Regular Series

Vol. 42 (2011), No. 3 - 4, pp. 365 - 886

Zakopane Conference on Nuclear Physics Extremes of the Nuclear Landscape


Extremes of the Nuclear Landscape: Experimental Studies

Acta Phys. Pol. B 42, 379 (2011)

page 379 •

abstract

Increasingly more intense beams of radioactive isotopes allow moving into unknown areas of the nuclear chart and exploring the limits in nuclear binding and proton-to-neutron ratio. New aspects of nuclear structure and important results for nuclear astrophysics are obtained. The paper provides some overview of experimental developments, facilities and research results; and is intended to set the stage for the many exciting examples of research presented in these proceedings.


Ab Initio Nuclear Theory — Progress and Prospects from Quarks to the Cosmos

Acta Phys. Pol. B 42, 397 (2011)

page 397 •

abstract

The vision of solving the nuclear many-body problem with fundamental interactions tied to QCD appears to approach reality. The goals are to preserve the predictive power of the underlying theory, to test fundamental symmetries with the nucleus as laboratory and to develop new understandings of the full range of complex nuclear phenomena. Recent progress includes the derivation, within chiral perturbation theory (ChPT), of the leading terms of the nucleon–nucleon (NN), three-nucleon (3N) and four-nucleon (4N) potentials. Additional substantial progress includes solving nuclear structure and reactions in nuclei up to mass 16 and selected heavier nuclei around closed shells using these ChPT interactions. Advances in theoretical frameworks (renormalization and many-body methods) as well as in computational resources (new algorithms and leadership-class parallel computers) signal a new generation of theory simulations that will yield valuable insights into origins of nuclear shell structure, collective phenomena and complex reaction dynamics. I outline some recent achievements and present ambitious consensus plans for a coming decade of research that will strengthen the links between nuclear theory and nuclear experiment, between nuclear physics and astrophysics, and between nuclear physics and nuclear energy applications.


Relativistic Energy Density Functionals: Beyond the Mean-field Approximation

Acta Phys. Pol. B 42, 405 (2011)

page 405 •

abstract

Relativistic energy density functionals (EDF) provide a complete and accurate description of nuclear ground states and collective excitations. Employing semi-empirical functionals adjusted to the nuclear matter equation of state and to bulk properties of finite nuclei, this framework has been applied to studies of arbitrarily heavy nuclei, exotic nuclei far from stability, and even systems at the nucleon drip-lines. EDF-based structure models have also been developed that go beyond the static mean-field approximation, and include correlations related to the restoration of broken symmetries and to fluctuations of collective variables.


Isospin Mixing in Nuclei around \(N\simeq Z\) and the Superallowed \(\beta \)-decay

Acta Phys. Pol. B 42, 415 (2011)

page 415 •

abstract

Theoretical approaches that use one-body densities as dynamical variables, such as Hartree–Fock or the density functional theory (DFT), break isospin symmetry both explicitly, by virtue of charge-dependent interactions, and spontaneously. To restore the spontaneously broken isospin symmetry, we implemented the isospin-projection scheme on top of the Skyrme-DFT approach. This development allows for consistent treatment of isospin mixing in both ground and exited nuclear states. In this study, we apply this method to evaluate the isospin impurities in ground states of even–even and odd–odd \(N\simeq Z\) nuclei. By including simultaneous isospin and angular-momentum projection, we compute the isospin-breaking corrections to the \(0^+\rightarrow 0^+\) superallowed \(\beta \)-decay.


The Density Matrix Renormalization Group and the Nuclear Shell Model

Acta Phys. Pol. B 42, 427 (2011)

page 427 •

abstract

We summarize the current status of a program to develop an angular-momentum-conserving variant of the Density Matrix Renormalization Group method into a practical truncation strategy for large-scale shell model calculations of atomic nuclei. Following a brief description of the method, we report the results of systematic test calculations for both even–even and odd-mass nuclei in the \(2p\)–\(1f\) shell. In all, the nucleons are limited to the orbitals of the \(2p\)–\(1f\) shell and interact via the GXPF1A interaction. The calculations systematically converge to the exact diagonalization results, where available. Most importantly, the fraction of the complete space required to achieve a high level of agreement is found to go down rapidly as the size of the full space grows.


full authors' list

K. Kaneko, S. Tazaki, T. Mizusaki, Y. Sun, M. Hasegawa, G. de Angelis

Mirror Energy Difference at High Spins in the Mirror Pair \(^{67}\)Se and \(^{67}\)As

Acta Phys. Pol. B 42, 439 (2011)

page 439 •

abstract

We investigate large mirror energy differences (MED) between high-spin states in the mirror nuclei \(^{67}\)Se and \(^{67}\)As. By employing large-scale shell model calculations, we show that the electromagnetic spin-orbit interaction and the Coulomb monopole radial term are important for the observed large MED in this mirror pair. It is clarified that this large MED is attributed to the proton pair excitations from the \(p_{3/2}\) and \(f_{7/2}\) orbits to the \(g_{9/2}\) orbit and the spin alignment of the \(g_{9/2}\) protons at high spins.


Local QRPA Vibrational and Rotational Inertial Functions for Large-amplitude Quadrupole Collective Dynamics

Acta Phys. Pol. B 42, 443 (2011)

page 443 •

abstract

A new microscopic approach is proposed to derive the five-dimensional quadrupole collective Hamiltonian. It is based on the time-dependent mean-field theory and the adiabatic self-consistent collective coordinate method. We apply the method to studies of oblate–prolate shape coexistence/mixing phenomena and anharmonic vibrations. Experimental data for Se isotopes are well reproduced.


Filter Diagonalization: A New Method for Large-scale Shell-model Calculations

Acta Phys. Pol. B 42, 447 (2011)

page 447 •

abstract

A new method, which is called filter diagonalization, is presented for large-scale shell-model calculations. This method is alternative to the widely used Lanczos method to evaluate shell-model energy and electromagnetic properties. In this contribution, we especially focus on its application to the mirror energy differences (MED) due to small isospin breaking.


Near-threshold Configuration Mixing

Acta Phys. Pol. B 42, 451 (2011)

page 451 •

abstract

The near-threshold mixing of Shell Model (SM) states is studied using the real-energy Continuum Shell Model (CSM). It is shown that the salient features of the configuration mixing can be traced back to the energy dependence of the nearby double-pole of the S-matrix of the complex-extended effective Hamiltonian of the CSM.


On Optimal Shapes of Fissioning and Rotating Nuclei

Acta Phys. Pol. B 42, 455 (2011)

page 455 •

abstract

Following the idea of Strutinsky we have evaluated in a liquid-drop type of approach the shapes of fissioning nuclei along the fission valley in a model independent way. These optimal shapes, which correspond to the minimum of the LD energy for a given elongation, are compared with the shapes obtained in some often used shape parametrisations. The effect of rotation on the optimal shapes of nuclei is discussed within an optimal-shape theory generalised to non-axial forms.


Nuclear Collective Models and Partial Symmetries

Acta Phys. Pol. B 42, 459 (2011)

page 459 •

abstract

It is shown that a mathematical modelling of the collective vibrations in the presence of the tetrahedral symmetry, in contrast to the previous simplistic predictions, may lead to large quadrupole moments \(Q_0\) in the tetrahedral symmetry nuclear bands. Their tetrahedral character originates from the fact that the vibrations take place around a tetrahedral minimum, however, a large amplitude vibrations collect large contributions to \(Q_0\).


A Symmetry of the CPHC Model of Odd–Odd Nuclei and Its Consequences for Properties of \(M1\) and \(E2\) Transitions

Acta Phys. Pol. B 42, 465 (2011)

page 465 •

abstract

A new symmetry of the Core-Particle-Hole Coupling model of odd–odd nuclei is discussed. This symmetry is used to explain a staggering pattern of the \(M1\) and \(E2\) transitions within and between partner bands.


full authors' list

K. Mazurek, J. Dudek, M. Kmiecik, A. Maj, J.P. Wieleczko, D. Rouvel

Poincaré Shape Transitions in Hot Rotating Nuclei

Acta Phys. Pol. B 42, 471 (2011)

page 471 •

abstract

Poincaré shape transitions in hot, fast rotating Barium nuclei have been investigated using a realistic, the so-called Lublin–Strasbourg Drop (LSD) model. In this contribution we present typical forms of the shape evolution of the total energy landscapes in function of spin and isospin selecting for illustration \(^{116}\)Ba, \(^{128}\)Ba, \(^{142}\)Ba and \(^{152}\)Ba isotopes, as representative for the medium-mass \(A\sim 130\) nuclei.


Cluster Radioactivity in \(^{114}\)Ba in the HFB Theory

Acta Phys. Pol. B 42, 477 (2011)

page 477 •

abstract

Cluster radioactivity in \(^{114}\)Ba is described as a spontaneous fission with a large mass asymmetry within the self-consistent HFB theory. A new fission valley with large octupole deformation is found in the potential energy surface. The fragment mass asymmetry of this fission mode corresponds to the expected one in cluster radioactivity with the emission of \(^{16}\)O predicted with a very long half-life.


