FURTHER-STUDIES OF THE STABILITY OF LIF-MG,CU,P (GR-200) AT MAXIMUM READOUT TEMPERATURES BETWEEN 240-DEGREES-C AND 280-DEGREES-C

It has recently been shown that LiF:Mg,Cu,P (GR-200) can be read out t o temperatures as high as 270 degrees C for 12s with negligible loss i n sensitivity. In the present work the long-term sensitivity of GR-200 was studied at readout temperatures between 240 degrees C and 280 deg rees C. The idea was that the readout at temperatures above 240 degree s C might initiate reaction processes which influence the sensitivity only after long-term storage. No difference was found in the behaviour of GR-200 chips with 80 accumulated readouts to 240 degrees C or 270 degrees C and after storage of up to four months. Slight losses in sen sitivity of 4% for 240 degrees C and 10% for 270 degrees C are observe d after 80 readouts during four months storage. However, at a maximum readout temperature of 280 degrees C, a 33% loss in sensitivity after 80 cycles is observed. In conclusion it is found that GR-200 can be re ad out at temperatures as high as 270 degrees C with negligible loss i n sensitivity (less than 0.1% per readout following an initialisation procedure of 1 readout) and acceptable residual signal (0.6%).