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Sample records for rich nuclei close

  1. The study of neutron-rich nuclei production in the region of the closed shell N=126 in the multi-nucleon transfer reaction 136Xe+208Pb

    NASA Astrophysics Data System (ADS)

    Novikov, K.; Harca, I. M.; Kozulin, E. M.; Dmitriev, S.; Itkis, J.; Knyazheva, G.; Loktev, T.; Corradi, L.; Valiente-Dobon, J.; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Vardaci, E.; Quero, D.; Montagnoli, G.; Scarlassara, F.; Strano, E.; Pollarolo, G.; Piot, J.; Mijatović, T.; Szilner, S.; Ackermann, D.; Chubarian, G.; Trzaska, W. H.

    2016-04-01

    The unexplored area of heavy neutron rich nuclei is extremely important for nuclear astrophysics investigations and, in particular, for the understanding of the r-process of astrophysical nucleogenesis. For the production of heavy neutron rich nuclei located along the neutron closed shell N=126 (probably the last "waiting point" in the r-process of nucleosynthesis) the low-energy multi-nucleon transfer reaction 136Xe+208Pb at Elab=870MeV was explored. Due to the stabilizing effect of the closed neutron shells in both nuclei, N=82 and N=126, and the rather favorable proton transfer from lead to xenon, the light fragments formed in this process are well bound and the Q-value of the reaction is nearly zero. Measurements were performed with the PRISMA spectrometer in coincidence with an additional time-of-flight (ToF) arm on the +20 beam line of the PIAVE-ALPI accelerator in Legnaro, Italy. The PRISMA spectrometer allows identification of the A, Z and velocity of the projectile-like fragments (PLF), while the second arm gives access to the target-like fragments (TLF). Details on the experimental setup and preliminary results are reported.

  2. 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.

  3. Structure of neutron-rich nuclei

    SciTech Connect

    Nazarewicz, W. ||

    1997-11-01

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

  4. On Closed Shells in Nuclei

    DOE R&D Accomplishments Database

    Mayer, M. G.

    1948-02-01

    It has been suggested in the past that special numbers of neutrons or protons in the nucleus form a particularly stable configuration.{sup1} The complete evidence for this has never been summarized, nor is it generally recognized how convincing this evidence is. That 20 neutrons or protons (Ca{sup40}) form a closed shell is predicted by the Hartree model. A number of calculations support this fact.{sup2} These considerations will not be repeated here. In this paper, the experimental facts indicating a particular stability of shells of 50 and 82 protons and of 50, 82, and 126 neutrons will be listed.

  5. Structure of neutron-rich nuclei around the N = 126 closed shell; the yrast structure of 205Au126 up to spin-parity I^{π} = (19/2+)

    NASA Astrophysics Data System (ADS)

    Podolyák, Zs.; Steer, S. J.; Pietri, S.; Górska, M.; 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.; Grebosz, 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, B. 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.

    2009-12-01

    Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a ensuremath ^{208}_{ 82}Pb beam at ensuremath E/A = 1 GeV on a ensuremath 2.5 g/cm^2 thick Be target. The synthesised nuclei were selected and identified in-flight using the fragment separator at GSI. Approximately 300 ns after production, the selected nuclei were implanted in an ensuremath ˜ 8 mm thick perspex stopper, positioned at the centre of the RISING ensuremath γ -ray detector spectrometer array. A previously unreported isomer with a half-life ensuremath T_{1/2} = 163(5) ns has been observed in the N = 126 closed-shell nucleus ensuremath ^{205}_{ 79}Au . Through γ -ray singles and γ - γ coincidence analysis a level scheme was established. The comparison with a shell model calculation tentatively identifies the spin-parity of the excited states, including the isomer itself, which is found to be ensuremath I^{π} = (19/2^+).

  6. Clusters in neutron-rich light nuclei

    NASA Astrophysics Data System (ADS)

    Jelavić Malenica, D.; Milin, M.; Di Pietro, A.; Figuera, P.; Lattuada, M.; Miljanić, D.; Musumarra, A.; Pellegriti, M. G.; Prepolec, L.; Scuderi, V.; Skukan, N.; Soić, N.; Torresi, D.; Uroić, M.

    2016-05-01

    Due to their high selectivity, transfer and sequential decay reactions are powerful tools for studies of both single particle (nucleon) and cluster states in light nuclei. Their use is particularly simple for investigations of α-particle clustering (because α-particle has Jπ=0+, which simplifies spin and parity assignments to observed cluster states), but they are also easily applicable to other types of clustering. Recent results on clustering in neutron-rich isotopes of beryllium, boron and carbon obtained measuring the 10B+10B reactions (at 50 and 72 MeV) are presented. The highly efficient and segmented detector systems used, built from 4 Double Sided Silicon Strip Detectors (DSSSD) allowed detection of double and multiple coincidences and, in that way, studies of states populated in transfer reactions, as well as their sequential decay.

  7. Relativistic mean field calculations in neutron-rich nuclei

    SciTech Connect

    Gangopadhyay, G.; Bhattacharya, Madhubrata; Roy, Subinit

    2014-08-14

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

  8. 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.

  9. 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.

  10. On Closed Shells in Nuclei. II

    DOE R&D Accomplishments Database

    Mayer, M. G.

    1949-04-01

    Discussion on the use of spins and magnetic moments of the even-odd nuclei by Feenberg and Nordheim to determine the angular momentum of the eigenfunction of the odd particle; discussion of prevalence of isomerism in certain regions of the isotope chart; tabulated data on levels of square well potential, spectroscopic levels, spin term, number of states, shells and known spins and orbital assignments.

  11. 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.

  12. Three-Body Forces and Proton-Rich Nuclei

    SciTech Connect

    Holt, Jason D; Menendez, J.

    2013-01-01

    We present the first study of three-nucleon (3N) forces for proton-rich nuclei along the N 8 and N 20 isotones. Our results for the ground-state energies and proton separation energies are in very good agreement with experiment where available, and with the empirical isobaric multiplet mass equation. We predict the spectra for all N 8 and N 20 isotones to the proton dripline, which agree well with experiment for 18Ne, 19Na, 20Mg and 42Ti. In all other cases, we provide first predictions based on nuclear forces. Our results are also very promising for studying isospin symmetry breaking in medium-mass nuclei based on chiral effective field theory.

  13. 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.

  14. 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.

  15. 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.

  16. Fission and Properties of Neutron-Rich Nuclei

    NASA Astrophysics Data System (ADS)

    Hamilton, Joseph H.; Ramayya, A. V.; Carter, H. K.

    2008-08-01

    Opening session. Nuclear processes in stellar explosions / M. Wiescher. In-beam [symbol]-ray spectroscopy of neutron-rich nuclei at NSCL / A. Gade -- Nuclear structure I. Shell-model structure of neutron-rich nuclei beyond [symbol]Sn / A. Covello ... [et al.]. Shell structure and evolution of collectivity in nuclei above the [symbol]Sn core / S. Sarkar and M. S. Sarkar. Heavy-ion fusion using density-constrained TDHF / A. S. Umar and V. E. Oberacker. Towards an extended microscopic theory for upper-fp shell nuclei / K. P. Drumev. Properties of the Zr and Pb isotopes near the drip-line / V. N. Tarasov ... [et al.]. Identification of high spin states in [symbol] Cs nuclei and shell model calculations / K. Li ... [et al.]. Recent measurements of spherical and deformed isomers using the Lohengrin fission-fragment spectrometer / G. S. Simpson ... [et al.] -- Nuclear structure II. Nuclear structure investigation with rare isotope spectroscopic investigations at GSI / P. Boutachkov. Exploring the evolution of the shell structures by means of deep inelastic reactions / G. de Anaelis. Probing shell closures in neutron-rich nuclei / R. Krücken for the S277 and REX-ISOLDEMINIBALL collaborations. Structure of Fe isotopes at the limits of the pf-shell / N. Hoteling ... [et al.]. Spectroscopy of K isomers in shell-stabilized trans-fermium nuclei / S. K. Tandel ... [et al.] -- Radioactive ion beam facilities. SPIRAL2 at GANIL: a world leading ISOL facility for the next decade / S. Gales. New physics at the International Facility for Antiproton and Ion Research (FAIR) next to GSI / I. Augustin ... [et al.]. Radioactive beams from a high powered ISOL system / A. C. Shotter. RlKEN RT beam factory / T. Motobayashi. NSCL - ongoing activities and future perspectives / C. K. Gelbke. Rare isotope beams at Argonne / W. F. Henning. HRIBF: scientific highlights and future prospects / J. R. Beene. Radioactive ion beam research done in Dubna / G. M. Ter-Akopian ... [et al.] -- Fission I

  17. Nuclear Forces and Their Impact on Neutron-Rich Nuclei and Neutron-Rich Matter

    NASA Astrophysics Data System (ADS)

    Hebeler, K.; Holt, J. D.; Menéndez, J.; Schwenk, A.

    2015-10-01

    We review the impact of nuclear forces on matter at neutron-rich extremes. Recent results have shown that neutron-rich nuclei become increasingly sensitive to three-nucleon forces, which are at the forefront of theoretical developments based on effective field theories of quantum chromodynamics. These developments include the formation of shell structure, the spectroscopy of exotic nuclei, and the location of the neutron drip line. Nuclear forces also constrain the properties of neutron-rich matter, including the neutron skin, the symmetry energy, and the structure of neutron stars. First, we review our understanding of three-nucleon forces and show how chiral effective field theory makes unique predictions for many-body forces. Then, we survey results with three-nucleon forces in neutron-rich oxygen and calcium isotopes and neutron-rich matter, which have been explored with a range of many-body methods. Three-nucleon forces therefore provide an exciting link between theoretical, experimental, and observational nuclear physics frontiers.

  18. Liquid-drop model for extremely neutron rich nuclei

    SciTech Connect

    Fisher, J.C.

    1998-08-01

    Nuclear energy levels are characterized in part by their isospin quantum numbers. Ordinary nuclides are well described by an independent-particle model with ground-state isospins equal to the minimum possible value T{sub min} = abs(A/2 {minus} Z). It has been suggested that extremely neutron rich nuclei constitute a second branch of the table of isotopes whose ground states have the maximum possible isospin T{sub max} = A/2 and that neutral members of the T{sub max} branch (i.e., polyneutrons) serve as mediating particles for the new class of nuclear reactions discovered by Fleischmann and Pons. The energetics of the new reactions have been qualitatively described by a liquid-drop model. Recent measurements of the mass spectrum of reaction products produced in the new reactions make possible a refinement of the model, providing an explanation for gaps of instability separating ranges of stability in the mass spectrum.

  19. New Band Structures in Aapprox110 Neutron-Rich Nuclei

    SciTech Connect

    Zhu, S. J.; Wang, J. G.; Ding, H. B.; Gu, L.; Xu, Q.; Yeoh, E. Y.; Xiao, Z. G.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Liu, S. H.; Li, K.; Luo, Y. X.; Rasmussen, J. O.; Lee, I. Y.; Qi, B.; Meng, J.

    2010-05-12

    The high spin states of neutron-rich nuclei in Aapprox110 region have been carefully investigated by measuring prompt gamma-gamma-gamma coincident measurements populated in the spontaneous fission of {sup 252}Cf with the Gammasphere detector array. Many new collective bands have been discovered. In this proceeding paper, we introduce some interesting new band structures recently observed by our cooperative groups, that is, the one-phonon- and two-phonon gamma-vibrational bands in odd-A {sup 103}Nb, {sup 105}Mo and {sup 107}Tc, the chiral doublet bands in even-even {sup 106}Mo, {sup 110}Ru and {sup 112}Ru, and the pseudospin partner bands with in {sup 108}Tc. The characteristics of these band structures have been discussed.

  20. Soft Dipole Modes of Neutron-Rich Nuclei

    NASA Astrophysics Data System (ADS)

    Csoto, A.; Gibson, B. F.; Afnan, I. R.

    1996-10-01

    We explore the open question of whether valance neutrons in ``halo nuclei'' can oscillate against the core to create a ``soft dipole'' mode. It has been suggested that such a dipole state would be situated at a few MeV of excitation energy, in contrast to usual dipole excitations at higher energies. The existence of a soft dipole mode, at least in ^11Li, appears to be supported by certain theoretical models and experimental data.footnote A. C. Hayes, Comments in Nuclear and Particle Physics 22, 27 (1996) However, this conclusion is based upon the behavior of specific observables at real energies. To clearly establish the existence of such resonant states, one should locate the corresponding complex poles of the S-matrix. We study ^6He and ^11Li in a three-body model based upon separable potentials that describe the known physics of the underlying two-body interactions. We solve the resulting Faddeev equations, continued into the complex energy plane, to search for the low lying excited states of these neutron-rich light nuclei.

  1. 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.

  2. 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.

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

    SciTech Connect

    Yoshida, Kenichi

    2011-05-06

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

  4. Experimental study of neutron-rich nuclei near the N = 82 closed shell using the {sub 40}{sup 96}Zr+{sub 50}{sup 124}Sn reaction with GASP and PRISMA-CLARA arrays

    SciTech Connect

    Rodríguez, W.; Torres, D. A.; Cristancho, F.; Medina, N. H.; Chapman, R.; Smith, J. F.; Mengoni, D.; Truesdale, V.; Grocutt, L.; Mulholland, K.; Kumar, V.; Hadinia, B.; Labiche, M.; Liang, X.; O'Donell, D.; Ollier, J.; Orlandi, R.; Smith, J. F.; Spohr, K. M.; Wady, P.; and others

    2014-11-11

    In this contribution an experimental study of the deep-inelastic reaction {sub 40}{sup 96}Zr+{sub 50}{sup 124}Sn at 530 MeV, using the GASP and PRISMA-CLARA arrays, is presented. The experiments populate a wealth of projectile-like and target-like binary fragments, in a large neutron-rich region around N ≥ 50 and Z ≈ 40. Preliminary results on the study of the yrast and near-yrast states for {sup 95}Nb will be shown, along with a comparison of the experimental yields obtained in the experiments.

  5. 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.

  6. Technology-Rich Schools Up Close

    ERIC Educational Resources Information Center

    Levin, Barbara B.; Schrum, Lynne

    2013-01-01

    This article observes that schools that use technology well have key commonalities, including a project-based curriculum and supportive, distributed leadership. The authors' research into tech-rich schools revealed that schools used three strategies to integrate technology successfully. They did so by establishing the vision and culture,…

  7. Technology-Rich Schools Up Close

    ERIC Educational Resources Information Center

    Levin, Barbara B.; Schrum, Lynne

    2013-01-01

    This article observes that schools that use technology well have key commonalities, including a project-based curriculum and supportive, distributed leadership. The authors' research into tech-rich schools revealed that schools used three strategies to integrate technology successfully. They did so by establishing the vision and culture,…

  8. Structure and reactions of light neutron rich nuclei

    SciTech Connect

    Esbensen, H.

    1993-01-01

    Radioactive beam experiments have made it possible to study the structure of nuclei at the neutron drip line. Pair correlations play a crucial role in such nuclei and characteristic features include an extended neutron halo density and a large dipole strength near threshold. The most detailed studies have been performed for [sup 11]Li. I will present a 3-body model that explains the main features of the data obtained for this nucleus.

  9. Structure and reactions of light neutron rich nuclei

    SciTech Connect

    Esbensen, H.

    1993-04-01

    Radioactive beam experiments have made it possible to study the structure of nuclei at the neutron drip line. Pair correlations play a crucial role in such nuclei and characteristic features include an extended neutron halo density and a large dipole strength near threshold. The most detailed studies have been performed for {sup 11}Li. I will present a 3-body model that explains the main features of the data obtained for this nucleus.

  10. Study of weakening of shell N = 28 for neutron rich nuclei through particle number fluctuation and pairing energy

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Rupayan

    2017-03-01

    Evolution of shells has been studied through fluctuations of particle numbers, pairing energies of large number of isotopes and isotones of nuclei evaluated through Skyrme-Hartree-Fock theory after inclusion of optimized tensor interaction. For neutron rich isotopes of Mg, Si, S and Ar no indication of shell closure at N = 28 has been observed. Calculations show occurrence of a doubly shell closed nucleus 114 Fl 184 .

  11. 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.

  12. Coupled cluster calculations of neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Hagen, Gaute

    2016-09-01

    In this talk I will present recent highlights from ab initio computations of atomic nuclei using coupled-cluster methods with state-of-the-art interactions from chiral effective field theory (EFT). The recent progress in computing nuclei from scratch is based on new optimizations of interactions from chiral EFT, and ab initio methods with a polynomial computational cost together with available super computing resources. The physics advancements I will discuss include: (i) accurate nuclear binding energies and radii of light and medium-mass nuclei, (ii) the neutron distribution and electric dipole polarizability of the nucleus 48Ca, (iii) and the structure of the rare nucleus 78Ni from first principles. All these quantities are currently targeted by precision measurements worldwide.

  13. 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.

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

    SciTech Connect

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

    1998-12-21

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

  15. Shape Evolution in Neutron-Rich Ru Nuclei

    NASA Astrophysics Data System (ADS)

    Söderström, P.-A.; Lorusso, G.; Watanabe, H.; Nishimura, S.; Doornenbal, P.; Browne, F.; Bruce, A. M.; Daido, R.; Fang, Y.; Gey, G.; Jung, H. S.; Nishizuka, I.; Patel, Z.; Rice, S.; Sinclair, L.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Wu, J.; Xu, Z. Y.; Baba, H.; Benzoni, G.; Carroll, R. J.; Chae, K. Y.; Crespi, F. C. L.; Fukuda, N.; Gernhäuser, R.; Ideguchi, E.; Inabe, N.; Isobe, T.; Jungclaus, A.; Kameda, D.; Kim, G. D.; Kim, Y.-K.; Kojouharov, I.; Kondev, F. G.; Kubo, T.; Kurz, N.; Kwon, Y. K.; Lalkovski, S.; Lane, G. J.; Li, Z.; Lozeva, R.; Montaner-Piza, A.; Moschner, K.; Naqvi, F.; Niikura, M.; Nishibata, H.; Odahara, A.; Orlandi, R.; Podolyak, Zs.; Regan, P. H.; Roberts, O. J.; Sakurai, H.; Schaffner, H.; Simpson, G. S.; Steiger, K.; Suzuki, H.; Takeda, H.; Tanaka, M.; Wendt, A.; Werner, V.; Wieland, O.; Yagi, A.; Yoshinaga, K.

    Recent experimental work has been carried out at the RIBF using the EURICA HPGe detector array. In this contribution, we discuss the recently published results on the shape evolution of the even-even isotopes 116,118Ru and present an outlook of β-delayed γ-ray spectroscopy of the odd-neutron nuclei and possibilities for life-time measurements of excited states.

  16. Nuclear structure investigation of some neutron-rich halo nuclei

    NASA Astrophysics Data System (ADS)

    Abdullah, Ahmed N.

    The ground state proton, neutron and matter densities, the corresponding rms radii and charge form factors of a dripline nuclei 6He, 11Li, 12Be and 14Be have been studied via a three-body model of (Core + n + n). The core-neutron interaction takes the form of Woods-Saxon (WS) potential. The two valence neutrons of 6He, 11Li and 12Be interact by the realistic interaction of ZBMII while those of 14Be interact via the realistic interaction of VPNP. The core and valence (halo) density distributions are described by the single-particle wave functions of the WS potential. The calculated results are discussed and compared with the experimental data. The long tail performance is clearly noticed in the calculated neutron and matter density distributions of these nuclei. The structure of the two valence neutrons in 6He, 11Li and 12Be is found to be mixed configurations with dominant (1p1/2)2 while that for 14Be is mixed configurations with dominant (2s1/2)2. The analysis of the present study supports the halo structure of these nuclei.

  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. Structure of Light Neutron-rich Nuclei Studied with Transfer Reactions

    SciTech Connect

    Wuosmaa, A. H.