Multiple Reflection Asymmetric Type Band Structures in \(^{220}\)Th and Dinuclear Model

Acta Phys. Pol. B 42, 481 (2011)

page 481 •

abstract

The lowest negative parity bands in \(^{220}\)Th are analysed within the dinuclear system model. The model is based on the assumption that the cluster type shapes are produced by the collective motion in the mass-asymmetry coordinate. The observed excitation spectrum, angular momentum dependence of the parity splitting and the staggering behaviour of the \(B(E1)\)/\(B(E2)\) ratios are described.


Angular Momentum Dependence of Cluster Emission from Highly Excited Nuclei

Acta Phys. Pol. B 42, 487 (2011)

page 487 •

abstract

Angular momentum dependence of cluster emission from highly excited intermediate nuclear system formed in \(^{93}\)Nb + \(^{9}\)Be and \(^{45}\)Sc + \(^{65}\)Cu reactions is studied within the dinuclear system model. The charge distributions of decay products and partial production cross-sections for C, O, Ne clusters are given.


Fission Rate and Time of Highly Excited Nuclei in Multi-dimensional Stochastic Calculations

Acta Phys. Pol. B 42, 493 (2011)

page 493 •

abstract

A four-dimensional stochastic approach to dynamics of nuclear fission induced by heavy ions was applied to calculations of the fission rate and time of highly excited compound nuclei. The research took into account not only three shape collective coordinates introduced on the basis of the \(\{c,h,\alpha \}\)-parametrization but also orientation degree of freedom (\(K\)-state) — spin about the symmetry axis. Overdamped Langevin equation was used to describe the evolution of the \(K\)-state. Impact of orientation degree of freedom on the fission rate and time of the compound nuclei was studied in detail for the reactions with high-energy projectiles \(^{14}\)N and \(^{16}\)O on target nuclei \(^{197}\)Au, \(^{208}\)Pb, \(^{232}\)Th and \(^{238}\)U. It was revealed that inclusion of the \(K\)-state in the dynamical model produces considerable increase in the mean fission time and decrease in the stationary fission rate. The \(K\)-state impact on the fission rate and time almost fully canceled the opposite effect produced by inclusion of nuclear neck and mass-asymmetry coordinates in the 1D Langevin calculations. The difference of 5–25% between 4D and 1D calculations was found as the result of this research.


The Effect of Valence Neutrons on Spin–Orbit Splitting

Acta Phys. Pol. B 42, 497 (2011)

page 497 •

abstract

We study the splitting of single-particle energies between spin–orbit partners (ls splitting) for the isotopic chains of some even–even closed shell nuclei in the Hartree–Fock–Bogolyubov framework. \(Z=8\), 20, 28 and 50 magic proton nuclei of stability valley and their even–even neighbours are selected and a limited systematic investigation is performed for the isotopic chains of C, O, Si, Ca, Ni, Sr, Sn, Te, and Ce isotopes. They are compared with existing data. The modification of proton spin–orbit partners energy splitting of those isotopes is investigated with valence neutron numbers extending to the neutron drip-line. Our calculation shows that the proton ls splitting in chosen nuclei becomes smaller with the increasing neutron number. This reduction is accounted for two different effects, namely, the effect of neutron diffuseness and tensor interaction. The neutron diffuseness values are also calculated for the nuclei under investigation. The deduced ls splitting reduction is compared for the nuclei with the same isospin number. The larger reduction is attributed to the tensor interaction assuming that the ls reduction due to the neutron surface thickness will be the same for the nuclei having the same neutron diffuseness parameter. The contribution from tensor interaction is mainly accounted for the interaction between the spin–orbit partner proton orbital and the neutron orbital having different angular momentum. Briefly, the effect of increased valence neutron number on proton effective single particle levels is discussed.


Relative Even and Odd Parity Levels within the Nuclei in the Iron Region

Acta Phys. Pol. B 42, 505 (2011)

page 505 •

abstract

In the current study, the ratio of the nuclear level densities with odd and even parities for \(^{58}\)Fe were calculated and compared with those of \(^{60}\)Ni, using a microscopic–macroscopic computational method. It was shown that the level densities of odd and even parities for even–even nuclei are not equal at low energies. However, increasing excitation energy reduces the difference between odd and even parities and equality is gained gradually.


Recent Results on Neutron-rich Nuclei

Acta Phys. Pol. B 42, 509 (2011)

page 509 •

abstract

The study of the nuclear landscape on the neutron-rich side of the valley of stability has seen recent developments in the past few years at the NSCL. Progress has been made using a wide variety of methods and reaction probes, all based on the availability of fast radioactive beams produced via the projectile fragmentation technique. I will discuss the evolution of shell structure in neutron-rich nuclei located across the \(sd\) and \(fp\) shells, based on various results obtained, ranging from the discovery of the most neutron-rich nuclei in that region, to in-beam \(\gamma \)-ray spectroscopy using various reactions such as knockout of one or two nucleons, as well as inelastic scattering.


The Structure of Neutron-rich Nuclei Studied by Deep Inelastic Reactions: Recent Results from LNL

Acta Phys. Pol. B 42, 519 (2011)

page 519 •

abstract

The evolution of nuclear properties as a function of the neutron excess depends on how the shell structure changes. This evolution has consequences on the ground state properties and on the single-particle and collective excitations. Presently, our knowledge about the structure of nuclei is mostly limited to nuclei close to the valley of stability or nuclei with a deficiency of neutrons. Only recently the availability of beams of unstable ions has given access to unexplored regions of the nuclear chart, especially on the neutron-rich side. A complementary way to study the structure of neutron-rich nuclear systems is offered by the use of high intensity beams of stable ions and binary reactions. Multi-nucleon and deep-inelastic reactions are a powerful tool to populate medium- and high-spin states in moderately neutron-rich systems. In this article, I will discuss some selected examples studied using the novel experimental setup that combines the large acceptance magnetic spectrometer, PRISMA, and the high-efficiency \(\gamma \)-ray detection arrays, CLARA and AGATA. They show the high potential of such reaction mechanism for the study of the spectroscopic properties of neutron-rich nuclear systems.


Nuclear Structure Studies of Neutron-rich Nuclei Performed by JYFLTRAP

Acta Phys. Pol. B 42, 529 (2011)

page 529 •

abstract

A wide range of studies on neutron-rich fission fragments have been performed at the University of Jyväskylä by using the JYFLTRAP double Penning trap setup coupled to the Ion Guide Isotope Separator On-Line (IGISOL) mass separator. Experimental results from high-precision mass measurements and decay spectroscopy measurements enables investigation of the nuclear structure of exotic neutron-rich isotopes.


full authors' list

L. Cáceres, D. Sohler, S. Grévy, C. Force, O. Sorlin, Zs. Dombrádi, L. Gaudefroy, N.L. Achouri, J.C. Angélique, F. Azaiez, D. Bayborodin, B. Bastin, R. Borcea, C. Bourgeois, A. Buta, A. Bürger, R. Chapman, J.C. Dalouzy, Z. Dlouhy, A. Drouard, Z. Elekes, S. Franchoo, S. Iacob, B. Laurent, M. Lazar, X. Liang, E. Liénard, J. Mrazek, L. Nalpas, F. Negoita, N.A. Orr, Y. Penionzhkevich, Zs. Podolyák, F. Pougheon, P. Roussel-Chomaz, M.G. Saint-Laurent, M. Stanoiu, I. Stefan, F. Nowacki, A. Poves

Shells and Shapes in the \(^{44}\)S Nucleus

Acta Phys. Pol. B 42, 533 (2011)

page 533 •

abstract

The results obtained from electron and in-beam spectroscopy experiments reveal that the \(^{44}\)S nucleus is located in a transitional region between the spherical \(^{48}\)Ca and the oblate \(^{42}\)Si. The comparison of the results with Large Scale Shell Model calculations points towards prolate-spherical shape coexistence where the ground state becomes the intruder configuration due to quadrupole excitations across the \(Z=14\) and \(N=28\) shell gaps.


full authors' list

M. Niikura, B. Mouginot, F. Azaiez, G. De Angelis, M. Assie, P. Bednarczyk, C. Borcea, A. Burger, G. Burgunder, A. Buta, L. Cáceres, E. Clément, L. Coquard, G. De France, F. De Oliveira, A. Dewald, A. Dijon, Z. Dombradi, E. Fiori, S. Franchoo, C. Fransen, G. Friessner, L. Gaudefroy, G. Georgiev, S. Grévy, M. Hackstein, M.N. Harakeh, F. Ibrahim, M. Kmiecik, R. Lozeva, A. Maj, I. Matea, C. Mihai, O. Möller, S. Myalski, F. Negoita, D. Pantelica, L. Perrot, T. Pissula, F. Rotaru, W. Rother, J.A. Scarpaci, I. Stefan, C. Stodel, J.C. Thomas, P. Ujic, D. Verney

Lifetime Measurement of 2\(^+_1\) State in \(^{74}\)Zn with Differential Plunger Technique

Acta Phys. Pol. B 42, 537 (2011)

page 537 •

abstract

We have measured the lifetime of the 2\(^+_1\) state in \(^{74}\)Zn by the recoil distance Doppler-shift method at GANIL. It resulted to be of 27.6(43) ps and is consistent with previously measured values of transition rates from Coulomb excitation measurements.


