WorldWideScience

Sample records for superheavy neutron rich

  1. On the fate of superheavy magnetic monopoles in a neutron star

    International Nuclear Information System (INIS)

    Kuzmin, V.A.; Rubakov, V.A.; AN SSSR, Moscow. Inst. Yadernykh Issledovanij)

    1983-02-01

    We propose two possible scenarios of the behaviour of superheavy magnetic monopoles in a neutron star, in which the monopole-antimonopole annihilation rate is sufficiently large to prevent the enormous heating of a neutron star due to the monopole induced neutron decays. We find that the galactic monopole flux of order 10 -16 cm -2 s -1 ster -1 can be compatible with the observational limit on the X-ray luminosity of neutron stars. (author)

  2. Neutron-rich isotopes of the lightest elements

    International Nuclear Information System (INIS)

    Oganesyan, Yu.Ts.; Penionzhkevich, Yu.Eh.; Kalpakchieva, R.

    1989-01-01

    A review is presented of the experimental investigations on the stability of very neutron-rich light nuclei carried out at the JINR Laboratory of Nuclear Reactions. Results on mass excess measurements are reported for 4 H, 5 H, 6 H, 7 H and for the superheavy helium isotope 9 He. Some results from the joint JINR-Ganil experiment on the search for and study of new neutron-rich light nuclei are also given. Analyzed are new possibilities for the investigation of multineutron decay of light nuclei. 14 refs.; 10 figs

  3. Neutron rich nuclei

    International Nuclear Information System (INIS)

    Foucher, R.

    1979-01-01

    If some β - emitters are particularly interesting to study in light, medium, and heavy nuclei, another (and also) difficult problem is to know systematically the properties of these neutron rich nuclei far from the stability line. A review of some of their characteristics is presented. How far is it possible to be objective in the interpretation of data is questioned and implications are discussed

  4. Neutron and Proton Diffusion in Fusion Reactions for the Synthesis of Superheavy Nuclei

    International Nuclear Information System (INIS)

    Ming-Hui, Huang; Zai-Guo, Gan; Zhao-Qing, Feng; Xiao-Hong, Zhou; Jun-Qing, Li

    2008-01-01

    The restriction of the one dimensional (1D) master equation (ME) with the mass number of the projectile-like fragment as a variable is studied, and a two-dimensional (2D) master equation with the neutron and proton numbers as independent variables is set up, and solved numerically. Our study showed that the 2D ME can describe the fusion process well in all projectile-target combinations. Therefore the possible channels to synthesize super-heavy nuclei can be studied correctly in wider possibilities. The available condition for employing 1D ME is pointed out

  5. The Chemistry of Superheavy Elements

    CERN Document Server

    Schädel, M

    2003-01-01

    The chemistry of transactinide or superheavy elements has reached element 108. Preparations are under way to leap to element 112 and beyond. The current status of this atom-at-a-time chemical research and its future perspectives are reviewed from an experimental point of view together with some of the interesting results from n -rich nuclides near and at the N=162 neutron shell. Experimental techniques and important results enlightening typical chemical properties of elements 104 through 108 are presented in an exemplary way. From the results of these experiments it is justified to place these elements in the Periodic Table of the Elements in to groups 4 through 8, respectively. However, mainly due to the influence of relativistic effects, it is no longer possible to deduce detailed chemical properties of these superheavy elements simply from this position.

  6. Structure of Light Neutron-rich Nuclei

    International Nuclear Information System (INIS)

    Dlouhy, Zdenek

    2007-01-01

    In this contribution we searched for irregularities in various separation energies in the frame of mass measurement of neutron-rich nuclei at GANIL. On this basis we can summarize that the new doubly magic nuclei are 8 He, 22 O and 24 O. They are characterized by extra stability and, except 24 O, they cannot accept and bind additional neutrons. However, if we add to these nuclei a proton we obtain 9 Li and 25 F which are the core for two-neutron halo nucleus 11 Li and enables that fluorine can bound even 6 more neutrons, respectively. In that aspect the doubly magic nuclei in the neutron-rich region can form the basis either for neutron halo or very neutron-rich nuclei. (Author)

  7. Fifth International Conference on Fission and Properties of Neutron-Rich Nuclei

    CERN Document Server

    Ramayya, A V; ICFN5

    2014-01-01

    These proceedings are the fifth in the series of International Conferences covering fission and properties of neutron-rich nuclei, which are at the forefront of nuclear research. The time interval of 5 years between each conference allows for significant new results to be achieved. Recently, world leaders in theory and experiments in research and the development of new facilities for research presented their latest results in areas such as synthesis of superheavy elements, new facilities for and recent results with radioactive ion beams, structure of neutron-rich nuclei, nuclear fission process, fission yields and nuclear astrophysics. This book is a major source of the latest research in these areas and plans for the future. The conference brought together a unique group of over 100 speakers including leaders from the major nuclear laboratories in Canada, China, France, Finland, Germany, Italy, Japan, Russia, Switerzland and the US along with leading research scientists from around the world.

  8. Neutron rich nuclei around 132Sn

    International Nuclear Information System (INIS)

    Bhattacharya, Sarmishtha

    2016-01-01

    The neutron rich nuclei with few particles or holes in 132 Sn have various experimental and theoretical interest to understand the evolution of nuclear structure around the doubly magic shell closure Z=50 and N=82. Some of the exotic neutron rich nuclei in this mass region are situated near waiting points in the r-process path and are of special astrophysical interest. Neutron rich nuclei near 132 Sn have been studied using fission fragment spectroscopy. The lifetime of low lying isomeric states have been precisely measured and the beta decay from the ground and isomeric states have been characterized using gamma-ray spectroscopy

  9. Synthesis of neutron-rich transuranic nuclei in fissile spallation targets

    Energy Technology Data Exchange (ETDEWEB)

    Mishustin, Igor, E-mail: mishustin@fias.uni-frankfurt.de [Frankfurt Institute for Advanced Studies, J.-W. Goethe University, 60438 Frankfurt am Main (Germany); “Kurchatov Institute”, National Research Center, 123182 Moscow (Russian Federation); Malyshkin, Yury, E-mail: malyshkin@fias.uni-frankfurt.de [Frankfurt Institute for Advanced Studies, J.-W. Goethe University, 60438 Frankfurt am Main (Germany); Institute for Nuclear Research, Russian Academy of Sciences, 117312 Moscow (Russian Federation); Pshenichnov, Igor, E-mail: pshenich@fias.uni-frankfurt.de [Frankfurt Institute for Advanced Studies, J.-W. Goethe University, 60438 Frankfurt am Main (Germany); Institute for Nuclear Research, Russian Academy of Sciences, 117312 Moscow (Russian Federation); Greiner, Walter [Frankfurt Institute for Advanced Studies, J.-W. Goethe University, 60438 Frankfurt am Main (Germany)

    2015-04-15

    A possibility of synthesizing neutron-rich superheavy elements in spallation targets of Accelerator Driven Systems (ADS) is considered. A dedicated software called Nuclide Composition Dynamics (NuCoD) was developed to model the evolution of isotope composition in the targets during a long-time irradiation by intense proton and deuteron beams. Simulation results show that transuranic elements up to {sup 249}Bk can be produced in multiple neutron capture reactions in macroscopic quantities. However, the neutron flux achievable in a spallation target is still insufficient to overcome the so-called fermium gap. Further optimization of the target design, in particular, by including moderating material and covering it by a reflector could turn ADS into an alternative source of transuranic elements in addition to nuclear fission reactors.

  10. Superheavy elements

    CERN Document Server

    Hofmann, S

    1999-01-01

    The outstanding aim of experimental investigations of heavy nuclei is the exploration of spherical 'SuperHeavy Elements' (SHEs). On the basis of the nuclear shell model, the next double magic shell-closure beyond sup 2 sup 0 sup 8 Pb is predicted at proton numbers between Z=114 and 126 and at neutron number N=184. All experimental efforts aiming at identifying SHEs (Z>=114) were negative so far. A highly sensitive search experiment was performed in November-December 1995 at SHIP. The isotope sup 2 sup 9 sup 0 116 produced by 'radiative capture' was searched for in the course of a 33 days irradiation of a sup 2 sup 0 sup 8 Pb target with sup 8 sup 2 Se projectiles, however, only cross-section limits were measured. Positive results were obtained in experiments searching for elements from 110 to 112 using cold fusion and the 1n evaporation channel. The produced isotopes were unambiguously identified by means of alpha-alpha correlations. Not fission, but alpha emission is the dominant decay mode. The measurement ...

  11. Thermodynamics of neutron-rich nuclear matter

    Energy Technology Data Exchange (ETDEWEB)

    López, Jorge A., E-mail: jorgelopez@utep.edu [Department of Physics, University of Texas at El Paso, El Paso, Texas 79968, U.S.A (United States); Porras, Sergio Terrazas, E-mail: sterraza@uacj.mx; Gutiérrez, Araceli Rodríguez, E-mail: al104010@alumnos.uacj.mx [Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua, México (Mexico)

    2016-07-07

    This manuscript presents methods to obtain properties of neutron-rich nuclear matter from classical molecular dynamics. Some of these are bulk properties of infinite nuclear matter, phase information, the Maxwell construction, spinodal lines and symmetry energy.

  12. Chemistry of superheavy elements

    International Nuclear Information System (INIS)

    Schaedel, M.

    2012-01-01

    The chemistry of superheavy elements - or transactinides from their position in the Periodic Table - is summarized. After giving an overview over historical developments, nuclear aspects about synthesis of neutron-rich isotopes of these elements, produced in hot-fusion reactions, and their nuclear decay properties are briefly mentioned. Specific requirements to cope with the one-atom-at-a-time situation in automated chemical separations and recent developments in aqueous-phase and gas-phase chemistry are presented. Exciting, current developments, first applications, and future prospects of chemical separations behind physical recoil separators ('pre-separator') are discussed in detail. The status of our current knowledge about the chemistry of rutherfordium (Rf, element 104), dubnium (Db, element 105), seaborgium (Sg, element 106), bohrium (Bh, element 107), hassium (Hs, element 108), copernicium (Cn, element 112), and element 114 is discussed from an experimental point of view. Recent results are emphasized and compared with empirical extrapolations and with fully-relativistic theoretical calculations, especially also under the aspect of the architecture of the Periodic Table. (orig.)

  13. Modeling a neutron rich nuclei source

    Energy Technology Data Exchange (ETDEWEB)

    Mirea, M.; Bajeat, O.; Clapier, F.; Ibrahim, F.; Mueller, A.C.; Pauwels, N.; Proust, J. [Institut de Physique Nucleaire, IN2P3/CNRS, 91 - Orsay (France); Mirea, M. [Institute of Physics and Nuclear Engineering, Tandem Lab., Bucharest (Romania)

    2000-07-01

    The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron rich nuclei based on the neutron induced fission can be realised using these beams. A theoretical optimization of such a facility as a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with a converter-target specific geometry. (author000.

  14. Modeling a neutron rich nuclei source

    International Nuclear Information System (INIS)

    Mirea, M.; Bajeat, O.; Clapier, F.; Ibrahim, F.; Mueller, A.C.; Pauwels, N.; Proust, J.; Mirea, M.

    2000-01-01

    The deuteron break-up process in a suitable converter gives rise to intense neutron beams. A source of neutron rich nuclei based on the neutron induced fission can be realised using these beams. A theoretical optimization of such a facility as a function of the incident deuteron energy is reported. The model used to determine the fission products takes into account the excitation energy of the target nucleus and the evaporation of prompt neutrons. Results are presented in connection with a converter-target specific geometry. (authors)

  15. A pilgrimage through superheavy valley

    Indian Academy of Sciences (India)

    gap p, average neutron pairing gap n, two-nucleon separation energy S2q and shell .... study has appeared as a powerful tool to study the shapes and collective properties of nuclei ... and identify the magic proton and neutron numbers in the superheavy region. ... pairing gap indicates the close shell structure of the nucleus.

  16. Neutron rich matter, neutron stars, and their crusts

    International Nuclear Information System (INIS)

    Horowitz, C J

    2011-01-01

    Neutron rich matter is at the heart of many fundamental questions in Nuclear Physics and Astrophysics. What are the high density phases of QCD? Where did the chemical elements come from? What is the structure of many compact and energetic objects in the heavens, and what determines their electromagnetic, neutrino, and gravitational-wave radiations? Moreover, neutron rich matter is being studied with an extraordinary variety of new tools such as Facility for Rare Isotope Beams (FRIB) and the Laser Interferometer Gravitational Wave Observatory (LIGO). We describe the Lead Radius Experiment (PREX) that is using parity violation to measure the neutron radius in 208Pb. This has important implications for neutron stars and their crusts. Using large scale molecular dynamics, we model the formation of solids in both white dwarfs and neutron stars. We find neutron star crust to be the strongest material known, some 10 billion times stronger than steel. It can support mountains on rotating neutron stars large enough to generate detectable gravitational waves. Finally, we describe a new equation of state for supernova and neutron star merger simulations based on the Virial expansion at low densities, and large scale relativistic mean field calculations.

  17. Experiments with neutron-rich isomeric beams

    International Nuclear Information System (INIS)

    Rykaczewski, K.; Lewitowicz, M.; Pfuetzner, M.

    1998-01-01

    A review of experimental results obtained on microsecond-isomeric states in neutron-rich nuclei produced in fragmentation reactions and studied with SISSI-Alpha-LISE3 spectrometer system at GANIL Caen is given. The perspectives of experiments based on secondary reactions with isomeric beams are presented

  18. Structure of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Nazarewicz, W.; Oak Ridge National Lab., TN; Warsaw Univ.

    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

  19. Structure of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Nazarewicz, W.

    2000-01-01

    Complete text of publication follows. The uncharted regions of the (N,Z) plane contain information that can answer many questions of fundamental importance for science: How many protons and neutrons can be clustered together by the strong interaction to form a bound nucleus? What are the proton and neutron magic numbers of the exotic nuclei? What are the properties of very short-lived exotic nuclei with extreme neutron-to-proton ratios? What is the effective nucleon-nucleon interaction in a nucleus that has a very large neutron excess? Nuclear life far from stability is different from that around the stability line; the promised access to completely new combinations of proton and neutron numbers offers prospects for new structural phenomena. The main objective of this talk is to discuss some of the challenges and opportunities of research with exotic nuclei. The covered topics will include: Theoretical challenges; Skins and halos in heavy nuclei; Shape coexistence in exotic nuclei; Beta-decays of neutron-rich nuclei. (author)

  20. The neutrino opacity of neutron rich matter

    Energy Technology Data Exchange (ETDEWEB)

    Alcain, P.N., E-mail: pabloalcain@gmail.com [Departamento de Física, FCEyN, UBA and IFIBA, Conicet, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires (Argentina); IFIBA-CONICET (Argentina); Dorso, C.O. [Departamento de Física, FCEyN, UBA and IFIBA, Conicet, Pabellón 1, Ciudad Universitaria, 1428 Buenos Aires (Argentina); IFIBA-CONICET (Argentina)

    2017-05-15

    The study of neutron rich matter, present in neutron star, proto-neutron stars and core-collapse supernovae, can lead to further understanding of the behavior of nuclear matter in highly asymmetric nuclei. Heterogeneous structures are expected to exist in these systems, often referred to as nuclear pasta. We have carried out a systematic study of neutrino opacity for different thermodynamic conditions in order to assess the impact that the structure has on it. We studied the dynamics of the neutrino opacity of the heterogeneous matter at different thermodynamic conditions with semiclassical molecular dynamics model already used to study nuclear multifragmentation. For different densities, proton fractions and temperature, we calculate the very long range opacity and the cluster distribution. The neutrino opacity is of crucial importance for the evolution of the core-collapse supernovae and the neutrino scattering.

  1. Transfer reaction studies in the region of heavy and superheavy nuclei at SHIP

    Energy Technology Data Exchange (ETDEWEB)

    Heinz, S; Comas, V; Hofmann, S; Ackermann, D; Heredia, J; Hessberger, F P; Khuyagbaatar, J; Kindler, B; Lommel, B; Mann, R, E-mail: s.heinz@gsi.de [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, 64291 Darmstadt (Germany)

    2011-02-01

    We studied multi-nucleon transfer reactions in the region of heavy and superheavy nuclei. The goal was to investigate these reactions as possibility to create new superheavy neutron-rich isotopes, which cannot be produced in fusion reactions. The experiments have been performed at the velocity filter SHIP at GSI. At SHIP we can detect and identify the heavy, target-like, transfer products. Due to the low background at the focal plane detector and the isotope identification via radioactive decays, the setup allows to reach an upper cross-section limit of 10 pb/sr within one day of beamtime. We investigated the systems {sup 58,64}Ni + {sup 207}Pb and {sup 48}Ca + {sup 248}Cm at beam energies below and up to 20% above the Coulomb barrier. At all energies we observed a massive transfer of protons and neutrons, where transfer products with up to eight neutrons more than the target nucleus could be identified.

  2. Synthesis and study of neutron-rich nuclides

    International Nuclear Information System (INIS)

    Luo Yixiao

    1995-01-01

    During the past few years our understanding of the decay properties and nuclear structure has been extended in a systematic fashion for the neutron-rich nuclei. This review will first sketch the production and identification of the neutron-rich nuclei throughout the whole mass region, and will then discuss the impressive progress in the studies of the exotic decay properties and nuclear structure of neutron-rich nuclei. Their astrophysical implications will also be outlined

  3. Synthesis of neutron-rich transuranic nuclei in fissile spallation targets

    OpenAIRE

    Mishustin, Igor; Malyshkin, Yury; Pshenichnov, Igor; Greiner, Walter

    2014-01-01

    A possibility of synthesizing neutron-reach super-heavy elements in spallation targets of Accelerator Driven Systems (ADS) is considered. A dedicated software called Nuclide Composition Dynamics (NuCoD) was developed to model the evolution of isotope composition in the targets during a long-time irradiation by intense proton and deuteron beams. Simulation results show that transuranic elements up to Bk-249 can be produced in multiple neutron capture reactions in macroscopic quantities. Howeve...

  4. Two-proton knockout on neutron-rich nuclei

    International Nuclear Information System (INIS)

    Bazin, D.; Brown, B.A.; Campbell, C.M.; Church, J.A.; Dinca, D.C.; Enders, J.; Gade, A.; Glasmacher, T.; Hansen, P.G.; Mueller, W.F.; Olliver, H.; Perry, B.C.; Sherrill, B.M.; Terry, J.R.; Tostevin, J.A.

    2004-01-01

    Two-proton knockout reactions on neutron-rich nuclei [Phys. Rev. Lett. 91 (2003) 012501] have been studied in inverse kinematics at intermediate energy. Strong evidence that the two-proton removal from a neutron-rich system proceeds as a direct reaction is presented, together with a preliminary theoretical discussion of the partial cross sections based on eikonal reaction theory and the many-body shell model. They show that this reaction can be used to characterize the wave functions of the projectiles and holds great promise for the study of neutron-rich nuclei

  5. Relativistic mean field calculations in neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Gangopadhyay, G.; Bhattacharya, Madhubrata [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Roy, Subinit [Saha Institute of Nuclear Physics, Block AF, Sector 1, Kolkata- 700 064 (India)

    2014-08-14

    Relativistic mean field calculations have been employed to study neutron rich nuclei. The Lagrange's equations have been solved in the co-ordinate space. The effect of the continuum has been effectively taken into account through the method of resonant continuum. It is found that BCS approximation performs as well as a more involved Relativistic Continuum Hartree Bogoliubov approach. Calculations reveal the possibility of modification of magic numbers in neutron rich nuclei. Calculation for low energy proton scattering cross sections shows that the present approach reproduces the density in very light neutron rich nuclei.

  6. Fusion enhancement in the reactions of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Bian Baoan; Zhang Fengshou; Zhou Hongyu

    2009-01-01

    The neutron-rich fusion reactions are investigated systematically using the improved isospin dependent quantum molecular dynamics model. By studying the systematic dependence of fusion barrier on neuron excess, we find the enhancement of the fusion cross sections for neutron-rich nuclear reactions that give the lowered static Coulomb barriers. The calculated fusion cross sections agree quantitatively with the experimental data. We further discuss the mechanism of the fusion enhancement of the cross sections for neutron-rich nuclear reactions by analyzing the dynamical lowering of the Coulomb barrier that is attributed to the enhancement of the N/Z ratio at the neck region.

  7. High-spin structure of neutron-rich Dy isotopes

    Indian Academy of Sciences (India)

    Neutron-rich Dy isotopes; high-spin states; g-factors; cranked HFB theory. ... for 164Dy marking a clear separation in the behaviour as a function of neutron ... cipal x-axis as the cranking axis) in this mass region we have planned to make a sys-.

  8. Fission decay properties of ultra neutron-rich uranium isotopes

    Indian Academy of Sciences (India)

    in the chain of neutron-rich uranium isotopes is examined here. The neutron ... mean field theory, this nucleus is shown to undergo exotic decay mode of thermal neu- .... For 250U with a fission barrier of 4.3 MeV [5], we obtain the value of.

  9. Dissipative dynamics of the synthesis of superheavy elements

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Takahiro; Aritomo, Y.; Tokuda, T.; Okazaki, K.; Ohta, M. [Konan Univ., Kobe (Japan). Dept. of Physics; Abe, Y.

    1997-07-01

    Fusion-fission process in heavy systems are analyzed by Smoluchowski equation taking into account the temperature dependent shell correction energy. The evaporation residue cross sections of superheavy elements have been shown to have an optimum value at a certain temperature, due to the balance between the diffusibility for fusion at high temperature and the restoration of the shell correction energy against fission at low temperature. The isotope dependence of the evaporation residue cross section is found to be very strong. Neutron rich compound system with small neutron separation energy is favorable for larger cross section because of the quick restoration of the shell correction energy. The Z-dependence is discussed for the formation of the compound nuclei with Z=102 to Z=114. (author)

  10. Synthesis and study of neutron-rich nuclides

    International Nuclear Information System (INIS)

    Luo, Y.X.

    1995-01-01

    During the past few years our understanding of the decay properties and nuclear structure has been extended in a systematic fashion for the neutron-rich nuclei. This review will discuss the impressive progress in the studies of the exotic decay properties and nuclear structure of n-rich nuclei. Their astrophysical implications will also be outlined. ((orig.))

  11. Maris polarization in neutron-rich nuclei

    Science.gov (United States)

    Shubhchintak; Bertulani, C. A.; Aumann, T.

    2018-03-01

    We present a theoretical study of the Maris polarization effect and its application in quasi-free reactions to assess information on the structure of exotic nuclei. In particular, we explore the dependence of the polarization effect on neutron excess and neutron-skin thickness. We discuss the uncertainties in the calculations of triple differential cross sections and of analyzing powers due the choices of various nucleon-nucleon interactions and optical potentials and the limitations of the method. Our study implies that polarization variables in (p, 2p) reactions in inverse kinematics can be an effective probe of single-particle structure of nuclei in radioactive-beam facilities.

  12. Reactions with fast radioactive beams of neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Aumann, T. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany)

    2005-11-01

    The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like {sup 11}Li and {sup 12}Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)

  13. Reactions with fast radioactive beams of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Aumann, T.

    2005-11-01

    The neutron dripline has presently been reached only for the lightest nuclei up to the element oxygen. In this region of light neutron-rich nuclei, scattering experiments are feasible even for dripline nuclei by utilizing high-energy secondary beams produced by fragmentation. In the present article, reactions of high-energy radioactive beams will be exemplified using recent experimental results mainly derived from measurements of breakup reactions performed at the LAND and FRS facilities at GSI and at the S800 spectrometer at the NSCL. Nuclear and electromagnetically induced reactions allow probing different aspects of nuclear structure at the limits of stability related to the neutron-proton asymmetry and the weak binding close to the dripline. Properties of the valence-neutron wave functions are studied in the one-neutron knockout reaction, revealing the changes of shell structure when going from the beta-stability line to more asymmetric loosely bound neutron-rich systems. The vanishing of the N=8 shell gap for neutron-rich systems like 11 Li and 12 Be, or the new closed N=14, 16 shells for the oxygen isotopes are examples. The continuum of weakly bound nuclei and halo states can be studied by inelastic scattering. The dipole response, for instance, is found to change dramatically when going away from the valley of stability. A redistribution of the dipole strength towards lower excitation energies is observed for neutron-rich nuclei, which partly might be due to a new collective excitation mode related to the neutron-proton asymmetry. Halo nuclei in particular show strong dipole transitions to the continuum at the threshold, being directly related to the ground-state properties of the projectile. Finally, an outlook on future experimental prospects is given. (orig.)

  14. Evolution of shell gaps with neutron richness

    International Nuclear Information System (INIS)

    Basu, Moumita Ray; Ray, I.; Kshetri, Ritesh; Saha Sarkar, M.; Sarkar, S.

    2006-01-01

    In the present work, an attempt has been made to coordinate the recent data available over the periodic table, specially near the shell gaps and studied the evolution of the shell gaps as function of neutron numbers and/or other related quantities

  15. Study of Superheavy Elements

    International Nuclear Information System (INIS)

    Hofmann, Sigurd

    2007-01-01

    The nuclear shell model predicts that the next doubly magic shell-closure beyond 208 Pb is at a proton number Z = 114, 120, or 126 and at a neutron number N = 172 or 184. The outstanding aim of experimental investigations is the exploration of this region of spherical 'SuperHeavy Elements' (SHEs). Experimental methods are described, which allowed for the identification of elements produced on a cross-section level of about 1 pb. The decay data reveal that for the heaviest elements, the dominant decay mode is alpha emission, not fission. Decay properties as well as reaction cross-sections are compared with results of theoretical investigations. Finally, plans are presented for the further development of the experimental set-up and the application of new techniques, as for instance the precise mass measurement of the produced nuclei using ion traps. At increased sensitivity, the detailed exploration of the region of spherical SHEs will start, after first steps on the island were made in recent years. (Author)

  16. Decay properties of some neutron-rich praseodymium isotopes

    International Nuclear Information System (INIS)

    Skarnemark, G.; Aronsson, P.O.; Stender, E.; Trautmann, N.; Kaffrell, N.; Bjoernstad, T.; Kvale, E.; Skarestad, M.

    1976-01-01

    Neutron-rich Pr isotopes produced in the thermal neutron-induced fission of 235 U have been investigated by means of γ-γ coincidence experiments. The nuclides have been separated from the fission product mixture, using the fast chemical separation system SISAK in connection with a gas jet recoil transport system. The results include assignments of several new γ-ray energies and partial decay schemes for 147 Pr, 148 Pr, 149 Pr and 150 Pr. (orig.) [de

  17. Shell gap reduction in neutron-rich N=17 nuclei

    International Nuclear Information System (INIS)

    Obertelli, A.; Gillibert, A.; Alamanos, N.; Alvarez, M.; Auger, F.; Dayras, R.; Drouart, A.; France, G. de; Jurado, B.; Keeley, N.; Lapoux, V.; Mittig, W.; Mougeot, X.; Nalpas, L.; Pakou, A.; Patronis, N.; Pollacco, E.C.; Rejmund, F.; Rejmund, M.; Roussel-Chomaz, P.; Savajols, H.; Skaza, F.; Theisen, Ch.

    2006-01-01

    The spectroscopy of 27 Ne has been investigated through the one-neutron transfer reaction 26 Ne(d,p) 27 Ne in inverse kinematics at 9.7 MeV/nucleon. The results strongly support the existence of a low-lying negative parity state in 27 Ne, which is a signature of a reduced sd-fp shell gap in the N=16 neutron-rich region, at variance with stable nuclei

  18. Maris polarization in neutron-rich nuclei

    Directory of Open Access Journals (Sweden)

    Shubhchintak

    2018-03-01

    Full Text Available We present a theoretical study of the Maris polarization effect and its application in quasi-free reactions to assess information on the structure of exotic nuclei. In particular, we explore the dependence of the polarization effect on neutron excess and neutron-skin thickness. We discuss the uncertainties in the calculations of triple differential cross sections and of analyzing powers due the choices of various nucleon–nucleon interactions and optical potentials and the limitations of the method. Our study implies that polarization variables in (p, 2p reactions in inverse kinematics can be an effective probe of single-particle structure of nuclei in radioactive-beam facilities.

  19. Calculation of the radii of neutron rich light exotic nuclei

    International Nuclear Information System (INIS)

    Charagi, S.K.; Gupta, S.K.

    1991-01-01

    The interaction cross section of a few unstable neutron rich nuclei have been measured using exotic isotope beams produced through the projectile fragmentation process in high energy heavy-ion collisions. Interaction cross section of He, Li, Be and B isotope projectiles with Be, C and Al targets have thus been measured at 790 MeV/nucleon. We have made a comprehensive analysis of the data on the interaction cross section, to extract the radii of these neutron rich light nuclei. 7 refs., 1 fig., 3 tabs

  20. Properties of neutron-rich hafnium high-spin isomers

    CERN Multimedia

    Tungate, G; Walker, P M; Neyens, G; Billowes, J; Flanagan, K; Koester, U H; Litvinov, Y

    It is proposed to study highly-excited multi-quasiparticle isomers in neutron-rich hafnium (Z=72) isotopes. Long half-lives have already been measured for such isomers in the storage ring at GSI, ensuring their accessibility with ISOL production. The present proposal focuses on:\\\\ (i) an on-line experiment to measure isomer properties in $^{183}$Hf and $^{184}$Hf, and\\\\ (ii) an off-line molecular breakup test using REXTRAP, to provide Hf$^{+}$ beams for future laser spectroscopy and greater sensitivity for the future study of more neutron-rich isotopes.

  1. Laser Spectroscopy of Neutron Rich Bismuth Isotopes

    CERN Multimedia

    2002-01-01

    %IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

  2. Surface energy of very neutron rich nuclei

    CERN Document Server

    Von Groote, H

    1976-01-01

    For a microscopic model calculation of the nuclear surface-energy coefficient sigma the surface energy is defined as the energy loss of an uncharged, semiinfinite (inhomogeneous) two-component system compared to an infinite (homogeneous) system with the same particle asymmetry delta . Using the Thomas-Fermi model the calculations are performed for a series of systems with increasing delta , starting from symmetric matter ( delta =0) and extending beyond the drip line of the neutrons, until the system undergoes a phase transition to a homogeneous system. The results for the surface energy as well as for the neutron skin and for the surface diffuseness are compared to the macroscopic approach of the Droplet Model (DM), which turns out to be a good approximation for small asymmetries typical for the region of the valley of beta -stability. For larger asymmetries, close to the drip lines, terms of higher order than contained in the DM approach are no longer negligible. Beyond the drip lines the pressure of the ou...

  3. Recent results on neutron rich tin isotopes by laser spectroscopy

    CERN Document Server

    Roussière, B; Crawford, J E; Essabaa, S; Fedosseev, V; Geithner, W; Genevey, J; Girod, M; Huber, G; Horn, R; Kappertz, S; Lassen, J; Le Blanc, F; Lee, J K P; Le Scornet, G; Lettry, Jacques; Mishin, V I; Neugart, R; Obert, J; Oms, J; Ouchrif, A; Peru, S; Pinard, J; Ravn, H L; Sauvage, J; Verney, D

    2001-01-01

    Laser spectroscopy measurements have been performed on neutron rich tin isotopes using the COMPLIS experimental setup. The nuclear charge radii of the even-even isotopes from A=108 to 132 are compared to the results of macroscopic and microscopic calculations. The improvements and optimizations needed to perform the isotope shift measurement on $^{134}$Sn are presented.

  4. Haloes and clustering in light, neutron-rich nuclei

    International Nuclear Information System (INIS)

    Orr, N.A.

    2001-10-01

    Clustering is a relatively widespread phenomenon which takes on many guises across the nuclear landscape. Selected topics concerning the study of halo systems and clustering in light, neutron-rich nuclei are discussed here through illustrative examples taken from the Be isotopic chain. (author)

  5. Influence Of The Neutron Richness On Binary Decays

    Directory of Open Access Journals (Sweden)

    Roy R.

    2010-03-01

    Full Text Available The influence of the neutron richness on binary decays is investigated in 78,82Kr+ 40Ca reactions at 5.5 MeV/A incident energy. Kinetic energy distributions and angular distributions of fragments with atomic number 6 ≤ Z ≤ 28 were measured using the 4π-INDRA array. Global features are compatible with an emission from a long-lived system. The yields around the symmetric splitting are about 30The persistence of strong structural effects is evidenced from elemental cross-sections of the light fragments. The cross-sections for odd-Z fragments are higher for the neutron rich CN while cross-sections for even-Z fragments are higher for the neutron poor CN. Calculations assuming two different potential energy surfaces are presented.

  6. Do superheavy elements imply the existence of black holes

    International Nuclear Information System (INIS)

    Pringle, J.E.; Dearborn, D.S.P.; Fabian, A.C.

    1976-01-01

    Some comments are offered on the question of where superheavy elements, such as elements 116, 124 and 126, are likely to have been formed. Most of these elements are thought to have been produced under conditions of explosive nucleosynthesis by what is known as the 'r-process', and particularly in conventional supernova explosions, but it is stated that the ability of the r-process to produce superheavy elements is very uncertain, and the conditions necessary for synthesis of these elements are difficult to realise in astrophysical situations. It is thought that superheavy elements exist in the outer layers of neutron stars, and ideal conditions for the production of superheavy nuclei, such as high neutron flux and rapid β decays, occur in the disruption of a neutron star. Such disruption is possible in two ways, both of which involve a black hole. It is likely that a neutron star is disrupted when it accretes sufficient material for its mass to exceed the maximum mass for stability, and it then has no alternative but to collapse to form a black hole and it seems possible that some of the outer layers are thrown off during the process. It is thus argued that the most likely site for the production of superheavy elements is in the surface layers of a neutron star, and the most plausible means by which these layers can be returned to the interstellar medium involves the intervention or formation of a black hole. (U.K.)

  7. Isospin Conservation in Neutron Rich Systems of Heavy Nuclei

    Science.gov (United States)

    Jain, Ashok Kumar; Garg, Swati

    2018-05-01

    It is generally believed that isospin would diminish in its importance as we go towards heavy mass region due to isospin mixing caused by the growing Coulomb forces. However, it was realized quite early that isospin could become an important and useful quantum number for all nuclei including heavy nuclei due to neutron richness of the systems [1]. Lane and Soper [2] also showed in a theoretical calculation that isospin indeed remains quite good in heavy mass neutron rich systems. In this paper, we present isospin based calculations [3, 4] for the fission fragment distributions obtained from heavy-ion fusion fission reactions. We discuss in detail the procedure adopted to assign the isospin values and the role of neutron multiplicity data in obtaining the total fission fragment distributions. We show that the observed fragment distributions can be reproduced rather reasonably well by the calculations based on the idea of conservation of isospin. This is a direct experimental evidence of the validity of isospin in heavy nuclei, which arises largely due to the neutron-rich nature of heavy nuclei and their fragments. This result may eventually become useful for the theories of nuclear fission and also in other practical applications.

  8. Physics with Heavy Neutron Rich Ribs at the Hribf

    Science.gov (United States)

    Radford, David

    2002-10-01

    The Holifield Radioactive Ion Beam Facility at the Oak Ridge National Laboratory has recently produced the world's first post-accelerated beams of heavy neutron-rich nuclei. B(E2;0^+ arrow 2^+) values for neutron-rich ^126,128Sn and ^132,134,136Te isotopes have been measured by Coulomb excitation of radioactive ion beams in inverse kinematics. The results for ^132Te and ^134Te (N=80,82) show excellent agreement with systematics of lighter Te isotopes, but the B(E2) value for ^136Te (N=84) is unexpectedly small. Single-neutron transfer reactions leading to ^135Te were identified using a ^134Te beam on ^natBe and ^13C targets at energies just above the Coulomb barrier. The use of the Be target provided an unambiguous signature for neutron transfer through the detection of two correlated α particles, arising from the breakup of unstable ^8Be. The results of these experiments will be discussed, togther with plans for future experiments with these heavy n-rich RIBs.

  9. Thermonuclear runaways in thick hydrogen rich envelopes of neutron stars

    Science.gov (United States)

    Starrfield, S. G.; Kenyon, S.; Truran, J. W.; Sparks, W. M.

    1981-01-01

    A Lagrangian, fully implicit, one dimensional hydrodynamic computer code was used to evolve thermonuclear runaways in the accreted hydrogen rich envelopes of 1.0 Msub solar neutron stars with radii of 10 km and 20 km. Simulations produce outbursts which last from about 750 seconds to about one week. Peak effective temeratures and luninosities were 26 million K and 80 thousand Lsub solar for the 10 km study and 5.3 millison and 600 Lsub solar for the 20 km study. Hydrodynamic expansion on the 10 km neutron star produced a precursor lasting about one ten thousandth seconds.

  10. Shape transition in the neutron rich sodium isotopes

    International Nuclear Information System (INIS)

    Campi, X.; Flocard, H.; Kerman, A.K.; Koonin, S.; Massachusetts Inst. of Tech., Cambridge

    1975-06-01

    Mass spectrometer measurements of the neutron rich sodium isotopes show a sudden increase at 31 Na in the values of the two neutron separation energies. The spherical shell model naturally predicts a sudden decrease at 32 Na after the N=20 shell closure. It is proposed that the explanation for this disagreement lies in the fact that sodium isotopes in this mass region are strongly deformed due to the filling of negative parity orbitals from the 1fsub(7/2) shell. Hartree-Fock calculations are presented in support of this conjecture [fr

  11. SU(3) symmetries in exotic neutron-rich nuclei

    International Nuclear Information System (INIS)

    Hayes, A.C.

    1991-01-01

    We examine the structure of the exotic neutron-rich nucleus 11 Li with an emphasis on understanding the origin of the soft E1 resonance and the neuron halo. The similarities and differences between shell model and di-neutron cluster model descriptions of the system are displayed using the Hecht expansion techniques. We find that the ground state 11 Li as described in large shell model calculations is well approximated by the di-neutron cluster state. In contrast to the ground state, the soft E1 model of 11 Li appears to have a more complicated structure and the E1 strength of this resonance is very sensitive to cancellations between p→s and p→d contributions to the dipole matrix elements. 12 refs., 6 figs., 3 tabs

  12. Nuclear treasure island [superheavy nuclei

    CERN Document Server

    CERN. Geneva

    1999-01-01

    Summary form only given. Soon after the experiments at Dubna, which synthesized element 114 and made the first footprints on the beach of the "island of nuclear stability", two new superheavy elements have been discovered at the Lawrence Berkeley National Laboratory. Element 118 and its immediate decay product, element 116, were manufactured at Berkeley's 88 inch cyclotron by fusing targets of lead-208 with an intense beam of 449 MeV krypton-86 ions. Although both new nuclei almost instantly decay into lighter ones, the decay sequence is consistent with theories that have long predicted the island of stability for nuclei with approximately 114 protons and 184 neutrons. Theorist Robert Smolanczuk, visiting from the Soltan Institute for Nuclear Studies in Poland, had calculated that this reaction should have particularly favourable production rates. Now that this route has been signposted, similar reactions could be possible: new elements and isotopes, tests of nuclear stability and mass models, and a new under...

  13. Experimental determination of one- and two-neutron separation energies for neutron-rich copper isotopes

    Science.gov (United States)

    Yu, Mian; Wei, Hui-Ling; Song, Yi-Dan; Ma, Chun-Wang

    2017-09-01

    A method is proposed to determine the one-neutron S n or two-neutron S 2n separation energy of neutron-rich isotopes. Relationships between S n (S 2n) and isotopic cross sections have been deduced from an empirical formula, i.e., the cross section of an isotope exponentially depends on the average binding energy per nucleon B/A. The proposed relationships have been verified using the neutron-rich copper isotopes measured in the 64A MeV 86Kr + 9Be reaction. S n, S 2n, and B/A for the very neutron-rich 77,78,79Cu isotopes are determined from the proposed correlations. It is also proposed that the correlations between S n, S 2n and isotopic cross sections can be used to find the location of neutron drip line isotopes. Supported by Program for Science and Technology Innovation Talents at Universities of Henan Province (13HASTIT046), Natural and Science Foundation in Henan Province (162300410179), Program for the Excellent Youth at Henan Normal University (154100510007) and Y-D Song thanks the support from the Creative Experimental Project of National Undergraduate Students (CEPNU 201510476017)

  14. Nuclear transition moment measurements of neutron rich nuclei

    Science.gov (United States)

    Starosta, Krzysztof

    2009-10-01

    The Recoil Distance Method (RDM) and related Doppler Shift Attenuation Method (DSAM) are well-established tools for lifetime measurements following nuclear reactions near the Coulomb barrier. Recently, the RDM was implemented at National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University using NSCL/K"oln plunger device and a unique combination of the state-of-the-art instruments available there. Doppler-shift lifetime measurements following Coulomb excitation, knock-out, and fragmentation at intermediate energies of ˜100 MeV/u hold the promise of providing lifetime information for excited states in a wide range of unstable nuclei. So far, the method was used to investigate the collectivity of the neutron-rich ^16,18,20C, ^62,64,66Fe, ^70,72Ni, ^110,114Pd isotopes and also of the neutron-deficient N=Z ^64Ge. A significant fraction of these experiments was performed using NSCL's Segmented Germanium Array instrumented with the Digital Data Acquisition System which enables gamma-ray tracking. The impact of GRETINA and gamma-ray tracking on RDM and DSAM studies of neutron-rich nuclei will be discussed.

  15. Beyond darmstadtium -Status and perspectives of superheavy element research

    International Nuclear Information System (INIS)

    Ackermann, D.

    2005-01-01

    The search for superheavy elements has yielded exciting results for both the ''cold fusion'' approach with reactions employing Pb and Bi targets and the ''hot fusion'' reactions with 48 Ca beams on actinide targets. In recent years the accelerator laboratories in Berkeley, Dubna and Darmstadt have been joined by new players in the game in France with GANIL, Caen, and in Japan with RIKEN, Tokyo. The latter yielding very encouraging results for the reactions on Pb/Bi targets which confirmed the data obtained at GSI. Beyond the successful synthesis, interesting features of the structure of the very heavy nuclei like the hint for a possible K-isomer in 270 Ds or the population of states at a spin of up to 22ℎ in 254 No give a flavor of the exciting physics we can expect in the region at the very extreme upper right of the nuclear chart. To get a hand on it, a considerable increase in sensitivity is demanded from future experimental set-ups. High intensity stable beam accelerators, mass measurement in ion traps and mass spectrometers, as well as the possible employment of unstable neutron-rich projectile species, initially certainly only for systematic studies of reaction mechanism and nuclear structure features for lighter exotic neutron-rich isotopes, are some of the technological challenges which have been taken on. (orig.)

  16. The electric dipole response of neutron rich tin isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Horvat, Andrea; Aumann, Thomas; Rossi, Dominic; Schindler, Fabia [Institut fuer Kernphysik, TU Darmstadt (Germany); Boretzky, Konstanze [GSI Helmholzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Johansen, Jacob [Aarhus University (Denmark); Schrock, Philipp [The University of Tokyo (Japan); Collaboration: R3B-Collaboration

    2016-07-01

    Studies of the dipole response in medium heavy and heavy neutron rich nuclei reveal valuable information about the isospin dependence of the nuclear equation of state. Therefore an experimental campaign investigating both the electric dipole response via Coulomb excitation and neutron removal along the tin isotope chain ({sup 124-134}Sn) has been carried out at the R3B (Reactions with Relativistic Radioactive Beams) setup at GSI (Helmholtzzentrum fuer Schwerionenforschung) for which the analysis is ongoing. The E1 response was induced via relativistic Coulomb scattering by a lead target in inverse kinematics, and calls for a kinematically complete determination of all reaction products in order to reconstruct the excitation energy by means of the invariant mass method. The goal is to obtain the Coulomb excitation cross section up to the adiabatic cut-off energy, covering the giant dipole resonance (GDR) range.

  17. Properties of neutron-rich nuclei studied by fission product nuclear chemistry

    International Nuclear Information System (INIS)

    Meyer, R.A.; Henry, E.A.; Griffin, H.C.; Lien, O.G. III; Lane, S.M.; Stevenson, P.C.; Yaffe, R.P.; Skarnemark, G.

    1979-09-01

    A review is given of the properties of neutron-rich nuclei studied by fission product nuclear chemistry and includes the techniques used in elemental isolation and current research on the structure of nuclei near 132 Sn, particle emission, and coexisting structure in both neutron-poor and neutron-rich nuclei. 35 references

  18. Level structures of neutron-rich Xe isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Lister, C.J.; Morss, L.R. [and others

    1995-08-01

    The level structures of neutron-rich Xe isotopes were determined by observing prompt gamma-ray coincidences in {sup 248}Cm fission fragments. A 5-mg {sup 248}Cm, in the form of {sup 248}Cm-KCl pellet, was placed inside Eurogam array which consisted of 45 Compton-suppressed Ge detectors and 5 Low-Energy Photon Spectrometers. Transitions in Xe isotopes were identified by the appearance of new peaks in the {gamma}-ray spectra obtained by gating on the gamma peaks of the complementary Mo fragments.

  19. Swimming back from the superheavy island

    International Nuclear Information System (INIS)

    Draculis, G.

    1999-01-01

    What's next in the series 108, 109, 110, 111, 112?The answer a couple of years ago looked like being not much. But major ripples are spreading in the Nuclear Physics community as news of the recent discoveries of the Superheavy element Z=118 and its daughters Z=116 and Z=114 was announced by a Berkeley group led by Victor Ninov [1]. Several pieces of news about Z=114 from studies at Dubna promoted by Yuri Oganessian [2,3] were circulating at about the same time.The 'not much' answer was because increasingly heroic efforts seemed to be needed to produce and identify each heavier element in the series. The problem is that such nuclei, if they exist in a stable or quasi-stable form are prone to fission, and so are any nuclei one might conceive as making to provide a path to one's nucleus of choice. The favoured reaction process used to make them is heavy-ion fusion which involves bombarding target nuclei of 208 PB (proton number Z=82), 238 U (Z=92) or even 244 Pu (Z=94) with medium weight (and relatively neutron-rich) beams such as 48 Ca (Z=20) and 86 Kr (Z=36) nuclei, accelerated to energies near or just above the Coulomb barrier, with the hope of the two nuclei overlapping and combining because of the highly attractive (strong) nuclear force. The catch is that putting sufficient energy in to get the nuclei together leaves the compound nucleus with excitation energy and spin, which dramatically increase its probability to fission, and therefore not survive further. As you go lower in beam energy, the probability for the initial fusion drops precipitously since the nuclei have to tunnel through a potential barrier caused by the repulsive Coulomb force between the nuclear charges, in order to make contact. Somewhere between the dramatically falling probability for fusion and steeply increasing probability for fission might be a window of production and survival

  20. Laser Spectroscopy Studies in the Neutron-Rich Sn Region

    CERN Multimedia

    Obert, J

    2002-01-01

    We propose to use the powerful laser spectroscopy method to determine the magnetic moment $\\mu$ and the variation of the mean square charge radius ($\\delta\\,\\langle$r$_{c}^{2}\\,\\rangle$) for ground and long-lived isomeric states of the Sn isotopes from A=125 to the doubly-magic $^{132}$Sn isotope and beyond. For these neutron-rich Sn nuclei, numerous $\\delta\\,\\langle$r$^{2}_{c}\\,\\rangle$ curves have already been calculated and the predictions depend upon the effective interactions used. Therefore, a study of the effect of the shell closure N=82 on the $\\delta\\,\\langle$r$^{2}_{c}\\,\\rangle$ values in the Z=50 magic nuclei is of great interest, especially because $^{132}$Sn is located far from the stability valley. It will help to improve the parameters of the effective interactions and make them more suitable to predict the properties of exotic nuclei. \\\\ \\\\The neutron-rich Sn isotopes produced with an uranium carbide target, are ionized using either a hot plasma ion source or the resonant ionization laser ion ...

  1. Spectroscopy of neutron-rich isotopes of nickel and iron

    International Nuclear Information System (INIS)

    Girod, M.; Dessagne, P.; Bernas, M.; Langevin, M.; Pougheon, F.; Roussel, P.

    1987-01-01

    Spectroscopy of neutron rich isotopes of 67 Ni, 68 Ni and 62 Fe is studied using the quasi-elastic transfer reactions ( 14 C, 16 O) and ( 14 C, 17 O) on mass separated targets of 70 Zn and of 64 Ni. The structure of these new nuclei is investigated through the Hartree-Fock-Bogoliubov (HFB) calculations, using the D1SA interaction. Inertial parameters are calculated in the cranking approximation. Collective excited states are obtained consistently by solving the Bohr Hamiltonian. Based on these results, quantum numbers are tentatively assigned to the observed states and angular distributions, measured and calculated from the DWBA, are used to check this assignment. The spectroscopy of more neutron rich nuclei, yet unknown, is anticipated. A sharper test of wave functions is provided by the monopole operator of the O 2 + → O 1 + transition in 68 Ni, which have been deduced from the halflife measurement performed in delayed coincidence experiments. An impressive agreement is obtained between the measured halflife and its value calculated using complete HFB wave functions

  2. Lifetime measurement in neutron-rich A ∝ 100 nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Saba; Jolie, Jan; Regis, Jean-Marc; Saed-Samii, Nima; Warr, Nigel [Institute for Nuclear Physics, University of Cologne, Cologne (Germany); Collaboration: EXILL-FATIMA-Collaboration

    2016-07-01

    Rapid shape changes are observed in the region of neutron rich nuclei with a mass around A=100. Precise lifetime measurements are a key ingredient in the systematic study of the evolution of nuclear deformation and the degree of collectivity in this region. Nuclear lifetimes of excited states can be obtained using the fast-timing technique with LaBr{sub 3}(Ce)-scintillators. We used neutron induced fission of {sup 241}Pu in order to study lifetimes of excited states of fission fragments in the A∝100 region. The EXILL-FATIMA array located at the PF1B cold neutron beam line at the Institut Laue-Langevin comprises of 8 BGO-shielded EXOGAM clover detectors and 16 very fast LaBr{sub 3}(Ce)-scintillator detectors, which were installed around the fission target. We have studied the lifetimes of low lying states for the nuclei {sup 98}Zr, {sup 100}Zr and {sup 102}Zr by applying the generalized centroid difference method. In this contribution we report on the used fast-timing setup and present preliminary results for the studied isotopes.

  3. Unexpectedly large charge radii of neutron-rich calcium isotopes

    CERN Document Server

    Garcia Ruiz, R F; Blaum, K; Ekström, A; Frömmgen, N; Hagen, G; Hammen, M; Hebeler, K; Holt, J D; Jansen, G R; Kowalska, M; Kreim, K; Nazarewicz, W; Neugart, R; Neyens, G; Nörtershäuser, W; Papenbrock, T; Papuga, J; Schwenk, A; Simonis, J; Wendt, K A; Yordanov, D T

    2016-01-01

    Despite being a complex many-body system, the atomic nucleus exhibits simple structures for certain ‘magic’ numbers of protons and neutrons. The calcium chain in particular is both unique and puzzling: evidence of doubly magic features are known in 40,48Ca, and recently suggested in two radioactive isotopes, 52,54Ca. Although many properties of experimentally known calcium isotopes have been successfully described by nuclear theory, it is still a challenge to predict the evolution of their charge radii. Here we present the first measurements of the charge radii of 49,51,52Ca, obtained from laser spectroscopy experiments at ISOLDE, CERN. The experimental results are complemented by state-of-the-art theoretical calculations. The large and unexpected increase of the size of the neutron-rich calcium isotopes beyond N = 28 challenges the doubly magic nature of 52Ca and opens new intriguing questions on the evolution of nuclear sizes away from stability, which are of importance for our understanding of neutron-...

  4. Isomer spectroscopy of neutron-rich 168 Tb 103

    Energy Technology Data Exchange (ETDEWEB)

    Gurgi, L. A.; Regan, P. H.; Söderström, P. -A.; Watanabe, H.; Walker, P. M.; Podolyák, Zs.; Nishimura, S.; Berry, T. A.; Doornenbal, P.; Lorusso, G.; Isobe, T.; Baba, H.; Xu, Z. Y.; Sakurai, H.; Sumikama, T.; Catford, W. N.; Bruce, A. M.; Browne, F.; Lane, G. J.; Kondev, F. G.; Odahara, A.; Wu, J.; Liu, H. L.; Xu, F. R.; Korkulu, Z.; Lee, P.; Liu, J. J.; Phong, V. H.; Yag, A.; Zhang, G. X.; Alharbi, T.; Carroll, R. J.; Chae, K. Y.; Dombradi, Zs.; Estrade, A.; Fukuda, N.; Griffin, C.; Ideguchi, E.; Inabe, N.; Kanaoka, H.; Kojouharov, I.; Kubo, T.; Kubono, S.; Kurz, N.; Kuti, I.; Lalkovski, S.; Lee, E. J.; Lee, C. S.; Lotay, G.; Moon, C. -B.; Nishizuka, I.; Nita, C. R.; Patel, Z.; Roberts, O. J.; Schaffner, H.; Shand, C. M.; Suzuki, H.; Takeda, H.; Terashima, S.; Vajta, Zs.; Yoshida, S.; Valiente-Dòbon, J. J.

    2017-11-01

    In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified event-by-event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identified using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr3) fast-timing scintillation detectors from the FATIMA collaboration. This paper presents the internal decay of a metastable isomeric excited state in the odd-odd nucleus 168Tb, which corresponds to a single proton-neutron hole configuration in the valence maximum nucleus 170Dy. These data represent the first information on excited states in this nucleus, which is the most neutron-rich odd-odd isotope of terbium (Z=65) studied to date. Nilsson configurations associated with an axially symmetric, prolate-deformed nucleus are proposed for the 168Tb ground state the observed isomeric state by comparison with Blocked BCS-Nilsson calculations.

  5. Synthesis and decay process of superheavy nuclei with Z=119-122 via hot-fusion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Ghahramany, N.; Ansari, A. [Shiraz University, Department of Physics and Biruni Observatory, College of Science, Shiraz (Iran, Islamic Republic of)

    2016-09-15

    In this research article attempts have been made to calculate the superheavy-nuclei synthesis characteristics including, the potential energy parameters, fusion probability, fusion and evaporation residue (ER) cross sections as well as, decay properties of compound nucleus and the residue nuclei formation probability for elements with Z=119-122 by using the hot-fusion reactions. It is concluded that, although a selection of double magic projectiles such as {sup 48}Ca with high binding energy, simplifies the calculations significantly due to spherical symmetric shape of the projectile, resulting in high evaporation residue cross section, unfortunately, nuclei with Z > 98 do not exist in quantities sufficient for constructing targets for the hot-fusion reactions. Therefore, practically our selection is fusion reactions with titanium projectile because the mass production of target nuclei for experimental purposes is more feasible. Based upon our findings, it is necessary, for new superheavy-nuclei production with Z > 119, to use neutron-rich projectiles and target nuclei. Finally, the maximal evaporation residue cross sections for the synthesis of superheavy elements with Z=119-122 have been calculated and compared with the previously founded ones in the literature. (orig.)

  6. Neutron rich clusters and the dynamics of fission and fusion

    International Nuclear Information System (INIS)

    Armbruster, P.

    1988-07-01

    In this lecture I want to discuss experimental evidence for the appearance of cluster aspects in the dynamics of large rearrangement processes, as fusion and fission. Clusters in the sense as used in my lecture are the strongly bound doubly magic nuclei as 20 Ca 28 48 , 28 Ni 50 78 , 132 50 Sn 82 , and 208 82 Pb 126 and the superheavy nucleus 298 114 184 . Two of these nuclei, 78 Ni and 298 114 have not yet been identified. I discuss first the experimental findings from heavy element production. Then I cover the stability of cluster aspects to intrinsic excitation energy in fusion and fission. (orig./HSI)

  7. Stability and production of superheavy nuclei

    International Nuclear Information System (INIS)

    Moeller, P.; Los Alamos National Lab., NM; Nix, J.R.

    1997-01-01

    Beyond uranium heavy elements rapidly become increasingly unstable with respect to spontaneous fission as the proton number Z increases, because of the disruptive effect of the long-range Coulomb force. However, in the region just beyond Z = 100 magic proton and neutron numbers and the associated shell structure enhances nuclear stability sufficient to allow observation of additional nuclei. Some thirty years ago it was speculated that an island of spherical, relatively stable superheavy nuclei would exist near the next doubly magic proton-neutron combination beyond 208 Pb, that is, at proton number Z 114 and neutron number N = 184. Theory and experiment now show that there also exists a rock of stability in the vicinity of Z = 110 and N = 162 between the actinide region, which previously was the end of the peninsula of known elements, and the predicted island of spherical superheavy nuclei slightly southwest of the magic numbers Z = 114 and N = 184. The authors review here the stability properties of the heavy region of nuclei. Just as the decay properties of nuclei in the heavy region depend strongly on shell structure, this structure also dramatically affects the fusion entrance channel. The six most recently discovered new elements were all formed in cold-fusion reactions. They discuss here the effect of the doubly magic structure of the target in cold-fusion reactions on the fusion barrier and on dissipation

  8. Weakly bound structures in neutron rich Si isotopes

    International Nuclear Information System (INIS)

    Singh, D.; Saxena, G.; Yadav, H.L.

    2009-01-01

    Production of radioactive beams have facilitated the nuclear structure studies away from the line of β-stability, especially for the neutron rich drip line nuclei. Theoretical investigations of these nuclei have been carried out by using various approaches viz. few body model or clusters, shell model and mean field theories, both nonrelativistic as well as relativistic mean field (RMF). The advantage of the RMF approach, however, is that in this treatment the spin-orbit interaction is included in a natural way. This is especially advantageous for the description of drip-line nuclei for which the spin-orbit interaction plays an important role. In this communication we report briefly the results of our calculations for the Si isotopes carried out within the framework of RMF + BCS approach

  9. Beta decay rates of neutron-rich nuclei

    Science.gov (United States)

    Marketin, Tomislav; Huther, Lutz; Petković, Jelena; Paar, Nils; Martínez-Pinedo, Gabriel

    2016-06-01

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei. Aside from the astrophysical applications, the results of this calculation can also be employed in the modeling of the electron and antineutrino spectra from nuclear reactors.

  10. Beta decay rates of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Marketin, Tomislav; Petković, Jelena; Paar, Nils; Huther, Lutz; Martínez-Pinedo, Gabriel

    2016-01-01

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei. Aside from the astrophysical applications, the results of this calculation can also be employed in the modeling of the electron and antineutrino spectra from nuclear reactors.

  11. Beta decay rates of neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Marketin, Tomislav, E-mail: marketin@phy.hr; Petković, Jelena; Paar, Nils [Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Huther, Lutz [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); Martínez-Pinedo, Gabriel [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); GSI Helmholtzzentrum für Schwerioneneforschung, Planckstraße 1, 64291 Darmstadt (Germany)

    2016-06-21

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei. Aside from the astrophysical applications, the results of this calculation can also be employed in the modeling of the electron and antineutrino spectra from nuclear reactors.

  12. Beta decay rates of neutron-rich nuclei

    International Nuclear Information System (INIS)

    Marketin, Tomislav; Huther, Lutz; Martínez-Pinedo, Gabriel

    2015-01-01

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. Currently, a single large-scale calculation is available based on a QRPA calculation with a schematic interaction on top of the Finite Range Droplet Model. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei

  13. Beta decay rates of neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Marketin, Tomislav, E-mail: marketin@phy.hr [Department of Physics, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Huther, Lutz [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); Martínez-Pinedo, Gabriel [Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, 64289 Darmstadt (Germany); GSI Helmholtzzentrum für Schwerioneneforschung, Planckstraße 1, 64291 Darmstadt (Germany)

    2015-10-15

    Heavy element nucleosynthesis models involve various properties of thousands of nuclei in order to simulate the intricate details of the process. By necessity, as most of these nuclei cannot be studied in a controlled environment, these models must rely on the nuclear structure models for input. Of all the properties, the beta-decay half-lives are one of the most important ones due to their direct impact on the resulting abundance distributions. Currently, a single large-scale calculation is available based on a QRPA calculation with a schematic interaction on top of the Finite Range Droplet Model. In this study we present the results of a large-scale calculation based on the relativistic nuclear energy density functional, where both the allowed and the first-forbidden transitions are studied in more than 5000 neutron-rich nuclei.

  14. Radiochemical search for neutron-rich isotopes of element 107

    International Nuclear Information System (INIS)

    Schaedel, M.

    1987-01-01

    Recent mass calculations have indicated that there is a region of deformed nuclei around neutron number N=162 that is especially stable against spontaneous fission. Barrier heights of about 5 MeV for Z = 107 nuclides can be extrapolated. To search for new, neutron-rich isotopes of element 107 in radiochemical experiments with 254 Es as a target an on-line chemical separation of element 107 (EKA-Rhenium), especially from the actinide elements is needed. An on-line gas-phase chemistry was developed with the homolog Re based on the volatility of the oxide which is transported in an O 2 containing atmosphere along a temperature gradient in a quartz tube and is condensed onto a thin Ta coated Ni-foil. The authors applied this technique in two series of experiments with their rotating wheel on-line gas-phase chemistry apparatus at the 88-inch cyclotron where they irradiated 254 Es as a target with 93 MeV and 96 MeV 16 O ions to search for 266 107. The assignment of the observed alpha events between 8 and 9 MeV to possibly (1) non actinide contaminants like 212 Po, (2) known isotopes of heavy elements like 261 105, or (3) a new isotope will be discussed

  15. Dipole polarizability of neutron rich nuclei and the symmetry energy

    Energy Technology Data Exchange (ETDEWEB)

    Horvat, Andrea; Johansen, Jacob; Miki, Kenjiro; Schindler, Fabia; Schrock, Philipp [IKP, TU Darmstadt (Germany); Aumann, Thomas [IKP, TU Darmstadt (Germany); GSI, Darmstadt (Germany); Boretzky, Konstanze [GSI, Darmstadt (Germany); Collaboration: R3B-Collaboration

    2015-07-01

    As a part of a systematic investigation of the dipole response of stable up to very neutron rich tin isotopes, nuclear and electromagnetic excitation of {sup 124}Sn-{sup 134}Sn has been investigated at relativistic energies in inverse kinematics induced by carbon and lead targets at the LAND-R3B setup at GSI in Darmstadt. The electric dipole response and the nuclear reaction cross section, total and charge-changing, are obtained from the kinematically complete determination of momenta of all particles on an event by event basis. The dipole polarizability is extracted from the Coulomb excitation interaction channel, in order to make use of relevant correlations of this observable with nuclear matter properties such as the symmetry energy at saturation density (J) and it's slope (L). The systematics of the low-lying ''pygmy'' dipole strength, the giant dipole resonance (GDR) and the neutron skin thickness are determined with respect to increasing isospin asymmetry. This talk also discusses the correlations and sensitivities of these variables and observables obtained within the framework of nuclear energy density functional theory.

  16. The pygmy dipole resonance in neutron-rich nuclei

    International Nuclear Information System (INIS)

    Hung, Nguyen Quang; Kiet, Hoang Anh Tuan; Duc, Huynh Ngoc; Chuong, Nguyen Thi

    2016-01-01

    The pygmy dipole resonance (PDR), which has been observed via the enhancement of the electric dipole strength E 1 of atomic nuclei, is studied within a microscopic collective model. The latter employs the Hartree-Fock (HF) method with effective nucleon-nucleon interactions of the Skyrme types plus the random-phase approximation (RPA). The results of the calculations obtained for various even-even nuclei such as "1"6"-"2"8O, "4"0"-"5"8Ca, "1"0"0"-"1"2"0Sn, and "1"8"2"-"2"1"8Pb show that the PDR is significantly enhanced when the number of neutrons outside the stable core of the nucleus is increased, that is, in the neutron-rich nuclei. As the result, the relative ratio between the energy weighted sum of the strength of the PDR and that of the GDR (giant dipole resonance) does not exceed 4%. The collectivity of the PDR and GDR states will be also discussed. (paper)

  17. Possibilities of production of neutron-rich Md isotopes in multi-nucleon transfer reactions

    Energy Technology Data Exchange (ETDEWEB)

    Mun, Myeong-Hwan; Lee, Young-Ouk [Korea Atomic Energy Research Institue, Daejeon (Korea, Republic of); Adamian, G.G.; Antonenko, N.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation)

    2016-12-15

    The possibilities of production of yet unknown neutron-rich isotopes of Md are explored in several multi-nucleon transfer reactions with actinide targets and stable and radioactive beams. The projectile-target combinations and bombarding energies are suggested to produce new neutron-rich isotopes of Md in future experiments. (orig.)

  18. Production and identification of new, neutron-rich nuclei in the {sup 208}Pb region

    Energy Technology Data Exchange (ETDEWEB)

    Rykaczewski, K. [Oak Ridge National Lab., TN (United States). Physics Div.]|[ISOLDE-CERN, Geneva (Switzerland)]|[Univ. of Warsaw (Poland); Kurpeta, J.; Plochocki, A. [Univ. of Warsaw (Poland)] [and others

    1998-11-01

    The recently developed methods allowing the experimental studies on new neutron-rich nuclei beyond doubly-magic {sup 208}Pb are briefly described. An identification of new neutron-rich isotopes {sup 215}Pb and {sup 217}Bi, and new decay properties of {sup 216}Bi studied by means of a pulsed release element selective technique at PS Booster-ISOLDE are reported.

