Science.gov

Sample records for deformed exotic nuclei

  1. Assigning {gamma} deformation from fine structure in exotic nuclei

    SciTech Connect

    Ferreira, L. S.; Maglione, E.; Arumugam, P.

    2011-10-28

    The nonadiabatic quasiparticle model for triaxial shapes is used to perform calculations for decay of {sup 141}Ho, the only known odd-Z even-N deformed nucleus for which fine structure in proton emission from both ground and isomeric states has been observed. All experimental data corresponding to this unique case namely, the rotational spectra of parent and daughter nuclei, decay widths and branching ratios for ground and isomeric states, could be well explained with a strong triaxial deformation {gamma}{approx}20. The recent experimental observation of fine structure decay from the isomeric state, can be explained only with an assignment of I{sup {pi}} = 3/2{sup +} as the decaying state, in contradiction with the previous assignment, of I{sup {pi}} 1/2{sup +}, based on adiabatic calculations. This study reveals that proton emission measurements could be a precise tool to probe triaxial deformations and other structural properties of exotic nuclei beyond the proton dripline.

  2. Exotic Nuclei

    SciTech Connect

    Galindo-Uribarri, Alfredo {nmn}

    2010-01-01

    Current experimental developments on the study of exotic nuclei far from the valley of stability are discussed. I start with general aspects related to the production of radioactive beams followed by the description of some of the experimental tools and specialized techniques for studies in reaction spectroscopy, nuclear structure research and nuclear applications with examples from selected topical areas with which I have been involved. I discuss some of the common challenges faced in Accelerator Mass Spectrometry (AMS) and Radioactive Ion Beam (RIB) science.

  3. Exotic modes of excitation in deformed neutron-rich nuclei

    SciTech Connect

    Yoshida, Kenichi

    2011-05-06

    Low-lying dipole excitation mode in neutron-rich Mg isotopes close to the drip line is investigated in the framework of the Hartree-Fock-Bogoliubov and the quasiparticle random-phase approximation employing the Skyrme and the pairing energy-density functionals. It is found that the low-lying dipole-strength distribution splits into the K{sup {pi}} = 0{sup -} and 1{sup -} components due to the nuclear deformation. The low-lying dipole strength increases as the neutron drip-line is approached.

  4. 2-D Hartee-Fock-Bogoliubov Calculations For Exotic Deformed Nuclei

    NASA Astrophysics Data System (ADS)

    Blazkiewicz, Artur; Oberacker, Volker E.; Umar, Sait A.; Teran, Edgar

    2003-10-01

    We solve the Hartree-Fock-Bogoliubov (HFB) equations in coordinate space; the computational method has been specifically designed to study ground state properties of nuclei near the neutron and proton drip lines teref1. The unique feature of our code is that it takes into account the strong coupling to high-energy continuum states, up to an equivalent single-particle energy of 60 MeV or higher. We solve the HFB equations for deformed, axially symmetric even-even nuclei in coordinate space on a 2-D lattice with Basis-Spline methods. For the p-h channel, the Skyrme (SLy4) effective N-N interaction is utilized, and for the p-p and h-h channel we use a delta interaction. Results teref2,ref3 are presented for binding energies, deformations, normal densities and pairing densities, Fermi levels, and pairing gaps. In particular, we calculate the properties of two light isotope chains up to the two-neutron dripline: oxygen (^22-28O) and sulfur (^40-52S). For some of the sulfur isotopes we found the "shape coexistence" what was also confirmed by RMF calculations of P. Ring and G.A. Lalazissis teref4. Furthermore, we study the strongly deformed heavy systems zirconium (^102,104Zr), cerium (^152Ce), and samarium (^158Sm).We are also planning to study other isotopes by running our new parallel MPI version of HFB code. Comparison with relativistic mean field theory and with experimental data is given whenever available. This work has been supported by the U.S. Department of Energy under grant No. DE-FG02-96ER40963 with Vanderbilt University. The numerical calculations were carried out on the IBM-RS/6000 SP supercomputer at NERSC in Berkeley and on our local "Beowulf" Vampire computer at Vanderbilt University. 99 ref1 Axially Symmetric Hartee-Fock-Bogoliubov calculations for nuclei near the drip lines,E. Teran, V.E. Oberacker and A.S. Umar, Phys. Rev. C 67, (June 2003) ref2 Half lives of isomeric states from SF of ^252Cf and large deformations in ^104Zr and ^158Sm, J.K. Hwang, A

  5. Exotic phenomena in nuclei

    NASA Astrophysics Data System (ADS)

    Neff, Thomas; Feldmeier, Hans; Roth, Robert

    2006-10-01

    In the Fermionic Molecular Dynamics (FMD) model the nuclear many-body system is described using Slater determinants with Gaussian wave-packets as single-particle states. The flexibility of the FMD wave functions allows for a consistent description of shell model like structures, deformed states, cluster structures as well as halos. An effective interaction derived from the realistic Argonne V18 interaction using the Unitary Correlation Operator Method is used for all nuclei. Results for nuclei in the p-shell will be presented. Halo features are present in the Helium isotopes, cluster structures are studied in Beryllium and Carbon isotopes. The interplay between shell structure and cluster structures in the ground and the Hoyle state in ^12C will be discussed.

  6. Relativistic Mean Field description of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Gambhir, Y. K.

    1994-03-01

    The Relativistic Mean Field (RMF) approach which essentially is an extension of the original σ — ω model of Walecka, has been applied to exotic nuclei as an illustration. We consider nuclei near Z = 34 in the very interesting 2p-1f region. The calculated binding energies, root mean square radii, deformations and other observables are very satisfactory and are in accordance with the experiment (where available) and also with the available empirical studies. Large deformations and shape co-existence are obtained for several cases.

  7. Exotic Light Nuclei

    ERIC Educational Resources Information Center

    Cerny, Joseph; Poskanzer, Arthur M.

    1978-01-01

    Among the light elements, nuclei with unequal numbers of protons and neutrons are highly unstable. Some survive just long enough to be detected and exhibit unusual regimes of radioactive decay. ( Autor/MA)

  8. International Symposium on Exotic Nuclei

    NASA Astrophysics Data System (ADS)

    Penionzhkevich, Yu. E.; Cherepanov, E. A.

    Methods of production of light exotic nuclei and study of their ptoperties -- Superheavy elements. Syhnthesis and properties -- Nuclear fission -- Nuclear reactions -- rare processes, decay and nuclear structure -- Experimental set-ups and future projects -- Radioactive beams. Production and research programmes -- Public relations.

  9. Exotic nuclei in astrophysics

    NASA Astrophysics Data System (ADS)

    Penionzhkevich, Yu. E.

    2012-07-01

    Recently the academic community has marked several anniversaries connected with discoveries that played a significant role in the development of astrophysical investigations. The year 2009 was proclaimed by the United Nations the International Year of Astronomy. This was associated with the 400th anniversary of Galileo Galilei's discovery of the optical telescope, which marked the beginning of regular research in the field of astronomy. An important contribution to not only the development of physics of the microcosm, but also to the understanding of processes occurring in the Universe, was the discovery of the atomic nucleus made by E. Rutherford 100 years ago. Since then the investigations in the fields of physics of particles and atomic nuclei have helped to understand many processes in the microcosm. Exactly 80 years ago, K. Yanski used a radio-telescope in order to receive the radiation from cosmic objects for the first time, and at the present time this research area of physics is the most efficient method for studying the properties of the Universe. Finally, the April 12, 1961 (50 years ago) launching of the first sputnik into space with a human being onboard, the Russian cosmonaut Yuri Gagarin, marked the beginning of exploration of the Universe with the direct participation of man. All these achievements considerably extended our ideas about the Universe. This work is an attempt to present some problems on the evolution of the Universe: the nucleosynthesis and cosmochronology from the standpoint of physics of particles and nuclei, in particular with the use of the latest results, obtained by means of radioactive nuclear beams. The comparison is made between the processes taking place in the Universe and the mechanisms of formation and decay of nuclei, as well as of their interaction at different energies. Examples are given to show the capabilities of nuclear-physics methods for studying cosmic objects and properties of the Universe. The results of

  10. Exotic nuclei and nuclear forces

    NASA Astrophysics Data System (ADS)

    Otsuka, Takaharu

    2013-01-01

    I overview new aspects of the structure of exotic nuclei as compared to stable nuclei, focusing on several characteristic effects of nuclear forces. The shell structure of nuclei has been proposed by Mayer and Jensen, and has been considered to be kept valid basically for all nuclei, with well-known magic numbers, 2, 8, 20, 28, 50, …. Nuclear forces were shown, very recently, to change this paradigm. It will be presented that the evolution of shell structure occurs in various ways as more neutrons and/or protons are added, and I will present basic points of this shell evolution in terms of the monopole interaction of nuclear forces. I will discuss three types of nuclear forces. The first one is the tensor force. The tensor force is one of the most fundamental nuclear forces, but its first-order effect on the shell structure has been clarified only recently in studies on exotic nuclei. The tensor force can change the spin-orbit splitting depending on the occupation of specific orbits. This results in changes of the shell structure in many nuclei, and consequently some of Mayer-Jensen's magic numbers are lost and new ones emerge, in certain nuclei. This mechanism can be understood in an intuitive way, meaning that the effect is general and robust. The second type of nuclear forces is central force. I will show a general but unknown property of the central force in the shell-model Hamiltonian that can describe nuclear properties in a good agreement with experiment. I will then demonstrate how it can be incorporated into a simple model of the central force, and will discuss how this force works in the shell evolution. Actually, by combining this central force with the tensor force, one can understand and foresee how the same proton-neutron interaction drives the shell evolution, for examples such as Sn/Sb isotopes, N = 20 nuclei and Ni/Cu isotopes. The distribution of single-particle strength is discussed also in comparison to (e,e‧p) experiment on 48Ca. The shell

  11. Reaction theories for exotic nuclei

    SciTech Connect

    Bonaccorso, Angela

    2012-11-20

    This contribution discusses two important dynamical effects in the scattering of exotic beams. The first part deals proton breakup. The Coulomb interactions between the core and the target and the proton and the target are treated to all orders, including also the full multipole expansion of the Coulomb potential. The dynamics of proton Coulomb breakup is compared to that of an equivalent neutron of larger binding energy in order to elucidate the differences with the well understood neutron breakup mechanism. With respect to nuclear breakup it is found that a proton behaves exactly as a neutron of larger binding energy. The extra 'effective energy' is due to the combined core-target Coulomb barrier. In Coulomb breakup we distinguish the effect of the core-target Coulomb potential (called recoil effect), with respect to which the proton behaves again as a more bound neutron, from the direct proton-target Coulomb potential. The latter gives cross sections about an order of magnitude larger than the recoil term. The two effects give rise to complicated interferences in the parallel momentum distributions. They are instead easily separable in the proton angular distributions which are therefore suggested as a very useful observable for future experimental studies. The second part has to do with the dynamics of one-neutron and one-proton removal from unstable nuclei with large asymmetry {Delta}S S{sub n}-S{sub p} in the separation energies and incident energies below 80 MeV/nucleon. Strong non-sudden effects are observed in the case of deeply-bound-nucleon removal. The corresponding parallel momentum distributions exhibit an abrupt cutoff at high momentum that corresponds to an energy threshold occurring when the incident energy per particle is of comparable magnitude as the nucleon separation energy.

  12. Study of Nuclear Moments on Exotic Nuclei

    SciTech Connect

    Ishihara, Masayasu

    2010-04-30

    Nuclear moments have been measured for a few tens of light unstable nuclei located very far from the line of stability using beta-NMR methods and spin-polarized RI beams. The obtained values of those moments provided indispensable information to reveal/disentangle unique properties of exotic nuclei.

  13. Exotic nuclei with open heavy flavor mesons

    SciTech Connect

    Yasui, Shigehiro; Sudoh, Kazutaka

    2009-08-01

    We propose stable exotic nuclei bound with D and B mesons with respect to heavy quark symmetry. We indicate that an approximate degeneracy of D(B) and D*(B*) mesons plays an important role, and discuss the stability of DN and BN bound states. We find the binding energies 1.4 MeV and 9.4 MeV for each state in the J{sup P}=1/2{sup -} with the I=0 channel. We discuss also possible existence of exotic nuclei DNN and BNN.

  14. Transfer involving deformed nuclei

    SciTech Connect

    Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.

    1985-03-01

    Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs.

  15. Direct Reactions with Exotic Nuclei

    SciTech Connect

    Baur, G.; Typel, S.

    2005-10-14

    We discuss recent work on Coulomb dissociation and an effective-range theory of low-lying electromagnetic strength of halo nuclei. We propose to study Coulomb dissociation of a halo nucleus bound by a zero-range potential as a homework problem. We study the transition from stripping to bound and unbound states and point out in this context that the Trojan-Horse method is a suitable tool to investigate subthreshold resonances.

  16. Dynamical effects in fusion with exotic nuclei

    NASA Astrophysics Data System (ADS)

    Vo-Phuoc, K.; Simenel, C.; Simpson, E. C.

    2016-08-01

    Background: Reactions with stable beams have demonstrated strong interplay between nuclear structure and fusion. Exotic beam facilities open new perspectives to understand the impact of neutron skin, large isospin, and weak binding energies on fusion. Microscopic theories of fusion are required to guide future experiments. Purpose: To investigate new effects of exotic structures and dynamics in near-barrier fusion with exotic nuclei. Method: Microscopic approaches based on the Hartree-Fock (HF) mean-field theory are used for studying fusion barriers in -54Ca40+116Sn reactions for even isotopes. Bare potential barriers are obtained assuming frozen HF ground-state densities. Dynamical effects on the barrier are accounted for in time-dependent Hartree-Fock (TDHF) calculations of the collisions. Vibrational couplings are studied in the coupled-channel framework and near-barrier nucleon transfer is investigated with TDHF calculations. Results: The development of a neutron skin in exotic calcium isotopes strongly lowers the bare potential barrier. However, this static effect is not apparent when dynamical effects are included. On the contrary, a fusion hindrance is observed in TDHF calculations with the most neutron-rich calcium isotopes which cannot be explained by vibrational couplings. Transfer reactions are also important in these systems due to charge equilibration processes. Conclusions: Despite its impact on the bare potential, the neutron skin is not seen as playing an important role in the fusion dynamics. However, the charge transfer with exotic projectiles could lead to an increase of the Coulomb repulsion between the fragments, suppressing fusion. The effects of transfer and dissipative mechanisms on fusion with exotic nuclei deserve further studies.

  17. Perspectives of Physics of Exotic Nuclei Beyond the Shell Evolution

    NASA Astrophysics Data System (ADS)

    Otsuka, Takaharu

    2015-11-01

    I present one of the possible paradigm shifts with exotic nuclei. This is the shell evolution due to nuclear forces, such as tensor, central and three-nucleon forces. I shall present major points with the N=34 magic number confirmed in 54Ca by RIBF of RIKEN very recently, after the theoretical prediction made in 2001. The shell evolution has been generalized to phenomena caused by massive particle-hole excitations, being referred to as Type II Shell Evolution. This can be found in 68,70Ni. In particular, the shape coexistence of spherical, oblate and prolate shapes is suggested theoretically. Thus, the perspectives of physics with exotic nuclei is being expanded further from single-particle aspects to shapes/deformation, changing the landscape of nuclear structure.

  18. Physics of Exotic Nuclei at RIBF

    NASA Astrophysics Data System (ADS)

    Sakurai, Hiroyoshi

    2014-09-01

    ``Exotic nuclei'' far from the stability line are unique objects of many-body quantum system, where ratios of neutron number to proton number are much larger or much smaller than those of nuclei found in nature. Their exotic properties and phenomena emerge from their large isospin asymmetry, and even affect scenarios of nucleosynthesis in the universe. Efforts have been made to produce and investigate such exotic nuclei at the accelerator facilities in the world. One of the facilities, the Radioactive Isotope Beam Factory (RIBF) facility at RIKEN, Japan has delivered intense radioactive isotope (RI) beams since 2007. In US, the Facility for Rare Isotope Beams is being constructed to start around 2020. To access nuclei far from the stability line, especially neutron-rich nuclei, the RIBF facility is highly optimized for inflight production of fission fragments via a U beam. The Super-conducting Ring Cyclotron delivers a 345 MeV/u U beam. The U nuclide is converted at a target to fission fragments. An inflight separator BigRIPS was designed to collect about 50% of fission fragments produced at the target and separate nuclei of interest. The RI beams produced at BigRIPS are then delivered to several experimental devices. Large-scale international collaborations have been formed at three spectrometers to conduct unique programs for the investigation of decay properties single particle orbits, collective motions, nucleon correlation, and the equation-of-state of asymmetric nuclear matter. Nuclear binding energy will be measured at a newly constructed ring for the r-process path, and charge distribution of exotic nuclei will be examined at a unique setup of an RI target section in an electron storage ring. Ultra slow RI beams available at a gas catcher system will be utilized for table-top and high precision measurements. In this talk, I would give a facility overview of RIBF, and introduce objectives at RIBF. Special emphasis would be given to selected recent highlights

  19. IBA in deformed nuclei

    SciTech Connect

    Casten, R.F.; Warner, D.D.

    1982-01-01

    The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for /sup 168/Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong ..beta.. ..-->.. ..gamma.. transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the ..beta.. ..-->.. ..gamma.. transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ..delta..K=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics.

  20. Neutron scattering on deformed nuclei

    NASA Astrophysics Data System (ADS)

    Hansen, L. F.; Haight, R. C.; Pohl, B. A.; Wong, C.; Lagrange, Ch.

    1985-01-01

    Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9Be, C, 181Ta, 232Th, 238U, and 239Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune, and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonably good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP.

  1. Single particle versus collectivity, shapes of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Jungclaus, Andrea

    2016-03-01

    In this article some selected topics of nuclear structure research will be discussed as illustration of the progress reached in this field during the last thirty years. These examples evidence the improvement of our understanding of the atomic nucleus reached on the basis of countless experiments, performed to study both exotic nuclei (nuclei far-off the valley of stability) as well as nuclei under exotic conditions (high excitation energy/temperature or large angular momentum/rotational frequency), using stable and radioactive ion beams. The experimental progress, in parallel to the advancement of modern theoretical descriptions, led us to a much richer view of this fundamental many-body system.

  2. JUSTIPEN: Japan US Theory Institute for Physics with Exotic Nuclei

    SciTech Connect

    Papenbrock, Thomas

    2014-05-16

    The grant “JUSTIPEN: Japan US Theory Institute for Physics with Exotic Nuclei ” (DOE DE‐FG02‐06ER41407) ran from 02/01/2006 thru 12/31/2013. JUSTIPEN is a venue for international collaboration between U.S.‐based and Japanese scientists who share an interest in theory of rare isotopes. Since its inception JUSTIPEN has supported many visitors, fostered collaborations between physicists in the U.S. and Japan, and enabled them to deepen our understanding of exotic nuclei and their role in cosmos.

  3. Exotic rotations and triaxiality in Nd nuclei

    NASA Astrophysics Data System (ADS)

    Petrache, C. M.

    2015-11-01

    We have recently studied the Nd nuclei up to very high spins and identified a multitude of bands which are interpreted as the manifestation of a nucleus with stable triaxial shape, presenting various types of collective motion: tilted axis and principal axis rotation, wobbling motion, chiral bands. Seniority isomers built on nearly spherical shapes up to very high spins, surrounded by coexisting triaxial bands, have also been observed. The new results obtained from the systematics of the high-spin bands of Nd nuclei are discussed.

  4. Towards a Deeper Understanding of the Nucleus with Exotic Nuclei

    NASA Astrophysics Data System (ADS)

    Ormand, Erich

    2006-10-01

    Despite more than fifty years of study, many questions about now nuclei are put together remain. While nuclei near the valley of stability have provided a wealth of information, they are not sufficient to provide us with a comprehensive and unified description of the nucleus. Especially lacking is an accurate picture of those exotic species that are the basis of cosmic alchemy. The missing pieces in the puzzle can be filled in with a determined experimental and theoretical effort focusing on nuclei lying far from the valley of stability. Here, I will outline the intellectual challenges that can be addressed by proposed exotic-beam facilities, and how new experimental data will quide and refine theoretical descriptions of the nucleus.

  5. The surface geometry of exotic nuclei

    SciTech Connect

    Carlson, B. V.; Baldini-Neto, E.; Hirata, D.; Peru-Desenfants, S.; Berger, J.-F.; Chamon, L. C.

    2007-02-12

    We analyze the surface geometry of the spherical even-even Ca, Ni, Sn and Pb nuclei using two approaches: The relativistic Dirac-Hartree-Bogoliubov one with several parameter sets and the non-relativistic Hartree-Fock-Bogoliubov one with the Gogny force. The proton and neutron density distributions are fitted to two-parameter Fermi density distributions to obtain the half-density radii and diffuseness parameters. Those parameters allow us to determine the nature of the neutron skins predicted by the models. The calculations are compared with existing experimental data.

  6. Fusion and reactions of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Martel, I.; Aguilera, E. F.; Acosta, L.; Sánchez-Benítez, A. M.; Wolski, R.

    2011-10-01

    Close to the drip lines, the scattering cross sections of halo nuclei show a different behaviour as compared to the tightly bound projectiles of the stability line. Several experiments carried out in the last decade have been dedicated to investigate the competition between transfer, breakup and fusion channels at energies around and below the Coulomb barrier. The rather complex scenario gives rise to conflicting conclusions concerning the effect of breakup and transfer on reaction dynamics and the sub-barrier fusion process. In this work we discuss recent experimental findings in fusion and reactions of 6He halo nucleus at energies around the Coulomb barrier.

  7. Reactions and structure of exotic nuclei

    SciTech Connect

    Esbensen, H.

    1993-08-01

    Radioactive beam experiments have made it possible to study the structure of light neutron rich nuclei. A characteristic feature is a large dipole strength near threshold. An excellent example is the loosely bound nucleus ``Li for which Coulomb dissociation plays a dominant role in breakup reactions on a high Z target. I will describe a three-body model and apply it to calculate the dipole response of {sup 11}Li and the momentum distributions for the three-body breakup reaction: {sup 11}Li {yields} {sup 9}Li+n+n, and comparisons will be made to recent three-body coincidence measurements.

  8. Clusterization and quadrupole deformation in nuclei

    SciTech Connect

    Cseh, J.; Algora, A.; Antonenko, N. V.; Jolos, R. V.; Scheid, W.; Darai, J.; Hess, P. O.

    2006-04-26

    We study the interrelation of the clusterization and quadrupole deformation of atomic nuclei, by applying cluster models. Both the energetic stability and the exclusion principle is investigated. Special attention is paid to the relative orientations of deformed clusters.

  9. Exotic modes of excitation in proton rich nuclei

    SciTech Connect

    Paar, N.

    2011-11-30

    The framework of relativistic energy density functional has been applied in description of excitation phenomena in nuclei close to the proton drip line. In particular, low-lying dipole excitations have been studied using relativistic quasiparticle random phase approximation, based on effective Lagrangians with density dependent meson nucleon couplings. In the isovector dipole channel, the occurrence of pronounced low-lying dipole peaks is predicted, corresponding to the proton pygmy dipole resonance. Since this exotic mode still awaits its experimental confirmation, systematic calculations have been conducted within a pool of neutron deficient nuclei, in order to identify the best possible candidates for measurements.

  10. New results on the structure of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Sakurai, Hiroyoshi

    2015-04-01

    `Exotic nuclei' far from the stability line are unique objects of many-body quantum system, where ratios of neutron number to proton number are much larger or much smaller than those of nuclei found in nature. Their exotic properties and phenomena emerge from their large isospin asymmetry, and even affect scenarios of nucleosynthesis in universe. One of the exotic emergences is shell evolution. The magic numbers of stable nuclei are known; 2, 8, 20, 28, 50, 82 and 126. However the numbers 8, 20 and 28 have been found no more magic in a neutron-rich region, and new magic numbers such as 6, 16, 32 and 34 have been discovered. To access nuclei far from the stability line, especially neutron-rich nuclei, a large heavy-ion accelerator facility `Radioactive Isotope Beam Factory (RIBF)' was constructed at RIKEN, Japan in 2007. The facility is highly optimized for inflight production of fission fragments via a U beam. The accelerator complex delivers an intense 345 MeV/u U beam. The U nuclide is converted at a target to fission fragments. The fragments of interest are collected and separated at an inflight separator, and are delivered to several experimental devices. The shell evolution programs at RIBF have been conducted with two methods; in-beam gamma spectroscopy and decay spectroscopy. A standard setup of in-beam gamma spectroscopy is combination of a NaI gamma detector array `DALI2' and a beam line spectrometer `ZeroDegree Spectrometer (ZDS)'. Coincidence measurements of de-excitation gamma rays at DALI2 and of reaction products at ZDS make it possible to select reaction channels event-by-event and to observe excited states of exotic nuclei in a specific reaction channel. Recently, a French-made thick liquid hydrogen target system `MINOS' has been introduced to access more neutron-rich nuclei. Isomer and beta-delayed gamma spectroscopy is organized with a Euroball germanium cluster array system `EURICA' and an active silicon stopper In this talk, I would like to

  11. Are the nuclei beyond 132Sn very exotic?

    NASA Astrophysics Data System (ADS)

    Lozeva, R.; Naïdja, H.; Nowacki, F.; Odahara, A.; Moon, C.-B.; NP1112-RIBF87 collaboration

    2016-06-01

    The term exotic nucleus is used for nuclei that have different from normal behavior. However, it turns out that the term normal is valid only for nuclei close to stability and more particularly for regions close to double-shell closures. As long as one drives away in the neutron-rich nuclei, especially at intermediate mass number, interplay between normal single-particle and many collective particle-hole excitations compete. In some cases with the addition of neutrons, these may turn to evolve as a skin, acting against the core nucleus that may also influence its shell evolution. Knowledge of these nuclear ingredients is especially interesting beyond the doubly-magic 132Sn, however a little is known on how the excitations modes develop with the addition of both protons and neutrons. Especially for the Sb nuclei, where one gradually increases these valence particles, the orbital evolution and its impact on exoticness is very intriguing. Experimental studies were conducted on several such isotopes using isomer and, β-decay spectroscopy at RIBF within EURICA. In particular, new data on 140Sb and 136Sb are examined and investigated in the framework of shell model calculations.

  12. Structure of exotic nuclei by large-scale shell model calculations

    SciTech Connect

    Utsuno, Yutaka; Otsuka, Takaharu; Mizusaki, Takahiro; Honma, Michio

    2006-11-02

    An extensive large-scale shell-model study is conducted for unstable nuclei around N = 20 and N = 28, aiming to investigate how the shell structure evolves from stable to unstable nuclei and affects the nuclear structure. The structure around N = 20 including the disappearance of the magic number is reproduced systematically, exemplified in the systematics of the electromagnetic moments in the Na isotope chain. As a key ingredient dominating the structure/shell evolution in the exotic nuclei from a general viewpoint, we pay attention to the tensor force. Including a proper strength of the tensor force in the effective interaction, we successfully reproduce the proton shell evolution ranging from N = 20 to 28 without any arbitrary modifications in the interaction and predict the ground state of 42Si to contain a large deformed component.

  13. PREFACE: Structure of Exotic Nuclei and Nuclear Forces

    NASA Astrophysics Data System (ADS)

    Honma, Michio; Otsuka, Takaharu; Aoi, Nori

    2006-11-01

    The International Symposium on `Structure of Exotic Nuclei and Nuclear Forces' was held at The Koshiba Hall, University of Tokyo, on 9 - 12 March 2006. This symposium was organized as an activity of the Grant-in-Aid for the specially promoted area `Monte Carlo Shell Model' from the Ministry of Education, Science, Sports and Culture (MEXT) of Japan. The symposium was sponsored by the Center for Nuclear Study (CNS) and by RIKEN. The purpose of the symposium was to discuss theoretical and experimental developments in the study of the structure of exotic nuclei and its relationship with nuclear forces. There has been much progress recently in our understanding of what the structure of exotic nuclei is and how it can be linked to nuclear forces, with emerging intriguing perspectives. The following subjects were covered in this symposium

  14. Present status and future of the shell model
  15. Effective interaction theories
  16. Experimental results and perspectives
  17. Few-body methods including ab initio calculations
  18. Advancements of mean-fieeld models
  19. Transition between shell and cluster structure
  20. Nuclear astrophysics and nuclear structure
  21. Particle physics and the shell model
  22. Emphasis was placed on the interplay between many-body structures and nuclear forces, and on the experimental clarification of these topics. Around 80 participants attended the symposium and we enjoyed 34 excellent and lively invited talks and 26 oral presentations. The organizing committee consisted of B A Brown (MSU), S Fujii (CNS), M Honma (Aizu), T Kajino (NAO), T Mizusaki (Senshu), T Motobayashi (RIKEN), K Muto (TIT), T Otsuka (Chair, Tokyo/CNS/RIKEN), P Ring (TMU), N Shimizu (Scientific Secretary, Tokyo), S Shimoura (CNS), Y Utsuno (Scientific Secretary, JAEA). Finally, we would like to thank all the speakers and the participants as well as the other organizers for their contributions which made the symposium so successful.

