The 100°C thermoluminescence (TL) sensitivity of fired quartz is increased greatly by beta irradiation and subsequent heating (eg by an order of magnitude following a 1 krad dose and heating to 500°C). Its radioluminescence response increases similarly, implying that the increase of TL sensitivity arises from an increased probability of photon emission per thermally released charge. This implication is confirmed by the decrease of thermally stimulated exoelectron emission (TSEE) sensitivity which accompanies the increase of the TL sensitivity. Furthermore, the decrease of TSEE sensitivity shows that the increased TL sensitivity arises from an intrinsic change in the luminescence centres themselves, rather than from some cause external to the luminescence centres. The increase of TL sensitivity is reduced by uv irradiation, and restored by subsequent heating to 500°C. These results indicate that the increase of TL sensitivity results primarily from and increase in the number of activated luminescence centres participating in TL emission, the centres being activated by charge capture.