We demonstrate that the creation of strange matter is conceivable in the midrapidity region of heavy ion collisions at Brookhaven RHIC and CERN LHC. A finite net-baryon density, abundant (anti)strangeness production, as well as strong net-baryon and net-strangeness fluctuations, provide suitable initial conditions for the formation of strangelets or metastable exotic multistrange (baryonic) objects. Even at very high initial entropy per baryon $S/A^{\mathrm{init}}\approx 500$ and low initial baryon numbers of $A_B^{\mathrm{init}}\approx 30$ a quark-gluon-plasma droplet can immediately charge up with strangeness and accumulate net-baryon number.

We have separated the longitudinal $\left(f_{00}\right)$, transverse $\left(f_{11}\right)$, and longitudinal-transverse interference $\left(f_{01}\right)$ structure functions in the ${}^2\mathrm{H}\left({e,e}^{\prime }p\right)n$ reaction at $|\overrightarrow{q}|\approx 400\mathrm{MeV}/c$ and $\omega \approx 110\mathrm{MeV}$. A nonrelativistic calculation which includes effects due to final state interactions, meson exchange currents, and isobar configurations agrees with the measured $f_{11}$ and $f_{01}$ but overpredicts $f_{00}$ by 25% ( $2\sigma$). The data are also compared to the results of previous structure function measurements.

Discrete $\gamma$ rays directly connecting states of a superdeformed (SD) band in ${}^{194}\mathrm{Hg}$ to the yrast states have been discovered. Thus, the excitation energies and spins of all members of the lowest SD band are established for the first time, together with their likely parity. The SD band decays from its ${10}^{+}$ and ${12}^{+}$ states, which lie 4204.8 and 4407.4 keV above the normal-deformed yrast states of the same spins.

Fusion excitation functions have been measured spanning the entire barrier region in 1 MeV energy steps for the two systems ${}^{40}\mathrm{Ca}{+}^{192}\mathrm{Os},{}^{194}\mathrm{Pt}$. Precautions were taken to ensure sufficiently small errors to allow for extraction of the distribution of fusion barriers from the second differential of the product of E and $\sigma$. These results are compared with coupled channel calculations which take into account the most important degrees of freedom of both projectile and target. The influence of the prolate deformation of ${}^{192}\mathrm{Os}$ and the oblate deformation of ${}^{192}\mathrm{Pt}$ as well as the octupole vibration of ${}^{40}\mathrm{Ca}$ is apparent.

Hard photons were measured in coincidence with projectilelike fragments in peripheral reactions of ${}^{36}\mathrm{Ar}+{}^{159}\mathrm{Tb}$ at $E/A=44\mathrm{}\mathrm{MeV}$. The probability for hard photon production was found to scale linearly with the transferred mass and to depend on the direction of the transfer, thus indicating the relative importance of one- and two-body dissipation in peripheral reactions.

The giant resonance region in ${}^{58}$Ni was studied with inelastic scattering of 240 MeV α particles at small angles including 0°. It is shown that the total isoscalar monopole strength in the region $E_x=12\mathrm{}$ to 25 MeV is $<50\mathrm{}\%$ of the $E0\mathrm{}$ energy-weighted sum rule, and that the centroid of the $E0\mathrm{}$ strength $E_{\mathrm{GMR}}>24.8\mathrm{}\mathrm{MeV}$ in contrast to the $E_{\mathrm{GMR}}\approx 17\mathrm{MeV}$ expected from systematics of other nuclei. If there is similar unobserved $E0\mathrm{}$ strength in other nuclei, $E_{\mathrm{GMR}}$ for those nuclei may be significantly different from those used to extract nuclear matter incompressibility.

The γ cascades feeding into low-K and high-K bands in ${}^{163}$Er are investigated analyzing variances and covariance of the spectrum fluctuations. From a large data set of 1$0^9$ triple coincidences, γ-γ coincidence spectra gated by resolved low-lying rotational bands are analyzed. Low-K bands are found to be fed by a much larger effective number of cascades than high-K bands. The covariance between pairs of gated spectra shows that the cascades feeding low-K bands are different from those feeding the high-K bands. The persistence of the K-selection rules for the excited rotational bands within the angular momentum region $30ħ\le I\le 40ħ$ is suggested as explanation.