    2015-01-01

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

  19. Production of neutron-rich transcalifornium nuclei in 238U-induced transfer reactions

    NASA Astrophysics Data System (ADS)

    Zhu, Long; Su, Jun; Xie, Wen-Jie; Zhang, Feng-Shou

    2016-11-01

    In order to produce more unknown neutron-rich transcalifornium nuclei, the collisions of 238U with the targets 248Cm, 249Cf, and 250Cm are investigated within the framework of the dinuclear system model. The production cross sections of unknown neutron-rich nuclei with Z =99 -104 in these reactions are predicted. The influences of N /Z ratios and charge numbers of the targets on the production cross sections are studied. It is found that high N /Z ratios of 248Cm and 250Cm targets enhance the production cross sections of neutron-rich transcalifornium nuclei. However, due to high charge number of the target 249Cf the predicted production cross sections of unknown neutron-rich nuclei with Z =104 in the reaction 238U+249Cf are higher than those in 238U+248Cm . We also have studied the entrance angular momentum effects on production probabilities of transfer products in the reaction 238U+248Cm . It is found that the formation probabilities of the final neutron-rich products increase first and then decrease with the increasing J .

  20. Predicted yields of new neutron-rich isotopes of nuclei with Z=64-80 in the multinucleon transfer reaction {sup 48}Ca+{sup 238}U

    SciTech Connect

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

    2010-05-15

    The production cross sections of new neutron-rich isotopes of nuclei with charge numbers Z=64-80 are estimated for future experiments in the multinucleon transfer reaction {sup 48}Ca+{sup 238}U at bombarding energy E{sub c.m.}=189 MeV close to the Coulomb barrier.

  1. Upbend and M1 scissors mode in neutron-rich nuclei - consequences for r-process $$(n,\\gamma )$$ reaction rates

    DOE PAGES

    Larsen, A. C.; Goriely, S.; Bernstein, L. A.; ...

    2015-01-01

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

  2. Upbend and M1 scissors mode in neutron-rich nuclei - consequences for r-process $(n,\\gamma )$ reaction rates

    SciTech Connect

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

    2015-01-01

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

  3. Production and identification of new, neutron-rich nuclei in the [sup 208]Pb region

    SciTech Connect

    Rykaczewski, K. ); Szerypo, J.; Evensen, A.-H.; Kugler, E.; Lettry, J.; Ravn, H. ); Kurpeta, J.; Pkochocki, A.; Karny, M.; Szerypo, J. ); Szerypo, J. ); Andreyev, H.; Huyse, M.; Wo uml; hr, A. ); Aystuml, J.; Nieminen, A.; Huhta, M. ); Walter, G. ) Hoff, P. )

    1998-12-01

    The recently developed methods allowing the experimental studies on new neutron-rich nuclei beyond doubly-magic [sup 208]Pb are briefly described. An identification of new neutron-rich isotopes [sup 215]Pb and [sup 217]Bi, and new decay properties of [sup 216]Bi studied by means of a pulsed release element selective technique at PS Booster-ISOLDE are reported. [copyright] [ital 1998 American Institute of Physics.

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

    SciTech Connect

    Rykaczewski, K.; Szerypo, J.; Evensen, A.-H.; Kugler, E.; Lettry, J.; Ravn, H.; Kurpeta, J.; Pkochocki, A.; Karny, M.; Szerypo, J.; Szerypo, J.; Andreyev, H.; Huyse, M.; Wo¨ hr, A.; Aystuml, J.; Nieminen, A.; Huhta, M.; Walter, G. Hoff, P.

    1998-12-01

    The recently developed methods allowing the experimental studies on new neutron-rich nuclei beyond doubly-magic {sup 208}Pb are briefly described. An identification of new neutron-rich isotopes {sup 215}Pb and {sup 217}Bi, and new decay properties of {sup 216}Bi studied by means of a pulsed release element selective technique at PS Booster-ISOLDE are reported. {copyright} {ital 1998 American Institute of Physics.}

  5. Production of neutron-rich nuclei with Z =60 -73 in reactions induced by Xe isotopes

    NASA Astrophysics Data System (ADS)

    Zhu, Long; Zhang, Feng-Shou; Wen, Pei-Wei; Su, Jun; Xie, Wen-Jie

    2017-08-01

    The multinucleon transfer reactions 124,136,144Xe +238U , Xe,144136+160Gd , Xe,144136+170Er , and Xe,144136+186W are investigated within the framework of the dinuclear system model. The charge equilibration effects on the production cross sections of exotic nuclei are studied. The neutron-deficient projectile 124Xe is favorable to produce transtarget neutron-deficient nuclei, while Xe,144136 shows great advantages of cross sections for producing neutron-rich nuclei in the proton pick-up channel. Furthermore, the influence of entrance angular momentum on the charge equilibration process is investigated. It is found that in a low angular momentum channel the more profound reconstruction of initial nuclei is noticed rather than peripheral collisions. We predict the production cross sections of several neutron-rich nuclei in the reactions Xe,144136+160Gd , Xe,144136+170Er , and Xe,144136+186W . It is found that many unknown nuclei can be produced at the level of μ b to mb.

  6. TOF-Bρ Mass Measurement of Neutron Rich Nuclei at the NSCL

    NASA Astrophysics Data System (ADS)

    Estradé, Alfredo; Matoš, Milan; Amthor, Matthew A.; Bazin, Daniel; Becerril, Ana D.; Elliot, Thom J.; Gade, Alexandra; Galaviz, Daniel; Lorusso, Giuseppe; Pereira, Jorge; Portillo, Mauricio; Rogers, Andrew; Schatz, Hendrik; Shapira, Dan; Smith, Edward; Stolz, Andreas; Wallace, Mark S.

    2007-10-01

    Experimental knowledge of nuclear masses of exotic nuclei is important for understanding nuclear structure far from the valley of β-stability, and as a direct input into astrophysical models. In the case of astrophysical processes involving neutron rich nuclei, such as nucleosynthesis during the r-process and the evolution of matter in the crust of an accreting neutron star, we are mostly limited to using theoretical mass models. The time of flight (TOF) mass measurement technique allows measuring very short-lived nuclei. It has been effectively applied using the fast fragment beams produced at the A1900 fragment separator at the National Superconducting Cyclotron Lab (NSCL) to reach masses very far from stability. We describe a recent mass measurement experiment in the neutron rich Fe region performed at the NSCL, and present preliminary results.

  7. 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.

  8. Studies of neutron-rich nuclei using the CPT mass spectrometer at CARIBU

    NASA Astrophysics Data System (ADS)

    Chaudhuri, A.; Bertone, P. F.; Buchinger, F.; Caldwell, S.; Clark, J. A.; Crawford, J. E.; Deibel, C. M.; Gulick, S.; Lascar, D.; Levand, A. F.; Li, G.; Savard, G.; Segel, R. E.; Sharma, K. S.; Sternberg, M. G.; Sun, T.; Van Schelt, J.

    2011-09-01

    The nucleosynthetic path of the astrophysical r-process and the resulting elemental abundances depend on neutron-separation energies which can be determined from the masses of the nuclei along the r-process reaction path. Due to the current lack of experimental data, mass models are often used. The mass values provided by the mass models are often too imprecise or disagree with each other. Therefore, direct high-precision mass measurements of neutron-rich nuclei are necessary to provide input parameters to the calculations and help refine the mass models. The Californium Rare Isotope Breeder Upgrade (CARIBU) facility of Argonne National Laboratory will provide experiments with beams of short-lived neutron-rich nuclei. The Canadian Penning Trap (CPT) mass spectrometer has been relocated to the CARIBU low-energy beam line to extend measurements of the neutron-rich nuclei into the mostly unexplored region along the r-process path. This will allow precise mass measurements (~ 10 keV/c2) of more than a hundred very neutron-rich isotopes that have not previously been measured.

  9. Bands and Isomers in Neutron-Rich Rare-Earth Nuclei in PHF Model

    NASA Astrophysics Data System (ADS)

    Praharaj, C. R.; Ghorui, S. K.; Naik, Z.; Sahu, B. B.

    Rotational structures of neutron-rich Gd and Dy nuclei in the REE peak region are studied with deformed Hartee-Fock (HF) and angular momentum (J) projection model. Spectra of ground band and a few more excited, positive and negative parity bands have been studied up to high spin values. Some 4-quasiparticle K-isomeric bands and their electromagnetic properties are predicted.

  10. 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.

  11. Evolution of collectivity in neutron-rich nuclei in the Sn132 region

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

    Motivated by the observed regularity in the energy spectra and the structure of the shell model wave functions for the levels of Te137 and I137, a few weakly and moderately deformed neutron-rich odd-A nuclei above the doubly magic nucleus Sn132 were studied using the particle rotor model (PRM). The calculated energy spectra and branching ratios agree reasonably well with the most recent experimental data. In a few cases ambiguity in level ordering was resolved and spin-parities were assigned to the levels. Observed octupole correlation in some of these nuclei is discussed in the light of the present results.

  12. Collective Band Structures in the Neutron-Rich 107,109Ru Nuclei

    NASA Astrophysics Data System (ADS)

    Zhu, Sheng-jiang; Gan, Cui-yun; J, Hamilton H.; A, Ramayya V.; B, Babu R. S.; M, Sakhaee; W, Ma C.; Long, Gui-lu; Deng, Jing-kang; Zhu, Ling-yan; Li, Ming; Yang, Li-ming; J, Komicki; J, Cole D.; R, Aryaeinejad; Y, Dardenne K.; M, Drigert W.; J, Rasmussen O.; M, Stoyer A.; S, Chu Y.; K, Gregorich E.; M, Mohar F.; S, Prussin G.; I, Lee Y.; N, Johnson R.; F, McGowan K.

    1998-11-01

    The levels in neutron-rich odd-A 107,109Ru nuclei have been investigated by using γ-γ- and γ-γ-γ-coincidence studies of the prompt γ-rays from the spontaneous fission of 252Cf. The ground state bands and the negative parity bands are identified and expanded in both nuclei. Triaxial rotor plus particle model calculations indicate the ground state bands originate from ν(d5/2 + g7/2) quasiparticle configurations and the negative parity bands are from νh11/2 orbital.

  13. Studies of neutron-rich nuclei far from stability at TRISTAN

    SciTech Connect

    Gill, R.L.

    1984-01-01

    The ISOL facility, TRISTAN, is a user facility located at Brookhaven National Laboratory's High Flux Beam Reactor. Short-lived, neutron-rich nuclei, far from stability, are produced by thermal neutron fission of /sup 235/U. An extensive array of experimental end stations are available for nuclear structure studies. These studies are augmented by a variety of long-lived ion sources suitable for use at a reactor facility. Some recent results at TRISTAN are presented as examples of using an ISOL facility to study series of nuclei, whereby an effective means of conducting nuclear structure investigations is available.

  14. The decay of proton-rich nuclei in the mass A=36 56 region

    NASA Astrophysics Data System (ADS)

    Dossat, C.; Adimi, N.; Aksouh, F.; Becker, F.; Bey, A.; Blank, B.; Borcea, C.; Borcea, R.; Boston, A.; Caamano, M.; Canchel, G.; Chartier, M.; Cortina, D.; Czajkowski, S.; de France, G.; de Oliveira Santos, F.; Fleury, A.; Georgiev, G.; Giovinazzo, J.; Grévy, S.; Grzywacz, R.; Hellström, M.; Honma, M.; Janas, Z.; Karamanis, D.; Kurcewicz, J.; Lewitowicz, M.; López Jiménez, M. J.; Mazzocchi, C.; Matea, I.; Maslov, V.; Mayet, P.; Moore, C.; Pfützner, M.; Pravikoff, M. S.; Stanoiu, M.; Stefan, I.; Thomas, J. C.

    2007-08-01

    In a series of experiments at the SISSI/LISE3 facility of GANIL conducted between 1999 and 2004, we have collected decay information for proton-rich nuclei between 36Ca and 56Zn. The data allowed us to study the decay properties of 26 nuclei. The main experimental information obtained for all nuclei is their β-decay half-life and their total β-delayed proton emission branching ratio. For many nuclei, individual proton groups and γ rays were identified and allowed us to establish first partial decay schemes for some of the nuclei studied. In addition, mass-excess values have been determined for some of the nuclei by means of the isobaric multiplet mass equation. For 50Ni, the decay via β-delayed two-proton emission could be tentatively identified. The decay of 49Ni allowed for the first time to identify the first 2 state in 48Fe. The experimental data are confronted to model predictions for the half-life and the mass-excess values.

  15. The decay of proton-rich nuclei in the mass A = 36 56 region

    SciTech Connect

    Dossat, C.; Aksouh, F.; Becker, F.; Bey, A.; Borcea, C.; Borcea, R.; Boston, A.; Caamano, M.; Canchel, G.; Czajkowski, S.; de Oliveira Santos, F.; Fleury, A.; Giovinazzo, J.; Grzywacz, Robert Kazimierz; Hellstrom, M.; Honma, M.; Janas, Z.; Karamanis, D.; Lewitowicz, M.; Lopez Jimenez, M. J.; Matea, I.; Maslov, V.; Mayet, P.; Moore, C.; Pfutzner, M.; Pravikoff, M. S.; Stefan, I.; Thomas, J.-C.

    2007-01-01

    In a series of experiments at the SISSI/LISE3 facility of GANIL conducted between 1999 and 2004, we have collected decay information for proton-rich nuclei between {sup 36}Ca and {sup 56}Zn. The data allowed us to study the decay properties of 26 nuclei. The main experimental information obtained for all nuclei is their {beta}-decay half-life and their total {beta}-delayed proton emission branching ratio. For many nuclei, individual proton groups and {gamma} rays were identified and allowed us to establish first partial decay schemes for some of the nuclei studied. In addition, mass-excess values have been determined for some of the nuclei by means of the isobaric multiplet mass equation. For {sup 50}Ni, the decay via {beta}-delayed two-proton emission could be tentatively identified. The decay of {sup 49}Ni allowed for the first time to identify the first 2{sup +} state in {sup 48}Fe. The experimental data are confronted to model predictions for the half-life and the mass-excess values.

  16. Theoretical study of triaxial shapes of neutron-rich Mo and Ru nuclei

    SciTech Connect

    Zhang, C. L.; Bhat, G. H.; Nazarewicz, W.; Sheikh, J. A.; Shi, Yue

    2015-09-10

    Here, whether atomic nuclei can possess triaxial shapes at their ground states is still a subject of ongoing debate. According to theory, good prospects for low-spin triaxiality are in the neutron-rich Mo-Ru region. Recently, transition quadrupole moments in rotational bands of even-mass neutron-rich isotopes of molybdenum and ruthenium nuclei have been measured. The new data have provided a challenge for theoretical descriptions invoking stable triaxial deformations. The purpose of this study is to understand experimental data on rotational bands in the neutron-rich Mo-Ru region, we carried out theoretical analysis of moments of inertia, shapes, and transition quadrupole moments of neutron-rich even-even nuclei around 110Ru using self-consistent mean-field and shell model techniques. Methods: To describe yrast structures in Mo and Ru isotopes, we use nuclear density functional theory (DFT) with the optimized energy density functional UNEDF0. We also apply triaxial projected shell model (TPSM) to describe yrast and positive-parity, near-yrast band structures. As a result, our self-consistent DFT calculations predict triaxial ground-state deformations in 106,108Mo and 108,110,112Ru and reproduce the observed low-frequency behavior of moments of inertia. As the rotational frequency increases, a negative-gamma structure, associated with the aligned ν(h11/2)2 pair, becomes energetically favored. The computed transition quadrupole moments vary with angular momentum, which reflects deformation changes with rotation; those variations are consistent with experiment. The TPSM calculations explain the observed band structures assuming stable triaxial shapes. Lastly, the structure of neutron-rich even-even nuclei around Ru-110 is consistent with triaxial shape deformations. Our DFT and TPSM frameworks provide a consistent and complementary description of experimental data.

  17. 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

  18. Spectroscopy of Moderately Neutron-rich Nuclei with the CLARA-PRISMA Setup

    SciTech Connect

    Gadea, A.; Marginean, N.; De Angelis, G.; Napoli, D. R.; Corradi, L.; Stefanini, A. M.; Fioretto, E.; Axiotis, M.; Behera, B. R.; Latina, A.; Rusu, C.; Zhimin, W.; Valiente-Dobon, J.; Pokrovskiy, I.; Della Vedova, F.; Farnea, E.; Lenzi, S. M.; Bazzacco, D.; Beghini, S.; Ur, C.

    2006-04-26

    Deep-inelastic and multi-nucleon transfer reactions can be used to populate nuclei with relatively large neutron excess. Recently, at the Laboratori Nazionali di Legnaro, a setup consisting on an efficient {gamma}-ray detection system CLARA coupled to the large acceptance magnetic spectrometer PRISMA, capable of tracking the trajectories of the reaction products, has been assembled. During the first year of activity, the experiments performed with the CLARA-PRISMA setup, have been focused mainly on the nuclear structure of neutron-rich nuclei. In particular, nuclei around N=20, N=50 and lying in the A{approx}60 transitional region with N<40, have been investigated. In this contribution, results of these experiments will be reported.

  19. Cluster-transfer reactions with radioactive beams: A spectroscopic tool for neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Bottoni, S.; Leoni, S.; Fornal, B.; Raabe, R.; Rusek, K.; Benzoni, G.; Bracco, A.; Crespi, F. C. L.; Morales, A. I.; Bednarczyk, P.; Cieplicka-Oryńczak, N.; Królas, W.; Maj, A.; Szpak, B.; Callens, M.; Bouma, J.; Elseviers, J.; De Witte, H.; Flavigny, F.; Orlandi, R.; Reiter, P.; Seidlitz, M.; Warr, N.; Siebeck, B.; Hellgartner, S.; Mücher, D.; Pakarinen, J.; Vermeulen, M.; Bauer, C.; Georgiev, G.; Janssens, R. V. F.; Balabanski, D.; Sferrazza, M.; Kowalska, M.; Rapisarda, E.; Voulot, D.; Lozano Benito, M.; Wenander, F.

    2015-08-01

    An exploratory experiment performed at REX-ISOLDE to investigate cluster-transfer reactions with radioactive beams in inverse kinematics is presented. The aim of the experiment was to test the potential of cluster-transfer reactions at the Coulomb barrier as a mechanism to explore the structure of exotic neutron-rich nuclei. The reactions 7Li(98Rb,α xn ) and 7Li(98Rb,t xn ) were studied through particle-γ coincidence measurements, and the results are presented in terms of the observed excitation energies and spins. Moreover, the reaction mechanism is qualitatively discussed as a transfer of a clusterlike particle within a distorted-wave Born approximation framework. The results indicate that cluster-transfer reactions can be described well as a direct process and that they can be an efficient method to investigate the structure of neutron-rich nuclei at medium-high excitation energies and spins.

  20. Cluster-transfer reactions with radioactive beams: A spectroscopic tool for neutron-rich nuclei

    DOE PAGES

    Bottoni, S.; Leoni, S.; Fornal, B.; ...

    2015-08-27

    An exploratory experiment performed at REX-ISOLDE to investigate cluster-transfer reactions with radioactive beams in inverse kinematics is presented. The aim of the experiment was to test the potential of cluster-transfer reactions at the Coulomb barrier as a mechanism to explore the structure of exotic neutron-rich nuclei. The reactions 7Li(98Rb,αxn) and 7Li(98Rb,txn) were studied through particle-γ coincidence measurements, and the results are presented in terms of the observed excitation energies and spins. Moreover, the reaction mechanism is qualitatively discussed as a transfer of a clusterlike particle within a distorted-wave Born approximation framework. The results indicate that cluster-transfer reactions can be describedmore » well as a direct process and that they can be an efficient method to investigate the structure of neutron-rich nuclei at medium-high excitation energies and spins.« less

  1. Total absorption spectroscopy of neutron-rich nuclei around the A = 100 mass region

    NASA Astrophysics Data System (ADS)

    Dombos, Alexander; Algora, Alejandro; Baumann, Thomas; Brett, Jaclyn; Crider, Benjamin; Ginter, Tom; Hager, Ulrike; Kwan, Elaine; Liddick, Sean; Marks, Braden; Naqvi, Farheen; Ong, Wei Jia; Pereira, Jorge; Prokop, Christopher; Quinn, Stephen; Simon, Anna; Scriven, Dustin; Spyrou, Artemis; Sumithrarachchi, Chandana; Deyoung, Paul

    2015-10-01

    Accurate modeling of the r-process requires knowledge of properties related to the β-decay of neutron-rich nuclei, such as β-decay half-lives and β-delayed neutron emission probabilities. These properties are related to the β-decay strength distribution, which can provide a sensitive constraint on theoretical models. Total absorption spectroscopy is a powerful technique to accurately measure quantities needed to calculate the β-decay strength distribution. In an effort to improve models of the r-process, the total absorption spectra of neutron-rich nuclei in the mass region around A = 100 were recently measured using the Summing NaI(Tl) (SuN) detector at the NSCL in the first ever total absorption spectroscopy measurement performed in a fragmentation facility. Total absorption spectra will be presented and the extracted β-decay feeding intensities will be compared to theoretical calculations.

