The lifetimes of the excited states of ${}^{55}\mathrm{Mn}$ between 1.5 and 2.7 MeV were measured using nuclear resonance fluorescence. The absolute lifetimes of the excited levels were determined from simultaneous measurements of manganese and aluminum. In this approach, the precisely known aluminum state serves as a means to normalize the results. Our findings differ from the evaluated level lifetimes in the Evaluated Nuclear Structure Data File (ENSDF), but agree with earlier nuclear resonance fluorescence measurements.

Relativistic effects are investigated in nuclear matter calculations employing renormalized low-momentum nucleon-nucleon ($\mathit{NN}$) interactions. It is demonstrated that the relativistic effects cure a problem of nonrelativistic low-momentum interactions, which fail to reproduce saturation of nuclear matter. Including relativistic effects, one already obtains saturation in a Hartree-Fock calculation. Brueckner-Hartree-Fock calculations lead to a further improvement of the saturation properties. The results are rather insensitive to the realistic $\mathit{NN}$ interaction on which they are based.

We use an approximate method to derive the polarization potential associated with breakup couplings in ${}^9\mathrm{Be}+{}^{144}\mathrm{Sm}$ collisions at near-barrier energies. This method is particularly useful for collisions of weakly bound projectiles which break up into more than two fragments. We find that this potential is repulsive at large distances and produces long-range absorption. Using this potential, we evaluate breakup and fusion cross section. In the case of fusion, for which there is available data, our results are shown to be in very good agreement with the experiment.

We develop a subtractive renormalization scheme to evaluate the $P$-wave $\mathit{NN}$ scattering phase shifts using chiral effective theory potentials. This allows us to consider arbitrarily high cutoffs in the Lippmann-Schwinger equation (LSE). We employ $\mathit{NN}$ potentials computed up to next-to-next-to-leading order (NNLO) in chiral effective theory, using both dimensional regularization and spectral-function regularization. Our results obtained from the subtracted $P$-wave LSE show that renormalization of the NNLO potential can be achieved by using the generalized $\mathit{NN}$ scattering lengths as input—an alternative to fitting the constant that multiplies the $P$-wave contact interaction in the chiral effective theory $\mathit{NN}$ force. However, to obtain a reasonable fit to the $\mathit{NN}$ data at NNLO the generalized scattering lengths must be varied away from the values extracted from the so-called high-precision potentials. We investigate how the generalized scattering lengths extracted from $\mathit{NN}$ data using various chiral potentials vary with the cutoff in the LSE. The cutoff dependence of these observables, as well as of the phase shifts at $T_{\mathrm{lab}}\approx 100$ MeV, suggests that for a chiral potential computed with dimensional regularization the highest LSE cutoff it is sensible to adopt is approximately 1 GeV. Using spectral-function regularization to compute the two-pion-exchange potentials postpones the onset of cutoff dependence in these quantities but does not remove it.

In this paper we study the magnetic susceptibility and other thermodynamic properties of the polarized nuclear matter at finite temperature using the lowest order constrained variational (LOCV) method employing the ${\mathit{AV}}_{18}$ potential. Our results show a monotonic behavior for the magnetic susceptibility which indicates that the spontaneous transition to the ferromagnetic phase does not occur for this system.

The philosophy on production of exotic hadrons (multiquark states) in the framework of the quark combination model is investigated, taking $f_0(980)$ as an example. The production rate and $p_T$ spectra of $f_0(980)$ considered as $(s\overline{s})$ or $(s\overline{q}\overline{s}q)$, respectively, are calculated and compared in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV. The unitarity of various combination models, when open for exotic hadron production, is addressed.

We propose and implement a simple method for improving the variational wave function of a many-body system. We have obtained a significant improvement in the binding energies, wave functions, and variance for the light nuclei ${}^3\mathrm{H}$, ${}^4\mathrm{He}$, and ${}^6\mathrm{Li}$, using the fully realistic Argonne $({\mathrm{AV}}_{18})$ two-body and Urbana-IX (UIX) three-body interactions. The energy of ${}^4\mathrm{He}$ was improved by about 0.2 MeV and the ${}^6\mathrm{Li}$ binding energy was increased by $\approx 1.7$ MeV compared to earlier variational Monte Carlo results. The latter result demonstrates the significant progress achieved by our method, and detailed analyses of the improved results are given. With central interactions the results are found to be in agreement with the “exact” calculations. Our study shows that the relative error in the many-body wave functions, compared to two-body pair correlations, increases rapidly at least proportionally to the number of pairs in the system. However, this error does not increase indefinitely since the pair interactions saturate owing to convergence of cluster expansion.

