An effective potential operator, previously derived from a multiple-scattering series expansion of the exact transition amplitude for scattering two composite particles, is used in a high energy context to derive an approximate one-body Schrödinger equation by use of the closure approximation. The equivalent one-body equation is reduced to a set of coupled-channel equations which relates the entrance channel to the final excited states of the projectile and target. A Schrödinger equation for the coherent elastic amplitude is extracted from the coupled equations. Total and absorption cross sections are then derived on the basis of the Eikonal approximation and the assumption that the coherent scattering dominates the forward scattered amplitude. Unlike other models, the assumption that nuclear matter single-particle densities can be represented by nuclear charge distributions is not made. Instead, a method for extracting single-particle density distributions from nuclear charge distributions is presented. Comparisons with other theoretical models and with recent experimental data are also made. Finally, an experimental method for choosing between the Glauber approximation and the theory presented here is suggested.

The disappearance of collective flow effects in heavy ion collisions is investigated using a microscopic optical model formalism for estimating collision momentum transfers. Phenomenological expressions for the balance energy are obtained which agree very well with measurements for various experimental collision pairs and with results obtained from Boltzmann-Uehling-Uhlenbeck simulations.

Combination of F 'P+ with Br 'P+ or I 2P+ ground state atoms in the presence of singlet O2 'Ag, 'Xi, leads to formation of BrF B311(O+) or IF B311(O+), which were detected by observation of their band emission spectra (975>A>483 nm), B311(O+)+X1C+. It was shown that formation of BrF B311(O+) explicitly requires energy transfer from 0, 'Ag or 'Xi. The most probable excitation process is envisaged to occur by combination of Br "P+ + F 'P+ atoms (in the presence of a third body) to give BrF A311(l) (or possibly 311(2, 0-)), followed by collisional energy transfer from singlet oxygen with BrF A311(l) to BrF B311(O+).At least 38 new bands of the B+Xsystem of BrF have been identified, and the previously uncertain vibrational numbering of the B311(O+) state has been confirmed. Vibrational constants are reported for the first time for levels of the XIZ+ ground state up to v" = 10, corresponding to an energy of 6262 cm-' above v" = 0. The available data on the dissociation energy of BrF are briefly surveyed, and a value of Do (BrF) = 2.384 eV is favoured.For the B+X system of IF, many new bands have been observed, and vibrational constants for levels up to v" = 19 (10 381 cm-' above v" = 0) of the ground state are reported.Rotational analyses of the spectroscopically interesting 311t XIE+ absorption systems of the diatomic interhalogens have been made in detail for IBr,l ICI and BrCl.3 For the corresponding fluorides, ClF, BrF and IF, similar studies have not so far been undertaken, probably because of the extreme experimental difficulties. However, some vibrational analyses of CIF 311(O+)tX1Z+ 4 3 and BrF 3rI(l, 0+) c X I Z + 6* have been reported. A more promising approach is the use of emission spectra, and Durie has described the spectra of BrF and IF in emission from flames of Br, or I2 burning in F2,* as well as a rotational analysis of 24 bands of the 311(0+)-X'Z+ system of IF from a similar s o u ~c e . ~ The spectroscopy of all three molecules (ClF, BrF and IF), however, is still incomplete compared with that of IBr, IC1 and BrCl, whilst considerable uncertainties in the dissociation energies of these molecules, especially of BrF and IF, remain.In the present work, atom combination (of Br+F, and I+F) in the presence of singlet oxygen lAg, l Z : was found to give extensive band systems in emission due to the B311(O+)-X1E+ transitions of BrF and IF. The first data on the higher vibrational levels of the XIE+ ground states of BrF and IF are reported. EXPERIMENTALThe spectroscopic investigations were carried out with a fast-flow system (fig. l(a)), which was provided with two side-arms, around each of which was fitted a microwave discharge cavity. Atom flows in argon or oxygen carriers from the discharges were mixed and pumped at 150 N m-z total pressure along the flow tube. Ground-state F 'P atoms were produced by dissociation of Ar (B.O.C. 99.995 %)+CF4 (Air Products Ltd.) mixtures l o in discharge B ' . The second discharge (B) was used to produce flows of Br 2P+ or I 'P+ atoms by reaction

Within the context of a high energy double-folding optical potential approximation to the exact nucleus–nucleus multiple-scattering series, eikonal scattering theory is used to investigate the validity of geometric reaction cross sections in relativistic heavy ion collisions. The potential used includes a finite range interaction and nuclear single-particle densities extracted from nuclear charge distributions by unfolding the finite proton charge distribution. Pauli correlation effects are also included in an approximate way. The sensitivity of the predictions to the assumed interaction, Pauli correlation approximation, and nuclear density distributions is investigated. These results are in agreement with early predictions concerning the geometric nature of relativistic heavy ion collisions and in disagreement with a recent analysis, utilizing the zero range approximation, which suggested otherwise. Reasons for the lack of agreement between the analyses are also presented. Finally, approximate applicability limits for geometric reaction cross sections are determined.

The electron absorbed fraction in the anterior nose is estimated in the International Commission on Radiological Protection Publication 66 using the EGS4 Code and a cylinder model. The electrons are assumed to come from point sources lining the inner surface of the nose. Although the radioactive source particles are carried in dust, self-absorption in the dust is ignored. Consequently, the absorbed fractions published in ICRP 66 cannot represent the correct energy deposition in the basal cell region. In this work we estimate the energy lost by the emitted electrons inside spherical dust particles, which vary in diameter from 1 micron to 100 microns. The absorbed fractions in the basal cell layer are then estimated using the modified electron energy spectrum. To illustrate these effects, modified absorbed fractions for a dust particle radius of 20 microns are compared to the absorbed fractions presented in ICRP 66. Significant differences are noted.