We propose a unified space-time picture of baryon stopping and quark-gluon plasma creation in ultrarelativistic heavy-ion collisions. It is assumed that the highly Lorentz contracted nuclei are decelerated by the coherent color field which is formed between them after they pass through each other. This process continues until the field is neutralized by the Schwinger mechanism. Conservation of energy and momentum allow us to calculate the energy losses of the nuclear slabs and the initial energy density of the quark-gluon plasma.

Low-lying resonance states in ${}^7\mathrm{He}{(}^6\mathrm{He}+n)$, formed after fragmentation reactions of a 227 MeV/nucleon ${}^8\mathrm{He}$ beam on a carbon target, have been studied. Coincidences between ${}^6\mathrm{He}$ nuclei and neutrons, corresponding to the one-neutron knockout channel in ${}^8\mathrm{He}$, were selected. The relative energy spectrum in the ${}^6\mathrm{He}+n$ system shows a structure, which is interpreted as the ${}^7\mathrm{He}$ ( $I^{\pi }{=3/2\mathrm{}}^{-}$) ground state, unbound with 0.43(2) MeV relative to the ${}^6\mathrm{He}+n$ system and a width of $\Gamma =0.15\mathrm{}\left(8\right)\mathrm{MeV}$ overlapping with an excited ( $I^{\pi }{=1/2\mathrm{}}^{-}$) state observed at 1.0(1) MeV with a width of $\Gamma =0.75\mathrm{}\left(8\right)\mathrm{MeV}$.

The quadrupole moment of the ${11}^{-}$ isomer in ${}^{196}\mathrm{Pb}$ has been measured by the level mixing spectroscopy method. This state has a $\pi \left({3s}_{1/2}^{-2\mathrm{}}{1h}_{9/2}1i_{13/2}\right){11}^{-}$ configuration which is involved in most of the shears band heads in the Pb region. The first directly measured value of $Q_s\left({11}^{-}\right)=(-)3.41\left(66\right)\mathrm{b}$, coupled to the previously known quadrupole moment of the $\nu \left({1i}_{13/2}^{-2\mathrm{}}\right){12}^{+}$ isomer allows us to estimate the quadrupole moment of the ${16}^{-}$ shears band head as $Q_s\left({16}^{-}\right)=-0.32\mathrm{}\left(10\right)\mathrm{b}$. The experimental values are compared to tilted axis cranking calculations, giving insight into the validity of the additivity approach to couple quadrupole moments and on the amount of deformation in the shears bands.

The spin-momentum correlation parameter $A_{\mathrm{ed}}^V$ was measured for the ${}^2\overrightarrow{\mathrm{H}}\left(\overrightarrow{e}{,e}^{\prime }p\right)n$ reaction for missing momenta up to $350\mathrm{MeV}/c$ at $Q^2=0.21\mathrm{}(\mathrm{GeV}/c{)}^2$ for quasielastic scattering of polarized electrons from vector-polarized deuterium. The data give detailed information about the deuteron spin structure and are in good agreement with the results of microscopic calculations based on realistic nucleon-nucleon potentials and including various spin-dependent reaction mechanism effects. The experiment reveals in a most direct manner the effects of the $D$ state in the deuteron ground-state wave function and shows the importance of isobar configurations for this reaction.

Rapidity distributions of protons from central ${}^{197}\mathrm{Au}{+}^{197}\mathrm{Au}$ collisions measured by the E895 Collaboration in the energy range from $(2–8)A\mathrm{GeV}$ at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity, $〈\beta \gamma {〉}_L$, as a function of the logarithm of beam energy.

Shell corrections are important in the determination of nuclear ground-state masses and shapes. Although general arguments favor a regular single-particle dynamics, symmetry breaking and the presence of chaotic layers cannot be excluded. The latter provide a natural framework that explains the observed differences between experimental and computed masses.

The neutron-rich ${}^{66,68}\mathrm{Ni}$ have been produced at GANIL via interactions of a $65.9A\mathrm{MeV}$ ${}^{70}\mathrm{Zn}$ beam with a ${}^{58}\mathrm{Ni}$ target. Their reduced transition probability $B({E2;0\mathrm{}}_1^{+}\to 2^{+})$ has been measured for the first time by Coulomb excitation in a ${}^{208}\mathrm{Pb}$ target at intermediate energy. The $B\left(E2\mathrm{}\right)$ value for ${}^{68}{\mathrm{Ni}}_{40}$ is unexpectedly small. An analysis in terms of large scale shell model calculations stresses the importance of proton core excitations to reproduce the $B\left(E2\mathrm{}\right)$ values and indicates the erosion of the $N=40\mathrm{}$ harmonic-oscillator subshell by neutron-pair scattering.

