Publications by Hans Kraus


Low temperature scintillation properties of Ga<inf>2</inf>O<inf>3</inf>

Journal of Physical Studies 24 (2020)

VB Mykhaylyk, H Kraus, V Kapustianyk, M Rudko, V Kolomiets

© 2020, Ivan Franko National University of Lviv. All rights reserved. This work is devoted to the study of the luminescence and scintillation properties of an undoped Ga3 crystal over the 7295 K temperature range. The samples were obtained using the edge-dened lm-fed growth2O method. These investigations were performed in order to conrm that the investigated crystals really could be considered as promising scintillation detectors of ionising radiation. The steady-state X-ray luminescence was excited by a URS-55A X-ray tube with a Ñu-anticathode tube. For the measurements of scintillation characteristics the crystal was placed in a helium constant ow cryostat and excited by α-particles from an241Am source. Two emission bands observed in UV and blue spectral range are assigned to the radiative recombination of self-trapped excitons and donor-acceptor pairs, respectively. The scintillation light output of the crystal increases with cooling, reaching the maximum value of 19300 ± 2200 ph/MeV at 50 K, and then it decreases by 30 % with further cooling to 7 K. It has been found that at room temperature an undoped Ga3 exhibits about one-third of the light output of a commercial LYSO-Ce scintillator. The detection eciency2Oof the crystal is lower in comparison with the best scintillators in the eld. Nevertheless, taking into account the fact that the intrinsic defects play a major role in the emission of gallium oxide, we can predict that substantial improvement of the scintillation properties is likely to occur through the material doping and optimisation of the production technology. This nding evidences that undoped β-Ga3 can be used for scintillation detection over the wide temperature range. The measured kinetics of the luminescence2O decay possesses a recombination character with the corresponding decay time (τ increasing from 1 to 1.8 × 10−6 s with cooling0.1),.


Measurement of the gamma ray background in the Davis cavern at the Sanford Underground Research Facility

Astroparticle Physics Elsevier 116 (2019) 102391

D Akerib, C Akerlof, S Alsum, K Boast, C Carels, A Cottle, T Fruth

Deep underground environments are ideal for low background searches due to the attenuation of cosmic rays by passage through the earth. However, they are affected by backgrounds from γ-rays emitted by 40K and the 238U and 232Th decay chains in the surrounding rock. The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC located within the Davis campus at the Sanford Underground Research Facility, Lead, South Dakota, at the 4850-foot level. In order to characterise the cavern background, in-situ γ-ray measurements were taken with a sodium iodide detector in various locations and with lead shielding. The integral count rates (0–3300 keV) varied from 596 Hz to 1355 Hz for unshielded measurements, corresponding to a total flux from the cavern walls of 1.9 ± 0.4 γ cm−2s−1. The resulting activity in the walls of the cavern can be characterised as 220 ± 60 Bq/kg of 40K, 29 ± 15 Bq/kg of 238U, and 13 ± 3 Bq/kg of 232Th.


Cryogenic characterization of a LiAlO <inf>2</inf> crystal and new results on spin-dependent dark matter interactions with ordinary matter: CRESST Collaboration

European Physical Journal C 80 (2020)

AH Abdelhameed, G Angloher, P Bauer, A Bento, E Bertoldo, R Breier, C Bucci, L Canonica, A D’Addabbo, S Di Lorenzo, A Erb, FV Feilitzsch, NF Iachellini, S Fichtinger, D Fuchs, A Fuss, VM Ghete, A Garai, P Gorla, D Hauff, M Ješkovský, J Jochum, J Kaizer, M Kaznacheeva, A Kinast, H Kluck, H Kraus, A Langenkämper, M Mancuso, V Mokina, E Mondragon, M Olmi, T Ortmann, C Pagliarone, V Palušová, L Pattavina, F Petricca, W Potzel, P Povinec, F Pröbst, F Reindl, J Rothe, K Schäffner, J Schieck, V Schipperges, D Schmiedmayer, S Schönert, C Schwertner, M Stahlberg, L Stodolsky, C Strandhagen, R Strauss, I Usherov, F Wagner, M Willers, V Zema, J Zeman, M Brützam, S Ganschow

