### Regular Series

#### Zakopane Conference on Nuclear Physics Extremes of the Nuclear Landscape

full authors' list

N. Chamel, J.M. Pearson, A.F. Fantina, C. Ducoin, S. Goriely, A. Pastore

Brussels–Montreal Nuclear Energy Density Functionals, from Atomic Masses to Neutron Stars

Acta Phys. Pol. B 46, 349 (2015)

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abstract

We have recently developed a series of accurately calibrated nuclear energy density functionals, fitted to essentially all atomic masses with a model root mean square deviation now reduced to 0.5 MeV for our functional BSk27*. At the same time, these functionals were adjusted to realistic equations of state of neutron matter and were constrained to reproduce various properties of nuclear matter. Using BSk27$^*$, we have calculated the internal constitution and the equation of state of the crust of non-accreting neutron stars.

Microscopic Calculations of Nuclear and Neutron Matter, Symmetry Energy and Neutron Stars

Acta Phys. Pol. B 46, 359 (2015)

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abstract

We present Quantum Monte Carlo calculations of the equation of state of neutron matter. The equation of state is directly related to the symmetry energy and determines the mass and radius of neutron stars, providing then a connection between terrestrial experiments and astronomical observations. We also show preliminary results of the equation of state of nuclear matter.

Nuclear Energy Density Functionals and Neutron Star Properties

Acta Phys. Pol. B 46, 369 (2015)

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abstract

Recently, a method based on relativistic nuclear energy density functional (EDF) has been employed to study relations between collective excitations in finite nuclei with the nuclear matter symmetry energy, and the phase transition density $n_{\rm t}$ and pressure $P_{\rm t}$ at the inner edge separating the liquid core and the solid crust of a neutron star. By using the thermodynamic method, relativistic EDF and experimental data on the properties of charge-exchange dipole transitions, isovector giant dipole and quadrupole resonances and pygmy dipole transitions, the neutron star liquid-to-solid phase transition density and pressure are constrained. The analysis shows that accurate measurements are necessary to further constrain the symmetry energy parameters and the structure of neutron star crust.

Three-body Forces: From Cold Atoms to Nuclei

Acta Phys. Pol. B 46, 379 (2015)

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abstract

Three- and higher-body forces enter naturally in effective field theories for strongly interacting quantum systems. We focus on the effect of three-body forces in systems close to the unitary limit and discuss applications in ultracold atoms and halo nuclei.

Nuclear Structure and Dynamics with Density Functional Theory

Acta Phys. Pol. B 46, 391 (2015)

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abstract

The superfluid local density approximation (SLDA) is widely used to compute ground-state properties of heavy nuclei. In the same framework, the time-dependent (TD) SLDA can provide information about the excited states and can be used to investigate phenomena involving large amplitude collective motion such as nuclear reactions. Hence, the TDSLDA represents an alternative to the more traditional approaches to nuclear reactions, in which the static and dynamic properties are usually decoupled. In this consistent framework, I briefly discuss the main characteristics of the Coulomb excitation of a $^{238}$U nucleus by a relativistic projectile.

The Nuclear Symmetry Energy and Other Isovector Observables from the Point of View of Nuclear Structure

Acta Phys. Pol. B 46, 395 (2015)

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abstract

In this contribution, we review some works related with the extraction of the symmetry energy parameters from isovector nuclear excitations, like the giant resonances. Then, we move to the general issue of how to assess whether correlations between a parameter of the nuclear equation of state and a nuclear observable are robust or not. To this aim, we introduce the covariance analysis and we discuss some counter-intuitive, yet enlightening, results from it.

Nuclear Structure Theory of the Heaviest Nuclei

Acta Phys. Pol. B 46, 405 (2015)

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abstract

The current status of the application of covariant density functional theory to the description of actinides and superheavy nuclei is reviewed. The achievements and open problems are discussed.

Temperature Dependence of Nuclear Symmetry Free Energy

Acta Phys. Pol. B 46, 419 (2015)

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abstract

The nuclear symmetry free energy as well as its slope and curvature parameters within the lowest order constrained variational method using Argonne V18 two-body interaction and an Urbana type three-body force are calculated. Density and temperature dependence of the above quantities are studied and the effect of including the three-body interaction on these parameters is also discussed.

On Systematics of Spontaneous Fission Half-lives

Acta Phys. Pol. B 46, 423 (2015)

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abstract

A simple phenomenological formula, based on the Świątecki idea for the evaluation of the spontaneous fission half-lives, is proposed. The model contains only one adjustable parameter fixed to the data for even–even nuclei and an additional hindrance factor for odd nuclei, which gives the effect of an odd particle. A good agreement with the experimental data for isotopes with $90 \le Z \le 103$ is achieved.

Production of Neutron-rich Nuclei in Low-energy Multinucleon Transfer Reactions

Acta Phys. Pol. B 46, 427 (2015)

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abstract

Multinucleon transfer processes in low-energy heavy ion collisions open new field of research in nuclear physics, namely, production and studying properties of not-yet-explored heavy neutron-rich nuclei. Beams of very heavy U-like ions are needed to produce new long-living isotopes of transfermium and superheavy elements. Beams of medium-mass ions can be used for the production of neutron-rich nuclei located along the neutron closed shell $N=126$ (the last waiting point) having the largest impact on the astrophysical r-process. Low-energy multinucleon transfer reactions is a very effective tool also for the production and spectroscopic study of light exotic nuclei. The corresponding cross sections are found to be 2 orders of magnitude larger as compared with high energy fragmentation reactions.

full authors' list

T. Mijatović, S. Szilner, L. Corradi, D. Montanari, S. Courtin, E. Fioretto, A. Gadea, A. Goasduff, F. Haas, D. Jelavić Malenica, G. Montagnoli, G. Pollarolo, L. Prepolec, F. Scarlassara, N. Soić, A.M. Stefanini, V. Tokić, C.A. Ur, J.J. Valiente-Dobon

Pairing Correlation Study in the $^{40}$Ar$\,+\,^{208}$Pb Multinucleon Transfer Reaction

Acta Phys. Pol. B 46, 439 (2015)

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abstract

The $^{40}$Ar$\,+\,^{208}$Pb multinucleon transfer reaction has been studied at $E_{\rm lab} = 255$ MeV with the large solid angle magnetic spectrometer PRISMA. Mass and charge yields, differential and total cross sections, total kinetic energy loss distributions of different channels were simultaneously measured. Angular distributions were measured in a wide angular range by matching different spectrometer angular settings. Absolute cross sections were obtained by careful evaluation of the spectrometer response function. These cross sections for different transfer channels allow the discussion of the role played by nucleon–nucleon correlations.

full authors' list

D. Ramos, C. Rodríguez-Tajes, M. Caamaño, F. Farget, L. Audouin, J. Benlliure, E. Casarejos, E. Clement, D. Cortina, O. Delaune, X. Derkx, A. Dijon, D. Doré, B. Fernández-Domínguez, G. de France, A. Heinz, B. Jacquot, A. Navin, C. Paradela, M. Rejmund, T. Roger, M.D. Salsac, C. Schmitt

Fission Yields of Minor Actinides at Low Energy Through Multi-nucleon Transfer Reactions of $^{238}$U on $^{12}$C

Acta Phys. Pol. B 46, 443 (2015)