  2. Theoretical study of triaxial shapes of neutron-rich Mo and Ru nuclei

    DOE PAGES

    Zhang, C. L.; Bhat, G. H.; Nazarewicz, W.; ...

    2015-09-10

    Here, whether atomic nuclei can possess triaxial shapes at their ground states is still a subject of ongoing debate. According to theory, good prospects for low-spin triaxiality are in the neutron-rich Mo-Ru region. Recently, transition quadrupole moments in rotational bands of even-mass neutron-rich isotopes of molybdenum and ruthenium nuclei have been measured. The new data have provided a challenge for theoretical descriptions invoking stable triaxial deformations. The purpose of this study is to understand experimental data on rotational bands in the neutron-rich Mo-Ru region, we carried out theoretical analysis of moments of inertia, shapes, and transition quadrupole moments of neutron-richmore » even-even nuclei around 110Ru using self-consistent mean-field and shell model techniques. Methods: To describe yrast structures in Mo and Ru isotopes, we use nuclear density functional theory (DFT) with the optimized energy density functional UNEDF0. We also apply triaxial projected shell model (TPSM) to describe yrast and positive-parity, near-yrast band structures. As a result, our self-consistent DFT calculations predict triaxial ground-state deformations in 106,108Mo and 108,110,112Ru and reproduce the observed low-frequency behavior of moments of inertia. As the rotational frequency increases, a negative-gamma structure, associated with the aligned ν(h11/2)2 pair, becomes energetically favored. The computed transition quadrupole moments vary with angular momentum, which reflects deformation changes with rotation; those variations are consistent with experiment. The TPSM calculations explain the observed band structures assuming stable triaxial shapes. Lastly, the structure of neutron-rich even-even nuclei around Ru-110 is consistent with triaxial shape deformations. Our DFT and TPSM frameworks provide a consistent and complementary description of experimental data.« less

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  4. Study of Collectivity in n-rich A=80 Nuclei using Radioactive Ion Beams

    NASA Astrophysics Data System (ADS)

    Padilla, E.; Galindo-Uribarri, A.; Baktash, C.; Fuentes, B.; Gross, C.; Mueller, P.; Radford, D. C.; Stracener, D.; Yu, C.-H.; Bijker, R.; Castanos, O.; Batchelder, J.; Hartley, D. J.

    2002-04-01

    We report on recent experiments performed at the HRIBF of Oak Ridge National Laboratory (ORNL) aimed to study neutron-rich nuclei in the A 80 mass region. First time use of Radioactive Ion Beams (RIBs) (78,80)Ge complemented with stable beam information allowed a systematic study of B(E2)-values that characterize the n-rich even-even Ge and Se isotopes. A comparison of the experimental results with IBA2 calculations will be presented. *Supported by US-DOE under the contract DE-AC05-00AOR22725.

  5. Production of proton-rich nuclei around Z = 84-90 in fusion-evaporation reactions

    NASA Astrophysics Data System (ADS)

    Chen, Peng-Hui; Feng, Zhao-Qing; Niu, Fei; Guo, Ya-Fei; Zhang, Hong-Fei; Li, Jun-Qing; Jin, Gen-Ming

    2017-05-01

    Within the framework of the dinuclear system model, production cross sections of proton-rich nuclei with charged numbers of Z = 84-90 are investigated systematically. Possible combinations with the 28Si, 32S, 40Ar bombarding the target nuclides 165Ho, 169Tm, 170-174Yb, 175,176Lu, 174, 176-180Hf and 181Ta are analyzed thoroughly. The optimal excitation energies and evaporation channels are proposed to produce the proton-rich nuclei. The systems are feasible to be constructed in experiments. It is found that the neutron shell closure of N = 126 is of importance during the evaporation of neutrons. The experimental excitation functions in the 40Ar induced reactions can be nicely reproduced. The charged particle evaporation is comparable with neutrons in cooling the excited proton-rich nuclei, in particular for the channels with α and proton evaporation. The production cross section increases with the mass asymmetry of colliding systems because of the decrease of the inner fusion barrier. The channels with pure neutron evaporation depend on the isotopic targets. But it is different for the channels with charged particles and more sensitive to the odd-even effect.

  6. Coupled cluster calculation for ground state properties of closed-shell nuclei and single hole states.

    NASA Astrophysics Data System (ADS)

    Mihaila, Bogdan; Heisenberg, Jochen

    2000-04-01

    We continue the investigations of ground state properties of closed-shell nuclei using the Argonne v18 realistic NN potential, together with the Urbana IX three-nucleon interaction. The ground state wave function is used to calculate the charge form factor and charge density. Starting with the ground state wave function of the closed-shell nucleus, we use the equation of motion technique to calculate the ground state and excited states of a neighboring nucleus. We then generate the corresponding magnetic form factor. We correct for distortions due to the interaction between the electron probe and the nuclear Coulomb field using the DWBA picture. We compare our results with the available experimental data. Even though our presentation will focus mainly on the ^16O and ^15N nuclei, results for other nuclei in the p and s-d shell will also be presented.

  7. 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.

  8. Dipole response in neutron-rich nuclei with new Skyrme interactions

    NASA Astrophysics Data System (ADS)

    Zheng, H.; Burrello, S.; Colonna, M.; Baran, V.

    2016-07-01

    We investigate the isoscalar and isovector E 1 response of neutron-rich nuclei, within a semiclassical transport model employing effective interactions for the nuclear mean field. In particular, we adopt the recently introduced SAMi-J Skyrme interactions, whose parameters are specifically tuned to improve the description of spin-isospin properties of nuclei. Our analysis evidences a relevant degree of isoscalar-isovector mixing of the collective excitations developing in neutron-rich systems. Focusing on the low-lying strength emerging in the isovector response, we show that this energy region essentially corresponds to the excitation of isoscalar-like modes, which also contribute to the isovector response owing to their mixed character. Considering effective interactions which mostly differ in the isovector channels, we observe that these mixing effects increase with the slope L of the symmetry energy at saturation density, leading to a larger strength in the low-energy region of the isovector response. This result appears connected to the increase, with L , of the neutron-proton asymmetry at the surface of the considered nuclei, i.e., to the neutron skin thickness.

  9. One- and two neutron decay of light neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Thoennessen, Michael

    2014-09-01

    Direct reactions with radioactive beams have been used very successfully to populate and measure nuclei beyond the neutron dripline and neutron unbound excited states of nuclei close to the neutron dripline. The use of different reactions (for example neutron removal and proton removal) to populate the same final nucleus can be used to selectively populate different states. Recent results from the MoNA-LISA setup at the NSCL, including 10He, 10,11Li, and 12,13Be will be presented. Direct reactions with radioactive beams have been used very successfully to populate and measure nuclei beyond the neutron dripline and neutron unbound excited states of nuclei close to the neutron dripline. The use of different reactions (for example neutron removal and proton removal) to populate the same final nucleus can be used to selectively populate different states. Recent results from the MoNA-LISA setup at the NSCL, including 10He, 10,11Li, and 12,13Be will be presented. This work was supported in part by the NSF, Grant PHY-11-02511.

  10. Stellar electron capture rates on neutron-rich nuclei and their impact on stellar core collapse

    NASA Astrophysics Data System (ADS)

    Raduta, Ad. R.; Gulminelli, F.; Oertel, M.

    2017-02-01

    During the late stages of gravitational core-collapse of massive stars, extreme isospin asymmetries are reached within the core. Due to the lack of microscopic calculations of electron-capture (EC) rates for all relevant nuclei, in general simple analytic parametrizations are employed. We study here several extensions of these parametrizations, allowing for a temperature, electron density, and isospin dependence as well as for odd-even effects. The latter extra degrees of freedom considerably improve the agreement with large-scale microscopic rate calculations. We find, in particular, that the isospin dependence leads to a significant reduction of the global EC rates during core collapse with respect to fiducial results, where rates optimized on calculations of stable f p -shell nuclei are used. Our results indicate that systematic microscopic calculations and experimental measurements in the N ≈50 neutron-rich region are desirable for realistic simulations of the core collapse.

  11. Production of very neutron-rich nuclei with a {sup 76}Ge beam

    SciTech Connect

    Tarasov, O. B.; Portillo, M.; Baumann, T.; Bazin, D.; Ginter, T. N.; Hausmann, M.; Pereira, J.; Stolz, A.; Amthor, A. M.; Gade, A.; Nettleton, A.; Sherrill, B. M.; Thoennessen, M.; Inabe, N.; Kubo, T.; Morrissey, D. J.

    2009-09-15

    Production cross sections for neutron-rich nuclei from the fragmentation of a {sup 76}Ge beam at 132 MeV/u were measured. The longitudinal momentum distributions of 34 neutron-rich isotopes of elements 13{<=}Z{<=}27 were scanned using a novel experimental approach of varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei, including 15 isotopes first observed in this work. These are the most neutron-rich nuclides of the elements 17{<=}Z{<=}25 ({sup 50}Cl, {sup 53}Ar, {sup 55,56}K, {sup 57,58}Ca, {sup 59,60,61}Sc, {sup 62,63}Ti, {sup 65,66}V, {sup 68}Cr, and {sup 70}Mn). A one-body Q{sub g} systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. Some of the fragments near {sup 58}Ca show anomalously large production cross sections.

  12. {beta}{sup -}-delayed spectroscopy of neutron-rich tantalum nuclei: Shape evolution in neutron-rich tungsten isotopes

    SciTech Connect

    Alkhomashi, N.; Regan, P. H.; Podolyak, Zs.; Pietri, S.; Garnsworthy, A. B.; Steer, S. J.; Farrelly, G.; Cullen, I. J.; Gelletly, W.; Walker, P. M.; Benlliure, J.; Caserejos, E.; Estevez, M. E.; Morales, A. I.; Casten, R. F.; Gerl, J.; Wollersheim, H. J.; Gorska, M.; Kojouharov, I.; Schaffner, H.

    2009-12-15

    The low-lying structure of {sup 188,190,192}W has been studied following {beta} decays of the neutron-rich mother nuclei {sup 188,190,192}Ta produced following the projectile fragmentation of a 1-GeV-per-nucleon {sup 208}Pb primary beam on a natural beryllium target at the GSI Fragment Separator. The {beta}-decay half-lives of {sup 188}Ta, {sup 190}Ta, and {sup 192}Ta have been measured, with {gamma}-ray decays of low-lying states in their respective W daughter nuclei, using heavy-ion {beta}-{gamma} correlations and a position-sensitive silicon detector setup. The data provide information on the low-lying excited states in {sup 188}W, {sup 190}W, and {sup 192}W, which highlight a change in nuclear shape at {sup 190}W compared with that of lighter W isotopes. This evolution of ground-state structure along the W isotopic chain is discussed as evidence for a possible proton subshell effect for the A{approx}190 region and is consistent with maximization of the {gamma}-softness of the nuclear potential around N{approx}116.

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

    SciTech Connect

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

    2010-04-26

    The structure of neutron-rich nuclei in the vicinity of {sup 78}Ni have been investigated via the beta-decay of {sup 71,73,75}Cu isotopes (ISOLDE, CERN). Experimental results have been compared with shell-model calculations performed with the ANTOINE code using a large (2p{sub 3/2}1 f{sub 5/2}2 p{sub 1/2}1 g{sub 9/2}) valence space and a (56/28)Ni{sub 28} core.

  14. Thermal effects on the Fission Barrier of neutron-rich nuclei

    SciTech Connect

    Minato, Futoshi; Hagino, Kouichi

    2008-11-11

    We discuss the fission barrier height of neutron-rich nuclei in a r-process site at highly excited state, which is resulted from the beta-decay or the neutron-capture processes. We particularly investigate the sensitivity of the fission barrier height to the temperature, including the effect of pairing phase transition from superfluid to normal fluid phases. To this end, we use the finite-temperature Skyrme-Hartree-Fock-Bogolubov method with a zero-range pairing interaction. We also discuss the temperature dependence of the fission decay rate.

  15. Nucleosynthesis of proton-rich nuclei. Experimental results on the rp-process

    NASA Astrophysics Data System (ADS)

    Galaviz, D.; Amthor, A. M.; Bazin, D.; Becerril, A. D.; Brown, B. A.; Chen, A. A.; Cole, A.; Cook, J. M.; Elliot, T.; Estrade, A.; Fülöp, Z. S.; Gade, A.; Glasmacher, T.; Heger, A.; Howard, M. E.; Kessler, R.; Lorusso, G.; Matos, M.; Montes, F.; Müller, W.; Pereira, J.; Schatz, H.; Sherrill, B.; Schertz, F.; Shimbara, Y.; Smith, E.; Smith, K.; Tamii, A.; Stolz, A.; Weisshaar, D.; Wallace, M.; Wiescher, M.; Zegers, R. G. T.

    2010-01-01

    We report in this study the nuclear properties of proton-rich isotopes located along the rp-process path. The experiments have recently been performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The level properties above the proton separation energy of the nuclei 30S, 36K and 37Ca were measured with precision of < 10 keV. This will allow a reduction in the determination of the astrophysical (p,γ) reaction rate under rp-process conditions.

  16. Lattice HFB calculations for nuclei far from stability: neutron-rich sulfur and tin isotopes

    NASA Astrophysics Data System (ADS)

    Oberacker, Volker; Umar, Sait; Teran, Edgar

    2002-10-01

    We have developed a new Hartree-Fock-Bogoliubov (HFB) code to study ground state and pairing properties of nuclei near the neutron and proton drip lines. The unique feature of our code is that it takes into account the strong coupling to high energy continuum states (up to an equivalent s.p. energy of about 60 MeV). We solve the HFB equations for deformed, axially symmetric even-even nuclei on a two-dimensional lattice using high accuracy Basis-Spline methods (Galerkin and collocation schemes). The effective N-N interaction in the p-h channel is of Skyrme-type (SLy4), and in the p-p and h-h channel it is a (modified) delta interaction. We present results for binding energies, 2-neutron separation energies, Fermi levels, pairing gaps, normal densities and pairing densities, and other observables. In particular, we will discuss neutron-rich sulfur (S-48,S-52) and tin (Sn-150) isotopes. [1] E. Teran, V.E. Oberacker and A.S. Umar, "Axially symmetric Hartree-Fock-Bogoliubov Calculations for Nuclei Near the Drip-Lines; nucl-th/0205042 * Research supported by U.S. DOE grant DE-FG02-96ER40963, and by the National Energy Research Scientific Computing Center (NERSC)

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

    SciTech Connect

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

    2014-07-23

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

  18. Isotopic excesses of proton-rich nuclei related to space weathering observed in a gas-rich meteorite Kapoeta

    SciTech Connect

    Hidaka, Hiroshi; Yoneda, Shigekazu E-mail: s-yoneda@kahaku.go.jp

    2014-05-10

    The idea that solar system materials were irradiated by solar cosmic rays from the early Sun has long been suggested, but is still questionable. In this study, Sr, Ba, Ce, Nd, Sm, and Gd isotopic compositions of sequential acid leachates from the Kapoeta meteorite (howardite) were determined to find systematic and correlated variations in their isotopic abundances of proton-rich nuclei, leading to an understanding of the irradiation condition by cosmic rays. Significantly large excesses of proton-rich isotopes (p-isotopes), {sup 84}Sr, {sup 130}Ba, {sup 132}Ba, {sup 136}Ce, {sup 138}Ce, and {sup 144}Sm, were observed, particularly in the first chemical separate, which possibly leached out of the very shallow layer within a few μm from the surface of regolith grains in the sample. The results reveal the production of p-isotopes through the interaction of solar cosmic rays with the superficial region of the regolith grains before the formation of the Kapoeta meteorite parent body, suggesting strong activity in the early Sun.

  19. Study of neutron-rich nuclei near doubly magic 132Sn

    NASA Astrophysics Data System (ADS)

    Sarkar, M. Saha; Sarkar, S.

    2012-06-01

    Large basis untruncated shell-model (SM) calculations have been done for nuclei with 50 ≤Z ≤56 and 82 ≤ N ≤ 88 in the π(gdsh) ⊗ ν (hf pi) valence space above the 132Sn core using both realistic CWG and empirical SMPN (1+2)-body Hamiltonians. These neutronrich nuclei lie on or close to the path of astrophysical r-process flow. Reasons behind the similarity and dissimilarity between the results using these two interactions have been discussed. The observation and prediction of unusually depressed first excited 2+1 states in even-A semi-magic Sn isotopes having N =84-88 and the possibility of a new magic number at N = 90 above 132Sn provide motivations for reviewing the problems related to the nuclear astrophysics in general.

  20. Coulomb Excitation of n-rich nuclei along the N = 50 shell closure

    NASA Astrophysics Data System (ADS)

    Padilla-Rodal, E.; Galindo-Uribarri, A.; Batchelder, J. C.; Beene, J. R.; Bingham, C.; Brown, B. A.; Lagergren, K. B.; Mueller, P. E.; Radford, D. C.; Stracener, D. W.; Urrego-Blanco, J. P.; Varner, R. L.; Yu, C.-H.

    2008-04-01

    Recently, we have been investigating characteristics of nuclear states around the neutron-rich mass A=80 region [1]. Using the Radioactive Ion Beams (RIBs) produced at HRIBF, we have successfully measured the B(E2) values for ^78,80,82Ge , using Coulomb excitation in inverse kinematics. For the germanium isotopes, these data allow a study of the systematic trend between the subshell N= 40 and the N=50 shell. Using the same technique, we have measured the B(E2) value of various nuclei along the N=50 shell including the radioactive nucleus ^84Se. This value together with our previously measured ^82Ge, and the recent result on ^80Zn from ISOLDE [2] are providing basic experimental information needed for a better understanding of the neutron-rich nuclei around A˜80. We report the new results and compare with shell model calculations. [1] E. Padilla-Rodal et al., Phys. Rev. Lett. 94 (2005) 122501. [2] J. Van de Walle et al., Phys. Rev. Lett. 99 (2007) 142501.

  1. 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.

  2. Direct Mass Measurements of Fluorine Through Chlorine Neutron-Rich Nuclei.

    NASA Astrophysics Data System (ADS)

    Zhou, Xiao-Gang

    1991-02-01

    Mass measurements have been made of the neutron -rich isotopes of fluorine through chlorine at the Los Alamos Meson Physics Facility. The masses of 34 neutron-rich isotopes are reported. Ten of these measurements represent first-time mass determinations of these species. The nuclei of interest are produced in fragmentation reaction. A transport line is used to capture a small fraction of the ions and transport them into the time-of-flight isochronous (TOFI) spectrometer. The TOFI spectrometer is isochronously designed, such that the transit time of the ion passing through the spectrometer is independent of the ion velocity, and only depends on its mass-to-charge ratio. A gas ionization counter located at the exit of the TOFI spectrometer is used to identify the ion atomic number and to measure the total energy. Three fast timing detectors are placed in the middle of the transport line, entrance, and exit of the TOFI spectrometer to determine the ion velocity and the M/Q ratio. We calculate each ion's charge state by using velocity, total energy, and M/Q ratio. With A, Z, Q assigned to each ion, we fit M/Q linearly to the known masses to obtain a high precision M/Q calibration. The masses of unknown nuclei are calculated through the M/Q calibration. The final results are generated by taking a weighted average for all runs and charge states. These results have confirmed the anomaly of enhanced binding found in neutron-rich Na and Mg isotopes and also suggest that the binding energies for those nuclei are less than that originally reported. The masses of several F through Al isotopes are compared with the shell model calculations. These comparisons demonstrate that the anomaly can be understood in terms of one or two neutron promotions from the sd shell to the fp shell. The results for some neutron-rich isotopes of P through Cl are compared to several mass models and good agreement in all cases is found.

