The high-spin states of the odd-odd nucleus ${}^{90}\mathrm{Nb}$ have been investigated with in-beam γ-spectroscopic techniques via the ${}^{76}\mathrm{Ge}$(${}^{19}\mathrm{F},5n){}^{90}\mathrm{Nb}$ reaction at a beam energy of 80 MeV. $\gamma \text{−}\gamma$ coincidences were measured using a $\gamma$-ray detector array. Twenty new $\gamma$ rays have been assigned to ${}^{90}\mathrm{Nb}$ and the level scheme has been extended up to an excitation energy of 8.095 MeV at spin $18\hslash$. The level structure of ${}^{90}\mathrm{Nb}$ at high spin states has been well reproduced using semiempirical shell-model calculations in the model space $\pi (1p_{1/2},0f_{5/2},0g_{9/2})\nu (0g_{9/2})$. The results show that the excitation of protons plays an important role in generating the high-spin states of ${}^{90}\mathrm{Nb}$.

The neutron-induced fission cross section of ${}^{237}\mathrm{U}$ target nuclide is calculated consistently with the ${}^{238}\mathrm{U}$(n,F), ${}^{238}\mathrm{U}$($n,2n$) and ${}^{238}\mathrm{U}$($n,3n$) reaction cross section up to $E_n~20$ MeV. The fission probability of the ${}^{238}\mathrm{U}$ nuclide, fissioning in ${}^{238}\mathrm{U}$($n,\mathit{nf}$) reaction is shown to be compatible with the surrogate ${}^{236}\mathrm{U}$($t,\mathit{pf}$) fission probability and ratio of fission probability $P_f$(${}^{238}\mathrm{U}$($d,d\text{'}f$))/$P_f$(${}^{236}\mathrm{U}$($d,d\text{'}f$)), data up to $E_n~14$ MeV. The ${}^{238}\mathrm{U}$($n,\mathit{nf}$) reaction contribution to the observed ${}^{238}U(n,F)$ cross section up to $E_n~9$ MeV is defined by the collective levels of the ${}^{238}\mathrm{U}$ at saddle deformations, lying within the pairing gap. The importance of the lowering of anomalous rotational $\gamma$-band $K^{\pi }=2^{+}$ band levels at saddle deformations is demonstrated. The excitation of the two-quasiparticle states at saddle deformations of the fissioniong ${}^{238}\mathrm{U}$ nuclide is evidenced.${}^{237}\mathrm{U}$ fission cross section is predicted up to $E_n~200$ MeV.

A systematic experimental study of inclusive pion double charge exchange in ${}^4\mathrm{He}$ has been undertaken. The reaction ${}^4\mathrm{He}$$({\pi }^{+},{\pi }^{-})4p$ was observed at incident energies of 120, 150, 180, 240, and 270 MeV; the ${}^4\mathrm{He}$$({\pi }^{-},{\pi }^{+})4n$ reaction was observed at incident energies of 180 and 240 MeV. At each incident energy, the doubly differential cross section was measured at three to five outgoing pion laboratory angles between ${25}^{°}$ and ${130}^{°}$. At each angle, cross sections were measured over the range of outgoing pion energies from 10 MeV to the kinematic limit for the reaction in which the final state consists of the oppositely charged pion plus four free nucleons. The spectra of outgoing pions are strikingly different from those observed for the inclusive double charge exchange reaction in heavier nuclei but resemble those observed in the $({\pi }^{-},{\pi }^{+})$ reaction in ${}^3\mathrm{He}$. The forward-angle spectra in the ${}^3\mathrm{He}$ and ${}^4\mathrm{He}$ reactions exhibit a prominent peak at high outgoing pion energies. Interpretation of the peaks in ${}^3\mathrm{He}$ (${}^4\mathrm{He}$) as a three-nucleon (four-nucleon) resonance is ruled out by kinematic analysis. The results of a calculation, wherein the double charge exchange reaction is assumed to proceed as two sequential single charge exchange interactions, suggest that the high-energy peak is naturally explained by this double scattering mechanism. Nonstatic treatment of the $\pi N$ interactions and the inclusion of nuclear binding effects appear to be important in reproducing the shape of the energy spectra at forward angles.

