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A Monte Carlo random walk model was used to study the creation and dynamics of F- and H-centers induced by electron irradiation in alkali-halide single crystals. The purpose of the study was to observe the effects of depth dependent electron energy deposition near the surface region using beam energies of 500 eV or less and relatively low currents (< 100 μA/cm2). The calculations were carried out using the parameters appropriate for an FCC LiF single crystal at room temperature. Depth dependent dynamics of F- and H-centers are also presented as well as F—H center recombination rates, and thermal and non-thermal halogen production rates at the surface. The model demonstrates that F—H center recombination dramatically affects the F-center distribution. F-center distributions are found to be peaked at the surface and do not reflect the initial energy deposition profile.

In initial observations during Auger studies of NaCl, we have observed stable, clearly resolved Auger peaks. With time, however, some of the Auger spectra reveal the occurrence of strong negative charging. This charging appears to be a result of irradiation-induced accumulation of sodium metal on the sample surface. We report the dependence of the strong negatively charged state on temperature. The results are consistent with the above model; the strongly negatively charged surface cannot be maintained at temperatures sufficiently high that sodium metal evaporation occurs.

In this study we observe that the positions of Auger signals shift from slightly below (∼10 eV) the tabulated values to well above (>150 eV). The observed shifts can be understood by a simple model of surface charging based on the change in the secondary electron emission of the damaged region.

The rate of radiated photons per electron passing through a helium-filled \ifmmode \hat{C}\else \^{C}\fi{}erenkov counter is observed to oscillate as a function of the gas pressure when a weak, static magnetic field is applied. The data agree well with an analysis which treats \ifmmode \hat{C}\else \^{C}\fi{}erenkov and synchrotron radiation as limiting manifestations of a unified process.

Presents a theoretical analysis of a hexapole magnet used for state selection and focusing of the F=1, mF=0 hyperfine state in hydrogen masers. The analysis determines the relative importance of the magnet properties and the geometry of the beam system in providing state selection and focusing. This in turn shows how the system may be optimised for minimum hydrogen flow at a given level of maser oscillation, thereby improving frequency stability (via reduction of the spin exchange interaction) and increasing operating time for a given volume of hydrogen gas.