Automatic Scanning of NTA Film Neutron Dosemeters

At the European Laboratory for Particle Physics CERN, personal neutron monitoring for over 4000 collaborators is performed with Kodak NTA film, one of the few suitable dosemeters in the stray radiation environment of a high energy accelerator. After development, films are scanned with a projection microscope. To overcome this lengthy and strenuous procedure an automated analysis system for the dosemeters has been developed. General purpose image recognition software, tailored to the specific needs with a macro language, analyses the digitised microscope image. This paper reports on the successful automatic scanning of NTA films irradiated with neutrons from a 238Pu-Be source (E ∼ 4 MeV), as well as on the extension of the method to neutrons of higher energies. The question of detection limits is discussed in the light of an application of the methods in routine personal neutron monitoring. (author)