  23. Shell closures, loosely bound structures, and halos in exotic nuclei

    SciTech Connect

    Saxena, G.; Singh, D.

    2013-04-15

    Inspired by the recent experiments indicating doubly magic nuclei that lie near the drip-line and encouraged by the success of our relativistic mean-field (RMF) plus state-dependent BCS approach to the description of the ground-state properties of drip-line nuclei, we develop this approach further, across the entire periodic table, to explore magic nuclei, loosely bound structures, and halo formation in exotic nuclei. In our RMF+BCS approach, the single-particle continuum corresponding to the RMF is replaced by a set of discrete positive-energy states for the calculations of pairing energy. Detailed analysis of the single-particle spectrum, pairing energies, and densities of the nuclei predict the unusual proton shell closures at proton numbers Z = 6, 14, 16, 34, and unusual neutron shell closures at neutron numbers N = 6, 14, 16, 34, 40, 70, 112. Further, in several nuclei like the neutron-rich isotopes of Ca, Zr, Mo, etc., the gradual filling of lowlying single-particle resonant state together with weakly bound single-particle states lying close to the continuum threshold helps accommodate more neutrons but with an extremely small increase in the binding energy. This gives rise to the occurrence of loosely bound systems of neutron-rich nuclei with a large neutron-to-proton ratio. In general, the halo-like formation, irrespective of the existence of any resonant state, is seen to be due to the large spatial extension of the wave functions for the weakly bound single-particle states with low orbital angular momentum having very small or no centrifugal barriers.

  24. Clusterization and Deformation in Heavy Nuclei

    SciTech Connect

    Algora, A.; Cseh, J.; Darai, J.; Hess, P.O.; Antonenko, N.V.; Jolos, R.V.; Scheid, W.

    2005-11-21

    The deformation-dependence of clusterization in heavy nuclei is investigated. In particular, allowed and forbidden cluster-configurations are determined for the ground, superdeformed, and hyperdeformed states of some nuclei, based on a microscopic (effective SU(3)) selection rule. The stability of the different cluster configurations from the viewpoint of the binding energy and the dinuclear system model (DNS) is also investigated.

  25. Structure properties of medium and heavy exotic nuclei

    NASA Astrophysics Data System (ADS)

    Gaidarov, M. K.

    2012-09-01

    Investigations of important characteristics of the structure of nuclei near drip-lines in coordinate and momentum space have been performed. The charge form factors, charge and matter densities and the corresponding rms radii for even-even isotopes of Ni, Kr, and Sn are calculated in the framework of deformed self-consistent mean field Skyrme DDHF+BCS method. The resulting charge radii and neutron skin thicknesses of these nuclei are compared with available experimental data, as well as with other theoretical predictions. The formation of a neutron skin is analyzed in terms of various definitions. Its correlation with the nuclear symmetry energy is studied within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The nucleon momentum distributions for the same isotopic chains of neutron-rich nuclei are studied in the framework of the same mean-field method, as well as of theoretical correlation methods based on light-front dynamics and local density approximation. The isotopic sensitivities of the calculated neutron and proton momentum distributions are investigated together with the effects of nucleon correlations and deformation of nuclei.

  26. Three-Body Forces and Neutron-Rich Exotic Nuclei

    NASA Astrophysics Data System (ADS)

    Otsuka, Takaharu; Suzuki, Toshio

    2013-08-01

    Physics of three-body forces in connection to exotic nuclei will be discussed. Three-nucleon forces (3NF), especially Fujita-Miyazawa 3NF, are shown to be the key for the solution to the long-standing problem of oxygen drip line, which deviates from basic trend towards the stability line. Three-body forces produce repulsive modifications to effective interaction between valence neutrons, and make the ground states less bound. The oxygen drip line is then located at the right place. The relation to the neutron matter is presented. Applications to Ca isotopes will be presented. The shell evolution due to the 3NF depicts the raising of single-particle energies and the widening of splitting among the orbits. This is in contrast to the so-called shell quenching. The 2+ levels are calculated for Ca isotopes, suggesting about the same sub-magic structure for N = 32 and 34.

  27. Elastic scattering, fusion, and breakup of light exotic nuclei

    NASA Astrophysics Data System (ADS)

    Kolata, J. J.; Guimarães, V.; Aguilera, E. F.

    2016-05-01

    The present status of fusion reactions involving light ( A < 20) radioactive projectiles at energies around the Coulomb barrier ( E < 10 MeV per nucleon) is reviewed, emphasizing measurements made within the last decade. Data on elastic scattering (providing total reaction cross section information) and breakup channels for the involved systems, demonstrating the relationship between these and the fusion channel, are also reviewed. Similarities and differences in the behavior of fusion and total reaction cross section data concerning halo nuclei, weakly-bound but less exotic projectiles, and strongly-bound systems are discussed. One difference in the behavior of fusion excitation functions near the Coulomb barrier seems to emerge between neutron-halo and proton-halo systems. The role of charge has been investigated by comparing the fusion excitation functions, properly scaled, for different neutron- and proton-rich systems. Possible physical explanations for the observed differences are also reviewed.

  28. Exotic Lepton Flavour Violating Processes in the Presence of Nuclei

    NASA Astrophysics Data System (ADS)

    Papoulias, D. K.; Kosmas, T. S.

    2013-02-01

    The discovery of neutrino oscillations indicates the existence of massive neutrinos in contrast to the massless neutrinos predicted by the Standard Model. One of the simplest extensions of the SM obtained by adding a heavy right-handed neutrino singlet, NR, per neutrino generation is the Seesaw mechanism. Within the context of this mechanism, flavour changing neutral current neutrino-nucleus reactions of the type are predicted to occur. In this contribution, motivated by the extensive studies (theoretical and experimental) of the LFV in ν- → e- conversion in nuclei, we investigate FCNC in neutrino-nucleus reactions. From a nuclear theory point of view, the Donnelly-Walecka model for cross sections calculations is employed. To this purpose, the single-particle transition matrix elements are evaluated from a Mathematica code developed in this work. Neutrino-nucleus reactions have important impact in Astrophysics and hence a detailed study of such exotic processes is of significant importance.

  29. {alpha} Decay of Deformed Actinide Nuclei

    SciTech Connect

    Stewart, T.L.; Kermode, M.W.; Beachey, D.J.; Rowley, N.; Grant, I.S.; Kruppa, A.T.

    1996-07-01

    {alpha} decay through a deformed potential barrier produces significant mixing of angular momenta when mapped from the nuclear interior to the outside. Using experimental branching ratios and either semiclassical or coupled-channels transmission matrices, we have found that there is a set of internal amplitudes which is essentially constant for all even-even actinide nuclei. These same amplitudes also give good results for the known anisotropic {alpha}-particle emission of the favored decays of odd nuclei in the same mass region. {copyright} {ital 1996 The American Physical Society.}

  1. Evolution of surface deformations of weakly bound nuclei in the continuum

    NASA Astrophysics Data System (ADS)

    Pei, J. C.; Zhang, Y. N.; Xu, F. R.

    2013-05-01

    We study weakly bound deformed nuclei based on the coordinate-space Skyrme Hartree-Fock-Bogoliubov (HFB) approach, in which a large box is employed for treating the continuum and large spatial extensions. When the limit of the core-halo deformation decoupling is approached, calculations found an exotic “egg”-like structure consisting of a spherical core plus a prolate halo in 38Ne, in which the near-threshold nonresonant continuum plays an essential role. Generally the halo probability and the decoupling effect in heavy nuclei can be hindered by high level densities around Fermi surfaces. However, deformed halos in medium-mass nuclei are possible as the negative-parity levels are sparse, e.g., in 110Ge. The deformation decoupling has also been demonstrated in pairing density distributions.

  2. Large acceptance spectrometers for invariant mass spectroscopy of exotic nuclei and future developments

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Kondo, Y.

    2016-06-01

    Large acceptance spectrometers at in-flight RI separators have played significant roles in investigating the structure of exotic nuclei. Such spectrometers are in particular useful for probing unbound states of exotic nuclei, using invariant mass spectroscopy with reactions at intermediate and high energies. We discuss here the key characteristic features of such spectrometers, by introducing the recently commissioned SAMURAI facility at the RIBF, RIKEN. We also investigate the issue of cross talk in the detection of multiple neutrons, which has become crucial for exploring further unbound states and nuclei beyond the neutron drip line. Finally we discuss future perspectives for large acceptance spectrometers at the new-generation RI-beam facilities.

  3. Effective field theory for deformed atomic nuclei

    DOE PAGESBeta

    Papenbrock, Thomas F.; Weidenmüller, H. A.

    2016-04-13

    In this paper, we present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. Finally, for rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.

  4. Effective field theory for deformed atomic nuclei

    NASA Astrophysics Data System (ADS)

    Papenbrock, T.; Weidenmüller, H. A.

    2016-05-01

    We present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. For rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.

  5. Super-Heavy Element and Other Exotic Nuclei Research at LLNL

    NASA Astrophysics Data System (ADS)

    Stoyer, M. A.

    2015-11-01

    The experimental nuclear physics group at LLNL is actively investigating exotic nuclei in a variety of regions of the chart of nuclides - from light nuclei to super-heavy elements. The experimental nuclear physics effort at LLNL is centered on investigating nuclei at the extremes--in particular, extremes of spin, isospin, neutron richness, excitation energy, decay and detectability, mass, and stability. This talk will focus on recent heavy and super-heavy element experiments including nuclear structure investigations of the heaviest nuclei. Other areas of research, including radioactive ion beam experiments, trapping experiments, nuclear decay spectroscopy experiments, and rare decay searches, will be discussed as time permits. Recent experimental results on studies of exotic nuclei by scientists at LLNL will be presented.

  6. QRPA Calculations for Spherical and Deformed Nuclei With the Gogny Force

    SciTech Connect

    Peru, S.

    2009-08-26

    Fully consistent axially-symmetric-deformed Quasi-particle Random Phase Approximation (QRPA) calculations have been performed with the D1S Gogny force. Dipole responses have been calculated in Ne isotopes to study the existence of soft dipole modes in exotic nuclei. A comparison between QRPA and generator coordinate method with Gaussian overlap approximation results is done for low lying 2{sup +} states in N = 16 isotones and Ni isotopes.

  7. M1 excitation scheme in deformed nuclei

    NASA Astrophysics Data System (ADS)

    Otsuka, Takaharu; Morrison, Iain

    1991-10-01

    We present the M1 excitation scheme in even-even deformed nuclei from the sum-rule viewpoint based on the Nilsson+BCS approach. The sum-rule states are introduced for the Scissors, spin and spin-flip modes. The functional form of the B(M1) sum rule of the Scissors mode is obtained, and its actual value is shown to be 4˜6(μN2). The spin excitation B(M1) is 10˜15(μN2) including the spin-flip transitions. The total B(M1) is 15˜20(μN2). The effect of the SD and SDG pair truncation is studied to test IBM-2 for M1 excitations. The SDG truncation reproduces very well the calculation without truncation. The SD truncation reproduces the orbital excitation, whereas yields some deviations for the spin excitation.

  8. Precision lifetime measurements of exotic nuclei based on Doppler-shift techniques

    SciTech Connect

    Iwasaki, Hironori

    2013-04-19

    A recent progress in precision lifetime measurements of exotic nuclei at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University is presented. The Recoil Distance Doppler-shift (RDDS) technique has been applied to nuclear reactions involving intermediate-energy rare isotope (RI) beams, to determine absolute transition strengths between nuclear states model independently from level lifetimes of interest. As such an example, recent lifetime measurements of the first 2{sup +} states in the neutron-rich {sup 62,64,66}Fe isotopes at and around N=40 are introduced. The experiment was performed at the Coupled Cyclotron Facility at NSCL using a unique combination of several experimental instruments; the Segmented Germanium Array (SeGA), the plunger device, and the S800 spectrograph. The reduced E2 transition probabilities B(E2) are determined directly from the measured lifetimes. The observed trend of B(E2) clearly demonstrates that an enhanced collectivity persists in {sup 66}Fe despite the harmonic-oscillator magic number N=40. The present results are also discussed in comparison with the large-scale shell model calculations, pointing to a possible extension of the deformation region beyond N=40.

  9. Pygmy Dipole Strength and Neutron Skins in Exotic Nuclei

    NASA Astrophysics Data System (ADS)

    Klimkiewicz, A.; Paar, N.; Adrich, P.; Fallot, M.; Boretzky, K.; Aumann, T.; Cortina-Gil, D.; Pramanik, U. Datta; Elze, Th. W.; Emling, H.; Geissel, H.; Hellström, M.; Jones, K. L.; Kratz, J. V.; Kulessa, R.; Nociforo, C.; Palit, R.; Simon, H.; Surówka, G.; Sümmerer, K.; Vretenar, D.; Waluś, W.

    2008-05-01

    Dipole strength distributions were determined for the neutron-rich nuclei 129-132Sn and 133,134Sb from electromagnetic excitation in an experiment using the FRS-LAND setup. For all nuclei, a sizeable fraction of ``pygmy'' dipole strength at excitation energies well below the giant dipole resonance was observed. The integrated low-lying dipole strength of the nuclei with low neutron separation energies can be compared to results for stable nuclei (e.g. N = 82 isotopes) determined for the energy regime of 5-9 MeV. A clear increase of the dipole strength with increasing asymmetry of the nuclei is observed. Comparing the ratio of the low-lying dipole over the giant dipole strength to recent relativistic mean field calculations, values for the parameters a4 and p0 of the symmetry energy and for the neutron skin thickness are derived. Averaged over 130Sn and 132Sn we extract a4 = 31.8+/-1.3 MeV and p0 = 2.2+/-0.5 MeV/fm3. The neutron skin sizes are determined to Rn-Rp = 0.23+/-0.03 fm and 0.24+/-0.03 fm for 130Sn and 132Sn, respectively. For 208Pb a neutron skin thickness of Rn-Rp = 0.18+/-0.035 fm follows, when applying the same method and using earlier published experimental findings on the dipole strength.

  10. Description of Exotic Nuclei with the Interacting Boson Model

    SciTech Connect

    Boeyuekata, M.; Van Isacker, P.; Uluer, I.

    2008-11-11

    Even--even nuclei in the A{approx}100 mass region are investigated within the framework of the interacting boson model-1 (IBM-1). The study includes energy spectra and electric quadrupole transition properties of zirconium, molybdenum, ruthenium and palladium isotopes with neutron number N{>=}54. A global parametrization of the IBM-1 hamiltonian is found leading to a description of 301 collective levels in 30 nuclei with a root-mean-square deviation from the observed level energies of 119 keV. The geometric character of the nuclei can be visualized by plotting the potential energy surface V({beta},{gamma}) obtained from the IBM-1 hamiltonian in the classical limit. The parametrization established on the basis of known elements is then used to predict properties of the unknown, neutron-rich isotopes {sup 106}Zr, {sup 112}Mo, {sup 116}Ru and {sup 120}Pd.

  11. Halos and rainbows: The elastic scattering of light exotic nuclei

    SciTech Connect

    Satchler, G.R.; Hussein, M.H.

    1993-10-01

    The scattering of an exotic light nucleus with a halo is compared with that of a normal nucleus. Four, sometimes opposing effects arising from the halo are identified. Semiclassical expressions are derived which embody these effects. The cases of {sup 11}Li and {sup 11}C scattering from {sup 12}C at E/A = 60 MeV are compared. We conclude that the {sup 11}Li differential cross sections are probably smaller than those for {sup 11}C, in agreement with recent analyses of the measurements.

  12. Folding model description of reactions with exotic nuclei

    SciTech Connect

    Ibraheem, Awad A.; Hassanain, M. A.; Mokhtar, S. R.; Zaki, M. A.; Mahmoud, Zakaria M. M.; Farid, M. El-Azab

    2012-08-15

    Microscopic folding calculations based upon the effective M3Y nucleon-nucleon interaction and the nuclearmatter densities of the interacting nuclei have been carried out to explain recently measured experimental data of the {sup 6}He+{sup 120}Sn elastic scattering cross section at four different laboratory energies near the Coulomb barrier. The extracted reaction cross sections are also considered.

  13. Ab Initio Calculations Of Nuclear Reactions And Exotic Nuclei

    SciTech Connect

    Quaglioni, S.

    2014-05-05

    Our ultimate goal is to develop a fundamental theory and efficient computational tools to describe dynamic processes between nuclei and to use such tools toward supporting several DOE milestones by: 1) performing predictive calculations of difficult-to-measure landmark reactions for nuclear astrophysics, such as those driving the neutrino signature of our sun; 2) improving our understanding of the structure of nuclei near the neutron drip line, which will be the focus of the DOE’s Facility for Rare Isotope Beams (FRIB) being constructed at Michigan State University; but also 3) helping to reveal the true nature of the nuclear force. Furthermore, these theoretical developments will support plasma diagnostic efforts at facilities dedicated to the development of terrestrial fusion energy.

  14. Probing the Evolution of the Shell Structures in Exotic Nuclei

    SciTech Connect

    De Angelis, Giacomo

    2008-11-11

    Magic numbers are a key feature in finite Fermion systems since they are strongly related to the underlying mean field. The size of the shell gaps and their evolution far from stability can be linked to the shape and symmetry of the nuclear mean field. Moreover the study of nuclei with large neutron/proton ratio allow to probe the density dependence of the effective interaction. Changes of the nuclear density and size in nuclei with increasing N/Z ratios are expected to lead to different nuclear symmetries and excitations. In this contribution I will discuss some selected examples which show the big potential of stable beams and of binary reactions for the study of the properties of the neutron-rich nuclear many body systems.

  15. Light Nuclei Studied with Nucleon Transfer Reactions Using Exotic Beams

    SciTech Connect

    Wuosmaa, A. H.; Rehm, K. E.; Greene, J. P.; Henderson, D. J.; Janssens, R. V. F.; Jiang, C. L.; Moore, E. F.; Pardo, R. C.; Peterson, D.; Pieper, S. C.; Savard, G.; Schiffer, J. P.; Sinha, S.; Tang, X.; Wiringa, R. B.; Jisonna, L.; Segel, R. E.; Paul, M.

    2006-04-26

    Single-neutron transfer with the (d,p) reaction in inverse kinematics has been used to study the properties of the light nuclei 9Li and 7He. The results for 9Li and 7He are compared to the predictions of ab-initio models of nuclear structure. Different possibilities for excited states in 7He are discussed in the context of other recent experimental studies of 7He.

  16. Investigation of the structure of light exotic nuclei by proton elastic scattering in inverse kinematics

    NASA Astrophysics Data System (ADS)

    Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V.; Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.

    2015-05-01

    In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the 6He, 8He, 11Li, and 14Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the 8Li, 9Li, and 12Be nuclei.

  17. Investigation of the structure of light exotic nuclei by proton elastic scattering in inverse kinematics

    SciTech Connect

    Alkhazov, G. D.; Vorobyov, A. A.; Dobrovolsky, A. V. Inglessi, A. G.; Korolev, G. A.; Khanzadeev, A. V.

    2015-05-15

    In order to study the spatial structure of exotic nuclei, it was proposed at the Petersburg Nuclear Physics Institute (PNPI) to measure the differential cross section for small-angle proton elastic scattering in inverse kinematics. Several experiments in beams of 0.7-GeV/nucleon exotic nuclei were performed at the heavy-ion accelerator facility of GSI (Gesellschaft für Schwerionenforschung, Darmstadt, Germany) by using the IKAR ionization spectrometer developed at PNPI. The IKAR ionization chamber filled with hydrogen at a pressure of 10 bar served simultaneously as a target and as a recoil-proton detector, which measured the recoil-proton energy. The beam-particle scattering angle was also measured. The results obtained for the cross sections in question were analyzed on the basis of the Glauber-Sitenko theory using phenomenological nuclear-density distributions with two free parameters. Nuclear-matter distributions and root-mean-square radii were found for the nuclei under investigation. The size of the halo in the {sup 6}He, {sup 8}He, {sup 11}Li, and {sup 14}Be nuclei was determined among other things. Information about neutron distributions in nuclei was deduced by combining the data obtained here with the known values of the radii of proton distributions. A sizable neutron skin was revealed in the {sup 8}Li, {sup 9}Li, and {sup 12}Be nuclei.

  18. Towards a novel laser-driven method of exotic nuclei extraction-acceleration for fundamental physics and technology

    NASA Astrophysics Data System (ADS)

    Nishiuchi, M.; Sakaki, H.; Esirkepov, T. Zh.; Nishio, K.; Pikuz, T. A.; Faenov, A. Ya.; Skobelev, I. Yu.; Orlandi, R.; Pirozhkov, A. S.; Sagisaka, A.; Ogura, K.; Kanasaki, M.; Kiriyama, H.; Fukuda, Y.; Koura, H.; Kando, M.; Yamauchi, T.; Watanabe, Y.; Bulanov, S. V.; Kondo, K.; Imai, K.; Nagamiya, S.

    2016-04-01

    A combination of a petawatt laser and nuclear physics techniques can crucially facilitate the measurement of exotic nuclei properties. With numerical simulations and laser-driven experiments we show prospects for the Laser-driven Exotic Nuclei extraction-acceleration method proposed in [M. Nishiuchi et al., Phys, Plasmas 22, 033107 (2015)]: a femtosecond petawatt laser, irradiating a target bombarded by an external ion beam, extracts from the target and accelerates to few GeV highly charged short-lived heavy exotic nuclei created in the target via nuclear reactions.

  19. Toward a Fundamental Understanding of Nuclear Reactions and Exotic Nuclei

    NASA Astrophysics Data System (ADS)

    Quaglioni, Sofia; Hupin, Guillaume; Langhammer, Joachim; Romero-Redondo, Carolina; Schuster, Micah D.; Johnson, Calvin W.; Navrátil, Petr; Roth, Robert

    Nuclear systems near the drip lines offer an exciting opportunity to advance our understanding of the interactions among nucleons, which has so far been mostly based on the study of stable nuclei. However, this is not a goal devoid of challenges. From a theoretical standpoint, it requires the capability to address within an ab initio framework not only bound, but also resonant and scattering states, all of which can be strongly coupled. In recent years, significant progress has been made in ab initio nuclear structure and reaction calculations based on input from Quantum Chromodynamics employing Hamiltonians constructed within chiral effective field theory. In this contribution, we present a brief overview of one of such methods, the ab initio no-core shell model with continuum, and its applications to nucleon and deuterium scattering on light nuclei. The first investigation of the low-lying continuum spectrum of 6He within an ab initio framework that encompasses the 4He + n + n three-cluster dynamics characterizing its lowest particle-decay channel will also be briefly presented.

  20. Secondary beams and the synthesis of exotic nuclei

    SciTech Connect

    Nitschke, J.M.

    1985-09-01

    With the advent of modern fast cycling synchrotrons capable of delivering high intensity heavy ion beams up to uranium, the production of secondary radioactive ion beams (RIBs) with sufficient intensity has become feasible. The basic production mechanism is the fragmentation of near relativistic heavy ion beams on light targets. The physical facts underlying the efficient conversion of stable beams into RIBs are: (1) at beam energies of several 100 MeV/A thick conversion targets (1 to 10 g/cm/sup 2/) can be used, which, for nuclei near stability, convert on the order of .1 to 1% of the primary beam into secondary beams, (2) the secondary beams are emitted into a narrow phase space (small transverse and longitudinal emittances), and (3) these emittances are of the correct magnitude to match the acceptances of suitably designed storage and accumulator rings. 14 refs.

  1. Investigation of Coulomb dipole polarization effects on reactions involving exotic nuclei

    NASA Astrophysics Data System (ADS)

    Fernández-García, J. P.; Alvarez, M. A. G.; Chamon, L. C.

    2015-07-01

    We have analyzed elastic scattering angular distributions and total reaction cross sections of the exotic nuclei 11,9Li on 208Pb, at energies below and above the Coulomb barrier. For this purpose, we have used an optical potential with no adjustable parameters, composed by the nuclear São Paulo potential, derived from the nonlocal nature of the interaction, and the Coulomb dipole polarization potential, derived from the semiclassical theory of Coulomb excitation. Within this formalism, we identified an unusual long-range absorption for the +208Pb 11Li system, which is dominated by the Coulomb interaction. We compare it to the absorption mechanisms observed for +208Pb6He which, unlike those of +208Pb11Li, take place at small interacting distances, where both Coulomb and nuclear interactions are important. The proposed approach shows to be a fundamental basis to study reactions involving exotic nuclei.

  2. Nuclear reaction cross sections of exotic nuclei in the Glauber model for relativistic mean field densities

    SciTech Connect

    Patra, S. K.; Panda, R. N.; Arumugam, P.; Gupta, Raj K.

    2009-12-15

    We have calculated the total nuclear reaction cross sections of exotic nuclei in the framework of the Glauber model, using as inputs the standard relativistic mean field (RMF) densities and the densities obtained from the more recently developed effective-field-theory-motivated RMF (the E-RMF). Both light and heavy nuclei are taken as the representative targets, and the light neutron-rich nuclei as projectiles. We found the total nuclear reaction cross section to increase as a function of the mass number, for both the target and projectile nuclei. The differential nuclear elastic scattering cross sections are evaluated for some selected systems at various incident energies. We found a large dependence of the differential elastic scattering cross section on incident energy. Finally, we have applied the same formalism to calculate both the total nuclear reaction cross section and the differential nuclear elastic scattering cross section for the recently discussed superheavy nucleus with atomic number Z=122.

  3. Next-Generation Facilities for the Research with Exotic Nuclei and Super-Heavy Elements

    NASA Astrophysics Data System (ADS)

    Scheidenberger, Christoph

    The present decade is governed by the construction and advent of new, dedicated radioactive beam facilities in several continents. These forthcoming facilities will allow to explore hitherto unknown territory in the chart of nuclei and to study new phenomena, effects and structural features in exotic nuclei. Increasing intensity of primary and secondary beams, selective and efficient separation techniques adapted to the reaction mechanisms and production methods, and sensitive instruments and detectors are the key prerequisites for new findings and exploratory measurements. The new facilities and instruments will enhance the science potential tremendously.

  4. The structure and shape of exotic nuclei beyond the proton drip-line

    SciTech Connect

    Ferreira, L. S.; Arumugam, P.; Maglione, E.

    2008-11-11

    Proton emission from deformed nuclei with triaxial symmetry is discussed within the non-adiabatic quasi-particle approach. As an example, we consider decay from {sup 161}Re, where we were able to reproduce the experimental half-life with a noticeable {gamma} deformation.

  5. Pushing the relative mass accuracy limit of ISOLTRAP on exotic nuclei below 10 ppb

    NASA Astrophysics Data System (ADS)

    Blaum, K.; Beck, D.; Bollen, G.; Herfurth, F.; Kellerbauer, A.; Kluge, H.-J.; Moore, R. B.; Sauvan, E.; Scheidenberger, C.; Schwarz, S.; Schweikhard, L.

    2003-05-01

    The Penning trap mass spectrometer ISOLTRAP plays a leading role in mass spectrometry of short-lived nuclides. The recent installation of a radio-frequency quadrupole trap and a carbon cluster ion source allowed for the first time mass measurements on exotic nuclei with a relative uncertainty of δ m/ m≈1×10 -8. The status of ISOLTRAP mass spectrometry and recent highlights are presented.

  6. New Experiments with Stored Exotic Nuclei at the FRS-ESR Facility

    SciTech Connect

    Geissel, H.

    2009-08-26

    High accuracy mass and novel nuclear lifetime measurements have been performed with bare and few-electron ions produced via projectile fragmentation and fission, separated in flight and stored at relativistic energies. Characteristic experimental results and new developments are reviewed. A new generation of studies with exotic nuclei will be possible with the advent of the proposed international Facility for Antiproton and Ion Research (FAIR)

  7. Time-of-Flight Mass Measurements of Exotic Nuclei

    SciTech Connect

    Matos, M.; Famiano, M.; Gade, A.; George, S.; Lynch, W. G.; Rogers, A.; Stolz, A.; Wallace, M.; Yurkon, J.

    2012-01-01

    Atomic masses play an important role in nuclear physics and astrophysics. The need of experimental mass values for unstable nuclides has triggered the development of a wide range of mass measurement techniques, with devices installed at many laboratories around the world. We have implemented a time-of-flight magnetic-rigidity (TOF-B ) technique at the National Superconducting Cyclotron Laboratory (NSCL) that includes a position measurement for magnetic rigidity corrections and uses the A1900 separator and the S800 spectrograph. We performed a successful first experiment measuring masses of neutron-rich isotopes in the region of Z 20 30, important for calculations of processes occurring in the crust of accreting neutron stars. The masses of 16 nuclei were determined, for 61V, 63Cr, 66Mn, and 74Ni for the first time, with atomic mass excesses of 30.510(890) MeV, 35.280(650) MeV, 36.900(790) MeV, and 49.210(990) MeV, respectively. The mass resolution achieved was 1.8 10 4.

