The ${}^{19}\mathrm{F}$ nucleus has been studied extensively. However, there have been no comprehensive experimental studies of ${}^{18}\mathrm{F}$$+n$ single-particle components in ${}^{19}\mathrm{F}$, and no measure of neutron vacancies in the ${}^{18}\mathrm{F}$ ground state, as such experiments require a (radioactive) ${}^{18}\mathrm{F}$ target or beam. We have used the ${}^2\mathrm{H}$(${}^{18}\mathrm{F}$,$p$)${}^{19}\mathrm{F}$ reaction to selectively populate states in ${}^{19}\mathrm{F}$ that are of ${}^{18}\mathrm{F}$$+n$ character. The 108.5-MeV radioactive ${}^{18}\mathrm{F}$${}^{+9}$ beam was provided by the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Proton-recoil coincidence data were taken for both α-decaying and particle-stable final states. Angular distributions and spectroscopic factors were measured for nine proton groups, corresponding to 13 states in ${}^{19}\mathrm{F}$. The results are compared to shell model calculations.

The nuclides ${}^{92}\mathrm{Mo}$, ${}^{98}\mathrm{Mo}$, and ${}^{100}\mathrm{Mo}$ have been studied in photon-scattering experiments by using bremsstrahlung produced at an electron energy of 6 MeV at the ELBE accelerator of the Forschungszentrum Rossendorf and at electron energies from 3.2 to 3.8 MeV at the Dynamitron accelerator at the University of Stuttgart. Six dipole transitions in ${}^{98}\mathrm{Mo}$ and 19 in ${}^{100}\mathrm{Mo}$ were observed for the first time in the energy range from 2 to 4 MeV. The experimental results are compared with predictions of the shell model and with predictions of the quasiparticle random-phase approximation (QRPA) in a deformed basis. The latter show significant contributions of isovector-orbital and isovector-spin vibrations. The change of the magnetic dipole strength in the isotopic chain of the even-mass isotopes from ${}^{92}\mathrm{Mo}$ to ${}^{100}\mathrm{Mo}$ is discussed. The calculations within the QRPA are extrapolated to the particle-separation energies to estimate the possible influence of $M1$ strength on the stability of the nuclides against photodissociation in cosmic scenarios.

The high spin states of ${}^{143}\mathrm{Sm}$ have been studied by in-beam γ-spectroscopy following the reaction ${}^{130}\mathrm{Te}$(${}^{20}\mathrm{Ne}$,$7n$)${}^{143}\mathrm{Sm}$ at $E_{\mathrm{lab}}=137$ MeV, using a Clover detector array. More than 50 new gamma transitions have been placed above the previously known $J^{\pi }=23/2^{-}$, 30 ms isomer at 2795 keV. The level scheme of ${}^{143}\mathrm{Sm}$ has been extended up to 12 MeV and spin-parity assignments have been made to most of the newly proposed level. Theoretical calculation with the relativistic mean field approach using blocked BCS method, has been performed. A sequence of levels connected by $M1$ transitions have been observed at an excitation energy ∼8.6 MeV. The sequence appears to be a magnetic rotational band from systematics.

High-spin states in ${}^{174}\mathrm{W}$ (Z = 74) have been populated using the reaction ${}^{128}\mathrm{Te}$(${}^{50}\mathrm{Ti}$, 4n)${}^{174}\mathrm{W}$ at beam energies of 215 and 225 MeV. The Gammasphere array was used to detect the γ rays emitted by the evaporation residues. Four previously known collective band structures have been extended, and 16 new rotational sequences observed. Two are built upon isomeric states, one corresponding to a two-quasiparticle K = 8 isomer, the other to a four-quasiparticle K = 12 isomer, with the latter exhibiting strong K-violating $\Delta K=12$ decays to the ground state band. Nucleonic configurations for the two- and four-quasiparticle excitations are proposed, and Woods-Saxon cranking calculations are presented to understand the rotational structures. Decay mechanisms of multi-quasiparticle K isomers are discussed in terms of the prevalent phenomenological models, with special emphasis on γ-tunneling calculations. Surprisingly, the latter underpredict the decay hindrance for the K = 12 isomer by three orders of magnitude, unlike all other isomer decays in this mass region.

A pioneering experiment in Λ hypernuclear spectroscopy, undertaken at the Thomas Jefferson National Accelerator Facility (JLab), was recently reported. The experiment used the high precision, continuous electron beam at JLab, and a special arrangement of spectrometer magnets to measure the hypernuclear spectrum from C and ${}^7\mathrm{Li}$ targets using the $(e,e\text{'}{K}^{+})$ reaction. The ${}_{\Lambda }^{12}$B spectrum found in this investigation was previously published, but is reported here in more detail, with improved resolution. In addition, the results of a ${}_{\Lambda }^7$He spectrum also obtained in the experiment, are shown. This latter spectrum indicates the need for a more detailed few-body calculation of the hypernucleus and the reaction process. The success of the experiment demonstrates the potential of the $(e,e\text{'}{K}^{+})$ reaction for high resolution spectroscopy of hypernuclear spectra.