We study the hadron spectra in nearly central $A+A$ collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) in a broad transverse momentum range. We cover the low-$p_T$ spectra using longitudinally boost-invariant hydrodynamics with initial energy and net-baryon number densities from the perturbative QCD (pQCD)+saturation model. Buildup of the transverse flow and sensitivity of the spectra to a single decoupling temperature $T_{\mathrm{dec}}$ are studied. Comparison with RHIC data at $\sqrt{s_{\mathit{NN}}}=130$ and 200 GeV suggests a rather high value $T_{\mathrm{dec}}=150$ MeV. The high-$p_T$ spectra are computed using factorized pQCD cross sections, nuclear parton distributions, fragmentation functions, and describing partonic energy loss in the quark-gluon plasma by quenching weights. Overall normalization is fixed on the basis of $p+\overline{p}(p)$ data and the strength of energy loss is determined from RHIC Au+Au data. Uncertainties are discussed. With constraints from RHIC data, we predict the $p_T$ spectra of hadrons in 5% most central Pb+Pb collisions at the LHC energy $\sqrt{s_{\mathit{NN}}}=5500$ GeV. Because of the closed framework for primary production, we can also predict the net-baryon number at midrapidity, as well as the strength of partonic energy losses at the LHC. Both at the LHC and RHIC, we recognize a rather narrow crossover region in the $p_T$ spectra, where the hydrodynamic and pQCD fragmentation components become of equal size. We argue that in this crossover region the two contributions are to a good approximation mutually independent. In particular, our results suggest a wider $p_T$ region of applicability for hydrodynamical models at the LHC than at RHIC.

The in-medium mass of a ${\Theta }^{+},m_{{\Theta }^{+}}^{*}$, in cold symmetric nuclear matter is calculated by use of the quark-meson coupling models. The ${\Theta }^{+}$ is treated as an MIT bag with a quark content $\mathit{uudd}\overline{s}$. The bag parameters for a free ${\Theta }^{+}$ are fixed to reproduce the observed mass of the ${\Theta }^{+}$. In doing so, we use three different values of the s-quark mass as the mass of the s quark is not well known. As usual, the strengths of the u- and d-quark couplings to σ- and ω-meson fields are determined to fit the nuclear saturation properties. However, the coupling constant $g_{\sigma }^s$ between the s quark and the σ meson cannot be fixed from the saturation properties, and thus we treat $g_{\sigma }^s$ as a free parameter and investigate how $m_{{\Theta }^{+}}^{*}$ depends on $g_{\sigma }^s$. We find that $m_{{\Theta }^{+}}^{*}$ depends significantly on the value of $g_{\sigma }^s$ but not on the mass of the s quark. Chemical potentials of the ${\Theta }^{+}$ and the $K+N$ system are calculated to discuss the decay of a ${\Theta }^{+}$ in nuclear matter. We calculate the effective mass of a kaon in nuclear matter in two ways: by using the optical potential of $K^{-}$ in matter and by using a quark model. By comparing the effective masses of K calculated from these two methods, we find that the magnitude of the real part of the optical potential that is consistent with the quark model is about 100 MeV. In that case, we find $g_{\sigma K}\approx 2$.

We calculate the Schiff moment of the nucleus ${}^{199}\mathrm{Hg}$, created by πNN vertices that are odd under parity (P) and time-reversal (T). Our approach, formulated in diagrammatic perturbation theory with important core-polarization diagrams summed to all orders, gives a close approximation to the expectation value of the Schiff operator in the odd-A Hartree-Fock-Bogoliubov ground state generated by a Skyrme interaction and a weak P- and T-odd pion-exchange potential. To assess the uncertainty in the results, we carry out the calculation with several Skyrme interactions, the quality of which we test by checking predictions for the isoscalar-$E1$ strength distribution in ${}^{208}\mathrm{Pb}$, and estimate most of the important diagrams we omit.

Φ measures of Bose-Einstein correlations are studied for four different pion multiplicity distributions. It is found that Φ measures depend strongly on the multiplicity distribution if the phase space density becomes large. To exclude the effects of the multiplicity fluctuations, Φ measures for fixed multiplicities should be calculated. The effects of multiplicity fluctuation on the ${\Phi }^{*}$ measure are also discussed.

