By the concept of effective boson numbers, systematics of the ${\mathit{E}}_{2_1^{+}}$, ${\mathit{E}}_{4_1^{+}}$, ${\mathit{E}}_{6_1^{+}}$, R=${\mathit{E}}_{4_1^{+}}$/${\mathit{E}}_{2_1^{+}}$, B(E2,$0_1^{+}$→$2_1^{+}$), and ${\mathit{Q}}_0$ for the even-even nuclei with A≥70 are presented. Some features for the excitation energies in the ground state band are observed and an intuitive explanation is given. Assuming correlation between the E2 and M1 transition strengths, the general trend of B(M1) for the even-even actinide nuclei is predicted. The results in this paper are also compared with the previous results in the ${\mathit{N}}_{\mathrm{\pi }}$${\mathit{N}}_{\nu }$ scheme and other parametrizations.

The isotopic production cross sections and momenta of all residues with nuclear charge greater than 39 from the reaction of 26, 40, and 50 MeV/nucleon ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$+Be, C, and Al were measured. The isotopic cross sections, the momentum distribution for each isotope, and the cross section as a function of nuclear charge and momentum are presented here. The new cross sections are consistent with previous measurements of the cross sections from similar reaction systems. The results are compared to a geometric incomplete fusion model and a Boltzmann-Nordheim-Vlasov model. Agreement between the models and the data is fair. The most proton-rich nuclei observed in this study are predicted to have less than 50 nb production cross sections by both of these models but are observed to have much larger cross sections.

The (e,2p) and (e,2n) cross sections and the (e+γ,2p) and (e+γ,2n) yields have been measured for ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ in the electron energy range 28–60 MeV. The experimental results have been analyzed using distorted-wave Born approximation E1 and E2 virtual photon spectra in order to derive the E1 and isovector E2 components of the (γ,2p) and (γ,2n) cross sections. In the 2n channel the E1 component exhausts 12.4(11)% of the E1 energy weighted sum, while the isovector E2 component exhausts 52(15)% of its sum. The 2p channel exhausts 1.03(8)% of the energy weighted sum for E1 and we were able to establish an upper limit for the isovector E2 contribution of 0.58% of its sum.

We report measurements of the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$(n,p) differential cross section at an incident energy of 198 MeV and angles from 0° to 24° using the TRIUMF Charge Exchange Facility. From these data we determine Gamow-Teller (GT) transition probabilities to low lying 1/$2^{+}$, 3/$2^{+}$, and 5/$2^{+}$ ${}_{}{}^{23}{}_{}{}^{}\mathrm{Ne}$ states and the ${\mathrm{GT}}^{+}$ strength distribution up to 25 MeV excitation energy. The values of ${\mathrm{B}}_{\mathrm{GT}}^{+}$ to discrete states, and the ${\mathrm{GT}}^{+}$ strength below 10 MeV, are found to be in reasonable agreement with a full 1s-0d shell model calculation with a normalization factor of about 0.74. The ${\mathrm{GT}}^{+}$ strength above 10 MeV suggests the removal of strength from lower to higher excitation energies. We also compare the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$(n,p) data with ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$(${\mathrm{\mu }}^{\mathrm{-}}$,ν) data and find agreement between the values of ${\mathrm{B}}_{\mathrm{GT}}^{+}$ to discrete levels extracted from the (n,p) and (${\mathrm{\mu }}^{\mathrm{-}}$,ν) reactions. The general consistency of the (n,p) and (${\mathrm{\mu }}^{\mathrm{-}}$,ν) data, and the full 1s-0d shell model calculation, give confidence in a recent extraction of the weak pseudoscalar coupling from ${\mathrm{\mu }}^{\mathrm{-}}$ capture on ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$. Finally, using both ${\mathrm{\beta }}^{\mathrm{-}}$-decay and ${\mathrm{\mu }}^{\mathrm{-}}$ capture data, we obtain unit cross sections from the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$(n,p) measurement.

The neutron total cross section of ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$ has been measured over the energy range 0.013 to 0.310 MeV. An R-matrix analysis has been performed to obtain resonance and average parameters which provide for a complete representation of the neutron entrance channels for the ${\mathit{s}}_{1/2}$, ${\mathit{p}}_{1/2}$, and ${\mathit{p}}_{3/2}$ contributions. The conventional s- and p-neutron strength functions have been determined to be 0.123±0.023 and 2.0±0.2, respectively (in units of ${10}^{\mathrm{-}4}$). Limits are placed on the average level spacings and strength functions for the individual partial wave components. The s-wave potential scattering radius has been determined to be 6.3±0.1 fm. Average scattering functions, deduced from the average parameters, have been used to determine the real well depth of an optical model potential which reproduces these functions. We find, as have others, that the real well depth is parity dependent.

