Data for the fragmentation of high energy gold projectiles were recently analyzed by Dreute et al. with the assumption that the average A/Z ratio of the residues was equal to that of the projectile. The momenta of the projectile fragments from this analysis were dramatically larger than expected. We point out that the assumption of a constant A/Z is inconsistent with a large body of data and leads to an overestimation of both the fragment mass and the momentum distribution. A better description of the variation of the residue A/Z ratio can be found in the prescription developed by Sümmerer et al. based on a broad range of data.

In reply to the Comment of Morrissey we present the standard deviations σ of distributions of transverse momentum components under the assumption that the ratios A/Z of fragments are determined by the parametrization of Sümmerer et al. These results do not change in comparison to those derived with a ratio A/Z equal to that of the projectile as presented by Dreute et al.

We have reformulated the relativistic theory of internal bremsstrahlung in electron capture (IBEC) and developed a numerical code for calculating a transition amplitude for any initial atomic state. All relativistic as well as screening effects are included within the independent-particle approximation. We have shown the advantage of the theory even in the pole-dominance region of the IBEC spectra, thus making it suitable for comparison with the observed spectra in experiments that search for light- and/or heavy-neutrino mass components. In addition, we have applied our code to study the interference effects in the IBEC transition amplitude of ${}_{}{}^{163}{}_{}{}^{}\mathrm{Ho}$ and found, in agreement with experimental data, a smaller interference suppression than predicted by several recent models.

The NN→NΔ reaction is investigated within the coupled πNN-NN theory. The model predictions for the differential cross section, production asymmetry, and spin-correlation parameters are compared with the Argonne data at ${\mathit{T}}_{\mathit{N}}^{\mathrm{lab}}$=0.57, 0.81, and 1.01 GeV. Short-range effects are introduced through the ρ-exchange contribution. The overall quality of the results is satisfactory, except for the triplet part of the production asymmetry at the two highest energies. The role of the ${}_{}{}^3{}_{}{}^{}$${\mathit{F}}_3$${\to }^5$${\mathit{P}}_3$ amplitude in this problem is assessed.

We show that a one-pion-exchange potential with a softer πNN form factor, as suggested by the axial vector form factor rather than a nucleon-nucleon interaction, gives a reasonable fit to the deuteron properties. This is achieved by considering the dressed pion propagator, in terms of quark-antiquark states. From this result we may get an insight into the problem of the softness of the πNN form factor of the realistic nucleon-nucleon interaction.

A search for the population of superdeformed (SD) states in ${}_{}{}^{194}{}_{}{}^{}\mathrm{Pb}$ following the ${\mathrm{\beta }}^{+}$ decay of ${}_{}{}^{194}{}_{}{}^{}\mathrm{Bi}$ was performed with the UNISOR on-line isotope separator at the Oak Ridge National Laboratory. The β decay of ${}_{}{}^{194}{}_{}{}^{}\mathrm{Bi}$, with its large ${\mathit{Q}}_{\mathrm{\beta }}$ value and high spins of the decaying isomeric states, provides a favorable opportunity to search for population of known SD states in the daughter nucleus, ${}_{}{}^{194}{}_{}{}^{}\mathrm{Pb}$. Both γ rays and conversion electrons were measured in singles and coincidence; however, no evidence for the population of SD states was observed. Upper limits for the population of certain SD states are presented. A possible explanation for the lack of SD band population following this β decay is discussed.

High spin states in the N=50 nucleus ${}_{}{}^{93}{}_{}{}^{}\mathrm{Tc}$ were populated and studied using the reaction ${}_{}{}^{66}{}_{}{}^{}\mathrm{Zn}$ ${(}^{31}$P, 2p2n${)}^{93}$Tc at a beam energy of 115 MeV. Gamma ray intensities and gamma-gamma coincidences were measured. Multipolarities of the transitions were extracted assuming stretched transitions. The positive and negative parity bands have been extended up to spins 39/$2^{+}$ and 43/$2^{\mathrm{-}}$, respectively. The proposed level scheme above J=25/2 cannot be well understood on the basis of the spherical shell model calculations with valence protons occupying the (1${\mathit{f}}_{5/2}$,2${\mathit{p}}_{3/2}$,2${\mathit{p}}_{1/2}$,1${\mathit{g}}_{9/2}$) configuration space. The breaking of the N=50 neutron core appears to be a plausible mechanism for the observed high spin states.

