Internal dose rate in quartz grains: Implications for luminescence dating

This study assesses how internal dose rate in quartz grains impacts luminescence dating.  In 2018, the Gliwice Luminescence Laboratory implemented innovative μDose system which combines advantages of alpha and beta counting measurement techniques with additional radioactive identification capabilities. The device allows measurements of small samples and results verification with an independent high-resolution gamma spectrometry method. 

All measurements of internal dose rate were made on  pure quartz grains after standard chemical pretreatment. Grains with diameters between 125 and 200 μm were selected for measurements. This material was dried and grounded to approx. 20 μm using a planetary ball mill prior to measurements on the μDose systems.  

Internal dose rate reported here is particularly important because of low (about 0.8-0.9 Gy/ka) or very low (0.4-0.6 Gy/ka) external dose rates. Internal dose rate in quartz grains in our measurements is a significant fraction of the total dose rate, often exceeding 10%. Ignoring this correction would make luminescence ages in our study artificially older.

Presented results were obtained with support of Polish National Science Centre, contract number 2018/30/E/ST10/00616