We are working to perfect the growth of divalent Eu-doped strontium iodide single crystals and to optimize the design of
SrI2(Eu)-based gamma ray spectrometers. SrI2(Eu) offers a light yield in excess of 100,000 photons/MeV and light yield
proportionality surpassing that of Ce-doped lanthanum bromide. Thermal and x-ray diffraction analyses of SrI2 and EuI2
indicate an excellent match in melting and crystallographic parameters, and very modest thermal expansion anisotropy.
We have demonstrated energy resolution with SrI2(4-6%Eu) of 2.6% at 662 keV and 7.6% at 60 keV with small crystals,
while the resolution degrades somewhat for larger sizes. Our experiments suggest that digital techniques may be useful
in improving the energy resolution in large crystals impaired by light-trapping, in which scintillation light is re-absorbed
and re-emitted in large and/or highly Eu2+ -doped crystals. The light yield proportionality of SrI2(Eu) is found to be
superior to that of other known scintillator materials, such as LaBr3(Ce) and NaI(Tl).
This paper was published in SPIE Proceedings Vol. 7449