The predicted and experimental properties of the new doubly magic nuclei ${}^{22}\mathrm{O}$ and ${}^{24}\mathrm{O}$ are discussed. These together with previous observations lead to a new rule for magic numbers: if there is an oscillator magic number (2, 8, 20, or 40) for one kind of nucleon, then the other kind of nucleon has a magic number for the filling of every possible (n, l, j) value.

Recent studies have provided new experimental information on the very neutron-rich nucleus ${}^{135}\mathrm{Sb}$. We have performed a shell-model calculation for this nucleus by using a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential. This gives a very good description of the observed properties of ${}^{135}\mathrm{Sb}$. We show that the anomalously low position of the first excited state, $J^{\pi }=5/2^{+}$, and the strongly hindered $M1$ transition to the ground state have their origin in the effective neutron-proton interaction.

The polarized longitudinal-transverse structure function ${\sigma }_{{\mathit{LT}}^{\text{'}}}$ measures the interference between real and imaginary amplitudes in pion electroproduction and can be used to probe the coupling between resonant and nonresonant processes. We report new measurements of ${\sigma }_{{\mathit{LT}}^{\text{'}}}$ in the $N(1440){\frac{1}{2}}^{+}$ (Roper) resonance region at $Q^2=0.40$ and $0.65{\text{GeV}}^2$ for both the ${\pi }^{0}p$ and ${\pi }^{+}n$ channels. The experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at a beam energy of 1.515 GeV. Complete angular distributions were obtained and are compared to recent phenomenological models. The ${\sigma }_{{\mathit{LT}}^{\text{'}}}({\pi }^{+}n)$ channel shows a large sensitivity to the Roper-resonance multipoles $M_{1-}$ and $S_{1-}$ and provides new constraints on models of resonance formation.

Half-lives of the decays of spherical nuclei away from the proton drip line by proton emissions are estimated theoretically. The quantum mechanical tunneling probability is calculated within the WKB approximation. Microscopic proton-nucleus interaction potentials are obtained by single folding the densities of the daughter nuclei with M3Y effective interaction supplemented by a zero-range pseudopotential for exchange along with the density dependence. Parameters of the density dependence are obtained from the nuclear matter calculations. Spherical charge distributions are used for Coulomb interaction potentials. These calculations provide reasonable estimates for the observed proton-radioactivity lifetimes of proton-rich nuclei for proton emissions from 26 ground and isomeric states of spherical proton emitters.

The renormalization of the chiral nuclear interactions is studied. In leading order, the cutoff dependence is related to the singular tensor interaction of the one-pion exchange potential. In S waves and in higher partial waves where the tensor force is repulsive this cutoff dependence can be absorbed by counterterms expected at that order. In the other partial waves additional contact interactions are necessary. The implications of this finding for the effective field theory program in nuclear physics are discussed.

The study of the hyperfine (hfs) anomaly in neutron rich nuclei can give a very specific and unique way to study the neutron distribution and the clustering structure. We study the sensitivity of the hfs anomaly to the clustering effects in the ${}^9\mathrm{Be}$ isotope using two different nuclear wave functions obtained in the three-cluster ($\alpha +\alpha +n$) model. The results are compared to those obtained for ${}^{9,11}\mathrm{Be}$ in a two-body core+neutron model to examine whether the hfs anomaly is sensitive to a halo structure in ${}^{11}\mathrm{Be}$.

We have measured the lifetime of the $T=0,J^{\pi }=3_1^{+}$ state of ${}^{58}\mathrm{Cu}$ at 444 keV. The excited states in ${}^{58}\mathrm{Cu}$ were populated with the ${}^{58}\mathrm{Ni}$($p,n\gamma$) reaction at the SUNY at Stony Brook TANDEM-LINAC facility. A lifetime τ = 0.468 ± 0.085 ns was found with the delayed γ-radiofrequency coincidence method with respect to the pulsed LINAC beam. It corresponds to an isoscalar $E2$ transition strength of 7.6 ± 1.4 W.u. to the $T=0,J^{\pi }=1_1^{+}$ ground state. The result agrees with the interpretation of the $3_1^{+}$ state as a collective quadrupole excitation of the $1_1^{+}$ ground state of ${}^{58}\mathrm{Cu}$.