  8. Study of Exotic Weakly Bound Nuclei Using Magnetic Analyzer Mavr

    NASA Astrophysics Data System (ADS)

    Maslov, V. A.; Kazacha, V. I.; Kolesov, I. V.; Lukyanov, S. M.; Melnikov, V. N.; Osipov, N. F.; Penionzhkevich, Yu. E.; Skobelev, N. K.; Sobolev, Yu. G.; Voskoboinik, E. I.

    2016-06-01

    A project of the high-resolution magnetic analyzer MAVR is proposed. The analyzer will comprise new magnetic optical and detecting systems for separation and identification of reaction products in a wide range of masses (5-150) and charges (1-60). The magnetic optical system consists of the MSP-144 magnet and a doublet of quadrupole lenses. This will allow the solid angle of the spectrometer to be increased by an order of magnitude up to 30 msr. The magnetic analyzer will have a high momentum resolution (10-4) and high focal-plane dispersion (1.9 m). It will allow products of nuclear reactions at energies up to 30 MeV/nucleon to be detected with the charge resolution ∼1/60. Implementation of the project is divided into two stages: conversion of the magnetic analyzer proper and construction of the nuclear reaction products identification system. The MULTI detecting system is being developed for the MAVR magnetic analyzer to allow detection of nuclear reaction products and their identification by charge Q, atomic number Z, and mass A with a high absolute accuracy. The identification will be performed by measuring the energy loss (ΔE), time of flight (TOF), and total kinetic energy (TKE) of reaction products. The particle trajectories in the analyzer will also be determined using the drift chamber developed jointly with GANIL. The MAVR analyzer will operate in both primary beams of heavy ions and beams of radioactive nuclei produced by the U400 - U400M acceleration complex. It will also be used for measuring energy spectra of nuclear reaction products and as an energy monochromator.

  9. TOPICAL REVIEW: Shapes and collectivity of exotic nuclei via low-energy Coulomb excitation

    NASA Astrophysics Data System (ADS)

    Görgen, Andreas

    2010-10-01

    The way in which an atomic nucleus responds to excitations, whether by promoting individual nucleons into higher shells or by collective rotation or vibration, reveals many details of the underlying nuclear structure. The response of the nucleus is closely related to its macroscopic shape. Low-energy Coulomb excitation provides a well-understood means of exciting atomic nuclei, allowing the measurement of static and dynamic electromagnetic moments as a probe of the nuclear wavefunctions. Owing to the availability of radioactive heavy-ion beams with energies near the Coulomb barrier, it is now possible to study the shape and collectivity of short-lived nuclei far from β stability (the so-called exotic nuclei), providing a particularly stringent test of modern theoretical nuclear structure models. This review gives an introduction to the experimental techniques related to low-energy Coulomb excitation with radioactive ion beams and summarizes the results that were obtained over the last 10 years for a wide variety of exotic nuclei at various laboratories employing the isotope separation on-line technique.

  10. Mass extrapolations in the region of deformed rare Earth nuclei

    SciTech Connect

    Borcea, C.; Audi, G.

    1998-12-21

    A procedure based on the regularity property of the mass surface is proposed to make predictions for the masses of neutron rich deformed nuclei in the rare earth region. Tables are given for the estimated masses; they extend up to the presumed limit of the deformation region.

  11. New approach for alpha-decay calculations of deformed nuclei

    SciTech Connect

    Ni Dongdong; Ren Zhongzhou

    2010-06-15

    We present a new theoretical approach to evaluate alpha-decay properties of deformed nuclei, namely the multichannel cluster model (MCCM). The deformed alpha-nucleus potential is taken into full account, and the coupled-channel Schroedinger equation with outgoing wave boundary conditions is employed for quasibound states. Systematic calculations are carried out for well-deformed even-even nuclei with Z>=98 and isospin dependence of nuclear potentials is included in the calculations. Fine structure observed in alpha decay is well described by the four-channel microscopic calculation, which is performed for the first time in alpha-decay studies. The good agreement between experiment and theory is achieved for both total alpha-decay half-lives and branching ratios to the ground-state rotational band of daughter nuclei. Predictions on the branching ratios to high-spin daughter states are presented for superheavy nuclei, which may be important to interpret future observations.

  12. Realistic shell-model calculations and exotic nuclei around {sup 132}Sn

    SciTech Connect

    Covello, A.; Itaco, N.; Coraggio, L.; Gargano, A.

    2008-11-11

    We report on a study of exotic nuclei around doubly magic {sup 132}Sn in terms of the shell model employing a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential. The short-range repulsion of the latter is renormalized by constructing a smooth low-momentum potential, V{sub low-k}, that is used directly as input for the calculation of the effective interaction. In this paper, we focus attention on proton-neutron multiplets in the odd-odd nuclei {sup 134}Sb, {sup 136}Sb. We show that the behavior of these multiplets is quite similar to that of the analogous multiplets in the counterpart nuclei in the {sup 208}Pb region, {sup 210}Bi and {sup 212}Bi.

  13. ENAM'04 Fourth International Conference on Exotic Nuclei and Atomic Masses

    SciTech Connect

    Gross, C. J.; Nazarewicz, W.; Rykaczewski, K. P.

    2005-01-01

    The conference can trace its origins to the 1950s and 1960s with the Atomic Mass and Fundamental Constants (AMCO) and the Nuclei Far From Stability (NFFS) series of conferences. Held jointly in 1992, the conferences officially merged in 1995 and the fourth conference was held at Callaway Gardens in Pine Mountain, GA and was organized by the Physics Division at Oak Ridge National Laboratory. The conference covered a broad list of topics consisting of a series of invited and contributed presentation highlighting recent research in the following fields: Atomic masses, nuclear moments, and nuclear radii; Forms of radioactivity; Nuclear structure, nuclei at the drip lines, cluster phenomena; Reactions with radioactive ion beams; Nuclear astrophysics; Fundamental symmetries and interactions; Heaviest elements and fission; Radioactive ion beam production and experimental developments; Applications of exotic nuclei

  14. The Subtleties of Pairing and Collective Structures in Deformed Nuclei

    NASA Astrophysics Data System (ADS)

    Sharpey-Schafer, J. F.

    2015-11-01

    It is well known that simple monopole pairing is a pretty crude approximation. It can account for the observations that the ground states of all even-even nuclei have spin-parity 01+ and that there is a pairing gap above the ground state in deformed nuclei before particle-hole configurations can be excited. As an approximation it is best for proton and neutron mid-shell nuclei where the available single particle Nilsson wavefunctions have large overlaps. However at the beginning of regions of deformation, where high-K orbitals can be bought to the Fermi surface from a lower shell, simple monopole pairing is inadequate in describing the physics of the observed data. More recently, with a considerable increase in the quantity and quality of experimental data available, configuration dependent pairing has been used to account for the properties of low-lying first excited 02+ states in N = 88 and 90 nuclei at the onset of deformation in the rare earths. The properties of 02+ states in these and other nuclei at the start of regions of deformation and the effects of blocking of pairing leading to a decrease in the backbending critical frequencies in odd nuclei are presented.

  15. Coulomb excitation of exotic nuclei at the R3B-LAND setup

    NASA Astrophysics Data System (ADS)

    Rossi, D. M.; Adrich, P.; Aksouh, F.; Alvarez-Pol, H.; Aumann, T.; Benlliure, J.; Böhmer, M.; Boretzky, K.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Datta Pramanik, U.; Emling, H.; Ershova, O.; Fernandez-Dominguez, B.; Geissel, H.; Gorska, M.; Heil, M.; Johansson, H.; Junghans, A.; Kiselev, O.; Klimkiewicz, A.; Kratz, J. V.; Kurz, N.; Labiche, M.; Le Bleis, T.; Lemmon, R.; Litvinov, Yu A.; Mahata, K.; Maierbeck, P.; Movsesyan, A.; Nilsson, T.; Nociforo, C.; Palit, R.; Paschalis, S.; Plag, R.; Reifarth, R.; Simon, H.; Sümmerer, K.; Wagner, A.; Walus, W.; Weick, H.; Winkler, M.

    2013-03-01

    Exotic Ni isotopes have been measured at the R3B-LAND setup at GSI in Darmstadt, using Coulomb excitation in inverse kinematics at beam energies around 500 MeV/u. As the experimental setup allows kinematically complete measurements, the excitation energy was reconstructed using the invariant mass method. The GDR and additional low-lying strength have been observed in 68Ni, the latter exhausting 4.1(1.9)% of the E1 energy-weighted sum rule. Also, the branching ratio for the non-statistical decay of the excited 68Ni nuclei was measured and amounts to 24(4)%.

  16. Polarization of the nuclear surface in deformed nuclei

    NASA Astrophysics Data System (ADS)

    Scamps, Guillaume; Lacroix, Denis; Adamian, G. G.; Antonenko, N. V.

    2013-12-01

    The density profiles of around 750 nuclei are analyzed using the Skyrme energy density functional theory. Among them, more than 350 nuclei are found to be deformed. In addition to rather standard properties of the density, we report a nontrivial behavior of the nuclear diffuseness as the system becomes more and more deformed. Besides the geometric effects expected in a rigid body, the diffuseness acquires a rather complex behavior leading to a reduction of the diffuseness along the main axis of deformation simultaneously with an increase of the diffuseness along the other axis. The possible isospin dependence of this polarization is studied. This effect, which is systematically seen in medium and heavy nuclei, can affect the nuclear dynamical properties. A quantitative example is given with the fusion barrier in the 40Ca+238U reaction.

  17. Recent developments in the eikonal description of the breakup of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Capel, P.; Colomer, F.; Esbensen, H.; Fukui, T.; Johnson, R. C.; Nunes, F. M.; Ogata, K.

    2016-06-01

    The study of exotic nuclear structures, such as halo nuclei, is usually performed through nuclear reactions. An accurate reaction model coupled to a realistic description of the projectile is needed to correctly interpret experimental data. In this contribution, I briefly summarise the assumptions made within the modelling of reactions involving halo nuclei. I describe briefly the Continuum-Discretised Coupled Channel method (CDCC) and the Dynamical Eikonal Approximation (DEA) in particular and present a comparison between them for the breakup of 15C on Pb at 68AMeV. I show the problem faced by the eikonal approximation at low energy and detail a correction that enables its extension down to lower beam energies. A new reaction observable is also presented. It consists of the ratio between angular distributions for two different processes, such as elastic scattering and breakup. This ratio is completely independent of the reaction mechanism and hence is more sensitive to the projectile structure than usual reaction observables, which makes it a very powerful tool to study exotic structures far from stability.

  18. β decay of the exotic Tz=-2 nuclei 48Fe,52Ni , and 56Zn

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    The results of a study of the β decays of three proton-rich nuclei with Tz=-2 , namely 48Fe,52Ni , and 56Zn, produced in an experiment carried out at GANIL, are reported. In all three cases we have extracted the half-lives and the total β -delayed proton emission branching ratios. We have measured the individual β -delayed protons and β -delayed γ rays and the branching ratios of the corresponding levels. Decay schemes have been determined for the three nuclei, and new energy levels are identified in the daughter nuclei. Competition between β -delayed protons and γ rays is observed in the de-excitation of the T =2 isobaric analog states in all three cases. Absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. In addition, we discuss in detail the data analysis taking as a test case 56Zn, where the exotic β -delayed γ -proton decay has been observed.

  19. Modeling level structures of odd-odd deformed nuclei

    SciTech Connect

    Hoff, R.W.; Kern, J.; Piepenbring, R.; Boisson, J.P.

    1985-01-15

    A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei has been applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation were derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings were used. Calculated and experimental level structures for /sup 238/Np, /sup 244/Am, and /sup 250/Bk are compared, as well as those for several nuclei in the rare-earch region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Corresponding average deviations for five rare-earth nuclei are 47 keV and 7%. Several applications of this modeling technique are discussed.

  20. Modeling level structures of odd-odd deformed nuclei

    SciTech Connect

    Hoff, R.W.; Kern, J.; Piepenbring, R.; Boisson, J.P.

    1984-09-07

    A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei has been applied to actinide species where new experimental data have been obtained by use of neutron-capture gamma-ray spectroscopy. The input parameters required for the calculation were derived from empirical data on single-particle excitations in neighboring odd-mass nuclei. Calculated configuration-specific values for the Gallagher-Moszkowski splittings were used. Calculated and experimental level structures for /sup 238/Np, /sup 244/Am, and /sup 250/Bk are compared, as well as those for several nuclei in the rare-earth region. The agreement for the actinide species is excellent, with bandhead energies deviating 22 keV and rotational parameters 5%, on the average. Corresponding average deviations for five rare-earth nuclei are 47 keV and 7%. Several applications of this modeling technique are discussed. 18 refs., 5 figs., 4 tabs.

  1. Symmetry energy and surface properties of neutron-rich exotic nuclei

    SciTech Connect

    Gaidarov, M. K.; Antonov, A. N.; Sarriguren, P.; Moya de Guerra, E.

    2014-07-23

    The symmetry energy, the neutron pressure and the asymmetric compressibility of spherical Ni, Sn, and Pb and deformed Kr and Sm neutron-rich even-even nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for isotopic chains of these nuclei in the framework of the deformed self-consistent mean-field Skyrme HF+BCS method. The mass dependence of the nuclear symmetry energy and the neutron skin thickness are also studied together with the role of the neutron-proton asymmetry. The studied correlations reveal a smoother behavior in the case of spherical nuclei than for deformed ones. We also notice that the neutron skin thickness obtained for {sup 208}Pb with SLy4 force is found to be in a good agreement with the recent data. In addition to the interest that this study may have by itself, we give some numerical arguments in proof of the existence of peculiarities of the studied quantities in Ni and Sn isotopic chains that are not present in the Pb chain.

  2. Distortion effects on the neutron knockout from exotic nuclei in the collision with a proton target

    NASA Astrophysics Data System (ADS)

    Cravo, E.; Crespo, R.; Deltuva, A.

    2016-05-01

    Background: Reaction theory plays a major role in the interpretation of experimental data and one needs to identify and include accurately all the relevant dynamical effects in order to extract reliable structure information. The knockout of a nucleon (neutron/proton) from a high energy exotic nucleus projectile colliding with a proton target allows to get insight on the structure of its valence and inner shells. Purpose: We aim to clarify the role of the distortion on the calculated observables for nucleon knockout, in particular, the dependence of the calculated observables on the binding energy ɛb and angular momentum L of the knockout particle, and on the mass of the projectile core, Ac. We consider mainly the knockout of a neutron that may be either in the valence or in the inner shell of the projectile nucleus. Method: Exact three-body Faddeev/Alt-Grassberger-Sandhas (Faddeev/AGS) calculations are performed for the nucleon knockout from stable and exotic nuclei in the collision of 420 MeV/u projectile beams with a proton target. Results are compared with plane-wave impulse approximation (PWIA) calculations. Results: The Faddeev/AGS formalism accurately predicts: (i) a systematic nearly logarithmic dependence of the distortion parameter on the separation energy; (ii) roughly linear dependence of the ratio of the full to the PWIA cross section on the asymmetry parameter; (iii) a distinct behavior between the calculated transverse core momentum distribution from the PWIA and full Faddeev/AGS exact approach which indicates that distortion effects do not modify fully exclusive observables through a common renormalization factor. Conclusions: To extract structure information on deeper shells one needs to include distortion effects accurately. A systematic analysis enables to estimate the total cross section for knockout of a nucleon from a given shell of nuclei at/away the stability line of the nuclear landscape. The comparison with experimental results may

  3. Collisions of deformed nuclei and superheavy-element production

    SciTech Connect

    Iwamoto, Akira; Moeller, P. |||; Nix, J.R.; Sagawa, Hiroyuki, Sagawa

    1995-09-01

    A detailed understanding of complete fusion cross sections in heavy-ion collisions requires a consideration of the effects of the deformation of the projectile and target. The aim here is to show that deformation and orientation of the colliding nuclei have a very significant effect on the fusion-barrier height and on the compactness of the touching configuration. To facilitate discussions of fusion configurations of deformed nuclei, the authors develop a classification scheme and introduce a notation convention for these configurations. They discuss particular deformations and orientations that lead to compact touching configurations and to fusion-barrier heights that correspond to fairly low excitation energies of the compound systems. Such configurations should be the most favorable for producing superheavy elements. They analyze a few projectile-target combinations whose deformations allow favorable entrance-channel configurations and whose proton and neutron numbers lead to compound systems in a part of the superheavy region where a half-lives are calculated to be observable, that is, longer than 1 {micro}s.

  4. The Onset of Deformation in Neutron-Deficient At Nuclei

    SciTech Connect

    Smith, M.B.; Chapman, R.; Cocks, J.F.C.; Dorvaux, O.; Helariutta, K.; Jones, P.M.; Julin, R.; Juutinen, S.; Kankaanpaa, H.; Kettunen, H.; Kuusiniemi, P.; Le Coz, Y.; Leino, M.; Middleton, D.J.; Muikku, M.; Nieminen, P.; Rahkila, P.; Savelius, A.; Spohr, K.-M.

    1999-12-31

    Excited states in the {sup 197}At nucleus have been identified for the first time using the recoil-decay-tagging technique. The excitation energy of these states is found to be consistent with the systematics of neutron-deficient At nuclei and with calculations indicating that the nucleus may be deformed in its ground state. A more recent experiment, to study states in {sup 195}At, is discussed.

  5. The onset of deformation in neutron-deficient At nuclei

    SciTech Connect

    Smith, M. B.; Chapman, R.; Middleton, D. J.; Spohr, K.-M.; Cocks, J. F. C.; Dorvaux, O.; Helariutta, K.; Jones, P. M.; Julin, R.; Juutinen, S.; Kankaanpaeae, H.; Kettunen, H.; Kuusiniemi, P.; Leino, M.; Muikku, M.; Nieminen, P.; Rahkila, P.; Savelius, A.; Coz, Y. Le

    1999-11-16

    Excited states in the {sup 197}At nucleus have been identified for the first time using the recoil-decay-tagging technique. The excitation energy of these states is found to be consistent with the systematics of neutron-deficient. At nuclei and with calculations indicating that the nucleus may be deformed in its ground state. A more recent experiment, to study states in {sup 195}At, is discussed.

  6. Microscopic and self-consistent description for neutron halo in deformed nuclei

    SciTech Connect

    Li Lulu; Meng Jie; Zhao Enguang; Zhou Shangui

    2013-05-06

    A deformed relativistic Hartree-Bogoliubov theory in continuum has been developed for the study of neutron halos in deformed nuclei and the halo phenomenon in deformed weakly bound nuclei is investigated. Magnesium and neon isotopes are studied and some results are presented for the deformed neutron-rich and weakly bound nuclei {sup 44}Mg and {sup 36}Ne. The core of the former nucleus is prolate, but the halo has a slightly oblate shape. This indicates a decoupling of the halo orbitals from the deformation of the core. The generic conditions for the existence of halos in deformed nuclei and for the occurrence of this decoupling effect are discussed.

  7. Recent Precision Experiments with Exotic Nuclei Produced with Uranium Projectiles and Experimental Prospects at Fair

    NASA Astrophysics Data System (ADS)

    Geissel, H.; Chen, L.; Dickel, T.; Farinon, F.; Dillmann, I.; Knöbel, R.; Kurcewicz, J.; Mukha, I.; Münzenberg, G.; Nociforo, C.; Patyk, Z.; Pietri, S.; Plass, W. R.; Prochazka, A.; Scheidenberger, C.; Takechi, M.; Weick, H.; Winfield, J. S.; Winkler, M.

    2014-03-01

    Precision experiments with relativistic fragments separated in-flight require special experimentalmethods to overcome the inherent large emittance from the creation in nuclear reactions and atomic interactions in matter. At GSI relativistic exotic nuclei have been produced via uranium projectile fragmentation and fission and investigated with the inflight separator FRS directly, or in combination with either the storage-cooler ring ESR or the FRS Ion Catcher. 1000 A·MeV 238U ions were used to create 60 new neutron-rich isotopes separated and identified with the FRS to measure their production cross sections. In another experimental campaign the fragments were separated in flight and injected into the storage-cooler ring ESR for accurate mass and lifetime measurements. In these experimentswe have obtained accurate new mass values analyzed via a novel method which has reduced the systematic errors for both Schottky Mass Spectrometry (SMS) and for Isochronous Mass Spectrometry (IMS). Pioneering experiments have been carried out with the FRS Ion Catcher consisting of three experimental components, the dispersive magnetic system of the FRS with a monoenergetic and a homogeneous degrader, a cryogenic stopping cell filled with pure helium and a multiple-reflection time-of flight mass separator. The FRS Ion Catcher enables high precision spectroscopy experiments with eV to keV exotic nuclides. Results from these different FRS experiments are presented in this overview together with prospects for the next-generation facility Super-FRS. The novel features of the Super-FRS compared with the present FRS will be discussed in addition.

  8. Beta decay of exotic TZ = -1, -2 nuclei: the interesting case of 56Zn

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    The β decay properties of the Tz = -2, 56Zn isotope and other proton-rich nuclei in the fp-shell have been investigated in an experiment performed at GANIL. The ions were produced in fragmentation reactions and implanted in a double-sided silicon strip detector surrounded by Ge EXOGAM clovers. Preliminary results for 56Zn are presented .The 56Zn decay proceeds mainly by β delayed proton emission, but β delayed gamma rays were also detected. Moreover, the exotic β delayed gamma-proton decay was observed for the first time. The 56Zn half-life and the energy levels populated in the 56Cu daughter have been determined. Knowledge of the gamma de-excitation of the mirror states in 56Co and the comparison with the results of the mirror charge exchange process, the 56Fe(3He,t) reaction (where 56Fe has Tz = +2), were important in the interpretation of the 56Zn decay data. The absolute Fermi and Gamow-Teller strengths have been deduced.

  9. Deformed Brueckner-Hartree-Fock calculation for light nuclei

    NASA Technical Reports Server (NTRS)

    Braley, R. C.; Ford, W. F.; Becker, R. L.; Patterson, M. R.

    1971-01-01

    For the first time the Brueckner-Hartree-Fock (BHF) method was applied to nuclei whose intrinsic structure is nonspherical. One aim was to investigate whether the energy dependent reaction matrix calculated from a realistic nucleon-nucleon interaction leads to deformations similar to, or different from, those obtained from energy independent interactions in Hartree-Fock (HF) calculations. Reaction matrix elements were calculated as a function of starting energy for the Hamada-Johnston interaction, using a Pauli operator appropriate to O-16 and a shifted oscillator spectrum for virtual excited states. Binding energies, single-particle energies, radii, and shape deformations of the intrinsic state in unrenormalized as well as renormalized BHF are discussed and compared with previous HF studies. Results are presented for C-12, O-16, and Ne-20.

  10. The analysis of predictability of recent alpha decay formulae and the alpha partial half-lives of some exotic nuclei

    SciTech Connect

    Dasgupta-Schubert, N.; Reyes, M. A.; Tamez, V. A.

    2009-04-20

    Alpha decay is one of the two main decay modes of the heaviest nuclei, (SHE), and constitutes one of the dominant decay modes of highly neutron deficient medium mass nuclei ('exotics'). Thus identifying and characterizing the alpha decay chains form a crucial part of the identification of SHE. We report the extension of the previously developed method for the detailed and systematic investigation of the reliability of the three main extant analytical formulae of alpha decay half-lives: the generalized liquid drop model based formula of Royer et al. (FR), the Sobiczewski modified semi-empirical Viola-Seaborg formula (VSS) and the recent phenomenological formula of Sobiczewski and Parkhomenko (SP)

  11. Structure models: From shell model to ab initio methods. A brief introduction to microscopic theories for exotic nuclei

    NASA Astrophysics Data System (ADS)

    Bacca, Sonia

    2016-04-01

    A brief review of models to describe nuclear structure and reactions properties is presented, starting from the historical shell model picture and encompassing modern ab initio approaches. A selection of recent theoretical results on observables for exotic light and medium-mass nuclei is shown. Emphasis is given to the comparison with experiment and to what can be learned about three-body forces and continuum properties.

  12. Tunneling from super- to normal-deformed minima in nuclei.

    SciTech Connect

    Khoo, T. L.

    1998-01-08

    An excited minimum, or false vacuum, gives rise to a highly elongated superdeformed (SD) nucleus. A brief review of superdeformation is given, with emphasis on the tunneling from the false to the true vacuum, which occurs in the feeding and decay of SD bands. During the feeding process the tunneling is between hot states, while in the decay it is from a cold to a hot state. The {gamma} spectra connecting SD and normal-deformed (ND) states provide information on several physics issues: the decay mechanism; the spin/parity quantum numbers, energies and microscopic structures of SD bands; the origin of identical SD bands; the quenching of pairing with excitation energy; and the chaoticity of excited ND states at 2.5-5 MeV. Other examples of tunneling in nuclei, which are briefly described, include the possible role of tunneling in {Delta}I = 4 bifurcation in SD bands, sub-barrier fusion and proton emitters.

  13. Role of higher-multipole deformations in exotic {sup 14}C cluster radioactivity

    SciTech Connect

    Sawhney, Gudveen; Sharma, Manoj K.; Gupta, Raj K.

    2011-06-15

    We have studied nine cases of spontaneous emission of {sup 14}C clusters in the ground-state decays of the same number of parent nuclei from the trans-lead region, specifically from {sup 221}Fr to {sup 226}Th, using the preformed cluster model (PCM) of Gupta and collaborators, with choices of spherical, quadrupole deformation ({beta}{sub 2}) alone, and higher-multipole deformations ({beta}{sub 2}, {beta}{sub 3}, {beta}{sub 4}) with cold ''compact'' orientations {theta}{sup c} of decay products. The calculated {sup 14}C cluster decay half-life times are found to be in nice agreement with experimental data only for the case of higher-multipole deformations ({beta}{sub 2}-{beta}{sub 4}) and {theta}{sup c} orientations of cold elongated configurations. In other words, compared to our earlier study of clusters heavier than {sup 14}C, where the inclusion of {beta}{sub 2} alone, with ''optimum'' orientations, was found to be enough to give the best comparison with data, here for {sup 14}C cluster decay the inclusion of higher-multipole deformations (up to hexadecapole), together with {theta}{sup c} orientations, is found to be essential on the basis of the PCM. Interestingly, whereas both the penetration probability and assault frequency work simply as scaling factors, the preformation probability is strongly influenced by the order of multipole deformations and orientations of nuclei. The possible role of Q value and angular-momentum effects are also considered in reference to {sup 14}C cluster radioactivity.

  14. The nuclear structure of deformed odd-odd nuclei: Experimental and theoretical investigations

    SciTech Connect

    Hoff, R.W.; Jain, A.K.; Sood, P.C.; Sheline, R.K.

    1988-06-06

    Previous surveys of experimental level structure in deformed odd-odd nuclei have been updated with recent results for the lanthanide and actinide regions. The relative strengths of the effective neutron-proton interaction derived from these data are compared. The predictive power of a semi-empirical model for level structure in deformed odd-odd nuclei is demonstrated. Comparison is made with recent Hartree-Fock calculations of selected nuclei.

  15. Exotic decay modes of odd-Z (105-119) superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Rajeswari, N. S.; Balasubramaniam, M.

    2014-06-01

    Half-lives of proton emission for proton emitters with Z = 51 to 83 are calculated, in the frame-work of unified fission model with the penetrability calculated using the WKB approximation. For all the ground and isomeric state of the proton, the deformation degree of freedom is included. Calculated half-lives are in good agreement with the experimental ones. Experimentally for a few isotopes, proton and alpha branches are reported. Hence we have calculated the half-lives of alpha decay for these elements. For parent nuclei 157Ta, 166Ir, 167Ir, 176Tl and 177Tl, the alpha decay mode is preferred over the proton emission. Further, the calculations are extended to find half-lives of superheavy element with odd proton number in the range Z = 105 to 119, for both proton, alpha and for a few cluster decays. Calculations on superheavy elements reveal that cluster radioactivity has half-lives comparable with proton emissions. It is found that proton emission is the primary competing decay mode with respect to alpha decay for superheavy elements. Among considered clusters, 12C, 20Ne and 24Mg are found to have lowest half-lives among other N = Z clusters and for a few clusters the half-lives are found to be comparable with that of proton emission.

  16. A new Time-of-Flight mass measurement project for exotic nuclei and ultra-high precision detector development

    NASA Astrophysics Data System (ADS)

    Sun, Bao-Hua; Zhao, Jian-Wei; Yan, Wen-Qi; Le, X. Y.; Lin, Wen-Jian; Song, C. Y.; Tanihata, Isao; Terashima, S.; Wang, T. F.; Zhang, S. S.; Zhu, L. H.

    2016-02-01

    The time-of-flight (TOF) mass spectrometry (MS), a high-resolution magnetic spectrometer equipped with a fast particle tracking system, is well recognized by its ability in weighing the most exotic nuclei. Currently such TOF-MS can achieve a mass resolution power of about 2×10-4. We show that the mass resolution can be further improved by one order of magnitude with augmented timing and position detectors. We report the progress in developing ultra-fast detectors to be used in TOF-MS.

