The higher-spin structure of ${}^{38}\mathrm{Cl}$ ($N=21$) was investigated following the ${}^{26}\mathrm{Mg}({}^{14}\mathrm{C}$, $pn$) reaction at 30 and 37 MeV beam energies. The outgoing protons were detected in an $E\text{−}\mathrm{\Delta }E$ Si telescope placed at $0^{\circ }$ close to the target with a Ta beam stopper between the target and telescope. Multiple $\gamma$ rays were detected in time coincidence with the protons using an enhanced version of the FSU $\gamma$-detection array. The level scheme was extended up to 8420 keV with a likely spin of 10 $\hslash$. A new multishell interaction was developed guided by the experimental information. This FSU interaction was built by fitting to the energies of 270 experimental states from ${}^{13}\mathrm{C}$ to ${}^{51}\mathrm{Ti}$. Calculations using the FSU interaction reproduce observed properties of ${}^{38}\mathrm{Cl}$ rather well, including the spectroscopic factors. The interaction has been successfully used to interpret the 1p1h and 2p2h configurations in some nearby nuclei as well.

The decay of $K$ isomers in Cm ($Z$ = 96) isotopes has been studied using inelastic and transfer reactions. The half-life of a previously identified 2-quasiparticle (qp) $K^{\pi }=8^{-}$ isomer in ${}^{246}\mathrm{Cm}$ has been measured. A new 2-qp isomer is observed in ${}^{248}\mathrm{Cm}$, its half-life measured and its decay scheme established. The reduced $K$ hindrances extracted for the decay transitions from the isomers in ${}^{246,248}\mathrm{Cm}$ indicate $K$ to be a robust quantum number and validate axial symmetry in these nuclei. The excitation energies of the 2-qp isomers in ${}^{246}\mathrm{Cm}$ ($N$ = 150) and ${}^{248}\mathrm{Cm}$ ($N$ = 152) support the persistence of a deformed subshell gap at $N$ = 152 in the $Z\approx 100$ region down to $Z$ = 96 nuclei.

I discuss the role and impact of net-baryon number conservation in measurements of net-proton fluctuations in heavy-ion collisions. I show that the magnitude of the fluctuations is entirely determined by the strength of two particle correlations. At LHC and top RHIC energy, this implies the fluctuations are proportional to the integral of the balance function (BF), $B^{p\overline{p}}$ of protons and antiprotons, while in the context of the RHIC beam energy scan (BES), one must also account for correlations of stopped protons. The integral of $B^{p\overline{p}}$ measured in a $4\pi$ detector depends on the relative cross sections of processes yielding $p\overline{p}$ and those balancing the proton baryon number via the production of other antibaryons. The accepted integral of $B^{p\overline{p}}$ further depends on the shape and width of the BF relative to the width of the acceptance. The magnitude of the measured second-order cumulant of net-proton fluctuations thus has much less to do with QCD susceptibilities than with the creation/transport of baryons and antibaryons in heavy-ion collisions, and most particularly the impact of radial flow on the width of the BF. I thus advocate that net-proton fluctuations should be studied by means of differential BF measurements rather than with integral correlators. I also derive an expression of net-baryon fluctuations in terms of integrals of balance functions of identified baryon pairs and argue that measurements of such balance functions would enable a better understanding of the collision system expansion dynamics, the hadronization chemistry, and an experimental assessment of the strength of net-baryon fluctuations.

An ab initio Green's function Monte Carlo (GFMC) method is introduced for calculating total rates of muon weak capture in light nuclei with mass number $A\le 12$. As a first application of the method, we perform a calculation of the rate in ${}^3\mathrm{H}$ and ${}^4\mathrm{He}$ in a dynamical framework based on realistic two- and three-nucleon interactions and realistic nuclear charge-changing weak currents. The currents include one- and two-body terms induced by $\pi$- and $\rho$-meson exchange, and $N$-to-$\mathrm{\Delta }$ excitation, and are constrained to reproduce the empirical value of the Gamow-Teller matrix element in tritium. We investigate the sensitivity of theoretical predictions to current parametrizations of the nucleon axial and induced pseudoscalar form factors as well as to two-body contributions in the weak currents. The large uncertainties in the measured ${}^4\mathrm{He}$ rates obtained from bubble-chamber experiments (carried out over 50 years ago) prevent us from drawing any definite conclusions. No data exist for ${}^3\mathrm{H}$, but results are compared to those of a recent Faddeev calculation as a validation of the present GFMC method.