We carry out a systematic analysis of angular distribution measurements for selected ground-state to ground-state ($d,p$) and ($p,d$) neutron transfer reactions, including the calcium isotopes. We propose a consistent three-body model reaction methodology in which we constrain the transferred-neutron bound state and nucleon-target optical potential geometries using modern Hartree-Fock calculations. Our deduced neutron spectroscopic factors are found to be suppressed by $~30$% relative to independent-particle shell-model values, from ${}^{40}\mathrm{Ca}$ through ${}^{49}\mathrm{Ca}$. The other nuclei studied, ranging from B to Ti, show similar average suppressions with respect to large-basis shell-model expectations. Our results are consistent with deduced spectroscopic strengths for neutrons and protons from intermediate-energy nucleon knockout reactions and for protons from ($e,e^{\text{'}}p$) reactions on well-bound nuclei.

Within the framework of the constituent quark model, it is shown that the single-hadron fragmentation function of a parton can be expressed as a convolution of a shower diquark or triquark distribution function and quark recombination probability if the interference between amplitudes of quark recombination with different momenta is neglected. The recombination probability is determined by the hadron's wave function in the constituent quark model. The shower diquark or triquark distribution functions of a fragmenting jet are defined in terms of overlapping matrices of constituent quarks and parton field operators. They are similar in form to dihadron or trihadron fragmentation functions in terms of parton operator and hadron states. Extending the formalism to the field theory at finite temperature, we automatically derive contributions to the effective single-hadron fragmentation function from the recombination of shower and thermal constituent quarks. Such contributions involve single-quark or diquark distribution functions that in turn can be related to diquark or triquark distribution functions by means of sum rules. We also derive QCD evolution equations for quark distribution functions that in turn determine the evolution of the effective jet fragmentation functions in a thermal medium.

We present an effective-Lagrangian description for forward-angle $K^{+}\Lambda$ photoproduction from the proton, valid for photon lab energies from threshold up to $16\mathrm{GeV}$. The high-energy part of the amplitude is modeled in terms of t-channel Regge-trajectory exchange. The sensitivity of the calculated observables to the Regge-trajectory phase is investigated in detail. The model is extended toward the resonance region by adding a number of s-channel resonances to the t-channel background. The proposed hybrid “Regge-plus-resonance” (RPR) approach allows one to exploit the $p(\gamma ,K^{+})\Lambda$ data in their entirety, resulting in stronger constraints on both the background and resonance couplings. The high-energy data can be used to fix the background contributions, leaving the resonance couplings as the sole free parameters in the resonance region. We compare various implementations of the RPR model and explore to what extent the description of the data can be improved by introducing the “new” resonances $D_{13}(1900)$ and $P_{11}(1900)$. Despite its limited number of free parameters, the proposed RPR approach provides an efficient description of the $p(\gamma ,K^{+})\Lambda$ dynamics in and beyond the resonance region.

Exclusive reactions induced at high momentum transfer in few body systems provide us with an original way to study the production and propagation of hadrons in cold nuclear matter. In very well-defined parts of the phase space, the reaction amplitude develops a logarithmic singularity. It is on solid ground since it depends on only on-shell elementary amplitudes and on low momentum components of the nuclear wave function. This is the best window for studying the propagation of exotic configurations of hadrons such as the onset of color transparency. It may appear earlier in meson-photoproduction reactions, more particularly in the strange sector, than in the more classical quasi-elastic scattering of electrons. More generally, those reactions provide us with the best tool to determine the cross section of the scattering of various hadrons (strange particles, vector mesons) from the nucleon and to obtain the production of possible exotic states.

We suggest a simple phenomenological parametrization for the deuteron electromagnetic structure, and show that a good fit on all available data for the three deuteron electromagnetic form factors (in the range $Q^2\le 2$ GeV${}^2$) can be obtained with a small number of parameters. The present description of the deuteron is based on two components with different radii, one corresponding to two nucleons separated by $\simeq 2$ fm, and a standard isoscalar contribution, saturated by ω and ϕ mesons, only.