© 2020, The Author(s). In this work, a first cryogenic characterization of a scintillating LiAlO 2 single crystal is presented. The results achieved show that this material holds great potential as a target for direct dark matter search experiments. Three different detector modules obtained from one crystal grown at the Leibniz-Institut für Kristallzüchtung (IKZ) have been tested to study different properties at cryogenic temperatures. Firstly, two 2.8 g twin crystals were used to build different detector modules which were operated in an above-ground laboratory at the Max Planck Institute for Physics (MPP) in Munich, Germany. The first detector module was used to study the scintillation properties of LiAlO 2 at cryogenic temperatures. The second achieved an energy threshold of (213.02 ± 1.48) eV which allows setting a competitive limit on the spin-dependent dark matter particle-proton scattering cross section for dark matter particle masses between 350MeV/c2 and 1.50GeV/c2. Secondly, a detector module with a 373 g LiAlO 2 crystal as the main absorber was tested in an underground facility at the Laboratori Nazionali del Gran Sasso (LNGS): from this measurement it was possible to determine the radiopurity of the crystal and study the feasibility of using this material as a neutron flux monitor for low-background experiments.


Latest results of CRESST-III's search for sub-GeV/c2 dark matter

Journal of Physics: Conference Series 1468 (2020)

H Kluck, AH Abdelhameed, G Angloher, P Bauer, A Bento, E Bertoldo, R Breier, C Bucci, L Canonica, A D'Addabbo, S Di Lorenzo, A Erb, FV Feilitzsch, N Ferreiro Iachellini, S Fichtinger, A Fuss, P Gorla, D Hauff, M Jeskovsky, J Jochum, J Kaizer, A Kinast, H Kraus, A Langenkämper, M Mancuso, V Mokina, E Mondragon, M Olmi, T Ortmann, C Pagliarone, V Palusova, L Pattavina, F Petricca, W Potzel, P Povinec, F Pröbst, F Reindl, J Rothe, K Schaner, J Schieck, V Schipperges, D Schmiedmayer, S Schönert, C Schwertner, M Stahlberg, L Stodolsky, C Strandhagen, R Strauss, I Usherov, M Willers, V Zema, J Zeman

© 2020 Institute of Physics Publishing. All rights reserved. The CRESST-III experiment searches for direct interactions of dark matter with ordinary matter. The main event signature would be a nuclear recoil inside one of the scintillating CaWO4 crystals. Operating the crystals as cryogenic calorimeters provides a phonon signal as measure of the deposited energy. The simultaneous readout of both signals is used to actively discriminate backgrounds. CRESST-III focuses on the sub-GeV/c2 mass region where the sensitivity is driven by the threshold. In the _rst data taking campaign of CRESST-III from 2016-2018 an unprecedented low threshold of 30.1 eV for nuclear recoils was obtained. In this contribution, we will report the status of the experiment and the latest results.


Bright and fast scintillations of an inorganic halide perovskite CsPbBr3 crystal at cryogenic temperatures

Scientific Reports Nature Research 10 (2020) 8601

V Mykhaylyk, H Kraus, V Kapustianyk, H Kim, P Mercere, M Rudko, P Da Silva, O Antonyak, M Dendebera

