To contribute meaningfully to any test of the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, the measured $\mathit{ft}$ value of a superallowed $0^{+}\to 0^{+}$ ${\beta }^{+}$ transition must be obtained to a precision of 0.1% or better. We have determined the half-life of the superallowed emitter ${}^{34}\mathrm{Ar}$ to be 843.8(4)ms; the quoted precision, 0.05%, is a factor of five improvement on the best previous measurement and meets this demanding requirement. Our measurement employed a high-efficiency gas counter, which was sensitive to positrons from both ${}^{34}\mathrm{Ar}$ and its daughter ${}^{34}\mathrm{Cl}$. We achieved the required precision on ${}^{34}\mathrm{Ar}$ by analyzing the parent-daughter composite decay with a new fitting technique. We also obtained an improved half-life for ${}^{34}\mathrm{Cl}$ of 1.5268(5) s, which has 0.03% precision and is a factor of two improvement on previous results. As a by-product of these measurements, we determined the half-life of ${}^{35}\mathrm{Ar}$ to be 1.7754(11) s.

Cross sections for capture reactions of charged particles in hot stellar matter turn out be increased by the quadrupole surface oscillations when the corresponding phonon energies are of the order of the star temperature. This increase is studied in a model that combines barrier distribution induced by surface oscillations and tunneling. The capture of charged particles by nuclei with well-deformed ground states is enhanced in stellar matter. It is found that the influence of quadrupole surface deformation on the nuclear reactions in stars grows when mass and proton numbers in colliding nuclei increase.

Simultaneous measurement of both neutrons and charged particles emitted in the reaction ${}^{64}\mathrm{Zn}$ + ${}^{64}\mathrm{Zn}$ at 45 MeV/nucleon allows comparison of the neutron to proton ratio at midrapidity with that at projectile rapidity. The evolution of $N/Z$ in both rapidity regimes with increasing centrality is examined. For the completely reconstructed midrapidity material one finds that the neutron to proton ratio is above that of the overall ${}^{64}\mathrm{Zn}$ + ${}^{64}\mathrm{Zn}$ system. In contrast, the reconstructed ratio for the quasiprojectile is below that of the overall system. This difference provides the most complete evidence to date of neutron enrichment of midrapidity nuclear matter at the expense of the quasiprojectile.

Three neutron-deuteron scattering experiments at 95 MeV have been performed recently at The Svedberg Laboratory in Uppsala. Subsets of the results of these experiments have been reported in two short articles, showing clear evidence for three-nucleon force effects. In this paper, we present a more detailed description of the experimental methods as well as further discussion of the results. In addition to neutron-deuteron scattering data, neutron-proton and ${}^{12}\mathrm{C}$$(n,n)$ elastic scattering data have been measured for normalization purposes, and ${}^{16}\mathrm{O}$$(n,n)$ data have been obtained for the first time at this energy. It was possible to extract ${}^{12}\mathrm{C}$$(n,n^{\text{'}})$ and ${}^{16}\mathrm{O}$$(n,n^{\text{'}})$ inelastic scattering cross sections to excited states below 12 MeV excitation energy. The inelastic scattering data (for both carbon and oxygen) are shown to have a significant impact on the determination of nuclear recoil kerma coefficients.

Tantalum-180m is a very rare primordial isotope and is not in its nuclear ground state. The radioactivity of ${}^{180}\mathrm{Ta}$${}^m$ has not yet been observed. Previous attempts to measure the half-life of ${}^{180}\mathrm{Ta}$${}^m$ have been performed using various detectors located above ground. In this work a 606 g Ta disk of natural isotopic composition was measured for 170 d in the 225 m deep underground laboratory HADES. The new lower bound for the half-life is $1.7\times {10}^{16}$ y for electron capture decay and $1.2\times {10}^{16}$ y for ${\beta }^{-}$ decay. This gives a total lower bound for the half-life of $7.1\times {10}^{15}$ y, which is a factor of 6 higher than the previous lower bound.

Two spin-doublet states in ${}_{\Lambda }^7$Li are studied on the basis of the $\alpha +\Lambda +n+p$ four-body model. We employ the two-body interactions that reproduce the observed properties of any subsystems composed of $\alpha N,\alpha \Lambda$, $\alpha \mathit{NN}$, and $\alpha \Lambda N$. Furthermore, the $\Lambda N$ interaction is adjusted so as to reproduce the $0^{+}\text{−}{1}^{+}$ splitting of in ${}_{\Lambda }^4$H. The calculated energy splittings of $3/2^{+}\text{−}1/2^{+}$ and $7/2^{+}\text{−}5/2^{+}$ states in ${}_{\Lambda }^7$Li are 0.69 and 0.46 MeV, which are in good agreement with the recent observed data. The spin-dependent components of the $\Lambda N$ interaction are discussed.