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abstract

First preliminary results of fragments distribution as a function of the excitation energy for different fissioning systems from U to Cm and $^{250}$Cf are presented. A new method based on inverse kinematics to study transfer-induced fission of minor actinides was carried out in GANIL in 2008, and again in 2011. In these experiments, a $^{238}$U beam at 6.1 $A$ MeV impinged on a carbon target to produce fissioning systems by multi-nucleon transfer reactions, resulting in the first experiments accessing the full identification of a collection of fissioning systems and their corresponding fission fragments distribution. The excitation energy is deduced from the detection of the recoil nucleus in an angular DE-E stripped silicon telescope, and the identification of the fragments is made possible by the VAMOS spectrometer.

full authors' list

D. Fabris, F. Gramegna, T. Marchi, M. Degerlier, O.V. Fotina, V.L. Kravchuk, M. D'Agostino, L. Morelli, S. Appannababu, G. Baiocco, S. Barlini, M. Bini, A. Brondi, M. Bruno, G. Casini, M. Cinausero, N. Gelli, R. Moro, A. Olmi, G. Pasquali, S. Piantelli, G. Poggi, S. Valdré, E. Vardaci

Pre-equilibrium Particles Emission and Its Possible Relation to $\alpha$-clustering in Nuclei

Acta Phys. Pol. B 46, 447 (2015)

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abstract

The search for cluster structure effects in nuclei have been studied looking to the pre-equilibrium particles emitted in two different reactions at the same beam velocity (16 $A$ MeV): $^{16}$O + $^{65}$Cu and $^{19}$F + $^{62}$Ni, leading to the same $^{81}$Rb$^{*}$ compound nucleus. The GARFIELD + RCo multi-detection system operating at LNL has been used. The preliminary data analysis results and the first theoretical model calculations are presented.

full authors' list

R. Kumar, V.R. Sharma, A. Yadav, P.P. Singh, S. Appanababu, A. Aggarwal, B.P. Singh, S. Mukherjee, S. Muralithar, R. Ali, R.K. Bhowmik

Low Energy Incomplete Fusion and the Role of Input Angular Momenta

Acta Phys. Pol. B 46, 453 (2015)

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abstract

Aiming to investigate the incomplete fusion processes at low projectile energies, experiments have been carried out for the $^{14}$N + $^{169}$Tm system at $\approx 4$–7 MeV/$A$. Excitation functions for several residues likely to be populated via complete and incomplete fusion processes have been measured for the first time using heavy recoil residue catcher technique followed by $\gamma$-ray spectroscopy. The measured excitation functions are compared with the calculations based on the available statistical model codes. The incomplete fusion strength function is found to increase with the projectile energy. An attempt has been made to compare the present system with an semi-empirical code MARC for incomplete fusion.

full authors' list

I. Ciepał, B. Kłos, A. Kozela, E. Stephan, St. Kistryn, A. Biegun, K. Bodek, A. Deltuva, M. Eslami-Kalantari, V. Jha, N. Kalantar-Nayestanaki, G. Khatri, Da. Kirillov, Di. Kirillov, St. Kliczewski, M. Kravcikova, P. Kulessa, H. Machner, A. Magiera, G. Martinska, J. Messchendorp, W. Parol, A. Ramazani-Moghaddam-Arani, B.J. Roy, H. Sakai, K. Sekiguchi, I. Sitnik, R. Siudak, I. Skwira-Chalot, R. Sworst, J. Urban, J. Zejma

Coulomb Force Effects in Deuteron–Proton Breakup Reaction

Acta Phys. Pol. B 46, 459 (2015)

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abstract

A large set of cross-section data for the $^{1}$H$(d,pp)n$ breakup reaction was measured at 130 MeV deuteron beam energy with the Germanium Wall setup covering the range of very forward polar angles. In the investigated part of the phase-space, the dynamics is dominated by the Coulomb force influence. The data are compared with results of theoretical calculations based on the realistic Argonne V18 potential supplemented with the long-range electromagnetic component. The predictions also include the Urbana IX three nucleon force model. The cross-section data reveal seizable Coulomb force effects.

Structural Effects on the Peak Production of Fragments

Acta Phys. Pol. B 46, 463 (2015)

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abstract

We study the role of systematic reduction and enhancement in nuclear radius on the multiplicities of various fragments using the Isospin-dependent Quantum Molecular Dynamics (IQMD) model. We find that multiplicities of various fragments are sensitive towards change in nuclear radius. We also find that peak center-of-mass energy ($E_{\rm cm}^{\max }$) and peak multiplicity of intermediate mass fragments ($\langle N_{\rm IMF} \rangle ^{\max }$) are sensitive towards the nuclear radius.

Effect of Electron Screening on Nuclear Reaction Rates

Acta Phys. Pol. B 46, 467 (2015)

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abstract

Recently, we performed an extensive experimental campaign, with an aim to study the electron screening in the laboratory for various nuclear reactions and involving both low and high $Z$ targets. Contrary to the large effect observed for low $Z$ targets, no large electron screening was observed for high $Z$ targets. This result was quite surprising and in continuation of our campaign, we focused on the studies of low $Z$ targets. The $^{2}$H$(p,\gamma )^{3}$He reaction was studied at low energies, in different deuterium implanted materials. Although we were not able to deduce the value of electron screening, we report three new values for the cross section.

full authors' list

J. Marganiec, S. Beceiro Novo, S. Typel, C. Wimmer, H. Alvarez-Pol, T. Aumann, K. Boretzky, E. Casarejos, A. Chatillon, D. Cortina Gil, U. Datta-Pramanik, Z. Elekes, Z. Fulop, D. Galaviz, H. Geissel, S. Giron, U. Greife, F. Hammache, M. Heil, J. Hoffman, H. Johansson, O. Kiselev, N. Kurz, K. Larsson, T. Le Bleis, Y. Litvinov, K. Mahata, C. Muentz, C. Nociforo, W. Ott, S. Paschalis, R. Plag, W. Prokopowicz, C. Rodríguez Tajes, D. Rossi, H. Simon, M. Stanoiu, J. Stroth, K. Sümmerer, A. Wagner, F. Wamers, H. Weick

Coulomb Dissociation Experiment of $^{27}$P

Acta Phys. Pol. B 46, 473 (2015)

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abstract

The $^{26}$Si($p,\gamma$)$^{27}$P reaction, which might play an important role in the rp process, was studied by the Coulomb Dissociation method. The experiment was performed at GSI, Darmstadt. A secondary $^{27}$P ion beam of 500 MeV/nucleon was directed onto a Pb target. From this experiment, the Coulomb Dissociation cross section, $\sigma _{\rm Coulex}$, will be deduced and then converted to the photoabsorption cross section, $\sigma _{\rm photo}$, and the radiative-capture cross section, $\sigma _{\rm cap}$. Also information on the structure of $^{27}$P will be obtained. The analysis is in progress.