  17. Search for α-Cluster Structure in Exotic Nuclei with the Prototype Active-Target Time-Projection Chamber

    NASA Astrophysics Data System (ADS)

    Fritsch, A.; Ayyad, Y.; Bazin, D.; Beceiro-Novo, S.; Bradt, J.; Carpenter, L.; Cortesi, M.; Mittig, W.; Suzuki, D.; Ahn, T.; Kolata, J. J.; Becchetti, F. D.; Howard, A. M.

    2016-03-01

    Some exotic nuclei appear to exhibit α-cluster structure. While various theoretical models currently describe such clustering, more experimental data are needed to constrain model predictions. The Prototype Active-Target Time-Projection Chamber (PAT-TPC) has low-energy thresholds for charged-particle decay and a high luminosity due to its thick gaseous active target volume, making it well-suited to search for low-energy α-cluster reactions. Radioactive-ion beams produced by the TwinSol facility at the University of Notre Dame were delivered to the PAT-TPC to study nuclei including 14C and 14O via α-resonant scattering. Differential cross sections and excitation functions were measured. Preliminary results from our recent experiments will be presented. This work is supported by the U.S. National Science Foundation.

  18. Two-neutron transfer reactions with heavy-deformed nuclei

    SciTech Connect

    Price, C.; Landowne, S.; Esbensen, H.

    1988-01-01

    In a recent communication we pointed out that one can combine the macroscopic model for two-particle transfer reactions on deformed nuclei with the sudden limit approximation for rotational excitation, and thereby obtain a practical method for calculating transfer reactions leading to high-spin states. As an example, we presented results for the reaction WSDy(VYNi,WNi) WDy populating the ground-state rotational band up to the spin I = 14 state. We have also tested the validity of the sudden limit for the inelastic excitation of high spin states and we have noted how the macroscopic model may be modified to allow for more microscopic nuclear structure effects in an application to diabolic pair-transfer processes. This paper describes our subsequent work in which we investigated the systematic features of pair-transfer reactions within the macroscopic model by using heavier projectiles to generate higher spins and by decomposing the cross sections according to the multipolarity of the transfer interaction. Particular attention is paid to characteristic structures in the angular distributions for the lower spin states and how they depend on the angular momentum carried by the transferred particles. 11 refs., 3 figs.

  19. Possible octupole deformation in Cs and Ba nuclei from their differential radii

    SciTech Connect

    Sheline, R.K.; Jain, A.K.; Jain, K.

    1988-12-01

    The odd-even staggering of the differential radii of Fr and Ra and the Cs and Ba nuclei is compared. This staggering is inverted in the region of known octupole deformation in the Fr and Ra nuclei. The normal staggering is eliminated in the Cs nuclei and attenuated in the Ba nuclei for neutron numbers 85--88. This fact is used to suggest the possible existence of octupole deformation and its neutron number range in the Cs and Ba nuclear ground states.

  20. {Delta}I = 2 energy staggering in normal deformed dysprosium nuclei

    SciTech Connect

    Riley, M.A.; Brown, T.B.; Archer, D.E.

    1996-12-31

    Very high spin states (I{ge}50{Dirac_h}) have been observed in {sup 155,156,157}Dy. The long regular band sequences, free from sharp backbending effects, observed in these dysprosium nuclei offer the possibility of investigating the occurence of any {Delta}I = 2 staggering in normal deformed nuclei. Employing the same analysis techniques as used in superdeformed nuclei, certain bands do indeed demonstrate an apparent staggering and this is discussed.

  1. Gamow-Teller Transitions in Proton Rich Exotic pf-shell Nuclei Deduced from Mirror Transitions

    SciTech Connect

    Fujita, Y.; Adachi, T.; Fujita, H.; Blank, B.; Brentano, P. von; Zell, K. O.; Berg, G. P. A.; Fujita, K.; Hatanaka, K.; Nakanishi, K.; Shimizu, Y.; Tameshige, Y.; Tamii, A.; Yosoi, M.; Negret, A.; Popescu, L.; Rubio, B.; Shimbara, Y.

    2010-08-12

    The rp-process nucleosynthesis proceeds through nuclei near the proton drip-line, in which Gamow-Teller (GT) transitions starting from unstable pf-shell nuclei play important roles. In the {beta}-decay study of these nuclei, half-lives can be measured rather accurately. On the other hand, in the high-resolution ({sup 3}He, t) charge-exchange reactions on mirror nuclei, individual GT transitions can be studied up to high excitations. For the accurate study of the GT transition strengths in the A = 52, T = 2, system, we compare and combine the {beta}-decay study of the proton-rich nucleus {sup 52}Ni and the {sup 52}Cr({sup 3}He, t) measurement assuming the isospin symmetry of the T{sub z} = {+-}2{yields}{+-}1 transitions.

  2. Thermonuclear flashes on hydrogen/helium accreting carbon monoxide white dwarfs and structure of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Mitchell, Joseph P.

    . Occurrence of rp-nucleosynthesis in these objects may make important sources of the chemical enrichment of isotopes below the iron group that are not know to be synthesized in hydrostatic stellar burning. The existence of rp-breakout in the flashes, shows the importance of nuclear physics in these objects. More precise nuclear reaction rate data are needed for proper energy generation and chemical evolution. With the occurrence of rp-nucleosynthesis in our models, it is especially advantageous to study radioactive proton rich nuclei. These studies are not without many difficulties in the laboratory, as many of the studies require the use of low intensity radioactive beams making clean, high statistic studies difficult. To address this issue, the hybrid target technique was used. This target technique was found to be a great tool for studying resonant proton scattering with exotic beams. It has been used to measure elastic and inelastic excitation functions in the study of 8B via 7Be+p scattering, as well as 12N+p elastic scattering. With such success, the hybrid target technique can be a very useful tool for studying reactions that are important in the rp-process. We have studied the structure of the astrophysically important, radioactive isotope 8B. Three new resonances have been suggested, a 0+1,2+2 , and 1+2 which were predominantly in the inelastic channel and never before seen in previous studies. However, due to their high excitation energies and narrow width, none of the resonances are expected to effect the astrophysically important 7Be(p, gamma) reaction rate. Results were compared to continuum shell model as well as ab initio calculations and found to be in good agreement with both sets of predictions, with the notable exception of the 2+2 state. (Abstract shortened by UMI.)

  3. Studies of light exotic nuclei in the vicinity of neutron and proton drip lines at FLNR JINR

    NASA Astrophysics Data System (ADS)

    Grigorenko, L. V.; Golovkov, M. S.; Krupko, S. A.; Sidorchuk, S. I.; Ter-Akopian, G. M.; Fomichev, A. S.; Chudoba, V.

    2016-04-01

    Defining the limits of the existence of the nuclear structure is one of fundamental problems of natural science, requiring the advancement of studies towards the sites of maximum neutron- and proton-excess nuclei, to the borders of nuclear stability, and further, to the regions of nuclear instability. In such regions, nuclear systems exist only as resonant states in continuous spectra with characteristic 'nuclear' lifetimes. This work is done most effectively with experimental setups providing radioactive ion beams (RIBs). This review discusses the approaches in this field of research developed during the last 20 years at the ACCULINNA fragment separator in the Flerov Laboratory of Nuclear Reactions (FLNR) of the Joint Institute for Nuclear Research (JINR). The methodology developed is based on the comprehensive study of correlations among the reaction fragments emitted in the decays of nuclear-unstable systems which are populated in direct reactions induced by RIBs with intermediate (20 – 60 MeV per nucleon) energies. This allows us to acquire detailed knowledge about exotic nuclear systems close to and beyond nuclear drip lines. We discuss exotic forms of nuclear dynamics appearing in the vicinity of nuclear drip lines and relevant results of their theoretical analysis. Also discussed are existing facilities and prospective projects aimed at nuclear structure studies with RIBs at JINR.

  4. Coupled-channels study of fine structure in the {alpha} decay of well deformed nuclei

    SciTech Connect

    Ni Dongdong; Ren Zhongzhou

    2011-06-15

    We formulate a theoretical model for the {alpha} decay of well-deformed even-even nuclei based on the coupled-channel Schroedinger equation. The {alpha}-decay half-lives and fine structures observed in {alpha} decay are well described by the five-channel microscopic calculations. Since the branching ratios to high-spin states are hard to understand in the traditional {alpha}-decay theories, this success could be important to interpret future observations of heavier nuclei. It is also found that the {alpha} transition to high-spin states is a powerful tool to probe the energy spectrum and deformation of daughter nuclei.

  5. Extended systematics of alpha decay half lives for exotic superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Budaca, A. I.; Budaca, R.; Silisteanu, I.

    2016-07-01

    The experimentally available data on the α decay half lives and Qα values for 96 superheavy nuclei are used to fix the parameters for a modified version of the Brown empirical formula through two fitting procedures which enables its comparison with similar fits using Viola-Seaborg and Royer formulas. The new expressions provide very good agreement with experimental data having fewer or the same number of parameters. All formulas with the obtained parameters are then extrapolated to generate half lives predictions for 125 unknown superheavy α emitters. The nuclei where the employed empirical formulas maximally or minimally diverge are pointed out and a selection of 36 nuclei with exceptional superposition of predictions was made for experimental reference.

  6. Microscopic Description of the Exotic Nuclei Reactions by Using Folding model Potentials

    SciTech Connect

    Ibraheem, Awad A.; Hassanain, M. A.; Mokhtar, S. R.; El-Azab Farid, M.; Zaki, M. A.; Mahmoud, Zakaria M. M.

    2011-10-27

    A microscopic folding approach based upon the effective M3Y nucleon-nucleon interaction and the nuclear matter densities of the interacting nuclei has been carried out to explain recently measured experimental data of the {sup 6}He+{sup 120}Sn elastic scattering reaction at four different laboratory energies near the Coulomb barrier. The corresponding reaction cross sections are also considered.

  7. Proximity potential for heavy ion reactions on deformed nuclei

    SciTech Connect

    Baltz, A. J.; Bayman, B. F.

    1982-01-01

    The usual treatment of the deformed optical model for analysis of heavy ion induced inelastic scattering data involves a deformed (target) radius, a spherical (projectile) radius and a potential strength dependent on the surface separation along the line between the two centers. Several authors using various approaches have shown that this center line potential is geometrically inadequate especially for description of higher L deformation parameters probed in heavy ion induced inelastic scattering experiments. A quantitatively adequate form of the deformed proximity potential suitable for use with a coupled channels reaction code in the analysis of inelastic scattering data above the Coulomb barrier is described. A major objective is to be able to extract reliably higher deformed multipole moments from such data. The deformed potential calculated in the folding model will serve as a geometrically exact benchmark to evaluate the accuracy of the proximity potential prescriptions. (WHK)

  8. {alpha}-cluster structure and exotic states in a self-consistent model for light nuclei

    SciTech Connect

    Maruhn, J. A.; Kimura, Masaaki; Schramm, S.; Reinhard, P.-G.; Horiuchi, H.; Tohsaki, A.

    2006-10-15

    In this article we examine to what extent traces of {alpha} clustering can be found in mean-field ground states of n{alpha} nuclei from {sup 8}Be through {sup 36}Ar as well as in some superdeformed states in {sup 32}S, {sup 36}Ar, and {sup 40}Ca. For this purpose we calculate the overlap of the mean-field Slater determinant with one containing pure Gaussians and perfect spin and isospin symmetry, optimizing the overlap by varying the {alpha}-particle positions and radii. In some cases a coherent sum over different configurations is also employed. We find quite large overlaps for some of the lighter systems that diminish for nuclei above {sup 20}Ne but again strong clustering in {sup 36}Ar.

  9. Constrained Hartree-Fock Theory and Study of Deformed Structures of Closed Shell Nuclei

    NASA Astrophysics Data System (ADS)

    Praharaj, Choudhury

    2016-03-01

    We have studied some N or Z = 50 nuclei in a microscopic model with effective interaction in a reasonably large shell model space. Excitation of particles across 50 shell closure leads to well-deformed excited prolate configurations. The potential energy surfaces of nuclei are studied using Hartree-Fock theory with quadrupole constraint to explore the various deformed configurations of N = 50 nuclei 82Ge , 84Se and 86Kr . Energy spectra are calculated from various intrinsic states using Peierls-Yoccoz angular momentum projection technique. Results of spectra and electromagnetic moments and transitions will be presented for N = 50 nuclei and for Z = 50 114Sn nucleus. Supported by Grant No SB/S2/HEP-06/2013 of DST.

  10. Nucleon states of strongly deformed nuclei and dinuclear systems in the nonoscillator two-center model

    SciTech Connect

    Samarin, V. V.

    2010-08-15

    A new method for numerically solving the Schroedinger equation for an arbitrary axisymmetric field with allowance for spin-orbit interaction is used to study neutron and proton states in strongly deformed nuclei and dinuclear systems produced at the first step of the fusion of nuclei. A quadrupole-octupole parametrization is proposed for the shape of a dinuclear system and for the potential energy of nucleons in this system. The experimentally observed deformations of the {sup 26,27,28}Mg nuclei and the difference in the cross sections for the fusion of nuclei in the {sup 18}O + {sup 58}Ni and {sup 16}O + {sup 60}Ni systems are explained qualitatively.

  11. Effects of high-order deformation on high-K isomers in superheavy nuclei

    SciTech Connect

    Liu, H. L.; Bertulani, C. A.; Xu, F. R.; Walker, P. M.

    2011-01-15

    Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of {beta}{sub 6} deformation, we find remarkable effects of the high-order deformation on the high-K isomers in {sup 254}No, the focus of recent spectroscopy experiments on superheavy nuclei. For shapes with multipolarity six, the isomers are more tightly bound and, microscopically, have enhanced deformed shell gaps at N=152 and Z=100. The inclusion of {beta}{sub 6} deformation significantly improves the description of the very heavy high-K isomers.

  12. Equilibrium deformations and excitation energies of single-quasiproton band heads of rare-earth nuclei

    NASA Astrophysics Data System (ADS)

    Nazarewicz, W.; Riley, M. A.; Garrett, J. D.

    1990-05-01

    Noncollective single-proton states in odd- Z (Eu, Tb, Ho, Tm, Lu, Ta, Ir and Au) rare-earth nuclei have been calculated using the shell correction method with an average Woods-Saxon potential and a monopole pairing residual interaction. Calculated equilibrium deformations of the lowest single-proton states are presented, and calculated band head excitation energies are compared with experimental proton band heads for odd- Z rare-earth nuclei. Good agreement is found between the experimental and calculated band heads. We find that strong polarisation effects due to the odd proton explain many of the systematic trends of known band heads. Different deformation driving forces of the odd-proton orbitals can also partly explain deviations seen in high-spin data. Shape co-existence effects in Ir and Au isotopes are discussed. In addition, equilibrium deformations of even-even rare-earth nuclei are computed and compared with experimental values.

  13. The Discoveries of Bohrium, Hassium, Meitnerium, and the New Region of Deformed Shell Nuclei

    NASA Astrophysics Data System (ADS)

    Muenzenberg, Gottfried

    2003-03-01

    The investigation of the light trans-actinide elements was not only exciting as it included the discovery of a number of new chemical elements. It led also to the discovery of a new region of shell nuclei existing beyond the macroscopic stability limit. Theory explained this in terms of a new shell region of deformed nuclei which bridge the trans-uranium nuclei and the predicted superheavy elements. This contribution will give a brief historic overview over these discoveries, experimental developments, and the impact on ongoing and future superheavy-element research.

  14. Energy dependence of exotic nuclei production cross sections by photofission reaction in GDR range

    NASA Astrophysics Data System (ADS)

    Bhowmick, Debasis; Khan, F. A.; Atta, Debasis; Basu, D. N.; Chakrabarti, Alok

    2016-02-01

    Photofission of actinides is studied in the region of nuclear excitation energies that covers the entire giant dipole resonance (GDR) region. The mass distributions of $^{238}$U photofission fragments have been explored theoretically for eight different endpoint bremsstrahlung energies from 11.5 MeV to 67.7 MeV which correspond to average photon energy of 9.09 MeV to 15.90 MeV. Among these energies, the 29.1 MeV corresponds to the average photon energy of 13.7$\\pm$0.3 MeV which coincides with GDR peak for $^{238}$U photofission. The integrated yield of $^{238}$U photofission as well as charge distribution of photofission products are calculated and its role in producing nuclei and their neutron-richness is investigated.

  15. Cluster radioactivity with effects of deformations and orientations of nuclei included

    SciTech Connect

    Arun, Sham K.; Gupta, Raj K.; Kanwar, Shefali; Singh, BirBikram; Sharma, Manoj K.

    2009-09-15

    Based on the preformed cluster model (PCM) of Gupta and collaborators, we have extended our recent study on ground-state cluster decays to parent nuclei resulting in daughters other than spherical {sup 208}Pb, i.e., to deformed daughters, and the very new cases of {sup 14}C and {sup 15}N decays of {sup 223}Ac, and {sup 34}Si decay of {sup 238}U, taking nuclei as spherical, quadrupole deformed ({beta}{sub 2}) alone, and with higher multipole deformations up to hexadecapole ({beta}{sub 2}, {beta}{sub 3}, {beta}{sub 4}) together with the 'optimum' orientations of cold decay process. Except for {sup 14}C decays of {sup 221}Fr, {sup 221-224,226}Ra, and {sup 225}Ac where higher multipole deformations up to {beta}{sub 4} are found essential, the quadrupole deformation {beta}{sub 2} alone is found good enough to fit the experimental data. Because the PCM treats the cluster-decay process as the tunneling of a preformed cluster, the deformations and orientations of nuclei modify both the preformation probability P{sub 0} and tunneling probability P, and hence the decay half-life, considerably.

  16. High-performance multiple-reflection time-of-flight mass spectrometers for research with exotic nuclei and for analytical mass spectrometry

    NASA Astrophysics Data System (ADS)

    Plaß, Wolfgang R.; Dickel, Timo; Ayet San Andres, Samuel; Ebert, Jens; Greiner, Florian; Hornung, Christine; Jesch, Christian; Lang, Johannes; Lippert, Wayne; Majoros, Tamas; Short, Devin; Geissel, Hans; Haettner, Emma; Reiter, Moritz P.; Rink, Ann-Kathrin; Scheidenberger, Christoph; Yavor, Mikhail I.

    2015-11-01

    A class of multiple-reflection time-of-flight mass spectrometers (MR-TOF-MSs) has been developed for research with exotic nuclei at present and future accelerator facilities such as GSI and FAIR (Darmstadt), and TRIUMF (Vancouver). They can perform highly accurate mass measurements of exotic nuclei, serve as high-resolution, high-capacity mass separators and be employed as diagnostics devices to monitor the production, separation and manipulation of beams of exotic nuclei. In addition, a mobile high-resolution MR-TOF-MS has been developed for in situ applications in analytical mass spectrometry ranging from environmental research to medicine. Recently, the MR-TOF-MS for GSI and FAIR has been further developed. A novel RF quadrupole-based ion beam switchyard has been developed that allows merging and splitting of ion beams as well as transport of ions into different directions. It efficiently connects a test and reference ion source and an auxiliary detector to the system. Due to an increase in the kinetic energy of the ions in the time-of-flight analyzer of the MR-TOF-MS, a given mass resolving power is now achieved in less than half the time-of-flight. Conversely, depending on the time-of-flight, the mass resolving power has been increased by a factor of more than two.

  17. Pygmy Dipole Strength in Exotic Nuclei and the Equation of State

    NASA Astrophysics Data System (ADS)

    Klimkiewicz, A.; Paar, N.; Adrich, P.; Fallot, M.; le Bleis, T.; Rossi, D.; Boretzky, K.; Aumann, T.; Alvarez-Pol, H.; Aksouh, F.; Benlliure, J.; Berg, T.; Boehmer, M.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Pramanik, U. Datta; Elze, Th. W.; Emling, H.; Ershova, O.; Fernando-Dominguez, B.; Geissel, H.; Gorska, M.; Heil, M.; Hellström, M.; Johansson, H.; Jones, K. L.; Junghans, A.; Kiselev, O.; Kratz, J. V.; Kulessa, R.; Kurz, N.; Labiche, M.; Lemmon, R.; Litvinov, Y.; Mahata, K.; Maierbeck, P.; Nilsson, T.; Nociforo, C.; Palit, R.; Paschalis, S.; Plag, R.; Reifarth, R.; Simon, H.; Sümmerer, K.; Surówka, G.; Vretenar, D.; Wagner, A.; Waluś, W.; Weick, H.; Winkler, M.

    2009-08-01

    A concentration of dipole strength at energies below the giant dipole resonance was observed in neutron-rich nuclei around 132Sn in an experiment using the FRS-LAND setup. This so-called "pygmy" dipole strength can be related to the parameters of the symmetry energy and to the neutron skin thickness on the grounds of a relativistic quasiparticle random-phase approximation. Using this ansatz and the experimental findings for 130Sn and 132Sn, we derive a value of the symmetry energy pressure of p¯0 = 2.2±0.5 MeV/fm3. Neutron skin thicknesses of Rn-Rp = 0.23±0.03 fm and 0.24±0.03 fm for 130Sn and 132Sn, respectively, have been determined. Preliminary results on 68Ni from a similar experiment using an improved setup indicate an enhanced cross section at low energies, while the results for 58Ni are in accordance with results from photoabsorption measurements.

  18. High-Resolution Magnetic Analyzer MAVR for the Study of Exotic Weakly-Bound Nuclei

    NASA Astrophysics Data System (ADS)

    Maslov, V. A.; Kazacha, V. I.; Kolesov, I. V.; Lukyanov, S. M.; Melnikov, V. N.; Osipov, N. F.; Penionzhkevich, Yu. E.; Skobelev, N. K.; Sobolev, Yu. G.; Voskoboinik, E. I.

    2015-11-01

    A project of the high-resolution magnetic analyzer MAVR is proposed. The analyzer will comprise new magnetic optical and detecting systems for separation and identification of reaction products in a wide range of masses (5-150) and charges (1-60). The magnetic optical system consists of the MSP-144 magnet and a doublet of quadrupole lenses. This will allow the solid angle of the spectrometer to be increased by an order of magnitude up to 30 msr. The magnetic analyzer will have a high momentum resolution (10-4) and high focal-plane dispersion (1.9 m). It will allow products of nuclear reactions at energies up to 30 MeV/nucleon to be detected with the charge resolution ~1/60. Implementation of the project is divided into two stages: conversion of the magnetic analyzer proper and construction of the nuclear reaction products identification system. The MULTI detecting system is being developed for the MAVR magnetic analyzer to allow detection of nuclear reaction products and their identification by charge Q, atomic number Z, and mass A with a high absolute accuracy. The identification will be performed by measuring the energy loss (ΔE), time of flight (TOF), and total kinetic energy (TKE) of reaction products. The particle trajectories in the analyzer will also be determined using the drift chamber developed jointly with GANIL. The MAVR analyzer will operate in both primary beams of heavy ions and beams of radioactive nuclei produced by the U400-U400M acceleration complex. It will also be used for measuring energy spectra of nuclear reaction products and as an energy monochromator.

  19. Projected shell model for Gamow-Teller transitions in heavy, deformed nuclei

    NASA Astrophysics Data System (ADS)

    Wang, Long-Jun; Sun, Yang; Gao, Zao-Chun; Kiran Ghorui, Surja

    2016-02-01

    Calculations of Gamow-Teller (GT) transition rates for heavy, deformed nuclei, which are useful input for nuclear astrophysics studies, are usually done with the quasiparticle random-phase approximation. We propose a shell-model method by applying the Projected Shell Model (PSM) based on deformed bases. With this method, it is possible to perform a state-by-state calculation for nuclear matrix elements for β-decay and electron-capture in heavy nuclei. Taking β- decay from 168Dy to 168Ho as an example, we show that the known experimental B(GT) from the ground state of the mother nucleus to the low-lying states of the daughter nucleus could be well described. Moreover, strong transitions to high-lying states are predicted to occur, which may considerably enhance the total decay rates once these nuclei are exposed to hot stellar environments.

  20. Excited states of deformable odd {sup 157,159}Tb nuclei: Nonconservation of the angular momentum of external nucleon

    SciTech Connect

    Sharipov, Sh.; Ermamatov, M. J.

    2009-01-15

    The previously developed rotationally single-particle and vibrational model of the triaxial deformable odd nuclei is extended to the case where the total angular momentum of an external nucleon is not conserved. The calculated ratios of the excitation energies of the {sup 157,159}Tb nuclei are compared with the existing experimental data. The ratios of E2-transition probabilities and those of quadrupole moments of the above nuclei are calculated using parameters determined from the spectra of these nuclei.

  1. Orientation effects of deformed nuclei on the production of superheavy elements

    SciTech Connect

    Wang Nan; Li Junqing; Zhao Enguang

    2008-11-15

    Within the dinuclear system model, the effects of the relative orientations of interacting deformed nuclei on the interaction potential energy surfaces, the evaporation residue cross sections of some cold fusion reactions leading to superheavy elements are investigated. The competition between fusion and quasifission is studied to show the effect of the orientation. It turns out that the belly-belly orientation is in favor of the production of superheavy nuclei, because in the case a barrier has suppressed the quasifission and thus helped fusion.

  2. Relativistic Energy Density Functionals: Exotic modes of excitation

    SciTech Connect

    Vretenar, D.; Paar, N.; Marketin, T.

    2008-11-11

    The framework of relativistic energy density functionals has been applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of {beta}-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure have been investigated with the relativistic quasiparticle random-phase approximation. We present results for the evolution of low-lying dipole (pygmy) strength in neutron-rich nuclei, and charged-current neutrino-nucleus cross sections.

  3. Linear response of light deformed nuclei investigated by self-consistent quasiparticle random-phase approximation

    SciTech Connect

    Losa, C.; Doessing, T.; Pastore, A.; Vigezzi, E.; Broglia, R. A.

    2010-06-15

    We present a calculation of the properties of vibrational states in deformed, axially-symmetric even-even nuclei, within the framework of a fully self-consistent quasiparticle random phase approximation (QRPA). The same Skyrme energy density and density-dependent pairing functionals are used to calculate the mean field and the residual interaction in the particle-hole and particle-particle channels. We have tested our software in the case of spherical nuclei against fully self-consistent calculations published in the literature, finding excellent agreement. We investigate the consequences of neglecting the spin-orbit and Coulomb residual interactions in QRPA. Furthermore we discuss the improvement obtained in the QRPA result associated with the removal of spurious modes. Isoscalar and isovector responses in the deformed {sup 24-26}Mg, {sup 34}Mg isotopes are presented and compared to experimental findings.

  4. Effective field theory of emergent symmetry breaking in deformed atomic nuclei

    DOE PAGESBeta

    Papenbrock, Thomas F.; Weidenmüller, H. A.

    2015-09-03

    Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. In this study, we extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. Lastly, in deformed nuclei these are vibrational modes each of whichmore » serves as band head of a rotational band.« less

  5. High Spin States and Octupole Deformation in Neutron-Rich ^145,147La Nuclei

    NASA Astrophysics Data System (ADS)

    Zhu, S. J.; Hamilton, J. H.; Ramayya, A. V.; Babu, B. R. S.; Jones, E. F.; Kormicki, J.; Daniel, A. V.; Hwang, J. K.; Beyer, C. J.; Wang, M. G.; Long, G. L.; Li, M.; Zhu, L. Y.; Gan, C. Y.; Ma, W. C.; Cole, J. D.; Aryaeinejad, R.; Dardenne, Y. X.; Drigert, M. W.; Rasmussen, J. O.; Asztalos, S.; Lee, I. Y.; Macchiavelli, A. O.; Chu, S. Y.; Gregorich, K. E.; Mohar, M. F.; Stoyer, M. A.; Lougheed, R. W.; Moody, K. J.; Wild, J. F.; Prussin, S. G.

    1998-04-01

    High spin states in neutron-rich odd-Z nuclei ^145,147La have been investigated from the study of prompt γ- rays in spontaneous fission of ^252Cf by using γ-γ- and γ-γ-γ- coincidence techniques. Alternating parity bands are extended up to spins I=(41/2) and I=(43/2) in ^145La and ^147La, respectively. Strong E1 transitions between the negative and positive parity bands give evidence for stable octupole deformation. The new higher spin levels give evidence for rotational enhancement of the stability of the octupole deformation. These collective bands show competition and co-existence between symmetric and asymmetric shapes in ^145La. Band crossing was found around hbarω≈ 0.26 ~0.30 MeV in both nuclei and these backbends are related to the alignment of two i_13/2 neutron from cranked shell model calculations.

  6. Effective field theory of emergent symmetry breaking in deformed atomic nuclei

    SciTech Connect

    Papenbrock, Thomas F.; Weidenmüller, H. A.

    2015-09-03

    Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. In this study, we extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. Lastly, in deformed nuclei these are vibrational modes each of which serves as band head of a rotational band.