Projectile-nucleus capture by a target nucleus at bombarding energies in the vicinity of the Coulomb barrier is treated with the reduced-density-matrix formalism. The effects of dissipation and fluctuations on the capture process are taken self-consistently into account within the quantum model suggested. The excitation functions for the capture in the reactions ${}^{16}\mathrm{O}$, ${}^{19}\mathrm{F}$, ${}^{26}\mathrm{Mg}$, ${}^{28}\mathrm{Si}$, ${}^{32,34,36,38}\mathrm{S}$, ${}^{40,48}\mathrm{Ca}$, ${}^{50}\mathrm{Ti}$, ${}^{52}\mathrm{Cr}$$+$${}^{208}\mathrm{Pb}$ with spherical nuclei are calculated and compared with the experimental data. At bombarding energies about (15–25) MeV above the Coulomb barrier the maximum of capture cross section is revealed for the ${}^{58}\mathrm{Ni}$$+$${}^{208}\mathrm{Pb}$ reaction.

High-statistics $\beta$-decay measurements of ${}^{112}\mathrm{Ag}$ and ${}^{112}\mathrm{In}$ were performed to study the structure of the ${}^{112}\mathrm{Cd}$ nucleus. The precise energies of the doublet of levels at 1871 keV, for which the $0^{+}$ member has been suggested as a possible daughter state following neutrinoless double electron capture of ${}^{112}\mathrm{Sn}$, were determined to be 1871.137(72) keV ($0_4^{+}$ level) and 1870.743(54) keV ($4_2^{+}$ level). The nature of the $0_4^{+}$ level, required for the calculation of the nuclear matrix element that would be needed to extract a neutrino mass from neutrinoless double electron capture to this state, is suggested to be of intruder origin.

The reactions of ${}^6\mathrm{Li}$ on ${}^{58}\mathrm{Fe}$ and ${}^7\mathrm{Li}$ on ${}^{57}\mathrm{Fe}$ have been studied at 15 MeV beam energy. These two reactions produce the same compound nucleus, ${}^{64}\mathrm{Cu}$. The charged particle spectra were measured at backward angles. The data obtained have been compared with Hauser-Feshbach model calculations. The level density parameters of ${}^{63}\mathrm{Ni}$ and ${}^{60}\mathrm{Co}$ have been obtained from the particle evaporation spectra. We also find contributions from the break up of the lithium projectiles to the low energy region of the $\alpha$ spectra.

The $\gamma$ rays associated with $\beta$ decay of the 21/2${\mathrm{}}^{+}$ isomer in ${}^{93}\mathrm{Mo}$ ($E_x=2.425$ MeV, $T_{1/2}=6.85$ h) were measured with a selective sensitivity to long-lived isomer decays. A new 1262-keV transition was found in the $\gamma$-$\gamma$ coincidence measurement, and it was attributed to a transition in ${}^{93}\mathrm{Nb}$, which is the daughter nucleus of the $\beta$ decay of the ${}^{93}\mathrm{Mo}$ isomer, from the 2.753- to the 1.491-MeV levels. Accurate $\gamma$-ray intensity balances have determined the $\beta$-decay intensity from the ${}^{93}\mathrm{Mo}$ isomer to the 2.753-MeV level in ${}^{93}\mathrm{Nb}$ and placed no appreciable intensity for the previously reported $\beta$-decay branching to the 2.180-MeV level, for which a recent in-beam $\gamma$-ray experiment assigned to be $I^{\pi }$ $=$ 17/2${\mathrm{}}^{-}$. Based on the $\gamma$-ray intensities from the 2.753-MeV level, spin-parity assignment of this level was revised from 21/2${\mathrm{}}^{+}$ to 19/2${\mathrm{}}^{+}$. The observed $\beta$-decay intensity and the spin-parity assignment were explained by the $\mathit{jj}$-coupling shell model calculations.

A $\beta$-decay study of ${}^{77}\mathrm{Cu}$ has been performed at the ISOLDE mass separator with the aim to deduce its $\beta$-decay properties and to obtain spectroscopic information on ${}^{77}\mathrm{Zn}$. Neutron-rich copper isotopes were produced by means of proton- or neutron-induced fission reactions on ${}^{238}\mathrm{U}$. After the production, ${}^{77}\mathrm{Cu}$ was selectively laser ionized, mass separated, and sent to different detection systems where $\beta$-$\gamma$ and $\beta$-$n$ coincidence data were collected. We report on the deduced half-live, decay scheme, and possible spin assignment of ${}^{77}\mathrm{Cu}$.

The Bohr Hamiltonian is considered in two forms. The first form deals with the Hamiltonian having a complicated expression for the mass tensor and a simple one for the quadrupole moment operator. The second form is characterized by a simple Hamiltonian with a one-constant mass coefficient but by a complicated expression for the quadrupole moment. The procedure to construct the quadrupole moment operator is outlined. As an example, the parameters of the second form of the quadrupole operator are calculated for the $N=90\hspace{0.5em}X(5)$ type nuclei ${}^{150}\mathrm{Nd}$, ${}^{152}\mathrm{Sm}$, and ${}^{154}\mathrm{Gd}$. The values of the intraband and the interband $E2$ transitions relating ground, $\beta$, and $\gamma$ bands are calculated for these nuclei using the constructed $E2$ transition operator.