Shape Coexistence, Triaxial Shape and Band Terminations at High Spin

Acta Phys. Pol. B 46, 477 (2015)

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abstract

Selected high-spin bands in $A=120$–170 nuclei are interpreted within the configuration-constrained Cranked Nilsson–Strutinsky formalism with pairing neglected (CNS) and with pairing included (CNSB). A few bands in Lu/Hf nuclei which have been interpreted as formed at large triaxial deformation are reinterpreted as rotational bands at small deformation approaching termination. The differences between the linked high-spin rotational bands in $^{125,126}$Xe are explored, suggesting that the bands in $^{126}$Xe terminate high above yrast at close to spherical shape.

full authors' list

E.S. Paul, J.M. Rees, P. Hampson, M.A. Riley, J. Simpson, A.D. Ayangeakaa, J.S. Baron, M.P. Carpenter, C.J. Chiara, U. Garg, D.J. Hartley, C.R. Hoffman, R.V.F. Janssens, F.G. Kondev, T. Lauritsen, P.J.R. Mason, J. Matta, S.L. Miller, P.J. Nolan, J. Ollier, M. Petri, D.C. Radford, J.P. Revill, X. Wang, S. Zhu, I. Ragnarsson

Recent Results at Ultrahigh Spin: Terminating States and Beyond in Mass 160 Rare-earth Nuclei

Acta Phys. Pol. B 46, 487 (2015)

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abstract

A classic region of band termination at high spin occurs in rare-earth nuclei with around ten valence nucleons above the $^{146}$Gd closed core. Results are presented here for such non-collective oblate ($\gamma =60^\circ$) terminating states in odd-$Z$ $^{155}$Ho, odd–odd $^{156}$Ho, and even–even $^{156}$Er, where they are compared with neighbouring nuclei. In addition to these particularly favoured states, the occurrence of collective triaxial strongly deformed (TSD) bands, bypassing the terminating states and extending to over 65$\hbar$, is reviewed.

Application of the Pfaffian Algorithm in the Nuclear Structure Study at High Spins

Acta Phys. Pol. B 46, 497 (2015)

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abstract

To expand the multi-quasiparticle (qp) configuration space of the projected shell model, the Pfaffian algorithm is applied to facilitate calculations of the matrix elements. With inclusion of 6-qp states in the projected basis, the yrast band of $^{166}$Hf at very high spins is studied, where the observed three anomalies in moment of inertia are well reproduced and explained by the contributions of the 2-qp, 4-qp, and 6-qp states, respectively.

Isospin Character of Low-lying Pygmy Dipole States Probed via Inelastic Scattering of $^{17}$O

Acta Phys. Pol. B 46, 501 (2015)

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abstract

The pygmy dipole states were populated in $^{208}$Pb and $^{124}$Sn by the inelastic scattering of a $^{17}$O beam at the energy of 20 MeV/$u$, and their subsequent gamma decay was measured with the AGATA demonstrator array. Differential cross sections as a function of the angle were measured. The results are compared with ($\gamma$, $\gamma '$) data. For the dipole transitions, a form factor obtained by folding a microscopically calculated transition density was used. This has allowed us to extract the isoscalar component of the 1$^{-}$ excited states.

full authors' list

A.C. Larsen, S. Goriely, L.A. Bernstein, D.L. Bleuel, A. Bracco, B.A. Brown, F. Camera, T.K. Eriksen, S. Frauendorf, F. Giacoppo, M. Guttormsen, A. Görgen, S. Harissopulos, S. Leoni, S.N. Liddick, F. Naqvi, H.T. Nyhus, S.J. Rose, T. Renstrøm, R. Schwengner, S. Siem, A. Spyrou, G.M. Tveten, A.V. Voinov, M. Wiedeking

Upbend and M1 Scissors Mode in Neutron-rich Nuclei — Consequences for r-process $(n,\gamma )$ Reaction Rates

Acta Phys. Pol. B 46, 509 (2015)

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abstract

An enhanced probability for low-energy $\gamma$-emission ($\!$upbend, $E_{\gamma }\! \lt \!3$ MeV) at high excitation energies has been observed for several light and medium-mass nuclei close to the valley of stability. Also the M1 scissors mode seen in deformed nuclei increases the $\gamma$-decay probability for low-energy $\gamma$-rays ($E_{\gamma } \approx 2$–3 MeV). These phenomena, if present in neutron-rich nuclei, have the potential to increase radiative neutron-capture rates relevant for the r-process. The experimental and theoretical status of the upbend is discussed, and preliminary calculations of ($n,\gamma$) reaction rates for neutron-rich, mid-mass nuclei including the scissors mode are shown.

Isospin Mixing in $^{80}$Zr at Finite Temperature

Acta Phys. Pol. B 46, 513 (2015)

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abstract

The isospin symmetry breaking (i.e. isospin mixing) due to the Coulomb interaction has been measured in the compound nucleus $^{80}$Zr$^{*}$ at temperature $T \simeq 2$ MeV. The giant dipole resonance $\gamma$ decay was used as a probe to deduce the mixing. The Coulomb spreading width and the degree of isospin mixing has been obtained from the analysis of the measured $\gamma$-ray spectra.

Effects of Phonon–Phonon Coupling on Properties of Pygmy Resonance in $^{132}$Sn

Acta Phys. Pol. B 46, 517 (2015)

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abstract

Starting from an effective Skyrme interaction, we study the effects of phonon–phonon coupling on the low-energy spectrum of the $1^{-}$ states in $^{132}$Sn. The calculations are performed within a finite rank separable approximation for the particle-hole interaction. The inclusion of two-phonon configurations brings a sizeable contribution to the low-lying strength. Comparison with available experimental data shows a reasonable agreement for the low-energy E1 strength distribution.

Theoretical and Experimental Perspectives of Nuclear Reaction Studies with Radioactive Ion Beams

Acta Phys. Pol. B 46, 521 (2015)

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abstract

Nuclear reactions are one of the most powerful probes to study the properties of nuclei, in particular nuclei at the limits of stability. Reactions also play an important role in astrophysics and other applications. In order to extract useful information from reaction measurements, experiment goes hand-in-hand with reaction theory. While the last five decades have provided very good qualitative understanding of the processes, the challenge in the field of reaction theory is to have a grasp on the systematic uncertainties, such that predictions can be truly quantitative. Here, we provide some examples of ongoing efforts aimed at advancing the theory for ($d,p$) reactions and reducing the associated uncertainties. We present the status of using the $^{86}$Kr($d,p$) reaction and the combined method to control the uncertainties introduced by the overlap function. We also discuss the ambiguities of using only data to constrain the optical potential and will show recent results on the role of non-locality in transfer reactions.

full authors' list

W.N. Catford, I.C. Celik, G.L. Wilson, A. Matta, N.A. Orr, C.Aa. Diget, P. Adsley, H. Al-Falou, R. Ashley, R.A.E. Austin, G.C. Ball, J.C. Blackmon, A.J. Boston, H.C. Boston, S.M. Brown, D.S. Cross, M. Djongolov, T.E. Drake, U. Hager, S.P. Fox, B.R. Fulton, N. Galinski, A.B. Garnsworthy, G. Hackman, D. Jamieson, R. Kanungo, K. Leach, J-P. Martin, J.N. Orce, C.J. Pearson, M. Porter-Peden, F. Sarazin, S. Sjue, C. Sumithrarachchi, C.E. Svensson, S. Triambak, C. Unsworth, R. Wadsworth, S.J. Williams

Structure of $^{26}$Na via a Novel Technique Using ($d,p\gamma$) with a Radioactive $^{25}$Na Beam

Acta Phys. Pol. B 46, 527 (2015)

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abstract

States in $^{26}$Na were populated in the ($d,p\gamma$) reaction, induced by bombarding deuterium target nuclei with an intense reaccelerated beam of $^{25}$Na ions from the ISAC2 accelerator at TRIUMF. Gamma-rays were recorded in coincidence with protons and used to extract differential cross sections for 21 states up to the neutron decay threshold of 5 MeV. Results for levels below 3 MeV are discussed in detail and compared with shell model calculations and with previous work. The angular distributions of decay gamma-rays were measured for individual states and are compared to theoretically calculated distributions, highlighting some issues for future work.