The ${}_{}{}^{223}{}_{}{}^{}\mathrm{Fr}$ β decay was reinvestigated using high-resolution single γ spectrometry as well as γ-γ coincidence techniques. For single γ-spectra measurements, radiochemically pure ${}_{}{}^{223}{}_{}{}^{}\mathrm{Fr}$ sources were obtained by chromatographic separation from a 75 MBq activity ${}_{}{}^{227}{}_{}{}^{}\mathrm{Ac}$ parent source and continuously purified of ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ and daughters. The analysis of the γ spectra of 30 sources showed the existence of 131 γ lines, of which 87 are reported for the first time in the ${}_{}{}^{223}{}_{}{}^{}\mathrm{Fr}$ β decay although many of them are observed following the ${}_{}{}^{227}{}_{}{}^{}\mathrm{Th}$ α decay. The ${}_{}{}^{223}{}_{}{}^{}\mathrm{Fr}$ half-life was remeasured and found to be ${\mathit{T}}_{1/2}$=22.00±0.07 min. γ-γ-t coincidence measurements were also carried out with ${}_{}{}^{223}{}_{}{}^{}\mathrm{Fr}$ purified sources. The ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ level scheme was built on the basis of our γ data, as well as ${}_{}{}^{227}{}_{}{}^{}\mathrm{Th}$ α-decay data. Among the 32 excited ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ levels, of which 22 were also known from ${}_{}{}^{227}{}_{}{}^{}\mathrm{Th}$ α decay, 13 are newly reported from ${}_{}{}^{223}{}_{}{}^{}\mathrm{Fr}$ β decay. Low energy levels (E<400 keV) may be classified as parity doublet bands according to the predictions of the reflection asymmetric rotor model. Above a 700 keV gap, a coexistence of symmetric and asymmetric shapes including both static and dynamic octupole correlations is suggested.

High spin states with angular momentum up to 21ħ in ${}_{}{}^{84}{}_{}{}^{}\mathrm{Y}$ have been established for the first time through the discrete-line γ-ray spectroscopy using the ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$${(}^{28}$Si,2pn${)}^{84}$Y reaction at 98 MeV. The experimental level scheme exhibits rotational characteristics with a large signature splitting and also signature inversion at I=11ħ. Theoretical calculations using the particle-rotor model with axial symmetry provide a good description of the observed phenomena.

Coulomb breakup is a very promising alternative method to the proton capture on radioactive ions, in order to extract gamma widths needed in astrophysics. A reanalysis of the Coulomb breakup experiments on ${}_{}{}^{14}{}_{}{}^{}\mathrm{O}$ shows one present weakness of the method and the need for further theoretical development of the formalism.

The ${\mathit{K}}^{+}$ production cross section far below the free nucleon-nucleon production threshold is estimated in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{12}$C collisions using simulations of the Boltzmann and the Boltzmann-Langevin equations. Fluctuations increase substantially the cross sections especially at low beam energies. We also give an estimate of the ${\mathit{K}}^{+}$ yield in ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$${+}^{42}$Ca collisions at an incident energy of 90 MeV/nucleon in order to compare our result to recent experimental data obtained in a similar system by Julien et al.

High-spin states in ${}_{}{}^{186}{}_{}{}^{}\mathrm{Hg}$ with a quadrupole deformation of ${\mathrm{\beta }}_2$=0.34(4) have been established from measured gamma-ray coincidences and lifetimes. These data, which provide the first evidence for a deformation midway between normal and super deformed, can be interpreted in terms of the [651] 1/2 and [770] 1/2 neutron configurations.

Elastic scattering of pions from finite nuclei is investigated utilizing a contemporary, momentum-space first-order optical potential combined with microscopic estimates of second-order corrections. The calculation of the first-order potential includes (1) full Fermi-averaging integration including the Δ propagation and the intrinsic nonlocalities in the π-N amplitude, (2) covariant kinematics, (3) invariant amplitudes, and (4) a finite-range off-shell pion-nucleon model which contains the nucleon-pole term. The Δ nucleus interaction is included via the mean spectral-energy approximation. This approach produces a convergent perturbation theory in which the Pauli corrections (treated as a second-order term) cancel remarkably against the pion true-absorption terms. Parameter-free results, including the Δ-nucleus shell-model potential, Pauli corrections, pion true absorption, and short-range correlations, are presented.

Different p¯p→Λ¯Λ transition mechanisms [K+${\mathit{K}}^{\mathrm{*}}$ exchange, K exchange only, and quark-gluon exchange ${(}^3$${\mathit{S}}_1$ version)] are investigated in a full coupled-channel (p¯p,Λ¯Λ) calculation. The elastic part of the p¯p and Λ¯Λ interactions has been derived from a one-boson-exchange version of the Bonn NN potential and a corresponding extension to the hyperon-nucleon case whereas the annihilation part is taken into account by phenomenological optical potentials. As expected, results for spin observables differ substantially for the different transition models. It turns out that resulting polarizations and spin correlation parameters are quite sensitive to variations in the initial- and final-state interactions whereas spin-transfer parameters are much more stable in this regard. Therefore, the latter observables, especially the depolarization ${\mathit{D}}_{\mathit{n}\mathit{n}}$, can be used to discriminate between various transition scenarios.

