Table of contents

The rotation of the spin in the coherent scattering of polarised thermal neutrons was calculated using empirical parity-violating potentials. The results obtained are up to an order of magnitude larger than expected on the basis of dimensional arguments. The sign of the effect depends on the isospin properties of the weak potential and can distinguish between potentials with large isotensor or large isovector components.

A unified treatment of large- and small-p_T particle production is discussed. When effects of momentum conservation are included correctly, a basic power-law p_T dependence has interesting consequences at present energies.

High spin states of the i_13/2 band in ¹⁵⁵Er have been populated using (¹²c, xn) reactions. Backbending-type behaviour appears, in sharp contrast with the heavier neighbouring odd erbium isotopes. The result apparently disagrees with the blocking effect of the rotation alignment model which is known to inhibit the development of the backbending mechanism. This suggests either that states other than i_13/2 are involved in the ¹⁵⁵Er backbending or that, due to strong vibrational effects, the rotation alignment model is not applicable.

alpha -spectroscopic amplitudes A_NJ are calculated for various (J^pi T=0) states of ¹⁶O using the shell model of Zuker, Buck and McGrory (1969). The n-particle-n-hole structure of the states is analysed in terms of the A_NJ. Good agreement with experiments is found. The relative strengths of the spectroscopic factors S_J correspond to the population rates of the states of ¹⁶O in direct reactions of the type ¹²C(A,A-4)¹⁶O.

Form factors for the inelastic scattering of electrons from the even-mass isotopes ^110-116Cd were measured. The B(E2 spin up) and Q(2₁⁺) deduced from these data confirm the results of a recent measurement of these quantities carried out by Coulomb excitation.

A simple density-dependent effective nucleon-nucleon interaction is used to show the effect of compressibility of nuclear matter on the real part of the n+⁴⁰Ca optical-model potential. It is found that the half-strength radius of the optical-model real potential decreases as the compression of nuclear matter increases.

Presents exact finite-range DWBA calculations using a realistic triton wavefunction for a series of (p,t) reactions on nuclei for which reliable spectroscopic factors are available. The theory predicts both the absolute magnitude and the shape of angular distributions and thus, for the cases studied, provides a test of the DWBA. The results obtained indicate that finite-range DWBA analysis of (p,t) reactions can probably provide additional information on the structure of nuclear wavefunctions.

A new simple-pole model for muon capture by ⁴⁰Ca with emission of neutrons is suggested, in close analogy with radiative pion capture, and the calculated energy spectrum of the emitted neutron agrees well with the experimental results of the Columbia group for higher neutron energies.

It is shown that the mass-asymmetry valleys, which appear in the fragmentation potential due to the shell effects of the fragments, are responsible (i) for the mass-asymmetry of the fission fragments, (ii) for the maximum of the fusion cross sections for the same compound system obtained by the different projectile-target combinations and (iii) for the asymmetry in the mass transfer in heavy-ion collisions. Due to the existence of different mass-asymmetry valleys for the same compound system, a new, highly asymmetric fission in which one of the fragments is close to the double magic nucleus ²⁰⁸Pb is predicted for transfermium nuclei including the superheavy nuclei.

It is shown that the lowest-order photon-photon scattering amplitude in quantum electrodynamics is manifestly gauge invariant when calculated using the dimensional regularization prescription.

The masses of charmed baryon states are predicted under the hypothesis of 15-plet dominance of SU(4) symmetry breaking, the analogue of octet dominance of SU(3) symmetry breaking. The breaking of SU(3) is completely determined by the masses of non-charmed baryons; to complete the specification of parameters, two independent charmed baryon masses are required. For this purpose, data from the Fermilab experiment of Knapp et al. (see Phys. Rev. Lett., vol.37, p.882 (1976)) are used. The 15-plet dominance hypothesis is then compared with other symmetry breaking schemes.

Presents an extensive study of hypercharge-exchange reactions within a dual Regge-cut model. Without any free parameter, a very satisfactory description of experimental data is obtained and predictions for the double charge-exchange reactions are presented. The scattering amplitudes obtained for the K* and K** quantum number exchanges agree fairly well with a universal behavior for vector and tensor exchanges.

From a study of the correlation of the longitudinal momenta of final-state nucleons in pd collisions, a classification of the event types has been effected. The event types identified are quasi-elastic (peripheral), central and charge-exchange collisions. Using the Van Hove LPS plot it is observed that those events classified as quasi-elastic are dominant and the nucleons resulting from the deuteron break-up in these collisions have approximately equal momenta. The quasi-elastic and the elastic events have been compared with the Glauber multiple scattering theory and are found to be well described by the model for small-angle scattering.

