Science.gov

Sample records for heavy nuclei photofission

  1. Kaon, pion, and proton associated photofission of Bi nuclei

    SciTech Connect

    Song, Y.; Margaryan, A.; Acha, A.; Ahmidouch, A.; Androic, D.; Asaturyan, A.; Asaturyan, R.; Baker, O. K.; Baturin, P.; Benmokhtar, F.; Carlini, R.; Chen, X.; Christy, M.; Cole, L.; Danagoulian, S.; Daniel, A.; Dharmawardane, V.; Egiyan, K.; Elaasar, M.; Ent, R.

    2010-10-15

    The first measurement of proton, pion, and kaon associated fission of Bi nuclei has been performed in a photon energy range 1. 45 < E{sub {gamma}}< 1. 55 GeV. The fission probabilities are compared with an inclusive fission probabilities obtained with photons, protons and pions. The fission probability of Bi nuclei in coincidence with kaons is 0. 18 {+-} 0. 06 which is {approx}3 times larger than the proton and pion associated fission probabilities and {approx}2 times larger than inclusive ones. The kaon associated excess fission events are explained in terms of bound {Lambda} residual states and their weak nonmesonic decays.

  2. Assessment of actinide mass embedded in large concrete waste packages by photon interrogation and photofission.

    PubMed

    Gmar, M; Jeanneau, F; Lainé, F; Makil, H; Poumarède, B; Tola, F

    2005-01-01

    This paper describes a method based on photofission developed in our laboratory to characterize in depth large waste packages. The method consists in using photons of high-energy (Bremsstrahlung radiation) in order to induce reactions of photofission on the heavy nuclei present in the wastes. The measurement of the delayed neutrons allows quantifying the actinides in the wastes. We present the first results of measurement performed with a concrete mock-up of 870l and two real waste packages.

  3. Heavy and Superheavy Atomic Nuclei

    NASA Astrophysics Data System (ADS)

    Sobiczewski, Adam

    2008-10-01

    The appearance and development of the concept of super-heavy atomic nuclei are described. The concept appeared during the studies of the limits of the nuclear chart and of the periodic table of the chemical elements. The article concentrates on theoretical studies of the properties of heaviest nuclei. Results of these studies are illustrated and discussed. Prospects for a nearest future of the research of heaviest nuclei are outlined.

  4. Proton Distribution in Heavy Nuclei

    DOE R&D Accomplishments Database

    Johnson, M. H; Teller, E.

    1953-11-13

    It is reasoned that, from considerations connected with beta-decay stability and Coulomb repulsion forces, a neutron excess is developed on the surface of heavy nuclei. Several consequences of this qualitative analysis in nucleon interactions are briefly noted. (K.S.)

  5. Fusion probability in heavy nuclei

    NASA Astrophysics Data System (ADS)

    Banerjee, Tathagata; Nath, S.; Pal, Santanu

    2015-03-01

    Background: Fusion between two massive nuclei is a very complex process and is characterized by three stages: (a) capture inside the potential barrier, (b) formation of an equilibrated compound nucleus (CN), and (c) statistical decay of the CN leading to a cold evaporation residue (ER) or fission. The second stage is the least understood of the three and is the most crucial in predicting yield of superheavy elements (SHE) formed in complete fusion reactions. Purpose: A systematic study of average fusion probability, , is undertaken to obtain a better understanding of its dependence on various reaction parameters. The study may also help to clearly demarcate onset of non-CN fission (NCNF), which causes fusion probability, PCN, to deviate from unity. Method: ER excitation functions for 52 reactions leading to CN in the mass region 170-220, which are available in the literature, have been compared with statistical model (SM) calculations. Capture cross sections have been obtained from a coupled-channels code. In the SM, shell corrections in both the level density and the fission barrier have been included. for these reactions has been extracted by comparing experimental and theoretical ER excitation functions in the energy range ˜5 %-35% above the potential barrier, where known effects of nuclear structure are insignificant. Results: has been shown to vary with entrance channel mass asymmetry, η (or charge product, ZpZt ), as well as with fissility of the CN, χCN. No parameter has been found to be adequate as a single scaling variable to determine . Approximate boundaries have been obtained from where starts deviating from unity. Conclusions: This study quite clearly reveals the limits of applicability of the SM in interpreting experimental observables from fusion reactions involving two massive nuclei. Deviation of from unity marks the beginning of the domain of dynamical models of fusion. Availability of precise ER cross

  6. Review of metastable states in heavy nuclei

    SciTech Connect

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

    2016-05-31

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

  7. Review of metastable states in heavy nuclei

    DOE PAGES

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

    2016-05-31

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

  8. Review of metastable states in heavy nuclei

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  9. Octupole shapes in heavy nuclei

    SciTech Connect

    Ahmad, I.

    1994-08-01

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

  10. Nuclei at HERA and heavy ion physics

    SciTech Connect

    Gavin, S.; Strikman, M.

    1995-12-31

    Copies of 16 viewgraph sets from a workshop held at Brookhaven National Laboratory, 17-18 November, 1995. Titles of talks: HERA: The Present; HERA: Potential with Nuclei; Review of Hadron-Lepton Nucleus Data; Fermilab E665: results in muon scattering; Interactions of Quarks and Gluons with Nuclear Matter; Rescattering in Nuclear Targets for Photoproduction and DIS; Structure Functions and Nuclear Effect at PHENIX; Probing Spin-Averaged and Spin-Dependent Parton Distributions Using the Solenoidal Tracker at RHIC (STAR); Jet Quenching in eA, pA, AA; Nuclear Gluon Shadowing via Continuum Lepton Pairs; What can we learn from HERA with a colliding heavy ion beam? The limiting curve of leading particles at infinite A; Coherent Production of Vector Mesons off Light Nuclei in DIS; A Model of High Parton Densities in PQCD; Gluon Production for Weizaecker-Williams Field in Nucleus-Nucleus Collisions; Summary Talk.

  11. Propagation of heavy cosmic-ray nuclei

    NASA Technical Reports Server (NTRS)

    Letaw, J. R.; Silberberg, R.; Tsao, C. H.

    1984-01-01

    Techniques for modeling the propagation of heavy cosmic-ray nuclei, and the required atomic and nuclear data, are assembled in this paper. Emphasis is on understanding nuclear composition in the charge range Z = 3-83. Details of the application of 'matrix methods' above a few hundred MeV/nucleon, a new treatment of electron capture decay, and a new table of cosmic ray-stable isotopes are presented. Computation of nuclear fragmentation cross sections, stopping power, and electron stripping and attachment are briefly reviewed.

  12. Shell effects in fusion of heavy nuclei

    SciTech Connect

    Moeller, P.; Nix, J.R.

    1997-12-31

    The spontaneous-fission properties of Fm isotopes undergo dramatic changes between {sup 256}Fm and {sup 258} Fm. The fission fragments of the former isotope are mass asymmetric with kinetic energies of about 200 MeV, whereas the fission fragments of the latter isotope are symmetric with kinetic energies of about 235 MeV. This rapid change occurs because the division into nearly doubly magic fragments near {sup 132}Sn becomes possible and opens up new valleys in the fission potential-energy surface. In the cold-fusion reactions leading to the heaviest elements, the nearly doubly magic targets and/or projectiles may give rise to important features associated with this magicity. Cold fusion is thought to favor heavy-element formation because it leads to low excitation energies of the compound nuclei. We investigate how near-magic targets and projectiles may lead to persistent survivability of the shells in the fusion valley as the ions merge, in addition to their effect on the compound-nucleus excitation energy.

  13. Do energetic heavy nuclei penetrate deeply into Earth's atmosphere?

    PubMed Central

    Price, P. B.; Askary, F.; Tarlé, G.

    1980-01-01

    We calculate the expected fluxes of cosmic ray nuclei with charge 5 ≤ Z ≤ 28 at various depths in the earth's atmosphere, taking into account the initial charge distribution, ionization loss, and various modes of fragmentation. The flux of surviving heavy nuclei is too low by a factor ≈10-10 to account for the ultra-high-energy Centauro events. We describe an experiment to search for highly ionizing particles that may or may not be nuclei. Images PMID:16592759

  14. Do energetic heavy nuclei penetrate deeply into Earth's atmosphere?

    PubMed

    Price, P B; Askary, F; Tarlé, G

    1980-01-01

    We calculate the expected fluxes of cosmic ray nuclei with charge 5 heavy nuclei is too low by a factor approximately 10(-10) to account for the ultra-high-energy Centauro events. We describe an experiment to search for highly ionizing particles that may or may not be nuclei.

  15. Effect of structural forbiddenness in fusion of heavy nuclei

    NASA Astrophysics Data System (ADS)

    Adamian, G. G.; Antonenko, N. V.; Tchuvil'Sky, Yu. M.

    1999-04-01

    With a microscopic approach based on the formalism of irreducible representations of the SU(3) group the influence of structural forbiddenness on the fusion of heavy nuclei and the dinuclear system phenomenon are investigated for different symmetric and asymmetric reactions used in the synthesis of heavy and superheavy nuclei. The energy thresholds for complete fusion in relative distance and mass asymmetry degrees of freedom are estimated.

  16. Analytic expressions for {alpha} particle preformation in heavy nuclei

    SciTech Connect

    Zhang, H. F.; Wang, Y. J.; Dong, J. M.; Royer, G.

    2009-11-15

    Experimental {alpha} decay energies and half-lives are investigated systematically to extract {alpha} particle preformation in heavy nuclei. Formulas for the preformation factors are proposed that can be used to guide microscopic studies on preformation factors and perform accurate calculations of the {alpha} decay half-lives. There is little evidence for the existence of an island of long stability of superheavy nuclei.

  17. Microscopic investigations on the fragmentation of heavy nuclei

    NASA Astrophysics Data System (ADS)

    Jung, Chr.; Cassing, W.; Mosel, U.; Cusson, R. Y.

    1988-02-01

    Model calculations of fragmentation reactions in the TDH F approximation provide quantitative information about the stability of heavy nuclei in a mean-field description. A comparison of these results to proton-induced fragmentation reactions shows that mean-field nuclei are much too stable against local fluctuations caused, e.g., by residual nucleon-nucleon collisions.

  18. Bose condensation of nuclei in heavy ion collisions

    NASA Technical Reports Server (NTRS)

    Tripathi, Ram K.; Townsend, Lawrence W.

    1994-01-01

    Using a fully self-consistent quantum statistical model, we demonstrate the possibility of Bose condensation of nuclei in heavy ion collisions. The most favorable conditions of high densities and low temperatures are usually associated with astrophysical processes and may be difficult to achieve in heavy ion collisions. Nonetheless, some suggestions for the possible experimental verification of the existence of this phenomenon are made.

  19. Two neutron correlations in photo-fission

    NASA Astrophysics Data System (ADS)

    Dale, D. S.; Kosinov, O.; Forest, T.; Burggraf, J.; Stave, S.; Warren, G.; Starovoitova, V.

    2016-09-01

    A large body of experimental work has established the strong kinematical correlation between fission fragments and fission neutrons. Here, we report on the progress of investigations of the potential for strong two neutron correlations arising from the nearly back-to-back nature of the two fission fragments that emit these neutrons in the photo-fission process. In initial measurements, a pulsed electron linear accelerator was used to generate bremsstrahlung photons that impinged upon an actinide target, and the energy and opening angle distributions of coincident neutrons were measured using a large acceptance neutron detector array. A planned comprehensive set of measurements of two neutron correlations in the photo-fission of actinides is expected to shed light on several fundamental aspects of the fission process including the multiplicity distributions associated with the light and heavy fission fragments, the nuclear temperatures of the fission fragments, and the mass distribution of the fission fragments as a function of energy released. In addition to these measurements providing important nuclear data, the unique kinematics of fission and the resulting two neutron correlations have the potential to be the basis for a new tool to detect fissionable materials. A key technical challenge of this program arises from the need to perform coincidence measurements with a low duty factor, pulsed electron accelerator. This has motivated the construction of a large acceptance neutron detector array, and the development of data analysis techniques to directly measure uncorrelated two neutron backgrounds.

  20. Two neutron correlations in photo-fission

    SciTech Connect

    Dale, D. S.; Kosinov, O.; Forest, T.; Burggraf, J.; Stave, S.; Warren, G.; Starovoitova, V.

    2016-01-01

    A large body of experimental work has established the strong kinematical correlation between fission fragments and fission neutrons. Here, we report on the progress of investigations of the potential for strong two neutron correlations arising from the nearly back-to-back nature of the two fission fragments that emit these neutrons in the photo-fission process. In initial measurements, a pulsed electron linear accelerator was used to generate bremsstrahlung photons that impinged upon an actinide target, and the energy and opening angle distributions of coincident neutrons were measured using a large acceptance neutron detector array. A planned comprehensive set of measurements of two neutron correlations in the photo-fission of actinides is expected to shed light on several fundamental aspects of the fission process including the multiplicity distributions associated with the light and heavy fission fragments, the nuclear temperatures of the fission fragments, and the mass distribution of the fission fragments as a function of energy released. In addition to these measurements providing important nuclear data, the unique kinematics of fission and the resulting two neutron correlations have the potential to be the basis for a new tool to detect fissionable materials. A key technical challenge of this program arises from the need to perform coincidence measurements with a low duty factor, pulsed electron accelerator. This has motivated the construction of a large acceptance neutron detector array, and the development of data analysis techniques to directly measure uncorrelated two neutron backgrounds.

  1. Cluster radioactivity in very heavy nuclei: a new perspective

    NASA Astrophysics Data System (ADS)

    Routray, T. R.; Nayak, Jagajjaya; Basu, D. N.

    2009-08-01

    Exotic cluster decay of very heavy nuclei is studied using the microscopic nuclear potentials obtained by folding density dependent M3Y effective interaction with the densities of the cluster and the daughter nuclei. The microscopic nuclear potential, Coulomb interaction and the centrifugal barrier arising out of spin-parity conservation are used to obtain the potential between the cluster and the daughter nuclei. Half life values are calculated in the WKB framework and the preformation factors are extracted. The latter values are seen to have only a very weak dependence on the mass of the emitted cluster.

  2. Heavy Nuclei, From RHIC to The Cosmos

    SciTech Connect

    Klein, Spencer R.

    2002-11-01

    Ultra-relativistic heavy ion collisions produce a high-temperature, thermalized system that may mimic the conditions present shortly after the big bang. This writeup will given an overview of early results from the Relativistic Heavy Ion Collider (RHIC), and discuss what we have learned about hot, strongly interacting nuclear systems. The thermal and chemical composition of the system will be discussed, along with observables that are sensitive to the early evolution of the system. I will also discuss the implications of the RHIC results for cosmic ray air showers.

  3. Cluster preformation law for heavy and superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Wei, K.; Zhang, H. F.

    2017-08-01

    The concept of cluster radioactivity has been extended to allow emitted particles with ZC>28 for superheavy nuclei by nuclear theory [Poenaru et al., Phys. Rev. Lett. 107, 062503 (2011), 10.1103/PhysRevLett.107.062503]. The preformation and emission mechanics of heavy-ion particles must be examined again before the fascinating radioactivity is observed for superheavy nuclei in laboratory. We extract the cluster preformation factor for heavy and superheavy nuclei within a preformed cluster model, in which the decay constant is the product of the preformation factor, assault frequency, and penetration probability. The calculated results show that the cluster penetration probability for superheavy nuclei is larger than that for actinide elements. The preformation factor depends on the nuclear structures of the emitted cluster and mother nucleus, and the well-known cluster preformation law S (AC) =S (α) (AC-1 )/3 [Blendowske and Walliser, Phys. Rev. Lett. 61, 1930 (1988), 10.1103/PhysRevLett.61.1930] will break down when the mass number of the emitted cluster Ac>28 , and new preformation formulas are proposed to estimate the preformation factor for heavy and superheavy nuclei.

  4. A Semi-microscopic Approach to Clusterization in Heavy Nuclei

    SciTech Connect

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

    2009-08-26

    We present a semimicroscopic approach to clusterization in heavy nuclei. The method is largely based on symmetry-considerations. As an example we determine the possible binary clusterizations of the shape isomers of the {sup 56}Ni nucleus. We combine our structure-considerations with energy-calculations.

  5. Recent studies of heavy nuclei far from stability at JYFL

    SciTech Connect

    Julin, R.; Enqvist, T.; Helariutta, K.

    1996-12-31

    The new K=130 Cyclotron + ECR facility of the Physics Department of the University of Jyvaskyla (JYFL) provides stable beams from protons up to krypton ions for nuclear structure studies. Two instruments designed especially for in-beam spectroscopic studies of heavy nuclei at JYFL are introduced in this contribution. Some results from recent measurements with them are reported.

  6. New results for medium and heavy-mass nuclei

    NASA Astrophysics Data System (ADS)

    Schwenk, Achim

    2016-09-01

    In this talk, we will discuss the advances, status and challenges of understanding and predicting medium and heavy-mass nuclei based on chiral effective field theory interactions. Supported in part by ERC Grant No. 307986 STRONGINT, the DFG through Grant SFB 1245, the BMBF under Contract No. 06DA70471, and the Max-Planck Society.

  7. Electronic detection of ultra-heavy nuclei by pyroelectric materials

    NASA Technical Reports Server (NTRS)

    Simpson, J. A.; Tuzzolino, A. J.

    1983-01-01

    A recent prediction by the authors that pyroelectric materials may be capable of detecting ultra-heavy nuclei has been confirmed. Charge pulse signals from pyroelectric crystals of lithium tantalate exposed to Au ions and a pulsed beam of Ni-58 ions, and from pyroelectric films of polyvinylidene fluoride exposed to a pulsed beam of Ni-58 ions, have been measured using pulse electronics with time constants in the microsecond range. These studies show that pyroelectric materials, in general, are capable of detecting incident nuclei having very high mass and charge. In particular, pyroelectric polymers, such as polyvinylidene fluoride, are readily available as inexpensive flexible films. This new class of charged particle detector could eventually find applications in large-area experiments for detection and trajectory determination of low-energy, ultra-heavy nuclei.

  8. Electronic detection of ultra-heavy nuclei by pyroelectric materials

    NASA Technical Reports Server (NTRS)

    Simpson, J. A.; Tuzzolino, A. J.

    1983-01-01

    A recent prediction by the authors that pyroelectric materials may be capable of detecting ultra-heavy nuclei has been confirmed. Charge pulse signals from pyroelectric crystals of lithium tantalate exposed to Au ions and a pulsed beam of Ni-58 ions, and from pyroelectric films of polyvinylidene fluoride exposed to a pulsed beam of Ni-58 ions, have been measured using pulse electronics with time constants in the microsecond range. These studies show that pyroelectric materials, in general, are capable of detecting incident nuclei having very high mass and charge. In particular, pyroelectric polymers, such as polyvinylidene fluoride, are readily available as inexpensive flexible films. This new class of charged particle detector could eventually find applications in large-area experiments for detection and trajectory determination of low-energy, ultra-heavy nuclei.

  9. Surface direct nuclear photoeffect in heavy deformed nuclei

    NASA Astrophysics Data System (ADS)

    Ishkhanov, B. S.; Orlin, V. N.; Stopani, K. A.

    2016-11-01

    A mechanism of photon-induced direct knockout of a nucleon from the nuclear surface without formation of intermediate excited nuclear state is described. The effect plays an important role at least for the (γ ,p ) reaction on heavy nuclei in the energy region centered at about 30 MeV where the probability of formation of the giant dipole resonance is already small but quasideuteron photoabsorption still does not prevail. A compact model of the surface direct nuclear photoeffect (SDNP) in heavy deformed nuclei that can be used to calculate the differential d σ (Eγ,ϑ )/d Ω and total σ (Eγ) cross sections of the SDNP under adiabatic approximation is formulated. The model is applied to calculation of the (γ ,p ) reaction cross sections on 160Gd and W,186184. The importance of the SDNP effect for these nuclei at Eγ˜30 MeV is demonstrated.

  10. The Heavy Nuclei eXplorer (HNX) Small Explorer Mission

    NASA Astrophysics Data System (ADS)

    Mitchell, John; Binns, W. Robert; Hams, Thomas; Israel, Martin; Krizmanic, John; Link, Jason; Rauch, Brian; Sakai, Kenichi; Sasaki, Makoto; Westphal, Andrew; Wiedenbeck, Mark; Heavy Nuclei eXplorer Collaboration

    2015-04-01

    The Heavy Nuclei eXplorer (HNX) will investigate the nature of the reservoirs of nuclei at the cosmic-ray sources, the mechanisms by which nuclei are removed from the reservoirs and injected into the cosmic accelerators, and the acceleration mechanism. HNX will use two large high-precision instruments, the Extremely-heavy Cosmic-ray Composition Observer (ECCO) and the Cosmic-ray Trans-Iron Galactic Element Recorder (CosmicTIGER), flying in the SpaceX DragonLab, to measure, for the first time, the abundance of every individual element in the periodic table from carbon through the actinides, providing the first measurement of many of these elements. HNX will measure several thousand ultra-heavy galactic cosmic ray (UHGCR) nuclei Z >= 30, including about 50 actinides, and will: determine whether GCRs are accelerated from new or old material, and find their age; measure the mix of nucleosynthesis processes responsible for the UHGCRs; determine how UHGCR elements are selected for acceleration, and measure the mean integrated pathlength traversed by UHGCRs before observation. The scientific motivation and instrument complement of HNX will be discussed.

  11. Probable Heavy Particle Decays from 306-339128 Superheavy Nuclei

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Sukumaran, Indu

    2016-12-01

    The heavy particle decays that are probable from the isotopes of Z = 128 superheavy nuclei within the range A = 306-339 have been analyzed within the Coulomb and proximity potential model (CPPM). The study includes the evaluation of heavy particle decay half-lives of 24 clusters, including both odd and even clusters that are supposed to be emitted from the Z = 128 superheavy nuclei. The predicted values in comparison with the models Universal curve (UNIV), Universal decay law (UDL), and scaling law of Horoi et al. are observed to follow the same trend, and almost all the values lie well within the experimental limit ( T 1/2 <1030s). The interesting point of the study is the confirmation of the importance of neutron magicity in the superheavy region, noticed from the plots of log10( T 1/2) vs. neutron number of the daughter nuclei. The minimum observed corresponds to the daughter nucleus with N = 184, which strongly supports the possibility of N = 184 to be a shell closure number. Also, the abrupt increase in the half-lives at A = 330 of the parent nuclei is the signature of neutron magicity at N = 202 associated with the parent nuclei. In addition, in the emission of odd mass clusters, the odd-even staggering (OES) effect is found which is more prominent in the case of heavy odd mass clusters. Importantly, the different slopes and intercepts obtained from the Geiger-Nuttall plots of log10( T 1/2) vs. Q -1/2 confirming the presence of shell closure effect and the plot of universal curve of log10( T 1 /2) vs.-lnP revealed the reliability of the model CPPM.

  12. Capabilities of the LDEF-2 heavy nuclei collection

    NASA Technical Reports Server (NTRS)

    Drach, J.; Price, P. B.; Salamon, M. H.; Tarle, G.; Ahlen, S. P.

    1985-01-01

    To take the next big step beyond High Energy Astronomy Observatory (HEAO-3) the Heavy Nuclei Collector (HNC), to be carried on an LDEF reflight, has the goals of greatly increased collecting power ( 30 actinides) and charge resolution sigma sub Z or = 0.25 E for Z up to approximately 100, which will provide abundances of all the charges 40 or Z or = 96 and permit sensitive searches for hypothetical particles such as monopoles, superheavy elements, and quark nuggets.

  13. Comparison of Muon Capture in Light and in Heavy Nuclei

    SciTech Connect

    Measday, David F.; Stocki, Trevor J.

    2007-10-26

    We have recently completed an experimental study at TRIUMF of muon capture in the following elements, N, Al, Si, Ca, Fe, Ni, I, Au, and Bi. We detected the nuclear gamma rays emitted by the product nuclei after muon capture. The energy of the gamma ray identifies the source nuclide, and thus the reaction which has occurred. Our data are of better quality, and more comprehensive than any other data set in the literature. The ({mu}{sup -},{nu}n) reaction is always dominant. In light nuclei, reactions such as ({mu}{sup -},{nu}p) and ({mu}{sup -},{nu}pn) can occur, but not for heavy nuclei. However the reverse is true for reactions such as ({mu}{sup -},{nu}3n) and ({mu}{sup -},{nu}4n), which are very rare in light nuclei, but easily detected in heavy elements. We shall discuss how such information can be useful in calculations of neutrino-nucleus interactions, and of electron-capture in supernovae.

  14. Source spectral index of heavy cosmic ray nuclei

    NASA Technical Reports Server (NTRS)

    Engelmann, J. J.; Ferrando, P.; Koch-Miramond, L.; Masse, P.; Soutoul, A.; Webber, W. R.

    1985-01-01

    From the energy spectra of the heavy nuclei observed by the French-Danish experiment on HEAO-3, the source spectra of the mostly primary nuclei (C, O, Ne, Mg, Si, Ca and Fe) in the framework of an energy dependent leaky box model (Engelmann, et al., 1985) were derived. The energy dependence of the escape length was derived from the observed B/C and sub-iron/iron ratios and the presently available cross sections for C and Fe on H nuclei (Koch-Miramond, et al., 1983). A good fit to the source energy spectra of all these nuclei was obtained by a power law in momentum with an exponent gamma = -2.4+0.05 for the energy range 1 to 25GeV/n (Engelmann, et al., 1985). Comparison with data obtained at higher energy suggested a progressive flattening of these spectra. More accurate spectral indices are sought by using better values of the escape length based on the latest cross section measurements (Webber 1984, Soutoul, et al., this conference). The aim is also to extend the analysis to lower energies down to 0.4GeV/n (kinetic energy observed near Earth), using data obtained by other groups. The only nuclei for which a good data base is possessed in a broad range of energies are O and Fe, so the present study is restricted to these two elements.

  15. Studies of Heavy-Ion Reactions and Transuranic Nuclei

    SciTech Connect

    Schroeder, W. Udo

    2016-07-28

    Studies of heavy-ion reactions and transuranic nuclei performed by the University of Rochester Nuclear Science Research Group have been successful in furthering experimental systematics and theoretical understanding of the behavior of nuclear systems excited to their limits of stability. The theoretical results explain specifically the “boiling” and “vaporization” of atomic nuclei, but are more generally applicable to isolated, quantal many-particle systems which, under thermal or mechanical stresses, all disintegrate by evaporation, via surface cluster emission, or via fission-like processes. Accompanying experimental investigations by the group have demonstrated several new types of dynamical instability of nuclei: In central, “head-on” collisions, target nuclei exhibit limited ability to stop energetic projectile nuclei and to dissipate the imparted linear momentum. Substantial matter overlap (“neck”) between projectile and target nuclei, which is observed at elevated collision energies, can be stretched considerably and break at several places simultaneously. These results provide new testing grounds for microscopic theory of the cohesion of nuclear matter. This property has remained elusive, even though the elementary nucleon-nucleon forces are well known since some time. Technical R&D has resulted in a detailed characterization of a novel plastic material, which can now be used in the design of sensitive diagnostic systems for various types of radio-activity. Innovative application of powerful laser systems has produced intense, controllable sources of exotic particle radioactivity for nuclear investigations. Several students have received their Ph.D. degree in experimental nuclear science for their work on basic nuclear research or R&D projects.

  16. Coincidence/Multiplicity Photofission Measurements

    SciTech Connect

    J.L. Jones; M.T. Swinhoe; S.J. Tobin; W. H. Geist; D.R. Norman; R.B. Rothrock; C.R. Freeman; K. J. Haskell

    2009-09-01

    An series of experiments using the Idaho National Laboratory (INL) photonuclear inspection system and a Los Alamos National Laboratory (LANL)-supplied, list-mode data acquisition method have shown enhanced performance utilizing pulsed photofission-induced, neutron coincidence counting between pulses of an up-to-10-MeV electron accelerator for nuclear material detection and identification. The enhanced inspection methodology has applicability to homeland security, treaty-related support, and weapon dismantlement applications. For the latter, this technology can directly support of Department of Energy/NA241 programmatic mission objectives relative to future Rocky Ridge-type testing campaigns for active inspection systems.

  17. The Heavy Nuclei eXplorer (HNX) Mission

    NASA Astrophysics Data System (ADS)

    Krizmanic, John; Mitchell, John; Binns, W. Robert; Hams, Thomas; Israel, Martin; Link, Jason; Rauch, Brian; Sakai, Kenichi; Sasaki, Makoto; Westphal, Andrew; Wiedenbeck, Mark; Heavy Nuclei eXplorer Collaboration

    2016-03-01

    The Heavy Nuclei eXplorer (HNX) will use two large high-precision instruments, the Extremely-heavy Cosmic-ray Composition Observer (ECCO) and the Cosmic-ray Trans-Iron Galactic Element Recorder (CosmicTIGER), designed to fly in a SpaceX DragonLab Capsule, to measure the cosmic-ray abundance of every individual element in the periodic table from carbon through curium, providing the first measurement of many of these elements. These measurements provide an investigation on the nature of the source material of cosmic rays, the processes that inject them into cosmic accelerators, and the acceleration mechanisms. HNX will measure several thousand ultra-heavy galactic cosmic ray (UHGCR) nuclei with Z >= 30 , including about 50 actinides (Z >= 79). These data allow for a measurement of the mix of new and old material that is accelerated to GCRs, determine their age, measure the mix of nucleosynthesis processes responsible for the UHGCRs, determine how UHGCR elements are selected for acceleration, and measure the mean integrated pathlength traversed by UHGCRs before observation. The scientific motivation and instrumentation of HNX will be discussed as well as recent beam test results.

  18. Neutron skin studies of medium and heavy nuclei

    NASA Astrophysics Data System (ADS)

    Thiel, M.; Becker, D.; Ferretti, M.; Kumar, K.; Sfienti, C.

    2014-06-01

    The recent PREX experiment at JLab has demonstrated the sensitivity of parity violating electron scattering to the neutron density, meanwhile outlining its major experimental challenges. On the other side, intermediate energy photons are an ideal probe for studying the properties of strongly interacting matter from the nuclear scale down to the sub-nuclear components of the nucleus. Among others coherent pion photoproduction can provide information on the existence and nature of neutron skins in nuclei. The simultaneous combination of different techniques allows a systematic determination across the periodic table thus benchmarking modern calculation. Recently a systematic investigation of the latter method has been exploited at MAMI (Mainz). At MESA the same setup as in the measurement of the weak mixing angle can be used to determine the parity-violating asymmetry for polarized electrons scattered on heavy nuclei with a 1% resolution. Status and prospects of the projects are presented.

  19. Proxy-SU(3) symmetry in heavy deformed nuclei

    NASA Astrophysics Data System (ADS)

    Bonatsos, Dennis; Assimakis, I. E.; Minkov, N.; Martinou, Andriana; Cakirli, R. B.; Casten, R. F.; Blaum, K.

    2017-06-01

    Background: Microscopic calculations of heavy nuclei face considerable difficulties due to the sizes of the matrices that need to be solved. Various approximation schemes have been invoked, for example by truncating the spaces, imposing seniority limits, or appealing to various symmetry schemes such as pseudo-SU(3). This paper proposes a new symmetry scheme also based on SU(3). This proxy-SU(3) can be applied to well-deformed nuclei, is simple to use, and can yield analytic predictions. Purpose: To present the new scheme and its microscopic motivation, and to test it using a Nilsson model calculation with the original shell model orbits and with the new proxy set. Method: We invoke an approximate, analytic, treatment of the Nilsson model, that allows the above vetting and yet is also transparent in understanding the approximations involved in the new proxy-SU(3). Results: It is found that the new scheme yields a Nilsson diagram for well-deformed nuclei that is very close to the original Nilsson diagram. The specific levels of approximation in the new scheme are also shown, for each major shell. Conclusions: The new proxy-SU(3) scheme is a good approximation to the full set of orbits in a major shell. Being able to replace a complex shell model calculation with a symmetry-based description now opens up the possibility to predict many properties of nuclei analytically and often in a parameter-free way. The new scheme works best for heavier nuclei, precisely where full microscopic calculations are most challenged. Some cases in which the new scheme can be used, often analytically, to make specific predictions, are shown in a subsequent paper.

  20. Manifestation of the structure of heavy nuclei in their alpha decays

    SciTech Connect

    Adamian, G. G. Antonenko, N. V.; Bezbakh, A. N.; Malov, L. A.

    2016-11-15

    Low-lying one- and two-quasiparticle states of heavy nuclei are predicted. Alpha-decay chains, including those that proceed through isomeric states, are examined on the basis of the predicted properties of superheavy nuclei.

  1. Atomic nuclei decay modes by spontaneous emission of heavy ions

    NASA Astrophysics Data System (ADS)

    Poenaru, D. N.; Ivaşcu, M.; Sndulescu, A.; Greiner, Walter

    1985-08-01

    The great majority of the known nuclides with Z>40, including the so-called stable nuclides, are metastable with respect to several modes of spontaneous superasymmetric splitting. A model extended from the fission theory of alpha decay allows one to estimate the lifetimes and the branching ratios relative to the alpha decay for these natural radioactivities. From a huge amount of systematic calculations it is concluded that the process should proceed with maximum intensity in the trans-lead nuclei, where the minimum lifetime is obtained from parent-emitted heavy ion combinations leading to a magic (208Pb) or almost magic daughter nucleus. More than 140 nuclides with atomic number smaller than 25 are possible candidates to be emitted from heavy nuclei, with half-lives in the range of 1010-1030 s: 5He, 8-10Be, 11,12B, 12-16C, 13-17N, 15-22O, 18-23F, 20-26Ne, 23-28Na, 23-30Mg, 27-32Al, 28-36Si, 31-39P, 32-42S, 35-45Cl, 37-47Ar, 40-49 K, 42-51. . .Ca, 44-53 Sc, 46-53Ti, 48-54V, and 49-55 Cr. The shell structure and the pairing effects are clearly manifested in these new decay modes.

  2. Neutron-halo nuclei in cold synthesis and cluster decay of heavy nuclei: {ital Z}=104 nucleus as an example

    SciTech Connect

    Gupta, R.K.; Singh, S.; Muenzenberg, G.; Scheid, W. ||

    1995-05-01

    Nuclei at the neutron-drip line are studied. The light neutron-halo nuclei are found to play an important role for both cold fusion reactions and exotic cluster decay studies of heavy nuclei at the neutron-drip line. For cold fusion reactions, beams of neutron-halo nuclei are shown to occur as natural extensions of the conventional lighter beams but with the corresponding target nuclei as the heavy neutron-rich radioactive nuclei. Thus, in synthesizing the various isotopes of a neutron-rich cool compound nucleus, both the target and projectile nuclei have to be richer in neutrons, with their proton numbers remaining the same. On the other hand, neutron-halo (cluster) decays are favored for a relatively less neutron-rich parent nucleus. Possible consequences of this work for the shell structure effects in neutron-rich heavy nuclei are also pointed out. This follows from the fact that the so far observed phenomena of both cold fusion and cluster radioactivity are associated with closed or nearly closed shell nuclei. Calculations are made for {sup 274,288}104, using the quantum mechanical fragmentation theory for cold fusion reaction studies and a performed cluster model for cluster decay studies.

  3. A search for anomalously heavy isotopes of low Z nuclei

    SciTech Connect

    Hemmick, T.K.

    1989-01-01

    Several recent theories suggest the possibility that undiscovered exotic forms of stable matter may exist in the universe. These would be hidden in nature as anomalous mass isotopes of ordinary nuclei. A search was performed for anomalous mass isotopes of hydrogen, lithium, beryllium, boron, carbon, oxygen and fluorine. No evidence for such isotopes was found for masses ranging from 100 to 10,000 amu. The sensitivity of our search was many orders of magnitude higher than theoretical calculations suggest should have been necessary. Although natural processes which lower concentrations of heavy isotopes do exist, we show that such processes cannot account for the dramatic differences between prediction and measurement. The implications of our results are discussed in the context of the recent theories to which it applies as well as any future theories which might predict anomalous stable forms of matter. Suggestions are made for ways to extend these results to other isotopes and higher masses.

  4. Strictly finite-range potential for light and heavy nuclei

    NASA Astrophysics Data System (ADS)

    Salamon, P.; Lovas, R. G.; Betan, R. M. Id; Vertse, T.; Balkay, L.

    2014-05-01

    Strictly finite-range (SFR) potentials are exactly zero beyond their finite range. Single-particle energies and densities, as well as S-matrix pole trajectories, are studied in a few SFR potentials suited for the description of neutrons interacting with light and heavy nuclei. The SFR potentials considered are the standard cutoff Woods-Saxon (CWS) potentials and two potentials approaching zero smoothly: the SV potential introduced by Salamon and Vertse [Phys. Rev. C 77, 037302 (2008), 10.1103/PhysRevC.77.037302] and the SS potential of Sahu and Sahu [Int. J. Mod. Phys. E 21, 1250067 (2012), 10.1142/S021830131250067X]. The parameters of these latter potentials were set so that the potentials may be similar to the CWS shape. The range of the SV and SS potentials scales with the cube root of the mass number of the core like the nuclear radius itself. For light nuclei a single term of the SV potential (with a single parameter) is enough for a good description of the neutron-nucleus interaction. The trajectories are compared with a benchmark for which the starting points (belonging to potential depth zero) can be determined independently. Even the CWS potential is found to conform to this benchmark if the range is identified with the cutoff radius. For the CWS potentials some trajectories show irregular shapes, while for the SV and SS potentials all trajectories behave regularly.

  5. Revisiting the symmetric reactions for synthesis of super-heavy nuclei of Z⩾120

    NASA Astrophysics Data System (ADS)

    Choudhury, R. K.; Gupta, Y. K.

    2014-04-01

    Extensive efforts have been made experimentally to reach nuclei in the super-heavy mass region of Z=110 and above with suitable choices of projectile and target nuclei. The cross sections for production of these nuclei are seen to be in the range of a few picobarn or less, and pose great experimental challenges. Theoretically, there have been extensive calculations for highly asymmetric (hot-fusion) and moderately asymmetric (cold-fusion) collisions and only a few theoretical studies are available for near-symmetric collisions to estimate the cross sections for production of super-heavy nuclei. In the present article, we revisit the symmetric heavy ion reactions with suitable combinations of projectile and target nuclei in the rare-earth region, that will lead to super-heavy nuclei of Z⩾120 with measurable fusion cross sections.

  6. Nuclear photofission studies with monochromatic γ ray beams

    NASA Astrophysics Data System (ADS)

    Csige, L.; Gulyás, J.; Habs, D.; Krasznahorkay, A.; Thirolf, P. G.; Tornyi, T. G.

    2012-07-01

    Two new research facilities will be ready for operation very soon (MEGa-Ray at Liver-more National Laboratory) or start construction (ELI-Nuclear Physics in Bucharest), both providing highly brilliant γ beams with so far unprecedented properties via Compton backscattering of laser photons from a high-quality, relativistic electron beam. With these intense, monochromatic γ beams, a new era of photonuclear physics will be enabled. A new research campaign is proposed to exploit the unprecedented properties of these highly-brilliant, novel γ beams on highly-selective studies of extremely deformed nuclei in the multiple-humped potential energy landscape of the actinides via photofission. With the unique γ beam bandwidth of ΔE/E = 10-3, we can aim at resolving individual resonances which could never be achieved so far due to the limited γ bandwidth of bremsstrahlung beams. Exploratory, non-bremsstrahlung photofission experiments are going to be performed very soon at the HIγS facility (Duke University, USA) to investigate the fine structure of the sub-barrier transmission resonances of the actinides.

  7. Nuclear photofission studies with monochromatic {gamma} ray beams

    SciTech Connect

    Csige, L.; Gulyas, J.; Habs, D.; Krasznahorkay, A.; Thirolf, P. G.; Tornyi, T. G.

    2012-07-09

    Two new research facilities will be ready for operation very soon (MEGa-Ray at Liver-more National Laboratory) or start construction (ELI-Nuclear Physics in Bucharest), both providing highly brilliant {gamma} beams with so far unprecedented properties via Compton backscattering of laser photons from a high-quality, relativistic electron beam. With these intense, monochromatic {gamma} beams, a new era of photonuclear physics will be enabled. A new research campaign is proposed to exploit the unprecedented properties of these highly-brilliant, novel {gamma} beams on highly-selective studies of extremely deformed nuclei in the multiple-humped potential energy landscape of the actinides via photofission. With the unique {gamma} beam bandwidth of {Delta}E/E = 10{sup -3}, we can aim at resolving individual resonances which could never be achieved so far due to the limited {gamma} bandwidth of bremsstrahlung beams. Exploratory, non-bremsstrahlung photofission experiments are going to be performed very soon at the HI{gamma}S facility (Duke University, USA) to investigate the fine structure of the sub-barrier transmission resonances of the actinides.

  8. Secondary electron background produced by heavy nuclei in a multiwire proportional counter hodoscope

    NASA Technical Reports Server (NTRS)

    Morgan, S. H., Jr.; Watts, J. W., Jr.; Schwille, H.; Pollvogt, U.

    1974-01-01

    The secondary electron background produced by heavy nuclei in a multiwire proportional counter hodoscope is calculated using both a simplified and a more complete Monte Carlo model. These results are compared with experimental data from a small multiwire proportional counter hodoscope operated in a 530 MeV/nucleon accelerator beam of nitrogen nuclei. Estimates of the secondary electron background produced by heavy relativistic nuclei are presented along with the detailed results from calculations of energy deposition in the hodoscope counter cells.

  9. Octupole response and stability of spherical shape in heavy nuclei

    NASA Astrophysics Data System (ADS)

    Abrosimov, V. I.; Davidovskaya, O. I.; Dellafiore, A.; Matera, F.

    2003-11-01

    The isoscalar octupole response of a heavy spherical nucleus is analyzed in a semiclassical model based on the linearized Vlasov equation. The octupole strength function is evaluated with different degrees of approximation. The zero-order fixed-surface response displays a remarkable concentration of strength in the 1ℏ ω and 3ℏ ω regions, in excellent agreement with the quantum single-particle response. The collective fixed-surface response reproduces both the high- and low-energy octupole resonances, but not the low-lying 3 - collective states, while the moving-surface response function gives a good qualitative description of all the main features of the octupole response in heavy nuclei. The role of triangular nucleon orbits, that have been related to a possible instability of the spherical shape with respect to octupole-type deformations, is discussed within this model. It is found that, rather than creating instability, the triangular trajectories are the only classical orbits contributing to the damping of low-energy octupole excitations.

  10. Medium-heavy nuclei from nucleon-nucleon interactions in lattice QCD

    NASA Astrophysics Data System (ADS)

    Inoue, Takashi; Aoki, Sinya; Charron, Bruno; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Ishii, Noriyoshi; Murano, Keiko; Nemura, Hidekatsu; Sasaki, Kenji; HAL QCD Collaboration

    2015-01-01

    On the basis of the Brueckner-Hartree-Fock method with the nucleon-nucleon forces obtained from lattice QCD simulations, the properties of the medium-heavy doubly magic nuclei such as 16O and 40Ca are investigated. We found that those nuclei are bound for the pseudoscalar meson mass MPS≃470 MeV. The mass number dependence of the binding energies, single-particle spectra, and density distributions are qualitatively consistent with those expected from empirical data at the physical point, although these hypothetical nuclei at heavy quark mass have smaller binding energies than the real nuclei.

  11. Nuclear isospin asymmetry in α decay of heavy nuclei

    NASA Astrophysics Data System (ADS)

    Shin, Eunkyoung; Lim, Yeunhwan; Hyun, Chang Ho; Oh, Yongseok

    2016-08-01

    The effects of nuclear isospin asymmetry on α -decay lifetimes of heavy nuclei are investigated within various phenomenological models of the nuclear potential for the α particle. We consider the widely used simple square-well potential and Woods-Saxon potential and modify them by including an isospin asymmetry term. We then suggest a model for the potential of the α particle motivated by a microscopic phenomenological approach of the Skyrme force model, which naturally introduces the isospin-dependent form of the nuclear potential for the α particle. The empirical α -decay lifetime formula of Viola and Seaborg [J. Inorg. Nucl. Chem. 28, 741 (1966), 10.1016/0022-1902(66)80412-8] is also modified to include isospin asymmetry effects. The obtained α -decay half-lives are in good agreement with the experimental data, and we find that including the nuclear isospin effects somehow improves the theoretical results for α -decay half-lives. The implications of these results are discussed, and the predictions on the α -decay lifetimes of superheavy elements are also presented.

  12. Heavy particle radioactivity from superheavy nuclei leading to 298114 daughter nuclei

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Priyanka, B.

    2014-09-01

    The feasibility for the alpha decay and the heavy particle decay from the even-even superheavy (SH) nuclei with Z = 116- 124 has been studied within the Coulomb and proximity potential model (CPPM). Our predicted half lives agree well with the values evaluated using the Universal formula for cluster decay (UNIV) of Poenaru et al., the Universal Decay Law (UDL) of Qi et al., and the Scaling Law of Horoi et al. The spontaneous fission half lives of the corresponding parents have also been evaluated using the semi-empirical formula of Santhosh et al. Within our fission model, we have studied the cluster formation probability for various clusters and the maximum cluster formation probability is found for the decay accompanying 298114. In the plots for log10 (T1/2) against the neutron number of the daughter in the corresponding decay, the half life is found to be the minimum for the decay leading to 298114 (Z = 114, N = 184). Most of the predicted half lives are well within the present upper limit for measurements (T1/2 <1030 s) and the computed alpha half lives for 290,292Lv agree well with the experimental data.

  13. Heavy-Ion Transfer Reactions with Deformed Nuclei

    NASA Astrophysics Data System (ADS)

    Helmer, Karl Gerard

    1992-01-01

    One-neutron transfer reactions involving actinide nuclei are used to investigate the effects of rotational motion on transfer populations. Deexcitation gamma rays were measured using a particle -particle-gamma triple coincidence method. Rotational states up to 28^{+ }(30^{+}) were seen in ^{234}U originating from the reaction ^{235}U( ^{206}Pb, ^ {207}Pb)^{234} U at a laboratory bombarding energy of 1394 MeV. Angular distributions for both inelastic excitation and transfer are presented and the one-neutron transfer reaction cross section as well as the grazing angle have been extracted. This study demonstrates the feasibility of using heavy-ion induced transfer reactions for spectroscopic studies. The second section of this thesis explores the question of diabolical pair transfer in nuclear physics using the reactions ^{206}Pb( ^{156}Gd, ^ {154}Gd)^{208} Pb (diabolical case) and ^{206 }Pb(^{156}Gd, ^{158}Gd)^ {204}Pb (nondiabolic case) at a laboratory bombarding energy of 888 MeV. Early calculations by Nikam, Ring and Canto predicted oscillatory behavior of pair transfer matrix elements as the cranking frequency was varied, within the cranking Hartree-Fock-Bogoliubov (CHFB) model, and explained this behavior as a manifestation of Berry's phase. Significant suppression of the high spin population in the diabolical nucleus was predicted. The diabolical point is supplied by the crossing of the ground-state band with the two-quasiparticle band. The strength of this band interaction is predicted to be oscillatory with chemical potential in the CHFB model. The study of pair transfer populations can therefore shed light not only on the possible existence of Berry's phase in nuclear systems, but also on whether the band interaction goes strictly to zero as predicted by the CHFB model. The results of this experiment agree with the latest calculations that the expected effects are more subtle than the earliest calculations predicted.

  14. Proton skins in momentum space and neutron skins in coordinate space in heavy nuclei

    NASA Astrophysics Data System (ADS)

    Cai, Bao-Jun; Li, Bao-An; Chen, Lie-Wen

    2016-12-01

    Neutron skins in coordinate space and proton skins in momentum space are predicted to coexist in heavy nuclei, and their correlation is governed by Liouville's theorem and Heisenberg's uncertainty principle. An analysis of their correlation within a further extended Thomas-Fermi approximation incorporating effects of nucleon short-range correlations reveals generally that protons move faster than neutrons in neutron skins of heavy nuclei.

  15. Generation of high-energy neutron beam by fragmentation of relativistic heavy nuclei

    NASA Astrophysics Data System (ADS)

    Yurevich, Vladimir

    2016-09-01

    The phenomenon of multiple production of neutrons in reactions with heavy nuclei induced by high-energy protons and light nuclei is analyzed using a Moving Source Model. The Lorentz transformation of the obtained neutron distributions is used to study the neutron characteristics in the inverse kinematics where relativistic heavy nuclei bombard a light-mass target. The neutron beam generated at 0∘has a Gaussian shape with a maximum at the energy of the projectile nucleons and an energy resolution σE/E < 4% above 6 GeV.

  16. Charge composition and energy spectra of ancient solar flare heavy nuclei. [in carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Goswami, J. N.; Lal, D.; Macdougall, J. D.

    1980-01-01

    Nuclear tracks in olivine grains from three carbonaceous chondrites are analyzed to determine the energy spectra and charge compositions of solar flare heavy nuclei during the early history of the solar system. Track length measurements of grains irradiated before compaction into meteorites over 4 billion years ago were performed accompanied by calibration experiments using heavy ion beams from an accelerator to identify tracks formed by very heavy (Z between 20 and 28) and very very heavy (Z greater than or equal to 30) groups of nuclei in the Murchison, Murray and Cold Bokkeveld meteorite grains. The time-averaged spectral shape of the solar flare very heavy nuclei is found to be similar to that obtained in lunar sample studies and direct observations. The meteorite grains also reproduce the currently observed enrichment of low-energy heavy ions in solar cosmic rays with respect to photospheric levels, with enhancement factors from 2 to 12 in the energy interval 6-10 MeV/n. Variations of very very heavy/very heavy nuclei abundance ratios within individual kinetic energy intervals are interpreted as representing possible changes of solar flare activity on time scales of 10,000 years.

  17. Interactions of heavy nuclei, Kr, Xe and Ho, in light targets

    NASA Technical Reports Server (NTRS)

    Kertzman, M. P.; Klarmann, J.; Newport, B. J.; Stone, E. C.; Waddington, C. J.; Binns, W. R.; Garrard, T. L.; Israel, M. H.

    1985-01-01

    Over the past few years, the HEAO-3 measurements of the abundance of ultra-heavy cosmic ray nuclei (Z 26) at Earth were analyzed. In order to interpret these abundances in terms of a source composition, allowances must be made for the propagation of the nuclei in the interstellar medium. Vital to any calculation of the propagation is a knowlege of the total and partial interaction cross sections for these heavy nuclei on hydrogen. Until recently, data on such reactions have been scarce. The semi-empirical formalism of Silberberg and Tsao were relied upon to predict the partial cross sections. However, now that relativistic heavy ion beams are available at the LBL Bevalac, some of the cross sections of interest can be measured at energies close to those of the cosmic ray nuclei being observed.

  18. Introduction to the study of collisions between heavy nuclei

    SciTech Connect

    Bayman, B.F.

    1980-01-01

    Current investigations concerning the collisions of nuclei governed by small de Broglie wavelengths are reviewed. The wave packets localize nuclei in regions small compared to their diameters. Cross sections are examined for potential scattering, elastic scattering, quasi-molecular states, peripheral particle-transfer reactions, fusion, and deep inelastic collisions. Theories of fusion and deep inelastic collisions are summarized. This paper is in the nature of a review-tutorial. 45 references, 51 figures, 2 tables. (RWR)

  19. {sup 231}Pa photofission cross section

    SciTech Connect

    Soldatov, A.S.; Rudnikov, V.E.; Smirenkin, G.N.

    1995-12-01

    The measurements of the {sup 231}Pa yield and cross section photofission in the energy range 7-9 MeV are presented. These measurements are a continuation of similar measurements performed for the {gamma}-ray energy range 4.8-7 MeV. The entire collection of experimental data which combine the results obtained in the present work and in Ref. 1 was analyzed.

  20. Interactions of heavy nuclei, Kr, Xe and Ho, in light targets

    NASA Technical Reports Server (NTRS)

    Kertzman, M. P.; Klarmann, J.; Newport, B. J.; Stone, E. C.; Waddington, C. J.; Binns, W. R.; Garrard, T. L.; Israel, M. H.

    1985-01-01

    Over the past few years, the HEAO-3 measurements of the abundances of ultra-heavy cosmic ray nuclei (Z 26) at earth have been analyzed. In order to interpret these abundances in terms of a source composition, allowance must be made for the propagation of the nuclei in the interstellar medium. Vital to any calculation of the propagation is a knowlege of the total and partial interaction cross sections for these heavy nuclei on hydrogen. Until recently, data on such reactions have been scarce. However, now that relativistic heavy ion beams are available at the LBL Bevalac, some of the cross sections of interest can be measured at energies close to those of the cosmic ray nuclei being observed. During a recent calibration at the Bevalac of an array similar to the HEAO-C3 UH-nuclei detector, targets of raphite (C), polyethylene (CH2), and aluminum were exposed to five heavy ion beams ranging in charge (Z) from 36 to 92. Total and partial charge changing cross sections for the various beam nuclei on hydrogen can be determined from the measured cross sections on C and CH2, and will be applied to the propagation problem. The cross sections on Al can be used to correct the abundances of UH cosmic rays observed in the HEAO C-3 detector for interactions in the detector itself.

  1. The Heavy Nuclei eXplorer (HNX) Mission

    NASA Technical Reports Server (NTRS)

    Binns, W. R.; Adams, J. H.; Barbier, L. M.; Craig, N.; Cummings, A. C.; Cummings, J. R.; Doke, T.; Hasebe, N.; Hayashi, T.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    The primary scientific objectives of HNX, which was recently selected by NASA for a Small Explorer (SMEX) Mission Concept Study, are to measure the age of the galactic cosmic rays (GCR) since nucleosynthesis, determine the injection mechanism for the GCR accelerator (Volatility or FIP), and study the mix of nucleosynthetic processes that contribute to the source of GCRs. The experimental goal of HNX is to measure the elemental abundances of all individual stable nuclei from neon through the actinides and possibly beyond. HNX is composed of two instruments: ECCO, which measures elemental abundances of nuclei with Z greater than or equal to 72, and ENTICE. which measures elemental abundances of nuclei with Z between 10 and 82. We describe the mission and the science that can be addressed by HNX.

  2. Charge-exchange resonances and restoration of Wigner's supersymmetry in heavy and superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Lutostansky, Yu. S.; Tikhonov, V. N.

    2016-11-01

    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 G and E 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 Δ E G-A of E G and E 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.

  3. Charge-exchange resonances and restoration of Wigner’s supersymmetry in heavy and superheavy nuclei

    SciTech Connect

    Lutostansky, Yu. S. Tikhonov, V. N.

    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.

  4. Studies of the Shapes of Heavy Nuclei at ISOLDE

    NASA Astrophysics Data System (ADS)

    Butler, Peter A.

    For certain combinations of protons and neutrons there is a theoretical expectation that the shape of nuclei can assume octupole deformation, which would give rise to reflection asymmetry or a "pear-shape" in the intrinsic frame, either dynamically (octupole vibrations) or statically (permanent octupole deformation). In this talk I will briefly review the historic evidence for reflection asymmetry in nuclei and describe how recent experiments carried out at REX-ISOLDE have constrained nuclear theory and how they contribute to tests of extensions of the Standard Model. I will also discuss future prospects for measuring nuclear shapes from Coulomb Excitation: experiments are being planned that will exploit beams from HIE-ISOLDE that are cooled in the TSR storage ring and injected into a solenoidal spectrometer similar to the HELIOS device developed at the Argonne National Laboratory.

  5. Triaxial shape fluctuations and quasiparticle excitations in heavy nuclei

    NASA Astrophysics Data System (ADS)

    Chen, Fang-Qi; Egido, J. Luis

    2017-02-01

    The deformation parameters (β ,γ ) together with two-quasiparticle excitations are taken into account, for the first time, as coordinates within a symmetry conserving (angular momentum and particle number) generator coordinate method. The simultaneous consideration of collective as well as single-particle degrees of freedom allows us to describe soft and rigid nuclei as well as the transition region in between. We apply the new theory to the study of the spectra and transition probabilities of the Er-172156 isotopes with a pairing-plus-quadrupole residual interaction. Good agreement with the experimental results is obtained for most of the observables studied and with the same quality for the very soft and the strongly deformed nuclei.

  6. One-quasiparticle states in odd-Z heavy nuclei

    SciTech Connect

    Adamian, G. G.; Antonenko, N. V.; Kuklin, S. N.; Scheid, W.

    2010-11-15

    The isotopic dependencies of one-quasiparticle states in Es and Md are treated. In {sup 253,255}Lr, the energies of the lowest one-quasiproton states are calculated. The one-quasiparticle isomer states are revealed in the nuclei of an {alpha}-decay chain starting from {sup 269}Rg. The {alpha} decays from some isomer states are predicted. The population of isomer states in the complete fusion reactions is discussed.

  7. Synthesis of New Neutron Rich Heavy Nuclei:. AN Experimentalist's View

    NASA Astrophysics Data System (ADS)

    Loveland, W.

    2014-09-01

    I attempt to experimentally evaluate the prospects of synthesizing new neutronrich superheavy nuclei. I consider three possible synthetic paths to neutronrich superheavy nuclei: (a) the use of neutron-rich radioactive beams. (b) the use of damped collisions and (c) the use of multi-nucleon transfer reactions. I consider the prospects of synthesizing new n-rich isotopes of Rf-Bh using light n-rich radioactive beams and targeted beams from ReA3, FRIB and SPIRAL2. For the damped collision path, I present the results of a study of a surrogate reaction, 160Gd + 186W. These data indicate the formation of Au (trans-target) fragments and the depletion of yields of target-like fragments by fission and fragment emission. The data are compared to predictions of Zagrebaev and Greiner. For the multi-nucleon transfer reactions, the results of a study of the 136Xe + 208Pb reaction are discussed. I consider the possibility of multi-nucleon transfer reactions with radioactive beams.

  8. {alpha} particle preformation in heavy nuclei and penetration probability

    SciTech Connect

    Zhang, H. F.; Royer, G.

