Neutron dose distribution at the GSI fragment separator

GSI is operating a facility for the production of rare isotopes. Nuclei are produced by fragmentation or fission of the impinging heavy ions with energies of ∼1 GeV per nucleon. The major part of the primary beam and the produced nuclei is deposited in the components of the Fragment Separator (FRS) and generates neutron radiation. Thermoluminescence dosemeters (TLDs) (6LiF/7LiF pairs in PE spheres) were exposed in neutron fields produced by uranium beams with energies between 100 and 1000 MeV per nucleon during an irradiation period in the year 2002. Two-dimensional dose distributions are obtained using these TL measurements in combination with model calculations. The applied model describes the dose distribution as a superposition of dose patterns of 20 single sources equally distributed along the FRS. The single source distribution is based on a measured double differential neutron distribution for a 1 GeV per nucleon uranium beam. (authors)