  7. Gamow-Teller {beta}{sup +} decay of deformed nuclei near the proton drip line

    SciTech Connect

    Frisk, F.; Hamamoto, I.; Zhang, X.Z. |

    1995-11-01

    Using a quasiparticle Tamm-Dancoff approximation (TDA) based on deformed Hartree-Fock (HF) calculations with Skyrme interactions, the distribution of the Gamow-Teller (GT) {beta}{sup +} decay strength is estimated for the HF local minima of even-even deformed nuclei near the proton drip line in the region of 28{lt}{ital Z}{lt}66. The distribution often depends sensitively on the nuclear shape (namely, oblate or prolate). In the region of {ital Z}{lt}50 the possibility of observing {beta}-delayed proton emission depends sensitively on the excess of {ital Z} over {ital Z}={ital N}. In the region of {ital Z}{gt}50 almost the entire estimated GT strength is found to lie below the ground states of the even-even mother nuclei, and the observation of the total GT strength by {beta}-delayed charged-particle(s) emission will be of essential importance.

  8. Proximity potential for deformed, oriented nuclei: 'Gentle' fusion and 'hugging' fusion

    SciTech Connect

    Manhas, Monika; Gupta, Raj K.

    2005-08-01

    The proximity potential is obtained in the form of the generalized 'pocket formula' for a collision between any two symmetric or asymmetric mass, deformed and noncoplanar (including also the case of coplanar) nuclei, having the fixed orientations {theta}{sub 1} and {theta}{sub 2} and any azimuthal angle {phi}(=0 deg. - 90 deg.). The method is applied first to some illustrative axially symmetric noncoplanar nuclei with the known 'gentle'- and 'hugging'-fusion configurations ({theta}{sub 1}={theta}{sub 2}=90 deg., {phi}=90 deg.). The very general case of noncoplanar nuclei having any orientation and azimuthal angles is also discussed. Application of the method to a specific reaction that has been used in experiments for synthesizing a superheavy nucleus is also made.

  9. {sup 208}Pb-daughter cluster radioactivity and the deformations and orientations of nuclei

    SciTech Connect

    Arun, Sham K.; Gupta, Raj K.; Singh, BirBikram; Kanwar, Shefali; Sharma, Manoj K.

    2009-06-15

    The role of deformations and orientations of nuclei is studied for the first time in cluster decays of various radioactive nuclei, particularly those decaying to doubly closed shell, spherical {sup 208}Pb daughter nucleus. Also, the significance of using the correct Q-value of the decay process is pointed out. The model used is the preformed cluster model (PCM) of Gupta and collaborators [R. K. Gupta et al., Proc. Int. Conf. on Nuclear Reactions Mechanisms, Varenna, 1988, p. 416; Phys. Rev. C 39, 1992 (1989); 55, 218 (1997); Heavy Elements and Related New Phenomena, edited by W. Greiner and R. K. Gupta, World Sc. 1999, Vol. II, p. 731]. In this model, cluster emission is treated as a tunneling of the confining interaction barrier by a cluster considered already preformed with a relative probability P{sub 0}. Since both the scattering potential and potential energy surface due to the fragmentation process in the ground state of the parent nucleus change significantly with the inclusion of deformation and orientation effects, both the penetrability P and preformation probability P{sub 0} of clusters change accordingly. The calculated decay half-lives for all the cluster decays investigated here are generally in good agreement with measured values for the calculation performed with quadrupole deformations {beta}{sub 2} alone and 'optimum' orientations of cold elongated configurations. In some cases, particularly for {sup 14}C decay of Ra nuclei, the inclusion of multipole deformations up to hexadecapole {beta}{sub 4} is found to be essential for a comparison with data. However, the available {beta}{sub 4}-values, particularly for nuclei in the mass region 16{<=}A{<=}26, need be used with caution.

  10. From superdeformation to extreme deformation and clusterization in the N ≈Z nuclei of the A ≈40 mass region

    NASA Astrophysics Data System (ADS)

    Ray, D.; Afanasjev, A. V.

    2016-07-01

    A systematic search for extremely deformed structures in the N ≈Z nuclei of the A ≈40 mass region has been performed for the first time in the framework of covariant density functional theory. At spin zero such structures are located at high excitation energies, which prevents their experimental observation. The rotation acts as a tool to bring these exotic shapes to the yrast line or its vicinity so that their observation could become possible with future generation of γ -tracking (or similar) detectors such as GRETA and AGATA. The major physical observables of such structures (such as transition quadrupole moments, as well as kinematic and dynamic moments of inertia), the underlying single-particle structure and the spins at which they become yrast or near yrast, are defined. The search for the fingerprints of clusterization and molecular structures is performed and the configurations with such features are discussed. The best candidates for observation of extremely deformed structures are identified. For several nuclei in this study (such as 36Ar), the addition of several spin units above the currently measured maximum spin of 16 ℏ will inevitably trigger the transition to hyper- and megadeformed nuclear shapes.

  11. Deformed shell model results for neutrinoless double beta decay of nuclei in A = 60 - 90 region

    NASA Astrophysics Data System (ADS)

    Sahu, R.; Kota, V. K. B.

    2015-03-01

    Nuclear transition matrix elements (NTME) for the neutrinoless double beta decay (Oνββ or OνDBD) of 70Zn, 80Se and 82Se nuclei are calculated within the framework of the deformed shell model (DSM) based on Hartree-Fock (HF) states. For 70Zn, jj44b interaction in 2p3/2, 1f5/2, 2p1/2 and 1g9/2 space with 56Ni as the core is employed. However, for 80Se and 82Se nuclei, a modified Kuo interaction with the above core and model space are employed. Most of our calculations in this region were performed with this effective interaction. However, jj44b interaction has been found to be better for 70Zn. The above model space was used in many recent shell model (SM) and interacting boson model (IBM) calculations for nuclei in this region. After ensuring that DSM gives good description of the spectroscopic properties of low-lying levels in these three nuclei considered, the NTME are calculated. The deduced half-lives with these NTME, assuming neutrino mass is 1 eV, are 1.1 × 1026, 2.3 × 1027 and 2.2 × 1024 yr for 70Zn, 80Se and 82Se, respectively.

  12. Octupole Deformation Bands of πh11/2 in Neutron-Rich 145,147La Nuclei

    NASA Astrophysics Data System (ADS)

    Zhu, Sheng-jiang; S, Zhu J.; Wang, Mu-ge; J, Hamilton H.; A, Ramayya V.; B, Babu R. S.; W, Ma C.; Long, Gui-lu; Zhu, Ling-yan; Li, Ming; A, Sakhaee; Gan, Cui-yun; Yang, Li-ming; J, Komicki; J, Cole D.; R, Aryaeinejad; M, Drigert W.; J, Rasmussen O.; M, Stoyer A.; S, Chu Y.; K, Gregorich E.; M, Mohar F.; S, Prussin G.; I, Lee Y.; Yu, Oganessian Ts; G, Ter-Akopian M.; A, Daniel V.

    1999-03-01

    Octupole deformation bands built on πh11/2 orbital in neutron-rich odd-Z 145,147La nuclei have been investigated by measuring the prompt γ-rays emitted from the 252Cf source. The alternating parity band structures and strong E1 transitions observed between negative- and positive-parity bands in both nuclei indicate the octupole deformation enhanced by the h11/2 single proton coupling. According to observed energy displacements the octupole deformation becomes stable at the intermediate spin states.

  13. Skyrme random-phase-approximation description of lowest Kπ=2γ+ states in axially deformed nuclei

    NASA Astrophysics Data System (ADS)

    Nesterenko, V. O.; Kartavenko, V. G.; Kleinig, W.; Kvasil, J.; Repko, A.; Jolos, R. V.; Reinhard, P.-G.

    2016-03-01

    The lowest quadrupole γ -vibrational Kπ=2+ states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies Eγ and reduced transition probabilities B (E 2 ) of 2γ+ states are calculated with the Skyrme forces SV-bas and SkM*. The energies of two-quasiparticle configurations forming the SRPA basis are corrected by using the pairing blocking effect. This results in a systematic downshift of Eγ by 0.3-0.5 MeV and thus in a better agreement with the experiment, especially in Sm, Gd, Dy, Hf, and W regions. For other isotopic chains, a noticeable overestimation of Eγ and too weak collectivity of 2γ+ states still persist. It is shown that domains of nuclei with low and high 2γ+ collectivity are related to the structure of the lowest two-quasiparticle states and conservation of the Nilsson selection rules. The description of 2γ+ states with SV-bas and SkM* is similar in light rare-earth nuclei but deviates in heavier nuclei. However SV-bas much better reproduces the quadrupole deformation and energy of the isoscalar giant quadrupole resonance. The accuracy of SRPA is justified by comparison with exact RPA. The calculations suggest that a further development of the self-consistent calculation schemes is needed for a systematic satisfactory description of the 2γ+ states.

  14. Probing resonances in deformed nuclei by using the complex-scaled Green's function method

    NASA Astrophysics Data System (ADS)

    Shi, Xin-Xing; Shi, Min; Niu, Zhong-Ming; Heng, Tai-Hua; Guo, Jian-You

    2016-08-01

    Resonance plays a key role in the formation of many physical phenomena. The complex-scaled Green's function method provides a powerful tool for exploring resonance. In this paper, we combine this method with the theory describing deformed nuclei with the formalism presented. Taking 45S as an example, we elaborate numerical details and demonstrate how to determine the resonance parameters. The results are compared with those obtained by the complex scaling method and the coupled-channel method and satisfactory agreement is obtained. In particular, the present scheme focuses on the advantages of the complex scaling method and the Green's function method and is more suitable for the exploration of resonance.

  15. Charge-exchange QRPA with the Gogny Force for Axially-symmetric Deformed Nuclei

    SciTech Connect

    Martini, M.; Goriely, S.; Péru, S.

    2014-06-15

    In recent years fully consistent quasiparticle random-phase approximation (QRPA) calculations using finite range Gogny force have been performed to study electromagnetic excitations of several axially-symmetric deformed nuclei up to the {sup 238}U. Here we present the extension of this approach to the charge-exchange nuclear excitations (pnQRPA). In particular we focus on the Isobaric Analog and Gamow-Teller resonances. A comparison of the predicted GT strength distribution with existing experimental data is presented. The role of nuclear deformation is shown. Special attention is paid to β-decay half-lives calculations for which experimental data exist and for specific isotone chains of relevance for the r-process nucleosynthesis.

  16. Interplay between proton-neutron pairing and deformation in self-conjugated medium mass nuclei

    NASA Astrophysics Data System (ADS)

    Gambacurta, Danilo; Lacroix, Denis

    2016-05-01

    We employ a model combining self-consistent mean-field and shell model techniques to study the competition between particle-like and proton-neutron pairing correlations in fp-shell even-even self-conjugate nuclei. Deformation effects are realistically and microscopically described. The resulting approach can give a precise description of pairing correlations and eventually treat the coexistence of different condensate formed of pairs with different total spin/ isospin. The standard BCS calculations are systematically compared with approaches including correlation effects beyond the independent quasi-particle picture. The competition between proton-neutron correlations in the isoscalar and isovector channels is also analyzed, as well as their dependence on the deformation properties.

  17. Derivation of an optical potential for statically deformed rare-earth nuclei from a global spherical potential

    SciTech Connect

    Nobre, G. P. A.; Palumbo, A.; Herman, M.; Brown, D.; Hoblit, S.; Dietrich, F. S.

    2015-02-25

    The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations characterized by nuclear deformations. A proper treatment of such excitations is often essential to the accurate description of experimental nuclear-reaction data and to the prediction of a wide variety of scattering observables. Stimulated by recent work substantiating the near validity of the adiabatic approximation in coupled-channel calculations for scattering on statically deformed nuclei, we explore the possibility of generalizing a global spherical optical model potential (OMP) to make it usable in coupled-channel calculations on this class of nuclei. To do this, we have deformed the Koning-Delaroche global spherical potential for neutrons, coupling a sufficient number of states of the ground state band to ensure convergence. We present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions for neutron-induced reactions on statically deformed nuclei in the rare-earth region. We choose isotopes of three rare-earth elements (Gd, Ho, W), which are known to be nearly perfect rotors, to exemplify the results of the proposed method. Predictions from our model for total, elastic and inelastic cross sections, as well as for elastic and inelastic angular distributions, are in reasonable agreement with measured experimental data. In conclusion, these results suggest that the deformed Koning-Delaroche potential provides a useful regional neutron optical potential for the statically deformed rare earth nuclei.

  18. Shape of Ar44: Onset of deformation in neutron-rich nuclei near Ca48

    NASA Astrophysics Data System (ADS)

    Zielińska, M.; Görgen, A.; Clément, E.; Delaroche, J.-P.; Girod, M.; Korten, W.; Bürger, A.; Catford, W.; Dossat, C.; Iwanicki, J.; Libert, J.; Ljungvall, J.; Napiorkowski, P. J.; Obertelli, A.; Piętak, D.; Rodríguez-Guzmán, R.; Sletten, G.; Srebrny, J.; Theisen, Ch.; Wrzosek, K.

    2009-07-01

    The development of deformation and shape coexistence in the vicinity of doubly magic Ca48, related to the weakening of the N=28 shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive Ar44 beam from the SPIRAL facility at GANIL. The 21+ and 22+ states in Ar44 were excited on Pb208 and Ag109 targets at two different beam energies. B(E2) values between all observed states and the spectroscopic quadrupole moment of the 21+ state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the Ar44 nucleus and giving evidence of an onset of deformation already two protons and two neutrons away from doubly magic Ca48. New Hartree-Fock-Bogoliubov based configuration mixing calculations have been performed with the Gogny D1S interaction for Ar44 and neighboring nuclei using two different approaches: the angular momentum projected generator coordinate method considering axial quadrupole deformations and a five-dimensional approach including the triaxial degree of freedom. The experimental values and new calculations are furthermore compared to shell-model calculations and to relativistic mean-field calculations. The new results give insight into the weakening of the N=28 shell closure and the development of deformation in this neutron-rich region of the nuclear chart.

  19. Review of metastable states in heavy nuclei.

    PubMed

    Dracoulis, G D; Walker, P M; Kondev, F G

    2016-07-01

    The structure of nuclear isomeric states is reviewed in the context of their role in contemporary nuclear physics research. Emphasis is given to high-spin isomers in heavy nuclei, with [Formula: see text]. The possibility to exploit isomers to study some of the most exotic nuclei is a recurring theme. In spherical nuclei, the role of octupole collectivity is discussed in detail, while in deformed nuclei the limitations of the K quantum number are addressed. Isomer targets and isomer beams are considered, along with applications related to energy storage, astrophysics, medicine, and experimental advances. PMID:27243336

  20. Review of metastable states in heavy nuclei

    NASA Astrophysics Data System (ADS)

    Dracoulis, G. D.; Walker, P. M.; Kondev, F. G.

    2016-07-01

    The structure of nuclear isomeric states is reviewed in the context of their role in contemporary nuclear physics research. Emphasis is given to high-spin isomers in heavy nuclei, with A≳ 150 . The possibility to exploit isomers to study some of the most exotic nuclei is a recurring theme. In spherical nuclei, the role of octupole collectivity is discussed in detail, while in deformed nuclei the limitations of the K quantum number are addressed. Isomer targets and isomer beams are considered, along with applications related to energy storage, astrophysics, medicine, and experimental advances.

  1. Non-Axial Octupole Deformations and Tetrahedral Symmetry in Heavy Nuclei

    SciTech Connect

    Mazurek, Katarzyna; Dudek, Jerzy

    2005-11-21

    The total energies of about 120 nuclei in the Thorium region have been calculated within the macroscopic-microscopic method in the 5-dimensional space of deformation parameters {alpha}20, {alpha}22, {alpha}30, {alpha}32 and {alpha}40. The macroscopic energy term contains the nuclear surface-curvature dependence as proposed within the LSD approach. The microscopic energies are calculated with the Woods-Saxon single particle potential employing the universal set of parameters.We study a possible presence of the octupole axial and non-axial degrees of freedom all-over in the ({beta}, {gamma})-plane focussing on the ground-states, secondary minima and in the saddle points. In fact, a competition between axial and tri-axial octupole deformation parameters is obtained at the saddle points and in the secondary minima for many isotones with N > 136. The presence of the tetrahedral symmetry minima is predicted in numerous nuclei in the discussed region, although most of the time at relatively high excitation energies.

  2. Deformed rotational bands in the doubly odd nuclei [sup 134]Pr and [sup 132]Pr

    SciTech Connect

    Hauschild, K.; Wadsworth, R.; Clark, R.M.; Hibbert, I.M. ); Beausang, C.W.; Forbes, S.A.; Nolan, P.J.; Paul, E.S.; Semple, A.T.; Wilson, J.N. ); Gizon, A.; Gizon, J.; Santos, D. ); Simpson, J. )

    1994-08-01

    The nuclei [sup 132,134]Pr have been investigated using the [sup 100]Mo([sup 37]Cl,[ital xn]) reactions at a beam energy of 155 MeV. Gamma rays were detected with the Eurogam array. Analysis of the data has revealed the presence of two new weakly populated decoupled bands in [sup 134]Pr. One of these bands has been linked into the normal-deformed states and is thought to be built on a [pi]([ital h][sub 11/2])[sup 2][direct product][nu]([ital f][sub 7/2],[ital h][sub 9/2]) configuration. The second band has been interpreted as being based on a [pi]([ital h][sub 11/2])[sup 3][direct product][nu][ital i][sub 13/2] intruder configuration within the second [beta][sub 2][congruent]0.3 prolate minimum. The known decoupled band in [sup 132]Pr (5[ital n] reaction channel) and the highly deformed band in [sup 130]La A([alpha]3[ital n]) have also been extended. The structure of all of these bands is discussed together with similar bands in nieghboring odd-odd nuclei.

  3. Fragmentation of two-phonon {gamma}-vibrational strength in deformed nuclei

    SciTech Connect

    Wu, C.Y.; Cline, D.

    1996-12-31

    Rotational and vibrational modes of collective motion. are very useful in classifying the low-lying excited states in deformed nuclei. The rotational mode of collective motion is characterized by rotational bands having correlated level energies and strongly-enhanced E2 matrix elements. The lowest intrinsic excitation with I,K{sup {pi}} = 2,2{sup +} in even-even deformed nuclei, typically occurring at {approx}1 MeV, is classified as a one-phonon {gamma}-vibration state. In a pure harmonic vibration limit, the expected two-phonon {gamma}-vibration states with I,K{sup {pi}} = 0,0{sup +} and 4,4{sup +} should have excitation energies at twice that of the I,K{sup {pi}} = 2,2{sup +} excitation, i.e. {approx}2 MeV, which usually is above the pairing gap leading to possible mixing with two-quasiparticle configurations. Therefore, the question of the localization of two-phonon {gamma}-vibration strength has been raised because mixing may lead to fragmentation of the two-phonon strength over a range of excitation energy. For several well-deformed nuclei, an assignment of I,K{sup {pi}}=4,4{sup +} states as being two-phonon vibrational excitations has been suggested based on the excitation energies and the predominant {gamma}-ray decay to the I,K{sup {pi}}=2,2{sup +} state. However, absolute B(E2) values connecting the presumed two- and one-phonon states are the only unambiguous measure of double phonon excitation. Such B(E2) data are available for {sup 156}Gd, {sup 160}Dy, {sup 168}Er, {sup 232}Th, and {sup 186,188,190,192}Os. Except for {sup 160}Dy, the measured B(E2) values range from 2-3 Weisskopf units in {sup 156}Gd to 10-20 Weisskopf units in osmium nuclei; enhancement that is consistent with collective modes of motion.

  4. Octupole deformation in the ground states of even-even nuclei: A global analysis within the covariant density functional theory

    NASA Astrophysics Data System (ADS)

    Agbemava, S. E.; Afanasjev, A. V.; Ring, P.

    2016-04-01

    A systematic investigation of octupole-deformed nuclei is presented for even-even systems with Z ≤106 located between the two-proton and two-neutron driplines. For this study we use five most-up-to-date covariant energy density functionals of different types, with a nonlinear meson coupling, with density-dependent meson couplings, and with density-dependent zero-range interactions. Pairing correlations are treated within relativistic Hartree-Bogoliubov theory based on an effective separable particle-particle interaction of finite range. This allows us to assess theoretical uncertainties within the present covariant models for the prediction of physical observables relevant for octupole-deformed nuclei. In addition, a detailed comparison with the predictions of nonrelativistic models is performed. A new region of octupole deformation, centered around Z ˜98 ,N ˜196 is predicted for the first time. In terms of its size in the (Z ,N ) plane and the impact of octupole deformation on binding energies this region is similar to the best known region of octupole-deformed nuclei centered at Z ˜90 ,N ˜136 . For the later island of octupole-deformed nuclei, the calculations suggest substantial increase of its size as compared with available experimental data.

  5. Effect of deformations on the binding energy of centrally depressed nuclei

    NASA Astrophysics Data System (ADS)

    Ismail, M.; Ellithi, A. Y.; Adel, A.; Abdulghany, A. R.

    2015-07-01

    The energy density formalism is implemented to study the binding energy of some heavy, superheavy and hyperheavy nuclei. The macroscopic contribution of binding energy is derived in the presence of a depression parameter in the nuclear density distribution, and the total energy is obtained by adding the shell and pairing correction to the macroscopic part. Total energy is studied with the variation of quadrupole {{β }2} and hexadecapole {{β }4} deformation parameters using different values of depression parameter. The addition of the shell and pairing corrections affects the behavior of the total energy especially the minimum position at specific deformation parameters, a second minimum in some cases are close to the first one, suggesting the possible existence of shape isomers. We minimized the total energy with respect to deformation and density depression parameters and obtained the binding energy of 208Pb, 238U, 252Cf, 280Cn, 285-289Fl, 298Fl, 306120, 320126, 339136, 500174 and 700226. The binding energies obtained are in good agreement with the available experimental data. The difference between the binding energies obtained by this simple method and experimental ones is less than 0.13%.

  6. Investigation of the Dipole Response in Exotic Nuclei --- Experiments at the LAND-R^3B Setup

    NASA Astrophysics Data System (ADS)

    Rossi, D.; Adrich, P.; Aksouh, F.; Alvarez-Pol, H.; Aumann, T.; Benlliure, J.; Böhmer, M.; Boretzky, K.; Casarejos, E.; Chartier, M.; Chatillon, A.; Cortina-Gil, D.; Pramanik, U. D.; Emling, H.; Ershova, O.; Fernando-Dominguez, B.; Geissel, H.; Gorska, M.; Heil, M.; Johansson, H. k.; Junghans, A.; Kiselev, O.; Klimkiewicz, A.; Kratz, J.; Kurz, N.; Labiche, M.; Bleis, T. L.; Lemmon, R.; Litvinov, Y.; Mahata, K.; Maierbeck, P.; Movsesyan, A.; Nilsson, T.; Nociforo, C.; Palit, R.; Paschalis, S.; Plag, R.; Reifarth, R.; Simon, H.; Sümmerer, K.; Wagner, A.; Walus, W.; Weick, H.; Winkler, M.

    We present experimental results on the electromagneticexcitation of neutron-rich nickel isotopes, making use of the R^{3}B-LAND setup at GSI. Exotic beams were produced at approximately 500 MeV/u and their reactions were studied in inverse kinematics. Integral cross sections for ^{58}Ni are discussed and compared to previous data, providing a validation of our experimental method. The E1 excitation-energy distribution of the unstable ^{68}Ni is presented as well, showing an excess in cross section in the 1n decay channel when compared only with a typical Giant Dipole Resonance.

  7. Reaction cross-section calculations using new experimental and theoretical level structure data for deformed nuclei

    SciTech Connect

    Hoff, R.W.; Gardner, D.G.; Gardner, M.A.

    1984-10-05

    A technique for modeling quasiparticle excitation energies and rotational parameters in odd-odd deformed nuclei has been used to construct sets of discrete states with energy 0 to 1.5 MeV in /sup 176/Lu and /sup 236/Np. These data were used as part of the input for calculation of isomer production cross-section ratios in the /sup 175/Lu(n,..gamma..)/sup 176/Lu and /sup 237/Np(n,2n)/sup 236/Np reactions. In order to achieve agreement with experiment, it has been found necessary to include in the modeled set many rotational bands (35 to 95), which are comprised of hundreds of levels with their gamma-ray branching ratios. It is essential that enough bands be included to produce a representative selection of K quantum numbers in the de-excitation cascade. 20 refs., 3 figs., 3 tabs.

  8. Deformation signature from the Gamow-Teller decay of N=Z nuclei

    SciTech Connect

    Miehe, Ch.; Dessagne, Ph.; Huck, A.; Knipper, A.; Marguier, G.; Longour, C.; Rauch, V.; Giovinazzo, J.; Borge, M. J. G.; Piqueras, I.; Tengblad, O.; Jokinen, A.; Ramdhane, M.

    1998-12-21

    The {sup 76}Sr (N=Z=38) and the {sup 72}Kr (N=Z=36) {beta}{sup +} EC decay have been studied at the CERN/ISOLDE PSB facility where their beta-gamma and delayed particle decay modes have been investigated. The established decay schemes yield new information on the Gamow-Teller (GT) strength spread over the J{sup {pi}}=1{sup +} states in the daughter nuclei. The delayed proton emission of an N=Z nucleus is observed for the first time in the case of {sup 76}Sr. The experimental GT strength intensities and distributions are discussed in the light of the theoretical estimates for oblate and prolate deformations.

  9. Theory of (3He,(alpha)) surrogate reactions for deformed uranium nuclei

    SciTech Connect

    Thompson, I; Escher, J E

    2006-11-08

    We present the one-step theory of neutron-pickup transfer reactions with {sup 3}He projectiles on {sup 235}U and {sup 238}U. We find all the neutron eigenstates in a deformed potential, and use those in a given energy range for ({sup 3}He, {alpha}) DWBA pickup calculations to find the spin and parity distributions of the residual target nuclei. A simple smoothing convolution is used to take into account the spreading width of the single-neutron hole states into the more complicated compound nuclear states. We assume that the initial target is an even-even rotor, but can take into account spectator neutrons outside such a rotor by recombining their spin and parity at the end of the calculations.

  10. Derivation of an optical potential for statically deformed rare-earth nuclei from a global spherical potential

    DOE PAGESBeta

    Nobre, G. P. A.; Palumbo, A.; Herman, M.; Brown, D.; Hoblit, S.; Dietrich, F. S.

    2015-02-25

    The coupled-channel theory is a natural way of treating nonelastic channels, in particular those arising from collective excitations characterized by nuclear deformations. A proper treatment of such excitations is often essential to the accurate description of experimental nuclear-reaction data and to the prediction of a wide variety of scattering observables. Stimulated by recent work substantiating the near validity of the adiabatic approximation in coupled-channel calculations for scattering on statically deformed nuclei, we explore the possibility of generalizing a global spherical optical model potential (OMP) to make it usable in coupled-channel calculations on this class of nuclei. To do this, wemore » have deformed the Koning-Delaroche global spherical potential for neutrons, coupling a sufficient number of states of the ground state band to ensure convergence. We present an extensive study of the effects of collective couplings and nuclear deformations on integrated cross sections as well as on angular distributions for neutron-induced reactions on statically deformed nuclei in the rare-earth region. We choose isotopes of three rare-earth elements (Gd, Ho, W), which are known to be nearly perfect rotors, to exemplify the results of the proposed method. Predictions from our model for total, elastic and inelastic cross sections, as well as for elastic and inelastic angular distributions, are in reasonable agreement with measured experimental data. In conclusion, these results suggest that the deformed Koning-Delaroche potential provides a useful regional neutron optical potential for the statically deformed rare earth nuclei.« less

  11. Coupled-channel effects in elastic scattering and near-barrier fusion induced by weakly bound nuclei and exotic halo nuclei

    SciTech Connect

    Beck, C.; Keeley, N.

    2007-05-15

    The influence on fusion of coupling to the breakup process is investigated for reactions where at least one of the colliding nuclei has a sufficiently low binding energy for breakup to become an important process. Elastic scattering, excitation functions for sub- and near-barrier fusion cross sections, and breakup yields are analyzed for {sup 6,7}Li+{sup 59}Co. Continuum-discretized coupled-channels (CDCC) calculations describe well the data at and above the barrier. Elastic scattering with {sup 6}Li (as compared to {sup 7}Li) indicates the significant role of breakup for weakly bound projectiles. A study of {sup 4,6}He induced fusion reactions with a three-body CDCC method for the {sup 6}He halo nucleus is presented. The relative importance of breakup and bound-state structure effects on total fusion is discussed.

  12. A high-performance multiple-reflection time-of-flight mass spectrometer and isobar separator for the research with exotic nuclei

    NASA Astrophysics Data System (ADS)

    Dickel, T.; Plaß, W. R.; Becker, A.; Czok, U.; Geissel, H.; Haettner, E.; Jesch, C.; Kinsel, W.; Petrick, M.; Scheidenberger, C.; Simon, A.; Yavor, M. I.