    2008-05-15

    The {alpha} particle preformation in the even-even nuclei from {sup 108}Te to {sup 294}118 and the penetration probability have been studied. The isotopes from Pb to U have been firstly investigated since the experimental data allow us to extract the microscopic features for each element. The assault frequency has been estimated using classical methods and the penetration probability from tunneling through the Generalized Liquid Drop Model (GLDM) potential barrier. The preformation factor has been extracted from experimental {alpha} decay energies and half-lives. The shell closure effects play the key role in the {alpha} preformation. The more the nucleon number is close to the magic numbers, the more the formation of {alpha} cluster is difficult inside the mother nucleus. The penetration probabilities reflect that 126 is a neutron magic number. The penetration probability range is very large compared to that of the preformation factor. The penetration probability determines mainly the {alpha} decay half-life while the preformation factor allows us to obtain information on the nuclear structure. The study has been extended to the newly observed heaviest nuclei.

  9. Study of Complete Fusion Reactions Leading to the Production of Heavy and Superheavy Nuclei

    SciTech Connect

    Roman N. Sagaidak

    1999-12-31

    Cross section values for heavy evaporation residues (ER) produced in complete fusion reactions induced by heavy ions on spherical and deformed target nuclei are analyzed in the framework of barrier penetration and statistical model approximations. For the reactions leading to Rn-Pa nuclei, a strong influence of the entrance channel on the measured cross section values is observed for nearly symmetric projectile-target combinations. In order to reproduce the observed excitation functions in such combinations we had to introduce the quantity of fusion probability. Considering the asymmetric reactions leading to the heaviest nuclei we also had to use the fusion probability to reproduce the cross section values obtained for cold fusion reactions induced by {sup 50}Ti and heavier projectiles on the Pb and Bi target nuclei, and also the values obtained for hot fusion reactions induced by {sup 34}S on actinide target nuclei. The scaling of fusion probabilities derived for both the reactions allowed us to predict the values of cross sections for superheavy elements (SHE) produced in the {sup 48}Ca induced reactions on actinide target nuclei and in the cold fusion reactions induced by the Zn and heavier projectiles.

  10. Study of complete fusion reactions leading to the production of heavy and superheavy nuclei

    SciTech Connect

    Sagaidak, Roman N.

    1999-11-16

    Cross section values for heavy evaporation residues (ER) produced in complete fusion reactions induced by heavy ions on spherical and deformed target nuclei are analyzed in the framework of barrier penetration and statistical model approximations. For the reactions leading to Rn-Pa nuclei, a strong influence of the entrance channel on the measured cross section values is observed for nearly symmetric projectile-target combinations. In order to reproduce the observed excitation functions in such combinations we had to introduce the quantity of fusion probability. Considering the asymmetric reactions leading to the heaviest nuclei we also had to use the fusion probability to reproduce the cross section values obtained for cold fusion reactions induced by {sup 50}Ti and heavier projectiles on the Pb and Bi target nuclei, and also the values obtained for hot fusion reactions induced by {sup 34}S on actinide target nuclei. The scaling of fusion probabilities derived for both the reactions allowed us to predict the values of cross sections for superheavy elements (SHE) produced in the {sup 48}Ca induced reactions on actinide target nuclei and in the cold fusion reactions induced by the Zn and heavier projectiles.

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

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  12. Simulation of photofission experiments at the ELI-NP facility

    NASA Astrophysics Data System (ADS)

    Constantin, P.; Balabanski, D. L.; Cuong, P. V.

    2016-04-01

    An extensive experimental program for the study of photofission will take place at the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility, where different actinide targets will be exposed to a brilliant gamma beam to produce fission fragments. We report on the implementation within the Geant4 simulation toolkit of the photofission process, of related background processes, and of extended ionic charge parameterization. These developments are used to evaluate the production rates of photofission fragments and their release efficiency from the actinide targets.

  13. Proximity potential for heavy ion reactions on deformed nuclei

    SciTech Connect

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

    1982-01-01

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

  14. Heavy-quark and lepton-pair production on nuclei

    SciTech Connect

    Boreskov, K.; Capella, A.; Kaidalov, A.; Tran Thanh Van, J. )

    1993-02-01

    We present a description of the [ital A] dependence of heavy-quark and Drell-Yan pair production in hadron-nucleus collisions, based on the Reggeon approach to strong interactions at high energies and the parton model. The same method has been successfully applied to the production of light-quark states. The existence of a new energy scale, which depends on the mass and [ital x][sub [ital F

  15. Model-space approach to parity violation in heavy nuclei

    SciTech Connect

    Johnson, M.B.

    1996-06-01

    The model-space approach is the basis of both shell model and statistical spectroscopy analyses of nuclear phenomena. The goal of this session is to bring out the main theoretical issues involved in its application to parity violation in the compound nucleus. Section 1 of the current paper sets the stage for the session, and Sect. 2 introduces and explores the model-space formulation as it underlies quantitative connections that are being made between the mean-square matrix element M{sup 2} measured in polarized neutron scattering from compound nuclei and the underlying parity violating interaction. This is followed in the paper by Tomsovic by a description of how statistical spectroscopy is applied to this problem, and in the paper by Hayes by a discussion of shell-model aspects of parity violation in the compound nucleus.

  16. Long Fission Times of Super-Heavy Compound Nuclei

    SciTech Connect

    Drouart, A.; Charvet, J. L.; Dayras, R.; Nalpas, L.; Volant, C.; Jacquet, D.

    2008-04-17

    The blocking technique in single crystals is a direct method to investigate the presence of long fission time components. With a lead beam impinging on a germanium single crystal, we tried to produce compound nuclei (CN) with atomic number Z = 114 at high excitation energy. Blocking patterns for reaction products are reconstructed with position sensitive detectors at 20 deg. relative to the beam direction. The Z and the energies of all products are measured with {delta}E-E telescopes of the 4{pi} INDRA array, so that all reaction channels are unambiguously identified. With this setup, we can reach long fission times (>10{sup -18} s) that can be associated with CN fissions. However, in contrast to previous experiments in which such long fission times could be measured for Z = 120 and 124, no hint of long lifetimes within our sensitivity limit for Z = 114 was observed, which may be due to the neutron deficiency of the formed isotopes.

  17. Analysis of quasifission competition in fusion reactions forming heavy nuclei

    NASA Astrophysics Data System (ADS)

    Hammerton, Kalee; Kohley, Zachary; Morrissey, Dave; Wakhle, Aditya; Stiefel, Krystin; Hinde, David; Dasgupta, Mahananda; Williams, Elizabeth; Simenel, Cedric; Carter, Ian; Cook, Kaitlin; Jeung, Dongyun; Luong, Duc Huy; McNeil, Steven; Palshetkar, Chandani; Rafferty, Dominic

    2015-10-01

    Heavy-ion fusion reactions have provided a mechanism for the production of superheavy elements allowing for the extension of both the periodic table and chart of the nuclides. However, fusion of the projectile and target, forming a compound nucleus, is hindered by orders of magnitude by the quasifission process in heavy systems. In order to fully understand this mechanism, and make accurate predictions for superheavy element production cross sections, a clear description of the interplay between the fusion-fission and quasifission reaction channels is necessary. The mass-angle distributions of fragments formed in 8 different Cr + W reactions were measured at the Australia National University in order to explore the N/Z dependence of the quasifission process. Two sets of data were measured: one at a constant energy relative to the fusion barrier and one at a constant compound nucleus excitation energy. The results of this analysis will provide insight into the effect of using more neutron-rich beams in superheavy element production reactions.

  18. Competition between complete fusion and quasifission in reactions with heavy nuclei

    SciTech Connect

    Antonenko, N. V.; Scheid, W.; Adamian, G. G.; Volkov, V. V.

    1998-02-15

    A model based on the dinuclear system concept is suggested for the calculation of the competition between complete fusion and quasifission in reactions with heavy nuclei. The fusion rate through the inner fusion barrier in mass asymmetry is found by using the Kramers-type expression. The calculated cross sections for the heaviest nuclei are in a good agreement with the experimental data. The experimentally observed rapid fall-off of the cross section of the cold fusion with increasing charge number Z of the compound nucleus is explained.

  19. Neutron productions in the fragmentation of relativistic heavy nuclei and formation of a beam of high-energy neutrons

    SciTech Connect

    Yurevich, V. I.

    2016-03-15

    The production of quasimonoenergetic high-energy neutrons at zero angle (0°) in the spallation of relativistic heavy nuclei is discussed by considering the example of the interaction of lead nuclei with light target nuclei. It is shown that this process can be used to generate a beam of high-energy neutrons at existing heavy ion accelerators. At the same time, itmay lead to the appearance of a parasitic neutron beam because of the interaction of the heavy-ion beam used with beam line and experimental setup materials.

  20. Isospin dependence of fragment spectra in heavy/super-heavy colliding nuclei at intermediate energies

    SciTech Connect

    Chugh, Rajiv Kumar, Rohit; Vinayak, Karan Singh

    2016-05-06

    Using isospin-dependent quantum molecular dynamics (IQMD) approach, we performed a theoretical investigation of the evolution of various kinds of fragments in heavy and superheavy-ion reactions in the intermediate/medium energy domain. We demonstrated direct impact of symmetry energy and Coulomb interactions on the evolution of fragments. Final fragment spectra (yields) obtained from the analysis of various heavy/super-heavy ion reactions at different reaction conditions show high sensitivity towards Coulomb interactions and less significant sensitivity to symmetry energy forms. No inconsistent pattern of fragment structure is obtained in case of super-heavy ion involved reactions for all the parameterizations of density dependence of symmetry energy.

  1. Bridging the nuclear structure gap between stable and super heavy nuclei.

    SciTech Connect

    Seweryniak, D.; Khoo, T. L.; Ahmad, I.; Kondev, F. G.; Robinson, A.; Back, B. B.; Carpenter, M. P.; Davids, C. N.; Greene, J. P.; Gros, S.; Janssens, R. V. F.; Lauritsen, T.; Lister, C. J.; McCutchan, E. A.; Peterson, D.; Zhu, S. F.; Physics; Univ. of York; Univ. of Massachusetts at Lowell; Japan Atomic Energy Agency; Univ. of Jyvaskyla; CSNSM Orsay; Yale Univ.; Univ. of Liverpool; RIKEN; Univ. of Maryland; Univ. of Notre Dame

    2010-01-01

    Due to recent advances in detection techniques, excited states in several trans-fermium nuclei were studied in many laboratories worldwide, shedding light on the evolution of nuclear structure between stable nuclei and the predicted island of stability centered around spherical magic numbers. In particular, studies of K-isomers around the Z=100 and N=152 deformed shell closures extended information on the energies of Nilsson orbitals at the Fermi surface. Some of these orbitals originate from spherical states, which are relevant to the magic gaps in super-heavy nuclei. The single-particle energies can be used to test various theoretical predictions and aid in extrapolations towards heavier systems. So far, the Woods-Saxon potential reproduces the data best, while self-consistent approaches miss some of the observed features, indicating a need to modify the underlying effective nucleon-nucleon interactions.

  2. Bridging the nuclear structure gap between stable and super heavy nuclei

    NASA Astrophysics Data System (ADS)

    Seweryniak, D.; Khoo, T. L.; Ahmad, I.; Kondev, F. G.; Robinson, A.; Tandel, S. K.; Asai, M.; Back, B. B.; Carpenter, M. P.; Chowdhury, P.; Davids, C. N.; Eeckhaudt, S.; Greene, J. P.; Greenlees, P. T.; Gros, S.; Hauschild, K.; Heinz, A.; Herzberg, R.-D.; Janssens, R. V. F.; Jenkins, D. G.; Jones, G. D.; Ketelhut, S.; Lauritsen, T.; Lister, C. J.; Lopez-Martens, A.; Marley, P.; McCutchan, E. A.; Nakatsukasa, T.; Papadakis, P.; Peterson, D.; Qian, J.; Rostron, D.; Stefanescu, I.; Tandel, U. S.; Wang, X. F.; Zhu, S. F.

    2010-03-01

    Due to recent advances in detection techniques, excited states in several trans-fermium nuclei were studied in many laboratories worldwide, shedding light on the evolution of nuclear structure between stable nuclei and the predicted island of stability centered around spherical magic numbers. In particular, studies of K-isomers around the Z=100 and N=152 deformed shell closures extended information on the energies of Nilsson orbitals at the Fermi surface. Some of these orbitals originate from spherical states, which are relevant to the magic gaps in super-heavy nuclei. The single-particle energies can be used to test various theoretical predictions and aid in extrapolations towards heavier systems. So far, the Woods-Saxon potential reproduces the data best, while self-consistent approaches miss some of the observed features, indicating a need to modify the underlying effective nucleon-nucleon interactions.

  3. A statistical approach to describe highly excited heavy and superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Chen, Peng-Hui; Feng, Zhao-Qing; Li, Jun-Qing; Zhang, Hong-Fei

    2016-09-01

    A statistical approach based on the Weisskopf evaporation theory has been developed to describe the de-excitation process of highly excited heavy and superheavy nuclei, in particular for the proton-rich nuclei. The excited nucleus is cooled by evaporating γ-rays, light particles (neutrons, protons, α etc) in competition with binary fission, in which the structure effects (shell correction, fission barrier, particle separation energy) contribute to the processes. The formation of residual nuclei is evaluated via sequential emission of possible particles above the separation energies. The available data of fusion-evaporation excitation functions in the 28Si+198Pt reaction can be reproduced nicely within the approach. Supported by Major State Basic Research Development Program in China (2015CB856903), National Natural Science Foundation of China Projects (11175218, U1332207, 11475050, 11175074), and Youth Innovation Promotion Association of Chinese Academy of Sciences

  4. Indication of a mini-valence Wigner-like energy in heavy nuclei

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    Certain double differences of binding energies can be constructed that exhibit the valence proton-neutron interaction. These double differences, known as δVpn(Z,N), show singularities in light N=Z even-even nuclei (and N=Z-1 even-Z, odd-N nuclei) due to uniquely large overlaps of the proton and neutron wave functions and the short-range residual interaction. It is suggested that a similar phenomenon appears, heavily muted, in heavy nuclei as well, when one considers valence nucleon numbers. It is proposed that it arises from the overall similarity of the sequences of orbits in different major shells, giving higher overlaps when the respective proton and neutron shells are approximately equally filled.

  5. Nonlinear ion-acoustic waves in a degenerate plasma with nuclei of heavy elements

    SciTech Connect

    Hossen, M. A. Mamun, A. A.

    2015-10-15

    The ion-acoustic (IA) solitary waves propagating in a fully relativistic degenerate dense plasma (containing relativistic degenerate electron and ion fluids, and immobile nuclei of heavy elements) have been theoretically investigated. The relativistic hydrodynamic model is used to derive the Korteweg-de Vries (K-dV) equation by the reductive perturbation method. The stationary solitary wave solution of this K-dV equation is obtained to characterize the basic features of the IA solitary structures that are found to exist in such a degenerate plasma. It is found that the effects of electron dynamics, relativistic degeneracy of the plasma fluids, stationary nuclei of heavy elements, etc., significantly modify the basic properties of the IA solitary structures. The implications of this results in astrophysical compact objects like white dwarfs are briefly discussed.

  6. Systematics of α-decay and spontaneous fission half-lives of super-heavy nuclei

    NASA Astrophysics Data System (ADS)

    Silisteanu, Ion; Anghel, Claudia-Ioana

    2017-01-01

    Simple relationships derived from the systematics of data and calculated α-decay and spontaneous fission half-lives are used to predict half-lives and branches for many still unknown super-heavy nuclei. Half-life calculations are performed within the shell model rate theory for α-decay, and a dynamical approach for spontaneous fission defined essentially by the shape, the hight of fission barrier, the fissility and nuclear deformations. Extensive half-lives predictions are made for many unknown super-heavy nuclei. The comparison of the behavior of measured α-decay properties with expectations from theoretical approximations (with and without; finite size corrections, resonance scattering effects, deformations and shell structure) provides insight into the accuracy of current nuclear models for the reaction dynamics and structure.

  7. A mechanism for the abundance enhancements of heavy nuclei in solar flare particle events

    NASA Technical Reports Server (NTRS)

    Cartwright, B. G.; Mogro-Campero, A.

    1973-01-01

    A mechanism is proposed to account for the recently reported abundance enhancements of heavy nuclei in solar flares. The mechanism requires two acceleration stages for its operation: First, fully stripped ions are accelerated to suprathermal energies, and subsequently, a fraction of these ions are Fermi accelerated to higher energies. It is shown that because injection into Fermi acceleration is rigidity dependent and the ions may pick up electrons during transport to the Fermi acceleration region, an enhancement of the abundances of heavy nuclei can occur. The degree of the enhancement depends on a number of factors particular to each flare, so that the degree of enhancement may be variable from flare to flare, or may be a function of time within a given flare. In some flares, conditions may be such that no enhancement would be expected.

  8. Properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei

    SciTech Connect

    Gorelik, M. L. Shlomo, Sh. Tulupov, B. A. Urin, M. H.

    2015-07-15

    The recently developed particle-hole dispersive optical model is applied to describe properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei. In particular, the double transition density averaged over the energy of the isoscalar monopole excitations is considered for {sup 208}Pb in a wide energy interval, which includes the isoscalar giant monopole resonance and its overtone. The energy-averaged strength functions of these resonances are also analyzed.

  9. New semi-empirical formula for α -decay half-lives of the heavy and superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.; Sridhar, K. N.

    2017-07-01

    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.

  10. Nuclear structure and weak rates of heavy waiting point nuclei under rp-process conditions

    NASA Astrophysics Data System (ADS)

    Nabi, Jameel-Un; Böyükata, Mahmut

    2017-01-01

    The structure and the weak interaction mediated rates of the heavy waiting point (WP) nuclei 80Zr, 84Mo, 88Ru, 92Pd and 96Cd along N = Z line were studied within the interacting boson model-1 (IBM-1) and the proton-neutron quasi-particle random phase approximation (pn-QRPA). The energy levels of the N = Z WP nuclei were calculated by fitting the essential parameters of IBM-1 Hamiltonian and their geometric shapes were predicted by plotting potential energy surfaces (PESs). Half-lives, continuum electron capture rates, positron decay rates, electron capture cross sections of WP nuclei, energy rates of β-delayed protons and their emission probabilities were later calculated using the pn-QRPA. The calculated Gamow-Teller strength distributions were compared with previous calculation. We present positron decay and continuum electron capture rates on these WP nuclei under rp-process conditions using the same model. For the rp-process conditions, the calculated total weak rates are twice the Skyrme HF+BCS+QRPA rates for 80Zr. For remaining nuclei the two calculations compare well. The electron capture rates are significant and compete well with the corresponding positron decay rates under rp-process conditions. The finding of the present study supports that electron capture rates form an integral part of the weak rates under rp-process conditions and has an important role for the nuclear model calculations.

  11. Microscopic dynamics simulations of heavy-ion fusion reactions induced by neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Wang, Ning; Ou, Li; Zhang, Yingxun; Li, Zhuxia

    2014-06-01

    The heavy-ion fusion reactions induced by neutron-rich nuclei are investigated with the improved quantum molecular dynamics (ImQMD) model. With a subtle consideration of the neutron skin thickness of nuclei and the symmetry potential, the stability of nuclei and the fusion excitation functions of heavy-ion fusion reactions O16 + Ge76, O16 + Sm154, Ca40 + Zr96, and Sn132 + Ca40 are systematically studied. The fusion cross sections of these reactions at energies around the Coulomb barrier can be well reproduced by using the ImQMD model. The corresponding slope parameter of the symmetry energy adopted in the calculations is L ≈78 MeV and the surface energy coefficient is gsur=18±1.5 MeV fm2. In addition, it is found that the surface-symmetry term significantly influences the fusion cross sections of neutron-rich fusion systems. For sub-barrier fusion, the dynamical fluctuations in the densities of the reaction partners and the enhanced surface diffuseness at neck side result in the lowering of the fusion barrier.

  12. Excitation energies of double isobar-analog states in heavy nuclei

    SciTech Connect

    Poplavskii, I. V.

    1988-12-01

    Several new relationships are established for isomultiplets on the basis of a theory in which the Coulomb coupling constant (CCC) is allowed to be complex. In particular, the following rule is formulated: the energies for fission or decay of members of an isomultiplet into a charged cluster and members of the corresponding daughter isomultiplet are equidistant. This relationship is well satisfied for isomultiplets with /ital A/less than or equal to60. By extrapolating the rule for fission and decay energies to the region of heavy nuclei, the excitation energies /ital E//sub /ital x// of double isobar-analog states (DIASs) are found for the nuclei /sup 197,199/Hg, /sup 205/Pb, /sup 205 - -209/Po, /sup 209/At, and /sup 238/Pu. A comparison of the computed energies /ital E//sub /ital x// with the experimentally measured values for /sup 208/Po attest to the reliability and good accuracy of the method proposed here when used to determine the excitation energies of DIASs in heavy nuclei.

  13. Observation of mass-asymmetric fission of mercury nuclei in heavy ion fusion

    NASA Astrophysics Data System (ADS)

    Prasad, E.; Hinde, D. J.; Ramachandran, K.; Williams, E.; Dasgupta, M.; Carter, I. P.; Cook, K. J.; Jeung, D. Y.; Luong, D. H.; McNeil, S.; Palshetkar, C. S.; Rafferty, D. C.; Simenel, C.; Wakhle, A.; Khuyagbaatar, J.; Düllmann, Ch. E.; Lommel, B.; Kindler, B.

    2015-06-01

    Background: Mass-asymmetric fission has been observed in low energy fission of 180Hg . Calculations predicted the persistence of asymmetric fission in this region even at excitation energies of 30-40 MeV. Purpose: To investigate fission mass distributions by populating different isotopes of Hg using heavy ion fusion reactions. Methods: Fission fragment mass-angle distributions have been measured for two reactions, 40Ca+142Nd and 13C+182W , populating 182Hg and 195Hg , respectively, using the Heavy Ion Accelerator Facility and CUBE spectrometer at the Australian National University. Measurements were made at beam energies around the capture barrier for the two reactions and mass ratio distributions were obtained using the kinematic reconstruction method. Results: Asymmetric fission has been observed following the population of 182Hg at an excitation energy of 22.8 MeV above the saddle point. A symmetric peaked mass ratio distribution was observed for 195Hg nuclei at a similar excitation energy above the saddle point. Conclusions: Mass-asymmetric fission has been observed in neutron deficient Hg nuclei populated via heavy ion fusion for the first time. The results are consistent with observations from beta-delayed fission measurements and provide a proof-of-principle for expanding experimental studies of the influence of shell effects on the fission processes.

  14. Pulsed Photofission Delayed Gamma Ray Detection for Nuclear Material Identification

    SciTech Connect

    John Kavouras; Xianfei Wen; Daren R. Norman; Dante R. Nakazawa; Haori Yang

    2012-11-01

    Innovative systems with increased sensitivity and resolution are in great demand to detect diversion and to prevent misuse in support of nuclear materials management for the U.S. fuel cycle. Nuclear fission is the most important multiplicative process involved in non-destructive active interrogation. This process produces the most easily recognizable signature for nuclear materials. High-energy gamma rays can also excite a nucleus and cause fission through a process known as photofission. After photofission reactions, delayed signals are easily distinguishable from the interrogating radiation. Linac-based, advanced inspection techniques utilizing the fission signals after photofission have been extensively studied for homeland security applications. Previous research also showed that a unique delayed gamma ray energy spectrum exists for each fissionable isotope. Isotopic composition measurement methods based on delayed gamma ray spectroscopy will be the primary focus of this work.

  15. Formation of Heavy Compound Nuclei, Their Survival and Correlation with Longtime-Scale Fission

    SciTech Connect

    Karamian, S. A.; Yakushev, A.-B.

    2007-05-22

    Fusion of two massive nuclei with formation of super-heavy compound nucleus (CN) is driven by the potential energy gradient, as follows from the analysis of nuclear reaction cross-sections. The conservative energy of the system is deduced in simple approximation using regularized nuclear mass and interaction barrier values. Different reaction for the synthesis of Zc (110-118) nuclei are compared and the favourable conditions are found for fusion of the stable (W-Pt) isotopes with radioactive fission fragment projectiles, like 94Kr or 100Sr. Thus, the cold fusion method can be extended for a synthesis of elements with Z > 113. Survival of the evaporation residue is defined by the neutron-to-fission probability ratio and by the successful emission of gammas at final step of the reaction. Numerical estimates are presented. Fixation of evaporation residue products must correlate with longtime-scale fission and available experimental results are discussed.

  16. Photo-disintegration of heavy nuclei at the core of Cen A

    SciTech Connect

    Kundu, Esha; Gupta, Nayantara E-mail: nayan@rri.res.in

    2014-04-01

    Fermi LAT has detected gamma ray emissions from the core of Cen A. More recently, a new component in the gamma ray spectrum from the core has been reported in the energy range of 4 GeV to tens of GeV. We show that the new component and the HESS detected spectrum of gamma rays from the core at higher energy have possibly a common origin in photo-disintegration of heavy nuclei. Assuming the cosmic rays are mostly Fe nuclei inside the core and their spectrum has a low energy cut-off at 52 TeV in the wind frame moving with a Doppler factor 0.25 with respect to the observer on earth, the cosmic ray luminosity required to explain the observed gamma ray flux above 1 GeV is found to be 1.5 × 10{sup 43} erg/sec.

  17. Frequency of light-flashes induced by Cerenkov radiation from heavy cosmic-ray nuclei

    NASA Technical Reports Server (NTRS)

    Madey, R.; Mcnulty, P. J.

    1972-01-01

    The expected frequency was calculated for light flashes induced in the dark-adapted eye by Cerenkov radiation from the flux of heavy nuclei that exists in space beyond the geomagnetic field. The expected frequency of light flashes depends on the threshold number of photons that must be absorbed in a rod cluster. The results of the calculation are presented as a curve of the mean frequency of light flashes versus the threshold number of absorbed photons. The results are not sensitive to variations in the path length from 5 to 15 grams per square centimeter of water-equivalent before the nucleus reaches the retina. Calculations were based on the fluxes and energy spectra of galactic cosmic ray nuclei of helium to iron, measured at a time of minimum solar modulation. The expected light flash frequencies induced by Cerenkov radiation are consistent with the frequencies reported by the astronauts on Apollo missions 11 through 14.

  18. Cluster decay in very heavy nuclei in a relativistic mean field model

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Madhubrata; Gangopadhyay, G.

    2008-02-01

    Exotic cluster decay of very heavy nuclei was studied in the microscopic Super-Asymmetric Fission Model. The Relativistic Mean Field model with the force FSU Gold was employed to obtain the densities of the cluster and the daughter nuclei. The microscopic nuclear interaction DDM3Y1, which has an exponential density dependence, and the Coulomb interaction were used in the double folding model to obtain the potential between the cluster and the daughter. Half-life values were calculated in the WKB approximation and the spectroscopic factors were extracted. The latter values are seen to have a simple dependence of the mass of the cluster as has been observed earlier. Predictions were made for some possible decays.

  19. In search of a broader microscopic underpinning of the potential energy surface in heavy deformed nuclei

    NASA Astrophysics Data System (ADS)

    Hess, P. O.; Ermamatov, M.

    2017-07-01

    Starting from the content of the shell model space and using a simple symplectic as a weight Hamiltonian, the relative positions of different symplectic irreducible representations are deduced. Applying a geometrical mapping leads to a microscopically derived Potential-Energy-Surface. After smoothing this surface and fitting a mass parameter to the first excited 6+-state in the ground state band, the spectrum of a nucleus can be reproduced qualitatively. The method is also used to obtain a first estimation of the quadrupole Potential Energy Surface of any nucleus, allowing to obtain information about the structure of the nucleus in question. Of special interest is the prediction of the structure of nuclei away from the valley of stability and of super-heavy nuclei. The method will be illustrated at184W. One objective is to show that the Pauli Exclusion Principle is the main driving force for the structure of a nucleus, though some further microscopic input has to be used.

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

    NASA Astrophysics Data System (ADS)

    Heinz, S.; Comas, V.; Hofmann, S.; Ackermann, D.; Heredia, J.; Heβberger, F. P.; Khuyagbaatar, J.; Kindler, B.; Lommel, B.; Mann, R.

    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 58,64Ni + 207Pb and 48Ca + 248Cm 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.

  1. Ion acoustic shock waves in a degenerate relativistic plasma with nuclei of heavy elements

    NASA Astrophysics Data System (ADS)

    Atteya, A.; Behery, E. E.; El-Taibany, W. F.

    2017-03-01

    Based on the quantum hydrodynamics theory, a rigorous model for ion acoustic shock waves (IASWs) in a degenerate relativistic plasma with heavy ion nuclei is presented. Two cases are considered: the ultra-relativistic case and the non-relativistic case. A Korteweg-de Vries-Burger's (KdVB) equation describing IASWs in such plasma is derived, then its explicit as well as oscillatory solutions are deduced. It is found that the shape of IASWs is influenced by the particle density of degenerate electrons, the concentration of heavy elements, the viscosity coefficient, and the quantum Bohm potential term. The results should be useful in understanding the shock wave characteristics in degenerate plasma which is found in compact astrophysical objects.

  2. Extracting nuclear sizes of medium to heavy nuclei from total reaction cross sections

    NASA Astrophysics Data System (ADS)

    Horiuchi, W.; Hatakeyama, S.; Ebata, S.; Suzuki, Y.

    2016-04-01

    Background: Proton and neutron radii are fundamental quantities of atomic nuclei. To study the sizes of short-lived unstable nuclei, there is a need for an alternative to electron scattering. Purpose: The recent paper by Horiuchi et al. [Phys. Rev. C 89, 011601(R) (2014)], 10.1103/PhysRevC.89.011601 proposed a possible way of extracting the matter and neutron-skin thickness of light- to medium-mass nuclei using total reaction cross section, σR. The analysis is extended to medium to heavy nuclei up to lead isotopes with due attention to Coulomb breakup contributions as well as density distributions improved by paring correlation. Methods: We formulate a quantitative calculation of σR based on the Glauber model including the Coulomb breakup. To substantiate the treatment of the Coulomb breakup, we also evaluate the Coulomb breakup cross section due to the electric dipole field in a canonical-basis-time-dependent-Hartree-Fock-Bogoliubov theory in the three-dimensional coordinate space. Results: We analyze σR's of 103 nuclei with Z =20 , 28, 40, 50, 70, and 82 incident on light targets, H,21, 4He, and 12C. Three kinds of Skyrme interactions are tested to generate those wave functions. To discuss possible uncertainty due to the Coulomb breakup, we examine its dependence on the target, the incident energy, and the Skyrme interaction. The proton is a most promising target for extracting the nuclear sizes as the Coulomb excitation can safely be neglected. We find that the so-called reaction radius, aR=√{σR/π } , for the proton target is very well approximated by a linear function of two variables, the matter radius and the skin thickness, in which three constants depend only on the incident energy. We quantify the accuracy of σR measurements needed to extract the nuclear sizes. Conclusions: The proton is the best target because, once the incident energy is set, its aR is very accurately determined by only the matter radius and neutron-skin thickness. If σR's at

  3. Interpretation of the mechanism of spontaneous fission of heavy nuclei in the framework of dinuclear system conception

    NASA Astrophysics Data System (ADS)

    Volkov, V. V.; Cherepanov, E. A.; Kalandarov, Sh. A.

    2016-11-01

    The new approach to the interpretation of the process of spontaneous fission of heavy nuclei is suggested. It is based on nuclear physics data which are obtained in heavy ion collisions. The process of spontaneous fission consists of three sequential stages: clusterization of the valent nucleons of a heavy nucleus into a light nucleus-cluster, which leads to the formation of a dinuclear system; evolution of the dinuclear system which proceeds by nucleon transfer from the heavy to light nucleus and decay of the dinuclear system from the equilibrium configuration into two fragments.

  4. Development of the Experimental Setup Dedicated for Alpha, Gamma and Electron Spectroscopy of Heavy Nuclei at FLNR JINR

    SciTech Connect

    Yeremin, A.; Malyshev, O.; Popeko, A.; Lopez-Martens, A.; Hauschild, K.; Dorvaux, O.; Saro, S.; Pantelika, D.

    2010-04-30

    Various types of reactions and identification techniques were applied in the investigation of formation cross sections and decay properties of transuranium elements. The fusion--evaporation reactions with heavy targets, recoil--separation techniques and identification of nuclei by the parent--daughter generic coincidences with the known daughter-nuclei after implantation into position--sensitive detectors were the most successful tools for production and identification of the heaviest elements known presently. This technique may be further improved and presently it may be very promising for the identification of new elements, search for new isotopes and measurement of new decay data for the known nuclei.At the Flerov Laboratory of Nuclear Reactions (JINR, Dubna), investigations of the complete fusion reactions leading to the synthesis of heavy and superheavy nuclei with the use of heavy ion beams from a powerful U400 cyclotron have been an important part of the experimental program. It is planned to upgrade U400 cyclotron of the FLNR, to deliver beams with higher intensities and smooth variation of energies.New experimental set up, the velocity filter, is now developing for synthesis and studies of the decay properties of heavy nuclei. At the focal plane of the separator GABRIELA set up (alpha,beta,gamma detectors array) will be installed.

  5. Development of the Experimental Setup Dedicated for Alpha, Gamma and Electron Spectroscopy of Heavy Nuclei at FLNR JINR

    NASA Astrophysics Data System (ADS)

    Yeremin, A.; Malyshev, O.; Popeko, A.; Lopez-Martens, A.; Hauschild, K.; Dorvaux, O.; Saro, S.; Pantelika, D.

    2010-04-01

    Various types of reactions and identification techniques were applied in the investigation of formation cross sections and decay properties of transuranium elements. The fusion—evaporation reactions with heavy targets, recoil—separation techniques and identification of nuclei by the parent—daughter generic coincidences with the known daughter-nuclei after implantation into position—sensitive detectors were the most successful tools for production and identification of the heaviest elements known presently. This technique may be further improved and presently it may be very promising for the identification of new elements, search for new isotopes and measurement of new decay data for the known nuclei. At the Flerov Laboratory of Nuclear Reactions (JINR, Dubna), investigations of the complete fusion reactions leading to the synthesis of heavy and superheavy nuclei with the use of heavy ion beams from a powerful U400 cyclotron have been an important part of the experimental program. It is planned to upgrade U400 cyclotron of the FLNR, to deliver beams with higher intensities and smooth variation of energies. New experimental set up, the velocity filter, is now developing for synthesis and studies of the decay properties of heavy nuclei. At the focal plane of the separator GABRIELA set up (α,β,γ detectors array) will be installed.

  6. Post-launch analysis of data from the High Energy Astrophysical Observatory Heavy Nuclei Experiment (HEAO-C3)

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1992-01-01

    The Final Report on the continuing analysis of data from the Heavy Nuclei Experiment (HNE), flown on the HEAO-3 mission, is presented. The HNE was designed to measure the elemental abundances of relativistic cosmic ray nuclei covering the charge range 17 is less than or equal to Z is less than or equal to 130. The result of these measurements is significant to the study of nucleosynthesis, the origin, acceleration, and propagation of cosmic ray nuclei, and the properties of the interstellar medium.

  7. Production cross sections of heavy neutron-rich nuclei approaching the nucleosynthesis r-process path around A =195

    NASA Astrophysics Data System (ADS)

    Kurtukian-Nieto, T.; Benlliure, J.; Schmidt, K.-H.; Audouin, L.; Becker, F.; Blank, B.; Casarejos, E.; Farget, F.; Fernández-Ordóñez, M.; Giovinazzo, J.; Henzlova, D.; Jurado, B.; Pereira, J.; Yordanov, O.

    2014-02-01

    In the present work we were able to synthesize and measure with high accuracy the production cross sections of more than 190 heavy neutron-rich nuclei by the in-flight fragmentation of relativistic 208Pb projectiles, 26 of which were produced for the first time. This work has shown that the N =126 region far below the doubly magic 208Pb has become accessible experimentally and represents a step further towards the study of heavy neutron-rich nuclei approaching the r-process waiting point at A =195.

  8. Neutron transfer and flow in reactions between heavy neutron-rich nuclei.

    NASA Astrophysics Data System (ADS)

    Shapira, Dan; Liang, Felix J.; Gross, Carl J.; Varner, Robert L.; Beene, James R.

    2006-10-01

    Two Step WKB calcualtions of nucleus nucleus capture were carried out. In our calcualtions we nvestigate the possibility of enhanced capture cross sectins for neutron rich heavy nuclei. The model calculation uses a systematic potential [1] that incorporates the effect of barrier distributions due to excitation and deformation in the entrance channel. Neutron transfer is treated in a semiclassical approximation [2][3]. The transfer form factor used in neutron transfer saturates at an internuclear distance where where neutron can flow freely between the two nuclear centers [4]. [1] K. Siwek-Wilczynska and J. Wilczynski Phys. Rev. C69, 024611 (2004). [2] V. Yu. Denisov Eur. Phys. A7, 87 (2000). [3] V. I. Zagrebaev Phys. Rev. C7, 061601R (2003). [4] P.H. Stelson Phys. Lett. B205, 190 (1988).

  9. Microscopic Analysis of the α-DECAY in Heavy and Superheavy Nuclei

    NASA Astrophysics Data System (ADS)

    Delion, D. S.; Sandulescu, A.; Greiner, W.

    2004-09-01

    We analyze the α-decay along N - Z chains in heavy and superheavy nuclei. The α-particle preformation amplitude is estimated within the pairing model, while the penetration part by the deformed WKB approach. We show that for N > 126 the plateau condition is not fulfilled along any α-chain, namely the logarithmic derivative of the Coulomb function changes much faster in comparison with that of the preformation factor. We correct this deficiency by considering an α-cluster factor in the preformation amplitude, depending upon the Coulomb parameter. For superheavy region an additional dependence upon the number of interacting α-particles indicates a clustering feature connected with a larger radial component.

  10. Theoretical description of fine structure in the α decay of heavy odd-odd nuclei

    NASA Astrophysics Data System (ADS)

    Ni, Dongdong; Ren, Zhongzhou

    2013-02-01

    The newly developed multichannel cluster model (MCCM), based on the coupled-channel Schrödinger equation with outgoing wave boundary conditions, is extended to study the α-decay fine structure in heavy odd-odd nuclei. Calculations are performed for the α transitions to favored rotational bands where the unpaired nucleons remain unchanged. The simple WKB barrier penetration formula is also used to evaluate the branching ratios for various daughter states. It is found that the WKB formula seems to overestimate the branching ratios for the second and third members of the favored rotational band, while the MCCM gives a precise description of them without any adjustable parameters. Moreover, the experimental total α-decay half-lives are well reproduced within the MCCM.

  11. Shell Effects in Fusion-Fission of Heavy and Superheavy Nuclei

    NASA Astrophysics Data System (ADS)

    Itkis, M. G.; Bogatchev, A. A.; Itkis, I. M.; Jandel, M.; Kliman, J.; Kniajeva, G. N.; Kondratiev, N. A.; Korzyukov, I. V.; Kozulin, E. M.; Krupa, L.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Prokhorova, E. V.; Voskresenski, V. M.; Zagrebaev, V. I.; Rusanov, A. Ya.; Corradi, L.; Gadea, A.; Latina, L.; Stefanini, A. M.; Szilner, S.; Trotta, M.; Vinodkumar, A. M.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Äystö, J.; Khlebnikov, S. V.; Rubchenya, V. A.; Trzaska, W. H.; Vakhtin, D. N.; Goverdovski, A. A.; Hanappe, F.; Materna, T.; Dorvaux, O.; Rowley, N.; Stuttge, L.; Giardina, G.

    2003-07-01

    The process of fusion-fission of heavy and superheavy nuclei with Z=82-122 formed in the reactions with 48Ca, 58Fe and 64Ni 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, Russia), the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy ) and the Accelerator of the Laboratory of University of Jyväskylä (JYFL, Finland) using the time-of-flight spectrometer of fission fragments CORSET[1] and the neutron multi-detector DEMON[2,3]. As a result of the experiments, mass and energy distributions (MED) of fission fragments, cross-sections of fission, quasi-fission and evaporation residues, multiplicities of neutrons and γ-quanta and their dependence on the mechanism of formation and decay of compound systems have been studied.

  12. Measurement of the energy and multiplicity distributions of neutrons from the photofission of 235U

    NASA Astrophysics Data System (ADS)

    Clarke, S. D.; Wieger, B. M.; Enqvist, A.; Vogt, R.; Randrup, J.; Haight, R. C.; Lee, H. Y.; Perdue, B. A.; Kwan, E.; Wu, C. Y.; Henderson, R. A.; Pozzi, S. A.

    2017-06-01

    For the first time, the complete neutron multiplicity distribution has been measured from the photofission of 235U induced by high-energy spallation γ rays arriving ahead of the neutron beam at the Los Alamos Neutron Science Center. The resulting average neutron multiplicity 3.80 ±0.08 (stat.) neutrons per photofission is in general agreement with previous measurements. In addition, unique measurements of the prompt fission energy spectrum of the neutrons from photofission and the angular correlation of two-neutron energies emitted in photofission also were made. The results are compared to calculations with the complete event fission model freya.

  13. Finite amplitude method applied to the giant dipole resonance in heavy rare-earth nuclei

    NASA Astrophysics Data System (ADS)

    Oishi, Tomohiro; Kortelainen, Markus; Hinohara, Nobuo

    2016-03-01

    Background: The quasiparticle random phase approximation (QRPA), within the framework of nuclear density functional theory (DFT), has been a standard tool to access the collective excitations of atomic nuclei. Recently, the finite amplitude method (FAM) was developed in order to perform the QRPA calculations efficiently without any truncation on the two-quasiparticle model space. Purpose: We discuss the nuclear giant dipole resonance (GDR) in heavy rare-earth isotopes, for which the conventional matrix diagonalization of the QRPA is numerically demanding. A role of the Thomas-Reiche-Kuhn (TRK) sum rule enhancement factor, connected to the isovector effective mass, is also investigated. Methods: The electric dipole photoabsorption cross section was calculated within a parallelized FAM-QRPA scheme. We employed the Skyrme energy density functional self-consistently in the DFT calculation for the ground states and FAM-QRPA calculation for the excitations. Results: The mean GDR frequency and width are mostly reproduced with the FAM-QRPA, when compared to experimental data, although some deficiency is observed with isotopes heavier than erbium. A role of the TRK enhancement factor in actual GDR strength is clearly shown: its increment leads to a shift of the GDR strength to higher-energy region, without a significant change in the transition amplitudes. Conclusions: The newly developed FAM-QRPA scheme shows remarkable efficiency, which enables one to perform systematic analysis of GDR for heavy rare-earth nuclei. The theoretical deficiency of the photoabsorption cross section could not be improved by only adjusting the TRK enhancement factor, suggesting the necessity of an approach beyond self-consistent QRPA and/or a more systematic optimization of the energy density functional (EDF) parameters.

  14. Tests of the fission-evaporation competition in the deexcitation of heavy nuclei

    SciTech Connect

    Siwek-Wilczynska, K.; Skwira, I.; Wilczynski, J.

    2005-09-01

    In order to verify methods of calculating the fission-evaporation competition in reactions used to synthesize new super-heavy nuclei in 'cold' (1n) and 'hot' (3n,4n) fusion reactions, we present an analysis of existing experimental data on the evaporation-residue cross sections in two selected reactions, {sup 208}Pb({sup 16}O, xn) and {sup 236}U({sup 12}C, xn), for which complementary experimental information necessary to unambiguously calculate the survival probabilities is available: precisely measured fusion excitation functions and saddle-point energies of the fissioning nuclei, deduced from experiments. Standard statistical model calculations, with shell effects accounted for by the Ignatyuk formula, were carried out assuming the ground state shell corrections of Moeller et al., and zero shell correction at the saddle configuration (resulting from the presented systematics). Good agreement of the calculated evaporation-residue cross sections with experimental data for different xn reaction channels at low excitation energies leaves no room for modifications of the conventional way of calculating the {gamma}{sub n}/{gamma}{sub f} ratio, particularly for including into this ratio an additional preexponential factor (such as the Kramers fission hindrance factor or an effective collective factor) significantly different from 1.

  15. Quarteting and spin-aligned proton-neutron pairs in heavy N =Z nuclei

    NASA Astrophysics Data System (ADS)

    Sambataro, M.; Sandulescu, N.

    2015-06-01

    We analyze the role of maximally aligned isoscalar pairs in heavy N =Z nuclei by employing a formalism of quartets. Quartets are superpositions of two neutrons and two protons coupled to total isospin T =0 and given J . The study is focused on the contribution of spin-aligned pairs carrying the angular momentum J =9 to the structure of 96Cd and 92Pd . We show that the role played by the J =9 pairs is quite sensitive to the model space and, in particular, it decreases considerably by passing from the simple 0 g9 /2 space to the more complete 1 p1 /2,1 p3 /2,0 f5 /2,0 g9 /2 space. In the latter case the description of these nuclei in terms of only spin-aligned J =9 pairs turns out to be unsatisfactory while an important contribution, particularly in the ground state, is seen to arise from isovector J =0 and isoscalar J =1 pairs. Thus, contrary to previous studies, we find no compelling evidence of a spin-aligned pairing phase in 92Pd .

  16. Direct stimulation of the retina by the method of virtual-quanta for heavy cosmic-ray nuclei

    NASA Technical Reports Server (NTRS)

    Mcnulty, P. J.; Madey, R.

    1972-01-01

    The contribution to the frequency of visual sensations induced in the dark-adapted eye by the virtual photon field was calculated, this field is associated with the heavy nuclei that exist in space beyond the geomagnetic field. In order to determine the probability that the virtual photon field induces a light flash, only the portion of the virtual photon spectrum that corresponds to the known frequency dependence of the sensitivity of human rods to visible light was utilized. The results can be expressed as a curve of the mean frequency of light flashes induced by the absorption of at least R virtual photons versus the threshold number R. The contribution to the light flash frequency from the virtual photon field of heavy cosmic ray nuclei is smaller than that from Cerenkov photons. The flux and energy spectra of galactic cosmic ray nuclei helium to iron were used.

  17. Calculation of primordial abundances of light nuclei including a heavy sterile neutrino

    SciTech Connect

    Mosquera, M.E.; Civitarese, O. E-mail: osvaldo.civitarese@fisica.unlp.edu.ar

    2015-08-01

    We include the coupling of a heavy sterile neutrino with active neutrinos in the calculation of primordial abundances of light-nuclei. We calculate neutrino distribution functions and primordial abundances, as functions depending on a renormalization of the sterile neutrino distribution function (a), the sterile neutrino mass (m{sub s}) and the mixing angle (φ). Using the observable data, we set constrains on these parameters, which have the values 0a < 0.4, sin{sup 2} φ ≈ 0.12−0.39 and 0m{sub s} < 7 keV at 1σ level, for a fixed value of the baryon to photon ratio. When the baryon to photon ratio is allowed to vary, its extracted value is in agreement with the values constrained by Planck observations and by the Wilkinson Microwave Anisotropy Probe (WMAP). It is found that the anomaly in the abundance of {sup 7}Li persists, in spite of the inclusion of a heavy sterile neutrino.

  18. Orbital deflection of fragments produced through peripheral reactions of heavy nuclei at 290 MeV/nucleon

    NASA Astrophysics Data System (ADS)

    Momota, S.; Kanazawa, M.; Kitagawa, A.; Sato, S.

    2017-02-01

    The orbital deflection phenomenon of reaction products formed through peripheral reactions of heavy nuclei at intermediate energy is studied to examine the contributions of the Coulomb potential and nuclear potential that act between the projectile and target nuclei. The angular distributions of fragments produced in 1-nucleon removal and exchange reactions of 40Ar and 84Kr beams with C, Al, Nb, Tb, and Au targets at 290 MeV/nucleon were observed. A significant deflection effect was successfully identified in observed angular distributions at energies as low as Ei = 100 MeV/nucleon. The deflection effect increases with the atomic number of the target nuclei. The observed deflection effect is consistently explainable using the classical deflection angle, which is obtained with respect to a simple framework of the Coulomb potential and the real part of the energy-dependent nuclear potential, and the characteristic impact parameter between the projectile and target nuclei.

  19. Physics of Unstable Nuclei

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

    . -- Asymmetric nuclear matter properties within the Brueckner theory / W. Zuo et al. -- Study of giant dipole resonance in continuum relativistic random phase approximation / D. Yang et al. -- Chiral bands for quasi-proton and quasi-neutron coupling with a triaxial rotor / B. Qi et al. -- Continuum properties of the Hartree-Fock mean field with finite-range interactions / H. S. Than et al. -- A study of pairing interaction in a separable form / Y. Tian et al. -- Microscopic study of the inelastic [symbol]+[symbol]C scattering / D. C. Cuong, D. T. Khoa -- Probing the high density behavior of the symmetry energy / F. Zhang et al. -- Microscopic calculations based on a Skyrme functional plus the pairing contribution / J. Li et al. -- In-medium cross sections in Dirac-Brueckner-Hartree-Fock approach / L. Peiyan et al. -- The effect of the tensor force on single-particle states and on the isotope shift / W. Zou et al. -- [symbol]Ne excited states two-proton decay / M. De Napoli et al. -- The isomeric ratio and angular momentum of fragment [symbol]Xe in photofission of heavy nuclei / T. D. Thiep et al. -- Search for correlated two-nucleon systems in [symbol]Li and [symbol]He nuclei via one-nucleon exchange reaction / N. T. Khai et al. -- Summary talk of ISPUN07 / N. Alamanos.

  20. Parameterization of deformed nuclei for Glauber modeling in relativistic heavy ion collisions

    DOE PAGES

    Sorensen, P.; Tang, A. H.; Videbaek, F.; ...

    2015-08-04

    In this study, the density distributions of large nuclei are typically modeled with a Woods–Saxon distribution characterized by a radius R0 and skin depth a. Deformation parameters β are then introduced to describe non-spherical nuclei using an expansion in spherical harmonics R0(1+β2Y20+β4Y40). But when a nucleus is non-spherical, the R0 and a inferred from electron scattering experiments that integrate over all nuclear orientations cannot be used directly as the parameters in the Woods–Saxon distribution. In addition, the β2 values typically derived from the reduced electric quadrupole transition probability B(E2)↑ are not directly related to the β2 values used in themore » spherical harmonic expansion. B(E2)↑ is more accurately related to the intrinsic quadrupole moment Q0 than to β2. One can however calculate Q0 for a given β2 and then derive B(E2)↑ from Q0. In this paper we calculate and tabulate the R0, a , and β2 values that when used in a Woods–Saxon distribution, will give results consistent with electron scattering data. We then present calculations of the second and third harmonic participant eccentricity (ε2 and ε3) with the new and old parameters. We demonstrate that ε3 is particularly sensitive to a and argue that using the incorrect value of a has important implications for the extraction of viscosity to entropy ratio (η/s) from the QGP created in Heavy Ion collisions.« less

  1. Unique first-forbidden β-decay transitions in odd-odd and even-even heavy nuclei

    NASA Astrophysics Data System (ADS)

    Nabi, Jameel-Un; Çakmak, Necla; Majid, Muhammad; Selam, Cevad

    2017-01-01

    The allowed Gamow-Teller (GT) transitions are the most common weak nuclear processes of spin-isospin (στ) type. These transitions play a key role in numerous processes in the domain of nuclear physics. Equally important is their contribution in astrophysics, particularly in nuclear synthesis and supernova-explosions. In situations where allowed GT transitions are not favored, first-forbidden transitions become significant, specifically in medium heavy and heavy nuclei. For neutron-rich nuclei, first-forbidden transitions are favored mainly due to the phase-space amplification for these transitions. In this work we calculate the allowed GT as well as unique first-forbidden (U1F) | ΔJ | = 2 transitions strength in odd-odd and even-even nuclei in mass range 70 ≤ A ≤ 214. Two different pn-QRPA models were used with a schematic separable interaction to calculate GT and U1F transitions. The inclusion of U1F strength improved the overall comparison of calculated terrestrial β-decay half-lives in both models. The ft values and reduced transition probabilities for the 2- ⟷0+ transitions were also calculated. We compared our calculations with the previously reported correlated RPA calculation and experimental results. Our calculations are in better agreement with measured data. For stellar applications we further calculated the allowed GT and U1F weak rates. These include β±-decay rates and electron/positron capture rates of heavy nuclei in stellar matter. Our study shows that positron and electron capture rates command the total weak rates of these heavy nuclei at high stellar temperatures.

  2. Density functional theory computation of Nuclear Magnetic Resonance parameters in light and heavy nuclei

    NASA Astrophysics Data System (ADS)

    Sutter, Kiplangat

    This thesis illustrates the utilization of Density functional theory (DFT) in calculations of gas and solution phase Nuclear Magnetic Resonance (NMR) properties of light and heavy nuclei. Computing NMR properties is still a challenge and there are many unknown factors that are still being explored. For instance, influence of hydrogen-bonding; thermal motion; vibration; rotation and solvent effects. In one of the theoretical studies of 195Pt NMR chemical shift in cisplatin and its derivatives illustrated in Chapter 2 and 3 of this thesis. The importance of representing explicit solvent molecules explicitly around the Pt center in cisplatin complexes was outlined. In the same complexes, solvent effect contributed about half of the J(Pt-N) coupling constant. Indicating the significance of considering the surrounding solvent molecules in elucidating the NMR measurements of cisplatin binding to DNA. In chapter 4, we explore the Spin-Orbit (SO) effects on the 29Si and 13C chemical shifts induced by surrounding metal and ligands. The unusual Ni, Pd, Pt trends in SO effects to the 29Si in metallasilatrane complexes X-Si-(mu-mt)4-M-Y was interpreted based on electronic and relativistic effects rather than by structural differences between the complexes. In addition, we develop a non-linear model for predicting NMR SO effects in a series of organics bonded to heavy nuclei halides. In chapter 5, we extend the idea of "Chemist's orbitals" LMO analysis to the quantum chemical proton NMR computation of systems with internal resonance-assisted hydrogen bonds. Consequently, we explicitly link the relationship between the NMR parameters related to H-bonded systems and intuitive picture of a chemical bond from quantum calculations. The analysis shows how NMR signatures characteristic of H-bond can be explained by local bonding and electron delocalization concepts. One shortcoming of some of the anti-cancer agents like cisplatin is that they are toxic and researchers are looking for

  3. Ground states of medium-heavy doubly-closed-shell nuclei in correlated-basis function theory

    NASA Astrophysics Data System (ADS)

    Bisconti, C.; Saavedra, F. Arias De; Co', G.; Fabrocini, A.

    2006-05-01

    The correlated-basis function theory is applied to the study of medium-heavy doubly-closed-shell nuclei with different wave functions for protons and neutrons and in the jj coupling scheme. State-dependent correlations including tensor correlations are used. Realistic two-body interactions of Argonne and Urbana type, together with three-body interactions, have been used to calculate ground-state energies and density distributions of the C12, O16, Ca40, Ca48, and Pb208 nuclei.

  4. The shell model Monte Carlo approach to level densities: from medium-mass to heavy deformed nuclei

    SciTech Connect

    Alhassid, Y.

    2008-04-17

    The shell model Monte Carlo (SMMC) approach is a powerful state-of-the-art method for the microscopic calculation of level densities in the presence of correlations. With this method it is possible to perform realistic calculations in model spaces that are many orders of magnitude larger than spaces that can be treated with conventional diagonalization methods. SMMC level densities of medium-mass nuclei were found to be in remarkably good agreement with experimental level densities without any adjustable parameters. We discuss recent developments, including a spin projection method for calculating the spin distribution of level densities and the extension of SMMC to heavy deformed nuclei.

  5. Use of relativistic rise in ionization chambers for measurement of high energy heavy nuclei

    NASA Technical Reports Server (NTRS)

    Barthelmy, S. D.; Israel, M. H.; Klarmann, J.; Vogel, J. S.

    1983-01-01

    A balloon-borne instrument has been constructed to measure the energy spectra of cosmic-ray heavy nuclei in the range of about 0.3 to about 100 GeV/amu. It makes use of the relativistic rise portion of the Bethe-Bloch curve in ionization chambers for energy determination in the 10- to 100-GeV/amu interval. The instrument consists of six layers of dual-gap ionization chambers for energy determination above 10 GeV/amu. Charge is determined with a NE114 scintillator and a Pilot 425 plastic Cerenkov counter. A CO2 gas Cerenkov detector (1 atm; threshold of 30 GeV/amu) calibrates the ion chambers in the relativistic rise region. The main emphasis of the instrument is the determination of the change of the ratio of Iron (26) to the Iron secondaries (21-25) in the energy range of 10 to 100 GeV/amu. Preliminary data from a balloon flight in the fall of 1982 from Palestine, TX is presented.

  6. Folding Model Analysis of Elastic Scattering of 11B from Light, Medium, and Heavy Nuclei

    NASA Astrophysics Data System (ADS)

    Aygun, M.

    2016-11-01

    The elastic scattering angular distributions of 11B projectile on light, medium, and heavy target nuclei including 7Li, 9Be, 12C, 16O, 24,25,26Mg, 27Al, 28Si, 40Ca, 58Ni, 59Co, 60Ni, 197Au, 208Pb, and 209Bi have been analyzed at various incident energies. The theoretical results have been obtained by using two different nuclear potentials within the framework of the optical model (OM). Firstly, the double folding potential for real part and the Wood—Saxon (WS) potential for imaginary part have been applied. Secondly, the calculations with double folding potential for both real and imaginary part have been performed and compared with the experimental data. It has been seen that the results are in very good agreement with the experimental data. Also, the volume integrals and cross-sections for each reaction have been obtained. Finally, a new and simple formula for the imaginary potential depth has been derived to clarify the nuclear interactions of 11B nucleus at low energy reactions.

  7. No chance for synthesis of super-heavy nuclei in fusion of symmetric systems

    NASA Astrophysics Data System (ADS)

    Cap, T.; Siwek-Wilczyńska, K.; Wilczyński, J.

