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The addition of small amounts of iodide to the silver bromide is known to have a significant effect on the photographic properties of silver halides. The change in the photographic sensitivity depends on both the concentration and distribution of iodide ions. Hence, it is important to obtain detailed information on the chemical bonding and compositional distribution of iodide in silver halide alloys. The depth distribution of iodide ions was determined with the ISS (ion scattering spectrometry) technique at both the top and bottom (111) surface layers of AgBr0.97I0.03, AgBr0.94I0.06 and AgBr0.90I0.10 sheet crystals grown on a flat Vycor® (quartz) substrate. ISS data show that iodide ions are more heavily segregated at the last-solidified surface. For the first-solidified surface, there is a smaller enhancement of iodide ions within the top 100 A region relative to the rest of the near-surface region. Systematic fluorescence EXAFS (extended X-ray absorption fine structure) and SEXAFS (surface EXAFS) measurements were made at 35 ± 5 K on both the Br and I absorption edges to study the local iodide distribution, bonding and structure of the top surface and bulk layers. EXAFS and SEXAFS data show that there are significant differences in the local iodide distribution and silver ion vacancy concentration between the bulk and surface layers. These differences vary with the concentration of iodide ions in the samples. For the bulk layers, there are no changes in the local iodide distribution and silver vacancy concentration as a function of iodide concentration, in contrast to the surface layers where significant differences were observed. Changes in the iodide concentration, local iodide distribution and silver vacancy concentration have negligible effects on the nearest-neighbor distances for both the surface and bulk layers. The nearest-neighbor I-Ag and I-Br distances are found to be slightly larger that the corresponding Br-Ag and Br-Br distances.

The results of an experimental study of the binding energies of light hypernuclei are presented, based on a sample of 2008 uniquely identified π − mesonic decays. The problems of the calibration procedure and the selection criteria are discussed. Various aspects of the Λ -N interaction are reviewed in the light of these new results.

In this experiment the relative rates of production of charged Σ hyperons by the capture of K- mesons on neutrons and protons in the heavy (silver and bromine) and the light emulsion nuclei (carbon, nitrogen and oxygen) have been measured. From these results it is concluded that there is a large neutron excess present in the outermost regions of heavy nuclei.

The energy and momentum distributions of 1454 (Σπ) pairs, separated between those produced by K− meson interactions occuring on the light (carbon, nitrogen and oxygen) and on the heavy (silver and bromine) emulsion nuclei, have been studied. The Auger electron yield in heavy nuclei for events of this type has been measured.

Twenty examples of π+ mesonic decays of light hypernuclei have been found together with 7000 π− mesonic decays. The ratio R4 of π+ mesonic decays for the gL4 He hypernucleus has been computed from the results of this work and those of a previous experiment [1] and is found to lie between the values 5.4 ± 1.5%1.7% and 6.9 ± 1.8%2.1%. The π+ mesonic decays of other species of hypernuclei are briefly discussed.