abstract

A brief outlook on low-energy nuclear physics is presented. Selected recent developments in nuclear structure theory are highlighted and a few open questions are discussed.

abstract

We show the formulation and the result of test calculation of the overlap of excites states in the quasiparticle random-phase approximation for calculating the nuclear matrix elements of the neutrino-less double beta decay. Our method uses the ground states of the QRPA explicitly. The feasibility of that calculation is demonstrated, and the effectiveness of the truncation used in our method is shown.

abstract

The Skyrme nuclear energy density functional theory (DFT) is used to model neutron-induced fission in actinides. This paper focuses on the numerical implementation of the theory. In particular, it reports recent advances in DFT code development on leadership class computers, and presents a detailed analysis of the numerical accuracy of DFT solvers for near-scission calculations.

abstract

Using the pairing-deformation-frequency self-consistent total-Routhian-surface and configuration-constrained potential-energy-surface calculations, we have studied nuclear deformation and its effect on the structure of nuclei. It was found that the high-order multipolarity-six (\(\beta _6\)) deformation plays a significant role in superheavy nuclei. Possible non-collective high-spin isomeric states which locate in the second well of actinide nuclei have been investigated with the predictions of excitation energies and configurations. High-spin isomers can extend shape coexistence in \(A\sim 190\) neutron-deficient nuclei. Triaxiality with \(\gamma \sim 30^\circ \) is found in the ground and excited rotational states of the \(A\sim 70\) germanium isotopes. Octupole correlations have also been discussed in different mass regions. In recent experiments, the textbook nucleus \(^{158}\)Er has been reached at ultrahigh spins around \(65\hbar \). We have studied \(^{158}\)Er ultrahigh-spin states by means of the self-consistent tilted-axis-cranking method based on the Nilsson shell correction and the Skyrme–Hartree–Fock model. The calculation with a \(\gamma \approx 12^\circ \) triaxial-strongly-deformed (TSD) excited configuration can well reproduce the observed large transitional quadrupole moment. It is demonstrated that the TSD minimum at negative \(\gamma \) deformation which appears in the principal-axis-cranking approach is a saddle point if allowing the rotational axis to change direction.

abstract

Half-lives of superheavy elements (SH) with \(108\le Z\le 126\) and \(148\le N\le 188\) are calculated from decay energies, fission barriers and the mass parameters that have been obtained in a uniform microscopic way within a selfconsistent Hartree–Fock–Bogoliubov (HFB) method, SkM\(^*\) force in the particle–hole channel and the density dependent delta interaction in the particle–particle channel. We consider \(\alpha \)-decay, spontaneous fission (SF) and \(\beta \) processes (\(\beta ^\pm \) and electron capture). The results indicate that the longest total half-lives are of the order of seconds for a set of nuclei in the vicinity of \(Z=112\), \(N=182\).

abstract

The HFB self-consistent method has been applied to study the properties of several neutron deficient superheavy nuclei with \(Z=120\)–\(124\), \(N=160\)–\(168\). Their distinctive feature is the existence of minima of the total HFB energy for strongly deformed, oblate shapes. The self-consistent results agree quite remarkably with those currently obtained by using microscopic–macroscopic method.

abstract

The time evolution of nuclei at high excitation energy and angular momentum is studied by means of three-dimensional Langevin calculations performed for two different parameterizations of the macroscopic potential: the Finite Range Liquid Drop Model (FRLDM) and the Lublin–Strasbourg Drop (LSD) prescription. Depending on the mass of the system, the topology of the potential energy surface (PES), in the deformation space, is observed to be different within these two approaches. When incorporated in the dynamical calculation, the FRLDM and LSD models are observed to give similar results in the heavy mass region, whereas the predictions can be strongly dependent on the PES for fission of medium-mass nuclei. The shape-dependent congruence energy is only slightly modulated on the top of the bulk LD part although it changes the PES and the barrier height.