full authors' list

K.L. Jones, S. Ahn, J.M. Allmond, A. Ayres, D.W. Bardayan, T. Baugher, D. Bazin, J.S. Berryman, A. Bey, C. Bingham, L. Cartegni, G. Cerizza, K.Y. Chae, J.A. Cizewski, A. Gade, A. Galindo-Uribarri, R.F. Garcia-Ruiz, R. Grzywacz, M.E. Howard, R.L. Kozub, J.F. Liang, B. Manning, M. Matoš, S. McDaniel, D. Miller, C.D. Nesaraja, P.D. O'Malley, S. Padgett, E. Padilla-Rodal, S.D. Pain, S.T. Pittman, D.C. Radford, A. Ratkiewicz, K.T. Schmitt, A. Shore, M.S. Smith, D.W. Stracener, S.R. Stroberg, J. Tostevin, R.L. Varner, D. Weisshaar, K. Wimmer, R. Winkler

Recent Direct Reaction Experimental Studies with Radioactive Tin Beams

Acta Phys. Pol. B 46, 537 (2015)

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abstract

Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the $Z=50$ proton shell closure, as well as the neutron shell closures lying in the neutron-rich, $N=82$, and neutron-deficient, $N=50$, regions. Here, we present two examples of direct reactions on exotic tin isotopes. The first uses a one-neutron transfer reaction and a low-energy reaccelerated ISOL beam to study states in $^{131}$Sn from across the $N=82$ shell closure. The second example utilizes a one-neutron knockout reaction on fragmentation beams of neutron-deficient $^{106,108}$Sn. In both cases, measurements of $\gamma$ rays in coincidence with charged particles proved to be invaluable.

Study of the Unbound $^{13}$Be Resonance in a ($p,2p$) Reaction at GSI

Acta Phys. Pol. B 46, 547 (2015)

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abstract

The neutron-rich unbound resonance $^{13}$Be is a key to understand the Borromean nucleus $^{14}$Be that is situated on the edge of the neutron dripline. This contribution reports on a kinematically-complete measurement at relativistic energies, performed by the R3B Collaboration using the $^{14}$B$(p,2p)^{13}$Be reaction in inverse kinematics.

Theoretical Description of the Decay Chain of the Nucleus $^{289}115$

Acta Phys. Pol. B 46, 551 (2015)

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abstract

A theoretical analysis of the $\alpha$-decay chain of the superheavy nucleus $^{289}115$ is performed. The study is done in two variants using two realistic nuclear-mass models (HN and WS3+). The experimental $\alpha$-transition energies $Q_{\alpha }^{\rm t}$ are reproduced by the calculations with the average accuracy of 200 keV and 220 keV in the HN and WS3+ variants, respectively. The experimental half-lives are reproduced, on the average, within the factors 3.5 and 4.6, when the HN and WS3+ mass models are used, respectively. The effect of the odd proton in the nucleus $^{281}$Rg, which decays mainly by spontaneous fission, on its spontaneous-fission half-life $T_{\rm sf}$ is estimated. The effect is the elongation of $T_{\rm sf}$ by a large factor of 140.

full authors' list

L. Csige, M. Csatlós, T. Faestermann, J. Gulyás, D. Habs, A. Krasznahorkay, P.G. Thirolf, T.G. Tornyi, H.-F. Wirth

Transmission Resonance Spectroscopy of the Doubly Odd $^{238}$Np in ($d$,pf) Reaction

Acta Phys. Pol. B 46, 559 (2015)

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abstract

The fission probability of $^{238}$Np was measured as a function of the excitation energy in the energy range of $E^*=5.4$–6.2 MeV in order to search for hyperdeformed rotational bands using the ($d$,pf) transfer reaction on a radioactive $^{237}$Np target. The experiment was performed at the Tandem accelerator of the Maier-Leibnitz Laboratory at Garching employing the $^{237}$Np($d$,pf) reaction at a bombarding energy of E$_d=12$ MeV. Overlapping resonances have been observed at excitation energies around $E^*=5.5$ MeV. These resonances could be ordered into a hyperdeformed rotational band by the preliminary analysis of the high-resolution excitation energy spectrum. The existence of a third minimum in the fission barrier of $^{238}$Np is also supported by nuclear reaction code (TALYS1.4) calculations which was used to describe the experimental data.

Influence of Shell Structure on Level Densities of Superheavy Nuclei

Acta Phys. Pol. B 46, 563 (2015)

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abstract

The intrinsic level densities of superheavy nuclei in the $\alpha$-decay chains of $^{296;298;300}120$ nuclei are calculated using the single-particle spectra obtained with the modified two-center shell model. The level density parameters are extracted and compared with their phenomenological values used in the calculations of the survival of excited heavy nuclei. The dependences of the level density parameters on the mass and charge numbers as well as on the ground-state shell corrections are studied.

full authors' list

A. Chietera, L. Stuttgé, F. Gönnenwein, Yu. Kopatch, M. Mutterer, I. Guseva, A. Gagarski, E. Chernysheva, O. Dorvaux, F.J. Hambsch, F. Hanappe, Z. Mezentsevah, S. Telezhnikovch

Neutron Emission Anisotropy in Fission

Acta Phys. Pol. B 46, 569 (2015)

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abstract

Experimental neutron angular distributions are investigated in the spontaneous fission process of $^{252}$Cf. The CORA experiment, presented in this paper, has the aim to study neutron angular correlations in order to elucidate the neutron emission mechanisms in the fission process. The experimental setup is composed by the CODIS fission chamber and the DEMON neutron multidetector. The development of a simulation toolkit based on GEANT4 and ROOT adopted as strategy to investigate the emission of the neutrons is described. Preliminary results on the sources of the anisotropy, scission neutron emission and/or dynamical anisotropy, are shown.

full authors' list

J. Sadhukhan, K. Mazurek, J. Dobaczewski, W. Nazarewicz, J.A. Sheikh, A. Baran

Multidimensional Skyrme-density-functional Study of the Spontaneous Fission of $^{238}$U

Acta Phys. Pol. B 46, 575 (2015)

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abstract

We determined the spontaneous fission lifetime of $^{238}$U by a minimization of the action integral in a three-dimensional space of collective variables. Apart from the mass-distribution multipole moments $Q_{20}$ (elongation) and $Q_{30}$ (left–right asymmetry), we also considered the pairing-fluctuation parameter $\lambda _{2}$ as a collective coordinate. The collective potential was obtained self-consistently using the Skyrme energy density functional SkM$^*$. The inertia tensor was obtained within the nonperturbative cranking approximation to the adiabatic time-dependent Hartree–Fock–Bogoliubov approach. The pairing-fluctuation parameter $\lambda _{2}$ allowed us to control the pairing gap along the fission path, which significantly changed the spontaneous fission lifetime.

Analysis of Experimental Data from Fusion-fission Reactions Within Four-dimensional Langevin Dynamics

Acta Phys. Pol. B 46, 579 (2015)

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abstract

A four-dimensional stochastic approach to dynamics of nuclear fission induced by heavy ions was applied to analyze the key observables from fusion-fission reactions resulted in the highly excited compound nuclei. We 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. We systematically investigated the possible deformation dependence of the viscosity coefficient $k_{\rm s}$ predicted by chaos theory and deformation dependence of the $\gamma _K$ coefficient deduced by Lestone et al. In the framework of 4D dynamical model, we examined the correlation between dissipation strength and mass, energy and angular distributions of fission fragments. Our calculations demonstrate that the deformation dependent coefficient $k_{\rm s}$ and $\gamma _K$ value obtained by Lestone is suitable for simultaneous description of experimental mass-energy and angular distributions of fission fragments in 4D model for heavy nuclei, in contrast with the 3D model. The influence of $k_{\rm s}$ and $\gamma _K$ parameters on the calculated results could be separated.

