Table of contents

Data on internal pair conversion in widely different nuclear transitions with energies above 12 MeV have an apparent excess in pairs around 9 MeV/ invariant mass. While the deviations individually may be circumstantial, in combination they appear to point to an overall anomaly.

The first successful application of an ion-guide separator (IGISOL) for collinear laser spectroscopy of radioisotopes has achieved an efficiency comparable with the best obtained with catcher-ionizer facilities. The ion beam energy spread was determined to be less than 6 eV, allowing laser fluorescence resonance signals for the radioisotopes to be detected with high resolution and sensitivity. Applications of this technique to measuring nuclear properties of refractory elements and short lived isomers promises to be particularly advantageous.

In this review we give a discussion of the structure of the standard model and its quantum corrections for testing the electroweak theory at present and future colliders. After a short summary of the tree level structure of the standard model we outline the calculation of physical quantities at the quantum level. Concrete applications are given to the vector boson mass interdependence and the Z resonance. Finally we show a comparision of the standard model prediction for the electroweak precision observables with the most recent experimental data.

Trajectories of S-matrix poles in the complex k plane are presented for a complex square well potential. The conformal character of the connection between the potential and the location of the poles is used to deduce the properties of these trajectories, including their behaviour for very strong absorption. Detailed results are presented for s and p states.

The method for calculating the scattering of composite particles with several kinds of constituent is studied. The formulae are derived and the method for sorting all Glauber expansion terms into several classes is given. The method of the integration is different from that of Lin and co-workers (Lin Z J et al 1991 J. Phys. G: Nucl. Part. Phys. 17 1159) and its analytical expressions are introduced. We calculate the D - D, P - P, P - and - P elastic scatterings. These results are compared with the data.

We stress that the observed pattern of flavour mixings can be partly interpreted by the quark mass hierarchy without the assumption of specific quark mass matrices. The quantitatively proper relations between the Kobayashi - Maskawa matrix elements and quark mass ratios, such as

are obtainable from a simple ansatz of flavour permutation symmetry breaking at the weak scale. We prescribe the same ansatz at the scale of supersymmetric grand unified theories, and find that its all low-energy consequences on flavour mixings and CP violation are in good agreement with current experimental data.

We have calculated the differential probability of the radiative decay, , of the -lepton carrying an anomalous magnetic moment. Taking into account both the inner bremsstrahlung and the structure-dependent radiation contributions, we computed the double differential probability. Observables, which are particularly suitable for the full reconstruction of the vector and axial form factors, are identified and implications for the measurement of the anomalous magnetic moment of the -lepton are discussed.

The processes of deep inelastic electron - proton (ep) scattering by charged current are suggested for investigation of the proton spin. An approach is proposed for the determination of the contributions of individual quark flavours and valence quarks to the proton spin. The electroweak radiative corrections of O to the observable quantities are calculated. The numerical calculations of the cross sections and the longitudinal polarization asymmetries taking into consideration electroweak corrections at HERA energies have been made.

The nucleon momentum and density distribution of the nucleus are calculated by using the Morse single-particle potential. The parameters for the momentum distribution are determined by fitting either the charge form factor to the available experimental data of the elastic electron scattering by or the momentum distribution to the corresponding `experimental' values. The calculations can be performed partly analytically and the results show a considerable overall improvement with respect to those obtained with the oscillator shell model. The rms radius of the charge density distribution determined by fitting the charge form factor is in very good agreement with the values obtained by means of model independent analysis.

Three- and four-neutron systems are studied within the framework of the hyperspherical approach with a local S-wave nn-potential. Possible bound and resonant states of these systems are sought as zeros of three- and four-body Jost functions in the complex momentum plane. It is found that zeros closest to the origin correspond to subthreshold (nnn) and (nnnn) resonant states. The positions of these zeros turned out to be sensitive to the choice of the nn-potential. For the Malfliet - Tjon potential they are (MeV) and (MeV). Movement of the zeros with an artificial increase of the potential strength also shows an extreme sensitivity to the choice of potential. Thus, to generate and bound states, the Yukawa potential needs to be multiplied by 2.67 and 2.32 respectively, while for the Malfliet - Tjon potential the required multiplicative factors are 4.04 and 3.59.

