A rotating-slit-collimator-based gamma radiation mapper.

For situations with radioactive material out of control where it may be physically difficult or prohibited to access areas close to the source, measurements from distance may be the only way to assess the radiation environment. Using collimated detectors will provide means to locate the direction of the radiation from the source. To investigate the possibilities of mapping gamma emitting radioactive material in a closed non-enterable area, a tentative system for mapping radioactive materials from a distance was built.

A deviation display method for visualising data in mobile gamma-ray spectrometry.

A real time visualisation method, to be used in mobile gamma-spectrometric search operations using standard detector systems is presented. The new method, called deviation display, uses a modified waterfall display to present relative changes in spectral data over energy and time. Using unshielded (137)Cs and (241)Am point sources and different natural background environments, the behaviour of the deviation displays is demonstrated and analysed for two standard detector types (NaI(Tl) and HPGe).