The structure of ${}^{34}\mathrm{Si}$ was studied through $\gamma$ spectroscopy separately in the ${\beta }^{-}$ decays of ${}^{34}\mathrm{Mg}$ and ${}^{34}\mathrm{Al}$ at the ISOLDE facility of CERN. Different configurations in ${}^{34}\mathrm{Si}$ were populated independently from the two recently identified $\beta$-decaying states in ${}^{34}\mathrm{Al}$ having spin-parity assignments $J^{\pi }=4^{-}$ dominated by the normal configuration $\pi {\left(d_{5/2}\right)}^{-1}\otimes \nu \left(f_{7/2}\right)$ and $J^{\pi }=1^{+}$ by the intruder configuration $\pi {\left(d_{5/2}\right)}^{-1}\otimes \nu {\left(d_{3/2}\right)}^{-1}{\left(f_{7/2}\right)}^2$. The paper reports on spectroscopic properties of ${}^{34}\mathrm{Si}$ such as an extended level scheme, spin and parity assignments based on $log\left(ft\right)$ values and $\gamma$-ray branching ratios, absolute $\beta$ feeding intensities, and neutron emission probabilities. A total of 11 newly identified levels and 26 transitions were added to the previously known level scheme of ${}^{34}\mathrm{Si}$. Large scale shell-model calculations using the SDPF-U-MIX interaction, able to treat higher order intruder configurations, are compared with the new results and conclusions are drawn concerning the predictive power of SDPF-U-MIX, the $N=20$ shell gap, the level of mixing between normal and intruder configurations for the $0_1^{+}$, $0_2^{+}$, and $2_1^{+}$ states, and the absence of triaxial deformation in ${}^{34}\mathrm{Si}$.

Measurements are reported for the angle-averaged double-differential cross section ${\langle d^2\sigma /\phantom{\sigma d{E}_{n}d{\mathrm{\Omega }}_n}d{E}_{n}d{\mathrm{\Omega }}_n\rangle }_{0^{\circ }<\theta <7.4^{\circ }}$ for the breakup reaction ${}^2\mathrm{H}$($n,2n$)${}^1\mathrm{H}$, induced by 14-MeV neutrons generated using an inertial confinement fusion platform. A bright neutron source, created on the OMEGA Laser System [Boehly et al., Opt. Commun. 133, 495 (1997)] with a luminosity of $L={10}^{24}{\mathrm{s}}^{-1}$, was used to irradiate deuterated targets. The absolute yields and energy spectra from the breakup neutrons emitted in a forward-angle geometry ($\theta =0^{\circ }$ to 7.4°) were detected with a sensitive, high-dynamic-range neutron time-of-flight spectrometer. The cross-section data, measured for neutron energy range from 0.5 to 10 MeV, is well reproduced by a theoretical calculation employing realistic nucleon–nucleon and three-nucleon forces.

Background: Deuteron-induced reactions are widely used to probe nuclear structure and astrophysical information. Those (d,p) reactions may be viewed as three-body reactions and described with Faddeev techniques.

Purpose: Faddeev-AGS equations in momentum space have a long tradition of utilizing separable interactions in order to arrive at sets of coupled integral equations in one variable. However, it needs to be demonstrated that observables calculated based on separable interactions agree exactly with those based on nonseparable forces.

Methods: Momentum space AGS equations are solved with separable and nonseparable forces as coupled integral equations.

Results: Deuteron-$\alpha$ scattering is calculated via momentum space AGS equations using the CD-Bonn neutron-proton force and a Woods-Saxon type neutron(proton)-${}^4\mathrm{He}$ force, for which the Pauli-forbidden S-wave bound state is projected out. Elastic as well as breakup observables are calculated and compared to results in which the interactions in the two-body sub-systems are represented by separable interactions derived in the Ernst-Shakin-Thaler (EST) framework.

Conclusions: We find that the calculations based on the separable representation of the interactions and the original interactions give results that are in excellent agreement. Specifically, integrated cross sections and angular distributions for elastic scattering agree within $\approx 1$%, which is well below typical experimental errors. In addition, the fivefold differential cross sections corresponding to breakup of the deuteron agree extremely well.

Precision nuclear charge radii measurements in the light-mass region are essential for understanding the evolution of nuclear structure, but their measurement represents a great challenge for experimental techniques. At the Collinear Resonance Ionization Spectroscopy (CRIS) setup at ISOLDE-CERN, a laser frequency calibration and monitoring system was installed and commissioned through the hyperfine spectra measurement of ${}^{38–47}\mathrm{K}$. It allowed for the extraction of the hyperfine parameters and isotope shifts with better than 1 MHz precision. These results are in excellent agreement with available literature values and they demonstrate the suitability of the CRIS technique for the study of nuclear observables in light atomic systems. In addition, the spectral line shapes obtained under different conditions were systematically investigated, highlighting the importance of finding optimal conditions, under which the extracted nuclear properties remain unaffected by laser-atom interactions.