The lowest-order constrained variational (LOCV) method is developed for the wide range of phenomenological two-nucleon interaction operators such as , and U potentials. The calculation is performed for both nuclear and neutron matter with the state-dependent correlation operators. The validity of our lowest-order approximation is tested by calculating the three-body cluster energy with the state-averaged correlation functions. It is shown that while the three-body cluster energy improves the nuclear matter saturation density, the LOCV method still overbinds nuclear matter with the above potentials. Finally, we find that our LOCV results are similar to those calculations which have been performed by using more sophisticated many-body techniques.

We investigate the relevant nuclear matrix element for the neutrino-accompanied double beta decay of to the first excited -state in . We show, that most of the dependence of the matrix element can be removed by the inclusion of the Pauli principle in the QRPA-calculations. The matrix element remains stable in the physical region of and would thus allow to reduce limits of the decay.

The azimuthal angle correlations in pairs of projectile fragments (PFs) of charge Z = 2 and Z > 2 are studied in the Pb-emulsion interactions at GeV, as a function of their transverse momentum . The correlation strength increases with the centrality of the collision (except at b = 0), and is much larger than the Au data at GeV.

The influence of the nucleon - multi-channel on nucleon - nucleon phase shifts is studied as a coupled-channel problem in the framework of the resonating group method by using the quark-cluster model with chiral symmetry. It can be seen that additional attraction is generated in the nucleon - nucleon interaction by the coupling to the channel. The mechanism of couplings to nucleon - channels plays an important role in the isotriplet P-wave nucleon - nucleon interaction and solution to the spin - orbit problem, while couplings to the nucleon - channel have a smaller effect on higher partial waves.

We apply the QRPA formalism developed in previous works to study the excitation of the M1 mode through scattering on and . The agreement with experiment is comparable with that of the shell model for sd-shell nuclei. Having in view previous works for heavy and medium nuclei, one could conclude that the quasiparticle random-phase approximation (QRPA) is applicable to nuclei from a wide range of masses.

Overlap functions and spectroscopic factors extracted from a model one-body density matrix (OBDM) accounting for short-range nucleon - nucleon correlations are used to calculate differential cross sections of (p, d) reactions and the momentum distributions of transitions to single-particle states in and . A comparison between the experimental (p, d) and data, their DWBA and CDWIA analyses and the OBDM calculations is made. Our theoretical predictions for the spectroscopic factors are compared with the empirically extracted ones. It is shown that the overlap functions obtained within the Jastrow correlation method are applicable to the description of the quantities considered.

Elastic scattering of by , , , and nuclei at various incident energies up to 100 MeV per nucleon is investigated by the continuum-discretized coupled-channel (CDCC) method based on a double-folding model of the - nucleus interaction with a realistic energy- and density-dependent nucleon - nucleon interaction, called DDM3Y. The projectile breakup effect is found to diminish with increasing incident energies. A comparison of the present result with an earlier CDCC calculation, based on the cluster-folding-model interaction, shows a clear difference between the two for large angle scattering. Possible implications of this discrepancy are discussed.

The half-life of the positron emitter has been measured using liquid scintillation (LS) spectrometry and counting in the National Institute of Standards and Technology (NIST) `' - re-entrant ionization chamber (IC). A total of 12 independent LS measurements and two independent IC measurements were made, all of which spanned two to four half-lives. Weighted nonlinear fits of the data resulted in half-lives of 9.68 min 0.04 min and 9.673 min 0.026 min (uncertainties are combined standard uncertainties) for the LS and IC data, respectively (a difference of only 0.07%). The weighted mean of these two values is 9.67 min 0.03 min, which is shorter than the ENSDF-recommended value of 9.74 min 0.02 min by 0.7%. Since this radionuclide is being investigated for use in positron emission tomography (PET), this difference in the half-life has an important effect on the estimation of the amount of radioactivity administered to patients when decay corrections must be applied.

