Precise measurement of the scintillation decay constant of ZnWO$_4$ crystal

TL;DR

This study precisely measured the scintillation decay time of ZnWO$_4$ crystals, revealing directional dependence and anisotropic light yield, which are crucial for optimizing detector performance.

Contribution

The paper provides the first detailed measurement of the directional dependence of decay constants and scintillation yield in ZnWO$_4$ crystals.

Findings

Decay time constant varies with incident direction, up to 24.3 μs.

Scintillation yield is anisotropic and correlates with decay time.

Maximum yield observed on the surface perpendicular to the b-axis.

Abstract

The scintillation decay time constant of a ZnWO$_4$ crystal irradiated with $\alpha$-particles from $^{241}$Am was precisely investigated, and was found to depend on the incident direction of the $\alpha$-particles on the crystal. The longest decay time constant ($24.3\pm0.6~\mu$s) was obtained on the surface perpendicular to the b-axis of the crystal (Surface B). On Surfaces A and C, the decay constants were $20.0$ and $21.3\pm0.2~\mu$s, respectively. The scintillation yield of the ZnWO$_4$ was also anisotropic and depended on the incident direction of the heavy particles. The maximum yield was achieved on surface B, suggesting a correlation between the light yield and scintillation decay time constant of ZnWO$_4$ crystals.