Development of a phoswich detector to detect neutrons in the charged-particle mixed field

Manned-space missions bring an exposure due to corpuscular radiations of which nature is quite different from what we encounter in the ground environment. In the space environment, many secondaries are produced through interactions of cosmic ray primaries with the spacecraft wall and other surrounding materials. Among this large variety of radiation components in the space, the contribution of neutrons to the radiation exposure of astronauts has remained to be studied. Up to today, efforts to measure neutron dose equivalent have been made using passive detector systems. Considering uncertainties involved in current measurements and estimations of high energy neutrons, and their increasing importance for future manned missions, it is necessary to measure neutron spectrum in the spacecraft under realistic conditions. The neutron spectra have never been measured on board a spacecraft, because the neutron measurement requires to discriminate between the neutron events due to charged particles caused from neutron reactions and the external charged particle events in the intense charged-particle field, mainly protons, of the space. The, we have developed a new real-time neutron detector which can afford accurate measurements of the spectrum in the energy range of 1 to 100 MeV. (author)