abstract

In this work, we report a few examples of excitation energies, magnetic and quadrupole moments as well as \(B(M1)\) and \(B(E2)\) transition probabilities calculated within the multiparticle–multihole (\(mp\)–\(mh\)) configuration mixing approach [N. Pillet, J.-F. Berger, E. Caurier, Phys. Rev. C78, 024305 (2008); N. Pillet et al. , Phys. Rev. C85, 044315 (2012)], for \(sd\)-shell even–even nuclei with \(10\leqslant Z\), \(N \leqslant 18\). The D1S Gogny effective interaction has been used. Only low-lying positive parity states have been considered. A very satisfactory agreement is obtained with experiment for energies, magnetic moments and \(B(M1)\) transition probabilities. The calculated \(B(E2)\) transition probabilities between \(2_1^+\) and \(0_1^+\) states, \(4_1^+\) and \(2_1^+\) states reproduce the experimental trends along the isotonic and isotopic chains with the good order of magnitude.

abstract

We report on the progress in conceptual and mathematical solutions of the theory of nuclear geometrical symmetries — more precisely: nuclear point-group symmetries — obtained within the TetraNuc Collaboration in recent years. We shortly summarise the basic concepts, the strategic lines of the solutions as well as the link between theoretical and experimental considerations.

abstract

The decay spectroscopy of \(^{106,108}\)Zr has been performed as a first decay spectroscopy experiment at the RIKEN Radioactive Isotope Beam Factory (RIBF). The \(\gamma \) rays emitted from \(^{106}\)Zr and \(^{108}\)Zr were measured in the \(\beta \) decay of \(^{106}\)Y and in the decay of the \(^{108}\)Zr isomer, respectively. The deformation evolution of the Zr isotopes and the isomerism of \(^{108}\)Zr are discussed. The EUROBALL-RIKEN Cluster Array (EURICA) spectrometer used for the decay spectroscopy with high statistics at RIBF is introduced.

abstract

In this article, we present strategic lines necessary in order to construct general nuclear mean-field Hamiltonians as allowed by symmetry principles, keeping in mind a possible increase of their predictive power.

abstract

A collective approach combining zero- and one-phonon excitations in nuclear quadrupole and octupole modes together with the rotational motion up to spin \(J=5\) is used to verify the possibility of reproducing the experimental electric \(B(E\lambda )\) probabilities in \(^{156}\)Gd nucleus in presence of the high-rank tetrahedral/octahedral symmetries in collective quadrupole, octupole and rotational states.

abstract

The multi-particle-plus-triaxial-rotor (MPR) model calculations were performed for several nuclei in the 100, 130 and 190 mass regions. It was found that chiral geometry can form even for very asymmetric nucleon configurations. However, the near-degeneracy of the partner bands may not be as good as the one observed for symmetric or slightly asymmetric configurations.

abstract

Precise and large sets of data for cross section, vector and tensor analyzing powers for the \(^{1}\)H(\(\vec d,pp)n\) breakup reaction were obtained in experiments carried out at KVI Groningen and FZ-Jülich at deuteron beam energies of 100 MeV, 13 MeV and 160 MeV (cross sections only). These precise experimental data obtained in a wide phase-space region allowed to establish evidences for three-nucleon force contributions and to confirm predictions of sizable effect of the Coulomb force. The vector analyzing powers data are generally quite well described by theoretical predictions even with pure nucleon–nucleon interactions. Tensor analyzing powers can be also very well reproduced by calculations in most of the studied region but in some regions locally discrepancies are observed at energy of 130 MeV.

abstract

The study of transfer reactions in inverse kinematics is a major focus of existing and future radioactive-ion-beam facilities. One of the obstacles in such measurements is poor \(Q\)-value resolution, often several hundred keV, which can prevent the extraction of useful information. At Argonne National Laboratory, it has recently been demonstrated that good \(Q\)-value resolution can be achieved by transporting the outgoing ions through a high-field solenoid, measuring their position as a function of energy. This provides several advantages over conventional Si arrays, such as large acceptance, good particle identification, and most importantly a \(Q\)-value resolution of better than 100 keV in most cases, including reactions with moderately heavy beams. In this paper, the concept of the solenoidal spectrometer, called HELIOS, will be discussed along with highlights of recent results.

abstract

In this contribution, we present recent results related to the quadrupole collectivity in neutron rich carbon isotopes. \(B(E2)\) transitions strengths derived from lifetime measurements are interpreted in a seniority scheme, indicating an increase role of proton excitations due to the reduction of the \(p_{3/2}\)–\(p_{1/2}\) spin–orbit splitting. We also discuss the evolution of the \(N=40\) shell closure with isospin and report on preliminary results of Coulomb Excitation experiments on \(^{66,68}\)Fe and \(^{64}\)Cr. Finally, a short review of the gamma-ray tracking technique and a status report of GRETINA are presented. Some aspects of the exciting physics campaign being carried out at NSCL/MSU are discussed.

