The hadronization cross section in a quark plasma at finite temperature and density is calculated in the framework of the Nambu–Jona-Lasinio model with explicit chiral symmetry breaking. In contrast to the familiar temperature effect, the quark plasma at high density begins to hadronize suddenly. It leads to a sudden and strong increase of final state pions in relativistic heavy ion collisions which may be considered as a clear signature of chiral symmetry restoration.

For the first time, six-quasiparticle isomers have been observed in the meta-stable nucleus ${}_{\hspace{0.5em}73}^{180}{\mathrm{Ta}}_{107}.$ Two new high-spin isomers were populated following deep-inelastic reactions with a pulsed ${}_{\hspace{0.5em}92}^{238}\mathrm{U}$ beam incident on a thick ${}_{\hspace{0.5em}72}^{180}\mathrm{Hf}$ target. Out-of-beam $\gamma$-ray events were collected using the Gammasphere germanium detector array. In addition to the known four-quasiparticle isomers, yrast $K^{\pi }{=(22\mathrm{}}^{-})$ and $K>~23$ six-quasiparticle isomers have been observed with microsecond half-lives. These are the highest-spin isomers observed using the technique of deep-inelastic excitation. The assignments are compared to predictions made by BCS and Lipkin-Nogami multiquasiparticle calculations.

The relative role of the momentum-dependent interactions and larger nucleon-nucleon cross section is discussed in multifragmentation using quantum molecular dynamical model. We find that the sensitivity of the larger cross section towards multifragmentation reduces in the presence of momentum-dependent interactions which makes it difficult to extract the magnitude of nucleon-nucleon cross section from multifragmentation. However, a large effect of different cross sections can be seen if a simple static equation of state is used.

We have created quasiprojectiles of varying isospin via peripheral reactions of ${}^{28}{\mathrm{S}\mathrm{i}+}^{112}\mathrm{Sn}$ and ${}^{124}\mathrm{Sn}$ at 30 and 50 MeV/nucleon. The quasiprojectiles have been reconstructed from completely isotopically identified fragments. The difference in $N/Z$ of the reconstructed quasiprojectiles allows the investigation of the disassembly as a function of the isospin of the fragmenting system. The isobaric yield ratio ${}^3{\mathrm{H}/}^3\mathrm{He}$ depends strongly on $N/Z$ ratio of quasiprojectiles. The dependences of mean fragment multiplicity and mean $N/Z$ ratio of the fragments on $N/Z$ ratio of the quasiprojectile are different for light charged particles and intermediate mass fragments. Observation of a different $N/Z$ ratio of light charged particles and intermediate mass fragments is consistent with an inhomogeneous distribution of isospin in the fragmenting system.

In a recent paper, Das et al. [Phys. Rev. C 60, 044617 (1999)] compare the merits of three entrance channel potentials, in a full finite-range distorted-wave Born approximation analysis of the ${}^{27}\mathrm{Al}(\alpha {,t)}^{28}\mathrm{Si}$ transfer reaction at 64.5 MeV laboratory energy. We show that two of these potentials are clearly not appropriate for describing the data in the entrance channel at this energy, and that the conclusions concerning the adequacy of deep versus molecular-type potentials for describing the α-nucleus interaction are therefore not warranted.

The point stressed by Michel and Reidemeister is that the Michel potential in our work is not final and an adjustment of the parameter $\alpha$ gives an elastic distribution and a potential similar to that obtained for the molecular one. This is usual in the absence of the elastic data at large angles as commented on by Tariq et al. [Phys. Rev. C 59, 2558 (1999)]. However, the inadequacy of the Michel potential with the parameter $\alpha =7.4\mathrm{}$ in the description of the $(\alpha ,t)$ reaction data leads to a finding of a better value for the parameter by Michel and Reidemeister. This justifies the use of the molecular and Michel potentials in the analysis of the reaction and conforms to the suggestion by Satchler (Ref. [40] in Tariq et al.) that the performance of a potential in nonelastic processes is a stronger criterion in its selection.