full authors' list

M. Moukaddam, G. Duchêne, D. Beaumel, J. Burgunder, L. Caceres, E. Clement, D. Curien, F. Didierjean, B. Fernandez, Ch. Finck, F. Flavigny, S. Franchoo, J. Gibelin, S. Giron, A. Gillibert, A. Goasduff, S. Grevy, J. Guillot, F. Haas, F. Hammache, M.N. Harakeh, K. Kemper, V. Lapoux, Y. Matea, A. Matta, L. Nalpas, F. Nowacki, A. Obertelli, J. Pancin, L. Perrot, J. Piot, E. Pllumbi, R. Raabe, J.A. Scarpaci, N. de Séréville, K. Sieja, O. Sorlin, I. Stefan, C. Stoedel, J.C. Thomas

Search for 2\(d_{5/2}\) Neutron States in \(^{69}\)Ni

Acta Phys. Pol. B 42, 541 (2011)

page 541 •

abstract

It has been shown that the neutron \(2d_{5/2}\) orbital has to be included in shell-model calculations to explain the large quadrupole collectivity observed in the Fe and Cr of \(N=40\) region, probably a new island of inversion similar to the one known for light nuclei around \(N=20\). Indeed, in these calculations using a large valence neutron space, the position, i.e. the single-particle energy, of the \(2d_{5/2}\) orbital is a crucial ingredient. The experiment discussed in this paper aims to determine the \(\nu 1g_{9/2}\)–\(\nu 2d_{5/2}\) gap using the neutron stripping reaction \(d(^{68}{\rm Ni},p)^{68}\)Ni which has been performed at GANIL in inverse kinematics. Preliminary results are presented.


full authors' list

B. Blank, P. Ascher, L. Audirac, G. Canchel, J. Giovinazzo, T. Kurtukian-Nieto, F. de Oliveira Santos, S. Grévy, J.-C. Thomas, C. Borcea, L.V. Grigorenko

Two-proton Radioactivity as a Tool of Nuclear Structure Studies

Acta Phys. Pol. B 42, 545 (2011)

page 545 •

abstract

New results on two-proton radioactivity, predicted 50 years ago and observed for the first time in 2002, are presented. These results have been obtained with a time projection chamber at the LISE3 facility of GANIL. After \(^{45}\)Fe, the direct observation of the two protons for \(^{54}\)Zn is only the second such case from a long lived ground-state two-proton emitter. The new results are discussed and future perspectives highlighted.


Recent Advances in Theoretical Studies of \(2p\) Radioactivity: Nuclear Many-body Structure in Three-body Model

Acta Phys. Pol. B 42, 555 (2011)

page 555 •

abstract

Nowadays quantum-mechanical three-cluster theory allows one to reliably calculate the processes of \(2p\) radioactivity (true three-body decays) and the corresponding energy and angular correlations. However, the connection of the three-cluster final state configuration with possibly many-body internal structure of the nucleus is unclear in this approach. A simple method for taking into account the many-body structure in the three-body decay calculations was developed. The results of the relativistic mean field (RMF) calculations are used as an input for the three-cluster decay model. The calculations for the prospective two-proton emitter \(^{26}\)S are provided.


Mass Measurements of Proton-rich Nuclei with JYFLTRAP

Acta Phys. Pol. B 42, 559 (2011)

page 559 •

abstract

The Penning trap setup JYFLTRAP, connected to the IGISOL facility, has been extensively used for atomic mass measurements of exotic nuclei. On the proton rich side of the chart of nuclei mass measurements have mostly contributed to fundamental physics and nuclear astrophysics studies with about 100 atomic masses measured.


Proton-rich Nuclei Studied with RISING

Acta Phys. Pol. B 42, 567 (2011)

page 567 •

abstract

During the years 2006 to 2009, Rare Isotope Spectroscopic INvestigations at GSI (RISING) have focused on high-resolution \(\gamma \)-ray spectroscopy of exotic nuclear species at rest: following unambiguous discrimination and identification by the FRagment Separator (FRS) and its suite of detectors, the nuclei of interest were implanted in either a passive stopper or a stack of silicon detectors to allow for measurements of delayed ion–\(\gamma (\gamma )\) or ion–\(\beta \)–\(\gamma (\gamma )\) correlations. Results concerning experiments along the \(N\sim Z\) line are summarised.


Superheavy Elements at GSI — Investigating Exotic Nuclear Matter

Acta Phys. Pol. B 42, 577 (2011)

page 577 •

abstract

The search for the next closed proton and neutron shells beyond \(^{208}\)Pb has yielded a number of exciting results in terms of the synthesis of new elements at the upper end of the charts of nuclides, in a region of exotic high-\(Z\) nuclear matter. In particular, the results obtained at the Flerov Laboratory of Nuclear Reactions (FLNR) for a rich number of decay patterns for \(^{48}\)Ca induced reactions on actinide targets have by now been confirmed for reactions on \(^{238}\)U, \(^{244}\)Pu and \(^{248}\)Cm at GSI, and on \(^{242}\)Pu at LBNL. These superheavy elements (SHE), however, are a nuclear structure phenomenon. They owe their existence to shell effects, an energy contribution of quantum mechanical origin to the nuclear potential, without which they would not be bound. Experimental activities in this field, apart from attempts to directly synthesize new elements, have to pursue reaction mechanism studies and, in particular, nuclear structure investigations to study the development of single particle levels towards the expected gap for the proton and neutron shell closure in the region of the spherical SHE.


Gamma and Electron Spectroscopy of the Heaviest Elements

Acta Phys. Pol. B 42, 587 (2011)

page 587 •

abstract

The production and spectroscopic study of the heaviest elements has always been a central theme of nuclear physics. In recent years, a wealth of new data has been produced, both in terms of new elements (up to \(Z=118\)) and in detailed spectroscopic studies of nuclei with masses above 240. Such studies provide data concerning nuclear parameters such as masses, decay modes, half-lives, moments of inertia and single-particle properties in systems with the highest possible number of protons. The main focus of current experiments is the search for the next closed proton- and neutron- shells beyond the doubly magic \(^{208}\)Pb. This search can be made directly, by producing nuclei in the region of interest (\(Z\gt 112\) and \(N\gt 176\)), or indirectly through the study of lighter deformed nuclei where the orbitals of interest at sphericity are active at the Fermi surface. In the latter case, the production cross-section is large enough to permit detailed in-beam and decay spectroscopic studies. These studies employ state-of-the art spectrometers such as the JUROGAM array of germanium detectors or the newly-commissioned SAGE combined conversion electron and gamma-ray spectrometer. Examples of recent highlights in studies of deformed heavy nuclei, along with the opportunities provided by current and future facilities to extend these studies are reviewed.


full authors' list

B.J.P. Gall, J. Piot, O. Dorvaux, K. Hauschild, A. Khouaja, M. Lamberti, A. Lopez-Martens, R.L. Lozeva, J. Pancin

Pushing the Limits of Spectroscopy with S\(^{3}\)

Acta Phys. Pol. B 42, 597 (2011)

page 597 •

abstract

Designed in the framework of the SPIRAL2 project, the Super Separator Spectrometer (S\(^3\)) will benefit from unprecedented high intensity stable beams available at the new LINAG accelerator. It will open new horizons for the physics of rare nuclei and low production cross-section nuclei at the extreme limits of the nuclear chart. A research and development program has been launched in order to optimize the S\(^3\) focal-plane detection according to the three main physics cases: Synthesis of new Super Heavy Elements, Spectroscopy of Very and Super Heavy Elements and Spectroscopy of neutron-deficient nuclei around \(^{100}\)Sn.


full authors' list

T.W. Hagen, A. Lopez-Martens, K. Hauschild, A.V. Belozerov, M.L. Chelnokov, V.I. Chepigin, D. Curien, O. Dorvaux, G. Drafta, B. Gall, A. Görgen, M. Guttormsen, A.V. Isaev, I.N. Izosimov, A.P. Kabachenko, D.E. Katrasev, T. Kutsarova, A.N. Kuznetsov, A.C. Larsen, O.N. Malyshev, A. Minkova, S. Mullins, H.T. Nyhus, D. Pantelica, J. Piot, A.G. Popeko, S. Saro, N. Scintee, S. Siem, E.A. Sokol, A.I. Svirikhin, A.V. Yeremin

Spectroscopy of Transfermium Nuclei Using the GABRIELA Setup

Acta Phys. Pol. B 42, 605 (2011)

page 605 •

abstract

Heavy elements above Fm (\(Z=100\)) are nuclei with vanishing liquid-drop fission barriers and are therefore entirely stabilized by quantum shell effects. Due to the large density of single-particle levels and strong polarized Coulomb fields, theoretical predictions of magic numbers are extremely model dependent. Furthermore, shell closures for one nucleon species depend strongly on the number of the other species. Reliable experimental data is needed in order to test and constrain theory. As there is a lack of such data in the region, new data is needed along with the confirmation of previous data. A detection system dedicated to the spectroscopy of transfermium nuclei was constructed in 2004 and installed at the focal plane of the VASSILISSA separator at the FLNR, Dubna, by a Franco–Russian collaboration. The results from the 2009 campaign will be presented.


