Excited states of the extremely neutron-deficient radon isotopes with $N=111,113,115$ have been studied for the first time in a series of in-beam experiments performed at the Accelerator Laboratory of the University of Jyväskylä. The reactions used were: ${}^{118}\mathrm{Sn}$(${}^{82}\mathrm{Kr}$, $3n$)${}^{197}\mathrm{Rn}$, ${}^{120}\mathrm{Sn}$(${}^{82}\mathrm{Kr}$, $3n$)${}^{199}\mathrm{Rn}$, ${}^{150}\mathrm{Sm}$(${}^{52}\mathrm{Cr}$, $3n$)${}^{199}\mathrm{Rn}$, and ${}^{122}\mathrm{Sn}$(${}^{82}\mathrm{Kr}$, $3n$)${}^{201}\mathrm{Rn}$. The γ rays emitted from excited states in the different isotopes were identified using the recoil-α-decay tagging technique. The estimated cross section for the production of ${}^{197}{\mathrm{Rn}}^m$ was 7(3) nb, which is the lowest cross section reported so far for an in-beam study. The energies of the $(17/2^{+})$ levels built on the isomeric $(13/2^{+})$ states in ${}^{197,199,201}\mathrm{Rn}$ indicate a transition from an anharmonic vibrational structure toward a rotational structure at low spins for these nuclei. However, the transition is not as sharp as predicted by theory.

Excited low-spin, nonyrast states in ${}^{170,172,174}\mathrm{Hf}$ were populated in ${\beta }^{+}/\epsilon$ decay and studied through off-beam γ-ray spectroscopy. New coincidence data allowed for a substantial revision of the level schemes of ${}^{170,172}\mathrm{Hf}$ and a confirmation of the level scheme of ${}^{174}\mathrm{Hf}$. The Hf isotopes represent a unique situation in which a crossing of collective intrinsic excitations occurs, enhancing significantly the effects of mixing. Using branching ratios from excited $2^{+}$ states, this mixing is followed and studied. The resulting mixing matrix elements are found to be $~30$ keV—an order of magnitude larger than estimated previously for nearby nuclei. In the case of ${}^{170}\mathrm{Hf}$, the $2_{\beta }^{+}$ and $2_{\gamma }^{+}$ level are shown to be completely mixed.

We compute the inclusive cross section of $f_2$ tensor-meson production in proton-proton collisions at high energy. We use an effective theory inspired from the tensor-meson dominance hypothesis that couples gluons to $f_2$ mesons. We compute the differential cross section in the $k_{\perp }$ factorization and in the color glass condensate formalism in the low density regime. We show that the two formalisms are equivalent for this specific observable. Finally, we study the phenomenology of $f_2$ mesons by comparing theoretical predictions of different parametrizations of the unintegrated gluon distribution function. We find that $f_2$-meson production is another observable that can be used to put constraints on these distributions.

We propose a new method to solve the Hartree-Fock-Bogoliubov equations for weakly bound nuclei, which works for both spherical and axially deformed cases. In this approach, the quasiparticle wave functions are expanded in a complete set of analytical Pöschl-Teller-Ginocchio and Bessel/Coulomb wave functions. Correct asymptotic properties of the quasiparticle wave functions are endowed in the proposed algorithm. Good agreement is obtained with the results of the Hartree-Fock-Bogoliubov calculation using box boundary condition for a set of benchmark spherical and deformed nuclei.