    2015-03-01

    A novel multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) and isobar separator for the research with exotic nuclides at low-energy rare isotope beam facilities has been developed, commissioned and characterized. It can be used (i) as broadband mass spectrometer with medium resolution, (ii) as highly accurate mass spectrometer for direct mass measurements and (iii) as high-resolution mass separator. The device features a worldwide unique combination of performance characteristics: a mass resolving power of 600,000 (FWHM), a mass measurement accuracy of ~10-7, large ion capacities in excess of 106 ions per second, a transmission efficiency of up to 70%, single-ion sensitivity, and cycle frequencies of up to 400 Hz have been achieved. The spatial separation of close-lying isobars with an intensity ratio of 200:1 and a binding energy difference as small as 4 MeV has been demonstrated. The MR-TOF-MS is ideally suited for experiments with rare and very short-lived nuclei at present and future in-flight, ISOL or IGISOL facilities, such as the FRS Ion-Catcher and SHIP/SHIPTRAP at GSI, TITAN at TRIUMF, IGISOL at the University of Jyväskylä and the Low-Energy Branch of the Super-FRS at FAIR.

  13. Physics of Unstable Nuclei

    NASA Astrophysics Data System (ADS)

    Khoa, Dao Tien; Egelhof, Peter; Gales, Sydney; Giai, Nguyen Van; Motobayashi, Tohru

    2008-04-01

    ]C([symbol], n)[symbol]O by the transfer reaction [symbol]C([symbol]Li, t)[symbol]O / F. Hammache et al. -- SPIRAL2 at GANIL: a world of leading ISOL facility for the physics of exotic nuclei / S. Gales -- Magnetic properties of light neutron-rich nuclei and shell evolution / T. Suzuki, T. Otsuka -- Multiple scattering effects in elastic and quasi free proton scattering from halo nuclei / R. Crespo et al. -- The dipole response of neutron halos and skins / T. Aumann -- Giant and pygmy resonances within axially-symmetric-deformed QRPA with the Gogny force / S. Péru, H. Goutte -- Soft K[symbol] = O+ modes unique to deformed neutron-rich unstable nuclei / K. Yoshida et al. -- Synthesis, decay properties, and identification of superheavy nuclei produced in [symbol]Ca-induced reactions / Yu. Ts. Oganessian et al. -- Highlights of the Brazilian RIB facility and its first results and hindrance of fusion cross section induced by [symbol]He / P. R. S. Gomes et al. -- Search for long fission times of super-heavy elements with Z = 114 / M. Morjean et al. -- Microscopic dynamics of shape coexistence phenomena around [symbol]Se and [symbol]Kr / N. Hinohara et al. -- [symbol]-cluster states and 4[symbol]-particle condensation in [symbol]O / Y. Funaki et al. -- Evolution of the N = 28 shell closure far from stability / O. Sorlin et al. -- Continuum QRPA approach and the surface di-neutron modes in nuclei near the neutron drip-line / M. Matsuo et al. -- Deformed relativistic Hartree-Bogoliubov model for exotic nuclei / S. G. Zhou et al. -- Two- and three-body correlations in three-body resonances and continuum states / K. Katō, K. Ikeda -- Pion- and Rho-Meson effects in relativistic Hartree-Fock and RPA / N. V. Giai et al. -- Study of the structure of neutron rich nuclei by using [symbol]-delayed neutron and gamma emission method / Y. Ye et al. -- Production of secondary radioactive [symbol] Na beam for the study of [symbol]Na([symbol], p)[symbol]Mg stellar reaction / D. N. Binh et al

  14. Experimental study of the electric dipole strength in the even Mo nuclei and its deformation dependence

    NASA Astrophysics Data System (ADS)

    Erhard, M.; Junghans, A. R.; Nair, C.; Schwengner, R.; Beyer, R.; Klug, J.; Kosev, K.; Wagner, A.; Grosse, E.

    2010-03-01

    Two methods based on bremsstrahlung were applied to the stable even Mo isotopes for the experimental determination of the photon strength function covering the high excitation energy range above 4 MeV with its increasing level density. Photon scattering was used up to the neutron separation energies Sn and data up to the maximum of the isovector giant resonance (GDR) were obtained by photoactivation. After a proper correction for multistep processes the observed quasicontinuous spectra of scattered photons show a remarkably good match to the photon strengths derived from nuclear photoeffect data obtained previously by neutron detection and corrected in absolute scale by using the new activation results. The combined data form an excellent basis to derive a shape dependence of the E1 strength in the even Mo isotopes with increasing deviation from the N=50 neutron shell (i.e., with the impact of quadrupole deformation and triaxiality). The wide energy coverage of the data allows for a stringent assessment of the dipole sum rule and a test of a novel parametrization developed previously which is based on it. This parametrization for the electric dipole strength function in nuclei with A>80 deviates significantly from prescriptions generally used previously. In astrophysical network calculations it may help to quantify the role the p-process plays in cosmic nucleosynthesis. It also has impact on the accurate analysis of neutron capture data of importance for future nuclear energy systems and waste transmutation.

  15. Roles of deformation and orientation in heavy-ion collisions induced by light deformed nuclei at intermediate energy

    SciTech Connect

    Cao, X. G.; Zhang, G. Q.; Cai, X. Z.; Ma, Y. G.; Guo, W.; Chen, J. G.; Tian, W. D.; Fang, D. Q.; Wang, H. W.

    2010-06-15

    The reaction dynamics of axisymmetric deformed {sup 24}Mg+{sup 24}Mg collisions has been investigated systematically by an isospin-dependent quantum molecular dynamics model. It is found that different deformations and orientations result in apparently different properties of reaction dynamics. We reveal that some observables such as nuclear stopping power (R), multiplicity of fragments, and elliptic flow are very sensitive to the initial deformations and orientations. There exists an eccentricity scaling of elliptic flow in central body-body collisions with different deformations. In addition, the tip-tip and body-body configurations turn out to be two extreme cases in central reaction dynamical process.

  16. Dirac-Hartree-Bogoliubov calculation for spherical and deformed hot nuclei: Temperature dependence of the pairing energy and gaps, nuclear deformation, nuclear radii, excitation energy, and entropy

    NASA Astrophysics Data System (ADS)

    Lisboa, R.; Malheiro, M.; Carlson, B. V.

    2016-02-01

    Background: Unbound single-particle states become important in determining the properties of a hot nucleus as its temperature increases. We present relativistic mean field (RMF) for hot nuclei considering not only the self-consistent temperature and density dependence of the self-consistent relativistic mean fields but also the vapor phase that takes into account the unbound nucleon states. Purpose: The temperature dependence of the pairing gaps, nuclear deformation, radii, binding energies, entropy, and caloric curves of spherical and deformed nuclei are obtained in self-consistent RMF calculations up to the limit of existence of the nucleus. Method: We perform Dirac-Hartree-Bogoliubov (DHB) calculations for hot nuclei using a zero-range approximation to the relativistic pairing interaction to calculate proton-proton and neutron-neutron pairing energies and gaps. A vapor subtraction procedure is used to account for unbound states and to remove long range Coulomb repulsion between the hot nucleus and the gas as well as the contribution of the external nucleon gas. Results: We show that p -p and n -n pairing gaps in the S10 channel vanish for low critical temperatures in the range Tcp≈0.6 -1.1 MeV for spherical nuclei such as 90Zr, 124Sn, and 140Ce and for both deformed nuclei 150Sm and 168Er. We found that superconducting phase transition occurs at Tcp=1.03 Δp p(0 ) for 90Zr, Tcp=1.16 Δp p(0 ) for 140Ce, Tcp=0.92 Δp p(0 ) for 150Sm, and Tcp=0.97 Δp p(0 ) for 168Er. The superfluidity phase transition occurs at Tcp=0.72 Δn n(0 ) for 124Sn, Tcp=1.22 Δn n(0 ) for 150Sm, and Tcp=1.13 Δn n(0 ) for 168Er. Thus, the nuclear superfluidity phase—at least for this channel—can only survive at very low nuclear temperatures and this phase transition (when the neutron gap vanishes) always occurs before the superconducting one, where the proton gap is zero. For deformed nuclei the nuclear deformation disappear at temperatures of about Tcs=2.0 -4.0 MeV , well above the

  17. Interplay of collective and single-particle properties of excited states of deformable odd nuclei {sup 155}Eu and {sup 161}Tm

    SciTech Connect

    Sharipov, Sh.; Ermamatov, M. J. Bayimbetova, J. K.

    2008-02-15

    The properties of excited states of two deformable odd nuclei are investigated within the nonadiabatic model previously developed by the present authors. The results of relevant calculations are compared with available experimental data.

  18. Multiquark exotics

    SciTech Connect

    Lipkin, H.J.

    1983-01-01

    The question Are Anomalons Multiquark Exotics is discussed. It is concluded that so far there is no convincing experimental evidence for any multiquark exotic bound state nor for any exotic resonance. Except for the delta and S* there are no candidates for bound states and no firm theoretical predictions waiting to be tested. Exotic resonances may exist in the 1.5 to 2.0 GeV region and in the charmed sector, e.g., the charmed-strange exotics. The experimental search for multiquark resonances is still open and active. (WHK)

  19. A C-code for the double folding interaction potential for reactions involving deformed target nuclei

    NASA Astrophysics Data System (ADS)

    Gontchar, I. I.; Chushnyakova, M. V.

    2013-01-01

    We present a C-code designed to obtain the interaction potential between a spherical projectile nucleus and an axial-symmetrical deformed target nucleus and in particular to find the Coulomb barrier, by using the double folding model (DFM). The program calculates the nucleus-nucleus potential as a function of the distance between the centers of mass of colliding nuclei as well as of the angle between the axis of symmetry of the target nucleus and the beam direction. The most important output parameters are the Coulomb barrier energy and the radius. Since many researchers use a Woods-Saxon profile for the nuclear term of the potential we provide an option in our code for fitting the DFM potential by such a profile near the barrier. Program summaryProgram title: DFMDEF Catalogue identifier: AENI_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENI_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 2245 No. of bytes in distributed program, including test data, etc.: 215442 Distribution format: tar.gz Programming language: C. Computer: PC, Mac. Operating system: Windows XP (with the GCC-compiler version 2), MacOS, Linux. RAM: 100 MB with average parameters set Classification: 17.9. Nature of problem: The code calculates in a semimicroscopic way the bare interaction potential between a spherical projectile nucleus and a deformed but axially symmetric target nucleus as a function of the center of mass distance as well as of the angle between the axis of symmetry of the target nucleus and the beam direction. The height and the position of the Coulomb barrier are found. The calculated potential is approximated by a conventional Woods-Saxon profile near the barrier. Dependence of the barrier parameters upon the characteristics of the effective NN forces (like, e

  20. Exotic Nuclei in South America

    SciTech Connect

    Lichtenthaeler, R.; Lepine-Szily, A.; Guimaraes, V.; Faria, P. N. de; Mendes, D. R. Jr; Pires, K. C. C.; Morcelle, V.; Barioni, A.; Morais, M. C.; Pampa Condori, R.; Assuncao, M.; Moro, A. M.; Rodriguez-Gallardo, M.; Arazi, A.

    2010-08-04

    The Radioactive Ion Beams in Brasil(RIBRAS) is described. Experiments using radioactive secondary beams of light rare isotopes such as {sup 6}He, {sup 7}Be, {sup 8}Li on several targets have been performed and the results are presented.

  1. Simple description of odd-A nuclei around the critical point of the spherical to axially deformed shape phase transition

    SciTech Connect

    Zhang Yu; Pan Feng; Liu Yuxin; Luo Yanan; Draayer, J. P.

    2011-09-15

    An analytically solvable model, X(3/2j+1), is proposed to describe odd-A nuclei near the X(3) critical point. The model is constructed based on a collective core described by the X(3) critical point symmetry coupled to a spin-j particle. A detailed analysis of the spectral patterns for cases j=1/2 and j=3/2 is provided to illustrate dynamical features of the model. By comparing theory with experimental data and results of other models, it is found that the X(3/2j+1) model can be taken as a simple yet very effective scheme to describe those odd-A nuclei with an even-even core at the critical point of the spherical to axially deformed shape phase transition.

  2. Deformed shell model results for neutrinoless positron double beta decay of nuclei in the A = 60-90 region

    NASA Astrophysics Data System (ADS)

    Sahu, R.; Srivastava, P. C.; Kota, V. K. B.

    2013-09-01

    Nuclear transition matrix elements (NTME) for neutrinoless positron double beta decay (0νβ+β+ and 0νβ+EC) of 64Zn, 74Se, 78Kr and 84Sr nuclei, which are in the A = 60-90 region, are calculated within the framework of the deformed shell model (DSM) based on Hartree-Fock states. For 64Zn, GXPF1A interaction in 1f7/2, 2p3/2, 1f5/2 and 2p1/2 space with 40Ca as the core is employed. Similarly for 74Se, 78Kr and 84Sr nuclei, 56Ni is taken as the inert core employing a modified Kuo interaction in 2p3/2, 1f5/2, 2p1/2 and 1g9/2 space. After ensuring that the DSM gives a good description of the spectroscopic properties of low-lying levels in the four nuclei considered, the NTME are calculated. The half-lives deduced with these NTME, assuming the neutrino mass is 1 eV, are smallest for 78Kr with the half-life for β+EC decay being ˜1027 yr. For all others, the half-lives are in the range of ˜1028-1029 yr.

  3. β+/EC decay rates of deformed neutron-deficient nuclei in the deformed QRPA with realistic interactions

    NASA Astrophysics Data System (ADS)

    Ni, Dongdong; Ren, Zhongzhou

    2015-05-01

    The weak-decay (β+ and EC) rates of neutron-deficient Kr, Sr, Zr, and Mo isotopes are investigated within the deformed quasiparticle random-phase approximation with realistic nucleon-nucleon interactions. The particle-particle and particle-hole channels of residual interactions are handled in large single-particle model spaces, based on the Brückner G-matrix with charge-dependent Bonn nucleon-nucleon forces. Contributions from allowed Gamow-Teller and Fermi transitions as well as first-forbidden transitions are calculated. The calculated half-lives show good agreement with the experimental data over a wide range of magnitude, from 10-2 to 107 s. Moreover, predictions of β-decay half-lives are made for some extremely proton-rich isotopes, which could be useful for future experiments.

  4. Identification of highly deformed even-even nuclei in the neutron- and proton-rich regions of the nuclear chart from the B(E2)↑ and E2 predictions in the generalized differential equation model

    NASA Astrophysics Data System (ADS)

    Nayak, R. C.; Pattnaik, S.

    2015-11-01

    We identify here the possible occurrence of large deformations in the neutron- and proton-rich (n-rich and p-rich) regions of the nuclear chart from extensive predictions of the values of the reduced quadrupole transition probability B(E2)↑ for the transition from the ground state to the first 2+ state and the corresponding excitation energy E2 of even-even nuclei in the recently developed generalized differential equation (GDE) model exclusively meant for these physical quantities. This is made possible from our analysis of the predicted values of these two physical quantities and the corresponding deformation parameters derived from them such as the quadrupole deformation β2, the ratio of β2 to the Weisskopf single-particle β2(sp) and the intrinsic electric quadrupole moment Q0, calculated for a large number of both known as well as hitherto unknown even-even isotopes of oxygen to fermium (0 to FM; Z = 8-100). Our critical analysis of the resulting data convincingly support possible existence of large collectivity for the nuclides 30,32Ne,34Mg, 60Ti, 42,62,64Cr,50,68Fe, 52,72Ni, 72,70,96Kr,74,76Sr,78,80,106,108Zr, 82,84,110,112Mo, 140Te,144Xe, 148Ba,122Ce, 128,156Nd,130,132,158,160Sm and 138,162,164,166Gd, whose values of β2 are found to exceed 0.3 and even 0.4 in some cases. Our findings of large deformations in the exotic n-rich regions support the existence of another “island of inversion” in the heavy-mass region possibly caused by breaking of the N = 70 subshell closure.

  5. Effects of angular dependence of surface diffuseness in deformed nuclei on Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Adamian, G. G.; Antonenko, N. V.; Malov, L. A.; Scamps, G.; Lacroix, D.

    2014-09-01

    The angular dependence of surface diffuseness is further discussed. The results of self-consistent calculations are compared with those obtained with the phenomenological mean-field potential. The rather simple parametrizations are suggested. The effects of surface polarization and hexadecapole deformation on the height of the Coulomb barrier are revealed.

  6. Total and partial capture cross sections in reactions with deformed nuclei at energies near and below the Coulomb barrier

    SciTech Connect

    Kuzyakin, R. A. Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.

    2013-06-15

    Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the {sup 16}O + {sup 112}Cd, {sup 152}Sm, and {sup 184}W; {sup 19}F +{sup 175}Lu; {sup 28}Si +{sup 94,100}Mo and {sup 154}Sm; {sup 40}Ca +{sup 96}Zr; {sup 48}Ca+ {sup 90}Zr; and {sup 64}Ni +{sup 58,64}Ni, {sup 92,96}Zr, and {sup 100}Mo reactions are in good agreement with available experimental data.

  7. Analytical description of odd-A nuclei near the critical point of the spherical to axially deformed shape transition

    SciTech Connect

    Zhang Yu; Pan Feng; Liu Yuxin; Hou Zhanfeng; Draayer, J. P.

    2010-09-15

    A coupling scheme for even-even nuclei with the X(5) critical point symmetry coupled to a single valence nucleon in a j orbit is proposed to approximately describe the critical point phenomena of spherical to axially deformed shape (phase) transition in odd-A nuclear systems. The corresponding scheme, which can be solved analytically, is called the X(5/(2j+1)) model. A special case with j=1/2 is analyzed in detail to show its level structure and transition patterns. It is further shown that {sup 189}Au and {sup 155}Tb may be possible X(5/(2j+1)) symmetry candidates with j=1/2 and j=3/2, respectively.

  8. Computer program for the relativistic mean field description of the ground state properties of even-even axially deformed nuclei

    NASA Astrophysics Data System (ADS)

    Ring, P.; Gambhir, Y. K.; Lalazissis, G. A.

    1997-09-01

    We present a Fortran program for the calculation of the ground state properties of axially deformed even-even nuclei in the framework of Relativistic Mean Field Theory (RMF). In this approach a set of coupled partial differentials has to be solved self-consistently: the Dirac equation for the nucleons moving in self-consistent fields and the Klein-Gordon equations for the meson fields and the electromagnetic field, whose sources are scalar and vector densities determined of the nucleons. For this purpose the Dirac spinors as well as the meson fields are expanded in terms of anisotropic oscillator wave functions in cylindrical coordinates. This requires a matrix diagonalization for the solution of the Dirac equations and the solution of an inhomogeneous matrix equation for the meson fields. For the determination of the Coulomb field the Greens function method is used.

  9. Total and partial capture cross sections in reactions with deformed nuclei at energies near and below the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Kuzyakin, R. A.; Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.

    2013-06-01

    Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the 16O + 112Cd, 152Sm, and 184W; 19F +175Lu; 28Si +94,100Mo and 154Sm; 40Ca +96Zr; 48Ca+ 90Zr; and 64Ni +58,64Ni, 92,96Zr, and 100Mo reactions are in good agreement with available experimental data.

  10. Dominance of Low Spin and High Deformation in Ab Initio Approaches to the Structure of Light Nuclei

    SciTech Connect

    Dytrych, T.; Draayer, J. P.; Sviratcheva, K. D.; Bahri, C.; Vary, J. P.

    2009-08-26

    Ab initio no-core shell-model solutions for the structure of light nuclei are shown to be dominated by low-spin and high-deformation configurations. This implies that only a small fraction of the full model space is important for a description of bound-state properties of light nuclei. It further points to the fact that the coupling scheme of choice for carrying out calculations for light nuclear systems is an algebraic-based, no-core shell-model scheme that builds upon an LS coupling [SO(3) x SU(2)] foundation with the spatial part of the model space further organized into its symplectic [SO(3) subset of SU(3) subset of Sp(3, R)] structure. Results for {sup 12}C and {sup 16}O are presented with the cluster nature of the excited 0{sup +} states in {sup 16}O analyzed within this framework. The results of the analysis encourages the development of a no-core shell model code that takes advantage of algebraic methods as well as modern computational techniques. Indeed, although it is often a very challenging task to cast complex algebraic constructs into simple logical ones that execute efficiently on modern computational systems, the construction of such a next-generation code is currently underway.

  11. Proton emission from the deformed odd-odd nuclei near drip line

    NASA Astrophysics Data System (ADS)

    Patial, M.; Arumugam, P.; Jain, A. K.; Maglione, E.; Ferreira, L. S.

    2016-01-01

    Proton emission from odd-odd nuclei is studied within the two quasiparticle plus rotor model which includes the non-adiabatic effects and the residual interaction between valence proton and neutron. Justification of the formalism is discussed through corroboration of our results with the experimental spectrum of 180Ta. Exact calculations are performed to get the proton emission halflives. Our results for the proton emitter 130Eu leads to the assignment of spin and parity Jπ = 1+ for the ground state. The role of Coriolis and residual neutron-proton interactions on the proton emission halflives and their interplay are also discussed.

  12. Further investigation of relativistic symmetry in deformed nuclei by similarity renormalization group

    NASA Astrophysics Data System (ADS)

    Li, Dong-Peng; Chen, Shou-Wan; Niu, Zhong-Ming; Liu, Quan; Guo, Jian-You

    2015-02-01

    Following a recent letter [J.-Y. Guo, S.-W. Chen, Z.-M. Niu, D.-P. Li, and Q. Liu, Phys. Rev. Lett. 112, 062502 (2014), 10.1103/PhysRevLett.112.062502], we present more details for the relativistic symmetry research by using the similarity renormalization group. With the theoretical formalism expressed in detail, we explore the origin and breaking mechanism of relativistic symmetries for an axially deformed nucleus. By comparing the energy splitting between the (pseudo-) spin doublets, it is shown that the spin energy splitting arises almost completely from the spin-orbit coupling, while the pseudospin energy splitting arises from a combination of the nonrelativistic, dynamical, and spin-orbit terms. Furthermore, these splittings are correlated with nuclear deformation as well as with the quantum numbers of the doublets. The origin of relativistic symmetries is disclosed and the breaking mechanism of spin and pseudospin symmetries is clarified.

  13. Selection rules for electromagnetic transitions in triaxially deformed odd-A nuclei

    SciTech Connect

    Tanabe, Kosai; Sugawara-Tanabe, Kazuko

    2008-06-15

    The approximate selection rules for the interband and intraband electromagnetic transitions are predicted referring to two quantum numbers, which are derived from an algebraic solution for the particle-rotor model with one high-j nucleon coupled to a triaxially deformed core. It is shown that the inclusion of angular momentum dependence for moments of inertia reproduces the experimental excitation energies relative to a reference quite well both for positive and negative parity TSD bands in {sup 161,163,165,167}Lu.

  14. Interplay between tensor force and deformation in even-even nuclei

    NASA Astrophysics Data System (ADS)

    Bernard, Rémi N.; Anguiano, Marta

    2016-09-01

    In this work we study the effect of the nuclear tensor force on properties related with deformation. We focus on isotopes in the Mg, Si, S, Ar, Sr and Zr chains within the Hartree-Fock-Bogoliubov theory using the D1ST2a Gogny interaction. Contributions to the tensor energy in terms of saturated and unsaturated subshells are analyzed. Like-particle and proton-neutron parts of the tensor term are independently examinated. We found that the tensor term may considerably modify the potential energy landscapes and change the ground state shape. We analyze too how the pairing characteristics of the ground state change when the tensor force is included.

  15. Deformation increase of high-spin core-excited isomers in the astatine nuclei

    SciTech Connect

    Scheveneels, G.; Hardeman, F.; Neyens, G.; Coussement, R. )

    1991-06-01

    Quadrupole moments of six high-spin isomers in the At isotopes have been measured with the level-mixing-spectroscopy method: {sup 208}At(16{sup {minus}}), {sup 209}At(29/2{sup +}), {sup 210}At(19{sup +},15{sup {minus}}), {sup 211}At(39/2{sup {minus}},29/2{sup +}). The results show that level mixing spectroscopy is a promising technique to determine quadrupole moments of isomers that are difficult to measure by other in-beam hyperfine interaction methods. A large increase of the quadrupole moment is observed if neutrons are excited across or removed from the {ital N}=126 shell closure. This behavior is explained in terms of an enhanced core softness for fewer core neutrons; the aligned valence particles, moving in equatorial orbits, then easily polarize the core towards oblate deformation.

  16. Charge-exchange modes of excitation in deformed neutron-rich nuclei

    SciTech Connect

    Yoshida, Kenichi

    2015-10-15

    Gamow-Teller (GT) mode of excitation and β-decay properties of deformed neutron-rich even-N Zr isotopes are investigated in a self-consistent Skyrme energy-density-functional approach, in which the Hartree-Fock-Bogoliubov equation is solved in the coordinate space and the proton-neutron Quasiparticle-RPA equation is solved in the quasiparticle basis. It is found that a stronger collectivity is generated for the GT giant resonance as an increase in the neutron number. Furthermore, we find that the T = 0 pairing enhances the low-lying GT strengths cooperatively with the T = 1 pairing correlation depending on the microscopic structure of the low-lying mode and the shell structure around the Fermi levels, and that the enhanced strength shortens the β-decay half-lives by at most an order of magnitude.

  17. Shape phase transition in odd-even nuclei: From spherical to deformed gamma-unstable shapes

    SciTech Connect

    Boeyuekata, M.; Alonso, C. E.; Arias, J. M.; Fortunato, L.; Vitturi, A.

    2010-07-15

    Shape phase transitions in odd-A nuclei are investigated within the framework of the interacting boson-fermion model. The case of a single j=9/2 fermion coupled to an even-even boson core is considered. This boson core transits from spherical to gamma-unstable shapes depending on the value of a control parameter in the boson Hamiltonian. The effect of the coupling of the odd particle to this core along the shape transition and, in particular, at the critical point is discussed. For that purpose, the ground-state energy surface in terms of the beta and gamma shape variables for the even core and odd-even energy surfaces for the different K states coming from j=9/2 are constructed. The evolution of each individual coupled state along the transition from the spherical [U(5)] to the gamma-unstable [O(6)] situation is investigated. One finds that the core-fermion coupling gives rise to a smoother transition than in the even-core case.

  18. β-Decay half-lives and nuclear structure of exotic proton-rich waiting point nuclei under rp-process conditions

    NASA Astrophysics Data System (ADS)

    Nabi, Jameel-Un; Böyükata, Mahmut

    2016-03-01

    We investigate even-even nuclei in the A ∼ 70 mass region within the framework of the proton-neutron quasi-particle random phase approximation (pn-QRPA) and the interacting boson model-1 (IBM-1). Our work includes calculation of the energy spectra and the potential energy surfaces V (β , γ) of Zn, Ge, Se, Kr and Sr nuclei with the same proton and neutron number, N = Z. The parametrization of the IBM-1 Hamiltonian was performed for the calculation of the energy levels in the ground state bands. Geometric shape of the nuclei was predicted by plotting the potential energy surfaces V (β , γ) obtained from the IBM-1 Hamiltonian in the classical limit. The pn-QRPA model was later used to compute half-lives of the neutron-deficient nuclei which were found to be in very good agreement with the measured ones. The pn-QRPA model was also used to calculate the Gamow-Teller strength distributions and was found to be in decent agreement with the measured data. We further calculate the electron capture and positron decay rates for these N = Z waiting point (WP) nuclei in the stellar environment employing the pn-QRPA model. For the rp-process conditions, our total weak rates are within a factor two compared with the Skyrme HF +BCS +QRPA calculation. All calculated electron capture rates are comparable to the competing positron decay rates under rp-process conditions. Our study confirms the finding that electron capture rates form an integral part of the weak rates under rp-process conditions and should not be neglected in the nuclear network calculations.

  19. Evolution of Structure in Nuclei: Meditation by Sub-Shell Modifications and Relation to Binding Energies

    NASA Astrophysics Data System (ADS)

    Casten, R. F.; Cakirli, R. B.

    2009-03-01

    Understanding the development of configuration mixing, coherence, collectivity, and deformation in nuclei is one of the crucial challenges in nuclear structure physics, and one which has become all the more important with the advent of next generation facilities for the study of exotic nuclei. We will discuss recent work on phase/shape transitional behavior in nuclei, and the role of changes in sub-shell structure in mediating such transitional regions. We will also discuss a newly found, much deeper, link between nuclear structure and nuclear binding energies.

  20. QPNM calculation for the ground state magnetic moments of odd-mass deformed nuclei: 157-167Er isotopes

    NASA Astrophysics Data System (ADS)

    Yakut, H.; Guliyev, E.; Guner, M.; Tabar, E.; Zenginerler, Z.

