Neutron dose distribution at the GSI fragment separator

Area of Science:

• Nuclear Physics
• Radiation Physics
• Accelerator Physics

Background:

• GSI operates a rare isotope production facility using heavy ion beams.
• Primary beams and produced nuclei interact within the Fragment Separator (FRS), generating significant neutron radiation.
• Understanding neutron radiation is crucial for facility safety and component integrity.

Purpose of the Study:

• To measure and map two-dimensional neutron dose distributions within the FRS.
• To evaluate the effectiveness of Thermoluminescence Dosemeters (TLDs) for neutron dosimetry in this environment.
• To develop a model for predicting neutron dose distribution.

Main Methods:

• Exposure of Thermoluminescence Dosemeters (TLDs), specifically 6LiF/7LiF pairs in PE spheres, to neutron fields.
• Utilizing uranium beams with energies ranging from 100 to 1000 MeV per nucleon.
• Combining TLD measurements with model calculations for dose distribution analysis.
• Developing a superposition model based on measured double differential neutron distributions for a 1 GeV per nucleon uranium beam.

Main Results:

• Acquisition of two-dimensional dose distributions using TLDs and model calculations.
• Demonstration of TLDs' capability to assess neutron radiation fields in accelerator environments.
• Validation of the applied model for describing dose distribution as a superposition of single source patterns.

Conclusions:

• The study successfully mapped neutron radiation fields within the GSI FRS using TLDs and modeling.
• The findings provide valuable data for radiation protection and operational safety at rare isotope facilities.
• The developed model offers a method for predicting dose distributions from distributed neutron sources.