Highly efficient scintillation crystals with short decay times are indispensable for improving the performance of numerous detection and imaging instruments that use- X-rays, gamma-quanta, ionising particles or neutrons. Halide perovskites emerged recently as very promising materials for detection of ionising radiation that motivated further exploration of the materials. In this work, we report on excellent scintillation properties of CsPbBr3 crystals when cooled to cryogenic temperatures. The temperature dependence of luminescence spectra, decay kinetics and light yield under excitation with X-rays and α-particles was investigated. It is shown that the observed changes of spectral and kinetic characteristics of the crystal with temperature can be consistently explained by radiative decay of free excitons, bound and trapped excitons as well as electron-hole pairs originating from their disintegration. It has been found that the crystal exhibits a fast decay time constant of 1 ns at 7 K. The scintillation light yield of CsPbBr3 at 7 K is assessed to be 50,000 ± 10,000 ph/MeV at excitation with 12 keV X-rays and 109,000 ± 22,000 ph/MeV at excitation with α-particles of 241Am. This finding places CsPbBr3 in an excellent position for the development of a new generation of cryogenic, efficient scintillation detectors with nanosecond response time, marking a step-change in opportunities for scintillator-based applications.


Lithium-Containing Crystals for Light Dark Matter Search Experiments

JOURNAL OF LOW TEMPERATURE PHYSICS 199 (2020) 510-518

E Bertoldo, AH Abdelhameed, G Angloher, P Bauer, A Bento, R Breier, C Bucci, L Canonica, A D'Addabbo, S Di Lorenzo, A Erb, FV Feilitzsch, N Ferreiro Iachellini, S Fichtinger, D Fuchs, A Fuss, P Gorla, D Hauff, M Jeskovsky, J Jochum, J Kaizer, A Kinast, H Kluck, H Kraus, A Langenkaemper, M Mancuso, V Mokina, E Mondragon, M Olmi, T Ortmann, C Pagliarone, V Palusova, L Pattavina, F Petricca, W Potzel, P Povinec, F Proebst, F Reindl, J Rothe, K Schaeffner, J Schieck, V Schipperges, D Schmiedmayer, S Schoenert, C Schwertner, M Stahlberg, L Stodolsky, C Strandhagen, R Strauss, I Usherov, M Willers, V Zema, J Zeman, M Bruetzam, S Ganschow, CRESST Collaboration


First results on low-mass dark matter from the CRESST-III experiment

Journal of Physics: Conference Series 1342 (2020)

F Petricca, G Angloher, P Bauer, A Bento, C Bucci, L Canonica, X Defay, A Erb, FV Feilitzsch, NF Iachellini, P Gorla, A Gütlein, D Hauff, J Jochum, M Kiefer, H Kluck, H Kraus, JC Lanfranchi, A Langenkämper, J Loebell, M Mancuso, E Mondragon, A Münster, C Pagliarone, W Potzel, F Pröbst, R Puig, F Reindl, J Rothe, K Schäffner, J Schieck, S Schönert, W Seidelf, M Stahlberg, L Stodolsky, C Strandhagen, R Strauss, A Tanzke, HHT Thi, C Türkoǧlu, A Ulrich, I Usherov, S Wawoczny, M Willers, M Wüstrich

© Published under licence by IOP Publishing Ltd. The CRESST experiment (Cryogenic Rare Even Search with Superconducting Thermometers), located at Laboratori Nazionali del Gran Sasso in Italy, searches for dark matter particles via their elastic scattering off nuclei in a target material. The CRESST target consists of scintillating CaWO4 crystals, which are operated as cryogenic calorimeters at millikelvin temperatures. Each interaction in the CaWO4 target crystal produces a phonon signal and a light signal that is measured by a second cryogenic calorimeter. Since the CRESST-II result in 2015, the experiment is leading the field of direct dark matter search for dark matter masses below 1.7 GeV/c 2, extending the reach of direct searches to the sub-GeV/c 2 mass region. For CRESST-III, whose Phase 1 started in July 2016, detectors have been optimized to reach the performance required to further probe the low-mass region with unprecedented sensitivity. In this contribution the achievements of the CRESST-III detectors will be discussed together with preliminary results and perspectives of Phase 1.