    2014-09-01

    Predictions of relatively large cross sections (of about 1 picobarn) for synthesis of super heavy nuclei of Z=122 and Z=124 in cold fusion (1n) reactions of symmetric 154Sm + 150Nd and 154Sm + 154Sm systems by R.K. Choudhury and Y.K. Gupta (2014) [1] are examined. The authors state that this result had been obtained by using the fusion-by-diffusion (FBD) model. As predictions of the original FBD model of Swiatecki, Cap, Siwek-Wilczyńska and Wilczyński had been definitely pessimistic regarding fusion of more symmetric systems (in comparison with equivalent asymmetric systems), we feel compelled to present excitation functions of the 154Sm(150Nd, 1n)303122 and 154Sm(154Sm, 1n)307124 reactions, calculated within the original fusion-by-diffusion model. In accordance with our earlier predictions of a general trend of fusion hindrance for near-symmetric systems, the cross sections for synthesis of 303122 and 307124 nuclides in fusion of these two symmetric systems are found to be extremely small and probably never reachable: about 10-11 pb and 10-13 pb, respectively. It is shown that Choudhury and Gupta obtained their results (overestimating the cross sections by 11 and 13 orders of magnitude) as an effect of an arbitrary and physically unjustified interference in the FBD model.

  8. Use of relativistic rise in ionization chambers for measurement of high energy heavy nuclei

    NASA Technical Reports Server (NTRS)

    Barthelmy, S. D.; Israel, M. H.; Klarmann, J.; Vogel, J. S.

    1983-01-01

    A balloon-borne instrument has been constructed to measure the energy spectra of cosmic-ray heavy nuclei in the range of about 0.3 to about 100 GeV/amu. It makes use of the relativistic rise portion of the Bethe-Bloch curve in ionization chambers for energy determination in the 10- to 100-GeV/amu interval. The instrument consists of six layers of dual-gap ionization chambers for energy determination above 10 GeV/amu. Charge is determined with a NE114 scintillator and a Pilot 425 plastic Cerenkov counter. A CO2 gas Cerenkov detector (1 atm; threshold of 30 GeV/amu) calibrates the ion chambers in the relativistic rise region. The main emphasis of the instrument is the determination of the change of the ratio of Iron (26) to the Iron secondaries (21-25) in the energy range of 10 to 100 GeV/amu. Preliminary data from a balloon flight in the fall of 1982 from Palestine, TX is presented.

  9. Increased delivery of condensation nuclei during the Late Heavy Bombardment to the terrestrial and martian atmospheres

    NASA Astrophysics Data System (ADS)

    Losiak, Anna

    2014-05-01

    During the period of the Late Heavy Bombardment (LHB), between 4.1 and 3.8 Ga, the impact rate within the entire Solar System was up to a few thousand times higher than the current value (Ryder 2002, Bottke et al. 2012, Fassett and Minton 2013). Multiple basin-forming events on inner planets that occurred during this time had a strong but short-lasting (up to few thousands of years) effect on atmospheres of Earth and Mars (Sleep et al. 1989, Segura et al. 2002, 2012). However, the role of the continuous flux of smaller impactors has not been assessed so far. We calculated the amount of meteoric material in the 10^-3 kg to 106 kg size range delivered to Earth and Mars during the LHB based on the impact flux at the top of the Earth's atmosphere based on results from Bland and Artemieva (2006). Those values were recalculated for Mars based on Ivanov and Hartmann (2009) and then recalculated to the LHB peak based on estimates from Ryder (2002), Bottke et al. (2012), Fassett and Minton (2013). During the LHB, the amount of meteoritic material within this size range delivered to Earth was up to ~1.7*10^10 kg/year and 1.4*10^10 kg/year for Mars. The impactors that ablate and are disrupted during atmospheric entry can serve as cloud condensation nuclei (Rosen 1968, Hunten et al. 1980, Ogurtsov and Raspopov 2011). The amount of material delivered during LHB to the upper stratosphere and lower mezosphere (Hunten et al. 1980, Bland and Artemieva 2006) is comparable to the current terrestrial annual emission of mineral cloud condensation nuclei of 0.5-8*10^12 kg/year (Tegen 2003). On Mars, the availability of condensation nuclei is one of the main factors guiding water-ice cloud formation (Montmessin et al. 2004), which is in turn one of the main climatic factors influencing the hydrological cycle (Michaels et al. 2006) and radiative balance of the planet (Haberle et al. 1999, Wordsworth et al. 2013, Urata and Toon 2013). Increased delivery of condensation nuclei during the

  10. Isomeric states observed in heavy neutron-rich nuclei populated in the fragmentation of a 208Pb beam

    NASA Astrophysics Data System (ADS)

    Steer, S. J.; Podolyák, Zs.; Pietri, S.; Górska, M.; Grawe, H.; Maier, K. H.; Regan, P. H.; Rudolph, D.; Garnsworthy, A. B.; Hoischen, R.; Gerl, J.; Wollersheim, H. J.; Becker, F.; Bednarczyk, P.; Cáceres, L.; Doornenbal, P.; Geissel, H.; Grębosz, J.; Kelic, A.; Kojouharov, I.; Kurz, N.; Montes, F.; Prokopwicz, W.; Saito, T.; Schaffner, H.; Tashenov, S.; Heinz, A.; Pfützner, M.; Kurtukian-Nieto, T.; Benzoni, G.; Jungclaus, A.; Balabanski, D. L.; Bowry, M.; Brandau, C.; Brown, A.; Bruce, A. M.; Catford, W. N.; Cullen, I. J.; Dombrádi, Zs.; Estevez, M. E.; Gelletly, W.; Ilie, G.; Jolie, J.; Jones, G. A.; Kmiecik, M.; Kondev, F. G.; Krücken, R.; Lalkovski, S.; Liu, Z.; Maj, A.; Myalski, S.; Schwertel, S.; Shizuma, T.; Walker, P. M.; Werner-Malento, E.; Wieland, O.

    2011-10-01

    Heavy neutron-rich nuclei were populated via the fragmentation of a E/A=1 GeV 20882Pb beam. Secondary fragments were separated and identified and subsequently implanted in a passive stopper. By the detection of delayed γ rays, isomeric decays associated with these nuclei have been identified. A total of 49 isomers were detected, with the majority of them observed for the first time. The newly discovered isomers are in 204,20580Hg, 201,202,204,20579Au, 197,203,20478Pt, 195,199-20377Ir, 193,197-19976Os, 19675Re, 190,19174W, and 18973Ta. Possible level schemes are constructed and the structure of the nuclei discussed. To aid the interpretation, shell-model as well as BCS calculations were performed.

  11. Search for magnetic dipole strength and giant spin-flip resonances in heavy nuclei. [120 to 200 MeV

    SciTech Connect

    Horen, D J

    1980-01-01

    A description is given of the use of high-resolution (n,n) scattering and the (p,n) reaction as tools to investigate highly excited states, with emphasis on information pertaining to magnetic dipole strength and giant spin-flip resonances in heavy nuclei. It is shown how the ability to determine uniquely the spins and parities of resonances observed in neutron scattering has been instrumental to an understanding of the distribution of M1 strength in /sup 207/ /sup 208/Pb. Some recent results of (p,n) studies with intermediate energy protons are discussed. Energy systematics of the giant Gamow-Teller (GT) resonance as well as new ..delta..l = ..delta..S = 1 resonance with J/sup ..pi../ = (1,2)/sup -/ are presented. It is shown how the (p,n) reaction might be useful in locating M1 strength in heavy nuclei. 20 figures.

  12. Setup with Laser Ionization in Gas Cell for Production and Study of Neutron-Rich Heavy Nuclei

    NASA Astrophysics Data System (ADS)

    Zagrebaev, V. I.; Zemlyanoy, S. G.; Kozulin, E. M.; Kudryavtsev, Yu.; Fedosseev, V.; Bark, R.; Janas, Z.; Othman, H. A.

    2015-11-01

    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 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.

  13. Heavy quarks and nuclei, or the charm & beauty of nuclear physics

    SciTech Connect

    Kharzeev, D.

    1997-09-22

    This report contains viewgraphs on the following: why heavy quarks? Heavy quarkonium in QCD vacuum and in matter; Phenomenology of quarkonium production; Induced decay of QCD vacuum in heavy ion collisions? Implications for quarkonium production; and Outlook.

  14. Spontaneous fission half-lives of heavy nuclei in ground state and in isomeric state

    NASA Astrophysics Data System (ADS)

    Ren, Zhongzhou; Xu, Chang

    2005-09-01

    We generalize the formulas of spontaneous fission half-lives of even-even nuclei in their ground state to both the case of odd nuclei and the case of fission isomers [Phys. Rev. C 71 (2005) 014309]. The spontaneous fission half-lives of odd- A nuclei and of odd-odd nuclei in the ground state are calculated by Swiatecki's formula, by its generalized form, and by a new formula where the blocking effect of unpaired nucleon on the half-lives has been taken into account with different mechanisms. By introducing a blocking factor or a generalized seniority in the formulas of the half-lives of even-even nuclei, we can reasonably reproduce the experimental fission half-lives of odd- A nuclei and of odd-odd nuclei with the same parameters used in ground state of even-even nuclei. For spontaneous fission of the isomers in transuranium nuclei the new formula can be simplified into a three-parameter formula and the isomeric half-lives can be well reproduced by the formula. The new formula of the isomeric half-lives is as good as Metag's formula of fission isomers. The half-lives of isomers from these formulas are very accurate and therefore these formulas can give reliable predictions for half-lives of new isomers of neighboring nuclei.

  15. Alpha-cluster preformation factor within cluster-formation model for odd-A and odd-odd heavy nuclei

    NASA Astrophysics Data System (ADS)

    Saleh Ahmed, Saad M.

    2017-06-01

    The alpha-cluster probability that represents the preformation of alpha particle in alpha-decay nuclei was determined for high-intensity alpha-decay mode odd-A and odd-odd heavy nuclei, 82 < Z < 114, 111 < N < 174. This probability was calculated using the energy-dependent formula derived from the formulation of clusterisation states representation (CSR) and the hypothesised cluster-formation model (CFM) as in our previous work. Our previous successful determination of phenomenological values of alpha-cluster preformation factors for even-even nuclei motivated us to expand the work to cover other types of nuclei. The formation energy of interior alpha cluster needed to be derived for the different nuclear systems with considering the unpaired-nucleon effect. The results showed the phenomenological value of alpha preformation probability and reflected the unpaired nucleon effect and the magic and sub-magic effects in nuclei. These results and their analyses presented are very useful for future work concerning the calculation of the alpha decay constants and the progress of its theory.

  16. Photofission product yields of 238U and 239Pu with 22-MeV bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Wen, Xianfei; Yang, Haori

    2016-06-01

    In homeland security and nuclear safeguards applications, non-destructive techniques to identify and quantify special nuclear materials are in great demand. Although nuclear materials naturally emit characteristic radiation (e.g. neutrons, γ-rays), their intensity and energy are normally low. Furthermore, such radiation could be intentionally shielded with ease or buried in high-level background. Active interrogation techniques based on photofission have been identified as effective assay approaches to address this issue. In designing such assay systems, nuclear data, like photofission product yields, plays a crucial role. Although fission yields for neutron-induced reactions have been well studied and readily available in various nuclear databases, data on photofission product yields is rather scarce. This poses a great challenge to the application of photofission techniques. In this work, short-lived high-energy delayed γ-rays from photofission of 238U were measured in between linac pulses. In addition, a list-mode system was developed to measure relatively long-lived delayed γ-rays from photofission of 238U and 239Pu after the irradiation. Time and energy information of each γ-ray event were simultaneously recorded by this system. Cumulative photofission product yields were then determined using the measured delayed γ-ray spectra.

  17. Enhanced Photofission-based, Coincidence/Multiplicity Inspection Measurements

    SciTech Connect

    J.L. Jones; D.R. Norman; K.J. Haskell; M.T. Swinhoe; S.J. Tobin; W.H. Geist; R.B. Rothrock; C.R. Freeman

    2010-07-01

    An enhanced active interrogation system has been developed that integrates a transportable Idaho National Laboratory (INL) photonuclear inspection system, using a pulsed bremsstrahlung source and a reconfigurable neutron detection system, with a Los Alamos National Laboratory (LANL) list-mode data acquisition system. A series of active interrogation experiments have shown enhanced nuclear material detection and identification utilizing pulsed photofission-induced, neutron coincidence/multiplicity counting between pulses of an up-to-10-MeV electron accelerator. This paper describes the integrated inspection system and presents some key shielded and unshielded nuclear material inspection results. The enhanced inspection methodology has applicability to homeland security and possible nuclear weapon dismantlement treaties.

  18. Cryogenic stopping cell for photofission fragments at the ELI-NP facility

    NASA Astrophysics Data System (ADS)

    Constantin, P.; Balabanski, D. L.; Cuong, P. V.

    2015-10-01

    The brilliant gamma beam at the future Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility will be used to generate a beam of exotic neutron-rich isotopes via photofission of actinide targets. We present simulations with the Geant4 toolkit of the photofission process for the design and optimization of the expected performance parameters of the Cryogenic Stopping Cell (CSC). The CSC will be used to extract the photofission fragments into the secondary beam of about 106 ions/s. We propose an experimental program to study refractory neutron-rich isotopes.

  19. Cryogenic stopping cell for photofission fragments at the ELI-NP facility

    SciTech Connect

    Constantin, P. Balabanski, D. L.; Cuong, P. V.

    2015-10-15

    The brilliant gamma beam at the future Extreme Light Infrastructure - Nuclear Physics (ELI-NP) facility will be used to generate a beam of exotic neutron-rich isotopes via photofission of actinide targets. We present simulations with the Geant4 toolkit of the photofission process for the design and optimization of the expected performance parameters of the Cryogenic Stopping Cell (CSC). The CSC will be used to extract the photofission fragments into the secondary beam of about 10{sup 6} ions/s. We propose an experimental program to study refractory neutron-rich isotopes.

  20. Production of heavy and superheavy neutron-rich nuclei in neutron capture processes

    NASA Astrophysics Data System (ADS)

    Zagrebaev, V. I.; Karpov, A. V.; Mishustin, I. N.; Greiner, Walter

    2011-10-01

    The neutron capture process is considered as an alternative method for production of superheavy (SH) nuclei. Strong neutron fluxes might be provided by nuclear reactors and nuclear explosions in the laboratory frame and by supernova explosions in nature. All these cases are discussed in the paper. There are two gaps of short-lived nuclei (one is the well-known fermium gap and the other one is located in the region of Z=106-108 and N˜170) which impede the formation of SH nuclei by rather weak neutron fluxes realized at available nuclear reactors. We find that in the course of multiple (rather “soft”) nuclear explosions these gaps may be easily bypassed, and thus, a measurable amount of the neutron-rich long-living SH nuclei located at the island of stability may be synthesized. Existing pulsed reactors do not allow one to bypass these gaps. We formulate requirements for the pulsed reactors of the next generation that could be used for production of long-living SH nuclei. Natural formation of SH nuclei (in supernova explosions) is also discussed. The yield of SH nuclei relative to lead is estimated to be about 10-12, which is not beyond the experimental sensitivity for a search of SH elements in cosmic rays.

  1. Isotopic dependence of the cross section for the induced fission of heavy nuclei

    SciTech Connect

    Bolgova, O. N.; Adamian, G. G.; Antonenko, N. V.; Zubov, A. S.; Ivanova, S. P.; Scheid, W.

    2009-06-15

    The cross sections for the induced fission of {sup 211-223}Ra, {sup 203-211}Rn, and {sup 221-231}Th nuclei undergoing peripheral collisions with {sup 208}Pb nuclei are calculated on the basis of the statistical model. The role of the N = 126 neutron shell is studied. The level density in excited nuclei is determined within the Fermi gas model and a model that takes into account the collective enhancement of the level density. The inclusion of a particle-hole excitation in addition to a collective Coulomb excitation makes it possible to obtain a satisfactory description of experimental cross sections for the fission of radium isotopes. The calculated ratios of the cross sections for the induced fission of {sup 236}U ({sup 237}U) and {sup 238}U ({sup 239}U) nuclei agree with experimental data.

  2. Analytic view at alpha clustering in even-even heavy nuclei near magic numbers 82 and 126

    NASA Astrophysics Data System (ADS)

    Ahmed, Saad M. Saleh; Yahaya, Redzuwan; Radiman, Shahidan; Yasir, Muhamad Samudi; Kassim, Hasan Abu; Khandaker, Mayeen Uddin

    2015-02-01

    Most studies on the determination of the alpha-decay preformation factor have used decay formulae. The preformation factor is known to contain abundant information on the nuclear structure. The successful determination of the preformation factor through the cluster formation model (CFM) motivates this study to determine the factor for nuclei near the magic numbers and present results in an analytic study based on different comparisons and observations. The difference between preformation factors obtained from CFM and from the decay formula method is significant. The formula method is used for the entire process of alpha decay as a transition between two states, whereas CFM is applied for the initial state of alpha formation. The preformation factor obtained using CFM and clusterization state representation was first compared with that obtained from the decay formula. Results were used to investigate alpha formation in even-even heavy nuclei, including 72 < Z < 92 and 92 < N < 142, near the magic numbers Z = 82 and N = 126. The values of the preformation factor were discussed and explained in detail according to the clusterization state representation to describe the most possible states of ground-state nuclei. The alpha clustering described through CFM is found to be consistent with that described using the decay formula for the open-shell nuclei of N < 126. The presence of more nucleons in the open-shell nuclei results in lower probability for alpha clustering and lower value of the preformation factor. However, few nucleons beyond the closed shell can cause higher probability for alpha clustering and larger value of the preformation factor. The maximum and minimum of the alpha-cluster formation occur in the nucleus of the double-shell closure (with N = 126 and Z = 82 and in the nucleus of two protons and two neutrons more. This formation probability is sensitive to the subshells, leading to the possibility of more clusterization states, including core

  3. Investigation of the energy-averaged double transition density of isoscalar monopole excitations in medium-heavy mass spherical nuclei

    NASA Astrophysics Data System (ADS)

    Gorelik, M. L.; Shlomo, S.; Tulupov, B. A.; Urin, M. H.

    2016-11-01

    The particle-hole dispersive optical model, developed recently, is applied to study properties of high-energy isoscalar monopole excitations in medium-heavy mass spherical nuclei. The energy-averaged strength functions of the isoscalar giant monopole resonance and its overtone in 208Pb are analyzed. In particular, we analyze the energy-averaged isoscalar monopole double transition density, the key quantity in the description of the hadron-nucleus inelastic scattering, and studied the validity of the factorization approximation using semi classical and microscopic one body transition densities, respectively, in calculating the cross sections for the excitation of isoscalar giant resonances by inelastic alpha scattering.

  4. Mean-field studies of time reversal breaking states in super-heavy nuclei with the Gogny force

    SciTech Connect

    Robledo, L. M.

    2015-10-15

    Recent progress on the description of time reversal breaking (odd mass and multi-quasiparticle excitation) states in super-heavy nuclei within a mean field framework and using several flavors of the Gogny interaction is reported. The study includes ground and excited states in selected odd mass isotopes of nobelium and mendelevium as well as high K isomeric states in {sup 254}No. These are two and four-quasiparticle excitations that are treated in the same self-consistent HFB plus blocking framework as the odd mass states.

  5. Mean-field studies of time reversal breaking states in super-heavy nuclei with the Gogny force

    NASA Astrophysics Data System (ADS)

    Robledo, L. M.

    2015-10-01

    Recent progress on the description of time reversal breaking (odd mass and multi-quasiparticle excitation) states in super-heavy nuclei within a mean field framework and using several flavors of the Gogny interaction is reported. The study includes ground and excited states in selected odd mass isotopes of nobelium and mendelevium as well as high K isomeric states in 254No. These are two and four-quasiparticle excitations that are treated in the same self-consistent HFB plus blocking framework as the odd mass states.

  6. Photofission Analysis for Fissile Dosimeters Dedicated to Reactor Pressure Vessel Surveillance

    NASA Astrophysics Data System (ADS)

    Bourganel, Stéphane; Faucher, Margaux; Thiollay, Nicolas

    2016-02-01

    Fissile dosimeters are commonly used in reactor pressure vessel surveillance programs. In this paper, the photofission contribution is analyzed for in-vessel 237Np and 238U fissile dosimeters in French PWR. The aim is to reassess this contribution using recent tools (the TRIPOLI-4 Monte Carlo code) and latest nuclear data (JEFF3.1.1 and ENDF/B-VII nuclear libraries). To be as exhaustive as possible, this study is carried out for different configurations of fissile dosimeters, irradiated inside different kinds of PWR: 900 MWe, 1300 MWe, and 1450 MWe. Calculation of photofission rate in dosimeters does not present a major problem using the TRIPOLI-4® Monte Carlo code and the coupled neutron-photon simulation mode. However, preliminary studies were necessary to identify the origin of photons responsible of photofissions in dosimeters in relation to the photofission threshold reaction (around 5 MeV). It appears that the main contribution of high enough energy photons generating photofissions is the neutron inelastic scattering in stainless steel reactor structures. By contrast, 137Cs activity calculation is not an easy task since photofission yield data are known with high uncertainty.

  7. The charge spectrum of heavy cosmic ray nuclei measured in the Biostack experiment aboard Apollo 16 using plastic detectors.

    PubMed

    Enge, W; Beaujean, R; Bartholoma, K P; Fukui, K

    1974-01-01

    In the Biostack experiment flown aboard Apollo 16 plastic detectors were used to select those individual biological objects which were hit by single heavy cosmic-ray nuclei during the 266 hours of space flight. The energy loss deposited in the biological object can be determined. This method needs a separate calibration in every experiment, i.e. an individual track etching rate as function of the energy loss. This calibration is given. An area of 36 cm2 of eight cellulose nitrate sheets was scanned for tracks of heavy cosmic-ray particles that stopped in the sheets. About 200 particles could be evaluated. Calibration was achieved using the oxygen isotope 16O of the cosmic-ray ions and the charge spectrum of all measured particles (Z=5-16) could be obtained.

  8. The Use of the Photofission of 238U for a Neutron-Rich Radioactive Ion Beams Generation

    NASA Astrophysics Data System (ADS)

    Szöllős, O.; Kliman, J.

    2003-10-01

    The fission fragments yield for photofission of 238U, induced by bremsstrahlung photons with endpoint energies of 25 and 50MeV was evaluated to estimate the possibility of producing the neutron-rich nuclei. The systematics coming from A.C. Wahl's Zp model 1 for charge distribution of fission fragments were used. Results for xenon and krypton isotopes are compared with experimental data 2 obtained on the DRIBs 3 (Dubna Radioactive Ion Beams) facility for neutron-rich nuclei production in Flerov Laboratory. The fission rate and fission density in production target for metallic uranium and UCx compounds were simulated with Geant4 4 simulation toolkit to design the target geometry, The fission rate dependence on material of the electron stopping target was examined, At nominal beam values on microtron MT-25 (Ie = 20μA, Ee = 25MeV) up to 2.1011 fissions/s could be achieved. Then the production rate of neutron-rich isotopes reaching order of 109s-1. The induced activity in the production target depending on an irradiation time was calculated for radiation protection purposes and target safety estimation. The cumulation of actinide nuclei was also calculated.

  9. Nuclear Structure Investigations Of Heavy Nuclei And The Decay Of SHE

    SciTech Connect

    Kuusiniemi, P.

    2005-04-05

    Within the framework of our studies of proton rich nuclei around the N 126 and N = 152 neutron shells we have performed a series of {alpha}-{gamma}-coincidence studies. The nuclei of interest were separated in-flight by the velocity filter SHIP and implanted into a position sensitive 16-strip PIPS-detector where their arrival and subsequent {alpha}-decays were registered. Associated {gamma}-rays were detected by a Ge-Clover-detector. In the present work recent results concerning 216Th and {alpha}-decay chains of 251No and 257Db are given together with brief discussion.

  10. Debye Layer Confinement of Nucleons in Nuclei for Heavy Nuclear Synthesis

    SciTech Connect

    Ghahramany, N.; Ghanaatian, M.

    2008-04-21

    Following the laser ablation studies leading to a theory of nuclei confinement by a Debye layer mechanism, we present here numerical evaluations for the known stable nuclei where the Coulomb repulsion is included as a rather minor component especially for lager nuclei. It is noticed that the well known empirical nuclear density of 2x10{sup 38} cm{sup -3} follows for a nucleon number A<60 for iron. The crucial change of the Fermi energy into the relativistic branch for the nucleons results for a density at 3x10{sup 39} cm{sup -3} which density corresponds to the Debye layer equilibrium near uranium above which the Fermi energy will not permit any nucleation. It is speculated whether the range between both densities at the big bang expansion at temperatures of few 100 keV and at 200 seconds after the big bang is resulting in a nuclear-chemical Boltzmann equilibrium for the generation of the endothermic nuclear generation. The question is then open, what additional nuclear expansion forces are acting in the elements between uranium and iron during this equilibrium reactions in nuclei such that the empirical nuclear density is produced.

  11. Allowance for the orientation of colliding ions in describing the synthesis of heavy nuclei

    SciTech Connect

    Litnevsky, V. L.; Kosenko, G. I.; Ivanyuk, F. A.; Pashkevich, V. V.

    2012-12-15

    The dynamical model proposed earlier for describing fusion-fission reactions was modified in order to take into account an arbitrary orientation of colliding ions. In this model, the evolution of collective coordinates of the system under study is treated as a two-stage process. The motion of the projectile nucleus toward the target nucleus is considered at the first stage, and the evolution of a continuous dinuclear system formed as soon as the projectile and target nuclei touch each other is calculated at the second stage. At either stage of the calculation, the dynamical evolution of the system is described in terms of Langevin equations. The shell structure of the nuclei involved is taken into account at both stages. The difference between the results obtained for the first stage with allowance for an arbitrary orientation of colliding ions and the respective results for the case where their symmetry axes are aligned are discussed. The cross sections for the touching of primary nuclei and for their fusion are calculated, along with the cross sections for evaporation-residue formation in reactions involving nuclei that are prolate and spherical in the ground state. The results are compared with available theoretical and experimental data.

  12. Allowance for the orientation of colliding ions in describing the synthesis of heavy nuclei

    NASA Astrophysics Data System (ADS)

    Litnevsky, V. L.; Kosenko, G. I.; Ivanyuk, F. A.; Pashkevich, V. V.

    2012-12-01

    The dynamical model proposed earlier for describing fusion-fission reactions was modified in order to take into account an arbitrary orientation of colliding ions. In this model, the evolution of collective coordinates of the system under study is treated as a two-stage process. The motion of the projectile nucleus toward the target nucleus is considered at the first stage, and the evolution of a continuous dinuclear system formed as soon as the projectile and target nuclei touch each other is calculated at the second stage. At either stage of the calculation, the dynamical evolution of the system is described in terms of Langevin equations. The shell structure of the nuclei involved is taken into account at both stages. The difference between the results obtained for the first stage with allowance for an arbitrary orientation of colliding ions and the respective results for the case where their symmetry axes are aligned are discussed. The cross sections for the touching of primary nuclei and for their fusion are calculated, along with the cross sections for evaporation-residue formation in reactions involving nuclei that are prolate and spherical in the ground state. The results are compared with available theoretical and experimental data.

  13. Spectroscopic factors and cluster decay half-lives of heavy nuclei

    SciTech Connect

    Kuklin, S.N.; Adamian, G.G.; Antonenko, N.V.

    2005-01-01

    The cluster radioactivity is treated under the assumption that the light clusters are produced by a collective motion of the nuclear system in the charge asymmetry coordinate with further penetration through the Coulomb barrier. The known experimental data on cluster radioactivity are described. The half-lives of cluster emission of neutron-deficient actinides and medium-mass nuclei are predicted.

  14. An algebraic fermion description of band termination and loss of collectivity in heavy nuclei

    NASA Astrophysics Data System (ADS)

    Guidry, Mike W.; Wu, Cheng-Li; Li, Zhen-Ping; Feng, Da Hsuan; Ginocchio, Joseph N.

    1987-03-01

    An algebraic fermion model is used to interpret the loss of E2 collectivity observed in two- and four-quasiparticle aligned bands, and the termination of collective bands at high spins in rare-earth nuclei. Both can be understood as a systematic consequence of finite angular momentum content in a coherent SU 3 core.

  15. Electron-positron pairs in physics and astrophysics: From heavy nuclei to black holes

    NASA Astrophysics Data System (ADS)

    Ruffini, Remo; Vereshchagin, Gregory; Xue, She-Sheng

    2010-02-01

    Due to the interaction of physics and astrophysics we are witnessing in these years a splendid synthesis of theoretical, experimental and observational results originating from three fundamental physical processes. They were originally proposed by Dirac, by Breit and Wheeler and by Sauter, Heisenberg, Euler and Schwinger. For almost seventy years they have all three been followed by a continued effort of experimental verification on Earth-based experiments. The Dirac process, e+e-→2γ, has been by far the most successful. It has obtained extremely accurate experimental verification and has led as well to an enormous number of new physics in possibly one of the most fruitful experimental avenues by introduction of storage rings in Frascati and followed by the largest accelerators worldwide: DESY, SLAC etc. The Breit-Wheeler process, 2γ→e+e-, although conceptually simple, being the inverse process of the Dirac one, has been by far one of the most difficult to be verified experimentally. Only recently, through the technology based on free electron X-ray laser and its numerous applications in Earth-based experiments, some first indications of its possible verification have been reached. The vacuum polarization process in strong electromagnetic field, pioneered by Sauter, Heisenberg, Euler and Schwinger, introduced the concept of critical electric field Ec=me2c3/(eħ). It has been searched without success for more than forty years by heavy-ion collisions in many of the leading particle accelerators worldwide. The novel situation today is that these same processes can be studied on a much more grandiose scale during the gravitational collapse leading to the formation of a black hole being observed in Gamma Ray Bursts (GRBs). This report is dedicated to the scientific race. The theoretical and experimental work developed in Earth-based laboratories is confronted with the theoretical interpretation of space-based observations of phenomena originating on cosmological

  16. Studies of the shapes of heavy pear-shaped nuclei at ISOLDE

    NASA Astrophysics Data System (ADS)

    Butler, P. A.

    2016-07-01

    For certain combinations of protons and neutrons there is a theoretical expectation that the shape of nuclei can assume octupole deformation, which would give rise to reflection asymmetry or a "pear-shape" in the intrinsic frame, either dynamically (octupole vibrations) or statically (permanent octupole deformation). I will briefly review the historic evidence for reflection asymmetry in nuclei and describe how recent experiments carried out at REX-ISOLDE have constrained nuclear theory and how they contribute to tests of extensions of the Standard Model. I will also discuss future prospects for measuring nuclear shapes from Coulomb Excitation: experiments are being planned that will exploit beams from HIE-ISOLDE that are cooled in the TSR storage ring and injected into a solenoidal spectrometer similar to the HELIOS device developed at the Argonne National Laboratory.

  17. Nilsson-SU3 self-consistency in heavy N =Z nuclei

    NASA Astrophysics Data System (ADS)

    Zuker, A. P.; Poves, A.; Nowacki, F.; Lenzi, S. M.

    2015-08-01

    It is argued that there exist natural shell-model spaces optimally adapted to the operation of two variants of Elliott's SU3 symmetry that provide accurate predictions of quadrupole moments of deformed states. A self-consistent Nilsson-like calculation describes the competition between the realistic quadrupole force and the central field, indicating a remarkable stability of the quadrupole moments—which remain close to their quasi- and pseudo-SU3 values—as the single-particle splittings increase. A detailed study of the N =Z even nuclei from 56Ni to 96Cd reveals that the region of prolate deformation is bounded by a pair of transitional nuclei 72Kr and 84Mo in which prolate ground-state bands are predicted to dominate, though coexisting with oblate ones.

  18. Studies of the shapes of heavy pear-shaped nuclei at ISOLDE

    SciTech Connect

    Butler, P. A.

    2016-07-07

    For certain combinations of protons and neutrons there is a theoretical expectation that the shape of nuclei can assume octupole deformation, which would give rise to reflection asymmetry or a ”pear-shape” in the intrinsic frame, either dynamically (octupole vibrations) or statically (permanent octupole deformation). I will briefly review the historic evidence for reflection asymmetry in nuclei and describe how recent experiments carried out at REX-ISOLDE have constrained nuclear theory and how they contribute to tests of extensions of the Standard Model. I will also discuss future prospects for measuring nuclear shapes from Coulomb Excitation: experiments are being planned that will exploit beams from HIE-ISOLDE that are cooled in the TSR storage ring and injected into a solenoidal spectrometer similar to the HELIOS device developed at the Argonne National Laboratory.

  19. Study of near-stability nuclei populated as fission fragments in heavy-ion fusion reactions

    SciTech Connect

    Fotiadis, Nikolaos; Nelson, Ronald O; Devlin, Matthew; Cizewski, Jolie A; Krucken, Reiner; Clark, R M; Fallon, Paul; Lee, I Yang; Macchiavelli, Agusto O; Becker, John A; Younes, Walid

    2010-01-01

    Examples are presented to illustrate the power of prompt {gamma}-ray spectroscopy of fission fragments from compound nuclei with A {approx} 200 formed in fusion-evaporation reactions in experiments using the Gammasphere Ge-detector array. Complementary methods, such as Coulomb excitation and deep-inelastic processes, are also discussed. In other cases (n, xn{gamma}) reactions on stable isotopes have been used to establish neutron excitation functions for {gamma}-rays using a pulsed 'white'-neutron source, coupled to a high-energy-resolution germanium-detector array. The excitation functions can unambiguously assign {gamma}-rays to a specific reaction product. Results from all these methods bridge the gaps in the systematics of high-spin states between the neutron-deficient and neutron-rich nuclei. Results near shell closures should motivate new shell model calculations.

  20. The study of initial conditions in collisions of light, intermediate and heavy nuclei

    NASA Astrophysics Data System (ADS)

    Loctionov, A. A.; Arginova, A. Kh.; Gaitinov, A. Sh.; Kvochkina, T. N.

    2017-06-01

    The system size dependence for multiparticle processes has been recognized in both cosmic ray ("Stratosphere" collaboration) and at accelerator ("EMU" collaboration) experiments. The strong enhancement in multiplicity fluctuations for the most central light-light - (C, O, Ne) + (C/N/O) - collisions has been revealed at JINR-AGS-SPS energies. The sharp difference of light nuclear interactions are interpreted as the sign of intrinsic alpha-clustering in light nuclei.

  1. Isospin asymmetry dependence of the α spectroscopic factor for heavy nuclei

    NASA Astrophysics Data System (ADS)

    Seif, W. M.; Shalaby, M.; Alrakshy, M. F.

    2011-12-01

    Both the valence nucleons (holes) and the isospin asymmetry dependencies of the preformation probability of an α-cluster inside parents radioactive nuclei are investigated. The calculations are employed in the framework of the density-dependent cluster model of an α-decay process for the even-even spherical parents nuclei with protons number around the closed shell Z0 = 82 and neutrons number around the closed shells Z0 = 82 and Z0 = 126. The microscopic α-daughter nuclear interaction potential is calculated in the framework of the Hamiltonian energy density approach based on the SLy4 Skyrme-like effective interaction. Also, the calculations based on the realistic effective M3Y-Paris nucleon-nucleon force have been used to confirm the results. The calculations then proceed to find the assault frequency and the α penetration probability within the WKB approximation. The half-lives of the different mentioned α decays are then determined and have been used in turn to find the α spectroscopic factor. We found that the spectroscopic factor increases with increasing the isospin asymmetry of the parent nuclei if they have valence protons and neutrons. When the parent nuclei have neutron or proton holes in addition to the valence protons or neutrons, then the spectroscopic factor is found to decrease with increasing isospin asymmetry. The obtained results show also that the deduced spectroscopic factors follow individual linear behaviors as a function of the multiplication of the valence proton (Np) and neutron (Nn) numbers. These linear dependencies are correlated with the closed shells core (Z0,N0). The same individual linear behaviors are obtained as a function of the multiplication of NpNn and the isospin asymmetry parameter, NpNnI. Moreover, the whole deduced spectroscopic factors are found to exhibit a nearly general linear trend with the function NpNn/(Z0+N0).

  2. Nucleon pairing correlations and the α cluster preformation probability inside heavy and superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Seif, W. M.

    2015-01-01

    The presence of paired or unpaired protons and neutrons in the open-shell radioactive α emitter affects the preformation probability of the α cluster inside it. The α-preformation probability inside the odd ( Z )-even ( N ) , even ( Z )-odd ( N ) , and odd ( Z )-odd ( N ) α emitters is investigated. The study is restricted to those decays with no angular momentum transfer to make a precise prediction about the mere pairing effect. The extended cluster model of α decay and the WKB approximation are used by taking into account the deformation degrees of freedom to carry out the calculations for 105 parent nuclei in the mass region of A =175 -289 . The α + daughter interaction potential is calculated by using the Hamiltonian energy-density approach in terms of the SLy4 Skyrme-like interaction, then it is implemented to find the average decay width over the different orientations. The half-life of the decay is then estimated and employed in turn to extract the α-preformation probability by taking account of errors on both the released energy and the experimental half-life time. According to the present calculations, it is found that the α cluster preformation probability inside the nuclei which have unpaired nucleons is less than it would be in the neighboring nuclei of the same shell and subshell closures but have no unpaired nucleons. In particular, the effect of the single unpaired neutron in the even ( Z )-odd ( N ) nuclei is slightly larger than that of the single unpaired proton in the odd ( Z )-even ( N ) ones. The effect of the unpaired nucleons appears more clearly in the odd ( Z )-odd ( N ) nuclei which have both an unpaired neutron and an unpaired proton. Based on the obtained results, an empirical pairing term is added to the empirical formula [J. Phys. G 40, 105102 (2013), 10.1088/0954-3899/40/10/105102] that relates the α cluster preformation probability to the proton and neutron numbers outside the closed shells of the parent nucleus.

  3. Observations of columnal recombination in the ionization tracks of energetic heavy nuclei in an argon-methane gas mixture

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, Mark E.

    1990-01-01

    Measurements of ionization signals resulting from the passage of energetic heavy nuclei through a gas mixture consisting of 95 mol percent Ar plus 5 mol percent CH4, at an absolute pressure of 3 atm are presented. The measurements take place under a uniform electric field perpendicular to the ionization track. The signals were compared to the calculated energy losses, with an assumption of proportionality between energy loss rate and ionization rate. Significant deviations from proportionality are found for energy loss rate grater than about 3000 MeV sq cm/g, while fractional deviations are found to be proportional to the energy loss rate (dE/dx) exp m, where m is equal to about two. These results are attributed to the columnal recombination.

  4. Science requirements for Heavy Nuclei Collection (HNC) experiment on NASA Long Duration Exposure Facility (LDEF) Mission 2

    NASA Technical Reports Server (NTRS)

    Price, P. Buford

    1991-01-01

    The Heavy Nuclei Collection (HNC) is a passive array of stacks of a special glass, 14 sheets thick, that record tracks of ultraheavy cosmic rays for later readout by automated systems on Earth. The primary goal is to determine the relative abundances of both the odd- and even-Z cosmic rays with Z equal to or greater than 50 with statistics a factor at least 60 greater than obtained in HEAO-3 and to obtain charge resolution at least as good as 0.25 charge unit. The secondary goal is to search for hypothetical particles such as superheavy elements. The HNC detector array will have a cumulative collection power equivalent to flying 32 sq m of detectors in space for 4 years. The array will be flown as a free-flight spacecraft and/or attached to Space Station Freedom.

  5. Observations of columnal recombination in the ionization tracks of energetic heavy nuclei in an argon-methane gas mixture

    NASA Technical Reports Server (NTRS)

    Wiedenbeck, Mark E.

    1990-01-01

    Measurements of ionization signals resulting from the passage of energetic heavy nuclei through a gas mixture consisting of 95 mol percent Ar plus 5 mol percent CH4, at an absolute pressure of 3 atm are presented. The measurements take place under a uniform electric field perpendicular to the ionization track. The signals were compared to the calculated energy losses, with an assumption of proportionality between energy loss rate and ionization rate. Significant deviations from proportionality are found for energy loss rate grater than about 3000 MeV sq cm/g, while fractional deviations are found to be proportional to the energy loss rate (dE/dx) exp m, where m is equal to about two. These results are attributed to the columnal recombination.

  6. Isobaric yield ratios in heavy-ion reactions, and symmetry energy of neutron-rich nuclei at intermediate energies

    NASA Astrophysics Data System (ADS)

    Ma, Chun-Wang; Wang, Fang; Ma, Yu-Gang; Jin, Chan

    2011-06-01

    The isobaric yield ratios of the fragments produced in the neutron-rich Ca48 and Ni64 projectile fragmentation are analyzed in the framework of a modified Fisher model. The correlations between the isobaric yield ratios (R) and the energy coefficients in the Weiszäcker-Beth semiclassical mass formula (the symmetry-energy term asym, the Coulomb-energy term ac, and the pairing-energy term ap) and the difference between the chemical potentials of the neutron and proton (μn-μp) are investigated. Simple correlations between (μn-μp)/T, ac/T, asym/T, and ap/T (where T is the temperature), and lnR are obtained. It is suggested that (μn-μp)/T, ac/T, asym/T, and ap/T of neutron-rich nuclei can be extracted using isobaric yield ratios for heavy-ion collisions at intermediate energies.

  7. Simultaneous description of low-lying positive and negative parity bands in heavy even-even nuclei

    NASA Astrophysics Data System (ADS)

    Ganev, H. G.

    2014-05-01

    The low-lying spectra including the first few excited positive and negative parity bands of some heavy even-even nuclei from the rare earth and actinide mass regions are investigated within the framework of the symplectic interacting vector boson model with the Sp(12,R) dynamical symmetry group. Symplectic dynamical symmetries allow the change of the number of excitation quanta or phonons building the collective states, providing for larger representation spaces and richer subalgebraic structures to incorporate more complex nuclear spectra. The theoretical predictions for the energy levels and the electromagnetic transitions between the collective states of the ground-state band and Kπ=0- band are compared with experiment and some other collective models incorporating octupole and/or dipole degrees of freedom. The energy staggering, which is a sensitive indicator of the octupole correlations in even-even nuclei, is also calculated and compared with experiment. The results obtained for the energy levels, energy staggering, and transition strengths reveal the relevance of the dynamical symmetry used in the model to simultaneously describe both positive and negative parity low-lying collective bands.

  8. Forward-backward multiplicity fluctuations in heavy nuclei collisions in the wounded nucleon model

    SciTech Connect

    Bzdak, Adam; Wozniak, Krzysztof

    2010-03-15

    We use the wounded nucleon model to study the forward-backward multiplicity fluctuations measured by the PHOBOS Collaboration in Au + Au collisions at sq root(s{sub N{sub N}})=200 GeV. The enhancement of forward-backward fluctuations in Au + Au collisions with respect to the elementary p+p interactions is explained in this model by the asymmetric shape of the pseudorapidity density of produced particles from a single wounded nucleon and the fluctuations of the number of wounded nucleons in the colliding nuclei. The wounded nucleon model describes these experimental data better than the HIJING, AMPT, or UrQMD models do.

  9. Fission barriers for Po nuclei produced in complete fusion reactions with heavy ions

    SciTech Connect

    Sagaidak, R. N.; Andreyev, A. N.

    2009-05-15

    Evaporation residues and fission excitation functions obtained in complete fusion reactions leading to Po compound nuclei have been analyzed in the framework of the standard statistical model. Macroscopic fission barriers deduced from the cross-section data analysis are compared with the predictions of various theoretical models and available data. A drop in the Po barriers with the decrease in a neutron number was found, which is stronger than predicted by any theory. The presence of entrance channel effects and collective excitations in the compound nucleus decay is considered as a possible reason for the barrier reduction.

  10. Fusion-Evaporation Cross Sections in Reactions Leading to Production of Super-Heavy Nuclei

    SciTech Connect

    Siwek-Wilczynska, K.; Skwira-Chalot, I.; Wilczynski, J.

    2006-08-14

    Fusion-evaporation cross sections were calculated for the 48Ca+204-208Pb and 50Ti+206,208Pb reactions and compared with the existing experimental data of the Dubna and GSI groups. The survival probabilities of the compound Z 102 and Z = 104 nuclei formed in these reactions were calculated using a Monte Carlo program based on the conventional Bohr-Wheeler theory of fission and statistical model of particle evaporation with Reisdorf-Ignatyuk prescription for the level densities and Strutinsky shell corrections of Moeller et al. 'Empirical' magnitudes of the dynamical hindrance of fusion have been deduced for these reactions.

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

    SciTech Connect

    Mazurek, Katarzyna; Dudek, Jerzy

    2005-11-21

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

  12. Heavy nuclei far from stability in the N < 126, Z > 82 region

    SciTech Connect

    Back, B.B.; Blumenthal, D.J.; Carpenter, M.P.

    1995-08-01

    There are long-standing calculations suggesting that nuclei in the N < 126, Z > 82 region far from stability exhibit deformation effects. Away from stability an observable permanent quadrupole deformation should be achieved but, as yet, there is no experimental evidence for such an effect. A series of experiments was performed to assess the production of nuclei in this region and to study their structure. These experiments were performed using gamma-ray spectroscopy to investigate the low-lying level schemes and alpha-particle spectroscopy in order to isolate fine structure in the decay. The low-lying level structure of the neutron-deficient isotope {sup 202}Rn was studied, for the first time, using the {sup 181}Ta({sup 27}Al,6n) and {sup 192}Pt({sup 16}O,6n) reactions. Gamma-ray transitions between excited states in {sup 202}Rn were identified by mass tagging the Fragment Mass Analyzer and by observation of coincident X rays. Transitions in {sup 203}Rn were also identified. The level scheme deduced from these data is consistent with the systematics of light radon isotopes below the N = 126 shell closure and with theoretical calculations indicating that the ground-state shape should not be strongly deformed at N = 116.

  13. On the charge to mass ratio of neutron cores and heavy nuclei

    SciTech Connect

    Patricelli, B.; Rotondo, M.; Ruffini, R.

    2008-01-03

    We determine theoretically the relation between the total number of protons N{sub p} and the mass number A (the charge to mass ratio) of nuclei and neutron cores with the model recently proposed by Ruffini et al. (2007) and we compare it with other N{sub p} versus A relations: the empirical one, related to the Periodic Table, and the semi-empirical relation, obtained by minimizing the Weizsaecker mass formula. We find that there is a very good agreement between all the relations for values of A typical of nuclei, with differences of the order of per cent. Our relation and the semi-empirical one are in agreement up to A{approx}10{sup 4}; for higher values, we find that the two relations differ. We interprete the different behaviour of our theoretical relation as a result of the penetration of electrons (initially confined in an external shell) inside the core, that becomes more and more important by increasing A; these effects are not taken into account in the semi-empirical mass-formula.

  14. Spectroscopy of neutron-rich nuclei populated through binary heavy-ion collisions

    SciTech Connect

    Lunardi, S.

    2009-05-04

    Neutron-rich nuclei from A = 50 to A = 80 have been studied through multi-nucleon transfer reactions by bombarding {sup 208}Pb and {sup 238}U targets with beams of {sup 48}Ca, {sup 64}Ni, {sup 70}Zn and {sup 82}Se. The gamma-array CLARA coupled to the large-acceptance magnetic spectrometer PRISMA gave unambiguous identification of prompt {gamma} rays belonging to each nucleus. The existence of the N = 32 sub-shell closure has been corroborated through the study of odd V isotopes, whereas a sizable gap at N = 34 has been evidenced from the spectroscopy of {sup 51}Ca and {sup 52}Sc. The evolution of the N = 50 shell closure far from stability has been studied down to Z = 31. With the {sup 48}Ca beam we have applied for the first time the Recoil Distance Dopple Shift technique to measure lifetimes of neutron-rich nuclei populated in multi-nucleon transfer reactions. Effective charges in the fp shell above {sup 48}Ca have been derived. The first implementation of the tracking array AGATA (the so called 'Demon-strator') will be soon coupled to the PRISMA spectrometer at Legnaro. The future prospects with the use of the Demonstrator are also presented.

  15. Photo-fission for the production of radioactive beams ALTO project

    NASA Astrophysics Data System (ADS)

    Essabaa, S.; Arianer, J.; Ausset, P.; Bajeat, O.; Baronick, J. P.; Clapier, F.; Coacolo, L.; Donzaud, C.; Ducourtieux, M.; Galès, S.; Gardès, D.; Grialou, D.; Hosni, F.; Guillemaud-Mueller, D.; Ibrahim, F.; Junquera, T.; Lau, C.; Le Blanc, F.; Lefort, H.; Le Scornet, J. C.; Lesrel, J.; Mueller, A. C.; Obert, J.; Perru, O.; Potier, J. C.; Proust, J.; Pougheon, F.; Roussière, B.; Rouvière, N.; Sauvage, J.; Sorlin, O.; Tkatchenko, A.; Verney, D.; Waast, B.; Rinolfi, L.; Rossat, G.; Forkel-Wirth, D.; Muller, A.; Bienvenu, G.; Bourdon, J.-C.; Garvey, T.; Jacquemard, B.; Omeich, M.

    2003-05-01

    In order to probe neutron rich radioactive noble gases produced by photo-fission, a PARRNe-1 experiment (Production d'Atomes Radioactifs Riches en Neutrons) has been carried out at CERN. The incident electron beam of 50 MeV was delivered by the LIL machine: LEP Injector Linac. The experiment allowed us to compare under the same conditions two production methods of radioactive noble gases: fission induced by fast neutrons and photo-fission. The obtained results show that the use of the electrons is a promising mode to get intense neutron rich ion beams. After the success of this photo-fission experiment, a conceptual design for the installation at IPN Orsay of a 50 MeV electron accelerator close to the PARRNe-2 device has been worked out: ALTO Project. This work has started within a collaboration between IPNO, LAL (Laboratoire de l'Accélérateur Linéaire) and CERN groups.

  16. Precision requirement of the photofission cross section for the nondestructive assay

    NASA Astrophysics Data System (ADS)

    Kimura, Rei; Sagara, Hiroshi; Chiba, Satoshi

    2017-09-01

    Principle of the new NDA technique based on the photofission reaction rate ratio (PFRR) has been developed by Kimura et al for measurement of uranium enrichment by using the only relative measured counts of neutron produced by photofission reactions of 235U and 238U at different specific incident photon energies. In the past analysis, no attentions have been paid for relatively large uncertainty of photonuclear cross section of special nuclear materials around 10%. In the present paper, quantitative analysis was performed to reveal the impact of photonuclear cross section uncertainty to predicted value of the uranium enrichment by the PFRR methodology. And also, the requirement of photofission cross section precision was evaluated as less than 3%, to satisfy the uncertainty of PFRR methodology to within 5%.

  17. Production of exotic nuclei in heavy ion collisions at Fermi energies

    NASA Astrophysics Data System (ADS)

    Ogul, R.; Buyukcizmeci, N.; Ergun, A.

    2017-06-01

    Isotopic distributions of projectile fragmentation in peripheral heavy ion collisions of 86Kr on 124Sn are calculated within the statistical multifragmentation model. Obtained data are compared to the experimental cross section measurements. We show the enhancement in the production of neutron-rich isotopes close to the projectile, observed in the experiments. The universality of the limitation of the excitation energy induced in the projectile residues is also demonstrated.

  18. Studies of heavy-ion reactions and transuranic nuclei. Progress report, September 1, 1992--August 31, 1993

    SciTech Connect

    Schroeder, W.U.

    1993-08-01

    This report contain papers on the following topics: The Cold-Fusion Saga; Decay Patterns of Dysprosium Nuclei Produced in {sup 32}S + {sup 118,124}Sn Fusion Reactions; Unexpected Features of Reactions Between Very Heavy Ions at Intermediate Bombarding Energies; Correlations Between Neutrons and Charged Products from the Dissipative Reaction {sup 197}Au+{sup 208}Pb at E/A = 29 MeV; Dissipative Dynamics of Projectile-Like Fragment Production in the Reaction {sup 209}Bi+{sup 136}Xe at E/A = 28.2 MeV; Dynamical Production of Intermediate-Mass Fragments in Peripheral {sup 209}Bi+{sup 136}Xe Collisions at E{sub lab}/A = 28.2 MeV; The Rochester 960-Liter Neutron Multiplicity Meter; A Simple Pulse Processing Concept for a Low-Cost Pulse-Shape-Based Particle Identification; A One-Transistor Preamplifier for PMT Anode Signals; A Five-Channel Multistop TDC/Event Handler for the SuperBall Neutron Multiplicity Meter; Construction of the SuperBall -- a 16,000-Liter Neutron Detector for Calorimetric Studies of Intermediate-Energy Heavy-Ion Reactions; A Computer Code for Light Detection Efficiency Calculations for Photo-multipliers of a Neutron Detector; Evaluation of Gd-Loaded Liquid Scintillators for the SuperBall Neutron Calorimeter; and Measurement of the Interaction of Cosmic-Ray {mu}{sup {minus}} with a Muon Telescope.

  19. Triaxial quadrupole dynamics and the inner fission barrier of some heavy even-even nuclei

    NASA Astrophysics Data System (ADS)

    Benrabia, K.; Medjadi, D. E.; Imadalou, M.; Quentin, P.

    2017-09-01

    Background: Inner fission barriers of actinide nuclei have been known for a long time to be unstable with respect to the axial symmetry. On the other hand, taking into account the effect of the relevant adiabatic mass parameter reduces or even may wash out this instability. A proper treatment of the dynamics for both axial and triaxial modes is thus crucial to accurately determine the corresponding fission barriers. This entails in particular an accurate description of pairing correlations. Purpose: We evaluate the potential energies, moments of inertia, and vibrational mass parameters in a two-dimensional relevant deformation space (corresponding to the usual β and γ quadrupole deformation parameters) for four actinide nuclei (236U, 240Pu, 248Cm, and 252Cf). We assess the relevance of our approach to describe the dynamics for a triaxial mode by computing the low energy spectra (exploring thus mainly the equilibrium deformation region). We evaluate the inner fission barrier heights releasing the axial symmetry constraint. Method: Calculations within the Hartree-Fock plus BCS approach are performed using the SkM* Skyrme effective interaction in the particle-hole channel and a seniority force in the particle-particle channel. The intensity of this residual interaction has been fixed to allow a good reproduction of some odd-even mass differences in the actinide region. Adiabatic mass parameters for the rotational and vibrational modes are calculated using the Inglis-Belyaev formula supplemented by a global renormalization factor taking into account the so-called Thouless-Valatin corrections. Spectra are obtained through the diagonalization of the corresponding Bohr collective Hamiltonian. Results: The experimental low energy spectra are qualitatively well reproduced by our calculations for the considered nuclei. Inner fission barrier heights are calculated and compared with available estimates from various experimental data. The reproduction of the data is better

  20. Ion-induced gammas for photofission interrogation of HEU.

    SciTech Connect

    Doyle, Barney Lee (Sandia National Laboratories, Albuquerque, NM); Antolak, Arlyn J.; Morse, Daniel H.; Provencio, Paula Polyak (Sandia National Laboratories, Albuquerque, NM)

    2006-03-01

    High-energy photons and neutrons can be used to actively interrogate for heavily shielded special nuclear material (SNM), such as HEU (highly enriched uranium), by detecting prompt and/or delayed induced fission signatures. In this work, we explore the underlying physics for a new type of photon source that generates high fluxes of mono-energetic gamma-rays from low-energy (<500 keV) proton-induced nuclear reactions. The characteristic energies (4- to 18-MeV) of the gamma-rays coincide with the peak of the photonuclear cross section. The source could be designed to produce gamma-rays of certain selected energies, thereby improving the probability of detecting shielded HEU or providing a capability to determine enrichment inside sealed containers. The fundamental physics of such an interrogation source were studied in this LDRD through scaled ion accelerator experiments and radiation transport modeling. The data were used to assess gamma and neutron yields, background, and photofission-induced signal levels from several (p,{gamma}) target materials under consideration.

  1. LDEF (Postflight), AO178 : A High-Resolution Study of Ultra-heavy Cosmic-Ray Nuclei, Tray D05

    NASA Technical Reports Server (NTRS)

    1990-01-01

    LDEF (Postflight), AO178 : A High-Resolution Study of Ultra-heavy Cosmic-Ray Nuclei, Tray D05 EL-1994-00311 LDEF (Postflight), AO178 : A High-Resolution Study of Ultra-heavy Cosmic-Ray Nuclei, Tray D05 The postflight photograph of the Ultra Heavy Cosmic Ray Experiment (UHCRE) was taken in SAEF II at KSC after removal of the experiment tray from the LDEF. The experiment tray flanges appear discolored by a brown stain. Outlines of experiment tray clamp blocks are clearly visible on the upper and lower tray flanges. The experiment tray holding fixture hardware covers the clamp block areas on the end flanges. The UHCRE detectors were contained in 16 peripheral LDEF trays with at least one UHCRE tray located on each row of the LDEF except row 3, row 9 and row 12. Each tray contains three cylindrical aluminum pressure vessels with an integral aluminum support structure. Each cylinder is filled with an Eccofoam insert that houses 4 UHCRE detector stacks. Each stack consist of layers of Lexan polycarbonate sheets (approximately 70) interleaved with several thin sheets of lead. Forty-seven of the 48 pressure vessels were pressurized to 1.0 bar of a dry gas mixture (oxygen, nitrogen and helium) and sealed. One of the units was left unsealed in order to investigate the effects of the vacuum environment on the detector materials. Thermal control was accomplished by attaching an aluminized Kapton thermal cover on the tray bottom (the Kapton facing the LDEF interior), placing the aluminum cylinder support structure on thermal isolators and covering the experiment with a thin (5 mil) silvered TEFLON® thermal cover. The silvered TEFLON® cover was supported by an aluminum frame, an integral part of the experiment structure, and held in place by Velcro pads selectively located on the frame and on the back of the cover. The copper colored strip extending over the trays lower flange is a copper coated pressure sensitive tape used to provide an electrical ground between the

  2. Islands of stability and quasi-magic numbers for super- and ultra-heavy nuclei

    NASA Astrophysics Data System (ADS)

    Ismail, M.; Ellithi, A. Y.; Adel, A.; Anwer, Hisham

    2016-12-01

    In the framework of Strutinsky’s approach, we calculated the shell and the residual pairing correction energies for 5569 even-even nuclei in the range 72 ⩽ Z ⩽ 282 and 96 ⩽ N ⩽ 540. Quasi-magic numbers and deformed islands of stability that reside in a range defined by Green’s formula and the two-neutrons drip line are introduced. We present 36 quasi-magic proton and 53 quasi-magic neutron magic numbers that contribute to the formation of 133 deformed islands of stability along the N-Z space. The quasi-magic proton and neutron magic numbers volatile as the mass number increases and other magic numbers take over. Consequently, the deformed islands of stability fail to exhibit a pattern along the search space covered.

