

UJ 



> 



u 

 en 



St. Genevieve Ls. 

 (Levies Member) 



100 



200 



TEMPERATURE 



300 

 CENTIGRADE 



400 



Figure 10-5. Glow curves of typical limestones. 



fections or impurity holes of low energy levels, can escape; therefore, the low- 

 temperature peaks do not show up. When exposed to high intensity gamma radi- 

 ation, however, these traps become filled much faster than they can be emptied 

 by thermal energy, and new low-temperature peaks are produced as shown in 

 Figure 10-7. 



An extensive study has been made of the thermoluminescence of calcium car- 

 bonates precipitated in the laboratory (Zeller and Wray, 1956). Some of the 

 peaks are associated with impurities such as manganese and strontium, as shown 

 in Figure 10-8. Unless the impurity ions are incorporated into the crystal lattice, 

 they cannot act as electron traps to provide thermoluminescence peaks. The pH 

 of the solution and the concentration of the impurities is an important factor in 



89 



