Response of CsI(T1) Crystals to Low-Energy Heavy Ions

The relative light output of thallium-activated cesium iodide was measured as a function of incident ion energy for ions of H, He, C, N, O, Ne, Ar, Kr, Xe, and Hg. Pulse height versus energy curves were obtained for protons from 1 to 100 keV, for helium ions from 10 to 100 keV, for carbon ions from 16 to 300 keV, for nitrogen ions from 40 to 200 keV, for oxygen ions from 20 to 200 keV, for neon ions from 30 to 200 keV, for argon and krypton ions from 60 to 200 keV, for xenon ions from 70 to 200 keV, and for mercury ions from 100 to 300 keV. In all cases studied here, the relation of the pulse height to incident ion energy is linear; the slope decreases as the mass is increased. The resolution (ratio of full width of the peak at half-maximum intensity to the peak central value) is approximately proportional to the inverse of the square root of the energy.