  3. Enhancement of solar heavy nuclei at high energies in the 4 July 1974 event

    NASA Technical Reports Server (NTRS)

    Bertsch, D. L.; Reames, D.

    1976-01-01

    Relative abundances of energetic nuclei in the 4 July 1974 solar event are presented. The results show a marked enhancement of abundances that systematically increase with nuclear charge numbers in the range of the observation, 6 less than or equal to Z less than or equal to 26 for energies above 15 MeV/nucleon. While such enhancements are commonly seen below 10 MeV/nucleon, most observations at higher energies are found to be consistent with solar system abundances. The energy spectrum of oxygen is observed to be significantly steeper than most other solar events studied in this energy region. It is proposed that these observations are characteristic of particle populations at energies approximately 1 MeV/nucleon, and that the anomalous features observed here may be the result of the high energy extension of such a population that is commonly masked by other processes or populations that might occur in larger solar events.

  4. Detection of the isotopes of heavy cosmic ray nuclei. [by particle counter telescope

    NASA Technical Reports Server (NTRS)

    Gilman, C. M.; Waddington, C. J.

    1975-01-01

    A counter telescope designed to detect and resolve the isotopic composition of cosmic ray nuclei heavier than neon is being prepared. The telescope consists of a rather conventional charge measuring array using two scintillator elements and two solid Cerenkov radiators of differing refractive index. The mass measurement is obtained by combining the velocity information from one or both of the Cerenkov radiators operating near their threshold with residual range measured in a block of nuclear emulsion. Path length corrections and particle location in the emulsions is provided by a spark chamber fired in coincidence with potentially suitable particles. The telescope has a geometry factor of 530 sq cm sr roughly. It should be able to resolve the isotopes of iron over the energy range of 300 to 720 Mev/n and those of neon over 300 to 400 MeV/n. The expected response and characteristics of the telescope are described in detail and the sensitivity to rare isotopes discussed.

  5. The Energetic Trans-Iron Composition Experiment (ENTICE) on the Heavy Nuclei Explorer (HNX)

    NASA Technical Reports Server (NTRS)

    Israel, M. H.; Adams, J. H.; Barbier, L. M.; Binns, W. R.; Christian, E. R.; Cummings, A. C.; Cummings, J. R.; Doke, T.; Hasebe, N.; Hayashi, T.; hide

    2001-01-01

    The ENTICE experiment is one of two instruments which make up the HNX mission. The experimental goal of ENTICE is to measure with high precision the elemental abundances of all nuclei with 10<=Z<=82. This will enable us to distinguish between possible injection mechanisms for the galactic cosmic ray accelerator such-as those dependent upon volatility or first ionization potential, and to study the mix of nucleosynthetic processes that contribute to the galactic cosmic ray source. The ENTICE experiment utilizes the dE/dx-C method of charge determination and consists of silicon dE/dx detectors, Cherenkov detectors with two different refractive indices, and a scintillating fiber hodoscope. The geometrical factor of the instrument is 8m2.sr. We will present a description of the instrument and its expected performance based on beam tests and a balloon flight of a prototype instrument.

  6. The Energetic Trans-Iron Composition Experiment (ENTICE) on the Heavy Nuclei Explorer (HNX) Mission

    NASA Technical Reports Server (NTRS)

    Israel, M. H.; Adams, James H., Jr.; Barbier, L. M.; Binns, W. R.; Christian, E. R.; Craig, N.; Cummings, A. C.; Doke, T.; Hasebe, N.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    The ENTICE experiment is one of two instruments that make up the HNX mission. The experimental goal of ENTICE is to measure with high precision the elemental abundances of all nuclei with Z between 10 and 82. This will enable us to determine if the injection mechanism for the cosmic ray accelerator is controlled by FIP or Volatility and to study the mix of nucleosynthetic processes that contribute to the galactic cosmic ray source. The ENTICE experiment utilizes the dE/dx-C method of charge determination and consists of silicon dE/dx detectors, Cherenkov detectors with two different refractive indices, and a fiber hodoscope. We will describe the instrument and its performance based on beam tests of a prototype instrument.

  7. Recent β-delayed neutron branching ratios of measurements with heavy nuclei

    NASA Astrophysics Data System (ADS)

    Caballero-Folch, Roger; Dillmann, Iris; Agramunt, Jorge; Tain, Jose Luis

    2016-09-01

    The understanding of the nuclear structure of the neutron-rich nuclei and several astrophysical phenomena, such as the r-process, is a challenge that need new experimental values to provide more realistic data inputs in theoretical models. The aim of this study is to achieve new β-delayed neutron branching ratios, Pn, of very neutron-rich nuclei. Experiments recently performed at the RIB facilities of GSI Darmstadt (Germany) and IGISOL in Jyväskylä (Finland) allowed to determine Pn values for heavier isotopes than those measured so far with a 4pi neutron detector based on 3He counters. At GSI it was possible to measure β1n emitters for several Hg and Tl isotopes with masses beyond A>200 and N>126, and at IGISOL the β2n emitter 136Sb, which represents an important leap in terms of mass since the heaviest known were around A 150 for β1n and A 100 for β2n. Results of P1n and P2n values will be presented, together with the new plans for β-delayed neutron emitter measurements at RIKEN (Japan). The BRIKEN project aims to measure more than a hundred of β1n, and many β2n and β3n emitters, a lot of them for the first time. These isotopes will be the most neutron-rich species measured so far. This work was partially supported by the Spanish Ministry of Economy and Competitivity under Grant FPA2011-28770-C03-03. TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada.

  8. Active Interrogation using Photofission Technique for Nuclear Materials Control and Accountability

    SciTech Connect

    Yang, Haori

    2016-03-31

    Innovative systems with increased sensitivity and resolution are in great demand to detect diversion and to prevent misuse in support of nuclear materials management for the U.S. fuel cycle. Nuclear fission is the most important multiplicative process involved in non-destructive active interrogation. This process produces the most easily recognizable signature for nuclear materials. In addition to thermal or high-energy neutrons, high-energy gamma rays can also excite a nucleus and cause fission through a process known as photofission. Electron linear accelerators (linacs) are widely used as the interrogating photon sources for inspection methods involving photofission technique. After photofission reactions, prompt signals are much stronger than the delayed signals, but it is difficult to quantify them in practical measurements. Delayed signals are easily distinguishable from the interrogating radiation. Linac-based, advanced inspection techniques utilizing the delayed signals after photofission have been extensively studied for homeland security applications. Previous research also showed that a unique delayed gamma ray energy spectrum exists for each fissionable isotope. In this work, high-energy delayed γ-rays were demonstrated to be signatures for detection, identification, and quantification of special nuclear materials. Such γ-rays were measured in between linac pulses using independent data acquisition systems. A list-mode system was developed to measure low-energy delayed γ-rays after irradiation. Photofission product yields of 238U and 239Pu were determined based on the measured delayed γ-ray spectra. The differential yields of delayed γ-rays were also proven to be able to discriminate nuclear from non-nuclear materials. The measurement outcomes were compared with Monte Carlo simulation results. It was demonstrated that the current available codes have capabilities and limitations in the simulation of photofission process. A two

  9. Nucleon and heavy-ion total and absorption cross section for selected nuclei

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Costner, C. M.

    1975-01-01

    Approximate solutions of the coupled-channel equations for high-energy composite particle scattering are obtained and are applied to the nuclear scattering problem. Relationships between several approximation procedures are established and discussed. The eikonal formalism is used with a small-angle approximation to calculate the coherent elastic scattered amplitude from which total and absorption cross sections are derived. Detailed comparisons with nucleon-nucleus experiments show agreement within 5 percent except at lower energies where the eikonal approximation is of questionable accuracy. Even at these lower energies, agreement is within 15 percent. Tables of cross sections required for cosmic heavy-ion transport and shielding studies are presented.

  10. Hypertriton and light nuclei production at Lambda-production subthreshold energy in heavy-ion collisions

    SciTech Connect

    Zhang, S.; Zu, Z.; Chen, J.H., Ma, Y.G., Cai, X-Z, Ma, G.L., Zhong, C.

    2011-08-01

    High-energy heavy-ion collisions produce abundant hyperons and nucleons. A dynamical coalescence model coupled with the ART model is employed to study the production probabilities of light clusters, deuteron (d), triton (t), helion ({sup 3}He), and hypertriton ({sub {Lambda}}{sup 3}H) at subthreshold energy of Aproduction ({approx} 1 GeV per nucleon). We study the dependence on the reaction system size of the coalescence penalty factor per additional nucleon and entropy per nucleon. The Strangeness Population Factor (S{sub 3} = {sup 3}{sub {Lambda}}H/({sup 3}He x {Lambda}/p)) shows an extra suppression of hypertriton comparing to light clusters of the same mass number. This model predicts a hypertriton production cross-section of a few {mu}b in {sup 36}Ar+{sup 36}Ar, {sup 40}Ca+{sup 40}Ca and {sup 56}Ni+{sup 56}Ni in 1 A GeV reactions. The production rate is as high as a few hypertritons per million collisions, which shows that the fixed-target heavy-ion collisions at CSR (Lanzhou/China) at {Lambda} subthreshold energy are suitable for breaking new ground in hypernuclear physics.

  11. Magnetic Dipole Moment Measurements of Picosecond States in Even and Odd Heavy Nuclei

    NASA Astrophysics Data System (ADS)

    Ballon, Douglas Jude

    The perturbed angular correlation and transient field technique is used to measure the precession of nuclear magnetic moments of low lying excited states in isotopes of silver, neodymium, samarium, and gadolinium. The precession measurements are used to explore three main areas of study. First, from the measurements made on ('150)Sm traversing gadolinium targets, the temperature dependence of the transient hyperfine field is deduced at ('150)Sm nuclei traveling at 2 < v/v(,0) < 4. These are compared with similar measurements made using iron targets. Second, the deduced values of the g-factors of the 2(,1)('+) states in even neodymium, samarium and gadolinium isotopes are discussed in connection with a possible proton shell closure at Z = 64. Third, the deduced values of the g-factors of the 3/2(,1)('-) and 5/2(,1)('-) states of ('107,109)Ag are compared to various theoretical predictions in order to explore any simple relationships that may exist between these states and the first 2(,1)('+) states of neighboring even-even nuclei. The following is a list of g-factors that were measured during the course of this work: (UNFORMATTED TABLE FOLLOWS). g(('107)Ag, 3/2(,1)('-)) = 0.607 (119). g(('109)Ag, 3/2(,1)('-)) = 0.661 (105). g(('107)Ag, 5/2(,1)('-)) = 0.409 (66). g(('109)Ag, 5/2(,1)('-)) = 0.287 (57). g(('144)Nd, 2(,1)('+)) = 0.166 (41). g(('146)Nd, 2(,1)('+)) = 0.312 (49). g(('148)Nd, 2(,1)('+)) = 0.411 (42). g(('150)Nd,2(,1)('+)) = 0.418 (38). g(('148)Sm, 2(,1)('+)) = 0.301 (33). g(('150)Sm, 2(,1)('+)) = 0.381 (27). g(('152)Gd, 2(,1)('+)) = 0.444 (40). (TABLE ENDS). The results of the temperature dependence experiment show deviations from an earlier measurement made using thulium in iron. The g-factors measured in the lighter isotopes of neodymium and samarium are significantly below the collective Z/A value. Fair agreement with the data can be obtained if proton shell closure is assumed at Z = 64 for N < 88. The measured g-factors in the silver isotopes

  12. Heavy ion physics in the intermediate energy range with light nuclei

    NASA Astrophysics Data System (ADS)

    Larochelle, Yves

    1997-04-01

    Projectile fragmentation can be studied in a wide range of excitation energy despite the fact that the projectile cannot undergo violent collisions to avoid losing its identity. The quality of the source determination allows precise analysis of the decay modes of those hot nuclei formed mainly in peripheral collisions. Results from projectile fragmentation of various system will be presented. Binary processes are dominant in the most peripheral collisions. That dominance persists even for the whole domain of impact parameter and at increasing bombarding energies (Y. Larochelle et al., Phys. Lett. B 352 (1995) 8 and ref. therein). In such a study on the 35Cl - 12C system, for the first time (L. Beaulieu et al., Phys. Rev. Let. 77 (1996) 462) a careful selection of the binary events allowed a direct measurement of the total dissipated energy. Besides that strong binary character, experimental evidence has been presented for the formation of a neck-like structure responsible in part for IMF emission in the Fermi energy domain (Y. Larochelle et al., preprint TASCC-P-96-30, submitted to Phys. Rev. C), from reactions of the 35Cl projectile on two targets: 12C and 197Au. Various dynamical approaches will be discussed in that analysis (X. Qian et al., accepted in Nucl. Phys. A), leading to hypotheses to explain the origin of the neck-like structure.

  13. Status and prospects of investigations into the collinear cluster decay of heavy nuclei

    SciTech Connect

    Pyatkov, Yu. V.; Kamanin, D. V.; Alexandrov, A. A.; Alexandrova, I. A.; Mkaza, N.; Zhuchko, V. E.; Kondratyev, N. A.; Kuznetsova, E. A. Mishinsky, G. V.; Malaza, V.; Strekalovsky, A. O.; Strekalovsky, O. V.

    2014-12-15

    Basic experimental results confirming the existence a new cluster-decay type called collinear cluster tripartition (CCT) are presented. Decays of this type manifest themselves, in particular, as a two-dimensional region of a locally enhanced yield of fragments (bump) that corresponds to specific missing-mass values in the mass-mass distribution of fission fragments. One of the decay modes that contribute to the bump can be treated as a cluster-decay type that is new in relation to the well-known heavy-ion or lead radioactivity. The conclusions drawn from an analysis of correlation mass distributions are confirmed by the results obtained from neutron-gated data, measurements of the nuclear charge for CCT events, and the direct detection of new-decay products.

  14. Linac based photofission inspection system employing novel detection concepts

    NASA Astrophysics Data System (ADS)

    Stevenson, John; Gozani, Tsahi; Elsalim, Mashal; Condron, Cathie; Brown, Craig

    2011-10-01

    Rapiscan Systems is developing a LINAC based cargo inspection system for detection of special nuclear material (SNM) in cargo containers. The system, called Photofission Based Alarm Resolution (PBAR) is being developed under a DHD/DNDO Advanced Technology Demonstration (ATD) program. The PBAR system is based on the Rapiscan Eagle P9000 X-ray system, which is a portal system with a commercial 9 MeV LINAC X-ray source. For the purposes of the DNDO ATD program, a conveyor system was installed in the portal to allow scanning and precise positioning of 20 ft ISO cargo containers. The system uses a two step inspection process. In the first step, the basic scan, the container is quickly and completely inspected using two independent radiography arrays: the conventional primary array with high spatial resolution and a lower resolution spectroscopic array employing the novel Z-Spec method. The primary array uses cadmium tungstate (CdWO 4) detectors with conventional current mode readouts using photodiodes. The Z-Spec array uses small plastic scintillators capable of performing very fast (up to 10 8 cps) gamma-ray spectroscopy. The two radiography arrays are used to locate high-Z objects in the image such as lead, tungsten, uranium, which could be potential shielding materials as well as SNM itself. In the current system, the Z-Spec works by measuring the energy spectrum of transmitted X-rays. For high-Z materials the higher end of the energy spectrum is more attenuated than for low-Z materials and thus has a lower mean energy and a narrower width than low- and medium-Z materials. The second step in the inspection process is the direct scan or alarm clearing scan. In this step, areas of the container image, which were identified as high Z, are re-inspected. This is done by precisely repositioning the container to the location of the high-Z object and performing a stationary irradiation of the area with X-ray beam. Since there are a large number of photons in the 9 MV

  15. Unitary version of the single-particle dispersive optical model and single-hole excitations in medium-heavy spherical nuclei

    NASA Astrophysics Data System (ADS)

    Kolomiytsev, G. V.; Igashov, S. Yu.; Urin, M. H.

    2017-07-01

    A unitary version of the single-particle dispersive optical model was proposed with the aim of applying it to describing high-energy single-hole excitations in medium-heavy mass nuclei. By considering the example of experimentally studied single-hole excitations in the 90Zr and 208Pb parent nuclei, the contribution of the fragmentation effect to the real part of the optical-model potential was estimated quantitatively in the framework of this version. The results obtained in this way were used to predict the properties of such excitations in the 132Sn parent nucleus.

  16. A new transition radiation detector to detect heavy nuclei around the knee

    NASA Astrophysics Data System (ADS)

    Boyle, Patrick J.; Swordy, Simon P.; Wakely, Scott P.

    2003-02-01

    The overall cosmic ray intensity spectrum falls as a constant power law over at least 11 decades of particle energy. One of the only features in this spectrum is the slight change in power law index near 1015 eV, often called the ‘knee" of the spectrum. Accurate measurements of cosmic ray elemental abundances into this energy region are expected to reveal the origin of this feature, and possibly the nature of cosmic ray sources. The extremely low intensity of particles at these energies (a few per m2 per year) makes the detection challenging. Since only direct measurements have so far proved reliable for the accurate determination of elemental composition, a large-area, light weight, device is needed to achieve long exposures above the atmosphere either on high-altitude balloons or spacecraft. Here we report on a detector which uses the x-ray transition radiation yield from plastic foams to provide a response into the knee region for heavy elements. We use individual xenon-filled gas proportional tubes as detectors, combined with Amplex ASIC chip electronics for readout. The construction of this type of detector, and its implementation in the upcoming NASA CREAM 100 day high-altitude balloon payload is described. Also discussed is the calibration of the detector in an accelerator beam at CERN and a comparison with GEANT4 Monet Carlo simulations.

  17. Isobaric yield ratios in heavy-ion reactions, and symmetry energy of neutron-rich nuclei at intermediate energies

    SciTech Connect

    Ma Chunwang; Wang Fang; Ma Yugang; Jin Chan

    2011-06-15

    The isobaric yield ratios of the fragments produced in the neutron-rich {sup 48}Ca and {sup 64}Ni projectile fragmentation are analyzed in the framework of a modified Fisher model. The correlations between the isobaric yield ratios (R) and the energy coefficients in the Weiszaecker-Beth semiclassical mass formula (the symmetry-energy term a{sub sym}, the Coulomb-energy term a{sub c}, and the pairing-energy term a{sub p}) and the difference between the chemical potentials of the neutron and proton ({mu}{sub n}-{mu}{sub p}) are investigated. Simple correlations between ({mu}{sub n}-{mu}{sub p})/T, a{sub c}/T, a{sub sym}/T, and a{sub p}/T (where T is the temperature), and lnR are obtained. It is suggested that ({mu}{sub n}-{mu}{sub p})/T, a{sub c}/T, a{sub sym}/T, and a{sub p}/T of neutron-rich nuclei can be extracted using isobaric yield ratios for heavy-ion collisions at intermediate energies.

  18. Durability of targets and foils irradiated by intense heavy ion beams in experiments on synthesis of superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Sagaidak, R. N.

    2017-09-01

    Durability of targets and window foils irradiated by intense heavy ion (HI) beams in the experiments on synthesis of superheavy nuclei, which are carried out in Dubna with Gas-Filled Recoil Separator (DGFRS), has been viewed in various ways. High fluxes of HI and heat generations, which are realized within relatively small areas and thicknesses of these elements of DGFRS, are inherent in such experiments. The lifetimes of the targets and window foils are estimated as the result of HI beam actions such as radiation damages, sputtering and evaporation of atoms. The most critical processes determining the durability of the targets and window foils are discussed. The processes of heat transfer due to thermal conductivity, convection and radiation are also considered from the point of view of possible ways of cooling of the elements irradiated by an intense HI beam. Temperatures of the targets and window foils as functions of time are calculated in the conditions of their pulse heating by the beam followed by radiative cooling of their surfaces. Such pulsing mode is realized in the DGFRS operation with the rotation of target and window foils irradiated by a continuous HI beam. Estimates show that radiative cooling in such conditions can be the most effective way of heat removal at the temperature of several hundred degrees. Such temperature can be reached on the surfaces of the target and window foils irradiated by HI beams at the intensity 1013 s-1.

  19. LOW-FIDELITY COVARIANCES FOR NEUTRON CROSS SECTIONS ON 57 STRUCTURAL AND 31 HEAVY NUCLEI IN THE FAST REGION.

    SciTech Connect

    PIGNI,M.T.; HERMAN, M.; OBLOZINSKY, P.

    2008-03-01

    We produced a large set of neutron cross section covariances in the energy range of 5 keV-20 MeV. The present set of data on 57 structural materials and 31 heavy nuclei follows our earlier work on 219 fission product materials and completes our extensive contribution to the low-fidelity covariance project (307 materials). This project aims to provide initial, low-fidelity yet consistent estimates of covariance data for nuclear criticality safety applications. The evaluation methodology combines the nuclear reaction model code EMPIRE which calculates sensitivity to nuclear reaction model parameters, and the Bayesian code KALMAN that propagates uncertainties of the model parameters to cross sections. Taking into account the large scale of the project, only marginal reference to experimental data was made. The covariances were derived from the perturbation of several key model parameters selected by the sensitivity analysis. These parameters refer to the optical model potential, the level densities and the strength of the pre-equilibrium emission. This work represents the first attempt ever to generate nuclear data covariances on such a large scale.

  20. LDEF (Postflight), AO178 : A High-Resolution Study of Ultra-heavy Cosmic-Ray Nuclei, Tray C11

    NASA Technical Reports Server (NTRS)

    1990-01-01

    LDEF (Postflight), AO178 : A High-Resolution Study of Ultra-heavy Cosmic-Ray Nuclei, Tray C11 EL-1994-00299 LDEF (Postflight), AO178 : A High-Resolution Study of Ultra-heavy Cosmic-Ray Nuclei, Tray C11 The postflight photograph of the Ultra Heavy Cosmic Ray Experiment (UHCRE) was taken in SAEF II at KSC after removal of the experiment tray from the LDEF. The experiment tray flanges appear discolored by a light brown stain. Outlines of experiment tray clamp blocks are faint but visible on the upper and lower experiment tray flanges.The experiment tray holding fixture hardware covers the clamp block areas on the end flanges. The UHCRE detectors were contained in 16 peripheral LDEF trays with at least one UHCRE tray located on each row of the LDEF except row 3, row 9 and row 12. Each tray contains three cylindrical aluminum pressure vessels with an integral aluminum support structure. Each cylinder is filled with an Eccofoam insert that houses 4 UHCRE detector stacks. Each stack consist of layers of Lexan polycarbonate sheets (approximately 70) interleaved with several thin sheets of lead. Forty-seven of the 48 pressure vessels were pressurized to 1.0 bar of a dry gas mixture (oxygen, nitrogen and helium) and sealed. One of the units was left unsealed in order to investigate the effects of the vacuum environment on the detector materials. Thermal control was accomplished by attaching an aluminized Kapton thermal cover on the tray bottom (the Kapton facing the LDEF interior), placing the aluminum cylinder support structure on thermal isolators and covering the experiment with a thin (5 mil) silvered TEFLON® thermal cover. The silvered TEFLON® cover was supported by an aluminum frame, an integral part of the experiment structure, and held in place by Velcro pads selectively located on the frame and on the back of the cover. The copper colored strip extending over the trays lower flange is a copper coated pressure sensitive tape used to provide an electrical ground

  1. Effect of three-body Coulomb interactions on the breakup of light nuclei in the field of a heavy ion: An asymptotic estimate

    SciTech Connect

    Alt, E.O.; Irgaziev, B.F.; Muminov, A.T.

    1995-11-01

    The quasielastic breakup of light nuclei into two charged fragments in the Coulomb field of a heavy multiply charged ion are studied. For fragments diverging with extremely low energies an asymptotic estimate is obtained for the ratio of the differential cross section in which three-body Coulomb effects are taken into account to that in which these effects are disregarded. It is shown that effects due to the acceleration of breakup fragments in the field of the heavy ion are significant. 13 refs., 2 figs.

  2. Upturn in the ratios of nuclei of Z=16-24 and abundant heavy nuclei to iron as observed in the ATIC experiment above 50 GeV/n and the Local Bubble

    NASA Astrophysics Data System (ADS)

    Panov, Alexander; Zatsepin, Victor; Sokolskaya, Natalia

    The ratios of heavy nuclei from sulfur (Z=16) to chromium (Z=24) fluxes and abundant heavy nuclei fluxes to the flux of iron were measured recently in the ATIC-2 experiment. These ratios are decreasing functions of energy from 5 GeV/n to approximately 30-50 GeV/n as expected. However, an unexpected sharp upturn in the ratios is observed above energies 30-50 GeV/n with high statistical significance and methodical reliability. Some details of the data are presented and discussed. Such a phenomenon could not be understood within usual uniform propagation models. A possible origin of the upturn is discussed and it is demonstrated that it can be explained as a propagation effect within a model of `closed galaxy with an embedded Local Bubble'. Moreover it is shown that a universal upturn at energies 200-300 GeV/n in the spectra of abundant even primary nuclei observed previously in the ATIC, CREAM and PAMELA experiments is also predicted by this model.

  3. [Results of measuring the charge and energy spectra of heavy nuclei on board the artificial Earth satellite Kosmos-936].

    PubMed

    Dashin, S A; Marennyĭ, A M; Gertsen, G P

    1982-01-01

    The measurements were performed using a package of dielectric track detectors mounted behind the shield of 60-80 kg.m-2 thick. The charge of nuclei was determined from the complete track length. As a result, 1915 tracks of nuclei with Z greater than or equal to 6 in the energy range 100-450 MeV/nuclon were detected and identified. The differential charge spectrum of nuclei with 6 less than or equal to Z less than or equal to 28 and the energy spectrum of nuclei of the iron group were built. For iron nuclei the following ration of isotope groups was obtained: (Fe52 + Fe53 + Fe54): (Fe55 + Fe56 + Fe57) : (Fe58 + Fe59 + Fe60) = (0.30 +/- 0.08) = (0.49 +/- 0.10) : (0.21 +/- 0.05).

  4. Photon scattering on /sup 238/U and the interpretation of near-threshold photofission resonances

    SciTech Connect

    Birenbaum, Y.; Alarcon, R.; Hoblit, S.D.; Laszewski, R.M.; Nathan, A.M.

    1987-10-01

    Cross sections for photon elastic scattering have been measured for /sup 238/U between 4.8 and 6.4 MeV with an energy resolution of about 50 keV. These data have been used along with existing photofission data to infer the total photoabsorption cross section sigma/sub T/ and the fission transmission coefficient T/sub f/ below neutron threshold. We find that the inferred sigma/sub T/ varies smoothly with energy and generally follows the extrapolated tail of the giant dipole resonance, and that T/sub f/ shows a broad bump between 5.6 and 5.9 MeV. These results strongly support the contention that resonances seen in near-threshold photofission cross sections are due to the fission and not the photon channel .

  5. Decay of heavy particles from Z = 125 superheavy nuclei in the region A = 295-325 using different versions of proximity potential

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Sukumaran, Indu

    Within the framework of Coulomb and proximity potential model (CPPM), the probable heavy particle decays from various isotopes of superheavy nuclei (SHN), Z = 125, within the range A = 295-325 have been studied using two versions of proximity potential; proximity 1977 and proximity 2000. The decay half lives evaluated using proximity 2000 is observed to be higher than the values obtained using proximity 1977. The effect of surface deformation on the decay half lives is studied using Coulomb and proximity potential for deformed nuclei (CPPMDN). As a result of the inclusion of deformation (β2), the penetrability of the decays are observed to be increased and accordingly the decay half lives are reduced. The estimated values are compared with other theoretical models, Universal curve (UNIV), Universal Decay law (UDL) and the scaling law of Horoi. The odd-even staggering (OES) effect is observed in the emission of odd mass clusters. An intriguing aspect of the study is the effect of the magicity at N = 184 which is confirmed from the plot of log10T1/2 against the neutron number of the daughter nuclei. Almost all the predicted half lives are favorable for experimental measurements. The Geiger-Nuttall (GN) plots and the Universal curve have been studied for various cluster emissions from various superheavy isotopes with Z = 125. Finally, the linearity of the GN plot and the Universal curve of the heavy particle emissions very well established the strength of CPPM.

  6. Persistent after-effects of heavy rain on concentrations of ice nuclei and rainfall suggest a biological cause

    NASA Astrophysics Data System (ADS)

    Bigg, E. K.; Soubeyrand, S.; Morris, C. E.

    2015-03-01

    Rainfall is one of the most important aspects of climate, but the extent to which atmospheric ice nuclei (IN) influence its formation, quantity, frequency, and location is not clear. Microorganisms and other biological particles are released following rainfall and have been shown to serve as efficient IN, in turn impacting cloud and precipitation formation. Here we investigated potential long-term effects of IN on rainfall frequency and quantity. Differences in IN concentrations and rainfall after and before days of large rainfall accumulation (i.e., key days) were calculated for measurements made over the past century in southeastern and southwestern Australia. Cumulative differences in IN concentrations and daily rainfall quantity and frequency as a function of days from a key day demonstrated statistically significant increasing logarithmic trends (R2 > 0.97). Based on observations that cumulative effects of rainfall persisted for about 20 days, we calculated cumulative differences for the entire sequence of key days at each site to create a historical record of how the differences changed with time. Comparison of pre-1960 and post-1960 sequences most commonly showed smaller rainfall totals in the post-1960 sequences, particularly in regions downwind from coal-fired power stations. This led us to explore the hypothesis that the increased leaf surface populations of IN-active bacteria due to rain led to a sustained but slowly diminishing increase in atmospheric concentrations of IN that could potentially initiate or augment rainfall. This hypothesis is supported by previous research showing that leaf surface populations of the ice-nucleating bacterium Pseudomonas syringae increased by orders of magnitude after heavy rain and that microorganisms become airborne during and after rain in a forest ecosystem. At the sites studied in this work, aerosols that could have initiated rain from sources unrelated to previous rainfall events (such as power stations) would

  7. Feasibility study of fissile mass quantification by photofission delayed gamma rays in radioactive waste packages using MCNPX

    NASA Astrophysics Data System (ADS)

    Simon, Eric; Jallu, Fanny; Pérot, Bertrand; Plumeri, Stéphane

    2016-12-01

    The feasibility of fissile mass quantification in large, long-lived medium activity radioactive waste packages using photofission delayed gamma rays has been assessed with MCNPX. The detection limit achievable is lower than the expected uranium mass in these waste packages, but the important sensibility to the waste matrix density and sample localization imposes to get an accurate measurement of these parameters. An isotope discrimination method based on gamma-ray ratios has been evaluated showing that photofission delayed gamma rays can be used to measure the fissile mass as well as the total uranium mass.

  8. Survivability and Fusability in Reactions Leading to Heavy Nuclei in the Vicinity of the N = 126 Closed Shell

    SciTech Connect

    Sagaidak, Roman N.

    2009-08-26

    The macroscopic component of fission barriers for Po to Th nuclei around the N = 126 closed neutron shell has been derived within the framework of the analysis of available fission and evaporation residues excitation functions using the conventional barrier passing (fusion) model coupled with the standard statistical model and compared with the predictions of various theoretical models.

  9. Photodisintegrated gamma rays and neutrinos from heavy nuclei in the gamma-ray burst jet of GRB 130427A

    NASA Astrophysics Data System (ADS)

    Joshi, Jagdish C.; Razzaque, Soebur; Moharana, Reetanjali

    2016-05-01

    Detection of ˜0.1-70 GeV prompt γ-ray emission from the exceptionally bright gamma-ray burst (GRB) 130427A by the Fermi-Large Area Telescope provides an opportunity to explore the physical processes of GeV γ-ray emission from the GRB jets. In this work, we discuss interactions of Iron and Oxygen nuclei with observed keV-MeV photons in the jet of GRB 130427A in order to explain an additional, hard spectral component observed during 11.5-33 s after trigger. The photodisintegration time-scale for Iron nuclei is comparable to or shorter than this duration. We find that γ rays resulting from the Iron nuclei disintegration can account for the hard power-law component of the spectra in the ˜1-70 GeV range, before the γγ → e± pair production with low-energy photons severely attenuates emission of higher energy photons. Electron antineutrinos from the secondary neutron decay, on the other hand, can be emitted with energies up to ˜2 TeV. The flux of these neutrinos is low and consistent with non-detection of GRB 130427A by the IceCube Neutrino Observatory. The required total energy in the Iron nuclei for this hadronic model for GeV emission is ≲10 times the observed total energy released in the prompt keV-MeV emission.

  10. Calculated fission properties of the heaviest elements: Vol. 2, Calculated single-particle levels in heavy nuclei

    SciTech Connect

    Moeller, P.; Nix, J.R.; Swiatecki, W.

    1986-09-01

    The decay properties of nuclei in many cases depend strongly on the quantum numbers of the single-particle levels in the vicinity of the Fermi surface. A striking illustration is the prolonged fission half-lives of odd nuclei relative to their even neighbors. The hindrance factor depends on the spin of unpaired odd particle and increases with increasing spin of the odd particle. The effect has been studied theoretically. For /sup 257/Fm the hindrance factor is almost ten orders of magnitude. The computer code for calculating nuclear masses calculates single-particle levels at the deformations considered as one step in the calculations. This code has been run for all nuclei considered in the 1981 mass study and the calculated single-particle levels were stored on permanent mass storage. This is actually point (I.D.1) in the research plan ('UNIFIED MODEL ...'). A computer code has been constructed for extracting levels of nuclei that are specified to the program and plotting them. Four such plots are included in this report as figs. 1-4. The levels are plotted relative to the Fermi surface of each nucleus. It is clear from the pictures that for /sup 257/Fm the calculations predict the N = 157 neutron orbital to have spin 9/2+ as is also found experimentally. The high spin is the reason for the large hindrance factor for fission of /sup 257/Fm. Figures of the type included here may be used to quickly survey larger regions of nuclei for candidates for special properties, such as unusually large hindrance factors in fission. More detailed calculations are usually required to determine the magnitude of the effects. We also include tables of the plotted single-particle levels since it is not always possible to determine the spin from an inspection of the plots, when levels are overlapping. 4 figs.

  11. Decay chains and photofission investigation based on nuclear spectroscopy of highly enriched uranium sample.

    PubMed

    Sibczynski, P; Kownacki, J; Syntfeld-Kazuch, A; Moszynski, M; Kisielinski, M; Czarnacki, W; Kosinski, K; Matusiak, M; Klimasz, M; Kowalczyk, M; Abraham, T; Mierzejewski, J; Srebrny, J

    2013-12-01

    Nuclear spectroscopy experiments were performed for 100g metallic uranium rod enriched to 93% (235)U, in order to establish and characterize the most prominent γ-rays in the natural decay series and photofission reaction. Single γ-ray spectra and γ-γ coincidences measurements were conducted before irradiation. The uranium sample was subsequently irradiated with 15 MeV bremsstrahlung photons. Relative intensities of γ-lines and several values of half-lives of the fission fragments decays were determined. The obtained information can be utilized in detection of smuggled nuclear materials and characterization of bulky nuclear waste packages. © 2013 Elsevier Ltd. All rights reserved.

  12. NUCLEAR AND HEAVY ION PHYSICS: α-decay half-lives of superheavy nuclei and general predictions

    NASA Astrophysics Data System (ADS)

    Dong, Jian-Min; Zhang, Hong-Fei; Wang, Yan-Zhao; Zuo, Wei; Su, Xin-Ning; Li, Jun-Qing

    2009-08-01

    The generalized liquid drop model (GLDM) and the cluster model have been employed to calculate the α-decay half-lives of superheavy nuclei (SHN) using the experimental α-decay Q values. The results of the cluster model are slightly poorer than those from the GLDM if experimental Q values are used. The prediction powers of these two models with theoretical Q values from Audi et al. (QAudi) and Muntian et al. (QM) have been tested to find that the cluster model with QAudi and QM could provide reliable results for Z > 112 but the GLDM with QAudi for Z <= 112. The half-lives of some still unknown nuclei are predicted by these two models and these results may be useful for future experimental assignment and identification.

  13. Charge composition of high energy heavy primary cosmic ray nuclei. Ph.D. Thesis - Catholic Univ. of Am.

    NASA Technical Reports Server (NTRS)

    Price, R. D.

    1974-01-01

    A detailed study of the charge composition of primary cosmic radiation for about 5000 charged nuclei from neon to iron with energies greater than 1.16 GeV/nucleon is presented. Values are obtained after corrections were made for detector dependences, atmospheric attenuation, and solar modulation. New values of 38.5, 32.4, 23.7, and 16.8 g/sq cm for the attenuation mean free paths in air for the same charge groups are presented.

  14. A Measurement of Charged and Neutral Elementary Particles Emitted from Antiproton Annihilation at Rest in Heavy Nuclei

    DTIC Science & Technology

    1989-06-15

    1991 SUMMARY Yields and ,nergy spectra of nuclear fragments and mesons emitted from antiproton crnihilation at rest in carbon, bismuth and uranium...anti- proton annihilation at rest in nuclei (carbon and uranium). These particles include (charged) pions, kaons, protons, light nuclear fragments ...included in order to demonstrate as discussed in [10], and escape of excess neutral pions the effect of pion absorption in the nuclear environment , due to

  15. The Experimental and Calculated Total γ-RAY Spectra and Population of Levels up to 3 Mev of Heavy Nuclei

    NASA Astrophysics Data System (ADS)

    Khitrov, V. A.; Sukhovoj, A. M.; Grigoriev, E. P.

    2003-06-01

    Comparison between the experimental and calculated with the parameters [1] spectra demonstrates more or less improvement of their correspondence (up to practical coincidence) for the 114Cd, 158Gd, 166Ho, 168Er, 182Ta, 196Pt, 198Au, and 200Hg compound nuclei and some exceeding of the calculated intensity for 150Sm, 156Gd, 160Tb, 164Dy, 176Lu, and 192Ir at the γ-transition energy Eγ > 3 - 4 MeV.

  16. Accessing transverse nucleon and gluon distributions in heavy nuclei using coherent vector meson photoproduction at high energies in ion ultraperipheral collisions

    NASA Astrophysics Data System (ADS)

    Guzey, V.; Strikman, M.; Zhalov, M.

    2017-02-01

    By using the theoretical approaches that describe well the available data on t -integrated coherent photoproduction of light and heavy vector mesons in Pb-Pb ultraperipheral collisions (UPCs) at the Large Hadron Collider (LHC) in Run 1, we calculate the momentum transfer distributions for this process for ρ and J /ψ vector mesons in the kinematics of Run 2 at the LHC. We demonstrate that nuclear shadowing not only suppresses the absolute value of the cross sections but also shifts the momentum transfer distributions toward smaller values of the momentum transfer |t | . This result can be interpreted as a broadening in the impact parameter space of the effective nucleon density in nuclei by 14% in the case of ρ and the nuclear gluon distribution by 5%-11% in the case of J /ψ .

  17. Strongly Enhanced Low Energy α-Particle Decay in Heavy Actinide Nuclei and Long-Lived Superdeformed and Hyperdeformed Isomeric States

    NASA Astrophysics Data System (ADS)

    Marinov, A.; Gelberg, S.; Kolb, D.; Weil, J. L.

    Unidentified low energy and very enhanced α-particle groups have been observed in various actinide fractions produced via secondary reactions in a CERN W target which had been irradiated with 24-GeV protons. In particular, 5.14, 5.27 and 5.53 MeV α-particle groups with corresponding half-lives of 3.8+/-1.0 y, 625+/-84 d and 26+/-7d, have been seen in Bk, Es and Lr-No sources, respectively. The measured energies are a few MeV lower than the known ground state to ground state α-decays in the corresponding neutron-deficient actinide nuclei. The half-lives are 104 to 107 shorter than expected from energy versus lifetime relationship for such low-energy α-particles in this region of nuclei. The deduced evaporation residue cross sections are in the mb region, about 104 times higher than expected. Not only is it impossible to identify these α-decays with any known activity in the whole nuclear chart, but they also could not be due to hypothetically unknown isomeric states in various conceivable neutron deficient nuclei, nor due to unknown isomeric states in the rare-earth region. Based on the fact that in other experiments we have found isomeric states in the second and third minima of the potential for other heavy ion reaction products, one can now understand in a quantitative way, both the unusual low energies, the unusual enhanced lifetimes and the unusual large production cross sections, in terms of production of similar isomeric states in appropriate actinide isotopes. Some consequences regarding the production of the long-lived superheavy elements are also discussed.

  18. Analyzing velocity map images to distinguish the primary methyl photofragments from those produced upon C-Cl bond photofission in chloroacetone at 193 nm

    SciTech Connect

    Alligood, Bridget W.; Straus, Daniel B.; Butler, Laurie J.

    2011-07-21

    We use a combination of crossed laser-molecular beam scattering experiments and velocity map imaging experiments to investigate the three primary photodissociation channels of chloroacetone at 193 nm: C-Cl bond photofission yielding CH{sub 3}C(O)CH{sub 2} radicals, C-C bond photofission yielding CH{sub 3}CO and CH{sub 2}Cl products, and C-CH{sub 3} bond photofission resulting in CH{sub 3} and C(O)CH{sub 2}Cl products. Improved analysis of data previously reported by our group quantitatively identifies the contribution of this latter photodissociation channel. We introduce a forward convolution procedure to identify the portion of the signal, derived from the methyl image, which results from a two-step process in which C-Cl bond photofission is followed by the dissociation of the vibrationally excited CH{sub 3}C(O)CH{sub 2} radicals to CH{sub 3}+ COCH{sub 2}. Subtracting this from the total methyl signal identifies the methyl photofragments that result from the CH{sub 3}+ C(O)CH{sub 2}Cl photofission channel. We find that about 89% of the chloroacetone molecules undergo C-Cl bond photofission to yield CH{sub 3}C(O)CH{sub 2} and Cl products; approximately 8% result in C-C bond photofission to yield CH{sub 3}CO and CH{sub 2}Cl products, and the remaining 2.6% undergo C-CH{sub 3} bond photofission to yield CH{sub 3} and C(O)CH{sub 2}Cl products.

  19. Impact of new data for neutron-rich heavy nuclei on theoretical models for r-process nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Kajino, Toshitaka; Mathews, Grant J.

    2017-08-01

    Current models for the r process are summarized with an emphasis on the key constraints from both nuclear physics measurements and astronomical observations. In particular, we analyze the importance of nuclear physics input such as beta-decay rates; nuclear masses; neutron-capture cross sections; beta-delayed neutron emission; probability of spontaneous fission, beta- and neutron-induced fission, fission fragment mass distributions; neutrino-induced reaction cross sections, etc. We highlight the effects on models for r-process nucleosynthesis of newly measured β-decay half-lives, masses, and spectroscopy of neutron-rich nuclei near the r-process path. We overview r-process nucleosynthesis in the neutrino driven wind above the proto-neutron star in core collapse supernovae along with the possibility of magneto-hydrodynamic jets from rotating supernova explosion models. We also consider the possibility of neutron star mergers as an r-process environment. A key outcome of newly measured nuclear properties far from stability is the degree of shell quenching for neutron rich isotopes near the closed neutron shells. This leads to important constraints on the sites for r-process nucleosynthesis in which freezeout occurs on a rapid timescale.

  20. Investigation of the relative abundance of heavy versus light nuclei in primary cosmic rays using underground muon bundles

    SciTech Connect

    Sundaralingam, Nakamuthu

    1993-06-08

    We study multiple muon events (muon bundles) recorded underground at a depth of 2090 mwe. To penetrate to this depth, the muons must have energies above 0.8 TeV at the Earth`s surface; the primary cosmic ray nuclei which give rise to the observed muon bundles have energies at incidence upon the upper atmosphere of 10 to 105TeV. The events are detected using the Soudan 2 experiment`s fine grained tracking calorimeter which is surrounded by a 14 m x 10 m x 31 m proportional tube array (the ``active shield``). Muon bundles which have at least one muon traversing the calorimeter, are reconstructed using tracks in the calorimeter together with hit patterns in the proportional tube shield. All ionization pulses are required to be coincident within 3 microseconds. A goal of this study is to investigate the relative nuclear abundances in the primary cosmic radiation around the ``knee`` region (103 - 104 TeV) of the incident energy spectrum. Four models for the nuclear composition of cosmic rays are considered: The Linsley model, the Constant Mass Composition model (CMC), the Maryland model and the Proton-poor model. A Monte Carlo which incorporates one model at a time is used to simulate events which are then reconstructed using the same computer algorithms that are used for the data. Identical cuts and selections are applied to the data and to the simulated events.

  1. Impact of new data for neutron-rich heavy nuclei on theoretical models for r-process nucleosynthesis.

    PubMed

    Kajino, Toshitaka; Mathews, Grant J

    2017-08-01

    Current models for the r process are summarized with an emphasis on the key constraints from both nuclear physics measurements and astronomical observations. In particular, we analyze the importance of nuclear physics input such as beta-decay rates; nuclear masses; neutron-capture cross sections; beta-delayed neutron emission; probability of spontaneous fission, beta- and neutron-induced fission, fission fragment mass distributions; neutrino-induced reaction cross sections, etc. We highlight the effects on models for r-process nucleosynthesis of newly measured β-decay half-lives, masses, and spectroscopy of neutron-rich nuclei near the r-process path. We overview r-process nucleosynthesis in the neutrino driven wind above the proto-neutron star in core collapse supernovae along with the possibility of magneto-hydrodynamic jets from rotating supernova explosion models. We also consider the possibility of neutron star mergers as an r-process environment. A key outcome of newly measured nuclear properties far from stability is the degree of shell quenching for neutron rich isotopes near the closed neutron shells. This leads to important constraints on the sites for r-process nucleosynthesis in which freezeout occurs on a rapid timescale.

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

    SciTech Connect

    Akram, W.; Schönbächler, M.; Sprung, P.; Vogel, N.

    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.

  3. ARIEL e-linac. Electron linear accelerator for photo-fission

    NASA Astrophysics Data System (ADS)

    Koscielniak, Shane

    2014-01-01

    The design and implementation of a 1/2 MW beam power electron linear accelerator (e-linac) for the production of rare isotope beams (RIB) via photo-fission in the context of the Advanced Rare IsotopE Laboratory, ARIEL (Koscielniak et al. 2008; Merminga et al. 2011; Dilling et al., Hyperfine Interact, 2013), is described. The 100 % duty factor e-linac is based on super-conducting radiofrequency (SRF) technology at 1.3 GHz and has a nominal energy of 50 MeV. This paper provides an overview of the accelerator major components including the gun, cryomodules and cryoplant, high power RF sources, and machine layout including beam lines. Design features to facilitate operation of the linac as a Recirculating Linear Accelerator (RLA) for various applications, including Free Electron Lasers, are also noted.

  4. Photoneutron and Photofission Cross Sections for URANIUM-238 and THORIUM-232 Using Neutron Capture Gamma Rays.

    NASA Astrophysics Data System (ADS)

    Varhue, Walter John

    The photofission and total photoneutron cross sections of ('238)U and ('232)Th have been measured as a function of energy between 4 and 11 Mev. The photons used were those produced in the neutron capture reaction in the Tangential Beam Port Facility of the University of Virginia Reactor. The capture gamma ray sources used were the following; Al, Cr, Co, Cu, Fe, Ni, S, and Ti. A computer code was used to calculate the spectrum of each capture gamma ray beam used in the irradiations. This calculation accounted for the attenuation in the beam and the contribution from neutron capture in Al and H. A second code iteratively solved for the best fit cross section curve for the experimentally obtained yield data. In the total photoneutron measurement, the neutrons were counted with a Halpern type detector containing 4 BF(,3) tubes. The intensity of the beam was determined with LiF thermoluminescent dosimeters. The results agree very well with those of previous studies. In the photofission measurement, fission fragments were counted in Lexan polycarbonate, a solid state nuclear track detector. The efficiency of this counting system has been determined analytically as a function of energy with the aid of published experimental measurements of the angular distribution of fission fragments and the etching properties of Lexan. In general the technique has proved to be successful in producing differential photonuclear cross section results. Resolution of the unfolding technique is limited by the density of principal gamma ray lines available from the capture targets. An obvious improvement would be the use of more capture targets. The results and conclusions of previous studies using neutron capture gamma rays have been placed in doubt due to the nature of calculations used to obtain cross values.

  5. Cross section systematics for the lightest Bi and Po nuclei produced in complete fusion reactions with heavy ions

    SciTech Connect

    Andreyev, A.N.; Ackermann, D.; Muenzenberg, G.; Antalic, S.; Saro, S.; Streicher, B.; Darby, I.G.; Page, R.D.; Wiseman, D.R.; Franchoo, S.; Hessberger, F.P.; Kuusiniemi, P.; Lommel, B.; Kindler, B.; Mann, R.; Sulignano, B.; Hofmann, S.; Huyse, M.; Vel, K. van de; Duppen, P. van

    2005-07-01

    The production of the very neutron-deficient nuclides {sup 184-192}Bi and {sup 186-192}Po in the vicinity of the neutron midshell at N = 104 has been studied by using heavy-ion-induced complete fusion reactions in a series of experiments at the velocity filter SHIP. The cross sections for the xn and pxn evaporation channels of the {sup 46}Ti+{sup 144}Sm{yields}{sup 190}Po*,{sup 98}Mo+{sup 92}Mo{yields}{sup 190}Po*,{sup 50,52}Cr+{sup 142}Nd{yields}{sup 192,194}Po*, and {sup 94,95}Mo+{sup 93}Nb{yields}{sup 187,188}Bi* reactions were measured. The results obtained, together with the previously known cross section data for the heavier Bi and Po nuclides, are compared with the results of statistical model calculations carried out with the HIVAP code. It is shown that a satisfactory description of the experimental data requires a significant (up to 35%) reduction of the theoretical fission barriers. The optimal reactions for production of the lightest Bi and Po isotopes are discussed.

  6. Time delays in heavy-ion-induced fission of medium-Z nuclei, measured by crystal blocking

    SciTech Connect

    Andersen, J. U.; Chevallier, J.; Forster, J. S.; Karamian, S. A.; Vane, C Randy; Beene, James R; Gross, Carl J; Krause, Herbert F; Liang, J Felix; Shapira, Dan; Uguzzoni, A.

    2012-01-01

    Time delays in fission induced by bombardment of Mo with 170- and 180-MeV {sup 32}S, 225- and 240-MeV {sup 48}Ti, and 300-MeV {sup 58}Ni have been measured by observation of crystal blocking of fission fragments. In contrast to earlier measurements with a W target, the results are consistent with fission of a compound nucleus in competition with mainly neutron emission. Most of the fissions happen on a time scale much shorter than attoseconds but there is a significant component of fission with much longer lifetimes. The measurements are reproduced with a standard statistical model, including a Kramers correction to fission widths from the viscosity of hot nuclear matter. These new results support the interpretation of our earlier measurements with a W target, which indicate that there is a transition in heavy-ion-induced fission at large atomic number and mass, from multichance fission in the standard Bohr-Wheeler picture to fission without formation of a compound nucleus. The process is slowed down by nuclear viscosity, with measured delays of order attoseconds.

  7. Korteweg-de Vries-Burgers equation in a multi-component magnetized plasma with nuclei of heavy elements

    NASA Astrophysics Data System (ADS)

    Hosen, B.; Amina, M.; Mamun, A. A.; Hossen, M. R.

    2016-12-01

    The nonlinear properties of ion-acoustic (IA) waves are investigated in a relativistically degenerate magnetized quantum plasma, whose constituents are non-degenerate inertial ions, degenerate electrons and immobile positively-charged heavy elements. For nonlinear studies, the well-known reductive perturbation technique is employed to derive the Korteweg-de Vries-Burger equation in the presence of relativistically degenerate electrons. Numerically, the amplitude, width, and phase speed are shown to be associated with the localized IA solitons, and shocks are shown to be significantly influenced by the various intrinsic parameters relevant to our model. The solitary and the shock wave properties have been to be influenced in the non-relativistic, as well as the ultrarelativistic, limits. The effects of the external magnetic field and the obliqueness are found to change the basic properties of IA waves significantly. The present analysis can be useful in understanding the collective process in dense astrophysical environments, like there of non-rotating white dwarfs, neutron stars, etc.

  8. Measurement of elliptic flow of light nuclei at √{sN N}=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, X. M.; Sun, Z.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, Y.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, F.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, H.; Xu, Z.; Xu, J.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Yang, Y.; Yang, S.; Yang, C.; Yang, Y.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, Y.; Zhang, X. P.; Zhang, Z.; Zhang, J. B.; Zhang, S.; Zhang, S.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2016-09-01

    We present measurements of second-order azimuthal anisotropy (v2) at midrapidity (|y |<1.0 ) for light nuclei d ,t ,3He (for √{sN N}=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei d ¯ (√{sN N}=200 , 62.4, 39, 27, and 19.6 GeV) and ¯3He (√{sN N}=200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v2 for these light nuclei produced in heavy-ion collisions is compared with those for p and p ¯. We observe mass ordering in nuclei v2(pT) at low transverse momenta (pT<2.0 GeV/c ). We also find a centrality dependence of v2 for d and d ¯. The magnitude of v2 for t and 3He agree within statistical errors. Light-nuclei v2 are compared with predictions from a blast-wave model. Atomic mass number (A ) scaling of light-nuclei v2(pT) seems to hold for pT/A <1.5 GeV /c . Results on light-nuclei v2 from a transport-plus-coalescence model are consistent with the experimental measurements.

  9. Measurement of elliptic flow of light nuclei at sNN=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

    DOE PAGES

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; ...

    2016-09-23

    Here we present measurements of second-order azimuthal anisotropy ( v2 ) at midrapidity ( |y| < 1.0 ) for light nuclei d , t , 3He (formore » $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei$$\\bar{d}$$ ( $$\\sqrt{s}$$$_{NN}$$ = 200 , 62.4, 39, 27, and 19.6 GeV) and 3 ¯¯¯¯¯ He ( $$\\sqrt{s}$$$_{NN}$$ = 200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v2 for these light nuclei produced in heavy-ion collisions is compared with those for p and $$\\bar{p}$$. We observe mass ordering in nuclei v2 ( pT) at low transverse momenta ( pT < 2.0 GeV/c). We also find a centrality dependence of v2 for d and $$\\bar{d}$$ . The magnitude of v2 for t and 3He agree within statistical errors. Light-nuclei v2 are compared with predictions from a blast-wave model. Atomic mass number ( A ) scaling of light-nuclei v2 (pT) seems to hold for pT / A < 1.5 GeV/c . Results on light-nuclei v2 from a transport-plus-coalescence model are consistent with the experimental measurements.« less

  10. Effects of T-odd asymmetry of the emission of light charged particles and photons during fission of heavy nuclei by polarized neutrons

    SciTech Connect

    Gagarskii, A. M.; Guseva, I. S.; Goennenwein, F.; Kopach, Yu. N.; Mutterer, M.; Kuz'mina, T. E.; Petrov, G. A.; Tyurin, G.; Nesvizhevsky, V.

    2011-12-15

    The new physical effects of T-odd asymmetry of the emission of light charged particles (LCPs) during the ternary fission of some heavy nuclei by cold polarized neutrons have been experimentally studied. The coefficients of triple scalar and vector correlation of the pulses of light particles and fission fragments (TRI effect) and the fivefold correlation of the same vectors (ROT effect) have been measured. These effects are believed to be caused by the rotation of polarized fissioning system around its polarization direction. The treatment of the experimental data for LCPs in the framework of this hypothesis leads to a good agreement between the calculation results and experimental data. The calculated value of the angle of rotation of the fission axis in the ternary fission of the polarized fissioning {sup 236}U* compound nucleus was used to process the results of measuring the ROT effect for {gamma} photons from binary-fission fragments of the same nucleus. A satisfactory description of these experimental data is obtained which serves a convincing confirmation of the rotation hypothesis.

  11. Photo-fission Product Yield Measurements at Eγ=13 MeV on 235U, 238U, and 239Pu

    NASA Astrophysics Data System (ADS)

    Tornow, W.; Bhike, M.; Finch, S. W.; Krishichayan, Fnu; Tonchev, A. P.

    2016-09-01

    We have measured Fission Product Yields (FPYs) in photo-fission of 235U, 238U, and 239Pu at TUNL's High-Intensity Gamma-ray Source (HI γS) using mono-energetic photons of Eγ = 13 MeV. Details of the experimental setup and analysis procedures will be discussed. Yields for approximately 20 fission products were determined. They are compared to neutron-induced FPYs of the same actinides at the equivalent excitation energies of the compound nuclear systems. In the future photo-fission data will be taken at Eγ = 8 . 0 and 10.5 MeV to find out whether photo-fission exhibits the same so far unexplained dependence of certain FPYs on the energy of the incident probe, as recently observed in neutron-induced fission, for example, for the important fission product 147Nd. Work supported by the U. S. Dept. of Energy, under Grant No. DE-FG02-97ER41033, and by the NNSA, Stewardship Science Academic Alliances Program, Grant No. DE-NA0001838 and the Lawrence Livermore, National Security, LLC under Contract No. DE-AC52-07NA27344.

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

    NASA Astrophysics Data System (ADS)

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

    2008-08-01

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

  13. Ultra Heavy Ion Collector (UHIC)

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1997-01-01

    The purpose of this final report is to study the propagation of heavy nuclei in cosmic radiation. Topics include: Mass Distributions of Fragments from the Interactions of 600 MeV/n Silver Nuclei; Charge-pickup by Heavy Relativistic Nuclei; Fragmentation and Propagation Heavy UH Cosmic Ray Nuclei; Nuclear Fragmentation Parameters Needed for Interpretation of Observed Fluxes of UH Cosmic Ray Nuclei; Fragmentation and Electromagnetic Dissociation of 10.6 GeV/nucleon (197) Au Nuclei; Nuclear Interaction Cross Sections for UltraHeavy Nuclei; The Charge-Changing Fragmentation of 10.6 GeV/nucleon 197 Au Nuclei; Fragmentation Cross Sections of Relativistic 84/36 Kr and 109/47 Ag Nuclei in Targets from Hydrogen to Lead; Mission Concept for the Study of Ultraheavy Galactic Cosmic Rays; and Propagation of the Heaviest UH - Cosmic Ray Nuclei.

