An improved PC based TL reader for research applications

A new improved PC based TL Reader for its applications in routine dosimetry and research is described. The reader can generate glow curves both time versus TL response and temperature versus TL response with an overall reproducibility of ± 1 %. Here the main thing is design of a linear temperature controller capable of (± 0.5 %) reproducing a selected linear heating rate (0.5 - 60 deg C/s) up to a clamping temperature (500 deg C). Some of the limitations faced in the earlier versions of TL reader for dosimetry have been improved in this system. In the earlier versions, temperature can be clamped only up to 400 deg C and heating rate can be selected up to 35 deg C/s. It is a PC based instrument, where parameters like heating rate, end point temperature, EHT, cycle time etc can be entered and stored in the memory of the microcontroller IC. Phosphors can be in the form of powder, disc, tape etc. When the sample (in the powder form) is loaded on the kanthal heater directly, spilIage of the powder inside the drawer assembly takes place. This leads to the collection of the powder inside the drawer assembly. A small removable sample tray is designed using the same material (kanthal) to avoid the spillage of the sample powder. An elaborate study was carried to find out the lag in temperature when the sample is loaded on the tray and results were compared with the sample directly on the heater. To evaluate the performance of the reader for higher temperature, glow curves were taken for some new phosphors whose glow peaks were above 350 deg C. (author)