In the bombardment of a ${}^{244}\mathrm{Pu}$ target with ${}^{48}\mathrm{Ca}$ ions, we observed two identical decay sequences of genetically linked events, each consisting of an implanted heavy atom, two subsequent α decays, and terminated by a spontaneous fission. The measured α energies and corresponding half-lives of the sequential chain members were $E_{\alpha }=9.84\mathrm{}\pm 0.05\hspace{0.5em}\mathrm{MeV}$ ${(T}_{1/2}{=1.9\mathrm{}}_{-0.8}^{+3.3\mathrm{}}\hspace{0.5em}\mathrm{s})$ and $9.17\pm 0.05\hspace{0.5em}\mathrm{MeV}$ ${(T}_{1/2}{=9.8\mathrm{}}_{-3.8}^{+18\mathrm{}}\hspace{0.5em}\mathrm{s});$ for the spontaneous fission ${(T}_{1/2}{=7.5\mathrm{}}_{-2.9}^{+14\mathrm{}}\hspace{0.5em}\mathrm{s}),$ the total energies deposited in the detector array were $213\pm 2$ and $221\pm 2\hspace{0.5em}\mathrm{MeV}.$ The decay properties of the synthesized nuclei are consistent with the consecutive α decays originating from the parent even-even nucleus ${}^{288}114,$ produced in the $4n$-evaporation channel with a cross section of about 1 pb. ${}^{288}114$ and ${}^{284}112$ are the heaviest known α-decaying even-even nuclides, following the production of ${}^{260}\mathrm{Sg}$ and ${}^{266}\mathrm{Sg}$ $\mathrm{}(Z=106\mathrm{})\mathrm{}$ and the observation of α decay of ${}^{264}\mathrm{Hs}$ $\mathrm{}(Z=108\mathrm{}).$ The observed radioactive properties of ${}^{288}114$ and the daughter nuclides match the decay scenario predicted by the macroscopic-microscopic theory.

By considering a class of diagrams which has been overlooked also in the most recent literature on three-body forces, we extract a new contribution to the three-nucleon interaction which specifically acts on the triplet odd states of the two-nucleon subsystem. In the static approximation, this $3N$-force contribution is fixed by the underlying $2N$ interaction, so in principle there are no free parameters to adjust. The $2N$ amplitude however enters in the $3NF$ diagram in a form which cannot be directly accessed or constrained by $\mathrm{NN}$ phase-shift analysis. We conclude that this new $3N$-force contribution provides a mechanism which implies that the presence of the third nucleon modifies the p-wave (and possibly the f-wave) components of the $2N$ subsystem in the triplet-isotriplet channels.

High-spin states of ${}^{98,99,100}\mathrm{Ru}$ have been populated using the reaction ${}^{70}\mathrm{Zn}{(}^{36}\mathrm{S},\alpha \mathrm{x}n)$ at 130 MeV. The $\gamma$ rays have been detected with the EUROGAM-2 array. New high-spin bands have been established in these nuclei and interpreted as terminating configurations using the Nilsson-Strutinsky cranking formalism. These bands were observed up to the predicted terminating states which are built from $g_{9/2}$ protons and $N=3\mathrm{}$ proton holes combined with $d_{5/2},$ $g_{7/2},$ and $h_{11/2}$ neutrons relative to a ${}^{90}\mathrm{Zr}$ core. Core-excited configurations with $N=3\mathrm{}$ proton holes have been found to play an important role. The observed high-spin states assigned as terminating show systematic behavior and provide new information on the energy spacing between the ${2d}_{5/2}$ and ${1g}_{7/2}$ neutron subshells.

We investigate the diagrammatic content of the Hellmann-Feynman theorem applied to nuclear matter within the framework of the Brueckner-Bethe-Goldstone theory for various self-consistent choices of the auxiliary potential. We identify cases in which one implicitly generates diagrams which are at odds with the Bethe-Brandow-Petscheck theorem. We point out that similar problems also arise with the Brueckner-Landau definition of the mean field. Finally, we characterize the structure exhibited by the potential energy diagrams when expressed in terms of G matrices and we provide the corresponding diagram rules.

Low spin states in the odd-odd nucleus ${}^{50}\mathrm{Mn}$ were populated in the ${}^{50}\mathrm{Cr}(p,n\gamma {)}^{50}\mathrm{Mn}$ fusion evaporation reaction at 15 MeV beam energy at the FN-Tandem accelerator in Cologne. γ-angular correlations, $\gamma \gamma$ coincidences, and Compton asymmetries were measured. 21 states of ${}^{50}\mathrm{Mn}$ were observed, 16 for the first time. Six new spin assignments and two parity assignments were made. Eight multipole-mixing ratios and nine new γ-decay branching ratios were determined for the first time. A full pf-shell model calculation for the low-lying states in ${}^{50}\mathrm{Mn}$ is compared to the data.

Thermodynamical properties of nuclear matter undergoing multifragmentation are studied within a simplified version of the statistical model. An exact analytical solution has been found for the grand canonical ensemble. Excluded volume effects are taken into account in the thermodynamically self-consistent way. In the thermodynamic limit the model exhibits a first order liquid-gas phase transition with specific mixed phase properties. An extension of the model including the Fisher’s term is also studied. The possibility of the second order phase transition at or above the critical point is demonstrated. The fragment mass distributions in different regions of the phase diagram are discussed.