    2012-08-01

    A new microscopic method has been developed in the framework of the Quasiparticle-Phonon Nuclear Model (QPNM) in order to investigate spin polarization effects on the magnetic properties such as magnetic moment, intrinsic magnetic moment and effective gs factor of the ground state of odd-mass 157-167Er isotopes. The calculations were performed using both Tamm-Dancoff Approximation (TDA) and Quasiparticle Random-Phase Approximation (QRPA). Reasonably good agreement has been obtained between the QRPA results and the relevant experimental data. Furthermore the variation of the intrinsic magnetic moment gK values with the mass number A exhibits similar behavior for both theoretical and experimental results. From the compression of the calculated intrinsic magnetic moment values with the experimental data the spin-spin interaction parameter has been found as χ=(30/A) MeV for odd-mass 157-167Er isotopes. Our results clarify the possibility of using this new method to describe the magnetic properties of odd-mass deformed nuclei.

  1. New Measurements of Reaction Cross Sections and Reduced Strong Absorption Radii of Neutron-Rich Exotic Nuclei in the Vicinity of Closed Shells N=20 and N=28

    NASA Astrophysics Data System (ADS)

    Khouaja, A.; Villari, A. C. C.; Benjelloun, M.; Hirata, D.; Savajols; Mittig, W.; Roussel-Chomaz, P.; Orr, N. A.; Pita, S.; Demonchy, C. E.; Giot, L.; Chartier, M.; Gillibert, A.; Baiborodin, D.; Penionzhkevich, Y.; Catford, W. N.; Lépine-Szily, A.; Dlouhy, Z.

    2005-09-01

    Mean energy integrated reaction cross-section measurements for various neutron-rich nuclei covering the region of closed shells N=20 and N=28 were performed, at intermediate energy (30 - 65 A.MeV), via direct method, where the Silicon detectors are used as an active target. Assuming that the energy dependence of the reaction cross-section is well described by the parametrization of S.Kox, the reduced strong absorption radius r02 is extracted for the first time, for 19 new nuclei, i.e. 27F, 27,30Ne, 33Na, 28,34-35Mg, 36-38Al, 38-40Si, 41-42P, 42-44S, 45Cl. Other 60 radii also measured in this experiment are compared to results from literature. The evolution of the reduced strong absorption radius is studied as a function of the neutrons excess. A new quadratic parametrization is therefore proposed for the nuclear radius as a function of the isospin in the region of closed shells N=8 and N=28. According to this parametrization, the skin effect is well reproduced and anomalous behaviours are observed to the nuclei 23N, 29Ne, 33Na, 35Mg, 44S, 45Cl and 45Ar.

  2. Microscopic study of a {ital C}{sub 4}-symmetry hypothesis in {ital A}{similar_to}150 superdeformed nuclei: Deformed Woods-Saxon mean field

    SciTech Connect

    Luo, W.D.; Bouguettoucha, A.; Dobaczewski, J.; Dudek, J.; Li, X.

    1995-12-01

    Microscopic analysis of the quantum (shell) effects related to the presence of the hexadecapole ({ital Y}{sub 4{mu}}; {mu}=0,2,4) components in the nuclear mean field is performed for the superdeformed nuclei in the mass {ital A} {similar_to} 150 region using the deformed Woods-Saxon potential. No shell effects favoring the {ital C}{sub 4}-symmetry are found. The calculations indicate, however, the existence of the {alpha}{sub 44}-deformation driving orbitals whose occupation might induce an {alpha}{sub 44}-polarization effect. For {sup 149}Gd and {sup 153}Dy nuclei, in which the existence of the {ital C}{sub 4}-symmetry effects is suspected, properties of several excited particle-hole configuration are analyzed.

  3. Band-head spectra of low-energy single-particle excitations in some well-deformed, odd-mass heavy nuclei within a microscopic approach

    NASA Astrophysics Data System (ADS)

    Koh, Meng-Hock; Duy Duc, Dao; Nhan Hao, T. V.; Thuy Long, Ha; Quentin, P.; Bonneau, L.

    2016-01-01

    In four well-deformed heavy odd nuclei, the energies of low-lying rotational band heads have been determined microscopically within a self-consistent Hartree-Fock-plus-BCS approach with blocking. A Skyrme nucleon-nucleon effective interaction has been used together with a seniority force to describe pairing correlations. Only such states which are phenomenologically deemed to be related to single-particle excitations have been considered. The polarization effects, including those associated with the genuine time-reversal symmetry breaking have been fully taken into account within our model assumptions. The calculated spectra are in reasonably good qualitative agreement with available data for the considered odd-neutron nuclei. This is not so much the case for the odd-proton nuclei. A potential explanation for such a difference in behavior is proposed.

  4. Effective theory for the nonrigid rotor in an electromagnetic field: Toward accurate and precise calculations of E2 transitions in deformed nuclei

    SciTech Connect

    Coello Pérez, Eduardo A.; Papenbrock, Thomas F.

    2015-07-27

    In this paper, we present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant nonminimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoretical uncertainties at leading order. To probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading-order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. In addition, we study the faint interband transitions within the effective theory and focus on the E2 transitions from the 02+ band (the “β band”) to the ground-state band. Here the predictions from the effective theory are consistent with data for several nuclei, thereby proposing a solution to a long-standing challenge.

  5. Effective theory for the nonrigid rotor in an electromagnetic field: Toward accurate and precise calculations of E2 transitions in deformed nuclei

    DOE PAGESBeta

    Coello Pérez, Eduardo A.; Papenbrock, Thomas F.

    2015-07-27

    In this paper, we present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant nonminimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoreticalmore » uncertainties at leading order. To probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading-order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. In addition, we study the faint interband transitions within the effective theory and focus on the E2 transitions from the 02+ band (the “β band”) to the ground-state band. Here the predictions from the effective theory are consistent with data for several nuclei, thereby proposing a solution to a long-standing challenge.« less

  6. Remnants of spherical shell structures in deformed nuclei: The impact of an N=64 neutron subshell closure on the structure of N~90 gadolinium nuclei

    SciTech Connect

    Ross, T.J.; Hughes, R.O.; Beausang, C.W.; Allmond, James M; Angell, C.T.; Basunia, M.S.; Bleuel, D.L.; Burke, J.T.; Casperson, R.J.; Escher, J.E.; Fallon, P.; Hatarik, R.; Munson, J.; Paschalis, S.; Petri, M.; Phair, L.; Ressler, J.J.; Scielzo, N.D.

    2013-01-01

    Odd-mass gadolinium isotopes around N = 90 were populated by the (p,d ) reaction, utilizing 25-MeV protons, resulting in population of low-spin quasineutron states at energies near and below the Fermi surface. Systematics of the single quasineutron levels populated are presented. A large excitation energy gap is observed between levels originating from the 2d3/2 , 1h11/2 , and 3s1/2 spherical parents (above the N = 64 gap), and the 2d5/2 (below the gap), indicating that the spherical shell model level spacing is maintained at least to moderate deformations.

  7. Microscopic time-dependent analysis of neutrons transfers at low-energy nuclear reactions with spherical and deformed nuclei

    NASA Astrophysics Data System (ADS)

    Samarin, Viacheslav

    2014-03-01

    Time-dependent Schrödinger equation is numerically solved by difference method for external neutrons of nuclei 6He, 18O, 48Са, 238U at their grazing collisions with energies in the vicinity of a Coulomb barrier. The spin-orbital interaction and Pauli's exclusion principle were taken into consideration during the solution.

  8. Rules governing the composition of revolving clusters in quasiband and prolate-deformation states of atomic nuclei.

    PubMed

    Pauling, L

    1982-11-01

    A set of rules, involving the magic and semimagic values of neutron and proton numbers and the proton/neutron ratio, is formulated for the composition of the revolving clusters producing the values of the moment of inertia given by the differences in energy of the adjacent levels in quasibands and bands of nuclei. The cluster compositions assigned with use of these rules to isotopes of Kr, Sr, Zr, Mo, and the actinon nuclei and to successive levels of the ground-state band of (158)Er lead to reasonable values of the radius of revolution (the distance from the center of the nonrevolving sphere to the center of the cluster). These values correspond to a spheron diameter of about 3.20 fm. PMID:16593256

  9. Deformed ODD-ODD nuclei: Matrix elements for the residual n-p interaction and patterns of alternating perturbations in level spacings

    SciTech Connect

    Hoff, R.W.; Jain, A.K.; Kvasil, J.; Sood, P.C.; Sheline, R.K.; Florida State Univ., Tallahassee, FL )

    1989-09-01

    The application of a simple semi-empirical model is discussed in terms of interpreting experimental nuclear structure data for twelve of the best characterized odd-odd deformed nuclei. An essential part of this modeling is to calculate values for the Gallagher-Moszkowski splittings and Newby shifts, the observables that arise from the n-p residual interaction in odd-odd nuclei. Assumptions regarding the form for this n-p force are traced historically. The predictive power of a favored form of the n-p force, one that includes a central force with short and long-range components, a tensor force, and some effects of core polarization, is examined in light of experimental data obtained since its formulation. A data set of 42 experimentally determined Newby shifts has been reviewed as to the reliability of each entry. Exceptions to a recently proposed rule for the a priori determination of the sign of Newby shift are discussed. Evidence is presented for the existence of an odd-even staggering or signature effect in the rotational spacings of many K{sup {minus}} bands (with K > 0). By use of Coriolis-coupling calculations, it has been possible to reproduce the staggering observed in some of the K{sup {minus}} rotational bands of {sup 156}Tb, {sup 168}Tm, {sup 176}Lu, {sup 182}Ta, and {sup 182}Re. 27 refs., 3 figs., 3 tabs.

  10. Probing the maximally deformed light rare-earth region around the drip-line nucleus 130Sm

    NASA Astrophysics Data System (ADS)

    Petri, M.; Paul, E. S.; Nolan, P. J.; Boston, A. J.; Cooper, R. J.; Dimmock, M. R.; Gros, S.; McGuirk, B. M.; Scraggs, H. C.; Turk, G.; Rossé, B.; Meyer, M.; Redon, N.; Schmitt, Ch; Stézowski, O.; Guinet, D.; Lautesse, Ph; DeFrance, G.; Bhattachasyya, S.; Mukherjee, G.; Rejmund, F.; Rejmund, M.; Savajols, H.; Scheurer, J. N.; Astier, A.; Deloncle, I.; Prévost, A.; Nyakó, B. M.; Gál, J.; Molnár, J.; Timár, J.; Zolnai, L.; Juhász, K.; Pucknell, V. F. E.; Wadsworth, R.; Joshi, P.; La Rana, G.; Moro, R.; Trotta, M.; Vardaci, E.; Hackman, G.; Ball, G.

    2006-07-01

    The neutron deficient rare-earth nuclei of the A~130 region are of particular interest since highly deformed prolate ground states are expected. Indeed these nuclei are predicted to show maximal ground-state deformations of β2 ~ 0.40 (axis ratio of 3:2), comparable to the deformation deduced for superdeformed cerium isotopes at high spin. A fusion-evaporation experiment was performed with radioactive ion beams at GANIL in October 2004 which had the goal to reach very proton-rich exotic nuclei located near the proton drip-line. A radioactive 76Kr beam, delivered by the SPIRAL facility, was used to bombard a thin 58Ni target. Emitted γ-rays were detected by the EXOGAM γ-ray spectrometer which was, for the first time, coupled with both the DIAMANT charged-particle array and the VAMOS spectrometer.

  11. Description of superdeformed nuclei in the A{approx}190 region by generalized deformed su{sub q}(2)

    SciTech Connect

    Alharbi, H. H.; Alhendi, H. A.; Alhakami, F. S.

    2009-05-15

    The generalized deformed su{sub q}(2) model is applied to 79 superdeformed bands in the region A{approx}190. The transition energies and the moments of inertia are calculated within the model and their validity is investigated by comparing them with the experimental data. Both the standard su{sub q}(2) and the generalized one fail to account for the uprising and the downturn of the dynamic moments of inertia. Both models, however, show remarkable agreement with the available experimental data at low angular frequency (({Dirac_h}/2{pi}){omega}{<=}0.25 MeV)

  12. Nonaxial-octupole effect in superheavy nuclei

    SciTech Connect

    Chen, Y.-S.; Sun, Yang; Gao Zaochun

    2008-06-15

    The triaxial-octupole Y{sub 32} correlation in atomic nuclei has long been expected to exist but experimental evidence has not been clear. We find, in order to explain the very low-lying 2{sup -} bands in the transfermium mass region, that this exotic effect may manifest itself in superheavy elements. Favorable conditions for producing triaxial-octupole correlations are shown to be present in the deformed single-particle spectrum, which is further supported by quantitative Reflection Asymmetric Shell Model calculations. It is predicted that the strong nonaxial-octupole effect may persist up to the element 108. Our result thus represents the first concrete example of spontaneous breaking of both axial and reflection symmetries in the heaviest nuclear systems.

  13. Light exotic systems at relativistic velocities

    NASA Astrophysics Data System (ADS)

    Simon, H.

    2010-03-01

    In this paper the results of a series of experiments, carried out at the GSI accelerator facilities in Darmstadt at the Aladin-LAND reaction setup are presented. Light nuclei at relativistic velocities, impinging on a carbon and a liquid hydrogen reaction target break up and all fragments are detected in coincidence. The observed correlations are used to draw conclusions on the underlying structure of the bound exotic projectiles as well as to explore continuum structures.

  14. Exotic structures near the drip lines

    SciTech Connect

    Sharma, M. M.; Saldanha, A. A.; Sharma, J. K.

    2011-10-28

    In our recent study of the isotope shifts of Kr isotopes near rp-process path in the framework of the RMF theory, we have found that due to large shell gaps in the deformed space, several N = Z nuclei exhibit the double magicity of protons and neutrons. These nuclei are known to contribute to large abundances in the rp-process nucleosynthesis and have been shown to be the waiting-point nuclei. In another study of the shell effects at N = 126 near the neutron drip line, we have found that nuclei exhibit additional stability beyond the neutron drip line.

  15. Effective Theory for Deformed Nuclei

    SciTech Connect

    Papenbrock, Thomas F

    2011-01-01

    Techniques from effective field theory are applied to nuclear rotation. This approach exploits the spontaneous breaking of rotational symmetry and the separation of scale between low-energy Nambu-Goldstone rotational modes and high-energy vibrational and nucleonic degrees of freedom.

  16. The influence of microscopic structures on rotational motion in nuclei

    NASA Astrophysics Data System (ADS)

    Wadsworth, R.; Nolan, P. J.

    2002-07-01

    This paper will concentrate on a study of the role and influence of microscopic structures on the properties of rotational bands in nuclei. Collective rotational features are well known in nuclei. Much of the review will discuss examples taken from experimental investigations of highly/superdeformed structures and their theoretical interpretation, which provide some of best and clearest rotational phenomena observed in nuclei. These structures have well-defined rotational properties that can be described by a collective model. The link between the deformation of these structures and the valence particle configuration has been established in many nuclei and recent experimental data are presented. Detailed investigations with new, very sensitive, instrumentation have revealed some extremely interesting and unexpected phenomena, such as the observation of identical rotational bands in neighbouring nuclei and energy staggering between adjacent states within a single band. The experimental and theoretical aspects of these new features will be discussed. The spectroscopy of highly/superdeformed structures has been studied extensively and many bands observed in a given nucleus which arise from particle-hole excitations. Measurements are now available, through the strength of magnetic dipole transitions, of the properties of specific single-particle orbitals. In the medium mass (A~60) region highly deformed states have been observed to decay by both proton and alpha emission in addition to the normal γ-decay mode. The decay widths, which are retarded for these channels, are related to the microscopic structures of the states involved. Investigations of rotational motion in exotic triaxial and hyperdeformed nuclear shapes are also reviewed. Recent work on `smooth band termination', in medium to medium-heavy nuclei, which results when a deformed collectively rotating nucleus gradually changes from a near-prolate to a non-collective oblate shape, has revealed detailed

  17. Deformed shell model calculations of half lives for β+/EC decay and 2ν β+β+/β+EC/ECEC decay in medium-heavy N~Z nuclei

    NASA Astrophysics Data System (ADS)

    Mishra, S.; Shukla, A.; Sahu, R.; Kota, V. K. B.

    2008-08-01

    The β+/EC half-lives of medium heavy N~Z nuclei with mass number A~64-80 are calculated within the deformed shell model (DSM) based on Hartree-Fock states by employing a modified Kuo interaction in (2p3/2,1f5/2,2p1/2,1g9/2) space. The DSM model has been quite successful in predicting many spectroscopic properties of N~Z medium heavy nuclei with A~64-80. The calculated β+/EC half-lives, for prolate and oblate shapes, compare well with the predictions of the calculations with Skyrme force by Sarriguren Going further, following recent searches, half-lives for 2ν β+β+/β+EC/ECEC decay for the nucleus Kr78 are calculated using DSM and the results compare well with QRPA predictions.

  18. Structure of unstable nuclei around N = 28 described by a shell model with the monopole-based universal interaction

    SciTech Connect

    Utsuno, Yutaka; Otsuka, Takaharu; Brown, B. Alex; Honma, Michio; Mizusaki, Takahiro

    2011-05-06

    The structure of exotic nuclei around N = 28 is investigated in the sd-pf shell-model space using a new effective interaction. The cross-shell part of the interaction is provided by the monopole-based universal interaction which has been successful in accounting for single-particle evolution in several mass regions. Focusing on the nuclear structure that is sensitive to the shell evolution, we show successful results for the proton-hole states in K isotopes and large deformation in {sup 42}Si. The results demonstrate that the present scheme may be a promising way for constructing an effective interaction for other mass regions.

  19. Nuclear spectroscopy in nuclei with Z ≥ 110

    NASA Astrophysics Data System (ADS)

    Ackermann, D.

    2015-12-01

    The nuclear structure of species at the extreme of highest atomic numbers Z and nuclear masses A promises to reveal intriguing new features of this exotic hadronic matter. Their stability itself they owe to quantum-mechanic effects only. They form metastable states which, governed by the subtle interplay of α decay and spontaneous fission versus quantum-mechanic stabilization via shell effects, are in some cases more robust against disintegration than their ground states. Following the isotopic and isotonic trends of single particle levels, as well as collective features like deformation, may reveal the path towards the gap in the level densities, expected for the next closed proton and neutron shells at the so-called "island of stability" of spherical superheavy nuclei. Their atomic configuration offers via X-ray spectroscopy a tool to identify the atomic number of heavy species, where other more traditional methods like evaporation residue (ER)-α correlation are not applicable.

  20. Exotic nonrelativistic string

    SciTech Connect

    Casalbuoni, Roberto; Gomis, Joaquim; Longhi, Giorgio

    2007-12-15

    We construct a classical nonrelativistic string model in 3+1 dimensions. The model contains a spurion tensor field that is responsible for the noncommutative structure of the model. Under double-dimensional reduction the model reduces to the exotic nonrelativistic particle in 2+1 dimensions.

  1. Exotic branes and nongeometric backgrounds.

    PubMed

    de Boer, Jan; Shigemori, Masaki

    2010-06-25

    When string or M theory is compactified to lower dimensions, the U-duality symmetry predicts so-called exotic branes whose higher-dimensional origin cannot be explained by the standard string or M-theory branes. We argue that exotic branes can be understood in higher dimensions as nongeometric backgrounds or U folds, and that they are important for the physics of systems which originally contain no exotic charges, since the supertube effect generically produces such exotic charges. We discuss the implications of exotic backgrounds for black hole microstate (non-)geometries. PMID:20867363

  2. Superheavy nuclei and fission barriers

    NASA Astrophysics Data System (ADS)

    Lu, Bing-Nan; Zhao, Jie; Zhao, En-Guang; Zhou, Shan-Gui

    In this chapter, we will present relativistic mean field (RMF) description of heavy and superheavy nuclei (SHN). We will discuss the shell structure and magic numbers in the mass region of SHN, binding energies and α decay Q values, shapes of ground states and potential energy surfaces and fission barriers. We particularly focus on the multidimensionally-constrained covariant density functional theories (CDFT) and the applications of CDFT to the study of exotic nuclear shapes and fission barriers.

  3. Promoting the exotic pet practice.

    PubMed

    Harris, Don J

    2005-09-01

    The marketing and promotion of an exotic pet veterinary practice allows the use of strategies that are not necessarily available in other veterinary disciplines. The advantage that an exotics practice enjoys is that it is able to capitalize not only on the unique nature of the species being attended but also on the specialized features of the hospital itself that make it specifically appropriate in caring for exotic pets. Before marketing, however, comes the responsibility that the practice live up to the claims made in promotional materials. A practice cannot ethically be presented as an "exotics" practice if it is nothing more than a dog and cat facility that is willing to attend to exotic pets. It is the competence of the veterinary staff and the appropriateness of the facility that determines the suitability of the practice for exotics management. PMID:16129354

  4. Superdeformed oblate superheavy nuclei

    SciTech Connect

    Jachimowicz, P.; Kowal, M.; Skalski, J.

    2011-05-15

    We study stability of superdeformed oblate (SDO) superheavy Z{>=}120 nuclei predicted by systematic microscopic-macroscopic calculations in 12D deformation space and confirmed by the Hartree-Fock calculations with the SLy6 force. We include into consideration high-K isomers that very likely form at the SDO shape. Although half-lives T{sub 1/2} < or approx. 10{sup -5} s are calculated or estimated for even-even spin-zero systems, decay hindrances known for high-K isomers suggest that some SDO superheavy nuclei may be detectable by the present experimental technique.

  5. Deformation of the very neutron-deficient rare-earth nuclei produced with the SPIRAL 76Kr radioactive beam and studied with EXOGAM + DIAMANT

    NASA Astrophysics Data System (ADS)

    Redon, N.; Prévost, A.; Guinet, D.; Lautesse, Ph.; Meyer, M.; Rossé, B.; Stézowski, O.; Nolan, P. J.; Andreoiu, C.; Boston, A. J.; Descovich, M.; Evans, A. O.; Gros, S.; Norman, J.; Page, R. D.; Paul, E. S.; Rainovski, G.; Sampson, J.; de France, G.; Casandjian, J. M.; Theisen, Ch.; Scheurer, J. N.; Nyakó, B. M.; Gál, J.; Kalinka, G.; Molnár, J.; Dombrádi, Zs.; Timár, J.; Zolnai, L.; Juhász, K.; Astier, A.; Deloncle, I.; Porquet, M. G.; Wadsworth, R.; Raddon, P.; Lee, Y.; Wilkinson, A.; Joshi, P.; Simpson, J.; Appelbe, D.; Joss, D.; Lemmon, R.; Smith, J.; Cullen, D.; Brondi, A.; La Rana, G.; Moro, R.; Vardacci, E.; Girod, M.

    2004-02-01

    The structure of the very neutron-deficient rare-earth nuclei has been investigated in the first experiment with the EXOGAM gamma array coupled to the DIAMANT light charged particle detector using radioactive beam of 76Kr delivered by the SPIRAL facility. Very neutron-deficient Pr, Nd and Pm isotopes have been populated at rather high spin by the reaction 76Kr + 58Ni at a beam energy of 328 MeV. We report here the first results of this experiment.

  6. Deformation of the very neutron-deficient rare-earth nuclei produced with the SPIRAL 76Kr radioactive beam and studied with EXOGAM + DIAMANT

    SciTech Connect

    Redon, N.; Guinet, D.; Lautesse, Ph.; Meyer, M.; Rosse, B.; Stezowski, O.; France, G. de; Casandjian, J. M.

    2004-02-27

    The structure of the very neutron-deficient rare-earth nuclei has been investigated in the first experiment with the EXOGAM gamma array coupled to the DIAMANT light charged particle detector using radioactive beam of 76Kr delivered by the SPIRAL facility. Very neutron-deficient Pr, Nd and Pm isotopes have been populated at rather high spin by the reaction 76Kr + 58Ni at a beam energy of 328 MeV. We report here the first results of this experiment.

  7. Current Status of Exotic Hadrons

    SciTech Connect

    Saeed, M.A.; Ahmed, Maqsood; Fazal-e-Aleem

    2005-03-17

    Physics of exotic hadrons is in the limelight these days. The models for these baryons are discussed as well as their production and decay processes and methods of their identification. The results of recent experiments in this field are presented, in which some unusual states are observed. These states are candidates for exotic hadrons.

  8. Coupled-cluster computations of atomic nuclei.

    PubMed

    Hagen, G; Papenbrock, T; Hjorth-Jensen, M; Dean, D J

    2014-09-01

    In the past decade, coupled-cluster theory has seen a renaissance in nuclear physics, with computations of neutron-rich and medium-mass nuclei. The method is efficient for nuclei with product-state references, and it describes many aspects of weakly bound and unbound nuclei. This report reviews the technical and conceptual developments of this method in nuclear physics, and the results of coupled-cluster calculations for nucleonic matter, and for exotic isotopes of helium, oxygen, calcium, and some of their neighbors. PMID:25222372

  9. Exotic States of Nuclear Matter

    NASA Astrophysics Data System (ADS)

    Lombardo, Umberto; Baldo, Marcello; Burgio, Fiorella; Schulze, Hans-Josef

    2008-02-01

    pt. A. Theory of nuclear matter EOS and symmetry energy. Constraining the nuclear equation of state from astrophysics and heavy ion reactions / C. Fuchs. In-medium hadronic interactions and the nuclear equation of state / F. Sammarruca. EOS and single-particle properties of isospin-asymmetric nuclear matter within the Brueckner theory / W. Zuo, U. Lombardo & H.-J. Schulze. Thermodynamics of correlated nuclear matter / A. Polls ... [et al.]. The validity of the LOCV formalism and neutron star properties / H. R. Moshfegh ... [et al.]. Ferromagnetic instabilities of neutron matter: microscopic versus phenomenological approaches / I. Vidaã. Sigma meson and nuclear matter saturation / A. B. Santra & U. Lombardo. Ramifications of the nuclear symmetry energy for neutron stars, nuclei and heavy-ion collisions / A. W. Steiner, B.-A. Li & M. Prakash. The symmetry energy in nuclei and nuclear matter / A. E. L. Dieperink. Probing the symmetry energy at supra-saturation densities / M. Di Toro et al. Investigation of low-density symmetry energy via nucleon and fragment observables / H. H. Wolter et al. Instability against cluster formation in nuclear and compact-star matter / C. Ducoin ... [et al.]. Microscopic optical potentials of nucleon-nucleus and nucleus-nucleus scattering / Z.-Y. Ma, J. Rong & Y.-Q. Ma -- pt. B. The neutron star crust: structure, formation and dynamics. Neutron star crust beyond the Wigner-Seitz approximation / N. Chamel. The inner crust of a neutron star within the Wigner-Seitz method with pairing: from drip point to the bottom / E. E. Saperstein, M. Baldo & S. V. Tolokonnikov. Nuclear superfluidity and thermal properties of neutron stars / N. Sandulescu. Collective excitations: from exotic nuclei to the crust of neutron stars / E. Khan, M. Grasso & J. Margueron. Monte Carlo simulation of the nuclear medium: fermi gases, nuclei and the role of Pauli potentials / M. A. Pérez-García. Low-density instabilities in relativistic hadronic models / C. Provid

  10. Heavy quark in exotic hadron and nuclear systems

    NASA Astrophysics Data System (ADS)

    Yasui, Shigehiro

    2014-09-01

    In recent years, it has turned out that heavy hadrons with charm and bottom flavors have rich structures, which are different from simple quark-antiquark or three-quark systems. The new states of heavy hadrons are called exotic hadrons X, Y and Z. The subjects are now covering not only exotic hadrons but also exotic ``nuclei'' in which heavy hadrons are bound. The purpose of the presentation is to discuss the general properties of exotic states of hadrons and nuclei with heavy quarks. We begin our discussion by the heavy quark spin (HQS) symmetry in the heavy quark limit, and show that all heavy hadrons are classified by the HQS symmetry, i.e. either HQS singlet or doublet. Next, in order to discuss the long-range physics of exotic hadrons, we introduce the heavy hadron effective theory according to the HQS symmetry in heavy quark sector as well as by chiral symmetry in light quark sector. As examples, we investigate the theoretically possible states of hadronic molecules with an anti-D meson (B meson) and nucleons with baryon number one, two and infinity (i.e. nuclear matter). Calculating the energies, we show that many of them exhibit the HQS doublets. Beyond the leading order in heavy quark limit, we further discuss the 1/M corrections with heavy hadron mass M, and show that finding the HQS-breaking (non-breaking) terms at 1/M is important to investigate the magnetic (electric) gluons in the heavy hadrons in nuclear medium [1,5]. In recent years, it has turned out that heavy hadrons with charm and bottom flavors have rich structures, which are different from simple quark-antiquark or three-quark systems. The new states of heavy hadrons are called exotic hadrons X, Y and Z. The subjects are now covering not only exotic hadrons but also exotic ``nuclei'' in which heavy hadrons are bound. The purpose of the presentation is to discuss the general properties of exotic states of hadrons and nuclei with heavy quarks. We begin our discussion by the heavy quark spin (HQS

  11. Octupole shapes in heavy nuclei

    SciTech Connect

    Ahmad, I.

    1994-08-01

    Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets.

