The reaction ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ (${\mathrm{\pi }}^{+}$,pp)pn was measured at ${\mathit{T}}_{\mathrm{\pi }}$=500 MeV. The angular distribution of quasifree two-body absorption which was obtained agrees in detail with the free πd→pp reaction and scales according to the number of T=0 pn pairs in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. Possible evidence for pd final-state interactions is discussed. The extrapolated total cross section for four-body absorption is 2.5±0.6 mb, which is substantially less than predicted from a model based on ΔΔ excitation.

High-spin states in the neutron-deficient ${}_{}{}^{113}{}_{}{}^{}\mathrm{I}$ nucleus have been investigated for the first time using the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$${(}^{58}$Ni,3pγ) reaction. Gamma-ray coincidence data were acquired with the Eurogam spectrometer in conjunction with the Daresbury recoil mass separator. A deformed intruder band has been established extending to a spin approaching 40ħ and excitation energy 30 MeV. A possible structure for the band is discussed. This is the first evidence for such a band in this mass region with Z>51.

Lifetimes of low-spin members of the superdeformed band in ${}_{}{}^{135}{}_{}{}^{}\mathrm{Nd}$ have been determined by the Doppler-shift recoil-distance method. We find a quadrupole moment of 7.$2_{\mathrm{-}1.5}^{+1.2\mathrm{}}$ b for the 677 keV (37/2- 33) / 2 ) transition in the band, confirming the large deformation previously measured by the Doppler-shift attenuation method. However, the quadrupole moment for the 620 keV transition deexciting the 3.324 MeV (25/2) state at the bottom of the band is much smaller. We conclude that the superdeformed potential-energy minimum disappears or the band drastically changes character at this point which causes the sudden depopulation.

Dynamical instabilities arising from fluctuations in the spinodal zone for nuclear matter are studied using a large variety of zero range interactions in the frame of a pseudoparticle model. Scale times for spinodal decomposition are extracted and a possible link with decomposition in real heavy-ion collisions is discussed.

A full three-body calculation for the tensor analyzing powers of ${}_{}{}^1{}_{}{}^{}\mathrm{H}$(d→,γ${)}^3$He over the energy range of available data is presented. The Paris two-nucleon interaction is used in the three-body equations and the electromagnetic transition is calculated with the Siegert E1 operator. Reasonable agreement with all the data is obtained only when full three-body dynamics and the nucleon-nucleon P-wave interactions are present in the initial state.

Effective optical potentials for intermediate energy alpha particles are discussed. It is shown that the strong refraction substantially reduces the absorption in the center of the nucleus.

The chaotic dynamics in nuclear collective motion is studied in the framework of a schematic shell model which has only monopole and quadrupole degrees of freedom. The model is shown to reproduce the experimentally observed global trend toward less chaotic motion in heavier nuclei. The relation between the current approach and the earlier studies with bosonic models is discussed.

The need to include dynamical collision momentum transfer contributions, arising from interacting nuclear and Coulomb fields, to estimates of fragment momentum distributions is discussed. Methods based upon an optical potential model are presented. Comparisons with recent experimental data of the Siegen group for variances of transverse momentum distributions for gold nuclei at 980A MeV fragmenting on silver foil and plastic nuclear track detector targets are made. The agreement between theory and experiment is good.

Modified methods for computing multifractal moments ${\mathit{G}}_{\mathit{q}}$ and scaled factorial moments ${\mathit{F}}_{\mathit{q}}$ in terms of a new scaled variable X suggested by Bialas and Gazdzicki, have been employed to study the self-similar behavior of particle production in interactions ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ at 14.5A GeV, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ at 60A and 200A GeV, and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ at 200A GeV with nuclear emulsion. Power-law dependences of the moments on the number of bins M of the new variable (X) have been observed in the data.

A new experiment to investigate the isospin sensitivity of the parity nonconserving (PNC) interaction in light nuclei is proposed. The observable is the PNC asymmetry for the emitted gamma rays from the $1^{\mathrm{-}}$1 state in ${}_{}{}^{20}{}_{}{}^{}\mathrm{F}$ (${\mathit{E}}_{\mathit{x}}$=0.983 MeV) partially polarized in the reaction ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$(d→,${\mathrm{\alpha }}_3$${)}^{20}$F, which is predicted in the range (2.4–5.8 )×${10}^{\mathrm{-}5}$. The structure parts of the components of the PNC matrix elements have been carefully calculated for the analysis of the experimental result in terms of the weak coupling constants. A new class of diagrams contributing to the PNC matrix elements has been included for the first time.

The property of a rho meson in dense nuclear matter is studied using the QCD sum rule. The spectral function appearing on the hadronic side of the sum is evaluated in the vector dominance model that takes into account the interaction between the rho meson and the pion. Including pion modification by the delta-hole polarization in the nuclear medium, we find that as the nuclear density increases the rho meson peak in the spectral function shifts to smaller invariant masses and its width becomes smaller. We discuss the possibility of studying the rho meson property in dense matter via the dilepton invariant mass spectrum from heavy-ion collisions.

The use of integrals as approximations for discrete sums in microcanonical equilibrium calculations is valid in the thermodynamic limit. We derive a criterion for testing the validity of this approximation for the relatively small volumes encountered in heavy ion collision fireballs. Numerical examples with CERN and BNL parameters show that there is a real possibility that continuous calculations for the hadronic gas are not accurate. By means of an example, we illustrate the dangers of using canonical and grand canonical methods without first testing whether assumptions underlying their use are valid. Detailed investigations are now required to test the difference between continuous and discrete calculations.