Measurements of the elastic and inelastic scattering cross sections for deuterons on ${}^{27}\mathrm{Al}$ and ${}^{56}\mathrm{Fe}$ have been completed at 5 and 7 MeV. Additional measurements of the $\mathrm{}(d,p),$ $(d,\alpha ),$ and $\mathrm{}(d,n)\mathrm{}$ spectra on these targets at the same energies have been made. An optical model analysis has yielded optical parameters for these nuclei. These are not consistent with some global models based on fits to data above 9 MeV. A Hauser-Feshbach calculation for each target at the appropriate bombarding energy has been compared with the various particle spectra. Evidence for both direct and compound nuclear reaction contributions is found. A small contribution is found from direct three-body breakup $(d+\overrightarrow{T}n+p+T),$ but $\mathrm{}(d,n)\mathrm{}$ and $\mathrm{}(d,p)\mathrm{}$ direct reactions to bound states are more common. Approximately 75% of the absorption cross section corresponds to compound nuclear processes.

By using a low-sensitivity glass track detector in planar geometry we measured the decay rate of ${}^{232}\mathrm{U}$ by spontaneous fission to be ${\lambda }_{\mathrm{SF}}=(8.6\mathrm{}\pm 1.8)\times {10}^{-24}{\mathrm{s}}^{\mathrm{-}1},$ corresponding to a half-life $T_{1/2}=(8.1\mathrm{}\pm 1.7)\times {10}^{22}\mathrm{s}.$ The inconsistency and consistency of this result with previous work is discussed, and spontaneous fission half-lives are compared with cluster decay ones for the various uranium isotopes measured up to now.

A microscopic approach to breakup reactions into the low-energy continuum of Borromean two-neutron halo nuclei is developed, taking quantum-mechanically into account both Coulomb and nuclear dissociation, simultaneously. The crucial role of both elastic and inelastic fragmentation is demonstrated for ${}^6\mathrm{He}$ breakup on C and Pb targets at intermediate energies, for kinematically complete experiments. Recent GSI experimental data are for the first time analyzed quantitatively and reveal a rich and complex interplay of reaction mechanisms and low-lying halo excitations.

Superdeformed bands in the mass $A=190\mathrm{}$ region decay suddenly, over a few states, at relatively low spin and high excitation energy. The decay path is very fragmented and only in a few cases have one-step or two-step decays been seen. Thus, only three superdeformed bands have so far been linked to the normal states they decay to. Most of the $\gamma$ rays from the decay form an unresolved quasicontinuum spectrum. This paper describes the extraction of the total quasicontinuum decay spectrum that connects the superdeformed and normal yrast states. It also demonstrates that the excitation energy and spins of superdeformed bands can be determined by analyzing this total decay spectrum. The analysis method is first tested in ${}^{194}\mathrm{Hg},$ which is one of the few cases where the excitation energy and spin of the yrast superdeformed band are known, and is then applied to the yrast superdeformed band in ${}^{192}\mathrm{Hg},$ where no one-step decays have been seen thus far. fe ndash

The angular and energy distributions of neutrons produced by 400 MeV/nucleon Ar, Fe, and Xe, and 800 MeV/nucleon Si ions stopping in thick C, Al, Cu, and Pb targets were measured using the Heavy-Ion Medical Accelerator in Chiba of the National Institute of Radiological Science (NIRS), Japan. The neutron spectra in the forward direction have broad peaks which are located at about 60 to 70 % of the incident particle energy per nucleon due to breakup and knock-on processes, and spread up to almost twice as much as the projectile energy per nucleon. The resultant spectra were integrated over energy to produce neutron angular distributions. The total neutron yields for each system were obtained by integrating over the angular distributions, and we could estimate the total yields using a simple formula. The experimental results are compared with the calculations using the heavy-ion collision Monte Carlo code, and the calculated results rather agree with the measured results. The phenomenological hybrid analysis, based on the moving source model and the Gaussian fitting of the breakup and knock-on processes, could also well represent the measured thick target neutron spectra.

Alpha decay from ${}^{225}\mathrm{Ra}$ has been observed for the first time. $5006\pm 5\mathrm{keV}$ and $4976\pm 5\mathrm{keV}$ alphas with intensities $2.0\pm 0.5\times {10}^{-5}$ and $6\pm 3\times {10}^{-6}$ and alpha decay hindrance factors $40\pm 10$ and $70\pm 35,$ respectively, are reported. The corresponding levels in ${}^{221}\mathrm{Rn}$ are the ground state $\left({\frac{7}{2}}^{+}\right)$ and $30\pm 10\mathrm{keV}$ excited state (tentatively ${\frac{3}{2}}^{+})$ with the octupole deformed configurations $\frac{3}{2}(-0.1\hspace{0.5em}0.6)$ mixed with $\frac{1}{2}\left(-0.1\hspace{0.5em}0.5\hspace{0.5em}-2\right).$