Three generations of personal dosimeter/identification badges used at Chalk River Laboratories. The 6 cm square badges displayed the photo and employee number on the front and were attached to the clothing near waist level with a clip fastener. The front could be flipped open and up to about 1968 revealed a film dosimeter, which was removed and the exposed dose read every two weeks. In addition, the inside of the badge contained a sulphur tablet and an indium foil that were read if it was suspected the wearer might have received a measurable exposure to neutrons. Several absorbers of varying thickness were used in front of the film to differentiate the energy of the absorbed gamma/beta radiation. About 1970 the film segment was replaced by two thermoluminescent detectors (TLDs). Changes in the geometry of the badge were introduced around 2000 and in addition, additional dosimeter elements were added.
