The Gamow-Teller (GT) transition strengths in fp-shell nuclei are important parameters in presupernova models. A high-energy-resolution (${}^3\mathrm{He}$$,t$) experiment was performed on the $T_z=1$ nucleus ${}^{46}\mathrm{Ti}$ at $0^{°}$ and at an intermediate incident energy of 140 MeV/nucleon for the study of precise GT transition strengths to the final $T_z=0$ nucleus ${}^{46}\mathrm{V}$. With an energy resolution of 33 keV, individual GT transitions were observed and GT strengths were derived for them up to the excitation energy of 4.5 MeV. The GT strengths were compared with shell-model calculations using various effective interactions. In this low-lying region, most GT states have isospin $T=0$. A few GT states with isospin $T=1$ were identified from the existence of the corresponding (analog) $M1$ states in ${}^{46}\mathrm{Ti}$. By comparing the GT strength with the corresponding (analogous) M1 transition strength studied in ${}^{46}\mathrm{Ti}$($e,e^{\text{'}}$) or ($\gamma ,{\gamma }^{\text{'}}$) measurements, a large constructive interference of orbital and spin terms was suggested for one of these $M1$ transitions.

A formalism based on a relativistic plane-wave impulse approximation is developed to investigate the strange-quark content $g_A^s$ of the axial-vector form factor of the nucleon via neutrino-nucleus scattering. Nuclear structure effects are incorporated via an accurately calibrated relativistic mean-field model. The ratio of neutral- to charged-current cross sections is used to examine the sensitivity of this observable to $g_A^s$. For values of the incident neutrino energy in the range proposed by the FINeSSE Collaboration and by adopting a value of $g_A^s=-0.19$, a 30% enhancement in the ratio is observed relative to the $g_A^s=0$ result.

We present quasielastic neutrino-nucleus cross sections in the energy range from 150 MeV to 5 GeV for the target nuclei ${}^{12}\mathrm{C}$ and ${}^{56}\mathrm{Fe}$. A relativistic description of the nuclear dynamics and the neutrino-nucleus coupling is adopted. For the treatment of final-state interactions we rely on two frameworks succesfully applied to exclusive electron-nucleus scattering: a relativistic optical potential and a relativistic multiple-scattering Glauber approximation. At lower energies, the optical-potential approach is considered to be the optimum choice, whereas at high energies a Glauber approach is more natural. Comparing the results of both calculations, it is found that the Glauber approach yields valid results down to the remarkably small nucleon kinetic energies of 200 MeV. We argue that the nuclear transparencies extracted from $A(e,e^{\text{'}}p)$ measurements can be used to obtain realistic estimates of the effect of FSI mechanisms on quasielastic neutrino-nucleus cross sections. We present two independent relativistic plane-wave impulse approximation (RPWIA) calculations of quasielastic neutrino-nucleus cross sections. They agree at the percentage level, showing the reliability of the numerical techniques adopted and providing benchmark RPWIA results.

The neutron capture cross section of the unstable nucleus ${}^{186}\mathrm{Re}$ is studied by investigating the inverse photodisintegration reaction ${}^{187}\mathrm{Re}$($\gamma ,n$). The special interest of the s-process branching point ${}^{186}\mathrm{Re}$ is related to the question of possible s-process contributions to the abundance of the r-process chronometer nucleus ${}^{187}\mathrm{Re}$. We use the photoactivation technique to measure photodisintegration rates. Our experimental results are in good agreement with two different statistical model calculations. Although the cross sections predicted by both models for the inverse reaction ${}^{186}\mathrm{Re}$($n,\gamma$) is too low to remove the overproduction of ${}^{186}\mathrm{Os}$; the two predicted neutron-capture cross sections differ by a factor of $2.4$; this calls for future theoretical study.

The recently proposed baryon-strangeness correlation ($C_{\mathrm{BS}}$) is studied with a string-hadronic transport model (UrQMD) for various energies from $E_{\mathrm{lab}}=4A$ GeV to $\sqrt{s}=200A$ GeV. It is shown that rescattering among secondaries cannot mimic the predicted correlation pattern expected for a quark-gluon-plasma. However, we find a strong increase of the $C_{\mathrm{BS}}$ correlation function with decreasing collision energy for $p+p$ and Au+Au and/or Pb+Pb reactions. For Au+Au reactions at the top BNL Relativistic Heavy Ion Collider energy ($\sqrt{s}=200A$ GeV), the $C_{\mathrm{BS}}$ correlation is constant for all centralities and compatible with the $p+p$ result. With increasing width of the rapidity window, $C_{\mathrm{BS}}$ follows roughly the shape of the baryon rapidity distribution. We suggest studying the energy and centrality dependence of $C_{\mathrm{BS}}$ to gain information on the onset of the deconfinement transition in temperature and volume.