  3. 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.

  4. 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.

  5. Shape Coexistence, Triaxiality, Chiral Bands in Neutron-Rich Nuclei and Hot Fission Mode

    NASA Astrophysics Data System (ADS)

    Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Zhu, S. J.; Luo, Y. X.; Rasmussen, J. O.; Gore, P. M.; Jones, E. F.; Fong, D.; Li, K.; Beyer, C. J.; Chaturvedi, L.; Xu, R. Q.; Yang, L. M.; Jiang, Z.; Zhang, Z.; Xiou, S. D.; Zhang, X. Q.; Ter-Akopian, G. M.; Daniel, A. V.; Oganessian, Yu.; Dimitrov, V.; Frauendorf, S.; Gelberg, A.; Kormicki, J.; Gilat, J.; Lee, I. Y.; Fallon, P.; Cole, J. D.; Drigert, M. W.; Stoyer, M. A.; Ginter, T. N.; Wu, S. C.; Donangelo, R.

    2005-09-01

    The structure of neutron-rich nuclei in the A=100 region have been investigated via prompt γ-γ-γ coincidences in the spontaneous fission of 252Cf at Gammasphere. New levels are observed in 93,95,97Sr, 99,101Y, 101,105Nb, 104,106Mo, 105,107,109Tc, 111,113Rh and 115,117Ag. The level structures show a clear evolution from spherical single particle structures seen in Sr, to symmetric, large prolate deformation in Y, to increasing triaxial shapes with increasing Z in Nb, Mo, Tc, Rh and Ag. Rigid triaxial-plus-rotor calculations were carried out for 107Tc and 111,113Rh. Best fits in 107Tc and 111,113Rb are for prolate β2 ~ 0.3 and γ increasing from -22.5° in 107Tc to near maximum triaxiality, γ = -28° in 111,113Rh. A K= 1/2 intruder band with symmetric deformation is found to coexist with the triaxial asymmetric bands in the Tc and Rh nuclei. In 106Mo, two sets of ΔI=1 bands have all the characteristics of chiral doublets. Tilted axis cranking calculations support the chiral assignment and indicate these form a new type of chiral band with a one and two phonon chiral vibrational nature associated essentially with the neutrons. These new type chiral doublets demonstrate the general nature of chirality in nuclei. Binary yields of Mo-Ba and Ru-Xe were determined with higher accuracy. The hot fission mode is seen only in Mo-Ba where it goes via a type of hyperdeformed shape for 144,145,146Ba with a 4.7% intensity.

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

    NASA Astrophysics Data System (ADS)

    Kimura, M.; Suhara, T.; Kanada-En'yo, Y.

    2016-12-01

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

  7. Nuclear shape transitions in neutron-rich medium-mass nuclei

    SciTech Connect

    Sarriguren, P.; Rodriguez-Guzman, R.; Robledo, L. M.

    2012-10-20

    We study the isotopic evolution of the ground-state nuclear shapes in neutron-rich Kr, Rb, Sr, Y, Zr, Nb, and Mo isotopic chains. Both even-even and odd-A nuclei are included in the analysis. For the latter we also study the systematics of their one-quasiparticle low-lying configurations. The theoretical approach is based on a selfconsistent Hartree-Fock-Bogoliubov formalism with finite range Gogny energy density functionals. Neutron separation energies, charge radii, and the spin-parity of the ground states are calculated and compared with available data. Shape-transition signatures are identified around N= 60 isotones as discontinuities in both charge radii isotopic shifts and spin-parities of the ground states. The nuclear deformation including triaxiality is shown to play a relevant role in the understanding of the bulk and spectroscopic features of the ground and low-lying one-quasiparticle states.

  8. Shell structure in neutron-rich Ca and Ni nuclei under semi-realistic mean fields

    SciTech Connect

    Nakada, H.

    2010-05-15

    Shell structure in the neutron-rich Ca and Ni nuclei is investigated by the spherical Hartree-Fock calculations with semi-realistic NN interactions. Specific ingredients of the effective interaction, particularly the tensor force, often play a key role in the Z dependence of the neutron shell structure. Such examples are found in N=32 and N=40; N=32 becomes magic or submagic in {sup 52}Ca while its magicity is broken in {sup 60}Ni, and N=40 is submagic (though not magic) in {sup 68}Ni but not in {sup 60}Ca. Comments are given on the doubly magic nature of {sup 78}Ni. We point out that the loose binding can lead to a submagic number N=58 in {sup 86}Ni, assisted by the weak pair coupling.

  9. g-Factors of Isomeric States in the Neutron-Rich Nuclei

    SciTech Connect

    Georgiev, G.; Neyens, G.; Hass, M.; Balabanski, Dimiter Loukanov; Bingham, Carrol R; Borcea, C.; Coulier, N.; Coussenment, R.; Daugas, J. M.; De France, Gilles M; Gorska, M.; Grawe, Hubert H; Grzywacz, Robert Kazimierz; Lewitowicz, Marek; Mach, Henryk A; Matea, I.; de Oliveira Santos, F.; Page, R. D.; Pfutzner, Marek; Penionzhkevich, Yu. E.; Podolyak, Zsolt F; Regan, Patrick H; Rykaczewski, Krzysztof Piotr; Sawicka, M.; Smirnova, N. A.; Sobolev, Yu.; Stanoiu, M.; Teughels, S.; Vyvey, K.

    2004-02-01

    We report the results from the first experiment to measure gyromagnetic factors of {micro}s isomers in neutron-rich nuclei produced by intermediate-energy projectile-fragmentation reactions. The Time Dependent Perturbed Angular Distribution (TDPAD) method was applied in combination with the heavy-ion-gamma correlation technique. The nuclides in the vicinity of {sup 68}Ni were produced and spin-oriented following the fragmentation of a {sup 76}Ge, 61.4 MeV/ u beam at GANIL. The results obtained, |g|({sup 69 m}Cu) = 0.225(25) and |g|({sup 67 m}Ni) = 0.125(6) provide another indication of the importance of proton excitation across the Z = 28 shell gap for the description of these states.

  10. 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).

  11. Very Low Energy Protons From the Beta Decay of Proton Rich Nuclei For Nuclear Astrophysics

    SciTech Connect

    Simmons, E.; Trache, L.; Banu, A.; McCleskey, M.; Roeder, B.; Spiridon, A.; Tribble, R. E.; Saastamoinen, A.; Aysto, J.; Davinson, T.; Woods, P. J.; Lotay, G. J.

    2010-03-01

    We have developed a new experimental technique to measure very low energy protons from beta-delayed p-decay of proton-rich nuclei produced and separated with the MARS recoil spectrometer at TAMU. Recently we have investigated the beta-delayed p-decays of {sup 23}Al and {sup 31}Cl and obtained information on the resonances in the reactions {sup 22}Na(p,gamma){sup 23}Mg and {sup 30}P(p,gamma){sup 31}S, respectively. These reactions are important in explosive H-burning in Novae. A simple setup consisting of a telescope made of a thin double sided Si strip detector (p-detector) backed or sandwiched between two thick Si detectors (beta-detectors) was designed. We studied two different p-detectors and found that the thinner detectors with a small cell size are best to measure proton energies as low as 2-300 keV.

  12. Direct mass measurements of proton-rich nuclei in the region from tellurium to polonium

    NASA Astrophysics Data System (ADS)

    Wollnik, H.; Beckert, K.; Beha, T.; Bosch, F.; Eickhoff, H.; Franzke, B.; Fujita, Y.; Geissel, H.; Haussmann, M.; Irnich, H.; Jung, H. C.; Kerscher, Th.; Klepper, O.; Kluge, H.-J.; Kozhuharov, C.; Kraus, G.; Löbner, K. E. G.; Münzenberg, G.; Nickel, F.; Nolden, F.; Novikov, Yu.; Radon, T.; Reich, H.; Scheidenberger, C.; Schlitt, B.; Schwab, W.; Schwinn, A.; Steck, M.; Sümmerer, K.

    1997-02-01

    In recent experiments using the FRS-ESR facilities at GSI we have measured the masses of 225 proton-rich nuclei in the range of 135≤A≤209. Applying the new technique of Schottky-Mass Spectrometry an accuracy of about 100 keV and a resolving power of 4 · 10 5 was achieved. Masses for cooled projectile fragments with half-lives larger than a few seconds were determined by their revolution frequencies in the ESR. Reliable predictions for the proton-drip line can be made for elements from bismuth to protactinium using the precisely measured Qα-values from literature and our new mass values for the isotopes at the ends of the corresponding α-chains.

  13. Excited State Properties in Neutron-rich Nuclei near N = 40

    NASA Astrophysics Data System (ADS)

    Crider, B. P.; Prokop, C. J.; Liddick, S. N.; Chiara, C. J.; Ayangeakaa, A. D.; Carroll, J. J.; Chen, J.; David, H. M.; Go, S.; Grzywacz, R.; Harker, J.; Janssens, R. V. F.; Lauritsen, T.; Seweryniak, D.; Walters, W. B.

    2015-10-01

    The neutron-rich nuclei near N = 40 have recently been the focus of many experimental and theoretical efforts. In this region, the competing energy cost for promoting pairs of nucleons across either Z = 28 or N = 40 and the energy gain from residual nucleon-nucleon interactions gives rise to several low-energy 0+ states and is a hallmark of shape coexistence. Low-energy 0+ states have been observed in 68Ni, and predicted for other nuclei in the region. Recent theoretical calculations are able to reproduce the energies of known states in 68Ni and stress the importance of the tensor component of the monopole interaction. Yet, while energies of the levels are a useful comparison, a more stringent test is the reproduction of level lifetimes, where the predicted half-lives can vary by several orders of magnitude depending on the interaction. To further benchmark theoretical calculations in this region, a setup designed to measure level lifetimes has been constructed. A description of the array and preliminary results will be presented. This work was supported by the DOE NNSA Award No. DE-NA0000979, NSF Contract No. PHY1102511, DOE SC NP Contract No. DE-AC-06CH11357 and Grant No. DE-FG02-94ER40834.

  14. 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.

  15. Ab initio Approach to Effective Single-Particle Energies in Doubly Closed Shell Nuclei

    SciTech Connect

    Duguet, T.

    2012-01-01

    The present work discusses, from an ab initio standpoint, the definition, the meaning, and the usefulness of effective single-particle energies (ESPEs) in doubly closed shell nuclei. We perform coupled-cluster calculations to quantify to what extent selected closed-shell nuclei in the oxygen and calcium isotopic chains can effectively be mapped onto an effective independent-particle picture. To do so, we revisit in detail the notion of ESPEs in the context of strongly correlated many-nucleon systems and illustrate the necessity of extracting ESPEs through the diagonalization of the centroid matrix, as originally argued by Baranger. For the purpose of illustration, we analyze the impact of correlations on observable one-nucleon separation energies and nonobservable ESPEs in selected closed-shell oxygen and calcium isotopes. We then state and illustrate the nonobservability of ESPEs. Similarly to spectroscopic factors, ESPEs can indeed be modified by a redefinition of inaccessible quantities while leaving actual observables unchanged. This leads to the absolute necessity of employing consistent structure and reaction models based on the same nuclear Hamiltonian to extract the shell structure in a meaningful fashion from experimental data.

  16. In-medium similarity renormalization group for closed and open-shell nuclei

    NASA Astrophysics Data System (ADS)

    Hergert, H.

    2017-02-01

    We present a pedagogical introduction to the in-medium similarity renormalization group (IMSRG) framework for ab initio calculations of nuclei. The IMSRG performs continuous unitary transformations of the nuclear many-body Hamiltonian in second-quantized form, which can be implemented with polynomial computational effort. Through suitably chosen generators, it is possible to extract eigenvalues of the Hamiltonian in a given nucleus, or drive the Hamiltonian matrix in configuration space to specific structures, e.g., band- or block-diagonal form. Exploiting this flexibility, we describe two complementary approaches for the description of closed- and open-shell nuclei: the first is the multireference IMSRG (MR-IMSRG), which is designed for the efficient calculation of nuclear ground-state properties. The second is the derivation of non-empirical valence-space interactions that can be used as input for nuclear shell model (i.e., configuration interaction (CI)) calculations. This IMSRG+shell model approach provides immediate access to excitation spectra, transitions, etc, but is limited in applicability by the factorial cost of the CI calculations. We review applications of the MR-IMSRG and IMSRG+shell model approaches to the calculation of ground-state properties for the oxygen, calcium, and nickel isotopic chains or the spectroscopy of nuclei in the lower sd shell, respectively, and present selected new results, e.g., for the ground- and excited state properties of neon isotopes.

  17. 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.

  18. Exotic neutron-rich medium-mass nuclei with realistic nuclear forces

    NASA Astrophysics Data System (ADS)

    Tsunoda, Naofumi; Otsuka, Takaharu; Shimizu, Noritaka; Hjorth-Jensen, Morten; Takayanagi, Kazuo; Suzuki, Toshio

    2017-02-01

    We present the first application of the newly developed extended Kuo-Krenciglowa (EKK) theory of the effective nucleon-nucleon interaction to shell-model studies of exotic nuclei, including those where conventional approaches with fitted interactions encounter difficulties. This EKK theory enables us to derive an interaction that is suitable for several major shells (s d +p f in this work). By using such an effective interaction obtained from the Entem-Machleidt QCD-based χ N3LO interaction and the Fujita-Miyazawa three-body force, the energies, E 2 properties, and spectroscopic factors of low-lying states of neutron-rich Ne, Mg, and Si isotopes are nicely described, as the first shell-model description of the "island of inversion" without fit of the interaction. The long-standing question as to how particle-hole excitations occur across the s d -p f magic gap is clarified with distinct differences from the conventional approaches. The shell evolution is shown to appear similarly to earlier studies.

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

    NASA Astrophysics Data System (ADS)

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

    1999-03-01

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

  20. Nuclear Structure of Radioactive Neutron-Rich Nuclei with 4pi Detector Arrays

    SciTech Connect

    Wu, C Y; Becker, J A; Cline, D

    2005-05-10

    In-beam studies of {gamma}-ray spectroscopy of radioactive neutron-rich nuclei using the 4{pi} TIGRESS array at TRIUMF requires a ''tag'' to improve the selectivity of the detected {gamma} rays in the high {gamma}-ray background produced by radioactive beams and the need for Doppler-shift correction. We propose development of two types of large solid angle auxiliary charged particle detectors to be used in conjunction with TRIGRESS in order to provide the required tag. The initial phase of detector development will focus on research involving light-mass radioactive beams with Z {le} 20. Gas avalanche detectors, such as CHICO, are not the ideal detector for lighter ions. Therefore, a new detector system, called Bambino, is being developed that is based on commercially available CD type position-sensitive silicon detectors. Three CD-S2 detectors, with a thickness of 140 {micro}m, have been ordered from Micron Semiconductor Ltd. A split spherical target chamber will be built in Rochester to accommodate two of those CD detectors in both forward and backward directions. These detectors will be placed 3 cm from the target, providing an angular coverage from 20.1{sup o} to 49.4{sup o} for the forward hemisphere and from 130.6{sup o} to 159.9{sup o} for the backward hemisphere. The detectors will us ten 8-channels preamplifiers, from Swan Research, that will be mechanically mounted on both the entrance and exit beam pipes. The work on both the internal and external cables connecting the detectors to the preamplifiers, vacuum feedthrough etc. is in progress. In addition, a vacuum chamber has been ordered from Kurt J. Lesker Company for testing these detectors. Bambino should be ready by the spring 2006. The second phase will involve the development of a next generation CHICO-like gas avalanche detector for experiments involving heavier radioactive beams. CHICO, a highly segmented parallel-plate avalanche counter, has proven to be very successful when used in conjunction

  1. Momentum distributions and spectroscopic factors of doubly closed shell nuclei in correlated basis function theory

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

    The momentum distributions, natural orbits, spectroscopic factors, and quasihole wave functions of the C12, O16, Ca40, Ca48, and Pb208 doubly closed shell nuclei have been calculated in the framework of the correlated basis function theory, by using the Fermi hypernetted chain resummation techniques. The calculations have been done by using the realistic Argonne v8' nucleon-nucleon potential, together with the Urbana IX three-body interaction. Operator dependent correlations, which consider channels up to the tensor ones, have been used. We found noticeable effects produced by the correlations. For high momentum values, the momentum distributions show large enhancements with respect to the independent particle model results. Natural orbit occupation numbers are depleted by about 10% with respect to the independent particle model values. The effects of the correlations on the spectroscopic factors are larger on the most deeply bound states.

  2. 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.

  3. Particle-number projected electric quadrupole moment of even-even proton-rich nuclei in the isovector pairing case

    NASA Astrophysics Data System (ADS)

    Douici, Mohamed; Allal, Nassima-Hosni; Fellah, Mohamed; Benhamouda, Naziha; Oudih, Mohamed-Reda

    2014-03-01

    The effect of the particle-number projection on the electric quadrupole moment (Q2) of even-even proton-rich nuclei is studied in the isovector neutron-proton (np) pairing case. As a first step, an expression of the electric quadrupole moment, which takes into account the isovector np pairing effect and which conserves the particle-number, is established within the Sharp-BCS (SBCS) method. This expression does generalize the one used in the pairing between like-particles case. As a second step, Q2 is calculated for even-even proton-rich nuclei using the single-particle energies of a Woods-Saxon mean-field. The obtained results are compared with the results obtained in the pairing between like-particles case. It is shown that the np pairing effect, as well as the projection one, is maximal when N=Z.

  4. Stability of proton-rich nuclei in the upper {ital sd} shell and lower {ital pf} shell

    SciTech Connect

    Cole, B.J.

    1996-09-01

    The decay properties of proton-rich nuclei with {ital Z}=19{endash}30 are investigated using measured binding energies of the analog neutron-rich nuclei and Coulomb energy shifts deduced from a parametrization of measured Coulomb displacement energies. Predicted binding energies and separation energies are compared where possible with previous calculations; in most cases the calculations agree within the quoted uncertainties. The positions of the one-proton and diproton drip lines are determined from the calculated separation energies. It is suggested that good candidates for the observation of correlated two-proton emission are {sup 34}Ca, {sup 38,39}Ti, {sup 45}Fe, {sup 48}Ni, and {sup 54}Zn. {copyright} {ital 1996 The American Physical Society.}

  5. K-isomers in Hf nuclei at and beyond the neutron-rich edge of {beta}-stability.

    SciTech Connect

    Chowdhury, P.; Alarcao, R. D.; Seabury, E. H.; Walker, P. M.; Wheldon, C.; Ahmad. I.; Carpenter, M. P.; Hackman, G.; Janssens, R. V. F.; Khoo, T. L.; Nisius, D.; Reiter, P.

    1999-03-30

    New high-K isomers are populated in {sup 180,181,182}Hf nuclei via inelastic excitation and transfer reactions, using pulsed {sup 238}U beams on Hf targets. The new data explore K-hindrances for different multipolarities and the role of residual spin-spin interactions for multi-quasiparticle (qp) configurations at the neutron-rich edge of the {beta}-stability line. The mapping of 4-qp K-isomers in the A {approx} 180 region is extended into neutron-rich territory.

  6. New isotope {sup 44}Si and systematics of the production cross sections of the most neutron-rich nuclei

    SciTech Connect

    Tarasov, O. B.; Baumann, T.; Bazin, D.; III, C. M. Folden; Ginter, T. N.; Hausmann, M.; Matos, M.; Portillo, M.; Schiller, A.; Stolz, A.; Amthor, A. M.; Gade, A.; Nettleton, A.; Sherrill, B. M.; Thoennessen, M.; Morrissey, D. J.