The highly selective reactions ${}^{12}\mathrm{C}$(${}^7\mathrm{Li}$,$d$)${}^{17}\mathrm{O}$ and ${}^{12}\mathrm{C}$(${}^6\mathrm{Li}$,$p$)${}^{17}\mathrm{O}$ have been used to populate high-lying excited states in ${}^{17}\mathrm{O}$ up to 16 MeV in excitation. Several of the states are newly observed, and the existence of others in a previous study of ${}^{12}\mathrm{C}$(${}^6\mathrm{Li}$,$p$)${}^{17}\mathrm{O}$ is confirmed. The observed spectra show a clear gap of about 3 MeV, indicating an energy gap between 3p-2h and 5p-4h states in ${}^{17}\mathrm{O}$. Differential cross section angular distributions have been extracted from the data for both reactions and they have been compared with finite-range DWBA calculations by assuming a “${}^5\mathrm{He}$” cluster transfer. Possible spins and parities are reported for states at 11.82 MeV ($7/2^{+}$), 12.00 MeV $(9/2^{+}),12.22$ MeV ($7/2^{-}$), and 12.42 MeV ($9/2^{+}$).

The neutron capture cross sections of the radioactive isotope ${}^{182}\mathrm{Hf}$ ($t_{1/2}=8.9\times {10}^6$ yr) in the thermal and epithermal energy regions have been measured by activation at the TRIGA Mark-II reactor of the Atomic Institute of the Austrian Universities in Vienna, Austria, and subsequent γ-ray spectroscopy of ${}^{183}\mathrm{Hf}$. High values for the thermal ($\mathit{kT}=25$ meV) cross section ${\sigma }_0=133\pm 10$ b and for the resonance integral $I_0=5850\pm 660$ b were found. Additionally, the absolute intensities of the main γ-ray transitions in the decay of ${}^{182}\mathrm{Hf}$ have been considerably improved.

We discuss the Garvey-Kelson mass relations in an extended formalism and show how they can be used to test and improve the consistency of the most commonly used mass formulas to achieve more accurate predictions.

New levels have been established above the 861-keV, $9/2^{+}$ isomeric state in ${}^{61}\mathrm{Fe}$. The observations can be reproduced satisfactorily by shell model calculations, but only after a significant lowering of the $\nu g_{9/2}$ single-particle energy with respect to the value determined empirically from levels outside a ${}^{48}\mathrm{Ca}$ core. The results are also described well within the scope of the particle-triaxial-rotor model assuming a deformation ${\beta }_2~0.24$. The present findings, together with the recently measured magnetic and quadrupole moments of this state, point toward a structure possibly associated with a prolate shape.

A microscopic potential is derived in correlation with the necking region within the fission-like shape on the basis of potential theory. The whole microscopic potential is of the two-center type, yielding the evolution of proton and neutron level schemes from one parent to two completely separated fragment nuclei. The shell corrections are calculated by using the smoothed necked in single-particle levels. The total deformation energy is obtained from the macroscopic-microscopic method. As an application, a dynamic calculation is performed for the fission of ${}^{236}\mathrm{Pu}$, by using the multidimensional minimization within the total space of deformation of two spheroids joined by a smoothed necking region.

Fusion reactions in the crust of an accreting neutron star are an important source of heat, and the depth at which these reactions occur is important for determining the temperature profile of the star. Fusion reactions depend strongly on the nuclear charge $Z$. Nuclei with $Z⩽6$ can fuse at low densities in a liquid ocean. However, nuclei with $Z=8$ or 10 may not burn until higher densities where the crust is solid and electron capture has made the nuclei neutron rich. We calculate the $S$ factor for fusion reactions of neutron rich nuclei including ${}^{24}\mathrm{O}+{}^{24}\mathrm{O}$ and ${}^{28}\mathrm{Ne}+{}^{28}\mathrm{Ne}$. We use a simple barrier penetration model. The $S$ factor could be further enhanced by dynamical effects involving the neutron rich skin. This possible enhancement in $S$ should be studied in the laboratory with neutron rich radioactive beams. We model the structure of the crust with molecular dynamics simulations. We find that the crust of accreting neutron stars may contain micro-crystals or regions of phase separation. Nevertheless, the screening factors that we determine for the enhancement of the rate of thermonuclear reactions are insensitive to these features. Finally, we calculate the rate of thermonuclear ${}^{24}\mathrm{O}+{}^{24}\mathrm{O}$ fusion and find that ${}^{24}\mathrm{O}$ should burn at densities near ${10}^{11}$ g/cm${}^3$. The energy released from this and similar reactions may be important for the temperature profile of the star.