abstract

The level schemes of \(^{68}\)Ni and \(^{67}\)Co were extended following \(^{70}\)Zn-induced deep-inelastic reactions. No evidence for a previously reported proton intruder \(0^+\) state at 2202 keV in \(^{68}\)Ni was found. In \(^{67}\)Co, two new states at 3216 and 3415 keV have been established; additional states associated with the intruder configuration have yet to be identified.

abstract

Lifetimes of the low-lying states in Zn isotopes around \(N=40\) have been measured using the Recoil Distance Doppler Shift method. The nuclei of interest were populated in deep-inelastic reactions in inverse kinematics. The ratios \(B(E2; 4^{+}\rightarrow 2^{+})/ B(E2; 2^{+}\rightarrow 0^{+}\)) measured for the Zn isotopes follow a systematics consistent with a seniority classification.

abstract

Deep-inelastic collisions of a \(^{208}\)Pb beam on a \(^{208}\)Pb target were performed using the ATLAS accelerator at Argonne National Laboratory. Prompt and delayed \(\gamma \)-rays from the reaction products were detected using the GAMMASPHERE detector array. The cross-coincidence method was used to identify transitions in \(^{207}\)Tl, by gating on \(\gamma \)-rays from its better-characterised reaction partner \(^{209}\)Bi. A number of new transitions were found in \(^{207}\)Tl.

abstract

In this contribution, we report on results of recent experiments performed at the velocity filter SHIP at GSI in Darmstadt obtained for nuclei above fermium (\(Z=100\)). In particular, new results are presented from an \(\alpha \)-decay study of \(^{259}\)Sg. These data resulted in the observation of new isomeric state in \(^{259}\)Sg and in the improvement of the quasiparticle systematics for \(N=153\) isotones.

abstract

The isomeric first excited state of \(^{229}\)Th exhibits the lowest nuclear excitation energy in the whole landscape of known nuclei. Due to its extremely low energy of 7.6(5) eV and its long lifetime of ca. 10\(^4\) s, it exhibits an extremely sharp relative linewidth of \(\Delta E/E\approx 10^{-20}\), thus rendering \(^{229m}\)Th an ideal candidate for a nuclear optical clock with very high accuracy. An experimental approach is introduced, based on a spatially decoupled population and de-excitation of the isomeric state, aiming at a first direct identification of the 163(11) nm UV fluorescence and targeting to improve on the accuracy of the transition wavelength, thus enabling an all-optical control via laser excitation.

abstract

High-seniority excitations above the \(10^+\) and \(27/2^-\) isomeric states were investigated with gamma coincidence techniques in neutron-rich Sn isotopes produced in fission processes following \(^{48}\)Ca+\(^{208}\)Pb, \(^{48}\)Ca+\(^{238}\)U and \(^{64}\)Ni+\(^{238}\)U reactions. In the data analysis, the delayed gamma coincidence technique was used to establish high-spin state structures in all Sn isotopes with isomeric half-lives below 10 \(\mu \)sec. For cases with long-lived isomeric states, the gamma cross-coincidence method was employed to identify such structures. The relevant features of the fusion–fission process were investigated to enable these identifications. The discussion of some details of these analyses is followed by two examples of the results obtained: the \(^{124}\)Sn level scheme and the level energy systematics for selected states established in even Sn isotopes.

abstract

The \(^{7}\)Li+\(^{130}\)Te reaction was used to populate excited states in \(^{132}\)Te and \(^{134}\)Xe. The experiment at the Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest, Romania, used an array of high-purity germanium (HPGe) and cerium-doped lanthanum bromide (LaBr\(_{3}\)(Ce)) detectors to measure sub-nanosecond half-lives using fast-timing techniques. The half-lives of the yrast 4\(^{+}\) and 6\(^{+}\) levels were measured in the \(N=80\) nuclei \(^{132}\)Te and \(^{134}\)Xe, respectively. An upper limit of \(T_{1/2}\)\(\leq 40\) ps was assigned to the 4\(^{+}\) level in \(^{132}\)Te and \(T_{1/2}=1075(155)\) ps was assigned to the 6\(^{+}\) level in \(^{134}\)Xe. The systematics of the \(B(E2)\) strengths around the \(N=82\) shell closure are discussed.