Self-consistent Description of Nuclear Photoabsorption Cross-sections

Acta Phys. Pol. B 42, 609 (2011)

page 609 •

abstract

Several approaches to photonuclear reactions, based on the time-dependent density-functional theory, have been developed recently. The standard linearization leads to the random-phase approximation (RPA) or the quasiparticle-random-phase approximation (QRPA). We have developed a parallelized QRPA computer program for axially deformed nuclei. We also present a feasible approach to the (Q)RPA calculation, that is the finite amplitude method (FAM). We show results of photoabsorption cross-sections for deformed nuclei using the QRPA and FAM calculations. Finally, the canonical-basis approach to the time-dependent Hartree–Fock–Bogoliubov method is presented, to demonstrate its feasibility and usefulness.


full authors' list

A. Corsi, A. Giaz, A. Bracco, F. Camera, F.C.L. Crespi, S. Leoni, R. Nicolini, V. Vandone, O. Wieland, G. Benzoni, N. Blasi, S. Brambilla, B. Million, S. Barlini, L. Bardelli, M. Bini, G. Casini, A. Nannini, G. Pasquali, G. Poggi, S. Carboni, V.L. Kravchuk, M. Cinausero, M. Degerlier, F. Gramegna, T. Marchi, D. Montanari, G. Baiocco, M. Bruno, M. D’Agostino, L. Morelli, S. Sambi, G. Vannini, M. Ciemala, M. Kmiecik, A. Maj, K. Mazurek, W. Meczynski, S. Myalski, D. Santonocito, R. Alba, C. Maiolino, M. Colonna, M. Di Toro, C. Rizzo

Prompt High Energy Dipole \(\gamma \) Emission

Acta Phys. Pol. B 42, 619 (2011)

page 619 •

abstract

The study of the collective properties of a nuclear system is a powerful tool to understand the structure which lies inside the nucleus. A successful technique which has been used in this field is the measurement of the \(\gamma \)-decay of the highly collective Giant Dipole Resonance (GDR). In fact, GDR can be used as a probe for the internal structure of hot nuclei and, in addition, constitutes a clock for the thermalization process. Using the fusion–evaporation reaction, it has been recently possible to study (i) the yield of the high-energy \(\gamma \)-ray emission of the Dynamical Dipole which takes place during the fusion process and (ii) the degree of isospin mixing at high temperature in the decay of \(^{80}\)Zr. In the first case it is important to stress the fact that the predictions of the theoretical models might differ depending on the type of nuclear equation of state (EOS) and on the \(N\)–\(N\) in-medium cross-section used in the calculations while, in the second physics case, the data are relative to the heaviest \(N=Z\) nucleus which has been possible to populate in the \(I=0\) channel using fusion–evaporation reaction. Both experiments were performed at the Laboratori Nazionali di Legnaro using the HECTOR-GARFIELD array. The high-energy \(\gamma \)-rays were measured in coincidence with light charged particles and fusion–evaporation residues.

Version corrected according to Erratum Acta Phys. Pol. B 44, 675 (2013)


full authors' list

C. Parascandolo, D. Pierroutsakou, R. Silvestri, C. Agodi, R. Alba, V. Baran, A. Boiano, M. Colonna, R. Coniglione, E. De Filippo, A. Del Zoppo, M. Di Toro, U. Emanuele, F. Farinon, A. Guglielmetti, G. Inglima, M. La Commara, C. Maiolino, B. Martin, M. Mazzocco, C. Mazzocchi, P. Molini, C. Rizzo, M. Romoli, M. Sandoli, D. Santonocito, C. Signorini, F. Soramel, A. Trifirò, M. Trimarchi

Investigation of the Dynamical Dipole Mode in the \(^{192}\)Pb Mass Region

Acta Phys. Pol. B 42, 629 (2011)

page 629 •

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\(_{\rm lab}=11\) and 10.1 MeV/nucleon, respectively. Both fusion–evaporation and fission events were studied simultaneously for the first time. Preliminary results obtained with a part of the collected statistics show that the dynamical dipole mode survives in reactions involving heavier mass reaction partners than those investigated in our previous works. As it represents a fast cooling mechanism on the fusion path, it could be used to favor the synthesis of super heavy elements through “hot” fusion reactions.


full authors' list

M. Ciemała, M. Kmiecik, V.L. Kravchuk, A. Maj, S. Barlini, G. Casini, F. Gramegna, F. Camera, A. Corsi, L. Bardelli, P. Bednarczyk, B. Fornal, M. Matejska-Minda, K. Mazurek, W. Męczyński, S. Myalski, J. Styczeń, B. Szpak, M. Ziębliński, M. Cinausero, T. Marchi, V. Rizzi, G. Prete, M. Degerlier, G. Benzoni, N. Blasi, A. Bracco, S. Brambilla, F. Crespi, S. Leoni, B. Million, O. Wieland, D. Montanari, R. Nicolini, A. Giaz, V. Vandone, G. Baiocco, M. Bruno, M. D'Agostino, L. Morelli, G. Vannini, M. Chiari, A. Nannini, S. Piantelli, A. Chbihi, J.P. Wieleczko, I. Mazumdar, O. Roberts, J. Dudek

Search for Jacobi Shape Transition in Hot Rotating \(^{88}\)Mo Nuclei Through Giant Dipole Resonance Decay

Acta Phys. Pol. B 42, 633 (2011)

page 633 •

abstract

We report on preliminary results from the experiment performed at Legnaro National Laboratories aiming at the investigation of the shape evolution of the \(^{88}\)Mo nucleus. The GDR spectra obtained for two data sets measured at \(^{48}\)Ti beam energy of 300 and 450 MeV corresponding to 3 and 3.8 MeV temperatures, respectively, are presented. The low energy component in GDR strength functions, similar to the theoretical predictions of LSD model, possibly indicates the presence of Jacobi shape transition.


full authors' list

S. Barlini, S. Carboni, M. Ciemala, V.L. Kravchuk, L. Bardelli, M. Bini, G. Casini, A. Nannini, G. Pasquali, M. Kmiecik, A. Maj, M. Zieblinski, M. Cinausero, M. Degerlier, F. Gramegna, T. Marchi, G. Baiocco, M. Bruno, M. D'Agostino, L. Morelli, F. Camera, A. Corsi, F.C.L. Crespi, D. Montanari, O. Wieland

Light Charged Particles Distribution and Fission Fragments Selection in \(^{48}\)Ti+\(^{40}\)Ca at 600 MeV

Acta Phys. Pol. B 42, 639 (2011)

page 639 •

abstract

The reactions \(^{48}{\rm Ti}+^{40}\)Ca at 600, 450 and 300 MeV were employed at the Laboratori Nazionali di Legnaro (LNL) to investigate the charged particles and the Giant Dipole Resonance (GDR) decay of hot rotating \(^{88}\)Mo nuclei. Some preliminary results about Light Charged Particles (LCP) distribution in coincidence with Evaporation Residues (ER) and fusion–fission events selection are shown.


Shape Transition and Isovector Giant Quadrupole Resonance Decay in Hot Rotating Nuclei

Acta Phys. Pol. B 42, 643 (2011)

page 643 •

abstract

We provide a brief review of our activities involving high energy gamma decay from hot-rotating nuclei. The two primary goals of this ongoing programme is to search for rare shape-phase transitions in heavy (\(A\sim 190\)) nuclei, from the analysis of the giant dipole resonance (GDR) gamma ray spectra and also to search for the Isovector Giant Quadrupole Resonance (IVGQR) based upon excited states. The efforts to carry out the exclusive measurements have resulted in the setting up of a sum-spin spectrometer in complete \(4\pi \) configuration. The performance of this spin-spectrometer will be presented in brief. In addition, this paper also presents the results of our studies with lanthanum bromide detectors of different sizes and configurations using low energy sources and in-beam measurements. The finite temperature potential energy surface calculations, carried out to guide the measurements, will also be discussed.


full authors' list

R. Nicolini, A. Bracco, D. Mengoni, S. Leoni, F. Camera, D. Bazzacco, E. Farnea, A. Gadea, F. Birocchi, A. Camplani, A. Corsi, F.C.L. Crespi, A. Giaz, L. Pellegri, S. Riboldi, V. Vandone, G. Benzoni, N. Blasi, C. Boiano, S. Brambilla, B. Million, O. Wieland, M. Bellato, A. Gottardo, R. Isocrate, C. Michelagnoli, D. Montanari, F. Recchia, C. Ur, D. Bortolato, E. Calore, P. Molini, D.R. Napoli, E. Sahin, J.J. Valiente-Dobon, M. Ciemala, M. Kmiecik, A. Maj, S. Myalski, A. Bürger, R. Kempley, P. Reiter

Study of High-lying States in \(^{208}\)Pb with the AGATA Demonstrator

Acta Phys. Pol. B 42, 653 (2011)

page 653 •

abstract

An experiment aiming at the study of the gamma decay from the Giant Resonance region in the nuclei \(^{208}\)Pb, \(^{90}\)Zr has recently been performed with the AGATA Demonstrator coupled to an array of large volume scintillators (LaBr\(_3\):Ce, BaF\(_2\)) to increase the overall gamma detection efficiency. The \(^{208}\)Pb and \(^{90}\)Zr nuclei were excited with the inelastic scattering of \(^{17}\)O at the incident energy of 20 MeV/u. The ejectiles were detected in a pair of silicon \(E\)–\(\Delta E\) telescopes placed at forward angles. Preliminary results concerning the first partial analysis of the measurement with the \(^{208}\)Pb target are here presented.