Experimental evidence for identification of the 5241-keV $0^{+}$ state in ${}^{208}$Pb as the lowest-spin member of the $3^{-}\otimes 3^{-}$ quartet is reported. This state, observed previously in neutron transfer reactions and inelastic proton scattering, has been populated with the inelastic neutron scattering reaction. Its decay to the $3^{-}$ octupole phonon in ${}^{208}$Pb is confirmed by $\gamma -\gamma$ coincidence measurements, and the spin-0 assignment is substantiated by the population cross section. The cascade of two E3 transitions thus established is an expected signature of a two-phonon octupole excitation.

To analyze ultrarelativistic nuclear interactions, usually either dynamical models like the string model are employed, or a thermal treatment based on hadrons or quarks is applied. String models encounter problems due to high string densities; thermal approaches are too simplistic, considering only average distributions and ignoring fluctuations. We propose a completely new approach, providing a link between the two treatments, and avoiding their main shortcomings: based on the string model, connected regions of high energy density are identified for single events, such regions being referred to as quark matter droplets. Each individual droplet hadronizes instantaneously according to the available $n$-body phase space, making use of special Monte Carlo techniques.

We present the first measurement to isolate the variation of nuclear effects in the x-ray transitions of few-electron heavy ions. Using a novel technique to produce and trap radioactive ions we measured the energy difference between ${2s}_{1/2}-{2p}_{3/2}$ transitions in Li-, Be-, B-, and C-like ${}^{233}$U and ${}^{238}$U. We show that because of the simplified atomic structure of few-electron ions the data are readily interpreted in terms of the variation in the mean nuclear radius. A value $\delta 〈r^2{〉}^{233,238}=-0.457\mathrm{}\pm 0.043$ f${\mathrm{m}}^2$ is found, which lies between earlier measurements based on different techniques.

The heavy nucleus ${}_{108}^{272}\mathrm{Hs}$ $(Z=108\mathrm{})$ and its evaporation daughters were produced using the reaction ${}^{232}\mathrm{Th}{(}^{40}\mathrm{Ar},\gamma \mathrm{xn})$ with beam energies 10.5 and 15.0 MeV/A. The giant dipole resonance γ radiation from the hot composite system prior to fission has been isolated using a differential method. The prefission component shows a strong dipole angular distribution relative to the spin direction.

A charge-symmetry-breaking nucleon-nucleon force due to the up-down quark mass difference is evaluated in the quark cluster model. It is applied to the shell-model calculation for the isovector mass shifts of isospin multiplets in $1s0d$-shell nuclei. We find that the contribution of the quark mass difference effect explains the systematic behavior of experiment. This contribution is large and may explain the Okamoto-Nolen-Schiffer anomaly, alternatively to the meson-mixing contribution, which is recently predicted to be reduced by the large off-shell correction.

The reaction ${}^3\mathrm{He}\left({e,e}^{\prime }d\right)p$ was measured at four-momentum transfer $q=420\mathrm{}$ MeV, for proton recoil momentum $P_r=22\mathrm{}$, 54, and 62 MeV/c, in parallel deuteron kinematics. Longitudinal $\left(L\right)$ and transverse $\left(T\right)$ response functions were obtained by means of Rosenbluth separations. The separated response functions are, respectively, found to be dominated by the contributions of isoscalar and isovector two-body currents. The $L/T$ ratios are about 3.5. This is an order of magnitude lower than that for elastic scattering on a free deuteron, or what would be expected for a purely isoscalar transition, but approximately agrees with what is theoretically expected for isoscalar plus isovector contributions.

Excited states of neutron deficient nuclei close to ${}^{100}$Sn were investigated in an in-beam spectroscopic experiment using the NORDBALL detector array. Excited states in ${}^{99}$Cd were identified for the first time. The measured half-life of an isomeric state in ${}^{99}$Cd indicates that the stability with respect to quadrupole shape changes is as large in ${}^{100}$Sn as for other heavy doubly magic nuclei.