abstract

Transfer reactions played a key role in unraveling many properties of the nucleus, in particular they have been essential to define the relevance of the independent particle motion and to define the properties of two-particle correlations. In view of the now available radioactive beams, it is important to summarize some aspects of the transfer processes that will be relevant to define the properties of nuclei close to the neutron and proton drip lines.

abstract

The revival of transfer reaction studies benefited from the construction of the new generation large solid angle spectrometers, coupled to large \(\gamma \) arrays. The recent results of \(\gamma \)-particle coincident measurements in \(^{40}\)Ca\(+^{96}\)Zr and \(^{40}\)Ar\(+^{208}\)Pb reactions demonstrate a strong interplay between single-particle and collective degrees of freedom that is pertinent to the reaction dynamics. The development of collectivity has been followed in odd Ar isotopes populated in the \(^{40}\)Ar\(+^{208}\)Pb reaction through the excitation of the \(11/2^{-}\) states, understood as the coupling of single particle degrees of freedom to nuclear vibration quanta. Pair transfer modes is another important degree of freedom which is presently being studied with Prisma in inverse kinematics at energies far below the Coulomb barrier. First results from the \(^{96}\)Zr\(+^{40}\)Ca reaction elucidate the role played by nucleon–nucleon correlation.

abstract

The reaccelerated fission-fragment beams at HRIBF provide a unique opportunity for studying the mechanisms of fusion involving nuclei with large neutron excess. The fusion excitation functions for neutron-rich radioactive \(^{132}\)Sn incident on \(^{40}\)Ca and \(^{58}\)Ni targets have been measured to explore the role of transfer couplings in sub-barrier fusion enhancement. Evaporation residue cross sections for \(^{124,126,127,128}\)Sn+\(^{64}\)Ni were measured to study the dependence of fusion probability on neutron excess.

abstract

Recent results on the reaction dynamics induced by light radioactive ion beams at Coulomb barrier energies are reviewed. As a general feature, the exotic structure and the weak binding energy of most of these projectiles enhance the reaction probability rather than the fusion cross section, as originally expected. The quest has now moved toward understanding which direct reaction mechanism originates the enhancement. Experimental data showed that \(n\)-halo and \(p\)-halo nuclei are characterized by a different behavior. Transfer processes enhance the reaction probability for \(n\)-halo nuclei, such as \(^{6,8}\)He, while for \(p\)-halo nuclei, such as \(^8\)B, the breakup channel seems to be mainly responsible for the enhancement.

abstract

“Ternary fission” has been studied previously as a process, where a lighter fragment with \(A \lt 30\) amu is emitted perpendicular to the fission axis. We use the term “true ternary fission” for a fission process with three masses of comparable size, \(A \gt 35\). Theoretical considerations repeatedly predicted that true ternary fission must occur in a collinear (prolate) geometry. Over the last decade (see Pyatkov et al. in Eur. Phys. J. A45 29 (2010) and refs. therein), the true ternary fission decay in neutron induced fission \(^{235}\)U (\(n\),fff) and in spontaneous fission of \(^{252}\)Cf (sf) has been studied. The name used for this process is (CCT), with three cluster-fragments of similar size in a collinear decay. The measurements are based on binary coincidences containing TOF and energy determinations, in two detector telescopes placed at \(180^\circ \). The masses and energies of the registered two fragments give complete kinematic solutions. The missing mass events in binary coincidences can be determined, these events are obtained by blocking one of the lighter fragments (after multiple scattering in the backing) on a structure in front of the detectors. The relatively high total yield of CCT (more than \(10^{-3}\) per binary fission) is explained. It is due to the favorable \(Q\)-values (more positive than for binary) and the large phase space of the CCT-decay, dominated by three (magic) clusters: e.g. isotopes of Sn, Ca and Ni. The kinetic energies of the fragments have been calculated. The fragments placed in between the other two have very low kinetic energies (below 20 MeV) and have thus escaped their detection in previous work on “ternary fission”, where in addition an oblate shape and a triangle for the momentum vectors had been assumed.