  14. Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

    NASA Astrophysics Data System (ADS)

    Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Davila, Jesus; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio

    2015-07-01

    During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e'n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides 232Th, 238U and 237Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

  15. Th and U fuel photofission study by NTD for AD-MSR subcritical assembly

    SciTech Connect

    Sajo-Bohus, Laszlo; Greaves, Eduardo D.; Barros, Haydn; Pino, Felix; Barrera, Maria T.; Farina, Fulvio; Davila, Jesus

    2015-07-23

    During the last decade a considerable effort has been devoted for developing energy generating systems based on advanced nuclear technology within the design concepts of GEN-IV. Thorium base fuel systems such as accelerator driven nuclear reactors are one of the often mentioned attractive and affordable options. Several radiotherapy linear accelerators are on the market and due to their reliability, they could be employed as drivers for subcritical liquid fuel assemblies. Bremsstrahlung photons with energies above 5.5MeV, induce (γ,n) and (e,e’n) reactions in the W-target. Resulting gamma radiation and photo or fission neutrons may be absorbed in target materials such as thorium and uranium isotopes to induce sustained fission or nuclear transmutation in waste radioactive materials. Relevant photo driven and photo-fission reaction cross sections are important for actinides {sup 232}Th, {sup 238}U and {sup 237}Np in the radiotherapy machines energy range of 10-20 MV. In this study we employ passive nuclear track detectors (NTD) to determine fission rates and neutron production rates with the aim to establish the feasibility for gamma and photo-neutron driven subcritical assemblies. To cope with these objectives a 20 MV radiotherapy machine has been employed with a mixed fuel target. Results will support further development for a subcritical assembly employing a thorium containing liquid fuel. It is expected that acquired technological knowledge will contribute to the Venezuelan nuclear energy program.

  16. The shapes of nuclei

    NASA Astrophysics Data System (ADS)

    Bertsch, G. F.

    Gerry Brown initiated some early studies on the coexistence of different nuclear shapes. The subject has continued to be of interest and is crucial for understanding nuclear fission. We now have a very good picture of the potential energy surface with respect to shape degrees of freedom in heavy nuclei, but the dynamics remain problematic. In contrast, the early studies on light nuclei were quite successful in describing the mixing between shapes. Perhaps a new approach in the spirit of the old calculations could better elucidate the character of the fission dynamics and explain phenomena that current theory does not model well.

  17. Spectroscopy of Neutron-rich Nuclei of the A{approx_equal}60 region populated through binary heavy-ion collisions

    SciTech Connect

    Lunardi, S.

    2008-11-11

    Neutron-rich nuclei of the mass A = 60 region (from V to Fe) have been studied through multi-nucleon transfer reactions by bombarding a {sup 238}U target with beams of {sup 64}Ni and {sup 70}Zn. Unambiguous identification of prompt {gamma} rays belonging to each nucleus has been achieved by using the efficient gamma-array CLARA coupled to the large-acceptance magnetic spectrometer PRISMA installed at the Legnaro National Laboratories. With the new data, the existence of the N = 32 sub-shell closure has been corroborated through the study of odd V isotopes, whereas a new region of deformation appears for neutron-rich Fe nuclei close to N = 40. The results obtained for all these nuclei are compared with shell model calculations which reproduces quite well the experimental data also for the most neutron-rich nuclei when excitations from the fp shell into the upper g{sub 9/2} orbital are allowed.

  18. High-power, photofission-inducing bremsstrahlung source for intense pulsed active detection of fissile material

    NASA Astrophysics Data System (ADS)

    Zier, J. C.; Mosher, D.; Allen, R. J.; Commisso, R. J.; Cooperstein, G.; Hinshelwood, D. D.; Jackson, S. L.; Murphy, D. P.; Ottinger, P. F.; Richardson, A. S.; Schumer, J. W.; Swanekamp, S. B.; Weber, B. V.

    2014-06-01

    Intense pulsed active detection (IPAD) is a promising technique for detecting fissile material to prevent the proliferation of special nuclear materials. With IPAD, fissions are induced in a brief, intense radiation burst and the resulting gamma ray or neutron signals are acquired during a short period of elevated signal-to-noise ratio. The 8 MV, 200 kA Mercury pulsed-power generator at the Naval Research Laboratory coupled to a high-power vacuum diode produces an intense 30 ns bremsstrahlung beam to study this approach. The work presented here reports on Mercury experiments designed to maximize the photofission yield in a depleted-uranium (DU) object in the bremsstrahlung far field by varying the anode-cathode (AK) diode gap spacing and by adding an inner-diameter-reducing insert in the outer conductor wall. An extensive suite of diagnostics was fielded to measure the bremsstrahlung beam and DU fission yield as functions of diode geometry. Delayed fission neutrons from the DU proved to be a valuable diagnostic for measuring bremsstrahlung photons above 5 MeV. The measurements are in broad agreement with particle-in-cell and Monte Carlo simulations of electron dynamics and radiation transport. These show that with increasing AK gap, electron losses to the insert and outer conductor wall increase and that the electron angles impacting the bremsstrahlung converter approach normal incidence. The diode conditions for maximum fission yield occur when the gap is large enough to produce electron angles close to normal, yet small enough to limit electron losses.

  19. Simulation of delayed γ-ray emission following photofission reactions induced by pulsed bremsstrahlung x-rays using MCNPX and experimental validation

    NASA Astrophysics Data System (ADS)

    Wen, Xianfei; Yang, Haori

    2016-12-01

    There is a great demand to develop non-destructive techniques to identify and quantify Special Nuclear Materials (SNM) in homeland security and nuclear safeguards applications. Passive assay could be extremely challenging in some scenarios. Active interrogation technique based on photofission has been identified as one of the promising approaches. In radiation detection system design based on such technique, it is highly desired to have abilities to accurately and efficiently simulate delayed γ-rays emitted from photofission reactions. In this work, simulation results were compared with measurement outcomes to demonstrate the capabilities and limitations of the code MCNPX 2.7.0 in the simulation of delayed γ-rays from photofission of uranium and plutonium samples. First, high-energy delayed γ-rays (Eγ 2.7-4.5 MeV) from photofission of 238U were simulated and validated against the energy spectra measured in between linac pulses. Second, low-energy delayed γ-ray spectra (Eγ 0.6-2.7 MeV) measured with a list-mode system after irradiation of 239Pu were used in the validation.

  20. Predictions for Superheavy Nuclei

    NASA Astrophysics Data System (ADS)

    Kumar, Krishna

    1990-01-01

    The Dynamic Deformation Model has been extended to the problem of fission in such a way that several thousand channels including particle-decay, α-decay, heavy-ion-emission, asymmetric fission, and symmetric fission can be taken into account. The model also includes a Kinetic Shell Correction which was ignored in previous predictions for Superheavy nuclei. This model is in better agreement with experimental life-times. A new location of the Superheavy peak is predicted at Z = 116 (eka-Polonium), A = 300, total half-life = 1079 years. New heavy-ion-fusion experiments and the means of identifying the Superheavy Elements are suggested.

  1. Comparison of yields of neutron-rich nuclei in proton- and photon-induced 238U fission

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    A comparative study of fission of actinides, especially 238U, by proton and bremsstrahlung photon is performed. The relative mass distribution of 238U fission fragments has been explored theoretically for both proton- and photon-induced fission. The integrated yield along with charge distribution of the products are calculated to find the neutron richness in comparison with the nuclei produced by the r process in nucleosynthesis. Some r -process nuclei in the intermediate-mass range for symmetric fission mode are found to be produced almost two orders of magnitude more for proton-induced fission than for photofission, although the rest of the neutron-rich nuclei in the asymmetric mode are produced in comparable proportion for both processes.

  2. Heavy elements and mixing in red giants

    NASA Astrophysics Data System (ADS)

    Smith, Verne V.

    A brief overview of the s-process in red giants is presented, followed by discussions of three specific topics involving heavy-element s-process nucleosynthesis and mixing in red giants: (1) a comparison of neutron densities derived from observations and from the most recent stellar models, (2) how observations of technetium in S stars have led to a natural division of these stars into two separate groups, one of which is the result of single-star stellar evolution while the other is the result of mass transfer in a binary system, (3) a brief discussion of the recent speculative suggestion that gamma-ray induced photofission of heavy elements (Th and U) might be a source of the Tc observed in certain types of red giants.

  3. Tests of a novel method to assay SNM using polarized photofission and its sensitivity in the presence of shielding

    NASA Astrophysics Data System (ADS)

    Mueller, J. M.; Ahmed, M. W.; Kafkarkou, A.; Kendellen, D. P.; Sikora, M. H.; Spraker, M. C.; Weller, H. R.; Zimmerman, W. R.

    2015-03-01

    A novel method to identify Special Nuclear Material was recently developed (Mueller et al., 2014) [1]. This method relies upon using a linearly polarized γ-ray beam to induce photofission of a sample and then comparing the prompt fission neutron yields in and out of the plane of beam polarization. The present paper will describe experimental tests of this new technique and assess its sensitivity in the presence of shielding. The capability of this technique to measure the enrichment of uranium was tested by using combinations of thin 235U and 238U foils of known enrichments. The sensitivity of this assay to shielding by lead, steel, and polyethylene was experimentally measured and simulated using GEANT4. These tests show that the measured asymmetry can indeed be used to determine the enrichment of materials composed of an admixture of 235U and 238U, and this asymmetry is relatively insensitive to moderate amounts of shielding.

  4. D mesic nuclei

    NASA Astrophysics Data System (ADS)

    García-Recio, C.; Nieves, J.; Tolos, L.

    2010-06-01

    The energies and widths of several D0 meson bound states for different nuclei are obtained using a D-meson selfenergy in the nuclear medium, which is evaluated in a selfconsistent manner using techniques of unitarized coupled-channel theory. The kernel of the meson-baryon interaction is based on a model that treats heavy pseudoscalar and heavy vector mesons on equal footing, as required by heavy quark symmetry. We find D0 bound states in all studied nuclei, from 12C up to 208Pb. The inclusion of vector mesons is the keystone for obtaining an attractive D-nucleus interaction that leads to the existence of D0-nucleus bound states, as compared to previous studies based on SU(4) flavor symmetry. In some cases, the half widths are smaller than the separation of the levels, what makes possible their experimental observation by means of a nuclear reaction. This can be of particular interest for the future P¯ANDA@FAIR physics program. We also find a D+ bound state in 12C, but it is too broad and will have a significant overlap with the energies of the continuum.

  5. Superdeformed nuclei

    SciTech Connect

    Janssens, R.V.F.; Khoo, Teng Lek.

    1991-01-01

    This paper reviews the most recent advances in the understanding of the physics of superdeformed nuclei from the point of view of the experimentalists. It covers among other subjects the following topics: (1) the discovery of a new region of superdeformed nuclei near A=190, (2) the surprising result of the occurrence of bands with identical transition energies in neighboring superdeformed nuclei near A=150 and A=190, (3) the importance of octupole degrees of freedom at large deformation and (4) the properties associated with the feeding and the decay of superdeformed bands. The text presented hereafter will appear as a contribution to the Annual Review of Nuclear and Particle Science, Volume 41. 88 refs., 11 figs.

  6. Estimation of M 1 scissors mode strength for deformed nuclei in the medium- to heavy-mass region by statistical Hauser-Feshbach model calculations

    NASA Astrophysics Data System (ADS)

    Mumpower, M. R.; Kawano, T.; Ullmann, J. L.; Krtička, M.; Sprouse, T. M.

    2017-08-01

    Radiative neutron capture is an important nuclear reaction whose accurate description is needed for many applications ranging from nuclear technology to nuclear astrophysics. The description of such a process relies on the Hauser-Feshbach theory which requires the nuclear optical potential, level density, and γ -strength function as model inputs. It has recently been suggested that the M 1 scissors mode may explain discrepancies between theoretical calculations and evaluated data. We explore statistical model calculations with the strength of the M 1 scissors mode estimated to be dependent on the nuclear deformation of the compound system. We show that the form of the M 1 scissors mode improves the theoretical description of evaluated data and the match to experiment in both the fission product and actinide regions. Since the scissors mode occurs in the range of a few keV to a few MeV, it may also impact the neutron capture cross sections of neutron-rich nuclei that participate in the rapid neutron capture process of nucleosynthesis. We comment on the possible impact to nucleosynthesis by evaluating neutron capture rates for neutron-rich nuclei with the M 1 scissors mode active.

  7. Cosmogenic nuclei

    NASA Technical Reports Server (NTRS)

    Raisbeck, G. M.

    1986-01-01

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

  8. Neutron-rich rare-isotope production from projectile fission of heavy nuclei near 20 MeV/nucleon beam energy

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    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 transfer model (DIT) or with the microscopic constrained molecular dynamics model (CoMD). The de-excitation or fission of the hot heavy projectile fragments is performed with the statistical multifragmentation model (SMM). We compared our model calculations with our previous experimental projectile-fission data of 238U (20 MeV/nucleon) + 208Pb and 197Au (20 MeV/nucleon) + 197Au and found an overall reasonable agreement. Our study suggests that projectile fission following peripheral heavy-ion collisions at this energy range offers an effective route to access very neutron-rich rare isotopes toward and beyond the astrophysical r-process path.

  9. X-ray decay lines from heavy nuclei in supernova remnants as a probe of the r-process origin and the birth periods of magnetars

    NASA Astrophysics Data System (ADS)

    Ripley, Justin L.; Metzger, Brian D.; Arcones, Almudena; Martínez-Pinedo, Gabriel

    2014-03-01

    The origin of rapid neutron capture (r-process) nuclei remains one of the longest standing mysteries in nuclear astrophysics. Core collapse supernovae (SNe) and neutron star binary mergers are likely r-process sites, but little evidence yet exists for their in situ formation in such environments. Motivated by the advent of sensitive new or planned X-ray telescopes such as the Nuclear Spectroscopic Telescope Array (NuSTAR) and the Large Observatory for X-ray Timing (LOFT), we revisit the prospects for the detection of X-ray decay lines from r-process nuclei in young or nearby supernova remnants. For all remnants planned to be observed by NuSTAR (and several others), we conclude that r-process nuclei are detectable only if the remnant possesses a large overabundance O ≳ 10^3 relative to the average yield per SN. Prospects are better for the next Galactic SN (assumed age of 3 yr and distance of 10 kpc), for which an average r-process yield is detectable via the 10.7 (9.2) keV line complexes of 194Os by LOFT at 6σ (5σ) confidence; the 27.3 keV line complex of 125Sb is detectable by NuSTAR at 2σ for O ≳ 2. We also consider X-rays lines from the remnants of Galactic magnetars, motivated by the much higher r-process yields of the magnetorotationally driven SNe predicted to birth magnetars. The ˜3.6-3.9 keV lines of 126Sn are potentially detectable in the remnants of the magnetars 1E1547.0-5408 and 1E2259+586 by LOFT for an assumed r-process yield predicted by recent simulations. The (non-)detection of these lines can thus probe whether magnetars are indeed born with millisecond periods. Finally, we consider a blind survey of the Galactic plane with LOFT for r-process lines from the most recent binary neutron star merger remnant, concluding that a detection is unlikely without additional information on the merger location.

  10. The influence of a presence of a heavy atom on the spin-spin coupling constants between two light nuclei in organometallic compounds and halogen derivatives

    NASA Astrophysics Data System (ADS)

    Wodyński, Artur; Pecul, Magdalena

    2014-01-01

    The 1JCC and 1JCH spin-spin coupling constants have been calculated by means of density functional theory (DFT) for a set of derivatives of aliphatic hydrocarbons substituted with I, At, Cd, and Hg in order to evaluate the substituent and relativistic effects for these properties. The main goal was to estimate HALA (heavy-atom-on-light-atom) effects on spin-spin coupling constants and to explore the factors which may influence the HALA effect on these properties, including the nature of the heavy atom substituent and carbon hybridization. The methods applied range, in order of reduced complexity, from Dirac-Kohn-Sham method (density functional theory with four-component Dirac-Coulomb Hamiltonian), through DFT with two- and one-component Zeroth Order Regular Approximation (ZORA) Hamiltonians, to scalar non-relativistic effective core potentials with the non-relativistic Hamiltonian. Thus, we are able to compare the performance of ZORA-DFT and Dirac-Kohn-Sham methods for modelling of the HALA effects on the spin-spin coupling constants.

  11. The influence of a presence of a heavy atom on the spin-spin coupling constants between two light nuclei in organometallic compounds and halogen derivatives

    SciTech Connect

    Wodyński, Artur; Pecul, Magdalena

    2014-01-14

    The {sup 1}J{sub CC} and {sup 1}J{sub CH} spin-spin coupling constants have been calculated by means of density functional theory (DFT) for a set of derivatives of aliphatic hydrocarbons substituted with I, At, Cd, and Hg in order to evaluate the substituent and relativistic effects for these properties. The main goal was to estimate HALA (heavy-atom-on-light-atom) effects on spin-spin coupling constants and to explore the factors which may influence the HALA effect on these properties, including the nature of the heavy atom substituent and carbon hybridization. The methods applied range, in order of reduced complexity, from Dirac-Kohn-Sham method (density functional theory with four-component Dirac-Coulomb Hamiltonian), through DFT with two- and one-component Zeroth Order Regular Approximation (ZORA) Hamiltonians, to scalar non-relativistic effective core potentials with the non-relativistic Hamiltonian. Thus, we are able to compare the performance of ZORA-DFT and Dirac-Kohn-Sham methods for modelling of the HALA effects on the spin-spin coupling constants.

  12. Measurements and calculations of the Coulomb cross section for the production of direct electron pairs by energetic heavy nuclei in nuclear track emulsion

    NASA Technical Reports Server (NTRS)

    Derrickson, J. H.; Eby, P. B.; Fountain, W. F.; Parnell, T. A.; Dong, B. L.; Gregory, J. C.; Takahashi, Y.; King, D. T.

    1988-01-01

    Measurements and theoretical predictions of the Coulomb cross section for the production of direct electron pairs by heavy ions in emulsion have been performed. Nuclear track emulsions were exposed to the 1.8 GeV/amu Fe-56 beam at the Lawrence Berkeley Laboratory bevalac and to the 60 and 200 GeV/amu O-16 and the 200 GeV/amu S-32 beam at the European Center for Nuclear Research Super Proton Synchrotron modified to accelerate heavy ions. The calculations combine the Weizsacker-Williams virtual quanta method applicable to the low-energy transfers and the Kelner-Kotov relativistic treatment for the high-energy transfers. Comparison of the measured total electron pair yield, the energy transfer distribution, and the emission angle distribution with theoretical predictions revealed a discrepancy in the frequency of occurrence of the low-energy pairs (less than or = 10 MeV). The microscope scanning criteria used to identify the direct electron pairs is described and efforts to improve the calculation of the cross section for pair production are also discussed.

  13. Studies of heavy ion reactions and transuranic nuclei. Progress report, August 1, 1979-July 31, 1980. [Univ. of Rochester, New York, 8/1/79-7/31/80

    SciTech Connect

    Huizenga, J.R.

    1980-07-01

    The study of heavy-ion reaction mechanisms at the SuperHILAC and LAMPF is reported. Preprints of five articles and manuscripts of four recent conference papers are given, along with complete citations of publications and a list of personnel. Significant work was performed in the following areas: the bombarding energy dependence of the /sup 209/Bi + /sup 136/Xe reaction; the fragment yields for specific Z and A for projectile-like fragments produced in the reaction of 8.3-MeV/u /sup 56/Fe ions with targets of /sup 56/Fe, /sup 165/Ho, /sup 209/Bi, and /sup 238/U; and time distributions of fragments from delayed fission after muon capture for muonic /sup 235/U, /sup 238/U, /sup 237/Np, /sup 239/Pu, and /sup 242/Pu. (RWR)

  14. Exotic Nuclei

    SciTech Connect

    Galindo-Uribarri, Alfredo {nmn}

    2010-01-01

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

  15. Exploratory study of fission product yield determination from photofission of Pu239 at 11 MeV with monoenergetic photons

    DOE PAGES

    Bhike, Megha; Tornow, W.; Krishichayan, -; ...

    2017-02-14

    Here, measurements of fission product yields play an important role for the understanding of fundamental aspects of the fission process. Recently, neutron-induced fission product-yield data of 239Pu at energies below 4 MeV revealed an unexpected energy dependence of certain fission fragments. In order to investigate whether this observation is prerogative to neutron-induced fission, a program has been initiated to measure fission product yields in photoinduced fission. Here we report on the first ever photofission product yield measurement with monoenergetic photons produced by Compton back-scattering of FEL photons. The experiment was performed at the High-Intensity Gamma-ray Source at Triangle Universities Nuclear Laboratory on 239Pu at Eγmore » = 11 MeV. In this exploratory study the yield of eight fission products ranging from 91Sr to 143Ce has been obtained.« less

  16. Parton distributions in nuclei: Quagma or quagmire

    SciTech Connect

    Close, F.E.

    1988-01-01

    The emerging information on the way quark, antiquark, and gluon distributions are modified in nuclei relative to free nucleons is reviewed. Particular emphasis is placed on Drell-Yan and /psi/ production on nuclei and caution against premature use of these as signals for quagma in heavy-ion collisions. If we are to identify the formation of quark-gluon plasma in heavy-ion collisions by changes in the production rates for /psi/ relative to Drell-Yan lepton pairs, then it is important that we first understand the ''intrinsic'' changes in parton distributions in nuclei relative to free nucleons. So, emerging knowledge on how quark, antiquark, and gluon distributions are modified in nuclei relative to free nucleons is reviewed, and the emerging theoretical concensus is briefly summarized.

  17. Unexpected high-energy γ emission from decaying exotic nuclei

    NASA Astrophysics Data System (ADS)

    Gottardo, A.; Verney, D.; Deloncle, I.; Péru, S.; Delafosse, C.; Roccia, S.; Matea, I.; Sotty, C.; Andreoiu, C.; Costache, C.; Delattre, M.-C.; Etilé, A.; Franchoo, S.; Gaulard, C.; Guillot, J.; Ibrahim, F.; Lebois, M.; MacCormick, M.; Marginean, N.; Marginean, R.; Martini, M.; Mihai, C.; Mitu, I.; Olivier, L.; Portail, C.; Qi, L.; Roussière, B.; Stan, L.; Testov, D.; Wilson, J.; Yordanov, D. T.

    2017-09-01

    The N = 5283Gaβ decay was studied at ALTO. The radioactive 83Ga beam was produced through the ISOL photofission technique and collected on a movable tape for the measurement of γ-ray emission following β decay. While β-delayed neutron emission has been measured to be 56-85% of the decay path, in this experiment an unexpected high-energy 5-9 MeV γ-ray yield of 16(4)% was observed, coming from states several MeVs above the neutron separation threshold. This result is compared with cutting-edge QRPA calculations, which show that when neutrons deeply bound in the core of the nucleus decay into protons via a Gamow-Teller transition, they give rise to a dipolar oscillation of nuclear matter in the nucleus. This leads to large electromagnetic transition probabilities which can compete with neutron emission, thus affecting the β-decay path. This process is enhanced by an excess of neutrons on the nuclear surface and may thus be a common feature for very neutron-rich isotopes, challenging the present understanding of decay properties of exotic nuclei.

  18. Computer Model Of Fragmentation Of Atomic Nuclei

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.

    1995-01-01

    High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.

  19. Computer Model Of Fragmentation Of Atomic Nuclei

    NASA Technical Reports Server (NTRS)

    Wilson, John W.; Townsend, Lawrence W.; Tripathi, Ram K.; Norbury, John W.; KHAN FERDOUS; Badavi, Francis F.

    1995-01-01

    High Charge and Energy Semiempirical Nuclear Fragmentation Model (HZEFRG1) computer program developed to be computationally efficient, user-friendly, physics-based program for generating data bases on fragmentation of atomic nuclei. Data bases generated used in calculations pertaining to such radiation-transport applications as shielding against radiation in outer space, radiation dosimetry in outer space, cancer therapy in laboratories with beams of heavy ions, and simulation studies for designing detectors for experiments in nuclear physics. Provides cross sections for production of individual elements and isotopes in breakups of high-energy heavy ions by combined nuclear and Coulomb fields of interacting nuclei. Written in ANSI FORTRAN 77.

  20. Collective Clusterization in Nuclei and Excited Compound Systems: The Dynamical Cluster-Decay Model

    NASA Astrophysics Data System (ADS)

    Gupta, Raj K.

    Clustering is a general feature of light, N = Z, α-like stable nuclei for both the ground and (intrinsic) excited states. This phenomenon is observed in spontaneous decays of heavy radioactive nuclei, and seems to play an important role in the decay of excited compound systems formed in heavy ion reactions. It is also shown to be present in exotic light-halo, super-heavy and super-superheavy nuclei.

  1. Nuclei at High Angular Momentum

    SciTech Connect

    Diamond, R. M.; Stephens, F. S.

    1980-12-01

    It appears that most nuclei show a compromise between purely collective and purely non-collective behavior at very high spins.non~collective behavior in nuclei has been seen only as high as 36 or 37{bar h}, at which point a more collective structure seems to develop. The concepts underlying the study of high angular momentum states are discussed. The factors that limit angular momentum in nuclei are considered. The currently emerging state of physics of very high spin states is reviewed. The detailed calculations currently made for high spin states are described, focusing not on the calculations themselves, but on the physical input to them and results that come out. Production of high-spin states using heavy-ion reactions is reviewed. Studies of {gamma}-rays de-exciting the evaporation residues from heavy-ion reactions are covered. Two types of {gamma} rays occur: those that cool the nucleus to or toward the yrast line, called "statistical," and those that are more or less parallel to the yrast line and remove the angular momentum, called "yrast~like." Collective rotation, in simplest form the motion of a deformed nucleus around an axis perpendicular to its symmetry axis, is also covered.

  2. Annihilation of Antiprotons in Heavy Nuclei.

    DTIC Science & Technology

    1986-04-01

    Consideration of matter- antimatter annihilation as an energy source for space propulsion has been taking place over the last several years. For details of...Journal of the British Interplanetary Society. Matter- antimatter annihilation produces the greatest amount of energy per unit mass of propellant of...any known possible means of propulsion. The form of antimatter most often considered for annihilation consists of antiprotons, which are the

  3. CORE RECONSTITUTION IN HEAVY DEFORMED NUCLEI

    DTIC Science & Technology

    The deviations are enumerated in the smooth systematics of rotational and vibrational characteristics in the regions of the nuclear periodic table where...there is a considerable prolate deformation. These deviations are classified according to their position in the nuclear periodic table . A

  4. Decay studies of heavy and superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Clark, Roderick M.

    2016-12-01

    In this contribution I discuss recent results on the decay of excited states, via electromagnetic transitions (γ-ray and conversion electrons), α decay, and fission, and discuss what these studies reveal in terms of the stability of the heaviest elements.

  5. Transitional nuclei near shell closures

    SciTech Connect

    Mukherjee, G.

    2014-08-14

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

  6. Measurement of elliptic flow of light nuclei at sNN=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

    SciTech Connect

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, X. M.; Sun, Z.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, Y.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, F.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, H.; Xu, Z.; Xu, J.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Yang, Y.; Yang, S.; Yang, C.; Yang, Y.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I. -K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, Y.; Zhang, X. P.; Zhang, Z.; Zhang, J. B.; Zhang, S.; Zhang, S.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.

    2016-09-23

    Here we present measurements of second-order azimuthal anisotropy ( v2 ) at midrapidity ( |y| < 1.0 ) for light nuclei d , t , 3He (for $\\sqrt{s}$$_{NN}$ = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei$\\bar{d}$ ( $\\sqrt{s}$$_{NN}$ = 200 , 62.4, 39, 27, and 19.6 GeV) and 3 ¯¯¯¯¯ He ( $\\sqrt{s}$$_{NN}$ = 200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v2 for these light nuclei produced in heavy-ion collisions is compared with those for p and $\\bar{p}$. We observe mass ordering in nuclei v2 ( pT) at low transverse momenta ( pT < 2.0 GeV/c). We also find a centrality dependence of v2 for d and $\\bar{d}$ . The magnitude of v2 for t and 3He agree within statistical errors. Light-nuclei v2 are compared with predictions from a blast-wave model. Atomic mass number ( A ) scaling of light-nuclei v2 (pT) seems to hold for pT / A < 1.5 GeV/c . Results on light-nuclei v2 from a transport-plus-coalescence model are consistent with the experimental measurements.

  7. Measurement of elliptic flow of light nuclei at sNN=200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV at the BNL Relativistic Heavy Ion Collider

    SciTech Connect

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisel, I.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, M. K.; Sharma, B.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, X. M.; Sun, Z.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, Y.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, F.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, H.; Xu, Z.; Xu, J.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Yang, Y.; Yang, S.; Yang, C.; Yang, Y.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I. -K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, J.; Zhang, Y.; Zhang, X. P.; Zhang, Z.; Zhang, J. B.; Zhang, S.; Zhang, S.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.

    2016-09-23

    Here we present measurements of second-order azimuthal anisotropy ( v2 ) at midrapidity ( |y| < 1.0 ) for light nuclei d , t , 3He (for $\\sqrt{s}$$_{NN}$ = 200 , 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV) and antinuclei$\\bar{d}$ ( $\\sqrt{s}$$_{NN}$ = 200 , 62.4, 39, 27, and 19.6 GeV) and 3 ¯¯¯¯¯ He ( $\\sqrt{s}$$_{NN}$ = 200 GeV) in the STAR (Solenoidal Tracker at RHIC) experiment. The v2 for these light nuclei produced in heavy-ion collisions is compared with those for p and $\\bar{p}$. We observe mass ordering in nuclei v2 ( pT) at low transverse momenta ( pT < 2.0 GeV/c). We also find a centrality dependence of v2 for d and $\\bar{d}$ . The magnitude of v2 for t and 3He agree within statistical errors. Light-nuclei v2 are compared with predictions from a blast-wave model. Atomic mass number ( A ) scaling of light-nuclei v2 (pT) seems to hold for pT / A < 1.5 GeV/c . Results on light-nuclei v2 from a transport-plus-coalescence model are consistent with the experimental measurements.

  8. Stability and production of superheavy nuclei

    SciTech Connect

    Moeller, P. |; Nix, J.R.

    1997-12-31

    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 {sup 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.

  9. Stability and production of superheavy nuclei

    SciTech Connect

    Moeller, Peter; Nix, J. Rayford

    1998-02-15

    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 sufficiently 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 {sup 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. We 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. We discuss here the effect of the doubly magic structure of the target in cold-fusion reactions on the fusion barrier and on dissipation.

  10. Stability and production of superheavy nuclei

    SciTech Connect

    Moeller, P.; Moeller, P.; Nix, J.R.

    1998-02-01

    Beyond uranium heavy elements rapidly become increasingly unstable with respect to spontaneous fission as the proton number {ital 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 sufficiently 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 {sup 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. We 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. We discuss here the effect of the doubly magic structure of the target in cold-fusion reactions on the fusion barrier and on dissipation. {copyright} {ital 1998 American Institute of Physics.}

  11. Order-to-chaos transition in rotational nuclei

    SciTech Connect

    Stephens, F.S.; Deleplanque, M.A.; Lee, I.Y.; Macchiavelli, A.O.; Ward, D.; Fallon, P.; Cromaz, M.; Clark, R.M.; Descovich, M.; Diamond, R.M.; Rodriguez-Vieitez, E.

    2004-05-13

    The authors have studied the narrow (valley-ridge) structure in the {gamma}-ray spectrum following a heavy-ion fusion reaction that produces several ytterbium nuclei. The intensity of this structure can be quantitatively related to the average chaotic behavior in these nuclei and they have traced this behavior from nearly fully ordered to nearly fully chaotic.

  12. Higher spin states in neutron rich nuclei

    NASA Astrophysics Data System (ADS)

    Zhu, S.; Zhao, X.; Hamilton, J. H.; Ramayya, A. V.; Ma, W. C.; Peker, L. K.; Kormicki, J.; Hong, X.; Gao, W. B.; Deng, J. K.

    Nuclei on the neutron rich side of beta stability have long been of interest for nuclear structure studies because they probe different regions of the single particle spectrum and different shell gap combinations for both spherical and deformed shapes. However, such nuclei have been a difficult challenge experimentally. Much information has been gained about the properties of neutron rich nuclei at low spin from the study of radioactive isotopes produced in neutron induced, and more recently, proton induced fission of uranium. Such studies have been made possible by the use of isotope separators on line to reactors and more recently to low energy proton accelerators. However, to test many of the theoretical predictions of nuclear models one needs information about the higher spin states in nuclei in addition to their low spin states populated in radioactive decays. Higher spin states in neutron rich nuclei have been an even more difficult challenge than the lower spin states accessible through decay studies. One cannot reach the higher spin states in these nuclei by heavy ion fusion evaporation in reactions as carried out extensively for proton rich nuclei. Many years ago prompt spontaneous fission studies were used to suggest for the first time that Sr-98 and Zr-100 had unusually large ground state of deformations. The availability of higher efficiency multi-detector arrays of Compton suppressed Ge detectors has brought on a renewed interest in studies of the prompt gamma rays of the fragments from spontaneous and induced fission. Groups at Argonne, Daresbury, and a Vanderbilt-Oak Ridge-Idaho-Dubna collaboration have carried out several such studies from spontaneous and heavy-ion induced fission which have revealed new insights into our knowledge of neutron rich nuclei. This paper is primarily a review of these studies, including recent, unpublished results.

  13. Structure and spectroscopy of transcurium nuclei.

    SciTech Connect

    Ahmad, I.

    2001-11-09

    The stability of the superheavy elements depends on the shell corrections which are governed by the single-particle spectra. Ideally one would like to experimentally determine the single-particle levels in the superheavy nuclei but the production of only a few atoms of these nuclides precludes such measurements. One therefore has to identify single-particle levels in the heaviest nuclei which are available in at least nanoCurie amounts. They have studied the structure of such heavy nuclei in the Z=98 region and identified many single-particle states. In particular, they have studied the structure of {sup 251}Cf and {sup 249}Bk by measuring the radiations emitted in the {alpha} decay of {sup 255}Fm and {sup 253}Es. These single-particle spectra can be used to test theoretical models for superheavy elements.

  14. Fission Barriers of Compound Superheavy Nuclei

    NASA Astrophysics Data System (ADS)

    Pei, J. C.; Nazarewicz, W.; Sheikh, J. A.; Kerman, A. K.

    2009-05-01

    The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. In this work, we investigate the isentropic fission barriers by means of the self-consistent nuclear density functional theory. The relationship between isothermal and isentropic descriptions is demonstrated. Calculations have been carried out for Fm264, Ds272, 127812, 129214, and 131224. For nuclei around 127812 produced in “cold-fusion” reactions, we predict a more rapid decrease of fission barriers with excitation energy as compared to the nuclei around 129214 synthesized in “hot-fusion” experiments. This is explained in terms of the difference between the ground-state and saddle-point temperatures. The effect of the particle gas is found to be negligible in the range of temperatures studied.

  15. Fission barriers of compound superheavy nuclei.

    PubMed

    Pei, J C; Nazarewicz, W; Sheikh, J A; Kerman, A K

    2009-05-15

    The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. In this work, we investigate the isentropic fission barriers by means of the self-consistent nuclear density functional theory. The relationship between isothermal and isentropic descriptions is demonstrated. Calculations have been carried out for 264Fm, 272Ds, ;{278}112, ;{292}114, and ;{312}124. For nuclei around ;{278}112 produced in "cold-fusion" reactions, we predict a more rapid decrease of fission barriers with excitation energy as compared to the nuclei around ;{292}114 synthesized in "hot-fusion" experiments. This is explained in terms of the difference between the ground-state and saddle-point temperatures. The effect of the particle gas is found to be negligible in the range of temperatures studied.

  16. Statistical ensembles and fragmentation of finite nuclei

    NASA Astrophysics Data System (ADS)

    Das, P.; Mallik, S.; Chaudhuri, G.

    2017-09-01

    Statistical models based on different ensembles are very commonly used to describe the nuclear multifragmentation reaction in heavy ion collisions at intermediate energies. Canonical model results are more appropriate for finite nuclei calculations while those obtained from the grand canonical ones are more easily calculable. A transformation relation has been worked out for converting results of finite nuclei from grand canonical to canonical and vice versa. The formula shows that, irrespective of the particle number fluctuation in the grand canonical ensemble, exact canonical results can be recovered for observables varying linearly or quadratically with the number of particles. This result is of great significance since the baryon and charge conservation constraints can make the exact canonical calculations extremely difficult in general. This concept developed in this work can be extended in future for transformation to ensembles where analytical solutions do not exist. The applicability of certain equations (isoscaling, etc.) in the regime of finite nuclei can also be tested using this transformation relation.

  17. Adiabatic fission barriers in superheavy nuclei

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    Using the microscopic-macroscopic model based on the deformed Woods-Saxon single-particle potential and the Yukawa-plus-exponential macroscopic energy, we calculated static fission barriers Bf for 1305 heavy and superheavy nuclei 98 ≤Z ≤126 , including even-even, odd-even, even-odd and odd-odd systems. For odd and odd-odd nuclei, adiabatic potential-energy surfaces were calculated by a minimization over configurations with one blocked neutron or/and proton on a level from the 10th below to the 10th above the Fermi level. The parameters of the model that have been fixed previously by a fit to masses of even-even heavy nuclei were kept unchanged. A search for saddle points has been performed by the "imaginary water flow" method on a basic five-dimensional deformation grid, including triaxiality. Two auxiliary grids were used for checking the effects of the mass asymmetry and hexadecapole nonaxiality. The ground states (g.s.) were found by energy minimization over configurations and deformations. We find that the nonaxiality significantly changes first and second fission saddle in many nuclei. The effect of the mass asymmetry, known to lower the second, very deformed saddles in actinides, in the heaviest nuclei appears at the less deformed saddles in more than 100 nuclei. It happens for those saddles in which the triaxiality does not play any role, which suggests a decoupling between effects of the mass asymmetry and triaxiality. We studied also the influence of the pairing interaction strength on the staggering of Bf for odd- and even-particle numbers. Finally, we provide a comparison of our results with other theoretical fission barrier evaluations and with available experimental estimates.

  18. Fusion and Breakup of Weakly Bound Nuclei

    SciTech Connect

    Gomes, P. R. S.; Lubian, J.; Padron, I.; Crema, E.; Chamon, L. C.; Hussein, M. S.; Canto, L. F.

    2006-08-14

    We discuss the influence of the breakup process of weakly bound nuclei on the fusion cross section. The complete fusion for heavy targets is found to be suppressed due to the incomplete fusion following the breakup, whereas this effect is negligible for light targets. The total fusion cross sections for stable projectiles are not affected by the breakup process, whereas it is suppressed for halo projectiles. The non capture breakup is the dominant process at sub-barrier energies.

  19. Active galactic nuclei

    PubMed Central

    Fabian, Andrew C.

    1999-01-01

    Active galactic nuclei are the most powerful, long-lived objects in the Universe. Recent data confirm the theoretical idea that the power source is accretion into a massive black hole. The common occurrence of obscuration and outflows probably means that the contribution of active galactic nuclei to the power density of the Universe has been generally underestimated. PMID:10220363

  20. Exploratory study of fission product yield determination from photofission of 239Pu at 11 MeV with monoenergetic photons

    NASA Astrophysics Data System (ADS)

    Bhike, Megha; Tornow, W.; Krishichayan, Tonchev, A. P.

    2017-02-01

    Measurements of fission product yields play an important role for the understanding of fundamental aspects of the fission process. Recently, neutron-induced fission product-yield data of 239Pu at energies below 4 MeV revealed an unexpected energy dependence of certain fission fragments. In order to investigate whether this observation is prerogative to neutron-induced fission, a program has been initiated to measure fission product yields in photoinduced fission. Here we report on the first ever photofission product yield measurement with monoenergetic photons produced by Compton back-scattering of FEL photons. The experiment was performed at the High-Intensity Gamma-ray Source at Triangle Universities Nuclear Laboratory on 239Pu at Eγ=11 MeV. In this exploratory study the yield of eight fission products ranging from 91Sr to 143Ce has been obtained.

  1. Abundances of cosmic ray nuclei heavier than 50 Sn

    NASA Technical Reports Server (NTRS)

    Waddington, C. J.; Fickle, R. K.; Garrard, T. L.; Stone, E. C.; Binns, W. R.; Israel, M. H.; Klarmann, J.

    1982-01-01

    Preliminary results are reported from 430 days of exposure of the heavy nuclei experiment on the HEAO-3 spacecraft. These results are confined to the heavy nuclei with Z equal to or greater than 50 and emphasize the conclusions obtained on the relative numbers of actinides and heavy stable elements in the lead-platinum region. The extreme paucity of actinides found is inconsistent with the predictions of a cosmic ray source that is highly enriched in r-process material, but quite consistent with a source whose composition is similar to that of normal solar system material. An upper limit, at the 95 percent confidence level, is placed in the ratio of nuclei with Z equal to or greater than 88/(Z in the range from 74 to 87) of 0.03.

  2. Isolation of Nuclei.

    PubMed

    Nabbi, Arash; Riabowol, Karl

    2015-08-03

    The isolation of nuclei is often the first step in studying processes such as nuclear-cytoplasmic shuttling, subcellular localization of proteins, and protein-chromatin or nuclear protein-protein interactions in response to diverse stimuli. Therefore, rapidly obtaining nuclei from cells with relatively high purity and minimal subcellular contamination, protein degradation, or postharvesting modification is highly desirable. Historically, the isolation of nuclei involved a homogenization step followed by centrifugation through high-density glycerol or sucrose. Although clean nuclei with little cytoplasmic contamination can be prepared using this method, it is typically time consuming and can allow protein degradation, protein modification, and leaching of components from the nuclei to occur. We have developed a rapid and simple fractionation method that is based on the selective dissolution of the cytoplasmic membrane (but not the nuclear membrane) using a low concentration of a nonionic detergent and rapid centrifugation steps. Here we describe important considerations when isolating nuclei from cells, introduce our rapid method, and compare this method to a more traditional protocol for isolating nuclei, noting the strengths and limitations of each approach.

  3. The intergalactic propagation of ultrahigh energy cosmic ray nuclei

    SciTech Connect

    Hooper, Dan; Sarkar, Subir; Taylor, Andrew M.; /Oxford U.

    2006-08-01

    We investigate the propagation of ultra-high energy cosmic ray nuclei (A = 1-56) from cosmologically distant sources through the cosmic radiation backgrounds. Various models for the injected composition and spectrum and of the cosmic infrared background are studied using updated photodisintegration cross-sections. The observational data on the spectrum and the composition of ultra-high energy cosmic rays are jointly consistent with a model where all of the injected primary cosmic rays are iron nuclei (or a mixture of heavy and light nuclei).

  4. New measurements of the EMC effect in light nuclei

    SciTech Connect

    A. Daniel

    2009-12-01

    Modifications of structure functions in nuclei (EMC effect) suggest that the nuclear quark distribution function is not just the incoherent sum of the proton and neutron distributions, and made clear the importance of nuclear effects even in high energy measurements. Jefferson Lab experiment E03-103 made precise measurements of the EMC effect in few-body and heavy nuclei with emphasis on the large x region. Data from the light nuclei suggests that the nuclear dependence of the high x quark distribution may depend on the nucleon's local environment, rather than being a purely bulk effect.

  5. Relativistic Brueckner—Hartree—Fock Theory for Finite Nuclei

    NASA Astrophysics Data System (ADS)

    Shen, Shi-Hang; Hu, Jin-Niu; Liang, Hao-Zhao; Meng, Jie; Ring, Peter; Zhang, Shuang-Quan

    2016-10-01

    Starting with a bare nucleon-nucleon interaction, for the first time the full relativistic Brueckner-Hartree-Fock equations are solved for finite nuclei in a Dirac-Woods-Saxon basis. No free parameters are introduced to calculate the ground-state properties of finite nuclei. The nucleus $^{16}$O is investigated as an example. The resulting ground-state properties, such as binding energy and charge radius, are considerably improved as compared with the non-relativistic Brueckner-Hartree-Fock results and much closer to the experimental data. This opens the door for \\emph{ab initio} covariant investigations of heavy nuclei.

  6. Exotic Light Nuclei

    ERIC Educational Resources Information Center

    Cerny, Joseph; Poskanzer, Arthur M.

    1978-01-01

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

  7. Exotic Light Nuclei

    ERIC Educational Resources Information Center

    Cerny, Joseph; Poskanzer, Arthur M.

    1978-01-01

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

  8. Observations of cometary nuclei

    NASA Astrophysics Data System (ADS)

    A'Hearn, M. F.

    Attempts to observe cometary nuclei and to determine fundamental physical parameters relevant to the relationship between comets and asteroids are reviewed. It has been found that cometary nuclei, at least of periodic comets, are bigger and blacker than generally thought as recently as five years ago. Geometric albedos may be typically three percent and typical radii are probably of order 5 km. Nuclei of periodic comets are probably highly prolate unless they are both oblate and rotating about one of the major axes. P/Halley images provide convincing evidence of the existence of mantles discussed in many models. Numerous pieces of evidence suggest a connection between cometary nuclei and A-A asteroids of types D and C.

  9. On the role of energy separated in fission process, excitation energy and reaction channels effects in the isomeric ratios of fission product 135Xe in photofission of actinide elements

    NASA Astrophysics Data System (ADS)

    Thiep, Tran Duc; An, Truong Thi; Cuong, Phan Viet; Vinh, Nguyen The; Mishinski, G. V.; Zhemenik, V. I.

    2016-07-01

    In this work we present the isomeric ratio of fission product 135Xe in the photo-fission of actinide elements 232Th, 233U and 237Np induced by end-point bremsstrahlung energies of 13.5, 23.5 and 25.0 MeV which were determined by the method of inert gaseous flow. The data were analyzed, discussed and compared with the similar data from literature to examine the role of energy separated in fission process, excitation energy and reaction channels effects.

  10. Photofission cross-section ratio measurement of 235 U/ 238 U using monoenergetic photons in the energy range of 9.0–16.6 MeV

    DOE PAGES

    Krishichayan,; Bhike, Megha; Finch, S. W.; ...

    2017-05-01

    Photofission cross-section ratios of 235U and 238U have been measured using monoenergetic photon beams from the High Intensity Gamma-ray Source facility at the Triangle Universities Nuclear Laboratory. These measurements have been performed in small energy steps between 9.0 and 16.6 MeV using a dual-fission ionization chamber. The measured cross-section ratios are compared with the previous experimental data as well as with the recent evaluated nuclear data library ENDF.

  11. Heavy hadrons in nuclear matter

    NASA Astrophysics Data System (ADS)

    Hosaka, Atsushi; Hyodo, Tetsuo; Sudoh, Kazutaka; Yamaguchi, Yasuhiro; Yasui, Shigehiro

    2017-09-01

    Current studies on heavy hadrons in nuclear medium are reviewed with a summary of the basic theoretical concepts of QCD, namely chiral symmetry, heavy quark spin symmetry, and the effective Lagrangian approach. The nuclear matter is an interesting place to study the properties of heavy hadrons from many different points of view. We emphasize the importance of the following topics: (i) charm/bottom hadron-nucleon interaction, (ii) structure of charm/bottom nuclei, and (iii) QCD vacuum properties and hadron modifications in nuclear medium. We pick up three different groups of heavy hadrons, quarkonia (J / ψ, ϒ), heavy-light mesons (D/ D ¯ , B ¯ / B) and heavy baryons (Λc, Λb). The modifications of those hadrons in nuclear matter provide us with important information to investigate the essential properties of heavy hadrons. We also give the discussions about the heavy hadrons, not only in infinite nuclear matter, but also in finite-size atomic nuclei with finite baryon numbers, to serve future experiments.

  12. Cluster Features of Normal-, Super- and Hyperdeformed nuclei

    SciTech Connect

    Adamian, G.G.; Antonenko, N.V.; Kuklin, S.N.

    2005-11-21

    It is shown that an important mode of nuclear excitations in different processes like as cluster radioactivity, parity splitting in normal deformed bands, decay out phenomenon of the yrast superdeformed states in the heavy nuclei and formation of super- and hyper-deformed states in induced fission and heavy ion reactions is related to the motion in charge (mass) asymmetry coordinate. With the suggested cluster model one can try to unify all phenomena mentioned above.

  13. New Neutron Rich Nuclei Near {sup 208}Pb

    SciTech Connect

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

    1998-11-13

    The level properties near the stable doubly-magic nuclei formed the experimental grounds for the theoretical description of nuclear structure. However with a departure from the beta-stability line, the classical well-established shell structure might be modified. In particular, it may even vanish for extremely exotic neutron-rich nuclei near the neutron-drip line. Presently, it is impossible to verify such predictions by a direct experimental studies of these exotic objects. However, one may try to observe and understand the evolution of the nuclear structure while departing in the experiment as far as possible from the stable nuclei. An extension of experimental nuclear structure studies towards the nuclei characterized by high neutron excess is crucial for such verifications as well as for the {tau}-process nucleosynthesis scenario. Heavy neutron-rich nuclei, south-east of doubly-magic {sup 208}Pb, were always very difficult to produce and investigate. The nuclei like {sup 218}Po and {sup 214}Pb or {sup 210}Tl marked the border line of known nuclei from the beginning of the radioactivity era for over ninety years. To illustrate the difficulties, one can refer to the experiments employing the on-line mass separator technique. A spallation of heavy targets like {sup 232}Th and {sup 238}U by high-energy protons was proven as a source of heavy neutron-rich nuclei. The isotopes near and beyond doubly-magic {sup 208}Pb were produced too. However, such studies often suffered from an isobaric contamination of much more strongly produced and efficiently released elements like francium or radon and their decay products. A new experimental technique, based on the pulsed release element selective method recently developed at the PS Booster-ISOLDE at CERN [7,8,9] greatly reduces the contamination of these very short-lived {alpha}-emitters (Z {ge} 84) for the isobaric mass chains A=215 to A=218.

  14. Imaging using accelerated heavy ions

    SciTech Connect

    Chu, W.T.

    1982-05-01

    Several methods for imaging using accelerated heavy ion beams are being investigated at Lawrence Berkeley Laboratory. Using the HILAC (Heavy-Ion Linear Accelerator) as an injector, the Bevalac can accelerate fully stripped atomic nuclei from carbon (Z = 6) to krypton (Z = 34), and partly stripped ions up to uranium (Z = 92). Radiographic studies to date have been conducted with helium (from 184-inch cyclotron), carbon, oxygen, and neon beams. Useful ranges in tissue of 40 cm or more are available. To investigate the potential of heavy-ion projection radiography and computed tomography (CT), several methods and instrumentation have been studied.

  15. Radiations from hot nuclei

    NASA Technical Reports Server (NTRS)

    Malik, F. Bary

    1993-01-01

    The investigation indicates that nuclei with excitation energy of a few hundred MeV to BeV are more likely to radiate hot nuclear clusters than neutrons. These daughter clusters could, furthermore, de-excite emitting other hot nuclei, and the chain continues until these nuclei cool off sufficiently to evaporate primarily neutrons. A few GeV excited nuclei could radiate elementary particles preferentially over neutrons. Impact of space radiation with materials (for example, spacecraft) produces highly excited nuclei which cool down emitting electromagnetic and particle radiations. At a few MeV excitation energy, neutron emission becomes more dominant than gamma-ray emission and one often attributes the cooling to take place by successive neutron decay. However, a recent experiment studying the cooling process of 396 MeV excited Hg-190 casts some doubt on this thinking, and the purpose of this investigation is to explore the possibility of other types of nuclear emission which might out-compete with neutron evaporation.

  16. Search for Superheavy Nuclei

    NASA Astrophysics Data System (ADS)

    Hamilton, J. H.; Hofmann, S.; Oganessian, Y. T.

    2013-10-01

    We describe the discoveries of new superheavy nuclei (a) with Z=107-112 produced in cold fusion reactions between 208Pb and 209Bi and beams of A > 50 and (b) with Z=113-118 in hot fusion reactions between actinide nuclei and 48Ca. We also discuss the facilities used in these measurements. We compare the behavior of the β-decay energies and half-lives, spontaneous fission half-lives, cross sections, and excitation functions with expectations from theoretical calculations. Finally, we outline future research directions, including studies of the detailed properties of nuclei synthesized at higher yields, searches for new elements with Z=119 and 120, and developments of new facilities.

  17. Scattering Of Light Nuclei

    SciTech Connect

    Quaglioni, S; Navratil, P; Roth, R

    2009-12-15

    The exact treatment of nuclei starting from the constituent nucleons and the fundamental interactions among them has been a long-standing goal in nuclear physics. Above all nuclear scattering and reactions, which require the solution of the many-body quantum-mechanical problem in the continuum, represent an extraordinary theoretical as well as computational challenge for ab initio approaches.We present a new ab initio many-body approach which derives from the combination of the ab initio no-core shell model with the resonating-group method [4]. By complementing a microscopic cluster technique with the use of realistic interactions, and a microscopic and consistent description of the nucleon clusters, this approach is capable of describing simultaneously both bound and scattering states in light nuclei. We will discuss applications to neutron and proton scattering on sand light p-shell nuclei using realistic nucleon-nucleon potentials, and outline the progress toward the treatment of more complex reactions.

  18. Monopole Strength Function of Deformed Superfluid Nuclei

    SciTech Connect

    Stoitsov, M. V.; Kortelainen, E. M.; Nakatsukasa, T.; Losa, C.; Nazarewicz, Witold

    2011-01-01

    We present an efficient method for calculating strength functions using the finite amplitude method (FAM) for deformed superfluid heavy nuclei within the framework of the nuclear density functional theory. We demonstrate that FAM reproduces strength functions obtained with the fully self-consistent quasi-particle random-phase approximation (QRPA) at a fraction of computational cost. As a demonstration, we compute the isoscalar and isovector monopole strength for strongly deformed configurations in ^{240}Pu by considering huge quasi-particle QRPA spaces. Our approach to FAM, based on Broyden's iterative procedure, opens the possibility for large-scale calculations of strength distributions in well-bound and weakly bound nuclei across the nuclear landscape.

  19. Disintegration of comet nuclei

    NASA Astrophysics Data System (ADS)

    Ksanfomality, Leonid V.

    2012-02-01

    The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies.

  20. THE SURVIVAL OF NUCLEI IN JETS ASSOCIATED WITH CORE-COLLAPSE SUPERNOVAE AND GAMMA-RAY BURSTS

    SciTech Connect

    Horiuchi, Shunsaku; Murase, Kohta; Ioka, Kunihito; Meszaros, Peter

    2012-07-01

    Heavy nuclei such as nickel-56 are synthesized in a wide range of core-collapse supernovae (CCSN), including energetic supernovae associated with gamma-ray bursts (GRBs). Recent studies suggest that jet-like outflows are a common feature of CCSN. These outflows may entrain synthesized nuclei at launch or during propagation, and provide interesting multi-messenger signals including heavy ultra-high-energy cosmic rays. Here, we investigate the destruction processes of nuclei during crossing from the stellar material into the jet material via a cocoon, and during propagation after being successfully loaded into the jet. We find that nuclei can survive for a range of jet parameters because collisional cooling is faster than spallation. While canonical high-luminosity GRB jets may contain nuclei, magnetic-dominated models or low-luminosity jets with small bulk Lorentz factors are more favorable for having a significant heavy nuclei component.

  1. Cosmic-ray electron injection from the ionization of nuclei.

    PubMed

    Morlino, Giovanni

    2009-09-18

    We show that the secondary electrons ejected from the ionization of heavy ions can be injected into the acceleration process that occurs at supernova remnant shocks. This electron injection mechanism works since ions are ionized during the acceleration when they move already with relativistic speed, just like ejected electrons do. Using the abundances of heavy nuclei measured in cosmic rays measured at the Earth, we estimate the electron/proton ratio at the source to be approximately 10;{-4}, big enough to account for the nonthermal synchrotron emission observed in young supernova remnants. We also show that the ionization process can limit the maximum energy that heavy ions can reach.

  2. Evaporation of particles from hot nuclei

    NASA Astrophysics Data System (ADS)

    Zejun, He; Jianshi, Wu; Wolfgang, Nörenberg

    1988-11-01

    For particle evaporation from hot nuclei a model is proposed which is applicable to high excitation energies where the mean free path of nucleons becomes comparable to or smaller than the size of the nucleus. The formalism allows to calculate the time evolution of the emitting system and the evaporation rates and spectra of the emitted particles. The nucleus 133Cs with an initial temperature of 18 MeV is studied as an example. Implications for intermediate-energy heavy-ion collisions are indicated.

  3. Exotic atomic nuclei

    NASA Astrophysics Data System (ADS)

    Hamilton, J. H.; Maruhn, J. A.

    1986-07-01

    From the study of nuclei with abundances of neutrons and protons (N numbers and Z numbers) quite different from those found in nature, it has been possible to gain new views of motions and structures within nuclear matter. Based on the spherical shell model of the nucleus proposed by Mayer and Jensen in 1949 and the collective model of nuclear deformation proposed in 1952 by Bohr and Mottelson, it has come to be possible to decide what shape or shapes a nucleus must have for a given set of N and Z numbers. It turns out that not only spherical nuclei are possible but also prolate and oblate spheroids (football and discus shaped), triaxial (like a partially deflated football), and even pear- or peanut-shaped. A significant experimental tool in such studies is the ISOL or Isotope-Separator, On-Line, which makes possible the construction of energy level diagrams from the study of exotic nuclei created when particles from accelerators strike various kinds of foil. The significance of magic numbers and super-magic numbers (particular combinations of N and Z) for the stability of various exotic nuclei is considered. International facilities engaged in such studies are noted.

  4. Physics with Polarized Nuclei.

    ERIC Educational Resources Information Center

    Thompson, William J.; Clegg, Thomas B.

