First results of the $m_T$ dependence of ${\pi }^{+}{\pi }^{+}$ and $K^{+}{K}^{+}$ correlations from $\mathrm{S}+\mathrm{Pb}$ collisions at 200 GeV $/c$ per nucleon measured by the focusing spectrometer of the NA44 experiment at CERN are presented. Multidimensional fits characterize the pion and kaon emission volume. The pion radius parameter decreases with increasing $p_T$. Furthermore, the pion and kaon radii show a common $1/\sqrt{m_T}$ dependence. This behavior can be interpreted as a result of a strong momentum-position correlation arising from collective flow.

We demonstrate that fluctuations, their relaxation, and the chiral phase transition are automatically incorporated in the numerical simulations of the classical equations of motion in the linear $\sigma$ model when longitudinal and transverse expansions are included. We find that domains of disoriented chiral condensate with 4–5 fm in size can form through a quench while an annealing leads to domains of smaller sizes. We also demonstrate that quenching cannot be achieved by relaxing a chirally symmetric system through expansion.

We investigate the time evolution of a quark-antiquark plasma by solving numerically the relativistic transport equations derived on the Hartree level from the Nambu–Jona-Lasinio model. We find that the phase transition in the expanding quark-antiquark plasma is different as compared to that in a static plasma. The expansion competes with the transition, and finally quark droplets will be formed which subsequently hadronize. These findings raise the question of whether static thermal models can make at all any prediction about signals of that transition.

We study the thermal properties of ${}^{54}\mathrm{Fe}$ with the Brown-Richter interaction in the complete $1p0f$ model space. Monte Carlo calculations show a peak in the heat capacity and rapid increases in both the moment of inertia and $M1\mathrm{}$ strength near a temperature of 1.1 MeV that are associated with the vanishing of proton-proton and neutron-neutron monopole pair correlations; neutron-proton correlations persist to higher temperatures. Our results are consistent with a Fermi gas level density whose backshift vanishes with increasing temperature.

Differential cross sections from kinematically complete measurements of $\mathrm{pp}\to \mathrm{pn}{\pi }^{+}$ production are presented for proton beam energies of 294.2, 299.5, and 319.5 MeV. Total cross sections are given for 294.2, 299.5, 306.5, 314.3, and 319.5 MeV. The two angular distributions close to threshold are dominated by $s$ wave contributions. Total cross sections within the first 30 MeV of threshold show qualitative agreement with an early theoretical prediction based on PCAC.

A Comment of the Letter by H. van der Ploeg, et al., Phys. Rev. Lett. 68, 3145 (1992).

A Reply to the Comment by Chr. Bargholtz, et al.

We discuss the implications of a doorway state model for parity mixing in compound nuclear states. We argue that in order to explain the tendency of parity violating asymmetries measured in ${}^{233}\mathrm{Th}$ to have a common sign, doorway states that contribute to parity mixing must be found in the same energy neighborhood of the measured resonance. The work concentrates on novel nuclear structure input, namely, that in the region of interest ( ${}^{233}\mathrm{Th}$) nuclei exhibit octupole deformations which leads to the existence of nearby parity doublets. These parity doublets are then used as doorway states in a model for parity mixing.

The cross section for the astrophysically important ${}_{}{}^{17}{}_{}{}^{}O(p,\alpha ){}_{}{}^{14}{}_{}{}^{}N$ reaction was measured at proton energies of 75 and 65 keV. Thick, high-purity ${\mathrm{Ta}}_2{O}_5$ targets (77% enriched ${}_{}{}^{17}{}_{}{}^{}O$) and large-area detectors were used with beam currents of 0.45 mA. Backgrounds were measured using ${\mathrm{Ta}}_2{O}_5$ targets of natural isotopic composition. The expected resonance at $E_p=70\mathrm{}$ keV was observed in the data taken at 75 keV, and its proton width was found to be $22\pm 3_{\mathrm{stat}}\pm 2_{\mathrm{target}}{}_{-1\mathrm{}\mathrm{beam}}^{+2\mathrm{}}$ neV.

Using charged-particle-exclusive measurements of $\mathrm{Au}+\mathrm{Au}$ collisions in the LBL Bevalac's EOS time projection chamber, we investigate momentum-space densities of fragments up to ${}^4\mathrm{He}$ as a function of fragment transverse momentum, azimuth relative to the reaction plane, rapidity, multiplicity, and beam energy. Most features of these densities above a transverse momentum threshold are consistent with momentum-space coalescence, and, in particular, the increase in sideward flow with fragment mass is generally well described by a momentum-space power law.

The neutron transmission through a thorogenic liquid ${}^{208}\mathrm{Pb}$ sample 2 in. thick has been measured in the neutron energy range between 0.1 and 360 eV at the ORNL neutron source ORELA. Analyzing the shape of the transmission spectra as a function of neutron energy, agreement was found with the predictions by the atomic form factor. With a sensitivity for the mean squared charge radius of the neutron $〈r_n^2〉$ as high as 3%, a very reliable and also accurate result of $〈r_n^2〉=-0.113\mathrm{}\pm 0.003\pm 0.004{\mathrm{fm}}^2$ was extracted. For the neutron-electron scattering length we obtained $b_{\mathrm{ne}}=(-1.31\mathrm{}\pm 0.03\pm 0.04)\times {10}^{-3\mathrm{}}\mathrm{fm}$.

