is the most promising. SrI 2 (Eu) emits into the Eu 2+ band, centered at 435 nm, with a decay time of 1.2 µs and a light yield of up to 115,000 photons/MeV. It offers energy resolution better than 3% FWHM at 662 keV, and exhibits excellent light yield proportionality. Transparent ceramics fabrication allows production of Gadolinium-and Terbium-based garnets which are not growable by melt techniques due to phase instabilities. While scintillation light yields of Cerium-doped ceramic garnets are high, light yield non-proportionality and slow decay components appear to limit their prospects for high energy resolution.We are developing an understanding of the mechanisms underlying energy dependent scintillation light yield non-proportionality and how it affects energy resolution. We have also identified aspects of optical design that can be optimized to enhance energy resolution.

We report observations of nonequilibrium charge state distributions of slow, highly charged ͑331 # q # 751͒ ions after transmission of thin carbon foils. Charge equilibration times are determined directly from the dependencies of exit charge states on projectile velocity ͑0.5 3 10 6 , y , 10 6 m͞s͒ and foil thickness (5 -10 nm). Ions like Xe 441 and Au 681 are found to equilibrate inside of solid matter in a time of only 7 fs. [S0031-9007(99)09368-0]

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