Table of contents

The authors demonstrate the possibility of pionic bubbles with small numbers of pions within the framework of their pi -nucleus interaction model proposed recently. It turns out that many nuclear phenomena observed at intermediate energies can be associated with this concept.

A comment on, and disagreement with, the recent conclusion of Klarsfeld et al. (see ibid., vol.10, p.165, 1984) that the D/S ratio for the deuteron is nearly independent of the pi NN coupling constant is given.

The authors dispute the contention that the deuteron properties alone provide a precise determination of the pi NN coupling constant f².

Energies and widths are calculated for the states of two rotational bands in ¹⁶O.

An optical-model potential for the d+⁶Li system is calculated using high-quality wavefunctions of the nucleus ⁶Li found previously. The problem of the low-energy extrapolation of the latest experimental data on the d-⁶Li reaction cross sections which are important for future high-temperature thermonuclear reactors is examined. This approach yields higher values compared with the standard extrapolated values for the low-energy reaction cross sections in the d-⁶Li system. The calculated cross sections are tabulated.

Supersymmetric generalisation of the four-fermion interactions in one spatial and one time dimension is studied. In order to supersymmetrise four-fermion interaction models such as the Gross-Neveu or Thirring models it turns out that one needs to introduce a supercurrent which contains the covariant derivative of the superfield in its structure. The Lagrangian constructed from this supercurrent therefore also has derivative couplings in the interaction. It is shown that the supersymmetric Gross-Neveu model up to one loop is finite and that the ultraviolet overlapping divergences of two loops cancel each other.

Using a nuclear physics approach, the authors investigate the orbital angular momentum dependence in the baryonium J^P=1^- production in the reaction pp pi ^-X⁺. Although the calculated cross section for l=0 states is larger than the experimental upper limit, they show that the existence of l=2 'nuclear type' baryonium states cannot be discarded.

Simple expressions for the single-particle transverse (current) response function and its sum rule are derived in terms of the Wigner transforms (WT) of the single-particle wavefunctions, leading to a semiclassical interpretation of the results. For finite nuclei, the harmonic-oscillator (HO) model is used to derive simple analytic expressions for the transverse (current) response function and its sum rule. A comparison is made with the results of the Fermi-gas (FG) model.

The level scheme of ⁸⁶Y was investigated by gamma -ray spectroscopy with ⁷⁶Ge(¹⁴N, 4n) and ⁷³Ge(¹⁶O, p2n) reactions. New energy levels, spins and parities in the yrast sequence above the known isomeric 8⁺ states were indicated. The possible structure of these states is discussed in connection with an observed similarity with the yrast states in both odd and even-even neighbouring nuclei.

An alpha-particle and gamma-ray investigation of ²¹⁵Fr was performed by means of the reaction ²⁰⁸Pb(¹¹B, 4n). Gamma-ray angular distributions, gamma - gamma and alpha - gamma coincidences time centroid shifts and pulsed-beam isomeric decay rates were measured. Excited states were observed up to spins of about ⁴⁷/₂ and 3.5 MeV excitation energy. An interpretation of the results is given in terms of a particle-hole analysis based on the Woods-Saxon single-particle potential.

The zero-angle finite-range approximation (ZAFRA) is introduced for coupled-reaction-channels (CRC) calculations involving nucleon transfer. The ZAFRA has been incorporated into an existing CRC program, CHUCK3 retaining the full projectile spin capabilities and enabling rapid calculations of normal-parity transfers to be made. Fits are presented to a number of nucleon transfer reactions which show reasonable agreement with previously published exact-finite-range (EFR) and no-recoil (NR) calculations.

Microscopic calculations of the l=0-5 phase-shifts for p+¹²C elastic scattering in the centre-of-mass incident energy range 0-18 MeV have been carried out using the single-channel resonating group method (RGM) and a purely central two-nucleon interaction. A complex generator coordinate technique has been used to evaluate the various matrix elements involved in the RGM calculations. For the ground state of the ¹²C nucleus a harmonic-oscillator shell-model wavefunction consisting of 19 Slater determinants which yields values of the RMS radius and charge form factor in good agreement with experiment has been used. Full antisymmetrisation has been performed in the calculation of all parts of the kernel functions except that corresponding to the Coulomb interaction. The calculated phase-shifts show the presence of sharp resonances for l=0 and 1 and a broad resonance for l=2. The differential cross sections for incident centre-of-mass energies of 1.75, 4.30, 8.86 and 14.95 MeV have also been calculated and are found to be in fair agreement with the experimental data.

Spectra of gamma rays in coincidence with incident stopped pi ^-, 220 MeV pi ^-, and 180 MeV pi ⁺ were taken with ²³Na and natural S targets. Spectra were also taken with incident 180 MeV pi ⁺ and 220 MeV pi ^- for a ³¹P target. The cross sections of a variety of levels in residual nuclei formed by single-, two- and multi-nucleon removal were observed, determined and analysed. The morphology of these spectra suggests a mixture of direct and cascade/evaporation processes. Cross sections calculated with an intranuclear cascade/statistical evaporation code are in good agreement with the majority of the cross sections observed for multi-nucleon removal processes.

The correlation of gamma-ray intensity with column density of atomic hydrogen and with the intensity of the ¹²CO line has been studied in the first and fourth galactic quadrants. If a simple linear relation is assumed between the ¹²CO and molecular hydrogen for the COS B observations then the results indicate that in the galactic plane ( mod b mod <or approximately=3.5 degrees ) the relative gamma-ray emissivity for H₂ to H I falls as the gamma-ray energy increases. This feature is not observed in local gas (nor is it apparent in the analysis of the SAS II observations). Accepting the phenomenon, interpretations centre on the likelihood of the standard conversion of ¹²CO to H₂ being faulty because of the effect of the galactic 'metallicity gradient' and the presence of discrete sources of gamma rays with a steep spectrum (perhaps from sources of cosmic-ray particles) associated with giant molecular clouds.

This paper discusses measurements of depths of maximum obtained by the use of the width of pulses of Cerenkov radiation produced by extensive air showers having sea-level sizes in the range 6*10⁵-10⁷ particles. These new data are analysed with the assistance of simulated pulse shapes incorporating actual instrumental responses. A discussion of the interpretation of this analysis emphasising selection effects of the Cerenkov detectors and of the particle array is given.

Size spectra of electrons (N_e) and muons (N_mu ) are obtained from the Akeno extensive air-shower experiment. The primary spectrum estimated from each spectrum is the same and is expressed by J(E₀)dE₀(4.0-5.0)*10^-23(E₀/10^15.67)^{- gamma} dE₀ m^-2 s^-1 sr^-1 where gamma =2.62+or-0.12 below and gamma =3.02+or-0.05 above 10^15.67 eV. There is no other significant change of slope in either the electron or the muon size spectrum beyond the corresponding energy 10^15.67 eV.

The mechanism of the formation of anomalous relativistic ion interactions is analysed on the basis of the modified nuclear pionisation model. Anomalous interactions are shown to occur in heavy-ion collisions at energies greater than approximately 10 GeV/nucleon. It is found that the existing selection criterion for central collisions is inapplicable in such an energy range and for heavy projectiles. It is predicted that the growth of the average transverse momentum of secondaries in central heavy-ion collisions is more rapid than that in hadron-hadron interactions.