TLD System for Measurement of a Wide Range of X- and Gamma Exposures

This paper describes a composite TLD system which has been designed and developed In the authors' laboratories. The phosphor used in these investigations was locally prepared lithium borate (manganese activated). The read-out system consists of: (1) a platinum foil used as the heating element; (2) a multiplier phototube to measure the thermoluminescence output; (3) a d.c. amplifier, (4) a recorder to display the glow curves; (5) a timer to start and terminate the readings; and (6) a light source to serve as a calibration standard for the PM tube. This system has provided consistent response in the exposure range from 400 mR to 108 R and efforts are under way to reduce the threshold further. The read-out system is provided with a nitrogen flushing facility to eliminate the effect of non-radiation-induced signals during measurement. Studies of the various characteristics of the phosphor, such as energy dependence, exposure rate dependence, linearity and reproducibility have been made and the results are presented. (author)