Fluorescent Response of CsI(Tl) to Energetic Nitrogen Ions

The light output of a CsI(Tl) crystal was measured as a function of energy for nitrogen ions from 2.9 to 23.8 Mev, for $\alpha$ particles up to 5.30 Mev, and for $\gamma$ rays of 73, 279.2, and 411.8 kev. The particle energy was varied with absorbing foils. The response to nitrogen ions was proportional to energy up to about 16 Mev. Above this energy a slight curvature of the response curve away from the energy axis was observed. The response to $\alpha$ particles was linear above about 3.5 Mev and extrapolated to ∼1 Mev on the energy scale. The light output from the $\gamma$ rays was proportional to their energy and parallel to the linear portion of the $\alpha$-particle response. The specific fluorescence $\frac{\mathrm{dL}}{\mathrm{dx}}$ appears to be an increasing function of the specific energy loss $\frac{\mathrm{dE}}{\mathrm{dx}}$.