Searches for Light Dark Matter with the CRESST-III Experiment

JOURNAL OF LOW TEMPERATURE PHYSICS 199 (2020) 547-555

M Mancuso, AH Abdelhameed, G Angloher, R Breier, P Bauer, A Bento, E Bertoldo, C Bucci, L Canonica, A D'Addabbo, S Di Lorenzo, A Erb, F von Feilitzsch, N Ferreiro Iachellini, S Fichtinger, A Fuss, P Gorla, D Hauff, M Jeskovsky, J Jochum, J Kaizer, A Kinast, H Kluck, H Kraus, A Langenkaemper, V Mokina, E Mondragon, M Olmi, T Ortmann, C Pagliarone, V Palusova, L Pattavina, F Petricca, W Potzel, P Povinec, F Proebst, F Reindl, J Rothe, K Schaeffner, J Schieck, V Schipperges, D Schmiedmayer, S Schoenert, C Schwertner, M Stahlberg, L Stodolsky, C Strandhagen, R Strauss, C Tuerkoglu, I Usherov, M Willers, V Zema, J Zeman, CRESST Collaboration


Projected WIMP sensitivity of the LUX-ZEPLIN dark matter experiment

PHYSICAL REVIEW D 101 (2020) ARTN 052002

DS Akerib, CW Akerlof, SK Alsum, HM Araujo, M Arthurs, X Bai, AJ Bailey, J Balajthy, S Balashov, D Bauer, J Belle, P Beltrame, T Benson, EP Bernard, TP Biesiadzinski, KE Boast, B Boxer, P Bras, JH Buckley, VV Bugaev, S Burdin, JK Busenitz, C Carels, DL Carlsmith, B Carlson, MC Carmona-Benitez, C Chan, JJ Cherwinka, A Cole, A Cottle, WW Craddock, A Currie, JE Cutter, CE Dahl, L de Viveiros, A Dobi, JEY Dobson, E Druszkiewicz, TK Edberg, WR Edwards, A Fan, S Fayer, S Fiorucci, T Fruth, RJ Gaitskell, J Genovesi, C Ghag, MGD Gilchriese, MGD van der Grinten, CR Hall, S Hans, K Hanzel, SJ Haselschwardt, SA Hertel, S Hillbrand, C Hjemfelt, MD Hoff, JY-K Hor, DQ Huang, CM Ignarra, W Ji, AC Kaboth, K Kamdin, J Keefner, D Khaitan, A Khazov, YD Kim, CD Kocher, EV Korolkova, H Kraus, HJ Krebs, L Kreczko, B Krikler, VA Kudryavtsev, S Kyre, J Lee, BG Lenardo, DS Leonard, KT Lesko, C Levy, J Li, J Liao, F-T Liao, J Lin, A Lindote, R Linehan, WH Lippincott, X Liu, MI Lopes, BL Paredes, W Lorenzon, S Luitz, JM Lyle, P Majewski, A Manalaysay, RL Mannino, C Maupin, DN McKinsey, Y Meng, EH Miller, J Mock, ME Monzani, JA Morad, E Morrison, BJ Mount, ASJ Murphy, HN Nelson, F Neves, J Nikoleyczik, K O'Sullivan, I Olcina, MA Olevitch, KC Oliver-Mallory, KJ Palladino, SJ Patton, EK Pease, B Penning, A Piepke, S Powell, RM Preece, K Pushkin, BN Ratcliff, J Reichenbacher, CA Rhyne, A Richards, JP Rodrigues, R Rosero, P Rossiter, JS Saba, M Sarychev, RW Schnee, M Schubnell, PR Scovell, S Shaw, TA Shutt, JJ Silk, C Silva, K Skarpaas, W Skulski, M Solmaz, VN Solovov, P Sorensen, I Stancu, MR Stark, TM Stiegler, K Stifter, M Szydagis, WC Taylor, R Taylor, DJ Taylor, D Temples, PA Terman, KJ Thomas, M Timalsina, WH To, A Tomas, TE Tope, M Tripathi, CE Tull, L Tvrznikova, U Utku, J Vavra, A Vacheret, JR Verbus, E Voirin, WL Waldron, JR Watson, RC Webb, DT White, TJ Whitis, WJ Wisniewski, MS Witherell, FLH Wolfs, D Woodward, SD Worm, M Yeh, J Yin, I Young, LUX-ZEPLIN Collaboration


