Real-time measurement of low-energy-range neutron spectra on board the space shuttle STS-89 (S/MM-8)

We have developed a real-time, Bonner Ball-type (neutron energy range is fr om thermal to 15 MeV) neutron spectral measurement system (Bonner Ball Neut ron Detector (BBND)) for use on board the International Space Station (ISS) . From measurements taken inside STS-89 (S/MM-8), we successfully distingui shed neutrons from protons and other particles in a mixed radiation field; a task hitherto considered difficult. Although the experimental period was short, only 3.5 days (January 24-27, 1998), we were able to obtain energy s pectral data and the Earth's neutron dose-equivalent map for the ISS orbita l conditions (altitude 400 km, orbit inclination angle 51.6). A method for calculating the neutron energy spectrum and compensating for the particle i nteraction with the sensors is also described in detail. (C) 2001 Elsevier Science Ltd. All rights reserved.