The ratio of the electric and magnetic form factors of the proton $G_{E_p}{/G}_{M_p}$, which is an image of its charge and magnetization distributions, was measured at the Thomas Jefferson National Accelerator Facility (JLab) using the recoil polarization technique. The ratio of the form factors is directly proportional to the ratio of the transverse to longitudinal components of the polarization of the recoil proton in the elastic $\overrightarrow{e}p\to e\overrightarrow{p}$ reaction. The new data presented span the range $3.5<\mathrm{}{Q}^2<5.6\mathrm{}{\mathrm{GeV}}^2$ and are well described by a linear $Q^2$ fit. Also, the ratio $\sqrt{Q^2}{F}_{2_p}{/F}_{1_p}$ reaches a constant value above $Q^2=2\mathrm{}{\mathrm{GeV}}^2$.

With a germanium detector array (Hyperball), we observed two $\gamma$-ray peaks corresponding to the two transitions ( ${5/2}^{+}\to {1/2}^{+}$ and ${3/2}^{+}\to {1/2}^{+}$) in the ${}_{\Lambda }^9\mathrm{Be}$ hypernucleus which was produced by the ${}^9\mathrm{Be}(K^{-},{\pi }^{-})$ reaction. The energies of the $\gamma$ rays are $3029\pm 2\pm 1\mathrm{keV}$ and $3060\pm 2\pm 1\mathrm{keV}$. The energy difference was measured to be ${31.4}_{-3.6\mathrm{}}^{+2.5\mathrm{}}\mathrm{keV}$, which indicates a very small $\Lambda$-spin-dependent spin-orbit force between a $\Lambda$ and a nucleon. This is the smallest level splitting by far ever measured in a hypernucleus.

We calculate the kaon-interferometry radius parameters for high-energy heavy-ion collisions, assuming a first-order phase transition from a thermalized quark-gluon plasma (QGP) to a gas of hadrons. At high transverse momenta $K_T\sim 1\mathrm{GeV}/c$ direct emission from the phase boundary becomes important; the emission duration signal, i.e., the $R_{\mathrm{out}}{/R}_{\mathrm{side}}$ ratio, and its sensitivity to $T_c$ (and thus to the latent heat) are enlarged. The $\mathrm{QGP}+\mathrm{hadronic}$ rescattering transport model calculations do not yield unusually large radii $\left(R_i\le 9\mathrm{fm}\right)$. Finite-momentum-resolution effects have a strong impact on the extracted interferometry parameters ( $R_i$ and $\lambda$), as well as on the ratio $R_{\mathrm{out}}{/R}_{\mathrm{side}}$.

Because of the time reversal invariance of the angular momentum operator $J^2$, the average energies and variances at fixed $J$ for random two-body Hamiltonians exhibit odd-even- $J$ staggering that may be especially strong for $J=0\mathrm{}$. It is shown that upon ensemble averaging over random runs, this behavior is reflected in the yrast states. Displaced (attractive) random ensembles lead to rotational spectra with strongly enhanced $B\left(E2\mathrm{}\right)$ transitions for a certain class of model spaces. It is explained how to generalize these results to other forms of collectivity.

Angular distributions of ${}^{12}\mathrm{C}(\alpha ,\alpha {)}^{12}\mathrm{C}$ have been measured for $E_{\alpha }=2.6\mathrm{}–8.2\mathrm{MeV}$, at angles from $24°$ to $166°$, yielding 12 864 data points. R-matrix analysis of the ratios of elastic scattering yields a reduced width amplitude of ${\gamma }_{12}=0.47\mathrm{}\pm 0.06{\mathrm{MeV}}^{1/2}$ for the $E_x=6.917\mathrm{}\mathrm{MeV}\left(2^{+}\right)$ state in ${}^{16}\mathrm{O}(a=5.5\mathrm{}\mathrm{fm})$. The dependence of the ${\chi }^2$ surface on the interaction radius $a$ has been investigated and a deep minimum is found at ${a=5.42\mathrm{}}_{-0.27\mathrm{}}^{+0.16\mathrm{}}\mathrm{fm}$. Using this value of ${\gamma }_{12}$, radiative $\alpha$ capture and ${}^{16}\mathrm{N}$ $\beta$-delayed $\alpha$-decay data, the S factor is calculated at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=300\mathrm{}\mathrm{keV}$ to be $S_{E2\mathrm{}}\left(300\right){=53\mathrm{}}_{-18\mathrm{}}^{+13\mathrm{}}\mathrm{keV}\mathrm{b}$ for destructive interference between the subthreshold resonance tail and the ground state $E2\mathrm{}$ direct capture.

