We discuss the effects of double octupole and quadrupole phonon excitations in ${}^{144}\mathrm{Sm}$ on fusion reactions between ${}^{16}\mathrm{O}$ and ${}^{144}\mathrm{Sm}$ at sub-barrier energies. The effects of anharmonicities of the vibrational states are taken into account by using the $\mathrm{sdf}$-interacting boson model. We compare the results with those in the harmonic limit to show that anharmonicities play an essential role in reproducing the experimental fusion barrier distribution. From the analysis of the high quality fusion data available for this system, we deduce negative static quadrupole moments for both the first $2^{+}$ and $3^{-}$ states in ${}^{144}\mathrm{Sm}$. This is the first time that the sign of static quadrupole moments of phonon states in a spherical nucleus is determined from the data of sub-barrier fusion reactions.

We show that under certain conditions a simple relationship exists between the elastic scattering of a composite halo nucleus and of its core from a stable target. The coupling of the elastic and projectile excitation channels is crucial to the analysis, which is particularly useful when the ratio of the halo to the core mass is small. In the case of ${}^{11}$Be elastic scattering the cross section relationship is quite well satisfied. For both ${}^{11}$Be and ${}^{19}$C our analysis reveals a significant sensitivity of elastic scattering data to the halo size and structure.

We argue that a decrease of the chiral scalar meson mass is responsible for recreation of ${\Psi }^{\prime }$ from $J/\Psi$ in ultrarelativistic nucleus-nucleus collisions. This causes the charmonium yields to freeze out at temperatures close to the chiral symmetry restoration temperature $T_c$. As a result the ratio ${\Psi }^{\prime }/\Psi$ may serve as a thermometer for $T_c$ itself. Results in a detailed reaction model support the conjecture. They show good agreement with recent data of NA38 and NA50 for $J/\Psi$ and ${\Psi }^{\prime }$ production in S on U and Pb on Pb collisions.

The quasifree $p+n\to d+\eta$ reaction cross section has been measured in the near-threshold region using deuterium from an internal cluster-jet target and 1350 MeV protons in the CELSIUS storage ring of the The Svedberg Laboratory, Uppsala. The energy dependence of the cross section is extracted by exploiting the Fermi momentum of the target neutron and reconstructing the kinematics on an event-by-event basis. The data cover center of mass excess energies from 16 to 113 MeV.

We formulate a method to solve the coordinate space Faddeev equations for positive energies. The method employs hyperspherical coordinates and analytical expressions for the effective potentials at large distances. Realistic computations of the parameters of the resonances and the strength functions are carried out for the Borromean halo nucleus ${}^6\mathrm{He}$ $(n+n+\alpha )$ for $J^{\pi }{=0\mathrm{}}^{\pm }{,1\mathrm{}}^{\pm }{,2\mathrm{}}^{\pm }$.

Excited states in ${}^{98}\mathrm{Cd}$, two proton holes from ${}^{100}\mathrm{Sn}$, were identified and studied for the first time, using in-beam spectroscopy with highly selective ancillary detectors. The structure of the $(\pi g_{9/2}{)}^{-2\mathrm{}}$ two-proton-hole spectrum below a $T_{1/2}=0.48\mathrm{}\left(16\right)\mu \mathrm{s}$ isomer is deduced and compared to shell-model predictions. A tentative $I^{\pi }=\left(8^{+}\right)$ assignment, as suggested by systematics, yields a strongly reduced $B({E2,8\mathrm{}}^{+}\to 6^{+})=0.44\mathrm{}{(}_{-10\mathrm{}}^{+20\mathrm{}})\mathrm{W}.\mathrm{u}.\mathrm{}$, corresponding to an effective proton charge of $e_{\pi }=0.85\mathrm{}{(}_{-10\mathrm{}}^{+20\mathrm{}})e$, which is at variance with existing theoretical predictions.