Production of 5.84 h ${}_{}{}^{189}{}_{}{}^{}\mathrm{Os}_{}^{\mathit{m}}{}_{}{}^{}$ by 200 through 300 kV bremsstrahlung has been measured and attributed to population of four nuclear states between 69.54 and 275.91 keV. From the measurements and known level parameters, contributions to isomer production from individual levels have been separated, and the half-life of the 216.66 keV level has been determined as 77±10 ps. Besides nuclear resonance absorption (NRA), the first level has long been assumed to be also excited by another process called nuclear excitation by electron transition (NEET), via virtual photon exchange due to recombination of vacancies produced in the K shell by incident x rays. However, contribution from competing NRA cannot be separated, and the claimed dominance or even the existence of the NEET process has remained unconfirmed.

Photoexcitation of 5.84 h ${}_{}{}^{189}{}_{}{}^{}\mathrm{Os}_{}^{\mathit{m}}{}_{}{}^{}$ and 10.6 d ${}_{}{}^{193}{}_{}{}^{}\mathrm{Ir}_{}^{\mathit{m}}{}_{}{}^{}$ was observed using high activity ${}_{}{}^{137}{}_{}{}^{}\mathrm{Cs}$ and ${}_{}{}^{60}{}_{}{}^{}\mathrm{Co}$ sources for irradiation. The highly converted weak isomeric transitions were detected by large area 2π multiwire proportional chambers. Determining resonance photon flux densities with Monte Carlo simulation, isomer excitation cross sections integrated over identified activation levels were evaluated and level half-lives were derived.

We present the results of a measurement of the spin-dependent asymmetry in ${}_{}{}^3{}_{}{}^{}\to$(e→,e′) inelastic scattering at kinematics on the low-energy transfer side of the quasielastic peak, including the region near the breakup threshold. Comparison with existing calculations based upon the plane wave impulse approximation shows significant deviation between the data and the model near the breakup threshold. Good agreement between data and theory is seen at higher energy transfer.

Alpha scattering from ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ at ${\mathit{E}}_{\mathrm{\alpha }}$= 65 MeV is described in the coupled channel framework with phenomenological as well as folded potentials. The multipole components of the deformed density of ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ are derived from Nilsson model wave functions. Reasonably good agreements are obtained for the angular distributions of 3/$2^{\mathrm{-}}$(g.s.) and 5/$2^{\mathrm{-}}$(2.43 MeV) states of the ground state band with folded potentials. The deformation predicted by the model corroborates with that derived from the phenomenological analysis with potentials of different geometries.

As a model for understanding the appearance of narrow lines in positron singles and electron-positron sum energy spectra found in heavy-ion collisions close to the Coulomb barrier, we propose the following scenario: After the Coulomb scattering both heavy nuclei are very likely in low (≤2 MeV) excited states, which subsequently decay by correlated monoenergetic (${\mathit{e}}^{+}$,${\mathit{e}}^{\mathrm{-}}$) pair conversion (MPC) and internal conversion (IC) processes thereby producing an asymptotic (${\mathit{e}}^{+}$,${\mathit{e}}^{\mathrm{-}}$) pair with the sum energy of the two nuclear transitions. We only consider processes where the two nuclear transitions are correlated by an intermediate bound electron state (the 1σ orbital) of the nuclear scattering system. Since this orbital is only weakly time dependent and persists for ∼${10}^{\mathrm{-}19}$ s, we obtain rather narrow, ${\mathrm{\Gamma }}_{{\mathit{e}}^{+}{\mathit{e}}^{\mathrm{-}}}$∼20 keV, sum energy lines for the (${\mathit{e}}^{+}$${\mathit{e}}^{\mathrm{-}}$) pair from this process. We, however, find that correlated E0-E0-transitions have cross sections at least 8 orders of magnitude too small and can safely be excluded as the cause of the narrow sum energy spectra observed experimentally. A rough estimate of the cross section indicates that correlated E1-E1 transitions occur with a substantially larger cross section and should thus be investigated in detail.

Measurements of the excitation of nuclear giant resonances by heavy-ion inelastic scattering have previously been analyzed using the deformed optical potential model. Here we reexamine these data using a folded potential model which employs a simple, but effective, nucleon-nucleon interaction that was deduced recently from heavy-ion elastic scattering measurements. The resulting estimates of the sum-rule exhaustion by the giant quadrupole resonance increase by amounts ranging from about 20% for the lighter targets to no change for ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. Applying the same model to data for excitation of the giant monopole resonance, we find that these transitions overexhaust the corresponding sum rule even more than previously indicated.

Previously published results of coincidence measurements between incomplete fusion products and fission fragments from the reaction of 140 MeV ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ with ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ have been used to determine the incomplete fusion contributions to the inclusive fission fragment angular distribution. The incomplete fusion contributions have been subtracted from the inclusive angular distribution, leaving the part due to complete fusion. Because the incomplete fusion processes account for 42% of the fission cross section, the maximum angular momentum contributing to complete fusion is reduced to approximately 55ħ. The angular distribution for fission following complete fusion has been compared with calculations made with the saddle point transition state model and with Bond’s scission point model. When proper account is taken of the large reduction in nuclear temperature at the saddle point due to pre-fission neutron evaporation, the saddle point transition state model reproduces the data very well. Proper handling of the incomplete fusion contributions is found to greatly improve the agreement of Bond’s scission point model with the data for this reaction.

