(40) neutron therapy beam by the pulsed-beam time-of-flight method. ICRU muscle kerma spectra have been derived from the fluence spectra. Spectral changes resulting from different irradiation conditions have been quantified in terms of the average neutron energy and the fractional low-energy (< 16 MeV) contribution. The changes observed with different thicknesses of polyethylene filtration are consistent with changes in quality parameters determined in biological and microdosimetric experiments. The dosimetry parameters (KtissueA150) N and (Wgas) N calculated for the measured spectra agree with the values recommended in the neutron dosimetry protocol. The shapes of the present fluence spectra differ from previous measurements of p(> 40)/Be spectra. In particular, they differ significantly from the spectrum measured by recoil techniques in an identical neutron therapy unit at the Clatterbridge Hospital, UK. The reasons for the difference are not known.