  19. Production and identification of new, neutron-rich nuclei in the 208Pb region

    International Nuclear Information System (INIS)

    Rykaczewski, K.; Kurpeta, J.; Plochocki, A.; Karny, M.; Szerypo, J.; Evensen, A.-H.; Kugler, E.; Lettry, J.; Ravn, H.; Duppen, P. van; Andreyev, A.; Huyse, M.; Woehr, A.; Jokinen, A.; Aeystoe, J.; Nieminen, A.; Huhta, M.; Ramdhane, M.; Walter, G.; Hoff, P.

    1998-01-01

    The recently developed methods allowing the experimental studies on new neutron-rich nuclei beyond doubly-magic 208 Pb are briefly described. An identification of new neutron-rich isotopes 215 Pb and 217 Bi, and new decay properties of 216 Bi studied by means of a pulsed release element selective technique at PS Booster-ISOLDE are reported

  20. Photo-neutron cross sections for unstable neutron-rich oxygen isotopes

    International Nuclear Information System (INIS)

    Leistenschneider, A.; Aumann, T.; Boretzky, K.

    2001-05-01

    The dipole response of stable and unstable neutron-rich oxygen nuclei of masses A = 17 to A = 22 has been investigated experimentally utilizing electromagnetic excitation in heavy-ion collisions at beam energies around 600 MeV/nucleon. A kinematically complete measurement of the neutron decay channel in inelastic scattering of the secondary beam projectiles from a Pb target was performed. Differential electromagnetic excitation cross sections dσ/dE were derived up to 30 MeV excitation energy. In contrast to stable nuclei, the deduced dipole strength distribution appears to be strongly fragmented and systematically exhibits a considerable fraction of low-lying strength, exhausting up to 12% of the energy-weighted dipole sum rule at excitation energies below 15 MeV. (orig.)

  1. Exploring Neutron-Rich Oxygen Isotopes with MoNA

    International Nuclear Information System (INIS)

    Frank, N.; Gade, A.; Peters, W. A.; Thoennessen, M.; Baumann, T.; Bazin, D.; Lecouey, J.-L.; Scheit, H.; Schiller, A.; Brown, J.; DeYoung, P. A.; Finck, J. E.; Hinnefeld, J.; Howes, R.; Luther, B.

    2007-01-01

    The Modular Neutron Array (MoNA) was used in conjunction with a large-gap dipole magnet (Sweeper) to measure neutron-unbound states in oxygen isotopes close to the neutron dripline. While no excited states were observed in 24 O, a resonance at 45(2) keV above the neutron separation energy was observed in 23 O

  2. Transition probabilities in neutron-rich Se,8684

    Science.gov (United States)

    Litzinger, J.; Blazhev, A.; Dewald, A.; Didierjean, F.; Duchêne, G.; Fransen, C.; Lozeva, R.; Sieja, K.; Verney, D.; de Angelis, G.; Bazzacco, D.; Birkenbach, B.; Bottoni, S.; Bracco, A.; Braunroth, T.; Cederwall, B.; Corradi, L.; Crespi, F. C. L.; Désesquelles, P.; Eberth, J.; Ellinger, E.; Farnea, E.; Fioretto, E.; Gernhäuser, R.; Goasduff, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hackstein, M.; Hess, H.; Ibrahim, F.; Jolie, J.; Jungclaus, A.; Kolos, K.; Korten, W.; Leoni, S.; Lunardi, S.; Maj, A.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Mijatovic, T.; Million, B.; Möller, O.; Modamio, V.; Montagnoli, G.; Montanari, D.; Morales, A. I.; Napoli, D. R.; Niikura, M.; Pollarolo, G.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Rosso, D.; Sahin, E.; Salsac, M. D.; Scarlassara, F.; Söderström, P.-A.; Stefanini, A. M.; Stezowski, O.; Szilner, S.; Theisen, Ch.; Valiente Dobón, J. J.; Vandone, V.; Vogt, A.

    2015-12-01

    Reduced quadrupole transition probabilities for low-lying transitions in neutron-rich Se,8684 are investigated with a recoil distance Doppler shift (RDDS) experiment. The experiment was performed at the Istituto Nazionale di Fisica Nucleare (INFN) Laboratori Nazionali di Legnaro using the Cologne Plunger device for the RDDS technique and the AGATA Demonstrator array for the γ -ray detection coupled to the PRISMA magnetic spectrometer for an event-by-event particle identification. In 86Se the level lifetime of the yrast 21+ state and an upper limit for the lifetime of the 41+ state are determined for the first time. The results of 86Se are in agreement with previously reported predictions of large-scale shell-model calculations using Ni78-I and Ni78-II effective interactions. In addition, intrinsic shape parameters of lowest yrast states in 86Se are calculated. In semimagic 84Se level lifetimes of the yrast 41+ and 61+ states are determined for the first time. Large-scale shell-model calculations using effective interactions Ni78-II, JUN45, jj4b, and jj4pna are performed. The calculations describe B (E 2 ;21+→01+) and B (E 2 ;61+→41+) fairly well and point out problems in reproducing the experimental B (E 2 ;41+→21+) .

  3. Delayed Particle Study of Neutron Rich Lithium Isotopes

    CERN Multimedia

    Marechal, F; Perrot, F

    2002-01-01

    We propose to make a systematic complete coincidence study of $\\beta$-delayed particles from the decay of neutron-rich lithium isotopes. The lithium isotopes with A=9,10,11 have proven to contain a vast information on nuclear structure and especially on the formation of halo nuclei. A mapping of the $\\beta$-strength at high energies in the daughter nucleus will make possible a detailed test of our understanding of their structure. An essential step is the comparison of $\\beta$-strength patterns in $^{11}$Li and the core nucleus $^{9}$Li, another is the full characterization of the break-up processes following the $\\beta$-decay. To enable such a measurement of the full decay process we will use a highly segmented detection system where energy and emission angles of both charged and neutral particles are detected in coincidence and with high efficiency and accuracy. We ask for a total of 30 shifts (21 shifts for $^{11}$Li, 9 shifts $^{9}$Li adding 5 shifts for setting up with stable beam) using a Ta-foil target...

  4. Perspectives of production of superheavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Adamian, G. G.; Antonenko, N. V., E-mail: antonenk@theor.jinr.ru; Bezbakh, A. N.; Sargsyan, V. V. [Joint Institute for Nuclear Research, RU–141980 Dubna (Russian Federation); Scheid, W. [Institut für Theoretische Physik der Justus-Liebig-Universität, D–35392 Giessen (Germany)

    2016-07-07

    Possible ways of production of superheavies are discussed. Impact of nuclear structure on the production of superheavy nuclei in complete fusion reactions is discussed. The proton shell closure at Z = 120 is discussed.

  5. Positron creation in superheavy quasi-molecules

    International Nuclear Information System (INIS)

    Mueller, B.

    1976-01-01

    The review of positron creation in superheavy quasi-molecules includes spontaneous positron emission from superheavy atoms, supercritical quasi-molecules, background effects, and some implications of the new ground state. 66 references

  6. Fission properties of superheavy nuclei for r -process calculations

    Science.gov (United States)

    Giuliani, Samuel A.; Martínez-Pinedo, Gabriel; Robledo, Luis M.

    2018-03-01

    We computed a new set of static fission properties suited for r -process calculations. The potential energy surfaces and collective inertias of 3640 nuclei in the superheavy region are obtained from self-consistent mean-field calculations using the Barcelona-Catania-Paris-Madrid energy density functional. The fission path is computed as a function of the quadrupole moment by minimizing the potential energy and exploring octupole and hexadecapole deformations. The spontaneous fission lifetimes are evaluated employing different schemes for the collective inertias and vibrational energy corrections. This allows us to explore the sensitivity of the lifetimes to those quantities together with the collective ground-state energy along the superheavy landscape. We computed neutron-induced stellar reaction rates relevant for r -process nucleosynthesis using the Hauser-Feshbach statistical approach and study the impact of collective inertias. The competition between different reaction channels including neutron-induced rates, spontaneous fission, and α decay is discussed for typical r -process conditions.

  7. Fusion-fission of superheavy nuclei at low excitation energies

    International Nuclear Information System (INIS)

    Itkis, M.G.; Oganesyan, Yu.Ts.; Kozulin, E.M.

    2000-01-01

    The process of fusion-fission of superheavy nuclei with Z = 102 -122 formed in the reactions with 22 Ne, 26 Mg, 48 Ca, 58 Fe and 86 Kr ions at energies near and below the Coulomb barrier has been studied. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR) using a time-of-flight spectrometer of fission fragments CORSET and a neutron multi-detector DEMON. As a result of the experiments, mass and energy distributions of fission fragments, fission and quasi-fission cross sections, multiplicities of neutrons and gamma-rays and their dependence on the mechanism of formation and decay of compound superheavy systems have been studied

  8. Study of neutron-rich $^{51−53}$ Ca isotopes via $\\beta$-decay

    CERN Multimedia

    The high Q$_\\beta$ values in certain neutron-rich regions of the chart of nuclides opens up the possibility to study states in the daughter nuclei which lie at high excitation energy, above the neutron separation threshold. We propose to perform spectroscopy of the $\\beta$-delayed neutron emission of the $^{51-53}$K isotopes to study the population of single-particle or particle-hole states both below and above the neutron separation threshold. The VANDLE neutron detector will be used in combination with the IDS tape station setup and Ge detectors.

  9. Era of superheavy-particle dominance and big bang nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Polnarev, A.G.; Khlopov, M.Y.

    1982-01-01

    The observed primordial He/sup 4/ abundance imposes astrophysical constraints on the possible departures from radiation dominance in the big bang universe during the neutron hardening era (at epoch t roughly-equal1 sec). Limits are obtained which, along with the data on the spectrum of the cosmic background radiation, practically rule out any stages of superheavy stable-particle dominance in the era 1< or approx. =t<10/sup 10/ sec, thereby setting restrictions on current elementary-particle theories.

  10. Structure of the neutron-rich lithium isotopes in heavy-ion reactions

    International Nuclear Information System (INIS)

    Bespalova, O.V.; Galakhmatova, B.S.; Romanovskij, E.A.; Shitikova, K.V.; Burov, V.V.; Rzyanin, M.V.; Miller, H.G.; Yen, G.D.

    1993-01-01

    The structure properties, for factors, angular distributions and interaction cross sections of Li neutron-rich isotopes have been analyzed in the unified way. A good qualitative agreement with the experiment data was obtained. 20 refs.; 11 figs.; 1 tab

  11. Study of very neutron-rich nuclei produced by means of a 48Ca beam

    International Nuclear Information System (INIS)

    Lewitowicz, M.; Artukh, A.G.

    1991-01-01

    The results of experiments with a 48 Ca beam performed at GANIL are presented and discussed. More than 30 very neutron-rich isotopes were identified or studied for the first time. The evidence for particle-unstable character of the 26 O isotope is reported. Half-life measurements for light neutron rich nuclei are compared with different theoretical predictions. (author) 14 refs.; 6 figs.; 1 tab

  12. Direct mass measurements of light neutron-rich nuclei using fast recoil spectrometers

    International Nuclear Information System (INIS)

    Vieira, D.J.; Wouters, J.M.

    1987-01-01

    Extensive new mass measurement capabilities have evolved with the development of recoil spectrometers. In the Z = 3 to 9 neutron-rich region alone, 12 neutron-rich nuclei have been determined for the first time by the fast-recoil direct mass measurement method. A recent experiment using the TOFI spectrometer illustrates this technique. A systematic investigation of nuclei that lie along or near the neutron-drip line has provided a valuable first glimpse into the nuclear structure of such nuclei. No evidence for a large single-particle energy gap at N = 14 is observed; however, a change in the two-neutron separation model calculations, and is interpreted in terms of the smaller 1s/sub 1/2/ - 1s/sub 1/2/ interaction compared to that of the 0d/sub 5/2/ - 0d/sub 5/2/ neutron-neutron interaction. 18 refs., 7 figs., 1 tab

  13. Stability of superheavy nuclei

    Science.gov (United States)

    Pomorski, K.; Nerlo-Pomorska, B.; Bartel, J.; Schmitt, C.

    2018-03-01

    The potential-energy surfaces of an extended set of heavy and superheavy even-even nuclei with 92 ≤Z ≤126 and isospins 40 ≤N -Z ≤74 are evaluated within the recently developed Fourier shape parametrization. Ground-state and decay properties are studied for 324 different even-even isotopes in a four-dimensional deformation space, defined by nonaxiality, quadrupole, octupole, and hexadecapole degrees of freedom. Nuclear deformation energies are evaluated in the framework of the macroscopic-microscopic approach, with the Lublin-Strasbourg drop model and a Yukawa-folded mean-field potential. The evolution of the ground-state equilibrium shape (and possible isomeric, metastable states) is studied as a function of Z and N . α -decay Q values and half-lives, as well as fission-barrier heights, are deduced. In order to understand the transition from asymmetric to symmetric fission along the Fm isotopic chain, the properties of all identified fission paths are investigated. Good agreement is found with experimental data wherever available. New interesting features about the population of different fission modes for nuclei beyond Fm are predicted.

  14. Structure of light neutron-rich nuclei through Coulomb dissociation

    Indian Academy of Sciences (India)

    The data analysis for Coulomb breakup of. ½ .... C (605 MeV/u) breaking up into a neutron and a .... direct break up model delivers a cross section of 107 mb for a ... separation energy for the last neutron in the even isotopes = 20 to 24 is 7 to 8 ...

  15. Problem of ''deformed'' superheavy nuclei

    International Nuclear Information System (INIS)

    Sobiczewski, A.; Patyk, Z.; Muntian, I.

    2000-08-01

    Problem of experimental confirmation of deformed shapes of superheavy nuclei situated in the neighbourhood of 270 Hs is discussed. Measurement of the energy E 2+ of the lowest 2+ state in even-even species of these nuclei is considered as a method for this confirmation. The energy is calculated in the cranking approximation for heavy and superheavy nuclei. The branching ratio p 2+ /p 0+ between α decay of a nucleus to this lowest 2+ state and to the ground state 0+ of its daughter is also calculated for these nuclei. The results indicate that a measurement of the energy E 2+ for some superheavy nuclei by electron or α spectroscopy is a promising method for the confirmation of their deformed shapes. (orig.)

  16. Are there superheavy atomic nuclei

    International Nuclear Information System (INIS)

    Herrmann, G.

    1982-04-01

    The author presents a populary introduction to the formation of nuclei with special regards to superheavy nuclei. After a general description of the methods of physics the atomic hypothesis is considered. Thereafter the structure of the nucleus is discussed, and the different isotopes are considered. Then radioactivity is described as an element transmutation. Thereafter the thermonuclear reactions in the sun are considered. Then the synthesis of elements using heavy ion reactions is described. In this connection the transuranium elements and the superheavy elements are considered. (orig./HSI) [de

  17. Nucleosynthesis of neutron-rich heavy nuclei during explosive helium burning in massive stars

    International Nuclear Information System (INIS)

    Blake, J.B.; Woosley, S.E.; Weaver, T.A.; Schramm, D.N.

    1981-01-01

    The production of heavy nuclei during explosive helium burning has been calculated using a hydrodynamical model of a 15 M/sub sun/ (Type II) supernovae and a n-process nuclear reaction network. The resulting neutron-rich heavy nuclei are not produced in the relative abundances of solar-system r-process material, especially in the vicinity of Pt, nor are any actinides produced. These deficiencies reflect an inadequate supply of neutrons. However, some neutron-rich isotopes, normally associated with the r-process, are produced which may be significant for the production of isotopic anomalies in meteorites

  18. Constraining the EOS of Neutron-Rich Nuclear Matter and Properties of Neutron Stars with Heavy-Ion Reactions

    International Nuclear Information System (INIS)

    Li Baoan; Worley, Aaron; Chen, L.-W.; Ko, Che Ming; Krastev, Plamen G.; Wen Dehua; Xiao Zhigang; Zhang Ming; Xu Jun; Yong Gaochan

    2009-01-01

    Heavy-ion reactions especially those induced by radioactive beams provide useful information about the density dependence of the nuclear symmetry energy, thus the Equation of State of neutron-rich nuclear matter, relevant for many astrophysical studies. The latest developments in constraining the symmetry energy at both sub- and supra-saturation densities from analyses of the isopsin diffusion and the π - /π + ratio in heavy-ion collisions using the IBUU04 transport model are discussed. Astrophysical ramifications of the partially constrained symmetry energy on properties of neutron star crusts, gravitational waves emitted by deformed pulsars and the w-mode oscillations of neutron stars are presented briefly.

  19. Spectroscopy of neutron rich nuclei using cold neutron induced fission of actinide targets at the ILL: the EXILL campaign

    Directory of Open Access Journals (Sweden)

    de France G.

    2014-03-01

    Full Text Available A combination of germanium detectors has been installed at the PF1B neutron guide of the ILL to perform the prompt spectroscopy of neutron-rich nuclei produced in the neutron-capture induced-fission of 235U and 241Pu. In addition LaBr3 detectors from the FATIMA collaboration have been installed in complement with the EXOGAM clovers to measure lifetimes of low-lying excited states. The measured characteristics and online spectra indicate very good performances of the overall setup.

  20. Single-Particle Structure of Neutron-Rich Nuclei

    International Nuclear Information System (INIS)

    Cizewski, Jolie; Jones, K.L.; Thomas, J.S.; Bardayan, Daniel W.; Blackmon, Jeff C.; Gross, Carl J.; Liang, J. Felix; Shapira, Dan; Smith, Michael Scott; Stracener, Daniel W.; Kozub, R.L.; Nesaraja, Caroline D.; Greife, U.; Livesay, Jake; Ma, Zhanwen

    2004-01-01

    Neutron transfer (d,p) reactions have been measured with rare isotope beams of 132Sn, 130Sn and 134Te accelerated to ∼4.5 MeV/u interacting with CD2 targets. Reaction protons were detected in an early implementation of the ORRUBA array of position-sensitive silicon strip detectors. Neutron excitations in the 2f7/2, 3p3/2, 3p1/2 and 2f5/2 orbitals were populated.

  1. Decay Studies of Very Neutron Rich Nuclei near 78Ni

    International Nuclear Information System (INIS)

    Winger, J. A.; Ilyushkin, S.; Korgul, A.; Gross, Carl J; Rykaczewski, Krzysztof Piotr; Batchelder, J. C.; Goodin, C.; Grzywacz, R.; Hamilton, J. H.; Krolas, W.; Liddick, Sean; Mazzocchi, C.; Nelson, C.; Padgett, Stephen; Piechaczek, A.; Rajabali, M. M.; Shapira, Dan; Zganjar, E. F.

    2008-01-01

    The properties of beta-gamma and beta-delayed neutron emission from 76-79 Cu and 83-85 Ga were measured at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory. Selected results on the decay properties of copper isotopes are briefly presented and discussed

  2. Goodness of isospin in neutron rich systems from the fission fragment distribution

    Science.gov (United States)

    Garg, Swati; Jain, Ashok Kumar

    2017-09-01

    We present the results of our calculations for the relative yields of neutron-rich fission fragments emitted in 208Pb (18O, fission) reaction by using the concept of the conservation of isospin and compare with the experimental data. We take into account a range of isospin values allowed by the isospin algebra and assume that the fission fragments are formed in isobaric analog states. We also take into account the neutron multiplicity data for various neutron-emission channels in each partition, and use them to obtain the weight factors in calculating the yields. We then calculate the relative yields of the fission fragments. Our calculated results are able to reproduce the experimental trends reasonably well. This is the first direct evidence of the isospin conservation in neutron-rich systems and may prove a very useful tool in their studies.

  3. Measurement of total reaction cross sections of exotic neutron rich nuclei

    International Nuclear Information System (INIS)

    Mittig, W.; Chouvel, J.M.; Wen Long, Z.

    1987-01-01

    Total reaction cross-sections of neutron rich nuclei from C to Mg in a thick Si-target have been measured using the detection of the associated γ-rays in a 4Π-geometry. This cross-section strongly increases with neutron excess, indicating an increase of as much as 15% of the reduced strong absorption radius with respect to stable nuclei

  4. Radioactivity of neutron rich oxygen, fluorine and neon isotopes

    International Nuclear Information System (INIS)

    Reed, A.T.; Page, R.D.; Tarasov, O.

    1999-01-01

    The γ-radiation and neutrons emitted following the β-decays of 24 O, 25-27 F and 28-30 Ne have been measured. The nuclides were produced in the quasi-fragmentation of a 78 MeV/A 36 S beam, separated in-flight and identified through time-of-flight and energy loss measurements. The ions were stopped in a silicon detector system, which was used to detect the β-particles emitted in their subsequent radioactive decay. The coincident γ-rays were measured using four large Ge detectors mounted close to the implantation point and the neutrons were detected using forty-two 3 He proportional counters. The measured γ-ray energy spectra are compared with shell model calculations and, where available, the level energies are deduced from transfer reactions

  5. Investigation of correlations in light neutron-rich nuclei

    International Nuclear Information System (INIS)

    Normand, G.

    2004-10-01

    Correlations play a crucial role in understanding the structure of light nuclei at and beyond the neutron drip-line. In this context, the two-neutron halo nucleus He 6 and the unbound systems H 5 , He 7,9 and Li 10 have been studied via measurements of the breakup of beams of He 6 and Be 11,12 . The CHARISSA and DEMON detector arrays were employed. The interpretation was facilitated by a simulation code (SILLAGE) which provided for the setup. In the case of He 7 , the existence of an excited state with E r ∼ 1 MeV and gamma ∼ 0.75 MeV was confirmed. The virtual character of the s-wave ground state of Li 10 was also confirmed and a scattering length of as ∼ -16 fm deduced. The results obtained for He 9 suggest that a virtual s-wave state may exist just above threshold. The study of the three-body breakup of He 6 found that the decay of the first 2+ state is essentially direct, while the decay of the remaining continuum strength is sequential - passage via He 5 . Using the technique of intensity interferometry an rms separation between the halo neutrons of 7.7 +- 0.8 fm was derived. This result was confirmed by a complementary method utilizing Dalitz plots. In the case of H 5 , the invariant mass spectrum was found to exhibit a broad (gamma ∼ 2 MeV) structure some 1.8 MeV above threshold. Comparison with recent three-body model calculations suggest that this corresponds to the predicted 1/2+ ground state. An rms valence neutron separation of some 5.5 fm was estimated. A search was also carried out for the 4n system using the Be 12* (2 alpha + Xn decay channel). No signal was observed beyond that expected on the basis of the known background processes. (author)

  6. Laser-spectroscopy studies of the nuclear structure of neutron-rich radium

    Science.gov (United States)

    Lynch, K. M.; Wilkins, S. G.; Billowes, J.; Binnersley, C. L.; Bissell, M. L.; Chrysalidis, K.; Cocolios, T. E.; Goodacre, T. Day; de Groote, R. P.; Farooq-Smith, G. J.; Fedorov, D. V.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Gins, W.; Heinke, R.; Koszorús, Á.; Marsh, B. A.; Molkanov, P. L.; Naubereit, P.; Neyens, G.; Ricketts, C. M.; Rothe, S.; Seiffert, C.; Seliverstov, M. D.; Stroke, H. H.; Studer, D.; Vernon, A. R.; Wendt, K. D. A.; Yang, X. F.

    2018-02-01

    The neutron-rich radium isotopes, Ra-233222, were measured with Collinear Resonance Ionization Spectroscopy (CRIS) at the ISOLDE facility, CERN. The hyperfine structure of the 7 s2S10→7 s 7 p P31 transition was probed, allowing measurement of the magnetic moments, quadrupole moments, and changes in mean-square charge radii. These results are compared to existing literature values, and the new moments and change in mean-square charge radii of 231Ra are presented. Low-resolution laser spectroscopy of the very neutron-rich 233Ra has allowed the isotope shift and relative charge radius to be determined for the first time.

  7. K isomerism and collectivity in neutron-rich rare-earth isotopes.

    OpenAIRE

    Patel, Zena

    2016-01-01

    Neutron-rich rare-earth isotopes were produced by in-flight fission of 238U ions at the Radioactive Isotope Beam Factory (RIBF), RIKEN, Japan. In-flight fission of a heavy, high-intensity beam of 238U ions on a light target provides the cleanest secondary beams of neutron-rich nuclei in the rare-earth region of isotopes. In-flight fission is advantageous over other methods of nuclear production, as it allows for a secondary beam to be extracted, from which the beam species can be separated an...

  8. Detection of the weak γ activities from new neutron-rich nuclei

    International Nuclear Information System (INIS)

    Zhang Li; Wang Jicheng; Zhao Jinhua; Yang Yongfeng; Zheng Jiwen; Hu Qingyuan; Guo Tianrui

    2003-01-01

    Energic signals of γ rays detected by a HPGe γ detector were coincided with γ-ray, energy-loss signals detected by a 4πΔEβ detector. Then the coinciding β-ray spectra was anticoincided with timing logical signals of 511 keV γ ray created in positron annihilate, detected by a large BGO detector. This special coincidence-anticoincidence system has played an important role in the first observation of the new neutron-rich nuclide 209 Hg. It is shown that this is an effective method to detecting very weak γ-ray activities of neutron-rich isotope in an element-separation sample

  9. Study of subshell gap around N = 70 for neutron-rich nuclei

    International Nuclear Information System (INIS)

    Hemalatha, M.

    2011-01-01

    The study and search for new regions of shell closure for nuclei away from stability is a topic of current interest both experimentally and theoretically. There have been few studies predicting a weak spherical subshell gap of 110 Zr (N = 70), for example. This is supported by a recent study indicating that the spherical N = 70 shell gap may not have a large effect at N = 68 for Zr isotopes. It would be, therefore, interesting to know whether there is a subshell closure at N = 70 in the neutron rich region and also for the very neutron-rich nuclei, 110 Zr

  10. Light neutron-rich hypernuclei from the importance-truncated no-core shell model

    Directory of Open Access Journals (Sweden)

    Roland Wirth

    2018-04-01

    Full Text Available We explore the systematics of ground-state and excitation energies in singly-strange hypernuclei throughout the helium and lithium isotopic chains — from HeΛ5 to HeΛ11 and from LiΛ7 to LiΛ12 — in the ab initio no-core shell model with importance truncation. All calculations are based on two- and three-baryon interaction from chiral effective field theory and we employ a similarity renormalization group transformation consistently up to the three-baryon level to improve the model-space convergence. While the absolute energies of hypernuclear states show a systematic variation with the regulator cutoff of the hyperon–nucleon interaction, the resulting neutron separation energies are very stable and in good agreement with available data for both nucleonic parents and their daughter hypernuclei. We provide predictions for the neutron separation energies and the spectra of neutron-rich hypernuclei that have not yet been observed experimentally. Furthermore, we find that the neutron drip lines in the helium and lithium isotopic chains are not changed by the addition of a hyperon. Keywords: Hypernuclei, Ab-initio methods, Neutron-rich nuclei, Neutron separation energies, Neutron drip line

  11. Nuclear reactions of neutron-rich Sn isotopes investigated at relativistic energies at R{sup 3}B

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Fabia; Aumann, Thomas; Horvat, Andrea [TU Darmstadt (Germany); Boretzky, Konstanze [GSI Helmholtzzentrum (Germany); Schrock, Philipp [CNS, University of Tokyo (Japan); Johansen, Jacob [Aarhus University (Denmark); Collaboration: R3B-Collaboration

    2016-07-01

    Nuclei with a large neutron excess are expected to form a neutron-rich surface layer which is often referred to as the neutron skin. The investigation of this phenomenon is of great interest in nuclear-structure physics and offers a possibility to constrain the equation-of-state of neutron-rich matter. Assuming a geometrical description of reaction processes as in the eikonal approximation, nuclear-induced reactions are a good tool to probe the neutron skin. Measured reaction cross sections can be used to constrain the density distributions of protons and neutrons in the nucleus and therefore the neutron-skin thickness. For this purpose, reactions of neutron-rich tin isotopes in the A=124-134 mass range have been measured on a carbon target at the R{sup 3}B-setup at GSI in inverse kinematics in a kinematically complete manner. Preliminary results for the reaction cross sections of {sup 124}Sn are presented.

  12. Identification of new neutron-rich actinide isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Oura, Yasuji; Sakama, Minoru; Ohyama, T. [Tokyo Metropolitan Univ. (Japan)] [and others

    1999-10-01

    To advance research on new neutron-deficient actinide isotopes using an on-line isotope separator combined with a gas-jet injector installed in the JAERI Tandem accelerator, Tokai, performance test of the equipment was carried out. Efficiency of the product isotopes being transported from the target chamber to the measuring system was greatly improved by employing lead iodides (PbI{sub 2}) as the aerosol carrier. With the help of this technique, the authors succeeded in synthesizing and identifying actinide isotopes, {sup 235}Am and {sup 236}Am, and measured their alpha-decay half-life. (S. Ohno)

  13. Asymptotic giant branch stars as producers of carbon and of neutron-rich isotopes

    International Nuclear Information System (INIS)

    Iben, I. Jr.

    1984-01-01

    Carbon stars are thought to be in the asymptotic giant branch (AGB) phase of evolution, alternately burning hydrogen and helium in shells above an electron-degenerate carbon-oxygen (CO) core. The excess of carbon relative to oxygen at the surfaces of these stars is thought to be due to convective dredge-up which occurs following a thermal pulse. During a thermal pulse, carbon and neutron-rich isotopes are made in a convective helium-burning zone. In model stars of large CO core mass, the source of neutrons for producing the neutron-rich isotopes is the 22 Ne(α,n) 25 Mg reaction and the isotopes are produced in the solar system s-process distribution. In models of small core mass, the 13 C(α,n) 16 reaction is thought to be responsible for the release of neutrons, and the resultant distribution of neutron-rich isotopes is expected to vary considerably from one star to the next, with the distribution in isolated instances possibly resembling the solar system distribution of r-process isotopes

  14. GALS – setup for production and study of heavy neutron rich nuclei

    Directory of Open Access Journals (Sweden)

    Zemlyanoy Sergey

    2015-01-01

    Full Text Available The present limits of the upper part of the nuclear map are very close to stability while the unexplored area of heavy neutron-rich nuclides along the neutron closed shell N = 126 below 208Pb is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleosynthesis. This area of the nuclear map can be reached neither in fusion–fission reactions nor in fragmentation processes widely used nowadays for the production of exotic nuclei. A new way was recently proposed for the production of these nuclei via low-energy multi-nucleon transfer reactions. The estimated yields of neutron-rich nuclei are found to be significantly high in such reactions and several tens of new nuclides can be produced, for example, in the near-barrier collision of 136Xe with 208Pb. A new setup is proposed to produce and study heavy neutron-rich nuclei located along the neutron closed shell N=126.

  15. GALS – setup for production and study of heavy neutron rich nuclei

    CERN Document Server

    Zemlyanoy, Sergey; Kozulin, Eduard; Kudryavtsev, Yury; Fedosseev, Valentin; Bark, Robert; Janas, Zenon; Othman, Hosam

    2015-01-01

    The present limits of the upper part of the nuclear map are very close to stability while the unexplored area of heavy neutron-rich nuclides along the neutron closed shell N = 126 below ^208Pb is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleosynthesis. This area of the nuclear map can be reached neither in fusion-fission reactions nor in fragmentation processes widely used nowadays for the production of exotic nuclei. A new way was recently proposed for the production of these nuclei via low-energy multi-nucleon transfer reactions. The estimated yields of neutron-rich nuclei are found to be significantly high in such reactions and several tens of new nuclides can be produced, for example, in the near-barrier collision of ^136Xe with ^208Pb. A new setup is proposed to produce and study heavy neutron-rich nuclei located along the neutron closed shell N=126.

  16. Examination of different strengths of octupole correlations in neutron-rich Pr and Pm isotopes

    Czech Academy of Sciences Publication Activity Database

    Thiamova, G.; Alexa, P.; Hons, Zdeněk; Simpson, G.S.

    2012-01-01

    Roč. 86, č. 4 (2012), 044334/1-044334/5 ISSN 0556-2813 R&D Projects: GA ČR GAP203/10/0310 Institutional support: RVO:61389005 Keywords : neutron rich nuclei * octupole correlations Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.715, year: 2012

  17. Beta spectroscopy on neutron-rich nuclei of mass 93<=A<=100

    International Nuclear Information System (INIS)

    Pahlmann, B.

    1982-01-01

    In the present thesis for the first time measurements of the Qsub(β) value of the neutron-rich fission products sup(99,100)Sr and 99 Rb were performed. Preliminary results could be obtained on the beta decays of the nuclides 100 Rb and 100 Y. (orig./HSI) [de

  18. Production of neutron-rich nuclei at 200 MeV/nucleon

    International Nuclear Information System (INIS)

    Symons, T.J.M.

    1979-01-01

    Ways that heavy ion accelerators have been used to produce neutron rich isotopes are discussed. These include: fusion-evaporation reactions; transfer reactions; deep-inelastic scattering; and heavy ion fragmentation. Experiments using beams of 40 Ar and 48 Ca at 205 MeV/nucleon and 212 MeV/nucleon respectively, are described

  19. Neutron roton pairing effect on some even ven rare-earth proton-rich nuclei

    International Nuclear Information System (INIS)

    Mokhtari, D.

    2004-01-01

    The neutron roton pairing effect on some even ven rare-earth proton-rich nuclei is studied. It is taken into account, in the isovector case, within the framework of the generalized Bogoliubov-Valatin transformation, using Woods-Saxon single-particle energies. (author)

  20. Nuclear structure far from stability: the neutron-rich 69-79Cu isotopes

    International Nuclear Information System (INIS)

    Franchoo, Serge

    2015-01-01

    Far from stability, the nuclear structure that is predicted by the shell model is evolving. Old magic numbers disappear, while new ones appear. Our understanding of the underlying nuclear force that drives these changes is still incomplete. After a short overview across the nuclear chart, we discuss the strength functions of the shell-model orbitals in the neutron-rich copper isotopes towards the 78 Ni doubly-magic nucleus. These were measured in a 72 Zn(d, 3 He) 71 Cu proton pick-up reaction in inverse kinematics with a radioactive beam at the Ganil laboratory in France. We also present the latest results from a 80 Zn(p,2p) 79 Cu knockout experiment at Riken in Japan, leading to selective population of hole states in 79 Cu. Our findings show that the Z=28 shell gap in the neutron-rich copper isotopes is surprisingly steady against the addition of neutrons beyond N=40. (author)

  1. Investigation of correlations in light neutron-rich nuclei; Etude des correlations dans les noyaux legers riches en neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Normand, G

    2004-10-01

    Correlations play a crucial role in understanding the structure of light nuclei at and beyond the neutron drip-line. In this context, the two-neutron halo nucleus He{sup 6} and the unbound systems H{sup 5}, He{sup 7,9} and Li{sup 10} have been studied via measurements of the breakup of beams of He{sup 6} and Be{sup 11,12}. The CHARISSA and DEMON detector arrays were employed. The interpretation was facilitated by a simulation code (SILLAGE) which provided for the setup. In the case of He{sup 7}, the existence of an excited state with E{sub r} {approx} 1 MeV and gamma {approx} 0.75 MeV was confirmed. The virtual character of the s-wave ground state of Li{sup 10} was also confirmed and a scattering length of as {approx} -16 fm deduced. The results obtained for He{sup 9} suggest that a virtual s-wave state may exist just above threshold. The study of the three-body breakup of He{sup 6} found that the decay of the first 2+ state is essentially direct, while the decay of the remaining continuum strength is sequential - passage via He{sup 5}. Using the technique of intensity interferometry an rms separation between the halo neutrons of 7.7 +- 0.8 fm was derived. This result was confirmed by a complementary method utilizing Dalitz plots. In the case of H{sup 5}, the invariant mass spectrum was found to exhibit a broad (gamma {approx} 2 MeV) structure some 1.8 MeV above threshold. Comparison with recent three-body model calculations suggest that this corresponds to the predicted 1/2+ ground state. An rms valence neutron separation of some 5.5 fm was estimated. A search was also carried out for the 4n system using the Be{sup 12*} (2 alpha + Xn decay channel). No signal was observed beyond that expected on the basis of the known background processes. (author)

  2. Coulomb Excitation of Neutron-Rich $A\\approx$140 Nuclei

    CERN Multimedia

    Van duppen, P L E

    2002-01-01

    Investigating the isospin dependence of the product between the B( E2; 0$_{1}^{+} \\rightarrow 2_{1}^{+}$)-value and the 2$_{1}^{+}$-excitation energy E$_{2^{+}}$ in even-even nuclei around $A\\!\\approx$140 one observes a rather smooth trend close to the valley of stability but clear indication for a reduction from the extrapolated B(E2)-values by one order of magnitude for some very neutron-rich nuclei. While close to the valley of stability the strong neutron-proton interaction results in an equilibration of the neutron and proton deformations with a predominate isoscalar character of the collective 2$^{+}$ excitation, it is conceivable that more loosely bound neutrons cannot polarize a close-to-magic proton core that well any more. This might result in a decoupling of the shape of the outer neutrons from the core and in a strong isovector admixture to the lowest lying 2$^{+}$ level. In this way the 2$^{+}$ -energies could be further lowered in neutron-rich nuclei, while the quadrupole moments of the proton c...

  3. Superheavy Nuclei in the Quark-Meson-Coupling Model

    Directory of Open Access Journals (Sweden)

    Stone Jirina

    2017-01-01

    Full Text Available We present a selection of the first results obtained in a comprehensive calculation of ground state properties of even-even superheavy nuclei in the region of 96 < Z < 136 and 118 < N < 320 from the Quark-Meson-Coupling model (QMC. Ground state binding energies, the neutron and proton number dependence of quadrupole deformations and Qα values are reported for even-even nuclei with 100 < Z < 136 and compared with available experimental data and predictions of macro-microscopic models. Predictions of properties of nuclei, including Qα values, relevant for planning future experiments are presented.

  4. Superheavy nuclei in the relativistic mean-field theory

    International Nuclear Information System (INIS)

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

    1996-01-01

    We have carried out a study of superheavy nuclei in the framework of the relativistic mean-field theory. Relativistic Hartree-Bogoliubov (RHB) calculations have been performed for nuclei with large proton and neutron numbers. A finite-range pairing force of Gogny type has been used in the RHB calculations. The ground-state properties of very heavy nuclei with atomic numbers Z=100-114 and neutron numbers N=154-190 have been obtained. The results show that in addition to N=184 the neutron numbers N=160 and N=166 exhibit an extra stability as compared to their neighbors. For the case of protons the atomic number Z=106 is shown to demonstrate a closed-shell behavior in the region of well deformed nuclei about N=160. The proton number Z=114 also indicates a shell closure. Indications for a doubly magic character at Z=106 and N=160 are observed. Implications of shell closures on a possible synthesis of superheavy nuclei are discussed. (orig.)

  5. Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons; Etude de la production de faisceaux riches en neutrons par fission induite par neutrons rapides

    Energy Technology Data Exchange (ETDEWEB)

    Lau, Ch

    2000-09-15

    This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons.

  6. Fission barriers of superheavy nuclei

    International Nuclear Information System (INIS)

    Burvenich, T.

    2001-01-01

    Full text: Self consistent microscopic mean-field models are powerful tools for the description of nuclear structure phenomena in the region of known elements, where they have reached a good quality. Especially the Skyrme-Hartree-Fock (SHF) method and the Relativistic Mean-Field (RMF) model will be considered in the discussion of the properties of these models. When it comes to extrapolation to the region of superheavy elements, though there is agreement concerning the global trends, these model exhibit significant differences in their predictions concerning fission barrier heights and structures. (Author)

  7. β decay and isomeric properties of neutron-rich Ca and Sc isotopes

    International Nuclear Information System (INIS)

    Crawford, H. L.; Mantica, P. F.; Berryman, J. S.; Stoker, J. B.; Janssens, R. V. F.; Carpenter, M. P.; Kay, B. P.; Lauritsen, T.; Zhu, S.; Broda, R.; Cieplicka, N.; Fornal, B.; Grinyer, G. F.; Minamisono, K.; Hoteling, N.; Stefanescu, I.; Walters, W. B.

    2010-01-01

    The isomeric and β-decay properties of neutron-rich 53-57 Sc and 53,54 Ca nuclei near neutron number N=32 are reported, and the low-energy level schemes of 53,54,56 Sc and 53-57 Ti are presented. The low-energy level structures of the 21 Sc isotopes are discussed in terms of the coupling of the valence 1f 7/2 proton to states in the corresponding 20 Ca cores. Implications with respect to the robustness of the N=32 subshell closure are discussed, as well as the repercussions for a possible N=34 subshell closure.

  8. High-accuracy mass measurements of neutron-rich Kr isotopes

    CERN Document Server

    Delahaye, P; Blaum, K; Carrel, F; George, S; Herfurth, F; Herlert, A; Kellerbauer, A G; Kluge, H J; Lunney, D; Schweikhard, L; Yazidjian, C

    2006-01-01

    The atomic masses of the neutron-rich krypton isotopes 84,86-95Kr have been determined with the tandem Penning trap mass spectrometer ISOLTRAP with uncertainties ranging from 20 to 220 ppb. The masses of the short-lived isotopes 94Kr and 95Kr were measured for the first time. The masses of the radioactive nuclides 89Kr and 91Kr disagree by 4 and 6 standard deviations, respectively, from the present Atomic-Mass Evaluation database. The resulting modification of the mass surface with respect to the two-neutron separation energies as well as implications for mass models and stellar nucleosynthesis are discussed.

  9. Ground-state configuration of neutron-rich Aluminum isotopes through Coulomb Breakup

    Directory of Open Access Journals (Sweden)

    Chakraborty S.

    2014-03-01

    Full Text Available Neutron-rich 34,35Al isotopes have been studied through Coulomb excitation using LAND-FRS setup at GSI, Darmstadt. The method of invariant mass analysis has been used to reconstruct the excitation energy of the nucleus prior to decay. Comparison of experimental CD cross-section with direct breakup model calculation with neutron in p3/2 orbital favours 34Al(g.s⊗νp3/2 as ground state configuration of 35Al. But ground state configuration of 34Al is complicated as evident from γ-ray spectra of 33Al after Coulomb breakup of 34Al.

  10. Mass measurements of neutron rich isotopes in the Fe region and electron capture processes in neutron star crusts

    International Nuclear Information System (INIS)

    Estrade, Alfredo; Matos, M.; Schatz, Hendrik; Amthor, A.M.; Beard, Mary; Brown, Edward; Bazin, D.; Becerril, A.; Elliot, T.; Gade, A.; Galaviz, D.; Gupta, Sanjib; Hix, William Raphael; Lau, Rita; Moeller, Peter; Pereira, J.; Portillo, M.; Rogers, A.M.; Shapira, Dan; Smith, E.; Stolz, A.; Wallace, M.; Wiescher, Michael

    2011-01-01

    Experimental knowledge of nuclear masses of exotic nuclei is important for understanding nuclear structure far from the valley of stability, and as a direct input into astrophysical models. Electron capture processes in the crust of accreting neutron stars have been proposed as a heat source that can affect the thermal structure of the star. Nuclear masses of very neutron-rich nuclides are necessary inputs to model the electron capture process. The time-of-flight (TOF) mass measurement technique allows measurements on very short-lived nuclei. It has been effectively applied using the fast fragment beams produced at the National Superconducting Cyclotron Lab (NSCL) to reach masses very far from stability. Measurements were performed for neutron-rich isotopes in the region of the N=32 and N=40 subshells, which coincides with the mass range of carbon superburst ashes. We discuss reaction network calculations performed to investigate the impact of our new measurements and to compare the effect of using different global mass models in the calculations. It is observed that the process is sensitive to the differences in the odd-even mass staggering predicted by the mass models, and our new result for 66Mn has a significant impact on the distribution of heat sources in the crust.

  11. The Peculiarities of the Production and Decay of Superheavy Nuclei

    International Nuclear Information System (INIS)

    Itkis, M. G.; Bogachev, A. A.; Itkis, I. M.; Jandel, M.; Kliman, J.; Knyazheva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Prokhorova, E. V.; Rusanov, A. Ya.; Sagaidak, R. N.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Behera, B. R.; Corradi, L.; Fioretto, E.

    2006-01-01

    The interest in the study of the fission process of superheavy nuclei mainly deals with the opportunity to obtain information about the cross-section of the compound nucleus (CN) formation at excitation energies E*≅15-30 MeV. It allows one to estimate the survival probability of the superheavy composite system after evaporation of 1-3 neutrons, i.e. in 'cold' or 'warm' fusion reactions. However, in order to solve this problem deeper understanding of the coalescence processes between colliding nuclei, the competition between fusion-fission and quasi-fission processes is needed. The characteristics of both processes, their manifestation in the experimental observables and the relative contribution to the capture cross-section in dependence on the excitation energies, reaction entrance channel etc were investigated for a wide range of target-projectile combinations. Results of the experiments devoted to the study of the fusion-fission and quasi-fission processes in the reactions of the formation of the superheavy nuclei with Z = 102-122 are presented. The heavy ions 26Mg, 48Ca, 50Ti, 58Fe and 64Ni were used as projectiles. The choice of the reactions with 48Ca and actinide-targets was inspired by the experiments on the production of the isotopes 283112, 289114 and 283116 in Dubna using the same reactions. The 50Ti, 58Fe and 64Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia) and the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) using the time-of-flight spectrometer of fission fragments CORSET. The role of the shell effects, the influence of the entrance channel asymmetry and the deformations of colliding nuclei on the mechanism of the fusion-fission and the competitive process of quasi-fission are discussed. The recent results on synthesis of

  12. Synthesis and properties of superheavy elements

    CERN Document Server

    Hofmann, S

    2003-01-01

    The nuclear shell model predicts that the next doubly magic shell-closure beyond sup 2 sup 0 sup 8 Pb is at a proton number Z = 114, 120, or 126 and at a neutron number N = 172 or 184. The outstanding of experimental investigations is the exploration of this region of spherical 'SuperHeavy Elements' (SHEs). Experimental methods are described which allowed for the identification of elements 107 to 112 in studies of cold fusion reactions based on lead and bismuth targets. Also presented are data which were obtained on the synthesis of elements 112, 114, and 116 in investigation of hot fusion reactions using actinide targets. The decay data reveal that for the heaviest elements, the dominant decay mode is alpha emission, not fission. Decay properties as well as reaction cross- sections are compared with the results of theoretical studies. Finally, plans are presented for the further development of the experimental set-up and the application of new techniques. At a higher sensitivity, the exploration of the regio...

  13. Study of the production of neutron-rich isotope beams issuing from fissions induced by fast neutrons

    International Nuclear Information System (INIS)

    Lau, Ch.

    2000-01-01

    This work is a contribution to the PARRNe project (production of radioactive neutron-rich isotopes). This project is based on the fission fragments coming from the fission of 238-uranium induced by fast neutrons. The fast neutron flux is produced by the collisions of deutons in a converter. Thick targets of uranium carbide and liquid uranium targets have been designed in order to allow a quick release of fission fragments. A device, able to trap on a cryogenic thimble rare gas released by the target, has allowed the production of radioactive nuclei whose half-life is about 1 second. This installation has been settled to different deuton accelerators in the framework of the European collaboration SPIRAL-2. A calibration experiment has proved the feasibility of fixing an ISOL-type isotope separator to a 15 MV tandem accelerator, this installation can provide 500 nA deutons beams whose energy is 26 MeV and be a valuable tool for studying fast-neutron induced fission. Zinc, krypton, rubidium, cadmium, iodine, xenon and cesium beams have been produced in this installation. The most intense beams reach 10000 nuclei by micro-coulomb for 26 MeV deutons. An extra gain of 2 magnitude orders can be obtained by using a more specific ion source and by increasing the thickness of the target. Another extra gain of 2 magnitude orders involves 100 MeV deutons

  14. Search for low lying dipole strength in the neutron rich nucleus Ne{sup 26}

    Energy Technology Data Exchange (ETDEWEB)

    Gibelin, J

    2005-11-15

    We carried out the Coulomb excitation, on a lead target, of an exotic beam of neutron-rich nucleus Ne{sup 26} at 58 MeV/n, in order to study the possible existence of a pygmy dipole resonance above the neutron emission threshold. The experiment was performed at the Riken Research Facility, in Tokyo (Japan) and included a gamma-ray detector, a charged fragment hodoscope and a neutron detector. Using the invariant mass method in the Ne{sup 25} + n decay channel, and by comparing the reaction cross section on the lead target and a light target of aluminum, we observe a sizable amount of E1 strength between the one neutron and the two neutron emission thresholds. The corresponding Ne{sup 26} angular distribution confirms its nature and we deduce its reduced dipole transition probability value of B(E1) = 0.54 {+-} 0.18 e{sup 2}fm{sup 2}. Our method also enables us to extract for the first time the decay pattern of a pygmy resonance. By detecting the decay photons from the excited states below the neutron emission threshold and by analyzing the angular distribution of the inelastically scattered Ne{sup 26} we deduce the reduced transition probability of the first 2{sup +} state, from the ground state. The value obtained of B(E2) = 87 {+-} 13 e{sup 2}fm{sup 4} being in disagreement with a previous result. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Gaidarov, M. K.; Antonov, A. N. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Sarriguren, P. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Moya de Guerra, E. [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

    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.

  16. IOP Shape coexistence in neutron-rich strontium isotopes at N = 60

    CERN Document Server

    Clément, Emmanuel

    2017-01-01

    The structure of neutron-rich $^{96,98}$ Sr nuclei was investigated by low-energy Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN, with the MINIBALL spectrometer. A rich set of transitional and diagonal E2 matrix elements has been extracted from the differential Coulomb-excitation cross sections. The results support the scenario of a shape transition at N=60, giving rise to the coexistence of a highly deformed prolate and a spherical configuration in $^{98}$ Sr with low configuration mixing.

  17. Nuclear symmetry energy and the neutron skin in neutron-rich nuclei

    NARCIS (Netherlands)

    Dieperink, AEL; Dewulf, Y; Van Neck, D; Waroquier, M; Rodin, [No Value

    2003-01-01

    The symmetry energy for nuclear matter and its relation to the neutron. skin in finite nuclei is discussed. The symmetry energy as a function of density obtained in a self-consistent Green function approach is presented and compared to the results of other recent theoretical approaches. A partial

  18. Chemical experiments with superheavy elements.

    Science.gov (United States)

    Türler, Andreas

    2010-01-01

    Unnoticed by many chemists, the Periodic Table of the Elements has been extended significantly in the last couple of years and the 7th period has very recently been completed with eka-Rn (element 118) currently being the heaviest element whose synthesis has been reported. These 'superheavy' elements (also called transactinides with atomic number > or = 104 (Rf)) have been artificially synthesized in fusion reactions at accelerators in minute quantities of a few single atoms. In addition, all isotopes of the transactinide elements are radioactive and decay with rather short half-lives. Nevertheless, it has been possible in some cases to investigate experimentally chemical properties of transactinide elements and even synthesize simple compounds. The experimental investigation of superheavy elements is especially intriguing, since theoretical calculations predict significant deviations from periodic trends due to the influence of strong relativistic effects. In this contribution first experiments with hassium (Hs, atomic number 108), copernicium (Cn, atomic number 112) and element 114 (eka-Pb) are reviewed.

  19. Structure of neutron-rich nuclei around the N = 50 shell-gap closure

    Science.gov (United States)

    Faul, T.; Duchêne, G.; Thomas, J.-C.; Nowacki, F.; Huyse, M.; Van Duppen, P.

    2010-04-01

    The structure of neutron-rich nuclei in the vicinity of 78Ni have been investigated via the β-decay of 71,73,75Cu isotopes (ISOLDE, CERN). Experimental results have been compared with shell-model calculations performed with the ANTOINE code using a large (2p3/21f5/22p1/21g9/2) valence space and a 56/28Ni28 core.

  20. Impact of triaxiality on the rotational structure of neutron-rich rhenium isotopes

    Directory of Open Access Journals (Sweden)

    M.W. Reed

    2016-01-01

    Full Text Available A number of 3-quasiparticle isomers have been found and characterised in the odd-mass, neutron-rich, 187Re, 189Re and 191Re nuclei, the latter being four neutrons beyond stability. The decay of the isomers populates states in the rotational bands built upon the 9/2−[514] Nilsson orbital. These bands exhibit a degree of signature splitting that increases with neutron number. This splitting taken together with measurements of the M1/E2 mixing ratios and with the changes observed in the energy of the gamma-vibrational band coupled to the 9/2−[514] state, suggests an increase in triaxiality, with γ values of 5°, 18° and 25° deduced in the framework of a particle-rotor model.

  1. Shape evolution in neutron-rich A ~ 140 nuclei beyond the doubly-magic nucleus 132Sn

    Science.gov (United States)

    Odahara, Atsuko; Eurica Collaboration

    2014-09-01

    Study for the shape evolution enables us to disentangle competition between spherical (single-particle like) shape and deformed (collective-like) shape as a function of neutron number. Neutron-rich nuclei in the northeast region of the doubly-magic 132Sn locates in one of the best mass region where a variety of collective modes, not only prolate deformation but also octupole collectivity, are expected to appear. These neutron-rich A ~140 nuclei were produced by using in-flight fission reaction of the 345 MeV/u 238U86+ beam at RIKEN RI Beam Factory. This experiment was performed in the framework of the EURICA (EUroball RIken Cluster Array) project based on the highly-efficient β- and isomer-decay spectroscopy methods. Around 20 extremely neutron-rich nuclei with Z=51--55 have been studied in this work. New isomers with half lives of longer than hundreds ns were found in some nuclei, such as the neutron-rich Cs isotopes. Also, preliminary results for the β decay of neutron-rich I and Xe isotopes have been obtained. Systematic change of the shape evolution for these neutron-rich isotopes will be discussed.

  2. Superheavy Element Synthesis and Nuclear Structure

    International Nuclear Information System (INIS)

    Ackermann, D.

    2009-01-01

    The search for the next closed proton and neutron shells beyond 2 08P b has yielded a number of exciting results in terms of the synthesis of new elements [1,2,3]. The superheavy elements (SHE), however, are a nuclear structure phenomenon. They owe their existence to the quantum mechanical origin of shell correction energies without which they would not be bound. In recent years the development of efficient experimental set-ups including separators and advanced particle and photon detection arrangements allowed for more and more detailed nuclear structure studies for nuclei at and beyond Z=100. A review of those recent achievements is given in ref. [4]. Among the most interesting features is the observation of K-isomeric states. Experimentally about 14 cases have been identified in the region of Z>96 as shown in Fig. 1. K-isomers or indications of their existence have been found for almost all even-Z elements in the region Z=100 to 110. We could recently establish and/or confirm such states in the even-even isotopes 2 52,254N o [5]. The heaviest nucleus where such a state was found is 2 70D s with Z=110 as we reported in 2001 [6]. Those nuclear structure studies lay out the grounds for a detailed understanding of these heavy and high-Z nuclear systems, and contribute at the same time valuable information to preparation of strategies to successfully continue the hunt for the localisation of the next spherical proton and neutron shells after 2 08P b. The recent activities for both SHE synthesis and nuclear structure investigations at GSI will be reported.(author)

  3. Precision mass measurements for studies of nucleosynthesis via the rapid neutron-capture process. Penning-trap mass measurements of neutron-rich cadmium and caesium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Atanasov, Dinko

    2016-07-06

    Although the theory for the rapid neutron-capture process (r-process) was developed more than 55 years ago, the astrophysical site is still under a debate. Theoretical studies predict that the r-process path proceeds through very neutron-rich nuclei with very asymmetric proton-to-neutron ratios. Knowledge about the properties of neutron-rich isotopes found in similar regions of the nuclear chart and furthermore suitable for r-process studies is still little or even not existing. The basic nuclear properties such as binding energies, half-lives, neutron-induced or neutron-capture reaction cross-sections, play an important role in theoretical simulations and can vary or even drastically alternate results of these studies. Therefore, a considerable effort was put forward to access neutron-rich isotopes at radioactive ion-beam facilities like ISOLDE at CERN. The goal of this PhD thesis is to describe the experimental work done for the precision mass measurements of neutron-rich cadmium ({sup 129-131}Cd) and caesium ({sup 132,146-148}Cs) isotopes. Measurements were done at the on-line radioactive ion-beam facility ISOLDE by using the four-trap mass spectrometer ISOLTRAP. The cadmium isotopes are key nuclides for the synthesis of stable isotopes around the mass peak A = 130 in the Solar System abundance.

  4. Precision mass measurements for studies of nucleosynthesis via the rapid neutron-capture process Penning-trap mass measurements of neutron-rich cadmium and caesium isotopes

    CERN Document Server

    AUTHOR|(CDS)2085660; Litvinov, Yuri A.; Kreim, Susanne

    Although the theory for the rapid neutron-capture process (r-process) was developed more than 55 years ago, the astrophysical site is still under a debate. Theoretical studies predict that the r-process path proceeds through very neutron-rich nuclei with very asymmetric proton- to-neutron ratios. Knowledge about the properties of neutron-rich isotopes found in similar regions of the nuclear chart and furthermore suitable for r-process studies is still little or even not existing. The basic nuclear properties such as binding energies, half-lives, neutron-induced or neutron-capture reaction cross-sections, play an important role in theoretical simulations and can vary or even drastically alternate results of these studies. Therefore, a considerable effort was put forward to access neutron-rich isotopes at radioactive ion-beam facilities like ISOLDE at CERN. The goal of this PhD thesis is to describe the experimental work done for the precision mass measurements of neutron-rich cadmium (129−131 Cd) and caesium...

  5. Gamma-ray spectroscopy of the neutron-rich Ni region through heavy-ion deep-inelastic collisions

    International Nuclear Information System (INIS)

    Ishii, T.; Asai, M.; Matsuda, M.; Ichikawa, S.; Makishima, A.; Hossain, I.; Kleinheinz, P.; Ogawa, M.

    2002-01-01

    Nuclei in the neutron-rich Ni region have been studied by γ-ray spectroscopy. Gamma-rays emitted from isomers, with T 1/2 >1 ns, produced in heavy-ion deep-inelastic collisions were measured with an isomer-scope. The nuclear structure of the doubly magic 68 Ni and its neighbor 69,71 Cu is discussed on the basis of the shell model. Future experiments for more neutron-rich Ni nuclei are also viewed. (orig.)

  6. Gamma-ray spectroscopy of the neutron-rich Ni region through heavy-ion deep-inelastic collisions

    Science.gov (United States)

    Ishii, T.; Asai, M.; Makishima, A.; Hossain, I.; Kleinheinz, P.; Ogawa, M.; Matsuda, M.; Ichikawa, S.

    Nuclei in the neutron-rich Ni region have been studied by γ-ray spectroscopy. Gamma-rays emitted from isomers, with T1/2 > 1 ns, produced in heavy-ion deep-inelastic collisions were measured with an isomer-scope. The nuclear structure of the doubly magic 68Ni and its neighbor 69,71Cu is discussed on the basis of the shell model. Future experiments for more neutron-rich Ni nuclei are also viewed.

  7. Odd-even parity splittings and octupole correlations in neutron-rich Ba isotopes

    Science.gov (United States)

    Fu, Y.; Wang, H.; Wang, L.-J.; Yao, J. M.

    2018-02-01

    The odd-even parity splittings in low-lying parity-doublet states of atomic nuclei with octupole correlations have usually been interpreted as rotational excitations on top of octupole vibration in the language of collective models. In this paper, we report a deep analysis of the odd-even parity splittings in the parity-doublet states of neutron-rich Ba isotopes around neutron number N =88 within a full microscopic framework of beyond-mean-field multireference covariant energy density functional theory. The dynamical correlations related to symmetry restoration and quadrupole-octupole shape fluctuation are taken into account with a generator coordinate method combined with parity, particle-number, and angular-momentum projections. We show that the behavior of odd-even parity splittings is governed by the interplay of rotation, quantum tunneling, and shape evolution. Similar to 224Ra, a picture of rotation-induced octupole shape stabilization in the positive-parity states is exhibited in the neutron-rich Ba isotopes.

  8. Cluster-transfer reactions with radioactive beams: a spectroscopic tool for neutron-rich nuclei

    CERN Document Server

    AUTHOR|(CDS)2086156; Raabe, Riccardo; Bracco, Angela

    In this thesis work, an exploratory experiment to investigate cluster-transfer reactions with radioactive beams in inverse kinematics is presented. The aim of the experiment was to test the potential of cluster-transfer reactions at the Coulomb barrier, as a possible mean to perform $\\gamma$ spectroscopy studies of exotic neutron-rich nuclei at medium-high energies and spins. The experiment was performed at ISOLDE (CERN), employing the heavy-ion reaction $^{98}$Rb + $^{7}$Li at 2.85 MeV/A. Cluster-transfer reaction channels were studied through particle-$\\gamma$ coincidence measurements, using the MINIBALL Ge array coupled to the charged particle Si detectors T-REX. Sr, Y and Zr neutron-rich nuclei with A $\\approx$ 100 were populated by either triton- or $\\alpha$ transfer from $^{7}$Li to the beam nuclei and the emitted complementary charged fragment was detected in coincidence with the $\\gamma$ cascade of the residues, after few neutrons evaporation. The measured $\\gamma$ spectra were studied in detail and t...

  9. Investigation of the single Particle Structure of the neutron-rich Sodium Isotopes $^{27-31}\\!$Na

    CERN Document Server

    2002-01-01

    We propose to study the single particle structure of the neutron-rich isotopes $^{27-31}\\!$Na. These isotopes will be investigated via neutron pickup reactions in inverse kinematics on a deuterium and a beryllium target. Scattered beam particles and transfer products are detected in a position sensitive detector located around 0$^\\circ$. De-excitation $\\gamma$-rays emitted after an excited state has been populated will be registered by the MINIBALL Germanium array. The results will shed new light on the structure of the neutron-rich sodium isotopes and especially on the region of strong deformation around the N=20 nucleus $^{31}\\!$Na.

  10. Light neutron-rich hypernuclei from the importance-truncated no-core shell model

    Science.gov (United States)

    Wirth, Roland; Roth, Robert

    2018-04-01

    We explore the systematics of ground-state and excitation energies in singly-strange hypernuclei throughout the helium and lithium isotopic chains - from He5Λ to He11Λ and from Li7Λ to Li12Λ - in the ab initio no-core shell model with importance truncation. All calculations are based on two- and three-baryon interaction from chiral effective field theory and we employ a similarity renormalization group transformation consistently up to the three-baryon level to improve the model-space convergence. While the absolute energies of hypernuclear states show a systematic variation with the regulator cutoff of the hyperon-nucleon interaction, the resulting neutron separation energies are very stable and in good agreement with available data for both nucleonic parents and their daughter hypernuclei. We provide predictions for the neutron separation energies and the spectra of neutron-rich hypernuclei that have not yet been observed experimentally. Furthermore, we find that the neutron drip lines in the helium and lithium isotopic chains are not changed by the addition of a hyperon.

  11. Neutrino-'pasta' scattering: The opacity of nonuniform neutron-rich matter

    International Nuclear Information System (INIS)

    Horowitz, C.J.; Perez-Garcia, M.A.; Piekarewicz, J.

    2004-01-01

    Neutron-rich matter at subnuclear densities may involve complex structures displaying a variety of shapes, such as spherical, slablike, and/or rodlike shapes. These phases of the nuclear pasta are expected to exist in the crust of neutron stars and in core-collapse supernovae. The dynamics of core-collapse supernovae is very sensitive to the interactions between neutrinos and nucleons/nuclei. Indeed, neutrino excitation of the low-energy modes of the pasta may allow for a significant energy transfer to the nuclear medium, thereby reviving the stalled supernovae shock. The linear response of the nuclear pasta to neutrinos is modeled via a simple semiclassical simulation. The transport mean free path for μ and τ neutrinos (and antineutrinos) is expressed in terms of the static structure factor of the pasta, which is evaluated using Metropolis Monte Carlo simulations

  12. Evidence for a smooth onset of deformation in the neutron-rich Kr isotopes

    CERN Document Server

    Albers, M; Nomura, K; Blazhev, A; Jolie, J; Mucher, D; Bastin, B; Bauer, C; Bernards, C; Bettermann, L; Bildstein, V; Butterworth, J; Cappellazzo, M; Cederkall, J; Cline, D; Darby, I; Das Gupta, S; Daugas, J M; Davinson, T; De Witte, H; Diriken, J; Filipescu, D; Fiori, E; Fransen, C; Gaffney, L P; Georgiev, G; Gernhauser, R; Hackstein, M; Heinze, S; Hess, H; Huyse, M; Jenkins, D; Konki, J; Kowalczyk, M; Kroll, T; Krucken, R; Litzinger, J; Lutter, R; Marginean, N; Mihai, C; Moschner, K; Napiorkowski, P; Nara Singh, B S; Nowak, K; Otsuka, T; Pakarinen, J; Pfeiffer, M; Radeck, D; Reiter, P; Rigby, S; Robledo, L M; Rodriguez-Guzman, R; Rudigier, M; Sarriguren, P; Scheck, M; Seidlitz, M; Siebeck, B; Simpson, G; Thole, P; Thomas, T; Van de Walle, J; Van Duppen, P; Vermeulen, M; Voulot, D; Wadsworth, R; Wenander, F; Wimmer, K; Zell, K O; Zielinska, M

    2012-01-01

    The neutron-rich nuclei $^{94,96}$Kr were studied via projectile Coulomb excitation at the REX-ISOLDE facility at CERN. Level energies of the first excited 2$^{+}$ states and their absolute $E2$ transition strengths to the ground state are determined and discussed in the context of the $E(2^{+}_{1})$ and $B(E2;2^{+}_{1} \\rightarrow 0^{+}_{1})$ systematics of the krypton chain. Contrary to previously published results no sudden onset of deformation is observed. This experimental result is supported by a new proton-neutron interacting boson model calculation based on the constrained Hartree-Fock-Bogoliubov approach using the microscopic Gogny-D1M energy density functional.

