Table of contents

Starting from the relativistic time-dependent Hartree-Fock approximation, the relativistic hydrodynamical equations coupled to a classical scalar field are derived. The pressure and stress tensors get defined automatically with the assumption of a local density approximation. In various approximations, the authors' equations reduce to those studied in the literature and the calculated sound velocity is precisely the same as that of other authors.

A technique, using the orthonormal basis for roots and weights of compact Lie groups, introduced by Van der Waerden and developed by Dynkin provides a convenient framework for discussing mass relations in grand unification theories. The structure constants N_{alpha beta} for SU(R+1), O(2R+1), Sp(2R), O(2R), and G(2) are obtained in an appendix, using an approach arising from this basis. The method for obtaining generators of non-regular subalgebras, in terms of generators of the original algebras, is discussed in terms of the basis. It is necessary to know this structure in order to trace the history of particles, originally in some grand unification group, through the various chains of decomposition into subgroups. As an illustrations, the methods are applied to finding the minimal, non-trivial, mass relations for fermions in the O(10) grand unification scheme.

Investigates the existence of a self-coupling, non-Abelian isospin gauge field. The authors assume that the rho meson is the gauge field for the isospin group, and it couples to pions and itself via the prescription of Yang-Mills theory. The decay rho to pi pi gamma would show an effect of a few per cent up to 32% due to this non-linear coupling, as opposed to the normal coupling. The production of a rho -meson pair in e⁺e^- to rho ⁺ rho ^- can also show up such an effect in the rho -meson pole energy region.

The polarisation in proton-nucleus scattering is studied within the Glauber model, in particular its sensitivity to the shapes of the input proton-nucleon amplitudes. The authors show that the polarisation is conveniently considered as a superposition of two terms. One, which is smooth, is identical to the proton-nucleon polarisation. The other, which is small, oscillates with a frequency determined by the nuclear size. Its strength depends sensitively on the shapes of the proton-nucleon amplitudes.

Considers the behaviour of the three-particle scattering length in the limit of zero binding energy of a target, assuming that the interaction of an incident particle with the target particles has no resonance character. In this case, the three-particle scattering length is shown to be the sum of the elementary scattering lengths, i.e. rescatterings vanish in this limit.

The quasi-elastic break-up of 187 MeV ¹²C ions into alpha and ⁸Be fragments is investigated. The contribution of this channel to the inclusive alpha spectrum is considered. For those break-up events in which the relative energy between the fragments is below 2.3 MeV, the break-up process proceeds primarily through discrete states of ¹²C rather than a direct break-up of the projectile.

The nucleus ⁹¹Mo has been investigated in the excitation energy region between 2.2 and 6.2 MeV by means of the ⁹²Mo (³He, alpha ) reaction at 25 MeV incident energy. Forty-three levels have been observed with 25-30 keV energy resolution and angular distributions were measured between 5 degrees and 50 degrees . DWBA analysis has led to unambiguous l assignments for most levels. Fifteen previously unknown l=3 levels are observed around 4 MeV. These levels could be interpreted as components of the f_7/2 neutron-hole strength, but the summed spectroscopic factors are much lower than the shell-model sum-rule limit. In addition, 14 l=1 levels were observed between 3 and 6 MeV excitation energy.

Levels and transitions in ²²⁷Ac were investigated by measuring perturbed and unperturbed gamma gamma directional correlations and gamma -ray distributions from oriented nuclei. The ensemble of oriented nuclei was prepared by diffusing ²³¹Pa into a gadolinium host and cooling to 16 mK. The multipole mixing ratios of six transitions were evaluated and spin-parity assignments to a number of levels were confirmed. Singles and coincident spectra were measured and the relative intensities of transitions with E_gamma >or=120 keV were obtained and the great majority of these were placed in the decay scheme. The data are consistent with previous interpretations of this nucleus in the context of the Nilsson model.

Models involving the production of cosmic-ray protons and heavier nuclei of energies in the range 1-10 GeV in extragalactic space are considered and the fluxes of gamma rays expected from their interactions with gas in clusters of galaxies are derived. Comparison with observation allows limits to be set on the fraction of the cosmic-ray flux detected at the Earth which is derived from extragalactic sources. It is found that for all reasonable models of extragalactic origin an excess of gamma -ray flux would result; thus, the bulk of the 1-10 GeV cosmic rays detected appear to be of Galactic origin.

The design of a large-volume underground anticoincidence detector is presented, together with the results obtained from it. The detector was situated at a depth of 62 hg cm^-2 and consisted of a 1 m cube of liquid scintillator surrounded by anticoincidence detectors. The performance of the system has been investigated extensively and the energy spectrum of anticoincidence events obtained. An examination of these events shows that they are due mainly to bremsstrahlung from electrons knocked on by muons in the rock surrounding the detector. An excess, of the order of a few per hour, of time-correlated events at times of less than 1000 mu s has been found and these are shown to be due to neutrons produced by muons in the surrounding rock.

The experimental situation of the density spectrum is a confused one. Cloud chambers offer the most direct access to the spectrum; their measurements, including new data, and their limitations are examined here. Experimental evidence shows that a mass above a chamber as thick as 0.6 radiation lengths can seriously distort a spectrum from that measured by a 'thin'-walled chamber of 0.1 radiation lengths. Thin chambers at mountain altitude and sea level show a sudden steepening of the exponent at high densities that is statistically significant. Monte-Carlo simulations of density spectra from an assumed primary spectrum reveal that normal interactions of proton primaries cannot reproduce the results. Other density spectra are examined and triggering selection bias emerges as a strong reason why some spectra are discordant.

Pairs of cloud chambers at sea level and Sulphur Mountain provide information on the type of shower structures involved in producing EAS density spectra. This is sufficient to allow deduction of a unique variation of shower structure with shower size that exactly reproduces the spectra: one that rapidly rejuvenates at sizes smaller than but close to the size at which the size spectrum steepens exponent and then abruptly commences to age slowly at this size and beyond. A sudden change in nuclear interaction characteristics at the commencement of steepening of the primary energy spectrum seems to be indicated.