abstract

The heavy ion reaction \(^{22}\)Ne+\(^{208}\)Pb at 128 MeV beam energy has been studied using the PRISMA-CLARA experimental setup at Legnaro National Laboratories. Aim of the experiment is the measurement of elastic, inelastic and one nucleon transfer cross sections. The data are presented in parallel with similar results for the unstable \(^{24}\)Ne nucleus, using existing data from the reaction \(^{24}\)Ne+\(^{208}\)Pb at 182 MeV (measured at SPIRAL with the VAMOS-EXOGAM setup). A comparison with angular distributions obtained by semiclassical and DWBA predictions for the quadrupole deformation parameter is also discussed. In particular, the DWBA analysis allowed to determine the \(\beta _{2}^{\rm C}\) charge deformation parameter both in \(^{22}\)Ne and \(^{24}\)Ne.

abstract

The quasi-elastic scattering angular distribution of the collision \(^{11}\)Be + \(^{64}\)Zn was measured and compared with the elastic scattering angular distribution for its core, the \(^{10}\)Be nucleus on the same target. Optical model and continuum-discretized coupled-channel calculations of the \(^{11}\)Be+\(^{64}\)Zn reaction were performed in order to interpret the effect of coupling with the break-up channels on the measured cross-sections.

abstract

The dynamics of \(^{8}\)He around the Coulomb barrier is investigated by measuring the energy and angular distribution of the elastic \(^{8}\)He and the \(^{6}\)He and \(^{4}\)He fragment yields in the collision process with a \(^{208}\)Pb target. The experiment was carried out at SPIRAL/GANIL in October 2010. The experimental results will provide information about the relevant reaction mechanisms and the validity of the optical model (OM) when applied to exotic nuclei. In this paper, details of the experimental setup and preliminary results on the elastic scattering for the collision at 22 MeV are presented.

abstract

The quantum diffusion approach is applied to study the isotopic dependencies of capture cross section and mean-square angular momentum in the reactions \(^{48}\)Ca + \(^{144,150,154}\)Sm and \(^{40}\)Ca + \(^{154}\)Sm.

abstract

The reduced transition probability \(B(E2; 0^+_{\rm gs} \rightarrow 2^+_1)\) for the proton-rich nucleus \(^{28}\)S was determined experimentally using Coulomb excitation at 53 MeV/nucleon. The resultant \(B(E2)\) value is smaller than those of neighboring \(N=12\) isotones and \(Z=16\) isotopes. The ratio of neutron/proton transition matrix amplitudes for the \(0^+_{\rm gs} \rightarrow 2^+_1\) transition were obtained to be \(1.9(2) \times N/Z\) from the present result and known \(B(E2)\) value in the mirror nucleus \(^{28}\)Mg. These results indicate the emergence of the magic number \(Z=16\) in \(^{28}\)S.

abstract

A new isospin-nonconserving Hamiltonian for \(sd\)-shell nuclei is applied to the calculation of branching ratios of the isospin-forbidden proton emission following the beta decay of \(^{22}\)Al.

abstract

The masses of heavy two-proton emitters (\(^{45}\)Fe, \(^{48}\)Ni and \(^{54}\)Zn) are calculated, basing on experimentally measured two-proton decay energies. The results are compared with theoretical predictions and extrapolations.

abstract

Odd-parity core excited states have been identified in two close neighbors of \(^{100}\)Sn: \(^{96}\)Pd and \(^{97}\)Ag. This was done in an fusion-evaporation experiment, using a \(^{58}\)Ni beam on a \(^{45}\)Sc target. Even-parity core excited states in these nuclei are very well reproduced in large scale (LSSM) calculations in which particle–hole excitations are allowed with up to five \(g_{9/2}\) protons and neutrons across the \(N=Z=50\) gap, to the \(g_{7/2}\), \(d_{5/2}\), \(d_{3/2}\), and \(s_{1/2}\) orbitals. The odd-parity states can only be qualitatively interpreted though, employing calculations in the full fpg shell model space, but with just one particle–hole core excitation allowed. A more complete model including odd-parity orbitals is need for the description of core excited states in the region of \(^{100}\)Sn.

abstract

Lifetimes of high-spin states in \(^{66}\)Ge have been measured using Doppler shift attenuation technique with the GASP and RFD setup. The \(^{66}\)Ge nucleus was populated in the \(^{40}\)Ca(\(^{32}\)S, \(\alpha 2p\)) reaction at beam energy of 95 MeV. The transition quadrupole moment, \(Q_{\rm t}\), of the negative parity band in this nucleus has been determined to be approx. 0.9\(\pm \)0.1 eb.