The ${}^{15}\mathrm{O}$($\alpha ,\gamma$)${}^{19}\mathrm{Ne}$ reaction is one of the most important breakout reactions for the hot CNO cycles. However, the relevant states in ${}^{19}\mathrm{Ne}$ at excitation energies of 4–5 MeV have not been well studied. The lifetimes of these states are not known and are only constrained by experimental upper and lower limits. In particular, accurate knowledge of the γ- and α-decay widths of the 4.03-MeV state of ${}^{19}\mathrm{Ne}$ is important, since the resonance strength of this level dominates the reaction rate for the astrophysically relevant temperatures $T_9<0.6$. In this work, we employed an improved Doppler-shifted attenuation method to obtain lifetime values of this and other states via ${}^{17}\mathrm{O}$(${}^3\mathrm{He}$, $n\text{−}\gamma$)${}^{19}\mathrm{Ne}$. For the 4.03-MeV state, the measured excitation energy is $4034.5\pm 0.8$ keV and the mean lifetime, measured here for the first time, is ${13}_{-6}^{+9}$ fs at the confidence level of $1\sigma$ and ${13}_{-9}^{+16}$ fs at the confidence level of $2\sigma$. This result is in excellent agreement with the 9-fs prediction by Langanke, Wiescher, Fowler, and Görres.

A one-boson-exchange model for the hyperon-nucleon ($\Lambda N,\Sigma N$) interaction is presented. The model incorporates the standard one boson exchanges of the lowest pseudoscalar and vector meson multiplets with coupling constants fixed by SU(6) flavor symmetry relations. As the main new feature of the model, the contributions in the scalar-isoscalar (σ) and vector-isovector (ρ) exchange channels are now constrained by a microscopic model of correlated $\pi \pi$ and $K\overline{K}$ exchange. Additional short-ranged ingredients of the model in the scalar-isovector ($a_0$) and scalar-isospin-1/2 (κ) channels are likewise viewed as arising from meson-meson correlations but are treated phenomenologically. With this model a satisfactory reproduction of the available hyperon-nucleon data can be achieved.

Large-scale fission barrier calculations have been performed in the framework of the Skyrme-Hartree-Fock model. Our Hartree-Fock-Bogoliubov calculations restore broken symmetries such as translational invariance, particle-number conservation, parity, and, in a more approximate way, rotational invariance. Axial symmetry is imposed, but reflection asymmetry is allowed. The energy surface properties are analyzed with the flooding method. A large set of Skyrme interactions, which were fitted to all known masses under different specific constraints, is used to study the main effects influencing the energy surface and the barrier heights. The principal interaction used in the comparison with experimental barriers is BSk8, the force on which the HFB-8 mass table is based. We found that for nuclei with $92\le Z\le 98$ the agreement of our calculations with experimental data is excellent; the rms deviation on the primary barriers is 0.722 MeV. For lighter nuclei, however, the calculated primary barriers are always too high because of the existence of a third barrier at very high deformations. However, our calculated superheavy barriers appear to be too low, although they are consistent with previous calculations.

We had previously used techniques involving isospin to count the number of states for three identical fermions in a single j shell with total angular momentum $I=j$. We generalize this to all I, but the main thrust of this work is to consider now a four-fermion system. As before, one evaluates the eigenvalues of the Hamiltonian ${\sum }_{i<j}[a+bt(i)·t(j)]$ from both an isospin point of view and an angular momentum point of view. In the four-particle case, we get a more limited result than in the three-particle case, namely the number of $T=0$ states minus twice the number of $T=2$ states, all of a given angular momentum I.

Neutron-rich Ca and Ni nuclei have been studied in a spherical relativistic mean-field formalism in coordinate space. A δ interaction has been adopted to treat the pairing correlations for the neutrons. Odd nuclei have been treated in the blocking approximation. The effect of the positive-energy continuum and the role of pairing in the stability of nuclei have been investigated by use of the resonant-BCS approach. In Ca isotopes, $N=50$ is no longer a magic number, whereas in Ni nuclei, a new magic number emerges at $N=70$. There is a remarkable difference in the relative positions of the drip lines for odd and even isotopes. In Ca isotopes, the last bound even and odd nuclei are found to be ${}^{72}\mathrm{Ca}$ and ${}^{59}\mathrm{Ca}$, respectively. In Ni isotopes, the corresponding nuclei are ${}^{98}\mathrm{Ni}$ and ${}^{97}\mathrm{Ni}$, respectively. The origin of this difference in relative positions of the drip line in even and odd isotopes in the two chains is traced to the difference in the single-particle level structures and consequent modification in the magic numbers in the two elements. Pairing interaction is seen to play a major role. The effect of the width of the resonance states on pairing has also been investigated.

