RESUMO
A 2-D tissue-equivalent sheet-type dosemeter (NTL sheet) was developed using thermoluminescent material of LiF:Mg,Cu,P (NTL-250). The energy responses of the NTL sheet and NTL-250 powder were measured with 10-150 keV monoenergetic photons from synchrotron radiation at SPring-8. The sample was irradiated by a rotational method for the uniform irradiation with the narrow beam. Linearity of the NTL-250 was confirmed up to 2 Gy. Energy responses of the NTL sheet and NTL-250 powder were close to that of soft tissue. On the other hand, the BaSO(4) sheet, which has been used practically, showed the response that the sensitivity approximately 60 keV was 100 times higher than that for (60)Co gamma rays. Therefore the NTL sheet can be said to have excellent properties for dose measurements.
Assuntos
Fluoretos/química , Fluoretos/efeitos da radiação , Transferência Linear de Energia , Compostos de Lítio/química , Compostos de Lítio/efeitos da radiação , Fótons , Dosimetria Termoluminescente/instrumentação , Cobre/química , Cobre/efeitos da radiação , Relação Dose-Resposta à Radiação , Desenho de Equipamento , Análise de Falha de Equipamento , Magnésio/química , Magnésio/efeitos da radiação , Teste de Materiais , Fósforo/química , Fósforo/efeitos da radiação , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Dosimetria Termoluminescente/métodosRESUMO
A (6)LiF-rich thermoluminescent sheet-type dosemeter ((6)LiF-rich NTL sheet) was developed for neutron 2D dosimetry. The dosemeter utilises the (6)Li(n, alpha)(3)H reaction to detect thermal neutrons. Responses of the (6)LiF-rich NTL sheet to neutrons were measured at the neutron beam irradiation facility for BNCT in JRR-4 Research Reactor at the Japan Atomic Energy Research Institute. Placement of a multi-leaf collimator at the output port of the neutron (beam) irradiation facility, produced either stripe- or round-shaped neutron distributions; the spatial distribution was measured using the developed NTL sheets. Direct measurements of neutron attenuation in water were also carried out using the developed NTL sheet, submersed in a water phantom. In each experiment, NTL sheets having natural abundance (7.9%) of LiF, and (6)LiF-enriched NTL (18.94%) sheet were irradiated under the same conditions. The ratio of thermoluminescence intensities of the (6)LiF-rich NTL sheet to that of the normal NTL sheet was compared to a theoretically calculated value. The experimental measurements are shown to be in good agreement with the calculations.
Assuntos
Terapia por Captura de Nêutron de Boro/instrumentação , Fluoretos/química , Fluoretos/efeitos da radiação , Compostos de Lítio/química , Compostos de Lítio/efeitos da radiação , Nêutrons/uso terapêutico , Dosimetria Termoluminescente/instrumentação , Relação Dose-Resposta à Radiação , Desenho de Equipamento , Análise de Falha de Equipamento , Teste de Materiais , Membranas Artificiais , Doses de Radiação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Dosimetria Termoluminescente/métodosRESUMO
Protons involved in the H-bond system in 1,2-diazine-chloranilic acid (2 : 1) are assumed to be in jumping motion in the double-minimum potential corresponding to the two extreme electronic states of O-H...N and O-...H-N+. 14N nuclear quadrupole coupling constants were determined by 1H-14N nuclear quadrupole double resonance. Assuming that the observed coupling constants are result of a fast exchange of the two extreme electronic states, the coupling constants for each state were estimated by use of the equilibrium populations of the two extreme states determined from multi-temperature X-ray single-crystal diffraction. It was suggested that not only the population but also the electron distribution of the extreme electronic states itself changes with temperature.