Resonance ionization spectroscopy (RIS) was performed on desorbed Au, and the complete hyperfine spectrum of both isomeric and ground states of the short lived ${}_{}{}^{184}{}_{}{}^{}A\mathrm{u}$ nucleus has been recorded from the ${5d}^{10}6s{}^2{S}_{1/2}\to {5d}^{10}6p{}^2{P}_{3/2}$ optical transition. The nuclear moments of both states and the mean square charge radius changes were measured. The magnetic moments were determined to be ${\mu }_{I=5\mathrm{}}^{184g}=+2.07\mathrm{}\left(2\right){\mu }_N$ and ${\mu }_{I=2\mathrm{}}^{184m}=+1.44\mathrm{}\left(2\right){\mu }_N$ and the spectroscopic quadrupole moments to be $Q_s^{184g}=+4.65\mathrm{}\left(26\right)b$ and $Q_s^{184m}=+1.90\mathrm{}\left(16\right)\mathrm{b}$. A difference in the mean square charge radius $\delta 〈r_c^2{〉}^{184g,184m}=-0.036\mathrm{}\left(3\right){\mathrm{fm}}^2$ was found.

Ground state energies and decay widths of particle-unstable nuclei are calculated within the Hartree-Fock approximation by performing a complex scaling of the many-body Hamiltonian. Because of this transformation, the wave functions of the resonant states are square integrable. The method is implemented with Skyrme effective interactions. Several Skyrme parametrizations are tested on four unstable nuclei: ${}^{10}$He, ${}^{12}$O, ${}^{26}$O, and ${}^{28}$O.

A Comment on the Letter by W. D. Heiss, R. G. Nazmitdinov, and S. Radu, Phys. Rev. Lett. 72, 2351 (1994).

The recently discovered regular bands of enhanced $M1\mathrm{}$ $\gamma$-ray transitions in nearly spherical Pb nuclei have been explained in terms of magnetic rotation. However, the special angular momentum coupling of the nucleons that form magnetic-rotational states has never been tested experimentally. In this paper, we report on the measurement of the $g$ factor of the 2583-keV head of such a band in ${}^{193}\mathrm{Pb}$. The result, $g=0.68\mathrm{}\left(3\right)$, is the first direct proof of the almost perpendicular coupling of the proton-particle and neutron-hole angular momentum vectors. This coupling results in a large component of the magnetic moment perpendicular to the total nuclear angular momentum, which is required for the occurrence of magnetic rotation.

We find a $\Delta I=4\mathrm{}$ bifurcation phenomenon in many ground state rotational bands by performing a staggering parameter analysis, which has been employed often for superdeformed bands. We find also that a small modification of the intrinsic state of the interacting boson model wave function in the sd-boson space, which has been used extensively for ground bands, is able to produce the regular $\Delta I=4\mathrm{}$ bifurcation pattern. Adding a g boson, we are able to generate even an irregular pattern in the $\Delta I=4\mathrm{}$ bifurcation phenomenon, which seems to be observed in some ground bands.

It is demonstrated by a fluctuation analysis based on the assumption of a Wigner distribution for the nuclear level spacings and of a Porter-Thomas distribution for the transition strengths that significant parts of the dipole strength excited in photon scattering experiments in heavy, deformed odd-mass nuclei are hidden in the background of the experimental spectra. With this additional strength, the heretofore claimed severe reduction of the $B\left(M1\mathrm{}\right)$ scissors mode strength in odd-mass nuclei compared to the one in neighboring even-even nuclei disappears.

The measured fusion barrier distributions for ${}_{}{}^{40}{}_{}{}^{}C\mathrm{a}+{}_{}{}^{192}{}_{}{}^{}O\mathrm{s}$, ${}^{194}$Pt show significant features due to projectile excitation, while none are seen for ${}_{}{}^{16}{}_{}{}^{}O+{}_{}{}^{144}{}_{}{}^{}S\mathrm{m}$. This conflict is reconciled using realistic coupled-channel calculations, which show that the higher excitation energy of the $3^{-}$ state in ${}^{16}$O produces an adiabatic potential renormalization, without affecting the structure in the barrier distribution. This result indicates that adiabatic effects restrict, in a natural way, the states which influence the shape of a fusion barrier distribution.

We give a semiclassical interpretation of the mass asymmetry in the fission of heavy nuclei. Using only a few classical periodic orbits and a cavity model for the nuclear mean field, we reproduce the onset of left-right asymmetric shapes at the fission isomer minimum and the correct topology of the deformation energy surface of ${}^{240}\mathrm{Pu}$ in the region of the outer fission barrier.