Inclusive electron scattering off the deuteron has been measured to extract the deuteron structure function $F_2$ with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The measurement covers the entire resonance region from the quasielastic peak up to the invariant mass of the final-state hadronic system $W\simeq 2.7$ GeV with four-momentum transfers $Q^2$ from $0.4$ to 6 (GeV/c)${}^2$. These data are complementary to previous measurements of the proton structure function $F_2$ and cover a similar two-dimensional region of $Q^2$ and Bjorken variable x. Determination of the deuteron $F_2$ over a large x interval including the quasielastic peak as a function of $Q^2$, together with the other world data, permit a direct evaluation of the structure function moments for the first time. By fitting the $Q^2$ evolution of these moments with an OPE-based twist expansion we have obtained a separation of the leading twist and higher twist terms. The observed $Q^2$ behavior of the higher twist contribution suggests a partial cancelation of different higher twists entering into the expansion with opposite signs. This cancelation, found also in the proton moments, is a manifestation of the “duality” phenomenon in the $F_2$ structure function.

New nuclear structure function data from Jefferson Lab covering the higher-x and lower-$Q^2$ regime make it possible to extract the higher-order $F_2$ moments for iron and deuterium at low four-momentum transfer squared $Q^2$. These moments allow for an experimental investigation of the nuclear momentum sum rule and a direct comparison of the nonsinglet nucleon moment with lattice QCD results.

Simple weak-coupling calculations for ${}^{23,25,27}\mathrm{Na}$ demonstrate that the lowest $J=1/2$ proton-hole state should lie near 5 MeV in ${}^{27}\mathrm{Na}$.

The low-energy np elastic-scattering parameters, including the zero-energy free-proton cross section ${\sigma }_0$, are determined with a substantially improved precision over previous values, using available np-scattering data below 3 MeV. The method includes a careful handling of a correlation between the singlet and triplet effective ranges which does not seem to have been previously treated. This correlation is responsible for a large systematic error in the singlet effective range and spoils a model-independent determination of the zero-energy triplet effective range. It is shown that improved cross section measurements between 20 and 600 keV (laboratory neutron energy) are needed to overcome the degrading effect of this correlation. The values obtained for the zero-energy cross section and the scattering lengths and effective ranges for the singlet and triplet are: ${\sigma }_0=20.4278(78)$ b, $a_t=5.4112(15)$ fm, $a_s=-23.7148(43)$ fm, $r_t=1.7436(19)$ fm, $r_s=2.750(18)$ fm (systematic error: −0.059 fm). The widely used measurement of the zero-energy free-proton elastic cross section from W. Dilg, Phys. Rev. C 11, 103 (1975), appears to be in error.

The binding energies of ${}^{29}\mathrm{Si}$, ${}^{33}\mathrm{S}$, and ${}^{36}\mathrm{Cl}$ have been measured with a relative uncertainty of $<0.59\times {10}^{-6}$ using a flat-crystal spectrometer. The unique features of these measurements are (1) nearly perfect crystals whose lattice spacing is known in meters, (2) a highly precise angle scale that is derived from first principles, and (3) a γ-ray measurement facility that is coupled to a high-flux reactor with near-core source capability. The binding energy is obtained by measuring all γ-rays in a cascade scheme connecting the capture and ground states. The measurements require the extension of precision flat-crystal diffraction techniques to the 5- to 6-MeV energy region, a significant precision measurement challenge. The binding energies determined from these γ-ray measurements are consistent with recent highly accurate atomic-mass measurements within a relative uncertainty of $4.3\times {10}^{-7}$. The γ-ray measurement uncertainties are the dominant contributors to the uncertainty of this consistency test. The measured γ-ray energies are in agreement with earlier precision γ-ray measurements.

The ground state and some low-lying excited states of oxygen isotopes ${}^{18}\mathrm{O}$–${}^{22}\mathrm{O}$ were simulated by means of auxiliary field diffusion Monte Carlo techniques. We performed the calculations by replacing the ${}^{16}\mathrm{O}$ core with a mean-field self-consistent potential we computed by using Skyrme interactions. The external neutrons were included in the Monte Carlo calculations, building a wave function with the orbitals computed in the self-consistent external potential. The shell considered was the 1$D_{5/2}$. The NN interactions employed included tensor, spin-orbit, and three-body forces. While absolute binding energies are too deep compared with those of experimental data, the differences between the energies for nearly all isotopes and excitations are in very good agreement with the experiments. The exception is the $4^{+}$ state of the ${}^{18}\mathrm{O}$ isotope, which shows a larger discrepancy.

Intermediate-mass fragments from the interaction of ${}^{27}\mathrm{Al}$, ${}^{59}\mathrm{Co}$, and ${}^{197}\mathrm{Au}$ with 200-MeV protons were measured in an angular range from ${20}^{°}$ to ${120}^{°}$ in the laboratory system. The fragments, ranging from isotopes of helium up to isotopes of carbon, were isotopically resolved. Double-differential cross sections, energy-differential cross sections, and total cross sections were extracted.

We estimate the rates for radiative transitions of the lightest scalar mesons $f_0(980)$ and $a_0(980)$ to the vector mesons ρ and ω. We argue that measurements of the radiative decays of those scalar mesons can provide important new information on their structure.