    2007-06-15

    The results of measurements of the production of neutron-rich nuclei by the fragmentation of a {sup 48}Ca beam at 142 MeV/nucleon are presented. Evidence was found for the production of a new isotope that is the most neutron-rich silicon nuclide, {sup 44}Si, in a net neutron pickup process. A simple systematic framework was found to describe the production cross sections based on thermal evaporation from excited prefragments that allows extrapolation to other weak reaction products.

  7. Beta Decay Studies of Proton Rich Nuclei, an Important Ingredient for rp-Process Calculations

    NASA Astrophysics Data System (ADS)

    Rubio, B.; Kucuk, L.; Orrigo, S. E. A.; Fujita, Y.; Gelletly, W.; Blank, B.; Adachi, T.; Aguilera, P.; Agramunt, J.; Algora, A.; Ascher, P.; Bilgier, B.; Cáceres, L.; Cakirli, R. B.; de France, G.; de Oliveira Santos, F.; Fujita, H.; Ganioğlu, E.; Gerbaux, M.; Giovinazzo, J.; Grévy, S.; Kamalou, O.; Kozer, H. C.; Kurtukian-Nieto, T.; Marqués, M.; Molina, F.; Nishimura, D.; Oikawa, H.; Oktem, Y.; Perrot, L.; Popescu, L.; Raabe, R.; Rogers, A. M.; Srivastava, P. C.; Susoy, G.; Stodel, C.; Suzuki, T.; Tamii, A.; Thomas, J. C.

    We have performed a series of beta-decay experiments at fragmentation facilities on Tz = -1/2, Tz = -1, and Tz = -2 nuclei. Most of these nuclei lie on the rp-process path and therefore some of the quantities we have measured such as T1/2 values are important ingredients in performing reaction flow calculations for light curve estimates and testing astrophysical models of X-ray bursters. At this conference we have presented the results of measurements of T1/2 values for 25 nuclei and compared with previous values.

  8. Surface properties of neutron-rich exotic nuclei: A source for studying the nuclear symmetry energy

    SciTech Connect

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

    2011-09-15

    We study the correlation between the thickness of the neutron skin in finite nuclei and the nuclear symmetry energy for isotopic chains of even-even Ni, Sn, and Pb nuclei in the framework of the deformed self-consistent mean-field Skyrme HF + BCS method. The symmetry energy, the neutron pressure, and the asymmetric compressibility in finite nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy density functional. The mass dependence of the nuclear symmetry energy and the neutron-skin thickness are also studied together with the role of the neutron-proton asymmetry. A correlation between the parameters of the equation of state (symmetry energy and its density slope) and the neutron skin is suggested in the isotopic chains of Ni, Sn, and Pb nuclei.

  9. Precision Mass Measurements of Short-Lived, Neutron-Rich, R-Process Nuclei About the N=82 Waiting Point

    NASA Astrophysics Data System (ADS)

    Lascar, Daniel David

    This thesis details the precision mass measurements of 33 neutron-rich ground-state nuclei and isomeric states that approach or lie on the proposed rapid neutron capture process (r-process) path. For many of the nuclei measured the work presented here will be the rst direct mass measurements of these nuclei, including 130In, 137Sb, 133I, and 134I. The measurements were made using the Canadian Penning Trap mass spectrometer (CPT), located at the ATLAS heavy ion-linac at Argonne National Laboratory. Ground states and isomers have been measured with the CPT at fractional precisions (δm/m) between 10-7, and 10-8. The nuclei were produced at the new CAlifornium Rare Isotope Breeder Upgrade (CARIBU) to ATLAS. Because nuclear masses are required for measuring neutron separation energies, and neutron separation energies are important inputs in r-process network calculations, precision mass measurements are critical for advancing our knowledge of the r-process. This thesis will give the astrophysical motivation for making these mass measurements, the theoretical background behind ion trapping and mass measurements using ion traps, an explanation of the CPT apparatus, the mass measurements themselves, and the results of those measurements as they pertain to r-process network calculations. Results of these mass measurements show significant shifts in the r-process path over a range of temperatures and neutron densities.

  10. 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.

  11. Neutron-Rich Nuclei and Neutron Stars: A New Accurately Calibrated Interaction for the Study of Neutron-Rich Matter

    SciTech Connect

    Todd-Rutel, B.G.; Piekarewicz, J.

    2005-09-16

    An accurately calibrated relativistic parametrization is introduced to compute the ground state properties of finite nuclei, their linear response, and the structure of neutron stars. While similar in spirit to the successful NL3 parameter set, it produces an equation of state that is considerably softer--both for symmetric nuclear matter and for the symmetry energy. This softening appears to be required for an accurate description of several collective modes having different neutron-to-proton ratios. Among the predictions of this model are a symmetric nuclear-matter incompressibility of K=230 MeV and a neutron skin thickness in {sup 208}Pb of R{sub n}-R{sub p}=0.21 fm. The impact of such a softening on various neutron-star properties is also examined.

  12. Neutron-rich nuclei and neutron stars: a new accurately calibrated interaction for the study of neutron-rich matter.

    PubMed

    Todd-Rutel, B G; Piekarewicz, J

    2005-09-16

    An accurately calibrated relativistic parametrization is introduced to compute the ground state properties of finite nuclei, their linear response, and the structure of neutron stars. While similar in spirit to the successful NL3 parameter set, it produces an equation of state that is considerably softer--both for symmetric nuclear matter and for the symmetry energy. This softening appears to be required for an accurate description of several collective modes having different neutron-to-proton ratios. Among the predictions of this model are a symmetric nuclear-matter incompressibility of K=230 MeV and a neutron skin thickness in 208 Pb of Rn-Rp=0.21 fm. The impact of such a softening on various neutron-star properties is also examined.

  13. Crossings in alternating-parity bands of neutron-rich Ba nuclei

    SciTech Connect

    Urban, W.; Jones, M.A.; Durell, J.L.

    1995-07-22

    {sup 144}Ba and {sup 146}Ba nuclei produced in the spontaneous fission of {sup 248}Cm have been studied using the EUROGRAM II array. Spins and parities of excited levels have been deduced from triple-{gamma} angular correlation and direction-polarization correlation measurements, which is the first use of these techniques in studies of fission product nuclei. Ground-state, alternating-parity bands have been extended significantly and crossing in these bands has been found in both isotopes. For the first time alternating-parity band termination by particle alignment has been observed.

  14. 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.

  15. Shape coexistence effects on stellar weak interaction rates of proton-rich nuclei within beyond-mean-field approach

    NASA Astrophysics Data System (ADS)

    Petrovici, A.; Andrei, O.

    2017-06-01

    Relevant for the astrophysical rp-process, proton-rich A˜70 nuclei manifesting shape coexistence have been investigated in the frame of the beyond-mean-field complex Excited Vampir variational model with symmetry projection before variation using the effective interaction obtained from a G-matrix based on BonnA/BonnCD potential. Reliable predictions on stellar weak interaction rates emerged starting from the realistic description of the experimentally accesible properties. The influence of shape coexistence and mixing in the structure of the low-lying parent states as well as in the independently calculated daughter states on weak interaction rates under X-ray burst environment is discussed.

  16. Masses of proton-rich T/sub z/<0 nuclei via the isobaric mass equation

    SciTech Connect

    Pape, A.; Antony, M.S.

    1988-07-01

    Masses of T/sub z/<0 nuclei through the element Sm, corresponding to Aless than or equal to117, have been calculated with the isobaric multiplet mass equation using parameterizations of its constant b and T/sub z/>0 reference masses of Wapstra, Audi, and Hoekstra. copyright 1988 Academic Press, Inc.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Praharaj, Choudhury

    2016-03-01

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

  19. Exploring Light Neutron Rich Nuclei via the ({sup 7}Li,{sup 7}Be) Reaction

    SciTech Connect

    Cavallaro, M.; Cappuzzello, F.; Cunsolo, A.; Foti, A.; Orrigo, S. E. A.; Rodrigues, M. R. D.; Borello-Lewin, T.; Lenske, H.; Petrascu, H.; Winfield, J. S.

    2008-11-11

    A systematic study of the nuclei that can be described as an integer number of {alpha} particles plus three neutrons via the ({sup 7}Li,{sup 7}Be) reaction at about 8 MeV/u has shown the presence of Bound States Embedded in the Continuum in the energy spectra. These are experimental signatures of the dynamical correlations of an easily polarizable core with a single-particle state of the valence neutron.

  20. Novel triaxial structure in low-lying states of neutron-rich nuclei around A ≈100

    NASA Astrophysics Data System (ADS)

    Xiang, J.; Yao, J. M.; Fu, Y.; Wang, Z. H.; Li, Z. P.; Long, W. H.

    2016-05-01

    Background: In recent years, the study of triaxiality in the low-lying states of atomic nuclei with transition character or shape coexistence has been of great interest. Previous studies indicate that the neutron-rich nuclei in the A ˜100 mass region with Z ˜40 ,N ˜60 serve as good grounds for examining the role of triaxiality in nuclear low-lying states. Purpose: The aim of this work is to provide a microscopic study of low-lying states for nuclei in the A ˜100 mass regions and to examine in detail the role of triaxiality in the shape-coexistence phenomena and the variation of shape with the isospin and spin values at the beyond mean-field level. Method: The starting point of our method is a set of relativistic mean-field plus BCS wave functions generated with a constraint on triaxial deformations (β ,γ ) . The excitation energies and electric multipole transition strengths of low-lying states are calculated by solving a five-dimensional collective Hamiltonian (5DCH) with parameters determined by the mean-field wave functions. Results: The low-lying states of Mo isotopes and of N =60 isotones in the A ˜100 mass region are calculated. The results indicate that triaxiality is essential to reproduce the data of excitation energies and electric quadrupole transition strengths in low-lying states and plays an important role in the shape evolution as a function of nucleon number. However, the decrease of nuclear collectivity with the increase of angular momentum in neutron-rich Mo isotopes has not been reproduced. Conclusions: The evolution of nuclear collectivity in the low-lying states of neutron-rich nuclei in the A ˜100 mass region as a function of nucleon number is governed by the novel triaxial structure. However, the mechanism that governs the variation of nuclear shape with spin in Mo isotopes remains unclear and deserves further investigation by taking into account the effects other than the collective motions.

  1. Near and sub-barrier fusion of neutron-rich oxygen and carbon nuclei using low-intensity beams

    NASA Astrophysics Data System (ADS)

    Steinbach, Tracy K.

    Fusion between neutron-rich light nuclei in the crust of an accreting neutron star has been proposed as a heat source that triggers an X-ray superburst. To explore the probability with which such fusion events occur and examine their decay characteristics, an experimental program using beams of neutron-rich light nuclei has been established. Evaporation residues resulting from the fusion of oxygen and 12C nuclei, are directly measured and distinguished from unreacted beam particles on the basis of their energy and time-of-flight. Using an experimental setup developed for measurements utilizing low-intensity (< 105 ions/s) radioactive beams, the fusion excitation functions for 16O + 12C and 18O + 12C have been measured. The fusion excitation function for 18O + 12C has been measured in the sub-barrier domain down to the 820 mub level, a factor of 30 lower than previous direct measurements. This measured fusion excitation function is compared to the predictions of a density constrained time-dependent Hartree-Fock model. This comparison reveals a shape difference in the fusion excitation functions, indicating a larger tunneling probability for the experimental data as compared to the theoretical calculations. In addition to the measured cross-section, the measured angular distribution of the evaporation residues provides insight into the relative importance of the different de-excitation channels. These evaporation residue angular distributions are compared to the predictions of a statistical model code, evapOR, revealing an under-prediction of the de-excitation channels associated with alpha particle emission.

  2. Invariant-Mass Spectroscopy of Extremely Neutron-Rich Nuclei with SAMURAI at RIBF

    NASA Astrophysics Data System (ADS)

    Kondo, Yosuke; Nakamura, Takashi; Achouri, N. Lynda; Aumann, Thomas; Baba, Hidetada; Delaunay, Franck; Doornenbal, Pieter; Fukuda, Naoki; Gibelin, Julien; Hwang, Jongwon; Inabe, Naohito; Isobe, Tadaaki; Kameda, Daisuke; Kanno, Daiki; Kim, Sunji; Kobayashi, Nobuyuki; Kobayashi, Toshio; Kubo, Toshiyuki; Leblond, Sylvain; Lee, Jenny; Marqués, F. Miguel; Minakata, Ryogo; Motobayashi, Tohru; Murai, Daichi; Murakami, Tetsuya; Muto, Kotomi; Nakashima, Tomohiro; Nakatsuka, Noritsugu; Navin, Alahari; Nishi, Seijiro; Ogoshi, Shun; Orr, Nigel A.; Otsu, Hideaki; Sato, Hiromi; Satou, Yoshiteru; Shimizu, Yohei; Suzuki, Hiroshi; Takahashi, Kento; Takeda, Hiroyuki; Takeuchi, Satoshi; Tanaka, Ryuki; Togano, Yasuhiro; Tuff, Adam G.; Vandebrouck, Marine; Yoneda, Ken-ichiro

    A first experimental campaign for three physics programs using a spectrometer SAMURAI, which is newly constructed at RIBF at RIKEN, was performed in May 2012. In this campaign, the unbound nuclei 25O and 26O produced by one-proton removal reactions at ˜200 MeV/nucleon were investigated by means of invariant mass method. High statistics data compared with previous experiments could be obtained together with good particle identification resolution for outgoing heavy ion. Preliminary results show high performance of the SAMURAI spectrometer combined with high intense RI beams provided by RIBF.

  3. Evidence for a Change in the Nuclear Mass Surface with the Discovery of the Most Neutron-Rich Nuclei with 17{<=}Z{<=}25

    SciTech Connect

    Tarasov, O. B.; Morrissey, D. J.; Amthor, A. M.; Gade, A.; Nettleton, A.; Sherrill, B. M.; Thoennessen, M.; Baumann, T.; Bazin, D.; Ginter, T. N.; Hausmann, M.; Pereira, J.; Portillo, M.; Stolz, A.; Inabe, N.; Kubo, T.

    2009-04-10

    The results of measurements of the production of neutron-rich nuclei by the fragmentation of a {sup 76}Ge beam are presented. The cross sections were measured for a large range of nuclei including 15 new isotopes that are the most neutron-rich nuclides of the elements chlorine to manganese ({sup 50}Cl, {sup 53}Ar, {sup 55,56}K, {sup 57,58}Ca, {sup 59,60,61}Sc, {sup 62,63}Ti, {sup 65,66}V, {sup 68}Cr, {sup 70}Mn). The enhanced cross sections of several new nuclei relative to a simple thermal evaporation framework, previously shown to describe similar production cross sections, indicates that nuclei in the region around {sup 62}Ti might be more stable than predicted by current mass models and could be an indication of a new island of inversion similar to that centered on {sup 31}Na.

  4. Production of beams of neutron-rich nuclei between Ca and Ni using the ion-guide technique

    SciTech Connect

    Perajarvi, K.; Cerny, J.; Hager, U.; Hakala, J.; Huikari, J.; Jokinen, A.; Karvonen, P.; Kurpeta, J.; Lee, D.; Moore, I.; Penttila, H.; Popov, A.; Aysto, J.

    2004-09-28

    Since several elements between Z = 20-28 are refractory in their nature, their neutron-rich isotopes are rarely available as low energy Radioactive Ion Beams (RIB) in ordinary Isotope Separator On-Line facilities [1-4]. These low energy RIBs would be especially interesting to have available under conditions which allow high-resolution beta-decay spectroscopy, ion-trapping and laser-spectroscopy. As an example, availability of these beams would open a way for research which could produce interesting and important data on neutron-rich nuclei around the doubly magic {sup 78}Ni. One way to overcome the intrinsic difficulty of producing these beams is to rely on the chemically unselective Ion Guide Isotope Separator On-Line (IGISOL) technique [5]. Quasi- and deep-inelastic reactions, such as {sup 197}Au({sup 65}Cu,X)Y, could be used to produce these nuclei in existing IGISOL facilities, but before they can be successfully incorporated into the IGISOL concept their kinematics must be well understood. Therefore the reaction kinematics part of this study was first performed at the Lawrence Berkeley National Laboratory using its 88'' cyclotron and, based on those results, a specialized target chamber was built[6]. The target chamber shown in Fig. 1 was recently tested on-line at the Jyvaaskylaa IGISOL facility. Yields of mass-separated radioactive projectile-like species such as {sup 62,63}Co are about 0.8 ions/s/pnA, corresponding to about 0.06 % of the total IGISOL efficiency for the products that hit the Ni-degrader. (The current maximum 443 MeV {sup 65}Cu beam intensity at Jyvaaskylaa is about 20 pnA.) This total IGISOL efficiency is a product of two coupled loss factors, namely inadequate thermalization and the intrinsic IGISOL efficiency. In our now tested chamber, about 9 % of the Co recoils are thermalized in the owing He gas (p{sub He}=300 mbar) and about 0.7 % of them are converted into the mass-separated ion beams. In the future, both of these physical

  5. Fragmentation cross sections and binding energies of neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Tsang, M. B.; Lynch, W. G.; Friedman, W. A.; Mocko, M.; Sun, Z. Y.; Aoi, N.; Cook, J. M.; Delaunay, F.; Famiano, M. A.; Hui, H.; Imai, N.; Iwasaki, H.; Motobayashi, T.; Niikura, M.; Onishi, T.; Rogers, A. M.; Sakurai, H.; Suzuki, H.; Takeshita, E.; Takeuchi, S.; Wallace, M. S.

    2007-10-01

    An exponential dependence of the fragmentation cross section on the average binding energy is observed and reproduced with a statistical model. The observed functional dependence is robust and allows the extraction of binding energies from measured cross sections. From the systematics of Cu isotope cross sections, the binding energies of Cu76,77,78,79 have been extracted. They are 636.94±0.4,647.1±0.4,651.6±0.4, and 657.8±0.5 MeV, respectively. Specifically, the uncertainty of the binding energy of Cu75 is reduced from 980 keV, as listed in the 2003 mass table of Audi, Wapstra, and Thibault to 400 keV. The predicted cross sections of two near drip-line nuclei, Na39 and Mg40 from the fragmentation of Ca48 are discussed.

  6. Fragmentation cross sections and binding energies of neutron-rich nuclei

    SciTech Connect

    Tsang, M. B.; Lynch, W. G.; Mocko, M.; Cook, J. M.; Delaunay, F.; Famiano, M. A.; Hui, H.; Rogers, A. M.; Wallace, M. S.; Friedman, W. A.; Sun, Z. Y.; Aoi, N.; Imai, N.; Motobayashi, T.; Takeuchi, S.; Iwasaki, H.; Onishi, T.; Sakurai, H.; Suzuki, H.; Niikura, M.

    2007-10-15

    An exponential dependence of the fragmentation cross section on the average binding energy is observed and reproduced with a statistical model. The observed functional dependence is robust and allows the extraction of binding energies from measured cross sections. From the systematics of Cu isotope cross sections, the binding energies of {sup 76,77,78,79}Cu have been extracted. They are 636.94{+-}0.4,647.1{+-}0.4,651.6{+-}0.4, and 657.8{+-}0.5 MeV, respectively. Specifically, the uncertainty of the binding energy of {sup 75}Cu is reduced from 980 keV, as listed in the 2003 mass table of Audi, Wapstra, and Thibault to 400 keV. The predicted cross sections of two near drip-line nuclei, {sup 39}Na and {sup 40}Mg from the fragmentation of {sup 48}Ca are discussed.