abstract

The nuclear structure of neutron-rich nuclei close to the double-magic nucleus \(^{78}\)Ni has been investigated by measuring the lifetime of excited states. In this contribution, it will be presented the lifetime of the \(J^{\pi }=7/2^-\) excited state at 981 keV of the \(^{71}\)Cu isotope, measured using the AGATA Demonstrator coupled to the PRISMA spectrometer and the Köln plunger setup. This is the first time this combined setup has been used for a lifetime measurement.

abstract

We present the current status of the available data and the calculations for the cross section of the \(^3\)He(\(\alpha \), \(\gamma \))\(^7\)Be reaction — accurate knowledge of which is required for the solar neutrino flux and the primordial \(^7\)Li abundance calculations. Precision measurements are being carried out by us in the range of \(E_{\rm cm}=1\) to 3 MeV using two types of experimental methods. A brief account of this work is given together with some of the recent theoretical calculations.

abstract

Primordial Nucleosynthesis, or Big-Bang Nucleosynthesis (BBN), is one of the three items of evidence for the Big-Bang model, together with the expansion of the Universe and the Cosmic Microwave Background. There is a good global agreement over a range of nine orders of magnitude between abundances of \(^4\)He, D, \(^3\)He and \(^{7}\)Li deduced from observations, and calculated in primordial nucleosynthesis. This comparison was used to determine the baryonic density of the Universe. For this purpose, it is now superseded by the analysis of the Cosmic Microwave Background (CMB) radiation anisotropies. However, there remains, a yet unexplained, discrepancy of a factor \(\approx 3\), between the calculated and observed lithium primordial abundances, that has not been reduced, neither by recent nuclear physics experiments, nor by new observations.

abstract

The reactions of relevance for stellar evolution are difficult to measure directly in the laboratory at the small astrophysical energies. In recent years, indirect reaction methods have been developed and applied to extract low-energy astrophysical \(S\)-factors. These methods require a combination of new experimental techniques and theoretical efforts, which are the subject of this review.

abstract

Neutron decay spectroscopy has become a successful tool to explore nuclear properties of nuclei with the largest neutron-to-proton ratios. Resonances in nuclei located beyond the neutron dripline are accessible by kinematic reconstruction of the decay products. The development of two-neutron detection capabilities of the Modular Neutron Array (MoNA) at NSCL has opened up the possibility to search for unbound nuclei which decay by the emission of two neutrons. Specifically, this exotic decay mode was observed in \(^{16}\)Be and \(^{26}\)O.

abstract

The structure of nucleus \(^{25}\)F was studied by use of in-beam \(\gamma \)-ray spectroscopy of the fragmentation of a \(^{36}\)S beam. The emitted \(\gamma \) rays were detected by BaF\(_2\) detectors. In the \(\gamma \)-ray spectrum obtained a wide bump between 3 and 4.5 MeV energy was observed corresponding to a set of \(\gamma \) rays, including their first and second escape peaks. In order to resolve the peaks and to determine the high-energy structure of \(^{25}\)F, the experimental spectra were compared to Geant4 simulations taking the complex line shape into account. The observed decomposition of the bump is in good agreement with the results of the two-step fragmentation experiment [Zs. Vajta et al. , submitted to Phys. Rev. C]. Furthermore, an additional transition was observed at 2140(30) keV.

abstract

A new method, based on the excitation of the anti-analog giant dipole resonance (AGDR) in (\(p,n\)) reaction, for measuring the neutron-skin thickness has been tested. The \(\gamma \)-decay of the AGDR to the isobaric analog state (IAS) has been measured. The difference in excitation energy of the AGDR and IAS was calculated. By comparing the theoretical results with the measured one, the \(\Delta R_{pn}\) value for \(^{124}\)Sn was deduced to be \(0.209 \pm 0.066\) fm. The present method provides a new possibility for measuring neutron-skin thickness of very exotic nuclei.

abstract

An unexpected enhancement in the \(\gamma \)-strength function for \(E_\gamma \lt 3\) MeV for Ti, Sc, V, Fe, and Mo nuclei close to the valley of stability has been discovered at the Oslo Cyclotron Laboratory. Provided that this enhancement is present also in very neutron-rich nuclei, it could give an increase in the neutron-capture rates up to two orders of magnitude. However, it is still an open question whether this structure persists when approaching the neutron drip line.

