THE 4-PI-FRAGMENT-SPECTROMETER FOBOS

The 4 pi-fragment-spectrometer FOBOS developed for heavy-ion research at beam energies of 10-100 AMeV has been commissioned for physical exp eriments at the Flerov Laboratory of Nuclear Reactions of the Joint In stitute for Nuclear Research in Dubna, Based on the logarithmic detect or principle, it is able to register charged fragments from protons up to heavy residual nuclei in a large dynamical range. Position-sensiti ve avalanche counters, axial ionization chambers and CsI(TI) scintilla tion detectors are arranged in three concentric detector shells. An ar ray of phoswich detectors is used as a more granular forward detector at narrow polar angles. The modular concept of FOBOS allows for differ ent experimental application in the field of exclusive fragment spectr oscopy at medium multiplicities. For illustration, the fragment spectr oscopy studies concerning the spontaneous fission process and the frag mentation of hot nuclei by means of the FOBOS set-up are considered. ( C) 1998 Elsevier Science B.V. All rights reserved.