  13. High spin study and lifetime measurements of neutron rich Co isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Regan, P H; Arrison, J W; Huttmeier, U J; Balamuth, D P [Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Physics

    1992-08-01

    The neutron rich nuclei {sup 61,63}Co have been studied using the reactions {sup 16}O({sup 48}Ca,p2n){sup 61}Co at 110 MeV and {sup 18}O({sup 48}Ca,p2n){sup 63}Co at 110 MeV respectively. Discrete lines from the channels of interest were investigated using pre-scaled {gamma} singles, charged-particle-{gamma}, neutron-charged-particle-{gamma} and charged particle-{gamma}-{gamma} data. Decay schemes, with level spins deduced from angular distribution data are presented together with preliminary information on the lifetimes of some higher excitation states. These data represent the first study on the medium to high spin states in these nuclei. (author). 9 refs., 1 tab., 4 figs.

  14. $\\beta$-decay study of neutron-rich Tl and Pb isotopes

    CERN Multimedia

    It is proposed to study the structure of neutron-rich nuclei beyond $^{208}$Pb. The one-proton hole $^{211-215}$Tl and the semi magic $^{213}$Pb will be produced and studied via nuclear and atomic spectroscopy searching for long-lived isomers and investigating the $\\beta$-delayed $\\gamma$- emission to build level schemes. Information on the single particle structure in $^{211-215}$Pb, especially the position of the g$_{9/2}$ and i$_{11/2}$ neutron orbitals, will be extracted along with lifetimes. The $\\beta$-decay will be complemented with the higher spin selectivity that can be obtained by resonant laser ionization to single-out the decay properties of long-living isomers in $^{211,213}$Tl and $^{213}$Pb.

  15. Fusion reaction around the Coulomb barrier with neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Atsushi [Institute of Physical and Chemical Research, Wako, Saitama (Japan)

    1997-07-01

    Two fusion reactions with neutron-rich nuclei are reported in this work. On the first reaction: {sup 9,10,11}Be+{sup 209}Bi, the fusion cross sections around the coulomb barrier were measured by determing {alpha} disintegration from compound nucleus Fr. In the field of 10-100 mb, the same total fusion cross sections were obtained. The phenomenon {sup 11}Be(neutron halo nucleus) alone increased and decreased was not observed. The fusion cross sections of {sup 27,29,31}Al+{sup 197}Au system were determined by using 130 kcps and 30 kcps of beam strength of {sup 29,31}Al, respectively. The value of {sup 27}Al was reproduced by calculation, but that of {sup 29}Al increased around barrier which could not be explained by CCDEF calculation. (S.Y.)

  16. I. Surface properties of neutron-rich nuclei. II. Pion condensation at finite temperature

    International Nuclear Information System (INIS)

    Kolehmainen, K.A.

    1983-01-01

    In part I, the energy density formalism, the Thomas-Fermi approximation, and Skyrme-type interactions were used to describe the energy density of a semi-infinite slab of neturon-rich nuclear matter at zero temperature. The existence of a drip phase at low proton fractions is allowed in addition to the more dense nuclear phase, and various bulk properties of both phases are found when the system is in equilibrium. The usual definition of the surface energy is extended to apply to the case where drip is present. Assuming a Fermi function type density profile, a constrained variational calculation is performed to determine the neutron and proton surface diffuseness parameters, the thickness of the neutron skin, and the surface energy. Results are obtained for proton fractions reanging from 0.5 (symmetric nuclear matter) to zero (pure neutron matter) for most Skyrme-type interactions in common use. The results are in close agreement with the predictions of the droplet model, as well as with the results of more exact calculations in those cases where the more exact results exist (only for symmetric or nearly symmetric matter in most cases). Significantly different asymmetry dependences for different interactions are found. In part II, several simple but increasingly complex models are used to calculate the threshold for charged pion condensation in neutron-rich nuclear matter at finite temperature. Unlike in mean field theory descriptions of pion condensation, the effects of thermal excitations of the pion field are included. The thermal pion excitations have two important effects: first, to modify the phase diagram qualitatively from that predicted by mean field theory, and second, to make the phase transition to a spatially nonuniform condensed state at finite temperature always first, rather than second, order

  17. Collisions of deformed nuclei and superheavy-element production

    International Nuclear Information System (INIS)

    Iwamoto, Akira; Moeller, P.; Univ. of Aizu, Fukushima; P. Moller Scientific Computing and Graphics, Inc., Los Alamos, NM; Los Alamos National Lab., NM; Nix, J.R.; Sagawa, Hiroyuki, Sagawa

    1995-01-01

    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 micros

  18. Evolution of collectivity in neutron-rich nuclei in the 132Sn region

    International Nuclear Information System (INIS)

    Kshetri, Ritesh; Sarkar, M. Saha; Sarkar, S.

    2006-01-01

    Motivated by the observed regularity in the energy spectra and the structure of the shell model wave functions for the levels of 137 Te and 137 I, a few weakly and moderately deformed neutron-rich odd-A nuclei above the doubly magic nucleus 132 Sn were studied using the particle rotor model (PRM). The calculated energy spectra and branching ratios agree reasonably well with the most recent experimental data. In a few cases ambiguity in level ordering was resolved and spin-parities were assigned to the levels. Observed octupole correlation in some of these nuclei is discussed in the light of the present results

  19. Spectroscopy on neutron-rich nuclei at RIKEN. Present and future

    International Nuclear Information System (INIS)

    Sakurai, H.

    2003-01-01

    Recent studies on nuclear structure by using radioactive isotope beams available at the RIKEN projectile-fragment separator (RIPS) are introduced. Special emphasis is given to experiments selected from the recent programs that highlight studies at N=20-28; on the large deformation of 30 Ne and 34 Mg via the in-beam gamma spectroscopy, and on the particle stability of very neutron-rich nuclei, 34 Ne, 37 Na and 43 Si. The RI Beam Factory (RIBF) project is illustrated through review of such present research activities at RIPS. (author)

  20. Application of the generator coordinate method to neutron-rich Se and Ge isotopes

    Directory of Open Access Journals (Sweden)

    Higashiyama Koji

    2014-03-01

    Full Text Available The quantum-number projected generator coordinate method (GCM is applied to the neutron-rich Se and Ge isotopes, where the monopole and quadrupole pairing plus quadrupole-quadrupole interaction is employed as an effective interaction. The energy spectra obtained by the GCM are compared to both the shell model results and the experimental data. The GCM reproduces well the energy levels of high-spin states as well as the low-lying states. The structure of the low-lying collective states is analyzed through the GCM wave functions.

  1. Decay of a three-quasiparticle isomer in the neutron-rich nucleus 183Ta

    Directory of Open Access Journals (Sweden)

    Zhu S.

    2012-10-01

    Full Text Available Excited states in neutron-rich tantalum isotopes have been studied with deep-inelastic reactions using 136Xe ions incident on a 186W target. New transitions observed below the τ=1.3 μs isomer in 183Ta have enabled the establishment of its energy and put limits on the spin and parity. On the basis of the reduced hindrances for the depopulating transitions, a 3-quasiparticle configuration of ν1/2−[510]11/2+[615] ⊗ π9/2−[514] is suggested.

  2. Simulation of neutron rich nuclei production through 239U fission at intermediates energies

    International Nuclear Information System (INIS)

    Mirea, M.; Clapier, F.; Pauwels, N.; Proust, J.

    1997-01-01

    The theoretical part and some results obtained from a model realised for fission processes in wide range of mass-asymmetries are presented. The fission barriers are computed in a tridimensional configuration space using the Yukawa - plus - exponential macroscopic energies corrected within the Strutinsky procedure. It is assumed that channel probabilities are proportional with Gamow penetrabilities. The model is applied for the disintegration of the 239 U in order to determine the relative yields for the production of neutron rich nuclei at diverse intermediate energies. (author)

  3. Collective excitations in neutron-rich nuclei within the model of a Fermi liquid drop

    International Nuclear Information System (INIS)

    Kolomietz, V.M.; Magner, A.G.

    2000-01-01

    We discuss a new mechanism of splitting of giant multipole resonances (GMR) in spherical neutron-rich nuclei. This mechanism is associated with the basic properties of an asymmetric drop of nuclear Fermi liquid. In addition to well-known isospin shell-model predictions, our approach can be used to describe the GMR splitting phenomenon in the wide nuclear-mass region A ∼ 40-240. For the dipole isovector modes, the splitting energy, the relative strength of resonance peaks, and the contribution to the energy-weighted sum rules are in agreement with experimental data for the integrated cross sections for photonuclear (γ, n) and (γ, p) reactions

  4. Coulomb excitation of neutron-rich $^{134-136}$Sn isotopes

    CERN Multimedia

    We propose to study excited states in the isotopes $^{134,136}$Sn by $\\gamma$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to investigate the evolution of quadrupole collectivity beyond the magic shell closure at N = 82 by the determination of B(E2) values and electric quadrupole moments $\\mathcal{Q}_2$. Recent shell-model calculations using realistic interactions predict possible enhanced collectivity in neutron-rich regions. Evidence for this could be obtained by this experiment. Furthermore, the currently unknown excitation energies of the 2$^+_{1}$ and 4$^+_{1}$ states in $^{136}$Sn will be measured for the first time.

  5. The CARDS array for neutron-rich decay spectroscopy at HRIBF

    CERN Document Server

    Batchelder, J C; Bingham, C R; Carter, H K; Cole, J D; Fong, D; Garrett, P E; Grzywacz, R; Hamilton, J H; Hartley, D J; Hwang, J K; Krolas, W; Kulp, D C; Larochelle, Y; Piechaczek, A; Ramayya, A V; Rykaczewski, K; Spejewski, E H; Stracener, D W; Tantawy, M N; Winger, J A; Wood, J; Zganjar, E F

    2003-01-01

    An array for decay studies of neutron-rich nuclei has been commissioned for use at the UNISOR separator at Holifield Radioactive Ion Beam Facility. This array consists of three segmented clover Ge detectors, plastic scintillators, and a high-resolution (approx 1 keV) Si conversion electron spectrometer. These detectors are mounted on a support that surrounds a moving tape collector. This system has been named clover array for radioactive decay studies. The detectors have been outfitted with digital flash ADCs (XIA DGFs) that fit the preamp signals, with built-in pileup rejection.

  6. The CARDS array for neutron-rich decay spectroscopy at HRIBF

    International Nuclear Information System (INIS)

    Batchelder, J.C.; Bilheux, J.-C.; Bingham, C.R.; Carter, H.K.; Cole, J.D.; Fong, D.; Garrett, P.E.; Grzywacz, R.; Hamilton, J.H.; Hartley, D.J.; Hwang, J.K.; Krolas, W.; Kulp, D.; Larochelle, Y.; Piechaczek, A.; Ramayya, A.V.; Rykaczewski, K.P.; Spejewski, E.H.; Stracener, D.W.; Tantawy, M.N.; Winger, J.A.; Wood, J.; Zganjar, E.F.

    2003-01-01

    An array for decay studies of neutron-rich nuclei has been commissioned for use at the UNISOR separator at Holifield Radioactive Ion Beam Facility. This array consists of three segmented clover Ge detectors, plastic scintillators, and a high-resolution (∼1 keV) Si conversion electron spectrometer. These detectors are mounted on a support that surrounds a moving tape collector. This system has been named clover array for radioactive decay studies. The detectors have been outfitted with digital flash ADCs (XIA DGFs) that fit the preamp signals, with built-in pileup rejection

  7. Decay spectroscopy of neutron-rich nuclei with the CAITEN detector

    Energy Technology Data Exchange (ETDEWEB)

    Steiger, Konrad [Physik-Department E12, Technische Universitaet Muenchen (Germany); Collaboration: CAITEN-Collaboration

    2012-07-01

    An experiment in fall 2010 at the RIBF (Radioactive Ion Beam Factory at RIKEN, Japan) investigated the neutron-rich nuclei in the neighborhood of {sup 30}Ne and {sup 36}Mg. These nuclei were produced by relativistic projectile fragmentation of a 345 AMeV {sup 48}Ca primary beam which was delivered from the superconducting ring cyclotron SRC with an average intensity of 70 pnA. The secondary cocktail beam was separated and identified with the BigRIPS fragment separator and the ZeroDegree spectrometer. The unambiguous particle identification was achieved by measuring the energy loss, time of flight and magnetic rigidity event-by-event. The identified fragments were implanted in the CAITEN detector (Cylindrical Active Implantation Target for Efficient Nuclear-decay study). The main part of this detector is a 4 x 10{sup 4}-fold segmented plastic scintillator with the shape of a hollow cylinder. To reduce background events the scintillator was moved continuously in axial and vertical direction (similar to a tape-transporting system). Implantations and decays were correlated in time and space. {gamma}-rays were detected with three germanium clover detectors. For the first time {beta}-delayed gammas were measured in the neutron-rich isotopes {sup 36-38}Si. The status of the analysis and preliminary results including new half-life values and tentative level schemes for these very exotic nuclei are presented.

  8. Study of shape transition in the neutron-rich Os isotopes

    Directory of Open Access Journals (Sweden)

    John P.R.

    2014-03-01

    Full Text Available The neutron-rich isotopes of tungsten, osmium and platinum have different shapes in their ground states and present also shape transitions phenomena. Spectroscopic information for these nuclei is scarce and often limited to the gamma rays from the decay of isomeric states. For the neutron-rich even-even osmium isotopes 194Os and 198Os, a shape transition between a slightly prolate deformed to an oblate deformed ground state was deduced from the observed level schemes. For the even-even nucleus lying in between, 196Os, no gamma ray transition is known. In order to elucidate the shape transition and to test the nuclear models describing it, this region was investigated through gamma-ray spectroscopy using the AGATA demonstrator and the large acceptance heavy-ion spectrometer PRISMA at LNL, Italy. A two-nucleon transfer from a 198Pt target to a stable 82Se beam was utilized to populate medium-high spin states of 196Os. The analysis method and preliminary results, including the first life-time measurement of isomeric states with AGATA, are presented.

  9. Development of axial asymmetry in the neutron-rich nucleus {sup 110}Mo

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, H., E-mail: hiroshi@ribf.riken.jp [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yamaguchi, K.; Odahara, A. [Department of Physics, Osaka University, Machikaneyama-machi 1-1, Osaka 560-0043 Toyonaka (Japan); Sumikama, T. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Nishimura, S. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yoshinaga, K. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Li, Z. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Miyashita, Y. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Sato, K. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Prochniak, L. [Institute of Physics, Maria Curie-Sklodowska University, pl. M. Curie-Sklodowskiej 1, 20-031 Lublin (Poland); Baba, H. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Berryman, J.S. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Blasi, N. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy); Bracco, A.; Camera, F. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy); Dipartimento di Fisica, Universita di Milano, via Celoria 16, I-20133 Milano (Italy); Chiba, J. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Doornenbal, P. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Go, S.; Hashimoto, T.; Hayakawa, S. [Center for Nuclear Study, University of Tokyo, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan)

    2011-10-19

    The neutron-rich nucleus {sup 110}Mo has been investigated by means of {gamma}-ray spectroscopy following the {beta}-decay of {sup 110}Nb, produced using in-flight fission of a {sup 238}U beam at 345 MeV/nucleon at the RIBF facility. In addition to the ground-band members reported previously, spectroscopic information on the low-lying levels of the quasi-{gamma} band built on the second 2{sup +} state at 494 keV has been obtained for the first time. The experimental finding of the second 2{sup +} state being lower than the yrast 4{sup +} level suggests that axially-asymmetric {gamma} softness is substantially enhanced in this nucleus. The experimental results are compared with model calculations based on the general Bohr Hamiltonian method. The systematics of the low-lying levels in even-even A{approx}110 nuclei is discussed in comparison with that in the neutron-rich A{approx}190 region, by introducing the quantity E{sub S}/E(2{sub 1}{sup +}), E{sub S}=E(2{sub 2}{sup +})-E(4{sub 1}{sup +}), as a global signature of the structural evolution involving axial asymmetry.

  10. New neutron-rich isotope production in 154Sm+160Gd

    Directory of Open Access Journals (Sweden)

    Ning Wang

    2016-09-01

    Full Text Available Deep inelastic scattering in 154Sm+160Gd at energies above the Bass barrier is for the first time investigated with two different microscopic dynamics approaches: improved quantum molecular dynamics (ImQMD model and time dependent Hartree–Fock (TDHF theory. No fusion is observed from both models. The capture pocket disappears for this reaction due to strong Coulomb repulsion and the contact time of the di-nuclear system formed in head-on collisions is about 700 fm/c at an incident energy of 440 MeV. The isotope distribution of fragments in the deep inelastic scattering process is predicted with the simulations of the latest ImQMD-v2.2 model together with a statistical code (GEMINI for describing the secondary decay of fragments. More than 40 extremely neutron-rich unmeasured nuclei with 58≤Z≤76 are observed and the production cross sections are at the order of μb to mb. The multi-nucleon transfer reaction of Sm+Gd could be an alternative way to synthesize new neutron-rich lanthanides which are difficult to be produced with traditional fusion reactions or fission of actinides.

  11. A systematic study of superheavy nuclei for Z = 114 and beyond using the relativistic mean field approach

    International Nuclear Information System (INIS)

    Patra, S.K.; Wu, Cheng-Li; Praharaj, C.R.; Gupta, Raj K.

    1999-01-01

    We have studied the structural properties of even-even, neutron deficient, Z=114-126, superheavy nuclei in the mass region A ∼ 270-320, using an axially deformed relativistic mean field model. The calculations are performed with three parameter sets (NL1, TM1 and NL-SH), in order to see the dependence of the structural properties on the force used. The calculated ground state shapes are found to be parameter dependent. For some parameter sets, many of the nuclei are degenerate in their ground state configuration. Special attention is given to the investigation of the magic structures (spherical shell closures) in the superheavy region. We find that some known magic numbers are absent and new closed shells are predicted. Large shell gaps appear at Z=80, 92, (114), 120 and 138, N=138, (164), (172), 184, (198), (228) and 258, irrespective of the parameter sets used. The numbers in parenthesis are those which correspond to relatively smaller gaps. The existence of new magic numbers in the valley of superheavy elements is discussed. It is suggested that nuclei around Z=114 and N = 164 ∼ 172 could be considered as candidates for the next search of superheavy nuclei. The existence of superheavy islands around Z=120 and N=172 or N 184 double shell closure is also discussed

  12. Experimental search for superheavy elements

    International Nuclear Information System (INIS)

    Wieloch, A.

    2008-12-01

    This work reports on the experimental search for superheavy elements (SHE). Two types of approaches for SHE production are studied i.e. '' cold '' fusion mechanism and massive transfer mechanism. First mechanism was studied in normal and inverse kinematics, by using Wien filter at the GANIL facility. The production of SHE elements with Z 106 and 108 is reported while negative results on the synthesis of SHE elements with Z 114 and 118 was received. The other approach i.e. reactions induced by heavy ion projectiles (e.g. 172 Yb, 197 Au) on fissile target nuclei (e.g. 238 U, 232 Th) at near Coulomb barrier incident energies was studied by using superconducting solenoid installed Texas A(and)M University. Preliminary results for the reaction 197 Au(7.5 MeV/u) - 232 Th are presented where three cases of the possible candidates for SHE elements were found. A dedicated detection setup for such studies is discussed and the detailed data analysis is presented. Detection of alpha and spontaneous fission radioactive decays is used to unambiguously identify the atomic number of SHE. Special statistical analysis for a very low detected number of α decays is applied to check consistency of the αradioactive chains. (author)

  13. Chemistry of the superheavy elements.

    Science.gov (United States)

    Schädel, Matthias

    2015-03-13

    The quest for superheavy elements (SHEs) is driven by the desire to find and explore one of the extreme limits of existence of matter. These elements exist solely due to their nuclear shell stabilization. All 15 presently 'known' SHEs (11 are officially 'discovered' and named) up to element 118 are short-lived and are man-made atom-at-a-time in heavy ion induced nuclear reactions. They are identical to the transactinide elements located in the seventh period of the periodic table beginning with rutherfordium (element 104), dubnium (element 105) and seaborgium (element 106) in groups 4, 5 and 6, respectively. Their chemical properties are often surprising and unexpected from simple extrapolations. After hassium (element 108), chemistry has now reached copernicium (element 112) and flerovium (element 114). For the later ones, the focus is on questions of their metallic or possibly noble gas-like character originating from interplay of most pronounced relativistic effects and electron-shell effects. SHEs provide unique opportunities to get insights into the influence of strong relativistic effects on the atomic electrons and to probe 'relativistically' influenced chemical properties and the architecture of the periodic table at its farthest reach. In addition, they establish a test bench to challenge the validity and predictive power of modern fully relativistic quantum chemical models. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  14. Superheavy nuclei: a relativistic mean field outlook

    International Nuclear Information System (INIS)

    Afanasjev, A.V.

    2006-01-01

    The analysis of quasi-particle spectra in the heaviest A∼250 nuclei with spectroscopic data provides an additional constraint for the choice of effective interaction for the description of superheavy nuclei. It strongly suggests that only the parametrizations which predict Z = 120 and N = 172 as shell closures are reliable for superheavy nuclei within the relativistic mean field theory. The influence of the central depression in the density distribution of spherical superheavy nuclei on the shell structure is studied. A large central depression produces large shell gaps at Z = 120 and N = 172. The shell gaps at Z = 126 and N = 184 are favoured by a flat density distribution in the central part of the nucleus. It is shown that approximate particle number projection (PNP) by means of the Lipkin-Nogami (LN) method removes pairing collapse seen at these gaps in the calculations without PNP

  15. Interplay between collective and single particle excitations around neutron-rich doubly-magic nuclei

    Directory of Open Access Journals (Sweden)

    Leoni S.

    2016-01-01

    Full Text Available The excitation spectra of nuclei with one or two particles outside a doubly-magic core are expected to be dominated, at low energy, by the couplings between phonon excitations of the core and valence particles. A survey of the experimental situation is given for some nuclei lying in close proximity of neutron-rich doubly-magic systems, such as 47,49Ca, 133Sb and 210Bi. Data are obtained with various types of reactions (multinucleon transfer with heavy ions, cold neutron capture and neutron induced fission of 235U and 241Pu targets, with the employment of complex detection systems based on HPGe arrays. A comparison with theoretical calculations is also presented, in terms of large shell model calculations and of a phenomenological particle-phonon model. In the case of 133Sb, a new microscopic “hybrid” model is introduced: it is based on the coupling between core excitations (both collective and non-collective of the doubly-magic core and the valence nucleon, using the Skyrme effective interaction in a consistent way.

  16. Interplay between collective and single particle excitations around neutron-rich doubly-magic nuclei

    Science.gov (United States)

    Leoni, S.

    2016-05-01

    The excitation spectra of nuclei with one or two particles outside a doubly-magic core are expected to be dominated, at low energy, by the couplings between phonon excitations of the core and valence particles. A survey of the experimental situation is given for some nuclei lying in close proximity of neutron-rich doubly-magic systems, such as 47,49Ca, 133Sb and 210Bi. Data are obtained with various types of reactions (multinucleon transfer with heavy ions, cold neutron capture and neutron induced fission of 235U and 241Pu targets), with the employment of complex detection systems based on HPGe arrays. A comparison with theoretical calculations is also presented, in terms of large shell model calculations and of a phenomenological particle-phonon model. In the case of 133Sb, a new microscopic "hybrid" model is introduced: it is based on the coupling between core excitations (both collective and non-collective) of the doubly-magic core and the valence nucleon, using the Skyrme effective interaction in a consistent way.

  17. Experimental study of the lifetime and phase transition in neutron-rich Zr 98 ,100 ,102

    Science.gov (United States)

    Ansari, S.; Régis, J.-M.; Jolie, J.; Saed-Samii, N.; Warr, N.; Korten, W.; Zielińska, M.; Salsac, M.-D.; Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T.; Simpson, G. S.; Drouet, F.; Vancraeyenest, A.; de France, G.; Clément, E.; Stezowski, O.; Ur, C. A.; Urban, W.; Regan, P. H.; Podolyák, Zs.; Larijani, C.; Townsley, C.; Carroll, R.; Wilson, E.; Mach, H.; Fraile, L. M.; Paziy, V.; Olaizola, B.; Vedia, V.; Bruce, A. M.; Roberts, O. J.; Smith, J. F.; Scheck, M.; Kröll, T.; Hartig, A.-L.; Ignatov, A.; Ilieva, S.; Lalkovski, S.; Mǎrginean, N.; Otsuka, T.; Shimizu, N.; Togashi, T.; Tsunoda, Y.

    2017-11-01

    Rapid shape changes are observed for neutron-rich nuclei with A around 100. In particular, a sudden onset of ground-state deformation is observed in the Zr and Sr isotopic chains at N = 60: Low-lying states in N ≤58 nuclei are nearly spherical, while those with N ≥60 have a rotational character. Nuclear lifetimes as short as a few picoseconds can be measured using fast-timing techniques with LaBr3(Ce) scintillators, yielding a key ingredient in the systematic study of the shape evolution in this region. We used neutron-induced fission of 241Pu and 235U to study lifetimes of excited states in fission fragments in the A ˜100 region with the EXILL-FATIMA array located at the PF1B cold neutron beam line at the Institut Laue-Langevin. In particular, we applied the generalized centroid difference method to deduce lifetimes of low-lying states for the nuclei 98Zr (N = 58), 100Zr, and 102Zr (N ≥60 ). The results are discussed in the context of the presumed phase transition in the Zr chain by comparing the experimental transition strengths with the theoretical calculations using the interacting boson model and the Monte Carlo shell model.

  18. Neutron-rich polonium isotopes studied with in-source laser spectroscopy

    CERN Document Server

    Dexters, Wim; Cocolios, T E

    This work studies the unknown region of neutron rich polonium isotopes. The polonium isotopes, with Z=84, lie above the magic lead nuclei (Z=82). The motivation for this research can mainly be found in these lead nuclei. When looking at the changes in the mean square charge radii beyond the N=126 shell gap, a kink is observed. This kink is also found in the radon (Z=86) and radium (Z=88) isotopes. The observed effect cannot be reproduced with our current models. The polonium isotopes yield more information on the kink and they are also able to link the known charge radii in lead isotopes to those in radon and radium. Additionally, the nuclear moments of the odd-neutron isotope $^{211}$Po are investigated. This nucleus has two protons and one neutron more than the doubly magic nucleus $^{208}$Pb. Nuclear moments of isotopes close to this doubly magic nucleus are good tests for the theoretic models. Besides pushing the models to their limits, the nuclear moments of $^{211}$Po also yield new information on the f...

  19. Equation of state of neutron-rich nuclear matter from chiral effective field theory

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, Norbert; Strohmeier, Susanne [Technische Universitaet Muenchen (Germany)

    2016-07-01

    Based on chiral effective field theory, the equation of state of neutron-rich nuclear matter is investigated systematically. The contributing diagrams include one- and two-pion exchange together with three-body terms arising from virtual Δ(1232)-isobar excitations. The proper expansion of the energy per particle, anti E(k{sub f},δ) = anti E{sub n}(k{sub f}) + δB{sub 1}(k{sub f}) + δ{sup 5/3}B{sub 5/3}(k{sub f}) + δ{sup 2}B{sub 2}(k{sub f}) +.., for the system with neutron density ρ{sub n} = k{sub f}{sup 3}(1-δ)/3π{sup 2} and proton density ρ{sub p} = k{sub f}{sup 3}δ/3π{sup 2} is performed analytically for the various interaction contributions. One observes essential structural differences to the commonly used quadratic approximation. The density dependent coefficient B{sub 1}(k{sub f}) turns out to be unrelated to the isospin-asymmetry of nuclear matter. The coefficient B{sub 5/3}(k{sub f}) of the non-analytical δ{sup 5/3}-term receives contributions from the proton kinetic energy and from the one- and two-pion exchange interactions. The physical consequences for neutron star matter are studied.

  20. Tests on the synthesis of superheavy elements

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    The article briefly summarizes the study of superheavy elements, starting with speculations on the existence of relatively long-living nuclei via theoretical works to nuclear properties and chemical properties, search for the longest-living nuclei of the calculated stability island in nature, up to the attempts to produce such superheavy elements in large heavy ion accelerators (Berkely, Dubna, Darmstadt, Orsay). Principle and problems of the two methods to achieve a synthesis of such heavy nuclei, i. e. fusion reactions and transfer reactions, are briefly discussed. (RB) [de

  1. Production of neutron-rich nuclei in fission induced by neutrons generated by the p+ sup 1 sup 3 C reaction at 55 MeV

    CERN Document Server

    Stroe, L; Andrighetto, A; Tecchio, L B; Dendooven, P; Huikari, J; Pentillä, H; Peraejaervi, K; Wang, Y

    2003-01-01

    Cross-sections for the production of neutron-rich nuclei obtained by neutron-induced fission of natural uranium have been measured. The neutrons were generated by bombarding a sup 1 sup 3 C target with 55 MeV protons. The results, position of the maximum in the (Z, A)-plane, width and magnitude, are very comparable with those where the neutrons are generated by bombardment of natural sup 1 sup 2 C graphite with 50 MeV deuterons. Depending on the geometry of the converter/target assembly the isotope yields, however, are a factor of 2-3 lower due to less efficient production of neutrons per primary projectile, especially at small forward angles. (orig.)

  2. Decay Study for the very Neutron-Rich Sn Nuclides, $^{135-140}$Sn Separated by Selective Laser Ionization

    CERN Multimedia

    2002-01-01

    %IS378 %title\\\\ \\\\ In this investigation, we wish to take advantage of chemically selective laser ionization to separate the very-neutron-rich Sn nuclides and determine their half-lives and delayed-neutron branches (P$_{n}$) using the Mainz $^{3}$He-delayed neutron spectrometer and close-geometry $\\gamma$-ray spectroscopy system. The $\\beta$-decay rates are dependent on a number of nuclear structure factors that may not be well described by models of nuclear structure developed for nuclides near stability. Determination of these decay properties will provide direct experimental data for r-process calculations and test the large number of models of nuclear structure for very-neutron rich Sn nuclides now in print.

  3. Beta-decay measurements of neutron-rich thallium, lead, and bismuth by means of resonant laser ionisation

    Science.gov (United States)

    Franchoo, S.; de Witte, H.; Andreyev, A. N.; Cederka¨Ll, J.; Dean, S.; de Smet, A.; Eeckhaudt, S.; Fedorov, D. V.; Fedosseev, V. N.; G´Rska, M.; Huber, G.; Huyse, M.; Janas, Z.; Ko¨Ster, U.; Kurcewicz, W.; Kurpeta, J.; Mayer, P.; Płchocki, A.; van de Vel, K.; van Duppen, P.; Weissman, L.; Isolde Collaboration

    2004-04-01

    Neutron-rich thallium, lead, and bismuth isotopes were investigated at the ISOLDE facility. After mass separation and resonant laser ionisation of the produced activity, new spectroscopic data were obtained for 215,218Bi and 215Pb. An attempt to reach heavy thallium had to be abandoned because of a strong francium component in the beam that gave rise to a neutron background through (α,n) reactions on the aluminium walls of the experimental chamber.

  4. Low-lying dipole strength of neutron-rich 'island of inversion' nuclei around n ∼ 20

    International Nuclear Information System (INIS)

    Datta Pramanik, U.; Chakraborty, S.; Ray, I.

    2009-01-01

    Magic numbers are the basic building blocks of nuclear structure since last fifty years. Recently, through various experimental results using Radioactive Ion Beam (RIB) facilities, it has been observed that those long cherished magic numbers are not valid anymore in the neutron rich nuclei like 32 Mg etc. The breakdown of magic number was hinted in the late 1980 's by Thibault et. al. in sodium nuclei ( 31,32 Na). Motobayashi et. al. showed large deformation for 32 Mg which leads to the failure of magic number at N = 20. Exploration into the cause of this breakdown shows the filling of higher pf orbitals rather than the pure lower sd orbitals in the ground state of the neutron-rich nuclei like Ne, Na, Mg in the region N∼20. Thus there is obviously an inversion in nuclear orbitals and hence the so called name 'island of inversion'. This year, we have performed an experiment at GSI, Darmstadt. The measurement of dipole threshold strength of neutron-rich nucleus (N∼20) through electromagnetic excitation was done using LAND-FRS setup. Through this dipole strength, we would like to probe directly the quantum numbers of the valence neutrons in neutron rich nuclei like 31-33 Mg, 33-35 Al, 29-30 Na, 25-27 Ne, 24 F etc.

  5. Recent activities for β-decay half-lives and β-delayed neutron emission of very neutron-rich isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Dillmann, Iris [TRIUMF, Vancouver BC, V6T 2A3, Canada and GSI Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Abriola, Daniel [Laboratorio Tandar, Comisión Nacional de Energía Atómica, B1650KINA, San Martín, Buenos Aires (Argentina); Singh, Balraj [Department of Physics and Astronomy, McMaster University, Hamilton ON, L8S 4M1 (Canada)

    2014-05-02

    Beta-delayed neutron (βn) emitters play an important, two-fold role in the stellar nucleosynthesis of heavy elements in the 'rapid neutron-capture process' (r process). On one hand they lead to a detour of the material β-decaying back to stability. On the other hand, the released neutrons increase the neutron-to-seed ratio, and are re-captured during the freeze-out phase and thus influence the final solar r-abundance curve. A large fraction of the isotopes inside the r-process reaction path are not yet experimentally accessible and are located in the (experimental) 'Terra Incognita'. With the next generation of fragmentation and ISOL facilities presently being built or already in operation, one of the main motivation of all projects is the investigation of these very neutron-rich isotopes. A short overview of one of the planned programs to measure βn-emitters at the limits of the presently know isotopes, the BRIKEN campaign (Beta delayed neutron emission measurements at RIKEN) will be given. Presently, about 600 β-delayed one-neutron emitters are accessible, but only for a third of them experimental data are available. Reaching more neutron-rich isotopes means also that multiple neutron-emission becomes the dominant decay mechanism. About 460 β-delayed two-, three-or four-neutron emitters are identified up to now but for only 30 of them experimental data about the neutron branching ratios are available, most of them in the light mass region below A=30. The International Atomic and Energy Agency (IAEA) has identified the urgency and picked up this topic recently in a 'Coordinated Research Project' on a 'Reference Database for Beta-Delayed Neutron Emission Data'. This project will review, compile, and evaluate the existing data for neutron-branching ratios and half-lives of β-delayed neutron emitters and help to ensure a reliable database for the future discoveries of new isotopes and help to constrain astrophysical and

  6. Collective motion in hot superheavy nuclei

    NARCIS (Netherlands)

    Tveter, TS; Gaardhoje, JJ; Maj, A; Ramsoy, T; Atac, A; Bacelar, J; Bracco, A; Buda, A; Camera, F; Herskind, B; Korten, W; Krolas, W; Menthe, A; Million, B; Nifenecker, H; Pignanelli, M; Pinston, JA; vanderPloeg, H; Schussler, F; Sletten, G

    1996-01-01

    The superheavy nucleus (272)(108)Hs and its evaporation daughters have been produced using the reaction Th-232(Ar-40,gamma xn) with beam energies 10.5 and 15.0 MeV/A. The Giant Dipole Resonance gamma-radiation from the hot conglomerate system prior to fission has been isolated using a differential

  7. Decay of heavy and superheavy nuclei

    Indian Academy of Sciences (India)

    April 2014 physics pp. 705–715. Decay of heavy and superheavy nuclei ... study on the feasibility of observing α decay chains from the isotopes of the ... studies on 284−286115 and 288−292117 will be a guide to future experiments. .... ratio of the α decay from the ground state of the parent nucleus to the level i of the.

  8. Silicon vertex detector for superheavy elements identification

    Directory of Open Access Journals (Sweden)

    Bednarek A.

    2012-07-01

    Full Text Available Silicon vertex detector for superheavy elements (SHE identification has been proposed. It will be constructed using very thin silicon detectors about 5 μm thickness. Results of test of 7.3 μm four inch silicon strip detector (SSD with fission fragments and α particles emitted by 252Cf source are presented

  9. Superheavy nuclei – cold synthesis and structure

    Indian Academy of Sciences (India)

    120 and Ж = 172 or 184, for superheavy nuclei. This result is discussed in ... 1980 [7] on the basis of the QMFT, once again prior to its observation in 1984. Thus, cold ... On the other hand, based on a rather complete deformed relativistic mean field (DRMF) calculation, using the NL1 parameter set, we [16] predicted. = 120.

  10. Magicity of neutron-rich nuclei within relativistic self-consistent approaches

    Directory of Open Access Journals (Sweden)

    Jia Jie Li

    2016-02-01

    Full Text Available The formation of new shell gaps in intermediate mass neutron-rich nuclei is investigated within the relativistic Hartree–Fock–Bogoliubov theory, and the role of the Lorentz pseudo-vector and tensor interactions is analyzed. Based on the Foldy–Wouthuysen transformation, we discuss in detail the role played by the different terms of the Lorentz pseudo-vector and tensor interactions in the appearing of the N=16, 32 and 34 shell gaps. The nuclei 24O, 48Si and 52,54Ca are predicted with a large shell gap and zero (24O, 52Ca or almost zero (48Si, 54Ca pairing gap, making them candidates for new magic numbers in exotic nuclei. We find from our analysis that the Lorentz pseudo-vector and tensor interactions induce very specific evolutions of single-particle energies, which could clearly sign their presence and reveal the need for relativistic approaches with exchange interactions.

  11. Determination of spin, magnetic moment and isotopic shift of neutron rich 205Hg by optical pumping

    International Nuclear Information System (INIS)

    Rodriguez, J.; Bonn, J.; Huber, G.; Kluge, H.J.; Otten, E.W.; European Organisation for Nuclear Research, Geneva

    1975-01-01

    Neutron rich 205 Hg(Tsub(1/2) = 5.2 min) was produced and on-line mass separated at the ISOLDE facility at CERN. The polarization achieved by optical pumping via the atomic line (6s 21 S 0 - 6s6p 3 P 1 , lambda = 2,537 A) was monitored by the β decay asymmetry. Hyperfine structure and isotopic shift of the 205 Hg absorption line was determined by Zeeman scanning. In addition a magnetic resoncance was performed on the polarized 205 Hg nuclei in the atomic ground state. The results are: I( 205 Hg) = 1/2 (confirmed); μ(I, 205 Hg) = 0.5915(1)μ(N) (uncorrected for diamagnetism); isotopic shift deltaν(204/205) = ν( 205 Hg) - ν( 204 Hg) = -1.8(1)GHz. μ(I) and IS are discussed briefly in the frame of current literature. (orig.) [de

  12. Mass measurements of neutron-rich indium isotopes toward the N =82 shell closure

    Science.gov (United States)

    Babcock, C.; Klawitter, R.; Leistenschneider, E.; Lascar, D.; Barquest, B. R.; Finlay, A.; Foster, M.; Gallant, A. T.; Hunt, P.; Kootte, B.; Lan, Y.; Paul, S. F.; Phan, M. L.; Reiter, M. P.; Schultz, B.; Short, D.; Andreoiu, C.; Brodeur, M.; Dillmann, I.; Gwinner, G.; Kwiatkowski, A. A.; Leach, K. G.; Dilling, J.

    2018-02-01

    Precise mass measurements of the neutron-rich In-130125 isotopes have been performed with the TITAN Penning trap mass spectrometer. TITAN's electron beam ion trap was used to charge breed the ions to charge state q =13 + thus providing the necessary resolving power to measure not only the ground states but also isomeric states at each mass number. In this paper, the properties of the ground states are investigated through a series of mass differentials, highlighting trends in the indium isotopic chain as compared to its proton-magic neighbor, tin (Z =50 ). In addition, the energies of the indium isomers are presented. The (8-) level in 128In is found to be 78 keV lower than previously thought and the (21 /2- ) isomer in 127In is shown to be lower than the literature value by more than 150 keV.

  13. Shape transitions in neutron rich 110-112Ru nuclei and empirical relations

    International Nuclear Information System (INIS)

    Bihari, Chhail; Singh, Yuvraj; Gupta, K.K.; Varshney, A.K.; Singh, M.; Gupta, D.K.

    2010-01-01

    In the study of even even neutron rich Ru isotopes, the electromagnetic properties of the γ-vibrational bands are well described by a rigid triaxial rotor for lower spin state and by the rotation vibration collective model for the higher spin states. Thus interpretation in further suggested by the observation of nearly identical moment of inertia, the rotational frequency below the first band crossing, between the ground state and the γ-structural bands for both 110 Ru and 112 Ru which conclude a weak pairing, a more likely suitable explanation of observations. In the present work, the soft rotor energy formula is undertaken suggested by Brentano et al. for yrast band, may be employed to calculate the perturbed energies of the anomalous rotational band (γ-band) generated by rotation of the rigid asymmetric atomic nucleus and the two parameter formula (TPF) of Gupta et al.

  14. Observation of isoscalar and isovector dipole excitations in neutron-rich 20O

    Directory of Open Access Journals (Sweden)

    N. Nakatsuka

    2017-05-01

    Full Text Available The isospin characters of low-energy dipole excitations in neutron-rich unstable nucleus 20O were investigated, for the first time in unstable nuclei. Two spectra obtained from a dominant isovector probe (O20+Au and a dominant isoscalar probe (O20+α were compared and analyzed by the distorted-wave Born approximation to extract independently the isovector and isoscalar dipole strengths. Two known 1− states with large isovector dipole strengths at energies of 5.36(5 MeV (11− and 6.84(7 MeV (12− were also excited by the isoscalar probe. These two states were found to have different isoscalar dipole strengths, 2.70(32% (11− and 0.67(12% (12−, respectively, in exhaustion of the isoscalar dipole-energy-weighted sum rule. The difference in isoscalar strength indicated that they have different underlying structures.

  15. Quadrupole collectivity beyond N = 50 in neutron- rich Se and Kr isotopes

    Science.gov (United States)

    Elman, Brandon; Gade, A.; Barofsky, D.; Bender, P. C.; Bowry, M.; Hjorth-Jensen, M.; Kemper, K. W.; Lipschutz, S.; Lunderberg, E.; Sachmpazidi, N.; Terpstra, N.; Walters, W. B.; Weisshaar, D.; Westerberg, A.; Williams, S. J.; Wimmer, K.

    2017-09-01

    We will present results on measuring the B (E 2 ;01+ ->2n+) strength for the neutron-rich 88,90Kr and 86Se isotopes from intermediate-energy Coulomb excitation. The electric quadrupole transition strengths to the first 2+ state complete, with considerably improved uncertainties, the evolution of quadrupole collectivity in the Kr and Se isotopes approaching N = 60 , for which 90Kr and 86Se had previously been the most uncertain. We also report significant excitation strength to several higher lying 2+ states in the krypton isotopes. The results confirm shell model calculations in the π (fpg) - ν (sdg) shell with only a minimally tuned shell model setup that is based on a nucleon-nucleon interaction derived from effective field theory with effective charges adjusted to 86Kr.

  16. Excited-state lifetimes in neutron-rich Ce isotopes from EXILL and FATIMA

    Energy Technology Data Exchange (ETDEWEB)

    Koseoglou, P.; Pietralla, N.; Stoyanka, I.; Kroell, T. [IKP, TU-Darmstadt, Darmstadt (Germany); Werner, V. [IKP, TU-Darmstadt, Darmstadt (Germany); Yale University (United States); Bernards, C.; Cooper, N. [Yale University (United States); Blanc, A.; Jentschel, M.; Koester, U.; Mutti, P.; Soldner, T.; Urban, W. [ILL Grenoble (France); Bruce, A.M.; Roberts, O.J. [University of Brighton (United Kingdom); Cakirli, R.B. [MPIK Heidelberg (Germany); France, G. de [GANIL Caen (France); Humby, P.; Patel, Z.; Podolyak, Zs.; Regan, P.H.; Wilson, E. [University of Surrey (United Kingdom); Jolie, J.; Regis, J.-M.; Saed-Samii, N.; Wilmsen, D. [KP, University of Cologne (Germany); Paziy, V. [Universidad Complutense (Spain); Simpson, G.S. [PSC Grenoble (France); Ur, C.A. [INFN Legnaro (Italy)

    2016-07-01

    {sup 235}U and {sup 241}Pu fission fragments were measured by a mixed spectrometer consisting of high-resolution Ge and fast LaBr{sub 3}(Ce)-scintillator detectors at the high-flux reactor of the ILL. Prompt γ-ray cascades from the nuclei of interest are selected via Ge-Ge-LaBr{sub 3}-LaBr{sub 3} coincidences. The good energy resolution of the Ge allow precise gates to be set, selecting the cascade, hence, the nucleus of interest. The excellent timing performance of the LaBr{sub 3} detectors in combination with the General Centroid Difference method allows the measurement of lifetimes in the ps range in preparation for the FATIMA experiment at FAIR. The first results on neutron-rich Ce isotopes are presented.

  17. Half-lives of cluster decay of neutron rich nuclei in trans-tin region

    International Nuclear Information System (INIS)

    Swamy, G.S.; Umesh, T.K.

    2011-01-01

    In this work, the logarithmic half-life [log 10 (T 1/2 )] values have been reported for the exotic decay of some neutron rich even–even parent nuclei (56≤Z≤64) accompanied by the emission of alpha-like and non-alpha-like clusters in the trans-tin region. These values were calculated by using the single line of universal curve (UNIV) for alpha and cluster radioactive decay as well as the universal decay law (UDL). The half-life values were also separately calculated by considering the interacting nuclear potential barrier as the sum of Coulomb and proximity potentials. The half-life values based on the three calculations mentioned above, were found to agree with one another within a few orders of magnitude. Possible conclusions are drawn based on the present study. (author)

  18. Superheavy nuclei and quasi-atoms produced in collisions of transuranium ions

    International Nuclear Information System (INIS)

    Zagrebaev, V.; Oganessian, Y.; Itkis, M.; Greiner, W.

    2005-01-01

    , may remain in contact rather long time. This time delay (up to 10 -19 s) could significantly increase the yield of the so-called spontaneous positron emission from super-strong electric field of quasi-atoms by a static QED process (transition from neutral to charged QED vacuum). This effect was searched sometime ago at GSI but no clear evidences of it have been found. New experiments may be performed now based on our new knowledge of collision dynamics of these nuclei. About twenty years ago damped collisions of very heavy nuclei have been used also for production of chemically separated long-lived actinides. The cross sections were found to be exponentially decreasing with increase of a charge number of heavier fragment, up to the level of 0.1 μb for production of Md isotopes in U + Cm collisions. A new effect, which we found here, is the 'inverse quasi-fission' process. In this process a superheavy nuclear system, say Th + Cf, travelling over the multidimensional potential energy surface, changes its mass asymmetry and may fall into the so-called lead valley. If Th comes to Pb, then Cf grows to the element 106. In spite of rather high excitation energy and low survival probability of residual fragments, this effect significantly increases the yield of nuclei complementary to lead and give us a new way for production of neutron rich (more close to the island of stability) superheavy elements in addition to the extensively used complete fusion reactions. These and some other prospects of subsequent theoretical and experimental studies along with possible collaborations in the field will be discussed in the talk

  19. Microscopic multiphonon approach to spectroscopy in the neutron-rich oxygen region

    Science.gov (United States)

    De Gregorio, G.; Knapp, F.; Lo Iudice, N.; Veselý, P.

    2018-03-01

    Background: A fairly rich amount of experimental spectroscopic data have disclosed intriguing properties of the nuclei in the region of neutron rich oxygen isotopes up to the neutron dripline. They, therefore, represent a unique laboratory for studying the evolution of nuclear structure away from the stability line. Purpose: We intend to give an exhaustive microscopic description of low and high energy spectra, dipole response, weak, and electromagnetic properties of the even 22O and the odd 23O and 23F. Method: An equation of motion phonon method generates an orthonormal basis of correlated n -phonon states (n =0 ,1 ,2 ,⋯ ) built of constituent Tamm-Dancoff phonons. This basis is adopted to solve the full eigenvalue equations in even nuclei and to construct an orthonormal particle-core basis for the eigenvalue problem in odd nuclei. No approximations are involved and the Pauli principle is taken into full account. The method is adopted to perform self-consistent, parameter free, calculations using an optimized chiral nucleon-nucleon interaction in a space encompassing up to two-phonon basis states. Results: The computed spectra in 22O and 23O and the dipole cross section in 22O are in overall agreement with the experimental data. The calculation describes poorly the spectrum of 23F. Conclusions: The two-phonon configurations play a crucial role in the description of spectra and transitions. The large discrepancies concerning the spectra of 23F are ultimately traced back to the large separation between the Hartree-Fock levels belonging to different major shells. We suggest that a more compact single particle spectrum is needed and can be generated by a new chiral potential which includes explicitly the contribution of the three-body forces.

  20. Decay studies and mass measurements on isobarically pure neutron-rich Hg and Tl isotopes

    CERN Multimedia

    Schweikhard, L C; Savreux, R P; Hager, U D K; Beck, D; Blaum, K

    2007-01-01

    We propose to perform mass measurements followed by $\\beta$- and $\\gamma$-decay studies on isobarically pure beams of neutron-rich Hg and Tl isotopes, which are very poorly known due to a large contamination at ISOL-facilities with surface-ionised francium. The aim is to study the binding energies of mother Hg and Tl nuclides, as well as the energies, spins and parities of the excited and ground states in the daughter Tl and Pb isotopes. The proposed studies will address a new subsection of the nuclear chart, with Z 126, where only 9 nuclides have been observed so far. Our studies will provide valuable input for mass models and shell-model calculations: they will probe the proton hole-neutron interaction and will allow to refine the matrix elements for the two-body residual interaction. Furthermore, they also give prospects for discovering new isomeric states or even new isotopes, for which the half-lives are predicted in the minute- and second-range.\\\\ To reach the isobaric purity, the experiments will be p...

  1. Coulomb Excitation of a Neutron-Rich $^{88}$Kr Beam Search for Mixed Symmetry States

    CERN Multimedia

    Andreoiu, C; Napiorkowski, P J; Iwanicki, J S

    2002-01-01

    We propose to use the ISOLDE/REX/MINIBALL/CD set-up to perform a Coulomb Excitation experiment with a $^{88}$Kr radioactive beam. The motivation includes a search for $Mixed$ $Symmetry$ states predicted by the IBM-2 model, gathering more spectroscopy data about the $^{88}$Kr nucleus and extending shape coexistence studies (performed previously by the proposers for neutron-deficient Kr isotopes) to the neutron-rich side. The proposed experiment will provide data complementary to the Coulomb Excitation of a relativistic $^{88}$Kr beam proposed by D. Tonev et al. for a RISING experiment. A total of 12 days of beam time is necessary for the experiment, equally divided into two runs. One run with a 2.2 MeV/A beam energy on a $^{48}$Ti target and a second run with the maximum available REX energy of 3.1 MeV/A on a $^{208}$Pb target are requested. Using either a UC$_{x}$ or ThC$_{x}$ fissioning primary target coupled with a plasma source by a cooled transfer line seems to be the best choice for the proposed experime...

  2. Evolution of Single Particle and Collective properties in the Neutron-Rich Mg Isotopes

    CERN Multimedia

    Reiter, P; Wiens, A; Fitting, J; Lauer, M; Van duppen, P L E; Finke, F

    2002-01-01

    We propose to study the single particle and collective properties of the neutron-rich Mg isotopes in transfer reactions and Coulomb excitation using REX-ISOLDE and MINIBALL. From the Coulomb excitation measurement precise and largely model independent B( E2 ; 0$^{+}_{g.s.}\\rightarrow$ 2$^{+}_{1}$ ) will be determined for the even-even isotopes. For the odd isotopes the distribution of the E2 strength over a few low-lying states will be measured. The sign of the M1/E2 mixing ratio, extracted from angular distributions, is characteristic of the sign of the deformation, as is the resulting level scheme. The neutron-pickup channel in the transfer reactions will allow for a determination of the single particle properties (spin, parity, spectroscopic factors) of these nuclei. This information will give new insights in changes of nuclear structure in the vicinity of the island of deformation around $^{32}$Mg. A total of 24 shifts of REX beam time is requested.

  3. Low-energy Coulomb excitation of neutron-rich zinc isotopes

    CERN Document Server

    Van de Walle, J; Behrens, T; Bildstein, V; Blazhev, A; Cederkäll, J; Clément, E; Cocolios, T E; Davinson, T; Delahaye, P; Eberth, J; Ekström, A; Fedorov, D V; Fedosseev, V; Fraile, L M; Franchoo, S; Gernhäuser, R; Georgiev, G; Habs, D; Heyde, K; Huber, G; Huyse, M; Ibrahim, F; Ivanov, O; Iwanicki, J; Jolie, J; Kester, O; Köster, U; Kröll, T; Krücken, R; Lauer, M; Lisetskiy, A F; Lutter, R; Marsh, B A; Mayet, P; Niedermaier, O; Pantea, M; Raabe, R; Reiter, P; Sawicka, M; Scheit, H; Schrieder, G; Schwalm, D; Seliverstov, M D; Sieber, T; Sletten, G; Smirnova, N; Stanoiu, M; Stefanescu, I; Thomas, J C; Valiente-Dobón, J J; Van Duppen, P; Verney, D; Voulot, D; Warr, N; Weisshaar, D; Wenander, F; Wolf, B H; Zielinska, M

    2009-01-01

    At the radioactive ion beam facility REX-ISOLDE, neutron-rich zinc isotopes were investigated using low-energy Coulomb excitation. These experiments have resulted in B(E2,20) values in 74-80Zn, B(E2,42) values in 74,76Zn and the determination of the energy of the first excited 2 states in 78,80Zn. The zinc isotopes were produced by high-energy proton- (A=74,76,80) and neutron- (A=78) induced fission of 238U, combined with selective laser ionization and mass separation. The isobaric beam was postaccelerated by the REX linear accelerator and Coulomb excitation was induced on a thin secondary target, which was surrounded by the MINIBALL germanium detector array. In this work, it is shown how the selective laser ionization can be used to deal with the considerable isobaric beam contamination and how a reliable normalization of the experiment can be achieved. The results for zinc isotopes and the N=50 isotones are compared to collective model predictions and state-of-the-art large-scale shell-model calculations, i...

  4. Shape of 44Ar: Onset of deformation in neutron-rich nuclei near 48Ca

    International Nuclear Information System (INIS)

    Zielinska, M.; Goergen, A.; Clement, E.; Korten, W.; Dossat, C.; Ljungvall, J.; Obertelli, A.; Theisen, Ch.; Delaroche, J.-P.; Girod, M.; Buerger, A.; Catford, W.; Iwanicki, J.; Napiorkowski, P. J.; Srebrny, J.; Wrzosek, K.; Libert, J.; PiePtak, D.; Rodriguez-Guzman, R.; Sletten, G.

    2009-01-01

    The development of deformation and shape coexistence in the vicinity of doubly magic 48 Ca, related to the weakening of the N=28 shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive 44 Ar beam from the SPIRAL facility at GANIL. The 2 1 + and 2 2 + states in 44 Ar were excited on 208 Pb and 109 Ag targets at two different beam energies. B(E2) values between all observed states and the spectroscopic quadrupole moment of the 2 1 + state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the 44 Ar nucleus and giving evidence of an onset of deformation already two protons and two neutrons away from doubly magic 48 Ca. New Hartree-Fock-Bogoliubov based configuration mixing calculations have been performed with the Gogny D1S interaction for 44 Ar 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.

  5. Study of the structure of yrast bands of neutron-rich 114-124Pd isotopes

    Science.gov (United States)

    Chaudhary, Ritu; Devi, Rani; Khosa, S. K.

    2018-02-01

    The projected shell model calculations have been carried out in the neutron-rich 114-124Pd isotopic mass chain. The results have been obtained for the deformation systematics of E(2+1) and E(4+1)/E({2}+1) values, BCS subshell occupation numbers, yrast spectra, backbending phenomena, B( E2) transition probabilities and g-factors in these nuclei. The observed systematics of E(2+1) values and R_{42} ratios in the 114-124Pd isotopic mass chain indicate that there is a decrease of collectivity as the neutron number increases from 68 to 78. The occurrence of backbending in these nuclei as well as the changes in the calculated B( E2) transition probabilities and g -factors predict that there are changes in the structure of yrast bands in these nuclei. These changes occur at the spin where there is crossing of g-band by 2-qp bands. The predicted backbendings and predicted values of B( E2)s and g-factors in some of the isotopes need to be confirmed experimentally.

  6. Gamma-ray spectroscopy of neutron-rich products of heavy-ion collisions

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, M.P.; Janssens, R.V.F.; Ahmad, I. [and others

    1995-08-01

    Thick-target {gamma}{gamma} coincidence techniques are being used to explore the spectroscopy of otherwise hard-to-reach neutron-rich products of deep-inelastic heavy ion reactions. Extensive {gamma}{gamma} coincidence measurements were performed at ATLAS using pulsed beams of {sup 80}Se, {sup 136}Xe, and {sup 238}U on lead-backed {sup 122,124}Sn targets with energies 10-15% above the Coulomb barrier. Gamma-ray coincidence intensities were used to map out yield distributions with A and Z for even-even product nuclei around the target and around the projectile. The main features of the yield patterns are understandable in terms of N/Z equilibration. We had the most success in studying the decays of yrast isomers. Thus far, more than thirty new {mu}s isomers in the Z = 50 region were found and characterized. Making isotopic assignments for previously unknown {gamma}-ray cascades proves to be one of the biggest problems. Our assignments were based (a) on rare overlaps with radioactivity data, (b) on the relative yields with different beams, and (c) on observed cross-coincidences between {gamma} rays from light and heavy reaction partners. However, the primary products of deep inelastic collisions often are sufficiently excited for subsequent neutron evaporation, so {gamma}{gamma} cross-coincidence results require careful interpretation.

  7. Antisymmetrized molecular dynamics studies for exotic clustering phenomena in neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, M. [Hokkaido University, Department of Physics, Sapporo (Japan); Hokkaido University, Nuclear Reaction Data Centre, Faculty of Science, Sapporo (Japan); Suhara, T. [Matsue College of Technology, Matsue (Japan); Kanada-En' yo, Y. [Kyoto University, Department of Physics, Kyoto (Japan)

    2016-12-15

    We present a review of recent works on clustering phenomena in unstable nuclei studied by antisymmetrized molecular dynamics (AMD). The AMD studies in these decades have uncovered novel types of clustering phenomena brought about by the excess neutrons. Among them, this review focuses on the molecule-like structure of unstable nuclei. One of the earliest discussions on the clustering in unstable nuclei was made for neutron-rich Be and B isotopes. AMD calculations predicted that the ground state clustering is enhanced or reduced depending on the number of excess neutrons. Today, the experiments are confirming this prediction as the change of the proton radii. Behind this enhancement and reduction of the clustering, there are underlying shell effects called molecular and atomic orbits. These orbits form covalent and ionic bonding of the clusters analogous to the atomic molecules. It was found that this ''molecular-orbit picture'' reasonably explains the low-lying spectra of Be isotopes. The molecular-orbit picture is extended to other systems having parity asymmetric cluster cores and to the three cluster systems. O and Ne isotopes are the candidates of the former, while the 3α linear chains in C isotopes are the latter. For both subjects, many intensive studies are now in progress. We also pay a special attention to the observables which are the fingerprint of the clustering. In particular, we focus on the monopole and dipole transitions which are recently regarded as good probe for the clustering. We discuss how they have and will reveal the exotic clustering. (orig.)

  8. Production and separation of neutron-rich rare isotopes around and below the Fermi energy

    CERN Document Server

    Souliotis, G A; Chubarian, G; Yennello, S J

    2003-01-01

    The production of n-rich rare isotopes around and below the Fermi energy is investigated using beams from the K500 Superconducting Cyclotron and the MARS recoil separator at the Cyclotron Institute of Texas A and M University. The experimental results from the reactions of 25 MeV/nucleon sup 8 sup 6 Kr + sup 6 sup 4 Ni and 21 MeV/nucleon sup 1 sup 2 sup 4 Sn + sup 1 sup 2 sup 4 Sn are presented and compared with simulations. The calculations involve a deep inelastic transfer (DIT) code for the primary interaction stage followed by the code GEMINI for the de-excitation stage. The results are also compared with the EPAX parametrization. The data on the 25 MeV/nucleon sup 8 sup 6 Kr + sup 6 sup 4 Ni reaction show that both proton-removal and several-neutron pick-up isotopes are produced. An enhancement is observed in the production of n-rich isotopes close to the projectile relative to the predictions of DIT/GEMINI and the expectations of EPAX. The data of 21 MeV/nucleon sup 1 sup 2 sup 4 Sn + sup 1 sup 2 sup 4 ...

  9. Reactions of neutron-rich Sn isotopes investigated at relativistic energies at R{sup 3}B

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Fabia; Aumann, Thomas; Johansen, Jacob; Schrock, Philipp [IKP, TU Darmstadt (Germany); Boretzky, Konstanze [GSI Helmholtzzentrum (Germany); Collaboration: R3B-Collaboration

    2015-07-01

    Reactions of neutron-rich tin isotopes in a mass range of A=124 to A=134 have been measured at the R{sup 3}B setup at GSI in inverse kinematics. Due to the neutron excess, which results in a weaker binding of the valence neutrons such isotopes are expected to form a neutron skin. The investigation of this phenomenon is an important goal in nuclear-structure physics. Reactions of the tin isotopes with different targets have been performed kinematically complete. The taken data set therefore allows for the extraction of the neutron-skin thickness from two independent reaction channels. These are dipole excitations on the one hand and nuclear-induced reactions on the other hand. This contribution focuses on the latter mechanism. The analysis techniques which are used to extract the total charge-changing as well as the total neutron-removal cross section are presented using the example of {sup 124}Sn. The total neutron-removal cross section is of particular interest because of its high sensitivity to the neutron-skin thickness.

  10. Probing the collectivity in neutron-rich Cd isotopes via γ-ray spectroscopy

    International Nuclear Information System (INIS)

    Naqvi, Farheen

    2011-01-01

    The spin and configurational structure of excited states of 127 Cd, 125 Cd and 129 Cd, having two proton and three, five and one neutron holes, respectively in the doubly magic 132 Sn core have been studied. The isomeric states in Cd isotopes were populated in the fragmentation of a 136 Xe beam at an energy of 750 MeV/u on a 9 Be target of 4 g/cm 2 . The experiment was performed at GSI Darmstadt. The neutron-rich Cd isotopes were selected using the Bρ - ΔE - Bρ method at the FRagment Separator (FRS). Event by event identification of fragments in terms of their A (mass) and Z (charge) was provided by the standard FRS detectors. The reaction residues were implanted in a plastic stopper surrounded by 15 Ge cluster detectors from the RISING array to detect the γ decays. In 127 Cd, an isomeric state with a half-life of 17.5(3) μs has been detected. This yrast (19/2) + isomer is proposed to have mixed proton-neutron configurations and to decay by two competing stretched M2 and E3 transitions. Experimental results are compared with the isotone 129 Sn. In 125 Cd, apart from the previously observed (19/2) + isomer, two new metastable states at 3896 keV and 2141 keV have been detected. A half-life of 13.6(2) μs was measured for the (19/2) + isomer, having a decay structure similar to the corresponding isomeric state in 127 Cd. The higher lying isomers have a half-life of 3.1(1) μs and 2.5(15) ns, respectively. Time distributions of delayed γ transitions and γγ-coincidence relations were exploited to construct decay schemes for the two nuclei. Comparison of the experimental data with shell-model calculations is also discussed. The new information provides input for the proton-neutron interaction in nuclei around the doubly magic 132 Sn core. The γ decays of the isomeric states in 129 Cd were not observed experimentally. The reasons for the non-observation of delayed γ rays for 129 Cd are either an isomeric half-life of less than 93 ns based on the experimentally

  11. Shape Evolution in Neutron-Rich Krypton Isotopes Beyond N=60: First Spectroscopy of ^{98,100}Kr.

    Science.gov (United States)

    Flavigny, F; Doornenbal, P; Obertelli, A; Delaroche, J-P; Girod, M; Libert, J; Rodriguez, T R; Authelet, G; Baba, H; Calvet, D; Château, F; Chen, S; Corsi, A; Delbart, A; Gheller, J-M; Giganon, A; Gillibert, A; Lapoux, V; Motobayashi, T; Niikura, M; Paul, N; Roussé, J-Y; Sakurai, H; Santamaria, C; Steppenbeck, D; Taniuchi, R; Uesaka, T; Ando, T; Arici, T; Blazhev, A; Browne, F; Bruce, A; Carroll, R; Chung, L X; Cortés, M L; Dewald, M; Ding, B; Franchoo, S; Górska, M; Gottardo, A; Jungclaus, A; Lee, J; Lettmann, M; Linh, B D; Liu, J; Liu, Z; Lizarazo, C; Momiyama, S; Moschner, K; Nagamine, S; Nakatsuka, N; Nita, C; Nobs, C R; Olivier, L; Orlandi, R; Patel, Z; Podolyák, Zs; Rudigier, M; Saito, T; Shand, C; Söderström, P A; Stefan, I; Vaquero, V; Werner, V; Wimmer, K; Xu, Z

    2017-06-16

    We report on the first γ-ray spectroscopy of low-lying states in neutron-rich ^{98,100}Kr isotopes obtained from ^{99,101}Rb(p,2p) reactions at ∼220  MeV/nucleon. A reduction of the 2_{1}^{+} state energies beyond N=60 demonstrates a significant increase of deformation, shifted in neutron number compared to the sharper transition observed in strontium and zirconium isotopes. State-of-the-art beyond-mean-field calculations using the Gogny D1S interaction predict level energies in good agreement with experimental results. The identification of a low-lying (0_{2}^{+}, 2_{2}^{+}) state in ^{98}Kr provides the first experimental evidence of a competing configuration at low energy in neutron-rich krypton isotopes consistent with the oblate-prolate shape coexistence picture suggested by theory.

