Table of contents

Nuclear beams with energies of several TeV per nucleon are considered as carriers of intense fields of photons in the energy range up to 100 GeV. Cross sections for intermediate boson and Higgs production by two-photon collisions are predicted to be in the nanobarn range. Production of heavy neutral particles in peripheral collision could be easily detectable because of low background.

A new isotope ²²⁰At has been identified among the mass-separated products of a spallation reaction of ThO₂. Its half-life has been found to be 3.71+or-0.04 min. This isotope was identified through its beta decay to four excited levels in ²²⁰Rn known previously from the alpha decay of ²²⁴Ra.

Analytical expressions are given for slowly converging integrals involving three distorted waves encountered in the study of stripping to unbound states and zero-range post-form distorted waves Born approximation for break-up of light ions.

Weakly bound projectiles can break up in the Coulomb field of a target nucleus. This break-up may be a sequential process in which the projectile is first excited to an inelastic state through which it subsequently breaks up, or the projectile can break up rapidly without passing through an intermediate state. It is found that the angular scattering range over which the Coulomb field is dominant is different for these two types of break-up. An explanation of this difference is that the transition matrix element for direct break-up in the Coulomb field has large contributions from widely separated fragments in the initial projectile.

In relativistic theories particle number is not conserved (although both lepton and baryon number are). Therefore when discussing the thermodynamics of a quantum field theory one uses the grand canonical formalism: the entropy S is maximised, keeping fixed the ensemble averages E and N of energy and lepton or baryon number. To implement these constraints two Lagrange multipliers are introduced, beta =1/kT and mu the chemical potential.

On the basis of the analysis of experimental data the author suggests the possibility of an SU(3) 27-plet of dibaryons. The masses of the dibaryon 27-plet have been estimated. The dibaryon experiments favour pp, pn, Lambda p, Sigma ^-p, Lambda Lambda , Xi ^-p existence in the 27-plet. The theory of a 27-plet of dibaryons agrees with predicted results in the MIT bag model.

The effect of the quark structure of the nucleon on nuclear matter properties is investigated within a sigma - omega -q model.

The ground-state (GS) binding energies of the Xi ^-hyperon in the few known Xi ^- hypernuclei have been analysed by adopting a simple Xi ^--nucleus potential for which the Schrodinger equation can be solved analytically and in addition simple formulae for the nuclear part of the Xi ^- GS binding energy, kinetic and potential energy as functions of the mass number of the core nucleus A_c identical to A may be derived. For the Coulomb part of the interaction the diffuseness of the surface has been taken into account in the framework of an approximate procedure. A comparison has been made of the volume integrals of the Xi ^-nucleon and Lambda -nucleon potentials mod V_{Xi -N} mod and mod V_{Lambda N} mod by using estimates of the parameters involved by means of least-squares fittings. The value of the ratio lambda =V_{Xi -N}/V_{Lambda <or approximately=}N is found to be <or approximately=0.8. It is also found that similar conclusions are reached by using in the same way other potential models, such as the Woods-Saxon one.

An approximate formula is derived for the two-body term in the cluster expansion of the charge form factor of light nuclei (4<or=A<or=16). It contains the harmonic oscillator parameters b₁ and the parameter lambda which originates from the correlation function. The dependence of the correlation parameter lambda on the mass number is also discussed.

Mixed-symmetry 2⁺ states are identified in vibrational-like nuclei lying between the Z=20 and 28 closed shells. The M1 strengths of 2⁺-2⁺ transitions are obtained from level lifetimes and gamma -ray multipole mixing ratios. The latter were measured using the directional distribution of gamma -rays from an oriented source (⁵⁶Fe) and gamma gamma directional correlations on cascades which follow neutron capture (⁴⁸Ti, ⁵⁴Cr and ⁵⁸Fe). There is strong evidence for the sharing the characteristics of the mixed-symmetry 2⁺ level with neighbouring 2⁺ levels. The identification of a 4⁺-4⁺ transition with a large B(M1) value in ⁵⁶Fe indicates the need for g-bosons in the IBA-2 which is used as a framework for discussing the data.

The authors develop a many-body theory for the real part of the heavy-ion interaction potential at energies near the Coulomb barrier. The theory is similar to the constrained Hartree-Fock method, but uses two-centre shell-model wavefunctions rather than self-consistent wavefunctions. This approximation allows them to calculate potential energy surfaces for very heavy systems. The interaction energy depends on two collective parameters: internuclear distance R and fragment deformation beta . As in most Hartree-Fock theories, they use a Skyrme force whose parameters are fitted to nuclei throughout the periodic table. The Coulomb energy is evaluated with high precision from the single-particle wavefunctions. They present potential energy surfaces for the reactions ⁴⁰Ca+⁴⁰Ca, ⁹⁰Zr+9⁰Zr and ²³⁸U+²³⁸U.

Differential cross sections have been measured for the reactions (t,⁶He), (t,⁶Li), (t,⁷Li), (t,⁹Be) on ^12,13C; (t,⁸Li) on ¹³C; for (³He, ⁶Li) on ^12,13C and (³He, ⁷Be) on ¹²C over the range 10 degrees -100 degrees CM. For the (³He, ⁷Be) and (³He, ⁶Li) reactions on ¹²C, analysing powers were measured over the range 20 degrees -75 degrees CM. Finite-range DWBA analyses have examined the effects of different optical potentials, including spin-orbit potentials, and bound-state potential geometries. Microscopic descriptions of the alpha -projectile cluster wavefunction and a number of potential descriptions have been used to generate form factors for the alpha -pick-up reactions. Spectroscopic factors have been extracted for all the reactions and compared with shell-model calculations.