The excitation of atomic nuclei via magnetic dipole transitions is closely related to the inelastic neutral-current neutrino-nucleus (NC-$\nu \mathrm{A}$) scattering process due to the similarity of the transition operators. NC-$\nu \mathrm{A}$-scattering serves for the detection of supernova neutrinos and poses a significant source of background in modern liquid-argon based high-energy neutrino detection experiments. To enable tests of the reliability of predictions for neutrino-nucleus scattering, the magnetic dipole response of ${}^{40}\mathrm{Ar}$ below 7.7 MeV was characterized in a nuclear resonance fluorescence experiment using quasimonoenergetic $\gamma$-ray beams. The linear polarization of the beams allowed for assignments of electric or magnetic character to previously known dipole excitations. A total magnetic dipole strength of $0.{36}_{-0.05}^{+0.04}{\mu }_N^2$ was identified in the energy range of the present experiment. Combined with data from previous measurements, the full magnetic dipole strength of ${}^{40}\mathrm{Ar}$ below the neutron separation threshold was investigated. Due to the low background in the energy range within the bandwidth of the $\gamma$-ray beams, the previous sensitivity limit was improved. A large-scale nuclear shell model calculation in the $sd\text{−}fp$ space satisfactorily agrees with the data in terms of excitation energies and strengths of the observed $1^{+}$ states.

The dynamical cluster-decay model (DCM), an extension of the preformed cluster model of Gupta and collaborators for the decay of hot and rotating compound nuclei (CN) formed in low-energy reactions, has been applied to study the mass distribution of ${}^{236}\mathrm{U}^{*}$ formed at an excitation energy corresponding to the capture of thermal neutrons by ${}^{235}\mathrm{U}$. The role of excitation energy of the compound nucleus, neck length parameter, and mass window (range of mass numbers) considered are also analyzed. The excitation energy of the compound nucleus is kept fixed for all channels, and the temperature for each channel is obtained iteratively to conserve the sum of excitation energies of two fragments to the excitation energy of the compound nucleus at a fixed distance, mimicking the saddle configuration. The obtained mass distributions and yields are compared with experimental yields.

The α-decay half-lives of some superheavy nuclei within a modified generalized liquid drop model (MGLDM) have been studied. The computed half-lives are compared with experimental data and also with existing theoretical models as well as the Royer, AKRE, New RenB, and Akrawy formulas, and are found to be in good agreement. Also, we have calculated the RMS deviation. We expect the present investigation is a clear indicator of the predictive power of the model and formulas, which may be helpful for future investigations in this field.

Making use of the hybrid Regge-plus-resonance model, we investigate the process of kaon photoproduction off the proton target. We present a new model whose free parameters were adjusted to data in and above the resonance region and which provides an acceptable description of experimental data. The overwhelming majority of nucleon resonances selected in this analysis overlaps with those selected in our previous analyses and also with the Bayesian analysis with the Regge-plus-resonance model, which we deem to be dependable. A novel feature of our model consists in applying a different scheme for gauge-invariance restoration, which results in a need for implementing a contact current. As we further reveal, the choice of the gauge invariance restoration scheme as well as the choice of either pseudoscalar or pseudovector coupling in the strong vertex play a significant role for cross-section predictions at forward angles where data are scarce.

In a simple coexistence model, I have examined $2n$ transfer ratios of $0^{+}$ states in even Zr nuclei. Results indicate that mixing is small in ${}^{96}\mathrm{Zr}$, but larger and nearly equal in ${}^{92,94}\mathrm{Zr}$, with ${}^{90}\mathrm{Zr}$ slightly larger. The ${}^{96}\mathrm{Zr}$ result is consistent with earlier analyses of E2 strengths.

We investigate the fusion of ${}^{16}\mathrm{O}$ and ${}^{154}\mathrm{Sm}$ with excited states at Coulomb energies using a theoretical dynamical model. The two-body Schrödinger equation is solved using the time-dependent wave-packet coupled-channels method. The wave function of the collective motion and excitations are visualized in both position and momentum space, providing a detailed mechanism of the reaction. We benchmark our calculations of the energy-resolved fusion transmission coefficients with those from the time-independent coupled-channels method. The present results are in good agreement with the time-independent results for a wide range of energies and angular momenta, demonstrating both the reliability of the quantum wave-packet dynamical approach for fusion and its usefulness for providing additional insights into fusion dynamics.