  12. Precision mass measurements on neutron-rich Zn isotopes and their consequences on the astrophysical r-process

    Energy Technology Data Exchange (ETDEWEB)

    Baruah, Sudarshan

    2008-07-15

    The rapid neutron-capture or the r-process is responsible for the origin of about half of the neutron-rich atomic nuclei in the universe heavier than iron. For the calculation of the abundances of those nuclei, atomic masses are required as one of the input parameters with very high precision. In the present work, the masses of the neutron rich Zn isotopes (A=71 to 81) lying in the r-process path have been measured in the ISOLTRAP experiment at ISOLDE/CERN. The mass of {sup 81}Zn has been measured directly for the rst time. The half-lives of the nuclides ranged from 46.5 h ({sup 72}Zn) down to 290 ms ({sup 81}Zn). In case of all the nuclides, the relative mass uncertainty ({delta}m=m) achieved was in the order of 10{sup -8} corresponding to a 100-fold improvement in precision over previous measurements. (orig.)

  13. Precision mass measurements on neutron-rich Zn isotopes and their consequences on the astrophysical r-process

    International Nuclear Information System (INIS)

    Baruah, Sudarshan

    2008-07-01

    The rapid neutron-capture or the r-process is responsible for the origin of about half of the neutron-rich atomic nuclei in the universe heavier than iron. For the calculation of the abundances of those nuclei, atomic masses are required as one of the input parameters with very high precision. In the present work, the masses of the neutron rich Zn isotopes (A=71 to 81) lying in the r-process path have been measured in the ISOLTRAP experiment at ISOLDE/CERN. The mass of 81 Zn has been measured directly for the rst time. The half-lives of the nuclides ranged from 46.5 h ( 72 Zn) down to 290 ms ( 81 Zn). In case of all the nuclides, the relative mass uncertainty (Δm=m) achieved was in the order of 10 -8 corresponding to a 100-fold improvement in precision over previous measurements. (orig.)

  14. A probability of synthesis of the superheavy element Z = 124

    Energy Technology Data Exchange (ETDEWEB)

    Manjunatha, H.C. [Government College for Women, Department of Physics, Kolar, Karnataka (India); Sridhar, K.N. [Government First Grade College, Department of Physics, Kolar, Karnataka (India)

    2017-10-15

    We have studied the fusion cross section, evaporation residue cross section, compound nucleus formation probability (P{sub CN}) and survival probability (P{sub sur}) of different projectile target combinations to synthesize the superheavy element Z=124. Hence, we have identified the most probable projectile-target combination to synthesize the superheavy element Z = 124. To synthesize the superheavy element Z=124, the most probable projectile target combinations are Kr+Ra, Ni+Cm, Se+Th, Ge+U and Zn+Pu. We hope that our predictions may be a guide for the future experiments in the synthesis of superheavy nuclei Z = 124. (orig.)

  15. Electronic structure and chemical properties of superheavy elements

    Energy Technology Data Exchange (ETDEWEB)

    Pershina, V [Gesellschaft fuer Schwerionenforschung (GSI), Helmholtzzentrum fuer Schwerionenforschung Gmbh (Germany)

    2009-12-31

    Relativistic electronic structure calculations of superheavy elements (Z>=104) are analyzed. Preference is given to those related to experimental research. The role of relativistic effects is discussed.

  16. Krypton and xenon in Apollo 14 samples - Fission and neutron capture effects in gas-rich samples

    Science.gov (United States)

    Drozd, R.; Hohenberg, C.; Morgan, C.

    1975-01-01

    Gas-rich Apollo 14 breccias and trench soil are examined for fission xenon from the decay of the extinct isotopes Pu-244 and I-129, and some samples have been found to have an excess fission component which apparently was incorporated after decay elsewhere and was not produced by in situ decay. Two samples have excess Xe-129 resulting from the decay of I-129. The excess is correlated at low temperatures with excess Xe-128 resulting from neutron capture on I-127. This neutron capture effect is accompanied by related low-temperature excesses of Kr-80 and Kr-82 from neutron capture on the bromine isotopes. Surface correlated concentrations of iodine and bromine are calculated from the neutron capture excesses.

  17. Covariant description of shape evolution and shape coexistence in neutron-rich nuclei at N≈60

    International Nuclear Information System (INIS)

    Xiang, J.; Li, Z.P.; Li, Z.X.; Yao, J.M.; Meng, J.

    2012-01-01

    The shape evolution and shape coexistence phenomena in neutron-rich nuclei at N≈60, including Kr, Sr, Zr, and Mo isotopes, are studied in the covariant density functional theory (DFT) with the new parameter set PC-PK1. Pairing correlations are treated using the BCS approximation with a separable pairing force. Sharp rising in the charge radii of Sr and Zr isotopes at N=60 is observed and shown to be related to the rapid changing in nuclear shapes. The shape evolution is moderate in neighboring Kr and Mo isotopes. Similar as the results of previous Hartree–Fock–Bogoliubov (HFB) calculations with the Gogny force, triaxiality is observed in Mo isotopes and shown to be essential to reproduce quantitatively the corresponding charge radii. In addition, the coexistence of prolate and oblate shapes is found in both 98 Sr and 100 Zr. The observed oblate and prolate minima are related to the low single-particle energy level density around the Fermi surfaces of neutron and proton respectively. Furthermore, the 5-dimensional (5D) collective Hamiltonian determined by the calculations of the PC-PK1 energy functional is solved for 98 Sr and 100 Zr. The resultant excitation energy of 0 2 + state and E0 transition strength ρ 2 (E0;0 2 + →0 1 + ) are in rather good agreement with the data. It is found that the lower barrier height separating the two competing minima along the γ deformation in 100 Zr gives rise to the larger ρ 2 (E0;0 2 + →0 1 + ) than that in 98 Sr.

  18. Neutron-rich Λ-Hypernuclei study with the FINUDA experiment

    Directory of Open Access Journals (Sweden)

    Botta E.

    2014-03-01

    Full Text Available The FINUDA experiment at DAΦNE, Frascati, has found evidence for the neutron-rich hypernucleus HΛ6${}_ \\wedge ^6{\\rm{H}}$ studying (π+, π− pairs in coincidence from the Kstop−+L6i→HΛ6+π+$K_{{\\rm{stop}}}^ - + {}^{\\rm{6}}{\\rm{Li}} \\to {}_ \\wedge ^6{\\rm{H}} + {\\pi ^ + }$ production reaction followed by HΛ6→H6e +π−${}_ \\wedge ^6{\\rm{H}} \\to {}^6{\\rm{He + }}{\\pi ^ - }$ weak decay. The production rate of HΛ6${}_ \\wedge ^6{\\rm{H}}$ undergoing this two-body π− decay has been found to be (2.9±2.0⋅10−6/Kstop−$(2.9 \\pm 2.0 \\cdot {10^{ - 6}}/K_{{\\rm{stop}}}^ - $. Its binding energy has been evaluated to be BΛ(HΛ6=(4.0±1.1${B_ \\wedge }({}_ \\wedge ^6H = (4.0 \\pm 1.1$ MeV with respect to (H5+Λ$({}^5{\\rm{H}} + \\Lambda $, jointly from production and decay. A systematic difference of (0.98 ± 0.74 MeV between BΛ values derived separately from decay and from production has been tentatively assigned to the HΛ6 0g.s.+→1+${}_\\Lambda ^6{\\rm{H 0}}_{{\\rm{g}}{\\rm{.s}}{\\rm{.}}}^ + \\to {1^ + }$ excitation. A similar investigation has been carried out for the neutron-rich hypernucleus HΛ9e${}_\\Lambda ^9{\\rm{He}}$ studying the Kstop−+B9e→HΛ9e+π+$K_{{\\rm{stop}}}^ - + {}_{}^{\\rm{9}}{\\rm{Be}} \\to {}_\\Lambda ^9{\\rm{He}} + {\\pi ^ + }$ reaction in coincidence with the H Λ 9e→ L 9i +  π −${}_\\Lambda ^9{\\rm{He}} \\to {}_{}^{\\rm{9}}{\\rm{Li + }}{\\pi ^ - }$ weak decay; an upper limit for the production rate of HΛ9e${}_\\Lambda ^9{\\rm{He}}$ undergoing the two-body π− decay has been found to be 4.2⋅10 −6 /K stop− $4.2 \\cdot {10^{ - 6}}/{\\rm{K}}_{stop}^ - $ (90% C.L..

  19. Quasifree (p ,p N ) scattering of light neutron-rich nuclei near N =14

    Science.gov (United States)

    Díaz Fernández, P.; Alvarez-Pol, H.; Crespo, R.; Cravo, E.; Atar, L.; Deltuva, A.; Aumann, T.; Avdeichikov, V.; Beceiro-Novo, S.; Bemmerer, D.; Benlliure, J.; Bertulani, C. A.; Boillos, J. M.; Boretzky, K.; Borge, M. J. G.; Caamaño, M.; Cabanelas, P.; Caesar, C.; Casarejos, E.; Catford, W.; Cederkäll, J.; Chartier, M.; Chulkov, L. V.; Cortina-Gil, D.; Datta Pramanik, U.; Dillmann, I.; Elekes, Z.; Enders, J.; Ershova, O.; Estradé, A.; Farinon, F.; Fernández-Domínguez, B.; Fraile, L. M.; Freer, M.; Galaviz, D.; Geissel, H.; Gernhäuser, R.; Golubev, P.; Göbel, K.; Hagdahl, J.; Heftrich, T.; Heil, M.; Heine, M.; Heinz, A.; Henriques, A.; Holl, M.; Hufnagel, A.; Ignatov, A.; Johansson, H. T.; Jonson, B.; Jurčiukonis, D.; Kalantar-Nayestanaki, N.; Kanungo, R.; Kelic-Heil, A.; Knyazev, A.; Kröll, T.; Kurz, N.; Labiche, M.; Langer, C.; Le Bleis, T.; Lemmon, R.; Lindberg, S.; Machado, J.; Marganiec, J.; Moro, A. M.; Movsesyan, A.; Nacher, E.; Najafi, A.; Nikolskii, E.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Perea, A.; Petri, M.; Pietras, B.; Pietri, S.; Plag, R.; Reifarth, R.; Ribeiro, G.; Rigollet, C.; Rossi, D.; Röder, M.; Savran, D.; Scheit, H.; Simon, H.; Sorlin, O.; Syndikus, I.; Taylor, J. T.; Tengblad, O.; Thies, R.; Togano, Y.; Vandebrouck, M.; Velho, P.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Wheldon, C.; Wilson, G.; Winfield, J. S.; Woods, P.; Yakorev, D.; Zhukov, M.; Zilges, A.; Zuber, K.; R3B Collaboration

    2018-02-01

    Background: For many years, quasifree scattering reactions in direct kinematics have been extensively used to study the structure of stable nuclei, demonstrating the potential of this approach. The R 3B collaboration has performed a pilot experiment to study quasifree scattering reactions in inverse kinematics for a stable 12C beam. The results from that experiment constitute the first quasifree scattering results in inverse and complete kinematics. This technique has lately been extended to exotic beams to investigate the evolution of shell structure, which has attracted much interest due to changes in shell structure if the number of protons or neutrons is varied. Purpose: In this work we investigate for the first time the quasifree scattering reactions (p ,p n ) and (p ,2 p ) simultaneously for the same projectile in inverse and complete kinematics for radioactive beams with the aim to study the evolution of single-particle properties from N =14 to N =15 . Method: The structure of the projectiles 23O, 22O, and 21N has been studied simultaneously via (p ,p n ) and (p ,2 p ) quasifree knockout reactions in complete inverse kinematics, allowing the investigation of proton and neutron structure at the same time. The experimental data were collected at the R3B -LAND setup at GSI at beam energies of around 400 MeV/u. Two key observables have been studied to shed light on the structure of those nuclei: the inclusive cross sections and the corresponding momentum distributions. Conclusions: The knockout reactions (p ,p n ) and (p ,2 p ) with radioactive beams in inverse kinematics have provided important and complementary information for the study of shell evolution and structure. For the (p ,p n ) channels, indications of a change in the structure of these nuclei moving from N =14 to N =15 have been observed, i.e., from the 0 d5 /2 shell to the 1 s1 /2 . This supports previous observations of a subshell closure at N =14 for neutron-rich oxygen isotopes and its weakening

  20. Velocity determination of neutron-rich projectile fragments with a ring-imaging Cherenkov detector

    International Nuclear Information System (INIS)

    Zeitelhack, K.

    1992-11-01

    For the velocity determination of relativistic heavy ions (A>100) in the energy range 300A.MeV ≤ E kin ≤ 2A.GeV a highly resolving, compact ring-imaging Cherenkov counter with large dynamical measurement range was developed. The Cherenkov light cone emitted in the flight of a relativistic heavy ion by a liquid layer (C 6 F 14 ) is focused on the entrance window of a one-dimensional position-resolving VUV-sensitive photon detector. This gas detector is operated at atmospheric pressure with a mixture of 90% methane and 10% isobutane with 0.04% TMAE as photosensitive admixture. For 725A.MeV 129 Xe ions a velocity resolution Δβ/β=1.8.10 -3 and a nuclear charge-number resolution ΔZ/Z=5.1.10 -2 was reached. The over the photon energy range 5.4 eV ≤ E γ ≤ 7.2 eV averaged detection efficiency of the detector system was determined to ε tot =2.8%>. At the 0deg magnet spectrometer Fragmentseparator of the GSI Darmstadt the RICH detector was for the first time applied for the identification of nuclear charge number and mass of heavy relativistic projectile fragments. In the experiment the production cross sections of very neutron-rich nuclei by fragmentation of 136 Xe projectiles in the reaction 76A.MeV 136 Xe on 27 Al were determined. From the measured production erates for the production of the double-magic nucleus 132 Zn in this reaction a cross section of σ=(0.4± 0.3 0.6 ) μbarn can be extrapolated. (orig./HSI) [de

  1. Superheavy Elements Challenge Experimental and Theoretical Chemistry

    CERN Document Server

    Zvára, I

    2003-01-01

    When reflecting on the story of superheavy elements, the an experimenter, acknowledges the role, which the predictions of nuclear and chemical theories have played in ongoing studies. Today, the problems of major interest for experimental chemistry are the studies of elements 112 and 114 including their chemical identification. Advanced quantum chemistry calculations of atoms and molecules would be of much help. First experiments with element 112 evidence that the metal is much more volatile and inert than mercury.

  2. Study of Beta-Delayed Neutron Emission by Neutron-Rich Nuclei and Analysis of the Nuclear Reaction Mechanism responsible for the Yields of these Nuclei

    International Nuclear Information System (INIS)

    Bazin, D.

    1987-07-01

    Among the nuclear mechanisms used for the production of nuclei far from stability, the projectile fragmentation process has recently proved its efficiency. However, at Fermi energies, one has to take into account some collective and relaxation effects which drastically modify the production cross-sections. The spectroscopic study of very neutron-rich nuclei is very dependent of these production rates. A study of beta-delayed neutron emission which leads to new measurements of half-lives and neutron delayed emission probabilities is achieved with a liquid scintillator detector. The results which are then compared to different theories are of interest for the understanding of natural production of heavy elements (r processus) [fr

  3. Neutron-rich isotopes around the r-process 'waiting-point' nuclei 2979Cu50 and 3080Zn50

    International Nuclear Information System (INIS)

    Kratz, K.L.; Gabelmann, H.; Pfeiffer, B.; Woehr, A.

    1991-01-01

    Beta-decay half-lives (T 1/2 ) and delayed-neutron emission probabilities (P n ) of very neutron-rich Cu to As nuclei have been measured, among them the new isotopes 77 Cu 48 , 79 Cu 50 , 81 Zn 51 and 84 Ga 53 . With the T 1/2 and P n -values of now four N≅50 'waiting-point' nuclei known, our hypothesis that the r-process has attained a local β-flow equilibrium around A≅80 is further strengthened. (orig.)

  4. Nuclear shell effects in neutron-rich nuclei around N=20 and N=32,34

    CERN Document Server

    Seidlitz, M

    Nuclear shell effects in neutron-rich nuclei around N=20 and N=32,34 were studied by means of reduced transition probabilities, i.e. B(E2) and B(M1) values. To this end a series of Coulomb-excitation experiments, employing radioactive 31Mg and 29,30Na beams, as well as a precise lifetime experiment of excited states in 56Cr were performed. The collective properties of excited states of 31Mg were the subject of a Coulomb-excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31Mg beam at a beam energy of 3.0 MeV/u. The beam intensity amounted to 3000 ions/s on average. The highly efficient MINIBALL setup was employed, consisting of eight HPGe cluster detectors for gamma-ray detection and a segmented Si-detector for coincident particle detection. The level scheme of 31Mg was extended. Spin and parity assignment of the observed 945 keV state yielded 5/2+ and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32Mg establishes that f...

  5. Shear viscosity of neutron-rich nucleonic matter near its liquid–gas phase transition

    International Nuclear Information System (INIS)

    Xu, Jun; Chen, Lie-Wen; Ko, Che Ming; Li, Bao-An; Ma, Yu Gang

    2013-01-01

    Within a relaxation time approach using free nucleon–nucleon cross sections modified by the in-medium nucleon masses that are determined from an isospin- and momentum-dependent effective nucleon–nucleon interaction, we investigate the specific shear viscosity (η/s) of neutron-rich nucleonic matter near its liquid–gas phase transition. It is found that as the nucleonic matter is heated at fixed pressure or compressed at fixed temperature, its specific shear viscosity shows a valley shape in the temperature or density dependence, with the minimum located at the boundary of the phase transition. Moreover, the value of η/s drops suddenly at the first-order liquid–gas phase transition temperature, reaching as low as 4–5 times the KSS bound of ℏ/4π. However, it varies smoothly for the second-order liquid–gas phase transition. Effects of the isospin degree of freedom and the nuclear symmetry energy on the value of η/s are also discussed

  6. Nuclear structure studies of the neutron-rich Rubidium isotopes using Coulomb excitation

    CERN Multimedia

    Reiter, P; Blazhev, A A; Voulot, D; Meot, V H; Simpson, G S; Georgiev, G P; Gaudefroy, L; Roig, O

    We propose to study the properties of odd-mass neutron-rich rubidium isotopes by the Coulomb-excitation technique, using the Miniball array coupled to the REX-ISOLDE facility. The results from similar measurements from the recent years (e.g. for the odd-mass and the odd-odd Cu isotopes, IS435) have shown the strong potential in such measurements for gaining information both for single-particle-like and collective states in exotic nuclei. Since there is practically no experimental information for excited states in the odd-mass Rb isotopes beyond $^{93}$Rb, the present study should be able to provide new data in a region of spherical ($^{93}$Rb and $^{95}$Rb) as well as well-deformed nuclei ($^{97}$Rb and $^{99}$Rb). Of particular interest is the rapid shape change that occurs when going from $^{95}$Rb (${\\varepsilon}_{2}$=0.06) to $^{97}$Rb (${\\varepsilon}_{2}$=0.3). These results should be of significant astrophysical interest as well, due to the close proximity of the r-process path.

  7. Isomers in neutron-rich A ∼ 190 nuclides from 208Pb fragmentation

    International Nuclear Information System (INIS)

    Rykaczewski, Krzysztof Piotr; Caamano, M.; Banu, A.; Walker, P.M.; Morton, N.H.; Regan, P. H.; Regan, Patrick H; Pfutzner, M.; Podolyak, Zs.; Gerl, J.; Hellstrom, M.; Mayet, P.; Miernik, K.; Mineva, M.N.; Aprahamian, A.; Benlliure, J.; Bruce, A.M.; Butler, P.A.; Cortina Gil, D.; Cullen, D.M.; Doring, J.; Enqvist, T.; Fox, C.; Garces Narro, J.; Geissel, H.; Gelletly, W.; Giovinazzo, J.; Gorska, M.; Grawe, H.; Grzywacz, R.; Kleinbohl, A.; Korten, W.; Lewitowicz, M.; Lucas, R.; Mach, H.; O'Leary, C.D.; De Oliveira, F.; Pearson, C.J.; Rejmund, F.

    2004-01-01

    Relativistic projectile fragmentation of 208 Pb has been used to produce isomers in neutron-rich, A ∼ 190 nuclides. A forward-focusing spectrometer provided ion-by-ion mass and charge identification. The detection of gamma-rays emitted by stopped ions has led to the assignment of isomers in 188 Ta, 190 W, 192 Re, 193 Re, 195 Os, 197 Ir, 198 Ir, 200 Pt, 201 Pt, 202 Pt and 203 Au, with half-lives ranging from approximately 10 ns to 1 ms. Tentative isomer information has been found also for 174 Er, 175 Er, 185 Hf, 191 Re, 194 Re and 199 Ir. In most cases, time-correlated, singles gamma-ray events provided the first spectroscopic data on excited states for each nuclide. In 200 Pt and 201 Pt, the assignments are supported by gamma-gamma coincidences. Isomeric ratios provide additional information, such as half-life and transition energy constraints in particular cases. The level structures of the platinum isotopes are discussed, and comparisons are made with isomer systematics

  8. Decay spectroscopy of neutron-rich nuclei around {sup 37,38}Al

    Energy Technology Data Exchange (ETDEWEB)

    Steiger, Konrad [Physik-Department E12, Technische Universitaet Muenchen (Germany); Collaboration: CAITEN-Collaboration

    2013-07-01

    An experiment at RIBF (Radioactive Isotope Beam Factory at RIKEN, Japan) investigated N=20 nuclei above {sup 29}F and the midshell region around {sup 37}Al. These nuclei were produced by relativistic projectile fragmentation of a 345 AMeV {sup 48}Ca primary beam from the superconducting ring cyclotron SRC with an average intensity of 70 pnA. The secondary cocktail beam was separated and identified with the BigRIPS fragment separator and the ZeroDegree spectrometer. The identified fragments were implanted in the CAITEN detector (Cylindrical Active Implantation Target for Efficient Nuclear-decay study). The main part of this detector is a highly segmented plastic scintillator with the shape of a hollow cylinder. To reduce background decay events the scintillator was moved axially and vertically similar to a tape-transport system. Implantations and decays were correlated in time and space. For the first time β-delayed γ-rays were measured in the neutron-rich isotopes {sup 37,38}Si (with three germanium clover detectors). From β-γ-γ coincidences partial level schemes could be constructed. The results were compared to shell model calculations and a tentative assignment for spins and parities of the experimental level schemes was possible. Significantly more precise half-lives for the implanted nuclei were measured.

  9. Evolution of deformation in neutron-rich Ba isotopes up to A =150

    Science.gov (United States)

    Licǎ, R.; Benzoni, G.; Rodríguez, T. R.; Borge, M. J. G.; Fraile, L. M.; Mach, H.; Morales, A. I.; Madurga, M.; Sotty, C. O.; Vedia, V.; De Witte, H.; Benito, J.; Bernard, R. N.; Berry, T.; Bracco, A.; Camera, F.; Ceruti, S.; Charviakova, V.; Cieplicka-Oryńczak, N.; Costache, C.; Crespi, F. C. L.; Creswell, J.; Fernandez-Martínez, G.; Fynbo, H.; Greenlees, P. T.; Homm, I.; Huyse, M.; Jolie, J.; Karayonchev, V.; Köster, U.; Konki, J.; Kröll, T.; Kurcewicz, J.; Kurtukian-Nieto, T.; Lazarus, I.; Lund, M. V.; Mǎrginean, N.; Mǎrginean, R.; Mihai, C.; Mihai, R. E.; Negret, A.; Orduz, A.; Patyk, Z.; Pascu, S.; Pucknell, V.; Rahkila, P.; Rapisarda, E.; Regis, J. M.; Robledo, L. M.; Rotaru, F.; Saed-Samii, N.; Sánchez-Tembleque, V.; Stanoiu, M.; Tengblad, O.; Thuerauf, M.; Turturica, A.; Van Duppen, P.; Warr, N.; IDS Collaboration

    2018-02-01

    The occurrence of octupolar shapes in the Ba isotopic chain was recently established experimentally up to N =90 . To further extend the systematics, the evolution of shapes in the most neutron-rich members of the Z =56 isotopic chain accessible at present, Ba,150148, has been studied via β decay at the ISOLDE Decay Station. This paper reports on the first measurement of the positive- and negative-parity low-spin excited states of 150Ba and presents an extension of the β -decay scheme of 148Cs. Employing the fast timing technique, half-lives for the 21+ level in both nuclei have been determined, resulting in T1 /2=1.51 (1 ) ns for 148Ba and T1 /2=3.4 (2 ) ns for 150Ba. The systematics of low-spin states, together with the experimental determination of the B (E 2 :2+→0+) transition probabilities, indicate an increasing collectivity in Ba-150148, towards prolate deformed shapes. The experimental data are compared to symmetry conserving configuration mixing (SCCM) calculations, confirming an evolution of increasingly quadrupole deformed shapes with a definite octupolar character.

  10. New mass analysis and results for neutron rich nuclei performed with isochronous mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Diwisch, Marcel [Justus-Liebig-Universitaet Giessen, Giessen (Germany); Knoebel, Ronja; Geissel, Hans; Plass, Wolfgang; Scheidenberger, Christoph [Justus-Liebig-Universitaet Giessen, Giessen (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Patyk, Zygmunt [Soltan Institute for Nuclear Studies, Warsaw (Poland); Weick, Helmut [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany)

    2015-07-01

    The Isochronous Mass Spectrometry (IMS) allows to measure masses of rare exotic nuclei in a storage ring in a timescale of tens of μs. The ring is operated in an isochronous mode, i.e. such that particles with different velocities but same mass-to-charge ratio (m/q) travel different paths in the ring arcs (faster ions travel longer paths whereas slower ions travel shorter paths). This means that for each m/q a fix revolution time exists and can be measured by a time-of-flight (TOF) detector which then yields the masses of the nuclei for known charge states. A new analysis approach of IMS data with a correlation matrix method allowed combining data with different quality. The latest production run was using an additional determination of the magnetic rigidity which increased the resolving power of the experiment. Combining this experiment with previous experiments one can increase the statistics and accuracy of the overall mass determination. It was possible to deduce mass values of neutron rich isotopes which have not been measured before. One of those isotopes is {sup 130}Cd which is a very important nuclei involved in the r-process. Those mass values and a comparison to theoretical predictions will be presented in the poster.

  11. New experimental investigation of cluster structures in 10 Be and 16 C neutron-rich nuclei

    Science.gov (United States)

    Dell'Aquila, L.; Acosta, D.; Auditore, L.; Cardella, G.; De Filippo, E.; De Luca, S.; Francalanza, L.; Gnoffo, B.; Lanzalone, G.; Lombardo, I.; Martorana, N. S.; Norella, S.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Quattrocchi, L.; Rizzo, F.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

    2017-11-01

    The existence of cluster structures in ^{10} Be and ^{16} C neutron-rich isotopes is investigated via projectile break-up reactions induced on polyethylene (CH _2 target. We used a fragmentation beam constituted by 55MeV/u ^{10} Be and 49MeV/u ^{16} C beams provided by the FRIBs facility at INFN-LNS. Invariant mass spectra of 4{He}+ 6 He and 6{He} + ^{10} Be breakup fragments are reconstructed by means of the CHIMERA 4π detector to investigate the presence of excited states of projectile nuclei characterized by cluster structure. In the first case, we suggest the presence of a new state in ^{10} Be at 13.5MeV. A non-vanishing yield corresponding to 20.6MeV excitation energy of ^{16} C was observed in the 6{He} + ^{10} Be cluster decay channel. To improve the results of the present analysis, a new experiment has been performed recently, taking advantage of the coupling of CHIMERA and FARCOS. In the paper we describe the data reduction process of the new experiment together with preliminary results.

  12. Exploratory analysis of a neutron-rich nuclei source based on photo-fission

    CERN Document Server

    Mirea, M; Clapier, F; Essabaa, S; Groza, L; Ibrahim, F; Kandri-Rody, S; Müller, A C; Pauwels, N; Proust, J

    2003-01-01

    A source of neutron rich ions can be conceived through the photo-fission process. An exploratory study of such a source is realized. A survey of the radiative electron energy loss theory is reported in order to estimate numerically the bremsstrahlung production of thick targets. The resulted bremsstrahlung angular and energy theoretical distributions delivered from W and UCx thick converters are presented and compared with previous results. Some quantities as the number of fission events produced in the fissionable source and the energy loss in the converters are also reported as function of the geometry of the combination and the incident electron energy. An attempt of comparison with experimental data shows a quantitative agreement. This study is focussed on initial kinetic energies of the electron beam included in the range 30-60 MeV, suitable for the production of large radiative gamma-ray yields able to induce the $^{238}$U fission through the giant dipole resonance. A confrontation with the number of fi...

  13. Isomer-delayed gamma-ray spectroscopy of neutron-rich 166Tb

    Directory of Open Access Journals (Sweden)

    Gurgi L.A.

    2017-01-01

    Full Text Available This short paper presents the identification of a metastable, isomeric-state decay in the neutron-rich odd-odd, prolate-deformed nucleus 166Tb. The nucleus of interest was formed using the in-flight fission of a 345 MeV per nucleon 238U primary beam at the RIBF facility, RIKEN, Japan. Gamma-ray transitions decaying from the observed isomeric states in 166Tb were identified using the EURICA gamma-ray spectrometer, positioned at the final focus of the BigRIPS fragments separator. The current work identifies a single discrete gamma-ray transition of energy 119 keV which de-excites an isomeric state in 166Tb with a measured half-life of 3.5(4 μs. The multipolarity assignment for this transition is an electric dipole and is made on the basis internal conversion and decay lifetime arguments. Possible two quasi-particle Nilsson configurations for the initial and final states which are linked by this transition in 166Tb are made on the basis of comparison with Blocked BCS Nilsson calculations, with the predicted ground state configuration for this nucleus arising from the coupling of the v(1-/2[521] and π(3+/2 Nilsson orbitals.

  14. Shape coexistence in neutron-rich Sr isotopes : Coulomb excitation of $^{96}$Sr

    CERN Multimedia

    Clement, E; Siem, S; Czosnyka, T

    2007-01-01

    The nuclei in the mass region A $\\cong$ 100 around Sr and Zr show a dramatic change of the nuclear ground-state shape from near spherical for N $\\leq$ 58 to strongly deformed for N $\\geq$ 60. Theoretical calculations predict the coexistence of slightly oblate and strongly prolate deformed configurations in the transitional region. However, excited rotational structures based on the highly deformed configuration, which becomes the ground state at N = 60, are not firmly established in the lighter isotopes, and the earlier interpretation of a very abrupt change of shape has been challenged by recent experimental results in favor of a rather gradual change. We propose to study the electromagnetic properties of the neutron-rich nucleus $_{38}^{96}$Sr$_{58}$ by low-energy Coulomb excitation using the REX-ISOLDE facility and the MINIBALL detector array. Both transitional and diagonal matrix elements will be extracted, resulting in a complete description of the transition strengths and quadrupole moments of the low-l...

  15. Structure of neutron rich nuclei of Germanium and Gallium beyond N equals 50 at Alto

    International Nuclear Information System (INIS)

    Lebois, M.

    2008-09-01

    The gamma rays following the beta decay of the following very neutron-rich isotopes: 82,83,84 Ga produced by photo-fission, have been studied at the newly built ISOL facility in Orsay: ALTO. In ALTO the interaction of an electron beam with U 238 target generates a continuous spectra of Bremsstrahlung gamma radiation that triggers U 238 fission. The fission fragments are then ionized, extracted and mass-separated. The analysis of the data has shown the existence of an isomer in 31 84 Ga 53 and has enabled us to confirm known results on 32 83 Ge 51 energy levels including the gamma transition between the 1/2+ state at 247,7 KeV and the fundamental state. We have also proposed the first energy level scheme for 33 84 As 51 . In order to understand the structure of the nucleus we have used the Thankappan and True model that gives a description of the coupling between the pair-pair core (half-magical) and the single nucleon. This model applied to the N=51 chain ( 38 89 Sr 51 , 36 87 Kr 51 , 34 85 Se 51 , 32 83 Ge 51 and 30 81 Zn 51 ) has allowed us to see the main features of odd isotope structure. We have also confirmed previous results concerning the nature of the states in the following decay 31 83 Ga 52 → 32 83 Ge 51

  16. Evolution of nuclear structure in neutron-rich odd-Zn isotopes and isomers

    Directory of Open Access Journals (Sweden)

    C. Wraith

    2017-08-01

    Full Text Available Collinear laser spectroscopy was performed on Zn (Z=30 isotopes at ISOLDE, CERN. The study of hyperfine spectra of nuclei across the Zn isotopic chain, N=33–49, allowed the measurement of nuclear spins for the ground and isomeric states in odd-A neutron-rich nuclei up to N=50. Exactly one long-lived (>10 ms isomeric state has been established in each 69–79Zn isotope. The nuclear magnetic dipole moments and spectroscopic quadrupole moments are well reproduced by large-scale shell–model calculations in the f5pg9 and fpg9d5 model spaces, thus establishing the dominant term in their wave function. The magnetic moment of the intruder Iπ=1/2+ isomer in 79Zn is reproduced only if the νs1/2 orbital is added to the valence space, as realized in the recently developed PFSDG-U interaction. The spin and moments of the low-lying isomeric state in 73Zn suggest a strong onset of deformation at N=43, while the progression towards 79Zn points to the stability of the Z=28 and N=50 shell gaps, supporting the magicity of 78Ni.

  17. Nuclear-decay studies of neutron-rich rare-earth nuclides

    International Nuclear Information System (INIS)

    Chasteler, R.M.

    1990-01-01

    Neutron-rich rare-earth nuclei were produced in multinucleon transfer reactions of 170 Er and 176 Yb projectiles on nat W targets at the Lawrence Berkeley Laboratory SuperHILAC and their radioactive decays properties studied at the on-line mass separation facility OASIS. Two unknown isotopes, 169 Dy (t 1/2 = 39 ± 8 s) and 174 Er(t 1/2 = 3.3 ± 0.2 m) were discovered and their decay characteristics determined. The decay schemes for two previously identified isotopes, 168 Dy (t 1/2 = 8.8 ± 0.3 m) and 171 Ho (t 1/2 = 55 ± 3 s), were characterized. Evidence for a new isomer of 3.0 m 168 Ho g , 168 Ho m (t 1/2 = 132 ± 4 s) which decays by isomeric transition (IT) is presented. Beta particle endpoint energies were determined for the decay of 168 Ho g , 169 Dy, 171 Ho, and 174 Er, the resulting Qβ-values are: 2.93 ± 0.03, 3.2 ± 0.3, 3.2 ± 0.6, and 1.8 ± 0.2 MeV, respectively. These values were compared with values calculated using recent atomic mass formulae. Comparisons of various target/ion source geometries used in the OASIS mass separator facility for these multinucleon transfer reactions were performed. 73 refs., 40 figs., 11 tabs

  18. β-decay spectroscopy of neutron-rich 160,161,162Sm isotopes

    Directory of Open Access Journals (Sweden)

    Patel Z.

    2016-01-01

    Full Text Available Neutron-rich 160,161,162Sm isotopes have been populated at the RIBF, RIKEN via β first time. β-coincident γ rays were observed in all three isotopes including γ rays from the isomeric decay of 160Sm and 162Sm. The isomers in 160Sm and 162Sm have previously been observed but have been populated via β decay for the first time. The isomeric state in 162Sm is assigned a 4−v72+[ 633 ]⊗v12−[ 521 ]${4^ - }v{{7 \\over 2}^ + }\\left[ {633} \\right] \\otimes v{{1 \\over 2}^ - }\\left[ {521} \\right]$ configuration based on the decay pattern. The level schemes of 160Sm and 162Sm are presented. The ground states in the parent nuclei 160Pm and 162Pm are both assigned a 6−v72+[633]⊗π52−[532]${6^ - }v{{7 \\over 2}^ + }\\left[ {633} \\right] \\otimes \\pi {{5 \\over 2}^ - }\\left[ {532} \\right]$ configuration based on the population of states in the daughter nuclei. Blocked BCS calculations were performed to further investigate the spin-parities of the ground states in 160Pm, 161Pm, and 162Pm, and the isomeric state in 162Sm

  19. Investigation of reduced transition-strengths in neutron-rich chromium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Braunroth, Thomas; Dewald, Alfred; Fransen, Christoph; Litzinger, Julia [Institut fuer Kernphysik, Universitaet Koeln (Germany); Iwasaki, Hironori [National Superconducting Cyclotron Laboratory, MSU (United States); Lemasson, Antoine [GANIL, Laboratoire Commun DSM/CEA (France); Lenzi, Silvia [Department of Physics and Astronomy, University of Padova (Italy); INFN, Sezione di Padova (Italy)

    2015-07-01

    Neutron-rich nuclei close to N=40 are known for their rapid changes in nuclear structure. While {sup 68}Ni exhibits signatures of a shell closure, experimental data - e.g. excitation energies of the 2{sup +}{sub 1}-state and B(E2;2{sup +}{sub 1} → 0{sup +}{sub 1})-values - along the isotopic chains in even more exotic Fe and Cr-isotopes suggest a sudden rise in collective behaviour for N → 40. Lifetimes of low-lying yrast states in {sup 58,60,62}Cr were measured with the Recoil Distance Doppler-shift (RDDS) technique at NSCL, MSU (USA) to deduce model independent B(E2)-values. After fragmentation of a primary {sup 82}Se beam (E=140 AMeV) on a {sup 9}Be target and subsequent filtering with the A1900 fragment separator, high purity {sup 59,61,63}Mn-beams (E ∝ 95 AMeV) impinged on the {sup 9}Be plunger target, where excited states in the above mentioned Cr-isotopes were then populated in one proton knockout reactions. The S800 spectrograph allowed a clear recoil identification, which then lead to clean γ-spectra as measured by the Segmented Germanium Array (SeGA). Final results of this experiment will be shown and discussed in the context of state-of-the-art shell-model calculations.

  20. Coulomb excitation of neutron-rich odd-$A$ Cd isotopes

    CERN Multimedia

    Reiter, P; Kruecken, R; Gernhaeuser, R A; Kroell, T; Leske, J; Marginean, N M

    We propose to study excited states in the odd-${A}$ isotopes $^{123,125,127}$Cd by ${\\gamma}$-ray spectroscopy following "safe" Coulomb excitation. The experiment aims to determine the B(E2) values connecting excited states with the ground state as well as the long-lived (11/2$^{-}$) isomer. The proposed study profits from the unique capability of ISOLDE to produce beams containing Cd in the ground state or in the isomeric state. Our recent results on the neutron-rich even-A Cd nuclei appear to show that these nuclei may possess some collectivity beyond that calculated by modern shell-model predictions. Beyond-mean-field calculations also predict these nuclei to be weakly deformed. These facets are surprising considering their proximity to the doubly magic $^{132}$Sn. Coulomb-excitation studies of odd-${A}$ Cd isotopes may give a unique insight into the deformation-driving roles played by different orbits in this region. Such studies of the onset of collectivity become especially important in light of recent...

  1. Study of neutron rich nuclei by delayed neutron decay using the Tonnerre multidetector; Etude de la decroissance par neutrons retardes de noyaux legers riches en neutrons avec le multidetecteur tonnerre

    Energy Technology Data Exchange (ETDEWEB)

    Timis, C.N

    2001-07-01

    A new detection array for beta delayed neutrons was built. It includes up to 32 plastic scintillation counters 180 cm long located at 120 cm from the target. Neutron energy spectra are measured by time-of-flight in the 300 keV-15 MeV range with good energy resolution. The device was tested with several known nuclei. Its performances are discussed in comparison with Monte Carlo simulations. They very high overall detection efficiency on the TONNERRE array made it possible to study one and two neutron emission of {sup 11}Li. A complete decay scheme was obtained. The {sup 33}Mg and {sup 35}Al beta decays were investigated for the first time by neutron and gamma spectroscopy. Complete decay schemes were established and compared to large scale shell-model calculations. (authors)

  2. Production of neutron-rich nuclides in the vicinity of N = 126 shell closure in multinucleon transfer reactions

    Directory of Open Access Journals (Sweden)

    Karpov Alexander

    2017-01-01

    Full Text Available Multinucleon transfer in low-energy nucleus-nucleus collisions is widely discussed as a method of production of yet-unknown neutron-rich nuclei hardly accessible (or inaccessible by other methods. Modeling of complicated dynamics of nuclear reactions induced by heavy ions is done within a multidimensional dynamical model of nucleus-nucleus collisions based on the Langevin equations. The model gives a continuous description of the system evolution starting from the well-separated target and projectile in the entrance channel of the reaction up to the formation of final reaction products. In this paper, rather recent sets of experimental data for the 136Xe+198Pt,208Pb reactions are analyzed together with the production cross sections for neutron-rich nuclei in the vicinity of the N = 126 magic shell.

  3. Effects of momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei

    International Nuclear Information System (INIS)

    Li Baoan; Das, Champak B.; Das Gupta, Subal; Gale, Charles

    2004-01-01

    Using an isospin- and momentum-dependent transport model we study effects of the momentum-dependent symmetry potential on heavy-ion collisions induced by neutron-rich nuclei. It is found that symmetry potentials with and without the momentum-dependence but corresponding to the same density-dependent symmetry energy E sym (ρ) lead to significantly different predictions on several E sym (ρ)-sensitive experimental observables especially for energetic nucleons. The momentum- and density-dependence of the symmetry potential have to be determined simultaneously in order to extract the E sym (ρ) accurately. The isospin asymmetry of midrapidity nucleons at high transverse momenta is particularly sensitive to the momentum-dependence of the symmetry potential. It is thus very useful for investigating accurately the equation of state of dense neutron-rich matter

  4. Pairing in exotic neutron-rich nuclei near the drip line and in the crust of neutron stars

    Science.gov (United States)

    Pastore, A.; Margueron, J.; Schuck, P.; Viñas, X.

    2013-09-01

    Exotic and drip-line nuclei as well as nuclei immersed in a low-density gas of neutrons in the inner crust of neutron stars are systematically investigated with respect to their neutron pairing properties. This is done using Skyrme density-functional and different pairing forces such as a density-dependent contact interaction and a separable form of a finite-range Gogny interaction. Hartree-Fock-Bogoliubov (HFB) and Bardeen-Cooper-Schrieffer (BCS) theories are compared. It is found that neutron pairing is reduced towards the drip line while overcast by strong shell effects. Furthermore, resonances in the continuum can have an important effect counterbalancing the tendency of reduction and leading to a persistence of pairing at the drip line. It is also shown that in these systems the difference between HFB and BCS approaches can be quantitatively large.

  5. Recent Progress in Constraining the Equation of State of Dense Neutron-Rich Nuclear Matter with Heavy-Ion Reactions

    International Nuclear Information System (INIS)

    Li Baoan; Chen Liewen; Wen Dehua; Xiao Zhigang; Xu Chang; Yong Gaochan; Zhang Ming

    2010-01-01

    The nuclear symmetry energy E sym (ρ) is the most uncertain part of the Equation of State (EOS) of dense neutron-rich nuclear matter. In this talk, we discuss the underlying physics responsible for the uncertain E sym (ρ) especially at supra-saturation densities, the circumstantial evidence for a super-soft E sym (ρ) from analyzing π - /π + ratio in relativistic heavy-ion collisions and its impacts on astrophysics and cosmology.

  6. Study of Neutron-Rich $^{124,126,128}$Cd Isotopes; Excursion from Symmetries to Shell-Model Picture

    CERN Multimedia

    Nieminen, A M; Reponen, M

    2002-01-01

    A short outline is given on a number of topics that are present in the long series of even-even Cd nuclei and therefore, may turn out to constitute an ideal test bench in order to verify a number of theoretical ideas on how collective motion, near closed shells, builds up taking into account both the valence and core nucleons when studying the nucleon correlations. Moreover, these experiments can reveal new challenges when moving towards very neutron-rich systems.

  7. In-beam γ-ray spectroscopy of the neutron rich 39Si

    International Nuclear Information System (INIS)

    Sohler, D.; Dombradi, Zs.; Achouri, N.L.; Angelique, J.C.; Bastin, B.; Azaiez, F.; Baiborodin, D.; Borcea, R.

    2009-01-01

    Complete text of publication follows. In order to clarify the role of proton excitations across the Z = 14 subshell closure in neutron-rich Si isotopes, we investigated the structure of the 14 39 Si 25 isotope, having three neutron-hole configurations with respect to an N = 28 core. The excited states of 39 Si were studied by in-beam γ-ray spectroscopy trough fragmentation of radioactive beams. The experiment was performed at the GANIL facility in France. The radioactive beams were produced by the fragmentation of the stable 48 Ca beam of 60 MeV/u energy and 4μA intensity on a 12 C target in the SISSI device. The cocktail beam produced was impinged onto a 9 Be target. The nuclei produced in the secondary fragmentation reaction were selected and unambiguously identified by the SPEG spectrometer. In the performed experiment the 39 Si nuclei were obtained via 1p, 1p1n, 2p1n and 2p2n knockout reactions from the 40,41 P and 42,43 S secondary beams. To measure the γ rays emitted from the excited states, the secondary target was surrounded by the 4π 'Chateau de Crystal' array consisting of 74 BaF 2 scintillators. The γ-ray spectra were generated by gating event-by-event on the incoming secondary beam particles and the ejectiles after the secondary target. For the γ rays emitted by the fast moving fragments accurate Doppler correction was performed. From the obtained γ spectra of 39 Si displayed in Figure 1, two strong γ transitions at 163 and 397 keV as well as weaker ones at 303, 657, 906, 1143 and 1551 keV have been identified. γγ coincidences were obtained in 39 Si after having added all data from the various reaction channels giving rise to 39 Si. Analysing these data the 163 keV transition was found to be in coincidence with the 657, 1143 and 1551 keV ones, but not with the 397 keV transition. The two lines of the 303+397 keV doublet are in mutual coincidence, and one or both of them are found in coincidence with the 906 keV transition.

  8. Mass measurement and structure studies of neutron-rich isotopes of Zn, Ni, Fe

    International Nuclear Information System (INIS)

    Dessagne, P.

    1982-01-01

    With the Orsay MP Tandem, the reaction ( 14 C, 16 O) on 58 - 60 - 62 - 64 Ni, 64 - 66 - 68 - 70 Zn, 74 - 76 Ge and 82 Se targets, and the reaction ( 14 C, 15 O) on 60 - 62 - 64 Ni, 68 - 70 Zn, 76 Ge targets, have been investigated at 72 MeV bombarding energy. The mass excess of neutron rich nuclei: 63 Fe (-55.19+-.06MeV), 69 Ni(-60.14+-.06 MeV), 75 Zn(.62.7+-08 MeV) have been measured for the first time, and those of 62 Fe, 68 Ni, 74 Zn, 80 Ge have been remeasured. A new equipment has been designed in order to perform measurements at zero degree. From the angular distribution around 0 0 for the 70 Zn( 14 C, 16 O) reaction, the first state of 68 Ni observed for the first time (1.77 MeV +- .04 MeV) has been shown to be a 0 + . This result establishes a new case of 2 1+ - 0 2+ inversion. The systematics of the ( 14 C, 16 O) measurements on the even Ni and Zn isotopes have shown a different behaviour with two series. For the Ni → Fe (g.s.) transitions, the ratio σsub(exp)/σsub(DWBA) increases by a factor of four when the neutron number varies from 30 to 36. Whereas for the Zn → Ni (gs) transitions this ratio remains constant for the first three isotopes and decrease by a factor of two when N=40. For the Ni → Fe transitions, axial and spherical symmetries have been used. In agreement with the shell model no change are found with the spherical symmetry. For the axial symmetry a variation is observed but strongly dapendant of the sub-shell. Hence no clear conclusion can be deduced for the cross section estimate. For the Zn → Ni transitions, the spherical symmetry has been used. One configuration prevails, leading to a qualitative agreement with the experimental results [fr

  9. Study of Ground State Wave-function of the Neutron-rich 29,30Na Isotopes through Coulomb Breakup

    Directory of Open Access Journals (Sweden)

    Rahaman A.

    2014-03-01

    Full Text Available Coulomb breakup of unstable neutron rich nuclei 29,30Na around the ‘island of inversion’ has been studied at energy around 434 MeV/nucleon and 409 MeV/nucleon respectively. Four momentum vectors of fragments, decay neutron from excited projectile and γ-rays emitted from excited fragments after Coulomb breakup are measured in coincidence. For these nuclei, the low-lying dipole strength above one neutron threshold can be explained by direct breakup model. The analysis for Coulomb breakup of 29,30Na shows that large amount of the cross section yields the 28Na, 29Na core in ground state. The predominant ground-state configuration of 29,30Na is found to be 28Na(g.s⊗νs1/2 and 29Na(g.s⊗νs1/2,respectively.

  10. Dipole resonances in light neutron-rich nuclei studied with time-dependent calculations of antisymmetrized molecular dynamics

    International Nuclear Information System (INIS)

    Kanada-En'yo, Y.; Kimura, M.

    2005-01-01

    To study isovector dipole responses of neutron-rich nuclei, we applied a time-dependent method of antisymmetrized molecular dynamics. The dipole resonances in Be, B, and C isotopes were investigated. In 10 Be, 15 B, and 16 C, collective modes of the vibration between a core and valence neutrons cause soft resonances at the excitation energy E x =10-15 MeV below the giant dipole resonance (GDR). In 16 C, we found that a remarkable peak at E x =14 MeV corresponds to the coherent motion of four valence neutrons against a 12 C core, whereas the GDR arises in the E x >20 MeV region because of vibration within the core. In 17 B and 18 C, the dipole strengths in the low-energy region decline compared with those in 15 B and 16 C. We also discuss the energy-weighted sum rule for the E1 transitions

  11. Synthesis of superheavy elements by cold fusion

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, S [Gesellschaft fuer Schwerionenforschung (GSI), Helmholtzzentrum fuer Schwerionenforschung Gmbh (Germany)

    2009-12-31

    The nuclear shell model predicts that the next doubly magic shell-closure beyond {sup 208}Pb is at the proton number Z=114, 120, or 126 and at the neutron number N=172 or 184. The outstanding aim of experimental investigations is the exploration of this region of spherical 'Super Heavy Elements' (SHEs). Using cold fusion reactions which are based on lead and bismuth targets, the new elements from 107 to 112 were synthesized at GSI in Darmstadt, Germany. Some of these results were confirmed at RIKEN in Wako, Japan, where also a relatively neutron-deficient isotope of element 113 was synthesized. In hot fusion reactions of {sup 48}Ca projectiles with actinide targets, a more neutron-rich isotope of element 112 and the new elements from 113 to 116 and even 118 were produced at FLNR in Dubna, Russia. Recently, part of these hot fusion data, which represent the first identification of nuclei located on the predicted island of SHEs, were confirmed in two independent experiments. The decay data reveal that for the heaviest elements, the dominant decay mode is alpha emission rather than fission. The decay properties as well as reaction cross-sections are compared with results of theoretical studies.

  12. Investigation of neutron-rich rare-earth nuclei including the new isotopes 177Tm and 184Lu

    International Nuclear Information System (INIS)

    Rykaczewski, K.; Gippert, K.L.; Runte, E.; Schmidt-Ott, W.D.; Tidemand-Petersson, P.; Kurcewicz, W.; Nazarewicz, W.

    1989-01-01

    Decays of neutron-rich isotopes in the rare-earth region were studied by means of on-line mass separation and β-γ spectroscopy using multinucleon-transfer reactions between beams of 136 Xe (9 and 11.7 MeV/u), 186 W (11.7 and 15 MeV/u) and 238 U (11.4 MeV/u) and targets of nat W and Ta. The higher beam energies appear to be advantageous for the production of such isotopes. Two new isotopes were identified: 177 Tm with a half-life T 1/2 = 85±10/15 s, and 184 Lu with T 1/2 ≅ 18 s. A new 47 s-activity found at A = 171 is tentatively assigned to the decay of the new isotope 171 Ho. The properties of the ground and excited states of neutron-rich lanthanide isotopes are interpreted within the shell model using the deformed Woods-Saxon potential. A change of the ground-state configuration for odd-mass neutron-rich lutetium isotopes from π 7/2 + [404] to π 9/2 - [514] is suggested, this change being due to the influence of a large hexadecapole deformation. The role of a possible isometric state in 180 Lu for the nucleosynthesis of 180m Ta is discussed. (orig.)

  13. Nuclear structure studies of neutron-rich heavy nuclei by mass measurements of francium and radium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Rosenbusch, Marco [Ernst-Moritz-Arndt-Universitaet, Institut fuer Physik, 17487 Greifswald (Germany); Collaboration: ISOLTRAP-Collaboration

    2013-07-01

    The mass is a unique property of an atomic nucleus reflecting its binding energy and thus the sum of all interactions at work. Precise measurements of nuclear masses especially of short-lived exotic nuclides provide important input for nuclear structure, nuclear astrophysics, tests of the Standard Model, and weak interaction studies. The Penning-trap mass spectrometer ISOLTRAP at the on-line isotope separator ISOLDE/CERN has been set up for precision mass measurements and continuously improved for accessing more exotic nuclides. The mass uncertainty is typically δm / m=10{sup -8} and the accessible half-life has been reduced to about 50 ms. In this contribution, the results of a measurement campaign of neutron-rich francium and radium isotopes will be presented, i.e. the masses of the isotopic chain of {sup 224-233}Fr and {sup 233,234}Ra, one of the most neutron-rich ensemble obtainable at ISOL facilities. The mass {sup 234}Ra denotes the heaviest mass ever measured with ISOLTRAP. Experimental data in the neutron-rich, heavy mass region is of great interest for studies of structural evolution far from stability, especially because the knowledge from nuclear mass models is scarce. The impact of the new data on the physics in this mass region as well as recent technical developments of ISOLTRAP are discussed.

  14. K isomerism and collectivity in neutron-rich rare-earth isotopes

    Science.gov (United States)

    Patel, Zena

    Neutron-rich rare-earth isotopes were produced by in-flight fission of 238U ions at the Radioactive Isotope Beam Factory (RIBF), RIKEN, Japan. In-flight fission of a heavy, high-intensity beam of 238U ions on a light target provides the cleanest secondary beams of neutron-rich nuclei in the rare-earth region of isotopes. In-flight fission is advantageous over other methods of nuclear production, as it allows for a secondary beam to be extracted, from which the beam species can be separated and identified. The excited states of nuclei are studied by delayed isomeric or beta-delayed gamma-ray spectroscopy. New K isomers were found in Sm (Z=62), Eu (Z=63), and Gd (Z=64) isotopes. The key results are discussed here. Excited states in the N=102 isotones 166Gd and 164Sm have been observed following isomeric decay for the first time. The K-isomeric states in 166Gd and 164Sm are due to 2-quasiparticle configurations. Based on the decay patterns and potential energy surface calculations, including beta6 deformation, both isomers are assigned a (6-) spin-parity. The half-lives of the isomeric states have been measured to be 950(60)ns and 600(140)ns for 166Gd and 164Sm respectively. Collective observables are discussed in light of the systematics of the region, giving insight into nuclear shape evolution. The decrease in the ground state band energies of 166Gd and 164Sm (N=102) compared to 164Gd and 162Sm (N=100) respectively, presents evidence for the predicted deformed shell closure at N=100. A 4-quasiparticle isomeric state has been discovered in 160Sm: the lightest deformed nucleus with a 4-quasiparticle isomer to date. The isomeric state is assigned an (11+) spin-parity with a measured half-life of 1.8(4)us. The (11+) isomeric state decays into a rotational band structure, based on a (6-) v5/2-[523] ⊗ v7/2+[633] bandhead, determined from the extracted gK-gR values. Potential energy surface and blocked BCS calculations were performed in the deformed midshell region

  15. Lifetimes in neutron-rich Nd isotopes measured by Doppler profile method

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Lister, C.J.; Morss, L.R. [and others

    1995-08-01

    Lifetimes of the rotational levels in neutron-rich even-even Nd isotopes were deduced from the analysis of the Doppler broadened line shapes. The experiment was performed at Daresbury with the Eurogam array, which at that time consisted of 45 Compton-suppressed Ge detectors and 5 Low-Energy Photon Spectrometers. The source was in the form of a 7-mm pellet which was prepared by mixing 5-mg; {sup 248}Cm and 65-mg KCl and pressing it under high pressure. Events for which three or more detectors fired were used to construct a cubic data array whose axes represented the {gamma}-ray energies and the contents of each channel the number of events with that particular combination of {gamma}-ray energies. From this cubic array, one-dimensional spectra were generated by placing gates on peaks on the other two axes. Gamma-ray spectra of even-even Nd isotopes were obtained by gating on the transitions in the complimentary Kr fragments. The gamma peaks de-exciting states with I {>=} 12 h were found to be broader than the instrumental line width due to the Doppler effect. The line shapes of they-ray peaks were fitted separately with a simple model for the feeding of the states and assuming a rotational band with constant intrinsic quadruple moment and these are shown in Fig. I-27. The quadrupole moments thus determined were found to be in good agreement with the quadrupole moments measured previously for lower spin states. Because of the success of this technique for the Nd isotopes, we intend to apply this technique to the new larger data set collected with the Eurogam II array. The results of this study were published.

  16. The impact of the tensor interaction on the β-delayed neutron emission of the neutron-rich Ni isotopes

    Directory of Open Access Journals (Sweden)

    Sushenok E.O.

    2018-01-01

    Full Text Available The neutron emission of the β-decay of 74;76;78;80Ni are studied within the quasiparticle random phase approximation with the Skyrme interaction. The coupling between one- and two-phonon terms in the wave functions of the low-energy 1+ states of the daughter nuclei is taken into account. It is shown that the strength decrease of the neutronproton tensor interaction leads to the increase of the half-life and the neutron-emission probability.

  17. Mean-field models and superheavy elements

    International Nuclear Information System (INIS)

    Reinhard, P.G.; Bender, M.; Maruhn, J.A.; Frankfurt Univ.

    2001-03-01

    We discuss the performance of two widely used nuclear mean-field models, the relativistic mean-field theory (RMF) and the non-relativistic Skyrme-Hartree-Fock approach (SHF), with particular emphasis on the description of superheavy elements (SHE). We provide a short introduction to the SHF and RMF, the relations between these two approaches and the relations to other nuclear structure models, briefly review the basic properties with respect to normal nuclear observables, and finally present and discuss recent results on the binding properties of SHE computed with a broad selection of SHF and RMF parametrisations. (orig.)

  18. The Superheavy Elements and Anti-Gravity

    Science.gov (United States)

    Anastasovski, Petar K.

    2004-02-01

    The essence of any propulsion concept is to overcome gravity. Anti-gravity is a natural means to achieve this. Thus, the technology to pursue anti-gravity, by using superheavy elements, may provide a new propulsion paradigm. The theory of superluminal relativity provides a hypothesis for existence of elements with atomic number up to Z = 145, some of which may possess anti-gravity properties. Analysis results show that curved space-time exists demonstrating both gravitic and anti-gravitic properties not only around nuclei but inside the nuclei as well. Two groups of elements (Z Hawking, in honour of Stephen W. Hawking.

  19. Superheavy Element Synthesis And Nuclear Structure

    International Nuclear Information System (INIS)

    Ackermann, D.; Block, M.; Burkhard, H.-G.; Heinz, S.; Hessberger, F. P.; Khuyagbaatar, J.; Kojouharov, I.; Mann, R.; Maurer, J.; Antalic, S.; Saro, S.; Venhart, M.; Hofmann, S.; Leino, M.; Uusitalo, J.; Nishio, K.; Popeko, A. G.; Yeremin, A. V.

    2009-01-01

    After the successful progress in experiments to synthesize superheavy elements (SHE) throughout the last decades, advanced nuclear structure studies in that region have become feasible in recent years thanks to improved accelerator, separation and detection technology. The means are evaporation residue(ER)-α-α and ER-α-γ coincidence techniques complemented by conversion electron (CE) studies, applied after a separator. Recent examples of interesting physics to be discovered in this region of the chart of nuclides are the studies of K-isomers observed in 252,254 No and in 270 Ds.

  20. Electronic structure and properties of superheavy elements

    International Nuclear Information System (INIS)

    Pershina, V.

    2015-01-01

    Spectacular developments in the relativistic quantum theory and computational algorithms in the last few decades allowed for accurate calculations of properties of the superheavy elements (SHE) and their compounds. Often conducted in a close link to the experimental research, these investigations helped predict and interpret an outcome of sophisticated and expensive experiments with single atoms. Most of the works, particularly those related to the experimental studies, are overviewed in this publication. The role of relativistic effects being of paramount importance for the heaviest elements is elucidated.

  1. Commissioning of the BRIKEN beta-delayed neutron detector for the study of exotic neutron-rich nuclei

    Directory of Open Access Journals (Sweden)

    Tolosa-Delgado A.

    2017-01-01

    Full Text Available The commissioning of a new setup for β-delayed neutron measurements was carried out successfully in November-2016, at the RIKEN Nishina Center in Japan. The β-decay half-lives and Pn branching ratios of several isotopes in the 78Ni region were measured. Details of the experimental setup and the first results are given.

  2. The effect of the scalar-isovector meson field on hyperon-rich neutron star matter

    International Nuclear Information System (INIS)

    Mi, Aijun; Zuo, Wei; Li, Ang

    2008-01-01

    We investigate the effect of the scalar-isovector δ-meson field on the equation of state (EOS) and composition of hyperonic neutron star matter, and the properties of hyperonic neutron stars within the framework of the relativistic mean field theory. The influence of the δ-field turns out to be quite different and generally weaker for hyperonic neutron star matter as compared to that for npeμ neutron star matter. We find that inclusion of the δ-field enhances the strangeness content slightly and consequently moderately softens the EOS of neutron star matter in its hyperonic phase. As for the composition of hyperonic star matter, the effect of the δ-field is shown to shift the onset of the negatively-charged (positively-charged) hyperons to slightly lower (higher) densities and to enhance (reduce) their abundances. The influence of the δ-field on the maximum mass of hyperonic neutron stars is found to be fairly weak, whereas inclusion of the δ-field turns out to enhance sizably both the radii and the moments of inertia of neutron stars with given masses. It is also shown that the effects of the δ-field on the properties of hyperonic neutron stars remain similar in the case of switching off the Σ hyperons. (author)

  3. Fe and N diffusion in nitrogen-rich FeN measured using neutron ...

    Indian Academy of Sciences (India)

    E-mail: mgupta@csr.ernet.in. Abstract. Grazing incidence neutron reflectometry provides an opportunity to measure the depth profile of a thin film sample with a resolution <1 nm, in a non-destructive way. In this way the diffusion across the interfaces can also be measured. In addition, neutrons have contrast among the ...

  4. Alpha decay properties of heavy and superheavy elements

    International Nuclear Information System (INIS)

    Vigila Bai, G.M. Carmel; Umai Parvathiy, J.

    2015-01-01

    Analysing accurately the lifetimes of α-decay chains is an important tool to detect and study the properties of superheavy nuclei. 48 Ca is used in the synthesis of superheavy nuclei Z = 106-118 at Dubna. The experimental work of 48 Ca projectiles at Dubna has given an opportunity to study the superheavy element (SHE). Here, the α-decay properties for Z = 106-118 are evaluated using our CYE model and are compared with the available experimental and theoretical values. (author)

  5. Theoretical description and predictions of the properties of superheavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Sobiczewski, A [Department of Theoretical Physics, Andrzej Soltan Institute for Nuclear Studies (Poland)

    2009-12-31

    Theoretical descriptions of superheavy atomic nuclei are shortly reviewed and illustrated by their results. Such properties of these nuclei as their shapes, masses, fission barriers, decay modes, decay energies, half-lives, are discussed. Special attention is given to the shell structure of the nuclei, due to which they exist. The role of the physical studies of the superheavy nuclei for the chemical research on the superheavy elements and, more generally, the relationship between these two kinds of investigation is underlined. This stresses the importance of close cooperation between physicists and chemists, experimentalists and theoreticians, in these studies.

  6. Universal odd-even staggering in isotopic fragmentation and spallation cross sections of neutron-rich fragments

    Science.gov (United States)

    Mei, B.; Tu, X. L.; Wang, M.