  12. Exotic Bbb R4 and quantum field theory

    NASA Astrophysics Data System (ADS)

    Asselmeyer-Maluga, Torsten; Mader, Roland

    2012-02-01

    Recent work on exotic smooth Bbb R4,s, i.e. topological Bbb R4 with exotic differential structure, shows the connection of 4-exotics with the codimension-1 foliations of S3, SU(2) WZW models and twisted K-theory KH(S3), H in H3(S3,Bbb Z). These results made it possible to explicate some physical effects of exotic 4-smoothness. Here we present a relation between exotic smooth Bbb R4 and operator algebras. The correspondence uses the leaf space of the codimension-1 foliation of S3 inducing a von Neumann algebra W(S3) as description. This algebra is a type III1 factor lying at the heart of any observable algebra of QFT. By using the relation to factor II, we showed that the algebra W(S3) can be interpreted as Drinfeld-Turaev deformation quantization of the space of flat SL(2, Bbb C) connections (or holonomies). Thus, we obtain a natural relation to quantum field theory. Finally we discuss the appearance of concrete action functionals for fermions or gauge fields and its connection to quantum-field-theoretical models like the Tree QFT of Rivasseau.

  13. Exotics from Heavy Ion Collisions

    SciTech Connect

    Ohnishi, Akira; Jido, Daisuke; Cho, Sungtae; Furumoto, Takenori; Yazaki, Koichi; Hyodo, Tetsuo; Ko, Che Ming; Lee, Su Houng; Nielsen, Marina; Sekihara, Takayasu; Yasui, Shigehiro

    2011-10-21

    Discriminating hadronic molecular and multi-quark states is a long standing problem in hadronic physics. We propose here to utilize relativistic heavy ion collisions to resolve this problem, as exotic hadron yields are expected to be strongly affected by their structures. Using the coalescence model, we find that the exotic hadron yield relative to the statistical model result is typically an order of magnitude smaller for a compact multi-quark state, and larger by a factor of two or more for a loosely bound hadronic molecule. We further find that some of the newly proposed heavy exotic states could be produced and realistically measured at RHIC and LHC.

  14. Recent astrophysical studies with exotic beams at ORNL

    NASA Astrophysics Data System (ADS)

    Bardayan, D. W.

    2006-03-01

    The availability of exotic beams has produced great opportunities for advances in our understanding of the nucleosynthesis occurring in stellar burning and stellar explosions such as novae, X-ray bursts, and supernovae. In these extreme environments, synthesized radioactive nuclei can undergo subsequent nuclear processing before they decay, and thus to understand these events, we must understand reaction rates involving radioactive nuclei. At the ORNL Holifield Radioactive Ion Beam Facility (HRIBF), we have made a number of measurements using proton-rich beams such as 18F and 7Be and neutron-rich beams such as 82Ge and 84Se that help clarify the structure of astrophysically-important nuclei. We are also poised to begin studies with doubly-magic 132Sn. The experimental methods and results are discussed.

  15. Recent Astrophysical Studies with Exotic Beams at ORNL

    SciTech Connect

    Bardayan, Daniel W

    2006-02-01

    The availability of exotic beams has produced great opportunities for advances in our understanding of the nucleosynthesis occurring in stellar burning and stellar explosions such as novae, X-ray bursts, and supernovae. In these extreme environments, synthesized radioactive nuclei can undergo subsequent nuclear processing before they decay, and thus to understand these events, we must understand reaction rates involving radioactive nuclei. At the ORNL Holi led Radioactive Ion Beam Facility (HRIBF), we have made several recent measurements using proton-rich beams such as 18F and 7Be and neutron-rich beams such as 82Ge and 84Se that help clarify the structure of astrophysically-important nuclei. We are also poised to begin studies with doubly-magic 132Sn. The experimental methods and results are discussed.

  16. Material Research Using Moessbauer Spectroscopy With Exotic Nuclei

    SciTech Connect

    Kobayashi, Y.

    2009-05-04

    We have succeeded to obtain in-beam Moessbauer spectra using a short-lived {sup 57}Mn (T{sub 1/2} = 1.45 min) probes implanted into some different types of samples, in order to study the chemical states of the excited atoms produced just after nuclear decays and/or the dynamic behaviors of isolated single atoms in a semiconductor. {sup 57}Mn was produced as a radioactive beam following a nuclear projectile-fragmentation reaction of {sup 58}Fe{sup 21+} beams (E = 63 MeV/nucleon) with Be production target, and separated by the in-flight isotope separator at the accelerators in RIKEN Nishina Center. From the temperature dependence of obtained Moessbauer parameters of the isomer shift (I.S.), the quadrupole splitting (Q.S.), and the linewidth (I), the chemical species and the dynamic behavior of the isolated atoms could be discussed. The in-beam Moessbauer technique combined with a short-lived RI beam is a very powerful tool to investigate the products after nuclear transformations and the dynamics of dilute impurities in solids.

  17. In-flight decay spectroscopy of exotic light nuclei

    SciTech Connect

    Charity, R. J.

    2012-11-20

    In-flight-decay spectroscopy is discussed, including its advantages and disadvantages. In particular the use of in-flight-decay spectroscopy for the study of two-proton decay along isobaric multiplets in highlighted.

  18. Core transitions in the breakup of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Summers, N. C.; Nunes, F. M.; Thompson, I. J.

    2006-03-01

    An interesting physical process has been unveiled: Dynamical core excitation during a breakup reaction of loosely bound core+N systems. These reactions are typically used to extract spectroscopic information and/or astrophysical information. A new method, the eXtended Continuum Discretized Coupled Channel (XCDCC) method, was developed to incorporate, in a consistent way and to all orders, core excitation in the bound and scattering states of the projectile, as well as dynamical excitation of the core as it interacts with the target. The model predicts cross sections to specific states of the core. It is applied to the breakup of Be11 on Be9 at 60 MeV/nucleon, and the calculated cross sections are in improved agreement with the data. The distribution of the cross section amongst the various core states is shown to depend on the reaction model used, and not simply on the ground state spectroscopic factors.

  19. Exotic structure in light neutron-rich nuclei

    SciTech Connect

    Itagaki, N.; Zhao, P. W.; Meng, J.; Matsuno, H.; Suhara, T.

    2015-10-15

    In this presentation I discussed two subjects. One is the persistence of threefold symmetry in the ground state of {sup 12}C. Recently D{sub 3h} symmetry has been established in {sup 12}C, which reflects the geometric symmetry of the three α particles. Although the spin-orbit interaction plays a significant role and this interaction breaks the α clusters, we show that threefold symmetry of {sup 12}C is still there. We use AQCM approach and discuss that inclusion of spin-orbit interaction, which is absent in the conventional microscopic α cluster models, is possible keeping the threefold symmetry. The second subject is the appearance of rod shape in C isotopes, which has been investigated in the framework of the cranking covariant density functional theory. The relationship between the stability of such states and the spin and isospin degrees of freedom is discussed; adding valence neutrons and rotating the system. These two effects stabilize the rod shape, and in addition, their coherent effect has been found; the σ-orbits (parallel to the symmetry axis) of the valence neutrons, which enhances the rod shape, is lowered by the rotation of the system, and this σ-orbit pulls down the single particle energies of protons with linear configuration owing to the proton-neutron interaction effect.

  20. New Generation of Physics with Exotic Nuclei at RIBF

    SciTech Connect

    Sakurai, H.

    2011-10-28

    I report present status and perspectives of RIBF 'RI Beam Factory (RIBF)' at RIKEN. RIBF is a top world-class in-flight RIB facility. Emphasis is given to on-going and future programs at the new facility through introducing experimental devices and recent highlights.

  1. EXOTIC MAGNETS FOR ACCELERATORS.

    SciTech Connect

    WANDERER, P.

    2005-09-18

    Over the last few years, several novel magnet designs have been introduced to meet the requirements of new, high performance accelerators and beam lines. For example, the FAIR project at GSI requires superconducting magnets ramped at high rates ({approx} 4 T/s) in order to achieve the design intensity. Magnets for the RIA and FAIR projects and for the next generation of LHC interaction regions will need to withstand high doses of radiation. Helical magnets are required to maintain and control the polarization of high energy protons at RHIC. In other cases, novel magnets have been designed in response to limited budgets and space. For example, it is planned to use combined function superconducting magnets for the 50 GeV proton transport line at J-PARC to satisfy both budget and performance requirements. Novel coil winding methods have been developed for short, large aperture magnets such as those used in the insertion region upgrade at BEPC. This paper will highlight the novel features of these exotic magnets.

  2. Super-heavy nuclei

    NASA Astrophysics Data System (ADS)

    Hofmann, Sigurd

    2015-11-01

    Scientifically based searches for elements beyond uranium started after the discovery of the neutron. Neutrons captured by uranium nuclei and subsequent {β }- decay, similarly as most of the elements were produced in nature, was the successful method applied. However, as a first result, Hahn and Strassmann discovered nuclear fission indicating a limit for the existence of nuclei at an increasing number of protons. Eventually, the nuclear shell model allowed for a more accurate calculation of binding energies, half-lives and decay modes of the heaviest nuclei. Theoreticians predicted a region of increased stability at proton number Z = 126, later shifted to 114, and neutron number N = 184. These nuclei receive their stability from closed shells for the protons and neutrons. Later, increased stability was also predicted for deformed nuclei at Z = 108 and N = 162. In this review I will report on experimental work performed on research to produce and identify these super-heavy nuclei (SHN). Intensive heavy ion beams, sophisticated target technology, efficient electromagnetic ion separators, and sensitive detector arrays were the prerequisites for discovery of 12 new elements during the last 40 years. The results are described and compared with theoretical predictions and interpretations. An outlook is given on further improvement of experimental facilities which will be needed for exploration of the extension and structure of the island of SHN, in particular for searching for isotopes with longer half-lives predicted to be located in the south east of the island, for new elements, and last not least, for surprises which, naturally, emerge unexpectedly.

  3. Halo or skin in the excited states of some light mirror nuclei

    NASA Astrophysics Data System (ADS)

    Chen, J. G.; Cai, X. Z.; Shen, W. Q.; Ma, Y. G.; Ren, Z. Z.; Zhang, H. Y.; Jiang, W. Z.; Zhong, C.; Wei, Y. B.; Guo, W.; Zhou, X. F.; Wang, K.; Ma, G. L.

    2005-01-01

    The properties of three pairs of mirror nuclei 13N- 13C, 15N- 15O and 21Na- 21Ne (these mirror nuclei are all made of a good inert core plus an unpaired valence nucleon) are investigated by using the nonlinear relativistic mean-field (RMF) theory. It is found that the calculated binding energies with two different parameter sets are very close to the experimental ones for both the ground states and the excited states except for the large deformed nuclei. The calculations show that the 2 s1/2 excited states of 15N and of 21Na are both weakly bound with a proton halo and a proton skin (or a pigmy proton skin), respectively. In addition, the 1 d5/2 excited state of 13C and the 2 s1/2 excited state of 15O are also weakly bound with a neutron skin, respectively. The ratio of the valence nucleon radius to matter radius is deduced and it can be regarded as an additional criterion for the existence of exotic structure. The unbound 2 s1/2 and 1 d5/2 excited states of 13N are also discussed.

  4. Mapping the deformation in the "island of inversion": Inelastic scattering of 30Ne and 36Mg at intermediate energies

    NASA Astrophysics Data System (ADS)

    Doornenbal, P.; Scheit, H.; Takeuchi, S.; Aoi, N.; Li, K.; Matsushita, M.; Steppenbeck, D.; Wang, H.; Baba, H.; Ideguchi, E.; Kobayashi, N.; Kondo, Y.; Lee, J.; Michimasa, S.; Motobayashi, T.; Poves, A.; Sakurai, H.; Takechi, M.; Togano, Y.; Yoneda, K.

    2016-04-01

    The transition strengths of the first-excited 2+ states and deformation lengths of the nuclei 30Ne and 36Mg were determined via Coulomb- and nuclear-force-dominated inelastic scattering at intermediate energies. Beams of these exotic nuclei were produced at the RIKEN Radioactive Isotope Beam Factory and were incident on lead and carbon targets at energies above 200 MeV/u . Absolute excitation cross sections on the lead target yielded reduced transition probabilities of 0.0277(79) and 0.0528(121) e2b2 , while the measurements with the carbon target revealed nuclear deformation lengths of δN=1.98 (11) and 1.93(11) fm for 30Ne and 36Mg, respectively. Corresponding quadrupole deformation parameters of β2˜0.5 from the two probes were found comparable in magnitude, showing no indication for a reduction in deformation along isotopic and isotonic chains from 32Mg towards the neutron drip-line. Comparisons to shell-model calculations illustrate the importance of neutron excitations across the N =20 shell for 30Ne and suggest that shallow maximums of collectivity may occur around N =22 and 24 along the neon and magnesium isotopic chains, respectively.

  5. Structure of neutron-rich nuclei

    SciTech Connect

    Nazarewicz, W. ||

    1997-11-01

    One of the frontiers of today`s nuclear science is the ``journey to the limits``: of atomic charge and nuclear mass, of neutron-to-proton ratio, and of angular momentum. The new data on exotic nuclei are expected to bring qualitatively new information about the fundamental properties of the nucleonic many-body system, the nature of the nuclear interaction, and nucleonic correlations at various energy-distance scales. In this talk, current developments in nuclear structure of neutron-rich nuclei are discussed from a theoretical perspective.

  6. Multiple muons of conventional and exotic origin in DUMAND

    NASA Technical Reports Server (NTRS)

    Grieder, K. F.

    1985-01-01

    A first summary of results from a theoretical analysis, based on hadron - muon cascade calculations, that yield relative intensities of very high energy multiple muons originating from ultra high energy interactions initiated by primary protons and iron nuclei in the atmosphere, under consideration of normal as well as direct and exotic production channels is presented. Lateral density distributions and target diagrams will be presented which show that only very large detectors, such as DUMAND, will be able to record multiple muons of conventional origin reliably. This, however, is a prerequisite for any primary mass determination based on multiple muon data.

  7. Mirror nuclei constraint in nuclear mass formula

    SciTech Connect

    Wang Ning; Liang Zuoying; Liu Min; Wu, Xizhen

    2010-10-15

    The macroscopic-microscopic mass formula is further improved by considering mirror nuclei constraint. The rms deviation with respect to 2149 measured nuclear masses is reduced to 0.441 MeV. The shell corrections, the deformations of nuclei, the neutron and proton drip lines, and the shell gaps are also investigated to test the model. The rms deviation of {alpha}-decay energies of 46 superheavy nuclei is reduced to 0.263 MeV. The predicted central position of the superheavy island could lie around N=176{approx}178 and Z=116{approx}120 according to the shell corrections of nuclei.

  8. LOUISIANA EXOTIC INVASIVE SPECIES SYMPOSIUM MX964256

    EPA Science Inventory

    The Louisiana Exotic Invasive Species Symposium will provide a multi-state collaboration among agency representatives, scientists, and the affected public to address the problem of exotic invasive species and to improve coastal environmental conditions in Louisiana.

  9. Exotic aphid control with pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Exotic aphids are invading ecosystems worldwide. The principal factors favoring establishment of these pests are their small size, parthenogenetic reproduction, short generation time, ability for long distance dispersal as winged morphs, and explosive population dynamics. In the past, attention to i...

  10. Exotic smoothness and quantum gravity

    NASA Astrophysics Data System (ADS)

    Asselmeyer-Maluga, T.

    2010-08-01

    Since the first work on exotic smoothness in physics, it was folklore to assume a direct influence of exotic smoothness to quantum gravity. Thus, the negative result of Duston (2009 arXiv:0911.4068) was a surprise. A closer look into the semi-classical approach uncovered the implicit assumption of a close connection between geometry and smoothness structure. But both structures, geometry and smoothness, are independent of each other. In this paper we calculate the 'smoothness structure' part of the path integral in quantum gravity assuming that the 'sum over geometries' is already given. For that purpose we use the knot surgery of Fintushel and Stern applied to the class E(n) of elliptic surfaces. We mainly focus our attention to the K3 surfaces E(2). Then we assume that every exotic smoothness structure of the K3 surface can be generated by knot or link surgery in the manner of Fintushel and Stern. The results are applied to the calculation of expectation values. Here we discuss the two observables, volume and Wilson loop, for the construction of an exotic 4-manifold using the knot 52 and the Whitehead link Wh. By using Mostow rigidity, we obtain a topological contribution to the expectation value of the volume. Furthermore, we obtain a justification of area quantization.

  11. Exotic power and propulsion concepts

    NASA Technical Reports Server (NTRS)

    Forward, Robert L.

    1990-01-01

    The status of some exotic physical phenomena and unconventional spacecraft concepts that might produce breakthroughs in power and propulsion in the 21st Century are reviewed. The subjects covered include: electric, nuclear fission, nuclear fusion, antimatter, high energy density materials, metallic hydrogen, laser thermal, solar thermal, solar sail, magnetic sail, and tether propulsion.

  12. SEARCHING FOR EXOTIC SPODOPTERA SPECIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We used sex pheromone-baited traps to collect native and exotic Spodoptera spp. moths at an orchid nursery in Lake County, FL. Lures for S. eridania, exempta, exigua, frugiperda, littoralis, litura, praefica, and Pseudaletia unipuncta were placed in bucket traps that surrounded the greenhouses of t...

  13. Cosmogenic nuclei

    NASA Technical Reports Server (NTRS)

    Raisbeck, G. M.

    1986-01-01

    Cosmogenic nuclei, nuclides formed by nuclear interactions of galactic and solar cosmic rays with extraterrestrial or terrestrial matter are discussed. Long lived radioactive cosmogenic isotopes are focused upon. Their uses in dating, as tracers of the interactions of cosmic rays with matter, and in obtaining information on the variation of primary cosmic ray flux in the past are discussed.

  14. Strong, weak and electromagnetic forces at work in atomic nuclei, decay properties

    NASA Astrophysics Data System (ADS)

    Benzoni, G.

    2016-04-01

    A survey of basic properties of the decay of unstable nuclei is here presented, with a focus on α and β decay. An overview of basic properties and the description of few examples of recently measured decays in exotic nuclei are given in the lecture.

  15. Study of Weakly Bound Nuclei at RIKEN RIBF

    NASA Astrophysics Data System (ADS)

    Motobayashi, Tohru

    2016-05-01

    Recent highlights of studies on unbound exotic nuclei at the RIKEN RI beam factory (RIBF) are presented. They include spectroscopy of nuetron-rich oxygen isotopes ^{26}O and ^{28}O, search for four-neutron states, and studies of proton unbound states of astrophysical interest.

  16. 9 CFR 352.13 - Handling and disposal of condemned or other inedible exotic animal products at official exotic...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... CERTIFICATION EXOTIC ANIMALS AND HORSES; VOLUNTARY INSPECTION Exotic Animals § 352.13 Handling and disposal of condemned or other inedible exotic animal products at official exotic animal establishments. This shall be... other inedible exotic animal products at official exotic animal establishments. 352.13......

  17. 9 CFR 352.13 - Handling and disposal of condemned or other inedible exotic animal products at official exotic...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... CERTIFICATION EXOTIC ANIMALS AND HORSES; VOLUNTARY INSPECTION Exotic Animals § 352.13 Handling and disposal of condemned or other inedible exotic animal products at official exotic animal establishments. This shall be... other inedible exotic animal products at official exotic animal establishments. 352.13......

  18. Onset of deformation in polonium nuclei

    SciTech Connect

    Younes, W.; Cizewski, J.A.

    1996-12-31

    The authors have been able to reproduce the systematics of the positive-parity states in {sup 192-208}Po within the framework of the Particle-Core Model. The wave-functions of the 2{sup +}{sub 1} states have been extracted using the Quasiparticle Random Phase Approximation. The increase in the collective motion of the lighter isotopes comes from the increased proton-neutron interaction when the neutrons and protons both occupy high-j orbitals.

  19. Spatial dependence of pairing in deformed nuclei

    SciTech Connect

    Balbutsev, E. B.; Malov, L. A.; Schuck, P.

    2011-11-15

    The solution of time-dependent Hartree-Fock-Bogoliubov equations by the Wignerfunction-moments method leads to the appearance of refined low-lying modes whose description requires the accurate knowledge of the anomalous density matrix. It is shown that calculations with Woods-Saxon potential satisfy this requirement, producing an anomalous density matrix of the same quality as more complicated calculations with realistic forces.

  20. Study of 0+ States in Deformed Nuclei

    SciTech Connect

    Lesher, S. R.; Ammar, Z.; Merrick, M.; Hannant, C. D.; Boukharouba, N.; McEllistrem, M. T.; Yates, S. W.; Warr, N.; Fransen, C.; Brown, T. B.

    2006-03-13

    In recent 160Gd(p,t) reaction studies the existence of more than ten 0+ states in 158Gd below 3.0 MeV was revealed. We have examined 158Gd with the (n,n'{gamma}) reaction at neutron energies up to 3.5 MeV to confirm the identification of these states and to determine their lifetimes through DSAM measurements. Gamma-ray excitation function and angular distribution measurements have been performed and {gamma} - {gamma} coincidences have been measured with the KEGS array of detectors. Moderately strong decays are observed from some of these 0+ states.

  1. Spin Modes in Nuclei and Nuclear Forces

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshio; Otsuka, Takaharu

    2011-05-01

    Spin modes in stable and unstable exotic nuclei are studied and important roles of tensor and three-body forces on nuclear structure are discussed. New shell model Hamiltonians, which have proper tensor components, are shown to explain shell evolutions toward drip-lines and spin properties of both stable and exotic nuclei, for example, Gamow-Teller transitions in 12C and 14C and an anomalous M1 transition in 17C. The importance and the necessity of the repulsive monopole corrections in isospin T = 1 channel to the microscopic two-body interactions are pointed out. The corrections are shown to lead to the proper shell evolutions in neutron-rich isotopes. The three-body force, in particular the Fujita-Miyazawa force induced by Δ excitations, is pointed out to be responsible for the repulsive corrections among the valence neutrons. The important roles of the three-body force on the energies and transitions in exotic oxygen and calcium isotopes are demonstrated.

  2. Spin Modes in Nuclei and Nuclear Forces

    SciTech Connect

    Suzuki, Toshio; Otsuka, Takaharu

    2011-05-06

    Spin modes in stable and unstable exotic nuclei are studied and important roles of tensor and three-body forces on nuclear structure are discussed. New shell model Hamiltonians, which have proper tensor components, are shown to explain shell evolutions toward drip-lines and spin properties of both stable and exotic nuclei, for example, Gamow-Teller transitions in {sup 12}C and {sup 14}C and an anomalous M1 transition in {sup 17}C. The importance and the necessity of the repulsive monopole corrections in isospin T = 1 channel to the microscopic two-body interactions are pointed out. The corrections are shown to lead to the proper shell evolutions in neutron-rich isotopes. The three-body force, in particular the Fujita-Miyazawa force induced by {Delta} excitations, is pointed out to be responsible for the repulsive corrections among the valence neutrons. The important roles of the three-body force on the energies and transitions in exotic oxygen and calcium isotopes are demonstrated.

  3. Properties of the hypothetical spherical superheavy nuclei

    SciTech Connect

    Smolanczuk, R. |

    1997-08-01

    Theoretical results on the ground-state properties of the hypothetical spherical superheavy atomic nuclei are presented and discussed. Even-even isotopes of elements Z=104{minus}120 are considered. Certain conclusions are also drawn for odd-A and odd-odd superheavy nuclei. Results obtained earlier for even-even deformed superheavy nuclei with Z=104{minus}114 are given for completeness. Equilibrium deformation, nuclear mass, {alpha}-decay energy, {alpha}-decay half-life, dynamical fission barrier, as well as spontaneous-fission half-life are considered. {beta}-stability of superheavy nuclei is also discussed. The calculations are based on the macroscopic-microscopic model. A multidimensional deformation space describing axially symmetric nuclear shapes is used in the analysis of masses and decay properties of superheavy nuclei. We determined the boundaries of the region of superheavy nuclei which are expected to live long enough to be detected after the synthesis in a present-day experimental setup. {copyright} {ital 1997} {ital The American Physical Society}

  4. Exotic Zc states at BESIII

    NASA Astrophysics Data System (ADS)

    Shan, Wei

    2016-05-01

    The BESIII Experiment at the Beijing Electron Positron Collider (BEPC2) collected large data samples for electron-positron collisions with center-of-mass above 4 GeV during 2013 and 2014. In this mass region, there are several states that are yet to be understood. In this article we will discuss BESIII analyses of the exotic Zc states. We present the studies of their decays to hidden charm and open charm final states for both the charged and neutral Zc states.

  5. Exotic containers for capillary surfaces

    NASA Technical Reports Server (NTRS)

    Concus, Paul; Finn, Robert

    1991-01-01

    This paper discusses 'exotic' rotationally symmetric containers that admit an entire continuum of distinct equilibrium capillary free surfaces. The paper extends earlier work to a larger class of parameters and clarifies and simplifies the governing differential equations, while expressing them in a parametric form appropriate for numerical integration. A unified presentation suitable for both zero and nonzero gravity is given. Solutions for the container shapes are depicted graphically along with members of the free-surface continuum, and comments are given concerning possible physical experiments.

  6. From hadrons to nuclei with charm and bottom flavors

    SciTech Connect

    Yasui, S.; Sudoh, K.

    2011-10-21

    We discuss new exotic nuclei which contain D-bar and B mesons. As simplest systems, we consider D-bar(B) bound systems with one nucleon and two nucleons. With respecting to the heavy quark symmetry, we derive the one pion exchange potential as a long range force as an interaction between D-bar(B) meson and nucleon. We solve the Schroedinger equation with coupled channels, and investigate the D-barN (BN) bound states. We further discuss the possibility of existence of D-barNN (BNN). We discuss the possible observations of these exotic states in experiments in accelerator facilities.

  7. Photoproduction of exotic baryon resonances

    NASA Astrophysics Data System (ADS)

    Karliner, Marek; Rosner, Jonathan L.

    2016-01-01

    We point out that the new exotic resonances recently reported by LHCb in the J / ψ p channel are excellent candidates for photoproduction off a proton target. This test is crucial to confirming the resonant nature of such states, as opposed to their being kinematical effects. We specialize to an interpretation of the heavier narrow state as a molecule composed of Σc and Dbar*, and estimate its production cross section using vector dominance. The relevant photon energies and fluxes are well within the capabilities of the GlueX and CLAS12 detectors at Thomas Jefferson National Accelerator Facility (JLAB). A corresponding calculation is also performed for photoproduction of an analogous resonance which is predicted to exist in the ϒp channel.

  8. Potential Habitats for Exotic Life Within the Life Supporting Zone

    NASA Astrophysics Data System (ADS)

    Leitner, Johannes J.; Firneis, Maria G.; Hitzenberger, Regina

    2010-05-01

    System and beyond have been compiled. Dynamical investigations (related to the interior of superearths), but also heat transport regimes and potential cycles with exotic solvents as well as tidal heating processes and their influence on the thermal regime of the planets will help to define the regions of potential exotic life more precisely. Atmospheric and subsurface cycles which can take place in such habitats as well as cloud and droplet formation with and without cloud nuclei cores will further extend our knowledge on mechanisms relevant for the stability of these systems. Finally the question of suitable biomarkers, which can enable the observation of exotic habitats and their potential life forms will be considered in the research platform. In this context a special topic is also the bandwidth of photosynthesis: how is the influence of different atmospheric gases and what are the environment conditions for the chemical reactions of photosynthesis? First preliminary results for the life supporting zones of selected planetary systems will be presented. References: [1] NRC (National Research Council)(2007) The Limits of Organic Life in Planetary Systems, National Academies Press, Washington, DC 20001, ISBN 978-0-309-10484-5. [2] Kasting, J.F., Whitmore D.P. and Reynolds R.T. (1993) Icarus, 101, 109-128.

  9. Selfconsistent calculations for hyperdeformed nuclei

    SciTech Connect

    Molique, H.; Dobaczewski, J.; Dudek, J.; Luo, W.D.

    1996-12-31

    Properties of the hyperdeformed nuclei in the A {approximately} 170 mass range are re-examined using the self-consistent Hartree-Fock method with the SOP parametrization. A comparison with the previous predictions that were based on a non-selfconsistent approach is made. The existence of the {open_quotes}hyper-deformed shell closures{close_quotes} at the proton and neutron numbers Z=70 and N=100 and their very weak dependence on the rotational frequency is suggested; the corresponding single-particle energy gaps are predicted to play a role similar to that of the Z=66 and N=86 gaps in the super-deformed nuclei of the A {approximately} 150 mass range. Selfconsistent calculations suggest also that the A {approximately} 170 hyperdeformed structures have neglegible mass asymmetry in their shapes. Very importantly for the experimental studies, both the fission barriers and the {open_quotes}inner{close_quotes} barriers (that separate the hyperdeformed structures from those with smaller deformations) are predicted to be relatively high, up to the factor of {approximately}2 higher than the corresponding ones in the {sup 152}Dy superdeformed nucleus used as a reference.

  10. Transitional nuclei near shell closures

    SciTech Connect

    Mukherjee, G.

    2014-08-14

    High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.