Nuclear Fission Modelling with SPY

Acta Phys. Pol. B 46, 585 (2015)

page 585 •

abstract

A precise knowledge of the impact of the compound nucleus characteristics on fission fragments properties like fission yield or kinetic energy is a big challenge. Since we are not able to track a nucleus splitting from compound nucleus to the fragments formation, we need a theoretical laboratory to study the fission mechanism and to have access to the correlation between the fragments properties and their nuclear structure, such as shell correction, pairing or collective degrees of freedom. To bring some answers, a new model named SPY (Scission Point Yields) has been developed to determine fission fragments characteristics using a statistical description of the fission process at the scission point. The most important property of the model relies on the nuclear structure of the fragments which is derived from full quantum microscopic calculations. This approach allows computing the fission final state of extremely exotic nuclei which are inaccessible by most of the fission model available on the market.

full authors' list

F. Gramegna, A. Andrighetto, M. Bellato, D. Benini, G. Bisoffi, J. Bermudez, E. Brezzi, L. Calabretta, M. Calderolla, S. Canella, S. Carturan, M. Cinausero, M. Comunian, L. Costa, S. Corradetti, G. De Angelis, J. Esposito, E. Fagotti, P. Favaron, A. Galatá, M. Giacchini, M. Gulmini, M. Lollo, A. Lombardi, M. Manzolaro, M. Maggiore, D. Maniero, T. Marchi, A. Monetti, R. Pengo, R. Pegoraro, A. Pisent, M. Poggi, A.M. Porcellato, C. Roncolato, M. Rossignoli, A.D. Russo, L. Sarchiapone, D. Scarpa, J.J. Valiente, J. Vasquez, D. Zafiropoulos, G. Prete

The SPES Project at LNL: Status of the Project, Technical Challenges, Instrumentation, Scientific Program

Acta Phys. Pol. B 46, 591 (2015)

page 591 •

abstract

Several technological innovations and challenges are foreseen for SPES (Selective Production of Exotic Species), the INFN project for a Nuclear Physics facility with Radioactive Ion Beams (RIBs). The project is in advanced construction in Legnaro. It will provide mostly neutron-rich exotic beams, derived by the fission fragments (10$^{13}$ fiss/s) produced in the interaction of an intense proton beam (200 $\mu$A) on a direct UCx target. The expected SPES beam intensities, their quality and, eventually, their maximum energies (up to 11 MeV/$A$ for $A=130$) will permit to perform forefront research in nuclear structure and nuclear dynamics, studying a region of the nuclear chart far from stability. By coordinating the developments on the accelerator complex and those of the experimental set-ups, a successful program can be obtained. A huge upgrading of the Linac ALPI post-accelerator is being performed. For what it concerns the instrumentation, some apparatuses are already installed at the Legnaro National Laboratory and they are regularly upgraded. Moreover, new developments are under study and construction, which are very innovative and challenging. The new instrumentation development is well inserted in international collaborations, where it was agreed to make them available for the experimentation at SPES. Several Letter of Intents have been presented to the Scientific Advisory Panel during the 2$^{\mathrm {nd}}$ SPES International Workshop (May 26–28, 2014). The presented themes represent a quite large and up-to-date scientific program to be discussed and studied in the forthcoming years.

full authors' list

T. Alexander, Zs. Podolyák, M.L. Cortes, J. Gerl, D. Rudolph, L.G. Sarmiento, F. Ameil, T. Arici, D. Bazzacco, Ch. Bauer, M.A. Bentley, A. Blazhev, M. Bowry, P. Boutachkov, R. Carroll, C. Fahlander, A. Gadea, J. Gellanki, W. Gelletly, A. Givechev, N. Goel, P. Golubev, M. Górska, A. Gottardo, E. Gregor, G. Guastalla, T. Habermann, M. Hackstein, A. Jungclaus, I. Kojouharov, W. Korten, S. Kumar, N. Kurz, N. Lalović, M. Lettmann, C. Lizarazo, C. Louchart, S. Mandal, E. Merchán, C. Michelagnoli, Th. Möller, K. Moschner, Z. Patel, N. Pietralla, S. Pietri, D. Ralet, M. Reese, P.H. Regan, P. Reiter, H. Schaffner, P. Singh, C. Stahl, R. Stegmann, O. Stezowksi, J. Taprogge, P. Thöle, P.M. Walker, O. Wieland, A. Wendt, E. Wilson, R. Wood, H.-J. Wollersheim

Isomeric Ratios in $^{206}$Hg

Acta Phys. Pol. B 46, 601 (2015)

page 601 •

abstract

$^{206}$Hg was populated in the fragmentation of an $E/A=1$ GeV $^{208}$Pb beam at GSI. It was part of a campaign to study nuclei around $^{208}$Pb via relativistic Coulomb excitation. The observation of the known isomeric states confirmed the identification of the fragmentation products. The isomeric decays were also used to prove that the correlations between beam identification detectors and the AGATA $\gamma$-ray tracking array worked properly and that the tracking efficiency was independent of the time relative to the prompt flash.

full authors' list

M. Klintefjord, K. Hadyńska-Klęk, J. Samorajczyk, A. Görgen, Ch. Droste, J. Srebrny, T. Abraham, C. Bauer, F.L. Bello Garrote, S. Bönig, A. Damyanova, F. Giacoppo, E. Grodner, P. Hoff, M. Kisieliński, M. Komorowska, W. Korten, M. Kowalczyk, J. Kownacki, A.C. Larsen, R. Lutter, T. Marchlewski, P. Napiorkowski, J. Pakarinen, E. Rapisarda, P. Reiter, T. Renstrøm, B. Siebeck, S. Siem, A. Stolarz, R. Szenborn, P. Thöle, T. Tornyi, A. Tucholski, G.M. Tveten, P. Van Duppen, M.J. Vermeulen, N. Warr, H. De Witte, M. Zielińska

Spectroscopy of Low-lying States in $^{140}$Sm

Acta Phys. Pol. B 46, 607 (2015)

page 607 •

abstract

Electromagnetic transition strengths and spectroscopic quadrupole moments for $^{140}$Sm were measured by means of multi-step Coulomb excitation with radioactive beam at the ISOLDE facility at CERN. A complementary experiment was performed at the Heavy Ion Laboratory in Warsaw to assign spins for non-yrast states using the angular correlation technique. Based on the new experimental data previous spin assignments need to be revised.

full authors' list

P.R. John, V. Modamio, J.J. Valiente-Dobón, D. Mengoni, S. Lunardi, T.R. Rodríguez

Shape Evolution in the Neutron-rich Osmium Isotopes: Prompt $\gamma$-ray Spectroscopy of ${}^{196}$Os

Acta Phys. Pol. B 46, 613 (2015)

page 613 •

abstract

In order to investigate the shape evolution in the neutron-rich osmium isotopes, the first in-beam $\gamma$-ray spectroscopic measurement of $^{196}{\rm Os}$ was performed at the Laboratori Nazionali di Legnaro, Italy. $^{196}{\rm Os}$ was populated in the two-proton-transfer channel $^{198}{\rm Pt} ({}^{82}{\rm Se}, {}^{84}{\rm Kr}) {}^{196}{\rm Os}$ with a beam energy of $426$ MeV. The beam-like recoils were detected in the large-acceptance magnetic spectrometer PRISMA and the coincident $\gamma$ rays were measured by the AGATA demonstrator. The de-excitation of the two lowest-lying yrast states was observed for the first time and a candidate for the $6^+_1$-level was found. The comparison with state-of-the-art beyond mean-field calculations reveal the $\gamma$-soft character of $^{196}{\rm Os}$.

