TL-efficiency—Overview and experimental results over the years

For several decades, thermoluminescence detectors (TLDs) have been widely used in environmental, personal and medical dosimetry. With the development of heavy-ion accelerators, investigations concentrated on the thermoluminescent (TL) response of different TL phosphors to heavy charged particles (HCPs), motivated by the manifold potential TLD applications in HCP dosimetry. At the beginning, the research interest was focused particularly on the most common TL material, LiF:Mg, Ti. During the last years, considerable effort has been invested to determine precisely TL-efficiency also for other phosphors, either based on theoretical models or on experiments at heavy-ion accelerator facilities. The high amount of TLDs being used in space dosimetry in combination with plastic nuclear track detectors (PNTDs) essentially requires the detailed knowledge of TL-efficiency to permit dose equivalent evaluation. The paper summarizes the theoretical models currently employed to describe TL-efficiency and reviews TL-efficiency measurements from the late 1960s up to now. Difficulties in comparing TL-efficiency data from various laboratories due to different readout systems and experimental protocols will be addressed. Valuable input for a critical discussion is provided by the large pool of recent TL-efficiency data generated in the framework of the ICCHIBAN intercomparison experiment. Particularly the results obtained by the authors for 6LiF:Mg, Ti (TLD-600), 7LiF:Mg, Ti (TLD-700), 6LiF:Mg, Cu, P (TLD-600H), 7LiF:Mg, Cu, P (TLD-700H) and CaF2:Tm (TLD-300) detectors, purchased from Thermo Fisher Scientific, Inc. (former Harshaw Chemical Co.), will be analyzed since these materials—and specific peaks in their glow curves—show distinctively different TL responses to HCP irradiation