Multifragment azimuthal correlation functions have been measured as a function of beam energy and impact parameter for the Ar+Sc system (E/A=35 to 115 MeV). The observed azimuthal correlation functions—which do not require corrections for dispersion of the reaction plane—exhibit strong asymmetries which are dependent on impact parameter and beam energy. Rotational collective motion and flow seem to dominate the correlation functions at low beam energies. It is proposed that multifragment azimuthal correlation functions can provide a useful probe for intermediate energy heavy ion reaction dynamics.

We study various nonequilibrium properties of a mixture comprised of pions, kaons, and nucleons. Quantitative calculations of the relaxation/collision times, the degradation of momentum in elastic collisions, and the relaxation times of shear and heat flows, drag flow, and diffusion flow are performed. Binary interactions are specified through the empirical phase shifts. The heavier kaons and nucleons are found to equilibrate more slowly than pions. These results shed new light on the influence of collective flow effects on the transverse momentum distributions of kaons and nucleons versus those of pions in ultrarelativistic nuclear collisions.

The E-802 spectrometer at the Brookhaven Alternating Gradient Synchrotron, enhanced by a trigger for selection of events with one or more specified particles, has been used to measure the momentum-space correlation between pairs of ${\mathit{K}}^{+}$’s emitted in central Si+Au collisions at 14.6 A GeV/c. This correlation has been projected onto the Lorentz-invariant relative four-momentum axis. Fits to this correlation function yield a size for the kaon source that is comparable to that found using ${\mathrm{\pi }}^{+}$ pairs from a similar rapidity range, once a transformation from the particle-pair frames to a single source frame is made.

General exact projection formulas at finite temperature for one-body statistical operators with broken symmetries are derived and applied to the calculation of angular momentum projected average energies and level densities in the static path approximation. The method is illustrated for ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ using a quadrupole interaction and compared with exact shell model results.

A rotational band based on the proton ${\mathit{h}}_{11/2}$ orbital has been observed to high spin (79/2ħ) and high rotational frequency (ħω≃1.0 meV) in the nucleus ${}_{51}{}^{113}{}_{}{}^{}\mathrm{Sb}$. The measured transition quadrupole moment is ${\mathit{Q}}_0$=4.4±0.6 e b, consistent with an axial prolate deformation of ${\mathrm{\beta }}_2$≃0.32. A large interaction strength (360±60 keV) has been measured for the rotational alignment of ${\mathit{h}}_{11/2}$ neutrons which, together with a considerable delay in the crossing frequency (Δħω≃0.09 MeV), is construed as the first direct evidence of a large high-j proton-neutron interaction.

Connections between the superdeformed and normal-deformed states in ${}_{}{}^{143}{}_{}{}^{}\mathrm{Eu}$ have been established by measuring energy sums of two consecutive γ-ray transitions in the linking cascade. Six decay paths have been observed connecting discrete states in the two potential wells. The absolute excitation energy and the most likely spin of the superdeformed band have been determined directly for the first time.

We present results from an experimental study of reabsorption effects in subthreshold ${\mathrm{\pi }}^0$ production in the reaction ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$${+}^{197}$Au at 44 MeV/nucleon. Within the picture of pion generation in nucleon-nucleon scattering we deduce, from our data and from a comparison with the systematics of production cross sections available for lighter reaction systems, information on the ${\mathrm{\pi }}^0$ absorption length in nuclear matter. For the ${\mathrm{\pi }}^0$ kinetic-energy range ≃5–100 MeV the energy-averaged ${\lambda }_{\mathrm{abs}}$ and its momentum dependence are obtained, and compared with optical-model calculations.

The α spectrum following the β decay of ${}_{}{}^{16}{}_{}{}^{}\mathrm{N}$ from the isotope separator TISOL has been measured by detecting ${10}^6$ α particles in coincidence with ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ nuclei. These data, which show a low-energy interference anomaly accompanying the main α peak, permit a more precise determination of the p-wave amplitude of the astrophysically important reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(α,γ${)}^{16}$O. The α spectrum and previous γ-ray data have been fitted simultaneously by a K-matrix parametrization; a value of S(E=0.3 MeV)=57±13 keV b has been obtained for the E1 part of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(α,γ${)}^{16}$O reaction.