    1979-01-01

    Discusses recent advances in polarization techniques, specifically those dealing with polarization of atomic nuclei, and how polarized beams and targets are produced. These techniques have greatly increased the scope of possible studies, and provided the tools for testing fundamental symmetries and the spin dependence of nuclear forces. (GA)

  5. Population of Nuclei Via 7Li-Induced Binary Reactions

    SciTech Connect

    Clark, Rodney M.; Phair, Larry W.; Descovich, M.; Cromaz, Mario; Deleplanque, M.A.; Fall on, Paul; Lee, I-Yang; Macchiavelli, A.O.; McMahan, Margaret A.; Moretto, Luciano G.; Rodriguez-Vieitez, E.; Sinha,Shrabani; Stephens, Frank S.; Ward, David; Wiedeking, Mathis

    2005-08-08

    The authors have investigated the population of nuclei formed in binary reactions involving {sup 7}Li beams on targets of {sup 160}Gd and {sup 184}W. The {sup 7}Li + {sup 184}W data were taken in the first experiment using the LIBERACE Ge-array in combination with the STARS Si {Delta}E-E telescope system at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. By using the Wilczynski binary transfer model, in combination with a standard evaporation model, they are able to reproduce the experimental results. This is a useful method for predicting the population of neutron-rich heavy nuclei formed in binary reactions involving beams of weakly bound nuclei formed in binary reactions involving beams of weakly bound nuclei and will be of use in future spectroscopic studies.

  6. Energetic Nuclei, Superdensity and Biomedicine

    ERIC Educational Resources Information Center

    Baldin, A. M.

    1977-01-01

    High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…

  7. Energetic Nuclei, Superdensity and Biomedicine

    ERIC Educational Resources Information Center

    Baldin, A. M.

    1977-01-01

    High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…

  8. Exotic phenomena in nuclei

    NASA Astrophysics Data System (ADS)

    Neff, Thomas; Feldmeier, Hans; Roth, Robert

    2006-10-01

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

  9. Nuclei and Fundamental Symmetries

    NASA Astrophysics Data System (ADS)

    Haxton, Wick

    2016-09-01

    Nuclei provide marvelous laboratories for testing fundamental interactions, often enhancing weak processes through accidental degeneracies among states, and providing selection rules that can be exploited to isolate selected interactions. I will give an overview of current work, including the use of parity violation to probe unknown aspects of the hadronic weak interaction; nuclear electric dipole moment searches that may shed light on new sources of CP violation; and tests of lepton number violation made possible by the fact that many nuclei can only decay by rare second-order weak interactions. I will point to opportunities in both theory and experiment to advance the field. Based upon work supported in part by the US Department of Energy, Office of Science, Office of Nuclear Physics and SciDAC under Awards DE-SC00046548 (Berkeley), DE-AC02-05CH11231 (LBNL), and KB0301052 (LBNL).

  10. Isomeric Decay Studies in Neutron-Rich N ≈ 126 Nuclei

    NASA Astrophysics Data System (ADS)

    Steer, S. J.; Podolyák, Zs.; Pietri, S.; Górska, M.; Farrelly, G. F.; Regan, P. H.; Rudolph, D.; Garnsworthy, A. B.; Hoischen, R.; Gerl, J.; Wollersheim, H. J.; Grawe, H.; Maier, K. H.; Becker, F.; Bednarczyk, P.; Cáceres, L.; Doornenbal, P.; Geissel, H.; GrȨBOSZ, J.; Kelic, A.; Kojouharov, I.; Kurz, N.; Montes, F.; Prokopowicz, W.; Saito, T.; Schaffner, H.; Tashenov, S.; Heinz, A.; Kurtukian-Nieto, T.; Benzoni, G.; Pfützner, M.; Jungclaus, A.; Balabanski, D. L.; Brandau, C.; Brown, A.; Bruce, A. M.; Catford, W. N.; Cullen, I. J.; Dombrádi, Zs.; Estevez, M. E.; Gelletly, W.; Ilie, G.; Jolie, J.; Jones, G. A.; Kmiecik, M.; Kondev, F. G.; Krücken, R.; Lalkovski, S.; Liu, Z.; Maj, A.; Myalski, S.; Schwertel, S.; Shizuma, T.; Walker, P. M.; Werner-Malento, E.; Wieland, O.

    Heavy neutron-rich nuclei were populated via relativistic energy fragmentation of a E/A = 1 GeV 208Pb beam. The nuclei of interest were selected and identified by a fragment separator and then implanted in a passive plastic stopper. Delayed γ rays following internal isomeric decays were detected by the RISING array. Experimental information was obtained on a number of nuclei with Z = 73-80 (Ta-Hg), providing new information both on the prolate-oblate transitional region as well as on the N = 126 closed shell nuclei.

  11. Covariant Density Functional Theory For Isospin Properties In Nuclei Far From Stability

    SciTech Connect

    Ring, P.; Lalazissis, G.A.; Niksic, T.; Vretenar, D.

    2005-04-05

    In recent years Covariant Density Functional Theory (CDFT) has been very successful for the description of ground state properties of nuclei all over the periodic table. Isospin properties of nuclei far from the valley of stability are used to improve the existing functionals. Modern parameter sets of the corresponding Lagrangian density are adjusted carefully to characteristic nuclei with explicit density dependence of the meson-nucleon couplings. They are tested in relativistic Hartree-Bogoliubov calculations of nuclear ground-states, in particular for the calculation of masses, and they are applied to the analysis of very recent data on super-heavy nuclei.

  12. Static and dynamic aspect of covariant density functional theory in proton rich nuclei

    SciTech Connect

    Ring, P.; Lalazissis, G. A.; Paar, N.; Vretenar, D.

    2007-11-30

    Proton rich nuclei are investigated in the framework of Covariant Density Functional Theory (CDFT). The Relativistic Hartree Bogoliubov (RHB) model is used to study the proton drip line in the region of heavy and superheavy nuclei. The dynamical behavior of nuclei with a large proton excess is studied within the Relativistic Quasiparticle Random Phase Approximation (RQRPA). Low lying El-strength is observed and it is shown that it corresponds to an oscillation of the proton skin against the isospin saturated neutron-proton core. This mode is in full analogy to the neutron pygmy resonances found in many nuclei with neutron excess.

  13. Leading twist nuclear shadowing phenomena in hard processes with nuclei

    DOE PAGES

    L. Franfurt; Guzey, V.; Strikman, M.

    2012-01-08

    We present and discuss the theory and phenomenology of the leading twist theory of nuclear shadowing which is based on the combination of the generalization of Gribov-Glauber theory, QCD factorization theorems, and HERA QCD analysis of diffraction in lepton-proton deep inelastic scattering (DIS). We apply this technique for the analysis of a wide range of hard processes with nuclei-inclusive DIS on deuterons, medium-range and heavy nuclei, coherent and incoherent diffractive DIS with nuclei, and hard diffraction in proton-nucleus scattering - and make predictions for the effect of nuclear shadowing in the corresponding sea quark and gluon parton distributions. We alsomore » analyze the role of the leading twist nuclear shadowing in generalized parton distributions in nuclei and certain characteristics of final states in nuclear DIS. We discuss the limits of applicability of the leading twist approximation for small x scattering off nuclei and the onset of the black disk regime and methods of detecting it. It will be possible to check many of our predictions in the near future in the studies of the ultraperipheral collisions at the Large Hadron Collider (LHC). Further checks will be possible in pA collisions at the LHC and forward hadron production at Relativistic Heavy Ion Collider (RHIC). As a result, detailed tests will be possible at an Electon-Ion Collider (EIC) in USA and at the Large Hadron-Electron Collider (LHeC) at CERN.« less

  14. Leading twist nuclear shadowing phenomena in hard processes with nuclei

    SciTech Connect

    L. Franfurt; Guzey, V.; Strikman, M.

    2012-01-08

    We present and discuss the theory and phenomenology of the leading twist theory of nuclear shadowing which is based on the combination of the generalization of Gribov-Glauber theory, QCD factorization theorems, and HERA QCD analysis of diffraction in lepton-proton deep inelastic scattering (DIS). We apply this technique for the analysis of a wide range of hard processes with nuclei-inclusive DIS on deuterons, medium-range and heavy nuclei, coherent and incoherent diffractive DIS with nuclei, and hard diffraction in proton-nucleus scattering - and make predictions for the effect of nuclear shadowing in the corresponding sea quark and gluon parton distributions. We also analyze the role of the leading twist nuclear shadowing in generalized parton distributions in nuclei and certain characteristics of final states in nuclear DIS. We discuss the limits of applicability of the leading twist approximation for small x scattering off nuclei and the onset of the black disk regime and methods of detecting it. It will be possible to check many of our predictions in the near future in the studies of the ultraperipheral collisions at the Large Hadron Collider (LHC). Further checks will be possible in pA collisions at the LHC and forward hadron production at Relativistic Heavy Ion Collider (RHIC). As a result, detailed tests will be possible at an Electon-Ion Collider (EIC) in USA and at the Large Hadron-Electron Collider (LHeC) at CERN.

  15. Potential energy surfaces of superheavy nuclei

    SciTech Connect

    Bender, M.; Rutz, K.; Maruhn, J.A.; Greiner, W.; Reinhard, P.-G. Rutz, K.; Maruhn, J.A.; Greiner, W.

    1998-10-01

    We investigate the structure of the potential energy surfaces of the superheavy nuclei {sub 158}{sup 258}Fm{sub 100}, {sub 156}{sup 264}Hs{sub 108}, {sub 166}{sup 278}112, {sub 184}{sup 298}114, and {sub 172}{sup 292}120 within the framework of self-consistent nuclear models, i.e., the Skyrme-Hartree-Fock approach and the relativistic mean-field model. We compare results obtained with one representative parametrization of each model which is successful in describing superheavy nuclei. We find systematic changes as compared to the potential energy surfaces of heavy nuclei in the uranium region: there is no sufficiently stable fission isomer any more, the importance of triaxial configurations to lower the first barrier fades away, and asymmetric fission paths compete down to rather small deformation. Comparing the two models, it turns out that the relativistic mean-field model gives generally smaller fission barriers. {copyright} {ital 1998} {ital The American Physical Society}

  16. Fission Barriers of Compound Superheavy Nuclei

    SciTech Connect

    Pei, Junchen; Nazarewicz, Witold; Sheikh, J. A.; Kerman, A. K.

    2009-01-01

    The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. We study the temperature-dependent fission barriers by means of the self-consistent nuclear density functional theory. The equivalence of isothermal and isentropic descriptions is demonstrated. The effect of the particle gas is found to be negligible in the range of temperatures studied. Calculations have been carried out for ^{264}Fm, ^{272}Ds, ^{278}112, ^{292}114, and ^{312}124. For nuclei around ^{278}112 produced in "cold fusion" reactions, we predict a more rapid decrease of fission barriers with temperature as compared to the nuclei around ^{292}114 synthesized in "hot fusion" experiments. This is explained in terms of the difference between the ground-state and fission-barrier temperatures. Our calculations are consistent with the long survival probabilities of the superheavy elements produced in Dubna with the ^{48}Ca beam.

  17. Fission Barriers of Compound Superheavy Nuclei

    NASA Astrophysics Data System (ADS)

    Nazarewicz, Witold

    2010-02-01

    The dependence of fission barriers on the excitation energy of the compound nucleus impacts the survival probability of superheavy nuclei synthesized in heavy-ion fusion reactions. In this work [1,2], we investigate the isentropic fission barriers by means of the self-consistent nuclear density functional theory. The relationship between isothermal and isentropic descriptions is demonstrated. Calculations have been carried out for ^264Fm, ^272Ds, ^278Cp, ^292114, and ^312124. For nuclei around ^278Cp produced in ``cold fusion" reactions, we predict a more rapid decrease of fission barriers with excitation energy as compared to the nuclei around ^292114 synthesized in ``hot fusion'' experiments. This is explained in terms of the difference between the ground-state and saddle-point temperatures. [4pt] [1] J.C. Pei, W. Nazarewicz, J.A. Sheikh and A.K. Kerman, Phys. Rev. Lett. 102, 192501 (2009).[0pt] [2] J.A. Sheikh, W. Nazarewicz, and J.C. Pei, Phys. Rev. C 80, 011302(R) (2009). )

  18. Positrons from heavy ions: A puzzle for physicists

    SciTech Connect

    Mueller, B.

    1986-10-15

    A review of experimental data and models for positron production in relativistic heavy ion reactions is presented. The mass range of nuclei is A = 180--247 (nuclear charge range is Z1+Z2 = 163--188). (AIP)

  19. How the Pauli exclusion principle affects fusion of atomic nuclei

    NASA Astrophysics Data System (ADS)

    Simenel, C.; Umar, A. S.; Godbey, K.; Dasgupta, M.; Hinde, D. J.

    2017-03-01

    The Pauli exclusion principle induces a repulsion between composite systems of identical fermions such as colliding atomic nuclei. Our goal is to study how heavy-ion fusion is impacted by this "Pauli repulsion." We propose a new microscopic approach, the density-constrained frozen Hartree-Fock method, to compute the bare potential including the Pauli exclusion principle exactly. Pauli repulsion is shown to be important inside the barrier radius and increases with the charge product of the nuclei. Its main effect is to reduce tunneling probability. Pauli repulsion is part of the solution to the long-standing deep sub-barrier fusion hindrance problem.

  20. Fusion-fission of superheavy nuclei and clustering phenomena

    NASA Astrophysics Data System (ADS)

    Itkis, M. G.; Itkis, I. M.; Knyazheva, G. N.; Kozulin, E. M.

    2017-06-01

    Results of the study of mass-energy distributions of binary fragments for a wide range of nuclei with Z = 82-122 produced in reactions with heavy ions at energies close and below the Coulomb barrier are reported. 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 quasifission processes are discussed. The observed peculiarities of the mass and energy distributions of reaction fragments are determined by the shell structure of the formed fragments.

  1. Properties of Cometary Nuclei

    NASA Technical Reports Server (NTRS)

    Rahe, J.; Vanysek, V.; Weissman, P. R.

    1994-01-01

    Active long- and short-period comets contribute about 20 to 30 % of the major impactors on the Earth. Cometary nuclei are irregular bodies, typically a few to ten kilometers in diameter, with masses in the range 10(sup 15) to 10(sup 18) g. The nuclei are composed of an intimate mixture of volatile ices, mostly water ice and hydrocarbon and silicate grains. The composition is the closest to solar composition of any known bodies in the solar system. The nuclei appear to be weakly bonded agglomerations of smaller icy planetesimals, and material strengths estimated from observed tidal disruption events are fairly low, typically 10(sup 2) to 10(sup 4) N m(sup -2). Density estimates range between 0.2 and 1.2 g cm(sup -3) but are very poorly determined, if at all. As comets age they develop nonvolitile crusts on their surfaces which eventually render them inactive, similar in appearance to carbonaceous asteroids. However, dormant comets may continue to show sporadic activity and outbursts for some time before they become truly extinct. The source of the long-period comets is the Oort cloud, a vast spherical cloud of perhaps 10(sup 12) to 10(sup 13) comets surrounding the solar system and extending to interstellar distances. The likely source for short-period comets is the Kuiper belt. a ring of perhaps 10(sup 8) to 10(sup 10) remnant icy planetesimals beyond the orbit of Neptune, though some short-period comets may also be long-period comets from the Oort cloud which have been perturbed into short-period orbits.

  2. Skyrmions and Nuclei

    NASA Astrophysics Data System (ADS)

    Battye, R. A.; Manton, N. S.; Sutcliffe, P. M.

    We review recent work on the modelling of atomic nuclei as quantised Skyrmions, using Skyrme's original model with pion fields only. Skyrmions are topological soliton solutions, whose conserved topological charge B is identified with the baryon number of a nucleus. Apart from an energy and length scale, the Skyrme model has just one dimensionless parameter m, proportional to the pion mass. It has been found that a good fit to experimental nuclear data requires m to be of order 1. The Skyrmions for B up to 7 have been known for some time, and are qualitatively insensitive to whether m is zero or of order 1. However, for baryon numbers B = 8 and above, the Skyrmions have quite a compact structure for m of order 1, rather than the hollow polyhedral structure found when m = 0. One finds for baryon numbers which are multiples of four, that the Skyrmions are composed of B = 4 sub-units, as in the α-particle model of nuclei. The rational map ansatz gives a useful approximation to the Skyrmion solutions for all baryon numbers when m = 0. For m of order 1, it gives a good approximation for baryon numbers up to 7, and generalisations of this ansatz are helpful for higher baryon numbers. We briefly review the work from the 1980s and 90s on the semiclassical rigidbody quantisation of Skyrmions for B = 1, 2, 3 and 4. We then discuss more recent work extending this method to B = 6, 7, 8, 10 and 12. We determine the quantum states of the Skyrmions, finding their spins, isospins and parities, and compare with the experimental data on the ground and excited states of nuclei up to mass number 12.

  3. Total photoabsorption in nuclei

    SciTech Connect

    Bianchi, N.

    1992-06-01

    The Frascati-Genova collaboration proposes to measure the total photonuclear cross section on a wide range of nuclei between 500 MeV and 2 GeV, to obtain informations on the interaction of baryon resonances with nucleons and on the onset of the shadowing effect. The experiment could be performed in the Hall B as soon as the tagging facility will be ready and before the end of the installation of the CLAS spectrometer. The requirements for the photon beam, like maximum energy, intensity and beam definition, are not so strong so that the experiment would also be a good first test of the tagged photon facility.

  4. Electroproduction of Strange Nuclei

    SciTech Connect

    E.V. Hungerford

    2002-06-01

    The advent of high-energy, CW-beams of electrons now allows electro-production and precision studies of nuclei containing hyperons. Previously, the injection of strangeness into a nucleus was accomplished using secondary beams of mesons, where beam quality and target thickness limited the missing mass resolution. We review here the theoretical description of the (e, e'K+) reaction mechanism, and discuss the first experiment demonstrating that this reaction can be used to precisely study the spectra of light hypernuclei. Future experiments based on similar techniques, are expected to attain even better resolutions and rates.

  5. Lattice QCD for nuclei

    NASA Astrophysics Data System (ADS)

    Beane, Silas

    2016-09-01

    Over the last several decades, theoretical nuclear physics has been evolving from a very-successful phenomenology of the properties of nuclei, to a first-principles derivation of the properties of visible matter in the Universe from the known underlying theories of Quantum Chromodynamics (QCD) and Electrodynamics. Many nuclear properties have now been calculated using lattice QCD, a method for treating QCD numerically with large computers. In this talk, some of the most recent results in this frontier area of nuclear theory will be reviewed.

  6. Population of Nuclei Via 7Li-Induced Binary Reactions

    SciTech Connect

    Clark, R M; Phair, L W; Descovich, M; Cromaz, M; Deleplanque, M A; Fallon, P; Lee, I Y; Macchiavelli, A O; McMahan, M A; Moretto, L G; Rodriguez-Vieitez, E; Sinha, S; Stephens, F S; Ward, D; Wiedeking, M; Bernstein, L A; Burke, J T; Church, J A

    2005-08-09

    The authors have investigated the population of nuclei formed in binary reactions involving {sup 7}Li beams on targets of {sup 160}Gd and {sup 184}W. The {sup 7}Li + {sup 184}W data were taken in the first experiment using the LIBERACE Ge-array in combination with the STARS Si {Delta}E-E telescope system at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. By using the Wilczynski binary transfer model, in combination with a standard evaporation model, they are able to reproduce the experimental results. This is a useful method for predicting the population of neutron-rich heavy nuclei formed in binary reactions involving beams of weakly bound nuclei and will be of use in future spectroscopic studies.

  7. Formation of superheavy nuclei in cold fusion reactions

    SciTech Connect

    Feng Zhaoqing; Jin Genming; Li Junqing; Scheid, Werner

    2007-10-15

    Within the concept of the dinuclear system (DNS), a dynamical model is proposed for describing the formation of superheavy nuclei in complete fusion reactions by incorporating the coupling of the relative motion to the nucleon transfer process. The capture of two heavy colliding nuclei, the formation of the compound nucleus, and the de-excitation process are calculated by using an empirical coupled channel model, solving a master equation numerically and applying statistical theory, respectively. Evaporation residue excitation functions in cold fusion reactions are investigated systematically and compared with available experimental data. Maximal production cross sections of superheavy nuclei in cold fusion reactions with stable neutron-rich projectiles are obtained. Isotopic trends in the production of the superheavy elements Z=110, 112, 114, 116, 118, and 120 are analyzed systematically. Optimal combinations and the corresponding excitation energies are proposed.

  8. Effective field theory for vibrations in odd-mass nuclei

    NASA Astrophysics Data System (ADS)

    Coello Pérez, E. A.; Papenbrock, T.

    2016-11-01

    Heavy even-even nuclei exhibit low-energy collective excitations that are separated in scale from the microscopic (fermion) degrees of freedom. This separation of scale allows us to approach nuclear vibrations within an effective field theory (EFT). In odd-mass nuclei collective and single-particle properties compete at low energies, and this makes their description more challenging. In this article we describe spherical odd-mass nuclei with ground-state spin I =1/2 by means of an EFT that couples a fermion to the collective degrees of freedom of an even-even core. The EFT relates observables such as energy levels, electric quadrupole transition strengths, and magnetic dipole moments of the odd-mass nucleus to those of its even-even neighbor and allows us to quantify theoretical uncertainties. For isotopes of rhodium and silver the theoretical description is consistent with data within experimental and theoretical uncertainties. Several testable predictions are made.

  9. Beta decay rates of neutron-rich nuclei

    SciTech Connect

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

    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.

  10. Heaviest Nuclei: New Element with Atomic Number 117

    ScienceCinema

    Oganessian, Yuri [Flerov Laboratory of Nuclear Reactions, Russia and Joint Institute for Nuclear Research

    2016-07-12

    One of the fundamental outcomes of the nuclear shell model is the prediction of the 'stability islands' in the domain of the hypothetical super heavy elements. The talk is devoted to the experimental verification of these predictions - the synthesis and study of both the decay and chemical properties of the super heavy elements. The discovery of a new chemical element with atomic number Z=117 is reported. The isotopes 293117 and 294117 were produced in fusion reactions between 48Ca and 249Bk. Decay chains involving 11 new nuclei were identified by means of the Dubna gas-filled recoil separator. The measured decay properties show a strong rise of stability for heavier isotopes with Z =111, validating the concept of the long sought island of enhanced stability for heaviest nuclei.

  11. Exotic nuclei in astrophysics

    NASA Astrophysics Data System (ADS)

    Penionzhkevich, Yu. E.

    2012-07-01

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

  12. Nucleomorphs: enslaved algal nuclei.

    PubMed

    Cavalier-Smith, T

    2002-12-01

    Nucleomorphs of cryptomonad and chlorarachnean algae are the relict, miniaturised nuclei of formerly independent red and green algae enslaved by separate eukaryote hosts over 500 million years ago. The complete 551 kb genome sequence of a cryptomonad nucleomorph confirms that cryptomonads are eukaryote-eukaryote chimeras and greatly illuminates the symbiogenetic event that created the kingdom Chromista and their alveolate protozoan sisters. Nucleomorph membranes may, like plasma membranes, be more enduring after secondary symbiogenesis than are their genomes. Partial sequences of chlorarachnean nucleomorphs indicate that genomic streamlining is limited by the mutational difficulty of removing useless introns. Nucleomorph miniaturisation emphasises that selection can dramatically reduce eukaryote genome size and eliminate most non-functional nuclear non-coding DNA. Given the differential scaling of nuclear and nucleomorph genomes with cell size, it follows that most non-coding nuclear DNA must have a bulk-sequence-independent function related to cell volume.

  13. Pulsars:. Gigantic Nuclei

    NASA Astrophysics Data System (ADS)

    Xu, Renxin

    What is the real nature of pulsars? This is essentially a question of the fundamental strong interaction between quarks at low-energy scale and hence of the non-perturbative quantum chromo-dynamics, the solution of which would certainly be meaningful for us to understand one of the seven millennium prize problems (i.e., "Yang-Mills Theory") named by the Clay Mathematical Institute. After a historical note, it is argued here that a pulsar is very similar to an extremely big nucleus, but is a little bit different from the gigantic nucleus speculated 80 years ago by L. Landau. The paper demonstrates the similarity between pulsars and gigantic nuclei from both points of view: the different manifestations of compact stars and the general behavior of the strong interaction.

  14. Ultrahigh energy cosmic ray nuclei from remnants of dead quasars

    NASA Astrophysics Data System (ADS)

    Moncada, Roberto J.; Colon, Rafael A.; Guerra, Juan J.; O'Dowd, Matthew J.; Anchordoqui, Luis A.

    2017-03-01

    We re-examine the possibility of ultrahigh energy cosmic rays being accelerated in nearby dormant quasars. We particularize our study to heavy nuclei to accommodate the spectrum and nuclear composition recently reported by the Pierre Auger Collaboration. Particle acceleration is driven by the Blandford-Znajek mechanism, which wires the dormant spinning black holes as Faraday unipolar dynamos. We demonstrate that energy losses are dominated by photonuclear interactions on the ambient photon fields. We argue that the local dark fossils of the past quasar activity can be classified on the basis of how source parameters (mass of the central engine and photon background surrounding the accelerator) impact the photonuclear interaction. In this classification it is possible to distinguish two unequivocal type of sources: those in which nuclei are completely photodisintegrated before escaping the acceleration region and those in which photopion production is the major energy damping mechanism. We further argue that the secondary nucleons from the photodisintegrated nuclei (which have a steep spectral index at injection) can populate the energy region below ;the ankle; feature in the cosmic ray spectrum, whereas heavy and medium mass nuclei (with a harder spectral index) populate the energy region beyond ;the ankle;, all the way to the high energy end of the spectrum. In addition, we show that five potential quasar remnants from our cosmic backyard correlate with the hot-spot observed by the Telescope Array.

  15. Compton scattering by nuclei

    NASA Astrophysics Data System (ADS)

    Hütt, M.-Th.; L'vov, A. I.; Milstein, A. I.; Schumacher, M.

    2000-01-01

    The concept of Compton scattering by even-even nuclei from giant-resonance to nucleon-resonance energies and the status of experimental and theoretical researches in this field are outlined. The description of Compton scattering by nuclei starts from different complementary approaches, namely from second-order S-matrix and from dispersion theories. Making use of these, it is possible to incorporate into the predicted nuclear scattering amplitudes all the information available from other channels, viz. photon-nucleon and photon-meson channels, and to efficiently make use of models of the nucleon, the nucleus and the nucleon-nucleon interaction. The total photoabsorption cross section constrains the nuclear scattering amplitude in the forward direction. The specific information obtained from Compton scattering therefore stems from the angular dependence of the nuclear scattering amplitude, providing detailed insight into the dynamics of the nuclear and nucleon degrees of freedom and into the interplay between them. Nuclear Compton scattering in the giant-resonance energy-region provides information on the dynamical properties of the in-medium mass of the nucleon. Most prominently, the electromagnetic polarizabilities of the nucleon in the nuclear medium can be extracted from nuclear Compton scattering data obtained in the quasi-deuteron energy-region. In our description of this latter process special emphasis is laid upon the exploration of many-body and two-body effects entering into the nuclear dynamics. Recent results are presented for two-body effects due to the mesonic seagull amplitude and due to the excitation of nucleon internal degrees of freedom accompanied by meson exchanges. Due to these studies the in-medium electromagnetic polarizabilities are by now well understood, whereas the understanding of nuclear Compton scattering in the Δ-resonance range is only at the beginning. Furthermore, phenomenological methods how to include retardation effects in the

  16. Interaction of eta mesons with nuclei

    NASA Astrophysics Data System (ADS)

    Kelkar, N. G.; Khemchandani, K. P.; Upadhyay, N. J.; Jain, B. K.

    2013-06-01

    Back in the mid-1980s, a new branch of investigation related to the interaction of eta mesons with nuclei came into existence. It started with the theoretical prediction of possible exotic states of eta mesons and nuclei bound by the strong interaction and later developed into an extensive experimental program to search for such unstable states as well as understand the underlying interaction via eta-meson producing reactions. The vast literature of experimental as well as theoretical works that studied various aspects of eta-producing reactions such as the π+n → ηp, pd → 3Heη, p 6Li → 7Be η and γ 3He → η X, to name a few, had but one objective in mind: to understand the eta-nucleon (ηN) and hence the η-nucleus interaction which could explain the production data and confirm the existence of some η-mesic nuclei. In spite of these efforts, there remain uncertainties in the knowledge of the ηN and hence the η-nucleus interaction. Therefore, this review is an attempt to bind together the findings in these works and draw some global and specific conclusions which can be useful for future explorations. The ηN scattering length (which represents the strength of the η-nucleon interaction) using different theoretical models and analyzing the data on η production in pion, photon and proton induced reactions was found to be spread out in a wide range, namely, 0.18 ⩽ ℜe aηN ⩽ 1.03 fm and 0.16 ⩽ ℑm aηN ⩽ 0.49 fm. Theoretical searches of heavy η-mesic nuclei based on η-nucleus optical potentials and lighter ones based on Faddeev type few-body approaches predict the existence of several quasibound and resonant states. Although some hints of η-mesic states such as ^3_{\\eta} He and ^{25}_{\\eta} Mg do exist from previous experiments, the promise of clearer signals for the existence of η-mesic nuclei lies in the experiments to be performed at the J-PARC, MAMI and COSY facilities in the near future. This review is aimed at giving an overall

  17. Interaction of eta mesons with nuclei.

    PubMed

    Kelkar, N G; Khemchandani, K P; Upadhyay, N J; Jain, B K

    2013-06-01

    Back in the mid-1980s, a new branch of investigation related to the interaction of eta mesons with nuclei came into existence. It started with the theoretical prediction of possible exotic states of eta mesons and nuclei bound by the strong interaction and later developed into an extensive experimental program to search for such unstable states as well as understand the underlying interaction via eta-meson producing reactions. The vast literature of experimental as well as theoretical works that studied various aspects of eta-producing reactions such as the π(+)n → ηp, pd → (3)Heη, p (6)Li → (7)Be η and γ (3)He → η X, to name a few, had but one objective in mind: to understand the eta-nucleon (ηN) and hence the η-nucleus interaction which could explain the production data and confirm the existence of some η-mesic nuclei. In spite of these efforts, there remain uncertainties in the knowledge of the ηN and hence the η-nucleus interaction. Therefore, this review is an attempt to bind together the findings in these works and draw some global and specific conclusions which can be useful for future explorations.The ηN scattering length (which represents the strength of the η-nucleon interaction) using different theoretical models and analyzing the data on η production in pion, photon and proton induced reactions was found to be spread out in a wide range, namely, 0.18 ≤ Re aηN ≤ 1.03 fm and 0.16 ≤ Rm aηN ≤ 0.49 fm. Theoretical searches of heavy η-mesic nuclei based on η-nucleus optical potentials and lighter ones based on Faddeev type few-body approaches predict the existence of several quasibound and resonant states. Although some hints of η-mesic states such as (3)(η)He and (25)(η)Mg do exist from previous experiments, the promise of clearer signals for the existence of η-mesic nuclei lies in the experiments to be performed at the J-PARC, MAMI and COSY facilities in the near future. This review is aimed at giving an overall status

  18. Quarks in Few Body Nuclei

    NASA Astrophysics Data System (ADS)

    Holt, Roy J.

    2016-03-01

    Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass-3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon.

  19. Mean field and collisions in hot nuclei

    SciTech Connect

    K /umlt o/hler, H.S.

    1989-06-01

    Collisions between heavy nuclei produce nuclear matter of high density and excitation. Brueckner methods are used to calculate the momentum and temperature dependent mean field for nucleons propagating through nuclear matter during these collisions. The mean field is complex and the imaginary part is related to the ''two-body'' collision, while the real part relates to ''one-body'' collisions. A potential model for the N-N interactions is avoided by calculating the Reaction matrix directly from the T-matrix (i.e., N-N phase shifts) using a version of Brueckner theory previously published by the author. Results are presented for nuclear matter at normal and twice normal density and for temperatures up to 50 MeV. 23 refs., 7 figs.

  20. Tilted foil polarization of radioactive beam nuclei

    NASA Astrophysics Data System (ADS)

    Goldring, Gvirol

    1992-11-01

    Tilted foil polarization has up to now been mostly applied to nuclear reaction products recoiling out of a target traversed by a primary particle beam. Being a universal phenomenon it can be applied equally well to beams of particles, primary or secondary, radioactive or other. There are however some technical considerations arising from the nature of the beam particles. Radioactive beams are associated with ground state nuclei. They usually have low nuclear spin and as a consequence-as will be shown later-low polarization. Secondary beams are usually low in intensity and do not impose any constraints on the foils they traverse; unlike intense primary heavy ion beams which, if they traverse the foils, essentially limit the foil material to carbon. We review here briefly the tilted foil polarization process and then discuss an experiment with an isomer beam. Finally we review experiments with radioactive beams, past, present and planned for the future.

  1. Dielectronic Recombination In Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Lukić, D.; Savin, D. W.; Schnell, M.; Brandau, C.; Schmidt, E.; Schippers, S.; Müller, A.; Lestinsky, M.; Sprenger, F.; Wolf, A.; Altun, Z.; Badnell, N. R.

    2006-05-01

    Recent X-ray satelitte observations of active galactic nuclei point out shortcomings in our understanding of low temperature dielectronic recombination (DR) for iron M- shell ions. In order to resolve this issue and to provide reliable iron M-shell DR data for modeling astrophysical plasmas, we are carrying out a series of laboratory measurements using the heavy-ion Test Storage Ring at the Max- Plank-Institute for Nuclear Physics in Heidelberg, Germany. Storage rings are currently the only laboratory method capable of studying low temperature DR. We use our results to produce experimentally- derived DR rate coefficients. We are also providing our data to atomic theorist to benchmark their DR calculations. Here we will report our recent DR results for selected Fe M-shell ions. At temperatures where these ions are predicted to form in photoionized gas, we find a significant discrepancy between our experimental results and previously recommended DR rate coefficients.

  2. Single-particle states in transcurium nuclei.

    SciTech Connect

    Ahmad, I.

    1999-09-30

    Identification of single-particle states in the heaviest known nuclei is important because their energies can be used to test the single-particle potential in these high-Z elements. These states can be identified by studying the decay schemes of very heavy odd-mass nuclides. For neutrons, the heaviest odd-mass nuclide available in milliCurie quantities is the 20-h {sup 255}Fm and for protons the heaviest nuclide available is the 20-d {sup 253}Es. These two isotopes were obtained from the Transplutonium Element Production Program at Oak Ridge and their spectra were measured with high-resolution germanium spectrometers. From the results of these measurements we have identified states in {sup 251}Cf and {sup 249}Bk up to 1 MeV excitation energy.

  3. Gross shell structure at high spin in heavy nuclei

    SciTech Connect

    Deleplanque, Marie-Agnes; Frauendorf, Stefan; Pashkevich, Vitaly V.; Chu, S.Y.; Unzhakova, Anja

    2003-10-07

    Experimental nuclear moments of inertia at high spins along the yrast line have been determined systematically and found to differ from the rigid-body values. The difference is attributed to shell effect and these have been calculated microscopically. The data and quantal calculations are interpreted by means of the semiclassical Periodic Orbit Theory. From this new perspective, features in the moments of inertia as a function of neutron number and spin, as well as their relation to the shell energies can be understood. Gross shell effects persist up to the highest angular momenta observed.

  4. στ+ strength in nuclei

    NASA Astrophysics Data System (ADS)

    Cha, D.

    1983-05-01

    The στ+ strength function is studied with the quasiparticle random phase approximation. The residual interaction modifies the pairing theory strength function in two ways. The particle-hole interaction reduces the overall strength by about a factor of 2, without shifting strength between different levels. The particle-particle interaction does not affect the overall strength, but shifts part of the strength from the lowest excitation to a higher excitation energy region. By comparing the theory with the observed (ft) values of the β+ decay in medium heavy nuclei, we find that an additional quenching is required for the στ+ mode, similar in magnitude to the additional quenching present in other isovector spin-flip transitions. Finally, we predict that there is a large concentration of the στ+ strength at higher excitation energy which cannot be observed by the β+ decay. NUCLEAR STRUCTURE στ+ states in odd-odd mass nuclei between A=100-150. QP-RPA calculation with zero-range interaction. Calculated (ft).

  5. Superheavy nuclei: from predictions to discovery

    NASA Astrophysics Data System (ADS)

    Oganessian, Yu Ts; Sobiczewski, A.; Ter-Akopian, G. M.

    2017-02-01

    A fundamental outcome of modern nuclear microscopic theory is the prediction of the ‘islands of stability’ in the region of hypothetical superheavy elements (SHEs). In a heavy nucleus, going through the large-scale deformation on the way to fission, the motion of single nucleons is coupled with the collective degrees of freedom of the whole system. The most striking effect of this coupling is obtained for the case of fission of the heaviest nuclei, whose existence is defined entirely by the nuclear structure, i.e. by the shell effect. From this point of view, the synthesis and study of properties of superheavy nuclei (SHN) is a direct way for checking the basic statements of the microscopic nuclear theory. On the nuclide map, SHN outline the border of the heaviest nuclear masses. SHN set the limits of the periodic system of chemical elements. The study of possible existence of SHN in nature offers a way for testing different scenarios of astrophysical nucleosynthesis. The paper elucidates experimental approaches, used for testing the theory predictions made about the SHN, and presents the results of the discovery of the ‘stability island’ of SHEs.

  6. On limits of ab initio calculations of pairing gap in nuclei

    SciTech Connect

    Saperstein, E. E.; Baldo, M.; Lombardo, U.; Pankratov, S. S.; Zverev, M. V.

    2011-11-15

    A brief review of recent microscopic calculations of nuclear pairing gap is given. A semi-microscopic model is suggested in which the ab initio effective pairing interaction is supplemented with a small phenomenological addendum. It involves a parameter which is universal for all medium and heavy nuclei. Calculations for several isotopic and isotonic chains of semi-magic nuclei confirm the relevance of the model.

  7. Coupled-Channels Study of α-DECAY Rates for Deformed Nuclei

    NASA Astrophysics Data System (ADS)

    Ni, Dongdong; Ren, Zhongzhou

    The generalized density-dependent cluster model is devoted to calculate α-decay half-lives of spherical and deformed nuclei. The multi-channel cluster model is developed to describe the α-decay fine structure in heavy deformed nuclei, including half-lives and branching ratios. After a brief review of these two models, special cases of the α-decay fine structure are presented. Calculations are separately performed using the coupled-channels and WKB approaches.

  8. Parity violation in nuclei

    SciTech Connect

    Robertson, R.G.H.

    1980-01-01

    A summary of parity violating effects in nuclei is given. Thanks to vigorous experimental and theoretical effort, it now appears that a reasonably well-defined value for the weak isovector ..pi..-nucleon coupling constant can be obtained. There is one major uncertainty in the analysis, namely the M2/E1 mixing ratio for the 2.79 MeV transition in /sup 21/Ne. This quantity is virtually impossible to calculate reliably and must be measured. If it turns out to be much larger than 1, then a null result in /sup 21/Ne is expected no matter what the weak interaction, so an experimental determination is urgently needed. The most promising approach is perhaps a measurement of the pair internal conversion coefficient. Of course, a direct measurement of a pure isovector case is highly desirable, and it is to be hoped that the four ..delta..T = 1 experiments will be pushed still further, and that improved calculations will be made for the /sup 6/Li case. Nuclear parity violation seems to be rapidly approaching an interesting and useful synthesis.

  9. Gluon density in nuclei

    SciTech Connect

    Ayala, A.L.; Ducati, M.B.G.; Levin, E.M.

    1996-10-01

    In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab.

  10. Electric Dipole Moments in Radioactive Nuclei, Tests of Time Reversal Symmetry

    SciTech Connect

    Auerbach, N.

    2010-11-24

    The research of radioactive nuclei opens new possibilities to study fundamental symmetries, such as time reversal and reflection symmetry. Such nuclei often provide conditions to check in an optimal way certain symmetries and the violation of such symmetries. We will discuss the possibility of obtaining improved limits on violation of time reversal symmetry using pear shaped radioactive nuclei. An effective method to test time reversal invariance in the non-strange sector is to measure parity and time reversal violating (T-P-odd) electromagnetic moments, (such as the static electric dipole moment). Parity and time reversal violating components in the nuclear force may produce P-T-odd moments in nuclei which in turn induce such moments in atoms. We will discuss the possibility that in some reflection asymmetric, heavy nuclei (which are radioactive) these moments are enhanced by several orders of magnitude. Present and future experiments, which will test this idea, will be mentioned.

  11. Global systematics of unique parity quasibands in odd-A collective nuclei

    NASA Astrophysics Data System (ADS)

    Bucurescu, D.; Cǎta-Danil, G.; Ivaşcu, M.; Stroe, L.; Ur, C. A.

    1994-04-01

    All known structures in the collective medium and heavy odd-A nuclei, based on the unique parity orbitals g9/2, h11/2, and i13/2, are collected and correlations between the energies within both the favored and unfavored quasibands are analyzed. A first startling result is that irrespective of the nature of the odd particle and the shell model orbital, for most of the nondeformed nuclei the energies within these quasibands, show a universal behavior of an anharmonic vibrator with a constant anharmonicity, identical with that found for the even-even nuclei. Second, the rapid transition between the anharmonic vibrator and the rotor regimes, which takes place in the even-even nuclei, is accompanied, in the adjacent odd-A nuclei, by an equally rapid transition from the anharmonic vibrator to the strong coupling regime.

  12. Heavy Ion Fragmentation Experiments at the Bevatron

    NASA Technical Reports Server (NTRS)

    Heckman, H. H.

    1975-01-01

    Fragmentation processes of heavy nuclei in matter using the heavy-ion capability of the Bevatron were studied. The purpose was to obtain the single particle inclusive spectra of secondary nuclei produced at 0 deg by the fragmentation of heavy ion beam projectiles. The process being examined is B+T yields F + anything, where B is the beam nucleus, T is the target nucleus, and F is the detected fragment. The fragments F are isotopically identified by experimental procedures involving magnetic analysis, energy loss and time-of-flight measurements. Attempts were also made to: (1) measure the total and partial production cross section for all isotopes, (2) test the applicability of high-energy multi-particle interaction theory to nuclear fragmentation, (3) apply the cross-section data and fragmentation probabilities to cosmic ray transport theory, and (4) search for systematic behavior of fragment production as a means to improve existing semi-empirical theories of cross sections.

  13. Scattering of Halo Nuclei at Energies below and around the Coulomb Barrier

    NASA Astrophysics Data System (ADS)

    Borge, M. J. G.; Cubero, M.; Fernández-García, J. P.; Moro, A. M.; Pesudo, V.; Acosta, L.; Alcorta, M.; Alvarez, M. A. G.; Bender, P.; Buchmann, L.; Diget, C. A.; Di Pietro, A.; Escrig, D.; Falou, H. A.; Figuera, P. P.; Fulton, B. R.; Fynbo, H. O. U.; Galaviz, D.; Garnsworthy, A.; Gómez-Camacho, J.; Hackman, G.; Kanungo, R.; Lay, J. A.; Madurga, M.; Martel, I.; Mukha, I.; Nilsson, T.; Rodríguez-Gallardo, M.; Rusek, K.; Sánchez-Benítez, A. M.; Rajabali, M.; Sarazin, F.; Shotter, A.; Tengblad, O.; Unsworth, C.; Walden, P.

    The loosely bound structure of halo nuclei is predicted to affect the collisions with heavy targets at energies around the Coulomb barrier. We report here on the results on a series of experiments done at different facilities to study the behaviour of the scattering of the archetype of the halo nuclei: 6He, 11Li, and 11Be on heavy targets at energies below and around the Coulomb barrier. The results are interpreted in the framework of Continuum-Discretized Coupled-Channel calculations (CDCC). The departure from Rutherford scattering is larger than expected. In first approximation the effect certainly scales with the loosely bound character of the projectile.

  14. New dimensions of the periodic system: superheavy, superneutronic, superstrange, antimatter nuclei

    SciTech Connect

    Greiner, Walter

    2010-12-23

    The possibilities for the extension of the periodic system into the islands of superheavy (SH) elements, to and beyond the neutron drip line and to the sectors of strangeness and antimatter are discussed. The multi-nucleon transfer processes in low-energy damped collisions of heavy actinide nuclei may help us to fill the gap between the nuclei produced in the ''hot'' fusion reactions and the continent of known nuclei. In these reactions we may also investigate the ''island of stability''. In many such collisions the lifetime of the composite giant system consisting of two touching nuclei turns out to be rather long ({>=}10{sup -20} s); sufficient for observing line structure in spontaneous positron emission from super-strong electric fields (vacuum decay), a fundamental QED process not observed yet experimentally. At the neutron-rich sector near the drip line islands and extended ridges of quasistable nuclei are predicted by HF calculations. Such nuclei, as well as very long living superheavy nuclei may be provided in double atomic bomb explosions. A tremendously rich scenario of new nuclear structure emerges with new magic numbers in the strangeness domain. Various production mechanisms are discussed for these objects and for antinuclei in high energy heavy-ion collisions.

  15. New dimensions of the periodic system: superheavy, superneutronic, superstrange, antimatter nuclei

    NASA Astrophysics Data System (ADS)

    Greiner, Walter

    2010-12-01

    The possibilities for the extension of the periodic system into the islands of superheavy (SH) elements, to and beyond the neutron drip line and to the sectors of strangeness and antimatter are discussed. The multi-nucleon transfer processes in low-energy damped collisions of heavy actinide nuclei may help us to fill the gap between the nuclei produced in the "hot" fusion reactions and the continent of known nuclei. In these reactions we may also investigate the "island of stability". In many such collisions the lifetime of the composite giant system consisting of two touching nuclei turns out to be rather long (≥10-20 s); sufficient for observing line structure in spontaneous positron emission from super-strong electric fields (vacuum decay), a fundamental QED process not observed yet experimentally. At the neutron-rich sector near the drip line islands and extended ridges of quasistable nuclei are predicted by HF calculations. Such nuclei, as well as very long living superheavy nuclei may be provided in double atomic bomb explosions. A tremendously rich scenario of new nuclear structure emerges with new magic numbers in the strangeness domain. Various production mechanisms are discussed for these objects and for antinuclei in high energy heavy-ion collisions.

  16. New, heavy transuranium isotopes

    SciTech Connect

    Hulet, E.K.

    1990-10-22

    In this report, we offer our most recent results concerning the decay properties for five new isotopes of Md, No, Lr, and for {sup 258m}Md. In additions to these successful experiments, we have also conducted searches for {sup 263}(105), {sup 264}(105), {sup 272}(109), and superheavy elements from bombardments of {sup 254}Es with heavy ions. {sup 2} An exciting finding in the course of this work is a new fission phenomenon, which we have termed bidmodal fission''. This is described in a subsequent section. The final part summarizes our conclusions based on the unexpectedly long half-lives and surprising fission properties of the heaviest nuclei. 27 refs., 19 figs.

  17. Stem cell mechanics: Auxetic nuclei

    NASA Astrophysics Data System (ADS)

    Wang, Ning

    2014-06-01

    The nuclei of naive mouse embryonic stem cells that are transitioning towards differentiation expand when the cells are stretched and contract when they are compressed. What drives this auxetic phenotype is, however, unclear.

  18. Generalized parton distributions in nuclei

    SciTech Connect

    Vadim Guzey

    2009-12-01

    Generalized parton distributions (GPDs) of nuclei describe the distribution of quarks and gluons in nuclei probed in hard exclusive reactions, such as e.g. deeply virtual Compton scattering (DVCS). Nuclear GPDs and nuclear DVCS allow us to study new aspects of many traditional nuclear effects (nuclear shadowing, EMC effect, medium modifications of the bound nucleons) as well as to access novel nuclear effects. In my talk, I review recent theoretical progress in the area of nuclear GPDs.

  19. Exotic Orbital Modes in Nuclei

    NASA Astrophysics Data System (ADS)

    von Neumann-Cosel, P.

    2003-06-01

    Experimental evidence for two types of collective excitations in nuclei generated by orbital motion is discussed, viz. a magnetic quadrupole twist mode observed in 180° electron scattering experiments and a toroidal electric dipole mode. The latter may be a source of low-energy pygmy dipole resonances observed in many nuclei. This is discussed in detail for the example of 208Pb based on the recent finding of a resonance at particle threshold in a high-resolution (γ, γ') experiment.

  20. The nature of comet nuclei

    NASA Technical Reports Server (NTRS)

    Sykes, Mark V.; Walker, Russell G.

    1992-01-01

    The icy-conglomerate model of comet nuclei has dominated all others since its introduction. It provided a basis for understanding the non-gravitational motions of comets which had perplexed dynamicists up to that time, and provided a focus for understanding cometary composition and origin. The image of comets as dirty snowballs was quickly adopted. Comet nuclei including their trail mass loss rates and refractory to volatile mass ratios are described.

  1. Heavy Flavors

    NASA Astrophysics Data System (ADS)

    Cox, B.; Soni, A.

    This is a summary report of the working group on Heavy Flavors. Discussions at the workshop were centered on B physics and on the signals for heavy quarks and leptons at the SSC. The Working Group Members were: V. Barger, H.-U. Bengtsson, C. Buchanan, I. Bigi, M. Block, B. Cox, N. Glover, J. Hewett, W.Y. Keung, B. Margolis, T. Rizzo, M. Suzuki, A. Soni, D. Stork, and S. Willenbrock.

  2. Theoretical studies on the modes of decay of superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Santhosh, K. P.; Nithya, C.

    2016-11-01

    The decay modes of recently synthesized superheavy nuclei are investigated by comparing the α -decay half-lives with the spontaneous fission half-lives. α -decay half-lives are calculated using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The agreement between theoretical and experimental α half-lives shows the predictability of the CPPMDN in the superheavy region. A modified formula is proposed for calculating the spontaneous fission half-lives including the shell correction. The agreement between theoretical predictions and experimental results of spontaneous fission half-lives is satisfactory for heavy and superheavy nuclei ranging from Th to Fl. A comparison between the spontaneous fission half-lives computed using eight different formalisms is performed for even-even superheavy nuclei in the range of 108 ≤Z ≤120 . Even though all these models can reproduce the experimental spontaneous fission half-lives, model-to-model variations in predicting the fission half-lives in superheavy region is evident from the study.

  3. Heavy ion fragmentation experiments at the bevatron

    NASA Technical Reports Server (NTRS)

    Heckman, H. H.

    1976-01-01

    Collaborative research efforts to study the fragmentation processes of heavy nuclei in matter using heavy ion beams of the Bevatron/Bevalac are described. The goal of the program is to obtain the single particle inclusive spectra of secondary nuclei produced at 0 deg by the fragmentation of heavy ion beam projectiles. The process being examined is B+T yields F + anything, where B is the beam nucleus, T is the target nucleus, and F is the detected fragment. The fragments F are isotopically identified by experimental procedures involving magnetic analysis, energy loss and time-of-flight measurements. Effects were also made to: (a) study processes of heavy nuclei in matter, (b) measure the total and partial production cross section for all isotopes, (c) test the applicability of high energy multiparticle interaction theory to nuclear fragmentation, (d) apply the cross section data and fragmentation probabilities to cosmic ray transport theory, and (e) search for systematic behavior of fragment production as a means to improve existing semi-empirical theories of cross-sections.

  4. Cavitation inception from bubble nuclei.

    PubMed

    Mørch, K A

    2015-10-06

    The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid. The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model and associated experiments throw new light on the effects of transient pressures on the tensile strength of water, which may be notably reduced or increased by such pressure changes.

  5. Cavitation inception from bubble nuclei

    PubMed Central

    Mørch, K. A.

    2015-01-01

    The tensile strength of ordinary water such as tap water or seawater is typically well below 1 bar. It is governed by cavitation nuclei in the water, not by the tensile strength of the water itself, which is extremely high. Different models of the nuclei have been suggested over the years, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid. The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure–time history of the water. A recent model and associated experiments throw new light on the effects of transient pressures on the tensile strength of water, which may be notably reduced or increased by such pressure changes. PMID:26442138

  6. Reflection asymmetric shapes in nuclei

    SciTech Connect

    Ahmad, I.; Carpenter, M.P.; Emling, H.; Holzmann, R.; Janssens, R.V.F.; Khoo, T.L.; Moore, E.F.; Morss, L.R.; Durell, J.L.; Fitzgerald, J.B.; Mowbary, A.S.; Hotchkiss, M.A.; Phillips, W.R.; Drigert, M.W.; Ye, D.; Benet, P.; Manchester Univ. . Dept. of Physics; EG and G Idaho, Inc., Idaho Falls, ID; Notre Dame Univ., IN; Purdue Univ., Lafayette, IN )

    1989-01-01

    Experimental data show that there is no even-even nucleus with a reflection asymmetric shape in its ground state. Maximum octupole- octupole correlations occur in nuclei in the mass 224 (N{approximately}134, Z{approximately}88) region. Parity doublets, which are the characteristic signature of octupole deformation, have been observed in several odd mass Ra, Ac and Pa nuclei. Intertwined negative and positive parity levels have been observed in several even-even Ra and Th nuclei above spin {approximately}8{Dirac h}. In both cases, the opposite parity states are connected by fast El transitions. In some medium-mass nuclei intertwined negative and positive parity levels have also been observed above spin {approximately}7{Dirac h}. The nuclei which exhibit octupole deformation in this mass region are {sup 144}Ba, {sup 146}Ba and {sub 146}Ce; {sup 142}Ba, {sup 148}Ce, {sup 150}Ce and {sup 142}Xe do not show these characteristics. No case of parity doublet has been observed in the mass 144 region. 32 refs., 16 figs., 1 tab.

  7. Formation of super-heavy elements in astrophysical nucleosynthesis

    SciTech Connect

    Zagrebaev, V. I.; Karpov, A. V.; Mishustin, I. N.; Greiner, Walter

    2012-10-20

    The unexplored area of heavy neutron-rich nuclides is extremely important for the understanding of the r process of astrophysical nucleogenesis. For elements with Z>100 only neutron deficient isotopes (located to the left of the stability line) have been synthesized so far. The 'north-east' area of the nuclear map can be reached neither in fusion reactions nor in fragmentation processes. Low energy multi-nucleon transfer reactions are quite promising for the production and study of neutron-rich heavy nuclei including those located at the superheavy (SH) island of stability [1]. The neutron capture process is considered here as an alternative method for the production of SH nuclei. Requirements for the pulsed reactors of the next generation that could be used for the synthesis of long-living neutron rich SH nuclei are formulated. Formation of SH nuclei in supernova explosions is also discussed and the abundance of SH elements in nature is estimated.

  8. Phase coexistence in nuclei

    NASA Astrophysics Data System (ADS)

    Gulminelli, F.

    2004-11-01

    In this work the general theory of first order phase transitions in finite systems is discussed, with a special emphasis to the conceptual problems linked to a thermodynamic description for small, short-lived systems de-exciting in the vacuum as nuclear samples coming from heavy ion collisions. After a short review of the general theory of phase transitions in the framework of information theory, we will present the different possible extensions to the field of finite systems. The concept of negative heat capacity, developed in the early seventies in the context of self-gravitating systems, will be reinterpreted in the general framework of convexity anomalies of thermostatistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. A careful study of the thermodynamic limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. In the second part of the paper we will apply the theoretical ideas developed in the first part to the possible observation of a liquid-to-gas-like phase transition in heavy ion collisions. The applicability of equilibrium concepts in a dynamical collisional process without boundary conditions will first be critically discussed. The observation of abnormally large partial energy fluctuations in carefully selected samples of collisions detected with the MULTICS-Miniball and INDRA array will then be reported as a strong evidence of a first order phase transition with negative heat capacity in the nuclear equation of state. Coexistence de phase dans les noyaux Ce papier présente une revue de la théorie générale des transitions de phase du premier ordre dans les petits systèmes, avec une attention particulière aux probl

  9. Expectations and Limits to Synthesize Nuclei with Z ≥ 120

    NASA Astrophysics Data System (ADS)

    Giardina, G.; Fazio, G.; Mandaglio, G.; Manganaro, M.; Nasirov, A. K.; Romaniuk, M. V.; Saccà, C.

    In order to explore the possibilities to synthesize the new superheavy elements with Z=120, 122, 124, 126 some hot-fusion (mass asymmetric) reactions and cold-fusion (less mass asymmetric) reactions are studied. The dynamics of reaction with massive nuclei and the formation probability of heavy and superheavy elements with Z=90-126 in the asymmetric and symmetric reactions are discussed. The systematics of fusion probability PCN and evaporation residue cross section σER in these reactions are presented. Moreover, we explore the possibility of synthesis of superheavy nuclei by the use of reaction with the neutron rich radioactive beam 132Sn, and by symmetric reactions like 136Xe+136Xe and 139,149La+ 139,149La.

  10. Magnetic moments of light nuclei from lattice quantum chromodynamics

    DOE PAGES

    Beane, S.  R.; Chang, E.; Cohen, S.; ...

    2014-12-16

    We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and 3He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to mπ ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of 3He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures itsmore » dominant structure. Similarly a shell-model-like moment is found for the triton, μ3H ~ μp. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.« less

  11. Fermi Hypernetted Chain Description of Doubly Closed Shell Nuclei

    NASA Astrophysics Data System (ADS)

    de Saavedra, F. Arias; Bisconti, C.; Co, G.

    2008-06-01

    For the first time, Fermi HyperNetted Chain (FHNC) techniques have been applied to describe the ground-state of medium and heavy doubly closed shell nuclei, with fully realistic nuclear interactions, including both two- and three-body forces, and operator dependent correlation functions. Calculations for the 12C, 16O,40Ca, 48Ca and 208Pb nuclei, have been done by using Argonne V8' two-body potential together with Urbana IX three-body force. These calculations reach an accuracy comparable to that of the best nuclear matter variational calculations. We have also investigated the effects produced by the short range correlations (SRC) on some ground state quantities related to observables.

  12. Beta-Delayed Neutron Emission in Neutron-Rich Nuclei

    NASA Astrophysics Data System (ADS)

    Marketin, Tomislav; Sieverding, André; Wu, Meng-Ru; Paar, Nils; Martínez-Pinedo, Gabriel

    β-delayed neutron emission is the process of emission of one or more neutrons, after β-decay, from the excited daughter nucleus. The probabilities of emission are an important physical quantity in a variety of nuclear physics applications, from the simulations of heavy element nucleosynthesis to control of reactor power levels and nuclear waste management. However, it is relatively difficult to measure and much less data is available than for β-decay, particularly for nuclei that are expected to take part in the r-process. In this work we will present a calculation of β-decay half-lives and β-delayed neutron emission probabilities in neutron-rich nuclei using the transition strength obtained with a microscopic model combined with a statistical calculation of level densities. We explore the effect of altered emission probabilities, with respect to the simple calculation, on the r-process.