The excitation energies and electric multipole decay rates of the lowest lying $2^{+}$ and $3^{-}$ vibrational states in Pb, Sn, and Ni nuclei are calculated following relativistic quasiparticle random-phase approximation formalism based on the relativistic Hartree-Bogoliubov mean field. Two sets of Lagrangian parameters, NL1 and NL3, are used to investigate the effect of the nuclear force. Overall there is good agreement with the available experimental data for a wide range of mass numbers considered here, and the NL3 set seems to be a better choice. However, strictly speaking, these studies point toward the need of a new set of force parameters that could produce more realistic single-particle levels, at least in vicinity of the Fermi surface, of a wide range of nuclear masses.

We present a unified semiclassical model of nucleon-induced pre-equilibrium reactions that permits the simulation of varying degrees of internal configuration mixing. We use it to compare the case of no configuration mixing with that of complete mixing. We also compare the two with an intermediate case that we call the natural model. The no-mixing and natural models yield very similar results, which are quite different from the complete-mixing ones. To reproduce standard exciton model spectra, the model simulations require complete mixing and an intraclass transition rate that is a thousand times larger than the natural one.

We studied the fragmentation of colliding nuclei at the energy of vanishing flow and evaluated its mass dependence throughout the periodic table. This study was performed within the framework of the quantum molecular dynamics model, which has been reported to reproduce the experimental data at low incident energies quite nicely. We simulated as many as 11 reactions for which the balance energy had been measured experimentally. Our observations at the energy of vanishing flow clearly suggest the existence of a power law system mass dependence for various fragment multiplicities. The power factor $\tau$($\propto A^{\tau }$) is close to ($-1/3$), as has also been reported for the mass dependence of the energy of vanishing flow. Experiments are needed to verify these predictions.

Investigation of the effect of the dynamical stage of heavy-ion collisions indicates that the increasing width of the initial isospin distributions is reflected by a significant modification of the isoscaling slope for the final isotopic distributions after deexcitation. For narrow initial distributions, the isoscaling slope assumes the limiting value of the two individual initial nuclei while for wide initial isotopic distributions the slope for hot fragments approaches the initial value. The isoscaling slopes for final cold fragments increase due to secondary emissions. The experimentally observed evolution of the isoscaling parameter in multifragmentation of hot quasiprojectiles at E${}_{\mathrm{inc}}=50A\mathrm{MeV}$, fragmentation of ${}^{86}\mathrm{Kr}$ projectiles at E${}_{\mathrm{inc}}=25A\mathrm{MeV}$ and multifragmentation of target spectators at relativistic energies was reproduced by a simulation with the dynamical stage described using the appropriate model (deep inelastic transfer and incomplete fusion at the Fermi energy domain and spectator-participant model at relativistic energies) and the deexcitation stage described with the statistical multifragmentation model. In all cases the isoscaling behavior was reproduced by a proper description of the dynamical stage and no unambiguous signals of the decrease of the symmetry energy coefficient were observed.

We have measured fragment cross-sections of projectile fragmentation reactions using primary beams of ${}^{40}\mathrm{Ca}$, ${}^{48}\mathrm{Ca}$, ${}^{58}\mathrm{Ni}$, and ${}^{64}\mathrm{Ni}$ at 140 MeV/nucleon on ${}^9\mathrm{Be}$ and ${}^{181}\mathrm{Ta}$ targets. The cross-sections were obtained by integrating the momentum distributions of isotopes with $Z⩾5$ measured in the A1900 fragment separator. We compare the extracted cross-sections to the predictions of the empirical parametrization of fragmentation cross-sections (EPAX).

Recent estimates that color glass condensate initial conditions may generate a larger initial eccentricity for noncentral relativistic heavy ion collisions (relative to the initial eccentricity assumed in earlier hydrodynamic calculations) have raised the possibility of a higher bound on the viscosity of the qark gluon plasma. We show that this large initial eccentricity results in part from a definition of the saturation scale as proportional to the number of nucleons participating in the collision. A saturation scale proportional to the nuclear thickness function (and therefore independent of the probe) leads to a smaller eccentricity, albeit still larger than the value used in hydrodynamic models. Our results suggest that the early elliptic flow in heavy ion collisions (unlike multiplicity distributions) is sensitive to the universality of the saturation scale in high-energy QCD.

