Luminescence and Scintillation Characterization of Sodium-Based Tungstate (Na₂W₂O₇) Crystal for Dark Matter Search

A Na2W2O7 single crystal was grown with a conventional Czochralski technique in a platinum crucible. A solid-state reaction method was used for the preparation of the polycrystalline compound. Temperature-dependent luminescence and scintillation properties of the crystal were studied under the excitation with a 280 nm light-emitting diode (LED) source, an X-ray source, and a 90Sr (beta) source. At different temperatures (from 300 to 10 K), an as-grown crystal's luminescence and scintillation light output was compared with a CaMoO4 crystal. Although the light output of Na2W2O7 crystal at room temperature is lower than CaMoO4 crystal, at 10 K, it is almost comparable. Compared to room temperature, the crystal's luminescence and scintillation light output at 10 K were increased by 17 and 14 fold, respectively. The decay time of the crystal was studied between 300 and 10 K using a 280 nm LED excitation source, and it varies from 3 s (300 K) to 94 s (10 K). A thermoluminescence (TL) study was carried out between 10 and 550 K. The kinetic parameters of the TL peaks are calculated with various standard methods. The current result suggests that the studied crystal has good potential as a cryogenic detector for dark matter search experiments in the near future.