  7. β-decay of neutron-rich Z∼60 nuclei and the origin of rare earth elements

    SciTech Connect

    Wu, J.; Nishimura, S.; Lorusso, G.; Baba, H.; Doornenbal, P.; Isobe, T.; Söderström, P. A.; Sakurai, H.; Xu, Z. Y.; Browne, F.; Daido, R.; Fang, Y. F.; Yagi, A.; Nishibata, H.; Odahara, A.; Yamamoto, T.; Ideguchi, E.; Aoi, N.; Tanaka, M.; Collaboration: EURICA Collaboration; and others

    2014-05-02

    A large fraction of the rare-earth elements observed in the solar system is produced in the astrophysical rapid neutron capture process (r-process). However, current stellar models cannot completely explain the relative abundance of these elements partially because of nuclear physics uncertainties. To address this problem, a β-decay spectroscopy experiment was performed at RI Beam Factory (RIBF) at RIKEN, aimed at studying a wide range of very neutron-rich nuclei with Z∼60 that are progenitors of the rare-earth elements with mass number A∼460. The experiment provides a test of nuclear models as well as experimental inputs for r-process calculations. This contribution presents the experimental setup and some preliminary results of the experiment.

  8. Different mechanism of two-proton emission from proton-rich nuclei 23Al and 22Mg

    NASA Astrophysics Data System (ADS)

    Ma, Y. G.; Fang, D. Q.; Sun, X. Y.; Zhou, P.; Togano, Y.; Aoi, N.; Baba, H.; Cai, X. Z.; Cao, X. G.; Chen, J. G.; Fu, Y.; Guo, W.; Hara, Y.; Honda, T.; Hu, Z. G.; Ieki, K.; Ishibashi, Y.; Ito, Y.; Iwasa, N.; Kanno, S.; Kawabata, T.; Kimura, H.; Kondo, Y.; Kurita, K.; Kurokawa, M.; Moriguchi, T.; Murakami, H.; Ooishi, H.; Okada, K.; Ota, S.; Ozawa, A.; Sakurai, H.; Shimoura, S.; Shioda, R.; Takeshita, E.; Takeuchi, S.; Tian, W. D.; Wang, H. W.; Wang, J. S.; Wang, M.; Yamada, K.; Yamada, Y.; Yasuda, Y.; Yoneda, K.; Zhang, G. Q.; Motobayashi, T.

    2015-04-01

    Two-proton relative momentum (qpp) and opening angle (θpp) distributions from the three-body decay of two excited proton-rich nuclei, namely 23Al → p + p +21Na and 22Mg → p + p +20Ne, have been measured with the projectile fragment separator (RIPS) at the RIKEN RI Beam Factory. An evident peak at qpp ∼ 20 MeV / c as well as a peak in θpp around 30° are seen in the two-proton break-up channel from a highly-excited 22Mg. In contrast, such peaks are absent for the 23Al case. It is concluded that the two-proton emission mechanism of excited 22Mg is quite different from the 23Al case, with the former having a favorable diproton emission component at a highly excited state and the latter dominated by the sequential decay process.

  9. High-precision β decay half-life measurements of proton-rich nuclei for testing the CVC hypothesis

    NASA Astrophysics Data System (ADS)

    Kurtukian-Nieto, T.

    2011-11-01

    The experimental study of super-allowed nuclear β decays serves as a sensitive probe of the conservation of the weak vector current (CVC) and allows tight limits to be set on the presence of scalar or right-handed currents. Once CVC is verified, it is possible to determine the Vud element of the CKM quark-mixing matrix. Similarly, the study of nuclear mirror β decays allows to arrive at the same final quantity Vud. Whereas dedicated studies of 0+ → 0+ decays are performed for several decades now, the potential of mirror transitions was only rediscovered recently. Therefore, it can be expected that important progress is possible with high-precision studies of different mirror β decays. In the present piece of work the half-life measurements performed by the CENBG group of the proton-rich nuclei 42Ti, 38-39Ca, 30-31S and 29P are summarised.

  10. Projected shell model study of odd-odd f-p-g shell proton-rich nuclei

    NASA Astrophysics Data System (ADS)

    Palit, R.; Sheikh, J. A.; Sun, Y.; Jain, H. C.

    2003-01-01

    A systematic study of two-quasiparticle bands of the proton-rich odd-odd nuclei in the mass A˜70 80 region is performed using the projected shell model approach. The study includes Br, Rb, and Y isotopes with N=Z+2 and Z+4. We describe the energy spectra and electromagnetic transition strengths in terms of the configuration mixing of the angular-momentum projected multi-quasiparticle states. Signature splitting and signature inversion in the rotational bands are discussed and are shown to be well described. A preliminary study of the odd-odd N=Z nucleus 74Rb, using the concept of spontaneous symmetry breaking is also presented.

  11. Continuum quasiparticle random-phase approximation for astrophysical direct neutron capture reactions on neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Matsuo, Masayuki

    2015-03-01

    I formulate a many-body theory to calculate the cross section of direct radiative neutron capture reaction by means of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random-phase approximation (QRPA). A focus is put on very-neutron-rich nuclei and low-energy neutron kinetic energy in the range from 1 keV to several MeV, which is relevant to the rapid neutron capture process of nucleosynthesis. I begin with the photoabsorption cross section and the E 1 strength function. Next, in order to apply the reciprocity theorem, I decompose the cross section into partial cross sections corresponding to different channels of one- and two-neutron emission decays of photo-excited states. A numerical example is shown for the photo-absorption of 142Sn and the neutron capture of 141Sn .

  12. Use of Neutron Transfer Reactions to Indirectly Determine Neutron Capture Cross Sections on Neutron-Rich Nuclei

    SciTech Connect

    McCleskey, M.; Mukhamedzhanov, A. M.; Tribble, R. E.; Simmons, E.; Spiridon, A.; Banu, A.; Roeder, B.; Goldberg, V.; Trache, L.; Chen, X. F.; Lui, Y.-W.

    2010-03-01

    {sup 14}C(n,gamma){sup 15}C is being used as a test case in the development of an indirect method to determine neutron capture cross sections on neutron-rich unstable nuclei at astrophysical energies. Our approach makes use of two reactions: one peripheral used to find the asymptotic normalization coefficient (ANC) and a second non-peripheral reaction to determine the spectroscopic factor. The ANC for {sup 15}C has been determined using a HI neutron transfer reaction with a 12 MeV/nucleon {sup 14}C beam on a {sup 13}C target. The spectroscopic factor will be determined using {sup 14}C(d,p) in forward kinematics with an incident deuteron energy of 60 MeV. Both experiments were performed using the MDM high-resolution spectrometer at Texas A and M University.

  13. Enhancement of fusion at near-barrier energies for neutron-rich light nuclei: 19O +12 C

    NASA Astrophysics Data System (ADS)

    Singh, Varinderjit; Vadas, J.; Steinbach, T. K.; Wiggins, B. B.; Hudan, S.; Desouza, R. T.; Baby, L. T.; Kuvin, S. A.; Tripathi, Vandana; Wiedenhover, I.; Umar, A. S.

    2017-01-01

    Measuring the fusion excitation function for an isotopic chain of projectile nuclei provides a sensitive test of a microscopic description of fusion. To investigate the theoretically predicted fusion enhancement for neutron-rich light nuclei, an experiment was performed to measure the fusion excitation functions for 19 O +12 C and 18 O +12 C . Using the 18O(d,p) reaction and the RESOLUT mass spectrometer at Florida State University, a beam of 19O was produced with an intensity of 2-4 x 103 p/s. This beam bombarded a 100 μg/cm2 carbon target. Using an approach optimized for the measurement of fusion with a low-intensity beam, evaporation residues (ERs) resulting from the de-excitation of the fusion product were measured. The ERs were identified by measuring their energy and time-of-flight. At near-barrier energies, an enhancement of fusion by a factor of three has been observed for 19 O +12 C in comparison to 18 O +12 C . Comparison of the experimental results with the predictions of a density constrained time-dependent Hartree-Fock (DC-TDHF) model provide evidence for the importance of pairing in the fusion process. Supported by the US DOE under Grant No. DEFG02-88ER-40404.

  14. β -decay half-lives of neutron-rich nuclei at A ~ 110 on r-process path

    NASA Astrophysics Data System (ADS)

    Nishizuka, Ippei; Sumikama, Toshiyuki; Browne, Frank; Bruce, Alison; Nishimura, Shunji; Doornenbal, Pieter; Lorusso, Giuseppe; Patel, Zena; Rice, Simon; Sinclair, Laura; Soderstom, Par-Ander; Watanabe, Hiroshi; Wu, Jin; Xu, Zhengyu; Yagi, Ayumi; Eurica Collaboration

    2014-09-01

    About half of the elements heavier than iron are thought to be produced by rapid-neutron capture process (r-process). The observed natural abundance in solar system was underestimated by a theoretical model at A ~ 110 , which uses β-decay half-lives. In the present study, we measured new β half-lives of neutron-rich nuclei on r-process path at RIBF in RIKEN. The nuclei of interest were produced by in-flight fission of uranium beam in beryllium target. The WAS3ABi detector which was 5 stacked double-sided silicon strip detectors (60 × 40 × 1 mm3), was used for the implantation of ions and the detection of both the implanted ions and the subsequently-emitted β rays. It is essential to make a position correlation between the mother nucleus and the β rays. In this talk, the analysis of the position correlation will be presented in detail. Preliminary results will be also shown.

  15. Beta-Decay and Delayed Neutron Emission of Very Neutron-Rich Nuclei

    NASA Astrophysics Data System (ADS)

    Borzov, I. N.

    2014-09-01

    Extended self-consistent beta-decay model has been applied for beta-decay rates and delayed multi-neutron emission probabilities of quasi-spherical neutron-rich isotopes. The Gamow-Teller and first-forbidden decays are treated within the coordinate-space formalism of the continuum QRPA based on the density functional theory description of the ground state. A new set of the Fayans density functional parameters (DF3a) have been employed giving a better spin-orbit splitting due to a stronger tensor term. A provision has been included to fix the odd particle in the proper orbit (before variation). This accounts for ground-state spin inversion effect which has been shown to exist in the region of the most neutron-rich doubly-magic nucleus 78Ni.

  16. Influence of pairing correlations on the radius of neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Chen, Ying; Meng, Jie; Ring, Peter

    2017-01-01

    The influence of pairing correlations on the neutron root mean square (rms) radius of nuclei is investigated in the framework of self-consistent Skyrme Hartree-Fock-Bogoliubov calculations. The continuum is treated appropriately by the Green's function techniques. As an example the nucleus 124Zr is treated for a varying strength of pairing correlations. We find that, as the pairing strength increases, the neutron rms radius first shrinks, reaches a minimum, and beyond this point it expands again. The shrinkage is due to the the so-called pairing antihalo effect, i.e., due to the decrease of the asymptotic density distribution with increasing pairing. However, in some cases, increasing pairing correlations can also lead to an expansion of the nucleus due to a growing occupation of so-called halo orbits, i.e., weakly bound states and resonances in the continuum with low-ℓ values. In this case, the neutron radii are extended just by the influence of pairing correlations, since these halo orbits cannot be occupied without pairing. The term "antihalo effect" is not justified in such cases. For a full understanding of this complicated interplay, self-consistent calculations are necessary.

  17. Particle-number conservation in odd mass proton-rich nuclei in the isovector pairing case

    NASA Astrophysics Data System (ADS)

    Fellah, M.; Allal, N. H.; Oudih, M. R.

    2015-06-01

    An expression of a wave function which describes odd-even systems in the isovector pairing case is proposed within the BCS approach. It is shown that it correctly generalizes the one used in the pairing between like-particles case. It is then projected on the good proton and neutron numbers using the Sharp-BCS (SBCS) method. The expressions of the expectation values of the particle-number operator and its square, as well as the energy, are deduced in both approaches. The formalism is applied to study the isovector pairing effect and the number projection one on the ground state energy of odd mass N ≈ Z nuclei using the single-particle energies of a deformed Woods-Saxon mean-field. It is shown that both effects on energy do not exceed 2%, however, the absolute deviations may reach several MeV. Moreover, the np pairing effect rapidly diminishes as a function of (N - Z). The deformation effect is also studied. It is shown that the np pairing effect, either before or after the projection, as well as the projection effect, when including or not the isovector pairing, depends upon the deformation. However, it seems that the predicted ground state deformation will remain the same in the four approaches.

  18. Interaction radii of proton-rich radioactive nuclei at A=60-80

    SciTech Connect

    Lima, G. F.; Lepine-Szily, A.; Lichtenthaler, R.; Villari, A. C. C.; Mittig, W.; Casandjian, J. M.; Lewitowicz, M.; Chartier, M.; Hirata, D.; Angelique, J. C.; Orr, N. A.; Audi, G.; Cunsolo, A.; Foti, A.; Donzeaud, C.; MacCormick, M.; Stephan, C.; Suomijarvi, T.; Tassan-Got, L.; Gillibert, A.

    1998-12-21

    The interaction radii of proton-rich, radioactive {sub 31}Ga, {sub 32}Ge, {sub 33}As, {sub 34}Se, {sub 35}Br isotopes were measured using the direct method. The secondary beams were produced using a {sup 78}Kr primary beam of 73 MeV/nucleon in conjunction with SISSI and the SPEG spectrometers at GANIL. Most elements show reduced radii which vary with N, with a minimum around N=36-38. The experimental reduced radii are compared to theoretical values obtained from Glauber reaction cross-section calculations based on Relativistic Mean Field (RMF) nuclear densities.

  19. 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.

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

    SciTech Connect

    Yoshida, Kenichi

    2015-10-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  2. Interaction radii of proton-rich radioactive nuclei at A=60{endash}80

    SciTech Connect

    Lima, G.F.; Lepine-Szily, A.; Villari, A.C.; Lichtenthaler, R.; Villari, A.C.; Mittig, W.; Chartier, M.; Casandjian, J.M.; Lewitowicz, M.; Ostrowski, A.N.; Hirata, D.; Angelique, J.C.; Orr, N.A.; Audi, G.; Cunsolo, A.; Foti, A.; Donzeaud, C.; MacCormick, M.; Stephan, C.; Suomijarvi, T.; Tassan-Got, L.; Gillibert, A.; Chartier, M.; Morrissey, D.J.; Sherrill, B.M.; Ostrowski, A.N.; Vieira, D.J.; Wouters, J.M.

    1998-12-01

    The interaction radii of proton-rich, radioactive {sub 31}Ga,thinsp{sub 32}Ge,thinsp{sub 33}As,thinsp{sub 34}Se,thinsp{sub 35}Br isotopes were measured using the direct method. The secondary beams were produced using a {sup 78}Kr primary beam of 73 MeV/nucleon in conjunction with SISSI and the SPEG spectrometers at GANIL. Most elements show reduced radii which vary with N, with a minimum around N=36{endash}38. The experimental reduced radii are compared to theoretical values obtained from Glauber reaction cross-section calculations based on Relativistic Mean Field (RMF) nuclear densities. {copyright} {ital 1998 American Institute of Physics.}

  3. Neutron-rich nuclei in cosmic rays and Wolf-Rayet stars

    NASA Technical Reports Server (NTRS)

    Prantzos, N.; Arnould, M.; Arcoragi, J. P.; Casse, M.

    1985-01-01

    Wolf-Rayet stars figure prominently in astrophysical research. As a bonus, they seem to offer, in the recent past, an interesting connection between classical astronomy and high energy astrophysics due to their unusual composition and their huge mechanical power. The material flowing from WC stars (carbon-rich WR stars) contains gas which has been processed through core-helium burning, i.e., considerably enriched into 12C,16O, 22Ne, and 25,26Mg. This composition is reminiscent of the cosmic ray source anomalies. Encouraging agreement is obtained with observation in the mass range 12 A 26 assuming acceleration of wind particles at the shock that delineates the WR cavity, and adequate dilution with normal cosmic rays, but silicon poses.

  4. Schottky Mass Measurements of Cooled Proton-Rich Nuclei at the GSI Experimental Storage Ring

    SciTech Connect

    Radon, T.; Schlitt, B.; Beckert, K.; Bosch, F.; Eickhoff, H.; Franzke, B.; Geissel, H.; Hausmann, M.; Irnich, H.; Klepper, O.; Kluge, H.; Kozhuharov, C.; Kraus, G.; Muenzenberg, G.; Nickel, F.; Nolden, F.; Patyk, Z.; Reich, H.; Scheidenberger, C.; Schwab, W.; Steck, M.; Suemmerer, K.; Kerscher, T.; Beha, T.; Loebner, K.E.; Fujita, Y.; Jung, H.C.; Wollnik, H.; Novikov, Y.

    1997-06-01

    High-precision mass measurements of proton-rich isotopes in the range of 60{le}Z{le}84 were performed using the novel technique of Schottky spectrometry. Projectile fragments produced by {sup 209}Bi ions at 930{ital A} MeV were separated with the magnetic spectrometer FRS and stored and cooled in the experimental storage ring (ESR). A typical mass resolving power of 350000 and a precision of 100keV were achieved in the region A{approx}200 . Masses of members of {alpha} chains linked by precise Q{sub {alpha}} values but not yet connected to the known masses were determined. In this way it is concluded that {sup 201}Fr and {sup 197}At are proton unbound. {copyright} {ital 1997} {ital The American Physical Society}

  5. Precision mass measurements of neutron-rich nuclei, and limitations on the r-process environment

    NASA Astrophysics Data System (ADS)

    Van Schelt, Jonathon A.

    2012-05-01

    The masses of 65 neutron-rich nuclides and 6 metastable states from Z = 49 to 64 were measured at a typical precision of δm/m= 10-7 using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements are on fission fragments from 252Cf spontaneous fission sources, including those measurements made at the new Californium Rare Isotope Breeder Upgrade facility (CARIBU) and an earlier source. The measured nuclides lie on or approach the predicted path of the astrophysical r process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in β-endpoint measurements. Simulations of the r process were undertaken to determine how quickly material can pass through the studied elements for a variety of conditions, placing limits on what temperatures densities allow passage on a desired timescale. The new masses produce manifold differences in effective lifetime compared to simulations performed with some model masses.

  6. High-K isomers in transactinide nuclei close to N = 162

    SciTech Connect

    Prassa, V. Nikšić, T.; Vretenar, D.; Lu, Bing-Nan; Ackermann, D.

    2015-10-15

    Transactinide nuclei around neutron number N = 162 display axially deformed equilibrium shapes, as shown in our previous analysis [1] of constrained mean-field energy surfaces and collective excitation spectra. In the present study we are particularly interested in the occurrence of high-K isomers in the axially deformed isotopes of Rf (Z = 104), Sg (Z = 106), Hs (Z = 108), and Ds (Z = 110), with neutron number N = 160 − 166 and the effect of the N=162 closure on the structure and distribution of two-quasiparticle (2qp) states. The evolution of high-K isomers is analysed in a self-consistent axially-symmetric relativistic Hartree-Bogoliubov calculation using the blocking approximation with time-reversal symmetry breaking.

  7. -decay measurements for N > 40 Mn nuclei and inference of collectivity for neutron-rich Fe isotopes

    SciTech Connect

    Daugas, J; Delaroche, J. P.; Pfutzner, M.; Sawicka, M.; Becker, F.; Belier, G.; Bingham, C. R.; Borcea, C.; Bouchez, E.; Buta, A.; Dragulescu, E.; Georgiev, G.; Giovinazzo, J.; Grawe, H.; Grzywacz, R.; Hammache, F.; Libert, J.; Meot, V.; Negoita, F.; de Oliveira Santos, F.; Perru, O.; Roig, O.; Rykaczewski, Krzysztof Piotr; Saint-Laurent, M. G.; Sauvestre, J. E.; Sorlin, O.; Stanoiu, M.; Stefan, I.; Theisen, Ch.

