Compact 4/spl pi/ Ge spectrometer for neutron capture cross section measurement

We develop a 4pi Ge spectrometer consisting of large-volume Ge detectors and BGO scintillators for capture cross section measurement of minor actinides such as ^241,243Am and ²³⁷Np. By using this spectrometer we can extract summed gamma-ray energy, which corresponds to excitation energy of the residual nucleus after neutron capture reaction. The high energy resolution achieved by Ge crystals will enable us to distinguish between the nucleus of interest and impurity nucleus: we can eliminate the contribution from the impurity nucleus in the cross section measurements, enabling us to derive accurate cross section data. In this paper we will describe detailed design study of the spectrometer and its performance based on the Monte-Carlo simulation code GEANT4.5.0.