Results of a new series of experiments on the study of production cross sections and decay properties of the isotopes of element 115 in the reaction ${}^{243}\mathrm{Am}+{}^{48}\mathrm{Ca}$ are presented. Twenty-one new decay chains originating from ${}^{288}115$ were established as the product of the $3n$-evaporation channel by measuring the excitation function at three excitation energies of the compound nucleus ${}^{291}115$. The decay properties of all newly observed nuclei are in full agreement with those we measured in 2003. At the lowest excitation energy $E^{*}=33\mathrm{MeV}$, for the first time we registered the product of the $2n$-evaporation channel, ${}^{289}115$, which was also observed previously in the reaction ${}^{249}\mathrm{Bk}+{}^{48}\mathrm{Ca}$ as the daughter nucleus of the decay of ${}^{293}117$. The maximum cross section for the production of ${}^{288}115$ is found to be 8.5 pb at $E^{*}\approx 36\mathrm{MeV}$.

A new Monte Carlo model of jet quenching in nuclear collisions, CUJET1.0, is applied to predict the jet flavor dependence of the nuclear modification factor for fragments $f=\pi ,D,B,e^{-}$ from quenched jet flavors $g,u,c,b$ in central collisions at RHIC and LHC. The nuclear modification factors for different flavors are predicted to exhibit a novel level crossing pattern over a transverse momentum range $5<p_T<100\mathrm{GeV}$ which can test jet-medium dynamics in quark gluon plasmas.

The quantitative consistency of nucleon transfer reactions as a probe of the occupancy of valence orbits in nuclei is tested. Neutron-adding, neutron-removal, and proton-adding transfer reactions were measured on the four stable even Ni isotopes, with particular attention to the cross section determinations. The data were analyzed consistently in terms of the distorted wave Born approximation to yield spectroscopic factors. Valence-orbit occupancies were extracted, utilizing the Macfarlane-French sum rules. The deduced occupancies are consistent with the changing number of valence neutrons, as are the vacancies for protons, both at the level of $<5\%$. While there has been some debate regarding the true “observability” of spectroscopic factors, the present results indicate that empirically they yield self-consistent results.

The extension of Green’s functions techniques to the complex energy plane provides access to fully dressed quasiparticle properties from a microscopic perspective. Using self-consistent ladder self-energies, we find both spectra and lifetimes of such quasiparticles in nuclear matter. With a consistent choice of the group velocity, the nucleon mean-free path can be computed. Our results indicate that, for energies above 50 MeV at densities close to saturation, a nucleon has a mean-free path of 4 to 5 fm.

Penning trap mass measurements of short-lived nuclides have been performed for the first time with highly charged ions, using the TITAN facility at TRIUMF. Compared to singly charged ions, this provides an improvement in experimental precision that scales with the charge state $q$. Neutron-deficient Rb isotopes have been charge bred in an electron beam ion trap to $q=8-12+$ prior to injection into the Penning trap. In combination with the Ramsey excitation scheme, this unique setup creating low energy, highly charged ions at a radioactive beam facility opens the door to unrivaled precision with gains of 1–2 orders of magnitude. The method is particularly suited for short-lived nuclides such as the superallowed $\beta$ emitter ${}^{74}\mathrm{Rb}$ ($T_{1/2}=65\mathrm{ms}$). The determination of its atomic mass and an improved $Q_{EC}$ value are presented.

The ${}^2\mathrm{H}(e,e^{\prime }p)n$ cross section at a momentum transfer of $3.5(\mathrm{GeV}/c{)}^2$ was measured over a kinematical range that made it possible to study this reaction for a set of fixed missing momenta as a function of the neutron recoil angle ${\theta }_{\mathrm{nq}}$ and to extract missing momentum distributions for fixed values of ${\theta }_{\mathrm{nq}}$ up to $0.55\mathrm{GeV}/c$. In the region of $35°\le {\theta }_{\mathrm{nq}}\le 45°$ recent calculations, which predict that final-state interactions are small, agree reasonably well with the experimental data. Therefore, these experimental reduced cross sections provide direct access to the high momentum component of the deuteron momentum distribution in exclusive deuteron electrodisintegration.