The angular distribution of nucleons from a kinematically complete measurement of pions absorbed in ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ on nucleon pairs with isospin T=0 and T=1 at incident pion energies of 119, 206, and 300 MeV are presented. The T=0 data are quite similar to pion absorption data in deuterium. The integrated absorption cross sections scale within errors with the number of isoscaler neutron-proton pairs. The T=1 cross sections, which correspond to absorption on dineutrons, are an order of magnitude smaller. The angular distributions for isovector absorption show a significant asymmetry, indicating interference effects between amplitudes with or without Δ isobars in the intermediate states. The existence of a significant three-nucleon absorption component is established. The integrated absorption cross sections for processes involving two and three nucleons were determined. The neutron and proton momentum probability densities in ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ were determined from the spectator recoil resulting from quasifree two-nucleon pion absorption.

The ppγ reaction at intermediate energies is investigated using a modern relativistic meson-exchange potential model. Both the single-scattering and rescattering terms are treated including relativistic corrections. It is shown that for energetic photons in the region near the end-point energy the relativistic spin correction is very large and reduces the ppγ cross section by a factor of ∼2. This large correction is dynamical in origin and can be traced in a very simple way to the strong energy dependence of the ${}_{}{}^1{}_{}{}^{}$${\mathit{S}}_0$ state contribution. It is also shown that, under these kinematical conditions, the rescattering term reduces the cross section, which amplifies the relativistic effects on the ppγ reaction. For the kinematical conditions of the recent TRIUMF experiment at ${\mathit{T}}_{\mathrm{lab}}$=280 MeV the rescattering contribution enhances the cross section and reduces the discrepancy between the data and the calculation.

A class of Lagrangians that describe the interaction of nucleons and pions and that provide a nonlinear representation of chiral symmetry is considered. We simplify the form of these Lagrangians by making an expansion in inverse powers of ${\mathit{f}}_{\mathrm{\pi }}$ and calculate the irreducible fermion-fermion scattering amplitude to order ${\mathit{f}}_{\mathrm{\pi }}^{\mathrm{-}4}$. Some of the integrals encountered in these calculations are divergent and are regulated with a (Euclidean) momentum-space cutoff, Λ, where Λ≃1 GeV. While elements of the S matrix are independent of the form of the Lagrangian used, somewhat different results are obtained for the irreducible amplitudes calculated with Lagrangians that have either pseudoscalar or pseudovector coupling of the pion field to the nucleon. We compare our results for the isoscalar irreducible amplitudes to the potentials used in the one-boson-exchange model of the nucleon-nucleon force. In the case of pseudovector coupling, there is only a single relevant diagram of order ${\mathit{g}}^4$, a ‘‘crossed-box’’ diagram. We find that this crossed-box diagram is well represented by the exchange of a ‘‘pseudo-eta’’ particle, that is, an isoscalar-pseudoscalar meson with an imaginary coupling constant. There is also a relatively small scalar attraction seen, while tensor, vector, and axial vector terms are quite small. We also consider a Lagrangian with pseudoscalar coupling. In this case, there are four diagrams of order ${\mathit{g}}^4$ in the irreducible amplitude. Again, we find a significant attractive pseudoscalar exchange term (‘‘pseudo-eta’’). Relatively small repulsive interactions of vector and scalar type are also found in this case. Further analysis of the isoscalar amplitude requires that we extend our model to reproduce the dynamics of correlated two-pion exchange.

We study the properties of the three-boson system with absorption, through a short range interaction in the limit where the range reduces to zero. We derive an analytic expression for the three-boson width that relates it to the real part of the three-boson energy, two-boson binding energy, and decay constant. One of the characteristics of this expression is that, in this limit, the ratio between the width and the three-boson binding energy is proportional to the range.

Low temperature nuclear orientation measurements have been made to study the nuclear magnetic dipole moments of ${}_{}{}^{72}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{g},}{}_{}{}^{}$m, ${}_{}{}^{73,74}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{m}}{}_{}{}^{}$, ${}_{}{}^{75,76}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{g}}{}_{}{}^{}$, and ${}_{}{}^{77}{}_{}{}^{}\mathrm{Br}_{}^{\mathit{g}}{}_{}{}^{}$ implanted into Fe. The analysis of the data has been performed within the framework of a two, nonzero field, site model to describe the occupation of Br nuclei in the host Fe lattice. The two sites were associated with magnetic hyperfine fields of ±81.38(6) and ±26(2) T. A spin of 1/2 for the ${}_{}{}^{73}{}_{}{}^{}\mathrm{Br}$ ground state is deduced and magnetic dipole moments are determined for the remaining nuclides. In addition, conversion electrons were observed for ${}_{}{}^{72}{}_{}{}^{}\mathrm{Br}$, confirming the multipolarity of the isomeric transition. An interpretation of the ground-state configurations and shapes of these isotopes is given using particle-rotor calculations and it is shown that the Br nuclides can be better described as a hole in the more deformed Kr nuclides rather than a particle beyond the Se cores.