Track-Effect Account of Scintillation Efficiency for Random and Channeled Heavy Ions of Intermediate Velocities

The high-velocity formulation of the track-effect theory of scintillation efficiency is generalized for applicability at intermediate velocities (velocities spanning the peak in $\frac{\mathrm{dE}}{\mathrm{dx}}$) and applied to room-temperature data for ${\mathrm{O}}^{16}$ in NaI(Tl) both for random and channel trajectories. A core-correction term is incorporated into the representation of $\frac{\mathrm{dE}}{\mathrm{dx}}$. Electron velocities are taken into account in the calculation of track width $R_{max}\mathrm{}\left(v\right)\mathrm{}$. The contribution to $\frac{\mathrm{dL}}{\mathrm{dE}}$ from the region of high energy-deposit density is included. Quantitative agreement within experimental error is achieved for the ${\mathrm{O}}^{16}$ random-response data over the range $0.9\le v\le 3.6$, where $v$ is in units of ${10}^9$ cm/sec, including the region of intermediate velocities characterized by a reversal of curvature and leveling off of $\frac{\mathrm{dL}}{\mathrm{dE}}$. The channel response is treated only so far as to indicate applicability of the theory. Values for the ratio $\frac{\left[\frac{\mathrm{dL}}{\mathrm{dE}}\right(\mathrm{channel}\left)\right]}{\left[\frac{\mathrm{dL}}{\mathrm{dE}}\right(\mathrm{random})+]}$ are accounted for both in approximate magnitude and qualitative dependence on particle velocity.