Flow coefficients $v_n$ for $n=2$, 3, 4, characterizing the anisotropic collective flow in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$, are measured relative to event planes ${\Psi }_n$, determined at large rapidity. We report $v_n$ as a function of transverse momentum and collision centrality, and study the correlations among the event planes of different order $n$. The $v_n$ are well described by hydrodynamic models which employ a Glauber Monte Carlo initial state geometry with fluctuations, providing additional constraining power on the interplay between initial conditions and the effects of viscosity as the system evolves. This new constraint can serve to improve the precision of the extracted shear viscosity to entropy density ratio $\eta /s$.

We have measured the ${}^{149}\mathrm{Sm}(n,\alpha ){}^{146}\mathrm{Nd}$ cross section at 4.5, 5.0, 5.5, 6.0, and 6.5 MeV. Measurements were performed at the 4.5 MV Van de Graaff accelerator of Peking University with monoenergetic neutrons produced via the ${}^2\mathrm{H}(d,n){}^3\mathrm{He}$ reaction using a deuterium gas target. Alpha particles were detected with a double-section gridded ionization chamber having two back-to-back ${}^{149}\mathrm{Sm}_2{\mathrm{O}}_3$ samples attached to the common cathode. Absolute neutron flux was measured using a small ${}^{238}\mathrm{U}$ fission chamber and monitored by a ${\mathrm{BF}}_3$ long counter. These are the first reported cross sections for this reaction at these energies, except at 6.0 eV, where our new data are in good agreement with our earlier result. The present results help to much better constrain the ${}^{149}\mathrm{Sm}(n,\alpha ){}^{146}\mathrm{Nd}$ cross section in a region where its energy dependence is changing fairly rapidly and there are large differences between evaluated nuclear data libraries.

We report a precision measurement of the deuteron tensor analyzing powers $T_{20}$ and $T_{21}$ at the MIT-Bates Linear Accelerator Center. Data were collected simultaneously over a momentum transfer range $Q=2.15–4.50{\mathrm{fm}}^{-1}$ with the Bates Large Acceptance Spectrometer Toroid using a highly polarized deuterium internal gas target. The data are in excellent agreement with calculations in a framework of effective field theory. The deuteron charge monopole and quadrupole form factors $G_C$ and $G_Q$ were separated with improved precision, and the location of the first node of $G_C$ was confirmed at $Q=4.19\pm 0.05{\mathrm{fm}}^{-1}$. The new data provide a strong constraint on theoretical models in a momentum transfer range covering the minimum of $T_{20}$ and the first node of $G_C$.

The intense, nearly monoenergetic, 100% polarized $\overrightarrow{\gamma }$-ray beams available at the $\mathrm{HI}\overrightarrow{\gamma }\mathrm{S}$ facility, along with the realization that the $E1\mathrm{\text{−}}E2$ interference term that appears in the Compton scattering polarization observable has opposite signs in the forward and backward angles, make it possible to obtain an order-of-magnitude improvement in the determination of the parameters of the isovector giant quadrupole resonance (IVGQR). Accurate IVGQR parameters will lead to a more detailed knowledge of the symmetry energy in the nuclear equation of state which is important for understanding nuclear matter under extreme conditions such as those present in neutron stars. Our new method is demonstrated for the case of ${}^{209}\mathrm{Bi}$.