Projected sensitivity of the LUX-ZEPLIN experiment to the 0 nu beta beta decay of Xe-136

PHYSICAL REVIEW C 102 (2020) ARTN 014602

DS Akerib, CW Akerlof, A Alqahtani, SK Alsum, TJ Anderson, N Angelides, HM Araujo, JE Armstrong, M Arthurs, X Bai, J Balajthy, S Balashov, J Bang, A Baxter, J Bensinger, EP Bernard, A Bernstein, A Bhatti, A Biekert, TP Biesiadzinski, HJ Birch, KE Boast, B Boxer, P Bras, JH Buckley, VV Bugaev, S Burdin, JK Busenitz, R Cabrita, C Carels, DL Carlsmith, MC Carmona-Benitez, M Cascella, C Chan, NI Chott, A Cole, A Cottle, JE Cutter, CE Dahl, L de Viveiros, JEY Dobson, E Druszkiewicz, TK Edberg, SR Eriksen, A Fan, S Fiorucci, H Flaecher, ED Fraser, T Fruth, RJ Gaitskell, J Genovesi, C Ghag, E Gibson, MGD Gilchriese, S Gokhale, MGD van der Grinten, CR Hall, A Harrison, SJ Haselschwardt, SA Hertel, JY-K Hor, M Horn, DQ Huang, CM Ignarra, O Jahangir, W Ji, J Johnson, AC Kaboth, AC Kamaha, K Kamdin, K Kazkaz, D Khaitan, A Khazov, I Khurana, CD Kocher, L Korley, EV Korolkova, J Kras, H Kraus, S Kravitz, L Kreczko, B Krikler, VA Kudryavtsev, EA Leason, J Lee, DS Leonard, KT Lesko, C Levy, J Li, J Liao, F-T Liao, J Lin, A Lindote, R Linehan, WH Lippincott, R Liu, X Liu, C Loniewski, MI Lopes, BL Paredes, W Lorenzon, S Luitz, JM Lyle, PA Majewski, A Manalaysay, L Manenti, RL Mannino, N Marangou, MF Marzioni, DN McKinsey, J McLaughlin, Y Meng, EH Miller, E Mizrachi, A Monte, ME Monzani, JA Morad, E Morrison, BJ Mount, ASJ Murphy, D Naim, A Naylor, C Nedlik, C Nehrkorn, HN Nelson, F Neves, JA Nikoleyczik, A Nilima, K O'Sullivan, I Olcina, KC Oliver-Mallory, S Pal, KJ Palladino, J Palmer, N Parveen, EK Pease, B Penning, G Pereira, K Pushkin, J Reichenbacher, CA Rhyne, Q Riffard, GRC Rischbieter, R Rosero, P Rossiter, G Rutherford, D Santone, ABMR Sazzad, RW Schnee, M Schubnell, D Seymour, S Shaw, TA Shutt, JJ Silk, C Silva, R Smith, M Solmaz, VN Solovov, P Sorensen, I Stancu, A Stevens, K Stifter, TJ Sumner, N Swanson, M Szydagis, M Tan, WC Taylor, R Taylor, DJ Temples, PA Terman, DR Tiedt, M Timalsina, A Tomas, M Tripathi, DR Tronstad, W Turner, L Tvrznikova, U Utku, A Vacheret, A Vaitkus, JJ Wang, W Wang, JR Watson, RC Webb, RG White, TJ Whitis, FLH Wolfs, D Woodward, X Xiang, J Xu, M Yeh, P Zarzhitsky, LUX-ZEPLINLZ Collaboration


The LUX-ZEPLIN (LZ) experiment

Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Elsevier 953 (2019) 163047

DS Akerib, CW Akerlof, DY Akimov, K Boast, A Cottle, T Fruth, E Gibson, H Kraus, A Stevens, M Tan,

We describe the design and assembly of the LUX-ZEPLIN experiment, a direct detection search for cosmic WIMP dark matter particles. The centerpiece of the experiment is a large liquid xenon time projection chamber sensitive to low energy nuclear recoils. Rejection of backgrounds is enhanced by a Xe skin veto detector and by a liquid scintillator Outer Detector loaded with gadolinium for efficient neutron capture and tagging. LZ is located in the Davis Cavern at the 4850’ level of the Sanford Underground Research Facility in Lead, South Dakota, USA. We describe the major subsystems of the experiment and its key design features and requirements.


