The beam of fission neutrons at FRM II and its application in medicine, biology, and materials characterisation

The source of the fission neutron beam at the research reactor FRM II is a thermal-to-fast neutron converter. It consists of a pair of movable uranium plates which can be positioned in closest touch to beam tube SR10. The energy spectrum of the neutrons is essentially a Watt spectrum with a mean energy of 1.9 MeV. The beam is used for a great variety of applications, e.g., the structure of large samples can be displayed by radiography and tomography; electronic components are tested with respect to their radiation hardness to hadrons; biologists are interested in the specific effects of the high linear energy transfer of fission neutrons, and radiotherapists administer the fast reactor neutrons to malignant tumours. Results of all these fields are given briefly.