full authors' list

C.M. Shand, E. Wilson, Zs. Podolyák, H. Grawe, B.A. Brown, B. Fornal, R.V.F. Janssens, M. Bowry, M. Bunce, M.P. Carpenter, R.J. Carroll, C.J. Chiara, N. Cieplicka-Oryńczak, A.Y. Deo, G.D. Dracoulis, C.R. Hoffman, R.S. Kempley, F.G. Kondev, G.J. Lane, T. Lauritsen, G. Lotay, M.W. Reed, P.H. Regan, C. Rodriguez-Triguero, D. Seweryniak, B. Szpak, P.M. Walker, S. Zhu

Structure of $^{207}$Pb Populated in $^{208}$Pb + $^{208}$Pb Deep-inelastic Collisions

Acta Phys. Pol. B 46, 619 (2015)

page 619 •

abstract

The yrast structure of $^{207}$Pb above the $13/2^+$ isomeric state has been investigated in deep-inelastic collisions of $^{208}$Pb and $^{208}$Pb at ATLAS, Argonne National Laboratory. New and previously observed transitions were measured using the Gammasphere detector array. The level scheme of $^{207}$Pb is presented up to $\sim 6$ MeV, built using coincidence and $\gamma$-ray intensity analyses. Spin and parity assignments of states were made, based on angular distributions and comparisons to shell model calculations.

full authors' list

K. Rezynkina, K. Hauschild, A. Lopez-Martens, O. Dorvaux, B. Gall, F. Déchery, H. Faure, A.V. Yeremin, M.L. Chelnokov, V.I. Chepigin, A.V. Isaev, I.N. Izosimov, D.E. Katrasev, A.N. Kuznetsov, A.A. Kuznetsova, O.N. Malyshev, A.G. Popeko, Y.A. Popov, E.A. Sokol, A.I. Svirikhin, J. Piot, J. Rubert

First Experimental Tests of SHELS: a New Heavy Ion Separator at the JINR

Acta Phys. Pol. B 46, 623 (2015)

page 623 •

abstract

A new Separator for Heavy ELement Spectroscopy (SHELS) has been recently installed at the U-400 accelerator at FLNR, JINR in Dubna, Russia. The details of the upgrade as well as the results from some of the commissioning runs are discussed. In particular, transmission tests with the $^{208}$Pb($^{40}$Ar, 2–3$n$)$^{245-6}$Fm reaction, as well as isomer spectroscopy results for $^{210}$Ra produced in $^{164}$Dy($^{50}$Ti, 3–5$n$)$^{209-11}$Ra reaction are presented.

Structure of Light Neutron-rich Nuclei Studied with Transfer Reactions

Acta Phys. Pol. B 46, 627 (2015)

page 627 •

abstract

Transfer reactions have been used for many years to understand the shell structure of nuclei. Recent studies with rare-isotope beams extend this work and make it possible to probe the evolution of shell structure far beyond the valley of stability, requiring measurements in inverse kinematics. We present a novel technical approach to measurements in inverse kinematics, and apply this method to different transfer reactions, each of which probes different properties of light, neutron-rich nuclei.

full authors' list

S. Leoni, G. Bocchi, S. Bottoni, D. Bazzacco, N. Cieplicka, B. Fornal, B. Szpak, C. Michelagnoli, A. Blanc, G. De France, M. Jentschel, U. Køster, R. Lozeva, P. Mutti, T. Soldner, G. Simpson, C. Ur, W. Urban

Particle-core Couplings Close to Neutron-rich Doubly-magic Nuclei

Acta Phys. Pol. B 46, 637 (2015)

page 637 •

abstract

Preliminary results are presented from a recent campaign of experiments, performed at the PF1B cold-neutron facility at ILL (Grenoble, France), in which $\gamma$-ray spectroscopy of neutron-rich nuclei produced in neutron induced fission on $^{235}$U and $^{241}$Pu targets was performed. By using the EXILL array, consisting of EXOGAM, GASP and ILL-Clover detectors, and a digital triggerless data acquisition system, $\gamma$ coincidences over several microseconds time windows were studied. This allowed to obtain new information on nuclei around $^{132}$Sn, such as $^{132}$Te, $^{133}$Sb and $^{130}$Sn, in which microsecond isomeric states occur. Preliminary results on $^{210}$Bi, populated by cold-neutron capture, are also shown. The data offer the possibility to investigate the couplings between core excitations and valence particles, around the doubly magic nuclei $^{132}$Sn and $^{208}$Pb.

full authors' list

G. Bocchi, S. Leoni, S. Bottoni, A. Blanc, G. De France, M. Jentschel, U. Køster, P. Mutti, T. Soldner, G. Simpson, C. Ur, W. Urban

Study of Low-spin States in Ca Isotopes via Neutron Capture Reactions

Acta Phys. Pol. B 46, 647 (2015)

page 647 •

abstract

Preliminary results are presented from a $\gamma$-spectroscopy study of low-spin states of $^{41,49}$Ca isotopes, produced by neutron capture on a Ca target, at very high coincidence rates. The experiment was performed at the PF1B cold-neutron facility at ILL (Grenoble, France), using the EXILL array, consisting of EXOGAM, GASP and ILL-Clover detectors.

full authors' list

Ł.W. Iskra, R. Broda, R.V.F. Janssens, J. Wrzesiński, C.J. Chiara, M.P. Carpenter, B. Fornal, N. Hoteling, F.G. Kondev, W. Królas, T. Lauritsen, T. Pawłat, D. Seweryniak, I. Stefanescu, W.B. Walters, S. Zhu

E2 Transition Probabilities for Decays of Isomers Observed in Neutron-rich Odd Sn Isotopes

Acta Phys. Pol. B 46, 651 (2015)

page 651 •

abstract

High-spin 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. By exploiting delayed- and cross-coincidence techniques, level schemes have been delineated in odd $^{119-125}$Sn isotopes. Particular attention was paid to the occurrence of 19/2$^+$ and 23/2$^+$ isomeric states for which the available information has now been significantly extended. Reduced transition probabilities, $B$(E2), extracted from the measured half-lives and the established details of the isomeric decays exhibit a striking regularity. This behavior was compared with the previously observed regularity of the $B$(E2) amplitudes for the seniority $\nu = 2$ and 3, 10$^+$ and 27/2$^-$ isomers in even- and odd-Sn isotopes, respectively.

full authors' list

Y. Fujita, B. Rubio, T. Adachi, B. Blank, H. Fujita, W. Gelletly, F. Molina, S.E.A. Orrigo

Gamow–Teller Excitations Studied by Weak and Strong Interactions

Acta Phys. Pol. B 46, 657 (2015)

page 657 •

abstract

Studying weak nuclear responses, especially the Gamow–Teller (GT) transitions starting from stable as well as unstable nuclei, provide crucial and critical information on nuclear structure. Therefore, the study of GT transitions is a key issue in nuclear physics and also nuclear-astrophysics. Under the assumption of isospin symmetry, it is expected that the structure of mirror nuclei and the GT transitions starting from their ground states are identical. We have studied the corresponding GT transitions starting from $T_{z}= \pm 1$ and $\pm 2$ $pf$-shell nuclei, respectively, by means of hadronic ($^3{\rm He},t$) charge-exchange reactions and mirror $\beta$ decays. The results on GT strength distributions measured in $\beta$ decays and ($^3{\rm He},t$) reactions performed at an intermediate incident energy of 140 MeV/nucleon and $0^{\circ }$ are compared. The combined results help provide an understanding of nuclear structure of nuclei far-from-stability.