First results from the CRESST-III low-mass dark matter program

Physical Review D American Physical Society 100 (2019) 102002

AH Abdelhameed, S Di Lorenzo, A Erb, FV Feilitzsch, S Fichtinger, N Ferreiro Iachellini, A Fuss, P Gorla, D Hauff, J Jochum, A Kinast, H Kluck, H Kraus, A Langenkämper, M Mancuso, V Mokina, E Mondragon, A Münster, M Olmi, T Ortmann, C Pagliarone, L Pattavina, F Petricca, W Potzel, F Reindl

The CRESST experiment is a direct dark matter search which aims to measure interactions of potential dark matter particles in an Earth-bound detector. With the current stage, CRESST-III, we focus on a low energy threshold for increased sensitivity towards light dark matter particles. In this paper we describe the analysis of one detector operated in the first run of CRESST-III (05/2016–02/2018) achieving a nuclear recoil threshold of 30.1 eV. This result was obtained with a 23.6 g CaWO 4 crystal operated as a cryogenic scintillating calorimeter in the CRESST setup at the Laboratori Nazionali del Gran Sasso (LNGS). Both the primary phonon (heat) signal and the simultaneously emitted scintillation light, which is absorbed in a separate silicon-on-sapphire light absorber, are measured with highly sensitive transition edge sensors operated at ∼ 15     mK . The unique combination of these sensors with the light element oxygen present in our target yields sensitivity to dark matter particle masses as low as 160     MeV / c 2 .


First results on sub-GeV spin-dependent dark matter interactions with Li-7

EUROPEAN PHYSICAL JOURNAL C 79 (2019) ARTN 630

AH Abdelhameed, G Angloher, P Bauer, A Bento, E Bertoldo, C Bucci, L Canonica, A D'Addabbo, X Defay, S Di Lorenzo, A Erb, F von Feilitzsch, NF Iachellini, S Fichtinger, A Fuss, P Gorla, D Hauff, J Jochum, A Kinast, H Kluck, H Kraus, A Langenkaemper, M Mancuso, V Mokina, E Mondragon, A Muenster, M Olmi, T Ortmann, C Pagliarone, L Pattavina, F Petricca, W Potzel, F Proebst, F Reindl, J Rothe, K Schaeffner, J Schieck, V Schipperges, D Schmiedmayer, S Schoenert, C Schwertner, M Stahlberg, L Stodolsky, C Strandhagen, R Strauss, C Tuerkoglu, I Usherov, M Willers, V Zema, M Chapellier, A Giuliani, C Nones, DV Poda, VN Shlegel, M Velazquez, AS Zolotarova, CRESST Collaboration


Geant4-based electromagnetic background model for the CRESST dark matter experiment.

The European physical journal. C, Particles and fields 79 (2019) 881-

AH Abdelhameed, G Angloher, P Bauer, A Bento, E Bertoldo, R Breier, C Bucci, L Canonica, A D'Addabbo, SD Lorenzo, A Erb, FV Feilitzsch, NF Iachellini, S Fichtinger, A Fuss, P Gorla, D Hauff, M Jes Kovský, J Jochum, J Kaizer, A Kinast, H Kluck, H Kraus, A Langenkämper, M Mancuso, V Mokina, E Mondragón, M Olmi, T Ortmann, C Pagliarone, V Palus Ová, L Pattavina, F Petricca, W Potzel, P Povinec, F Pröbst, F Reindl, J Rothe, K Schäffner, J Schieck, V Schipperges, D Schmiedmayer, S Schönert, C Schwertner, M Stahlberg, L Stodolsky, C Strandhagen, R Strauss, C Türkoğlu, I Usherov, M Willers, V Zema, J Zeman