Kinematically complete measurements for Coulomb dissociation of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ into ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$+2n were made at 28 MeV/nucleon. The n-n correlation function suggests a large source size for the two-neutron emission. The electromagnetic excitation spectrum of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ has a peak, as anticipated in low-energy dipole resonance models, but a large post-breakup Coulomb acceleration of the ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ fragment is observed, indicating a very short lifetime of the excited state and favoring direct breakup as the dissociation mechanism.

A complete set of diagonal spin-transfer observables has been measured at excitation energies between 30 and 40 MeV for inelastic proton scattering from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ at 497 and 581 MeV at a momentum transfer of 0.56 ${\mathrm{fm}}^{\mathrm{-}1}$. The longitudinal and transverse spin-flip probabilities are deduced. Their unequal enhancements relative to free nucleon-nucleon scattering values are explained by a distorted-wave impulse approximation calculation in which the finite nucleus random-phase approximation is used to describe the nuclear respose.

We report the first measurement of analyzing powers and spin correlation parameters using a storage ring with both beam and internal target polarized. Spin observables were measured for elastic scattering of 45 and 198 MeV protons from polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ nuclei in a new laser-pumped internal gas target at the Indiana University Cyclotron Facility Cooler Ring. Scattered protons and recoil ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ nuclei were detected in coincidence with large acceptance plastic scintillators and silicon detectors. The internal-target technique demonstrated in this experiment has broad applicability to the measurement of spin-dependent scattering in nuclear and particle physics.

The photon decay of the relativistic Coulomb excitation of the single and double giant dipole resonance (GDR) in the target has been observed in the system 1A GeV ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. For peripheral events which are dominated by relativistic Coulomb excitation, a large Lorentzian structure in the photon energy spectrum is peaked at 13.3±0.1 MeV with a width of 4.1±0.1 MeV, corresponding to the single GDR in the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ target. The sum energy of coincident γ-γ pairs shows a broad feature at 25.6±0.9 MeV with a Lorentzian width of 5.8±1.1 MeV, which we assign to the double GDR observed via the two-γ decay channel.

The U-like K-vacancy production probability in 7.5-MeV/nucleon deep-inelastic ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$${+}^{238}$U collisions has been measured for no-fission, single-fission, and double-fission exit channels. The results are interpreted using quasimolecular orbital correlations for diatomic and triatomic configurations. This leads to the determination of lower limits for the time scale for late fission of U-like products (≥8 and ≥4 as) and their probability (≥77% and ≥52%), at mean initial-excitation energies of ∼40 and ∼105 MeV, respectively.

We have searched for the effect of a neutrino of mass 17 keV/${\mathit{c}}^2$ in the beta decay of ${}_{}{}^{35}{}_{}{}^{}\mathrm{S}$ with an appartus incorporating a high-resolution solid-state detector and a superconducting solenoid. The experimental mixing probability, ${\sin }^2$θ=-0.0004±0.0008(stat) ±0.0008(syst), is consistent with zero, in disagreement with several previous experiments. Our sensitivity to neutrino mass is verified by measurements with a mixed source of ${}_{}{}^{35}{}_{}{}^{}\mathrm{S}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$, which artificially produces a distortion in the beta spectrum similar to that expected from the massive neutrino.

In general, the spectrum of lepton pairs produced in nuclear reactions depends on both invariant mass and momentum. But under a few reasonable assumptions on the time evolution of the system, we show that once the quark-gluon plasma is created in ultrarelativistic heavy ion collisions, the observed dilepton spectrum between the φ and J/ψ peak becomes dependent essentially only on its transverse mass ${\mathit{M}}_{\mathit{T}}$ and thus shows ${\mathit{M}}_{\mathit{T}}$ scaling. This scaling will not be observed if the quark-gluon plasma is not created in collisions.