Recent Advances in the Shell Model Calculations of the Spectroscopic Properties of $^{134,136,138}$Sn

Acta Phys. Pol. B 46, 669 (2015)

page 669 •

abstract

This manuscript reviews recent results of the shell model calculations based on a realistic interaction, where the properties of $^{134,136,138}$Sn isotopes are investigated, including the model space above $^{110}$Zr. Spectra, transitions strengths and masses are in overall good agreement with the experimental data.

Particle-hole Nature of the Light High-spin Toroidal Isomers

Acta Phys. Pol. B 46, 675 (2015)

page 675 •

abstract

Nuclei under non-collective rotation with a large angular momentum above some threshold can assume a toroidal shape. In our previous work, we showed by using cranked Skyrme–Hartree–Fock approach that even–even, $N=Z$, high-$K$, toroidal isomeric states may have general occurrences for light nuclei with $28\leq A \leq 52$. We present here some additional results and systematics on the particle-hole nature of these high-spin toroidal isomers.

Multiple Chiral Bands Associated with the Same Strongly Asymmetric Many-particle Nucleon Configuration

Acta Phys. Pol. B 46, 683 (2015)

page 683 •

abstract

Multi-particle-plus-triaxial-rotor (MPR) model calculations were performed for chiral partner bands associated with strongly asymmetric many-particle nucleon configuration in the 190 mass region. Multiple chiral systems were found, but they may not necessarily form well defined pairs of near-degenerate bands.

full authors' list

T. Marchlewski, R. Szenborn, J. Samorajczyk, E. Grodner, J. Srebrny, Ch. Droste, L. Próchniak, A.A. Pasternak, M. Kowalczyk, M. Kisieliński, T. Abraham, J. Andrzejewski, P. Decowski, K. Hadyńska-Klęk, Ł. Janiak, M. Komorowska, J. Mierzejewski, P. Napiorkowski, J. Perkowski, A. Stolarz

Electromagnetic Properties of Chiral Bands in $^{124}$Cs

Acta Phys. Pol. B 46, 689 (2015)

page 689 •

abstract

The spontaneous chiral symmetry breaking was experimentally studied at the Heavy Ion Laboratory of the University of Warsaw by use of the DSAM and DCO analysis. Obtained lifetimes, branching ratios and E2/M1 mixing ratios were used to determine $B$(M1) and $B$(E2) values. The preliminary results for $^{124}$Cs confirm spontaneous chiral symmetry breaking hypothesis in the $15\hbar$–$20\hbar$ spin range.

full authors' list

R.J. Carroll, R.D. Page, D.T. Joss, J. Uusitalo, I.G. Darby, K. Andgren, B. Cederwall, S. Eeckhaudt, T. Grahn, C. Gray-Jones, P.T. Greenlees, B. Hadinia, P.M. Jones, R. Julin, S. Juutinen, M. Leino, A.-P. Leppänen, M. Nyman, D. O'Donnell, J. Pakarinen, P. Rahkila, M. Sandzelius, J. Sarén, C. Scholey, D. Seweryniak, J. Simpson

Competing Decay Modes of a High-spin Isomer in the Proton-unbound Nucleus $^{158}$Ta

Acta Phys. Pol. B 46, 695 (2015)

page 695 •

abstract

An isomeric state at high spin and excitation energy was recently observed in the proton-unbound nucleus $^{158}$Ta. This state was observed to decay by both $\alpha$ and $\gamma$ decay modes. The large spin change required to decay via $\gamma$-ray emission incurs a lifetime long enough for $\alpha$ decay to compete. The $\alpha$ decay has an energy of 8644(11) keV, which is among the highest observed in the region, a partial half-life of 440(70) $\mu$s and changes the spin by 11$\hbar$. In this paper, additional evidence supporting the assignment of this $\alpha$ decay to the high-spin isomer in $^{158}$Ta will be presented.

full authors' list

H. Heylen, C. Babcock, J. Billowes, M.L. Bissell, K. Blaum, P. Campbell, B. Cheal, R.F. Garcia Ruiz, Ch. Geppert, W. Gins, K. Kreim, I.D. Moore, R. Neugart, G. Neyens, W. Nörtershäuser, J. Papuga, D.T. Yordanov

Collinear Laser Spectroscopy on Neutron-rich Mn Isotopes Approaching $N=40$

Acta Phys. Pol. B 46, 699 (2015)

page 699 •

abstract

We have studied $^{51,53-64}$Mn ($Z=25$) via bunched-beam collinear laser spectroscopy at ISOLDE, CERN. Model-independent information on the ground- and isomeric state spins, as well as their $g$-factors is obtained from the measured hyperfine spectra. The spins are essential for further establishing the level schemes in the mass region, while the $g$-factors reveal the changing ground state wave functions in the Mn chain approaching $N=40$.

full authors' list

J. Sethi, R. Palit, J.J. Carroll, S. Karamian, S. Saha, S. Biswas, Z. Naik, T. Trivedi, M.S. Litz, P. Datta, S. Chattopadhyay, R. Donthi, U. Garg, S. Jadhav, H.C. Jain, S. Kumar, D. Mehta, B.S. Naidu, G.H. Bhat, J.A. Sheikh, S. Sihotra, P.M. Walker

Spectroscopy of the Low-lying States Near the High Spin Isomer in $^{108}$Ag

Acta Phys. Pol. B 46, 703 (2015)

page 703 •

abstract

A comprehensive study of the low-lying states of $^{108}$Ag, near the isomeric state at $E_{\rm i} = 110$ keV with $J^\pi = 6^+$ and $T_{1/2} = 438$ y, has been presented. Spectroscopy of these states has been carried out using the reaction $^{100}$Mo($^{11}$B, $3n\gamma$)$^{108}$Ag at 39 MeV beam energy using INGA. The multipolarities and electromagnetic nature of the transitions have been assigned based on the angular correlation and polarization measurements. The experimentally identified states have been compared to the results of the Projected Hartree–Fock calculations to understand the configurations involved in these states.

full authors' list

S.E.A. Orrigo, B. Rubio, Y. Fujita, B. Blank, W. Gelletly, J. Agramunt, A. Algora, P. Ascher, B. Bilgier, L. Cáceres, R.B. Cakirli, H. Fujita, E. Ganioğlu, M. Gerbaux, J. Giovinazzo, S. Grévy, O. Kamalou, H.C. Kozer, L. Kucuk, T. Kurtukian-Nieto, F. Molina, L. Popescu, A.M. Rogers, G. Susoy, C. Stodel, T. Suzuki, A. Tamii, J.C. Thomas

$\beta$-delayed $\gamma$-proton Decay in $^{56}$Zn: Analysis of the Charged-particle Spectrum

Acta Phys. Pol. B 46, 709 (2015)

page 709 •

abstract

A study of the $\beta$ decay of the proton-rich $T_{z} = -2$ nucleus $^{56}$Zn has been reported in a recent publication. A rare and exotic decay mode, $\beta$-de-layed $\gamma$-proton decay, has been observed there for the first time in the $fp$ shell. Here, we expand on some of the details of the data analysis, focussing on the charged particle spectrum.

full authors' list

C. Mazzocchi, A. Korgul, K.P. Rykaczewski, R. Grzywacz, P. Bączyk, C.R. Bingham, N.T. Brewer, C.J. Gross, C. Jost, M. Karny, M. Madurga, A.J. Mendez II, K. Miernik, D. Miller, S. Padgett, S.V. Paulauskas, D.W. Stracener, M. Wolińska-Cichocka

Beta Decay of the Most Neutron-rich Isotopes Close to $^{78}$Ni

Acta Phys. Pol. B 46, 713 (2015)

page 713 •

abstract

In an experiment at the HRIBF, Oak Ridge National Laboratory, USA, we have investigated excited states in $^{86}$Se populated in the beta-decay of $^{86}$As. Several new transitions were identified. Preliminary results are presented.