The Asymmetry Term in the Nuclear-matter Incompressibility from Measurements on the Giant Monopole Resonance: An Update

Acta Phys. Pol. B 42, 659 (2011)

page 659 •

abstract

We have investigated the isoscalar giant monopole resonances (ISGMR) in \(^{112-124}\)Sn and \(^{106-116}\)Cd nuclei using inelastic scattering of 386-MeV \(\alpha \)-particles at extremely forward angles, including 0\(^\circ \). The strength distributions for various multipoles were extracted by a multipole decomposition analysis based on the expected angular distributions of the respective multipoles. From the ISGMR results, a value of \(K_{\tau } \sim -500\) MeV is obtained for the asymmetry term in the nuclear incompressibility.


full authors' list

L. Stuhl, A. Krasznahorkay, M. Csatlós, T. Adachi, A. Algora, J. Deaven, E. Estevez, H. Fujita, Y. Fujita, C. Guess, J. Gulyás, K. Hatanaka, K. Hirota, H.J. Ong, D. Ishikawa, H. Matsubara, R. Meharchand, F. Molina, H. Okamura, G. Perdikakis, B. Rubio, C. Scholl, T. Suzuki, G. Susoy, A. Tamii, J. Thies, R. Zegers, J. Zenihiro

High Resolution Study of the Relative Dipole Strength Distribution in Sc Isotopes

Acta Phys. Pol. B 42, 667 (2011)

page 667 •

abstract

Experimental data from the Ca(\(^3\)He,t)Sc charge exchange reaction on the targets \(^{40, 42, 44, 48} \)Ca at \(420\) MeV beam energy are presented. The achieved energy resolution of \(20\) keV, and the measured angular distributions allowed the extraction of the dipole strength for excitation energies lower than 15 MeV in the Sc isotopes for the first time. The possible existence of a new type soft dipole vibration mode is dicussed.


full authors' list

W. Reviol, D.G. Sarantites, X. Chen, M. Montero, O.L. Pechenaya, J. Snyder, R.V.F. Janssens, M.P. Carpenter, C.J. Chiara, T.L. Khoo, T. Lauritsen, C.J. Lister, D. Seweryniak, S. Zhu, K. Hauschild, A. Lopez-Martens, D.J. Hartley, S. Frauendorf

Tidal Waves and Onset of Collectivity above \(N =\) 126

Acta Phys. Pol. B 42, 671 (2011)

page 671 •

abstract

Recent experiments in the actinide region, using Gammasphere and the evaporation residue detector HERCULES, have covered the territory between \(N=126\) and the center of static octupole deformation at \(N=134\). The \(^{220}\)Th nucleus and the neighboring \(^{218}\)Ra and \(^{219}\)Th nuclei mark the emergence of quadrupole–octupole collectivity in this mass region. Their octupole bands have \(B(E1)\)/\(B(E2)\) ratios which are typical for the region, but the level spacings do not concur with a rotational-like behavior. In addition, a spin-dependent staggering of the \(B(E1)\)/\(B(E2)\) ratios is evident. These features can be described, based on a phonon picture, by a constant-frequency tidal-wave mode for a reflection-asymmetric nuclear surface.


Reaction Dynamics and Nuclear Structure Studies of \(N\)-rich Nuclei around \(^{48}\)Ca via Deep Inelastic Collisions with Heavy-Ions

Acta Phys. Pol. B 42, 681 (2011)

page 681 •

abstract

The population and \(\gamma \) decay of neutron rich nuclei around \(^{48}\)Ca has been measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using deep-inelastic collisions on \(^{64}\)Ni, at 5.9 MeV/\(A\). The reaction properties of the main products are investigated, focusing on total cross-sections and energy integrated angular distributions. Gamma spectroscopy studies are also performed for the most intense transfer channels, making use of angular distributions and polarization measurements to firmly establish spin and parity of the excited states. In the case of \(^{49}\)Ca candidates for particle-core couplings are investigated and interpreted on basis of lifetime measurements and comparison with model predictions.


Neutron-rich Nuclei Populated in Deep-inelastic Collisions: New Studies of the Redistribution of Protons and Neutrons

Acta Phys. Pol. B 42, 689 (2011)

page 689 •

abstract

The redistribution of protons and neutrons between nuclei in deep-inelastic collisions is discussed in terms of the \(N/Z\) ratio equilibration. Experimentally established product yield distributions are used for comparison with two sets of model predictions. The present and perspective use of deep-inelastic reactions for spectroscopic studies of exotic neutron-rich nuclei is discussed.


full authors' list

N. Buyukcizmeci, F. Bulut, M. Erdogan, H. Imal, R. Ogul, A.S. Botvina, I.N. Mishustin, W. Trautmann

Investigating the Isotopic Effects in Nuclear Fragmentation

Acta Phys. Pol. B 42, 697 (2011)

page 697 •

abstract

Modifications for symmetry energy coefficients of nuclear matter at freeze-out density are investigated on the basis of the Statistical Multifragmentation Model (SMM). In order to compare our predictions with MSU experimental data we consider the fragmentation of the projectiles \(^{124}\)Sn and \(^{112}\)Sn which were also used for the MSU experiments, and of the projectiles \(^{124}\)Sn, \(^{124}\)La and \(^{107}\)Sn used for the ALADIN experiments. Comparing our results with the experimental data, it is confirmed that a significant reduction of the symmetry term coefficient is found necessary to reproduce the mean \(\langle N\rangle /Z\) values of light fragments.


full authors' list

I. Lombardo, C. Agodi, F. Amorini, A. Anzalone, L. Auditore, I. Berceanu, G. Cardella, S. Cavallaro, E. DeFilippo, G. Giuliani, E. Geraci, L. Grassi, J. Han, E. LaGuidara, G. Lanzalone, D. Loria, C. Maiolino, A. Pagano, M. Papa, S. Pirrone, G. Politi, F. Porto, F. Rizzo, P. Russotto, A. Trifirò, M. Trimarchi, G. Verde, M. Vigilante

The Strong Role of \(N/Z\) Degree of Freedom in Ca+Ca Reactions at 25 MeV/Nucleon

Acta Phys. Pol. B 42, 701 (2011)

page 701 •

abstract

Isospin effects on dynamics of semi-central collisions involving \(^{40}\)Ca+\(^{40}\)Ca, \(^{40}\)Ca+\(^{48}\)Ca and \(^{48}\)Ca+\(^{48}\)Ca reactions at 25 MeV/nucleon have been investigated. For the selected class of events, the balance between the emission of evaporation residues and the presence of binary-like phenomena seems to be influenced by the neutron to proton ratio (\(N/Z\)) of entrance channels. In particular, for neutron-rich systems, evaporation residue emission is enhanced. Experimental observations confirm the key role played by the \(N/Z\) degree of freedom on nuclear dynamics at 25 MeV/nucleon.


Relativistic Coulomb Excitation: From RISING to PreSPEC

Acta Phys. Pol. B 42, 705 (2011)

page 705 •

abstract

The new PreSPEC project will be presented with an advanced particle (LYCCA) and \(\gamma \)-ray (AGATA) detection system as compared to the RISING set-up. This contribution focuses on planned Coulomb excitation experiments at relativistic energies. Characteristic parameters are presented, followed by the experimental conditions for experiments at 100 A MeV and feasibility studies for future measurements.


full authors' list

R.S. Kempley, Zs. Podolyák, D. Bazzacco, A. Gadea, E. Farnea, J.J. Valiente-Dobón, D. Mengoni, F. Recchia, E. Sahin, A. Gottardo, L. Corradi, E. Fioretto, S. Szilner, V. Anagnostatou, N. Al-Dahan, G. De Angelis, M. Bellato, B. Berti, D. Bortolato, M. Bowry, M. Bunce, P. Cocconi, A. Colombo, Zs. Dombrádi, C. Fanin, W. Gelletly, R. Isocrate, S. Ketenci, N. Kondratyev, I. Kuti, P.J.R. Mason, C. Michelagnoli, T. Mijatovic, P. Molini, G. Montagnioli, D. Montanari, M. Nakhostin, D.R. Napoli, D. Pellegrini, P.H. Regan, G. Rampazzo, P. Reiter, D. Rosso, F. Scarlassara, A. Stefanini, P. Singh, N. Toniolo, C.A. Ur