    2018-04-01

    An evident odd-even staggering (OES) in fragment cross sections has been experimentally observed in many fragmentation and spallation reactions. However, quantitative comparisons of this OES effect in different reaction systems are still scarce for neutron-rich nuclei near the neutron drip line. By employing a third-order difference formula, the magnitudes of this OES in extensive experimental cross sections are systematically investigated for many neutron-rich nuclei with (N -Z ) from 1 to 23 over a broad range of atomic numbers (Z ≈3 -50 ). A comparison of these magnitude values extracted from fragment cross sections measured in different fragmentation and spallation reactions with a large variety of projectile-target combinations over a wide energy range reveals that the OES magnitude is almost independent of the projectile-target combinations and the projectile energy. The weighted average of these OES magnitudes derived from cross sections accurately measured in different reaction systems is adopted as the evaluation value of the OES magnitude. These evaluated OES magnitudes are recommended to be used in fragmentation and spallation models to improve their predictions for fragment cross sections.

  7. Decay properties of {sup 256-339}Ds superheavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Santhosh, K.P.; Nithya, C. [Kannur University, School of Pure and Applied Physics, Payyanur, Kerala (India)

    2017-09-15

    The decay properties of 84 isotopes of darmstadtium superheavy nuclei (Z = 110) have been studied using various theoretical models. The proton emission half-lives, the alpha decay half-lives, the spontaneous fission half-lives and the cluster decay half-lives of all the isotopes are evaluated. The one-proton emission half-lives and the alpha decay half-lives are predicted using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The calculated alpha half-lives are compared with the available experimental results as well as with the predictions of other theoretical models. The predicted half-lives matches well with the experimental results. The one-proton half-lives are also compared with the predictions using other formalisms. The shell-effect-dependent formula of Santhosh et al. has been employed for calculating the spontaneous fission half-lives. A theoretical comparison of spontaneous fission half-lives with four different formalisms is performed. By comparing the one-proton emission half-lives, the alpha decay half-lives and the spontaneous fission half-lives decay modes are predicted for all the isotopes of Ds. It is seen that the isotopes within the range 256 ≤ A ≤ 263 and 279 ≤ A ≤ 339 decay through spontaneous fission and the isotopes 264 ≤ A ≤ 278 exhibit alpha decay. Cluster decay half-lives are calculated using different models including the Coulomb and proximity potential (CPPM), for determining the magicities in the superheavy region. The effect of magicity at N = 184 and N = 202 were confirmed from the plot of log{sub 10}T{sub 1/2} versus neutron number of the daughter nuclei for the emission of different clusters. We hope that the systematic and detailed study of all the possible decay modes of {sup 256-339}Ds using various theoretical models will be helpful in the experimental identification of the isotopes of the element in the future. (orig.)

  8. Superheavy element chemistry. Achievements and perspectives

    International Nuclear Information System (INIS)

    Schaedel, M.

    2007-01-01

    Superheavy elements have been synthesized and chemically characterized one-atom-at-a-time up to element 108. Presently, the quest for element 112 is one of the hottest topics in this field. The transactinide elements 104 to 108 are members of group 4 to 8 of the Periodic Table and element 112 belongs into group 12. Chemical properties of some of these elements, like elements 104 and 105, show stunning deviations from simple extrapolations within their respective group while others exhibit great similarities with their lighter homologues elements. First experiments to investigate seaborgium (Sg, element 106) in aqueous solution were performed. Again, in large international collaborations at the GSI, several gas-phase chemistry experiments were performed with hassium (Hs, element 108). Recently, the highly efficient and very clean separation of Hs was applied for nuclear studies of various Hs nuclides investigating their cross section and their nuclear decay properties in the region of the doubly-magic 270 Hs (Z=108, N=162). To overcome certain limitations of the presently used on-line chemical separations the new TransActinide Separation and Chemistry Apparatus (TASCA) - with a gas-filled recoil separator as a front-end tool - was designed and built at the GSI in a collaborative effort. Presently in its commissioning phase, TASCA shall be a key instrument for a big leap into quantitatively and qualitatively new experiments in the region of superheavy elements. (author)

  9. On superheavy elements, what did we achieve

    International Nuclear Information System (INIS)

    Armbruster, P.

    1986-03-01

    The properties of the heaviest isotopes are discussed using recent results on α-energies, halflives, and branchings between the different decay modes. From the data on α- and spontaneous fission halflives and absolute masses, fission barriers and barrier widths are deduced. Shell corrections of the heaviest nuclei are obtained and compared to recent calculations. The concept of superheavy elements is examined, and it is shown that the heaviest isotopes known must be classified 'superheavy'. The production cross sections are summarized and within the extra-push model the reduced fusion probabilities in the entrance channel are discussed. It is shown that besides nuclear structure effects in the collision partners are of importance. It is concluded that targets around 208 Pb give a double gain, on the one hand from the fact that fusion is relatively cold (1n- and 2n-channels), and on the other hand that the extra-push limitation is setting in later than the model predicts. The possibilities to make still heavier elements are restricted not by their groundstate instability but by the principal limitations of their production. (orig.)

  10. Gravitational production of superheavy dark matter

    International Nuclear Information System (INIS)

    Chung, Daniel J. H.; Crotty, Patrick; Kolb, Edward W.; Riotto, Antonio

    2001-01-01

    The dark matter in the universe can be in the form of a superheavy matter species (wimpzilla). Several mechanisms have been proposed for the production of wimpzilla particles during or immediately following the inflationary epoch. Perhaps the most attractive mechanism is through gravitational particle production, where particles are produced simply as a result of the expansion of the universe. In this paper we present a detailed numerical calculation of wimpzilla gravitational production in hybrid-inflation models and natural-inflation models. Generalizing these findings, we also explore the dependence of the gravitational production mechanism on various models of inflation. We show that superheavy dark matter production seems to be robust, with Omega X h 2 ∼(M X /10 11 GeV) 2 (T RH /10 9 GeV), so long as M X I , where M X is the wimpzilla mass, T RH is the reheat temperature, and H I is the expansion rate of the universe during inflation

  11. Study of ground-state configuration of neutron-rich aluminium isotopes through electromagnetic excitation

    International Nuclear Information System (INIS)

    Chakraborty, S.; Datta Pramanik, U.; Chatterjee, S.

    2013-01-01

    The region of the nuclear chart around neutron magic number, N∼20 and proton number (Z), 10≤ Z≤12 is known as the Island of Inversion. The valance neutron(s) of these nuclei, even in their ground state, are most likely occupying the upper pf orbitals which are normally lying above sd orbitals, N∼20 shell closure. Nuclei like 34,35 Al are lying at the boundary of this Island of Inversion. Little experimental information about their ground state configuration are available in literature

  12. Onset of collectivity in neutron-rich Sr and Kr isotopes: Prompt spectroscopy after Coulomb excitation at REX-ISOLDE, CERN

    Directory of Open Access Journals (Sweden)

    Clément E.

    2013-12-01

    Full Text Available A rapid onset of quadrupole deformation is known to occur around the neutron number 60 in the neutron-rich Zr and Sr isotopes. This shape change has made the neutron-rich A = 100 region an active area of experimental and theoretical studies for many decades now. We report in this contribution new experimental results in the neutron rich 96,98Sr investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility, CERN. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross section supporting the scenario of shape coexistence/change at N = 60. Future perspectives are presented including the recent experimental campaign performed at ILL-Grenoble.

  13. ZIRCONIUM—HAFNIUM ISOTOPE EVIDENCE FROM METEORITES FOR THE DECOUPLED SYNTHESIS OF LIGHT AND HEAVY NEUTRON-RICH NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Akram, W.; Schönbächler, M. [School of Earth, Atmospheric and Environmental Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Sprung, P. [Institut für Planetologie, Universität Münster, Wilhelm-Klemm-Strasse 10, D-48149 Münster (Germany); Vogel, N. [Institute for Geochemistry and Petrology, ETH, Clausiusstrasse 25, 8092 Zürich (Switzerland)

    2013-11-10

    Recent work based on analyses of meteorite and terrestrial whole-rock samples showed that the r- and s- process isotopes of Hf were homogeneously distributed throughout the inner solar system. We report new Hf isotope data for Calcium-Aluminum-rich inclusions (CAIs) of the CV3 carbonaceous chondrite Allende, and novel high-precision Zr isotope data for these CAIs and three carbonaceous chondrites (CM, CO, CK). Our Zr data reveal enrichments in the neutron-rich isotope {sup 96}Zr (≤1ε in {sup 96}Zr/{sup 90}Zr) for bulk chondrites and CAIs (∼2ε). Potential isotope effects due to incomplete sample dissolution, galactic and cosmic ray spallation, and the nuclear field shift are assessed and excluded, leading to the conclusion that the {sup 96}Zr isotope variations are of nucleosynthetic origin. The {sup 96}Zr enrichments are coupled with {sup 50}Ti excesses suggesting that both nuclides were produced in the same astrophysical environment. The same CAIs also exhibit deficits in r-process Hf isotopes, which provides strong evidence for a decoupling between the nucleosynthetic processes that produce the light (A ≤ 130) and heavy (A > 130) neutron-rich isotopes. We propose that the light neutron-capture isotopes largely formed in Type II supernovae (SNeII) with higher mass progenitors than the supernovae that produced the heavy r-process isotopes. In the context of our model, the light isotopes (e.g. {sup 96}Zr) are predominantly synthesized via charged-particle reactions in a high entropy wind environment, in which Hf isotopes are not produced. Collectively, our data indicates that CAIs sampled an excess of materials produced in a normal mass (12-25 M{sub ☉}) SNII.

  14. Frontiers of heavy-ion physics and superheavy elements

    International Nuclear Information System (INIS)

    Muenzenberg, G.

    2003-01-01

    This contribution will focus on three topics of GSI nuclear structure research: superheavy elements, direct mass measurements in the storage ring, and studies of fission in reversed kinematics. The GSI project for a new synchrotron facility will be outlined

  15. Microscopic description of quadrupole collectivity in neutron-rich nuclei across the N = 126 shell closure

    Science.gov (United States)

    Rodríguez-Guzmán, R.; Robledo, L. M.; Sharma, M. M.

    2015-06-01

    The quadrupole collectivity in Nd, Sm, Gd, Dy, Er, Yb, Hf and W nuclei with neutron numbers 122 ≤ N ≤ 156 is studied, both at the mean field level and beyond, using the Gogny energy density functional. Besides the robustness of the N = 126 neutron shell closure, it is shown that the onset of static deformations in those isotopic chains with increasing neutron number leads to an enhanced stability and further extends the corresponding two-neutron drip lines far beyond what could be expected from spherical calculations. Independence of the mean-field predictions with respect to the particular version of the Gogny energy density functional employed is demonstrated by comparing results based on the D1S and D1M parameter sets. Correlations beyond mean field are taken into account in the framework of the angular momentum projected generator coordinate method calculation. It is shown that N = 126 remains a robust neutron magic number when dynamical effects are included. The analysis of the collective wave functions, average deformations and excitation energies indicate that, with increasing neutron number, the zero-point quantum corrections lead to dominant prolate configurations in the 0{1/+}, 0{2/+}, 2{1/+} and 2{2/+} states of the studied nuclei. Moreover, those dynamical deformation effects provide an enhanced stability that further supports the mean-field predictions, corroborating a shift of the r-process path to higher neutron numbers. Beyond mean-field calculations provide a smaller shell gap at N = 126 than the mean-field one in good agreement with previous theoretical studies. However, the shell gap still remains strong enough in the two-neutron drip lines.

  16. Nuclear spectroscopy of neutron rich A = 147 nuclides: decay of 147Cs, 147Ba and 147La

    International Nuclear Information System (INIS)

    Shmid, M.; Chu, Y.Y.; Gowdy, G.M.

    1981-01-01

    A study of the beta decay of neutron rich nuclides of the A = 147 chain was carried out at the TRISTAN isotope separator. Half lives of 14 'Cs, 147 Ba and 147 La were measured. Six gamma lines are assigned to 147 Cs decay. A decay scheme for 147 Ba with levels up to 2 MeV is proposed for the first time. A partial decay scheme for 147 La is proposed, which confirms the previously existing one, with five new levels added from the present work

  17. New approach to the nuclear in beam γ spectroscopy of neutron rich nuclei at N=20 using projectile fragmentation

    International Nuclear Information System (INIS)

    Lopez-Jimenez, M.J.; Saint-Laurent, M.G.; Achouri, L.; Daugas, J.M.; Belleguic, M.; Azaiez, F.; Bourgeois, C.; Angelique, J.C.

    1999-01-01

    The structure of nuclei far from stability around 32 Mg have been recently investigated by means of a novel method. In-beam γ-decay spectroscopy of a large number of exotic neutron-rich nuclei produced by projectile fragmentation of a 36 S projectile has been performed, using coincidences between the recoil fragments collected at the focal plane of SPEG spectrometer and γ-rays emitted at the target location. Preliminary results on both the population mechanism and the decay of excited states in nuclei around 32 Mg are presented. (author)

  18. Hyperfine structure and isotope shift of the neutron-rich barium isotopes 139-146Ba and 148Ba

    International Nuclear Information System (INIS)

    Wendt, K.; Ahmad, S.A.; Klempt, W.; Neugart, R.; Otten, E.W.

    1988-01-01

    The hyperfine structure and isotope shift in the 6s 2 S 1/2 -6p 2 P 3/2 line of Ba II (455.4 nm) have been measured by collinear fast-beam laser spectroscopy for the neutron-rich isotopes 139-146 Ba and 148 Ba. Nuclear moments and mean square charge radii of these isotopes have been recalculated. The isotope shift of the isotope 148 Ba (T 1/2 = 0.64 s) could be studied for the first time, yielding δ 2 > 138,148 = 1.245(3) fm 2 . (orig.)

  19. Theoretical study on production of heavy neutron-rich isotopes around the N=126 shell closure in radioactive beam induced transfer reactions

    Directory of Open Access Journals (Sweden)

    Long Zhu

    2017-04-01

    Full Text Available In order to produce more unknown neutron-rich nuclei around N=126, the transfer reactions 136Xe + 198Pt, 136–144Xe + 208Pb, and 132Sn + 208Pb are investigated within the framework of the dinuclear system (DNS model. The influence of neutron excess of projectile on production cross sections of target-like products is studied through the reactions 136,144Xe + 208Pb. We find that the radioactive projectile 144Xe with much larger neutron excess is favorable to produce neutron-rich nuclei with charge number less than the target rather than produce transtarget nuclei. The incident energy dependence of yield distributions of fragments in the reaction 132Sn + 208Pb are also studied. The production cross sections of neutron-rich nuclei with Z=72–77 are predicted in the reactions 136–144Xe + 208Pb and 132Sn + 208Pb. It is noticed that the production cross sections of unknown neutron-rich nuclei in the reaction 144Xe + 208Pb are at least two orders of magnitude larger than those in the reaction 136Xe + 208Pb. The radioactive beam induced transfer reactions 139,144Xe + 208Pb, considering beam intensities proposed in SPIRAL2 (Production System of Radioactive Ion and Acceleration On-Line project as well, for production of neutron-rich nuclei around the N=126 shell closure are investigated for the first time. It is found that, in comparison to the stable beam 136Xe, the radioactive beam 144Xe shows great advantages for producing neutron-rich nuclei with N=126 and the advantages get more obvious for producing nuclei with less charge number.

  20. Synthesis and investigation of superheavy elements - perspectives with radioactive beams

    International Nuclear Information System (INIS)

    Muenzenberg, G.

    1997-09-01

    The perspectives for the investigation of heavy and superheavy elements with intense beams of radioactive nuclei available from the new generation of secondary beam facilities in combination with modern experimental developments are the subject of this paper. The nuclear properties of the recently discovered shell nuclei centered at Z=108 and N=164 and predictions on the location of the superheavy region with improved theoretical models will be discussed. (orig.)

  1. On the thermalization achieved in the reactions involving superheavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, Rajni [Department of Physics, MCM DAV College for Women, Sector 36A, Chandigarh-160036, India rajnibansal.pu@gmail.com (India)

    2016-05-06

    In the present study, we aim to explore the role of Coulomb potential on the thermalization achieved in the reactions involving superheavy nuclei. Particularly, we shall study the degree of the equilibrium attained in a reaction by the 3D density plots, anisotropy ratio as well as by the rapidity distribution of the nucleons. Our study reveals that the degree of the equilibrium attained in the central reactions of the superheavy nuclei remains unaffected by the Coulomb potential.

  2. Recent searches for superheavy elements at the superhilac

    International Nuclear Information System (INIS)

    Hulet, E.K.

    1978-01-01

    The results of the search for superheavy elements are negative with respect to the finding of such elements. However, by assuming 2 spontaneous fission events as the lower limit of detection, the limits to their formation cross sections are calculated and plotted. It is noted that the half-life limits, also shown are easily within the huge uncertainties of the theoretical predicted half lives for any superheavy element nuclides produced in the experiment. 19 references

  3. {gamma} ray spectroscopy of neutron rich nuclei around N=20; Spectroscopie {gamma} des noyaux riches en neutrons autour de N=20

    Energy Technology Data Exchange (ETDEWEB)

    Gelin, M

    2007-09-15

    There is an island of inversion around {sup 32}Mg (12 protons, 20 neutrons) in contradiction with a shell closure N=20. It means a coexistence of spherical and deformed shapes. This work is devoted to the study of {gamma}-ray spectroscopy for nuclei in this region, based on an experiment done at GANIL with a composite secondary beam produced by fragmentation. The originality of the method used here lies in the possibility to study simultaneously several nuclei, and for each of them to explore several reaction channels. The VAMOS spectrometer was used for the identification of the ejectiles. The {gamma}-rays were detected with EXOGAM, a germanium clover array. The detectors used before and after the target allowed for a unique identification and a selection of the reaction channel: inelastic scattering, transfer and fragmentation reaction. In this thesis the following nuclei were studied: {sup 28}Ne, {sup 30-32}Mg {sup 31-34}Al, {sup 33-35}Si, {sup 35}P. New {gamma}-rays have been observed. The {gamma}-ray angular distributions and {gamma}-{gamma} angular correlations have been measured for some transitions. Assignment of spins and parities has been proposed for some states. In particular, in {sup 34}Si, the 3{sup -} assignment is confirmed and a new candidate for the second 0{sup +} has been proposed. In {sup 32}Mg, the state at 2.321 MeV, for which conflicting assignment existed, is deduced from the present data as a 4{sup +}, and a 6{sup +} state is proposed. (author)

  4. Sensitivity of the moment of inertia of neutron stars to the equation of state of neutron-rich matter

    International Nuclear Information System (INIS)

    Fattoyev, F. J.; Piekarewicz, J.

    2010-01-01

    The sensitivity of the stellar moment of inertia to the neutron-star matter equation of state is examined using accurately calibrated relativistic mean-field models. We probe this sensitivity by tuning both the density dependence of the symmetry energy and the high-density component of the equation of state, properties that are at present poorly constrained by existing laboratory data. Particularly attractive is the study of the fraction of the moment of inertia contained in the solid crust. Analytic treatments of the crustal moment of inertia reveal a high sensitivity to the transition pressure at the core-crust interface. This may suggest the existence of a strong correlation between the density dependence of the symmetry energy and the crustal moment of inertia. However, no correlation was found. We conclude that constraining the density dependence of the symmetry energy - through, for example, the measurement of the neutron skin thickness in 208 Pb - will place no significant bound on either the transition pressure or the crustal moment of inertia.

  5. Nuclear shell effects in neutron-rich nuclei around N=20 and N=32,34

    International Nuclear Information System (INIS)

    Seidlitz, Michael

    2012-01-01

    Nuclear shell effects in neutron-rich nuclei around N=20 and N=32,34 were studied by means of reduced transition probabilities, i.e. B(E2) and B(M1) values. To this end a series of Coulomb-excitation experiments, employing radioactive 31 Mg and 29,30 Na beams, as well as a precise lifetime experiment of excited states in 56 Cr were performed. The collective properties of excited states of 31 Mg were the subject of a Coulomb-excitation experiment at REX-ISOLDE, CERN, employing a radioactive 31 Mg beam at a beam energy of 3.0 MeV/u. The beam intensity amounted to 3000 ions/s on average. The highly efficient MINIBALL setup was employed, consisting of eight HPGe cluster detectors for γ-ray detection and a segmented Si-detector for coincident particle detection. The level scheme of 31 Mg was extended. Spin and parity assignment of the observed 945 keV state yielded 5/2 + and its de-excitation is dominated by a strong collective M1 transition. Comparison of the transition probabilities of 30,31,32 Mg establishes that for the N=19 magnesium isotope not only the ground state but also excited states are largely dominated by a deformed pf intruder configuration. This implies that 31 Mg is part of the so-called ''island of inversion''. Coulomb-excitation experiments of radioactive 29,30 Na were carried out at REX-ISOLDE, CERN, at a final beam energy of 2.85 MeV/u. De-excitation γ rays were detected by the MINIBALL γ-ray spectrometer in coincidence with scattered particles in a segmented Si-detector. Despite rather low beam intensities transition probabilities to the first excited states were deduced. Results of very recently published experiments at MSU and TRIUMF could be largely confirmed and extended. The measured B(E2) values agree well with shell-model predictions, supporting the idea that in the sodium isotopic chain the ground-state wave function contains a significant intruder admixture already at N=18, with N=19 having an almost pure 2p2h deformed ground

  6. Towards Superheavies: Spectroscopy of 94 < Z < 98, 150 < N < 154 Nuclei

    Directory of Open Access Journals (Sweden)

    Chowdhury P.

    2016-01-01

    nuclear structure studies are important testing grounds for theoretical models that aim to describe superheavy nuclei. To study the highest neutron orbitals (150 ≤ N ≤ 154, we have populated high angular momentum states in a series of Pu (Z = 94, Cm (Z = 96 and Cf (Z = 98 nuclei, via inelastic and transfer reactions, with heavy beams on long-lived radioactive actinide targets. Multiple collective excitation modes and structures were identified, and their configurations deduced. Quasiparticle alignments are mapped, with odd-A band structures helping identify specific orbital contributions via blocking arguments. Higher-order multipole shapes are observed to play a significant role in disentangling competing neutron and proton alignments. The N > 152 data provide new perspectives on physics beyond the N = 152 sub-shell gap.

  7. Study of the structure of light neutron rich nucleus with the Tonnerre array

    International Nuclear Information System (INIS)

    Pietri, St.

    2003-06-01

    This work concern the technical development made on the multidetector TONNERRE and the study of the 34 Si nucleus by a complete beta-neutron-gamma spectroscopy. In the first part various tests performed on modules of the detector in the 'Centre d'Etude de Bruyere le Chatel' are presented. A modification of the embassies of the photomultipliers tubes allows to gain more than 50% in the neutron efficiency and to obtain a threshold lower than 300 keV for the neutron energy. A complete C++ simulation of the neutron propagation in the array was carried out. It explains that the slow component of the light output of the scintillator may be responsible of the shape of the time-of-flight spectrum. The second part of these report presents the experiment devoted to the study of the structure of the 34 Si from the beta decay of the 34 Al. It was performed at the GANIL facility using the TONNERRE array and germanium of ENOGAM. The 34 Al was produced by projectile fragmentation of a 36 S beam of 50 MeV/A in a target of 9 Be. A complete beta scheme of the 34 Al is proposed. Eight neutron lines following the 34 Al decay were observed for the first time. Finally we suggest that a monopolar transition could occur in the 34 Si nucleus signing a O + 2 state at 2133 keV. (author)

  8. Feasibility studies of thermonuclear neutron capture synthesis of SHE

    International Nuclear Information System (INIS)

    Meldner, H.W.

    1978-01-01

    A variety of thermonuclear neutron sources and neutron capture targets were investigated for their potential of allowing signigicant production of heavy, perhaps superheavy, isotopes. The neutron sources considered range from inertial confinement microexplosives to (underground) macroexplosives. Optimal capture targets appear to be composites containing uranium and protactinium. 1 figure

  9. Superheavy magnetic monopoles and the standard cosmology

    International Nuclear Information System (INIS)

    Turner, M.S.

    1984-10-01

    The superheavy magnetic monopoles predicted to exist in grand unified theories (GUTs) are very interesting obsects, both from the point of view of particle physics, as well as from astrophysics and cosmology. Astrophysical and cosmological considerations have proved to be invaluable in studying the properties of GUT monopoles. Because of the glut of monopoles predicted in the standard cosmology for the simplest GUTs (so many that the Universe should have reached a temperature of 3 0 K at the tender age of approx. = 10,000 yrs), the simplest GUTs and the standard cosmology are not compatible. This is a very important piece of information about physics at unification energies (E greater than or equal to 10 14 GeV) and about the earliest moments (t less than or equal to 10 -34 s) of the Universe. In this talk the author reviews the cosmological consequences of GUT monopoles within the context of the standard hot big bang model. 46 references

  10. Superheavy thermal dark matter and primordial asymmetries

    Energy Technology Data Exchange (ETDEWEB)

    Bramante, Joseph [Perimeter Institute for Theoretical Physics,31 Caroline St N, Waterloo, ON N2L 2Y5 (Canada); Unwin, James [Department of Physics, University of Illinois at Chicago,845 W Taylor St, Chicago, IL 60607 (United States)

    2017-02-23

    The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, we show that the perturbative unitarity mass bound on thermal relic dark matter is relaxed to 10{sup 10} GeV. We proceed to study superheavy asymmetric dark matter models, made possible by a sizable entropy injection after dark matter freeze-out, and identify how the Affleck-Dine mechanism would generate the baryon and dark asymmetries.

  11. Superheavy thermal dark matter and primordial asymmetries

    International Nuclear Information System (INIS)

    Bramante, Joseph; Unwin, James

    2017-01-01

    The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, we show that the perturbative unitarity mass bound on thermal relic dark matter is relaxed to 10 10 GeV. We proceed to study superheavy asymmetric dark matter models, made possible by a sizable entropy injection after dark matter freeze-out, and identify how the Affleck-Dine mechanism would generate the baryon and dark asymmetries.

  12. Superheavy dark matter through Higgs portal operators

    Science.gov (United States)

    Kolb, Edward W.; Long, Andrew J.

    2017-11-01

    The WIMPzilla hypothesis is that the dark matter is a super-weakly-interacting and superheavy particle. Conventionally, the WIMPzilla abundance is set by gravitational particle production during or at the end of inflation. In this study we allow the WIMPzilla to interact directly with Standard Model fields through the Higgs portal, and we calculate the thermal production (freeze-in) of WIMPzilla dark matter from the annihilation of Higgs boson pairs in the plasma. The two particle-physics model parameters are the WIMPzilla mass and the Higgs-WIMPzilla coupling. The two cosmological parameters are the reheating temperature and the expansion rate of the universe at the end of inflation. We delineate the regions of parameter space where either gravitational or thermal production is dominant, and within those regions we identify the parameters that predict the observed dark matter relic abundance. Allowing for thermal production opens up the parameter space, even for Planck-suppressed Higgs-WIMPzilla interactions.

  13. Physics of superheavy dark matter in supergravity

    Science.gov (United States)

    Addazi, Andrea; Marciano, Antonino; Ketov, Sergei V.; Khlopov, Maxim Yu.

    New trends in inflationary model building and dark matter production in supergravity are considered. Starobinsky inflation is embedded into 𝒩 = 1 supergravity, avoiding instability problems, when the inflaton belongs to a vector superfield associated with a U(1) gauge symmetry, instead of a chiral superfield. This gauge symmetry can be spontaneously broken by the super-Higgs mechanism resulting in a massive vector supermultiplet including the (real scalar) inflaton field. Both supersymmetry (SUSY) and the R-symmetry can also be spontaneously broken by the Polonyi mechanism at high scales close to the inflationary scale. In this case, Polonyi particles and gravitinos become superheavy, and can be copiously produced during inflation by the Schwinger mechanism sourced by the universe expansion. The Polonyi mass slightly exceeds twice the gravitino mass, so that Polonyi particles are unstable and decay into gravitinos. Considering the mechanisms of superheavy gravitino production, we find that the right amount of cold dark matter composed of gravitinos can be achieved. In our scenario, the parameter space of the inflaton potential is directly related to the dark matter one, providing a new unifying framework of inflation and dark matter genesis. A multi-superfield extension of the supergravity framework with a single (inflaton) superfield can result in a formation of primordial nonlinear structures like mini- and stellar-mass black holes, primordial nongaussianity, and the running spectral index of density fluctuations. This framework can be embedded into the SUSY GUTs inspired by heterotic string compactifications on Calabi-Yau three-folds, thus unifying particle physics with quantum gravity.

  14. Identification of new neutron-rich rare-earth nuclei produced in /sup 252/Cf spontaneous fission

    CERN Document Server

    Greenwood, R C; Gehrke, R J; Meikrantz, D H

    1981-01-01

    A program of systematic study of the decay properties of neutron-rich rare-earth nuclei with 30 sneutron-rich rare-earth isotopes including /sup 155/Pm (t/sub 1/2/=48+or-4 s) and /sup 163/Gd (t/sub 1 /2/=68+or-3 s), in addition to 5.51 min /sup 158/Sm which was identified in an earlier series of experiments. (11 refs).

  15. Structure of neutron-rich isotopes of boron and carbon at the limits of stability

    International Nuclear Information System (INIS)

    Leblond, Sylvain

    2015-01-01

    The unbound nuclei 18 B and 21 C have been studied in an experiment undertaken at the RIBF-RIKEN using the recently commissioned SAMURAI spectrometer and NEBULA neutron array. The two systems were probed using single-neutron and single and two-proton knockout from secondary beams of 22 C, 22 N, et 23 O respectively in the case of 21 C and 19 B, 19 C and 20 N for 18 B. The invariant mass spectra were reconstructed from the momentum of the fragment ( 17 B, 20 C) and neutron. In order to interpret the results a complete simulation of the experimental setup was utilised. The analysis procedures as well as the calibrations were verified through a measurement of the well-known ground state of 16 B. In the case of 18 B three states were observed: an s-wave virtual state (as ≤ -50 fm), an l=2 resonance at E r =0.77 ± 0.09 MeV and an l=0 resonance at E r = 1.6 ± 0.6 MeV. These results suggest that the low-lying level structure of 18 B is governed by a competition between the neutron 2s 1/2 and 1d 5/2 configurations. In the case of 21 C resonances were observed at E r = 0.8 ± 0.15 MeV (l = 0) and E r = 1.5 ±0.1 MeV (l=2), a result which confirms predictions of an inversion of the 5/2 + and 1/2 + levels. Finally an analysis of the momentum distributions for 18 B and 21 C produced in single-neutron knockout was carried out. The results indicate that the valence neutrons 19 B and 22 C are in mixed (2s 1/2 ) 2 and (1d 5/2 ) 2 configurations. (author)

  16. High flux, beamed neutron sources employing deuteron-rich ion beams from D2O-ice layered targets

    Science.gov (United States)

    Alejo, A.; Krygier, A. G.; Ahmed, H.; Morrison, J. T.; Clarke, R. J.; Fuchs, J.; Green, A.; Green, J. S.; Jung, D.; Kleinschmidt, A.; Najmudin, Z.; Nakamura, H.; Norreys, P.; Notley, M.; Oliver, M.; Roth, M.; Vassura, L.; Zepf, M.; Borghesi, M.; Freeman, R. R.; Kar, S.

    2017-06-01

    A forwardly-peaked bright neutron source was produced using a laser-driven, deuteron-rich ion beam in a pitcher-catcher scenario. A proton-free ion source was produced via target normal sheath acceleration from Au foils having a thin layer of D2O ice at the rear side, irradiated by sub-petawatt laser pulses (˜200 J, ˜750 fs) at peak intensity ˜ 2× {10}20 {{W}} {{cm}}-2. The neutrons were preferentially produced in a beam of ˜70° FWHM cone along the ion beam forward direction, with maximum energy up to ˜40 MeV and a peak flux along the axis ˜ 2× {10}9 {{n}} {{sr}}-1 for neutron energy above 2.5 MeV. The experimental data is in good agreement with the simulations carried out for the d(d,n)3He reaction using the deuteron beam produced by the ice-layered target.

  17. My journey to the superheavy island with Szymanski, Nilsson, Nix, and Swiatecki from Lysekil to the present

    International Nuclear Information System (INIS)

    Mueller, Peter

    2010-01-01

    We discuss the great theoretical insights on nuclear stability that emerged in the late 1960s, especially the realization that observable nuclei might include a superheavy island 20+ protons beyond uranium with 92 protons. However, we now realize that the early models were not sufficiently quantitative to yield definite conclusions. Further groundwork for such models was laid in the 1970s. Around 1980 more quantitative, global and universal models appeared and together with experimental advances the mapping of the superheavy island, or as it turns out now, continent started in earnest. We review these early developments and conclude with some examples of our current insights. In particular, 1) some theoretical models do have predictive capabilities for nuclear properties such as ground-state masses, shapes, and half-lives 10 or more neutrons and protons away from previously known regions and 2) the superheavy island may be a continent connected to the actinides by a narrow land bridge; the continent itself may extend from about proton number Z = 110 to Z = 120 or slightly beyond. (author)

  18. Study of single particle properties of neutron-rich Na isotopes on the "shore of the island of inversion" by means of neutron-transfer reactions

    CERN Multimedia

    Reiter, P; Blazhev, A A; Riisager, K; Bastin, B; Tengborn, E A; Kruecken, R; Voulot, D; Jeppesen, H B; Hadinia, B; Gernhaeuser, R A; Fynbo, H O U; Georgiev, G P; Habs, D; Fraile prieto, L M; Chapman, R; Nilsson, T; Diriken, J V J; Jenkins, D G; Kroell, T; Leske, J; Huyse, M L; Patronis, N

    We aim at the investigation of single particle properties of neutron-rich Na isotopes around the "shore of the island of inversion". As first experiment of this programme, we propose to study excited states in the isotope $^{29}$Na by a one-neutron transfer reaction with a $^{28}$Na beam at 3 MeV/u obtained from REX-ISOLDE impinging on a CD$_{2}$-target. The $\\gamma$-rays will be detected by the MINIBALL array and the particles by the T-REX array of segmented Si detectors. The main physics aims are to extract from the relative spectroscopic factors information on the configurations contributing to the wave functions of the populated states and, secondly, to identify and characterize negative parity states whose excitation energies reflect directly the N= 28 gap in this region. The results will be compared to recent shell model calculations involving new residual interactions. This will shed new light on the evolution of single particle structure and help to understand the underlying physics relevant for the f...

  19. Neutron und X-ray diffraction study on the superstructure of a sodium-rich low plagioclase An sub(16.5)

    International Nuclear Information System (INIS)

    Joswig, W.; Korekawa, M.

    1977-01-01

    Neutron and X-ray diffraction experiments had been carried out on a sodium-rich low plagioclase Ansub(16.5) from Sultan Hamud, Kenya. In constrast to previous work very weak (g) reflections (satellites) for all reflections Okl, except reflections 001, could be observed. It is shown that the neutron diffraction method is advantageous to study on submicroscopic periodic domain structure as reported here. (orig.) [de

  20. Mass measurement project by determination of Q{sub {beta}} for neutron-rich nuclei; Projet de mesure des masses par determination des Q{sub {beta}} pour des noyaux tres riches en neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Pautrat, M; Lagrange, J M; Petizon, L [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire; Vanhorenbeeck, J; Duhamel, P [Brussels Univ. (Belgium). Inst. d` Astronomie et d` Astrophysique; Binon, F [Universite Libre de Bruxelles (Belgium)

    1994-12-31

    The aim of the project described hereafter is to collect new data on the exotic neutron rich nuclei of the Fe to Zn region, and in particular to determine their masses, for both nuclear physics and astrophysics purposes. These isotopes will be produced through projectile fragmentation at the GANIL facility and selected by the LISE3 spectrometer. Their half-lives will be measured as well as the energy of their main {gamma} rays; {gamma} - {gamma} coincidences will then allow to build a preliminary level scheme. The analysis of {beta} spectra and {beta} - {gamma} coincidences will finally provide the maximum {beta} decay energies of the studied nuclei leading to their masses. The difficulties arising from the low production rates, the {beta} detection, the data handling are discussed together with the solutions proposed to overcome them. (authors). 17 refs.

  1. Neutron scattering study of the magnetic correlations of iron rich Fe-Zr glasses

    International Nuclear Information System (INIS)

    Fernandez-Baca, J.A.; Rhyne, J.J.; Erwin, R.W.; Fish, G.E.

    1988-01-01

    Small angle neutron scattering (SANS) and polarized-beam spin rotation measurements show that amorphous Fe/sub 80/Zr/sub 10/ does not exhibit conventional long range ferromagnetic order below T/sub C/. The SANS measurements show the existence of two characteristic length scales; one provides evidence of relatively large spin clusters, while the other is characteristic of the spin dynamics. 4 refs., 3 figs

  2. Saturation of Deformation and Identical Bands in Very-Neutron Rich Sr Isotopes

    CERN Multimedia

    2002-01-01

    The present proposal aims at establishing nuclear properties in an isotopic chain showing unique features. These features include the saturation of ground state deformation at its onset and the existence of ground state identical bands in neighbouring nuclei with the same deformation. The measurements should help to elucidate the role played by the proton-neutron residual interaction between orbitals with large spatial overlap, i.e. $\\pi g _{9/2} \

  3. Statistical properties of warm nuclei: Investigating the low-energy enhancement in the $\\gamma$- strength function of neutron-rich nuclei

    CERN Multimedia

    We propose to start a program to study the $\\gamma$-ray strength function of neutron rich nuclei in inverse kinematics with radioactive beams at HIE-ISOLDE. An unexpected increase in the $\\gamma$-strength function at low energy has been observed in several stable nuclei using the Oslo method. This year these results were confirmed with a different experimental technique and model independent analysis developed by iThemba/Livermore. If this enhancement of the $\\gamma$-strength function is also present in neutron-rich nuclei, it will strongly affect the neutron capture cross sections, which are important input in stellar models of synthesis of heavier elements in stars. We propose to start with an experiment using a $^{66}$Ni beam of 5.5 MeV /u, where the data will be analyzed using both methods independently, and we are sure to get enough statistics, before moving to more neutron-rich nuclei. When/if neutron-rich Ti, Fe or Mo beams will be available at ISOLDE, we will submit additional proposals.

  4. Production of neutron-rich isotopes by cold fragmentation in the reaction 197Au + Be at 950 A MeV

    International Nuclear Information System (INIS)

    Benlliure, J.; Pereira, J.; Schmidt, K.H.; Cortina-Gil, D.; Enqvist, T.; Heinz, A.; Junghans, A.R.; Farget, F.; Taieb, J.

    1999-09-01

    The production cross sections and longitudinal-momentum distributions of very neutron-rich isotopes have been investigated in the fragmentation of a 950 A MeV 179 Au beam in a beryllium target. Seven new isotopes ( 193 Re, 194 Re, 191 W, 192 W, 189 Ta, 187 Hf and 188 Hf) and the five-proton-removal channel were observed for the first time. The reaction mechanism leading to the formation of these very neutron-rich isotopes is explained in terms of the cold-fragmentation process. An analytical model describing this reaction mechanism is presented. (orig.)

  5. $\\beta$-decay study of neutron-rich Tl, Pb, and Bi by means of the pulsed-release technique and resonant laser ionisation

    CERN Multimedia

    Lettry, J

    2002-01-01

    It is proposed to study new neutron-rich nuclei around the Z = 82 magic shell closure, with major relevance for understanding the evolution of nuclear structure at extreme isospin values. Following the IS354 experiment, $\\beta$-decay studies of neutron-rich thallium, lead and bismuth isotopes will be performed for 215 $\\leqslant$ A $\\leqslant$ 219. To this purpose the pulsed-release technique, which was pioneered at ISOLDE, will be optimised. It will be complemented with the higher element selectivity that can be obtained by the unique features of resonant laser ionisation, available at ISOLDE from the RILIS source.

  6. Direct mass measurements in the light neutron-rich region using a combined energy and time-of-flight technique

    International Nuclear Information System (INIS)

    Pillai, C.; Swenson, L.W.; Vieira, D.J.; Butler, G.W.; Wouters, J.M.; Rokni, S.H.; Vaziri, K.; Remsberg, L.P.

    1985-01-01

    This experiment has demonstrated that direct mass measurements can be performed (albeit of low precision in this first attempt) using the M proportional to ET 2 method. This technique has the advantage that many particle-bound nuclei, produced in fragmentation reactions can be measured simultaneously, independent of their N or Z. The main disadvantage of this approach is that both energy and time-of-flight must be measured precisely on an absolute scale. Although some mass walk with N and Z was observed in this experiment, these uncertainties were largely removed by extrapolating the smooth dependence observed for known nuclei which lie closer to the valley of β-stability. Mass measurements for several neutron-rich light nuclei ranging from 17 C to 26 Ne have been performed. In all cases these measurements agree with the latest mass compilation of Wapstra and Audi. The masses of 20 N and 24 F have been determined for the first time

  7. Low-lying level structure of the neutron-rich nucleus {sup 109}Nb: A possible oblate-shape isomer

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, H., E-mail: hiroshi@ribf.riken.j [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sumikama, T. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Nishimura, S. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yoshinaga, K. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Li, Z. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Miyashita, Y. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Yamaguchi, K. [Department of Physics, Osaka University, Machikaneyama-machi 1-1, Osaka 560-0043 Toyonaka (Japan); Baba, H. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Berryman, J.S. [Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Blasi, N. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy); Bracco, A.; Camera, F. [INFN, Sezione di Milano, via Celoria 16, I-20133 Milano (Italy); Dipartimento di Fisica, Universita di Milano, via Celoria 16, I-20133 Milano (Italy); Chiba, J. [Department of Physics, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba (Japan); Doornenbal, P. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Go, S.; Hashimoto, T.; Hayakawa, S. [Center for Nuclear Study, University of Tokyo, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Hinke, C. [Physik Department, Technische Universitaet Muenchen, D-85748 Garching (Germany); Ideguchi, E. [Center for Nuclear Study, University of Tokyo, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Isobe, T. [RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2011-01-31

    The neutron-rich nuclei {sup 109}Nb and {sup 109}Zr have been populated using in-flight fission of a {sup 238}U beam at 345 MeV/nucleon at the RIBF facility. A T{sub 1/2}=150(30) ns isomer at 313 keV has been identified in {sup 109}Nb for the first time. The low-lying levels in {sup 109}Nb have been also populated following the {beta}-decay of {sup 109}Zr. Based on the difference in feeding pattern between the isomeric and {beta} decays, the decay scheme from the isomeric state in {sup 109}Nb was established. The observed hindrances of the electromagnetic transitions deexciting the isomeric state are discussed in terms of possible shape coexistence. Potential energy surface calculations for single-proton configurations predict the presence of low-lying oblate-deformed states in {sup 109}Nb.

  8. β decay half-live measurement of 22 very neutron-rich isotopes in the Ti-Ni region

    International Nuclear Information System (INIS)

    Czajkowski, S.; Ameil, F.; Armbruster, P.; Donzaud, C.; Geissel, H.; Kozhuharov, C.; Schwab, W.; Bernas, M.; Dessagne, P.; Miehe, C.; Grewe, A.; Hanelt, E.; Heinz, A.; Jong, M. de; Steinhaeuser, S.; Janas, Z.

    1997-01-01

    Very neutron-rich Ti to Ni isotopes were produced in fragmentation of a 500 MeV/u 86 Kr primary beam on a Be target, separated using the Fragment Separator at GSI, and implanted in a set of PIN-diodes where β-decay particles were detected. From time-correlations analysis the unknown β-decay half-life of 22 isotopes were determined. Their values are within 10 -1 s. The β decay spectrum of 70 Co is presented as resulting from an analysis of the first β particle detected after ion implantation in the same detector. Also are presented the example of 3 β decay chains for 65 Mn and 66 Mn. The identification of such chains was instrumental in reducing the influence of background noise in the time correlation analysis while it allows life-time determinations of high confidence

  9. β Decay processes of neutron-rich isotopes of sodium and magnesium

    International Nuclear Information System (INIS)

    Guillemaud, D.

    1982-01-01

    The γ and n activities from the β decay of Na isotopes up to 34 Na, which are formed in high-energy fragmentation and analysed through mass-spectrometry techniques, are observed as well as those from their Mg descendants. Their intensities Isub(γ) and Isub(β) are measured; some radioactive half lives are determined. Delayed-neutron branching ratios Pn are measured. The existence of 35 Na is for the first time indicated. The position of the first excited 2 + level is taken as an indication of a stronger deformation for that isotope [fr

  10. Direct mass and lifetime measurements of neutron-rich nuclei up to A∼100 using the TOFI spectrometer at LAMPF

    International Nuclear Information System (INIS)

    Lind, V.G.

    1993-01-01

    This project was directed toward the study of neutron-rich nuclei using the experimental facilities at LAMPF, which is a part of LANL. The principal results of the investigation include the discovery of many new isotopes along with a measurement of their masses and in particular those nuclides in the Z = 7--19 and 14 --26 regions of the chart of the nuclides.Thirty-four new nuclides were detected and studied with their masses being measured with relatively high accuracy, and an additional twenty-six that were previously known and measured were remeasured to an improved accuracy. Besides providing new information about the mass surface in new and extended redons of the chart of the nuclides, this investigation enabled properties and previously unknown structure of some of the nuclei to be determined such as nuclear deformation among some of the nuclides. Also a study of the neutron pairing gaps and the proton pairing gaps among these nuclides was made. Other developments also achieved included instrument (TOFI) improvements and upgrades and theoretical investigations into the masses of the hadrons

  11. The structure of neutron-rich nuclei explored via in-beam gamma-ray spectroscopy of fast beams

    International Nuclear Information System (INIS)

    Glasmacher, T.; Campbell, C.M.; Church, J.A.; Dinca, D.C.; Hansen, P.G.; Olliver, H.; Perry, B.C.; Sherrill, B.M.; Terry, J.R.; Bazin, D.; Enders, J.; Gade, A.; Hu, Z.; Mueller, W.F.

    2003-01-01

    In-beam gamma-ray spectroscopy with fast exotic beams provides an efficient tool to study bound states in exotic neutron-rich nuclei. Specialized experimental techniques have been developed and explore different aspects of nuclear structure. Inelastic scattering experiments with γ-ray detection can measure the response of exotic nuclei to electromagnetic (Coulomb excitation with a heavy target) or hadronic probes (proton scattering with hydrogen target). In-beam fragmentation populates higher-lying bound states to establish levels. Single- and two-nucleon knockout reactions allow for detailed wavefunction spectroscopy of individual levels and for the measurement of spectroscopic factors. Experimental programs employing these techniques are now underway at all projectile-fragmentation facilities around the world. Here we report on several successful in-beam gamma-ray spectroscopy experiments that have been performed at the Coupled Cyclotron Facility at Michigan State University with an emphasis on elucidating the evolution of nuclear structure around neutron numbers N=16, N=20, and N=28 in the π(sd) shell. (orig.)

  12. Actinide collisions for QED and superheavy elements with the time-dependent Hartree-Fock theory and the Balian-Vénéroni variational principle

    Directory of Open Access Journals (Sweden)

    Kedziora David J.

    2011-10-01

    Full Text Available Collisions of actinide nuclei form, during very short times of few zs (10−21 s, the heaviest ensembles of interacting nucleons available on Earth. Such collisions are used to produce super-strong electric fields by the huge number of interacting protons to test spontaneous positron-electron pair emission (vacuum decay predicted by the quantum electrodynamics (QED theory. Multi-nucleon transfer in actinide collisions could also be used as an alternative way to fusion in order to produce neutron-rich heavy and superheavy elements thanks to inverse quasifission mechanisms. Actinide collisions are studied in a dynamical quantum microscopic approach. The three-dimensional time-dependent Hartree-Fock (TDHF code tdhf3d is used with a full Skyrme energy density functional to investigate the time evolution of expectation values of one-body operators, such as fragment position and particle number. This code is also used to compute the dispersion of the particle numbers (e.g., widths of fragment mass and charge distributions from TDHF transfer probabilities, on the one hand, and using the BalianVeneroni variational principle, on the other hand. A first application to test QED is discussed. Collision times in 238U+238U are computed to determine the optimum energy for the observation of the vacuum decay. It is shown that the initial orientation strongly affects the collision times and reaction mechanism. The highest collision times predicted by TDHF in this reaction are of the order of ~ 4 zs at a center of mass energy of 1200 MeV. According to modern calculations based on the Dirac equation, the collision times at Ecm > 1 GeV are sufficient to allow spontaneous electron-positron pair emission from QED vacuum decay, in case of bare uranium ion collision. A second application of actinide collisions to produce neutron-rich transfermiums is discussed. A new inverse quasifission mechanism associated to a specific orientation of the nuclei is proposed to

  13. The Superheavy Elements and Anti-Gravity

    International Nuclear Information System (INIS)

    Anastasovski, Petar K.

    2004-01-01

    The essence of any propulsion concept is to overcome gravity. Anti-gravity is a natural means to achieve this. Thus, the technology to pursue anti-gravity, by using superheavy elements, may provide a new propulsion paradigm. The theory of superluminal relativity provides a hypothesis for existence of elements with atomic number up to Z = 145, some of which may possess anti-gravity properties. Analysis results show that curved space-time exists demonstrating both gravitic and anti-gravitic properties not only around nuclei but inside the nuclei as well. Two groups of elements (Z < 64 and 63 < Z <145) exist that demonstrate these capabilities. The nuclei of the first group of elements have the masses with only the property of gravity. The nuclei of the elements of the second group have the masses with both properties: gravity and anti-gravity in two different ranges of curved space-time around the nuclei.. The hypothetical element with Z = 145 is the unique among all elements whose nucleus has only anti-gravity property. It is proposed that this element be named Hawking, in honour of Stephen W. Hawking

  14. On the Production of Superheavy Elements

    CERN Document Server

    Armbruster, P

    2003-01-01

    Since the discovery of Deformed Superheavy Nuclei (1983–85) a bridge connects the island of SHE to known isotopes of lighter elements. What we know experimentally and theoretically on the nuclear structure of SHE is reported in a first section. The making of the elements, with an analysis of production cross sections, and the macroscopic limitation to Z=112+ is presented in a second section. The break-down of fusion cross sections in the ‘Coulomb Falls’ within a range of about 10 elements is introduced as the universal limiting phenomenon. How the nuclear structure of the collision partners modifies the on-set of this limitation is presented in Section 3. Reactions induced by deformed nuclei are pushed by side collisions to higher excitation energies (4n- and 5n-channels), whereas reactions driven by the cluster-like, closed-shell nuclei, 208126Pb and 13882Ba, are kept at low excitation energies (1n- and 2n-channels). The on-set of production limitation for deformed collision partners is moved to smalle...

  15. Quasifission Dynamics in the Formation of Superheavy Elements

    Directory of Open Access Journals (Sweden)

    Hinde D.J.

    2017-01-01

    Full Text Available Superheavy elements are created through the fusion of two heavy nuclei. The large Coulomb energy that makes superheavy elements unstable also makes fusion forming a compact compound nucleus very unlikely. Instead, after sticking together for a short time, the two nuclei usually come apart, in a process called quasifission. Mass-angle distributions give the most direct information on the characteristics and time scales of quasifission. A systematic study of carefully chosen mass-angle distributions has provided information on the global trends of quasifission. Large deviations from these systematics at beam energies near the capture barrier reveal the major role played by the nuclear structure of the two colliding nuclei in determining the reaction outcome, and thus implicitly in hindering or favouring superheavy element synthesis.

  16. From heavy nuclei to super-heavy nuclei

    International Nuclear Information System (INIS)

    Theisen, Ch.

    2003-01-01

    The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)

  17. Actinide targets for the synthesis of super-heavy elements

    International Nuclear Information System (INIS)

    Roberto, J.B.; Alexander, C.W.; Boll, R.A.; Burns, J.D.; Ezold, J.G.; Felker, L.K.; Hogle, S.L.; Rykaczewski, K.P.

    2015-01-01

    Since 2000, six new super-heavy elements with atomic numbers 113 through 118 have been synthesized in hot fusion reactions of "4"8Ca beams on actinide targets. These target materials, including "2"4"2Pu, "2"4"4Pu, "2"4"3Am, "2"4"5Cm, "2"4"8Cm, "2"4"9Cf, and "2"4"9Bk, are available in very limited quantities and require specialized production and processing facilities resident in only a few research centers worldwide. This report describes the production and chemical processing of heavy actinide materials for super-heavy element research, current availabilities of these materials, and related target fabrication techniques. The impact of actinide materials in super-heavy element discovery is reviewed, and strategies for enhancing the production of rare actinides including "2"4"9Bk, "2"5"1Cf, and "2"5"4Es are described.

  18. Quasifission in heavy and superheavy element formation reactions

    International Nuclear Information System (INIS)

    Hinde, D.J.; Dasgupta, M.; Jeung, D.Y.; Mohanto, G.; Prasad, E.; Simenel, C.; Walshe, J.; Wahkle, A.; Williams, E.; Carter, I.P.; Cook, K.J.; Kalkal, Sunil; Rafferty, D.C.; Rietz, R. du; Simpson, E.C.; David, H.M.; Düllmann, Ch.E.; Khuyagbaatar, J.

    2016-01-01

    Superheavy elements are created in the laboratory by the fusion of two heavy nuclei. The large Coulomb repulsion that makes superheavy elements decay also makes the fusion process that forms them very unlikely. Instead, after sticking together for a short time, the two nuclei usually come apart, in a process called quasifission. Mass-angle distributions give the most direct information on the characteristics and time scales of quasifission. A systematic study of carefully chosen mass-angle distributions has provided information on the global trends of quasifission. Large deviations from these systematics reveal the major role played by the nuclear structure of the two colliding nuclei in determining the reaction outcome, and thus implicitly in hindering or favouring superheavy element production.

  19. Measurement of the magnetic moment of the 2$^{+}$ state in neutron-rich radioactive $^{72,74}$Zn using the transient field technique in inverse kinematics

    CERN Multimedia

    Kruecken, R; Speidel, K; Voulot, D; Neyens, G; Gernhaeuser, R A; Fraile prieto, L M; Leske, J

    We propose to measure the sign and magnitude of the g-factors of the first 2$^{+}$ states in radioactive neutron-rich $^{72,74}$Zn applying the transient field (TF) technique in inverse kinematics. The result of this experiment will allow to probe the $\

  20. Phenomenological study of nuclear structure of neutron-rich 88Rb isotope

    Science.gov (United States)

    Gupta, Surbhi; Gupta, Anuradha; Bharti, Arun

    2018-05-01

    A theoretical study of the nuclear structure of odd-odd 88Rb nucleus in the A ˜100 mass region is carried out by using the angular-momentum-projection technique implemented in the Projected Shell Model (PSM). The influence of the high-j orbitals, h11/2 for neutrons and g9/2 for protons on the structure of 88Rb isotope is investigated in the present case by assuming an axial symmetry in the deformed basis. For this isotope, PSM calculations are performed to obtain the yrast line and also the description of the formation of the yrast level structure from multi-quasi-particle configurations. The back-bending in moment of inertia and transition energies have also been calculated and compared with the experimental data.

  1. Neutron-proton pairing effect on the proton-rich nuclei moment of inertia

    International Nuclear Information System (INIS)

    Mokhtari, D.; Ami, I.; Fellah, M.; Allal, N.H.; Fellah, M.; Allal, N.H.

    2008-01-01

    The neutron-proton (n-p) pairing effect on the nuclear moment of inertia is studied within the BCS approximation in the isovector case. An analytical expression of the moment of inertia is established by means of the cranking model. This expression generalizes the usual BCS one (i.e. when only the pairing between like-particles is considered). The moment of inertia of N = Z even-even nuclei, for which experimental values are known, i.e., such as 32 ≤ A ≤ 80, has been numerically evaluated, with and without inclusion of the n-p pairing effect. The used single-particle and Eigen-states are those of a deformed Woods-Saxon mean field. It turns out that the inclusion of the n-p pairing improves the obtained values when compared to the usual BCS approximation, since the average discrepancies with the experimental data are respectively 7% and 37%. (authors)

  2. Neutron-proton pairing effect on the proton-rich nuclei moment of inertia

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari, D.; Ami, I.; Fellah, M.; Allal, N.H. [Laboratoire de Physique Theorique, Faculte de Physique, USTHB, Algiers (Algeria); Fellah, M.; Allal, N.H. [Centre de Recherche Nucleaire d' Alger, COMENA, Algiers (Algeria)

    2008-07-01

    The neutron-proton (n-p) pairing effect on the nuclear moment of inertia is studied within the BCS approximation in the isovector case. An analytical expression of the moment of inertia is established by means of the cranking model. This expression generalizes the usual BCS one (i.e. when only the pairing between like-particles is considered). The moment of inertia of N = Z even-even nuclei, for which experimental values are known, i.e., such as 32 {<=} A {<=} 80, has been numerically evaluated, with and without inclusion of the n-p pairing effect. The used single-particle and Eigen-states are those of a deformed Woods-Saxon mean field. It turns out that the inclusion of the n-p pairing improves the obtained values when compared to the usual BCS approximation, since the average discrepancies with the experimental data are respectively 7% and 37%. (authors)

  3. Decay of neutron-rich Mn nuclides and deformation of heavy Fe isotopes

    CERN Document Server

    Hannawald, M; Wöhr, A; Walters, W B; Kratz, K L; Fedosseev, V; Mishin, V I; Böhmer, W; Pfeiffer, B; Sebastian, V; Jading, Y; Köster, U; Lettry, Jacques; Ravn, H L

    1999-01-01

    The use of chemically selective laser ionization combined with beta-delayed neutron counting at CERN/ISOLDE has permitted identification and half-life measurements for 623-ms Mn-61 up through 14-ms Mn-69. The measured half-lives are found to be significantly longer near N=40 than the values calculated with a QRPA shell model using ground-state deformations from the FRDM and ETFSI models. Gamma-ray singles and coincidence spectroscopy has been performed for Mn-64 and Mn-66 decays to levels of Fe-64 and Fe-66, revealing a significant drop in the energy of the first 2+ state in these nuclides that suggests an unanticipated increase in collectivity near N=40.

  4. Role of nuclear couplings in the inelastic excitation of weakly-bound neutron-rich nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Dasso, C.H. [Niels Bohr Institute, Copenhagen (Denmark); Lenzi, S.M.; Vitturi, A. [Universita di Padova (Italy)

    1996-12-31

    Much effort is presently devoted to the study of nuclear systems far from the stability line. Particular emphasis has been placed in light systems such as {sup 11}Li, {sup 8}B and others, where the very small binding energy of the last particles causes their density distribution to extend considerably outside of the remaining nuclear core. Some of the properties associated with this feature are expected to characterize also heavier systems in the vicinity of the proton or neutron drip lines. It is by now well established that low-lying concentrations of multipole strength arise from pure configurations in which a peculiar matching between the wavelength of the continuum wavefunction of the particles and the range of the weakly-bound hole states occurs. To this end the authors consider the break-up of a weakly-bound system in a heavy-ion collision and focus attention in the inelastic excitation of the low-lying part of the continuum. They make use of the fact that previous investigations have shown that the multipole response in this region is not of a collective nature and describe their excited states as pure particle-hole configurations. Since the relevant parameter determining the strength distributions is the binding energy of the last bound orbital they find it most convenient to use single-particle wavefunctions generated by a sperical square-well potential with characteristic nuclear dimensions and whose depth has been adjusted to give rise to a situation in which the last occupied neutron orbital is loosely-bound. Spin-orbit couplings are, for the present purpose, ignored. The results of this investigation clearly indicate that nuclear couplings have the predominant role in causing projectile dissociation in many circumstances, even at bombarding energies remarkably below the Coulomb barrier.

  5. A novel approach to the island of stability of super-heavy elements search

    Directory of Open Access Journals (Sweden)

    Wieloch A.

    2016-01-01

    Full Text Available It is expected that the cross section for super-heavy nuclei production of Z > 118 is dropping into the region of tens of femto barns. This creates a serious limitation for the complete fusion technique that is used so far. Moreover, the available combinations of the neutron to proton ratio of stable projectiles and targets are quite limited and it can be difficult to reach the island of stability of super heavy elements using complete fusion reactions with stable projectiles. In this context, a new experimental investigation of mechanisms other than complete fusion of heavy nuclei and a novel experimental technique are invented for our search of super- and hyper-nuclei. This contribution is focused on that technique.

  6. Small angle neutron scattering modeling of copper-rich precipitates in steel

    International Nuclear Information System (INIS)

    Spooner, S.

    1997-11-01

    The magnetic to nuclear scattering intensity ratio observed in the scattering from copper rich precipitates in irradiated pressure vessel steels is much smaller than the value of 11.4 expected for a pure copper precipitate in iron. A model for precipitates in pressure vessel steels which matches the observed scattering typically incorporates manganese, nickel, silicon and other elements and it is assumed that the precipitate is non-magnetic. In the present work consideration is given to the effect of composition gradients and ferromagnetic penetration into the precipitate on the small angle scattering cross section for copper rich clusters as distinguished from conventional precipitates. The calculation is an extension of a scattering model for micelles which consist of shells of varying scattering density. A discrepancy between recent SANS scattering experiments on pressure vessel steels was found to be related to applied magnetic field strength. The assumption of cluster structure and its relation to atom probe FIM findings as well as the effects of insufficient field for magnetic saturation is discussed

  7. Neutron Skins and Neutron Stars

    OpenAIRE

    Piekarewicz, J.

    2013-01-01

    The neutron-skin thickness of heavy nuclei provides a fundamental link to the equation of state of neutron-rich matter, and hence to the properties of neutron stars. The Lead Radius Experiment ("PREX") at Jefferson Laboratory has recently provided the first model-independence evidence on the existence of a neutron-rich skin in 208Pb. In this contribution we examine how the increased accuracy in the determination of neutron skins expected from the commissioning of intense polarized electron be...

  8. Electronic structure theory of the superheavy elements

    Energy Technology Data Exchange (ETDEWEB)

    Eliav, Ephraim, E-mail: ephraim@tau.ac.il [School of Chemistry, Tel Aviv University, 6997801 Tel Aviv (Israel); Fritzsche, Stephan, E-mail: s.fritzsche@gsi.de [Helmholtz-Institut Jena, Fröbelstieg 3, D-07743 Jena (Germany); Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena, D-07743 Jena (Germany); Kaldor, Uzi, E-mail: kaldor@tau.ac.il [School of Chemistry, Tel Aviv University, 6997801 Tel Aviv (Israel)

    2015-12-15

    High-accuracy calculations of atomic properties of the superheavy elements (SHE) up to element 122 are reviewed. The properties discussed include ionization potentials, electron affinities and excitation energies, which are associated with the spectroscopic and chemical behavior of these elements, and are therefore of considerable interest. Accurate predictions of these quantities require high-order inclusion of relativity and electron correlation, as well as large, converged basis sets. The Dirac–Coulomb–Breit Hamiltonian, which includes all terms up to second order in the fine-structure constant α, serves as the framework for the treatment; higher-order Lamb shift terms are considered in some selected cases. Electron correlation is treated by either the multiconfiguration self-consistent-field approach or by Fock-space coupled cluster theory. The latter is enhanced by the intermediate Hamiltonian scheme, allowing the use of larger model (P) spaces. The quality of the calculations is assessed by applying the same methods to lighter homologs of the SHEs and comparing with available experimental information. Very good agreement is obtained, within a few hundredths of an eV, and similar accuracy is expected for the SHEs. Many of the properties predicted for the SHEs differ significantly from what may be expected by straightforward extrapolation of lighter homologs, demonstrating that the structure and chemistry of SHEs are strongly affected by relativity. The major scientific challenge of the calculations is to find the electronic structure and basic atomic properties of the SHE and assign its proper place in the periodic table. Significant recent developments include joint experimental–computational studies of the excitation spectrum of Fm and the ionization energy of Lr, with excellent agreement of experiment and theory, auguring well for the future of research in the field.

  9. Evidence for prevalent Z = 6 magic number in neutron-rich carbon isotopes.

    Science.gov (United States)

    Tran, D T; Ong, H J; Hagen, G; Morris, T D; Aoi, N; Suzuki, T; Kanada-En'yo, Y; Geng, L S; Terashima, S; Tanihata, I; Nguyen, T T; Ayyad, Y; Chan, P Y; Fukuda, M; Geissel, H; Harakeh, M N; Hashimoto, T; Hoang, T H; Ideguchi, E; Inoue, A; Jansen, G R; Kanungo, R; Kawabata, T; Khiem, L H; Lin, W P; Matsuta, K; Mihara, M; Momota, S; Nagae, D; Nguyen, N D; Nishimura, D; Otsuka, T; Ozawa, A; Ren, P P; Sakaguchi, H; Scheidenberger, C; Tanaka, J; Takechi, M; Wada, R; Yamamoto, T

    2018-04-23

    The nuclear shell structure, which originates in the nearly independent motion of nucleons in an average potential, provides an important guide for our understanding of nuclear structure and the underlying nuclear forces. Its most remarkable fingerprint is the existence of the so-called magic numbers of protons and neutrons associated with extra stability. Although the introduction of a phenomenological spin-orbit (SO) coupling force in 1949 helped in explaining the magic numbers, its origins are still open questions. Here, we present experimental evidence for the smallest SO-originated magic number (subshell closure) at the proton number six in 13-20 C obtained from systematic analysis of point-proton distribution radii, electromagnetic transition rates and atomic masses of light nuclei. Performing ab initio calculations on 14,15 C, we show that the observed proton distribution radii and subshell closure can be explained by the state-of-the-art nuclear theory with chiral nucleon-nucleon and three-nucleon forces, which are rooted in the quantum chromodynamics.

