Investigation of Absolute Light Output Measurement Techniques

The recently published works on new measurement techniques of the scintillators´ absolute light yield triggered our response in the attempt to find out a way to resolve the disagreements between the old, established technique and the emerging, new one. Authors of the new approach argue that the conditions in which the photomultipliers photocathodes quantum efficiencies´ characteristics are being determined differ substantially from those present in assembled scintillation detectors. The suggested changes, such as resignation from applying an optical coupling, however, seem to overestimate the impact of some factors on derived absolute light yield. A series of measurements of BGO, CsI(Tl), NaI(Tl), LaCl₃, and LaBr₃ crystals of various sizes were performed in order to verify the credibility of the new method´s assumptions. The results seem to support the approved and broadly applied technique.