For the ${\beta }^{-}$-decay of the neutron we analyze the continuum-state and bound-state decay modes. We calculate the decay rates, the electron energy spectrum for the continuum-state decay mode, and angular distributions of the decay probabilities for the continuum-state and bound-state decay modes. The theoretical results are obtained for the new value for the axial coupling constant $g_A=1.2750(9)$, obtained recently by H. Abele [Prog. Part. Nucl. Phys. 60, 1 (2008)] from the fit of the experimental data on the coefficient of the correlation of the neutron spin and the electron momentum of the electron energy spectrum of the continuum-state decay mode. We take into account the contribution of radiative corrections and the scalar and tensor weak couplings. The calculated angular distributions of the probabilities of the bound-state decay modes of the polarized neutron can be used for the experimental measurements of the bound-state ${\beta }^{-}$-decays into the hyperfine states with total angular momentum $F=1$ and scalar and tensor weak coupling constants.

Along with ${\pi }^0$ and $\eta$ mesons, a resonance structure in the invariant mass spectrum of two photons at $M_{\gamma \gamma }=360\pm 7\pm 9$ MeV is observed in the reaction $d\text{C}\to \gamma +\gamma +X$ at momentum 2.75 GeV/$c$ per nucleon. Estimates of its width and production cross section are $\Gamma =63.7\pm 17.8$ MeV and ${\sigma }_{\gamma \gamma }=98\pm {24}_{-67}^{+93}\hspace{0.5em}\mu \mathrm{b}$, respectively. The collected statistics amount to $2339\pm 340$ events of $1.5\times {10}^6$ triggered interactions of a total number $~{10}^{12}$ of $d$C interactions. This resonance structure is not observed in $p$C collisions at the beam momentum 5.5 GeV/$c$. Possible mechanisms of this ABC-like effect are discussed.

Three-body correlations for the ground-state decay of the lightest two-proton emitter ${}^6\mathrm{Be}$ are studied both theoretically and experimentally. Theoretical studies are performed in a three-body hyperspherical-harmonics cluster model. In the experimental studies, the ground state of ${}^6\mathrm{Be}$ was formed following the $\alpha$ decay of a ${}^{10}\mathrm{C}$ beam inelastically excited through interactions with Be and C targets. Excellent agreement between theory and experiment is obtained demonstrating the existence of complicated correlation patterns that can elucidate the structure of ${}^6\mathrm{Be}$ and, possibly, of the $A=6$ isobars.

The experimental data for $\alpha$-decay half-lives to ground and excited states of deformed nuclei with $222⩽A⩽252$ and $88⩽Z⩽102$ are analyzed in the framework of the unified model for $\alpha$ decay and $\alpha$ capture. The branching ratios to excited states depend on the energy and the angular momentum of the $\alpha$ particle. The evaluated branching ratios for $0_{\mathrm{g}.\mathrm{s}.}^{+}\to 0_{\mathrm{g}.\mathrm{s}.}^{+},2^{+},4^{+}\hspace{0.5em}\alpha$ transitions in even-even nuclei agree with the experimental data. The experimental and calculated branching ratios for $\alpha$ transitions into more highly excited states are similar.

Charged-particle and $\gamma$ decays in ${}^{24}\mathrm{Mg}{}^{*}$ are investigated for excitation energies where quasimolecular resonances appear in ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ collisions. Various theoretical predictions for the occurrence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are discussed within the measured ${}^{24}\mathrm{Mg}{}^{*}$ excitation energy region. The inverse kinematics reaction ${}^{24}\mathrm{Mg}+{}^{12}\mathrm{C}$ is studied at $E_{\mathrm{lab}}({}^{24}\mathrm{Mg})=130$ MeV, an energy that enables the population of ${}^{24}\mathrm{Mg}$ states decaying into ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ resonant breakup states. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with Euroball IV installed at the Vivitron tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions, and their associated $\gamma$ decays studied. Coincident events associated with inelastic and $\alpha$-transfer channels have been selected by choosing the excitation energy or the entry point via the two-body $Q$ values. The analysis of the binary reaction channels is presented with a particular emphasis on ${}^{24}\mathrm{Mg}\text{−}\gamma$, ${}^{20}\mathrm{Ne}\text{−}\gamma$, and ${}^{16}\mathrm{O}$-$\gamma$ coincidences. New information (spin and branching ratios) is deduced on high-energy states in ${}^{24}\mathrm{Mg}$ and ${}^{16}\mathrm{O}$, respectively.