Cross-coincidences in the \(^{136}\)Xe+\(^{208}\)Pb Deep-inelastic Reaction

Acta Phys. Pol. B 42, 717 (2011)

page 717 •

abstract

A deep-inelastic reaction experiment with a \(^{136}\)Xe beam impinging on a \(^{208}\)Pb target was performed. Gamma rays were detected with the AGATA Demonstrator. The beam-like fragments were identified with the PRISMA spectrometer on event-by-event basis. Doppler corrected \(\gamma \)-ray spectra were obtained for both the identified beam-like nuclei and for the target-like binary partners. This cross-coincidence method can be used to study heavy target-like nuclei which cannot be unambiguously identified in the spectrometer due to their large masses and low velocities.


full authors' list

D. Lebhertz, M. Ciemała, S. Courtin, A. Goasduff, D.G. Jenkins, M. Labiche, O. Roberts, O. Stezowski

Performances of the Future Multidetector PARIS Illustrated on the Radiative Capture Physics Case

Acta Phys. Pol. B 42, 721 (2011)

page 721 •

abstract

The future \(\gamma \)-multidetector PARIS for SPIRAL2 will be an array composed of the recently developed LaBr\(_{3}\) scintillators. It is dedicated to the study of the \(\gamma \)-radiation from hot nuclei. Different physics cases are proposed for this detector: one of them is the radiative capture of light-heavy ions. This paper presents a status of knowledge for this physics case and shows which improvements could be provided by the use of PARIS illustrated in the case of \(^{12}\)C(\(^{16}\)O,\(\gamma \))\(^{28}\)Si.


full authors' list

F. Naqvi, P. Boutachkov, M. Górska, J. Gerl, F. Farinon, E.T. Gregor, K. Hadynska, A. Jhingan, R. Janik, I. Kojouharov, N.A. Kondratyev, M.A.G. Alvarez, I. Mukha, P. Napiorkowski, C. Nociforo, D. Pietak, W. Prokopowicz, S. Pietri, A. Prochazka, H. Schaffner, P. Strmen, H. Weick, H.J. Wollersheim

Development of Slowed Down Beams at the Fragment Separator for FAIR

Acta Phys. Pol. B 42, 725 (2011)

page 725 •

abstract

The feasibility studies of the slowed down beam setup involving deceleration of a \(^{64}\)Ni beam at 250 MeV/\(u\) to 13 MeV/\(u\) in a thick Al degrader was performed at the FRagment Separator (FRS) at GSI. The experimentally measured energy spread and the nuclear reaction yields in the degrader are in good agreement with simulations.


Testing and Development of a Novel Phoswich Scintillator Detector for PARIS

Acta Phys. Pol. B 42, 729 (2011)

page 729 •

abstract

LaBr\(_{3}\)(Ce) is a novel scintillator that holds a lot of potential in \(\gamma \)-ray spectroscopy due to its high energy resolution and timing properties, despite exhibiting self-activity due to the \(^{138}\)La isotope in the crystal (0.09% abundance). However, due to the high cost of these scintillators, a phoswich detector was acquired as a more cost effective approach to constructing the new Photon Array for the study of Radioactive Ion and Stable beams (PARIS), intended for the SPIRAL2 beam-line at GANIL. Tests on the timing and energy response of a 1"\(\times \) 1"\(\times \) 2" LaBr\(_{3}\)(Ce) and 1"\(\times \) 1"\(\times \) 6" CsI(Na) phoswich detector is presented. Little is known about what happens to these crystals during neutron activation, and this was also investigated, where the study of the pulse shapes from neutron and gamma sources were used to show that (\(n, \gamma \)) discrimination was not possible. An activated spectrum from a \(^{241}\)Am/ \(^{9}\)Be source was acquired where neutron activation due to excited states of lanthanum and bromine (\(^{140}\)La, \(^{80}\)Br and \(^{82}\)Br) were found. The timing of the phoswich was also investigated, and found to be \(\sim 650\) ps when used in a start–stop set-up with BaF\(_{2}\). A marginal improvement of around 40 ps was achieved despite the set-up being poorly time matched.


Overview on the Cluster Structure and the Alpha Condensation

Acta Phys. Pol. B 42, 735 (2011)

page 735 •

abstract

Recent trends in nuclear cluster physics are discussed. Three subjects of the discussion are (1) clustering in neutron-rich nuclei, (2) alpha-condensate-like states, and (3) coexistence of cluster and mean-field-type states. The subject (1) includes molecular-orbital and atomic-orbital structures in Be and F isotopes and also dineutron correlation in halo nucleus \(^{11}\)Li. The subject (2) is discussed by using the investigations of \(^{12}\)C and \(^{16}\)O. The discussion of the subject (3) is based on two points: One is the AMD studies of cluster and mean-field-type states in many nuclei and the other is the monopole transitions between cluster states and the ground state with mean-field-type structure.


full authors' list

C. Beck, P. Papka, A. Sànchez i Zafra, S. Thummerer, F. Azaiez, P. Bednarczyk, S. Courtin, D. Curien, O. Dorvaux, A. Goasduff, D. Lebhertz, A. Nourreddine, M. Rousseau, M.-D. Salsac, W. von Oertzen, B. Gebauer, C. Wheldon, Tz. Kokalova, G. Efimov, V. Zherebchevsky, Ch. Schulz, H.G. Bohlen, D. Kamanin, G. de Angelis, A. Gadea, S. Lenzi, D.R. Napoli, S. Szilner, M. Milin, W.N. Catford, D.G. Jenkins, G. Royer

Clusters in Light Nuclei

Acta Phys. Pol. B 42, 747 (2011)

page 747 •

abstract

A great deal of research work has been undertaken in the \(\alpha \)-clustering study since the pioneering discovery, half a century ago, of \(^{12}\)C + \(^{12}\)C molecular resonances. Our knowledge in the physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. In this work, the occurence of “exotic” shapes in light \(N=Z\) \(\alpha \)-like nuclei is investigated. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Results on clustering aspects are also discussed for light neutron-rich oxygen isotopes.


full authors' list

S. Courtin, A. Goasduff, F. Haas, D. Lebhertz, D.G. Jenkins, P.A. Marley, D.A. Hutcheon, C.A. Davis, C. Ruiz

Radiative Capture in the \(^{12}{\rm C}+^{16}\)O System: Structural versus Statistical Aspects of the Decay

Acta Phys. Pol. B 42, 757 (2011)

page 757 •

abstract

This paper discusses how the radiative capture process can shed light on the origin of the resonances observed in light heavy-ion collisions. The impact of resonant features on the fusion cross-sections is described from energies around the Coulomb barrier down to the Gamow energy in systems like \(^{12}\)C+\(^{12}\)C and \(^{12}\)C+\(^{16}\)O.


full authors' list

V.V. Parkar, I. Martel, A.M. Sánchez-Benítez, L. Acosta, K. Rusek, Ł. Standylo, N. Keeley

Dipole Polarizabilities of Weakly Bound Nuclei

Acta Phys. Pol. B 42, 761 (2011)

page 761 •

abstract

Dipole polarizability, one of the fundamental properties of a nucleus, studied in elastic scattering experiments has been reviewed here. For strongly bound nuclei the effect of dipole polarizability is usually negligible. However, for weakly bound nuclei, where the dipole strength extends to low excitation energies, it does play a major role. This effect has already been examined in the scattering of the lightest weakly-bound stable nuclei, viz., \(d\), \(^3\)He, and \(^7\)Li. In the present work we have studied it for the weakly bound unstable borromean nucleus, \(^6\)He, using the elastic scattering data available at energies around the Coulomb barrier with a \(^{208}\)Pb target.


full authors' list

T. Kuboki, T. Ohtsubo, M. Takechi, I. Hachiuma, K. Namihira, T. Suzuki, T. Yamaguchi, Y. Ohkuma, Y. Shimbara, S. Suzuki, R. Watanabe, M. Fukuda, M. Mihara, D. Nishimura, Y. Ishibashi, Y. Ito, T. Moriguchi, D. Nagae, H. Ooishi, K. Ogawa, A. Ozawa, Y. Yasuda, H. Suzuki, T. Sumikama, K. Yoshinaga, H. Geissel, M. Winkler, T. Izumikawa, S. Momota, N. Aoi, N. Fukuda, N. Inabe, D. Kameda, K. Kusaka, T. Kubo, M. Lantz, T. Ohnishi, M. Ohtake, T. Suda, H. Takeda, K. Tanaka, Y. Yanagisawa, A. Yoshida, K. Yoshida

Measurement of Interaction Cross-sections for Neutron-rich Na Isotopes

Acta Phys. Pol. B 42, 765 (2011)

page 765 •

abstract

The interaction cross-sections (\(\sigma _{\rm {I}}\)) of neutron-rich Na isotopes, \(^{23-35}\)Na, on C target have been measured at \(250A\) MeV using the RI beam factory (RIBF) at RIKEN. Mass dependence of \(\sigma _{\rm {I}}\) for \(^{27-35}\)Na suggests monotonic growth of the skin thickness. The root-mean-square nuclear matter radii (\(\tilde {r}_{\rm m}\)) of \(^{23-35}\)Na were deduced from observed \(\sigma _{\rm {I}}\) via a Glauber-type calculation. These \(\tilde {r}_{\rm m}\) are in a good agreement with the theoretical prediction by relativistic mean field model (RMF). \(\tilde {r}_{\rm m}\) of \(^{33-35}\)Na were determined for the first time.


full authors' list

S. Cherubini, C. Spitaleri, M. Gulino, M. La Cognata, R.G. Pizzone, L. Lamia, G.G. Rapisarda, S. Romano, L. Sergi, A. Mukhamedzhanov, L. Trache, R.E. Tribble, S. Kubono, H. Yamaguchi, A. Tumino

Recent Studies on Trojan Horse Method

Acta Phys. Pol. B 42, 769 (2011)

page 769 •

abstract

The study of nuclear reactions that are important for the understanding of astrophysical problems received an increasing attention over the last decades. The Trojan Horse Method was proposed as a tool to overcome some of the problems connected with the measurement of cross-sections between charged particles at astrophysical energies. Here we present some recent studies on this method.