We study the nuclear deformation energy of superheavy nuclei by using the macroscopic - microscopic method. Nuclear shape is determined by three independent shape coordinates: separation distance between the fragment centres; mass asymmetry, and neck radius. The Yukawa-plus-exponential model gives the macroscopic energy. Shell and pairing (microscopic) corrections are calculated on the basis of a superasymmetric two-centre shell model. Various spherical magic numbers in the region of superheavy nuclei are obtained by changing the strength of the spin - orbit coupling in the two-centre shell model. A complete set of and values have been obtained leading to magic numbers up to 126 for protons and 184 for neutrons (including Z = 114, 120 and N = 172). Potential energy surfaces for nuclei , , and are plotted versus the separation distance and mass asymmetry. Compact shapes, typical for synthesis by fusion reactions or cold fission, are assumed.

Monte Carlo simulations of cosmic-ray-induced showers in the atmosphere have been used to develop three new methods for measuring the energy of the primary particles in the - eV range independently of the particle species. Both the electron number and Cherenkov light density near and beyond the hump in the lateral distributions are found to accurately indicate the primary energy, provided an appropriate correction based on the depth of the shower maximum is applied. The depth of the shower maximum can be estimated from the slope of the radial distribution of the Cherenkov light. In addition, a simultaneous measurement of the muon number and Cherenkov light intensity also provides a very accurate measure of the primary energy. All of these parameters can be determined by using existing particle detector arrays. A very precise measurement of the cosmic-ray all-particle spectrum regardless of chemical composition is thus shown to be practicable.

Momentum spectra of pions, muons, electrons and secondary positrons have been measured at an atmospheric depth of with the same instrument. Data was collected by the Matter Antimatter Space Spectrometer of the New Mexico State University in a balloon flight in September 1991 at the rigidity cut-off of in Fort Sumner, New Mexico.

The first measurement of the positive muon spectrum in the range to is reported in this paper. The spectral index above of the negative muon momentum spectrum of this measurement is in agreement with analytical cascade calculations which assume a primary proton kinetic energy spectrum with a slope of in the corresponding kinetic energy range. In the momentum interval 300 - , both negative and positive muon fluxes turn out to be larger than calculated fluxes by a factor of about 1.4.

The measurement of the secondary electron and positron energy spectra allows a reliable subtraction of the atmospheric background from the primary electron and positron fluxes which are affected by large uncertainties in most of the experiments. The energy spectra of the secondary particles reported here have the same systematic errors implying a higher relative accuracy with respect to those measurements made in different flights.

The bulk of the diffuse galactic gamma-ray emission above a few tens of GeV has been conventionally ascribed to the decay of neutral pions produced in cosmic-ray interactions with interstellar matter. Cosmic-ray electrons may, however, make a significant contribution to the gamma-ray spectrum at high energies, and even dominate at TeV - PeV energies depending on their injection spectral index and acceleration cut-off energy. If the injection spectrum is flat, the highest energy electrons will also contribute a diffuse hard x-ray/soft gamma-ray flux via synchrotron emission, and this may offer an explanation for the OSSE observation of a steep spectrum below a few MeV from the inner Galaxy. We perform a propagation calculation for cosmic-ray electrons, and use the resulting interstellar electron spectrum to obtain the gamma-ray spectrum due to inverse Compton, synchrotron and bremsstrahlung interactions consistently from MeV to PeV energies. We compare our results with available observations from satellite-borne telescopes, optical Cerenkov telescopes and air shower arrays and place constraints on the injection spectrum of cosmic-ray electrons. With future observations at TeV - PeV energies it should be possible to determine the average interstellar spectrum of cosmic-ray electrons, and hence estimate their spectrum on acceleration.