The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) dark matter search experiment aims for the detection of dark matter particles via elastic scattering off nuclei in CaWO4 crystals. To understand the CRESST electromagnetic background due to the bulk contamination in the employed materials, a model based on Monte Carlo simulations was developed using the Geant4 simulation toolkit. The results of the simulation are applied to the TUM40 detector module of CRESST-II phase 2. We are able to explain up to (68±16)% of the electromagnetic background in the energy range between 1 and 40keV .


Megahertz non-contact luminescence decay time cryothermometry by means of ultrafast PbI2 scintillator

Scientific Reports Springer Nature Publishing Group 9 (2019) 5274

VB Mykhaylyk, H Kraus, L Bobb, R Gamernyk, K Koronski

Realtime in situ temperature monitoring in difficult experimental conditions or inaccessible environments is critical for many applications. Non-contact luminescence decay time thermometry is often the method of choice for such applications due to a favorable combination of sensitivity, accuracy and robustness. In this work, we demonstrate the feasibility of an ultrafast PbI2 scintillator for temperature determination, using the time structure of X-ray radiation, produced by a synchrotron. The decay kinetics of the scintillations was measured over the 8–107 K temperature range using monochromatic pulsed X-ray excitation. It is found that lead iodide exhibits a very fast and intense scintillation response due to excitons and donor-acceptor pairs, with the fast decay component varying between 0.08 and 0.5 ns – a feature that can be readily exploited for temperature monitoring. The observed temperature dependence of the decay time is discussed in terms of two possible mechanisms of thermal quenching – transition over activation barrier and phonon-assisted escape. It is concluded that the latter provides a better fit to the experimental results and is consistent with the model of luminescence processes in PbI2. We evaluated the sensitivity and estimated the accuracy of the temperature determination as ca. ±6 K at 107 K, improving to ±1.4 K at 8 K. The results of this study prove the feasibility of temperature monitoring, using ultrafast scintillation of PbI2 excited by X-ray pulses from a synchrotron, thus enabling non-contact in-situ cryothermometry with megahertz sampling rate.


Low temperature scintillation properties of Ga2O3

Applied Physics Letters AIP Publishing 115 (2019) 081103

VB Mykhaylyk, H Kraus, V Kapustianyk, M Rudko

Gallium oxide has recently been identified as a promising scintillator. To assess its potential as a detector material for ionizing radiation at low temperatures, we measured the luminescence and scintillation properties of an undoped Ga2O3 crystal over the 7–295 K temperature range. The emission of the crystal is due to the radiative decay of self-trapped excitons and donor-acceptor pairs and peaks at a wavelength of 380 nm. The scintillation light output of the undoped Ga2O3 increases with a decrease in temperature, reaching a maximum value of 19 300 ± 2200 ph/MeV at 50 K. The measured luminescence kinetics has a recombination character with specific decay time (τ0.1) increasing from 1 to 1.8 μs at cooling. Since radiative decay in the crystal competes with nonradiative processes, material optimization could lead to the scintillator achieving a yield of 40800 ph/MeV, a figure considered to be an upper limit.


Bright and fast scintillation of organolead perovskite MAPbBr₃ at low temperatures

Materials Horizons Royal Society of Chemistry (2019)

V Mykhaylyk, H Kraus, M Saliba

We report the excellent scintillation properties of MAPbBr3, an organic–inorganic trihalide perovskite (OTP). The characteristic scintillation time constants were determined using pulsed monochromatic 14 keV X-rays from a synchrotron. We find that between 50 and 130 K the MAPbBr3 crystal exhibits a very fast and intense scintillation response, with the fast (τf) and slow (τs) decay components reaching 0.1 and 1 ns, respectively. The light yield of MAPbBr3 is estimated to be 90 000 ± 18 000 ph MeV−1 at 77 K and 116 000 ± 23 000 ph MeV−1 at 8 K.