We investigate the intermittent and multifractal behaviors of the multiplicity fluctuations of medium energy particles in 800 GeV proton interactions with emulsion nuclei. For our analysis, we have used ordinary scaled factorial moments (SFM) denoted as ${\mathit{F}}_{\mathit{q}}$, modified SFM, (${\mathit{F}}_{\mathit{q}}^{\prime }$) and modified multifractal moments, (${\mathit{G}}_{\mathit{q}}^{\prime }$) with suppressed statistical contributions. For a close comparison between the ${\mathit{F}}_{\mathit{q}}^{\prime }$ and ${\mathit{G}}_{\mathit{q}}^{\prime }$ moments, they have both been expanded in a set of basic functions each of which has a characteristic fractal behavior as a function of the resolution in phase space. The experimental values of anomalous fractal dimensions ${\mathit{d}}_{\mathit{q}}$ and Renyi dimensions ${\mathit{D}}_{\mathit{q}}$ are determined for q=2-5. The latter are corrected for statistical contamination in the multiplicity fluctuations. The observed variation of ${\mathit{d}}_{\mathit{q}}$ and ${\mathit{D}}_{\mathit{q}}^{\mathrm{dyn}}$ with q supports a self-similar random cascading mechanism for the particle production process. It is found that ${\mathit{D}}_{\mathit{q}}^{\mathrm{dyn}}$+${\mathit{d}}_{\mathit{q}}$=1.

Recent estimates suggest that the production of strange exotic objects, such as the hypothetical H dibaryon (H), is surprisingly large in Au collisions at AGS energies. Two possible bound states of the H, namely H${\mathrm{-}}^3$He and H-d, would be well separated in mass from known nuclear isotopes and therefore could be uniquely identified by experiment. We report the null result of a first search for these objects in Au+Pt collisions at the AGS, and limit their production cross sections for stable systems to ∼${10}^{\mathrm{-}5}$ mb/(GeV${)}^2$, near y=0.6 and ${\mathit{p}}_{\mathit{t}}$/Z=0.18 GeV/c.

We recently introduced a completely new way to study ultrarelativistic nuclear scattering by providing a link between the string model approach and a statistical description. A key issue is the microcanonical treatment of hadronizing individual quark matter droplets. In this paper we describe in detail the hadronization of these droplets according to n-body phase space, by using methods of statistical physics, i.e., constructing Markov chains of hadron configurations.

Nucleon correlations in the target and projectile nuclei are shown to reduce significantly the fluctuations in multiple nucleon-nucleon collisions, total multiplicity, and transverse energy in relativistic heavy-ion collisions, in particular for heavy projectile and target. The interplay between cross-section fluctuations, from color transparency and opacity, and nuclear correlations is calculated and found to be able to account for large fluctuations in transverse energy spectra. Numerical implementation of correlations and cross-section fluctuations in Monte Carlo codes is discussed.

The systematics of strangeness enhancement is calculated using the hijing and venus models and compared to recent data on pp, pA, and AA collisions at CERN/SPS energies (200A GeV). The hijing model is used to perform a linear extrapolation from pp to AA. venus is used to estimate the effects of final state cascading and possible nonconventional production mechanisms. This comparison shows that the large enhancement of strangeness observed in S+Au collisions, interpreted previously as possible evidence for quark-gluon plasma formation, has its origins in nonequilibrium dynamics of few nucleon systems. A factor of 2 enhancement of ${\mathrm{\Lambda }}^0$ at midrapidity is indicated by recent pS data, where on the average one projectile nucleon interacts with only two target nucleons. There appears to be another factor of 2 enhancement in the light ion reaction SS relative to pS, when on the average only two projectile nucleons interact with two target ones.

We investigate the nucleon to Δ(1232) vector and axial vector amplitudes in the nonrelativistic quark model of the Isgur-Karl variety. A particular interest is to investigate the SU(6) symmetry breaking, due to color hyperfine interaction. We compare the theoretical estimates to recent experimental investigation of the Adler amplitudes by neutrino scattering.

In this paper, we develop a general framework to study meson photoproduction off nucleons in the chiral quark model. The s- and u-channel resonance contributions are expressed in terms of the Chew-Goldberger-Low-Nambu (CGLN) amplitudes. The kaon-photoproduction processes, γp→${\mathit{K}}^{+}$Λ, γp→${\mathit{K}}^{+}$${\mathrm{\Sigma }}^0$, and γp→${\mathit{K}}^0$${\mathrm{\Sigma }}^{+}$, are calculated. The initial results show that the quark model provides a much improved description of the reaction mechanism for kaon photoproduction off the nucleon with less parameters than the traditional phenomenological approaches.

The kaon photoproduction process γp→${\mathit{K}}^{+}$Λ is studied in a momentum-projected color dielectric quark model. In contrast to phenomenological analyses, only a few Feynman diagrams are used, yet the diagrams include form factors derived from quark wave functions. The predicted cross sections are close to experiment. The unitarization of the Born diagrams, which effectively includes the KΛ final-state interaction, is found to be important in the prediction of the Λ polarization. It is concluded that only a small number of graphs is needed to explain the basic physics as long as a realistic model of the baryon structure and final-state interactions are included.