The contributions of direct knockout processes, in addition to the diffractive production and one-pion-exchange processes associated with the $\phi \rho \pi$ and $\phi \gamma \pi$ couplings, to the polarization observables of the $\phi$ photoproduction from proton are calculated. We make use of the Pomeron-photon analogy and of a relativistic harmonic oscillator quark model. We find that some of the double polarization observables are very sensitive to a possible $s\overline{s}$ admixture in the proton. It arises from the difference in the spin structures of the three different amplitudes. This suggests that such measurements could be very useful to probe the strangeness content in the proton.

Spreading properties of the Gamow-Teller resonance in ${}^{90}$Nb and ${}^{208}$Bi are studied within an approach including the $2p2h$ configuration mixing and the ground-state correlations beyond the random-phase approximation. The M3Y interaction and single-particle wave functions within the standard harmonic oscillator potential are used in numerical calculations. The single-particle energies around the Fermi surface are replaced with the empirical values or those given by a Woods-Saxon potential. Results obtained provide a reasonable account for recent experimental findings. The extension of the present approach to hot nuclei is also provided.

Inelastic scattering data of ${}^{11}\mathrm{Li}$ from hydrogen at $68A\mathrm{MeV}$ have been interpreted as the excitation of a state in ${}^{11}\mathrm{Li}$ at $E_x=1.3\mathrm{}\mathrm{MeV}$, with an assignment of $J^{\pi }={\frac{3}{2}}^{+}$. Analysis of those data in a distorted wave approximation assuming transitions to three candidates obtained in a $(0+2)ħ\omega$ shell model suggests an alternative nuclear shakeoff mechanism.

We present measured dielectron production cross sections for $\mathrm{Ca}+\mathrm{Ca}$, $\mathrm{C}+\mathrm{C}$, $\mathrm{He}+\mathrm{Ca}$, and $d+\mathrm{Ca}$ reactions at $1.0A\mathrm{GeV}$. Statistical uncertainties and systematic effects are smaller than in previous dilepton spectrometer (DLS) nucleus-nucleus data. For pair mass $M\le 0.35\mathrm{GeV}{/c}^2$ we obtain (1) the $\mathrm{Ca}+\mathrm{Ca}$ cross section is larger than the previous DLS measurement and current model results, (2) the mass spectra suggest large contributions from ${\pi }^0$ and $\eta$ Dalitz decays, and (3) $d\sigma /\mathrm{dM}\propto A_P{A}_T$. For $M>\mathrm{}0.5\mathrm{GeV}{/c}^2$ the $\mathrm{Ca}+\mathrm{Ca}$ to $\mathrm{C}+\mathrm{C}$ cross section ratio is significantly larger than the ratio of $A_P{A}_T$ values.

A high-spin rotational cascade of six $\gamma$ rays has been observed in ${}^{62}\mathrm{Zn}$. The quadrupole moment of ${2.7}_{-0.5\mathrm{}}^{+0.7\mathrm{}}e\mathrm{b}$ measured for this band corresponds to a deformation ${\beta }_2{=0.45\mathrm{}}_{-0.07\mathrm{}}^{+0.10\mathrm{}}$. The properties of this band are in excellent agreement with calculations that predict high-spin superdeformed bands in ${}^{62}\mathrm{Zn}$ with deformations ${\beta }_2=0.41\mathrm{}–0.49$. These results establish a new region of superdeformation for nuclei with neutron and proton numbers $N,Z\approx 30–32$.

Experimental measurements of ultraviolet and visible emission from two samples containing ${}^{233}$U suggest the deexcitation of a reported 3.5 eV isomeric level in ${}^{229}$Th. The unique phenomenon of ultraviolet $\gamma$-ray emission was observed from this level. Results are consistent with theoretical arguments suggesting that the nucleus can also deexcite via an inelastic electronic bridge mechanism. These observations indicate the exotic phenomenon of nuclear emission in the optical band, and open new areas of physics related to nuclear-atomic interaction.