Radioactive contamination of SrI2(Eu) crystal scintillator

TL;DR

This study characterizes SrI2(Eu) crystal scintillators, assessing their radioactivity, response to radiation, and potential for low-level counting applications, including rare decay searches.

Contribution

It provides detailed measurements of the intrinsic radioactivity and scintillation properties of SrI2(Eu) crystals, demonstrating their suitability for sensitive detection tasks.

Findings

Measured alpha/beta ratio of 0.55 at 7.7 MeV

No difference in scintillation pulse decay for alpha and gamma radiation

Potential for detecting rare nuclear decay processes with sensitivity around 10^{15}-10^{16} years

Abstract

A strontium iodide crystal doped by europium (SrI2(Eu)) was produced by using the Stockbarger growth technique. The crystal was subjected to a characterization that includes relative photoelectron output and energy resolution for gamma quanta. The intrinsic radioactivity of the SrI2(Eu) crystal scintillator was tested both by using it as scintillator at sea level and by ultra-low background HPGe gamma spectrometry deep underground. The response of the SrI2(Eu) detector to alpha particles (alpha/beta ratio and pulse shape) was estimated by analysing the 226Ra internal trace contamination of the crystal. We have measured: alpha/beta=0.55 at E_alpha=7.7 MeV, and no difference in the time decay of the scintillation pulses induced by alpha particles and gamma quanta. The application of the obtained results in the search for the double electron capture and electron capture with positron emission in 84Sr has been investigated at a level of sensitivity: T_1/2 \sim 10^{15}-10^{16} yr. The results of these studies demonstrate the potentiality of this material for a variety of scintillation applications, including low-level counting experiments.