    2011-01-01

    A decay spectroscopic study of the neutron-rich isotopes has been performed using fragmentation of a 86Kr primary beam. Fragments from this reaction have been selected by the LISE2000 spectrometer at the Grand Acc el erateur National d Ions Lourds (GANIL). Half-lives of 29 isotopes, including the first ones identified for 61Ti (15 4 ms), 64V (19 8 ms), and 71Fe (28 5 ms), have been determined and compared with model predictions. 67,68Mn -delayed rays were observed for the first time. The branching for the -delayed neutron emission was measured to be greater than 10(5)% in the 67Mn decay. The 67Fe isomeric level is firmly determined at higher energy than assigned in previous works. The excitation energies of the first (2+) and (4+) states of 68Fe are suggested to lie at 522(1) and 1389(1) keV, respectively, thus bringing confirmation of assignments based on in-beam -ray spectroscopy. Beyond-mean-field calculations with the Gogny D1S force have been performed for even-mass nuclei through the Fe isotopic chain. Not only 68Fe but most of the neutron-rich Fe isotopes with neutron numbers below N = 50 are interpreted as soft rotors. The calculated mean occupancy of the neutron g9/2 and d5/2 orbitals in correlated ground states is steadily growing with increasing neutron number throughout the isotopic chain. Interpretation of 67Fe data is based upon the present calculations for the 66Fe and 68Fe even cores.

  8. High-precision {beta} decay half-life measurements of proton-rich nuclei for testing the CVC hypothesis

    SciTech Connect

    Kurtukian-Nieto, T. [Centre d'Etudes Nucleaires de Bordeaux-Gradignan , Universite Bordeaux 1, CNRS Collaboration: NEX Group of CENBG

    2011-11-30

    The experimental study of super-allowed nuclear {beta} decays serves as a sensitive probe of the conservation of the weak vector current (CVC) and allows tight limits to be set on the presence of scalar or right-handed currents. Once CVC is verified, it is possible to determine the V{sub ud} element of the CKM quark-mixing matrix. Similarly, the study of nuclear mirror {beta} decays allows to arrive at the same final quantity V{sub ud}. Whereas dedicated studies of 0{sup +}{yields}0{sup +} decays are performed for several decades now, the potential of mirror transitions was only rediscovered recently. Therefore, it can be expected that important progress is possible with high-precision studies of different mirror {beta} decays. In the present piece of work the half-life measurements performed by the CENBG group of the proton-rich nuclei {sup 42}Ti, {sup 38-39}Ca, {sup 30-31}S and {sup 29}P are summarised.

  9. Exploring the extended density-dependent Skyrme effective forces for normal and isospin-rich nuclei to neutron stars

    SciTech Connect

    Agrawal, B.K.; Dhiman, Shashi K.; Kumar, Raj

    2006-03-15

    We parametrize the recently proposed generalized Skyrme effective force (GSEF) containing extended density dependence. The parameters of the GSEF are determined by the fit to several properties of the normal and isospin-rich nuclei. We also include in our fit a realistic equation of state for the pure neutron matter up to high densities so that the resulting Skyrme parameters can be suitably used to model the neutron star with the 'canonical' mass ({approx}1.4M{sub {center_dot}}). For the appropriate comparison, we generate a parameter set for the standard Skyrme effective force (SSEF) using exactly the same set data as employed to determine the parameters of the GSEF. We find that the GSEF yields larger values for the neutron skin thickness which are closer to the recent predictions based on the isospin diffusion data. The Skyrme parameters so obtained are employed to compute the strength function for the isoscalar giant monopole, dipole, and quadrupole resonances. It is found that in the case of GSEF, because of the larger value of the nucleon effective mass, the values of centroid energies for the isoscalar giant resonances are in better agreement with the corresponding experimental data than those obtained using the SSEF. We also present results for some of the key properties associated with the neutron star of canonical mass and for the one with the maximum mass.

  10. Dineutron correlations in quasi-two-dimensional systems in a simplified model, and possible relation to neutron-rich nuclei

    SciTech Connect

    Kanada-En'yo, Yoshiko; Hinohara, Nobuo; Suhara, Tadahiro; Schuck, Peter

    2009-05-15

    Two-neutron correlation in the {sup 1}S channel in quasi-two-dimensional (2D) neutron systems at zero temperature is studied by means of the BCS theory with finite-range effective nuclear forces. The dineutron correlation in low density neutron systems confined in an infinite slab is investigated in a simplified model that neutron motion of one direction is frozen. When the slab is thin enough, two neutrons form a tightly bound dineutron with a small size in the quasi-2D system, and a Bose dineutron gas is found in low density limit. With increase of Fermi momentum, the neutron system changes from the Bose-gas phase to the superfluid Cooper pair phase. The density dependence of the neutron pairing shows the BCS-BEC crossover phenomena at finite low-density region. In the transition region, the size shrinking of neutron pair and enhancement of pairing gap are found. The relation to dineutron correlation at surface of neutron-rich nuclei is also discussed.

  11. Shape of {sup 44}Ar: Onset of deformation in neutron-rich nuclei near {sup 48}Ca

    SciTech Connect

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

    2009-07-15

    The development of deformation and shape coexistence in the vicinity of doubly magic {sup 48}Ca, related to the weakening of the N=28 shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive {sup 44}Ar beam from the SPIRAL facility at GANIL. The 2{sub 1}{sup +} and 2{sub 2}{sup +} states in {sup 44}Ar were excited on {sup 208}Pb and {sup 109}Ag targets at two different beam energies. B(E2) values between all observed states and the spectroscopic quadrupole moment of the 2{sub 1}{sup +} state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the {sup 44}Ar nucleus and giving evidence of an onset of deformation already two protons and two neutrons away from doubly magic {sup 48}Ca. New Hartree-Fock-Bogoliubov based configuration mixing calculations have been performed with the Gogny D1S interaction for {sup 44}Ar and neighboring nuclei using two different approaches: the angular momentum projected generator coordinate method considering axial quadrupole deformations and a five-dimensional approach including the triaxial degree of freedom. The experimental values and new calculations are furthermore compared to shell-model calculations and to relativistic mean-field calculations. The new results give insight into the weakening of the N=28 shell closure and the development of deformation in this neutron-rich region of the nuclear chart.

  12. Systematic study of unfavored α -decay half-lives of closed-shell nuclei related to ground and isomeric states

    NASA Astrophysics Data System (ADS)

    Deng, Jun-Gang; Zhao, Jie-Cheng; Xiang, Dong; Li, Xiao-Hua

    2017-08-01

    In the present work, the unfavored α -decay half-lives and α preformation probabilities of closed-shell nuclei related to ground and isomeric states around Z =82 , N =82 and 126 shell closures are investigated by adopting the two-potential approach from the perspective of valence nucleon (hole) and isospin asymmetry of the parent nucleus. The results indicate that α preformation probability has linear dependence on NpNn or NpNnI , the same as the case of favored α decay in our previous work [X.-D. Sun et al., Phys. Rev. C 94, 024338 (2016), 10.1103/PhysRevC.94.024338]. Np, Nn, and I represent the number of valence protons (holes), the number of valence neutrons (holes), and the isospin of the parent nucleus, respectively. Fitting the α preformation probability data extracted from the differences between experimental data and calculated half-lives without a shell correction, we give two linear formulas of the α preformation probabilities and the values of corresponding parameters. Based on the formulas and corresponding parameters, we calculate the α -decay half-lives for those nuclei. The calculated results can well reproduce the experimental data.

  13. Analytical potential for the elastic scattering of light halo nuclei below and close to the Coulomb barrier

    SciTech Connect

    Borowska, L.; Terenetsky, K.; Verbitsky, V.; Fritzsche, S.

    2009-04-15

    An analytical expression for the dynamic polarization potential is derived for the elastic scattering of light halo nuclei in the Coulomb field of heavy targets. The derivation is based on the adiabatic motion of the projectile below and close to the Coulomb barrier together with a uniform approximation for the Coulomb functions. Detailed computations have been carried out for the elastic scattering of d+{sup 208}Pb and {sup 6}He+{sup 208}Pb at collision energies of 8 and 17.8 MeV and are compared with measurements as far as available. The obtained expression for the dynamic polarization potential is simple and can be applied for any arbitrary system with a dineutron configuration.

  14. Twins born in different environments? Nuclei of two dSphs: isolated galaxy KKS3 and E269-66, a close neighbor of NGC5128

    NASA Astrophysics Data System (ADS)

    Sharina, Margarita; Kniazev, Alexei; Karachentsev, Igor

    2017-03-01

    We present the results of age, metallicity and radial velocity determination for central massive globular clusters (GCs) in dwarf spheroidal galaxies: KKs3 and ESO269-66. KKS3 is a unique isolated galaxy. ESO269-66 is a close neighbor of the giant S0 Centaurus A. The results contribute to the knowledge about the origin of massive star clusters and their host dSphs. The structure and star formation histories of the two dwarf galaxies look rather similar. Both of them have experienced several star-forming events. The most recent ones occurred 1-2 Gyr ago, and most powerful bursts happened 12-14 Gyrs ago. Our analysis has shown that both GCs appear to be 1-2 Gyr younger and 0.1-0.3 dex more metal-rich than the most ancient metal-poor stars in the host dSphs. We examine signatures of multiple stellar population in the GCs using our data. Since central star-forming bursts were extended in time, the massive clusters might be considered as nuclei of the galaxies.

  15. Pygmy dipole response of proton-rich argon nuclei in random-phase approximation and no-core shell model

    SciTech Connect

    Barbieri, C.; Martinez-Pinedo, G.; Caurier, E.; Langanke, K.

    2008-02-15

    The occurrence of a pygmy dipole resonance in proton rich {sup 32,34}Ar is studied using the unitary correlator operator method interaction V{sub UCOM}, based on Argonne V18. Predictions from the random-phase approximation (RPA) and the shell model in a no-core basis are compared. It is found that the inclusion of configuration mixing up to two-particles-two-holes broadens the pygmy strength slightly and reduces sensibly its strength, as compared to the RPA predictions. For {sup 32}Ar, a clear peak associated with a pygmy resonance is found. For {sup 34}Ar, the pygmy states are obtained close to the giant dipole resonance and mix with it.

  16. Helminth parasitism in two closely related South African rodents: abundance, prevalence, species richness and impinging factors.

    PubMed

    Spickett, Andrea; Junker, Kerstin; Krasnov, Boris R; Haukisalmi, Voitto; Matthee, Sonja

    2017-04-01

    We investigated patterns of helminth infection in two closely related rodents (social Rhabdomys pumilio occurring mainly in xeric habitats and solitary R. dilectus occurring mainly in mesic habitats) at 20 localities in different biomes of South Africa and asked if between-species differences were mainly caused by difference in sociality or difference in environmental conditions of their respective habitats. Helminths recovered from the gastrointestinal tract totalled 11 nematode and 5 cestode species from R. pumilio and 19 nematode and 7 cestode species from R. dilectus. In both hosts, mean abundance and prevalence of nematodes were higher compared to cestodes. Cestode infection as well as nematode abundance, species richness or prevalence did not differ between the two rodents. However, incidence of nematode infection was significantly higher in R. dilectus than in R. pumilio. Moreover, nematode numbers and species richness in infracommunities of R. pumilio inhabiting the relatively more xeric Karoo biome were significantly lower than in those inhabiting the relatively less xeric Fynbos biome. Although we could not unequivocally distinguish between effects of host sociality and environmental factors on the number of individuals and species of helminths in the two hosts, differences in the incidence of nematode infection between R. pumilio and R. dilectus as well as differences in the number of nematode individuals and species between R. pumilio from the Fynbos and the Karoo suggested the effect of environmental conditions on helminth infection to be more important than that of sociality.

  17. Twins born in different environments? Nuclei of two dSphs: isolated galaxy KKS3 and ESO269-66, a close neighbor of NGC5128

    NASA Astrophysics Data System (ADS)

    Sharina, Margarita; Karachentsev, Igor; Kniazev, Alexei

    2015-08-01

    The close vicinity of giant neighbors determines the environmental mechanisms that have been considered responsible for the evolution of dwarf spheroidal galaxies (dSphs). In the recent years, Karachentsev and collaborators have reported on the discovery of a few truly isolated dSphs in the Local volume. This study focuses on one of these unusual objects, KKs3 (MV=-12.3 mag). It contains a massive globular cluster (GC) (MV=-8.5 mag) near its optical center. We have performed the estimation of its radial velocity using a medium-resolution spectrum obtained with the RSS spectrograph at the Southern African Large Telescope (SALT). The signal-to-noise ratio in the spectrum was sufficient to estimate the age and metallicity for the GC using simple stellar population models, and the methods of full spectrum fitting and Lick index diagnostic diagrams. The results contribute to the knowledge about the origin of massive star clusters and their host dSphs.In the same way we have analyzed another luminous GC (MV=-10) in the center of ESO269-66 (MB=-15.4), a close dSph neighbor of the giant S0 Cen A. The cluster was observed with SALT in the same instrumental configuration. The structure and star formation histories of the two galaxies look rather similar. Both of them have experienced several star-forming events. The most recent ones occurred 1÷2 Gyr ago, and most powerful bursts happened 12÷14 Gyrs ago. Our analysis has shown that both GCs appear to be 1÷2 Gyr younger and 0.2÷0.3 dex more metal-rich than the most ancient metal-poor stars in the host dSphs. We examine signatures of multiple stellar population in the GCs using out data. Since central star-forming bursts were extended in time, the massive clusters might be considered as nuclei of the galaxies.

  18. The RNB project in Japanese Hadron Facility and possible use of neutron-rich beam for the study of superheavy nuclei

    SciTech Connect

    Nomura, Toru

    1998-02-15

    We first describe briefly a radioactive nuclear beam (RNB) facility based on the isotope separator on-line and post-accelerator scheme planned in Japanese Hadron Project. In this facility, various radioactive nuclear species produced in 3 GeV proton-induced reactions will be accelerated through heavy-ion linacs in three stages, the maximum output energy in each stage being 0.17, 1.05 and 6.5 meV/nucleon, respectively. Secondly, we discuss the feasibility of the use of neutron-rich RNB for experimental study of more neutron-rich superheavy nuclei than those presently known. It is shown that the increase of the survival probability of neutron-rich compound nuclei can possibly compensate for a difficulty arising from expected weak intensities of the secondary-beams. In addition, cold-fusion-like reactions as well as possible enhancement of near-barrier fusion cross sections that can become more prominent by use of neutron-rich beams are discussed.

  19. Production and Beta Half Lives of Nuclei Close TI the Nucleosynthesis R-Process Path at N=126

    SciTech Connect

    Benlliure, J.; Caamano, M.; Casarejos, E.; Cortina, D.; Kurtukian, T.; Ordonez, M. F.; Pereira, J.; Becker, F.; Henzlova, D.; Jurado, B.; Schmidt, K. H.; Yordanov, O.; Audouin, L.; Rejmund, F.

    2007-05-22

    Cold-fragmentation reactions of 208Pb projectiles impinging a beryllium target at 1 A GeV have been used to produce more than 190 nuclei ''south'' of lead, 25 of them for the first time. The beta half lives or upper limits of 13 of these new nuclei have been determined using position and time correlations between the nuclei and the betas in an active stopper. The measured half lives can only be described when first forbidden transitions are considered.

  20. 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.

  1. Pygmy dipole mode in deformed neutron-rich Mg isotopes close to the drip line

    NASA Astrophysics Data System (ADS)

    Yoshida, Kenichi

    2009-10-01

    We investigate the microscopic structure of the low-lying isovector-dipole excitation mode in neutron-rich Mg36,38,40 close to the drip line by means of the deformed quasiparticle random-phase approximation employing the Skyrme and the local pairing energy-density functionals. It is found that the low-lying bump structure above the neutron emission-threshold energy develops when the drip line is approached, and that the isovector dipole strength at Ex<10 MeV exhausts about 6.0% of the classical Thomas-Reiche-Kuhn dipole sum rule in Mg40. We obtained the collective dipole modes at around 8-10 MeV in Mg isotopes, that consist of many two-quasiparticle excitations of the neutron. The transition density clearly shows an oscillation of the neutron skin against the isoscalar core. We found significant coupling effects between the dipole and octupole excitation modes due to the nuclear deformation. It is also found that the responses for the compressional dipole and isoscalar octupole excitations are much enhanced in the lower energy region.

  2. Conversion electron spectroscopy at the FMA focal plane: Decay studies of proton-rich N {approximately} 82 nuclei

    SciTech Connect

    Nisius, D.; Janssens, R.V.F.; Ahmad, I.

    1995-08-01

    The FMA has proven to be an ideal instrument for the detailed study of the decay of microsecond isomers behind the focal plane following mass selection. In reactions leading to the population of nuclei with isomeric lifetimes longer than their flight time through the device, decay gamma rays and conversion electrons can be detected in an environment free from the backgrounds of prompt radiation and delta electrons. This was a very successful technique to study proton (h{sub 11/2}){sup n} seniority isomers in nuclei with Z > 64 and N {approximately} 82. Since isomeric decay gamma rays are emitted isotropically, conversion electrons are essential for the assignment of multipolarities in these nuclei. Furthermore, the low-energy transitions that depopulate isomeric states are typically highly converted and can escape gamma-ray detection, but they can be identified by their conversion electrons.

  3. Description of nuclear octupole and quadrupole deformation close to axial symmetry: Octupole vibrations in the X(5) nuclei Nd150 and Sm152

    NASA Astrophysics Data System (ADS)

    Bizzeti, P. G.; Bizzeti-Sona, A. M.

    2010-03-01

    The model, introduced in a previous paper, for the description of the octupole and quadrupole degrees of freedom in conditions close to the axial symmetry is used to describe the negative-parity band based on the first octupole vibrational state in nuclei close to the critical point of the U(5)-to-SU(3) phase transition. The situation of Nd150 and Sm152 is discussed in detail. The positive-parity levels of these nuclei, and also the in-band E2 transitions, are reasonably accounted for by the X(5) model. With simple assumptions on the nature of the octupole vibrations, it is also possible to describe the negative-parity sector with comparable accuracy without changing the description of the positive-parity part.

  4. Gamow-teller strengths in proton-rich exotic nuclei deduced in the combined analysis of mirror transitions.

    PubMed

    Fujita, Y; Adachi, T; von Brentano, P; Berg, G P A; Fransen, C; De Frenne, D; Fujita, H; Fujita, K; Hatanaka, K; Jacobs, E; Nakanishi, K; Negret, A; Pietralla, N; Popescu, L; Rubio, B; Sakemi, Y; Shimbara, Y; Shimizu, Y; Tameshige, Y; Tamii, A; Yosoi, M; Zell, K O

    2005-11-18

    Isospin symmetry is expected for the T(z)=+/-1-->0 isobaric analogous transitions in isobars with mass number A, where T(z) is the z component of isospin T. Assuming this symmetry, strengths of analogous Gamow-Teller (GT) transitions within A = 50 isobars were determined from a high energy-resolution study at 0 degrees in combination with the decay Q value and lifetime from the beta decay. This method can be applied to other pf-shell nuclei and can be used to study GT strengths of astrophysical interest.

  5. Neutron Transfer Reactions on Neutron-Rich N=50 and N=82 Nuclei Near the r-Process Path

    SciTech Connect

    Cizewski, J. A.; Jones, K. L.; Kozub, R. L.; Pain, S. D.; Thomas, J. S.; Arbanas, Goran; Adekola, Aderemi S; Bardayan, Daniel W; Blackmon, Jeff C; Chae, K. Y.; Chipps, K.; Dean, David Jarvis; Erikson, Luke; Gaddis, A. L.; Harlin, Christopher W; Hatarik, Robert; Howard, Joshua A; Johnson, Micah; Kapler, R.; Krolas, W.; Liang, J Felix; Livesay, Jake; Ma, Zhanwen; Matei, Catalin; Moazen, Brian; Nesaraja, Caroline D; O'Malley, Patrick; Paulauskas, Stanley V; Shapira, Dan; ShrinerJr., J. F.; Sissom, D. J.; Smith, Michael Scott; Swan, T. P.; Wilson, Gemma L

    2009-01-01

    Neutron transfer (d,p) reaction studies on the N = 50 isotones, 82Ge and 84Se, and A{approx}130 nuclei, 130,132Sn and 134Te, have been measured. Direct neutron capture cross sections for 82Ge and 84Se (n,?) have been calculated and are combined with Hauser-Feshbach expectations to estimate total (n,?) cross sections. The A{approx}130 studies used an early implementation of the ORRUBA array of position-sensitive silicon strip detectors for reaction proton measurements. Preliminary excitation energy and angular distribution results from the A{approx}130 measurements are reported.

