On the use of new vs. heated sample carriers for luminescence measurements

To ensure precise luminescence measurements, it is crucial to carry out measurements on clean sample carriers. Moreover, it is essential to ensure that the light emitted by the studied sample is reproducibly reflected towards the detector, particularly when the sample exhibits dim luminescence. This study reports observations made by three laboratories working in the field of retrospective dosimetry. The study discusses the results obtained using new sample carriers (made of stainless steel), instead of sample carriers previously heated to a temperature of 450 degrees C. The article describes the cleaning protocols routinely used by each laboratory and the treatment with distilled water that effectively removed spurious signals. When measuring TL signals of resistors using new sample carriers, a signal reduction of 10% was observed in the second measurement compared to the initial TL. For display glass samples from a mobile phone, a signal reduction between 15% and 32% was observed. However, there was negligible change in reproducibility when using the previously heated sample carriers. The reflectance of the sample carrier surface was indirectly measured using breakthrough signal measurements using violet or blue LEDs. A signal reduction of 12-14 % was observed when heating was applied for 20 new, unheated sample carriers using violet LEDs. The impact on dose estimation is discussed, and some recommendations are provided to guarantee precise luminescence measurements.