abstract

The \(M1\)-scissors resonance (SR) has been measured for the first time in the quasi-continuum of actinides. Particle-\(\gamma \) coincidences are recorded with deuteron and \(^3\)He induced reactions on \(^{232}\)Th. An unexpectedly strong integrated strength of \(B_{M1} = 11\)–15 \(\mu _{n}^{2}\) is measured in the \(E_{\gamma }=1.0\)–\(3.5\) MeV region. The increased \(\gamma \)-decay probability due to the scissors mode is important for cross-section calculations for future fuel cycles of fast nuclear reactors and may also have impact on stellar nucleosynthesis.

abstract

The electric dipole (\(E1\)) response of \(^{208}{\rm Pb}\) has been precisely determined by proton inelastic scattering measurement at very forward angles. The electric dipole polarizability, which is an inversely energy-weighted sum-rule of the electric dipole strength, has been extracted as \(20.1\!\pm \! 0.6\) fm\(^3\). The data has been used to constrain the neutron skin thickness of \(^{208}\)Pb as \(0.168\pm 0.22\) fm and the slope parameter of the symmetry energy as \(L=46\pm 15\) MeV. The determination of the slope parameter is important for nuclear physics as well as for astrophysical simulations related to neutron stars.

abstract

The effects of the secondary deexcitation on isotopic distributions, commonly used as an observable to extract information on the symmetry energy, hints at the necessity of reconstructing primary fragments from measured quantities. Preliminary results of data measured in the \(4\pi \) detector INDRA and the VAMOS spectrometer presented here open up the possibility of planning a program on charged particle spectroscopy of exotic nuclei.

abstract

The intense, nearly mono-energetic, 100% linearly polarized beams available at the HI\(\gamma \)S facility, along with the realization that the \(E1\)–\(E2\) interference term that appears in the Compton scattering polarization observable has opposite signs in the forward and backward angles, has been shown to make it possible to obtain an order-of-magnitude improvement in the determination of the parameters of the isovector giant quadrupole resonance (IVGQR). The first nucleus which was studied was \(^{209}\)Bi. One surprise was that only 56% of the Isovector \(E2\) Energy Weighted Sum Rule was observed. Preliminary results have now been obtained for the case of \(^{89}\)Y. The parameters in this case suggest an \(A\)-dependence for the energy, width, and sum-rule fraction which is quite intriguing. The method and the results for \(^{209}\)Bi and \(^{89}\)Y will be presented, along with plans for future systematic studies. The possible impact of these results on the nuclear equation of state, which is important for our understanding of nuclear matter under extreme conditions, will be discussed.

abstract

The giant dipole resonance’s (GDR) width and shape at finite temperature and angular momentum are described within the phonon damping model (PDM), which predicts an overall increase in the GDR’s total width at low and moderate temperature \(T\), and its saturation at high \(T\). At \(T\lt 1\) MeV the GDR width remains nearly constant because of thermal pairing. The PDM description is compared with the experimental systematics obtained from heavy-ion fusion, inelastic scattering of light particles on heavy targets, and \(\alpha \) induced fusion reactions, as well as with predictions by other theoretical approaches. The results obtained within the PDM and GDR’s experimental data are also employed to predict the viscosity of hot medium and heavy nuclei.

abstract

The dynamical dipole mode was investigated in the mass region of the \(^{192}\)Pb compound nucleus, by using the \(^{40}\)Ca + \(^{152}\)Sm and \(^{48}\)Ca + \(^{144}\)Sm reactions at \(E_{\mathrm {lab}}=11\) and 10.1 MeV/nucleon, respectively. Both fusion-evaporation and fission events were studied simultaneously for the first time. Our results show that the dynamical dipole mode survives in reactions involving heavier nuclei than those studied previously, however, its yield is lower than that expected within BNV calculations.

abstract

The GEMINI++ simulation code [R.J. Charity, GEMINI: A Code to Simulate the Decay of Compound Nucleus by a Series of Binary Decays, IAEA, Trieste, Italy, 2008, p. 139.] has been extensively used for the description of charged particle decay and fission fragment emission following heavy-ion fusion-reactions. In this paper, we report on enhancing the capabilities of this code by adding the possibility of emission of high-energy gamma rays from the decay of Giant Dipole Resonance (GDR).