Valence correlation schemes provide powerful tools to interpret nuclear phenomenology. It is shown that nearly all B(E2:$2_1^{+}$→$0_1^{+}$) values from light nuclei to the actinides are encompassed in a tight correlation envelope by expressing these B(E2) values in Weisskopf units, normalizing to the mass, and plotting against ${\mathit{N}}_{\mathit{p}}$${\mathit{N}}_{\mathit{n}}$. ‘‘Deviant’’ nuclei are thereby highlighted, and it is concluded that B(E2:$2_1^{+}$→$0_1^{+}$) values alone can provide signatures, not only of quadrupole collectivity, but also of axial asymmetry, hexadecapole shapes, shape coexistence, saturation of collectivity, shell structure, and the evolution of shell gaps. Moreover, combined with E($4_1^{+}$)/E($2_1^{+}$) ratios, B(E2:$2_1^{+}$→$0_1^{+}$) values provide a simple new method to distinguish the two principal classes of nuclear phase transitions.

Experimental and theoretical evidence is presented that the proton exchange is strongly enhanced by a mixing of single-particle configurations in ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ (in the system ${}_{}{}^{36}{}_{}{}^{}\mathrm{S}$${+}^{37}$Cl, which is shown to be the clearest example of hybridization in nuclear physics. The experimental data on elastic and inelastic transfer are only reproduced if the complete set of single-particle states (${\mathit{d}}_{3/2}$,${\mathit{s}}_{1/2}$,${\mathit{f}}_{7/2}$,${\mathit{p}}_{3/2}$,${\mathit{f}}_{5/2}$, and ${\mathit{p}}_{1/2}$) is included in a coupled-reaction-channel calculation. The strong enhancement is explained by the hybridization of orbits of different parity. In a two-center molecular-orbital approach the density of the proton orbitals in the lowest state is shown to be concentrated at the center between the two ${}_{}{}^{36}{}_{}{}^{}\mathrm{S}$ cores.

We describe some implications for massive dihadron production experiments of recent observations in Fermilab experiments E609 and E557 of large nuclear rescattering effects in dijet production in hard pA collisions. Substantial upward corrections to α (in the ${\mathit{A}}^{\mathrm{\alpha }}$ cross section parametrization) are indicated for dihadron experiments which detect symmetric back-to-back hadrons with narrow acceptance in azimuth or ${\mathit{p}}_{\mathit{T}}$. Other consequences of the large nuclear rescattering are also discussed.

The (${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^{\mathrm{-}}$) double-charge-exchange reaction for pion energies of 200 to 1400 MeV is calculated with a zero-parameter Glauber theory that includes spin flip and pion absorption. Differential cross sections and excitation functions are obtained for ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ targets. Results for ${\mathit{T}}_{\mathrm{\pi }}$=300–525 MeV are compared with recent experimental results and suggest a new quenching process. We have calculated effects of medium polarization on the isovector pion operator and find a strong reduction in good agreement with data. A pronounced dip in the cross section near ${\mathit{T}}_{\mathrm{\pi }}$=1300 MeV offers a unique testing ground for unconventional mechanisms.

In a plunger experiment the mean life of the (ν${\mathit{f}}_6^2$×$3^{\mathrm{-}}$×$3^{\mathrm{-}}$)${12}^{+}$ state at 3.981 MeV in ${}_{64}{}^{148}{}_{}{}^{}\mathrm{Gd}_{84}^{}{}_{}{}^{}$ was measured at τ=83(10) ps, giving 77(11)${\mathit{B}}_{\mathit{W}}$ for the 1286 keV ${12}^{+}$→$9^{\mathrm{-}}$ E3 transition rate, confirming the double-octupole character of the ${12}^{+}$ state. The observed deviations in energy and transition rate from harmonic vibration are shown to be caused by the exclusion principle acting between nucleons in the two phonons and are related to the dominant contributions to the ${}_{}{}^{148}{}_{}{}^{}\mathrm{Gd}$ octupole phonon of the low-lying Δl=Δj=3 proton and neutron in-shell $3^{\mathrm{-}}$ excitations which are of vital significance for the octupole mode in open-shell nuclei.