  10. Neutron rich 73Ga and 79As isotopes via the (α,p) reaction

    International Nuclear Information System (INIS)

    Rotbard, G.; Vergnes, M.; Berrier-Ronsin, G.; Vernotte, J.

    1979-01-01

    The (α,p) reaction at 26 MeV has been used to study 73 Ga and 79 As with 12 keV resolution (FWHM). The reaction behaves like a simple proton stripping ('spectator' zero coupled neutron pair) and the characteristic shapes of the angular distributions permit to assign new spins and parities. In 73 Ga: 198 keV (5/2 - ), 1116 keV (1/2 - ), 1494 keV (9/2 + ). In 79 As: g.s (3/2 - ), 233 keV (5/2 - ), 499 keV (1/2 - ), 777 keV (9/2 + ), 1806 keV (9/2 + ), 1891 keV (1/2 - ), 1964 keV (9/2 + ). The observed splitting of the Jsup(π)=3/2 - strength in 73 Ga, important as compared to the one observed in 71 Ga, is attributed to a change of structure between N=40 and 42

  11. Triaxial shapes in the ground states of even-even neutron-rich Ru isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, I.; Lister, C.J.; Morss, L.R. [and others

    1995-08-01

    Partial level schemes for {sup 108,110,112}Ru, and {sup 114}Ru about which nothing was previously known, were determined from the measurement of prompt, triple-gamma coincidences in {sup 248}Cm fission fragments. A 5-mg {sup 249}Cm source, mixed with 65-mg KCl and pressed in the form of a 7-mm diameter pellet, was used for the experiment. Prompt {gamma} rays emitted from the fission fragments were detected with the Eurogam array at Daresbury, which at that time consisted of 45 Compton suppressed Ge detectors and 5 LEPS spectrometers. Transitions in Ru were identified by gating on {gamma} rays in the complementary Te fragments. Figure I-25 shows the technique used to identify the previously unknown transitions in {sup 114}Ru and its partial level scheme. High spin states up to spin 10 h were observed and the {gamma}-ray branching ratios were determined. The ratios of electric quadrupole transition probabilities deduced from the experimental branching ratios were found to be in good agreement with the predictions of a simple model of rigid triaxial rotor. Our analysis shows that gamma deformation in Ru isotopes is increasing with the neutron number and the gamma value for {sup 112}Ru and {sup 114}Ru is {approximately} 25 degrees. This is one of the highest gamma values encountered in nuclei, suggesting soft triaxial shapes for {sup 112}Ru and {sup 114}Ru. The results of this investigation were published.

  12. Precision mass measurements of neutron-rich Co isotopes beyond N =40

    Science.gov (United States)

    Izzo, C.; Bollen, G.; Brodeur, M.; Eibach, M.; Gulyuz, K.; Holt, J. D.; Kelly, J. M.; Redshaw, M.; Ringle, R.; Sandler, R.; Schwarz, S.; Stroberg, S. R.; Sumithrarachchi, C. S.; Valverde, A. A.; Villari, A. C. C.

    2018-01-01

    The region near Z =28 and N =40 is a subject of great interest for nuclear structure studies due to spectroscopic signatures in 68Ni suggesting a subshell closure at N =40 . Trends in nuclear masses and their derivatives provide a complementary approach to shell structure investigations via separation energies. Penning trap mass spectrometry has provided precise measurements for a number of nuclei in this region; however, a complete picture of the mass surfaces has so far been limited by the large uncertainty remaining for nuclei with N >40 along the iron (Z =26 ) and cobalt (Z =27 ) chains because these species are not available from traditional isotope separator online rare isotope facilities. The Low-Energy Beam and Ion Trap Facility at the National Superconducting Cyclotron Laboratory is the first and only Penning trap mass spectrometer coupled to a fragmentation facility and therefore presents the unique opportunity to perform precise mass measurements of these elusive isotopes. Here we present the first Penning trap measurements of Co,6968, carried out at this facility. Some ambiguity remains as to whether the measured values are ground-state or isomeric-state masses. A detailed discussion is presented to evaluate this question and to motivate future work. In addition, we perform ab initio calculations of ground-state and two-neutron separation energies of cobalt isotopes with the valence-space in-medium similarity renormalization group approach based on a particular set of two- and three-nucleon forces that predict saturation in infinite matter. We discuss the importance of these measurements and calculations for understanding the evolution of nuclear structure near 68Ni.

  13. French contribution to the super-heavy nuclei discovery

    International Nuclear Information System (INIS)

    Nifenecker, H.; Asghar, M.

    1999-01-01

    The research on super-heavy nuclei is a science in full operation for which the Berkeley physicist give proof of perseverance. The author wonders about the french absence in this domain. He recalls the strategical decisions concerning the research programs of the period and gives outline of the future with the interest of the ECR (Electronic Cyclotron Resonance) sources. (A.L.B.)

  14. Dynamics of light, intermediate, heavy and superheavy nuclear ...

    Indian Academy of Sciences (India)

    2014-05-01

    May 1, 2014 ... Various features related to the dynamics of competing decay modes of nuclear systems are explored by addressing the experimental data of a number of reactions in light, intermediate, heavy and superheavy mass regions. The DCM, being a non-statistical description for the decay of a com- pound nucleus ...

  15. Salam-Weinberg symmetry breaking with superheavy Higgs particles

    International Nuclear Information System (INIS)

    Misra, S.P.

    1986-09-01

    We discuss here the possibility of the breaking of the Salam-Weinberg symmetry by Higgs particles which are superheavy. The symmetry-breaking is associated with a nonzero vacuum expectation value of fermion condensates. This mechanism, if operative in nature, will imply the absence of Higgs particles at the weak scale. (author)

  16. The extension of the Periodic System: superheavy - superneutronic

    Energy Technology Data Exchange (ETDEWEB)

    Greiner, W [Frankfurt Institute for Advanced Studies, J.W.Goethe University (Germany); Zagrebaev, V [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation)

    2009-12-31

    Nuclear reactions leading to formation of new superheavy elements and isotopes are discussed. The scope and limitations of different nuclear reactions ('cold' and 'hot' synthesis, fusion of fission fragments, transfer reactions and reactions with radioactive ion beams) are analyzed, trying to find most promising reactions which may be used at available facilities.

  17. Projectile fragmentation of neutron-rich nuclei on light target (momentum distribution and nucleon-removal cross section)

    International Nuclear Information System (INIS)

    Kobayashi, T.; Tanihata, I.; Suzuki, T.

    1992-01-01

    Transverse momentum distributions of the projectile fragments from β-unstable nuclei have been measured with various projectile and target combinations. The momentum correlation of two neutrons in the neutron halo is extracted from the P c t distribution of 9 Li and hat of the neutrons. It is found that the two neutrons are moving in the same direction on average and thus strongly suggests the formation of a di-neutron in 11 Li. (Author)

  18. Spes: An intense source of Neutron-Rich Radioactive Beams at Legnaro

    Science.gov (United States)

    Andrighetto, A.; Manzolaro, M.; Corradetti, S.; Scarpa, D.; Monetti, A.; Rossignoli, M.; Ballan, M.; Borgna, F.; D'Agostini, F.; Gramegna, F.; Prete, G.; Meneghetti, G.; Ferrari, M.; Zenoni, A.

    2018-02-01

    The Isotope Separation On-Line (ISOL) method for the production of Radioactive Ion Beams (RIB) is attracting significant interest in the worldwide nuclear physics community. Within this context the SPES (Selective Production of Exotic Species) RIB facility is now under construction at INFN LNL (Istituto Nazionale di Fisica Nucleare Laboratori Nazionali di Legnaro). This technique is established as one of the main techniques for high intensity and high quality beams production. The SPES facility will produce n-rich isotopes by means of a 40 MeV proton beam, emitted by a cyclotron, impinging on a uranium carbide multi-foil fission target. The aim of this work is to describe the most important results obtained by the study of the on-line behavior of the SPES production target assembly. This target system will produce RIBs at a rate of about 1013 fissions per second, it will be able to dissipate a total power of up to 10 kW, and it is planned to work continuously for 2 week-runs of irradiation. ISOL beams of 24 different elements will be produced, therefore a target and ion source development is ongoing to ensure a great variety of produced isotopes and to improve the beam intensity and purity.

  19. Fusion-fission dynamics and synthesis of the superheavy elements

    International Nuclear Information System (INIS)

    Abe, Yasuhisa

    2003-01-01

    Experiments of fusion-fission reactions clarify that the life time of nuclear fission is much longer than that expected from Bohr-Wheeler formula from the measurements of multiplicities of neutrons, gamma rays etc. emitted prior scission, and thereby appear to require a dynamical treatment of the process. Following the pioneering work by Kramers with the dissipation- fluctuation dynamics, the fissioning degree of freedom is described with the viewpoint of Brownian motion under incessant interactions with the heat bath particles, i.e., with nucleons in thermal equilibrium, in the present case. In the dynamical description the fission width is no more constant in time, but has a transient feature, as well as the reduction factor, the so-called Kramers factor. Both result in a longer life time, consistent with anomalous multiplicities measured. In the fusion process, Coulomb barriers play a crucial role in lighter heavy ion systems, but in very heavy systems it is known that there exists a hindrance in fusion. That is, the Coulomb barrier is not enough for determination of fusion probability, but an extra-energy above the barrier height is required for the system to fuse. This is understood by the properties of the Liquid Drop Model. After overcoming the Coulomb barrier, the ions touch with each other. But the united system, i.e., the pear-shaped configuration is located outside of the conditional saddle point or of the ridgeline. Therefore, in order to form the spherical compound nucleus, the system has to overcome one more barrier. Naturally, in such a situation, the kinetic energy carried in by the incident projectile has been more or less dissipated, i.e., the composite system is heated up. Thus, the shape evolution toward the spherical shape or toward the re-separation can be considered as a Brownian motion with the heat bath inside. The present author et al. have proposed the two-step model for fusion of massive heavy-ion systems where the fusion probability is

  20. Recent searches for superheavy elements in deep-inelastic reactions

    International Nuclear Information System (INIS)

    Hulet, E.K.; Lougheed, R.W.; Nitschke, J.M.

    1980-10-01

    New attempts have been made to synthesize superheavy elements (SHE) by nuclear reactions that may possibly form the products at low excitation energies. Survival of the superheavy elements would then be enhanced because of reduced losses from prompt fission. Classical and diffusion-model calculations of deep-inelastic reactions indicate there should be detectable yields of SHE formed with less than 30 MeV of excitation energy. Accordingly, superheavy elements have been sought in such reactions where targets of 248 Cm and 238 U have been irradiated with 136 Xe and 238 U ions. In the most recent experiments, targets of 248 Cm metal (3.5 to 7 mg-cm -2 ) were bombarded with 1.8-GeV 238 U ions from the UNILAC accelerator. The longer-lived SHE and actinides near the target Z were chemically separated, and the yields of a number of isotopes of Bk, Cf, Es, and Fm were measured. An upper limit of 30 nb was obtained for the formation of 1-h 259 No. In addition to the off-line chemical recovery and search for SHE, an on-line experiment was performed to detect volatile SHE with half-lives of a minute or more. All experiments to produce and detect superheavy elements were much less than optimum because of premature failures in the Cm-metal targets. The outcome and status of these experiments and the implications of the actinide yields in estimating the chances for forming superheavy elements in the 248 Cm + 238 U reactions are discussed. 5 figures, 1 table

  1. Schottky mass measurements of heavy neutron-rich nuclides in the element range $70\\leq Z\\leq 79$ at the ESR

    CERN Document Server

    Shubina, D; Litvinov, Yu A; Blaum, K; Brandau, C; Bosch, F; Carroll, J J; Casten, R F; Cullen, D M; Cullen, I J; Deo, A Y; Detwiler, B; Dimopoulou, C; Farinon, F; Geissel, H; Haettner, E; Heil, M; Kempley, R S; Kozhuharov, C; Knobel, R; Kurcewicz, J; Kuzminchuk, N; Litvinov, S A; Liu, Z; Mao, R; Nociforo, C; Nolden, F; Patyk, Z; Plass, W R; Prochazka, A; Reed, M W; Sanjari, M S; Scheidenberger, C; Steck, M; Stohlker, Th; Sun, B; Swan, T P D; Trees, G; Walker, P M; Weick, H; Winckler, N; Winkler, M; Woods, P J; Yamaguchi, T; Zhou, C

    2013-01-01

    Storage-ring mass spectrometry was applied to neutron-rich $^{197}$Au projectile fragments. Masses of $^{181,183}$Lu, $^{185,186}$Hf, $^{187,188}$Ta, $^{191}$W, and $^{192,193}$Re nuclei were measured for the first time. The uncertainty of previously known masses of $^{189,190}$W and $^{195}$Os nuclei was improved. Observed irregularities on the smooth two-neutron separation energies for Hf and W isotopes are linked to the collectivity phenomena in the corresponding nuclei.

  2. New neutron-rich isotopes in the scandium-to-nickel region, produced by fragmentation of a 500 MeV/u 86Kr beam

    International Nuclear Information System (INIS)

    Weber, M.; Geissel, H.; Keller, H.; Magel, A.; Muenzenberg, G.; Nickel, F.; Pfuetzner, M.; Piechaczek, A.; Roeckl, E.; Rykaczewski, K.; Schall, I.; Suemmerer, K.; Donzaud, C.; Guillemaud-Mueller, D.; Mueller, A.C.; Stephan, C.; Tassan-Got, L.; Dufour, J.P.; Pravikoff, M.; Grewe, A.; Voss, B.; Vieira, D.J.

    1991-10-01

    We have measured production cross-sections of the new neutron-rich isotopes 58 Ti, 61 V, 63 Cr, 66 Mn, 69 Fe, 71 Co and neighbouring isotopes that have been identified as projectile fragments from reactions between a 500 MeV/u 86 Kr beam and a beryllium target. The isotope identification was performed with the zero-degree magnetic spectrometer FRS at GSI, using in addition time-of-flight and energy-loss mesurements. The experimental production cross-sections for the new nuclides and neighbouring isotopes are compared with an empirical parameterization. The resulting prospects for reaching even more neutron-rich isotopes, such as the doubly-magic nuclide 78 Ni, are discussed. (orig.)

  3. Neutron-rich rare isotope production from projectile fission of heavy beams in the energy range of 20 MeV/nucleon

    OpenAIRE

    Vonta, N.; Souliotis, G. A.; Loveland, W. D.; Kwon, Y. K.; Tshoo, K.; Jeong, S. C.; Veselsky, M.; Bonasera, A.; Botvina, A.

    2016-01-01

    We investigate the possibilities of producing neutron-rich nuclides in projectile fission of heavy beams in the energy range of 20 MeV/nucleon expected from low-energy facilities. We report our efforts to theoretically describe the reaction mechanism of projectile fission following a multinucleon transfer collision at this energy range. Our calculations are mainly based on a two-step approach: the dynamical stage of the collision is described with either the phenomenological Deep-Inelastic Tr...

  4. A systematic study of band structure and electromagnetic properties of neutron rich odd mass Eu isotopes in the projected shell model framework

    Energy Technology Data Exchange (ETDEWEB)

    Pandit, Rakesh K.; Devi, Rani [University of Jammu, Department of Physics and Electronics, Jammu (India); Khosa, S.K. [Central University of Jammu, Department of Physics and Astronomical Sciences, Jammu (India); Bhat, G.H.; Sheikh, J.A. [University of Kashmir, Department of Physics, Srinagar (India)

    2017-10-15

    The positive and negative parity rotational band structure of the neutron rich odd mass Eu isotopes with neutron numbers ranging from 90 to 96 are investigated up to the high angular momentum. In the theoretical analysis of energy spectra, transition energies and electromagnetic transition probabilities we employ the projected shell model. The calculations successfully describe the formation of the ground and excited band structures from the single particle and multi quasiparticle configurations. Calculated excitation energy spectra, transition energies, exact quantum mechanically calculated B(E2) and B(M1) transition probabilities are compared with experimental data wherever available and a reasonably good agreement is obtained with the observed data. The change in deformation in the ground state band with the increase in angular momentum and the increase in neutron number has also been established. (orig.)

  5. Shape coexistence in the N=19 neutron-rich nucleus 31Mg explored by β–γ spectroscopy of spin-polarized 31Na

    Directory of Open Access Journals (Sweden)

    H. Nishibata

    2017-04-01

    Full Text Available The structure of excited states in the neutron-rich nucleus 31Mg, which is in the region of the “island of inversion” associated with the neutron magic number N=20, is studied by β–γ spectroscopy of spin-polarized 31Na. Among the 31Mg levels below the one neutron separation energy of 2.3 MeV, the spin values of all five positive-parity levels are unambiguously determined by observing the anisotropic β decay. Two rotational bands with Kπ=1/2+ and 1/2− are proposed based on the spins and energies of the levels. Comparison on a level-by-level basis is performed between the experimental results and theoretical calculations by the antisymmetrized molecular dynamics (AMD plus generator coordinate method (GCM. It is found that various nuclear structures coexist in the low excitation energy region in 31Mg.

  6. Study of the tensor correlation in a neutron-rich sd-shell region with the charge- and parity-projected Hartree-Fock method

    International Nuclear Information System (INIS)

    Sugimoto, Satoru; Toki, Hiroshi; Ikeda, Kiyomi

    2008-01-01

    We study the effect of the tensor force on nuclear structure with mean-field and beyond-mean-field methods. An important correlation induced by the tensor force is two-particle-two-hole (2p2h) correlation, which cannot be treated with a usual mean-filed method. To treat the 2p2h tensor correlation, we develop a new framework (charge- and parity-projected Hartree-Fock (CPPHF) method), which is a beyond-mean-field method. In the CPPHF method, we introduce single-particle states with parity and charge mixing. The parity and charge projections are performed on a total wave function before variation. We apply the CPPHF method to oxygen isotopes including neutron-rich ones. The potential energy from the tensor force has the same order of magnitude with that from the LS force and becomes smaller with neutron number, which indicates that excess neutrons do not contribute to the 2p2h tensor correlation significantly. We also study the effect of the tensor force on spin-orbit-splitting (ls-splitting) in a neutron-rich fluorine isotope 23 F. The tensor force reduces the ls-splitting for the proton d-orbits by about 3 MeV. This effect is important to reproduce the experimental value. We also find that the 2p2h tensor correlation does not affect the ls-splitting in 23 F

  7. Measurement of ground state properties of neutron-rich nuclei on the r-process path between the N=50 and N=82 shells

    CERN Multimedia

    2007-01-01

    The evolution of the unknown ground-state ${\\beta}$-decay properties of the neutron-rich $^{84-89}$Ge, $^{90-93}$Se and $^{102-104}$Sr isotopes near the r-process path is of high interest for the study of the abundance peaks around the N=50 and N=82 neutron shells. At ISOLDE, beams of certain elements with sufficient isotopic purity are produced as molecular sidebands rather than atomic beams. This applies e.g, to germanium, separated as GeS$^{+}$, selenium separated as SeCO$^{+}$ and strontium separated as SrF$^{+}$. However, in case of neutron-rich isotopes produced in actinide targets, new "isobaric" background of atomic ions appears on the mass of the molecular sideband. For this particular case, the ECR charge breeder, positioned in the experimental hall after ISOLDE first mass separation, can be advantageously used as a purification device, by breaking the molecules and removing the molecular contaminants. This proposal indicates our interest in the study of basic nuclear structure properties of neutron...

  8. Coulomb excitation of neutron-rich nuclei between the N=40 and N=50 shell gaps using REX-ISOLDE and the Ge MINIBALL array

    CERN Multimedia

    2002-01-01

    We propose to perform Coulomb excitation experiments of neutron-rich nuclei in the vicinity of $^{68}$Ni towards $^{78}$Ni using the REX-ISOLDE facility coupled with the highly efficient MINIBALL array. Major changes in the structure of the atomic nucleus are expected around the N = 40 subshell closure. Recent B(E2) measurements suggested that $^{68}$Ni behaves like a doubly magic nucleus while neutron-rich Zn isotopes with N>38 exhibit a sudden increase of B(E2) values which may be the signature of deformation. We would like to check and test these predictions for neutron-rich nuclei in the vicinity of N = 40 and N = 50 shell closures like $^{72}$Zn, $^{74}$Zn, $^{76}$Zn, $^{68}$Ni, $^{70}$Ni. Our calculations show that an energy upgrade from 2.2 to 3 MeV/nucleon will be of crucial importance for a part of our study while some nuclei can still be very efficiently studied at an energy of 2.2 MeV/nucleon. Therefore, to perform our experiment in an efficient way, we request 21 shifts of beam time before the ene...

  9. Capture and dissipation in the superheavy region

    Energy Technology Data Exchange (ETDEWEB)

    Materna, T. E-mail: tmaterna@ulb.ac.be; Aritomo, Y.; Amar, N.; Bogatchev, A.; Bouchat, V.; Dorvaux, O.; Giardina, G.; Grevy, S.; Hanappe, F.; Itkis, I.; Jandel, M.; Knyajeva, G.; Kliman, J.; Kozulin, E.; Kondratiev, N.; Krupa, L.; Peter, J.; Prokhorova, E.; Pokrovsky, I.; Schmitt, C.; Stuttge, L.; Voskresensky, V

    2004-04-05

    The competition between fusion-fission and quasi-fission in the reactions {sup 48}Ca+{sup 208}Pb and {sup 48}Ca+{sup 244}Pu(E* = 40MeV) is investigated using the pre-scission neutron multiciplicity distributions (PSNMD) obtained with a new analysis protocol.

  10. Fission dynamics of superheavy nuclei formed in uranium induced reactions

    International Nuclear Information System (INIS)

    Gurjit Kaur; Sandhu, Kirandeep; Sharma, Manoj K.

    2017-01-01

    The compound nuclear system follows symmetric fission if the competing processes such as quasi-elastic, deep inelastic, quasi-fission etc are absent. The contribution of quasi fission events towards the fusion-fission mechanism depends on the entrance channel asymmetry of reaction partners, deformations and orientations of colliding nuclei beside the dependence on energy and angular momentum. Usually the 209 Bi and 208 Pb targets are opted for the production of superheavy nuclei with Z CN =104-113. The nuclei in same mass/charge range can also be synthesized using actinide targets + light projectiles (i.e. asymmetric reaction partners) via hot fusion interactions. These actinide targets are prolate deformed which prefer the compact configurations at above barrier energies, indicating the occurrence of symmetric fission events. Here an attempt is made to address the dynamics of light superheavy system (Z CN =104-106), formed via hot fusion interactions involving actinide targets

  11. Boiling points of the superheavy elements 117 and 118

    International Nuclear Information System (INIS)

    Takahashi, N.

    2001-01-01

    It has been shown that the relativistic effect on the electrons reveal in the heavy element region. What kind of changes will appear in the heavy elements because of the relativistic effects? Can we observe the changes? We observed that the boiling points of astatine and radon are lower than that extrapolated values from lighter elements in the same groups. Systematic behavior of the elements on the boiling point was examined and a new method for the estimation of the boiling points of the superheavy elements in the halogen and rare gases has been found. The estimated values of the elements 117 and 118 are 618 and 247 K, respectively which are considerably lower than those obtained until now. If these values are correct the production of the superheavy elements with heavy ions reaction may be affected. Further, the chemical properties may be fairly different from the lighter elements. (author)

  12. Superheavy Elements and Beyond: - Supercritical Coulomb Field and Giant Quasiatoms

    International Nuclear Information System (INIS)

    Greiner, Walter

    2007-01-01

    The status of theory of Superheavy Nuclei is reviewed. Based with the Two-Center Shell Model Potential Energy Surfaces are calculated. Fusion, fission, quasifission and other processes are discussed. I particular time-delay during the formation of giant quasi atoms/molecules will be crucial for observing the change of the Dirac vacuum in supercritical Coulomb fields by spontaneous positron emission. It will be shown how the various phenomena are interrelated

  13. Structural and decay properties of Z = 132, 138 superheavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Rather, Asloob A.; Ikram, M.; Usmani, A.A. [Aligarh Muslim University, Department of Physics, Aligarh (India); Kumar, Bharat; Patra, S.K. [Institute of Physics, Bhubaneswar (India); Homi Bhabha National Institute, Mumbai, Anushakti Nagar (India)

    2016-12-15

    In this paper, we analyze the structural properties of Z = 132 and Z = 138 superheavy nuclei within the ambit of axially deformed relativistic mean-field framework with NL3* parametrization and calculate the total binding energies, radii, quadrupole deformation parameter, separation energies, density distributions. We also investigate the phenomenon of shape coexistence by performing the calculations for prolate, oblate and spherical configurations. For clear presentation of nucleon distributions, the two-dimensional contour representation of individual nucleon density and total matter density has been made. Further, a competition between possible decay modes such as α-decay, β-decay and spontaneous fission of the isotopic chain of superheavy nuclei with Z = 132 within the range 312 ≤ A ≤ 392 and 318 ≤ A ≤ 398 for Z = 138 is systematically analyzed within self-consistent relativistic mean-field model. From our analysis, we inferred that the α-decay and spontaneous fission are the principal modes of decay in majority of the isotopes of superheavy nuclei under investigation apart from β-decay as dominant mode of decay in {sup 318-322}138 isotopes. (orig.)

  14. Predictions on the modes of decay of odd Z superheavy isotopes within the range 105 ≤ Z ≤ 135

    Science.gov (United States)

    Santhosh, K. P.; Nithya, C.

    2018-05-01

    The decay modes of 1051 odd Z superheavy nuclei within the range 105 ≤ Z ≤ 135, and their daughter nuclei are studied by comparing the alpha decay half-lives with the spontaneous fission half-lives. The alpha decay half-lives are calculated using the Coulomb and proximity potential model for deformed nuclei (CPPMDN) proposed by Santhosh et al. (2011) and the spontaneous fission half-lives are obtained with the shell-effect dependent formula of Santhosh et al. (Santhosh and Nithya, 2016). For a theoretical comparison, the alpha decay half-lives are also computed with the Coulomb and proximity potential model (CPPM), Viola-Seaborg-Sobiczewski semi-empirical relation (VSS), Universal curve of Poenaru et al. (UNIV), the analytical formula of Royer, and the Universal decay law of Qi et al. (UDL). The predicted decay modes and half-lives were compared with the available experimental results. The proton and neutron separation energies are calculated to identify those nuclei, which decay through proton and neutron emission. From the entire study of odd Z superheavy elements, it is seen that among 1051 nuclei, 233 nuclei exhibit proton emission and 18 nuclei exhibit neutron emission. 56 nuclei are stable against alpha decay with negative Q value for the decay. 92 nuclei show alpha decay followed by spontaneous fission and 9 nuclei show alpha decay followed by proton emission. 39 nuclei decay through full alpha chain and 595 nuclei decay through spontaneous fission. We hope that the study will be very useful for the future experimental investigations in this field.

  15. Status and prospect of super-heavy nuclei research at IMP

    International Nuclear Information System (INIS)

    Xu Hushan; Sun Zhiyu; Zhan Wenlong; Zhou Xiaohong; Huang Wenxue; Zhang Hongbin; Gan Zaiguo; Li Junqing; Ma Xinwen; Qin Zhi; Xiao Guoqing; Guo Zhongyan; Li Zhihui; Zhang Yuhu; Jin Genming; Huang Tianheng; Hu Zhengguo; Zhang Xueheng; Zheng Chuan; Chinese Academy of Sciences, Beijing

    2006-01-01

    The history and the international status of the super-heavy nuclei synthesis are briefly described. The related research work carried out at the Institute of Modern Physics (IMP) has been reviewed. The prospect of the super-heavy nuclei research at IMP has been introduced. (authors)

  16. On the problem of synthesis of superheavy nuclei. A short historical review on first theoretical predictions

    International Nuclear Information System (INIS)

    Kalinkin, B.N.; Gareev, F.A.

    1999-01-01

    It is shown that it is just Dubna that possesses the priority both in the recent synthesis of a superheavy nucleus with charge Z=114 (Flerov Laboratory of Nuclear Reactions, JINR) and in its theoretical prediction (Bogolyubov Laboratory of Theoretical Physics, JINR) made 33 years ago. Possible sizes of the 'island of stability' of superheavy nuclei are discussed

  17. Q-value effects in the synthesis of superheavy elements

    International Nuclear Information System (INIS)

    Graeger, Reimar

    2010-01-01

    Superheavy elements (Z>or similar 104) only exist due to nuclear shell effects, which stabilize them against spontaneous fission (SF). Theoretical calculations predict these shell stabilization effects to reach a maximum at the closures of the next spherical proton and neutron shells, which are anticipated in the region between Z=114 and Z=126 and at N=184. More recent calculations, that also consider deformed nuclear shapes extended this picture and predicted deformed shell closures at Z=108 and at N=162, creating a region of enhanced stability around 270 Hs, confirmed in recent Hs chemistry experiments by measuring the decay of 270 Hs for the first time. Recently, the formation of deformed doubly-magic 270 Hs in the 4n evaporation channel in the fusion reactions 248 Cm( 26 Mg,4n), 244 Pu( 30 Si,4n), 238 U( 36 S,4n), and 226 Ra( 48 Ca,4n) was studied theoretically using a two-parameter Smoluchowski equation. Simple entrance channel arguments make compound nucleus (CN) formation appear favorable for systems with larger mass asymmetry. However, due to a lower reaction Q value, the reactions 238 U( 36 S,4n) 270 Hs and 226 Ra( 48 Ca,4n) 270 Hs are predicted to have higher cross sections compared to the reactions 248 Cm( 26 Mg,4n) 270 Hs and 244 Pu( 30 Si,4n) 270 Hs. The aim of the research done in the framework of this thesis was to study the influence of the reaction (B-Q)-value on the yield of SHE produced in nuclear fusion reactions. Therefore the most promising reactions 36 S+ 238 U and 48 Ca+ 226 Ra have been investigated and compared with the already measured reaction 26 Mg+ 248 Cm. The reaction 36 S+ 238 U was investigated at two beam energies. One correlated decay chain attributed to 270 Hs was found at E * =51 MeV resulting in a cross section of 0.8 -0.7 +2.6 pb. The reaction 48 Ca+ 226 Ra was investigated at three beam energies. Six correlated decay chains attributed to 270 Hs were detected at E * =40 MeV corresponding to a cross section of 8.3 -3.7 +6.7 pb

  18. Penning-trap mass measurements of the neutron-rich K and Ca isotopes: Resurgence of the N=28 shell strength

    Science.gov (United States)

    Lapierre, A.; Brodeur, M.; Brunner, T.; Ettenauer, S.; Finlay, P.; Gallant, A. T.; Simon, V. V.; Delheij, P.; Lunney, D.; Ringle, R.; Savajols, H.; Dilling, J.

    2012-02-01

    We present Penning-trap mass measurements of neutron-rich 44,47-50K and 49,50Ca isotopes carried out at the TITAN facility at TRIUMF-ISAC. The 44K mass measurement was performed with a charge-bred 4+ ion utilizing the TITAN electron beam ion trap and agrees with the literature. The mass excesses obtained for 47K and 49,50Ca are more precise and agree with the values published in the 2003 Atomic Mass Evaluation (AME’03). The 48,49,50K mass excesses are more precise than the AME’03 values by more than 1 order of magnitude. For 48,49K, we find deviations of 7σ and 10σ, respectively. The new 49K mass excess lowers significantly the two-neutron separation energy at the neutron number N=30 compared with the separation energy calculated from the AME’03 mass-excess values and thus increases the N=28 neutron-shell gap energy at Z=19 by approximately 1 MeV.

  19. Z dependence of the N=152 deformed shell gap: In-beam γ-ray spectroscopy of neutron-rich 245,246Pu

    International Nuclear Information System (INIS)

    Makii, H.; Ishii, T.; Asai, M.; Tsukada, K.; Toyoshima, A.; Ichikawa, S.; Matsuda, M.; Makishima, A.; Kaneko, J.; Toume, H.; Shigematsu, S.; Kohno, T.; Ogawa, M.

    2007-01-01

    We have measured in-beam γ rays in the neutron-rich 246 Pu 152 and 245 Pu 151 nuclei by means of 244 Pu( 18 O, 16 O) 246 Pu and 244 Pu( 18 O, 17 O) 245 Pu neutron transfer reactions, respectively. The γ rays emitted from 246 Pu ( 245 Pu) were identified by selecting the kinetic energy of scattered 16 O ( 17 O) detected by Si ΔE-E detectors. The ground-state band of 246 Pu was established up to the 12 + state. We have found that the shell gap of N=152 is reduced in energy with decreasing atomic number by extending the systematics of the one-quasiparticle energies in N=151 nuclei into those in 245 Pu. This reduction of the shell gap clearly affects the 2 + energy of the ground-state band of 246 Pu

  20. Study of fission barriers in neutron-rich nuclei using the (p,2p) reaction. Status of SAMURAI-experiment NP1306 SAMURAI14

    Energy Technology Data Exchange (ETDEWEB)

    Reichert, Sebastian [TU Munich (Germany); Collaboration: NP1306-SAMURAI14-Collaboration

    2015-07-01

    Violent stellar processes are currently assumed to be a major origin of the elements beyond iron and their abundances. The conditions during stellar explosions lead to the so called r-process in which the rapid capture of neutrons and subsequent β decays form heavier elements. This extension of the nuclei stops at the point when the repulsive Coulomb energy induces fission. Its recycling is one key aspect to describe the macroscopic structure of the r-process and the well known elemental abundance pattern. The RIBF at RIKEN is able to provide such neutron rich heavy element beams and a first test with the primary beam {sup 238}U was performed to understand the response of the SAMURAI spectrometer and detectors for heavy beams. The final goal is the definition of the fission barrier height with a resolution of 1 MeV (in σ) using the missing mass method using (p,2p) reactions in inverse kinematics.

  1. Study of the N=28 shell closure by one neutron transfer reaction: astrophysical application and {beta}-{gamma} spectroscopy of neutron rich nuclei around N=32/34 and N=40; Etude de la fermeture de couche N=28 autour du noyau {sub 18}{sup 46}Ar{sub 28} par reaction de transfert d'un neutron: application a l'astrophysique et Spectroscopie {beta}-{gamma} de noyaux riches en neutrons de N=32/34 et N=40

    Energy Technology Data Exchange (ETDEWEB)

    Gaudefroy, L

    2005-09-15

    The study of the N=28 shell closure has been presented as well as its astrophysical implications. Moreover the structure of neutron rich nuclei around N=32/34 and 40 was studied. The N=28 shell closure has been studied trough the one neutron transfer reaction on {sup 44,46}Ar nuclei. Excitation energies of states in {sup 45,47}Ar nuclei have been obtained, as well as their angular momenta and spectroscopic factors. These results were used to show that N=28 is still a good magic number in the argon isotopic chain. We interpreted the evolution of the spin-orbit partner gaps in terms of the tensor monopolar proton-neutron interaction. Thanks to this latter, we showed it is not necessary to summon up a reduction of the intensity of the spin-orbit force in order to explain this evolution in N=29 isotopes from calcium to argon chains. The neutron capture rates on {sup 44,46}Ar have been determined thanks to the results of the transfer reaction. Their influence on the nucleosynthesis of {sup 46,48}Ca was studied. We proposed stellar conditions to account for the abnormal isotopic ratio observed in the Allende meteorite concerning {sup 46,48}Ca isotopes. The beta decay and gamma spectroscopy of neutron rich nuclei in the scandium to cobalt region has been studied. We showed that beta decay process is dominated by the {nu}f{sub 5/2} {yields} {pi}f{sub 7/2} Gamow-Teller transition. Moreover, we demonstrated that the {nu}g{sub 9/2} hinders this process in the studied nuclei, and influences their structure, by implying the existence of isomers. Our results show that N=34 is not a magic number in the titanium chain and the superior ones. (author)

  2. Total reaction cross sections and neutron-removal cross sections of neutron-rich light nuclei measured by the COMBAS fragment-separator

    Science.gov (United States)

    Hue, B. M.; Isataev, T.; Erdemchimeg, B.; Artukh, A. G.; Aznabaev, D.; Davaa, S.; Klygin, S. A.; Kononenko, G. A.; Khuukhenkhuu, G.; Kuterbekov, K.; Lukyanov, S. M.; Mikhailova, T. I.; Maslov, V. A.; Mendibaev, K.; Sereda, Yu M.; Penionzhkevich, Yu E.; Vorontsov, A. N.

    2017-12-01

    Preliminary results of measurements of the total reaction cross sections σR and neutron removal cross section σ-xn for weakly bound 6He, 8Li, 9Be and 10Be nuclei at energy range (20-35) A MeV with 28Si target is presented. The secondary beams of light nuclei were produced by bombardment of the 22Ne (35 A MeV) primary beam on Be target and separated by COMBAS fragment-separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 200 μm Al was installed. The Bρ of the second section of the fragment-separator was adjusted for measurements in energy range (20-35) A MeV. Two-neutron removal cross sections for 6He and 10Be and one -neutron removal cross sections 8Li and 9Be were measured.

  3. Vacancy enhanced formation and phase transition of Cu-rich precipitates in α - iron under neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Lv, G. C. [Basic Experimental Center of Natural Science, University of Science and Technology Beijing, Beijing, 100083 (China); Corrosion and Protection Center, Key Laboratory of Environmental Fracture (MOE), University of Science and Technology Beijing, Beijing, 100083 (China); Zhang, H. [Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Canada, T6G2V4 (Canada); He, X. F.; Yang, W. [China Institute of Atomic Energy, Beijing, 102413 (China); Su, Y. J., E-mail: yjsu@ustb.edu.cn [Corrosion and Protection Center, Key Laboratory of Environmental Fracture (MOE), University of Science and Technology Beijing, Beijing, 100083 (China)

    2016-04-15

    In this paper, we employed both molecular statics and molecular dynamics simulation methods to investigate the role of vacancies in the formation and phase transition of Cu-rich precipitates in α-iron. The results indicated that vacancies promoted the diffusion of Cu atoms to form Cu-rich precipitates. After Cu-rich precipitates formed, they further trapped vacancies. The supersaturated vacancy concentration in the Cu-rich precipitate induced a shear strain, which triggered the phase transition from bcc to fcc structure by transforming the initial bcc (110) plane into fcc (111) plane. In addition, the formation of the fcc-twin structure and the stacking fault structure in the Cu-rich precipitates was observed in dynamics simulations.

  4. Superheavy Elements: Theoretical Expectations and Related Fundamental Issues

    International Nuclear Information System (INIS)

    Greiner, W.

    2008-01-01

    I discuss the theory for superheavy elements, based on the Two Center Shell Model. Potential energy surfaces, cold valleys, cold fusion, quasi fusion and other processes will be discussed. The experimental results from GSI, Dubna and Japan are presented. Finally, utilizing the theory of mass-exchange in dynamical encounters by Zagrebaev and myself, I will outline the possibility of long time delays of giant molecular/atomic systems (e.g. U + U, U + Cm, etc) and its relevance for observing the supercritical decay of the QED-vacuum

  5. Lifetime measurements in neutron-rich isotopes close to N = 40 and development of a simulation tool for RDDS spectra

    International Nuclear Information System (INIS)

    Braunroth, Thomas Christian

    2017-01-01

    interest are the neutron-rich 59,61 Mn isotopes (Z=25), for which level lifetimes of the 7/2 - 1 , 9/2 - 1 and 11/2 - 1 states were determined (in 61 Mn the assignment is only tentative). In addition, level lifetimes in 63 Mn of the tentatively assigned (7/2 - 1 ) and (9/2 - 1 ) states were evaluated. The results are compared to shell-model calculations using the fp interaction KB3G as well as the state-of-the-art interaction LNPS-m. The present data indicates a structural change close to N=36. The experimental data for 61 Mn suggests that the B(M1) value for the 7/2 - 1 → 5/2 - gs is underestimated by the LNPS-m interaction when free g factors are used. In the second part of this thesis, a tool is presented which allows to generate γ-ray spectra of lifetime studies based on the electromagnetic Doppler-shift using empirical parameters. The tool is highly flexible which enables the incorporation of various experimental bounding conditions. It is applied to investigate the influence of velocity distributions on the lifetime analysis and results indicate that systematic deviations are minimized if distance-dependent mean recoil velocities are taken into account.

  6. Lifetime measurements in neutron-rich isotopes close to N = 40 and development of a simulation tool for RDDS spectra

    Energy Technology Data Exchange (ETDEWEB)

    Braunroth, Thomas Christian

    2017-10-10

    degree of quadrupole deformation. Other isotopes that were produced in the experiment were investigated with respect to the identification of γ-ray transitions and level lifetimes. Of particular interest are the neutron-rich {sup 59,61}Mn isotopes (Z=25), for which level lifetimes of the 7/2{sup -}{sub 1}, 9/2{sup -}{sub 1} and 11/2{sup -}{sub 1} states were determined (in {sup 61}Mn the assignment is only tentative). In addition, level lifetimes in {sup 63}Mn of the tentatively assigned (7/2{sup -}{sub 1}) and (9/2{sup -}{sub 1}) states were evaluated. The results are compared to shell-model calculations using the fp interaction KB3G as well as the state-of-the-art interaction LNPS-m. The present data indicates a structural change close to N=36. The experimental data for {sup 61}Mn suggests that the B(M1) value for the 7/2{sup -}{sub 1} → 5/2{sup -}{sub gs} is underestimated by the LNPS-m interaction when free g factors are used. In the second part of this thesis, a tool is presented which allows to generate γ-ray spectra of lifetime studies based on the electromagnetic Doppler-shift using empirical parameters. The tool is highly flexible which enables the incorporation of various experimental bounding conditions. It is applied to investigate the influence of velocity distributions on the lifetime analysis and results indicate that systematic deviations are minimized if distance-dependent mean recoil velocities are taken into account.

  7. Study of the structure of light neutron rich nucleus with the Tonnerre array; Etude de la structure de noyaux legers riches en neutrons a l'aide du multidetecteur Tonnerre

    Energy Technology Data Exchange (ETDEWEB)

    Pietri, St

    2003-06-01

    This work concern the technical development made on the multidetector TONNERRE and the study of the {sup 34}Si nucleus by a complete beta-neutron-gamma spectroscopy. In the first part various tests performed on modules of the detector in the 'Centre d'Etude de Bruyere le Chatel' are presented. A modification of the embassies of the photomultipliers tubes allows to gain more than 50% in the neutron efficiency and to obtain a threshold lower than 300 keV for the neutron energy. A complete C++ simulation of the neutron propagation in the array was carried out. It explains that the slow component of the light output of the scintillator may be responsible of the shape of the time-of-flight spectrum. The second part of these report presents the experiment devoted to the study of the structure of the {sup 34}Si from the beta decay of the {sup 34}Al. It was performed at the GANIL facility using the TONNERRE array and germanium of ENOGAM. The {sup 34}Al was produced by projectile fragmentation of a {sup 36}S beam of 50 MeV/A in a target of {sup 9}Be. A complete beta scheme of the {sup 34}Al is proposed. Eight neutron lines following the {sup 34}Al decay were observed for the first time. Finally we suggest that a monopolar transition could occur in the {sup 34}Si nucleus signing a O{sup +}{sub 2} state at 2133 keV. (author)

  8. Exploration of (super-)heavy elements using the Skyrme-Hartree-Fock model

    International Nuclear Information System (INIS)

    Erler, Jochen

    2011-01-01

    Motivated by the steadily increasing number of known nuclei and nuclear properties, theories of nuclear structure are presently a field of intense research. This work concentrates on the self-consistent description of nuclei in terms of the Skyrme-Hartree-Fock (SHF) approach. The extrapolation of nuclear shell structure to the region of super-heavy elements (SHE) using the SHF model, the dependence on different parameterization and the influence of collective correlation will be studied. The general scope of this work are large scale calculation for a global survey of properties of SHE like binding energies, separation energies and decay characteristics and lifetimes. These calculations were done in a collaboration with the theory group of the GSI in Darmstadt and have the aim to develop a database of lifetimes and reaction rates for α, β-decay and spontaneous fission in a very wide range with proton numbers 86 ≤ Z ≤ 120 and neutron numbers up to N ∼ 260 relevant for the astrophysical r-process. The results of this study for example predictions of a possible islands of very stable nuclei and information of favored decay mode for each nuclei are also applicable in the recent experimental synthesis of exotic SHE. For these calculation a framework to calculate β-decay half-lives within the SHF model has been developed and the existing axial SHF code has been extended to compute β-transition matrix elements and so to provide an estimation of half-lives. (orig.)

  9. Exploration of (super-)heavy elements using the Skyrme-Hartree-Fock model

    Energy Technology Data Exchange (ETDEWEB)

    Erler, Jochen

    2011-01-31

    Motivated by the steadily increasing number of known nuclei and nuclear properties, theories of nuclear structure are presently a field of intense research. This work concentrates on the self-consistent description of nuclei in terms of the Skyrme-Hartree-Fock (SHF) approach. The extrapolation of nuclear shell structure to the region of super-heavy elements (SHE) using the SHF model, the dependence on different parameterization and the influence of collective correlation will be studied. The general scope of this work are large scale calculation for a global survey of properties of SHE like binding energies, separation energies and decay characteristics and lifetimes. These calculations were done in a collaboration with the theory group of the GSI in Darmstadt and have the aim to develop a database of lifetimes and reaction rates for {alpha}, {beta}-decay and spontaneous fission in a very wide range with proton numbers 86 {<=} Z {<=} 120 and neutron numbers up to N {approx} 260 relevant for the astrophysical r-process. The results of this study for example predictions of a possible islands of very stable nuclei and information of favored decay mode for each nuclei are also applicable in the recent experimental synthesis of exotic SHE. For these calculation a framework to calculate {beta}-decay half-lives within the SHF model has been developed and the existing axial SHF code has been extended to compute {beta}-transition matrix elements and so to provide an estimation of half-lives. (orig.)

  10. New results from isochronous mass measurements of neutron-rich uranium fission fragments with the FRS-ESR-facility at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Knoebel, R.; Litvinov, Yu.A.; Weick, H.; Bosch, F.; Boutin, D.; Dimopoulou, C.; Dolinskii, A.; Franczak, B.; Franzke, B.; Kozhuharov, C.; Kurcewicz, J.; Litvinov, S.A.; Matos, M.; Mazzocco, M.; Muenzenberg, G.; Nociforo, C.; Nolden, F.; Stadlmann, J.; Steck, M.; Winkler, M. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Diwisch, M. [Justus-Liebig-Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Geissel, H.; Plass, W.R.; Scheidenberger, C.; Chen, L. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Justus-Liebig-Universitaet Giessen, II. Physikalisches Institut, Giessen (Germany); Patyk, Z. [National Centre for Nuclear Research - NCBJ Swierk, Warszawa (Poland); Sun, B. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); Hausmann, M. [Michigan State University, East Lansing, MI (United States); Nakajima, S.; Suzuki, T.; Yamaguchi, T. [Saitama University, Department of Physics, Saitama (Japan); Ohtsubo, T. [Niigata University, Department of Physics, Niigata (Japan); Ozawa, A. [University of Tsukuba, Institute of Physics, Ibaraki (Japan); Walker, P.M. [University of Surrey, Department of Physics, Guildford (United Kingdom)

    2016-05-15

    Masses of uranium fission fragments have been measured with the FRagment Separator (FRS) combined with the Experimental Storage Ring (ESR) at GSI. A 410-415 MeV/u {sup 238}U projectile beam was fast extracted from the synchrotron SIS-18 with an average intensity of 10{sup 9}/spill. The projectiles were focused on a 1g/cm{sup 2} beryllium target at the entrance of the FRS to create neutron-rich isotopes via abrasion-fission. The fission fragments were spatially separated with the FRS and injected into the isochronous storage ring ESR for fast mass measurements without applying cooling. The Isochronous Mass Spectrometry (IMS) was performed under two different experimental conditions, with and without B ρ-tagging at the high-resolution dispersive central focal plane of the FRS. The evaluation has been done for the combined data sets from both experiments with a new method of data analysis. The use of a correlation matrix has provided experimental mass values for 23 different neutron-rich isotopes for the first time and 6 masses with improved values. The new masses were obtained for nuclides in the element range from Se to Ce. The applied analysis has given access even to rare isotopes detected with an intensity of a few atoms per week. The novel data analysis and systematic error determination are described and the results are compared with extrapolations of experimental values and theoretical models. (orig.)

  11. Gamma-ray Spectroscopy of Nano-second Isomers in Neutron-rich Ni Region Produced by Deep-inelastic Collisions

    Science.gov (United States)

    Ishii, Tetsuro; Asai, Masato; Kleinheinz, Peter; Matsuda, Makoto; Ichikawa, Shinichi; Makishima, Akiyasu; Ogawa, Masao

    2001-10-01

    We have been studying nuclear structure of neutron-rich nuclei produced by heavy-ion deep-inelastic collisions at the JAERI Tandem Booster facility. In our method using an `isomer-scope', γ-rays only from isomers with T_1/2 > 1ns are measured by shielding Ge detectors from prompt γ rays emitted at the target position. Atomic numbers of isomers can be also identified by detecting projectile-like fragments with Si Δ E-E detectors. Until now, we have found several new isomers in neutron-rich Ni region using about 8 MeV/nucleon ^70Zn, ^76Ge and ^82Se beams and a ^198Pt target of 4.3 mg/cm^2 thickness. In the doubly magic ^68_28Ni_40, the (ν g_9/2^2 ν p_1/2-2)8^+ isomer with T_1/2=23(1) ns was found. In its neighbor nuclei ^69,71Cu, the 19/2^- isomers were found and the energy levels decaying from the isomers can be calculated very accurately by a parameter-free shell model calculation using experimental energy levels as two-body residual interactions. I will also briefly discuss nano-second isomers in ^32,33Si and ^34P produced by 9 MeV/nucleon ^37Cl beams.

  12. ${\\beta}$-decay studies of neutron-rich $^{61-70}$Mn isotopes with the new LISOL ${\\beta}$-decay setup

    CERN Multimedia

    Diriken, J V J

    2008-01-01

    The aim of this proposal is to gather new information that will serve as benchmark to test shell model calculations in the region below $^{68}$Ni, where proper residual interactions are still under development. More specifically, the ${\\beta}$-decay experiment of the $^{61-70}$Mn isotopes will highlight the development of collectivity in the Fe isotopes and its daughters. At ISOLDE, neutron-rich Mn isotopes are produced with a UC$_{x}$ target and selective laser ionization. These beams are particularly pure and reasonable yields are obtained for the neutron-rich short lived $^{61-70}$Mn isotopes. We propose to perform ${\\beta}$-decay studies on $^{61-70}$Mn utilizing the newly-developed "LISOL ${\\beta}$-decay setup", consisting of two MINIBALL cluster Ge detectors and a standard tape station. The use of digital electronics in the readout of these detectors enables us to perform a "slow correlation technique" which should indicate the possible existence of isomers in the daughter nuclei.

  13. System analytical studies on ground state properties of neutron-rich nuclides in the nuclear mass region A ≅ 100

    International Nuclear Information System (INIS)

    Toenhardt, M.

    1987-01-01

    In this thesis only nuclei with even proton and even neutron number have been studied. This constraint allows to use a for the description of excitation spectra very successful model, the interacting boson model (IBM) and to combine this with the density functional method. From the obtained Hamiltonian via an energy-density functional an effective potential is constructed which can be applied in the framework of the density-functional method in order to calculate ground state energies and densities. From the density distributions radii and values for the static deformation are determined. As further ground state property the separation energy for two neutrons is studied. (orig./HSI) [de

  14. Coulomb excitation of neutron-rich$^{28,29,30}$Na nuclei with MINIBALL at REX-ISOLDE: Mapping the borders of the island of inversion

    CERN Multimedia

    Butler, P; Cederkall, J A; Reiter, P; Wiens, A; Blazhev, A A; Kruecken, R; Voulot, D; Kalkuehler, M; Wadsworth, R; Gernhaeuser, R A; Hess, H E; Holler, A; Finke, F; Leske, J; Huyse, M L; Seidlitz, M

    We propose to study the properties of neutron-rich nuclei $^{28,29,30}$Na via Coulomb excitation experiments using the REX-ISOLDE facility coupled with the highly efficient MINIBALL array. Reliable B(E2,0$^{+}$ $\\rightarrow$ 2$^{+}$) values for $^{30,32}$Mg were obtained at ISOLDE. Together with recent new results on $^{31}$Mg, collective and single particle properties are probed for Z=12 at the N=20 neutron closed shell, the 'island of inversion'. We would like to extend this knowledge to the neighbouring $^{28,29,30}$Na isotopes where a different transition from the usual filling of the neutron levels into the region with low lying 2p-2h cross shell configurations is predicted by theory. Detailed theoretical predictions on the transition strength in all three Na nuclei are awaiting experimental verification and are the subject of this proposal. At REX beam energies of 3.0 MeV /nucleon the cross-sections for Coulomb excitation are sufficient. Moreover the results from the close-by $^{30,31,32}$Mg nuclei de...

  15. Search for superheavy elements in the bombardment of 248Cm with 48Ca

    International Nuclear Information System (INIS)

    Hulet, E.K.; Lougheed, R.W.; Wild, J.F.; Landrum, J.H.; Stevenson, P.C.; Ghiorso, A.; Nitschke, J.M.; Otto, R.J.; Morrissey, D.J.; Baisden, P.A.; Gavin, B.F.; Lee, D.; Silva, R.J.; Fowler, M.M.; Seaborg, G.T.

    1977-01-01

    We have searched for superheavy elements 110 to 116 with half-lives between 10 4 and 10 8 s in fractions chemically separated after each of a series of bombardments of 248 Cm made with 267-MeV 48 Ca ions. After 6 months of α and spontaneous-fission counting, our results provide no persuasive evidence for the presence of super-heavy elements. The most plausible explanation for not finding the superheavy elements is that they have either short half-lives or very small formation cross sections

  16. Superheavy element research at the velocity filter ship

    International Nuclear Information System (INIS)

    Heinz, S.

    2012-01-01

    The Separator for Heavy Ion Reaction Products (SHIP) is a velocity filter located at the UNILAC accelerator of GSI Darmstadt, Germany. For about 35 years a broad experimental program in the field of superheavy element research is running at SHIP. During the last years particularly investigations in the region of the heaviest known nuclei were performed. In fusion reactions of 48 Ca + 248 Cm → 296 116* a total of six decay chains was observed which could be attributed to the evaporation residues 292 116 and 293 116. In this experiment, data measured previously on the same isotopes in Dubna were well confirmed. Besides, two attempts were made to synthesize isotopes of the still unobserved element Z = 120 in reactions of 64 Ni + 238 U and 54 Cr + 248 Cm. No events were observed in these experiments leading to one-event cross-section limits of 90 fb and 560 fb, respectively. For future superheavy element research, a new superconducting continuous wave LINAC is planned at GSI which shall deliver beam intensities of up to 1014 particles per second. In this context we are developing a next generation separator and new detection techniques

  17. Half-life predictions for decay modes of superheavy nuclei

    International Nuclear Information System (INIS)

    Duarte, S.B.; Tavares, O.A.P.; Goncalves, M.; Rodriguez, O.; Guzman, F.; Barbosa, T.N.; Garcia, F.; Dimarco, A.

    2004-09-01

    We applied the Effective Liquid Drop Model (ELDM) to predict the alpha-decay, cluster emission and cold fission half-life-values of nuclei in the region of Superheavy Elements (SHE). The present calculations have been made in the region of the ZN-plane defined by 155 <=N <=220 and 110<=Z<=135. Shell effects are included via the Q-value of the corresponding decay case. We report the results of a systematic calculation of the half-life for the three nuclear decay modes in a region of the ZN-plane where superheavy elements are expected to be found. Results have shown that, among the decay modes investigated here, the alpha decay is the dominant one. i.e, the decay mode of smallest half-lives. Half-life predictions for alpha decay, cluster emission and cold fission for the isotopic family of the most recent SHE detected of Z=115 and for the isotopic family of the already consolidated SHE of Z=111 are presented. (author)

  18. Neutron-capture reactions by stable and unstable neutron-rich nuclei and their relevance for nucleosynthesis in hot and explosive astrophysical scenarios

    International Nuclear Information System (INIS)

    Hofinger, R.

    1997-10-01

    This thesis deals on the one hand with neutron-capture reactions by carbon-, nitrogen-, oxygen- and sulfur-isotopes, and on the other hand with the two-step processes 4 He(2n, γ) 6 He and 9 Li(2n, γ) 11 Li. Some of the involved carbon-, nitrogen- and oxygen-isotopes possess neutron-halos characterized by the unexpected large radial extension of the nuclear matter density distribution. Special attention is paid to the halo properties in the calculation of the direct neutron capture cross section. For the determination of the nuclear structure, models are used, when no experimental information is available. The results for the reaction rates are compared to previously used rates. The rates obtained in this work are partly orders of magnitude higher than the previously used reaction rates. The reaction rates for the two-step processes are on the one hand calculated assuming a two-step process, on the other hand from genuine three-body models for the process of photodisintegration of the nuclei 6 He and 11 Li. It turns out that the calculations assuming a trio-step process underestimate the reaction rates by orders of magnitude. The influence of the reaction rate for the reaction 4 He(2n, γ) 6 He and the formation of 12 C is examined in a nuclear reaction network under conditions which are typical for the α- process in supernovae of type II. It turns out that under these conditions the influence of the reaction 4 He(2n, γ) 6 He is negligible on the formation of 12 C. (author)

  19. Microscopic description of the competition between spontaneous fission and α -decay in neutron-rich Ra, U and Pu nuclei

    International Nuclear Information System (INIS)

    Rodríguez-Guzmán, R; Robledo, L M

    2017-01-01

    Constrained mean-field calculations, based on the Gogny-D1M energy density functional, have been carried out to describe fission in Ra, U and Pu nuclei with neutron number 144 ≤ N ≤ 176. Fission paths, collective masses and zero-point quantum vibrational and rotational corrections are used to compute the spontaneous fission half-lives. We also pay attention to isomeric states along the considered fission paths. Alpha decay half-lives have also been computed using a parametrization of the Viola-Seaborg formula. Though there exists a strong variance of the predicted fission rates with respect to the details involved in their computation a robust trend is obtained indicating, that with increasing neutron number fission dominates over α -decay. Our results also suggest that a dynamical treatment of pairing correlations is required within the microscopic studies of the fission process in heavy nuclear systems. (paper)

  20. Seal coat damage evaluation due to superheavy load moves based on a mechanistic-empirical approach.

    Science.gov (United States)

    2010-03-01

    The number of superheavy load (SHL) moves has increased drastically within the past 5 years in : Texas. Along with the increasing SHL moves, the Texas Department of Transportation (TxDOT) has : become increasingly aware of the rising concerns associa...

  1. Upper Limit of the Periodic Table and Synthesis of Superheavy Elements

    Directory of Open Access Journals (Sweden)

    Khazan A.

    2007-04-01

    Full Text Available For the first time, using the heaviest possible element, the diagram for known nuclides and stable isotopes is constructed. The direction of search of superheavy elements is indicated. The Periodic Table with an eighth period is tabulated.

  2. Deep inelastic reactions and isomers in neutron-rich nuclei across the perimeter of the A = 180 - 190 deformed region

    International Nuclear Information System (INIS)

    Dracoulis, G.D.; Lane, G.J.; Byrne, A.P.; Watanabe, H.; Hughes, R.O.; Kondev, F.G.; Carpenter, M.P.; Janssens, R.V.F.; Lauritsen, T.; Lister, C.J.; Seweryniak, D.; Zhu, S.; Chowdhury, P.; Shi, Y.; Xu, F.R.

    2014-01-01

    Recent results on high-spin isomers populated in deep-inelastic reactions in the transitional tungsten-osmium region are outlined with a focus on 190 Os, 192 Os and 194 Os. As well as the characterization of several two-quasineutron isomers, the 12 + and 20 + isomers in 192 Os are interpreted as manifestations of maximal rotation alignment within the neutron i(13/2) and possibly proton h(11/2) shells at oblate deformation. (authors)

  3. New semi-empirical formula for α-decay half-lives of the heavy and superheavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Manjunatha, H.C. [Government College for Women, Department of Physics, Kolar, Karnataka (India); Sridhar, K.N. [Government First Grade College, Department of Physics, Kolar, Karnataka (India)

    2017-07-15

    We have succesfully formulated the semi-empirical formula for α-decay half-lives of heavy and superheavy nuclei for different isotopes of the wide atomic-number range 94 < Z < 136. We have considered 2627 isotopes of heavy and superheavy nuclei for the fitting. The value produced by the present formula is compared with that of experiments and other eleven models, i.e. ImSahu, Sahu, Royer10, VS2, UNIV2, SemFIS2, WKB. Sahu16, Densov, VSS and Royer formula. This formula is exclusively for heavy and superheavy nuclei. α-decay is one of the dominant decay mode of superheavy nucleus. By identifying the α-decay mode superheavy nuclei can be detected. This formula helps in predicting the α-decay chains of superheavy nuclei. (orig.)

  4. The Transplutonium. The superheavy nuclei found in the micas of Madagascar and their interests

    International Nuclear Information System (INIS)

    Raoelina Andriambololona

    1976-01-01

    Since June 1976, evidence for the existence of superheavy elements is discussed about. After having recalled artificial elements with atomic numbers Z of wich go from Z=95 (Americium) to Z=107 (built in 1976), superheavy elements having Z greater than 110 are considered. They have been discovered by american searchers in giant halos seen in Madagascar micas. The samples have been recoked in the Fort-Dauphin region (Haut Mandrare). The corresponding numbers Z are 114, 115, 116, 124, 125, 125, 126, 127. It seems that the existence of Z=126 element should be accepted with a greater degree of confidence. But different experiences done by other groups seem to show the evidence of superheavy elements in micas looks weaker. Nevertheless, it is interesting to investigate the evidence or the non-evidence of those elements. We estimate the mass numbers A of those superheavy elements in the liquid drop model if we assume that they are stable versus β. The results thus obtained agree with the shell-model ones within 4 % approximation. We propose if the evidence of superheavies is confirmed to give the name of madagascarium to one of them (Z=126) by similitude with francium, lutetium, polonium, berkelium, americium, europium, ...Their evidence was first conjectured in Madagascar micas in 1976. Superheavy nuclei are to be distinguished from hypernuclei. [fr

  5. Mean free paths and in-medium scattering cross sections of energetic nucleons in neutron-rich nucleonic matter within the relativistic impulse approximation

    International Nuclear Information System (INIS)

    Jiang Weizhou; Li Baoan; Chen Liewen

    2007-01-01

    The mean free paths and in-medium scattering cross sections of energetic nucleons in neutron-rich nucleonic matter are investigated using the nucleon optical potential obtained within the relativistic impulse approximation with the empirical nucleon-nucleon scattering amplitudes and the nuclear densities obtained in the relativistic mean-field model. It is found that the isospin-splitting of nucleon mean free paths, sensitive to the imaginary part of the symmetry potential, changes its sign at certain high kinetic energy. The in-medium nucleon-nucleon cross sections are analytically and numerically demonstrated to be essentially independent of the isospin asymmetry of the medium and increase linearly with density in the high-energy region where the relativistic impulse approximation is applicable

  6. First observation of the beta decay of neutron-rich $^{218}Bi$ by the pulsed-release technique and resonant laser ionization

    CERN Document Server

    De Witte, H; Borzov, I N; Caurier, E; Cederkäll, J; De Smet, A; Eckhaudt, S; Fedorov, D V; Fedosseev, V; Franchoo, S; Górska, M; Grawe, H; Huber, G; Huyse, M; Janas, Z; Köster, U; Kurcewicz, W; Kurpeta, J; Plochocki, A; Van Duppen, P; Van de Vel, K; Weissman, L

    2004-01-01

    The neutron-rich isotope /sup 218/Bi has been produced in proton- induced spallation of a uranium carbide target at the ISOLDE facility at CERN, extracted from the ion source by the pulsed-release technique and resonant laser ionization, and its beta decay is studied for the first time. A half-life of 33(1)s was measured and is discussed in the self-consistent continuum-quasi particle-random- phase approximation framework that includes Gamow-Teller and first- forbidden transitions. A level scheme was constructed for /sup 218 /Po, and a deexcitation pattern of stretched E2 transitions 8/sup +/ to 6/sup +/ to 4/sup +/ to 2/sup +/ to 0/sup +/ to the ground state is suggested. Shell-model calculations based on the Kuo-Herling interaction reproduce the experimental results satisfactorily. (28 refs).

  7. β-decay half-lives of neutron-rich isotopes of Fe, Co, Ni involved in the beginning of the r-process

    International Nuclear Information System (INIS)

    Czajkowski, S.; Bernas, M.; Brissot, R.

    1992-01-01

    The very neutron-rich Fe- to Ni-isotopes are of interest since they are located at the very beginning of the astrophysical r-process path. The β-decay half-lives of several isotopes, identified in thermal fission of 235 U or 239 Pu, have been measured at the ILL high-flux reactor using the Lohengrin spectrometer. Half-lives have been determined from time-correlations analysis between the fragment implantation and the detection of the subsequent β-particles in the same detector. With the fragment separator FRS , at GSI, the projectile fragments of 86 Kr have been separated. The β-decay half-life of 65 Fe has been measured. Received: (from VMMAIL[FRSAC11 for XIN[IAEA1 via NJE)

  8. Discovery and cross-section measurement of neutron-rich isotopes in the element range from neodymium to platinum with the FRS

    International Nuclear Information System (INIS)

    Kurcewicz, J.; Farinon, F.; Geissel, H.; Pietri, S.; Nociforo, C.; Prochazka, A.; Weick, H.; Winfield, J.S.; Estradé, A.; Allegro, P.R.P.; Bail, A.; Bélier, G.; Benlliure, J.; Benzoni, G.; Bunce, M.; Bowry, M.; Caballero-Folch, R.