The functional renormalization group is applied to the effective action for scattering of two nonrelativistic fermions. The resulting physical effective action is shown to contain the correct threshold singularity. The corresponding “bare” action respects Galilean invariance up to second order in momenta. Beyond that order it contains terms that violate this symmetry and, for the particular regulator considered, nonanalytic third-order terms. The corresponding potential can be expanded around a nontrivial fixed point using the power counting appropriate to a system with large scattering length.

An isomeric state in ${}^{209}\mathrm{Ra}$ has been observed for the first time, using the GABRIELA setup at the focal plane of VASSILISSA, to decay to the ground state of ${}^{209}\mathrm{Ra}$ via a cascade of 238-keV ($M2$) and 644-keV transitions. The half-life of the isomer has been measured to be $117(5)\hspace{1em}\mu$s and from systematics is assigned as a neutron $i_{13/2}^{-1}$ excitation.

A model for the $\mathit{NN}$ force, which is induced by the formation of an intermediate dibaryon dressed with σ- and other meson fields, has been developed by the present authors in previous years. This model is applied to the deuteron photodisintegration processes with the main focus on the γ-induced polarization $P_y^{\text{'}}$ of the neutron at energies below $E_{\gamma }\lesssim$ 30 MeV. The inclusion of the intermediate dibaryon leads to a model of the $\mathit{NN}$ force completely different to the conventional $\mathit{NN}$ potential models at short distances. Here the model is tested on the nucleonic level through comparison to rather similar predictions from the conventional $\mathit{NN}$ potential model both for the total and differential cross sections and also for the spin polarization of the ejected neutrons. The predictions of the present model are at least of the same quality than those for the Nijmegen potential; the visible differences with experimental data for $P_y^{\text{'}}$ still remain. However, in combination with the previous results a consistent description can be achieved simultaneously for many observables.

The existence of a higher nodal band state with a ${}^3\mathrm{He}$ cluster structure, i.e., a vibrational mode in which the intercluster relative motion is excited in ${}^{19}\mathrm{Ne}$ in addition to those with the α cluster structure in ${}^{20}\mathrm{Ne}$ and the ${}^{16}\mathrm{O}$ cluster structure in ${}^{32}\mathrm{S}$, is suggested, which reinforces the importance of the concept of ${}^3\mathrm{He}$ clustering in nuclei. This conclusion was reached by investigating ${}^3\mathrm{He}$ scattering from ${}^{16}\mathrm{O}$ in a wide range of incident energies and prerainbow oscillations.

The first in-beam γ-ray spectroscopy study of ${}^{24}\mathrm{Al}$ is presented. A complete level structure of ${}^{24}\mathrm{Al}$ incorporating all states below the proton-emission threshold, has been constructed. The first excited state above the proton threshold has also been identified as a $3^{+}$ state at 2345.1 ± 1.4 keV. This state, corresponding to a resonance energy of 473 ± 3 keV, has been suggested to be the dominant resonance contributing to the ${}^{23}\mathrm{Mg}$($p,\gamma$)${}^{24}\mathrm{Al}$ stellar reaction rate. The improved precision of the level energy and unambiguous assignment of the state has reduced the uncertainty of the ${}^{23}\mathrm{Mg}$$(p,\gamma )$${}^{24}\mathrm{Al}$ stellar reaction rate, which constrains the production of $A>20$ nuclei in ONe novae.