The Structure of \(^{12}\)C and Stellar Helium Burning

Acta Phys. Pol. B 42, 775 (2011)

page 775 •

abstract

The rate of stellar formation of carbon at high temperatures (\(T\!\gt \!3\) GK) may increase beyond that which is expected from the Hoyle state at 7.654 MeV due to contributions from higher lying states in \(^{12}\)C. The long sought for second \(2^+\) state predicted at 9–10 MeV excitation energy in \(^{12}\)C was predicted to significantly increase the production of \(^{12}\)C. An Optical Readout Time Projection Chamber (O-TPC) operating with the gas mixture of CO\(_2\)(80%) + N\(_2\)(20%) at 100 Torr with gamma beams from the HI\(\gamma \)S facility of TUNL at Duke was used to study the formation of carbon (and oxygen) during helium burning. Preliminary measurements were carried out at beam energies: \(E = 9.51, 9.61, 9.72, 10.00, 10.54, 10.84\) and \(11.14\) MeV. Extra attention was paid to separating the carbon dissociation events, \(^{12}\)C\((\gamma ,3\alpha )\), from the oxygen dissociation events, \(^{16}\)O\((\gamma ,\alpha )^{12}\)C. Complete angular distributions were measured giving credence to a newly identified \(2^+\) state just below 10.0 MeV.


Nuclear Astrophysics Deep Underground: The LUNA Experiment

Acta Phys. Pol. B 42, 785 (2011)

page 785 •

abstract

At astrophysically relevant temperatures, nuclear cross-sections are extremely small and experimental measurements in a laboratory at the Earths surface are hampered by the cosmic background. The LUNA Collaboration has exploited the unique features of the rock cover offered by the LNGS underground laboratory in terms of background reduction, to study very important hydrogen (H)-burning reactions at astrophysically relevant energies. After a general introduction on the LUNA experiment, this paper reports briefly on the recently obtained results.


full authors' list

A. Kozela, G. Ban, A. Białek, K. Bodek, P. Gorel, K. Kirch, St. Kistryn, M. Kuźniak, O. Naviliat-Cuncic, N. Severijns, E. Stephan, J. Zejma

Free Neutron Decay and Time Reversal Violation

Acta Phys. Pol. B 42, 789 (2011)

page 789 •

abstract

Both components of the transverse electron polarization have been measured in free neutron decay. The T-odd, P-odd correlation coefficient associated with polarization component perpendicular to the neutron polarization and electron momentum, was found to be \(R= 0.006 \pm 0.012 \pm 0.005\). This value is consistent with time reversal invariance, and significantly improves limits on the relative strength of imaginary scalar couplings in the weak interaction. The value obtained for the T-even, P-even correlation coefficient connected with the second transversal polarization component, \(N= 0.065 \pm 0.012\pm 0.004\), agrees with the Standard Model expectation providing an important sensitivity test of the experimental setup.


full authors' list

N. Targosz-Ślęczka, K. Czerski, A. Huke, G. Ruprecht, L. Martin, D. Blauth, H. Winter

Enhanced Pycnonuclear Reactions in Metallic Environments

Acta Phys. Pol. B 42, 795 (2011)

page 795 •

abstract

Study of the deuteron fusion reactions at very low energies in metallic environments enables us to determine the strength of the astrophysical electron screening effect in the terrestrial laboratories. Experiments performed under high and ultra high vacuum conditions showed that the experimentally determined screening energies corresponding to the reduction of the Coulomb barrier were significantly larger than the theoretical values calculated in terms of the dielectric function theory. As the origin of the so-called enhanced screening effect observed in nuclear reactions taking place in metals is unexplained we discuss here the interplay between a strong plasma screening and a narrow resonance placed close to the reaction threshold, which leads to the target material dependence of the reaction cross-section.


full authors' list

P.E. Garrett, K.L. Green, R.A.E. Austin, G.C. Ball, D.S. Bandyopadhyay, S. Colosimo, D.S. Cross, G.A. Demand, G.F. Grinyer, G. Hackman, W.D. Kulp, K.G. Leach, A.C. Morton, C.J. Pearson, A.A. Phillips, M.A. Schumaker, C.E. Svensson, J. Wong, J.L. Wood, S.W. Yates

Using \(\beta \)-decay to Map the \(E2\) Strength in the Cd Isotopes and the Downfall of Vibrational Motion

Acta Phys. Pol. B 42, 799 (2011)

page 799 •

abstract

The \(\beta \) decay of \(^{112}\)Ag has been used to populate spin \(0^+\) and \(2^+\) states in \(^{112}\)Cd to 3 MeV excitation energy. The statistical quality obtained allows the extraction of very weak \(\gamma \)-ray branching ratios that, combined with known level lifetimes, enables the determination of the \(B(E2)\) values or upper limits for transitions populating the proposed two-phonon states. While candidates for \(3^+\), \(4^+\), and \(6^+\) three-phonon levels have been identified, there are no candidates for the \(0^+\) and \(2^+\) three phonon levels, and the upper limits of the \(B(E2)\) values indicate that phonon \(E2\) strength is not fragmented, but absent below \(5\hbar \omega _2\).


full authors' list

K. Wrzosek-Lipska, M. Zielińska, K. Hadyńska-Klęk, J. Iwanicki, M. Kisieliński, M. Kowalczyk, P.J. Napiorkowski, D. Piętak, J. Srebrny

Quadrupole Moment of the \(2^+_1\) State in \(^{100}\)Mo

Acta Phys. Pol. B 42, 803 (2011)

page 803 •

abstract

Coulomb excitation is the only experimental method that can measure quadrupole moments of short-lived excited states, thus providing information on nuclear shape. This paper presents data analysis techniques that were used to extract the diagonal matrix element of the 2\(^+_1\) state in \(^{100}\)Mo. Influence of various methods of data subdivision and accuracy of the beam energy on the final result is discussed. Obtained quadrupole moment of the 2\(^+_1\) state is compared to the one determined from earlier measurements.


full authors' list

V. Anagnostatou, P.H. Regan, M.R. Bunce, D. McCarthy, V. Werner, T. Ahn, R.J. Casperson, R. Chevrier, N. Cooper, A. Heinz, G. Ilie, M.K. Smith, E. Williams, L. Bettermann, D. Radeck, C.W. Beausang, C. Boniwell, B. Pauerstein

Measurements of Picosecond Lifetimes in the Transitional Nucleus \(^{100}\)Pd using the RDDM in Inverse Kinematics

Acta Phys. Pol. B 42, 807 (2011)

page 807 •

abstract

Electromagnetic transition rates have been measured for decays from the ground state band in the transitional nucleus \(^{100}\)Pd using the Recoil Distance Doppler Shift Method in inverse kinematics via the \(^{24}\)Mg(\(^{80}\)Se,4n)\(\\ ^{100}\)Pd reaction at a beam energy of 268 MeV. The nuclei produced were stopped using a Cu foil and data were recorded for 10 different target-stopper distances. The gamma-rays emitted were measured using the SPEEDY germanium detector array at WNSL Yale University and the target-to-stopper distances were determined and kept constant using the New Yale Plunger Device. The preliminary results of this study are presented.


full authors' list

R. Kumar, P. Doornenbal, A. Jhingan, R.K. Bhowmik, S. Appannababu, P. Bednarczyk, L. Cáceres, J. Cederkäll, A. Ekström, R. Garg, J. Gerl, M. Górska, H. Grawe, J. Kaur, I. Kojouharov, S. Mandal, S. Mukherjee, S. Muralithar, W. Prokopowicz, P.P. Singh, P. Reiter, H. Schaffner, A. Sharma, R.P. Singh, D. Siwal, H.J Wollersheim

Enhanced \(0^+_{\rm g.s.} \rightarrow 2^+_1\) \(E2\) Transition Strength in \(^{112,114}\)Sn

Acta Phys. Pol. B 42, 813 (2011)

page 813 •

abstract

The poorly known \(B(E2\); \(0^{+}\rightarrow 2^{+}\)) values of \(^{112}\)Sn and \(^{114}\)Sn have been measured to high precision. Two Coulomb excitation experiments were performed to determine the reduced transition probabilities relative to \(^{116}\)Sn in order to minimize the systematic errors. The obtained \(B\)(\(E2\uparrow \)) values of \(0.242(8)~e^{2}b^{2}\) for \(^{112}\)Sn and \(0.232(8)~e^{2}b^{2}\) for \(^{114}\)Sn confirm the tendency of large \(B\)(\(E2\uparrow \)) values for the lighter tin isotopes below the midshell \(^{116}\)Sn that has been observed recently in various radioactive ion beam experiments.


