Growth and characterization of potassium strontium iodide: A new high light yield scintillator with 2.4% energy resolution

摘要

A new ternary metal halide scintillator, potassium strontium iodide, activated with divalent europium (KSr_2I_5: Eu) has been discovered. This material has a monodinic crystal structure with a density of 439 g/cm~3. Differential scanning calorimetry indicates a congruent melting point of 470 ℃ and suggests that this compound has no solid-solid phase transitions. As is the case with most metal halides, the material is hygroscopic, and it has some internal radioactivity due to the presence of ~(40)K Single crystals of KSr_2I_5 doped with 4% Eu~(2+) were grown in evacuated quartz ampoules via the Bridgman technique. The X-ray excited emission spectrum consisted of a single peak at ～445 nm due to the 5d-4f transition in Eu~(2+). The measured light yield is ～94,000 photons/MeV with an energy resolution of 2.4% at 662 keV. The crystal has an excellent proportionality response over a wide range of energies from 14 keV to 1275 keV.