    2012-01-01

    Using the high-resolution performance of the fragment separator FRS at GSI we have discovered 60 new neutron-rich isotopes in the atomic number range of 60⩽Z⩽78. The new isotopes were unambiguously identified in reactions with a 238 U beam impinging on a Be target at 1 GeV/nucleon. The production cross-section for the new isotopes have been measured down to the pico-barn level and compared with predictions of different model calculations. For elements above hafnium fragmentation is the dominant reaction mechanism which creates the new isotopes, whereas fission plays a dominant role for the production of the new isotopes up to thulium.

  9. Discovery and cross-section measurement of neutron-rich isotopes in the element range from neodymium to platinum with the FRS

    Energy Technology Data Exchange (ETDEWEB)

    Kurcewicz, J., E-mail: j.kurcewicz@gsi.de [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Farinon, F.; Geissel, H. [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Justus-Liebig-Universitaet Giessen, 35392 Giessen (Germany); Pietri, S.; Nociforo, C. [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Prochazka, A. [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Justus-Liebig-Universitaet Giessen, 35392 Giessen (Germany); Weick, H.; Winfield, J.S. [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Estrade, A. [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); Allegro, P.R.P. [Institute of Physics, Universidade de Sao Paulo, CEP 05508-090 Cidade Universitaria, Sao Paulo (Brazil); Bail, A.; Belier, G. [CEA DAM DiF, 91290 Arpajon Cedex (France); Benlliure, J. [Universidad de Santiago de Compostela, E-15706 Santiago de Compostella (Spain); Benzoni, G. [INFN sezione di Milano, I-20133 Milano (Italy); Bunce, M.; Bowry, M. [Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH (United Kingdom); Caballero-Folch, R. [Universitat Politecnica de Catalunya, 08034 Barcelona (Spain); and others

    2012-10-31

    Using the high-resolution performance of the fragment separator FRS at GSI we have discovered 60 new neutron-rich isotopes in the atomic number range of 60 Less-Than-Or-Slanted-Equal-To Z Less-Than-Or-Slanted-Equal-To 78. The new isotopes were unambiguously identified in reactions with a {sup 238}U beam impinging on a Be target at 1 GeV/nucleon. The production cross-section for the new isotopes have been measured down to the pico-barn level and compared with predictions of different model calculations. For elements above hafnium fragmentation is the dominant reaction mechanism which creates the new isotopes, whereas fission plays a dominant role for the production of the new isotopes up to thulium.

  10. Spectroscopic Quadrupole Moments in {96,98}Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60.

    Science.gov (United States)

    Clément, E; Zielińska, M; Görgen, A; Korten, W; Péru, S; Libert, J; Goutte, H; Hilaire, S; Bastin, B; Bauer, C; Blazhev, A; Bree, N; Bruyneel, B; Butler, P A; Butterworth, J; Delahaye, P; Dijon, A; Doherty, D T; Ekström, A; Fitzpatrick, C; Fransen, C; Georgiev, G; Gernhäuser, R; Hess, H; Iwanicki, J; Jenkins, D G; Larsen, A C; Ljungvall, J; Lutter, R; Marley, P; Moschner, K; Napiorkowski, P J; Pakarinen, J; Petts, A; Reiter, P; Renstrøm, T; Seidlitz, M; Siebeck, B; Siem, S; Sotty, C; Srebrny, J; Stefanescu, I; Tveten, G M; Van de Walle, J; Vermeulen, M; Voulot, D; Warr, N; Wenander, F; Wiens, A; De Witte, H; Wrzosek-Lipska, K

    2016-01-15

    Neutron-rich {96,98}Sr isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations. In particular, a very small mixing between the coexisting states is observed, contrary to other mass regions where strong mixing is present. Experimental results have been compared to beyond-mean-field calculations using the Gogny D1S interaction in a five-dimensional collective Hamiltonian formalism, which reproduce the shape change at N=60.

  11. Study of the elastic scattering and of the (p,n) charge exchange reaction with neutron-rich light exotic beams; Etude de la diffusion elastique et de la reaction d`echange de charge (p,n) avec des faisceaux exotiques legers riches en neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Cortina Gil, D.

    1996-07-05

    We have measured at GANIL, with the high resolution spectrometer SPEG, the elastic scattering of several neutron rich secondary beams ({sup 6}He, {sup 10}Be and {sup 11}Be) on a polypropylene target and the charge exchange reaction p({sup 6}He, {sup 6}Li)n. These exotic beams were produced by nuclear fragmentation and re-focalized with the SISSI device (superconducting solenoids). The signature of a halo structure in these nuclei has been analysed. Special attention has been paid to several aspects of the associated calculations namely, the proton and neutron density distributions and the small binding energy for the last nucleons in these exotic nuclei. Break-up mechanisms are seen to play an important role in these nuclei. 100 refs.

  12. α decay chains in 271-294115 superheavy nuclei

    International Nuclear Information System (INIS)

    Santhosh, K. P.; Priyanka, B.; Joseph, Jayesh George; Sahadevan, Sabina

    2011-01-01

    α decay of 271-294 115 superheavy nuclei is studied using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The predicted α half-lives of 287 115 and 288 115 nuclei and their decay products are in good agreement with experimental values. Comparison of α and spontaneous fission half-lives predicts four-α chains and three-α chains, respectively, from 287 115 and 288 115 nuclei and are in agreement with experimental observation. Our study predicts two-α chains from 273,274,289 115, three-α chains from 275 115, and four-α chains consistently from 284,285,286 115 nuclei. These observations will be useful for further experimental investigation in this region.

  13. In-beam separation and mass determination of superheavy nuclei

    International Nuclear Information System (INIS)

    Malyshev, O.N.; Eremin, A.V.; Popeko, A.G.

    2003-01-01

    Within the past fifteen years, the recoil separator VASSILISSA has been used for the investigations of evaporation residues produced in complete fusion reactions induced by heavy ions. The study of decay properties and formation cross sections of the isotopes of elements 110, 112 and 114 was performed using high intensity 48 Ca beams and 232 Th, 238 U, 242 Pu targets. For further experiments aimed at the synthesis of the superheavy element isotopes (Z≥110) with the use of intense 48 Ca extracted beams, improvements in the ion optical system of the separator and the focal plane detector system have been made. The results from the test reactions and new result for the isotope 283 112 are presented

  14. Remarks on the fission barriers of super-heavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, S. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Goethe-Universitaet Frankfurt, Institut fuer Physik, Frankfurt (Germany); Heinz, S.; Mann, R.; Maurer, J.; Muenzenberg, G.; Barth, W.; Dahl, L.; Kindler, B.; Kojouharov, I.; Lang, R.; Lommel, B.; Runke, J.; Scheidenberger, C.; Tinschert, K. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Antalic, S. [Comenius University, Department of Nuclear Physics and Biophysics, Bratislava (Slovakia); Eberhardt, K.; Thoerle-Pospiech, P.; Trautmann, N. [Johannes Gutenberg-Universitaet Mainz, Mainz (Germany); Grzywacz, R. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Knoxville, TN (United States); Hamilton, J.H. [Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States); Henderson, R.A.; Kenneally, J.M.; Moody, K.J.; Shaughnessy, D.A.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Miernik, K. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Warsaw, Warsaw (Poland); Miller, D. [University of Tennessee, Knoxville, TN (United States); Morita, K. [RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama (Japan); Nishio, K. [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan); Popeko, A.G.; Yeremin, A.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Roberto, J.B.; Rykaczewski, K.P. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Uusitalo, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland)

    2016-04-15

    Shell-correction energies of super-heavy nuclei are approximated by using Q{sub α} values of measured decay chains. Five decay chains were analyzed, which start at the isotopes {sup 285}Fl, {sup 294}118, {sup 291}Lv, {sup 292}Lv and {sup 293}Lv. The data are compared with predictions of macroscopic-microscopic models. Fission barriers are estimated that can be used to eliminate uncertainties in partial fission half-lives and in calculations of evaporation-residue cross-sections. In that calculations, fission probability of the compound nucleus is a major factor contributing to the total cross-section. The data also provide constraints on the cross-sections of capture and quasi-fission in the entrance channel of the fusion reaction. Arguments are presented that fusion reactions for synthesis of isotopes of elements 118 and 120 may have higher cross-sections than assumed so far. (orig.)

  15. Nuclear spectroscopy with Geant4. The superheavy challenge

    Science.gov (United States)

    Sarmiento, Luis G.

    2016-12-01

    The simulation toolkit Geant4 was originally developed at CERN for high-energy physics. Over the years it has been established as a swiss army knife not only in particle physics but it has seen an accelerated expansion towards nuclear physics and more recently to medical imaging and γ- and ion- therapy to mention but a handful of new applications. The validity of Geant4 is vast and large across many particles, ions, materials, and physical processes with typically various different models to choose from. Unfortunately, atomic nuclei with atomic number Z > 100 are not properly supported. This is likely due to the rather novelty of the field, its comparably small user base, and scarce evaluated experimental data. To circumvent this situation different workarounds have been used over the years. In this work the simulation toolkit Geant4 will be introduced with its different components and the effort to bring the software to the heavy and superheavy region will be described.

  16. Alpha Decay of Even-Even Superheavy Nuclei

    International Nuclear Information System (INIS)

    Oudih, M.R.; Hamza, Y.; Fellah, M.; Allal, N.H.; Fellah, M.; Allal, N.H.

    2011-01-01

    Alpha decay properties of even-even superheavy nuclei with 112.Z.120 have been investigated using the Hartree-Fock-Bogoliubov approach. The method is based on the SkP Skyrme interaction and the Lipkin-Nogami prescription for treating the pairing correlations. The alpha decay energies are extracted from the binding energies and then used for the calculation of the decay half-lives using a formula similar to that of Viola-Seaborg. The parameters of the formula were obtained through a least square fit to even-even heavy nuclei taken from the tables of Audi- Wapstra and some more recent references. The results are compared with other theoretical evaluations.

  17. Alpha-decay chains of superheavy nuclei 292-296118

    Science.gov (United States)

    Singh, U. K.; Kumawat, M.; Saxena, G.; Kaushik, M.; Jain, S. K.

    2018-05-01

    We have employed relativistic mean-field plus BCS (RMF+BCS) approach for the study of even-even superheavy nuclei with Z = 118 which is the last and recent observed element in the periodic chart so far. Our study includes binding energies, Qα values, alpha-decay half-lives and spontaneous decay half-lives along with comparison of available experimental data and the results of FRDM calculations. We find an excellent match with the only known decay chain of 294118 for Z = 118 so far and predict decay chain of 292118 and 296118 in consistency with known experimental decay chains and FRDM results. These results may provide a very helpful insight to conduct experiments for realizing the presence of nuclei with Z = 118.

  18. Toroidal Superheavy Nuclei in Skyrme-Hartree-Fock Approach

    International Nuclear Information System (INIS)

    Staszczak, A.; Wong, Cheuk-Yin

    2009-01-01

    Within the self-consistent constraint Skyrme-Hartree-Fock+BCS model (SHF+BCS), we found equilibrium toroidal nuclear density distributions in the region of superheavy elements. For nuclei with a sufficient oblate deformation (Q 20 < -200 b), it becomes energetically favorable to change the genus of nuclear surface from 0 to 1, i.e., to switch the shape from a biconcave disc to a torus. The energy of the toroidal (genus=1) SHF+BCS solution relative to the compact (genus=0) ground state energy is strongly dependent both on the atomic number Z and the mass number A. We discuss the region of Z and A where the toroidal SHF+BCS total energy begins to be a global minimum

  19. Estimation of atomic masses of heavy and superheavy elements

    Energy Technology Data Exchange (ETDEWEB)

    Uno, Masahiro [Ministry of Education, Science and Culture, Tokyo (Japan)

    1997-07-01

    To estimate unknown atomic masses of heavy and superheavy elements, three kinds of formula: FRDM (finite range droplet model by Moeller et al.), TUYY (an empirical formula by Tachibana et al.) and our KUTY are explained. KUTY estimates the crude shell energies of spherical nucleus from sum of single-particle energies. Then, the refined shell energies in due consideration of paring and deformation are obtained by mixing with the functions of the crude shell energies. Experimental values of U and Fm isotopes were compared with estimation mass of KUTY and FRDM. In the field with experimental values of U isotopes, the value of KUTY and FRDM separated the same difference from the experimental value. The behavior of KUTY and FRDM for Fm isotopes were same as that of U, but ETFSI deviated a little from the experimental values. (S.Y.)

  20. Attempts in search for superheavy elements in nature II

    International Nuclear Information System (INIS)

    Langrock, E.-J.; Vater, P.; Brandt, R.; Langrock, G.; Schumer, F.; Schreck, P.

    1999-01-01

    The search for superheavy elements is continued. We chose minerals for long-time exposure in a sandwich arrangement (PAD [polyallyldiglycol carbonate] and mica). In a first step we investigated samples of manganese concretions from the Pacific Ocean, enriched samples from Salton Sea and a volatile by product - fraction of copper - shale (Kupferschiefer) from Mansfeld ('Theisenschlamm'). After an exposure time of 535 days or 326 days, respectively, and proper etching, the SSNTD's were scanned using an optical microscope. Tracks due to the fission fragments could be seen neither at the PAD nor at the mica surface. The most hopeful sample 'Theisenschlamm' gives about 1.2x10 6 tracks of α-particles at PAD. This can be explained by the uranium content. The exposure will be continued and other samples will be investigated, too

  1. Reaction cross section measurements of neutron-rich exotic nuclei in the vicinity of closed shells N=20 and N=28

    International Nuclear Information System (INIS)

    Khouaja, A.

    2003-12-01

    Using the direct method, the mean energy integrated reaction cross section was investigated for a wide range of neutron-rich nuclei (N → Ar) at GANIL. Using the parametrisation of S. Kox, 19 new radii measurements (reaction cross sections) were obtained. By the isotopic, isotonic and isospin dependence, the evolution of the strong reduced radius was studied according to the excess of neutrons. New halo effect is proposed to the nuclei of Mg 35 and S 44 . A quadratic parametrization is also proposed for the nuclear radius as a function of the isospin in the region of closed shells N=8 and N=28. In addition, we used a modified version of the Glauber model for studying the tail and matter distribution of nuclei. Indeed, using our new data the effects of the nuclear size (root mean square radii) and the matter distribution (diffusivity) were de-convoluted for each isotope. The root mean square radii of Na and Mg isotopes obtained so far were consistent with the ones from literature. (author)

  2. First one-line mass measurements at SHIPTRAP and mass determinations of neutron-rich Fr and Ra isotopes at ISOLTRAP

    International Nuclear Information System (INIS)

    Rahaman, M.S.

    2005-01-01

    SHIPTRAP is an ion trap facility behind the velocity lter SHIP at GSI/Darmstadt. Its aim are precision studies of transuranium nuclides produced in a fusion reaction and separated by SHIP. The current set-up for high-precision mass measurements consists of three main functional parts: (i) a gas cell for stopping the energetic ions from SHIP, (ii) radiofrequency quadrupole structures to cool and to bunch the ions extracted from the gas cell, and (iii) a superconducting magnet with two cylindrical Penning traps at a eld strength of 7 T. In this work the Penning trap system has been installed and extensively characterized. The rst on-line mass measurements of short-lived nuclides were carried out and the masses of 147 Er and 148 Er could be experimentally determined for the rst time. Here a relative mass uncertainty of δm/m of about 1 x 10 -6 was achieved. Furthermore the masses of heavy neutron-rich 229-232 Ra and 230 Fr isotopes have been determined with a relative mass uncertainty of about 1 x 10 -7 with the ISOLTRAP mass spectometer at ISOLDE/CERN. The isotope 232 Ra is the heaviest unstable nuclide ever investigated with a Penning trap. Underlying nuclear structure effects of these nuclides far from β-stability were studied by a comparison of the resulting two-neutron separation energies S 2n with those given by the theoretical Infinite Nuclear Mass model. (orig.)

  3. A study of some neutron-rich isotopes of lanthanum, cerium and praseodymium by means of fast chemical on-line separation technique SISAK

    International Nuclear Information System (INIS)

    Skarnemark, G.

    1977-01-01

    The fast on-line chemical separation technique SISAK has been utilized to study the decay properties of neutron-rich isotopes of La, Ce and Pr. The results include partial decay schemes and γ-ray intensity data for 14 min 143 La, 42 s 144 La, 25 s 145 La, 9 s 146 La, 3 min 145 Ce, 14 min 146 Ce, 56 s 147 Ce, 50 s 148 Ce, 12 min 147 Pr, 2 min 148 Pr, 3 min 149 Pr and 6 s 150 Pr. Half-lives and γ-ray energies are reported for the previously unknown nuclides 147 La (Tsub(1/2) = 2.2 s), 148 La (Tsub(1/2) approximately 1 s), 149 Ce (Tsub(1/2) = 5.7 s) and 150 Ce (Tsub(1/2) = 4.1 s). The nuclides were formed in thermal neutron-induced fission of 235 U. The fission products were transferred to the SISAK system via a gas jet recoil transportation (GJRT) system. The combination of the GJRT system with SISAK is discussed, as well as the chemical separation systems used for the isolation of La, Ce and Pr. The appendices I - IX contain previously published material which is included in the thesis. (Auth.)

  4. Neutron-Rich Silver Isotopes Produced by a Chemically Selective Laser Ion-Source: Test of the R-Process " Waiting-Point " Concept

    CERN Multimedia

    2002-01-01

    The r-process is an important nucleosynthesis mechanism for several reasons: \\begin{enumerate} \\item It is crucial to an understanding of about half of the A>60 elemental composition of the Galaxy; \\item It is the mechanism that forms the long-lived Th-U-Pu nuclear chronometers which are used for cosmochronolgy; \\item It provides an important probe for the temperature (T$ _{9} $)-neutron density ($n_{n}$) conditions in explosive events; and last but not least \\item It may serve to provide useful clues to and constraints upon the nuclear properties of very neutron-rich heavy nuclei. \\end{enumerate} \\\\ \\\\With regard to nuclear-physics data, of particular interest are the T$ _{1/2} $ and P$_{n-} $ values of certain$\\,$ "waiting-point"$\\,$ isotopes in the regions of the A $ \\approx $ 80 and 130. r-abundance peaks. Previous studies of $^{130}_{\\phantom{1}48}$Cd$_{82}$ and $^{79}_{29}$Cu$_{50}$. $\\beta$-decay properties at ISOLDE using a hot plasma ion source were strongly complicated by isobar and molecular-ion c...

  5. Study of neutron-rich nuclei structure around the N=28 shell closure using the in-beam gamma spectroscopy technique

    International Nuclear Information System (INIS)

    Bastin, B.

    2007-10-01

    For a few years now, a loss of magicity in neutron-rich nuclei near the neutron drip-line at N=28 has been suggested and observed. Deformation in these nuclei has been observed. The deformation was explained in S isotopes as being due to a moderate reduction of the N=28 shell closure together with a proton induced collectivity originating from the near degeneracy of the proton d3/2 and s1/2 orbitals. As a consequence, the observed deformation seems to result from a subtle interplay between neutron and proton excitations. Since the proton configuration in the Si isotopes is expected to be more stable due to the Z=14 sub-shell gap, 42 Si was considered as a key nucleus in order to distinguish the different effects responsible for the structural changes observed at N=28. Even if it is at the limits of our technical possibilities, an in-beam gamma-spectroscopy experiment using two-step fragmentation and one or several nucleons knockout reaction mechanisms was performed at GANIL. The measurement of the energy of the first excited state in 42 Si, combined with the observation of 38,40 Si and the spectroscopy of 41,43 P, has given evidence for the loss of magicity at N=28 far from stability. Modifications of the effective interaction used in modern shell model calculations have been completed following this investigation, increasing its predictive character. This study confirms the role of the tensor force and the density dependence of the spin-orbit interaction in the collapse of the N=28 shell closure. (author)

  6. Study of shell closures N=40 and N=50 in neutron-rich nuclei; Etude des fermetures de couches N=40 et N=50 dans les noyaux riches en neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Perru, O

    2004-12-01

    For this thesis I have studied 2 neutron shell closures: N=40 and N=50. On N=50, an experiment was done in February 2001 on the ISOL line PARRNe, the issue was to measure the first excited states of {sup 83}Ge (Z=32, N=51) by studying the beta decay of {sup 83}Ga produced by fission of {sup 238}U.The extreme precision of the experimental device, with the operation of hot plasma ion sources made it possible to reach spectroscopic information of the Ge isotopes beyond the magic gap N=50. Two transitions have been attributed to {sup 83}Ge: at 867 keV and at 1238 keV. The level scheme of {sup 83}Ge could be interpreted in terms of weak coupling: the excited states of this nucleus are due to the couplings between the single neutron beyond N=50 and the remaining nucleons.On N=40, we wanted to determine the transition probability between ground state and first excited state, called B(E2), in {sup 70}Ni (N=42) and {sup 74}Zn (N=44) from Coulomb excitation. These exotic nuclei are produced by fragmentation of a primary beam of {sup 76}Ge on a target of {sup 58}Ni, selected by the spectrometer LISE, then interact with a secondary {sup 208}Pb target to induce the Coulomb excitation. At the end of this analysis, the following values have been obtained: B(E2,{sup 70}Ni)=860(170) e{sup 2}fm{sup 4}, B(E2,{sup 74}Zn)=1960(140) e{sup 2}fm{sup 4}. These values have been compared on the one hand to variational calculations which I have realised, on the other hand to published shell model calculations.These calculations point out the complex aspect of the Ni nuclei, which do not seem to have a typical behaviour of semi magic nuclei although they are located on a closed shell in protons (Z=28). (author)

  7. Pion condensation in cold dense matter and neutron stars

    International Nuclear Information System (INIS)

    Haensel, P.; Proszynski, M.

    1982-01-01

    We study possible influence, on the neutron star structure, of a pion condensation occurring in cold dense matter. Several equations of state with pion-condensed phase are considered. The models of neutron stars are calculated and confronted with existing observational data on pulsars. Such a confrontation appears to rule out the models of dense matter with an abnormal self-bound state, and therefore it seems to exclude the possibility of the existence of abnormal superheavy neutron nuclei and abnormal neutron stars with a liquid pion-condensed surface

  8. Spectroscopy of very heavy nuclei with a view to study super-heavy nuclei

    International Nuclear Information System (INIS)

    Khalfallah, F.

    2007-08-01

    Within the recent years, the spectroscopic study of single particle orbitals of very heavy elements (VHE) has become possible with the development of increasingly efficient experimental setups. This allows us, through nuclear deformation, to access with these deformed nuclei to orbitals situated around the Fermi level in the spherical superheavy elements (SHE) and learn more about the nuclear structure of these nuclei. The aim of this work is the spectroscopic studies of heavy and very heavy elements. Because of the experimental difficulties associated with the fusion reactions in the VHE region, a detailed optimization studies is essential. Simulation of energy loss and angular straggling of these nuclei due to the interaction in the target and to neutron's evaporation was carried out and allowed us to optimize the angular acceptance of the separators according to the target thickness. An extensive survey and exploration in the VHE region was also conducted on the basis of cross section's systematics in the literature and simulations carried out using the statistical code Hivap. In this framework, the possible extension of the range of validity of a set of Hivap parameters was investigated. This work has enabled us to prepare a list of experiments of interest for the production of very heavy nuclei. In this thesis, our work was concentrated on the spectroscopy of the nuclei No 256 et Rf 256 for which two experimental proposals were accepted. The octupole deformations predicted in the actinides region is studied in another part of this thesis, a part witch is dedicated to the gamma spectroscopy of Pa 223 . The data from a new experiment carried out using the Jurogam-Ritu-Great setup are analysed and compared to previous results. They confirm the octupole deformed shape in this nucleus. (author)

  9. Spins, charge radii and magnetic moments of neutron-rich Mn isotopes measured with bunched beam Collinear Laser Spectroscopy

    CERN Document Server

    AUTHOR|(CDS)2085887; Heylen, Hanne

    In this work, the odd-even $^{51–63}$Mn isotopes have been analyzed using collinear laser spectroscopy, from which the magnetic dipole moment and the change in change in mean square charge radius can be determined. The magnetic moment is very sensitive to the composition of the total nuclear wave function, while the charge radius gives information about the relative size and degree of deformation of the nucleus. An additional advantage of collinear laser spectroscopy is the possibility of direct measurement of the nuclear spin. The main motivation behind the study of these isotopes is to investigate the change in nuclear structure when approaching neutron number N = 40. This region is of interest due to the apparent doubly magic nature of $^{68}$Ni , which is not seen in the N = 40 isotopes of $^{26}$Fe and $^{24}$Cr. Mn, situated between these elements, offers another perspective due to its uncoupled proton. Based on the observed spectra and extracted moments, spins were assigned to $^{59,61,63}$Mn. The ex...

  10. Transition probabilities in neutron-rich Se,8280 and the role of the ν g9 /2 orbital

    Science.gov (United States)

    Litzinger, J.; Blazhev, A.; Dewald, A.; Didierjean, F.; Duchêne, G.; Fransen, C.; Lozeva, R.; Verney, D.; de Angelis, G.; Bazzacco, D.; Birkenbach, B.; Bottoni, S.; Bracco, A.; Braunroth, T.; Cederwall, B.; Corradi, L.; Crespi, F. C. L.; Désesquelles, P.; Eberth, J.; Ellinger, E.; Farnea, E.; Fioretto, E.; Gernhäuser, R.; Goasduff, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hackstein, M.; Hess, H.; Ibrahim, F.; Jolie, J.; Jungclaus, A.; Kolos, K.; Korten, W.; Leoni, S.; Lunardi, S.; Maj, A.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Mijatovic, T.; Million, B.; Möller, O.; Modamio, V.; Montagnoli, G.; Montanari, D.; Morales, A. I.; Napoli, D. R.; Niikura, M.; Pietralla, N.; Pollarolo, G.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Rosso, D.; Sahin, E.; Salsac, M. D.; Scarlassara, F.; Söderström, P.-A.; Stefanini, A. M.; Stezowski, O.; Szilner, S.; Theisen, Ch.; Valiente-Dobón, J. J.; Vandone, V.; Vogt, A.

    2018-04-01

    Transition probabilities of intermediate-spin yrast and non-yrast excitations in Se,8280 were investigated in a recoil distance Doppler-shift (RDDS) experiment performed at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. The Cologne Plunger device for deep inelastic scattering was used for the RDDS technique and was combined with the AGATA Demonstrator array for the γ -ray detection and coupled to the PRISMA magnetic spectrometer for an event-by-event particle identification. In 80Se, the level lifetimes of the yrast (61+) and (81+) states and of a non-yrast band feeding the yrast 41+ state are determined. A spin and parity assignment of the head of this sideband is discussed based on the experimental results and supported by large-scale shell-model calculations. In 82Se, the level lifetimes of the yrast 61+ state and the yrare 42+ state and lifetime limits of the yrast (101+) state and of the 51- state are determined. Although the experimental results contain large uncertainties, they are interpreted with care in terms of large-scale shell-model calculations using the effective interactions JUN45 and jj44b. The excited states' wave functions are investigated and discussed with respect to the role of the neutron g9 /2 orbital.

  11. 18 Sco: A solar twin rich in refractory and neutron-capture elements. Implications for chemical tagging

    Energy Technology Data Exchange (ETDEWEB)

    Meléndez, Jorge; Monroe, TalaWanda R.; Tucci Maia, Marcelo; Freitas, Fabrício C. [Departamento de Astronomia do IAG/USP, Universidade de São Paulo, Rua do Matão 1226, 05508-900 São Paulo, SP (Brazil); Ramírez, Iván [McDonald Observatory and Department of Astronomy, University of Texas at Austin (United States); Karakas, Amanda I.; Yong, David; Asplund, Martin [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston, ACT 2611 (Australia); Bedell, Megan; Bean, Jacob [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Bergemann, Maria [Institute of Astronomy, University of Cambridge, Madingley Road, CB3 0HA, Cambridge (United Kingdom); Do Nascimento, José-Dias Jr.; Castro, Matthieu [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Bazot, Michael [Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Alves-Brito, Alan, E-mail: jorge.melendez@iag.usp.br [Instituto de Fisica, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves 9500, Porto Alegre, RS (Brazil)

    2014-08-10

    We study with unprecedented detail the chemical composition and stellar parameters of the solar twin 18 Sco in a strictly differential sense relative to the Sun. Our study is mainly based on high-resolution (R ∼ 110,000), high signal-to-noise ratio (800-1,000) Very Large Telescope UVES spectra, which allow us to achieve a precision of about 0.005 dex in differential abundances. The effective temperature and surface gravity of 18 Sco are T{sub eff} = 5823 ± 6 K and log g = 4.45 ± 0.02 dex, i.e., 18 Sco is 46 ± 6 K hotter than the Sun and log g is 0.01 ± 0.02 dex higher. Its metallicity is [Fe/H] = 0.054 ± 0.005 dex, and its microturbulence velocity is +0.02 ± 0.01 km s{sup –1} higher than solar. Our precise stellar parameters and differential isochrone analysis show that 18 Sco has a mass of 1.04 ± 0.02 M{sub ☉} and that it is ∼1.6 Gyr younger than the Sun. We use precise High Accuracy Radial velocity Planet Searcher (HARPS) radial velocities to search for planets, but none are detected. The chemical abundance pattern of 18 Sco displays a clear trend with condensation temperature, thus showing higher abundances of refractories in 18 Sco than in the Sun. Intriguingly, there are enhancements in the neutron-capture elements relative to the Sun. Despite the small element-to-element abundance differences among nearby n-capture elements (∼0.02 dex), we successfully reproduce the r-process pattern in the Solar System. This is independent evidence for the universality of the r process. Our results have important implications for chemical tagging in our Galaxy and nucleosynthesis in general.

  12. On-line mass separator of superheavy atoms

    International Nuclear Information System (INIS)

    Oganesyan, Yu.Ts.

    2002-01-01

    The concept is presented of an on-line Mass Analyzer of SuperHeavy Atoms (MASHA) dedicated to the separation and determination of the mass and decay properties of new elements and isotopes produced in heavy-ion induced reactions. The new nuclides with half-lives T 1/2 ≥ 1 s are transported to an ECR-source working at a frequency of 2.45 GHz and are separated by mass with a mass resolution of M/ΔM ∼ 1500. In the focal plane of the magnetic analyzer a front strip detector surrounded by side detectors will be placed to determine the mass according to the signals from the detected α-particles or fission fragments with efficiency of about 90 %. In comparison to other existing in-flight recoil separators, the present setup will be characterized by higher efficiency and high selectivity relative to background reaction products. The setup MASHA may be used also in the investigation of nuclear reactions of different type induced by stable and radioactive beams

  13. On-Line Mass Separator of Superheavy Atoms

    CERN Document Server

    Oganessian, Yu T

    2002-01-01

    The concept is presented of an on-line Mass Analyzer of SuperHeavy Atoms (MASHA) dedicated to the separation and determination of the mass and decay properties of new elements and isotopes produced in heavy-ion induced reactions. The new nuclides with half-lives T_{1/2}\\ge 1 s are transported to an ECR-source working at a frequency of 2.45 GHz and are separated by mass with a mass resolution of M/\\Delta M\\sim 1500. In the focal plane of the magnetic analyzer a front strip detector surrounded by side detectors will be placed to determine the mass according to the signals from the detected alpha-particles or fission fragments with efficiency of about 90 %. In comparison to other existing in-flight recoil separators, the present setup will be characterized by higher efficiency and high selectivity relative to background reaction products. The setup MASHA may be used also in the investigation of nuclear reactions of different type induced by stable and radioactive beams.

  14. Systematical calculations on the ground state properties of heavy and superheavy nuclei

    International Nuclear Information System (INIS)

    Ren, Z.Z.; Center of Theoretical Nuclear Physics, Lanzhou; Mao, Y.C.; Zhi, Q.J.; Xu, C.; Dong, T.K.

    2007-01-01

    The synthesis of superheavy elements is now a hot topic in nuclear physics. Alpha-decay and spontaneous fission are two main decay modes in heavy and superheavy regions. Theoretical studies on alpha radioactivity and spontaneous fission can provide useful information for experiments. We investigate the alpha-decay and spontaneous fission of heavy and superheavy nuclei with different models. This includes the alpha-decay energies, alpha decay half-lives, and half-lives of spontaneous fission. The theoretical alpha-decay half-lives are in good agreement with experimental ones. The calculated half-lives of spontaneous fission are in reasonable agreement with present data. The properties of unknown nuclei are predicted. (author)

  15. From heavy nuclei to super-heavy nuclei; Des noyaux lourds aux super-lourds

    Energy Technology Data Exchange (ETDEWEB)

    Theisen, Ch

    2003-01-01

    The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)

  16. Identification and Decay Studies of New, Neutron-Rich Isotopes of Bismuth, Lead and Thallium by means of a Pulsed Release Element Selective Method

    CERN Multimedia

    Mills, A; Kugler, E; Van duppen, P L E; Lettry, J

    2002-01-01

    % IS354 \\\\ \\\\ It is proposed to produce, identify and investigate at ISOLDE new, neutron-rich isotopes of bismuth, lead and thallium at the mass numbers A=215 to A=218. A recently tested operation mode of the PS Booster-ISOLDE complex, taking an advantage of the unique pulsed proton beam structure, will be used together with a ThC target in order to increase the selectivity. The decay properties of new nuclides will be studied by means of $\\beta$-, $\\gamma$- and X- ray spectroscopy methods. The expected information on the $\\beta$-half-lives and excited states will be used for testing and developing the nuclear structure models ``south-east'' of $^{208}$Pb, and will provide input data for the description of the r-process path at very heavy nuclei. The proposed study of the yields and the decay properties of those heavy nuclei produced in the spallation of $^{232}$Th by a 1~GeV proton beam contributes also the data necessary for the simulations of a hybrid accelerator-reactor system.

  17. Beta- and gamma-decay studies of neutron-rich chromium, manganese, cobalt and nickel isotopes including the new isotopes 60Cr and 60gMn

    International Nuclear Information System (INIS)

    Bosch, U.; Schmidt-Ott, W.D.; Runte, E.; Tidemand-Petersson, P.; Koschel, P.; Meissner, F.; Kirchner, R.; Klepper, O.; Roeckl, E.; Rykaczewski, K.; Schardt, D.

    1987-10-01

    A 36 mg/cm 2 thick nat W target was irradiated with 11.5 MeV/u 76 Ge of 15 to 20 particle + nA beam intensity. On-line mass-separated samples of projectile-like neutron-rich products from multi-nucleon transfer-reactions were investigated in the region of mass 58-69 by β- and γ-ray spectroscopy. The new isotope 60 Cr was identified with a half-life of 0.57(6) s and for the 60 Mn ground-state a half-life value of 51(6) s was obtained. Decay schemes were constructed for 58 Cr, 58 Mn (t 1/2 = 3 s), 65,66,67 Co and 69 Ni. One new γ-ray was found in the decay of 59 Cr. The Q β -value of 66 Co was measured yielding 9.7(5) MeV. The comparison of the measured new β-half-life of 60 Cr with the most recent predictions gave again an enhancement of the experimental value. (orig.)

  18. First on-line mass measurements at SHIPTRAP and mass determinations of neutron-rich Fr and Ra isotopes at ISOLTRAP

    CERN Document Server

    Rahaman, Saidu

    SHIPTRAP is an ion trap facility behind the velocity filter SHIP at GSI/Darmstadt. Its aim are precision studies of transuranium nuclides produced in a fusion reaction and separated by SHIP. The current set-up for high-precision mass measurements consists of three main functional parts: (i) a gas cell for stopping the energetic ions from SHIP, (ii) radiofrequency quadrupole structures to cool and to bunch the ions extracted from the gas cell, and (iii) a superconducting magnet with two cylindrical Penning traps at a field strength of 7 T. In this work the Penning trap system has been installed and extensively characterized. The first on-line mass measurements of short-lived nuclides were carried out and the masses of $^{147}$Er and $^{148}$Er could be experimentally determined for the first time. Here a relative mass uncertainty of $\\delta$ m/m of about 1$\\times$ 10$^{-6}$ was achieved. Furthermore the masses of heavy neutron-rich $^{229-232}$Ra and $^{230}$Fr isotopes have been determined with a relative m...

  19. Octupole correlations in neutron-rich {sup 143,145}Ba and a type of superdeformed band in {sup 145}Ba

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, S.J.; Wang, M.G.; Long, G.L.; Zhu, L.Y.; Gan, C.Y.; Yang, L.M.; Sakhaee, M.; Li, M.; Deng, J.K. [Physics Department, Tsinghua University, Beijing 100084, Peoples Republic of (China); Zhu, S.J.; Hamilton, J.H.; Ramayya, A.V.; Jones, E.F.; Hwang, J.K.; Zhang, X.Q.; Gore, P.M.; Peker, L.K.; Drafta, G.; Babu, B.R.; Deng, J.K.; Ginter, T.N.; Beyer, C.J.; Kormicki, J.; Ter-Akopian, G.M.; Daniel, A.V. [Physics Department, Vanderbilt University, Nashville, Tennessee 37235 (United States); Zhu, S.J.; Ter-Akopian, G.M.; Daniel, A.V. [Joint Institute for Heavy Ion Research, Oak Ridge, Tennessee 37831 (United States); Ma, W.C. [Physics Department, Mississippi State University, Mississippi 39762 (United States); Cole, J.D.; Aryaeinejad, R.; Drigert, M.W. [Idaho National Engineering Laboratory, Idaho Falls, Idaho 83415 (United States); Rasmussen, J.O.; Asztalos, S.; Lee, I.Y.; Macchiavelli, A.O.; Chu, S.Y.; Gregorich, K.E.; Mohar, M.F. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Ter-Akopian, G.M.; Daniel, A.V.; Oganessian, Y.T.; Kliman, J. [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna (Russia); Donangelo, R. [Universidade Federal do Rio de Janeiro, Caixa Postal 68528, RG (Brazil); Stoyer, M.A.; Lougheed, R.W.; Moody, K.J.; Wild, J.F. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Prussin, S.G. [Nuclear Engineering Department, University of California at Berkeley, Berkeley, California 94720 (United States); Kliman, J. [Institute of Physics, SASc, Dubravskacesta 9, 84228 Bratislava (Slovakia); Griffin, H.C. [University of Michigan, Ann Arbor, Michigan 48104 (United States)

    1999-11-01

    High spin states in neutron-rich odd-{ital Z} {sup 143,145}Ba nuclei have been investigated from the study of prompt {gamma} rays in the spontaneous fission of {sup 252}Cf by using {gamma}-{gamma}- and {gamma}-{gamma}-{gamma}- coincidence techniques. Alternating parity bands are identified for the first time in {sup 145}Ba and extended in {sup 143}Ba. A new side band, with equal, constant dynamic, and kinetic moments of inertia equal to the rigid body value, as found in superdeformed bands, is discovered in {sup 145}Ba. Enhanced E1 transitions between the negative- and positive-parity bands in these nuclei give evidence for strong octupole deformation in {sup 143}Ba and in {sup 145}Ba. These collective bands show competition and coexistence between symmetric and asymmetric shapes in {sup 145}Ba. Evidence is found for crossing M1 and E1 transitions between the s=+i and s={minus}i doublets in {sup 143}Ba. {copyright} {ital 1999} {ital The American Physical Society}

  20. Search for superheavy elements in monazite from Beach sands of South India

    International Nuclear Information System (INIS)

    Kapoor, S.S.; Ramamurthy, V.S.; Lal, R.; Kataria, S.K.

    1977-01-01

    Monazite minerals obtained from beach of South India were examined for the presence of superheavy elements with photon-induced x-ray fluorescence method. The accumulated data of a number of runs each of several days duration do not show any convicing peaks above the background at the expected locations for superheavy elements which are above the present sensitivity of detection of about 10 ppm by weight for element 126. However, some intriguing features pertaining to structures in the x-ray spectra around 27 kev were observed, which are of interest for further investigations. (author)

  1. Critical angular momentum dependence of the fission barriers and the stability of superheavy nuclei

    International Nuclear Information System (INIS)

    Magda, M.T.; Sandulescu, A.

    1978-10-01

    Measured complete fusion and evaporation cross section data are used to determine the critical angular momenta for which the fission barriers are vanishing in the region of nuclei with Z = 102 - 116. It is shown that, in order to fit these data, larger values of the critical angular momenta are obtained for superheavy nuclei (Z = 110 - 112) than for heavy ones (Z = 102 - 107), which indicates a relatively higher stability against fission for superheavy nuclei, in agreement with the theoretically predicted island of stability. (author)

  2. Global and local approaches to population analysis: Bonding patterns in superheavy element compounds

    Science.gov (United States)

    Oleynichenko, Alexander; Zaitsevskii, Andréi; Romanov, Stepan; Skripnikov, Leonid V.; Titov, Anatoly V.

    2018-03-01

    Relativistic effective atomic configurations of superheavy elements Cn, Nh and Fl and their lighter homologues (Hg, Tl and Pb) in their simple compounds with fluorine and oxygen are determined using the analysis of local properties of molecular Kohn-Sham density matrices in the vicinity of heavy nuclei. The difference in populations of atomic spinors with the same orbital angular momentum and different total angular momenta is demonstrated to be essential for understanding the peculiarities of chemical bonding in superheavy element compounds. The results are fully compatible with those obtained by the relativistic iterative version of conventional projection analysis of global density matrices.

  3. Fission and r-process nucleosynthesis in neutron star mergers

    International Nuclear Information System (INIS)

    Giuliani, Samuel Andrea

    2018-01-01

    Fission plays a crucial role for the r-process nucleosynthesis in neutron star mergers. Due to the high neutron densities achieved in this astrophysical scenario the sequence of neutron captures and beta decays that constitutes the r process produces superheavy neutron rich nuclei that become unstable against fission. Fission determines thus the heaviest nuclei that can be produced by the r process and the fission yields shape the abundances of lighter nuclei. But despite the key role of fission the sensitivity of the r-process nucleosynthesis to uncertainties in fission predictions has not been explored. Nowadays there are only few set of fission rates suited for r-process calculations and most of them rely on a simplified treatment of the fission process. In this thesis we go beyond these approximations and compute the fission properties of r-process nuclei using the energy density functional approach. Fission is described as a tunneling process where the nucleus ''moves'' in a collective space characterized by coordinates describing the nuclear shape. Thus fission depends on the evolution of the energy with the deformation but also on the inertia due to the motion in the collective space. This is analogous to the quantum mechanical tunneling of a particle inside a potential well. In our study the relevant quantities for the description of the fission process are consistently computed for 3642 nuclei following the Hartree-Fock-Bogolyubov theory with constraining operators. We perform an extensive benchmark against the available experimental data and explore the variations of the fission properties along the superheavy landscape. We find that while collective inertias have a strong impact in the fission probabilities of light nuclei their role becomes less relevant in r -process nuclei. Within the statistical model we compute the neutron induced stellar reaction rates relevant for the r-process nucleosynthesis. These sets of stellar reaction

  4. Neutron matter, symmetry energy and neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Stefano, Gandolfi [Los Alamos National Laboratory (LANL); Steiner, Andrew W [ORNL

    2016-01-01

    Recent progress in quantum Monte Carlo with modern nucleon-nucleon interactions have enabled the successful description of properties of light nuclei and neutron-rich matter. Of particular interest is the nuclear symmetry energy, the energy cost of creating an isospin asymmetry, and its connection to the structure of neutron stars. Combining these advances with recent observations of neutron star masses and radii gives insight into the equation of state of neutron-rich matter near and above the saturation density. In particular, neutron star radius measurements constrain the derivative of the symmetry energy.

  5. Reaction cross section measurements of neutron-rich exotic nuclei in the vicinity of closed shells N=20 and N=28; Mesures de section efficace de reaction de noyaux exotiques riches en neutrons dans la zone de fermeture des couches N=20 et N=28

    Energy Technology Data Exchange (ETDEWEB)

    Khouaja, A

    2003-12-01

    Using the direct method, the mean energy integrated reaction cross section was investigated for a wide range of neutron-rich nuclei (N {yields} Ar) at GANIL. Using the parametrisation of S. Kox, 19 new radii measurements (reaction cross sections) were obtained. By the isotopic, isotonic and isospin dependence, the evolution of the strong reduced radius was studied according to the excess of neutrons. New halo effect is proposed to the nuclei of Mg{sup 35} and S{sup 44}. A quadratic parametrization is also proposed for the nuclear radius as a function of the isospin in the region of closed shells N=8 and N=28. In addition, we used a modified version of the Glauber model for studying the tail and matter distribution of nuclei. Indeed, using our new data the effects of the nuclear size (root mean square radii) and the matter distribution (diffusivity) were de-convoluted for each isotope. The root mean square radii of Na and Mg isotopes obtained so far were consistent with the ones from literature. (author)

  6. Study of neutron-rich nuclei structure around the N=28 shell closure using the in-beam gamma spectroscopy technique; Etude de la structure des noyaux riches en neutrons autour de la fermeture de couches N=28 par spectroscopie gamma en ligne

    Energy Technology Data Exchange (ETDEWEB)

    Bastin, B

    2007-10-15

    For a few years now, a loss of magicity in neutron-rich nuclei near the neutron drip-line at N=28 has been suggested and observed. Deformation in these nuclei has been observed. The deformation was explained in S isotopes as being due to a moderate reduction of the N=28 shell closure together with a proton induced collectivity originating from the near degeneracy of the proton d3/2 and s1/2 orbitals. As a consequence, the observed deformation seems to result from a subtle interplay between neutron and proton excitations. Since the proton configuration in the Si isotopes is expected to be more stable due to the Z=14 sub-shell gap, {sup 42}Si was considered as a key nucleus in order to distinguish the different effects responsible for the structural changes observed at N=28. Even if it is at the limits of our technical possibilities, an in-beam gamma-spectroscopy experiment using two-step fragmentation and one or several nucleons knockout reaction mechanisms was performed at GANIL. The measurement of the energy of the first excited state in {sup 42}Si, combined with the observation of {sup 38,40}Si and the spectroscopy of {sup 41,43}P, has given evidence for the loss of magicity at N=28 far from stability. Modifications of the effective interaction used in modern shell model calculations have been completed following this investigation, increasing its predictive character. This study confirms the role of the tensor force and the density dependence of the spin-orbit interaction in the collapse of the N=28 shell closure. (author)

  7. Structure of superheavy elements with Meson field theory and beyond

    International Nuclear Information System (INIS)

    Walter Greiner

    2005-01-01

    The extension of the periodic system into various new areas is investigated. Experiments for the synthesis of superheavy elements and the predictions of magic numbers with modern meson field theories are reviewed. Furtheron, different channels of nuclear decay are discussed including cluster radioactivity, cold fission and cold multifragmentation. A perspective for future research is given. We also study the possibility of producing a new kind of nuclear system that in addition to ordinary nucleons contains a few antibaryons. The properties of such systems are described within the relativistic mean-field model by employing G-parity transformed interactions for antibaryons. Calculations are first done for infinite systems and then for finite nuclei from 4 He to 208 Pb. It is demonstrated that the presence of a real antibaryon leads to a strong rearrangement of a target nucleus, resulting in a significant increase of its binding energy and local compression. Noticeable effects remain even after the antibaryon coupling constants are reduced by a factor of 3-4 compared to G-parity motivated values. We have performed detailed calculations of the antibaryon annihilation rates in the nuclear environment by applying a kinetic approach. It is shown that owing to significant reduction of the reaction Q values, the in-medium annihilation rates should be strongly suppressed, leading to relatively long-lived antibaryon- nucleus systems. Multinucleon annihilation channels are analyzed too. We have also estimated formation probabilities of bound antibaryon-nucleus systems in antiproton- nucleus reactions and have found that their observation will be feasible at the future GSI antiproton facility. Several observable signatures are proposed. The possibility of producing cold multi-quark-antiquark clusters is discussed. This opens the possibility for cold compression of nuclear matter - in contrast to the creation of hot and dense nuclear matter in nuclear shock waves created in

  8. Some new approaches to the synthesis of heavy and superheavy elements

    International Nuclear Information System (INIS)

    Flerov, G.N.

    1980-01-01

    The results of work on the synthesis of heavy and superheavy elements are considered. It is shown that the new regularity of the systematics of spontaneous-fission half-lives, established for heavy nuclei at Dubna, has made it possible to extend the region of the nuclei being synthesized. In particular, it becomes possible to produce relatively long-lived heavy isotopes of Z>=107. The results of experiments to study the emission of energetic α-particles in the collision of heavy nuclei are presented. It is noted that such reactions can be used to produce atomic nuclei with low excitation energy and large angular momentum. The possible use of similar reactions in the synthesis of heavy and superheavy elements is discussed. In case the existence of a naturally occurring superheavy element has been established, a possibility will arise to synthesize in nuclear reactions a number of isotopes belonging to the island of stability, and to investigate their properties. The present state of work on the search for superheavy elements in nature is briefly described

  9. Superheavy elements in D I Mendeleev's Periodic Table

    Energy Technology Data Exchange (ETDEWEB)

    Oganessian, Yury Ts; Dmitriev, Sergey N [Flerov Laboratory for Nuclear Reactions, Joint Institute for Nuclear Research, Dubna, Moscow Region (Russian Federation)

    2009-12-31

    The results on the synthesis of new superheavy elements, synthesized in complete fusion reactions of {sup 48}Ca ions with actinide targets, are summarized and analyzed. The perspectives for the synthesis of element 117, as well as of elements with Z>=118 are also considered.

  10. Relativistic quantum chemistry of the superheavy elements. Closed-shell element 114 as a case study

    International Nuclear Information System (INIS)

    Schwerdtfeger, Peter; Seth, Michael

    2002-01-01

    The chemistry of superheavy element 114 is reviewed. The ground state of element 114 is closed shell [112]7s 2 7p 1/2 2 and shows a distinct chemical inertness (low reactivity). This inertness makes it rather difficult to study the atom-at-a-time chemistry of 114 in the gas or liquid phase. (author)

  11. Influence of fragment deformation and orientation on compact configuration of odd-Z superheavy nuclei

    International Nuclear Information System (INIS)

    Gurjit Kaur; Sandhu, Kirandeep; Sharma, Manoj K.

    2016-01-01

    The synthesis of heavy and superheavy nuclei is generally carried out by using hot and cold fusion reaction mechanisms. It has been noticed that, the cold fusion reactions occur at relatively low excitation energies (E*_C_N ∼ 10-20 MeV) whereas, the hot fusion reactions occur at excitation energies of E*_C_N ∼ 30- 50 MeV. The fusion mechanism is quite different in both the processes. In the cold fusion process, the interaction of spherical targets (Pb and Bi) with deformed light mass projectiles occurs. On the other hand, the fusion of deformed actinide targets with spherical "4"8Ca projectile characterize the hot interaction processes. Hence the deformations and orientations of targets and projectiles play extremely important role in the superheavy fusion process. The present analysis is carried out to aggrandize the work of which illustrate the role of deformations and orientations on even superheavy nuclei. Here, we extend this analysis for odd superheavy nuclei. It is relevant to note that the temperature and angular momentum effects are not included in the present analysis

  12. Mendeleev's principle against Einstein's relativity: news from the chemistry of superheavy elements

    Energy Technology Data Exchange (ETDEWEB)

    Gaeggeler, Heinz W [Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland)

    2009-12-31

    The review briefly considers the problems of synthesis and chemical identification of superheavy elements. The specific features of their properties are determined by the relativistic effects. The synthesis and chemical investigations into bohrium and element 112 are discussed as examples.

  13. The mass (charge) spectrum of superheavy nuclei fission fragments: the new perspectives for the theory of nucleosynthesis

    International Nuclear Information System (INIS)

    Maslyuk, V.T.

    2012-01-01

    A new approach to the problem of nucleosynthesis based on assumption of a nuclear matter or superheavy nuclei series fragmentation up to atomic nuclei is proposed. It is shown that studies of the mass (charge) fragments yields (MCFY) after nuclear matter disintegration is possible within proposed statistical theory. The data of MCFY calculation for exotic superheavy nuclei multifragmentation with A=300, 900 and 1200 and arbitrary Z values are demonstrated

  14. Single-particle states in neutron-rich 69,71Cu by means of the (d,3He) transfer reaction

    International Nuclear Information System (INIS)

    Morfouace, Pierre

    2014-01-01

    In two (d, 3 He) transfer reactions with MUST2 at GANIL and the split-pole at Orsay, we have determined the position of the proton-hole states in the neutron-rich 71 Cu (N=42) and 69 Cu (N=40) isotopes. We have found that in 71 Cu the hole strength of the f7/2 orbital lies at higher excitation energies than expected. From beta-decay and laser spectroscopy, the f5/2 first excited particle state in these isotopes was known to come down rapidly in energy when passing N=40 and even become the ground state in 75 Cu. This sudden energy shift has been explained in a number of theoretical works. The prediction for the f7/2 spin-orbit partner was that it would change in energy too through a related effect. Experimentally, the f7/2 proton-hole state is not known for N≥40. In 71 Cu two 7/2- states around 1 MeV are candidates to be a proton-hole. The experiment at GANIL took place in March 2011. A secondary beam of 72 Zn at 38 AMeV was produced by fragmentation and purified through the LISE spectrometer. The transfer reaction in inverse kinematics was studied with the MUST2 detectors plus four 20 micrometer silicon detector to identified the 3 He of low kinetic energy. The excitation spectrum of 71 Cu was reconstruct thanks to the missing mass method and the angular distributions were extracted and compared with a reaction model using the DWUCK4 and DWUCK5 code. From this work no states have been populated around 1 MeV concluding that the centroid of the f7/2 lies at higher excitation energy. We then remeasured the single-particle strength in 69 Cu in the corresponding (d, 3 He) reaction at Orsay in March 2013 in order to extend the existing data where 60% of the f7/2 strength is missing and make sure that there is a consistent analysis of spectroscopic factors between both isotopes in order to well understood and well quantify the evolution of the f7/2 orbital when we start filling the g9/2 orbital. In this second experiment we have performed the reaction in direct

  15. Beta decay and magnetic moments as tools to probe nuclear structure. Study of neutron-rich nuclei around N=40; Decroissance beta et moments magnetiques comme outils pour sonder la structure nucleaire. Etude des noyaux riches en neutrons autour de N=40

    Energy Technology Data Exchange (ETDEWEB)

    Matea, I

    2003-12-01

    The evolution of nuclear structure in nuclei far from the {beta} stability line is one of the 'hot topics' in modern experimental and theoretical nuclear physics. The present thesis is devoted to the study of structure of neutron-rich nuclei around N=40. The evolution of the neutron g9/2 orbital with increasing number of neutrons is one of the key points defining the structure of these nuclei at low excitation energy. We used for this investigation as experimental tools the magnetic dipole moments measurements and the {beta} decay spectroscopy. For the measurement of the gyromagnetic factor of the 9/2{sup +} isomeric state in Fe{sup 61} we have applied the TDPAD method. This method (like most of measurements of nuclear moments) requires an oriented ensemble of nuclei. The orientation of Fe{sup 61m} was achieved via the fragmentation of Ni{sup 64} at 55 MeV/u and the selection of the fragment momentum with the LISE spectrometer at GANIL. The experimental device was specially conceived to preserve the alignment up to the implantation point. The measured value of the g factor was compared with large-scale shell model and Hartree-Fock-Bogoliubov model predictions. The nuclei studied via {beta} decay were produced by the fragmentation of Kr{sup 86} at 58 MeV/u. For the selection of reaction products we used for the first time the LISE2000 spectrometer and for the detection of {gamma} rays four EXOGAM clover detectors. We measured 5 new lifetimes and 4 lifetimes with a higher precision. From the prompt {beta}{gamma} coincidences we identified new states in the daughter nuclei, as it is the case of the first 2{sup +} excited states in Fe{sup 68} and Ni{sup 72}. The results were compared with the predictions of the large-scale shell model. Other transitions were observed for the first time in {beta}{gamma} decay of Ti{sup 60}, Fe{sup 70} and Co{sup 71,73}. (author)

  16. Nuclear structure of neutron rich gallium, germanium and arsenic around N=50 and development of a laser ion source at ALTO

    International Nuclear Information System (INIS)

    Tastet, B.

    2011-01-01

    During this thesis, we have studied β decays of gallium's nuclei around N=50 and prepared a laser ionization source at ALTO.The production of exotic isotopes has brought new beam production challenges. The one addressed here relates to the elimination of isobar contaminants that create background for experiments. To address this issue a laser ionization source has been developed at ALTO. Copper has been chosen to be the first element to be ionized for physical interests and to compare the results of the laser ionization source with the ones at others facilities. A laser setup has been installed and optimized in order to ionize selectively the atoms of copper produced for experiments. After the optimization, a test of ionization of stable-copper was performed. This test has shown us that the laser system is able to successfully ionize atoms of copper.The studies of the region of the neutron-rich nuclei around N=50 are still to complete. 79,80,82,83,84,85 Ga has been produced using photo-nuclear reactions at the experimental area of the on-line PARRNe mass-separator operating with the ALTO facility. The fission fragments are produced at the interaction of the 50 MeV electron beam delivered by the ALTO linear accelerator with a thick target of uranium in a standard UC x form. The oven is connected to a W ionizer heated up to 2000 C degrees that selectively ionizes alkalis but also elements with low ionization potentials such as Ga. The ions are accelerated through 30 kV and magnetically mass-separated before being implanted on a mylar tape close to the detection setup, so that this system allows us to study β and β-n decays of 79,80,82,83,84,85 Ga.The data analysis have produced new results concerning the decays of 80 Ga, 84 Ga and 84 Ge. For 80 Ga, the existence of an isomeric state has been confirmed and two different half-lives were measured for the ground state and the isomer. Furthermore, the analysis of 84 Ga decay confirmed two states and allowed us to

  17. Fusion-fission probabilities, cross sections, and structure notes of superheavy nuclei

    International Nuclear Information System (INIS)

    Kowal, Michał; Cap, Tomasz; Jachimowicz, Piotr; Skalski, Janusz; Siwek-Wilczyńska, Krystyna; Wilczyński, Janusz

    2016-01-01

    Fusion – fission probabilities in the synthesis of heaviest elements are discussed in the context of the latest experimental reports. Cross sections for superheavy nuclei are evaluated using the “Fusion by Diffusion” (FBD) model. Predictive power of this approach is shown for experimentally known Lv and Og isotopes and predictions given for Z = 119, 120. Ground state and saddle point properties as masses, shell corrections, pairing energies, and deformations necessary for cross-section estimations are calculated systematically within the multidimensional microscopic-macroscopic method based on the deformed Woods-Saxon single-particle potential. In the frame of the FBD approach predictions for production of elements heavier than Z = 118 are not too optimistic. For this reason, and because of high instability of superheavy nuclei, we comment on some structure effects, connected with the K-isomerism phenomenon which could lead to a significant increase in the stability of these systems.

  18. Structure of exotic nuclei and superheavy elements in meson field theory

    International Nuclear Information System (INIS)

    Linn, Khin Nyan

    2008-07-01

    In this work the nuclear structure of exotic nuclei and superheavy nuclei is studied in a relativistic framework. In the relativistic mean-field (RMF) approximation, the nucleons interact with each other through the exchange of various effective mesons (scalar, vector, isovector-vector). Ground state properties of exotic nuclei and superheavy nuclei are studied in the RMF theory with the three different parameter sets (ChiM,NL3,NL-Z2). Axial deformation of nuclei within two drip lines are performed with the parameter set (ChiM). The position of drip lines are investigated with three different parameter sets (ChiM,NL3,NL-Z2) and compared with the experimental drip line nuclei. In addition, the structure of hypernuclei are studied and for a certain isotope, hyperon halo nucleus is predicted. (orig.)

  19. α-decay chains and cluster-decays of superheavy 269-27110 nuclei

    International Nuclear Information System (INIS)

    Sushil Kumar; Rajesh Kumar; Balasubramaniam, M.; Gupta, Raj K.

    2001-01-01

    Due to the availability of radioactive nuclear beams (RNB) and the advancement in accelerator technology, it is now possible to synthesize very heavy elements (Z> 100), called superheavy elements. It is a well established fact that these superheavy elements, due to their shorter lifetime, decay via successive alpha emissions and at a later stage undergo spontaneous fission. Several such decay chains are now observed. An attempt is made to fit all such known decay chains and the results of the three observed α-decay chains of Z=110 ( 269-271 10) nuclei are presented. The model used is the preformed cluster model (PCM). Also, an attempt is made for the first time to find the possibility of any branching to heavy-cluster emissions in these chains

  20. Structure of exotic nuclei and superheavy elements in meson field theory

    Energy Technology Data Exchange (ETDEWEB)

    Linn, Khin Nyan

    2008-07-15

    In this work the nuclear structure of exotic nuclei and superheavy nuclei is studied in a relativistic framework. In the relativistic mean-field (RMF) approximation, the nucleons interact with each other through the exchange of various effective mesons (scalar, vector, isovector-vector). Ground state properties of exotic nuclei and superheavy nuclei are studied in the RMF theory with the three different parameter sets (ChiM,NL3,NL-Z2). Axial deformation of nuclei within two drip lines are performed with the parameter set (ChiM). The position of drip lines are investigated with three different parameter sets (ChiM,NL3,NL-Z2) and compared with the experimental drip line nuclei. In addition, the structure of hypernuclei are studied and for a certain isotope, hyperon halo nucleus is predicted. (orig.)

  1. Synthesis of superheavy elements: Uncertainty analysis to improve the predictive power of reaction models

    OpenAIRE

    Lu , H.; Boilley , D.; Abe , Y.; Shen , C.

    2016-01-01

    13 pages, 13 figures, submitted for publication in PRC; International audience; Background: Synthesis of super-heavy elements is performed by heavy-ion fusion-evaporation reactions. However , fusion is known to be hindered with respect to what can be observed with lighter ions. Thus some delicate ambiguities remain on the fusion mechanism that eventually lead to severe discrepancies in the calculated formation probabilities coming from different fusion models. Purpose: In the present work, we...

  2. Barium isotopes in Allende meteorite - Evidence against an extinct superheavy element

    Science.gov (United States)

    Lewis, R. S.; Anders, E.; Shimamura, T.; Lugmair, G. W.

    1983-01-01

    Carbon and chromite fractions from the Allende meteorite that contain isotopically anomalous xenon-131 to xenon-136 (carbonaceous chondrite fission or CCF xenon) at up to 5 x 10 to the 11th atoms per gram show no detectable isotopic anomalies in barium-130 to barium-138. This rules out the possibility that the CCF xenon was formed by in situ fission of an extinct superheavy element. Apparently the CCF xenon and its carbonaceous carrier are relics from stellar nucleosynthesis.

  3. Super-heavy dark matter – Towards predictive scenarios from inflation

    Energy Technology Data Exchange (ETDEWEB)

    Kannike, Kristjan [National Institute of Chemical Physics and Biophysics, Rävala 10, 10143 Tallinn (Estonia); Racioppi, Antonio, E-mail: antonio.racioppi@kbfi.ee [National Institute of Chemical Physics and Biophysics, Rävala 10, 10143 Tallinn (Estonia); Raidal, Martti [National Institute of Chemical Physics and Biophysics, Rävala 10, 10143 Tallinn (Estonia); Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu (Estonia)

    2017-05-15

    A generic prediction of the Coleman–Weinberg inflation is the existence of a heavy particle sector whose interactions with the inflaton, the lightest state in this sector, generate the inflaton potential at loop level. For typical interactions the heavy sector may contain stable states whose relic abundance is generated at the end of inflation by the gravity alone. This general feature, and the absence of any particle physics signal of dark matter so far, motivates us to look for new directions in the dark sector physics, including scenarios in which dark matter is super-heavy. In this article we study the possibility that the dark matter is even heavier than the inflaton, its existence follows from the inflaton dynamics, and its abundance today is naturally determined by the weakness of gravitational interaction. This implies that the super-heavy dark matter scenarios can be tested via the measurements of inflationary parameters and/or the CMB isocurvature perturbations and non-Gaussianities. We explicitly work out details of three Coleman–Weinberg inflation scenarios, study the systematics of super-heavy dark matter production in those cases, and compute which parts of the parameter spaces can be probed by the future CMB measurements.

  4. Microstructure Evolution and Surface Cracking Behavior of Superheavy Forgings during Hot Forging

    Directory of Open Access Journals (Sweden)

    Zhenhua Wang

    2018-01-01

    Full Text Available In recent years, superheavy forgings that are manufactured from 600 t grade ingots have been applied in the latest generation of nuclear power plants to provide good safety. However, component production is pushing the limits of the current free-forging industry. Large initial grain sizes and a low strain rate are the main factors that contribute to the deformation of superheavy forgings during forging. In this study, 18Mn18Cr0.6N steel with a coarse grain structure was selected as a model material. Hot compression and hot tension tests were conducted at a strain rate of 10−4·s−1. The essential nucleation mechanism of the dynamic recrystallization involved low-angle grain boundary formation and subgrain rotation, which was independent of the original high-angle grain boundary bulging and the presence of twins. Twins were formed during the growth of dynamic recrystallization grains. The grain refinement was not obvious at 1150°C. A lowering of the deformation temperature to 1050°C resulted in a fine grain structure; however, the stress increased significantly. Crack-propagation paths included high-angle grain boundaries, twin boundaries, and the insides of grains, in that order. For superheavy forging, the ingot should have a larger height and a smaller diameter.