abstract

The Coulomb excitation experiment to study electromagnetic structure of low-lying states in \(^{42}\)Ca with a focus on a possible superdeformation in this nucleus was performed at the Laboratori Nazionali di Legnaro in Italy. Preliminary values of the determined quadrupole deformation parameters for both the ground state band and the presumed superdeformed band are presented.

abstract

The production of rare isotopes at facilities such as ISOLDE is often compromised by the presence of intense isobaric contaminant beams. This has necessitated extensive research and development into cleaner production methods, such as the laser ion source, as well optimization of target materials and design. In a few special cases, it has been possible to use these techniques to even produce isomeric beams for spectroscopy and post acceleration. Such selectivity is not possible for all elements and there are still many cases prevented by isobaric contamination. During the last three years a new laser spectroscopy experiment CRIS has been established at ISOLDE that aims to produce a universal method of isotope purification for secondary experiments, such as nuclear spectroscopy. This new technique offers an efficient method for selecting either the ground state or long lived isomeric state \(\gt 1\) ms.

abstract

We present the results of an experiment in which the structure of neutron-rich nuclei located in the vicinity of \(N=40\) was studied. The importance of our results comes from the fact that knowing the behaviour of the neutron \(g_{9/2}\) orbital with increasing neutron number is one of the key points in defining the structure of these nuclei at low excitation energy. Preliminary results on the isomers of \(^{75}\)Cu will be presented together with tentative spin and parity assignments.

abstract

The photofission cross-section of \(^{238}\)U was measured in the sub-barrier energy region as a function of the \(\gamma \) energy using, for the first time, a mono-chromatic, high-brilliance, Compton backscattered \(\gamma \) beam. This prototype experiment was performed at the HI\(\gamma \)S gamma beam facility of the Duke University at Durham (North Carolina, US) using the \(^{238}\)U(\(\gamma ,f\)) reaction at a beam energy varied between \(E_{\gamma }=4.7\)–6.0 MeV and with an energy resolution of \(\Delta E=150\)–200 keV (\(\Delta E/E\approx 3\)%). The photofission cross-section was determined down to \(E^{*}=4.7\) MeV. Indications of transmission resonances have been observed at excitation energies of \(E^*=5.1\) and 5.6 MeV with moderate amplitudes.

abstract

Our work focuses on precision measurements of \(\beta \)-\(\nu \) correlation from the \(\beta \)-decay of \(^{6}\)He by the use of an innovative ion trapping device, the Electrostatic Ion Beam Trap, which incorporates the radioactive ion beam, ion trapping, ion bunching, and a radiation detection system. Production of \(^{6}\)He radioisotopes would be carried out by the use of neutron-induced reactions and for the ionization an Electron Beam Ion Trap would be used.

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We report on tests of LaBr\(_3\):Ce–NaI:Tl phoswich detectors with \(\gamma \)-rays at various \(\gamma \)-ray energies, up to 22.56 MeV, using radioactive sources and nuclear reactions induced by proton beams delivered by accelerators at IFJ PAN Kraków and PLF Mumbai. Two-dimensional analysis of complex waveforms recorded with digital electronics is compared to analog discrimination methods. Both approaches allow to resolve the LaBr\(_3\):Ce and NaI:Tl signal components, and to construct clean associated \(\gamma \)-ray spectra. A digital algorithm to be implemented for the PARIS scintillator array is investigated.

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The \(N = 8\) neutron-rich nucleus \(^{13}\)B has been investigated via the (\(^{18}\)O,\(^{16}\)O) two neutron transfer reaction at 85 MeV. Several excited states are populated in the final nucleus. A comparison with the \(^{12}\)C(\(^{18}\)O,\(^{16}\)O)\(^{14}\)C two neutron transfer reaction at the same incident energy seems to confirm the rapid shell evolution recently observed in the \(N = 8\) systems.

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The quarks \(c\), \(b\) and \(t\) together with the \(\tau \) lepton are commonly labeled as heavy flavors. Studies related to these four elementary particles provide an important window to understanding of the least known aspects of the Standard Model of high energy physics as well as vast opportunities for searches of New Physics. This paper contains a pedagogical introduction to the physics of heavy flavors.

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The ideas in neutrino physics are both, exciting and instructive. In this paper, a subjective review of several fundamental ideas and discoveries in this subject will be presented. We will focus on experimental aspects, starting from the discovery of electron neutrino, about 20 years after neutrino “theoretical birth” by W. Pauli, and finishing with short status of current techniques used in large scale neutrino physics experiments.