full authors' list

K. Hadyńska-Klęk, P.J. Napiorkowski, A. Maj, F. Azaiez, J.J. Valiente-Dobón, G. de Angelis, G. Anil Kumar, D. Bazzacco, P. Bednarczyk, M. Bellato, G. Benzoni, L. Berti, D. Bortolato, B. Bruyneel, F. Camera, M. Ciemała, P. Cocconi, A. Colombo, A. Corsi, F. Crespi, A. Czermak, B. Dulny, E. Farnea, B. Fornal, S. Franchoo, A. Gadea, A. Giaz, A. Gottardo, X. Grave, J. Grębosz, M. Gulmini, H. Hess, R. Isocrate, G. Jaworski, M. Kicińska-Habior, M. Kmiecik, N. Kondratyev, A. Korichi, W. Korten, G. Lehaut, S. Lenzi, S. Leoni, S. Lunardi, G. Maron, R. Menegazzo, D. Mengoni, E. Merchán, W. Męczyński, C. Michelagnoli, P. Molini, D.R. Napoli, R. Nicolini, M. Niikura, M. Palacz, G. Rampazzo, F. Recchia, N. Redon, P. Reiter, D. Rosso, E. Sahin, J. Srebrny, I. Stefan, O. Stézowski, J. Styczeń, N. Toniolo, C.A. Ur, V. Vandone, B. Wadsworth, A. Wiens, K. Wrzosek-Lipska, M. Zielińska, M. Ziębliński

Refinement of the \(^{42}\)Ca Level Scheme. Preliminary Results from the First AGATA Demonstrator Experiment

Acta Phys. Pol. B 42, 817 (2011)

page 817 •

abstract

The Coulomb excitation experiment to study electromagnetic properties of low-lying states in \(^{42}\)Ca with a focus on a presumably superdeformed band was performed at the Laboratori Nazionali di Legnaro in Italy using the \(\gamma \)-ray spectrometer AGATA Demonstrator coupled to the DANTE charged particle detector array. First results are presented, including the refinement of the \(^{42}\)Ca level scheme.


full authors' list

C. Michelagnoli, C.A. Ur, E. Farnea, S. Lenzi, S. Lunardi, F. Recchia, N. Marginean, D. Bucurescu, G. Cata-Danil, D. Deleanu, D. Filipescu, D. Ghita, T. Glodariu, R. Marginean, C. Mihai, A. Negret, S. Pascu, T. Sava, L. Stroe, G. Suliman

Lifetime Measurement in the \(N=Z\) Nucleus \(^{44}\)Ti

Acta Phys. Pol. B 42, 825 (2011)

page 825 •

abstract

The Recoil Distance Doppler-Shift method has been used to measure the lifetime of the first \(3^-\) state in the \(N=Z\) \(^{44}\)Ti nucleus, populated via the \(^{40}\)Ca(\(^6\)Li, \(pn)^{44}\)Ti reaction. State-of-the-art analysis techniques have been employed to determine the experimental lifetime, resulting in a \(B(E3; 3_1^- \rightarrow 0_1^+)\approx 3\) W.u.


full authors' list

A. Dijon, J. Ljungvall, E. Clément, G. de France, P. Van Isacker, A. Görgen, A. Obertelli, W. Korten, J.P. Delaroche, A. Dewald, A. Gadea, L. Gaudefroy, M. Girod, M. Hackstein, J. Libert, D. Mengoni, T. Pissula, F. Recchia, M. Rejmund, W. Rother, E. Sahin, C. Schmitt, A. Shrivastava, J.J. Valiente-Dobón, K.O. Zell, M. Zielińska

Lifetime Measurements in Neutron-rich Fe and Co Isotopes

Acta Phys. Pol. B 42, 829 (2011)

page 829 •

abstract

Lifetimes of yrast states in neutron-rich Fe and Co isotopes were measured using the differential Recoil Distance Doppler Shift (RDDS) and the differential decay curves methods. The nuclei of interest were populated in multi-nucleon transfer in inverse kinematics. The deduced \(B(E2)\) values are compared with large-scale shell-model calculations, leading to a better understanding of the mechanisms at the origin of the onset of collectivity in the region just below \(^{68}\)Ni.


Hypernuclei — the Next Decade

Acta Phys. Pol. B 42, 833 (2011)

page 833 •

abstract

We are at the verge of a new impact from hypernuclear experiments planned or already operative at various laboratories all over the world. The complementary of these different experimental approaches to hypernuclei provides a wide basis for a comprehensive understanding of strange hadrons in cold hadronic matter. High precision studies of light \({\mit \Lambda }\) hypernuclei, spectroscopy of double \({\mit \Lambda }{\mit \Lambda }\) nuclei and the properties of antihyperons in nuclei are examples for the outstanding challenges for hypernuclei research in the next decade.


full authors' list

P.G. Thirolf, D. Habs, M. Gross, K. Allinger, J. Bin, A. Henig, D. Kiefer, W. Ma, J. Schreiber

Laser Particle Acceleration: Status and Perspectives for Nuclear Physics

Acta Phys. Pol. B 42, 843 (2011)

page 843 •

abstract

High power short-pulse lasers with peak powers presently reaching Terawatts and even Petawatt levels routinely reach focal intensities of \(10^{18}\)–\(10^{21}\) W/cm\(^2\). These lasers are able to produce a variety of secondary radiation, from relativistic electrons and multi-MeV/nucleon ions to high-energetic X-rays and \({\gamma }\)-rays. In many laboratories world-wide large resources are presently devoted to a rapid development of this novel tool of particle acceleration, targeting nuclear, fundamental and high-field physics studies as well as various applications e.g. in medical technology for diagnostics and tumor therapy. Within the next 5 years a new EU-funded large-scale research infrastructure (ELI: Extreme Light Infrastructure) will be constructed, with one of its four pillars exclusively devoted to nuclear physics based on high intensity lasers (ELI-Nuclear Physics, to be built in Magurele/Bucharest). There the limits of laser intensity will be pushed by three orders of magnitude to yet unprecedented \(10^{24}\) W/cm\(^2\).


full authors' list

V.S. Alexandrov, K.V. Chekirda, V.L. Fedorin, N.A. Melnikov, A.A. Pasternak, Yu.G. Zakharenko

Nuclear Transitions and New Standards of Length and Time

Acta Phys. Pol. B 42, 853 (2011)

page 853 •

abstract

Modern standards of length and time are based on wavelength measurements of laser light sources, whose relative stability is limited by the temperature dependence of molecular or atomic transition frequencies and cannot be better than 10\(^{-15}\). The cardinal way of improvement is to find nuclear transitions coincident with any laser line. This short review is devoted to the present status of investigations and available projects of using the \(7.6\) eV transition in \(^{229}\)Th. Some new ideas are proposed and discussed.


First Results on Charged Particle Production in ALICE Experiment at LHC

Acta Phys. Pol. B 42, 859 (2011)

page 859 •

abstract

The ALICE experiment is the dedicated heavy-ion experiment at the CERN LHC, but its physics program also covers \(pp\) physics. ALICE, since its start, has collected \(pp\) data at 3 different center-of-mass energies — 900 GeV, 2.36 TeV and 7 TeV. Here, a brief description of the experimental apparatus is given, and some recent results on the particle multiplicity and charged particle spectra are presented. Results are compared with the existing data from lower energies and with Monte Carlo predictions.


What Is the Role of Nuclear Effects in Ultrarelativistic Reactions at 158 GeV/Nucleon?

Acta Phys. Pol. B 42, 867 (2011)

page 867 •

abstract

In this paper I shall present a few simple examples on how the nuclear structure, nuclear density, isospin content, and finally the electric charge of the nucleus influence various aspects of multiparticle production in ultrarelativistic nuclear reactions.


Status of the SPIRAL2 Project

Acta Phys. Pol. B 42, 877 (2011)

page 877 •

abstract

The SPIRAL2 project at GANIL, one of the ESFRI list and the NuPECC Road Map European research infrastructures, entered recently in the construction phase. In the following, a physics case of the facility, expected performances and main technical parameters of the facility as well as planned new experimental areas and detectors are shortly introduced.


FAIR — Facility, Research Program and Status of the Project

Acta Phys. Pol. B 42, 883 (2011)

page 883 •

abstract

The international Facility for Antiproton and Ion Research (FAIR) in Europe will provide a worldwide science community with a unique and technically innovative accelerator system to perform forefront research in the sciences concerned with the basic structure of matter, and in intersections with other fields. The facility will deliver an extensive range of primary and secondary particle beams from protons and their antimatter partners, antiprotons, to ion beams of all chemical elements up to the heaviest, uranium, with in many respects unique properties and intensities. The paper will include overview of the new facility design and research programs to be carried out there. The current status of the FAIR project will be also presented.


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