The structure of the deformed, doubly odd nuclide ${}^{180}\mathrm{Re}$ has been studied by γ-ray and conversion-electron spectroscopy using the ${}^{174}\mathrm{Yb}$(${}^{11}\mathrm{B}$,5n) reaction with a pulsed 71 MeV beam of ${}^{11}\mathrm{B}$ ions. Several of the previously known intrinsic states have been given revised spin and parity assignments. Rotational bands are observed with $K^{\pi }=(4^{+}),(5^{-}),(7^{+}),8^{+},9^{-},{13}^{+},{14}^{-},{15}^{-},{16}^{+},{21}^{-}$, and $({22}^{+}$). Among these, a four-quasiparticle t band is identified, which is already energetically favored at its bandhead compared to the corresponding two-quasiparticle band; and two six-quasiparticle bands are identified and associated with a $\tau =13$ μs isomer. The observed structures, including g factors and alignments, are interpreted with the aid of Nilsson-plus-BCS calculations and configuration-constrained potential energy surface calculations. Reduced-hindrance values are obtained for K-forbidden transitions, illustrating the important role of the K quantum number for near-yrast isomers.

We study the J-pairing Hamiltonian and find that the sum of eigenvalues of spin-I states equals the sum of the norm matrix elements within the pair basis for four identical particles such as four fermions in a single-j shell or four bosons with spin l. We relate the number of states to sum rules of nine-j coefficients. We obtained sum rules for nine-j coefficients $\langle (\mathit{jj})J,(\mathit{jj})K:I|(\mathit{jj})J,(\mathit{jj})K:I\rangle$ and $\langle (\mathit{ll})J,(\mathit{ll})K:I|(\mathit{ll})J,(\mathit{ll})K:I\rangle$ summing over (1) even J and even K, (2) even J and odd K, (3) odd J and odd K, and (4) both even and odd values for J and K, where j is a half integer and l is an integer.

Gamma-ray singles spectra of extremely pure (chemically and isotopically) samples of ${}^{255}\mathrm{Fm}$, with strengths of $~1$ mCi, have been measured with a high-resolution 2-cm${}^2\times$10-mm germanium LEPS detector and with a 25% Ge spectrometer. Gamma rays with intensities as low as $1.0\times {10}^{-6}$% per ${}^{255}\mathrm{Fm}$ α decay have been identified. The electron spectrum of a mass-separated ${}^{251}\mathrm{Es}$ source was measured with a cooled Si(Li) electron spectrometer. The spectrum provided the conversion coefficients of low-energy transitions in ${}^{251}\mathrm{Cf}$ and thereby their multipolarities. The present measurements confirm the previous assignments of single-particle states in ${}^{251}\mathrm{Cf}$. These include $1/2^{+}$[620], 0.0 keV; $7/2^{+}$[613], 106.30 keV; $3/2^{+}$[622], 177.59 keV; $11/2^{-}$[725], 370.47 keV; $9/2^{-}$[734], 433.91 keV; $5/2^{+}$[622], 543.98 keV; $1/2^{-}$[750], 632.0 keV; $9/2^{+}$[615], 683 keV; and $9/2^{+}$[604], 974.0 keV. A vibrational band was identified in previous studies at 981.4 keV and given an assignment of $\{7/2^{+}[613]\otimes 2^{-}\}3/2^{-}$. Three new vibrational bands are identified in the present work at 942.5, 1086.5, and 1250.0 keV with tentative assignments $\{7/2^{+}[613]\otimes 1^{-}\}5/2^{-},\{7/2^{+}[613]\otimes 1^{-}\}9/2^{-}$, and $\{7/2^{+}[613]\otimes 0^{+}\}7/2^{+}$, respectively. A level was identified at 1185.5 keV with spin of 5/2 or 7/2 but it was not given any configuration assignment. Another level was identified at 1077.5 keV and given a spin of 9/2. Again, no configuration could be assigned to this level.

Excited states of ${}^{90}\mathrm{Nb}$ were investigated via prompt and delayed γ decays and the recoil-isomer tagging technique. The level scheme of ${}^{90}\mathrm{Nb}$ has been extended up to $J=19\hslash$ and $E_x=8.4$ MeV. Half-lives of the ${11}^{-}$ and $17/2^{-}$ isomeric levels in ${}^{90,91}\mathrm{Nb}$ were measured to be $0.47\pm 0.01$ and $3.3\pm 0.4$ μs, respectively. The results are compared with the predictions of large-basis shell model calculations. The effects of truncation of the valence model space on the calculated results are discussed.

