Reactor beam profile measurements with electrochemically etched track detectors

The beam profile of the bismuth-filtered thermal neutron beam of the PTB research reactor has been measured using CR-39 track detectors electrochemically etched on a relatively large area of 5.5 x 5.5 cm2. The tracks were automatically counted with an image analysing system. With the use of different converters it was possible to determine the local distribution of the thermal neutrons and that of fast neutrons present in the beam. (author)