Neutron measurement techniques for hand-held devices

Reliable measurement techniques are important for early detection of illicit use of nuclear and radioactive material. Nuclear safeguards are an important tool to impede the illicit handling of fissionable material. But the scope of safeguards is only nuclear material within the fuel cycle. Neutron emitting radioactive material may have its origin from the fuel cycle as well as from an industrial neutron source. Terrorist attacks using neutron emitting material may have far reaching consequences not only if nuclear material is involved. Therefore it is of great importance that mobile measuring systems are available to detect and to respond to possible malicious acts involving this material. Fraunhofer INT has built up a mobile measuring system in a transportable container for the detection and identification of radioactive and nuclear material. The system is equipped with various types of detectors for neutron and gamma radiation, some of the detectors are similar to those used in safeguards. The measuring capabilities of the system have been extended by mobile, easy transportable neutron measuring devices. These devices not only count neutrons but are also able to give additional spectral, coincidence, or multiplicity information. Thereby different types of neutron sources, like SNM or industrial, can be distinguished. Various mobile neutron detection devices have been tested in different neutron fields of variable strength and with additional shielding of different types. Results of these measurements will be presented. The advantages and disadvantages of different concepts will be shown. This may help to prevent illicit trafficking of nuclear material.