The energy dependent neutron-induced fission cross section of ${}_{}{}^{233}{}_{}{}^{}P\mathrm{a}$ has for the first time been measured directly with monoenergetic neutrons. This nuclide is an important intermediary in a thorium based fuel cycle, and its fission cross section is a key parameter in the modeling of future advanced fuel and reactor concepts. A first experiment resulted in four cross section values between 1.0 and 3.0 MeV, establishing a fission threshold in excess of 1 MeV. Significant discrepancies were found with a previous indirect experimental determination and with model estimates.

E896 has measured $\Lambda$ production in $11.6A\mathrm{GeV}/c$ Au-Au collisions over virtually the whole rapidity phase space. The midrapidity $p_t$ distributions have been measured for the first time at this energy and appear to indicate that the $\Lambda$ hyperons have different freeze-out conditions than protons. A comparison with the relativistic quantum molecular dynamics model shows that while there is good shape agreement at high rapidity the model predicts significantly different slopes of the $m_t$ spectra at midrapidity. The data, where overlap occurs, are consistent with previously reported measurements.

The Müller-Israel-Stewart second-order theory of relativistic imperfect fluids based on Grad’s moment method is used to study the expansion of hot matter produced in ultrarelativistic heavy-ion collisions. The temperature evolution is investigated in the framework of the Bjorken boost-invariant scaling limit. The results of these second-order theories are compared to those of first-order theories due to Eckart and to Landau and Lifshitz and those of zeroth order (perfect fluid) due to Euler.

The traditional nuclear pairing problem is shown to be in one-to-one correspondence with a classical electrostatic problem in two dimensions. We make use of this analogy in a series of calculations in the tin region, showing that the extremely rich phenomenology that appears in this classical problem can provide interesting new insights into nuclear superconductivity.

The thermal component of the $8\mathrm{GeV}/c$ $\pi +\mathrm{Au}$ data of the ISiS Collaboration is shown to follow the scaling predicted by Fisher’s model when Coulomb energy is taken into account. Critical exponents $\tau$ and $\sigma$, the critical point $(p_c,{\rho }_c{,T}_c)$, surface energy coefficient $c_0$, enthalpy of evaporation $\Delta H$, and critical compressibility factor $C_c^F$ are determined. For the first time, the experimental phase diagrams, $(p,T)$ and $(T,\rho )$, describing the liquid vapor coexistence of finite neutral nuclear matter have been constructed.

The emission pattern in the $v_{\mathrm{perp}}{-v}_{\mathrm{par}}$ plane of intermediate mass fragments with $Z=3\mathrm{}–7$ (IMF) has been studied in the collision ${}^{116}\mathrm{Sn}+{}^{93}\mathrm{Nb}$ at $29.5A\mathrm{MeV}$ as a function of the total kinetic energy loss of the reaction. This pattern shows that for peripheral reactions most IMF’s are emitted at velocities intermediate between those of the projectile- and target-like products. Coulomb trajectory calculations show that these IMF’s are produced in the interaction zone in a short time interval at the end of the target-projectile interaction.

A strong increase of inclusive nuclear-charge pickup cross sections, forming ${}_{83}\mathrm{Bi}$ from $158A\mathrm{GeV}$ ${}_{82}\mathrm{Pb}$ ions, is observed in comparison to similar measurements at $10.6A\mathrm{GeV}$. From the dependence of these cross sections on target atomic number, this increase is attributed to the electromagnetic process of pion production by equivalent photons. The observed cross sections can be reproduced quantitatively using the recently developed RELDIS code.

Numbers of protons per $\Gamma$ hypernuclear weak decay were measured as a function of proton energy above 40 MeV, explicitly identifying production of $\Gamma$ hypernuclei by the $\left({\pi }^{+}{,K}^{+}\right)$ reaction. The ratios between the neutron-stimulated to proton-stimulated nonmesonic decay widths, $\Gamma (\Lambda n\to \mathrm{nn})/\Gamma (\Lambda p\to \mathrm{np})(={\Gamma }_n/{\Gamma }_p)$ were extracted by fitting the proton energy spectra. The present result claims that the proton yields are suppressed and the ${\Gamma }_n/{\Gamma }_p$ ratios are close to 1 both for ${}_{\Lambda }^{12}\mathrm{C}$ and ${}_{\Lambda }^{28}\mathrm{Si}$ in contradiction to theoretical expectations based on meson exchange models.