A linked cluster expansion suitable for the treatment of ground-state properties of complex nuclei, as well as of various particle-nucleus scattering processes, has been used to calculate the ground-state energy, density, and momentum distribution of ${}^{16}\mathrm{O}$ and ${}^{40}\mathrm{Ca}$ in terms of realistic interactions. First, a benchmark calculation for the ground-state energy is performed with the truncated $V{8}^{\text{'}}$ potential and consisting of the comparison of our results with the ones obtained by the Fermi hypernetted chain approach, adopting in both cases the same mean-field wave functions and the same correlation functions. The results exhibited a nice agreement between the two methods. Therefore the approach has been applied to the calculation of the ground-state energy, density, and momentum distributions of ${}^{16}\mathrm{O}$ and ${}^{40}\mathrm{Ca}$ by use of the full $V{8}^{\text{'}}$ potential, and again a satisfactory agreement was found with the results based on more advanced approaches in which higher-order cluster contributions are taken into account. It appears therefore that the cluster expansion approach can provide accurate approximations for various diagonal and nondiagonal density matrices, so that it could be used for a reliable evaluation of nuclear effects in various medium- and high-energy scattering processes off nuclear targets. The developed approach can be readily generalized to the treatment of Glauber-type final-state interaction effects in inclusive, semi-inclusive, and exclusive processes off nuclei at medium and high energies.

In this paper, we present new experimental data measured at $E_p=$ 29.9 MeV for the inclusive reactions ($p,\mathit{xp}$) and ($p,x\alpha$) on nucleus ${}^{56}\mathrm{Fe}$. We investigate the adequacy of the theoretical models in explaining the measured experimental data, and we determine the contributions of multistep direct and multistep compound processes in the formation of the cross-sections. We show that the traditional frameworks are valid for the description of the new experimental data, and our measurements agree with previous measurements for the ($p,\mathit{xp}$) and ($p,x\alpha$) reactions on the ${}^{54}\mathrm{Fe}$ nucleus. The only exception is within the energy region of $E_p=$ 15 and 25 MeV for both reactions, where the cross-section for the ${}^{56}\mathrm{Fe}$ nucleus is smaller than the cross-section for the ${}^{54}\mathrm{Fe}$ nucleus.

We have investigated the population of nuclei formed in binary reactions involving ${}^7\mathrm{Li}$ beams on targets of ${}^{160}\mathrm{Gd}$ and ${}^{184}\mathrm{W}$. The ${}^7\mathrm{Li}$+${}^{184}\mathrm{W}$ data were taken in the first experiment to use the LIBERACE Ge array in combination with the STARS Si $\Delta E\text{−}E$ telescope system at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. By using the Wilczyński binary transfer model, in combination with a standard evaporation model, we are able to reproduce the experimental results. This is a useful method for predicting the population of neutron-rich heavy nuclei formed in binary reactions involving beams of weakly bound nuclei and will be of use in future spectroscopic studies.

The effects of strong-color electric fields on the baryon production at RHIC are studied in the framework of the HIJING/B$\overline{\text{B}}$ (v2.0) model. The particle species dependence of nuclear modification factors are analyzed for Au+Au collisions at 200A GeV. A doubling of the string tension leading to a modification of the strangeness suppression according to the Schwinger mechanism is shown to provide an alternative explanation to coalescence models for the interpretation of the observed baryon and meson production at moderate $p_T$ and results in a predicted enhancement in the (multi)strange (anti)hyperon production.

We report on a high-statistics search for the $\Theta (1540){}^{+}$ resonance in ${\Sigma }^{-}$-nucleus collisions at 340 GeV/c. No evidence for this resonance was found in our data sample which contains 13 million $K_s^0\to {\pi }^{+}{\pi }^{-}$ decays above background. For the decay channel ${\Theta }^{+}\to K_s^{0}p$ and the kinematic range $x_F>$ 0.05, we find the production cross section to be $\mathrm{BR}({\Theta }^{+}\to K_s^{0}p){\sigma }_0<1.8$ μb per nucleon at 99% C.L.

We present experimental results of nuclear-charge changing interactions for 158A-GeV ultrarelativistic In ions in Si, Ge, Sn, W, and Pb targets. Calculations based on the abrasion-ablation model for hadronic interaction and the RELDIS model for electromagnetic dissociation are compared to the data.

We study the pion distributions in jets produced in heavy-ion collisions in association with trigger particles restricted to definite momentum ranges. We determine the centrality dependence of the associated particle distributions for both d + Au and Au + Au collisions in the recombination model. The central-to-peripheral ratios show significant dependence on centrality for Au + Au collisions but negligible dependence for d + Au collisions. The results are in agreement with the qualitative features of the data.