Collinear-laser spectroscopy with the bunched-beams technique was used for the study of neutron deficient Rb isotopes, out to ${}^{74}\mathrm{Rb}$ ($N=Z=37$) at TRIUMF. The measured hyperfine coupling constants of ${}^{76,78m}\mathrm{Rb}$ were in agreement with literature values. The nuclear spin of ${}^{75}\mathrm{Rb}$ was confirmed to be $I=3/2$, and its hyperfine coupling constants were measured for the first time. The mean-square charge radius of ${}^{74}\mathrm{Rb}$ was determined for the first time. This result has improved the isospin symmetry breaking correction term used to calculate the $\mathcal{F}t$ value, with implications for tests of the unitarity of the Cabibbo-Kobayashi-Maskawa matrix.

We report the observation of two-neutrino double-beta decay in ${}^{136}\mathrm{Xe}$ with $T_{1/2}=2.11\pm 0.04(\mathrm{stat})\pm 0.21(\mathrm{syst})\times {10}^{21}\mathrm{yr}$. This second-order process, predicted by the standard model, has been observed for several nuclei but not for ${}^{136}\mathrm{Xe}$. The observed decay rate provides new input to matrix element calculations and to the search for the more interesting neutrinoless double-beta decay, the most sensitive probe for the existence of Majorana particles and the measurement of the neutrino mass scale.

A new technique to measure $(p,n)$ charge-exchange reactions in inverse kinematics at intermediate energies on unstable isotopes was successfully developed and used to study the ${}^{56}\mathrm{Ni}(p,n)$ reaction at $110\mathrm{MeV}/\mathrm{u}$. Gamow-Teller transition strengths from ${}^{56}\mathrm{Ni}$ leading to ${}^{56}\mathrm{Cu}$ were obtained and compared with shell-model predictions in the $pf$ shell using the KB3G and GXPF1A interactions. The calculations with the GXPF1A interaction reproduce the experimental strength distribution much better than the calculations that employed the KB3G interaction, indicating deficiencies in the spin-orbit and proton-neutron residual potentials for the latter. The results are important for improving the description of electron-capture rates on nuclei in the iron region, which are important for modeling the late evolution of core-collapse and thermonuclear supernovae.

The fusion excitation functions for radioactive ${}^{132}\mathrm{Sn}+{}^{58}\mathrm{Ni}$ and stable ${}^{130}\mathrm{Te}+{}^{58,64}\mathrm{Ni}$ were measured at energies near the Coulomb barrier. The coupling of transfer channels in heavy-ion fusion was examined through a comparison of $\mathrm{Sn}+\mathrm{Ni}$ and $\mathrm{Te}+\mathrm{Ni}$ systems, which have large variations in the number of positive $Q$-value nucleon transfer channels. In contrast with previous experimental comparisons, where increased sub-barrier fusion cross sections were observed in systems with positive $Q$-value neutron transfer channels, the reduced excitation functions were equivalent for the different $\mathrm{Sn}+\mathrm{Ni}$ and $\mathrm{Te}+\mathrm{Ni}$ systems. The present results suggest a dramatically different influence of positive $Q$-value transfer channels on the fusion process for the $\mathrm{Sn}+\mathrm{Ni}$ and $\mathrm{Te}+\mathrm{Ni}$ systems.

A precision measurement of the $\gamma$ yields following the $\beta$ decay of ${}^{32}\mathrm{Cl}$ has determined its isobaric-analogue branch to be $({22.47}_{-0.18}^{+0.21})\%$. Since it is an almost pure-Fermi decay, we can also determine the amount of isospin-symmetry breaking in this superallowed transition. We find a very large value, ${\delta }_C=5.3(9)\%$, in agreement with a shell-model calculation. This result sets a benchmark for isospin-symmetry-breaking calculations and lends support for similarly calculated, yet smaller, corrections that are currently applied to $0^{+}\to 0^{+}$ transitions for tests of the standard model.

