Undoped Cs3Cu2I5 crystal - Candidate for dark matter searches: Temperature-dependent scintillation and luminescence

초록

Intrinsic scintillators offer significant advantages for advanced applications due to the uniform distribution of their luminescence centers. In this research, we investigated the luminescence and scintillation characteristics of undoped Cs3Cu2I5 crystals at room temperature and cryogenic conditions, comparing their potential for dark matter detection with that of CsI crystals. Like CsI, Cs3Cu2I5 is non-hygroscopic and exhibits a higher scintillation light yield. Typically, the light yield of intrinsic scintillators, such as undoped CsI and NaI, tends to increase at cryogenic temperatures, and we anticipate a similar trend for Cs3Cu2I5. To explore this further, we analyzed the scintillation properties of Cs3Cu2I5 down to 10 K under 662 keV gamma-ray excitation. Remarkably, the absolute light yield of Cs3Cu2I5 reached 150 ph/keV at 662 keV, significantly exceeding that of CsI under similar conditions. Additional studies employing photoluminescence and thermally stimulated luminescence across temperatures from 300 K to 10 K suggested that the enhanced scintillation yield at lower temperatures may be linked to self- activators' behavior in a free state. Simulations of the temperature-dependent energy transfer processes support this finding, highlighting the potential for improved light yields at cryogenic temperatures. These results confirm that undoped Cs3Cu2I5 crystals are promising for dark matter searches utilizing cryogenic methods.

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