The new proton radioactivity ${}^{185m}\mathrm{Bi}$ has been observed, produced via the ${}^{95}\mathrm{Mo}{(}^{92}\mathrm{Mo},pn{)}^{185}\mathrm{Bi}$ reaction. Its decay proceeds from the low-lying ${\frac{1}{2}}^{+}$ intruder state in ${}^{185}\mathrm{Bi}$ to the ${}^{184}\mathrm{Pb}$ ground state with the emission of a proton of energy $1.585\pm 0.009\mathrm{MeV}$ and a half-life of $44\pm 16\mu \mathrm{s}$. This marks the first observation of proton radioactivity above the $Z=82\mathrm{}$ closed shell, and it has been used to obtain the admixture of a $0^{+}$ intruder state in ${}^{184}\mathrm{Pb}$ into the ${}^{184}\mathrm{Pb}$ ground-state wave function.

Rho meson propagation in hot hadronic matter is studied in a model with coupling to $\pi \pi$ states. Medium modifications are induced by a change of the pion dispersion relation through collisions with nucleons and $\Delta$'s in the fireball. Maintaining gauge invariance dilepton production is calculated and compared to the recent data of the CERES Collaboration in central $\mathrm{S}+\mathrm{Au}$ collisions at 200 GeV/u. The observed enhancement of the rate below the rho meson mass can be largely accounted for.

The charge ( $Z$) distributions from intermediate energy heavy-ion reactions depend upon the multiplicity $n$ of intermediate mass fragments through a factor of the form $e^{-cnZ}$. Experimentally $c$ starts from zero at low values of the transverse energy $E_t$ and reaches a saturation value at high $E_t$. In a liquid-gas phase diagram $c=0\mathrm{}$ for the saturated vapor, while $c>\mathrm{}0\mathrm{}$ for the unsaturated vapor. It is suggested that in the $c\approx 0$ regime the source evaporates down to a sizable remnant, while for $c>\mathrm{}0\mathrm{}$ the source vaporizes completely. Percolation of finite systems and nuclear evaporation portray a behavior similar to that observed experimentally.

The $\gamma$ decay of excited states in the $N=Z$ odd-odd nucleus ${}^{74}\mathrm{Rb}$ has been observed for the first time. The reaction ${}^{40}\mathrm{Ca}{(}^{40}\mathrm{Ca},\alpha \mathrm{pn}{)}^{74}\mathrm{Rb}$ at 128 MeV beam energy was used. The ground state rotational band can be interpreted as being formed from the $T=1\mathrm{}$ isobaric analog states of ${}^{74}\mathrm{Kr}$ with pairing correlations based on $T=1\mathrm{}$, $M_T=0\mathrm{}$ neutron-proton pairs. At higher rotational frequency, a $T=0\mathrm{}$ rotational band becomes energetically favored over the $T=1\mathrm{}$ ground state band, in agreement with the predictions of cranked shell model calculations which explicitly include $T=0\mathrm{}$ and $T=1\mathrm{}$ pairs.

We calculate exotic cluster states for heavy nuclei in the actinide region, using potentials based on an $\alpha -\mathrm{c}\mathrm{o}\mathrm{r}\mathrm{e}$ potential which itself reproduces the properties of the low-lying positive parity states of ${}^{212}$Po. We find that by suitably scaling the parameters of the $\alpha -\mathrm{c}\mathrm{o}\mathrm{r}\mathrm{e}$ potential so as to reproduce the exotic decay lifetimes, we obtain a good description of the spectra and electromagnetic decay properties of the ground state rotational bands of the actinide nuclei.

We calculate the nuclear suppression for $J/\psi$ and ${\psi }^{\prime }$ production within a coupled channel approach in the subspace of the $J/\psi$ and ${\psi }^{\prime }$ states. We are able to explain why (i) $J/\psi$ and ${\psi }^{\prime }$ show the same suppression from 200 to 800 GeV in proton-nucleus collisions and why (ii) ${\psi }^{\prime }$ is absorbed more strongly than $J/\psi$ in nucleus-nucleus collisions at 200 GeV. Our numerical result, which includes only interactions with nucleons, accounts for half of the observed suppression in sulfur uranium collisions.