Speaker
Description
Recent results of neutrino oscillations have shown that neutrinos have masses. However, the results do not provide absolute masses and properties of neutrinos. To answer these questions, many experiments have been being carried out or prepared. One of the experiments is the Advanced Mo Based Rare Process Experiment (AMoRE) searching for the neutrino-less double beta decays (0ν2β) of 100Mo isotopes in 48deplCa100MoO4 scintillation crystals at mK temperatures [1]. Due to a background from 2ν2β decays from 48Ca and a limitation in calcium purification below an acceptable level [2], new molybdate-based scintillation crystals for the AMoRE phase-II are necessary. If a scintillation crystal containing the molybdenum emits a high enough light output, it can be a candidate scintillator for the neutrino-less double beta decay experiment. This study reports on a growth of a Cs2Mo2O7 single crystal and new results related to scintillation properties of the grown crystal.
We synthesized raw powders in a sintering process and confirmed the compound via an X-ray diffraction pattern. For the crystal growth, we also checked the phase transition of the compound via a Differential Scanning Calorimetry (DSC). After growing the single crystal by a Czochralski method, we prepared a sample for a luminescence property measurement.
Temperature dependences of emission spectrum and decay time were measured from 10 K to the room temperature. We used a 280 nm light emitting diode (LED) as an excitation source for the emission spectrum and a 266 nm pulsed type laser for the decay time due to its high intensity. In addition, we measured the emission spectrum of a Li2MoO4 crystal to compare the relative light output with the Cs2Mo2O7. Since the Li2MoO4 crystal is well studied, we selected it as a reference. The new results of the Cs2Mo2O7 crystal show that Cs2Mo2O7 can be a candidate scintillator for the neutrino-less double beta decay experiment. We also measured transmittance of the crystal at a room temperature.
Keywords: Neutrino-less double beta decay, Scintillation properties, Czochralski technique, Cs2Mo2O7 crystal, Li2MoO4 crystal.
References
[1] V. Alenkov et al., arXiv:1512.05957v1, 18 Dec 2015.
[2] V.B. Mikhailik and H. Kraus, Phys. Status Solidi B, 247 (2010) 1583–1599.