This paper presents a measurement of forward-forward and forward-central dijet azimuthal angular correlations and conditional yields in proton-proton ($pp$) and proton-lead ($p+\mathrm{Pb}$) collisions as a probe of the nuclear gluon density in regions where the fraction of the average momentum per nucleon carried by the parton entering the hard scattering is low. In these regions, gluon saturation can modify the rapidly increasing parton distribution function of the gluon. The analysis utilizes $25{\mathrm{pb}}^{-1}$ of $pp$ data and $360\mu {\mathrm{b}}^{-1}$ of $p+\mathrm{Pb}$ data, both at $\sqrt{s_{NN}}=5.02$ TeV, collected in 2015 and 2016, respectively, with the ATLAS detector at the Large Hadron Collider. The measurement is performed in the center-of-mass frame of the nucleon-nucleon system in the rapidity range between $-4.0$ and 4.0 using the two highest transverse-momentum jets in each event, with the highest transverse-momentum jet restricted to the forward rapidity range. No significant broadening of azimuthal angular correlations is observed for forward-forward or forward-central dijets in $p+\mathrm{Pb}$ compared to $pp$ collisions. For forward-forward jet pairs in the proton-going direction, the ratio of conditional yields in $p+\mathrm{Pb}$ collisions to those in $pp$ collisions is suppressed by approximately 20%, with no significant dependence on the transverse momentum of the dijet system. No modification of conditional yields is observed for forward-central dijets.

We present a new approach to identify fragments using computer simulations of relativistic heavy ion collisions. It is based on the simulated annealing technique and can be applied to $n$-body transport models such as quantum molecular dynamics. This new approach is able to predict isotope yields as well as hypernucleus production. In order to illustrate its predicting power, we confront this new method with experimental data and show the sensitivity to the parameters which govern cluster formation.

Background: The neutron-deficient osmium isotopic chain provides a great laboratory for the study of shape evolution, with the transition from the soft triaxial rotor in ${}^{168}\mathrm{Os}$ to the well-deformed prolate rotor in ${}^{180}\mathrm{Os}$, while shape coexistence appears around $N=96$ in ${}^{172}\mathrm{Os}$. Therefore, the study of the Os isotopic chain should provide a better understanding of shape changes in nuclei and a detailed scrutiny of nuclear structure calculations. In this paper, the lifetimes of the low-lying yrast states of ${}^{170}\mathrm{Os}$ have been measured for the first time to investigate the shape evolution with neutron number.

Purpose: Lifetimes of excited states in the ground-state band of ${}^{170}\mathrm{Os}$ are measured to investigate the shape evolution with neutron number in osmium isotopes and compare with state-of-the-art calculations.

Methods: The states of interest were populated via the fusion-evaporation reaction ${}^{142}\mathrm{Nd}({}^{32}\mathrm{S},4n)$ at a bombarding energy of 170 MeV at the ALTO facility from IPN (Orsay, France). Lifetimes of the $2_1^{+}$ and $4_1^{+}$ states in ${}^{170}\mathrm{Os}$ were measured with the recoil-distance Doppler-shift method using the Orsay universal plunger system.

Results: Lifetimes of the two first excited states in ${}^{170}\mathrm{Os}$ were measured for the first time. A very small $B(E2;4_1^{+}\to 2_1^{+})/B(E2;2_1^{+}\to 0_1^{+})=0.38\left(11\right)$ was found, which is very uncharacteristic for collective nuclei. These results were compared to state-of-the-art beyond-mean-field calculations.

Conclusions: Although theoretical results give satisfactory results for the energy of the first few excited states in ${}^{170}\mathrm{Os}$ and the $B(E2;2_1^{+}\to 0_1^{+})$ they fail to reproduce the very small $B(E2;4_1^{+}\to 2_1^{+})$, which remains a puzzle.

The roles of strange axial form factor and axial mass for both neutral-current and charged-current reactions are investigated in the quasi-elastic neutrino-nucleus scattering within a relativistic single-particle model. The calculation is performed for various target nuclei like ${}^{12}\mathrm{C}$, ${}^{40}\mathrm{Ca}$, ${}^{56}\mathrm{Fe}$, and ${}^{208}\mathrm{Pb}$ at the incident neutrino (antineutrino) energies of 1.0 and 2.0 GeV. Then we discuss the dependence of differential cross section on the role of axial mass and strange axial form factor with different target nuclei on both neutral-current and charged-current reactions. Finally we compare our results with the MiniBooNE, T2K, and $\mathrm{MINER}\nu \mathrm{A}$ experimental data for the double-differential cross section and the scaled total cross section.

Photoneutron cross sections were measured for ${}^{137}\mathrm{Ba}$ and ${}^{138}\mathrm{Ba}$ at energies below two-neutron threshold using quasimonochromatic $\gamma$-ray beams produced in laser Compton scattering at the NewSUBARU synchrotron radiation facility. The photoneutron data are used to constrain the $\gamma$-ray strength function on the basis of the Hartree-Fock-Bogolyubov plus quasiparticle random phase approximation using the Gogny $D1M$ interaction. Supplementing the experimentally constrained $\gamma$-ray strength function with the zero-limit $E1$ and $M1$ contributions, which are unique to the deexcitation mode, we discuss radiative neutron capture cross sections relevant to the $s$-process nucleosynthesis of barium isotopes in the vicinity of the neutron magic number 82.