  13. Measuring the collectivity of neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Görgen, Andreas

    2012-10-01

    Measuring the lifetimes of excited nuclear states provides direct information on electromagnetic transition rates and on the collectivity of nuclear excitations. The recoil distance Doppler-shift (RDDS) method is a well-established technique for measuring picosecond lifetimes of excited states, which has been extensively used in combination with fusion-evaporation reactions to measure lifetimes in neutron-deficient nuclei. Here we discuss novel ways of combining the RDDS technique with multi-nucleon transfer and fusion-fission reactions, which allow measurement of picosecond lifetimes in neutron-rich nuclei. Experiments were performed at both GANIL and Legnaro National Laboratories (LNL) with the goal to investigate the onset of collectivity around 68Ni and the evolution of shapes and shape coexistence in medium-heavy fission fragments.

  14. The fate of ultrahigh energy nuclei in the immediate environment of young fast-rotating pulsars

    SciTech Connect

    Kotera, Kumiko; Amato, Elena; Blasi, Pasquale E-mail: amato@arcetri.astro.it

    2015-08-01

    Young, fast-rotating neutron stars are promising candidate sources for the production of ultrahigh energy cosmic rays (UHECRs). The interest in this model has recently been boosted by the latest chemical composition measurements of cosmic rays, that seem to show the presence of a heavy nuclear component at the highest energies. Neutrons stars, with their metal-rich surfaces, are potentially interesting sources of such nuclei, but some open issues remain: 1) is it possible to extract these nuclei from the star's surface? 2) Do the nuclei survive the severe conditions present in the magnetosphere of the neutron star? 3) What happens to the surviving nuclei once they enter the wind that is launched outside the light cylinder? In this paper we address these issues in a quantitative way, proving that for the most reasonable range of neutron star surface temperatures (T<10{sup 7} K), a large fraction of heavy nuclei survive photo-disintegration losses. These processes, together with curvature losses and acceleration in the star's electric potential, lead to injection of nuclei with a chemical composition that is mixed, even if only iron is extracted from the surface. We show that under certain conditions the chemical composition injected into the wind region is compatible with that required in previous work based on purely phenomenological arguments (typically ∼50% protons, ∼30% CNO and ∼20% Fe), and provides a reasonable explanation of the mass abundance inferred from ultra high energy data.

  15. The fate of ultrahigh energy nuclei in the immediate environment of young fast-rotating pulsars

    NASA Astrophysics Data System (ADS)

    Kotera, Kumiko; Amato, Elena; Blasi, Pasquale

    2015-08-01

    Young, fast-rotating neutron stars are promising candidate sources for the production of ultrahigh energy cosmic rays (UHECRs). The interest in this model has recently been boosted by the latest chemical composition measurements of cosmic rays, that seem to show the presence of a heavy nuclear component at the highest energies. Neutrons stars, with their metal-rich surfaces, are potentially interesting sources of such nuclei, but some open issues remain: 1) is it possible to extract these nuclei from the star's surface? 2) Do the nuclei survive the severe conditions present in the magnetosphere of the neutron star? 3) What happens to the surviving nuclei once they enter the wind that is launched outside the light cylinder? In this paper we address these issues in a quantitative way, proving that for the most reasonable range of neutron star surface temperatures (T<107 K), a large fraction of heavy nuclei survive photo-disintegration losses. These processes, together with curvature losses and acceleration in the star's electric potential, lead to injection of nuclei with a chemical composition that is mixed, even if only iron is extracted from the surface. We show that under certain conditions the chemical composition injected into the wind region is compatible with that required in previous work based on purely phenomenological arguments (typically ~50% protons, ~30% CNO and ~20% Fe), and provides a reasonable explanation of the mass abundance inferred from ultra high energy data.

  16. Chromatin structure in barley nuclei.

    PubMed

    Mithieux, G; Roux, B

    1983-10-03

    In order to study the chromatin structure of a higher plant we used a high-yield method, which allows one to obtain up to 10(9) nuclei/kg fresh barley leaves. Significant amounts of low-ionic-strength-soluble chromatin can be extracted from these nuclei. Physicochemical properties were examined and discussed. Electric birefringence allowed us to observe the same transition in electro-optical properties as has been observed for animal chromatin, and suggested the existence of a symetrical structure occurring for approximately six nucleosomes. Circular dichroism showed that barley oligonucleosomes exhibit a higher molar ellipticity at 282 nm than total soluble chromatin and than their animal counterparts.

  17. Penetration factor in deformed potentials: Application to α decay with deformed nuclei

    NASA Astrophysics Data System (ADS)

    Ismail, M.; Ellithi, A. Y.; Botros, M. M.; Abdurrahman, A.

    2012-10-01

    A new averaging process of the calculation of α-decay half-lives for heavy and superheavy nuclei is studied in the framework of a deformed density-dependent cluster model. The potential between a spherical α particle and a deformed daughter nucleus is calculated numerically from the double-folding model by the multipole expansion method. The nuclear potential is calculated at each α-particle emission angle applying the Bohr-Sommerfeld condition at each case. The penetration factors and the half-lives for all the emission angles are evaluated with the new averaging process and compared with older values based on a fixed value of the nuclear potential depth. Finally, the half-lives of 83 even-even heavy nuclei in the atomic-number range 82-118 are calculated by the two methods and compared with their experimental values and the corresponding half-lives of the spherical daughter nuclei.

  18. Threshold photoneutron angular distribution and polarization studies of nuclei

    SciTech Connect

    Holt, R.J.

    1980-01-01

    The photoneutron method was applied to the study of: (1) deuteron photodisintegration; (2) giant magnetic dipole resonances in heavy nuclei; (3) mechanism of radiative capture in light nuclei; and (4) isospin splitting of the giant dipole resonance in /sup 60/Ni. These studies were performed with the pulsed bremsstrahlung beam and high-resolution spectrometer available at the Argonne high-current electron linac. A threshold photoneutron polarization method was developed in order to search for the giant M1 resonance in heavy nuclei. A surprisingly small amount of M1 strength was found in /sup 208/Pb. Furthermore, the M1 strength for the 5.08-MeV excitation in /sup 17/O, the best example of a single-particle M1 resonance in nuclei, was found to be strongly quenched. In addition, the /sup 17/O(..gamma..,n/sub 0/)/sup 16/O reaction was found to provide an ideal example of the Lane-Lynn theory of radiative capture. The interplay among the three components of the theory, internal, channel and potential capture, were evident from the data. An electron beam transport system was developed which allows the bremsstrahlung to impinge on the photoneutron target on an axis perpendicular to the usual reaction plane. This system provides an accurate method for the measurement of relative angular distributions in (..gamma..,n) reactions. This system was applied to a high-accuracy measurement of the relative angular distribution for the D(..gamma..,n)H reaction. The question of isospin-splitting of the giant dipole resonance in /sup 60/Ni was studied by using the unique pico-pulse from the accelerator and the newly installed 25-m, neutron flight paths. The results provide clear evidence for the effect of isospin splitting.

  19. Design of a new in-flight separator for heavy and superheavy fusion and transfer products

    NASA Astrophysics Data System (ADS)

    Heinz, S.; Barth, W.; Franczak, B.; Geissel, H.; Gupta, M.; Hofmann, S.; Mickat, S.; Münzenberg, G.; Plaß, W. R.; Scheidenberger, C.; Weick, H.; Winkler, M.

    2013-12-01

    We are developing a new velocity filter which is foreseen for separation of fusion and deep inelastic transfer products in the region of heavy and superheavy nuclei. The device is developed in collaboration with GSI Darmstadt, the University of Giessen and the Manipal University, India. In parallel to the separator design we are developing new techniques for particle detection and identification, especially for heavy nuclei which are not accessible with the presently available techniques.

  20. Determination of the effects of nuclear level density parameters on photofission cross sections of 235U up to 20 MeV

    NASA Astrophysics Data System (ADS)

    Sarpün, Ismail Hakki; Aydın, Abdullah; Pekdoğan, Hakan

    2017-09-01

    The level density models and level density parameters are two of important quantities for describing the properties of nuclei. Especially, the level density parameter has an important role as input in calculation of reaction cross sections. In this study, the cross sections on 235U(g,f) reaction were calculated for different level density models using the TALYS 1.6 code up to 20 MeV gamma incident energies. First, it was determined the level density model that was the closest to the experimental data. Secondly, cross sections obtained for different level density parameters of this model were compared with experimental data from the EXFOR database. Thus it was determined the best level density parameter fit to experimental data.

  1. From hadrons to nuclei with charm and bottom flavors

    SciTech Connect

    Yasui, S.; Sudoh, K.

    2011-10-21

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

  2. Cluster approach to the structure of nuclei with Z {>=} 96

    SciTech Connect

    Shneidman, T. M. Adamian, G. G.; Antonenko, N. V.; Jolos, R. V.

    2007-08-15

    The properties of alternating parity bands in heavy nuclei {sup 234}Th, {sup 239-242}U, {sup 241-245}Pu, {sup 243-248}Cm, {sup 245-250}Cf, {sup 248-251}Fm, {sup 249-254}No, {sup 253-256}Rf, and {sup 258}Sg are analyzed within the dinuclearsystem model. The model is based on the assumption that the cluster-type shapes are produced by the motion of the nuclear system in the mass-asymmetry coordinate. The energies of the low-lying states whose parity is opposite to the parity of the ground state are predicted for the first time.

  3. International Symposium on Exotic Nuclei

    NASA Astrophysics Data System (ADS)

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

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

  4. Chiral electroweak currents in nuclei

    DOE PAGES

    Riska, D. O.; Schiavilla, R.

    2017-01-10

    Here, the development of the chiral dynamics based description of nuclear electroweak currents is reviewed. Gerald E. (Gerry) Brown’s role in basing theoretical nuclear physics on chiral Lagrangians is emphasized. Illustrative examples of the successful description of electroweak observables of light nuclei obtained from chiral effective field theory are presented.

  5. Electromagnetic structure of light nuclei

    SciTech Connect

    Pastore, Saori

    Here, the present understanding of nuclear electromagnetic properties including electromagnetic moments, form factors and transitions in nuclei with A ≤ 10 is reviewed. Emphasis is on calculations based on nuclear Hamiltonians that include two- and three-nucleon realistic potentials, along with one- and two-body electromagnetic currents derived from a chiral effective field theory with pions and nucleons.

  6. Electromagnetic structure of light nuclei

    DOE PAGES

    Pastore, Saori

    2016-03-25

    Here, the present understanding of nuclear electromagnetic properties including electromagnetic moments, form factors and transitions in nuclei with A ≤ 10 is reviewed. Emphasis is on calculations based on nuclear Hamiltonians that include two- and three-nucleon realistic potentials, along with one- and two-body electromagnetic currents derived from a chiral effective field theory with pions and nucleons.

  7. Octupole correlation effects in nuclei

    SciTech Connect

    Chasman, R.R.

    1992-01-01

    Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.

  8. Octupole correlation effects in nuclei

    SciTech Connect

    Chasman, R.R.

    1992-08-01

    Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions.

  9. Understanding nuclei: progress and challenges

    SciTech Connect

    Dean, D. J.

    2008-04-17

    Nuclear theory today aims for a comprehensive theoretical framework that can describe all nuclei. I discuss recent progress in this pursuit and the associated challenges as we move forward, paying particular attention to progress in the applications of coupled-cluster theory to the challenges.

  10. Nuclei and propeller cavitation inception

    SciTech Connect

    Gindroz, B.; Billet, M.L.

    1994-12-31

    Propeller cavitation inception tests were conducted in the Grand Tunnel Hydrodynamique (GTH) of the Bassin d`Essaid des Carenes. Both acoustic and visual cavitation inception were determined for leading-edge sheet, travelling bubble, and tip vortex. These data were obtained for specific water quality conditions. The water quality was determined from cavitation susceptibility meter measurements for degassed water (maximum liquid tension, few nuclei), low injection rate of microbubbles (medium liquid tension, low nuclei concentration), medium injection rate of microbubbles (medium liquid tension, high nuclei concentration) and high injection rate of microbubbles (minimum liquid tension, high nuclei concentration). Results clearly demonstrate a different influence of water quality for each type of cavitation. Little variation in cavitation inception index for a significant increase in liquid tension and microbubble size distribution was found for leading-edge sheet; however, tip vortex cavitation inception index decreased significantly for an increase in liquid tension. In addition, a dependency on event rate was determined for tip vortex cavitation inception.

  11. Structural Evolution in Atomic Nuclei: Residual Interactions, Quantum Phase Transitions and the Emergence of Collectivity

    SciTech Connect

    Casten, R. F.

    2007-10-26

    A synoptic view of the evolution of structure with Z and N in nuclei is beginning to emerge from the confiuence of new experimental results on phase transitional behavior, newly proposed many-body symmetries for critical point nuclei, a new generation of solvable collective models, powerful approaches to viewing the systematics of nuclear properties based on simple models of residual interactions, and advances in microscopic calculations of medium mass and heavy nuclei. A recent compilation of nuclear masses has contributed by permitting empirical extractions of new p-n interaction strengths of the last protons with the last neutrons in many nuclei across the nuclear chart. A number of these developments will be discussed with an eye to the opportunities and challenges they provide for the future, especially in the era of next-generation exotic beam facihties throughout the world.

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

    SciTech Connect

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

    2009-12-15

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

  13. Study of Analytic Statistical Model for Decay of Light and Medium Mass Nuclei in Nuclear Fragmentation

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Wilson, John W.

    1996-01-01

    The angular momentum independent statistical decay model is often applied using a Monte-Carlo simulation to describe the decay of prefragment nuclei in heavy ion reactions. This paper presents an analytical approach to the decay problem of nuclei with mass number less than 60, which is important for galactic cosmic ray (GCR) studies. This decay problem of nuclei with mass number less than 60 incorporates well-known levels of the lightest nuclei (A less than 11) to improve convergence and accuracy. A sensitivity study of the model level density function is used to determine the impact on mass and charge distributions in nuclear fragmentation. This angular momentum independent statistical decay model also describes the momentum and energy distribution of emitted particles (n, p, d, t, h, and a) from a prefragment nucleus.

  14. Alpha decay and cluster decay of some neutron-rich actinide nuclei

    NASA Astrophysics Data System (ADS)

    Carmel Vigila Bai, G. M.; Agnes, R. Nithya

    2017-03-01

    Nuclei in the actinide region are good in exhibiting cluster radioactivity. In the present work, the half-lives of α-decay and heavy cluster emission from certain actinide nuclei have been calculated using cubic plus Yukawa plus exponential model (CYEM). Our model has a cubic potential for the overlapping region which is smoothly connected by a Yukawa plus exponential potential for the region after separation. The computed half-lives are compared with those of other theoretical models and are found to be in good agreement with each other. In this work, we have also studied the deformation effects on half-lives of cluster decay. These deformation effects lower the half-life values and it is also found that the neutron-rich parent nuclei slow down the cluster decay process. Geiger-Nuttal plots for various clusters are found to be linear and most of the emitted clusters are α-like nuclei.

  15. Production of heavy isotopes in transfer reactions by collisions of {sup 238}U+{sup 238}U

    SciTech Connect

    Feng Zhaoqing; Jin Genming; Li Junqing

    2009-12-15

    The dynamics of transfer reactions in collisions of two very heavy nuclei {sup 238}U+{sup 238}U is studied within the dinuclear system (DNS) model. Collisions of two actinide nuclei form a superheavy composite system during a very short time, in which a large number of charge and mass transfers may take place. Such reactions have been investigated experimentally as an alternative way for the production of heavy and superheavy nuclei. The role of collision orientation in the production cross sections of heavy nuclides is analyzed systematically. Calculations show that the cross sections decrease drastically as the charged numbers of the heavy fragments increase. The transfer mechanism is favorable to synthesizing heavy neutron-rich isotopes, such as nuclei around the subclosure at N=162 from No (Z=102) to Db (Z=105)

  16. Meson production and nuclear fragmentation of the nuclei in the atmosphere

    SciTech Connect

    Navia, C.E.; Pinto, H.V.; Pinto, F.A. ); Maldonado, R.H.; Portella, H.M. Instituto de Fisica, Universidade Federal Fluminense, 24020 Niteroi, Rio de Janeiro, Brazil )

    1989-11-01

    Propagation of primary and secondary cosmic rays in the atmosphere is calculated analytically. Two different cases of primary-cosmic-ray composition are used: the first case assumes a mixed composition of very heavy, heavy, middle, and {alpha} nuclei and nucleons; the second case considers only nucleons in the primary-cosmic-ray flux. The mechanism of multiple meson production is formulated according to the wounded-nucleon model for a nucleus-nucleus interaction and the scaling model for a nucleon-nucleon interaction. The mechanism of nuclear fragmentation is formulated according to experimental values of the fragmentation parameters at low energy. The calculated results of the electromagnetic flux are compared with the results of mountain experiments with a large-scale emulsion chamber and experimental data at airplane altitudes. From these comparisons the model with heavy nuclei gives the best fit.

  17. Secondary beams and the synthesis of exotic nuclei

    SciTech Connect

    Nitschke, J.M.

    1985-09-01

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

  18. Magnetic moments of neutron deficient yttrium nuclei

    SciTech Connect

    Berks; El Hajjaji, O.; Fahad, M.; Hassani, R.; Giroux, J.; Marest, G.; Marguier, G.; Stone, N.J.; Rikovska, J.; Green, V.R.; and others

    1987-12-10

    This paper describes recent low temperature nulcear orientation (LTNO) work on neutron deficient /sup 85m,86,86m/Y nuclei. Results are compared with experimental systematics of neighbouring nuclei and particle core coupling calculations.

  19. Helium nuclei in quenched lattice QCD

    SciTech Connect

    Yamazaki, T.; Ukawa, A.; Kuramashi, Y.

    2010-06-01

    We present results for the binding energies for {sup 4}He and {sup 3}He nuclei calculated in quenched lattice QCD at the lattice spacing of a=0.128 fm with a heavy quark mass corresponding to m{sub {pi}=}0.8 GeV. Enormous computational cost for the nucleus correlation functions is reduced by avoiding redundancy of equivalent contractions stemming from permutation symmetry of protons or neutrons in the nucleus and various other symmetries. To distinguish a bound state from an attractive scattering state, we investigate the volume dependence of the energy difference between the nucleus and the free multinucleon states by changing the spatial extent of the lattice from 3.1 to 12.3 fm. A finite energy difference left in the infinite spatial volume limit leads to the conclusion that the measured ground states are bounded. It is also encouraging that the measured binding energies and the experimental ones show the same order of magnitude.

  20. Dielectronic Recombination In Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Lukic, D. V.; Schnell, M.; Savin, D. W.; Altun, Z.; Badnell, N.; Brandau, C.; Schmidt, E. W.; Müller, A.; Schippers, S.; Sprenger, F.; Lestinsky, M.; Wolf, A.

    XMM-Newton and Chandra observations of active galactic nuclei (AGN) show rich spectra of X-ray absorption lines. These observations have detected a broad unresolved transition array (UTA) between ˜ 15-17 Å. This is attributed to inner-shell photoexcitation of M-shell iron ions. Modeling these UTA features is currently limited by uncertainties in the low-temperature dielectronic recombination (DR) data for M-shell iron. In order to resolve this issue, and to provide reliable iron M-shell DR data for plasma modeling, we are carrying out a series of laboratory measurements using the heavy-ion Test Storage Ring (TSR) at the Max-Plank-Institute for Nuclear Physics in Heidelberg, Germany. Currently, laboratory measurements of low temperature DR can only be performed at storage rings. We use the DR data obtained at TSR, to calculate rate coefficients for plasma modeling and to benchmark theoretical DR calculations. Here we report our recent experimental results for DR of Fe XIV forming Fe XIII.

  1. Dielectronic Recombination In Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Lukic, D. V.; Schnell, M.; Savin, D. W.; Altun, Z.; Badnell, N.; Brandau, C.; Schmidt, E. W.; Mueller, A.; Schippers, S.; Sprenger, F.; Lestinsky, M.; Wolf, A.

    2006-01-01

    XMM-Newton and Chandra observations of active galactic nuclei (AGN) show rich spectra of X-ray absorption lines. These observations have detected a broad unresolved transition array (UTA) between approx. 15-17 A. This is attributed to inner-shell photoexcitation of M-shell iron ions. Modeling these UTA features is currently limited by uncertainties in the low-temperature dielectronic recombination (DR) data for M-shell iron. In order to resolve this issue, and to provide reliable iron M-shell DR data for plasma modeling, we are carrying out a series of laboratory measurements using the heavy-ion Test Storage Ring (TSR) at the Max-Plank-Institute for Nuclear Physics in Heidelberg, Germany. Currently, laboratory measurements of low temperature DR can only be performed at storage rings. We use the DR data obtained at TSR, to calculate rate coefficients for plasma modeling and to benchmark theoretical DR calculations. Here we report our recent experimental results for DR of Fe XIV forming Fe XIII.

  2. Nuclear structure/nuclei far from stability

    SciTech Connect

    Casten, R.F.; Garrett, J.D.; Moller, P.; Bauer, W.W.; Brenner, D.S.; Butler, G.W.; Crawford, J.E.; Davids, C.N.; Dyer, P.L.; Gregorich, K.; Hagbert, E.G.; Hamilton, W.D.; Harar, S.; Haustein, P.E.; Hayes, A.C.; Hoffman, D.C.; Hsu, H.H.; Madland, D.G.; Myers, W.D.; Penttila, H.T.; Ragnarsson, I.; Reeder, P.L.; Robertson, G.H.; Rowley, N.; Schreiber, F.; Seifert, H.L.; Sherrill, B.M.; Siciliano, E.R.; Sprouse, G.D.; Stephens, F

    1990-01-01

    This report outlines some of the nuclear structure topics discussed at the Los Alamos Workshop on the Science of Intense Radioactive Ion Beams (RIB). In it we also tried to convey some of the excitement of the participants for utilizing RIBs in their future research. The introduction of radioactive beams promises to be a major milestone for nuclear structure perhaps even more important than the last such advance in beams based on the advent of heavy-ion accelerators in the 1960's. RIBs not only will allow a vast number of new nuclei to be studies at the extremes of isospin, but the variety of combinations of exotic proton and neutron configurations should lead to entirely new phenomena. A number of these intriguing new studies and the profound consequences that they promise for understanding the structure of the atomic nucleus, nature's only many-body, strongly-inteacting quantum system, are discussed in the preceeding sections. However, as with any scientific frontier, the most interesting phenomena probably will be those that are not anticipated--they will be truly new.

  3. New results on the structure of exotic nuclei

    NASA Astrophysics Data System (ADS)

    Sakurai, Hiroyoshi

    2015-04-01

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

  4. Properties of nuclei probed by laser light

    NASA Astrophysics Data System (ADS)

    Neugart, Rainer

    2017-03-01

    Viewing objects as small as atomic nuclei by visible light sounds quite unrealistic. However, nuclei usually appear as constituents of atoms whose excitations are indeed associated with the absorption and emission of light. Nuclei can thus interact with light via the atomic system as a whole.

  5. Heavy Ion Reactions with Neutron-Rich Beams - Proceedings of the Riken International Workshop

    NASA Astrophysics Data System (ADS)

    Yamaji, S.; Ishihara, M.; Takigawa, N.

    1993-11-01

    The Table of Contents for the book is as follows: * Preface * Opening Address * Fusion I * Heavy Ion Fusion at Subbarrier Energies: Progress and Questions * Angular Momentum in Heavy Ion Subbarrier Interaction * Fusion II * High Precision Fusion Excitation Function Measurements: What Can We Learn from Them? * Transfer Reactions for 16O + 144,152Sm near the Coulomb Barrier * Fusion III * Recent Theoretical Developments in the Study of Subbarrier Fusion * Direct Reaction Approach to Heavy Ion Scattering and Fusion at Energies near Coulomb Barrier * Fusion IV * Roles of Multi-Step Transfer in Fusion Process Induced by Heavy Ion Reactions * Special Session * RIKEN Accelerator Research Facility (RARF) * Fission I * Bimodal Nature of Nuclear Fission * Systematics of Isotope Production Rates: Mass Excess Dependence of Fission Products * Semiclassical Methods for the Multi-Dimensional Quantum Decay * Dynamics of Di-Nucleus Systems: Molecular Resonances * Fission II * The Competition Between Fusion-Fission and Deeply Inelastic Reactions in the Medium Mass Systems * Unstable Nuclei I * Coulomb Dissociation and Momentum Distributions for 11Li → 9Li+n+n Breakup Reactions * Unstable Nuclei II * Elastic Scattering and Fragmentation of Halo Nuclei * Secondary Reactions of Neutron-Rich Nuclei at Intermediate Energies * Life Time of Soft Dipole Excitation * Unstable Nuclei III * Shell Structure of Exotic Unstable Nuclei * Properties of Unstable Nuclei Within the Relativistic Many-Body Theory * Fusion with Unstable Nuclei * Barrier Distributions for Heavy Ion Fusion * Heavy Ion Reactions with Neutron-Rich Beams * Heavy Ion Fusion with Neutron-Rich Beams * Superheavy Elements * Study of α Decays Following 40Ar Bombardment on 238U * Production of Superheavy Elements via Fusion: What is Limiting Us? * Panel Session * Comments * List of Participants

  6. Physical processing of cometary nuclei

    NASA Technical Reports Server (NTRS)

    Weissman, Paul R.; Stern, S. Alan

    1989-01-01

    Cometary nuclei were formed far from the Sun in the colder regions of the solar nebula, and have been stored in distant orbits in the Oort cloud over most of the history of the solar system. It had been thought that this benign environment would preserve comets in close to their original pristine state. However, recent studies have identified a number of physical processes that have likely acted to modify cometary nuclei in a variety of significant ways. It is important to consider all of these possible processes, both in deciding on a site on the nucleus for collection of cometary samples, and in interpreting the results of analyses of returned cometary samples. Although it can no longer be said that comets are pristine samples of original solar nebula material, they are still the best obtainable samples of that unique period in the formation of the planetary system.

  7. Radio characteristics of galactic nuclei

    NASA Astrophysics Data System (ADS)

    Condon, J. J.

    1986-02-01

    Radio characteristics of galactic nuclei, providing such unique information as spectral data on source variability, and the long-term history of the central engine and its duration of activity and total energy, are reviewed. The compact radio source characteristics are complicated by orientation-dependent relativistic beaming and by refractive focusing in the interstellar medium. Incoherent synchrotron radiation is thought to be the emission mechanism, with the result that synchrotron self-absorption in compact sources hides the central engine from direct radio observation. However, the history revealed by the extended jets and lobes of radio galaxies and quasars favors a single massive object not supported by radiation pressure, either a spinar or a black hole, as the energy source in radio-galaxy nuclei.

  8. Transport of cosmic ray nuclei in various materials

    NASA Technical Reports Server (NTRS)

    Silberberg, R.; Tsao, C. H.; Letaw, J. R.

    1988-01-01

    Cosmic-ray heavy ions have become a concern in space radiation effects analyses. Heavy ions rapidly deposit energy and create dense ionization trails as they traverse materials. Collection of the free charge disrupts the operation of microelectronic circuits. This effect, called the single-event upset, can cause a loss of digital data. Passage of high linear energy transfer particles through the eyes has been observed by Apollo astronauts. These heavy ions have great radiobiological effectiveness and are the primary risk factor for leukemia induction on a manned Mars mission. Models of the transport of heavy cosmic-ray nuclei through materials depend heavily on our understanding of the cosmic-ray environment, nuclear spallation cross sections, and computer transport codes. Our group has initiated and pursued the development of a full capability for modeling these transport processes. A recent review of this ongoing effort is presented in Ref. 5. In this paper, we discuss transport methods and present new results comparing the attenuation of cosmic rays in various materials.

  9. Transport of cosmic ray nuclei in various materials.

    PubMed

    Silberberg, R; Tsao, C H; Letaw, J R

    1988-01-01

    Cosmic-ray heavy ions have become a concern in space radiation effects analyses. Heavy ions rapidly deposit energy and create dense ionization trails as they traverse materials. Collection of the free charge disrupts the operation of microelectronic circuits. This effect, called the single-event upset, can cause a loss of digital data. Passage of high linear energy transfer particles through the eyes has been observed by Apollo astronauts. These heavy ions have great radiobiological effectiveness and are the primary risk factor for leukemia induction on a manned Mars mission. Models of the transport of heavy cosmic-ray nuclei through materials depend heavily on our understanding of the cosmic-ray environment, nuclear spallation cross sections, and computer transport codes. Our group has initiated and pursued the development of a full capability for modeling these transport processes. A recent review of this ongoing effort is presented in Ref. 5. In this paper, we discuss transport methods and present new results comparing the attenuation of cosmic rays in various materials.

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

    SciTech Connect

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

    2016-04-15

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

  11. Geometric symmetries in light nuclei

    NASA Astrophysics Data System (ADS)

    Bijker, R.

    2017-06-01

    The algebraic cluster model is is applied to study cluster states in the nuclei12C and16O. The observed level sequences can be understood in terms of the underlying discrete symmetry that characterizes the geometrical configuration of the α-particles, i.e. an equilateral triangle for12C, and a regular tetrahedron for16O. The structure of rotational bands provides a fingerprint of the underlying geometrical configuration of α-particles.

  12. Direct Reactions with Exotic Nuclei

    SciTech Connect

    Baur, G.; Typel, S.

    2005-10-14

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

  13. Debye Layers in Plasmas Generalized to Hadron Confinement of Nuclei and Quark-Gluon-Plasmas

    NASA Astrophysics Data System (ADS)

    Hora, Heinrich; Miley, George H.

    2005-10-01

    . A new theory for the nuclear forces for confining the hadrons in a nucleus has been derived from a generalization of the Debye layer as known from the plasma ablation at laser irradiation where the temperature is substituted by the Fermi energy of the nucleons [1]. The first convincing proof is by using the empirical density of the nucleons defining their Fermi energy to arrive at a Debye length of about 3 fm as measured by Hofstadter for the decay of the nucleon density at the surface of heavy nuclei. This decay is interpreted as Wigner scattering and the Goos-Haenchen effect. With the same steps of substitutions, the surface energy of nuclei is always too small against the nucleon enthalpy to confine the hadrons until the density reaches such high values reproducing the empirical known radii of nuclei. By this way nuclei are possible only until uranium or curium by a Boltzmann equilibrium process explaining the endothermic generation of heavy nuclei in the Universe [2]. At and about six times higher nucleon density, the Fermi statistics changes into its relativistic branch excluding nucleation in neutron stars and explaining the quark-gluon plasma. [1] Edward Teller Lectures, H. Hora and G.H. Miley eds. (Imperial College Press London 2005) p. 103. [2] H. Hora, G.H. Miley, F. Osman, Astrophysics and Space Science, 298, 247 (2005)

  14. Beta-delayed fission probabilities of transfermium nuclei, involved in the r-process

    NASA Astrophysics Data System (ADS)

    Panov, I.; Lutostansky, Yu; Thielemann, F.-K.

    2016-01-01

    For the nucleosynthesis of heavy and superheavy nuclei fission becomes very important when the r-process runs in a very high neutron density environment. In part, fission is responsible for the formation of heavy nuclei due to the inclusion of fission products as new seed nuclei (fission cycling). More than that, beta-delayed fission, along with spontaneous fission, is responsible in the late stages of the r-process for the suppression of superheavy element yields. For beta-delayed fission probability calculations a model description of the beta-strength- functions is required. Extended theoretical predictions for astro-physical applications were provided long ago, and new predictions also for superheavy nuclei with uptodate nuclear input are needed. For the further extension of data to heavier transactinides the models of strength- functions should be modified, taking into account more complicated level schemes. In our present calculations the strength-function model is based on the quasi-particle approximation of Finite Fermi Systems Theory. The probabilities of beta-delayed fission and beta-delayed neutron emission are calculated for some transfermium neutron-rich nuclei, and the influence of beta-delayed fission upon superheavy element formation is discussed.

  15. New high spin states and isomers in the {sup 208}Pb and {sup 207}Pb nuclei

    SciTech Connect

    Broda, R.; Wrzesinski, J.; Pawlat, T.

    1996-12-31

    The two most prominent examples of the heavy doubly closed shell (DCS) nuclei, {sup 208}Pb and {sup 132}Sn, are not accessible by conventional heavy-ion fusion processes populating high-spin states. This experimental difficulty obscured for a long time the investigation of yrast high-spin states in both DCS and neighboring nuclei and consequently restricted the study of the shell model in its most attractive regions. Recent technical development of multidetector gamma arrays opened new ways to exploit more complex nuclear processes which populate the nuclei of interest with suitable yields for gamma spectroscopy and involve population of moderately high spin states. This new possibility extended the range of accessible spin values and is a promising way to reach new yrast states. Some of these states are expected to be of high configurational purity and can be a source of important shell model parameters which possibly can be used later to check the validity of the spherical shell model description at yet higher spin and higher excitation energy. The nuclei in the closest vicinity of {sup 132}Sn are produced in spontaneous fission and states with spin values up to I=14 can be reached in fission gamma spectroscopy studies with the presently achieved sensitivity of gamma arrays. New results on yrast states in the {sup 134}Te and {sup 135}I nuclei populated in fission of the {sup 248}Cm presented at this conference illustrate such application of the resolving power offered by modern gamma techniques.

  16. The Energetic Trans-Iron Nuclei Experiment (ENTICE)

    NASA Technical Reports Server (NTRS)

    Binns, W. R.; Israel, M. H.; Cummings, A. C.; Labrador, A. W.; Mewaldt, R. A.; Leske, R. A.; Stone, E. C.; Wiedenbeck, M. E.; Christian, E. R.; Denolfo, G. A.; hide

    2009-01-01

    The ENTICE experiment is one of two instruments that comprise the "Orbiting Astrophysical Spectrometer in Space (OASIS)" which is presently undergoing a NASA "Astrophysics Strategic Mission Concept Study". ENTICE is designed to make high precision measurements of the abundances of individual elements from neon through the actinides and, in addition, will search for possible superheavy nuclei in the galactic cosmic rays. The ENTICE instrument utilizes silicon detectors, aerogel and acrylic Cherenkov counters, and a scintillating optical fiber hodoscope to measure the charge and energy of these ultra-heavy nuclei for energies greater than 0.3 GeV/nucleon. It is a large instrument consisting of four modules with a total effective geometrical factor of 20 m2sr. Measurements made in space for a period of 3 years with ENTICE will enable us to determine if cosmic rays include a component of recently synthesized heavy elements (Pu and Cm), what the age of that component is, and test the model of the OB association origin of galactic cosmic rays. Additionally, it will enable us to study how diffusive shock acceleration of cosmic rays operates differently on interstellar grains and gas.

  17. The Energetic Trans-Iron Nuclei Experiment (ENTICE)

    NASA Technical Reports Server (NTRS)

    Binns, W. R.; Israel, M. H.; Cummings, A. C.; Labrador, A. W.; Mewaldt, R. A.; Leske, R. A.; Stone, E. C.; Wiedenbeck, M. E.; Christian, E. R.; Denolfo, G. A.; Hams, T.; Link, J. T.; Mitchell, J. W.; Sasaki, M.; Adams, J. H.; Waddington, C. J.

    2009-01-01

    The ENTICE experiment is one of two instruments that comprise the "Orbiting Astrophysical Spectrometer in Space (OASIS)" which is presently undergoing a NASA "Astrophysics Strategic Mission Concept Study". ENTICE is designed to make high precision measurements of the abundances of individual elements from neon through the actinides and, in addition, will search for possible superheavy nuclei in the galactic cosmic rays. The ENTICE instrument utilizes silicon detectors, aerogel and acrylic Cherenkov counters, and a scintillating optical fiber hodoscope to measure the charge and energy of these ultra-heavy nuclei for energies greater than 0.3 GeV/nucleon. It is a large instrument consisting of four modules with a total effective geometrical factor of 20 m2sr. Measurements made in space for a period of 3 years with ENTICE will enable us to determine if cosmic rays include a component of recently synthesized heavy elements (Pu and Cm), what the age of that component is, and test the model of the OB association origin of galactic cosmic rays. Additionally, it will enable us to study how diffusive shock acceleration of cosmic rays operates differently on interstellar grains and gas.

  18. Short Range Correlations in Nuclei at Large xbj through Inclusive Quasi-Elastic Electron Scattering

    SciTech Connect

    Ye, Zhihong

    2013-12-01

    The experiment, E08-014, in Hall-A at Jefferson Lab aims to study the short-range correlations (SRC) which are necessary to explain the nuclear strength absent in the mean field theory. The cross sections for 2H, 3He, 4He, 12C, 40Ca and 48Ca, were measured via inclusive quasi-elastic electron scattering from these nuclei in a Q2 range between 0.8 and 2.8 (GeV/c)2 for x>1. The cross section ratios of heavy nuclei to 2H were extracted to study two-nucleon SRC for 1

  19. Modeling multi-nucleon transfer in symmetric collisions of massive nuclei

    NASA Astrophysics Data System (ADS)

    Welsh, T.; Loveland, W.; Yanez, R.; Barrett, J. S.; McCutchan, E. A.; Sonzogni, A. A.; Johnson, T.; Zhu, S.; Greene, J. P.; Ayangeakaa, A. D.; Carpenter, M. P.; Lauritsen, T.; Harker, J. L.; Walters, W. B.; Amro, B. M. S.; Copp, P.

    2017-08-01

    Symmetric collisions of massive nuclei, such as 238U + 248Cm, have been proposed as ways to make new n-rich heavy nuclei via multi-nucleon transfer (MNT) reactions. We have measured the yields of several projectile-like and target-like fragments from the reaction of 1360 MeV 204Hg + 198Pt. We find that current models for this symmetric collision (GRAZING, DNS, ImQMD) significantly underestimate the yields of these transfer products, even for small transfers.

  20. Spreading widths of giant resonances in spherical nuclei: Damped transient response

    NASA Astrophysics Data System (ADS)

    Severyukhin, A. P.; Åberg, S.; Arsenyev, N. N.; Nazmitdinov, R. G.

    2017-06-01

    We propose a general approach to describe spreading widths of monopole, dipole, and quadrupole giant resonances in heavy and superheavy spherical nuclei. Our approach is based on the ideas of the random matrix distribution of the coupling between one-phonon and two-phonon states generated in the random-phase approximation. We use the Skyrme interaction SLy4 as our model Hamiltonian to create a single-particle spectrum and to analyze excited states of the doubly magic nuclei 132Sn, 208Pb, and 310126. Our results demonstrate that the approach enables to us to describe a gross structure of the spreading widths of the giant resonances considered.

  1. Modeling multi-nucleon transfer in symmetric collisions of massive nuclei

    DOE PAGES

    Welsh, T.; Loveland, W.; Yanez, R.; ...

    2017-05-18

    We propose symmetric collisions of massive nuclei, such as 238U + 248Cm, as ways to make new n-rich heavy nuclei via multi-nucleon transfer (MNT) reactions. We have measured the yields of several projectile-like and target-like fragments from the reaction of 1360 MeV 204Hg + 198Pt. We also find that current models for this symmetric collision (GRAZING, DNS, ImQMD) significantly underestimate the yields of these transfer products, even for small transfers.

  2. Interactions of 200 GeV gold nuclei in light elements

    NASA Technical Reports Server (NTRS)

    Brewster, N. R.; Fickle, R. K.; Waddington, C. J.; Binns, W. R.; Israel, M. H.; Jones, M. D.; Klarmann, J.; Garrard, T. L.; Newport, B. J.; Stone, E. C.

    1983-01-01

    Total charge-changing cross sections and partial cross-sections for interactions of 200 GeV Au-197 nuclei incident on carbon and polyethylene (CH2) targets have been measured during a calibration of the HEAO-3 Heavy Nuclei Experiment. From these, the total and partial cross-sections for Au-197 incident on hydrogen are inferred. The effects of using these cross-sections in one model of cosmic ray propagation are illustrated. Comparisons to predictions using semi-empirical formulas are shown.

  3. Constraining the astrophysical origin of the p-nuclei through nuclear physics and meteoritic data.

    PubMed

    Rauscher, T; Dauphas, N; Dillmann, I; Fröhlich, C; Fülöp, Zs; Gyürky, Gy

    2013-06-01

    A small number of naturally occurring, proton-rich nuclides (the p-nuclei) cannot be made in the s- and r-processes. Their origin is not well understood. Massive stars can produce p-nuclei through photodisintegration of pre-existing intermediate and heavy nuclei. This so-called γ-process requires high stellar plasma temperatures and occurs mainly in explosive O/Ne burning during a core-collapse supernova. Although the γ-process in massive stars has been successful in producing a large range of p-nuclei, significant deficiencies remain. An increasing number of processes and sites has been studied in recent years in search of viable alternatives replacing or supplementing the massive star models. A large number of unstable nuclei, however, with only theoretically predicted reaction rates are included in the reaction network and thus the nuclear input may also bear considerable uncertainties. The current status of astrophysical models, nuclear input and observational constraints is reviewed. After an overview of currently discussed models, the focus is on the possibility to better constrain those models through different means. Meteoritic data not only provide the actual isotopic abundances of the p-nuclei but can also put constraints on the possible contribution of proton-rich nucleosynthesis. The main part of the review focuses on the nuclear uncertainties involved in the determination of the astrophysical reaction rates required for the extended reaction networks used in nucleosynthesis studies. Experimental approaches are discussed together with their necessary connection to theory, which is especially pronounced for reactions with intermediate and heavy nuclei in explosive nuclear burning, even close to stability.

  4. Heavy Stars Thrive among Heavy Elements

    NASA Astrophysics Data System (ADS)

    2002-08-01

    VLT Observes Wolf-Rayet Stars in Virgo Cluster Galaxies [1] Summary Do very massive stars form in metal-rich regions of the Universe and in the nuclei of galaxies ? Or does "heavy element poisoning" stop stellar growth at an early stage, before young stars reach the "heavyweight class"? What may at the first glance appear as a question for specialists actually has profound implications for our understanding of the evolution of galaxies, those systems of billions of stars - the main building blocks of the Universe. With an enormous output of electromagnetic radiation and energetic elementary particles, massive stars exert a decisive influence on the surrounding (interstellar) gas and dust clouds . They also eject large amounts of processed elements, thereby participating in the gradual build-up of the many elements we see today. Thus the presence or absence of such stars at the centres of galaxies can significantly change the overall development of those regions and hence, presumably, that of the entire galaxy. A team of European astronomers [2] has now directly observed the presence of so-called Wolf-Rayet stars (born with masses of 60 - 90 times that of the Sun or more) within metal-rich regions in some galaxies in the Virgo cluster, some 50 million light-years away. This is the first unambiguous detection of such massive stellar objects in metal-rich regions . PR Photo 20a/02 : H II regions in the Virgo cluster galaxy NGC 4254 . PR Photo 20b/02 : Multi-object-slit observation of galaxy NGC 4303 . PR Photo 20c/02 : Spectrum of H II region in NGC 4254 with Wolf-Rayet signatures. Production of heavy elements in the Universe Most scientists agree that the Universe in which we live underwent a dramatic event, known as the Big Bang , approximately 15,000 million years ago. During the early moments, elementary particles were formed which after some time united into more complex nuclei and in turn resulted in the production of hydrogen and helium atoms and their isotopes

  5. Exotic few-body systems with a heavy meson

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yasuhiro

    2014-09-01

    Hadron as an impurity bound in nuclei causes interesting phenomena which do not emerge in normal nuclei. These effects would give us the information not only on the internal structure of the nuclei, but also on the changing properties of the impurity in the nuclear medium. The hadron-nucleus systems have been studied in the light flavor sector, especially. However, a strong attraction between a heavy meson (Dbar and B) and a nucleon, provided by the one pion exchange potential (OPEP), was suggested recently. The OPEP is enhanced by the heavy quark spin symmetry which induces the mass degeneracy between the heavy pseudoscalar and vector mesons. The attraction motivates us to investigate the Dbar (B) nuclei having the exotic flavor structure. Hence, these bound states are stable against the strong decay. We discuss the possible existence of exotic few-body states realized as DbarNN and BNN. The OPEP between the Dbar (B) meson and the nucleon N is considered. By solving coupled channel equations for PNN and P* NN channels (P (P*) is the heavy pseudoscalar (vector) meson), we obtain new three-body bound states and resonances. In these states, the tensor force of the OPEP plays an important role to yield the attraction.

  6. Electromagnetic dissociation effects in galactic heavy-ion fragmentation

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Townsend, L. W.

    1986-01-01

    Methods for calculating cross sections for the breakup of galactic heavy ions by the Coulomb fields of the interacting nuclei are presented. By using the Weizsacker-Williams method of virtual quanta, estimates of electromagnetic dissociation cross sections for a variety of reactions applicable to galactic cosmic ray shielding studies are presented and compared with other predictions and with available experimental data.

  7. Probing the nuclear structure with heavy-ion reactions

    SciTech Connect

    Broglia, R.A.

    1982-01-01

    Nuclei display distortions in both ordinary space and in gauge space. It is suggested that it is possible to learn about the spatial distribution of the Nilsson orbitals and about the change of the pairing gap with the rotational frequency through the analysis of one- and two-nucleon transfer reactions induced in heavy-ion collisions.

  8. Creating The Perfect Liquid In Heavy-Ion Collisions

    SciTech Connect

    Jacak, B.; Steinberg, P.

    2010-05-01

    In 2005 the four experimental groups at Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) announced that collisions of gold nuclei at ultrarelativistic energies produced a 'perfect liquid' of quarks and gluons. That's something quite different from the gaseous quark-gluon state theorists and experimenters were expecting from quantum chromodynamics, the standard theory of the strong interaction.

  9. On final conditions in high energy heavy ion Collisions

    SciTech Connect

    Sinyukov, Yu.M.; Akkelin, S.V.; Xu, N.

    1998-06-01

    Motivated by the recent experimental observations, wediscuss the freeze-out properties of the fireball created in centralheavy ion collisions. We find that the freeze-out conditions, liketemperature, velocity gradient near center of the fireball, are similarfor different colliding systems and beam energies. This means that thetransverse flow is stronger in the collisions of heavy nuclei than thatof the light ones.

  10. Heavy Metal Stars

    NASA Astrophysics Data System (ADS)

    2001-08-01

    La Silla Telescope Detects Lots of Lead in Three Distant Binaries Summary Very high abundances of the heavy element Lead have been discovered in three distant stars in the Milky Way Galaxy . This finding strongly supports the long-held view that roughly half of the stable elements heavier than Iron are produced in common stars during a phase towards the end of their life when they burn their Helium - the other half results from supernova explosions. All the Lead contained in each of the three stars weighs about as much as our Moon. The observations show that these "Lead stars" - all members of binary stellar systems - have been more enriched with Lead than with any other chemical element heavier than Iron. This new result is in excellent agreement with predictions by current stellar models about the build-up of heavy elements in stellar interiors. The new observations are reported by a team of Belgian and French astronomers [1] who used the Coude Echelle Spectrometer on the ESO 3.6-m telescope at the La Silla Observatory (Chile). PR Photo 26a/01 : A photo of HD 196944 , one of the "Lead stars". PR Photo 26b/01 : A CES spectrum of HD 196944 . The build-up of heavy elements Astronomers and physicists denote the build-up of heavier elements from lighter ones as " nucleosynthesis ". Only the very lightest elements (Hydrogen, Helium and Lithium [2]) were created at the time of the Big Bang and therefore present in the early universe. All the other heavier elements we now see around us were produced at a later time by nucleosynthesis inside stars. In those "element factories", nuclei of the lighter elements are smashed together whereby they become the nuclei of heavier ones - this process is known as nuclear fusion . In our Sun and similar stars, Hydrogen is being fused into Helium. At some stage, Helium is fused into Carbon, then Oxygen, etc. The fusion process requires positively charged nuclei to move very close to each other before they can unite. But with increasing

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

    NASA Astrophysics Data System (ADS)

    Itkis, M. G.; Beghini, S.; Behera, B. R.; Bogachev, A. A.; Bouchat, V.; Corradi, L.; Dorvaux, O.; Fioretto, E.; Hanappe, F.; Itkis, I. M.; Jandel, M.; Kliman, J.; Knyazheva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Latina, A.; Materna, T.; Montagnoli, G.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Prokhorova, E. V.; Rowley, N.; Rusanov, A. Ya.; Sagaidak, R. N.; Scarlassara, F.; Schmitt, C.; Stefanini, A. M.; Stuttge, L.; Szilner, S.; Trotta, M.

    2006-08-01

    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. CORSIKA implementation of heavy quark production and propagation in extensive air showers

    NASA Astrophysics Data System (ADS)

    Bueno, A.; Gascón, A.

    2014-02-01

    Heavy quarks are commonly produced in current accelerator experiments. Hence it is natural to think that they should be likewise created in collisions with larger center of mass energies like the ones involving ultra-high energy cosmic rays and atmospheric nuclei. Despite this fact, a detailed treatment of heavy hadrons is missing in Monte Carlo generators of Extensive Air Showers (EAS). It is a must to improve the description of how heavy flavors appear and evolve in atmospheric showers. With this goal in mind, we study two different models for heavy quark production in proton-air collisions. We also analyze a dedicated treatment of heavy hadrons interactions with atmospheric nuclei. This paper shows how those models have been implemented as new options available in CORSIKA, one of the most used EAS simulators. This new computational tool allows us to analyze the effects that the propagation of heavy hadrons has in the EAS development.

  13. The Spectroscopy of Neutron-Rich sdf-Shell Nuclei Using the CLARA-PRISMA Setup

    SciTech Connect

    Liang, X.; Hodsdon, A.; Chapman, R.; Burns, M.; Keyes, K.; Ollier, J.; Papenberg, A.; Spohr, K.; Azaiez, F.; Ibrahim, F.; Stanoiu, M.; Haas, F.; Caurier, E.; Curien, D.; Nowacki, F.; Salsac, M.-D.; Bazzacco, D.; Beghini, S.; Farnea, E.; Menegazzo, R.

    2006-08-14

    Since the discovery of the breakdown of shell effects in very neutron-rich N=20 and 28 nuclei, studies of the properties of nuclei far from stability have been of intense interest since they provide a unique opportunity to increase our understanding of nuclear interactions in extreme conditions and often challenge our theoretical models.Deep-inelastic processes can be used to populated high spin states of neutron-rich nuclei. In the deep-inelastic processes, an equilibration in N/Z between the target and projectile nuclei is achieved. For most heavy neutron-rich target nuclei, the N/Z ratio is 1.5 - 1.6, while for the possible neutron-rich sdf-shell projectile it is about 1.2. Thus by using deep-inelastic processes one can populate neutron-rich nuclei around N=20 and N=28.New results for the spectroscopy of neutron-rich N=22 36Si and 37P are presented here.

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

    SciTech Connect

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

    2015-05-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  16. Structure and reactions of drip-line nuclei

    SciTech Connect

    Hansen, P.G.

    1996-12-31

    Secondary radioactive beams produced at intermediate-energy heavy-ion accelerators have in a short time span added a new dimension to the research on nuclear species at the limits of particle stability, and new detection techniques have made it possible to study reactions caused by incident beams of as little as one particle per second. Imminent developments such as the M.S.U. Coupled-Cyclotron Facility are expected to extend the range and to permit the observation of many previously inaccessible species. For a perspective on the progress in this area one only needs to go about fifteen years back to a time when it had just become possible to study the radioactivity of rare nuclear species such as {sup 11}Li. In presenting early experiments with secondary beams produced in fragmentation James Symons said {open_quotes}... In the introduction to this paper we questioned the applicability of high-energy heavy-ion accelerators to this field. Our experience at the Bevalac leads us to believe that this question does indeed have a positive answer. If the physics interest justifies it, then high-energy heavy-ion beams can certainly be expected to play a role in the study of nuclei at the limits of stability.{close_quotes} At the time, very few, if any, realized how prophetic this remark was. In the present paper the interpretation of the longitudinal-momentum distributions from the nuclear fragmentation of single-nucleon halos is discussed. It is pointed out that these measurements, at least for the cases studied so far, directly reflect the halo wave function, and that there is no direct contribution from the reaction mechanism. This is an important difference from the radial momentum distributions, for which diffractive processes play an important role. The author discusses stripping reactions of {sup 11}Be and {sup 8}B on light nuclei yielding {sup 10}Be and {sup 7}Be.

  17. Ground states of larger nuclei

    SciTech Connect

    Pieper, S.C.; Wiringa, R.B.; Pandharipande, V.R.

    1995-08-01

    The methods used for the few-body nuclei require operations on the complete spin-isospin vector; the size of this vector makes such methods impractical for nuclei with A > 8. During the last few years we developed cluster expansion methods that do not require operations on the complete vector. We use the same Hamiltonians as for the few-body nuclei and variational wave functions of form similar to the few-body wave functions. The cluster expansions are made for the noncentral parts of the wave functions and for the operators whose expectation values are being evaluated. The central pair correlations in the wave functions are treated exactly and this requires the evaluation of 3A-dimensional integrals which are done with Monte Carlo techniques. Most of our effort was on {sup 16}O, other p-shell nuclei, and {sup 40}Ca. In 1993 the Mathematics and Computer Science Division acquired a 128-processor IBM SP which has a theoretical peak speed of 16 Gigaflops (GFLOPS). We converted our program to run on this machine. Because of the large memory on each node of the SP, it was easy to convert the program to parallel form with very low communication overhead. Considerably more effort was needed to restructure the program from one oriented towards long vectors for the Cray computers at NERSC to one that makes efficient use of the cache of the RS6000 architecture. The SP made possible complete five-body cluster calculations of {sup 16}O for the first time; previously we could only do four-body cluster calculations. These calculations show that the expectation value of the two-body potential is converging less rapidly than we had thought, while that of the three-body potential is more rapidly convergent; the net result is no significant change to our predicted binding energy for {sup 16}O using the new Argonne v{sub 18} potential and the Urbana IX three-nucleon potential. This result is in good agreement with experiment.

  18. Breakup Densities of Hot Nuclei

    NASA Astrophysics Data System (ADS)

    Viola, V. E.; Kwiatkowski, K.; Natowitz, J. B.; Yennello, S. J.

    2004-09-01

    Breakup densities of hot 197Au-like residues have been deduced from the systematic trends of Coulomb parameters required to fit intermediate-mass-fragment kinetic-energy spectra. The results indicate emission from nuclei near normal nuclear density below an excitation energy E*/A≲2 MeV, followed by a gradual decrease to a near-constant value of ρ/ρ0˜0.3 for E*/A≳5 MeV. Temperatures derived from these data with a density-dependent Fermi-gas model yield a nuclear caloric curve that is generally consistent with those derived from isotope ratios.

  19. Superdeformation in the mercury nuclei

    SciTech Connect

    Janssens, R.V.F.; Carpenter, M.P.; Fernandez, P.B.; Moore, E.F.; Ahmad, I.; Khoo, T.L.; Wolfs, F.L.H. ); Drigert, M.W. ); Ye, D.; Beard, K.B.; Garg, U.; Reviol, W. ); Bearden, I.G.; Benet, P.; Daly, P.J.; Grabowski, Z.W. )

    1990-01-01

    We shall first summarize the present experimental situation concerning {sup 192}Hg, the nucleus regarded as the analog of {sup 152}Dy for this superdeformation (SD) region in that gaps are calculated to occur at large deformation for Z = 80 and N = 112. Proton and neutron excitations out of the {sup 192}Hg core will then be reviewed with particular emphasis on {sup 191}Hg and {sup 193}Tl. The presentation will conclude with a brief discussion on limits of the SD region for neutron deficient Hg nuclei. 26 refs., 10 figs.

  20. Thermal evolution of cometary nuclei

    NASA Technical Reports Server (NTRS)

    Prialnik, Dina

    1989-01-01

    The long-term thermal evolution in models of comet nuclei is examined. Models of the nucleus surface and interior are discussed and the equations of comet nucleus evolution are analyzed. The thermal evolution of a nucleus in Comet P/Halley's orbit is outlined. The effects of temperature, composition, and orbital parameters on the evolutionary course are examined. Consideration is given to the implications of the assumption that new comets are pristine objects which have undergone little alteration and constitute a source of original solar nebula material.

  1. Pre-equilibrium decay processes in energetic heavy ion reactions

    SciTech Connect

    Blann, M.

    1986-04-15

    The Boltzmann master equation (BME) is defined for application to precompound decay in heavy ion reactions in the 10 100 MeV/nucleon regime. Predicted neutron spectra are compared with measured results for central collisions of /sup 20/Ne and /sup 12/C with /sup 165/Ho target nuclei. Comparisons are made with subthreshold ..pi../sup 0/ yields in heavy ion reactions between 35 and 84 MeV/nucleon, and with the ..pi../sup 0/ spectra. The BME is found to be an excellent tool for investigating these experimentally observed aspects of non-equilibrium heavy ion reactions. 18 refs., 8 figs.

  2. Nucleosynthesis of heavy elements in the r-process

    SciTech Connect

    Panov, I. V.

    2016-03-15

    The current state of the problem of heavy-element production in the astrophysical r-process is surveyed. The nucleosynthesis process in the neutron-star-merger scenario, within which the problem of free-neutron source is solved, is considered most comprehensively. A model that describes well the observed abundances of heavy elements is examined. Theoretical approaches used in this model to calculate a number of features of short-lived neutron-rich nuclei are described. The contributions of various fission processes to the production of heavy elements are assessed. The possibility of superheavy-element production in the r-process is demonstrated.

  3. Transcription in Isolated Wheat Nuclei

    PubMed Central

    Luthe, Dawn Sywassink; Quatrano, Ralph S.