The α-particle clustering structure of ${}^{94}$Mo and ${}^{212}$Po, which is of interest for investigating the persistence of α clustering in heavy nuclei, is studied within the framework of a local potential approach using a double folding model. It is shown that the model, which describes α scattering from ${}^{90}$Zr well, locates the ground state of ${}^{94}$Mo at the energy corresponding to experiment. A similar result was obtained for the $\alpha {+}^{208}\mathrm{Pb}$ system. It is found that the model gives not only the ground band of ${}^{94}$Mo and ${}^{212}$Po as compact α-cluster states but also predicts other developed genuine α-cluster states below and near the Coulomb barrier.

Deuteron momentum distributions are predicted for nucleus-nucleus reactions at beam energies of (10–15) $A$ GeV. The deuteron transverse momentum spectra exhibit a pronounced shoulder-arm shape deviating markedly from thermal distributions due to collective transverse nuclear flow. A clear “bounceoff” event shape is seen for protons and deuterons: The transverse momentum components in the reaction plane are for deuterons up to a factor of 2 larger than for protons. The strength of the collective matter flow is sensitive to the type of baryon potential interaction employed. This allows the study of the transient mean fields at high density in these reactions via the event shape analysis of nucleons and nucleon clusters.

A high-spin rotational band of ten transitions between 1305 and 2641 keV with a nearly constant moment of inertia $J^{\left(2\right)}=27\mathrm{}{ħ}^2\mathrm{M}\mathrm{eV}{}^{-1\mathrm{}}$ has been observed and is tentatively assigned to ${}^{83}$Sr. The properties of this band are in excellent agreement with theoretical calculations which predict the onset of superdeformation in and around ${}^{83}$Sr at spins $I\approx 35ħ$. These results establish a new region of superdeformation in medium-mass nuclei with particle numbers $N,Z\approx 40$.

Four superdeformed bands, consisting of $\gamma$-ray cascades of up to 15 transitions, have been found in the light rare earth nucleus ${}^{133}$Pr. This is the first observation of multiple superdeformed bands in the $A\approx 130$ mass region. These bands are populated weakly at 0.2%–1% of the reaction channel intensity. The single particle configurations have been identified as $\pi g_{9/2}\left[404\right]{9/2}^{+}$ for bands 1 and 2 and $\pi h_{11/2}\left[532\right]{5/2}^{-}$ for bands 3 and 4. Dipole linking transitions between two superdeformed bands have been observed, branching ratios have been measured, and $B\left(M1\mathrm{}\right)/B\left(E2\mathrm{}\right)$ ratios deduced. A $B\left(M1\mathrm{}\right)$ value for the $\pi g_{9/2}\left[404\right]{9/2}^{+}$ orbital of $(1.7\pm 0.2){\mu }_N^2$ (where ${\mu }_N$ is the nuclear magneton) has been extracted, based on the measured quadrupole moment for the ${}^{132}$Ce core.

Two excited superdeformed (SD) bands have been observed in ${}^{132}\mathrm{Ce}$ using the Eurogam gamma-ray spectrometer. Possible configurations are proposed in terms of particle-hole excitation from a theoretical analysis based on the cranking approximation with the Woods-Saxon deformed potential. From relationships between $\gamma$-ray energies of SD bands in ${}^{132}\mathrm{Ce}$ and ${}^{131}\mathrm{Ce}$, the existence of identical bands and approximately quantized alignments is established in the mass 130 region.

The reaction ${}_{}{}^{12}{}_{}{}^{}C\left({e,e}^{\prime }\mathrm{pp}\right)$ has been studied at an energy transfer $\omega =212\mathrm{MeV}$ and a three-momentum transfer $|\mathit{q}|=70\mathrm{MeV}/c$. The measured missing-energy spectrum shows a signature for knockout of proton pairs from $(1p{)}^2$, $(1p,1s)$, and $(1s{)}^2$ states. A comparison of the data with a calculation, in which different processes leading to two-nucleon knockout are accounted for, shows that the measured cross section for the knockout of a $(1p{)}^2$ pair can largely be attributed to short-range nucleon-nucleon correlations.

Gamow-Teller strength functions in the resonance region are calculated in the full $(\mathrm{pf}{)}^8$ space. The observed profile is very sensitive to the level density and may become so diluted as to be confused with background. A model independent proof is given that standard quenching originates in nuclear correlations, and that some 30% of the total strength must be due to states outside the $(\mathrm{pf}{)}^8$ space. By combining this argument with the results of shell model calculations, comparison with the ${}^{48}\mathrm{Ca}(p,n{)}^{48}\mathrm{Sc}$ experimental data strongly suggest that most of the strength that is currently thought to be missing is actually observed.

A measurement of the superallowed $0^{+}\to 0^{+}$ branching ratio in ${}^{10}$C performed with the $8\pi$ gamma-ray spectrometer is described. From the measured branching ratio, we extract a new precise value of $Ft{(}^{10}\mathrm{C})=3076.7\mathrm{}(6.0)\mathrm{s}$. This does not support previously suggested $Z$- or $Z^2$-dependent corrections to the superallowed $0^{+}\to 0^{+}$ data set, which removed the apparent nonunitarity of the Cabibbo-Kobayashi-Maskawa matrix.

Nuclear transparencies measured in exclusive incoherent ${\mathrm{\rho }}^0$ meson production from hydrogen, deuterium, carbon, calcium, and lead in muon-nucleus scattering are reported. The data were obtained with the E665 spectrometer using the Fermilab Tevatron muon beam with a mean beam energy of 470 GeV. Increases in the nuclear transparencies are observed as the virtuality of the photon increases, in qualitative agreement with the expectations of color transparency.