The quadrupole moments of heavy deformed nuclei are calculated in the pseudo-SU(3) model. It is found that they compare favourably with experimental values and the predictions of the Nilsson model.

For pt.III see ibid., vol.246, p.490 (1975). A variational calculation of the J=¹/₂⁺ bound and scattering state parameters of the three-nucleon system with the super-soft-core potential of Gogny, Pires and Detourreil (1970) is described. The triton binding energy is found to be -8.3+or-0.2 MeV, which is in good agreement with other calculations. The form-factor minimum is found to be q²=16.5 fm^-2 which is at rather high q² when the closeness of the binding energy to the experimental value is considered. The zero-energy n-D scattering length is found to be 2.8 fm, which again is significantly far from experiment.

The coherent state basis is employed to obtain, in the semiclassical limit, the Euler equation of hydrodynamics corresponding to the single-particle Schrodinger equation. This may also correspond to a collective vibrational mode of the system. By introducing unobserved modes, the concept of viscosity (and the Navier-Stokes equation) is extracted. The motivation for the study stems from the physics that underlies the increasing use of macro-concepts and of hydrodynamical ideas in nuclear physics, particularly in the description of heavy-ion reactions and of fission and fusion processes.

The relation between the surface thickness of proton and neutron density distributions in ²⁰⁸Pb, derived from Hartree-Fock calculations is discussed. The influence of the Coulomb interaction on the surface thickness is investigated in detail. The results are compared with recent Thomas-Fermi calculations.

Directional correlations of the strongly hindered 922 keV (E1-M2-E3) gamma ray with the subsequent 253 keV gamma ray of ¹⁸⁴W polarised in nickel foils at T=20 mK showed time-reversal-violating asymmetry equal to (-7.5+or-5.9)*10^-4. As a result, TRIV components of the E1, M2 and E3 multipole matrices appear to be less than approximately 10^-6, 10^-3 and 10^-3 Weisskopf units respectively.

The authors have studied the gamma rays and conversion electrons emitted in the decay of ¹⁰⁸Sn, and present a decay scheme for ¹⁰⁸Sn to levels in ¹⁰⁸In based on the results of the measurements. They interpret the 1⁺ level at 669 keV in ¹⁰⁸In as being due mainly to the ( pi g₉2/^-1 nu g₇2/) configuration and discuss the systematics of the beta transition between this level and the ( pi g₉2/²) configuration.

It is shown that an alpha -cluster preformation coefficient and an alpha -cluster level density can be calculated for nuclei or a pair of neighbouring nuclei for which the alpha radioactivity and (p, alpha ) reaction are measured. The analysis of these two kinds of alpha emission is made on a similar basis by applying the ideas of the 'exciton' model. The analysis of natural alpha radioactivity is then extended to all known alpha -decaying nuclei, in order to obtain the value of the alpha -cluster preformation coefficient.

Parastatistics with continuous order are proposed. The various parastatistics are used in scattering theory as an effective description accounting for the internal structure of composite particles (nuclei). Also investigated is the possibility that muons are (composite) para-particles.

The authors have tested, in the case of the ⁴He nucleus, the method of Delsanto and Quarati (see ibid., vol.2, p.161 (1976)) for elimination, from continuum calculations of nuclear reaction cross sections, of spuriosities deriving from the centre-of-mass motion. The results seem to indicate that the method is effective and the overall agreement satisfactory.

The energy spectrum of nuclear active particles (NAP) with energy Sigma E_gamma greater than 3 TeV is obtained from an analysis of thick emulsion chamber (140 cu of Pb) exposed on Mount Norikura at 2770 m above sea level and the vertical flux is estimated to be (1.4+or-0.1)*10^-10 cm^-2 s^-1 sr^-1. Assuming that the energy spectrum and the zenith angle distribution of NAP are expressed by power functions proportional to E^{-( gamma +1)} and cos^n-2 theta respectively in differential form, the exponents gamma and n are obtained as 2.3+or-0.1 and 7.3+or-0.5 respectively. The collision mean free path and the ratio of constituents of NAP are discussed.

The flux of charged hadrons has been measured at sea level with an iron calorimeter of depth 960 g cm^-2; the geometric factor was about 0.7 m² sr. The total running time was 1.6*10⁶ s. An upper limit to the flux of all hadrons has been obtained in the energy range 500<E<10000 GeV. It does not support the observation of a 'step' in the spectrum at about 3000 GeV.