A theory for electron scattering from Borromean two-neutron halo nuclei with full inclusion of final state interactions is developed. The halo nucleus is described as a three-body system (core + n + n). Nuclear wave functions for bound state and low-lying three-body continuum excitations are calculated by the method of hyperspherical harmonics. The model is applied to explore electron scattering on ${}^6\mathrm{He}$ leading to nuclear excitations near the three-body breakup threshold.

The sum rule for the structure function $g_1^p$ which is related to the cross section of photoproduction is used to show that a sign change of the integral corresponding to the appropriately defined moment at $n=0$ where the integral is cut at the point $x=x_c(Q^2)$ occurs at very small $Q^2$ near $Q^2~0.09$ (GeV/c)${}^2$ and $x_c~0.024$. This fact shows that the origin of the sign difference between the Ellis-Jaffe sum rule and the Drell-Hearn-Gerasimov sum rule lies in the rapid change of the elastic contribution at low $Q^2$ which is compensated by the inelastic contribution to satisfy the sum rule at $n=0$. Hence it occurs at very small $Q^2$.

We present an analytic, recoil-order calculation of the proton asymmetry from polarized neutron β-decay. The differential decay rate in terms of electron energy and proton direction follows, parametrized in terms of the most general Lorentz-invariant hadron current coupled to a left-handed lepton current. Implications for experimental efforts to measure recoil-order currents are discussed.

A very long baseline experiment, with $L/E$ of $1.6\times {10}^4$ m/MeV, has been proposed as the ideal means to measure ${\theta }_{13}$, including its sign, for neutrino energies less than 50 MeV. Higher energies require consideration of the Earth MSW effect. Approximating a constant density mantle, we examine the ${\nu }_e\text{−}{\nu }_{\mu }$ and ${\nu }_{\mu }\text{−}{\nu }_{\mu }$ oscillation channels at very long baselines with particular focus upon the deviation of ${\theta }_{23}$ from maximal mixing and the sign of ${\theta }_{13}$. It is demonstrated that measurements of these oscillation channels in this region are sensitive to ${\theta }_{13}$, including its sign, and to ${\theta }_{23}$, including its octant, with a significant correlation between the value of ${\theta }_{13}$ and the difference of ${\theta }_{23}$ from maximal mixing.

Recent experimental data on the low-lying states in ${}^{190}\mathrm{W}$ show a change in the $E(4_1^{+})/E(2_1^{+})$ behavior compared to less neutron-rich neigbors. Self-consistent axially-deformed Hartree-Fock calculations, using a separable monopole interaction, of nuclei in the vicinity of ${}^{190}\mathrm{W}$ are performed to systematically examine the evolution of ground state quadrupole deformations. It is found that the neutron number $N=116$ causes a coexistence of oblate and prolate shapes, with a weak dependence on proton number, thereby hindering the development of these isotones as well-deformed rotors.

The semiclassical Coulomb excitation interaction is at times expressed in the Lorentz gauge in terms of the electromagnetic fields and a contribution from the scalar electric potential. We point out that the potential term can make spurious contributions to excitation cross sections, especially when the decay of excited states is taken into account. We show that, through an appropriate gauge transformation, the excitation interaction can be expressed in terms of the electromagnetic fields alone.

The level density parameters for backshifted Fermi gas (both without and with energy-dependent level density parameter) and constant-temperature models have been determined for 310 nuclei between ${}^{18}\mathrm{F}$ and ${}^{251}\mathrm{Cf}$ by fitting of the complete level schemes at low excitation energies and s-wave neutron resonance spacings at the neutron binding energies. Simple formulas are proposed for the description of the two parameters of each of these models, which involve only quantities available from the mass tables. These formulas may constitute a reliable tool for extrapolating to nuclei far from stability, where nuclear level densities cannot be measured.

The β decay of ${}^{13}\mathrm{O}$ has been studied at the IGISOL facility of the Jyväskylä accelerator centre (Finland). By developing a low-energy isotope-separated beam of ${}^{13}\mathrm{O}$ and using a modern segmented charged-particle detector array an improved measurement of the delayed proton spectrum was possible. Protons with energy up to more than 12 MeV are measured and the corresponding $\log (\mathit{ft})$ values extracted. A revised decay scheme is constructed. The connection to molecular states and the shell model is discussed.