Geant4-based electromagnetic background model for the CRESST dark matter experiment (vol 79, 881, 2019)

EUROPEAN PHYSICAL JOURNAL C 79 (2019) ARTN 987

AH Abdelhameed, G Angloher, P Bauer, A Bento, E Bertoldo, R Breier, C Bucci, L Canonica, A D'Addabbo, S Di Lorenzo, A Erb, FV Feilitzsch, NF Iachellini, S Fichtinger, A Fuss, P Gorla, D Hauff, M Jeskovsky, J Jochum, J Kaizer, A Kinast, H Kluck, H Kraus, A Langenkaemper, M Mancuso, V Mokina, E Mondragon, M Olmi, T Ortmann, C Pagliarone, V Palusova, L Pattavina, F Petricca, W Potzel, P Povinec, F Proebst, F Reindl, J Rothe, K Schaeffner, J Schieck, V Schipperges, D Schmiedmayer, S Schoenert, C Schwertner, M Stahlberg, L Stodolsky, C Strandhagen, R Strauss, C Tuerkoglu, I Usherov, M Willers, V Zema, J Zeman


Limits on dark matter effective field theory parameters with CRESST-II

EUROPEAN PHYSICAL JOURNAL C 79 (2019) ARTN 43

G Angloher, P Bauer, A Bento, E Bertoldo, C Bucci, L Canonica, A D'Addabbo, X Defay, S Di Lorenzo, A Erb, FV Feilitzsch, NF Iachellini, P Gorla, D Hauff, J Jochum, M Kiefer, H Kluck, H Kraus, A Langenkaemper, M Mancuso, V Mokina, E Mondragon, V Morgalyuk, A Muenster, M Olmi, C Pagliarone, F Petricca, W Potzel, F Proebst, F Reindl, J Rothe, K Schaffner, J Schieck, V Schipperges, S Schoenert, M Stahlberg, L Stodolsky, C Strandhagen, R Strauss, C Tuerkoglu, I Usherov, M Willers, M Wuestrich, V Zema, R Catena, CRESSTCollaboration


Characterisation of tungstate and molybdate crystals ABO<inf>4</inf> (A = Ca, Sr, Zn, Cd; B = W, Mo) for luminescence lifetime cryothermometry

Materialia 4 (2018) 287-296

N Ahmed, H Kraus, HJ Kim, V Mokina, V Tsiumra, A Wagner, Y Zhydachevskyy, VB Mykhaylyk

© 2018 Acta Materialia Inc. Luminescence lifetime thermometry for remote temperature monitoring of cryogenic objects requires materials that exhibit a suitably large change of the luminescence kinetics at low temperatures. Results of systematic studies of the temperature-induced changes in the luminescence of tungstates and molybdates with the general formula ABO4 (A = Ca, Sr, Zn, Cd; B = W, Mo) over the 4.5–300 K temperature range are summarized. It is shown through analysing changes of the emission and excitation spectra, as well as the decay kinetics, that in these materials the luminescence is due to the emission of self-trapped excitons, a process that exhibits strong temperature dependence. The main emphasis of the study is on establishing the factors that determine the character of the temperature dependence of the luminescence decay time constant. We discuss our findings in terms of a model that analyses the dynamics of radiative and non-radiative transitions between the excited and ground states of the emission center. Two thermally activated processes drive the observed changes. The first is the non-radiative decay of excited states, resulting in a decrease of the luminescence decay time constant at high temperatures. Additionally it is demonstrated that in molybdates and tungstates the fine splitting of the excited state facilitates a second mechanism for thermally activated exchange of charged carriers between the two split levels. This has a noticeable effect on the dynamics of the radiative decay at low temperatures. We established that the sensitivity of the luminescence lifetime to temperature changes can be estimated by using information on the energy structure of materials. It is concluded that within tungstates and molybdates under study SrWO4 is the most promising material for application in luminescence lifetime cryothermometry.

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