We present results from time-of-flight nuclear mass measurements at the National Superconducting Cyclotron Laboratory that are relevant for neutron star crust models. The masses of 16 neutron-rich nuclei in the scandium–nickel range were determined simultaneously, with the masses of ${}^{61}\mathrm{V}$, ${}^{63}\mathrm{Cr}$, ${}^{66}\mathrm{Mn}$, and ${}^{74}\mathrm{Ni}$ measured for the first time with mass excesses of $-30.510(890)\mathrm{MeV}$, $-35.280(650)\mathrm{MeV}$, $-36.900(790)\mathrm{MeV}$, and $-49.210(990)\mathrm{MeV}$, respectively. With these results the locations of the dominant electron capture heat sources in the outer crust of accreting neutron stars that exhibit super bursts are now experimentally constrained. We find the experimental $Q$ value for the ${}^{66}\mathrm{Fe}\to {}^{66}\mathrm{Mn}$ electron capture to be 2.1 MeV ($2.6\sigma$) smaller than predicted, resulting in the transition occurring significantly closer to the neutron star surface.

Back-to-back hadron pair yields in $d+\mathrm{Au}$ and $p+p$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$ were measured with the PHENIX detector at the Relativistic Heavy Ion Collider. Rapidity separated hadron pairs were detected with the trigger hadron at pseudorapidity $|\eta |<0.35$ and the associated hadron at forward rapidity (deuteron direction, $3.0<\eta <3.8$). Pairs were also detected with both hadrons measured at forward rapidity; in this case, the yield of back-to-back hadron pairs in $d+\mathrm{Au}$ collisions with small impact parameters is observed to be suppressed by a factor of 10 relative to $p+p$ collisions. The kinematics of these pairs is expected to probe partons in the Au nucleus with a low fraction $x$ of the nucleon momenta, where the gluon densities rise sharply. The observed suppression as a function of nuclear thickness, $p_T$, and $\eta$ points to cold nuclear matter effects arising at high parton densities.

A $\beta$-decaying high-spin isomer in ${}^{96}\mathrm{Cd}$, with a half-life $T_{1/2}={0.29}_{-0.10}^{+0.11}\mathrm{s}$, has been established in a stopped beam rare isotope spectroscopic investigations at GSI (RISING) experiment. The nuclei were produced using the fragmentation of a primary beam of ${}^{124}\mathrm{Xe}$ on a ${}^9\mathrm{Be}$ target. From the half-life and the observed $\gamma$ decays in the daughter nucleus, ${}^{96}\mathrm{Ag}$, we conclude that the $\beta$-decaying state is the long predicted ${16}^{+}$ “spin-gap” isomer. Shell-model calculations, using the Gross-Frenkel interaction and the $\pi \nu (p_{1/2},g_{9/2})$ model space, show that the isoscalar component of the neutron-proton interaction is essential to explain the origin of the isomer. Core excitations across the $N=Z=50$ gaps and the Gamow-Teller strength, $B(\mathrm{GT})$ distributions have been studied via large-scale shell-model calculations using the $\pi \nu (g,d,s)$ model space to compare with the experimental $B(\mathrm{GT})$ value obtained from the half-life of the isomer.

The results of two relativistic models with different descriptions of the final-state interactions are compared with the MiniBooNE data of charged-current quasielastic cross sections. The relativistic mean field model uses the same potential for the bound and ejected nucleon wave functions. In the relativistic Green’s function model, the final-state interactions are described in the inclusive scattering consistently with the exclusive scattering using the same complex optical potential. The relativistic Green’s function results describe the experimental data for total cross sections without the need to modify the nucleon axial mass.

The theory of octupolar-excitation ion-cyclotron-resonance mass spectrometry is presented which predicts an increase of up to several orders of magnitude in resolving power under certain conditions. The new method has been applied for a direct Penning-trap mass-ratio determination of the ${}^{164}\mathrm{Er}\mathrm{\text{−}}{}^{164}\mathrm{Dy}$ mass doublet. ${}^{164}\mathrm{Er}$ is a candidate for the search for neutrinoless double-electron capture. However, the measured $Q_{ϵϵ}$ value of 25.07(12) keV results in a half-life of ${10}^{30}$ years for a 1 eV Majorana-neutrino mass.