Table of contents

An apparent inconsistency in the data which involve the pion form factor, the P-wave isovector pi pi phase-shift and the pion charge radius is examined by using only fundamental properties of the pion form factor.

It is shown that new mass-asymmetry valleys appear in the fragmentation potential V(l, eta ) as function of the length l and mass-asymmetry coordinate eta =(A₁-A₂)/(A₁+A₂) at larger values of eta . These valleys are due to a correct treatment of the shell effects such that for separated fragments the shell effects equal the sum of the shell effects of the individual fragments and correspond to the double magic fragments ⁴⁸Ca, ⁷⁸Ni, ¹³²Sn and ²⁰⁸Pb or maybe ⁵⁶Ni. It is also shown that the fission mass distributions have additional peaks corresponding to the bottom of these new valleys. The calculations are illustrated for ²⁵²No and ²³⁸U. The preliminary results show relatively high percentage yields for ²³⁸U, in agreement with present available experimental data.

Backward pion photoproduction is studied in an effective pole model with N_alpha , N_gamma , and Delta _delta effective poles. Information from other related reactions is studied, in particular that relating to the size of the Delta _delta contribution and the ratio of contributions from isoscalar and isovector photons. This information is then incorporated into an effective pole model for backward gamma N to pi N and a fit to existing data achieved. Further experiments are suggested.

Glauber multiple-scattering theory is applied to an analysis of the elastic and inelastic scattering of 1.37 GeV alpha particles on ¹²C. An approach which treats the N- alpha amplitude at an incident nucleon kinetic energy equal to the alpha -kinetic energy per particle as the basic interaction is adopted. Using the gaussian model for ⁴He to obtain the N- alpha amplitude in terms of the NN amplitude it is found that, in general, the experimental data may be explained qualitatively. However, large discrepancies in terms of the magnitude of the cross sections in the small-angle region and the positions of the minima in the angular distribution at larger angles are generally present. Effects of the two-body correlation in the projectile as well as in the target are also investigated.

The technique of lowest-order constrained variational calculations used by the authors to study the bulk properties of homogeneous, quantal fluids (1978) is extended for use in discussing the ground-state properties of finite nuclei. The significance of various constraints in finite systems is discussed. It is shown that the saturating effects of explicit allowance for N*(1234) excitations is essential if the calculations are to yield sensible binding energies and RMS radii. Specific application is made to the light closed-shell nuclei ⁴He, ¹²C and ¹⁶O.

The structure of nuclear states up to J^pi =12⁺ is investigated in the even-A scandium isotopes ^44,46,48Sc. The investigations are carried out in the framework of the Hartree-Fock projection formalism by employing a realistic nucleon-nucleon interaction. An inert ⁴⁰Ca core is assumed and all the valence nucleons are treated explicitly in the configuration space of the full pf shell. The energy levels, static moments and electromagnetic transition probabilities are evaluated from band-mixing calculations wherein the lowest six energetically close intrinsic states of the nuclei are taken into account. The theoretical results are in fair agreement with the available experimental data.

The difference between the exact T-matrix and the DWBA amplitude is shown to be the stationary value of a certain functional. Generalised unitarity is used to separate the on-shell and off-shell parts of that value. An expansion of that functional in terms of multi-step processes leads to Pade approximants.

The iterative R-matrix (IRM) method has been applied to the study of the ¹²C(p,p)¹²C reaction below 8 MeV using a collective rotational model for the target nucleus. The predictions of the method employing the natural boundary conditions and the lowest four basis states per channel have been found to be substantially better than the corresponding standard R-matrix calculations with the boundary condition parameter b_c=0 and the channel radius a_c=6.0 fm in all channels. The results for the phase-shifts and inelasticity factors for J^pi =¹/₂⁺, ³/₂⁺ and ⁵/₂⁺ obtained using the IRM method are generally in good agreement with the equivalent coupled-channels calculations, and hence with the corresponding phase-shift analyses of the experimental data in the energy region of interest.

The level structure of ⁸⁰Br has been studied by the ⁸¹Br(p,d) reaction with 22.8 MeV incident protons. Forty excited levels up to 2.0 MeV have been identified. The angular distributions for 39 of the observed transitions are compared with distorted-wave Born approximation calculations. Angular momentum transfers are determined and spectroscopic strengths are deduced from the data. These results are compared with the results of previous studies of ⁸⁰Br.

The excitation functions for the reactions ¹⁴N(n,2n)¹³N, ¹⁹F(n,2n)¹⁸F, ⁵⁴Fe(n,2n)⁵³Fe, ²⁷Al(n,p)²⁷Mg and ²⁷Al(n, alpha )²⁴Na between 14.7 and 19.0 MeV were measured by the activation technique, relative to the ⁵⁶Fe(n,p)⁵⁶Mn reaction. Uncertainties from 3 to 10% are approximately 99% confidence level were achieved. The results are compared with some recent evaluations, and large discrepancies are found in some cases. The neutron flux independent ratio of the important secondary standard cross sections ²⁷Al(n, alpha )/⁵⁶Fe(n,p) showed very good agreement with the measurements of Robertson et al. (1973), and Santry and Butler (1964), but not with the evaluations. The half-life of ⁵³Fe was measured as 8.62+or-0.06 min, where the random uncertainty is at approximately 99% confidence level.

The local synchrotron emissivity spectrum is derived from radio observations in the anticentre direction, using absorption optical depths derived from the distribution of the diffuse H alpha radiation and statistical properties of radio galaxies at low frequencies. The corresponding electron spectrum, which relates largely to regions of the Galaxy of median distance some 600 pc away from the Sun, is deduced for the range 100 MeV-1 GeV and comparison is made with the 'local' spectrum (at the Sun) derived in a quite different way on the basis of the ratio of measured fluxes of electrons and positrons in the primary radiation. The gamma -ray data of the Cos-B experiment are analysed in terms of the respective contributions from electron bremsstrahlung and proton interactions and the ratio of the flux of electrons to protons is determined; this relates to the electron spectrum at distances from the Sun in the range 2-4 kpc.