    1980-01-01

    Nuclei free of RNase activity were isolated from 3-hour-imbibed wheat (var. Yamhill) embryos by centrifugation through a discontinuous gradient of Percoll. The maximum rate of RNA synthesis observed in these nuclei was approximately 5 picomoles [3H]UTP per milligram DNA per minute. Two monovalent cation optima were found when measured in the presence of 15 millimolar MgCl2 or 2 millimolar MnCl2; 15 and 75 millimolar (NH4)2SO4. At the high monovalent cation optimum, the rate of RNA synthesis was linear for the first 10 to 15 minutes of incubation and still increasing after 3 hours. RNA synthesized in vitro (30-minute pulse followed by a 30-minute chase) showed distinct 18 and 26S RNA peaks comprising 13 and 17% of the total radioactivity, respectively. The over-all pattern of RNA synthesized in vitro was similar to the in vivo pattern. Approximately 40 to 50% of the RNA synthesized was inhibited by α-amanitin at 4 micrograms per milliliter. The newly synthesized 6 to 10S RNA appeared to be selectively inhibited by α-amanitin. PMID:16661179

  4. Selfconsistent calculations for hyperdeformed nuclei

    SciTech Connect

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

    1996-12-31

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

  5. Physical Processing of Cometary Nuclei

    NASA Technical Reports Server (NTRS)

    Weissman, Paul R.; Stern, S. Alan

    1997-01-01

    Cometary nuclei preserve a cosmo-chemical record of conditions and processes in the primordial solar nebula, and possibly even the interstellar medium. However, that record is not perfectly preserved over the age of the solar system due to a variety of physical processes which act to modify cometary surfaces and interiors. Possible structural and/or internal processes include: collisional accretion, disruption, and reassembly during formation; internal heating by long and short-lived radionuclides; amorphous to crystalline phase transitions, and thermal stresses. Identified surface modification processes include: irradiation by galactic cosmic rays, solar protons, UV photons, and the Sun's T Tauri stage mass outflow; heating by passing stars and nearby supernovae; gardening by debris impacts; the accretion of interstellar dust and gas and accompanying erosion by hypervelocity dust impacts and sputtering; and solar heating with accompanying crust formation. These modification processes must be taken into account in both the planning and the interpretation of the results of a Comet Nucleus Sample Return Mission. Sampling of nuclei should be done at as great a depth below the surface crust as technically feasible, and at vents or fissures leading to exposed volatiles at depth. Samples of the expected cometary crust and near-surface layers also need to be returned for analysis to achieve a better understanding of the effects of these physical processes. We stress that comets are still likely less modified dm any other solar system bodies, but the degree of modification can vary greatly from one comet to the next.

  6. Physical Processing of Cometary Nuclei

    NASA Astrophysics Data System (ADS)

    Weissman, Paul R.; Stern, S. Alan

    1997-12-01

    Cometary nuclei preserve a cosmo-chemical record of conditions and processes in the primordial solar nebula, and possibly even the interstellar medium. However, that record is not perfectly preserved over the age of the solar system due to a variety of physical processes which act to modify cometary surfaces and interiors. Possible structural and/or internal processes include: collisional accretion, disruption, and reassembly during formation; internal heating by long and short-lived radionuclides; amorphous to crystalline phase transitions, and thermal stresses. Identified surface modification processes include: irradiation by galactic cosmic rays, solar protons, UV photons, and the Sun's T Tauri stage mass outflow; heating by passing stars and nearby supernovae; gardening by debris impacts; the accretion of interstellar dust and gas and accompanying erosion by hypervelocity dust impacts and sputtering; and solar heating with accompanying crust formation. These modification processes must be taken into account in both the planning and the interpretation of the results of a Comet Nucleus Sample Return Mission. Sampling of nuclei should be done at as great a depth below the surface crust as technically feasible, and at vents or fissures leading to exposed volatiles at depth. Samples of the expected cometary crust and near-surface layers also need to be returned for analysis to achieve a better understanding of the effects of these physical processes. We stress that comets are still likely less modified dm any other solar system bodies, but the degree of modification can vary greatly from one comet to the next.

  7. ISOLATION OF SKELETAL MUSCLE NUCLEI

    PubMed Central

    Edelman, Jean C.; Edelman, P. Michael; Knigge, Karl M.; Schwartz, Irving L.

    1965-01-01

    A method employing aqueous media for isolation of nuclei from rat skeletal muscle is described. The technique involves (a) mincing and then homogenizing in a 0.32 M sucrose-salt solution with a Potter-Elvehjem type homogenizer using a Delrin (an acetal resin) pestle and a carefully controlled, relatively large pestle-to-glass clearance, (b) filtering through fiberglass and stainless steel screens of predetermined mesh size to remove myofibrils and connective tissue, and (c) centrifuging in a 2.15 M sucrose-salt solution containing 0.7 mM ATP. Electron and phase-contrast microscopic observations show that the nuclei are intact, unencumbered by cytoplasmic tags, and possess well preserved distinct nucleoli, nucleoplasm, and nuclear membranes. Cytoplasmic contamination is minimal and mainly mitochondrial. Chemical assays of the nuclear fraction show that the DNA/protein and RNA/DNA ratios are comparable to those obtained in other tissues. These ratios, as well as the low specific activity obtained for cytochrome c oxidase and the virtual absence of myofibrillar ATPase, indicate a high degree of purity with minimal mitochondrial and myofibrillar contamination. The steps comprising the technique and the reasons for their selection are discussed. PMID:4287141

  8. Mass-23 nuclei in astrophysics

    NASA Astrophysics Data System (ADS)

    Fraser, P. R.; Amos, K.; Canton, L.; Karataglidis, S.; Svenne, J. P.; van der Kniff, D.

    2015-09-01

    The formation of mass-23 nuclei by radiative capture is of great interest in astrophysics. A topical problem associated with these isobars is the so-called 22Na puzzle of ONe white dwarf novae, where the abundance of 22Na observed is not as is predicted by current stellar models, indicating there is more to learn about how the distribution of elements in the universe occurred. Another concerns unexplained variations in elements abundance on the surface of aging red giant stars. One method for theoretically studying nuclear scattering is the Multi-Channel Algebraic Scattering (MCAS) formalism. Studies to date have used a simple collective-rotor prescription to model the target states which couple to projectile nucleons. While, in general, the target states considered all belong to the ground state rotor band, for some systems it is necessary to include coupling to states outside of this band. Herein we discuss an extension of MCAS to allow coupling of different strengths between such states and the ground state band. This consideration is essential when studying the scattering of neutrons from 22Ne, a necessary step in studying the mass-23 nuclei mentioned above.

  9. Breast cancer cell nuclei classification in histopathology images using deep neural networks.

    PubMed

    Feng, Yangqin; Zhang, Lei; Yi, Zhang

    2017-08-31

    Cell nuclei classification in breast cancer histopathology images plays an important role in effective diagnose since breast cancer can often be characterized by its expression in cell nuclei. However, due to the small and variant sizes of cell nuclei, and heavy noise in histopathology images, traditional machine learning methods cannot achieve desirable recognition accuracy. To address this challenge, this paper aims to present a novel deep neural network which performs representation learning and cell nuclei recognition in an end-to-end manner. The proposed model hierarchically maps raw medical images into a latent space in which robustness is achieved by employing a stacked denoising autoencoder. A supervised classifier is further developed to improve the discrimination of the model by maximizing inter-subject separability in the latent space. The proposed method involves a cascade model which jointly learns a set of nonlinear mappings and a classifier from the given raw medical images. Such an on-the-shelf learning strategy makes obtaining discriminative features possible, thus leading to better recognition performance. Extensive experiments with benign and malignant breast cancer datasets are conducted to verify the effectiveness of the proposed method. Better performance was obtained when compared with other feature extraction methods, and higher recognition rate was achieved when compared with other seven classification methods. We propose an end-to-end DNN model for cell nuclei and non-nuclei classification of histopathology images. It demonstrates that the proposed method can achieve promising performance in cell nuclei classification, and the proposed method is suitable for the cell nuclei classification task.

  10. Studies of yrast and continuum states in A=140-160 nuclei. Progress report, January 1, 1980-December 31, 1980. [Purdue Univ. , 1/1/80-12/31/80

    SciTech Connect

    Daly, P.J.

    1981-01-01

    The structure of nuclei in the A approx. 150 region was investigated by in-beam ..gamma..-ray spectroscopy using heavy-ion beams, mostly from the Argonne Tandem-Linac. Results for the nuclei /sup 148/Dy, /sup 149/Dy, /sup 153/Dy, /sup 154/Dy, /sup 149/Ho, and /sup 150/Ho are summarized. The feeding of yrast states in these nuclei and the link between the highest known yrast states and the continuum region were also studied. 6 figures.

  11. PHYSICAL STUDIES OF ISOLATED EUCARYOTIC NUCLEI

    PubMed Central

    Olins, Donald E.; Olins, Ada L.

    1972-01-01

    The degree of chromatin condensation in isolated rat liver nuclei and chicken erythrocyte nuclei was studied by phase-contrast microscopy as a function of solvent pH, K+ and Mg++ concentrations Data were represented as "phase" maps, and standard solvent conditions selected that reproducibly yield granular, slightly granular, and homogeneous nuclei Nuclei in these various states were examined by ultraviolet absorption and circular dichroism (CD) spectroscopy, low-angle X-ray diffraction, electron microscopy, and binding capacity for ethidium bromide Homogeneous nuclei exhibited absorption and CD spectra resembling those of isolated nucleohistone. Suspensions of granular nuclei showed marked turbidity and absorption flattening, and a characteristic blue-shift of a crossover wavelength in the CD spectra. In all solvent conditions studied, except pH < 2 3, low-angle X-ray reflections characteristic of the native, presumably superhelical, nucleohistone were observed from pellets of intact nuclei. Threads (100–200 A diameter) were present in the condensed and dispersed phases of nuclei fixed under the standard solvent conditions, and examined in the electron microscope after thin sectioning and staining Nuclei at neutral pH, with different degrees of chromatin condensation, exhibited similar binding capacities for ethidium bromide. These data suggest a model that views chromatin condensation as a close packing of superhelical nucleohistone threads but still permits condensed chromatin to respond rapidly to alterations in solvent environment. PMID:4554987

  12. Mass yield distributions of fission products from photo-fission of 238U induced by 11.5-17.3 MeV bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Naik, H.; Carrel, Frédérick; Kim, G. N.; Laine, Frédéric; Sari, Adrien; Normand, S.; Goswami, A.

    2013-07-01

    The yields of various fission products in the 11.5, 13.4, 15.0 and 17.3 MeV bremsstrahlung-induced fission of 238U have been determined by recoil catcher and an off-line γ-ray spectrometric technique using the electron linac, SAPHIR at CEA, Saclay, France. The mass yield distributions were obtained from the fission product yields using charge-distribution corrections. The peak-to-valley ( P/ V ratio, average light mass (< A L>) and heavy mass (< A H>) and average number of neutrons (< v>) in the bremsstrahlung-induced fission of 238U at different excitation energies were obtained from the mass yield data. From the present and literature data in the 238U ( γ, f ) and 238U ( n, f ) reactions at various energies, the following observations were obtained: i) The mass yield distributions in the 238U ( γ, f ) reaction at various energies of the present work are double-humped, similar to those of the 238U ( n, f ) reaction of comparable excitation energy. ii) The yields of fission products for A = 133-134, A = 138-140, and A = 143-144 and their complementary products in the 238U ( γ, f) reaction are higher than other fission products due to the nuclear structure effect. iii) The yields of fission products for A = 133-134 and their complementary products are slightly higher in the 238U ( γ, f ) than in the 238U ( n, f ) , whereas for A = 138-140 and 143-144 and their complementary products are comparable. iv) With excitation energy, the increase of yields of symmetric products and the decrease of the peak-to-valley ( P/ V ratio in the 238U ( γ, f) reaction is similar to the 238U ( n, f) reaction. v) The increase of < v> with excitation energy is also similar between the 238U ( γ, f ) and 238U ( n, f) reactions. However, it is surprising to see that the < A L> and < A H> values with excitation energy behave entirely differently from the 238U ( γ, f ) and 238U ( n, f ) reactions.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  14. Building Relativistic Mean-Field Models for Atomic Nuclei and Neutron Stars

    NASA Astrophysics Data System (ADS)

    Chen, Wei-Chia; Piekarewicz, Jorge

    2014-03-01

    Nuclear energy density functional (EDF) theory has been quite successful in describing nuclear systems such as atomic nuclei and nuclear matter. However, when building new models, attention is usually paid to the best-fit parameters only. In recent years, focus has been shifted to the neighborhood around the minimum of the chi-square function as well. This powerful covariance analysis is able to provide important information bridging experiments, observations, and theories. In this work, we attempt to build a specific type of nuclear EDFs, the relativistic mean-field models, which treat atomic nuclei, nuclear matter, and neutron stars on the same footing. The application of covariance analysis can reveal correlations between observables of interest. The purpose is to elucidate the alleged relations between the neutron skin of heavy nuclei and the size of neutron stars, and to develop insight into future investigations.

  15. Scaling of the F_2 structure function in nuclei and quark distributions at x>1

    SciTech Connect

    Fomin, N; Arrington, J; Gaskell, D; Daniel, A; Seely, J; Asaturyan, R; Benmokhtar, F; Boeglin, W; Boillat, B; Bosted, P; Bruell, A; Bukhari, M.H.S.; Christy, M E; Chudakov, E; Clasie, B; Connell, S H; Dalton, M M; Dutta, D; Ent, R; El Fassi, L; Fenker, H; Filippone, B W; Garrow, K; Hill, C; Holt, R J; Horn, T; Jones, M K; Jourdan, J; Kalantarians, N; Keppel, C E; Kiselev, D; Kotulla, M; Lindgren, R; Lung, A F; Malace, S; Markowitz, P; McKee, P; Meekins, D G; Miyoshi, T; Mkrtchyan, H; Navasardyan, T; Niculescu, G; Okayasu, Y; Opper, A K; Perdrisat, C; Potterveld, D H; Punjabi, V; Qian, X; Reimer, P E; Roche, J; Rodriguez, V M; Rondon, O; Schulte, E; Segbefia, E; Slifer, K; Smith, G R; Solvignon, P; Tadevosyan, V; Tajima, S; Tang, L; Testa, G; Tvaskis, V; Vulcan, W F; Wasko, C; Wesselmann, F R; Wood, S A; Wright, J; Zheng, X

    2010-11-01

    We present new data on electron scattering from a range of nuclei taken in Hall C at Jefferson Lab. For heavy nuclei, we observe a rapid falloff in the cross section for $x>1$, which is sensitive to short range contributions to the nuclear wave-function, and in deep inelastic scattering corresponds to probing extremely high momentum quarks. This result agrees with higher energy muon scattering measurements, but is in sharp contrast to neutrino scattering measurements which suggested a dramatic enhancement in the distribution of the `super-fast' quarks probed at x>1. The falloff at x>1 is noticeably stronger in ^2H and ^3He, but nearly identical for all heavier nuclei.

  16. High spin spectroscopy of near spherical nuclei: Role of intruder orbitals

    SciTech Connect

    Bhattacharyya, S.; Bhattacharjee, T.; Mukherjee, G.; Banerjee, D.; Das, S. K.; Guin, R.; Gupta, S. Das

    2014-08-14

    High spin states of nuclei in the vicinity of neutron shell closure N = 82 and proton shell closure Z = 82 have been studied using the Clovere Ge detectors of Indian National Gamma Array. The shape driving effects of proton and neutron unique parity intruder orbitals for the structure of nuclei around the above shell closures have been investigated using light and heavy ion beams. Lifetime measurements of excited states in {sup 139}Pr have been done using pulsed-beam-γ coincidence technique. The prompt spectroscopy of {sup 207}Rn has been extended beyond the 181μs 13/2{sup +} isomer. Neutron-rich nuclei around {sup 132}Sn have been produced from proton induced fission of {sup 235}U and lifetime measurement of low-lying states of odd-odd {sup 132}I have been performed from offline decay.

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

    NASA Astrophysics Data System (ADS)

    Chowdhury, P.; Hota, S. S.; Qiu, Y.; Ahmad, I.; Carpenter, M. P.; Greene, J. P.; Janssens, R. V. F.; Khoo, T. L.; Kondev, F. G.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Zhu, S.

    2016-09-01

    The heaviest nuclei where excitations above the ground state can be studied lie near Z ~ 100. These 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.

  18. Nuclear spectroscopy of r-process nuclei around N = 126 using KISS

    NASA Astrophysics Data System (ADS)

    Hirayama, Y.; Watanabe, Y. X.; Miyatake, H.; Schury, P.; Wada, M.; Oyaizu, M.; Kakiguchi, Y.; Mukai, M.; Kimura, S.; Ahmed, M.; Jeong, S. C.; Moon, J. Y.; Park, J. H.

    2017-09-01

    The beta-decay properties and atomic mass of nuclei with neutron magic number of N = 126 are considered critical for understanding the production of heavy elements such as gold and platinum at astrophysical sites. We will produce and measure the half-lives and masses of the nuclei with Z = 74-77 around N = 126 by using the multinucleon transfer (MNT) reaction of ^{136} Xe/ ^{238} U beams and ^{198} Pt target system. For this purpose, we have constructed the KEK Isotope Separation System (KISS) at RIKEN RIBF facility. KISS consists of an argon gas cell based laser ion source (atomic number selection) and an isotope separation on-line (ISOL) (mass number selection), to produce pure low-energy beams of neutron-rich isotopes around N = 126 . We performed the on-line tests to study the basic properties of the KISS and, successfully extracted laser-ionized nuclei around N = 126.

  19. ECCO: Th/U/Pu/Cm Dating of Galactic Cosmic Ray Nuclei

    NASA Technical Reports Server (NTRS)

    Westphal, A. J.; Weaver, B. A.; Solarz, M.; Dominquez, G.; Craig, N.; Adams, J. H.; Barbier, L. M.; Christian, E. R.; Mitchell, J. W.; Binns, W. R.; hide

    2001-01-01

    The ECCO (Extremely-heavy Cosmic-ray Composition Observer) instrument is one of two instruments which comprise the HNX (Heavy Nuclei Explorer) mission. The principal goal of ECCO is to measure the age of galactic cosmic ray nuclei using the actinides (Th, U, Pu, Cm) as clocks. As a bonus, ECCO will search with unprecedented sensitivity for long-lived elements in the superheavy island of stability. ECCO is an enormous array (23 sq. m) of BP-1 glass track-etch detectors, and is based on the successful flight heritage of the Trek detector which was deployed externally on Mir. We present a description of the instrument, estimates of expected performance, and recent calibrations which demonstrate that the actinides can be resolved from each other with good charge resolution.

  20. ECCO: Th/U/Pu/Cm Dating of Galactic Cosmic Ray Nuclei

    NASA Technical Reports Server (NTRS)

    Westphal, A. J.; Weaver, B. A.; Solarz, M.; Dominquez, G.; Craig, N.; Adams, J. H.; Barbier, L. M.; Christian, E. R.; Mitchell, J. W.; Binns, W. R.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    The ECCO (Extremely-heavy Cosmic-ray Composition Observer) instrument is one of two instruments which comprise the HNX (Heavy Nuclei Explorer) mission. The principal goal of ECCO is to measure the age of galactic cosmic ray nuclei using the actinides (Th, U, Pu, Cm) as clocks. As a bonus, ECCO will search with unprecedented sensitivity for long-lived elements in the superheavy island of stability. ECCO is an enormous array (23 sq. m) of BP-1 glass track-etch detectors, and is based on the successful flight heritage of the Trek detector which was deployed externally on Mir. We present a description of the instrument, estimates of expected performance, and recent calibrations which demonstrate that the actinides can be resolved from each other with good charge resolution.

  1. IBA for novice experimentalists. I. Introduction to IBA: mostly symmetries. II. Tests in even-even nuclei: mostly transitional systems. III. Supersymmetries: theory and experiment

    SciTech Connect

    Cizewski, J.A.

    1982-08-01

    The report contains the notes from a series of lectures on the Interacting Boson Approximation (IBA) model. The lectures were presented at Lawrence Livermore National Laboratory on July 28, 30 and August 1, 1982 by Jolie A. Cizewski from Yale University. The IBA was developed by F. Iachello and A. Arima starting about seven years ago to understand collective quadrupole excitations in medium and heavy mass nuclei away from closed shells. Since then the formalism has been extended to odd-mass nuclei and considerable work has gone into understanding the microscopic construction of the bosons in this model. The IBA has been applied to nuclei as light as Zn and Ge and as heavy as U and Pu; to nuclei near closed shells, such as Mo and Hg; to stable nuclei and nuclei far from stability. The present lectures were designed to give the experimentalist an introduction to the IBA and to give specific examples of how it could be applied to understand the structure of heavy even and odd mass nuclei. Much of the emphasis was on the symmetries (and supersymmetries) of the model and how the use of symmetries enabled the relatively straightforward understanding of empirical systems as deviations from these symmetries. The richness of possible applications of the IBA to understanding collective phenomena in nuclei was not fully explored, but rather a few illustrative examples were selected and described in detail. The references, accumulated at the end of this report, provide a more comprehensive, although not complete, list of tests of the IBA in even mass nuclei and the new symmetries in odd mass nuclei. The references also list the main theoretical papers which provide the details of the IBA formalism.

  2. Correlations of heavy quarks produced at the Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Younus, Mohammed; Jamil, Umme; Srivastava, Dinesh K.

    2012-02-01

    We study the correlations of heavy quarks produced in relativistic heavy-ion collisions and find them to be quite sensitive to the effects of the medium and the production mechanisms. In order to put this on a quantitative footing, as a first step, we analyze the azimuthal, transverse momentum, and rapidity correlations of heavy quark-antiquark (Q\\overline{Q}) pairs in pp collisions at {O}(α3s). This sets the stage for the identification and study of medium modification of similar correlations in the relativistic collision of heavy nuclei at the Large Hadron Collider. Next we study the additional production of charm quarks in heavy ion collisions due to multiple scatterings, namely jet-jet collisions, jet-thermal collisions, and thermal interactions. We find that these give rise to azimuthal correlations which are quite different from those arising from the prompt initial production at leading order and at next to leading order. Communicated by Professor Steffen Bass.

  3. Fragmentation of N-14 nuclei at 29 GeV - Inclusive isotope spectra at 0 deg.

    NASA Technical Reports Server (NTRS)

    Heckman, H. H.; Greiner, D. E.; Lindstrom, P. J.; Bieser, F. S.

    1972-01-01

    We report the first results of a Bevatron heavy-ion experiment on the inclusive spectra of isotopically identified nuclei 3(Z-range between 3 and 7), produced by the fragmentation of 29-GeV N-14 ions in carbon and hydrogen. The preliminary values of the partial differential cross sections at 0 deg give evidence that the modes of fragmentation of N-14 projectiles are independent of the target nucleus.

  4. The method of event selection for nuclei separation with the calorimeter in the PAMELA experiment

    NASA Astrophysics Data System (ADS)

    Karelin, A. V.; Likhacheva, V. L.; Voronov, S. A.

    2016-02-01

    Here we discuss a method for a study of the heavy nuclei cosmic ray composition. The method is based on a charge separation with the PAMELA calorimeter. The work is in progress now. The ability is presented to carry out measurements up to Fe and Ni. As a result we expect to get important data about the abundance of the chemical elements in the cosmic rays.

  5. Neutron halo in deformed nuclei

    SciTech Connect

    Zhou Shangui; Meng Jie; Ring, P.; Zhao Enguang

    2010-07-15

    Halo phenomena in deformed nuclei are investigated within a deformed relativistic Hartree Bogoliubov (DRHB) theory. These weakly bound quantum systems present interesting examples for the study of the interdependence between the deformation of the core and the particles in the halo. Contributions of the halo, deformation effects, and large spatial extensions of these systems are described in a fully self-consistent way by the DRHB equations in a spherical Woods-Saxon basis with the proper asymptotic behavior at a large distance from the nuclear center. Magnesium and neon isotopes are studied and detailed results are presented for the deformed neutron-rich and weakly bound nucleus {sup 44}Mg. The core of this nucleus is prolate, but the halo has a slightly oblate shape. This indicates a decoupling of the halo orbitals from the deformation of the core. The generic conditions for the occurrence of this decoupling effects are discussed.

  6. Single Pion production from Nuclei

    SciTech Connect

    Singh, S. K.; Athar, M. Sajjad; Ahmed, S.

    2007-12-21

    We have studied charged current one pion production induced by {nu}{sub {mu}}({nu}-bar{sub {mu}}) from some nuclei. The calculations have been done for the incoherent pion production processes from these nuclear targets in the {delta} dominance model and take into account the effect of Pauli blocking, Fermi motion and renormalization of {delta} properties in the nuclear medium. The effect of final state interactions of pions has also been taken into account. The numerical results have been compared with the recent results from the MiniBooNE experiment for the charged current 1{pi} production, and also with some of the older experiments in Freon and Freon-Propane from CERN.

  7. The Physics of Cometary Nuclei

    NASA Technical Reports Server (NTRS)

    Whipple, Fred L.

    1997-01-01

    The recent developments in cometary studies suggest rather low mean densities and weak structures for the nuclei. They appear to be accumulations of fairly discrete units loosely bound together, as deduced from the observations of Comet Shoemaker-Levy 9 during its encounter with Jupiter. The compressive strengths deduced from comet splitting by Opik and Sekanina are extremely low. These values are confirmed by theory developed here. assuming that Comet P/Holmes had a companion that collided with it in 1892. There follows a short discussion that suggests that the mean densities of comets should increase with comet dimensions. The place of origin of short-period comets may relate to these properties.

  8. Inclusive breakup of Borromean nuclei

    NASA Astrophysics Data System (ADS)

    Hussein, M. S.; Carlson, B. V.; Frederico, T.

    2017-06-01

    We derive the inclusive breakup cross section of a three-fragment projectile nuclei, a = b + x 1 +x 2, in the spectator model. The resulting four-body cross section for observing b, is composed of the elastic breakup cross section which contains information about the correlation between the two participant fragments, and the inclusive non-elastic breakup cross section. This latter cross section is found to be a non-trivial four-body generalization of the Austern formula [1], which is proportional to a matrix element of the form, . The new feature here is the three-body absorption, represented by the imaginary potential, W 3b . We analyze this type of absorption and supply ideas of how to calculate its contribution.

  9. Breakup Densities of Hot Nuclei.

    NASA Astrophysics Data System (ADS)

    Viola, Vic

    2006-04-01

    Breakup densities of hot ^197Au-like residues have been deduced from the systematic trends of Coulomb parameters required to fit intermediate-mass-fragment kinetic-energy spectra. The results indicate emission from nuclei near normal nuclear density below an excitation energy E*/A .3ex<˜x 2 MeV, followed by a gradual decrease to a near-constant value of ρ/ρ0˜ 3 for E*/A .3ex>˜x 5 MeV. Temperatures derived from these data with a density-dependent Fermi-gas model yield a nuclear caloric curve that is generally consistent with those derived from isotope ratios.

  10. Quasifree kaon photoproduction on nuclei

    SciTech Connect

    Frank Lee; T. MART; Cornelius Bennhold; Lester Wright

    2001-12-01

    Investigations of the quasifree reaction A({gamma}, K Y)B are presented in the distorted wave impulse approximation (DWIA). For this purpose, we present a revised tree-level model of elementary kaon photoproduction that incorporates hadronic form factors consistent with gauge invariance, uses SU(3) values for the Born couplings and uses resonances consistent with multi-channel analyses. The potential of exclusive quasifree kaon photoproduction on nuclei to reveal details of the hyperon-nucleus interaction is examined. Detailed predictions for the coincidence cross section, the photon asymmetry, and the hyperon polarization and their sensitivities to the ingredients of the model are obtained for all six production channels. Under selected kinematics these observables are found to be sensitive to the hyperon-nucleus final state interaction. Some polarization observables are found to be insensitive to distortion effects, making them ideal tools to search for possible medium modifications of the elementary amplitude.

  11. Reaction theory for exotic nuclei

    SciTech Connect

    Bonaccorso, Angela

    2014-05-09

    Exotic nuclei are usually defined as those with unusual N/Z ratios. They can be found in the crust of neutron stars enbedded in a sea of electrons or created in laboratory by fragmentation of a primary beam (in-flight method) or of the target (ISOL method). They are extremely important for nuclear astrophysics, see for example Ref.[1]. Furthermore by studying them we can check the limits of validity of nuclear reaction and structure models. This contribution will be devoted to the understanding of how by using reaction theory and comparing to the data we can extract structure information. We shall discuss the differences between the mechanisms of transfer and breakup reactions, an we will try to explain how nowadays it is possible to do accurate spectroscopy in extreme conditions.

  12. Proton emission from triaxial nuclei

    SciTech Connect

    Delion, D.S.; Wyss, R.; Karlgren, D.; Liotta, R.J.

    2004-12-01

    Proton decay from triaxially deformed nuclei is investigated. The deformation parameters corresponding to the mother nucleus are determined microscopically and the calculated decay widths are used to probe the mean-field wave function. The proton wave function in the mother nucleus is described as a resonant state in a coupled-channel formalism. The decay width, as well as the angular distribution of the decaying particle, are evaluated and their dependence upon the triaxial deformation parameters is studied in the decay of {sup 161}Re and {sup 185}Bi. It is found that the decay width is very sensitive to the parameters defining the triaxial deformation while the angular distribution is a universal function which does not depend upon details of the nuclear structure.

  13. Energy density functional for nuclei and neutron stars

    NASA Astrophysics Data System (ADS)

    Erler, J.; Horowitz, C. J.; Nazarewicz, W.; Rafalski, M.; Reinhard, P.-G.

    2013-04-01

    it also reproduces expected neutron star data within assumed error bands. This functional is expected to yield more reliable predictions in the region of very neutron rich heavy nuclei.

  14. Covariant density functional theory: Global performance and rotating nuclei

    NASA Astrophysics Data System (ADS)

    Ray, Debisree

    Covariant density functional theory (CDFT) is a modern theoretical tool for the description of nuclear structure physics. Here different physical properties of the ground and excited states in atomic nuclei have been investigated within the CDFT framework employing three major classes of the state-of-the-art covariant energy density functionals. The global performance of CEDFs for even-even nuclei are investigated and the systematic theoretical uncertainties are estimated within the set of four CEDFs in known regions of the nuclear chart and their propagation towards the neutron drip line. Large-scale axial relativistic Hartree-Bogoliubov (RHB) calculations are performed for even-even nuclei to calculate different ground state observables. The predictions for the two-neutron drip line are also compared in a systematic way with the non-relativistic results. CDFT has been applied for systematic study of extremely deformed, rotating N ˜ Z nuclei of the A ˜ 40 mass region. At spin zero such structures are located at high energies which prevents their experimental observation. The rotation acts as a tool to bring these exotic shapes down to the yrast line so that their observation could become possible with a future generation detectors such as GRETA or AGATA. The major physical observables of such structures, the underlying single-particle structure and the spins at which they become yrast or near yrast are defined. The search for the fingerprints of clusterization and molecular structures is performed and the configurations with such features are discussed. CDFT has been applied to study fission barriers of superheavy nuclei and related systematic theoretical uncertainties in the predictions of inner fission barrier heights in super- heavy elements. Systematic uncertainties are substantial in superheavy elements and their behavior as a function of proton and neutron numbers contains a large random component. The benchmarking of the functionals to the experimental

  15. Fission fragment angular distributions in pre-actinide nuclei

    NASA Astrophysics Data System (ADS)

    Banerjee, Tathagata; Nath, S.; Jhingan, A.; Kaur, Gurpreet; Dubey, R.; Yadav, Abhishek; Laveen, P. V.; Shamlath, A.; Shareef, M.; Gehlot, J.; Saneesh, N.; Prasad, E.; Sugathan, P.; Pal, Santanu

    2016-10-01

    Background: Complete fusion of two nuclei leading to formation of a heavy compound nucleus (CN) is known to be hindered by various fission-like processes, in which the composite system reseparates after capture of the target and the projectile inside the potential barrier. As a consequence of these non-CN fission (NCNF) processes, fusion probability (PCN) starts deviating from unity. Despite substantial progress in understanding, the onset and the experimental signatures of NCNF and the degree of its influence on fusion have not yet been unambiguously identified. Purpose: This work aims to investigate the presence of NCNF, if any, in pre-actinide nuclei by systematic study of fission angular anisotropies and fission cross sections (σfis) in a number of nuclear reactions carried out at and above the Coulomb barrier (VB) . Method: Fission fragment angular distributions were measured for six 28Si-induced reactions involving isotopically enriched targets of 169Tm,176Yb,175Lu,180Hf,181Ta, and 182W leading to probable formation of CN in the pre-actinide region, at a laboratory energy (Elab) range of 129-146 MeV. Measurements were performed with large angular coverage (θlab=41∘ -170∘) in which fission fragments (FFs) were detected by nine hybrid telescope (E -Δ E ) detectors. Extracted fission angular anisotropies and σfis were compared with statistical model (SM) predictions. Results: Barring two reactions involving targets with large non-zero ground state spin (J ) , viz., 175Lu(7/2+) and 181Ta(7/2+) , experimental fission angular anisotropies were found to be higher in comparison with predictions of the statistical saddle point model (SSPM), at Ec .m . near VB. Comparison of present results with those from neighboring systems revealed that experimental anisotropies increasingly deviated from SSPM predictions as one moved from pre-actinide to actinide nuclei. For reactions involving targets with large nonzero J , this deviation was subdued. Comparison between

  16. Towards the exact calculation of medium nuclei

    SciTech Connect

    Gandolfi, Stefano; Carlson, Joseph Allen; Lonardoni, Diego; Wang, Xiaobao

    2016-12-19

    The prediction of the structure of light and medium nuclei is crucial to test our knowledge of nuclear interactions. The calculation of the nuclei from two- and three-nucleon interactions obtained from rst principle is, however, one of the most challenging problems for many-body nuclear physics.

  17. Ice nuclei emissions from biomass burning

    Treesearch

    Markus D. Petters; Matthew T. Parsons; Anthony J. Prenni; Paul J. DeMott; Sonia M. Kreidenweis; Christian M. Carrico; Amy P. Sullivan; Gavin R. McMeeking; Ezra Levin; Cyle E. Wold; Jeffrey L. Collett; Hans Moosmuller

    2009-01-01

    Biomass burning is a significant source of carbonaceous aerosol in many regions of the world. When present, biomass burning particles may affect the microphysical properties of clouds through their ability to function as cloud condensation nuclei or ice nuclei. We report on measurements of the ice nucleation ability of biomass burning particles performed on laboratory-...

  18. Thalamic nuclei after human blunt head injury.

    PubMed

    Maxwell, William L; MacKinnon, Mary Anne; Smith, Douglas H; McIntosh, Tracy K; Graham, David I

    2006-05-01

    Paraffin-embedded blocks from the thalamus of 9 control patients, 9 moderately disabled, 12 severely disabled, and 10 vegetative head-injured patients assessed using the Glasgow Outcome Scale and identified from the Department of Neuropathology archive. Neurons, astrocytes, macrophages, and activated microglia were differentiated by Luxol fast blue/cresyl violet, GFAP, CD68, and CR3/43 staining and stereological techniques used to estimate cell number in a 28-microm-thick coronal section. Counts were made in subnuclei of the mediodorsal, lateral posterior, and ventral posterior nuclei, the intralaminar nuclei, and the related internal lamina. Neuronal loss occurred from mediodorsal parvocellularis, rostral center medial, central lateral and paracentral nuclei in moderately disabled patients; and from mediodorsal magnocellularis, caudal center medial, rhomboid, and parafascicular nuclei in severely disabled patients; and all of the above and the centre median nucleus in vegetative patients. Neuronal loss occurred primarily from cognitive and executive function nuclei, a lesser loss from somatosensory nuclei and the least loss from limbic motor nuclei. There was an increase in the number of reactive astrocytes, activated microglia, and macrophages with increasing severity of injury. The study provides novel quantitative evidence for differential neuronal loss, with survival after human head injury, from thalamic nuclei associated with different aspects of cortical activation.

  19. Atomic parity nonconservation, neutron radii, and effective field theories of nuclei

    SciTech Connect

    Sil, Tapas; Centelles, M.; Vinas, X.; Piekarewicz, J.

    2005-04-01

    Accurately calibrated effective field theories are used to compute atomic parity nonconserving (APNC) observables. Although accurately calibrated, these effective field theories predict a large spread in the neutron skin of heavy nuclei. Whereas the neutron skin is strongly correlated to numerous physical observables, in this contribution we focus on its impact on new physics through APNC observables. The addition of an isoscalar-isovector coupling constant to the effective Lagrangian generates a wide range of values for the neutron skin of heavy nuclei without compromising the success of the model in reproducing well-constrained nuclear observables. Earlier studies have suggested that the use of isotopic ratios of APNC observables may eliminate their sensitivity to atomic structure. This leaves nuclear structure uncertainties as the main impediment for identifying physics beyond the standard model. We establish that uncertainties in the neutron skin of heavy nuclei are at present too large to measure isotopic ratios to better than the 0.1% accuracy required to test the standard model. However, we argue that such uncertainties will be significantly reduced by the upcoming measurement of the neutron radius in {sup 208}Pb at the Jefferson Laboratory.

  20. Heavy Rescue - Course Outline.

    DTIC Science & Technology

    1980-11-01

    used during heavy rescue operations . Methods and procedures for utilizing heavy rescue equipment. 4 Methods of developing improvised rescue equipment...utilizing available materials. A simulated exercise utilizing various rescue operations and techniques. Methods and procedures for the maintenance and...HEAVY RESCUE CONSIDERATIONS LEVEL I PERFORMANCE GOALS: 1 Hour GIVEN: 1. Summary of blocked access considerations during heavy rescue operations 2

  1. PSEUDOSPIN SYMMETRY IN NUCLEI, SPIN SYMMETRY IN HADRONS

    SciTech Connect

    P. PAGE; T. GOLDMAN; J. GINOCCHIO

    2000-08-01

    Ginocchio argued that chiral symmetry breaking in QCD is responsible for the relativistic pseudospin symmetry in the Dirac equation, explaining the observed approximate pseudospin symmetry in sizable nuclei. On a much smaller scale, it is known that spin-orbit splittings in hadrons are small. Specifically, new experimental data from CLEO indicate small splittings in D-mesons. For heavy-light mesons we identify a cousin of pseudospin symmetry that suppresses these splittings in the Dirac equation, known as spin symmetry. We suggest an experimental test of the implications of spin symmetry for wave functions in electron-positron annihilation. We investigate how QCD can give rise to two different dynamical symmetries on nuclear and hadronic scales.

  2. High baryon densities in heavy ion collisions at energies attainable at the BNL Relativistic Heavy-Ion Collider and the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Li, Ming; Kapusta, Joseph I.

    2017-01-01

    In very high-energy collisions nuclei are practically transparent to each other but produce very hot nearly baryon-free matter in the so-called central rapidity region. The energy in the central rapidity region comes from the kinetic energy of the colliding nuclei. We calculate the energy and rapidity loss of the nuclei using the color glass condensate model. This model also predicts the excitation energy of the nuclear fragments. Using a space-time picture of the collision we calculate the baryon and energy densities of the receding baryonic fireballs. For central collisions of gold nuclei at the highest energy attainable at the Relativistic Heavy-Ion Collider, for example, we find baryon densities more than ten times that of atomic nuclei over a large volume.

  3. 76 FR 63702 - In the Matter of the Designation of Conspiracy of Fire Nuclei, aka Conspiracy of the Nuclei of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-13

    ... Conspiracy of Fire Nuclei, aka Conspiracy of the Nuclei of Fire, aka Conspiracy of Cells of Fire, aka Synomosia of Pyrinon Tis Fotias, aka Thessaloniki-Athens Fire Nuclei Conspiracy, as a Specially Designated... that the organization known as Conspiracy of Fire Nuclei, also known as Conspiracy of the Nuclei...

  4. Heavy-ion radiotherapy

    NASA Astrophysics Data System (ADS)

    Kanai, Tatsuaki

    2000-11-01

    Heavy-ion radiotherapy using high-energy carbon beams has been performed at the National Institute of Radiological Sciences, Japan. The physical frame works for heavy-ion radiotherapy are established using physical understandings of radiation physics. In order to increase the accuracy of heavy-ion radiotherapy, many physical problems should be solved. Unsolved problems, such as the depth dose distributions, range of heavy-ion in patients and heavy-ion dosimetry in the radiation therapy, are discussed. .

  5. [Galactic heavy charged particles damaging effect on biological structures].

    PubMed

    Grigor'ev, A I; Krasavin, E A; Ostrovskiĭ, M A

    2013-03-01

    A concept of the radiation risk of the manned interplanetary flights is proposed and substantiated. Heavy charged particles that are a component of the galactic cosmic rays (GCR) have a high damaging effect on the biological structures as great amount of energy is deposited in heavy particle tracks. The high biological effectiveness of heavy ions is observed in their action on cell genetic structures and the whole organism, including the brain structures. The hippocampus is the part of the central nervous system that is the most sensitive to radiation--first of all, to heavy charged particles. Irradiation of animals with accelerated iron ions at doses corresponding to the real fluxes of GCR heavy nuclei, to which Mars mission crews can be exposed, leads to marked behavioral function disorders in the post-irradiation period. To evaluate the radiation risk for the interplanetary flight crews, the concept of successful mission accomplishment is introduced. In these conditions, the central nervous system structures can be the critical target of GCR heavy nuclei. Their damage can modify the higher integrative functions of the brain and cause disorders in the crew members' operator performances.

  6. Systematic study of α decay half-lives of doubly odd nuclei within the two-potential approach

    NASA Astrophysics Data System (ADS)

    Sun, Xiao-Dong; Deng, Jun-Gang; Xiang, Dong; Guo, Ping; Li, Xiao-Hua

    2017-04-01

    α decay is a common and important process of natural radioactivity of the heavy and superheavy nuclei. From the α decay of nuclei, we can obtain much more information of nuclei structure. In our previous works [X.-D. Sun et al., Phys. Rev. C 93, 034316 (2016), 10.1103/PhysRevC.93.034316; X.-D. Sun et al., Phys. Rev. C 95, 014319 (2017), 10.1103/PhysRevC.95.014319], we have done systematic study on the α preformation probability of both the even-even and odd-A nuclei within the two-potential approach. The α preformation probabilities will systematically change due to the shell effect, proton-neutron correlation, and so on. This work is the extension of the previous works. In this work, we systematically study the α decay of doubly odd nuclei. We find that for superallowed α decay the α preformation probabilities of doubly odd nuclei are larger than those of odd-A ones in general, and for the heavier nuclei the extra neutrons suppress the proton-neutron correlation resulting in the small α preformation probabilities. The calculated results can well reproduce the experimental half-lives. The half-lives of the α decay chain beginning from nuclide 296119 are also predicted and compared with various empirical formulas.

  7. Orientation dependent behavior of the Coulomb barrier parameters for deformed-deformed nuclei

    NASA Astrophysics Data System (ADS)

    Ismail, M.; Adel, A.

    2011-06-01

    The Coulomb barrier parameters (radius, R, and height, V) for the interaction between two deformed nuclei are calculated in phenomenological way in the framework of the double folding model with the realistic M3Y nucleon-nucleon ( NN) interaction. The variations of R and V for the reactions Ar48+Pu238, Mg26+Cm248, Mg26+U238, and Ne22+U238 in the orientation degrees of freedom are investigated. It is found that the distribution of the Coulomb barrier parameters in the orientation degrees of freedom shows almost the same patterns as the sum of the nuclear radii of the interacting nuclei along the direction of the separation vector joining their two centers of mass. The orientation Coulomb barrier radius distribution follows the same variations as the sum of radii while the barrier height distribution follows it inversely. This correlation (anticorrelation) between R ( V) and the nuclear radii of the deformed nuclei dose not give the values of R and V. This suggests a simple and straightforward way to predict the behavior of the barrier parameters with different orders of deformations without performing the heavy numerical calculations necessary when the two nuclei are being deformed. It also allows us to estimate, with reasonable accuracy, the compact and elongated configurations of the interacting nuclei which lead to hot and cold fusion reactions, respectively.

  8. Strangeness in nuclei and neutron stars

    NASA Astrophysics Data System (ADS)

    Lonardoni, Diego

    2017-01-01

    The presence of exotic particles in the core of neutron stars (NS) has been questioned for a long time. At present, it is still an unsolved problem that drives intense research efforts, both theoretical and experimental. The appearance of strange baryons in the inner regions of a NS, where the density can exceed several times the nuclear saturation density, is likely to happen due to energetic considerations. The onset of strange degrees of freedom is considered as an effective mechanism to soften the equation of state (EoS). This softening affects the entire structure of the star, reducing the pressure and therefore the maximum mass that the star can stably support. The observation of two very massive NS with masses of the order of 2M⊙ seems instead to rule out soft EoS, apparently excluding the possibility of hyperon formation in the core of the star. This inconsistency, usually referred to as the hyperon puzzle, is based on what we currently know about the interaction between strange particles and normal nucleons. The combination of a poor knowledge of the hypernuclear interactions and the difficulty of obtaining clear astrophysical evidence of the presence of hyperons in NS makes the understanding of the behavior of strange degrees of freedom in NS an intriguing theoretical challenge. We give our contribution to the discussion by studying the general problem of the hyperon-nucleon interaction. We attack this issue by employing a quantum Monte Carlo (QMC) technique, that has proven to be successful in the description of strongly correlated Fermion systems, to the study of finite size nuclear systems including strange degrees of freedom, i.e. hypernuclei. We show that many-body hypernuclear forces are fundamental to properly reproduce the ground state physics of Λ hypernuclei from light- to medium-heavy. However, the poor abundance of experimental data on strange nuclei leaves room for a good deal of indetermination in the construction of hypernuclear

  9. Fission and Properties of Neutron-Rich Nuclei - Proceedings of the Second International Conference

    NASA Astrophysics Data System (ADS)

    Hamilton, J. H.; Phillips, W. R.; Carter, H. K.

    The Table of Contents for the book is as follows: * Preface * Structure of Elementary Matter: Cold Valleys and Their Importance in Fission, Fusion and for Superheavy Nuclei * Tunnelling Phenomena in Nuclear Physics * Heavy Nuclei Studies Using Transfer Reactions * Isomeric Properties of Nuclei Near 78Ni * Investigation of Light Actinide Nuclei at Yale and Beyond * U-Projectile Fission at Relativistic Energies * Cluster Description of Cold Fission Modes in 252Cf * Neutron-pair Transfer Theory for Pear-shaped Ba Fission Fragments * New RMFA Parameters of Normal and Exotic Nuclei * Study of Fission Fragments from 12C+238U Reactions: Prompt and Delayed Spectroscopy * γ-Ray Angular Correlations in 252Cf and 248Cm Fission Fragments * Fragment Angular Momentum and Descent Dynamics in 252Cf Spontaneous Fission * The Experimental Investigation of Neutron-Rich Nuclei * High-Spin Structure of Some Odd-Z Nuclei with A ≈ 100 From Heavy-Ion Induced Fission * Coexistence of Symmetric and Asymmetric Nuclear Shapes and 10Be Ternary Fission * Octupole Effects in the Lanthanides * High Spin Structure of the 113-1l6Cd Isotopes Produced by Heavy-Ion Induced Fission Reaction * Temperature-Dependent Fission Barriers and Mass Distributions for 239U * Strength Distributions for Gamow Teller Transitions in Very Weakly Bound Systems * High Spin Fragmentation Spectroscopy * Search for a Four-Neutron Transfer From 8He to 4He * Microsecond Isomers in Fission Fragments in the Vicinity of the Doubly Magic 132Sn * Recent On-Line NMR/on Nuclear Magnetic Dipole Moments Near 132Sn: Meson Exchange Current Effects at the Shell Closure and Shell Model Treatment of Variation with Proton and Neutron Number * High-spin K-Isomers Beyond the Fusion Limit * High Energy Neutron Induced Fission: Charge Yield Distributions and Search and Spectroscopy of New Isomers * Hartree-Fock Mean-Field Models Using Separable Interactions * Variation of Fission Characteristics Over the Nuclear Chart * Investigation of

  10. Incoherent {pi}{sup 0} photoproduction from complex nuclei

    SciTech Connect

    Rodrigues, T.E.; Mesa, J.; Garcia, C.; Arruda-Neto, J.D.T.; Dale, D.; Nakagawa, I.

    2005-05-01

    Incoherent {pi}{sup 0} photoproduction from nuclei is evaluated via a multicollisional intranuclear cascade framework. In-medium modifications are taken into account, including a realistic dynamical treatment of multiple {pi}N and {delta}N scattering processes throughout the cascade. This time-dependent analysis yields structures in the {sup 12}C {pi}{sup 0} differential cross section both in the {delta} region and in the photon energy range from 5 to 6 GeV, with the former in very nice agreement with recent results from Mainz Microton. For heavy nuclei, however, such structures disappear because of a more effective Fermi motion and a relatively higher final state interaction of the produced pions as they exit the nucleus. The calculation of the incoherent part of the total {pi}{sup 0} photoproduction propitiates a clean and powerful kinematical separation from competitive (electromagnetic/nuclear) production processes, which currently is a theoretical challenge for the PrimEx experiment at the Jefferson Lab.

  11. Method to look for imprints of ultrahigh energy nuclei sources

    NASA Astrophysics Data System (ADS)

    Giacinti, G.; Semikoz, D. V.

    2011-04-01

    We propose a new method to search for heavy nuclei sources, on top of background, in the Ultra-High Energy Cosmic Ray data. We apply this method to the 69 events recently published by the Pierre Auger Collaboration [P. Abreu (Pierre Auger Observatory Collaboration), Astropart. Phys.APHYEE0927-6505 34, 314 (2010).10.1016/j.astropartphys.2010.08.010] and find a tail of events for which it reconstructs the source at a few degrees from the Virgo galaxy cluster. The reconstructed source is located at ≃8.5° from M87. The probability to have such a cluster of events in some random background and reconstruct the source position in any direction of the sky is about 7×10-3. The probability to reconstruct the source at less than 10° from M87 in a data set already containing such a cluster of events is about 4×10-3. This may be a hint at the Virgo cluster as a bright ultrahigh energy nuclei source. We investigate the ability of current and future experiments to validate or rule out this possibility, and discuss several alternative solutions which could explain the existing anisotropy in the Auger data.

  12. Collisions of deformed nuclei and superheavy-element production

    SciTech Connect

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

    1995-09-01

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

  13. A microscopic multiphonon approach to even and odd nuclei

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

    The formalism of an equation of motion phonon method is briefly outlined. In even-even nuclei, the method derives equations of motion which generate an orthonormal basis of correlated n-phonon states (n = 0, 1, 2, ...), built of constituent Tamm-Dancoff phonons, and, then, solves the nuclear eigenvalue problem in such a multiphonon basis. In odd nuclei, analogous equations yield a basis of correlated orthonormal multiphonon particle-core states to be used for the solution of the full eigenvalue equations. The formalism does not rely on approximations, but lends itself naturally to simplifying assumptions. As illustrated here, the method has been implemented numerically for studying the electric dipole response in the heavy neutron rich 208Pb and 132Sn and in the odd 17O and 17F. Self-consistent calculations, using a chiral inspired Hamiltonian, have confirmed the important role of the multiphonon states in enhancing the fragmentation of the strength in the giant and pygmy resonance regions consistently with the experimental data.

  14. Mushrooms as Rainmakers: How Spores Act as Nuclei for Raindrops

    PubMed Central

    2015-01-01

    Millions of tons of fungal spores are dispersed in the atmosphere every year. These living cells, along with plant spores and pollen grains, may act as nuclei for condensation of water in clouds. Basidiospores released by mushrooms form a significant proportion of these aerosols, particularly above tropical forests. Mushroom spores are discharged from gills by the rapid displacement of a droplet of fluid on the cell surface. This droplet is formed by the condensation of water on the spore surface stimulated by the secretion of mannitol and other hygroscopic sugars. This fluid is carried with the spore during discharge, but evaporates once the spore is airborne. Using environmental electron microscopy, we have demonstrated that droplets reform on spores in humid air. The kinetics of this process suggest that basidiospores are especially effective as nuclei for the formation of large water drops in clouds. Through this mechanism, mushroom spores may promote rainfall in ecosystems that support large populations of ectomycorrhizal and saprotrophic basidiomycetes. Our research heightens interest in the global significance of the fungi and raises additional concerns about the sustainability of forests that depend on heavy precipitation. PMID:26509436

  15. Magnetic moments of light nuclei from lattice quantum chromodynamics

    SciTech Connect

    Beane, S.  R.; Chang, E.; Cohen, S.; Detmold, W.; Lin, H.  W.; Orginos, K.; Parreño, A.; Savage, M.  J.; Tiburzi, B.  C.

    2014-12-16

    We present the results of lattice QCD calculations of the magnetic moments of the lightest nuclei, the deuteron, the triton and 3He, along with those of the neutron and proton. These calculations, performed at quark masses corresponding to mπ ~ 800 MeV, reveal that the structure of these nuclei at unphysically heavy quark masses closely resembles that at the physical quark masses. We find that the magnetic moment of 3He differs only slightly from that of a free neutron, as is the case in nature, indicating that the shell-model configuration of two spin-paired protons and a valence neutron captures its dominant structure. Similarly a shell-model-like moment is found for the triton, μ3H ~ μp. The deuteron magnetic moment is found to be equal to the nucleon isoscalar moment within the uncertainties of the calculations.

  16. Cluster emissions with ? daughter from neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Kumar, Satish; Batra, J. S.; Gupta, Raj K.

    1996-02-01

    Cluster emissions from neutron-rich 0954-3899/22/2/006/img2, and 0954-3899/22/2/006/img3 nuclei are studied within the preformed cluster model of Malik and Gupta. Q-value estimates of the decays selected on the basis of shell effects in binding energies and their relative preformation probabilities show that these nuclei are stable (Q<0) against 0954-3899/22/2/006/img4 and 0954-3899/22/2/006/img5 decays and all the metastable (Q>0) decays are of non-alpha-like heavy clusters. The most probable decays (minimum half-life times) are the ones with a doubly magic 0954-3899/22/2/006/img6 nucleus as the daughter nucleus, arising due to the WKB penetrability. Compared to the presently measurable alpha-like cluster decays of the corresponding neutron-deficient parents into a 0954-3899/22/2/006/img7 daughter nucleus, these decays are suppressed by many orders of magnitude.

  17. Mushrooms as Rainmakers: How Spores Act as Nuclei for Raindrops.

    PubMed

    Hassett, Maribeth O; Fischer, Mark W F; Money, Nicholas P

    2015-01-01

    Millions of tons of fungal spores are dispersed in the atmosphere every year. These living cells, along with plant spores and pollen grains, may act as nuclei for condensation of water in clouds. Basidiospores released by mushrooms form a significant proportion of these aerosols, particularly above tropical forests. Mushroom spores are discharged from gills by the rapid displacement of a droplet of fluid on the cell surface. This droplet is formed by the condensation of water on the spore surface stimulated by the secretion of mannitol and other hygroscopic sugars. This fluid is carried with the spore during discharge, but evaporates once the spore is airborne. Using environmental electron microscopy, we have demonstrated that droplets reform on spores in humid air. The kinetics of this process suggest that basidiospores are especially effective as nuclei for the formation of large water drops in clouds. Through this mechanism, mushroom spores may promote rainfall in ecosystems that support large populations of ectomycorrhizal and saprotrophic basidiomycetes. Our research heightens interest in the global significance of the fungi and raises additional concerns about the sustainability of forests that depend on heavy precipitation.

  18. Optical model analyses of heavy ion fragmentation in hydrogen targets

    NASA Technical Reports Server (NTRS)

    Townsend, Lawrence W.

    1994-01-01

    Quantum-mechanical optical-model methods for calculating cross sections for the fragmentation of high-energy heavy ions by hydrogen targets are presented. The cross sections are calculated with a knockout-ablation collision formalism which has no arbitrary fitting parameters. Predictions of elemental production cross sections from the fragmentation of 1.2A Ge(V(La-139) nuclei and of isotope production cross sections from the fragmentation of 400A MeV(S-32) nuclei are in good agreement with recently reported experimental measurements.

  19. Galactic heavy-ion shielding using electrostatic fields

    NASA Technical Reports Server (NTRS)

    Townsend, L. W.

    1984-01-01

    The shielding of spacecraft against galactic heavy ions, particularly high-energy Fe(56) nuclei, by electrostatic fields is analyzed for an arrangement of spherical concentric shells. Vacuum breakdown considerations are found to limit the minimum radii of the spheres to over 100 m. This limitation makes it impractical to use the fields for shielding small spacecraft. The voltages necessary to repel these Fe(56) nuclei exceed present electrostatic generating capabilities by over 2 orders of magnitude and render the concept useless as an alternative to traditional bulk-material shielding methods.

  20. Ice Nuclei from Birch Trees

    NASA Astrophysics Data System (ADS)

    Felgitsch, Laura; Seifried, Teresa; Winkler, Philipp; Schmale, David, III; Grothe, Hinrich

    2017-04-01

    While the importance of heterogeneous ice nucleation in the atmosphere is known, we still know very little about the substances triggering these freezing events. Recent findings support the theory that biological ice nuclei (IN) exhibit the ability to play an important role in these processes. Huffman et al. (2013) showed a burst of biological IN over woodlands triggered by rain events. Birch pollen are known to release a high number of efficient IN if incubated in water (Pummer et al. 2012). Therefore birches are of interest in our research on this topic. Plants native to the timberline, such as birch trees, have to cope with very cold climatic conditions, rendering freezing avoidance impossible. These plants trigger freezing in their extracellular spaces to control the freezing process and avoid intracellular freezing, which would have lethal consequences. The plants hereby try to freeze at a temperature well above homogeneous freezing temperatures but still at temperatures low enough to not be effected by brief night frosts. To achieve this, IN are an important tool. The specific objective of our work was to study the potential sources and distribution of IN in birch trees. We collected leaves, fruit, bark, and trunk cores from a series of mature birch trees in Tyrol, Austria at different altitudes and sampling sites. We also collected samples from a birch tree in an urban park in Vienna, Austria. Our data show a sampling site dependence and the distribution of IN throughout the tree. Our data suggest that leaves, bark, and wood of birch can function as a source of IN, which are easily extracted with water. The IN are therefore not restricted to pollen. Hence, the amount of IN, which can be released from birch trees, is tremendous and has been underrated so far. Future work aims to elucidate the nature, contribution, and potential ecological roles of IN from birch trees in different habitats. Huffman, J.A., Prenni, A.J., DeMott, P.J., Pöhlker, C., Mason, R