The transverse response function $R_T(q,\omega )$ for ${}^3\mathrm{He}$ is calculated using the configuration space BonnA nucleon-nucleon potential, the Tucson-Melbourne three-body force, and the Coulomb potential. Final states are completely taken into account via the Lorentz integral transform technique. Nonrelativistic one-body currents plus two-body π and ρ meson exchange currents (MECs) as well as the Siegert operator are included. The response $R_T$ is calculated for $q=174$, 250, 400, and 500 MeV/$c$ and in the threshold region at $q=174$, 324, and 487 MeV/$c$. Strong MEC effects are found in low- and high-energy tails, but due to MECs there are also moderate enhancements of the quasielastic peak (6–10%). The calculation is performed both directly and via transformation of electric multipoles to a form that involves the charge operator. The contribution of the latter operator is suppressed in and below the quasielastic peak, while at higher energies the charge operator represents almost the whole MEC contribution at the lowest $q$ value. The effect of the Coulomb force in the final state interaction is investigated for the threshold region at $q=174$ MeV/$c$. Its neglect enhances $R_T$ by more than 10% in the range up to 2 MeV above threshold. In a comparison with experimental data, one finds relatively good agreement at $q=250$ and 400 MeV/$c$, while at $q=500$ MeV/$c$, presumably due to relativistic effects, the theoretical quasielastic peak position is shifted to somewhat higher energies. The strong MEC contributions in the threshold region are nicely confirmed by data at $q=324$ and 487 MeV/$c$.

Fully consistent axially-symmetric-deformed quasiparticle random phase approximation (QRPA) calculations have been performed, in which the same Gogny D1S effective force has been used for both the Hartree-Fock-Bogolyubov mean field and the QRPA approaches. Giant resonances calculated in deformed ${}^{26-28}\mathrm{Si}$ and ${}^{22-24}\mathrm{Mg}$ nuclei as well as in the spherical ${}^{30}\mathrm{Si}$ and ${}^{28}\mathrm{Mg}$ isotopes are presented. Theoretical results for isovector-dipole and isoscalar monopole, quadrupole, and octupole responses are presented and the impact of the intrinsic nuclear deformation is discussed.

We simulate the dynamics of Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC) with a hybrid model that treats the dense early quark-gluon plasma (QGP) stage macroscopically as an ideal fluid but models the dilute late hadron resonance gas (HG) microscopically using a hadronic cascade. By comparing with a pure hydrodynamic approach we identify effects of hadronic viscosity on the transverse momentum spectra and differential elliptic flow $v_2(p_T)$. We investigate the dynamical origins of the observed mass ordering of $v_2(p_T)$ for identified hadrons, focusing on dissipative effects during the late hadronic stage. Within our approach, we find that, at RHIC energies, much of the finally observed mass splitting is generated during the hadronic stage, due to buildup of additional radial flow. The ϕ meson, having a small interaction cross section, does not fully participate in this additional flow. As a result, it violates the mass-ordering pattern for $v_2(p_T)$ that is observed for other hadron species. We also show that the early decoupling of the ϕ meson from the hadronic rescattering dynamics leads to interesting and unambiguous features in the $p_T$ dependence of the nuclear suppression factor $R_{\mathit{AA}}$ and of the $\varphi /p$ ratio.

Unstable modes in asymmetric nuclear matter (ANM) at subsaturation densities are studied in the framework of relativistic mean-field density-dependent hadron models. The size of the instabilities that drive the system are calculated and a comparison with results obtained within the nonlinear Walecka model is presented. The distillation and antidistillation effects are discussed.

The mixing between sterile and active neutrinos is taken into account in the calculation of Big Bang Nucleosynthesis. The abundances of primordial elements, like D, ${}^3\mathrm{He}$, ${}^4\mathrm{He}$, and ${}^7\mathrm{Li}$, are calculated by including sterile neutrinos and by using finite chemical potentials. It is found that the resulting theoretical abundances are consistent with Wilkinson Microwave Anisotropy Probe (WMAP) data on baryonic densities, and with limits of Liquid Scintillator Neutrino Detector (LSND) on mixing angles, only if ${}^7\mathrm{Li}$ is excluded from the statistical analysis of theoretical and experimental results.