We measured the polarization-transfer coefficient $K_y^{y^{\text{'}}}$ of the fusion reaction ${}^2\mathrm{H}$($\overrightarrow{d},\overrightarrow{p}$ )${}^3\mathrm{H}$ at E${}_d=58$ keV at the laboratory reaction angle $\theta ={45}^{°}$. The result is compared with theoretical predictions based on Faddeev-Yakubovsky equations, calculated with and without inclusion of the Coulomb interaction, and a prediction based on a T-matrix parametrization of all available data of this reaction at energies below 500 keV.

The near-threshold $\mathit{np}\to d{\pi }^0$ cross section is calculated in chiral perturbation theory to next-to-leading order in the expansion parameter $\sqrt{M{m}_{\pi }}/{\Lambda }_{\chi }$. At this order irreducible pion loops contribute to the relevant pion-production operator. Although their contribution to this operator is finite, considering initial- and final-state distortions produces a linear divergence in its matrix elements. We renormalize this divergence by introducing a counterterm, whose value we choose to reproduce the threshold $\mathit{np}\to d{\pi }^0$ cross section measured at TRIUMF. The energy dependence of this cross section is then predicted in chiral perturbation theory, being determined by the production of p-wave pions, and also by energy dependence in the amplitude for the production of s-wave pions. With an appropriate choice of the counterterm, the chiral prediction for this energy dependence converges well.

We analyze the influence of σ meson exchange on the main non-mesonic hypernuclear weak decay observables: Total rate ${\Gamma }_{\mathrm{NM}}$, neutron-to-proton branching ratio ${\Gamma }_{n/p}$, and proton asymmetry parameter $a_{\Lambda }$. The σ meson exchange is added to the standard strangeness-changing weak $\Lambda N\to \mathit{NN}$ transition potential, which includes the exchange of the complete pseudoscalar and vector mesons octet ($\pi ,\eta ,K,\rho ,\omega ,K^{*}$). Using a shell model formalism, the σ meson weak coupling constants are adjusted to reproduce the recent ${\Gamma }_{\mathrm{NM}}$ and ${\Gamma }_{n/p}$ experimental data for ${}_{\Lambda }^5\mathrm{He}$. Numerical results for the remaining observables of ${}_{\Lambda }^5\mathrm{He}$ and all the observables of ${}_{\Lambda }^{12}C$ decays are presented. They clearly show that the addition of the σ meson improves the agreement with the data. However, its effect it is not enough to reproduce well the $a_{\Lambda }$ values, which means that other improvements of the model must be explored to explain the puzzle posed by the experiments.

The nucleus ${}^{31}\mathrm{P}$ has been studied in the ${}^{24}\mathrm{Mg}$(${}^{16}\mathrm{O}$,2$\alpha p$) reaction with a 70-MeV ${}^{16}\mathrm{O}$ beam. A complex level scheme extended up to spins 17/2${}^{+}$ and 15/2${}^{-}$, on positive and negative parity, respectively, has been established. Lifetimes for the new states have been investigated by the Doppler shift attenuation method. Two shell-model calculations have been performed to describe the experimental data, one by using the code ANTOINE in a valence space restricted to the sd shell, and the other by applying the Monte Carlo shell model in a valence space including the $\mathit{sd}\text{−}\mathit{fp}$ shells. The latter calculation indicates that intruder excitations, involving the promotion of a $T=0$ proton-neutron pair to the fp shell, play a dominant role in the structure of the positive-parity high-spin states of ${}^{31}\mathrm{P}$.

Secondary neutron-production cross sections have been measured from interactions of 290 MeV/nucleon C and 600 MeV/nucleon Ne in a target composed of simulated Martian regolith and polyethylene, and from 400 MeV/nucleon Ne interactions in wall material from the International Space Station. The data were measured between 5° and 80° in the laboratory. We report the double-differential cross sections, angular distributions, and total neutron-production cross sections from all three systems. The spectra from all three systems exhibit behavior previously reported in other heavy-ion neutron-production experiments, namely, a peak at forward angles near the energy corresponding to the beam velocity, with the remaining spectra generated by pre-equilibrium and equilibrium processes. The double-differential cross sections are fitted with a moving-source parametrization. Also reported are the data without corrections for neutron flux attenuation in the target and other intervening materials and for neutron production in nontarget materials near the target position. These uncorrected spectra are compared with SHIELD-HIT and PHITS transport model calculations. The transport model calculations reproduce the spectral shapes well but, on average, underestimate the magnitudes of the cross sections.