In this work we present the probably first realistic shell model calculation of the low-lying spectra for the unstable even Sn isotopes with mass number A=102, 104, and 106. The effective shell model interaction was derived from a realistic free nucleon-nucleon interaction employing perturbative many-body techniques. For several of the isotopes studied, experimental data are rather scarce or nonexistent. The spectra we derive may therefore serve as a guide for identifying levels in the unstable Sn isotopes near the doubly magic ${}_{}{}^{100}{}_{}{}^{}\mathrm{Sn}$ core. We test our results by calculating E2 transitions for the above nuclei.

The (e,n) cross section and the (e+γ,n) yield have been measured for ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ in the electron energy range 12–60 MeV. The experimental results have been analyzed using distorted-wave Born approximation E1 and E2 virtual photon spectra for a finite nucleus in order to derive the E1 and E2 components of the (γ,n) cross section. The E1 component exhausts 40% of the E1 energy weighted sum rule while the isoscalar E2 exhausts 70–80 % of its sum.

We have performed neutron-capture gamma-ray studies on natural and enriched targets of ${}_{}{}^{134}{}_{}{}^{}\mathrm{Ba}$ in order to investigate the nuclear levels of ${}_{}{}^{135}{}_{}{}^{}\mathrm{Ba}$. The low-energy level spectra were compared with the calculations using the interacting-boson-fermion model (IBFM) and the cluster-vibration model. The level densities up to 5 MeV that are calculated within the IBFM are in accordance with the constant temperature Fermi gas model. From the spin distribution we have determined the corresponding spin cutoff parameter σ and compared it to the prediction from nuclear systematics.

We have performed a kinematically complete measurement of the Coulomb dissociation of 28 MeV/nucleon ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ into ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ and two neutrons by a Pb target. From the energies and angles of the emitted neutrons and of ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$, the excitation energy E of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ was determined on an event-by-event basis, and the Coulomb dissociation cross section as a function of excitation energy was constructed. The photonuclear cross section ${\mathrm{\sigma }}_{\mathit{E}1}$(E) and the dipole strength function dB(E1)/dE were determined from the Coulomb dissociation cross section. ${\mathrm{\sigma }}_{\mathit{E}1}$(E) has a peak at E=1.0 MeV and a width Γ=0.8 MeV. These parameters are consistent with the picture of a soft dipole mode. However, a significant post-breakup Coulomb acceleration of ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ suggests instead a direct breakup. The complete kinematical measurement also allowed neutron and ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ momentum distributions to be constructed in the rest frame of the ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$. The momentum distributions were fitted with Gaussian functions, yielding width parameters ${\mathrm{\sigma }}_9$=18±4 MeV/c and ${\mathrm{\sigma }}_{\mathit{n}}$=13±3 MeV/c. A more general feature of the breakup mechanism of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ could be deduced from these measurements. It was found that the ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ and neutron momentum distributions and the neutron-neutron relative momentum distribution could be reproduced if the ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ excitation energy was partitioned between the ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ and the neutrons by a three-body phase space distribution. This indicates there is no directional correlation between the halo neutrons, and shows that the halo neutrons do not exist as a dineutron bound to a ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ core.

Electron conversion coefficients for nine transitions in ${}_{}{}^{127}{}_{}{}^{}\mathrm{Ba}$ and ${}_{}{}^{130}{}_{}{}^{}\mathrm{La}$ have been measured to test the hypothesis that static octupole deformation occurs in the A=128 region. No evidence for alternating parity band or parity doublet structures is observed. Such structures are indicators of static octupole deformation in the A=145 and 225 regions.

The precession of the angular distribution of gamma rays deexciting the $2_1^{+}$ states of ${}_{}{}^{194,196,198}{}_{}{}^{}\mathrm{Pt}$ and ${}_{}{}^{148}{}_{}{}^{}\mathrm{Nd}$ nuclei have been measured by the transient field method. Average values of the transient field acting at Pt and Nd ions recoiling through gadolinium have been obtained from these data, and are shown to validate the Rutgers parametrization in the recoil velocity range 1.9≤(v/${\mathit{v}}_0$)<=4.6. The g($2_1^{+}$) factors of ${}_{}{}^{196,198}{}_{}{}^{}\mathrm{Pt}$ relative to g${(}^{194}$Pt)=0.302(16) have also been deduced: g${(}^{196}$Pt)=0.302(24) and g${(}^{198}$Pt)=0.350(30), in good agreement with other transient field measurements.

The structure of the low-lying levels of the ${}_{}{}^{91}{}_{}{}^{}\mathrm{Zr}$ nucleus is discussed in a framework of the cluster-phonon coupling model. In order to describe simultaneously positive- and negative-parity states, octupole as well as quadrupole vibrations of the ${}_{}{}^{88}{}_{}{}^{}\mathrm{Sr}$ core are allowed. The cluster states include two single protons coupled to a single neutron. The residual interaction among the cluster particles is assumed to be the modified surface δ interaction. Energy levels and electromagnetic properties are calculated and compared with the experimental data.

The relativistic nuclear mean-field model with derivative scalar coupling suggested by Zimanyi and Moszkowski is extended to finite temperature by means of the real-time Green’s function method with a pair cutoff approximation. The temperature and density dependences of the nucleon masses are given. The obtained equation of state is used to discuss the liquid-gas phase transition of nuclear matter. The critical temperature and density given by this model are ${\mathit{kT}}_{\mathit{C}}$=16.51 MeV and ${\mathrm{\rho }}_{\mathit{C}}$=0.0675 ${\mathrm{fm}}^{\mathrm{-}3}$, respectively.