  5. Super-heavy dark matter – Towards predictive scenarios from inflation

    Directory of Open Access Journals (Sweden)

    Kristjan Kannike

    2017-05-01

    Full Text Available A generic prediction of the Coleman–Weinberg inflation is the existence of a heavy particle sector whose interactions with the inflaton, the lightest state in this sector, generate the inflaton potential at loop level. For typical interactions the heavy sector may contain stable states whose relic abundance is generated at the end of inflation by the gravity alone. This general feature, and the absence of any particle physics signal of dark matter so far, motivates us to look for new directions in the dark sector physics, including scenarios in which dark matter is super-heavy. In this article we study the possibility that the dark matter is even heavier than the inflaton, its existence follows from the inflaton dynamics, and its abundance today is naturally determined by the weakness of gravitational interaction. This implies that the super-heavy dark matter scenarios can be tested via the measurements of inflationary parameters and/or the CMB isocurvature perturbations and non-Gaussianities. We explicitly work out details of three Coleman–Weinberg inflation scenarios, study the systematics of super-heavy dark matter production in those cases, and compute which parts of the parameter spaces can be probed by the future CMB measurements.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rajeswari, N.S. [Bharathiar University, Department of Physics, Coimbatore (India); Avinashilingam Institute for Home Science and Higher Education for Women - University, Department of Physics, Coimbatore (India); Balasubramaniam, M. [Bharathiar University, Department of Physics, Coimbatore (India)

    2014-06-15

    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 {sup 157}Ta, {sup 166}Ir, {sup 167}Ir, {sup 176}Tl and {sup 177}Tl, 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, {sup 12}C, {sup 20}Ne and {sup 24}Mg 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. (orig.)

  7. Probable cluster decays from 298-336126 superheavy nuclei

    International Nuclear Information System (INIS)

    Priyanka, B.; Santhosh, K.P.

    2015-01-01

    The present paper deals with an investigation on the cluster decay of even clusters 4 He, 8,10 Be, 14 C, 18,20,22 O , 22,24,26 Ne, 28,30 Mg and odd clusters 15 N, 23 F, 25 Ne, 29 Mg from both the even-even and even-odd isotopes of Z=126, which has helped in predicting the neutron magicity beyond N=126

  8. Penning-trap mass spectrometry of radioactive, highly charged ions. Measurements of neutron-rich Rb and Sr nuclides for nuclear astrophysics and development of a novel Penning trap for cooling highly charged ions

    International Nuclear Information System (INIS)

    Simon, Vanessa Veronique

    2012-01-01

    High-precision atomic mass measurements are vital for the description of nuclear structure, investigations of nuclear astrophysical processes, and tests of fundamental symmetries. The neutron-rich A ∼ 100 region presents challenges for modeling the astrophysical r-process because of sudden nuclear shape transitions. This thesis reports on high-precision masses of short-lived neutron-rich 94,97,98 Rb and 94,97-99 Sr isotopes using the TITAN Penning-trap mass spectrometer at TRIUMF. The isotopes were charge-bred to q = 15+; uncertainties of less than 4 keV were achieved. Results deviate by up to 11σ compared to earlier measurements and extend the region of nuclear deformation observed in the A∼100 region. A parameterized r-process model network calculation shows that mass uncertainties for the elemental abundances in this region are now negligible. Although beneficial for the measurement precision, the charge breeding process leads to an increased energy spread of the ions on the order of tens of eV/q. To eliminate this drawback, a Cooler Penning Trap (CPET) has been developed as part of this thesis. The novel multi-electrode trap structure of CPET forms nested potentials to cool HCI sympathetically using either electrons or protons to increase the overall efficiency and precision of the mass measurement. The status of the off-line setup and initial commissioning experiments are presented.

  9. New Fragment Separation Technology for Superheavy Element Research

    International Nuclear Information System (INIS)

    Shaughnessy, D A; Moody, K J; Henderson, R A; Kenneally, J M; Landrum, J H; Lougheed, R W; Patin, J B; Stoyer, M A; Stoyer, N J; Wild, J F; Wilk, P A

    2008-01-01

    This project consisted of three major research areas: (1) development of a solid Pu ceramic target for the MASHA separator, (2) chemical separation of nuclear decay products, and (3) production of new isotopes and elements through nuclear reactions. There have been 16 publications as a result of this project, and this collection of papers summarizes our accomplishments in each of the three areas of research listed above. The MASHA (Mass Analyzer for Super-Heavy Atoms) separator is being constructed at the U400 Cyclotron at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia. The purpose of the separator is to physically separate the products from nuclear reactions based on their isotopic masses rather than their decay characteristics. The separator was designed to have a separation between isotopic masses of ±0.25 amu, which would enable the mass of element 114 isotopes to be measured with outstanding resolution, thereby confirming their discovery. In order to increase the production rate of element 114 nuclides produced via the 244 Pu+ 48 Ca reaction, a new target technology was required. Instead of a traditional thin actinide target, the MASHA separator required a thick, ceramic-based Pu target that was thick enough to increase element 114 production while still being porous enough to allow reaction products to migrate out of the target and travel through the separator to the detector array located at the back end. In collaboration with UNLV, we began work on development of the Pu target for MASHA. Using waste-form synthesis technology, we began by creating zirconia-based matrices that would form a ceramic with plutonium oxide. We used samarium oxide as a surrogate for Pu and created ceramics that had varying amounts of the starting materials in order to establish trends in material density and porosity. The results from this work are described in more detail in Refs. [1,4,10]. Unfortunately, work on MASHA was delayed in Russia because it was found that

  10. Nuclear structure studies towards superheavy elements and perspectives with AGATA

    International Nuclear Information System (INIS)

    Korichi, A.

    2005-01-01

    A variety of theoretical approaches have been used to calculate the shell closure of spherical Super Heavy Elements (SHE) but the predictions of the location of the 'island of stability' vary from Z=114 to 120 and 126, with neutron numbers around N=172 or N=184 depending on the model employed. A deformed minimum around Z=108 and N=162 is predicted and an increase of the half-life of Hassium (Z=108) is experimentally observed when approaching the neutron number N=162. Super heavy nuclei are produced with very low cross-section (a few picobarns) and this makes their spectroscopic study impossible with today's beam intensities and detectors. However, important information can be obtained from the structure of mid-shell deformed nuclei (Z∼104) where selected single particle orbitals, which lie close to the spherical shell gap in SHE, are close to the Fermi level. The information will come from decay and in-beam spectroscopy. A promising area of progress, using the state-of-the art instruments, is represented by the observation of rotational gamma-ray transitions in No and Fm isotopes showing the deformed character of these nuclei. One of the objectives and focus of the nuclear structure community is related to the investigation of Single particle excitations beyond the N=152 neutron gap and collective properties of heavier systems towards Z∼104. The IN2P3-JINR collaboration has launched a project of electron and gamma-ray spectroscopy studies of heavy nuclei at the FLNR. This project benefits from the radioactive actinide targets uniquely available at Dubna and from the very intense stable beams provided by the U400 cyclotron. This offers a unique opportunity for the study of nuclei above Z=100 along an isotopic chain approaching N=162. In this contribution, the emphasis will be on the GABRIELA project and its issues. I will finally point out the perspectives with the new generation of gamma detectors such as AGATA

  11. Validation and Comparison of the Therapeutic Efficacy of Boron Neutron Capture Therapy Mediated By Boron-Rich Liposomes in Multiple Murine Tumor Models

    Directory of Open Access Journals (Sweden)

    Charles A Maitz

    2017-08-01

    Full Text Available Boron neutron capture therapy (BNCT was performed at the University of Missouri Research Reactor in mice bearing CT26 colon carcinoma flank tumors and the results were compared with previously performed studies with mice bearing EMT6 breast cancer flank tumors. Mice were implanted with CT26 tumors subcutaneously in the caudal flank and were given two separate tail vein injections of unilamellar liposomes composed of cholesterol, 1,2-distearoyl-sn-glycer-3-phosphocholine, and K[nido-7-CH3(CH215–7,8-C2B9H11] in the lipid bilayer and encapsulated Na3[1-(2`-B10H9-2-NH3B10H8] within the liposomal core. Mice were irradiated 30 hours after the second injection in a thermal neutron beam for various lengths of time. The tumor size was monitored daily for 72 days. Despite relatively lower tumor boron concentrations, as compared to EMT6 tumors, a 45 minute neutron irradiation BNCT resulted in complete resolution of the tumors in 50% of treated mice, 50% of which never recurred. Median time to tumor volume tripling was 38 days in BNCT treated mice, 17 days in neutron-irradiated mice given no boron compounds, and 4 days in untreated controls. Tumor response in mice with CT26 colon carcinoma was markedly more pronounced than in previous reports of mice with EMT6 tumors, a difference which increased with dose. The slope of the dose response curve of CT26 colon carcinoma tumors is 1.05 times tumor growth delay per Gy compared to 0.09 times tumor growth delay per Gy for EMT6 tumors, indicating that inherent radiosensitivity of tumors plays a role in boron neutron capture therapy and should be considered in the development of clinical applications of BNCT in animals and man.

  12. Observation of superheavy primary cosmic ray nuclei with solid state track detectors and x-ray films

    International Nuclear Information System (INIS)

    Doke, Tadayoshi; Hayashi, Takayoshi; Ito, Kensai; Yanagimachi, Tomoki; Kobayashi, Shigeru.

    1977-01-01

    The measurements of energy spectra and the nuclear charge distribution of superheavy nuclei heavier than iron in primary cosmic ray can provide information on the origin, propagation and life time of the cosmic ray. Since incident particles are in the region of relativistic velocity (the low energy cosmic ray below the cutoff energy is forbidden from entering), the charges of cosmic ray nuclei can be determined without knowing the energy of particles. The balloon-borne solid state track detector and plastic and X-ray films were employed for the detection of superheavy cosmic ray, and the five events were detected with the cellulose nitrate film. The flux of superheavy nuclei is predicted from the present analysis. (Yoshimori, M.)

  13. Search for superheavy elements in the reaction 238U+9.6 MeV/N 63Cu,65Cu

    International Nuclear Information System (INIS)

    Esterlund, R.A.; Molzahn, D.; Brandt, R.; Patzelt, P.; Vater, P.; Boos, A.H.

    1976-01-01

    According to calculations of NIX and others, the formation of superheavy elements might occur in heavy-ion reaction systems such as the one under investigation in the present work i.e., 238 U + 63 Cu and 65 Cu at 9.6 MeV/nucleon. Since previous experiments have indicated that upper limits to the production cross-section for superheavy elements are extremely low, two rather long irradiations of 27 hrs and 42 hrs, respectively, have been carried out at the University of Manchester LINAC. The first run has already been reported on in the literature. In the case of the second run, after chemical separation into HgS, CdS, and La(OH) 3 fractions, the samples were assayed simultaneously and continuously over a period of 6 months for alpha- and spontaneous-fission activity, using Si surface-barrier detector. Each sample was at the same time mounted on mica, for the purpose of scanning for fission tracks at a later date. No indications from the data have so far been found that superheavy elements were produced. Possible reasons for the failure to detect superheavy elements in this experiment are: The half-life of any product is either too short (a few hours) or too long (a few years); the chemical properties of the superheavy elements are very different from those predicted; the position of the superheavy island is not where it is commonly assumed to be and may, for example, be at Z>=114 and N>=184, as predicted by ROUBEN et al. (T.G.)

  14. Identification of the neutron-rich nuclides /sup 147; 148/Ba and half- life determination of the heavy isotopes of Rb, Sr, Y, Cs, Ba and La

    CERN Document Server

    Amiel, S; Nir-El, Y; Shmid, M

    1976-01-01

    The neutron nuclides /sup 147; 148/Ba were produced in the thermal neutron induced fission of /sup 235/U. A new surface ionization integrated target ion source operating at temperatures in the region of 1800 degrees C permits the measurement of half-lives of isotopes down to about 0.1 sec due to the very fast release of atoms from the target. Isotopes of Rb, Sr, Cs, and Ba were separated by positive surface ionization and their half-lives measured using beta activity detected by a silicon surface barrier detector with a depletion depth of 300 mu . The isotopes /sup 147/Ba and /sup 148/Ba were identified for the first time and their half-lives were found to be 0.72+or-0.07 sec and 0.47+or-0.20 sec, respectively. (0 refs).

  15. Many-particle and many-hole states in neutron-rich Ne isotopes related to broken N=20 shell closure

    International Nuclear Information System (INIS)

    Kimura, Masaaki; Horiuchi, Hisashi

    2004-01-01

    The low-lying level structures of 26 Ne, 28 Ne and 30 Ne which are related to the breaking of the N=20 shell closure have been studied in the framework of the deformed-basis anti-symmetrized molecular dynamics plus generator coordinate method using the Gogny D1S force. The properties of the many-particle and many-hole states are studied as well as that of the ground band. We predict that the negative-parity states, in which neutrons are promoted into the pf-orbit from the sd orbit, have a small excitation energy in the cases of 28 Ne and 30 Ne. We regard this to be a typical phenomena accompanying the breaking of the N=20 shell closure. It is also found that the neutron 4p4h structure of 30 Ne appears at low excitation energy, which contains α + 16 O correlations. (author)

  16. Fission times studies of the Z=124 superheavy nucleus by X-ray fluorescence

    International Nuclear Information System (INIS)

    Airiau, Maud

    2016-01-01

    Since the 1960's nuclear structure model have predicted the existence of an island of stability of superheavy elements. It should be located around the next magic numbers expected at N=172 or 184 and between Z=114 and 126 depending on the model. Very high fission barrier of a few MeV are predicted to be generated by microscopic effects for those nuclei for which large fission times distributions extended to very high fission times are induced. Fission time measurements of the superheavy element Z=124 have been made by us using the X-ray fluorescence technique, a method based on the filling of inner-shell electronic vacancies created during the collision leading to the formation of the compound nucleus. The aim of this experiment was to detect in coincidence both fission fragments and characteristic X-rays from the Z=124, created by the reaction 238 U+ 70,76 Ge. The main difficulty was to identify those X-rays due to the fact that gamma-rays from fission fragments were emitted in the same energy range, which affected our photon multiplicities for any fragment selection. This new difficulty brings an important limitation to the study of some particular superheavy elements by the X-ray fluorescence method. K X-rays spectra have been simulated using MCDF (Multi-Configuration-Dirac-Fock) and then compared to the experimental ones in order to get a maximal K X-ray multiplicity compatible with our data. The extracted results were about 6-7% for 76 Ge and from 12 to 14% for 70 Ge. Those values remain compatible with the experimental signature of long lifetime component observed for the same system but using a blocking technique in single crystals. (author) [fr

  17. 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

    International Nuclear Information System (INIS)

    Nayak, R.C.; Pattnaik, S.

    2015-01-01

    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 β 2 , the ratio of β- 2 to the Weisskopf single-particle β 2(sp) and the intrinsic electric quadrupole moment Q 0 , 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 30,32 Ne, 34 Mg, 60 Ti, 42,62,64 Cr, 50,68 Fe, 52,72 Ni, 72,70,96 Kr, 74,76 Sr, 78,80,106,108 Zr, 82,84,110,112 Mo, 140 Te, 144 Xe, 148 Ba, 122 Ce, 128,156 Nd, 130,132,158,160 Sm and 138,162,164,166 Gd, whose values of β 2 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. (author)

  18. Superheavy contributions to FCNC in the flipped SU(5) x U(1)

    Energy Technology Data Exchange (ETDEWEB)

    Gabbiani, F.; Masiero, A.

    1988-08-04

    In the supersymmetric GUT's the presence of the superheavy fields yields new contributions to flavour-changing neutral-current effects at low energy. We analyse this phenomenon in the context of the flipped SU(5) x U(1) superstring (-inspired) model. We show that possibly sizeable flavour leptonic changes (..mu.. -> e..gamma.., ..mu.. -> eeanti e, ..mu..-e conversion in nuclei) are generated. K-anti K, B-anti B mixings and b -> s..gamma.. constrain new couplings at the superlarge scale, which are unrelated to the standard Yukawa coefficients.

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

    International Nuclear Information System (INIS)

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

    2011-01-01

    Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of β 6 deformation, we find remarkable effects of the high-order deformation on the high-K isomers in 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 β 6 deformation significantly improves the description of the very heavy high-K isomers.

  20. Superheavy particles in cosmology and evolution of inhomogeneities in the early universe

    International Nuclear Information System (INIS)

    Khlopov, M. Yu.; Polnarev, A.G.

    1983-01-01

    The stages of dominance of superheavy metastable particles, predicted by GUTs, are shown to result in the formation of primordial black holes (PBH) in the course of evolution of small initial inhomogeneities. The minimal probability of PBH formation is estimated. The relationship between the spectrum of these PBH, the spectrum of initial metric fluctuations and the parameters of the GUTs is established. Observational astrophysical restrictions on the PBH spectrum then provide a number of restrictions on the parameters of the GUTs depending on the amplitude of initial metric perturbations. (author)

  1. Charge quantization without superheavy masses in a Kaluza--Klein description of electromagnetism

    International Nuclear Information System (INIS)

    Ross, D.K.

    1987-01-01

    A scalar matter field coupled to general relativity and electromagnetism in a five-dimensional Kaluza--Klein model is considered. The five-dimensional space is assumed to be a fiber bundle as in the usual description of a gauge theory and not a more general manifold. Properly taking this into account allows one to use a Lagrangian density for the scalar field which includes charge quantization but not the unphysical superheavy masses found by other authors. A natural, satisfactory explanation of why charge is quantized results

  2. Theoretical Predictions of Cross-Sections of the Super-Heavy Elements

    Science.gov (United States)

    Bouriquet, B.; Kosenko, G.; Abe, Y.

    The evaluation of the residue cross-sections of reactionssynthesising superheavy elements has been achieved by the combination of the two-step model for fusion and the evaporation code (KEWPIE) for survival probability. The theoretical scheme of those calculations is presented, and some encouraging results are given, together with some difficulties. With this approach, the measured excitation functions of the 1n reactions producing elements with Z=108, 110, 111 and 112 are well reproduced. Thus, the model has been used to predict the cross-sections of the reactions leading to the formation of the elements with Z=113 and Z=114.

  3. Theoretical predictions of cross-sections of the super-heavy elements

    International Nuclear Information System (INIS)

    Bouriquet, B.; Abe, Y.; Kosenko, G.

    2004-01-01

    The evaluation of the residue cross-sections of reactions synthesising superheavy elements has been achieved by the combination of the two-step model for fusion and the evaporation code (KEWPIE) for survival probability. The theoretical scheme of those calculations is presented, and some encouraging results are given, together with some difficulties. With this approach, the measured excitation functions of the 1n reactions producing elements with Z = 108, 110, 111 and 112 are well reproduced. Thus, the model has been used to predict the cross-sections of the reactions leading to the formation of the elements with Z = 113 and Z = 114. (author)

  4. What can we learn from the fission time of the super-heavy elements?

    OpenAIRE

    Boilley, D.; Marchix, A.; Wilgenbus, D.; Lallouet, Y.; Gimbert, F.; Abe, Y.

    2007-01-01

    International audience; Recent experiments performed at GANIL with a crystal blocking technique have shown direct evidences of long fission times in the Super-Heavy Elements (SHE) region. Aimed to localize the SHE island of stability, can these experiments give access to the fission barrier and then to the shell-correction energy? In this paper, we calculate the fission time of heavy elements by using a new code, KEWPIE2, devoted to the study of the SHE.We also investigate the effect of poten...

  5. Status of the low-energy super-heavy element facility at RIKEN

    Energy Technology Data Exchange (ETDEWEB)

    Schury, P., E-mail: schury@riken.jp [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Wada, M.; Ito, Y. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Arai, F. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Institute of Physics, University of Tsukuba, Tsukuba City, Ibaraki (Japan); Kaji, D. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Kimura, S. [Institute of Physics, University of Tsukuba, Tsukuba City, Ibaraki (Japan); Morimoto, K.; Haba, H. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Jeong, S. [Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan); Koura, H. [Advanced Science Research Center, Japan Atomic Energy Agency, Ibaraki 319-1195 (Japan); Miyatake, H. [Institute of Particle and Nuclear Studies (IPNS), High Energy Accelerator Research Organization (KEK), Ibaraki 305-0801 (Japan); Morita, K.; Reponen, M. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Ozawa, A. [Institute of Physics, University of Tsukuba, Tsukuba City, Ibaraki (Japan); Sonoda, T.; Takamine, A. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Wollnik, H. [Dept. Chemistry and BioChemistry, New Mexico State University, Las Cruces, NM (United States)

    2016-06-01

    In order to investigate nuclei produced via fusion–evaporation reactions, especially super-heavy elements (SHE), we have begun construction of a facility for conversion of fusion–evaporation residues (EVR) to low-energy beams. At the base of this facility is a small cryogenic gas cell utilizing a traveling wave RF-carpet, located directly following the gas-filled recoil ion separator GARIS-II, which will thermalize EVRs to convert them into ion beams amenable to ion trapping. We present here the results of initial studies of this small gas cell.

  6. Superheavy-element fission tracks in iron meteorites, and reply by Bull, R.K

    International Nuclear Information System (INIS)

    Runcorn, S.K.

    1980-01-01

    Comment is made on the lack of superheavy element (SHE) fission tracks observed in silicates from the class IA Odessa iron meteorite by Bull (Nature; 282:393 (1979)). Two explanations are suggested. Firstly, a thermal history for Odessa can be constructed in which the meteorite reaches track retention temperatures only after a time corresponding to many half lives for the SHEs (taken to be approximately 100 Myr) has elapsed and secondly that the IA irons never took up many SHEs. These suggestions are discussed in a reply by Bull. (U.K.)

  7. True ternary fission and quasifission of superheavy nuclear systems

    Directory of Open Access Journals (Sweden)

    Greiner Walter

    2011-10-01

    Full Text Available We found that a true ternary fission with formation of a heavy third fragment (a new kind of radioactivity is quite possible for superheavy nuclei due to the strong shell effects leading to a three-body clusterization with the two doubly magic tin-like cores. The three-body quasifission process could be even more pronounced for giant nuclear systems formed in collisions of heavy actinide nuclei. In this case a three-body clusterization might be proved experimentally by detection of two coincident lead-like fragments in low-energy U+U collisions.

  8. Therapeutic efficacy of boron neutron capture therapy mediated by boron-rich liposomes for oral cancer in the hamster cheek pouch model

    Energy Technology Data Exchange (ETDEWEB)

    Heber, Elisa M. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Hawthorne, M. Frederick [Univ. of Missouri, Columbia, MO (United States). International Inst. of Nano and Molecular Medicine; Kueffer, Peter J. [Univ. of Missouri, Columbia, MO (United States). International Inst. of Nano and Molecular Medicine; Garabalino, Marcela A. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Thorp, Silvia I. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Pozzi, Emiliano C. C. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Hughes, Andrea Monti [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Maitz, Charles A. [Univ. of Missouri, Columbia, MO (United States). International Inst. of Nano and Molecular Medicine; Jalisatgi, Satish S. [Univ. of Missouri, Columbia, MO (United States). International Inst. of Nano and Molecular Medicine; Nigg, David W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Curotto, Paula [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Trivillin, Verónica A. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina); Schwint, Amanda E. [Comision Nacional de Energia Atomica (CNEA), Buenos Aires (Argentina)

    2014-11-11

    Unilamellar liposomes formulated with an equimolar mixture of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine, incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] in the lipid bilayer, and encapsulating Na3[1-(2’-B10-H9)-2-NH3B10H8] were prepared by probe sonication and investigated in vivo. Microwave assisted digestion followed by inductively coupled plasma-optical emission spectroscopy was utilized to determine the biodistribution of boron in various tissues following either a single tail vein injection or two identical injections (separated by 24 hours) of the liposomal suspension in BALB/c mice bearing EMT6 mammary adenocarcinomas in their right flank. Double-injection protocols resulted in a boron content in the tumor exceeding 50 µg of boron per gram of tissue for 48 to 72 hours subsequent to the initial injection while tumor:blood boron ratios were more ideal from 54 hours (1.9:1) to 96 hours (5.7:1) subsequent to the initial injection. Tumor bearing mice were given a double-injection of liposomes containing the 10B-enriched analogs of the aforementioned agents and subjected to a 30 minute irradiation by thermal neutrons with a flux of 8.8 x 108 (±7%) neutrons/cm2 s integrated over the energy range of 0.0 – 0.414 eV. Significant tumor response for a single BNCT treatment was demonstrated by growth curves versus a control group. Vastly diminished tumor growth was witnessed at 14 days (186% increase versus 1551% in controls) in mice that were given a second injection/radiation treatment 7 days after the first. Mice given a one hour neutron irradiation following the double-injection of liposomes had a similar response (169% increase at 14 days) suggesting that neutron fluence is the limiting factor towards BNCT efficacy in this study.

  9. Effects of 2p-2h configurations on low-energy dipole states in neutron-rich N=80, 82 and 84 isotones

    Directory of Open Access Journals (Sweden)

    Arsenyev N. N.

    2016-01-01

    Full Text Available Starting from the Skyrme interaction SLy4 we study the effects of phonon-phonon coupling on the low-energy electric dipole response in 130−134Sn, 132−136Te and 134−138Xe. Our calculations are performed within the finite-rank separable approximation, which enables one to perform quasiparticle random phase approximation calculations in very large two-quasiparticle configuration spaces. A dependence of the pygmy dipole resonance strengths on the neutron skin thickness is found. The inclusion of the two-phonon configurations gives a considerable contribution to the low-lying strength.

  10. 94 β-Decay Half-Lives of Neutron-Rich _{55}Cs to _{67}Ho: Experimental Feedback and Evaluation of the r-Process Rare-Earth Peak Formation.

    Science.gov (United States)

    Wu, J; Nishimura, S; Lorusso, G; Möller, P; Ideguchi, E; Regan, P-H; Simpson, G S; Söderström, P-A; Walker, P M; Watanabe, H; Xu, Z Y; Baba, H; Browne, F; Daido, R; Doornenbal, P; Fang, Y F; Gey, G; Isobe, T; Lee, P S; Liu, J J; Li, Z; Korkulu, Z; Patel, Z; Phong, V; Rice, S; Sakurai, H; Sinclair, L; Sumikama, T; Tanaka, M; Yagi, A; Ye, Y L; Yokoyama, R; Zhang, G X; Alharbi, T; Aoi, N; Bello Garrote, F L; Benzoni, G; Bruce, A M; Carroll, R J; Chae, K Y; Dombradi, Z; Estrade, A; Gottardo, A; Griffin, C J; Kanaoka, H; Kojouharov, I; Kondev, F G; Kubono, S; Kurz, N; Kuti, I; Lalkovski, S; Lane, G J; Lee, E J; Lokotko, T; Lotay, G; Moon, C-B; Nishibata, H; Nishizuka, I; Nita, C R; Odahara, A; Podolyák, Zs; Roberts, O J; Schaffner, H; Shand, C; Taprogge, J; Terashima, S; Vajta, Z; Yoshida, S

    2017-02-17

    The β-decay half-lives of 94 neutron-rich nuclei ^{144-151}Cs, ^{146-154}Ba, ^{148-156}La, ^{150-158}Ce, ^{153-160}Pr, ^{156-162}Nd, ^{159-163}Pm, ^{160-166}Sm, ^{161-168}Eu, ^{165-170}Gd, ^{166-172}Tb, ^{169-173}Dy, ^{172-175}Ho, and two isomeric states ^{174m}Er, ^{172m}Dy were measured at the Radioactive Isotope Beam Factory, providing a new experimental basis to test theoretical models. Strikingly large drops of β-decay half-lives are observed at neutron-number N=97 for _{58}Ce, _{59}Pr, _{60}Nd, and _{62}Sm, and N=105 for _{63}Eu, _{64}Gd, _{65}Tb, and _{66}Dy. Features in the data mirror the interplay between pairing effects and microscopic structure. r-process network calculations performed for a range of mass models and astrophysical conditions show that the 57 half-lives measured for the first time play an important role in shaping the abundance pattern of rare-earth elements in the solar system.

  11. Proton-rich nuclear statistical equilibrium

    International Nuclear Information System (INIS)

    Seitenzahl, I.R.; Timmes, F.X.; Marin-Lafleche, A.; Brown, E.; Magkotsios, G.; Truran, J.

    2008-01-01

    Proton-rich material in a state of nuclear statistical equilibrium (NSE) is one of the least studied regimes of nucleosynthesis. One reason for this is that after hydrogen burning, stellar evolution proceeds at conditions of an equal number of neutrons and protons or at a slight degree of neutron-richness. Proton-rich nucleosynthesis in stars tends to occur only when hydrogen-rich material that accretes onto a white dwarf or a neutron star explodes, or when neutrino interactions in the winds from a nascent proto-neutron star or collapsar disk drive the matter proton-rich prior to or during the nucleosynthesis. In this Letter we solve the NSE equations for a range of proton-rich thermodynamic conditions. We show that cold proton-rich NSE is qualitatively different from neutron-rich NSE. Instead of being dominated by the Fe-peak nuclei with the largest binding energy per nucleon that have a proton-to-nucleon ratio close to the prescribed electron fraction, NSE for proton-rich material near freezeout temperature is mainly composed of 56Ni and free protons. Previous results of nuclear reaction network calculations rely on this nonintuitive high-proton abundance, which this Letter explains. We show how the differences and especially the large fraction of free protons arises from the minimization of the free energy as a result of a delicate competition between the entropy and nuclear binding energy.

  12. Neutron stars

    International Nuclear Information System (INIS)

    Irvine, J.M.

    1978-01-01

    The subject is covered in chapters entitled: introduction (resume of stellar evolution, gross characteristics of neutron stars); pulsars (pulsar characteristics, pulsars as neutron stars); neutron star temperatures (neutron star cooling, superfluidity and superconductivity in neutron stars); the exterior of neutron stars (the magnetosphere, the neutron star 'atmosphere', pulses); neutron star structure; neutron star equations of state. (U.K.)

  13. Approach synthesis of superheavy nuclei from some aspects of cross section calculations

    International Nuclear Information System (INIS)

    Liu Zuhua

    2003-01-01

    Several important aspects in the cross section calculations for the synthesis of superheavy nuclei have been inquired. They are the effects of the coupled-channels, the damping of shell correction energy, the collective enhancements in the level density and the spin distributions of evaporation residues. The channel coupling of relative motion with internal degrees of freedom will enhance significantly the capture cross section at sub-barrier energies. However, recent measurements of spin distributions for the survived compound nucleus show that only low partial waves contribute to the evaporation residues, which should at least partially cancel out the enhancement due to the effects of the channel coupling. The fission barriers are determined mainly by the shell correction energy in the case of superheavy nuclei. Therefore, it is especially important to determine as accurate as possible the damping parameter which describes the decrease of the shell effects influence. In addition, the collective enhancement factor in the level density also plays a very important role in the synthesis of heavy spherical nuclei

  14. Contributions to the theory of alpha disintegration of heavy and superheavy nuclei

    International Nuclear Information System (INIS)

    Tarnoveanu, G.I.

    1977-01-01

    Alpha disintegration of heavy and super-heavy spherical nuclei is studied. When the new calculation technique for alpha intensities dependent on the shell-model has been applied, a technique which allows the use of a more complex structure of the alpha particle, the detailed calculation of the alpha half-times is performed for both radioactive alpha nuclei in the lead area and for the super-heavy nuclei, by using the R matrix theory of alpha disintegration independent of the channel radius. The relative values of overlap integrals calculated by means of the intrinsic function for the Gauss and Moshinsky type alpha particle are presented, as well as a comparison between them and the experiment values for 8.6, 9.00 and 9.6 fm channel radii in the case of Po, Ra, Rn and Th isotopes. Original contributions to the alpha disintegration theory are represented by the generalization of the Taylor series method expressing the transformations to the centre of mass, and the relative distance from two particles to four particles in the same harmonic oscillator potential, and by the development of the R matrix theory for alpha disintegration independent of the channel radius in the case of complex structured alpha particles. (author)

  15. Charge-exchange resonances and restoration of Wigner’s supersymmetry in heavy and superheavy nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Lutostansky, Yu. S., E-mail: lutostansky@yandex.ru; Tikhonov, V. N. [National Research Center Kurchatov Institute (Russian Federation)

    2016-11-15

    Various facets of the question of whether Wigner’s supersymmetry [SU(4) symmetry] may be restored in heavy and superheavy nuclei are analyzed on the basis of a comparison of the results of calculations with experimental data. The energy difference between the giant Gamow–Teller resonance and the analog resonance (the difference of E{sub G} and E{sub A}) according to calculations based on the theory of finite Fermi systems is presented for the case of 33 nuclei for which experimental data are available. The calculated difference ΔE{sub G–A} of E{sub G} and E{sub A} tends to zero in heavier nuclei, showing evidence of the restoration of Wigner’s SU(4) symmetry. Also, the isotopic dependence of the Coulomb energy difference between neighboring isobaric nuclei is analyzed within the SU(4) approach for more than 400 nuclei in the mass-number range of A = 5–244. The restoration of Wigner’s SU(4) symmetry in heavy nuclei is confirmed. It is shown that the restoration of SU(4) symmetry is compatible with the possible existence of the stability island in the region of superheavy nuclei.

  16. Neutrino masses and superheavy dark matter in the 3-3-1-1 model

    Energy Technology Data Exchange (ETDEWEB)

    Huong, D.T.; Dong, P.V. [Vietnam Academy of Science and Technology, Institute of Physics, Hanoi (Viet Nam)

    2017-04-15

    In this work, we interpret the 3-3-1-1 model when the B - L and 3-3-1 breaking scales behave simultaneously as the inflation scale. This setup not only realizes the previously achieved consequences of inflation and leptogenesis, but also provides new insights in superheavy dark matter and neutrino masses. We argue that the 3-3-1-1 model can incorporate a scalar sextet, which induces both small masses for the neutrinos via a combined type I and II seesaw and large masses for the new neutral fermions. Additionally, all the new particles have large masses in the inflation scale. The lightest particle among the W-particles that have abnormal (i.e., wrong) B - L number in comparison to those of the standard model particles may be superheavy dark matter as it is stabilized by W-parity. The dark matter candidate may be a Majorana fermion, a neutral scalar, or a neutral gauge boson, which was properly created in the early universe due to gravitational effects on the vacuum or thermal production after cosmic inflation. (orig.)

  17. Barrier for cold-fusion production of superheavy elements

    International Nuclear Information System (INIS)

    Ichikawa, Takatoshi; Iwamoto, Akira; Moeller, Peter; Sierk, Arnold J.

    2005-01-01

    We estimate the fusion-barrier height B fu (two-body) for approaching ions in cold-fusion reactions in a model where the projectile deformation and quadrupole zero-point vibrational energy are taken into account. This barrier height is defined as the barrier energy at the target and projectile separation distance where an original oblate deformation of projectile and/or target caused by a repulsive Coulomb force turns into a large prolate deformation caused by the attractive nuclear force as the target and projectile come closer. The instability develops before touching because the attractive short-range nuclear force overcomes the repulsive Coulomb force and the shape-stabilizing effect of shell structure. The shell structure of the doubly magic 208 Pb target is sufficiently strong that its shape remains very close to spherical in all cases studied here. The fusion potential for approaching ions in the two-body channel is calculated in the macroscopic-microscopic model with the quadrupole vibrational zero-point energy obtained in the WKB approximation. We compare our results with data from 10 experimental cold-fusion reactions and with the Bass barriers. Differences and similarities between the Yukawa-plus-exponential model and the Bass model are discussed. We also calculate five-dimensional potential-energy surfaces for the single compound system and show that well-established fission and fusion valleys are both present. For heavy systems, B fu (two-body) becomes lower than the fission barrier just beyond the ground state of the compound system. In the vicinity of this transition, the optimum collision energy for formation of evaporation residues can be expected to depend in a delicate fashion on the interplay among B fu (two-body) , the fusion valley, the fission barrier of the compound system, and the one- and two-neutron separation energies S 1n and S 2n . We discuss these issues in detail and calculate fission-barrier heights. Except for reactions in which

  18. The search for super-heavy ions; La quete des noyaux super-lourds

    Energy Technology Data Exchange (ETDEWEB)

    Grevy, St. [Grand Accelerateur National d' Ions Lourds (GANIL-LPC), IN2P3 - CNRS / Ensicaen et Universite, 14 - Caen (France); Stodel, Ch. [Grand Accelerateur National d' Ions Lourds (GANIL), CEA-CNRS-IN2P3, 14 - Caen (France)

    2003-07-01

    The authors present the search for heavy nuclei, they briefly draw a historical review of the production of heavy isotopes and then describe the means and possibilities the French GANIL (national great accelerator of heavy ions) facility offers. The different steps of the experimental process are described: production, selection, detection and identification. The production cross-sections are so weak that every parameter involved in the production process has to be optimized. It appears that the limit of our technological knowledge has been reached and unless an important technical step forward it seems impossible to go down below the pico-barn (10{sup -12}*10{sup -24} cm{sup 2}) for production cross-sections. The 2 remaining ways to improve the situation are: 1) to increase the intensity of the incident particle beam (today we have < 10{sup 13} pps), this implies that an important development about accelerators and ion sources has to be achieved, 2) the other way is to use radioactive ion beams, the excess of neutrons of the incident ion gives a better production rate and will allow us to reach the neutron-rich part of the stability island. (A.C.)

  19. Neutron-rich nuclei produced at zero degrees in damped collisions induced by a beam of 18O on a 238U target

    Science.gov (United States)

    Stefan, I.; Fornal, B.; Leoni, S.; Azaiez, F.; Portail, C.; Thomas, J. C.; Karpov, A. V.; Ackermann, D.; Bednarczyk, P.; Blumenfeld, Y.; Calinescu, S.; Chbihi, A.; Ciemala, M.; Cieplicka-Oryńczak, N.; Crespi, F. C. L.; Franchoo, S.; Hammache, F.; Iskra, Ł. W.; Jacquot, B.; Janssens, R. V. F.; Kamalou, O.; Lauritsen, T.; Lewitowicz, M.; Olivier, L.; Lukyanov, S. M.; Maccormick, M.; Maj, A.; Marini, P.; Matea, I.; Naumenko, M. A.; de Oliveira Santos, F.; Petrone, C.; Penionzhkevich, Yu. E.; Rotaru, F.; Savajols, H.; Sorlin, O.; Stanoiu, M.; Szpak, B.; Tarasov, O. B.; Verney, D.

    2018-04-01

    Cross sections and corresponding momentum distributions have been measured for the first time at zero degrees for the exotic nuclei obtained from a beam of 18O at 8.5 MeV/A impinging on a 1 mg/cm2238U target. Sizable cross sections were found for the production of exotic species arising from the neutron transfer and proton removal from the projectile. Comparisons of experimental results with calculations based on deep-inelastic reaction models, taking into account the particle evaporation process, indicate that zero degree is a scattering angle at which the differential reaction cross section for production of exotic nuclei is at its maximum. This result is important in view of the new generation of zero degrees spectrometers under construction, such as the S3 separator at GANIL, for example.

  20. Penning-trap mass spectrometry of neutron-rich copper isotopes for probing the Z = 28 and N = 50 shell closures

    CERN Multimedia

    Manea, V

    We propose to perform a Penning-trap mass measurement of $^{79}$Cu. This exotic N = 50 isotone is the last frontier before the doubly-magic $^{78}$Ni and will greatly improve our knowledge of shell evolution. In the same run, we propose $^{77-78}$Cu mass measurements, as well as the search for a possible isomer in $^{76m}$Cu. The data will help to clarify the structure of the odd proton in the Cu isotopes, the influence on the Z = 28 proton core of the νg$_{9/2}$ orbital filling and the impact of the proton-neutron residual interaction on the strength of the N = 50 shell closure.

  1. Study of the nuclear structure far from stability: Coulomb excitation of neutron-rich Rb isotopes around N=60; Production of nuclear spin polarized beams using the tilted foils technique

    International Nuclear Information System (INIS)

    Sotty, C.

    2013-01-01

    The underlying structure in the region A ∼ 100, N ∼ 60 has been under intensive and extensive investigation, mainly by β-decay and γ-ray spectroscopy from fission processes. Around N ∼ 60, by adding just few neutrons, protons a rapid shape change occurs from spherical-like to well deformed g.s. shape. Shape coexistence has been observed in the Sr and Zr nuclei, and is expected to take place in the whole region. The mechanisms involved in the appearance of the deformation is not well understood. The interplay between down-sloping and up-sloping neutron Nilsson orbital is evoked as one of the main reasons for the sudden shape change. However, a clear identification of the active proton and neutron orbitals was still on-going. For that purpose, the neutron rich 93;95;97;99 Rb isotopes have been studied by Coulomb excitation at CERN (ISOLDE) using the REX-ISOLDE post-accelerator and the MINIBALL setup. The completely unknown structures of 97;99 Rb have been populated and observed. Prompt γ-ray coincidences of low-lying states have been observed and time-correlated in order to build level schemes. The associated transition strengths have been extracted with the GOSIA code. The observed matrix elements of the electromagnetic operator constituted new inputs of further theoretical calculations giving new insight on the involved orbitals. The sensitivity of such experiment can be increased using nuclear spin polarized radioactive ion beam. For that purpose the Tilted Foils Technique (TFT) of polarization has been investigated at CERN. This technique consists to spin polarize the ion beam, passing through thin foils tilted at an oblique angle with respect to the beam direction. The initially obtained atomic polarization is transferred to the nucleus by hyperfine interaction. This technique does not depend on the chemical nature of the element. Short lived nuclei can be polarized in-flight without any need to be stopped in a catcher. It opens up the possibility to

  2. Development of an on-line high-temperature ion source for neutron-rich fission products at TRIGA-SPEC

    Energy Technology Data Exchange (ETDEWEB)

    Renisch, Dennis [Institut fuer Kernchemie, Johannes Gutenberg-Universitaet Mainz (Germany); Collaboration: TRIGA-SPEC-Collaboration

    2012-07-01

    The TRIGA-SPEC experiment at the TRIGA Mainz research reactor aims to determine ground-state properties of exotic nuclides. It includes the Penning-trap mass spectrometer TRIGA-TRAP and the collinear laser spectroscopy setup TRIGA-LASER. Nuclides of interest are produced in the neutron-induced fission of suitable actinide isotopes, thermalized in a gas-filled volume and transported to an on-line ion source with a gas-jet. The ion source being constructed has two operation modes: a high-temperature surface ionization mode and a hollow cathode plasma mode. It is expected that the surface mode will yield a high ionization efficiency for certain elements, in the order of at least several percent, whereas the plasma mode has the advantage, that more elements can be ionized but with lower efficiency compared to the surface ionization mode. The current status of the TRIGA-SPEC experiments and the present performance of the on-line ion source are presented.

  3. Ground state properties of neutron-rich Mg isotopes the "island of inversion" studied with laser and $\\beta$-NMR spectroscopy

    CERN Document Server

    Kowalska, M

    2006-01-01

    Studies in regions of the nuclear chart in which the model predictions of properties of nuclei fail can bring a better understanding of the strong interaction in the nuclear medium. To such regions belongs the so called "island of inversion" centered around Ne, Na and Mg isotopes with 20 neutrons in which unexpected ground-state spins, large deformations and dense low-energy spectra appear. This is a strong argument that the magic N=20 is not a closed shell in this area. In this thesis investigations of isotope shifts of stable $^{24-26}$Mg, as well as spins and magnetic moments of short-lived $^{29,31}$Mg are presented. The successful studies were performed at the ISOLDE facility at CERN using collinear laser and $\\beta$-NMR spectroscopy techniques. The isotopes were investigated as single-charged ions in the 280 nm transition from the atomic ground state $^2\\!$S$_{1/2}$ to one of the two lowest excited states $^2\\!$P$_{1/2 ,\\,3/2}$ using continuous wave laser beams. The isotope-shift measurements with fluor...

  4. Mass measurements of neutron-rich strontium and rubidium isotopes in the region $A \\approx 100$ and development of an electrospray ionization ion source

    CERN Document Server

    de Roubin, Antoine

    An extension of the atomic mass surface in the region $A \\approx 100$ is performed via mass measurements of the $^{100−102}$Sr and $^{100−102}$Rb isotopes with the ion-trap mass spectrometer ISOLTRAP at CERN-ISOLDE. The first direct mass measurements of $^{102}$Sr and $^{101,102}$Rb are reported here. These measurements confirm the continuation of the region of nuclear deformation with the increase of neutron number, at least as far as $N = 65$. In order to interpret the deformation in the strontium isotopic chain and to determine whether an onset of deformation is present in heavier krypton isotopes, a comparison is made between experimental values and theoretical calculations available in the literature. To complete this comparison, Hartree-Fock-Bogoliubov calculations for even and odd isotopes are also presented, illustrating the competition of nuclear shapes in the region. The development of an electrospray ionization ion source is presented. This source can deliver a large range of isobaric masses ...

  5. Investigating the nuclear structure of the neutron-rich odd-mass Fe isotopes, in the $\\beta$-decay of their parent - Mn

    CERN Document Server

    AUTHOR|(CDS)2079133; Van Duppen, Piet

    For many years the shell structure of the nucleus, originally proposed by Mayer and Haxel, predicting certain energy gaps at specific proton and/or neutron numbers, has been consistent with the experimental findings at or near the line of stability. These nuclei exhibit a sequence of magic numbers – 2, 8, 20, 28, 50, 82, which is different from the one calculated using only a Harmonic Oscillator potential: 2, 8, 20, 40, 70... The strong spin-orbit term, added to the latter potential by Mayer and Haxel, is a necessary requirement for a successful description of these quantum systems, which lowers the energy orbitals with higher spins directly affecting the l = 4 (1$g_{9/2}$) orbit by reducing the gap at N = 40 and creating the N = 50 one. With the development of more exotic radioactive beams, however, it has been observed that for nuclei away from the stability line the traditional shell gaps have weakened, while new energy gaps have emerged instead. It has been further realized that the residual nucleon- nu...

  6. On the spectroscopy of the 1ssigma-orbital in superheavy collision systems

    International Nuclear Information System (INIS)

    Stiebing, K.E.; Schmidt-Boecking, H.; Schadt, W.; Bethge, K.; Mokler, P.H.; Bosch, F.; Liesen, D.; Vincent, P.

    1982-01-01

    The probability for the emission of quasimolecular K-radiation (K-MO-radiation) in superheavy collision systems was measured in the system 208 Pb + 208 Pb as function of the scattering angle and the photon energy for incident energies of 4.3 and 4.8 MeV/u. In the present article these measurements and their evaluation are extensively described. The results are discussed with special regards to the contributions from the 1ssigma-molecular orbital, because there exists a great interest on an utmost precise knowledge of the binding energy of these most strongly bound electrons. For this a survey about the dynamical model of the emission of quasimolecular X-radiation in the configuration formalism is given. (orig./HSI) [de

  7. Binary fragmentation based studies for the near super-heavy compound nucleus {sup 256}Rf

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Meenu; Behera, B.R.; Mahajan, Ruchi; Kaur, Gurpreet; Sharma, Priya; Kapoor, Kushal; Rani, Kavita [Panjab University, Department of Physics, Chandigarh (India); Saneesh, N.; Dubey, R.; Yadav, A.; Sugathan, P.; Jhingan, A.; Chatterjee, A.; Chatterjee, M.B. [Inter University Accelerator Centre, New Delhi (India); Kumar, Neeraj; Mandal, S. [University of Delhi, Department of Physics and Astrophysics, Delhi (India); Kumar, S. [Andhra University, Department of Nuclear Physics, Visakhapatnam (India); Saxena, A.; Kailas, S. [Bhabha Atomic Research Centre, Nuclear Physics Division, Mumbai (India); Pal, Santanu [CS, Kolkata (India); Nasirov, Avazbek [JINR, Bogoliubov Laboratory of Theoretical Physics, Dubna (Russian Federation); National University, Department of Physics, Tashkent (Uzbekistan); Kayumov, Bakhodir [National University, Department of Physics, Tashkent (Uzbekistan)

    2017-06-15

    Binary fragmentation of the near super-heavy compound nucleus {sup 256}Rf has been studied through the reaction {sup 48}Ti + {sup 208}Pb at a bombarding energy well above the Coulomb barrier. For a better understanding of its reaction dynamics, the mass distribution, mass-energy distribution and mass-angle distribution of the fission fragments produced from {sup 256}Rf have been investigated thoroughly. The masses and kinetic energies of the fission fragments were reconstructed event-by-event from their measured velocities and emission angles. From the mass-energy analysis, a sizeable contribution from the asymmetric fission was observed on the edges of symmetric mass distribution. Evidence of asymmetric fission was also clued from the observed correlation between the masses and emission angles of the fission fragments. Contribution of the quasi-fission products has also been estimated by performing the theoretical dinuclear system calculations. (orig.)

  8. Ionization history of the universe as a test for superheavy dark matter particles

    International Nuclear Information System (INIS)

    Doroshkevich, A.G.; Naselsky, P.D.

    2002-01-01

    In this paper we discuss the possible distortions of the ionization history of the universe caused by an injection of nonthermal energy due to decays of hypothetical superheavy dark matter (SHDM) particles. These particles are usually considered as a possible source of ultrahigh energy cosmic rays in the framework of the top-down model. Estimates of the fraction of energy of decays converted to the UV range show that, for suitable parameters of the SHDM particles, significant distortions of the power spectra of the cosmic microwave background anisotropy appear. A comparison with the observed power spectrum allows us to restrict some properties of the SHDM particles. These decays can also increase by about 5-10 times the degree of ionization of hydrogen at redshifts z∼10-50, which essentially accelerates the formation of molecules of H 2 and the first stars during the 'dark ages'

  9. New approach to description of fusion-fission dynamics in super-heavy element formation

    International Nuclear Information System (INIS)

    Zagrebaev, V.I.

    2002-01-01

    A new mechanism of the fusion-fission process for a heavy nuclear system is proposed, which takes place in the (A 1 , A 2 ) space, where A 1 and A 2 are two nuclei, surrounded by a certain number of shared nucleons ΔA. The nuclei A 1 and A 2 gradually lose (or acquire) their individualities with increasing (or decreasing) a number of collectivized nucleons ΔA. The driving potential in the (A 1 , A 2 ) space is derived, which allows the calculation of both the probability of the compound nucleus formation and the mass distribution of fission and quasi-fission fragments in heavy ion fusion reactions. The cross sections of super-heavy element formation in the 'hot' and 'cold' fusion reactions have been calculated up to Z CN =118. (author)

  10. Search for super-heavy GUT magnetic monopoles in cosmic rays

    International Nuclear Information System (INIS)

    Shepko, M.J.

    1986-05-01

    A search for superheavy grand unified (GUT) magnetic monopoles has been performed utilizing a large (260m 2 sr) array of scintillation counters, sited underground at a depth of 1200 m.w.e. This apparatus measures both the time of flight and specific ionization of particles passing through it and has a trigger which is sensitive to prompt as well as very slowly developing pulses from the detector. No monopole events have been observed during 280 days of live time operation of this detector. An upper limit on the flux of monopoles of 4.6 x 10 -14 cm -2 sr -1 s -1 is obtained in the velocity range 8.5 x 10 -4 c to 0.012c at a 90% confidence level. 50 refs., 47 figs., 16 tabs

  11. First prompt in-beam γ-ray spectroscopy of a superheavy element: the 256Rf

    International Nuclear Information System (INIS)

    Rubert, J; Dorvaux, O; Gall, B J P; Asfari, Z; Piot, J; Greenlees, P T; Grahn, T; Herzan, A; Jakobsson, U; Jones, P; Julin, R; Juutinen, S; Andersson, L L; Cox, D M; Herzberg, R-D; Asai, M; Dechery, F; Hauschild, K; Henning, G; Heßberger, F P

    2013-01-01

    Using state-of-the-art γ-ray spectroscopic techniques, the first rotational band of a superheavy element, extending up to a spin of 20 h, was discovered in the nucleus 256 Rf. To perform such an experiment at the limits of the present instrumentation, several developments were needed. The most important of these developments was of an intense isotopically enriched 50 Ti beam using the MIVOC method. The experimental set-up and subsequent analysis allowed the 256 Rf ground-state band to be revealed. The rotational properties of the band are discussed and compared with neighboring transfermium nuclei through the study of their moments of inertia. These data suggest that there is no evidence of a significant deformed shell gap at Z = 104.

  12. On the way to unveiling the atomic structure of superheavy elements

    International Nuclear Information System (INIS)

    Laatiaoui, Mustapha

    2016-01-01

    Optical spectroscopy of the transfermium elements (atomic number Z > 100) is nowadays one of the most fascinating and simultaneously challenging tasks in atomic physics. On the one hand, key atomic and even nuclear ground-state properties may be obtained by studying the spectral lines of these heaviest elements. On the other hand, these elements have to be produced “online” by heavy-ion induced fusion-evaporation reactions yielding rates on the order of a few atoms per second at most, which renders their optical spectroscopy extremely difficult. Only recently, a first foray of laser spectroscopy into this heaviest element region was reported. Several atomic transitions in the element nobelium (Z = 102) were observed and characterized, using an ultra-sensitive and highly efficient resonance ionization technique. The findings confirm the predictions and additionally provide a benchmark for theoretical modelling. The work represents an important stepping stone towards experimental studies of the atomic structure of superheavy elements.

  13. Review of even element super-heavy nuclei and search for element 120

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, S. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Goethe-Universitaet Frankfurt, Institut fuer Physik, Frankfurt (Germany); Heinz, S.; Mann, R.; Maurer, J.; Barth, W.; Burkhard, H.G.; Dahl, L.; Kindler, B.; Kojouharov, I.; Lang, R.; Lommel, B.; Runke, J.; Scheidenberger, C.; Schoett, H.J.; Tinschert, K. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Muenzenberg, G. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Manipal University, Manipal Centre for Natural Sciences, Manipal, Karnataka (India); Antalic, S.; Saro, S. [Comenius University, Department of Nuclear Physics and Biophysics, Bratislava (Slovakia); Eberhardt, K.; Thoerle-Pospiech, P.; Trautmann, N. [Johannes Gutenberg-Universitaet Mainz, Mainz (Germany); Grzywacz, R. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Knoxville, TN (United States); Hamilton, J.H. [Vanderbuilt University, Department of Physics and Astronomy, Nashville, TN (United States); Henderson, R.A.; Kenneally, J.M.; Moody, K.J.; Shaughnessy, D.A.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Miernik, K. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Warsaw, Warsaw (Poland); Miller, D. [University of Tennessee, Knoxville, TN (United States); Morita, K. [RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama (Japan); Nishio, K. [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan); Popeko, A.G.; Yeremin, A.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Roberto, J.B.; Rykaczewski, K.P. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Uusitalo, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland)

    2016-06-15

    The reaction {sup 54}Cr + {sup 248}Cm was investigated at the velocity filter SHIP at GSI, Darmstadt, with the intention to study production and decay properties of isotopes of element 120. Three correlated signals were measured, which occurred within a period of 279ms. The heights of the signals correspond with the expectations for a decay sequence starting with an isotope of element 120. However, a complete decay chain cannot be established, since a signal from the implantation of the evaporation residue cannot be identified unambiguously. Measured properties of the event chain are discussed in detail. The result is compared with theoretical predictions. Previously measured decay properties of even element super-heavy nuclei were compiled in order to find arguments for an assignment from the systematics of experimental data. In the course of this review, a few tentatively assigned data could be corrected. New interpretations are given for results which could not be assigned definitely in previous studies. The discussion revealed that the cross-section for production of element 120 could be high enough so that a successful experiment seems possible with presently available techniques. However, a continuation of the experiment at SHIP for a necessary confirmation of the results obtained in a relatively short irradiation of five weeks is not possible at GSI presently. Therefore, we decided to publish the results of the measurement and of the review as they exist now. In the summary and outlook section we also present concepts for the continuation of research in the field of super-heavy nuclei. (orig.)

  14. Validation of new superheavy elements and IUPAC-IUPAP joint working group

    International Nuclear Information System (INIS)

    Jarlskog, Cecilia

    2016-01-01

    The great chemist Glenn Seaborg has written a delightful little book “Man-made Transuranium Elements”, published in 1963, in which he points out that: “The former basic criterion for the discovery of a new element – namely, chemical identification and separation from all previously-known elements – had to be changed in the case of lawrencium (element 103). This also may be true for elements beyond lawrencium.” Indeed this is what has happened. The elements with Z ≥ 103 are produced in nuclear reactions and are detected by counters. The detectors have undergone substantial refinement. For example one uses multiwire proportional chambers [for which George Charpak received the 1992 Nobel Prize in Physics] as well as solid state micro-strip detectors. In spite of this remarkable shift from chemistry to physics, the managerial staff of the International Union of Pure and Applied Chemistry (IUPAC) does not seem to be aware of what has been going on. The validation of superheavy elements should be done by physicists as the chemists lack the relevant competence as I will discuss here below. This article is about a collaboration between International Union of Pure and Applied Chemistry (IUPAC) and its sister organization International Union of Pure and Applied Physics (IUPAP), to deal with discovery of superheavy elements beyond Z = 112. I spent a great deal of time on this issue. In my opinion, the collaboration turned out to be a failure. For the sake of science, which should be our most important concern (and not politics), the rules for the future collaborations, if any, should be accurately defined and respected. The validation of new elements should be done by people who have the relevant competence – the physicists.

  15. High-spin structure of the neutron-rich sup 1 sup 0 sup 9 sup , sup 1 sup 1 sup 1 sup , sup 1 sup 1 sup 3 sup sub 4 sup sub 5 Rh isotopes

    CERN Document Server

    Venkova, T; Bauchet, A; Deloncle, I; Astier, A; Buforn, N; Meyer, M; Prevost, A; Redon, N; Stezowski, O; Lalkovski, S; Donadille, L; Dorvaux, O; Gall, B J P; Schulz, N; Lucas, R; Minkova, A

    2002-01-01

    The sup 1 sup 0 sup 9 sup , sup 1 sup 1 sup 1 sup , sup 1 sup 1 sup 3 Rh nuclei have been produced as fission fragments in the fusion reaction sup 1 sup 8 O + sup 2 sup 0 sup 8 Pb at 85 MeV. Their level schemes have been built from gamma-rays detected using the Euroball IV array. High-spin states of the neutron-rich sup 1 sup 1 sup 1 sup , sup 1 sup 1 sup 3 Rh nuclei have been identified for the first time. Several rotational bands with the odd proton occupying the pi g sub 9 sub / sub 2 , pi p sub 1 sub / sub 2 and pi(g sub 7 sub / sub 2 /d sub 5 sub / sub 2) sub-shells have been observed. A band of low-energy transitions has been identified at excitation energy around 2 MeV in sup 1 sup 0 sup 9 sup , sup 1 sup 1 sup 1 Rh, which can be interpreted in terms of three-quasiparticle excitation, pi g sub 9 sub / sub 2 nu h sub 1 sub 1 sub / sub 2 nu g sub 7 sub / sub 2 /d sub 5 sub / sub 2. In addition another structure built on states located at low excitation energy (608 keV in sup 1 sup 1 sup 1 Rh, 570 keV in ...

  16. Structure of neutron-rich nuclei around the N = 126 closed shell; the yrast structure of {sup 205}Au{sub 126} up to spin-parity I{sup {pi}} = (19/2{sup +})

    Energy Technology Data Exchange (ETDEWEB)

    Podolyak, Zs.; Steer, S.J.; Pietri, S.; Regan, P.H.; Brandau, C.; Catford, W.N.; Cullen, I.J.; Gelletly, W.; Jones, G.A.; Liu, Z.; Walker, P.M. [University of Surrey, Department of Physics, Guildford (United Kingdom); Gorska, M.; Gerl, J.; Wollersheim, H.J.; Grawe, H.; Becker, F.; Geissel, H.; Kelic, A.; Kojouharov, I.; Kurz, N.; Montes, F.; Prokopowicz, W.; Saito, T.; Schaffner, H.; Tashenov, S.; Werner-Malento, E. [GSI, Darmstadt (Germany); Rudolph, D.; Hoischen, R. [Lund University, Department of Physics, Lund (Sweden); Garnsworthy, A.B. [University of Surrey, Department of Physics, Guildford (United Kingdom); Yale University, WNSL, New Haven, CT (United States); Maier, K.H. [Institute of Nuclear Physics, Krakow (Poland); University of the West of Scotland, Dept. of Physics, Paisley (United Kingdom); Bednarczyk, P.; Grebosz, J. [GSI, Darmstadt (Germany); Institute of Nuclear Physics, Krakow (Poland); Caceres, L. [GSI, Darmstadt (Germany); Universidad Autonoma de Madrid, Dept. de Fisica Teorica, Madrid (Spain); Doornenbal, P. [GSI, Darmstadt (Germany); Universitaet zu Koeln, IKP, Koeln (Germany); Heinz, A. [Yale University, WNSL, New Haven, CT (United States); Kurtukian-Nieto, T. [Universidad de Santiago de Compostela, Santiago de Campostela (Spain); Benzoni, G.; Wieland, O. [Universita degli Studi di Milano (Italy); INFN, Milano (Italy); Pfuetzner, M. [Warsaw University, IEP, Warsaw (Poland); Jungclaus, A. [Universidad Autonoma de Madrid, Dept. de Fisica Teorica, Madrid (Spain); Balabanski, D.L. [Bulgarian Academy of Sciences, INRNE, Sofia (Bulgaria); Brown, B.A. [Univ. of Surrey, Dept. of Physics, Guildford (United Kingdom); Michigan State Univ., NSCL, East Lansing, MI (United States); Bruce, A.M.; Lalkovski, S. [Univ. of Brighton, School of Environment and Technology, Brighton (United Kingdom); Dombradi, Zs. [Institute for Nuclear Research, Debrecen (Hungary); Estevez, M.E. [Instituto de Fisica Corpuscular, Valencia (Spain)] [and others

    2009-12-15

    Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a {sup 208}{sub 82} Pb beam at E/A = 1 GeV on a 2.5 g/cm{sup 2} thick Be target. The synthesised nuclei were selected and identified in-flight using the fragment separator at GSI. Approximately 300 ns after production, the selected nuclei were implanted in an {proportional_to}8 mm thick perspex stopper, positioned at the centre of the RISING {gamma} -ray detector spectrometer array. A previously unreported isomer with a half-life T{sub 1/2} = 163(5) ns has been observed in the N=126 closed-shell nucleus {sup 205}{sub 79} Au. Through {gamma}-ray singles and {gamma}-{gamma} coincidence analysis a level scheme was established. The comparison with a shell model calculation tentatively identifies the spin-parity of the excited states, including the isomer itself, which is found to be I{sup {pi}} = (19/2{sup +}). (orig.)

  17. Observation of the new neutron-rich nuclei 29F, 35,36Mg, 38,39Al, 40,41Si, 43,44P, 45,46,47S, 46,47,48,49Cl and 49,50,51Ar by means of a 55 MeV/u 48Ca beam

    International Nuclear Information System (INIS)

    Guillemaud-Mueller, D.; Anne, R.; Penionzhkevich, Yu.Eh.

    1988-01-01

    Using magnetic separation and identification through time of flight and ΔE,E measurements, the new neutron-rich nuclei, 29 F, 35,36 Mg, 38,39 Al, 40,41 Si, 43,44 P, 45,46,47 S, 46,47,48,49 Cl, 49,50,51 Ar have been observed from interactions of 48 Ca beam of 55 MeV/u with tantalum targets

  18. Microcantilever-Enabled Neutron Detection

    Directory of Open Access Journals (Sweden)

    Kevin R. Kyle

    2014-04-01

    Full Text Available A new concept for neutron radiation detection was demonstrated using piezoresistive microcantilevers as the active sensing element. Microcantilevers were used to measure the tiny volumetric changes in a sensing material upon absorption of neutron radiation and transmutation into a new element. Highly ordered inorganic crystalline lattices of boron-rich materials dispersed in polymeric rubber matrices were shown to act as volumetric neutron transducers.

  19. Polarized neutrons

    International Nuclear Information System (INIS)

    Williams, W.G.

    1988-01-01

    The book on 'polarized neutrons' is intended to inform researchers in condensed matter physics and chemistry of the diversity of scientific problems that can be investigated using polarized neutron beams. The contents include chapters on:- neutron polarizers and instrumentation, polarized neutron scattering, neutron polarization analysis experiments and precessing neutron polarization. (U.K.)

  20. Neutron--neutron logging

    International Nuclear Information System (INIS)

    Allen, L.S.

    1977-01-01

    A borehole logging tool includes a steady-state source of fast neutrons, two epithermal neutron detectors, and two thermal neutron detectors. A count rate meter is connected to each neutron detector. A first ratio detector provides an indication of the porosity of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two epithermal neutron detectors. A second ratio detector provides an indication of both porosity and macroscopic absorption cross section of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two thermal neutron detectors. By comparing the signals of the two ratio detectors, oil bearing zones and salt water bearing zones within the formation being logged can be distinguished and the amount of oil saturation can be determined. 6 claims, 2 figures