Systematic and consistent microscopic description of measured reaction cross sections at low projectile en-ergies is presented. Finite-range Glauber model (GM-F) along with the Coulomb modification is used. The required inputs, namely the neutron and proton density distributions of the relevant projectiles and the targets, are calculated in the relativistic mean field framework. The GM-F reproduces the experiment well. At high projectile energies both the GM-F and the zero-range Glauber model in the optical limit (GM-Z) yield almost identical results; however, the GM-F in general is superior at low projectile energies, as expected.

The astrophysical factor for ${}^7\mathrm{Be}$($p,\gamma$)${}^8\mathrm{B}$ at zero energy, $S_{17}(0)$, is determined from an analysis of ${}^{208}\mathrm{Pb}$(${}^8\mathrm{B}$, $p+$${}^7\mathrm{Be}$)${}^{208}\mathrm{Pb}$ at 52 MeV/nucleon by means of the method of continuum-discretized coupled channels (CDCC) taking account of all nuclear and Coulomb breakup processes. The asymptotic normalization coefficient (ANC) method is used to extract $S_{17}(0)$ from the calculated breakup cross section. The main result of the present paper is $S_{17}(0)=20.9_{-1.9}^{+2.0}$ eV b. The error consists of 8.4% experimental systematic error and the error due to the ambiguity in the s-wave $p\text{−}$${}^7\mathrm{Be}$ scattering length. This value of $S_{17}(0)$ differs from the one extracted with the first-order perturbation theory including Coulomb breakup by dipole transitions: $18.9\pm 1.8$ eV b. It turns out that the difference is due to the inclusion of the nuclear and Coulomb-quadrupole transitions and multistep processes of all-order in the present work. The $p\text{−}$${}^7\mathrm{Be}$ interaction potential used in the CDCC calculation is also used in the ANC analysis of ${}^7\mathrm{Be}$($p,\gamma$)${}^8\mathrm{B}$. The value of $S_{17}(0)=21.7_{-0.55}^{+0.62}$ eV b obtained is consistent with the previous one obtained from a precise measurement of the p-capture reaction cross section extrapolated to zero incident energy, $S_{17}(0)=22.1\pm 0.6$ (expt) $\pm 0.6$ (theo) eV b, where (theo) stands for the error in the extrapolation. Thus, the agreement between the values of $S_{17}(0)$ obtained from direct ${}^7\mathrm{Be}$($p,\gamma$)${}^8\mathrm{B}$ and indirect ${}^8\mathrm{B}$-breakup measurements is significantly improved.

The isoscaling properties of isotopically resolved projectile residues from peripheral collisions of ${}^{86}\mathrm{Kr}$ (25 MeV/nucleon) ${}^{64}\mathrm{Ni}$ (25 MeV/nucleon), and ${}^{136}\mathrm{Xe}$ (20 MeV/nucleon) beams on various target pairs are employed to probe the symmetry energy coefficient of the nuclear binding energy. The present study focuses on heavy projectile fragments produced in peripheral and semiperipheral collisions near the onset of multifragment emission ($E^{*}/A=2$–3 MeV). For these fragments, the measured average velocities are used to extract excitation energies. The excitation energies, in turn, are used to estimate the temperatures of the fragmenting quasiprojectiles in the framework the Fermi gas model. The isoscaling analysis of the fragment yields provided the isoscaling parameters α that, in combination with temperatures and isospin asymmetries provided the symmetry energy coefficient of the nuclear binding energy of the hot fragmenting quasiprojectiles. The extracted values of the symmetry energy coefficient at this excitation energy range (2–3 MeV/nucleon) are lower than the typical liquid-drop model value ∼25 MeV corresponding to ground-state nuclei and show a monotonic decrease with increasing excitation energy. This result is of importance in the formation of hot nuclei in heavy-ion reactions and in hot stellar environments such as supernova.

Calculations that demonstrate the influence of three key nuclear reaction rates on the evolution of asymptotic giant branch stars have been carried out. We study the case of a star with an initial mass of $2M_{\odot }$ and a metallicity of $Z=0.01$, somewhat less than the solar metallicity. The dredge-up of nuclear processed material from the interior of the star and the yield predictions for carbon are sensitive to the rate of the ${}^{14}\mathrm{N}$$(p,\gamma )$${}^{15}\mathrm{O}$ and triple-α reactions. These reactions dominate the H- and He-burning shells of stars in this late evolutionary phase. Published uncertainty estimates for each of these two rates propagated through stellar evolution calculations cause uncertainties in carbon enrichment and yield predictions of about a factor of 2. The other important He-burning reaction, ${}^{12}\mathrm{C}$$(\alpha ,\gamma )$${}^{16}\mathrm{O}$, although associated with the largest uncertainty in our study, does not have a significant influence on the abundance evolution compared with other modeling uncertainties. This finding remains valid when the entire evolution from the main sequence to the tip of the asymptotic giant branch is considered. We discuss the experimental sources of the rate uncertainties addressed here and give some outlooks for future work.

