Table of contents

The authors investigate high-energy multiparticle production models in which Bose-Einstein symmetry leads to production of multi-pion final states with very high rapidity density in a limited rapidity region. They outline the possible experimental consequences and indicate where direct evidence of this phenomenon may be sought.

Two-body correlation functions obtained in a LOCV calculation on nuclear matter using the Reid soft-core potential are state averaged and then used to calculate the three-body convergence parameter kappa ₃ and three-body cluster energy E₃. kappa ₃ is found to be less than 0.1 for Fermi momenta k_F<or approximately=1.6 fm^-1 and the three-body cluster energy changes the saturation binding energy by a fraction of an MeV per nucleon. The inclusion of the three-body clusters does, however, significantly reduce the saturation density. The authors conclude that, allowing for explicit excitation of the N*(1234) and including up to three-body clusters, the Reid potential yields nuclear matter saturation properties close to those predicted by a semi-empirical analysis.

The authors have searched for precursors to air showers using a 0.64 m² scintillation detector system located under a thick layer of absorber inside a multiplate cloud chamber. They find no evidence for a finite flux of tachyon-like particles in an operating time of 3621 hours compared with the observation of six events in 40 hours with a 2.1 m² detector as reported by Ashton et al. (1977).

A synthesis for leptons and hadrons is proposed in terms of an SO(8)*SO(8) phenomenological symmetry. This leads to eight flavours of tricoloured quarks, four charged leptons and four neutrinos, but only a single new quantum number (style). The mesons and baryons of the scheme are exhibited, and predicted new phenomena (particularly in e⁺e^- annihilation) are discussed.

The Heitler-London-Pauling variational method is applied to the pi ^-nn system in a non-relativistic approach and no true bound state is found for conventional parametrisations of the pi N interaction.

The elastic, 2⁺ inelastic (4.43 MeV level) and total scattering cross sections of medium-energy pions on ¹²C have been calculated within Glauber theory using the microscopic alpha -cluster model. For the input the authors take the gaussian parametrised pi -N amplitude. It is found that the model gives a fairly good account of the scattering data. The agreement between the calculated and experimental angular distributions at higher energies is particularly good when the pi -N phase-shift solutions of Roper and Wright (1965) are used.

Nuclear radii derived from electron-scattering experiments are analysed along the whole periodic table. Differences of RMS radii of charge distributions are plotted against neutron number. The plot shows many shell effects throughout the periodic table.

Energy spectra of the nuclei for N=28, 22<or=Z<or=26 are calculated within the framework of the shell model by using a two-range central-plus-tensor potential proposed by Schiffer (1976). An inert ⁴⁸Ca core is assumed. Calculations are made in several basic vector spaces. Good isospin is included for the case of one proton excitation.

A prescription is given for the approximate evaluation of the Hill-Wheeler integral for the angular momentum coefficients. It is shown that the functional form of these coefficients for the ground-state band of deformed even-even nuclei is given by K(2J+1)exp(-J(J+1)/ sigma ²). Three methods are described to determine the parameters K and sigma ². This distribution is used to obtain a modified form for the Peierls-Yoccoz inertia parameter.

In the continuum shell model, the width of the ³/₂^-, ³/₂ resonance state at 15.1 MeV in the mirror nuclei ¹³C and ¹³N is calculated. If channel coupling and the Pauli principle are taken into account, the width calculated without external mixing and without isotensor components is of the correct order of magnitude. The calculations show that coupling to isospin-allowed channels which are closed plays an important role.

The single-particle potential, its isotopic spin dependence, symmetry coefficient and effective mass in nuclear matter have been calculated using a simple effective interaction consisting of a density-dependent delta-function repulsion and a gaussian attraction. The density dependence in the interaction has been considered in three different forms: rho ^2/3, rho ^1/3 and rho ^1/6. The three parameters of the interaction are determined so as to reproduce the correct binding energy and density in nuclear matter and the ground-state energy of ¹⁶O. With the above interaction, simple relations for the single-particle potential, symmetry coefficient, effective mass and other related quantities in nuclear matter are derived. It is found that the Hugenholtz-Van Hove theorem is satisfied exactly and the results for these quantities are in good agreement with those referred to in the literature.

An earlier suggestion of the authors (1976) that the proton optical-model potential has terms, both real and imaginary, which depend explicitly on angular momentum is hereby supported by a systematic study of proton scattering from ¹⁶O and ⁴⁰Ca at a wide range of energies, as well as ⁵⁸Ni and ⁵⁶Fe. Not only are the fits to data improved (in some cases the improvement is very great), but the extracted parameters show certain striking regularities which were less apparent in l-independent fits. We also make some general remarks concerning the status of phenomenological fits and the interpretation of l dependence.

The gamma rays and conversion electrons following the gamma decay of ¹⁴¹Ba obtained by mass separation of ²³⁵U fission products have been measured. The main features of the ¹⁴¹La level scheme were established on the basis of gamma-ray energies and intensities, internal conversion electron measurements and quantitative and qualitative gamma - gamma coincidences. A total of 144 gamma rays have been identified as belonging to the ¹⁴¹Ba decay. Conversion coefficients were determined.

A critical analysis of the Dorman, Ahluwalia and Ericksen (DAE) (1971) method of derivation of coupling functions for underground muon telescopes has been made. It is concluded that the differential response curve for sea-level muon telescopes as given by Ahluwalia (1975) is not realistic and also that the DAE method of deriving the coupling functions for underground telescopes is not justified.

Results are presented for the lateral distribution and the longitudinal development of electrons between an atmospheric depth of 550 g cm^-2 and 1100 g cm^-2 in air showers with sizes 3*10⁶ to 5*10⁹ observed at Mount Chacaltaya. The lateral distribution is compared with those determined at mountain altitudes and at sea level by other groups. The longitudinal development is also compared with the results of other groups and with theoretical predictions under various models of nuclear interactions.

Results are presented for the lateral distribution of muons with energies above 600 MeV in air showers with electron sizes 10⁷ to 10⁹ observed at Mount Chacaltaya. Results are also presented for the muon size spectrum at 644 g cm^-2 and the longitudinal development of muons from 550 g cm^-2 to 990 g cm^-2 for intensities 10^-8 m^-2 s^-1 sr^-1 to 10^-10 m^-2 s^-1 sr^-1.

The authors give the results of a two-year study of the cosmic-ray air-shower density spectrum at sea level. The experiment confirms the steepening of the spectrum at densities around 400 particles/m² and suggests that the spectrum flattens again at appreciably higher densities. They suggest an improved experiment to investigate this and show that it is capable of distinguishing between a number of hypotheses. The experiment is expected to give information on the overall cosmic-ray energy spectrum between 10¹⁴ and 10¹⁷ eV, the composition of the radiation in that range and phenomena producing high transverse momenta in high-energy particle interactions.