Beta-delayed Neutron Energy Spectrum Calculated in Effective Density Model

Acta Phys. Pol. B 46, 717 (2015)

page 717 •

abstract

Effective density model is used to calculate delayed neutron spectra. Comparison is made with some of the available experimental results. The calculated spectra show good agreement, on statistical level, with the experimental results.

full authors' list

F. Browne, A.M. Bruce, T. Sumikama, I. Nishizuka, S. Nishimura, P. Doornenbal, G. Lorusso, Z. Patel, S. Rice, L. Sinclair, P.-A. Söderström, H. Watanabe, J. Wu, Z.Y. Xu, H. Baba, N. Chiga, R. Carroll, R. Daido, F. Didierjean, Y. Fang, G. Gey, E. Ideguchi, N. Inabe, T. Isobe, D. Kameda, I. Kojouharov, N. Kurz, T. Kubo, S. Lalkovski, Z. Li, R. Lozeva, N. Naoki, H. Nishibata, A. Odahara, Zs. Podolyák, P.H. Regan, O.J. Roberts, H. Sakurai, H. Schaffner, G.S. Simpson, H. Suzuki, H. Takeda, M. Tanaka, J. Taprogge, V. Werner, O. Wieland, A. Yagi

Gamma-ray Spectroscopy in the Vicinity of $^{108}$Zr

Acta Phys. Pol. B 46, 721 (2015)

page 721 •

abstract

The half-lives of $2^+_1$ states were measured for $^{102,104}$Zr and $^{106,108}$Mo to test a new implementation of a LaBr$_3$(Ce) array at the RIBF, RIKEN, Japan. The nuclei of interest were produced through the fission of a 345 MeV/nucleon $^{238}$U beam and selected by the BigRIPS separator. Fission fragments were implanted into the WAS3ABi active stopper, surrounding which, 18 LaBr$_3$(Ce) detectors provided fast $\gamma$-ray detection. Timing between the LaBr$_3$(Ce) array and plastic scintillators allowed for the measurement of half-lives of low-lying states. The preliminary results, which agree with literature values, are presented along with experimental details.

Mean Lifetime Measurements in Low-statistics Experiments

Acta Phys. Pol. B 46, 725 (2015)

page 725 •

abstract

Statistical methods, based on maximum likelihood function, suitable for mean lifetime measurements in low-statistic experiments are presented. Examples of two typical experimental methods — implantation and moving tape collector — are discussed.

Dark Matter, Dark Energy and the Future of Particle Physics

Acta Phys. Pol. B 46, 729 (2015)

page 729 •

abstract

The existence of dark matter and dark energy would be evidence for physics beyond the Standard Model of particle physics and an essential ingredient to a Standard Model of cosmology. The main avenues to making progress in these topics are the search for Super-symmetry, the search for axions and the probing of the quantum vacuum. The crucial tools needed for this research program are future particle accelerators which are affordable and ultra high intensity lasers. The advancement of basic science is dependent on these developments.

Using the Nuclear Remnants as a New Source of Information on the Space-time Evolution of Ultrarelativistic Heavy Ion Collisions

Acta Phys. Pol. B 46, 737 (2015)

page 737 •

abstract

In nucleus–nucleus collisions at high energy (typically in the range of a few or more GeV per nucleon pair in the collision c.m.s.), one usually identifies two different “zones” in the reaction: the participant zone, created by the nucleons directly participating in the reaction, and the two spectator systems — the two nuclear remnants which do not participate directly to the collision. In this work, we investigate the possibility of using the electromagnetic interaction induced by the two spectator systems as a new source of information on the space-time evolution of the participant zone.

full authors' list

C.A. Ur, D. Balabanski, G. Cata-Danil, S. Gales, I. Morjan, O. Tesileanu, D. Ursescu, I. Ursu, N.V. Zamfir

New Frontiers in Nuclear Physics Research at ELI–NP

Acta Phys. Pol. B 46, 743 (2015)

page 743 •

abstract

Extreme Light Infrastructure–Nuclear Physics (ELI–NP) is one of the three pillars of the pan-European ELI initiative aiming to use extreme electromagnetic fields for nuclear physics research. The pillar, currently under construction at Bucharest-Magurele, will comprise two major research instruments: a high power laser system and a very brilliant gamma beam system. Both systems are at the limits of the present-day’s technology. The high power laser system will consist of two 10 PW APPOLON-type lasers based on OPCPA technology with output energy higher than 200 J, pulse duration of 20–30 fs and intensities of up to 10$^{23}$–10$^{24}$ W/cm$^2$. The gamma beam, produced via inverse Compton scattering of laser pulses on a relativistic electron beam, will be characterized by high spectral density of about $10^4$ photons/s/eV, narrow bandwidth ($\lt 0.5\%$), tunable energy of up to 20 MeV and degree of linear polarization higher than 95%.

full authors' list

A. Wrońska, P. Bednarczyk, D. Böckenhoff, A. Bubak, S. Feyen, A. Konefał, K. Laihem, A. Magiera, A. Stahl, M. Ziębliński

Gamma Emission in Hadron Therapy — Experimental Approach

Acta Phys. Pol. B 46, 753 (2015)

page 753 •

abstract

Experiment Gamma-CCB at the Cyclotron Centre Bronowice focuses on investigation of gamma emission in experimental modelling of hadron therapy, searching for manifestation of the Bragg peak in gamma spectra. Experimental program comprises a series of measurements for different energies of the beam accelerated in the cyclotron Proteus C-235, as well as for several phantom materials. The paper reports on the results of the first measurements performed at 70 MeV proton beam energy and for two target materials: graphite and polymethyl methacrylate PMMA. Two different experimental techniques were tested, resulting in differential gamma spectra or spectra integrated over whole proton penetration path in a phantom. Strong correlation of the intensity of the carbon and oxygen excitation lines with the Bragg peak position has been observed in both types of measurements, confirming potential of the method in the future application in hadron therapy.

Search for $\eta$-mesic Nuclei with WASA-at-COSY

Acta Phys. Pol. B 46, 757 (2015)

page 757 •

abstract

We search for an evidence of $\eta$-mesic He with the WASA detector. Two dedicated experiments were performed at the Cooler Synchrotron COSY-Jülich. The experimental method is based on the measurement of the excitation functions for the two reaction channels: $dd \rightarrow {^3\mathrm {He}}\, p \pi ^{-}$ and $dd \rightarrow {^3\mathrm {He}}\, n \pi ^{0}$, where the outgoing $N$–$\pi$ pairs originate from the conversion of the $\eta$ meson on a nucleon inside the He nucleus. In this contribution, the experimental method is shortly described and the current status of the analysis is presented.

Version corrected according to Erratum Acta Phys. Pol. B 47, 569 (2016)

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