The sensitivity of the differential cross section of the interaction between a neutrino-electron and dense matter to the possibly nonzero neutrino electromagnetic properties has been investigated. Here, the relativistic mean field model inspired by effective field theory has been used to describe nonstrange dense matter, both with and without the neutrino trapping. We have found that the cross section becomes more sensitive to the constituent distribution of the matter, once electromagnetic properties of the neutrino are taken into account. The effects of neutrino electromagnetic properties on the cross section become more significant for the neutrino magnetic moment ${\mu }_{\nu }>{10}^{-10}{\mu }_B$ and for the neutrino charge radius $R>{10}^{-5}{\mathrm{MeV}}^{-1}$.

The modern theory of neutrinoless double beta decay includes a scaling factor that has often been treated inconsistently in the literature. The nuclear contribution to the decay half-life can be suppressed by 15%–20% when scaling factors are mismatched. Correspondingly, $\langle m_{\nu }\rangle$ is overestimated.

We report on a set of in-beam studies of excited states in ${}^{250}\mathrm{Fm}$. We detected prompt γ rays by using the JUROSPHERE IV array and conversion electrons by using the SACRED spectrometer. Both devices were used in conjunction with the RITU gas-filled recoil separator located at the University of Jyväskylä. ${}^{250}\mathrm{Fm}$ nuclei were produced through the ${}^{204}\mathrm{Hg}$(${}^{48}\mathrm{Ca}$,$2n)$${}^{250}\mathrm{Fm}$ fusion-evaporation reaction. An experimental excitation function gave a maximum reaction cross section of (980 ± 160) nb at an energy of 209 MeV in the center of the target. Tagging techniques were employed, and a number of E2 transitions were observed that connected the ground-state band levels from spin $4^{+}$ up to ${18}^{+}$. The highly converted $4^{+}\to 2^{+}$ transition is observed only by use of conversion electron spectroscopy. The observed ground-state band transitions indicate a rotational structure. We deduce a quadrupole deformation parameter of ${\beta }_2=0.28$ ± 0.02. A low-energy background of apparent nuclear origin is observed in conversion electrons and postulated to arise from the decay of high-K bands. The half-life of ${}^{250}\mathrm{Fm}$ is measured to be 30.4 ± 1.5 min.

High-spin states in the proton-rich nucleus ${}^{45}\mathrm{V}$ have been identified for the first time. A comprehensive γ-ray decay scheme has been established following an experiment performed at the Vivitron accelerator at IReS Strasbourg by using the Euroball γ-ray detector array coupled to the Neutron Wall and Euclides detector arrays. The natural (negative-) parity scheme is identified up to the $f_{7/2}$ band termination in addition to a positive-parity collective structure based on a $d_{3/2}$ particle-hole excitation. Comparison of this scheme with that of the mirror partner, ${}^{45}\mathrm{Ti}$, has yielded detailed information on the variation of Coulomb energy as a function of excitation energy and angular momentum. This is the first time that such an analysis has been performed for a collective structure built on a cross-shell excitation. Comparison of the observed Coulomb energies with those predicted by large-scale shell-model calculations is presented. In this case, unusually, the calculations do not fare as well as for heavier nuclei in the shell. In addition, stark differences between the two nuclei are observed for the decay intensities of the parity-changing $E1$ decays that de-excite the positive-parity deformed bands.

The neutron and proton single-particle spectral functions in asymmetric nuclear matter fulfill energy-weighted sum rules. The validity of these sum rules within the self-consistent Green's function approach is investigated. The various contributions to these sum rules and their convergence as a function of energy provide information about correlations induced by the realistic interaction between the nucleons. The study of the sum rules in asymmetric nuclear matter exhibits the isospin dependence of the nucleon-nucleon correlations.

Gamma-ray and conversion-electron spectroscopy have established the existence of a 2.29(1) s, $K^{\pi }=0^{+}$, isomeric state in neutron-rich ${}^{174}\mathrm{Tm}$. The isomer deexcites via 100- and 152-keV electromagnetic transitions. First results from a newly commissioned Si(Li) detector array have established their $M1$ and $E3$ multipolarities, respectively. The single-particle configurations of the excited states suggest that the $E3$ transition originates from a $\pi h_{11/2}^{-1}\to \pi d_{3/2}$ configuration change, whereas the $M1$ transition occurs between members of a Gallaghar-Moszkowski doublet. From the measured half-life, the deduced $B(E3)$ value of 0.024(2) W.u. is highly hindered. The reported measurements resolve ambiguities in the previously proposed β decay scheme of ${}^{174}\mathrm{Er}$ to ${}^{174}\mathrm{Tm}$.