A $K$-matrix formalism is used to relate single-channel and multi-channel fits. We show how the single-channel formalism changes as new hadronic channels become accessible. These relations are compared with those commonly used to fit pseudoscalar meson photoproduction data.

We study an equation of state (EOS) for dense matter in the core of a compact star with hyperons and calculate the star's structure in an effective model using a mean-field approach. With varying incompressibility and effective nucleon mass, we analyze the resulting EOS with hyperons in β equilibrium and their underlying effect on the gross properties of the compact star sequences. The results obtained in our analysis are compared with predictions of other theoretical models and observations. The maximum mass of a compact star lies in the range $1.21\text{−}1.96M_{\odot }$ for the different EOS obtained in the model.

Following precise experimental studies at the Duke Free-Electron Laser Laboratory, we discuss the photodisintegration of deuterons with 100% linearly polarized photons using a model independent theoretical approach taking together $M1$ and $E1$ amplitudes simultaneously. The isoscalar $M{1}_s$ contribution is also taken exactly into account. From the existing experimental measurement on doubly polarized thermal neutron capture, it is seen that the isoscalar $M{1}_s$ contribution could be of the same order of magnitude as the experimentally measured cross sections at energies relevant to Big Bang Nucleosynthesis (BBN). Therefore appropriate measurements on deuteron photodisintegration are suggested to empirically determine the $M{1}_s$ contribution at astrophysical energies.

Coulomb energy calculations for the lowest $0^{+},T=2$ state in $A=16$ nuclei allow tight constraints on the masses of the lowest $1/2^{+},T=3/2$ state in ${}^{15}\mathrm{O}$ and ${}^{15}\mathrm{F}$, and of the $0^{+},T=2$ state in ${}^{16}\mathrm{F}$.

We have investigated the disassembly of light nuclear systems with charge $12\text{−}15$ to extract the power-law parameters of the fragmenting nuclear system. Excited nuclei were produced in semiperipheral reactions ${}^{28}\mathrm{Si}$+${}^{112,124}\mathrm{Sn}$ at 30 and 50 MeV/nucleon and the residual cold fragments were detected by the multidetector array for charged particles FAUST. We have studied the power-law parameter τ as a function of the excitation energy of quasiprojectiles. We observe a systematic occurrence of the minimum of τ with respect to the excitation energy accompanied by the maximum of the second moment of the charge distribution in the same region of excitation energy. The main features observed in the characteristics of mass and charge distributions for multifragmentation of heavier systems, such as power-law behavior of charge distribution, are thus observed also for very light systems. Moreover, behavior of the charge distribution with respect to the $N/Z$ degree of freedom has been shown.

The β-decay properties of ${}_{28}^{72}{\mathrm{Ni}}_{44}$ and ${}_{29}^{72}{\mathrm{Cu}}_{43}$ have been studied at the LISOL facility of Louvain-La-Neuve and at the CERN-ISOLDE facility, respectively. These neutron-rich nuclei have been produced in the proton-induced fission of ${}^{238}\mathrm{U}$. Their decay schemes are presented and the lifetime $T_{1/2}=6.63(3)$ s of ${}^{72}\mathrm{Cu}$ was measured. No β-decaying isomeric state was found in ${}^{72}\mathrm{Cu}$, in line with a suggested spin (2) for its ground state. Spin and parity assignments of the observed excited states in the odd-odd nucleus ${}^{72}\mathrm{Cu}$ are proposed and discussed in terms of coupling between the valence proton and neutrons. Comparison is made with a schematic shell-model picture of ${}^{72}\mathrm{Cu}$ and with large-scale shell-model calculations performed in the ($2p_{3/2}1f_{5/2}2p_{1/2}1g_{9/2}$) shell space outside the doubly magic ${}_{28}^{56}{\mathrm{Ni}}_{28}$ core.

One-proton removal from ${}^{15}\mathrm{O}$ at intermediate energies ($56A$ MeV) is studied in the eikonal approximation of the Glauber model. The production of the ${}^{14}\mathrm{N}$ core fragment in the ground and excited states is studied. The calculated proton removal cross section, the ${}^{15}\mathrm{O}$ interaction cross section, and the longitudinal momentum distribution of the ${}^{14}\mathrm{N}$ fragments are compared to recent experimental data [H. Jeppesen et al., Nucl. Phys. A739, 57 (2004)].