Nuclear radiation detection properties of diamond

The thermoluminescence behaviour of natural diamond and conventional synthetic diamond after irradiation by ionizing radiations was studied. In line with the findings of other researchers, the shortcomings of these stones, when used as thermoluminescence dosimeters, are highlighted. In particular the relatively low sensitivity in common synthetic diamond is attributed to the presence of nitrogen. Systematic decreasing of the nitrogen level indicates unambigously that the thermoluminescence sensitivity increases substantially. Experimental evidence strongly suggests that the nitrogen, which is generally accepted to appear in synthetic diamond in dispersed paramagnetic form, acts as non-radiative recombination centres for charge carriers. Further improvement in the thermoluminescence response occurs with the incorporation of boron. A triple role model for the impurity boron in synthetic diamond is evidenced by an increase in the linearity of the thermoluminescence response, an increase in the thermoluminescence intensity, and the appearance of shallow trapping levels which give rise to thermoluminescence glow peaks below room temperature. Practical dosimeters should be relatively insensitive to ambient lighting. The effect of incorporated nickel in suppressing this sensitivity is highlighted. There is a suggested correlation between the presence of the W8 ESR-line (which has been associated with the presence of nickel) and the degree to which the synthetic diamond is sensitive to ambient lighting. Experimental data in support of the concept that the luminescence centre is due to associated donor-acceptor pairs with the boron being the acceptor are presented. No support however, for the A-aggregate per se being the major donor responsible for emission in the visible region could be found. 106 figs., 26 tabs., 180 refs