Timing limits of ultrafast cross-luminescence emission in CsZnCl-based crystals for TOF-PET, HEP and TOF-CT

Abstract

Cross-luminescence (CL) has been shown to be one of the promising scintillation mechanisms to overcome timing limitations in TOF-PET, TOF-CT or high energy physics. However, well-known CL-emitters (e.g. BaF2) have so far not been established in practice due to their disadvantages, mainly the emission in the deep-UV, calling for the need to develop new CL-emitting scintillators. One promising candidate is CsZnCl-based materials with a decay time ~1-2ns and light emission ~300nm. In this work, Cs2ZnCl4and Cs3ZnCl5are examined regarding their scintillation emission time profile and coincidence time resolution (CTR) read out with commercially available and research SiPMs. With 2x2x3mm³ crystals and a time-correlated single-photon counting (TCSPC) setup decay times of 1.79ns for Cs2ZnCl4and 1.03ns for Cs3ZnCl5were measured with no long tails in the scintillation emission time profiles, validating previously published measurements. Additionally, a prompt emission with significant abundance of 5% and 6% was discovered. Assuming a light yield of 1980ph/MeV for Cs2ZnCl4and 1460ph/MeV for Cs3ZnCl5, this relates to 122 (Cs2ZnCl4) and 73 (Cs3ZnCl5) ph/MeV energy deposit. CTR measurements with a high-frequency setup reached 60ps (FWHM) using Cs2ZnCl4coupled to FBK VUV SiPMs with silicon oil (Dow Corning 200), which is on par with state-of-the-art LYSO:Ce,Ca glue-coupled to NUV-MT SiPMs at 58ps. We find that the CTR of Cs2ZnCl4, air-coupled to VUV SiPMs, at 78ps (FWHM) is comparable to BaF2at 75ps (FWHM). With their fast decay time and high CTR, these crystals seem to be perfectly suitable for high-rate time-of-flight applications further supported by the non-hygroscopicity for Cs2ZnCl4and only slight hygroscopicity for Cs3ZnCl5. Further measurements and simulations are planned to explore the prompt emission and to investigate light transport and sensitivity.

Authors 8

1. Katrin Herweg Aachen Institute for Experimental Molecular Imaging Department of Physics of Molecular Imaging Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,Institute for Experimental Molecular Imaging,Department of Physics of Molecular Imaging Systems,Aachen,North Rhine-Westphalia,Germany

   Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, North Rhine-Westphalia, Germany

2. D. J. Rutstrom

   University of Tennessee at Knoxville

   Affiliation as printed

   University of Tennessee Knoxville,Scintillation Materials Research Center,Knoxville,Tennessee,United States of America

   Department of Materials Science and Engineering, University of Tennessee Knoxville, Knoxville, Tennessee, United States of America

   Scintillation Materials Research Center, University of Tennessee Knoxville, Knoxville, Tennessee, United States of America

3. Vanessa Nadig Aachen Institute for Experimental Molecular Imaging Department of Physics of Molecular Imaging Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,Institute for Experimental Molecular Imaging,Department of Physics of Molecular Imaging Systems,Aachen,North Rhine-Westphalia,Germany

   Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, North Rhine-Westphalia, Germany

4. Luis Stand

   University of Tennessee at Knoxville

   Affiliation as printed

   University of Tennessee Knoxville,Scintillation Materials Research Center,Knoxville,Tennessee,United States of America

   Department of Nuclear Engineering, University of Tennessee Knoxville, Knoxville, Tennessee, United States of America

   Scintillation Materials Research Center, University of Tennessee Knoxville, Knoxville, Tennessee, United States of America

5. Charles L. Melcher

   University of Tennessee at Knoxville

   Affiliation as printed

   University of Tennessee Knoxville,Scintillation Materials Research Center,Knoxville,Tennessee,United States of America

   Department of Materials Science and Engineering, University of Tennessee Knoxville, Knoxville, Tennessee, United States of America

   Scintillation Materials Research Center, University of Tennessee Knoxville, Knoxville, Tennessee, United States of America

6. Mariya Zhuravleva

   University of Tennessee at Knoxville

   Affiliation as printed

   University of Tennessee Knoxville,Scintillation Materials Research Center,Knoxville,Tennessee,United States of America

   Department of Materials Science and Engineering, University of Tennessee Knoxville, Knoxville, Tennessee, United States of America

   Scintillation Materials Research Center, University of Tennessee Knoxville, Knoxville, Tennessee, United States of America

7. Volkmar Schulz Aachen Institute for Experimental Molecular Imaging Department of Physics of Molecular Imaging Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,Institute for Experimental Molecular Imaging,Department of Physics of Molecular Imaging Systems,Aachen,North Rhine-Westphalia,Germany

   Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, North Rhine-Westphalia, Germany

   Hyperion Hybrid Imaging Systems GmbH, Aachen, North Rhine-Westphalia, Germany

8. S. Gundacker Aachen Institute for Experimental Molecular Imaging Department of Physics of Molecular Imaging Systems

   RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University,Institute for Experimental Molecular Imaging,Department of Physics of Molecular Imaging Systems,Aachen,North Rhine-Westphalia,Germany

   Department of Physics of Molecular Imaging Systems, Institute for Experimental Molecular Imaging, RWTH Aachen University, Aachen, North Rhine-Westphalia, Germany