  6. Study of cluster structures in 10Be and 16C neutron-rich nuclei via break-up reactions

    NASA Astrophysics Data System (ADS)

    Dell'Aquila, D.; Acosta, L.; Amorini, F.; Andolina, R.; Auditore, L.; Berceanu, I.; Cardella, G.; Chatterjiee, M. B.; De Filippo, E.; Francalanza, L.; Gnoffo, B.; Grzeszczuk, A.; Lanzalone, G.; Lombardo, I.; Martorana, N.; Minniti, T.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Pop, A.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

    2016-05-01

    Projectile break-up reactions induced on polyethylene (CH2) target are used in order to study the spectroscopy of 10Be and 16C nuclei. For the present experiment we used 10Be and 16C beams delivered by the FRIBs facility at INFN-LNS, and the CHIMERA 4π multi-detector. 10Be and 16C structures are studied via a relative energy analysis of break-up fragments. The 4He+6He break-up channel allowed us to study the spectroscopy of 10Be; in particular we find evidence of a new state in 10Be at 13.5 MeV excitation energy. The 16C nucleus is studied via 6He-10Be correlation; we find the fingerprint of a possible state at about 20.6 MeV

  7. Gamow-Teller Strengths in Proton-Rich Exotic Nuclei Deduced in the Combined Analysis of Mirror Transitions

    SciTech Connect

    Fujita, Y.; Adachi, T.; Fujita, H.; Shimbara, Y.; Brentano, P. von; Fransen, C.; Pietralla, N.; Zell, K.O.; Berg, G.P.A.; Frenne, D. de; Jacobs, E.; Negret, A.; Popescu, L.; Fujita, K.; Hatanaka, K.; Nakanishi, K.; Sakemi, Y.; Shimizu, Y.; Tameshige, Y.; Tamii, A.

    2005-11-18

    Isospin symmetry is expected for the T{sub z}={+-}1{yields}0 isobaric analogous transitions in isobars with mass number A, where T{sub z} is the z component of isospin T. Assuming this symmetry, strengths of analogous Gamow-Teller (GT) transitions within A=50 isobars were determined from a high energy-resolution T{sub z}=+1{yields}0, {sup 50}Cr({sup 3}He,t){sup 50}Mn study at 0 deg. in combination with the decay Q value and lifetime from the T{sub z}=-1{yields}0, {sup 50}Fe{yields}{sup 50}Mn {beta} decay. This method can be applied to other pf-shell nuclei and can be used to study GT strengths of astrophysical interest.

  8. Crossover from skin mode to proton-neutron mode in E1 excitations of neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

    Nakada, H.; Inakura, T.; Sawai, H.

    2013-03-01

    The character of the low-energy E1 excitations is investigated by analyzing transition densities obtained from the RPA calculations in the doubly magic nuclei. We propose a decomposition method of the E1 excitations into the pn mode (i.e., oscillation between protons and neutrons) and the skin mode (i.e., oscillation of the neutron skin against the inner core) via the transition densities, by which their mixing is handled in a straightforward manner. Crossover behavior of the E1 excitations is found, from the skin mode at low energy to the pn mode at higher energy. The ratio of the skin-mode strength to the full strength turns out to be insensitive to the nuclides and to the effective interactions in the energy region of the crossover. Depending on the excitation energy, the observed low-energy E1 excitations are not necessarily dominated by the skin mode, as exemplified for 90Zr.

  9. Shell-model Monte Carlo studies of neutron-rich nuclei in the 1s-0d-1p-0f shells

    NASA Astrophysics Data System (ADS)

    Dean, D. J.; Ressell, M. T.; Hjorth-Jensen, M.; Koonin, S. E.; Langanke, K.; Zuker, A. P.

    1999-05-01

    We demonstrate the feasibility of realistic shell-model Monte Carlo (SMMC) calculations spanning multiple major shells, using a realistic interaction whose bad saturation and shell properties have been corrected by a newly developed general prescription. Particular attention is paid to the approximate restoration of translational invariance. The model space consists of the full sd-pf shells. We include in the study some well-known T=0 nuclei and several unstable neutron-rich ones around N=20,28. The results indicate that SMMC calculations can reproduce binding energies, B(E2) transitions, and other observables with an interaction that is practically parameter free. Some interesting insight is gained into the nature of deep correlations. The validity of previous studies is confirmed.

  10. Ultraviolet observations of close-binary and pulsating nuclei of planetary nebulae; Winds and shells around low-mass supergiants; The close-binary nucleus of the planetary nebula HFG-1; A search for binary nuclei of planetary nebulae; UV monitoring of irregularly variable planetary nuclei; and The pulsating nucleus of the planetary nebula Lo 4

    NASA Technical Reports Server (NTRS)

    Bond, Howard E.

    1992-01-01

    A brief summary of the research highlights is presented. The topics covered include the following: binary nuclei of planetary nebulae; other variable planetary nuclei; low-mass supergiants; and other IUE-related research.

  11. High-spin isomers in neutron-rich nuclei studied with the TARDIS-array at IGISOL

    NASA Astrophysics Data System (ADS)

    Lhersonneau, G.; Butler, P. A.; Cocks, J. F. C.; Honkanen, A.; Huhta, M.; Jones, P. M.; Jokinen, A.; Julin, R.; Juutinen, S.; Lampinen, A.; Müller, D.; Mäkelä, E.; Oinonen, M.; Parmonen, J. M.; Piiparinen, M.; Savelius, A.; Smith, J. F.; Törmänen, S.; Virtanen, A.; Äystö, J.

    1996-02-01

    A 12 Compton-suppressed detector array TARDIS has been placed around the collection spot of the IGISOL separator, with the aim of studying decays of high-spin isomers in neutron-rich isotopes produced by fission. An experiment on 97Y shows that the detection limit is improved by more than one order of magnitude with respect to previous measurements at research reactors with conventional detector setups.

  12. Stellar (n ,γ ) cross sections of neutron-rich nuclei: Completing the isotope chains of Yb, Os, Pt, and Hg

    NASA Astrophysics Data System (ADS)

    Marganiec, J.; Dillmann, I.; Domingo-Pardo, C.; Käppeler, F.

    2014-12-01

    The (n ,γ ) cross sections of the most neutron-rich stable isotopes of Yb, Os, Pt, and Hg have been determined in a series of activation measurements at the Karlsruhe 3.7 MV Van de Graaff accelerator, using the quasistellar neutron spectrum for k T =25 keV that can be produced with the 7Li(p ,n ) 7Be reaction. In this way, Maxwellian averaged cross sections could be directly obtained with only minor corrections. After irradiation the induced activities were counted with a HPGe detector via the strongest γ -ray lines. The stellar neutron capture cross sections of Yb,176174, Os,192190, Pt,198196, and Hg,204202, extrapolated to k T =30 keV, were found to be 157 ±6 mb, 114 ±8 mb, 278 ±11 mb, 160 ±7 mb, 171 ±19 mb, 94 ±4 mb, 62 ±2 mb, and 32 ±15 mb, respectively. In the case of 196Pt the partial cross section to the isomeric state at 399.5 keV could be determined as well. With these results the cross section data for long isotopic chains could be completed for a discussion of the predictive power of statistical model calculations towards the neutron-rich and proton-rich sides of the stability valley.

  13. 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.

  14. Beta Decay of the Proton-Rich Nuclei 102Sn and 104Sn

    SciTech Connect

    Karny, M.; Batist, L.; Banu, A.; Becker, F.; Blazhev, A.; Brown, B. A.; Bruchle, W.; Doring, J.; Faestermann, T.; Gorska, M.; Grawe, H.; Janas, Z.; Jungclaus, A.; Kavatsyuk, M.; Kavatsyuk, O.; Kirchner, R.; La Commara, M.; Mandal, S.; Mazzocchi, C.; Miernik, K.; Mukha, I.; Muralithar, S.; Plettner, C.; Plochocki, A.; Roeckl, E.; Romoli, M.; Rykaczewski, Krzysztof Piotr; Schadel, M.; Schmidt, K.; Schwengner, R.; Zylicz, J.

    2006-01-01

    The {beta} decays of {sup 102}Sn and {sup 104}Sn were studied by using high-resolution germanium detectors as well as a Total Absorption Spectrometer (TAS). For {sup 104}Sn, with three new {beta}-delayed {gamma}-rays identified, the total Gamow-Teller strength (BGT) value of 2.7(3) was obtained. For {sup 102}Sn, the {gamma}-{gamma} coincidence data were collected for the first time, allowing us to considerably extend the decay scheme. This scheme was used to unfold the TAS data and to deduce a BGT value of 4.2(8) for this decay. This result is compared to shell model predictions, yielding a hindrance factor of 3.6(7) in agreement with those obtained previously for {sup 98}Cd and {sup 100}In. Together with the latter two, {sup 102}Sn completes the triplet of Z {le} 50, N {ge} 50 nuclei with two proton holes, one proton hole and one neutron particle, and two neutron particles with respect to the doubly magic {sup 100}Sn core.

  15. Closing regulatory gaps: new ground rules for platelet-rich plasma.

    PubMed

    Anitua, Eduardo; Prado, Roberto; Orive, Gorka

    2015-09-01

    The Spanish Agency of Medicines and Medical Devices (AEMPS) has drawn up a comprehensive report and resolution that regulates for the first time the use of platelet-rich plasma (PRP) as a human-use medicinal product. This regulatory framework offers emerging challenges to adapt the use of PRP to the new requirements of safety and efficacy. The heterogeneity of the different products can hinder their regulation, which today differs substantially in the different worldwide regulatory frameworks. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Distinction between elastic scattering of weakly bound proton- and neutron-rich nuclei: The case of 8B and 11Be

    NASA Astrophysics Data System (ADS)

    Yang, Y. Y.; Liu, X.; Pang, D. Y.

    2016-09-01

    Experimental data show that the elastic scattering cross sections of the neutron-rich nucleus 11Be are greatly reduced by the coupling effects from the breakup channels, while those of the proton-rich nucleus 8B are not. Such difference is found to persist in results of systematic calculations of 8B elastic scattering from 208Pb at 60 and 170.3 MeV and from 64Zn at 32 and 86 MeV, and 11Be elastic scattering from 208Pb at 55 and 143 MeV and from 64Zn at 29 and 66 MeV with the continuum-discretized coupled channel (CDCC) method. The Coulomb and centrifugal barriers experienced by the valence proton in the ground state of 8B, which do not exist for the valence neutron in the ground state of 11Be, are found to be the reason for such differences in the angular distributions of elastic scattering cross sections of these two weakly bound nuclei.

  17. Yield ratios and directed flows of light fragments from reactions induced by neutron-rich nuclei at intermediate energy

    NASA Astrophysics Data System (ADS)

    Yan, Ting-Zhi; Li, Long-Long; Wang, Rui-Feng; Yan, Ting-Feng

    2017-04-01

    The yield ratios of neutron/proton and 3H/3He and the directed flow per nucleon for these projectile-like fragments at large impact parameters are studied for 50Ca + 40Ca and 50Cr + 40Ca for comparison at 50 MeV/u using the isospin-dependent quantum molecular dynamics (IQMD) model. It is found that the yield ratios and the directed flows per nucleon are different for reactions induced by the neutron-rich nucleus 50Ca and the stable isobaric nucleus 50Cr, and depend on the hardness of the EOS. The ratios of neutron/proton and 3H/3He and the difference of directed flow per nucleon of neutron-proton are suggested to be possible observables to investigate the isospin effects. Supported by National Natural Science Foundation of China (11405025)

  18. Spherical nuclei near the stability line and far from it

    NASA Astrophysics Data System (ADS)

    Isakov, V. I.

    2016-11-01

    Results of microscopic and semiphenomenological calculations of features of spherical nuclei lying near the stability line and far from it are presented. The reason why the nuclei being considered are spherical is that they are magic at least in one nucleon sort. The present analysis is performed for Z = 50 and Z = 28 isotopes and for N = 50 isotones, the region extending from neutron-rich to neutron-deficient nuclei being covered. The isotopic dependence of the mean-field spin-orbit nuclear potential is revealed; systematics of energies of levels and probabilities for electromagnetic transitions is examined; and root-mean-square radii of nuclei are calculated, along with the proton- and neutron-density distributions in them. Nuclei in the vicinity of closed shells are considered in detail, and the axial-vector weak coupling constant in nuclei is evaluated. A systematic comparison of the results of calculations with experimental data is performed.

  19. Spherical nuclei near the stability line and far from it

    SciTech Connect

    Isakov, V. I.

    2016-11-15

    Results of microscopic and semiphenomenological calculations of features of spherical nuclei lying near the stability line and far from it are presented. The reason why the nuclei being considered are spherical is that they are magic at least in one nucleon sort. The present analysis is performed for Z = 50 and Z = 28 isotopes and for N = 50 isotones, the region extending from neutron-rich to neutron-deficient nuclei being covered. The isotopic dependence of the mean-field spin–orbit nuclear potential is revealed; systematics of energies of levels and probabilities for electromagnetic transitions is examined; and root-mean-square radii of nuclei are calculated, along with the proton- and neutron-density distributions in them. Nuclei in the vicinity of closed shells are considered in detail, and the axial-vector weak coupling constant in nuclei is evaluated. A systematic comparison of the results of calculations with experimental data is performed.

  20. Performance of a total absorption clover detector for Qβ measurements of neutron-rich nuclei far from the β-stability line

    NASA Astrophysics Data System (ADS)

    Hayashi, H.; Shibata, M.; Asai, M.; Osa, A.; Sato, T. K.; Koizumi, M.; Kimura, A.; Oshima, M.

    2014-05-01

    To measure β-decay energies (Qβs) of neutron-rich nuclei far from the β-stability line, we have improved upon the previously described total absorption detector, composed of a clover Ge detector (80 mmϕ×90 mmL×4 crystals) and 4π BGO Compton suppressors. This detector can directly determine the Qβ from the end-point of the measured spectrum. Nuclei of interest such as new isotopes have Qβ values over 4 MeV; therefore, high detection efficiencies are needed. This total absorption detector has a through-hole (alongside its vertical axis) at the center of the four Ge crystals, and the radioactive sources can be placed in this hole to measure the total absorption spectrum. The β- and γ-rays are absorbed by the detector with almost 4π geometry while escaping radiations from the Ge detector can be detected by the 4π BGO Compton suppressors. We also developed a practical analytic procedure based on the folding method, in which response functions of γ- and β-rays were considered with an assumed decay scheme. The systematic uncertainty of the deduced Qβs was evaluated to be ±30 keV using 18 fission products whose Qβ values were precisely measured. With the detector and an on-line mass separator, we have determined the Qβ values of 166Eu and 165Gd for the first time, and have proposed more precise Qβ values for 160-165Eu and 163Gd than previously found. Owing to the especially good energy resolution of the detector, the isomeric state in 163Gd was also successfully observed for the first time through end-point analysis and analysis of the observed γ-rays. This result contributes to the determination of reliable Qβ values for 163Gd and 163Eu.

  1. Delayed triggering of radio active galactic nuclei in gas-rich minor mergers in the local Universe

    NASA Astrophysics Data System (ADS)

    Shabala, S. S.; Deller, A.; Kaviraj, S.; Middelberg, E.; Turner, R. J.; Ting, Y. S.; Allison, J. R.; Davis, T. A.

    2017-02-01

    We examine the processes triggering star formation and active galactic nucleus (AGN) activity in a sample of 25 low-redshift (z < 0.13) gas-rich galaxy mergers observed at milliarcsecond resolution with Very Long Baseline Interferometry (VLBI) as part of the mJy Imaging VLBA Exploration at 20 cm (mJIVE-20) survey. The high (>107 K) brightness temperature required for an mJIVE-20 detection allows us to unambiguously identify the radio AGN in our sample. We find three such objects. Our VLBI AGN identifications are classified as Seyferts or low-ionization nuclear emission-line regions (LINERs) in narrow line optical diagnostic plots; mid-infrared colours of our targets and the comparison of Hα star formation rates with integrated radio luminosity are also consistent with the VLBI identifications. We reconstruct star formation histories in our galaxies using optical and UV photometry, and find that these radio AGN are not triggered promptly in the merger process, consistent with previous findings for non-VLBI samples of radio AGN. This delay can significantly limit the efficiency of feedback by radio AGN triggered in galaxy mergers. We find that radio AGN hosts have lower star formation rates than non-AGN radio-selected galaxies at the same starburst age. Conventional and VLBI radio imaging shows these AGN to be compact on arcsecond scales. Our modelling suggests that the actual sizes of AGN-inflated radio lobes may be much larger than this, but these are too faint to be detected in existing observations. Deep radio imaging is required to map out the true extent of the AGN, and to determine whether the low star formation rates in radio AGN hosts are a result of the special conditions required for radio jet triggering, or the effect of AGN feedback.

  2. B(E2)↑ Measurements for Radioactive Neutron-Rich Ge Isotopes: Reaching the N=50 Closed Shell

    NASA Astrophysics Data System (ADS)

    Padilla-Rodal, E.; Galindo-Uribarri, A.; Baktash, C.; Batchelder, J. C.; Beene, J. R.; Bijker, R.; Brown, B. A.; Castaños, O.; Fuentes, B.; del Campo, J. Gomez; Hausladen, P. A.; Larochelle, Y.; Lisetskiy, A. F.; Mueller, P. E.; Radford, D. C.; Stracener, D. W.; Urrego, J. P.; Varner, R. L.; Yu, C.-H.

    2005-03-01

    The B(E2;0+1→2+1) values for the radioactive neutron-rich germanium isotopes 78,80Ge and the closed neutron shell nucleus 82Ge were measured at the HRIBF using Coulomb excitation in inverse kinematics. These data allow a study of the systematic trend between the subshell closures at N=40 and 50. The B(E2) behavior approaching N=50 is similar to the trend observed for heavier isotopic chains. A comparison of the experimental results with a shell model calculation demonstrates persistence of the N=50 shell gap and a strong sensitivity of the B(E2) values to the effective interaction.

  3. The new neutron rich nuclei

    SciTech Connect

    Gridnev, K. A.; Gridnev, D. K.; Tarasov, V. N.; Tarasov, D. V.; Viñas, X.; Greiner, W.

    2014-07-23

    Using HF+BCS method with Skyrme forces we analyze the neutron drip line. It is shown that around magic and new magic numbers the drip line may form stability peninsulas. It is shown that the location of these peninsulas does not depend on the choice of Skyrme forces. It is found that the size of the peninsulas is sensitive to the choice of Skyrme forces and the most extended peninsulas appear with the SkI2 set.

  4. Fast convergence of learning requires plasticity between inferior olive and deep cerebellar nuclei in a manipulation task: a closed-loop robotic simulation

    PubMed Central

    Luque, Niceto R.; Garrido, Jesús A.; Carrillo, Richard R.; D'Angelo, Egidio; Ros, Eduardo

    2014-01-01

    The cerebellum is known to play a critical role in learning relevant patterns of activity for adaptive motor control, but the underlying network mechanisms are only partly understood. The classical long-term synaptic plasticity between parallel fibers (PFs) and Purkinje cells (PCs), which is driven by the inferior olive (IO), can only account for limited aspects of learning. Recently, the role of additional forms of plasticity in the granular layer, molecular layer and deep cerebellar nuclei (DCN) has been considered. In particular, learning at DCN synapses allows for generalization, but convergence to a stable state requires hundreds of repetitions. In this paper we have explored the putative role of the IO-DCN connection by endowing it with adaptable weights and exploring its implications in a closed-loop robotic manipulation task. Our results show that IO-DCN plasticity accelerates convergence of learning by up to two orders of magnitude without conflicting with the generalization properties conferred by DCN plasticity. Thus, this model suggests that multiple distributed learning mechanisms provide a key for explaining the complex properties of procedural learning and open up new experimental questions for synaptic plasticity in the cerebellar network. PMID:25177290

  5. Mineralogical and geochemical investigation of clay-rich mine tailings from a closed phosphate mine, Bartow Florida, USA

    NASA Astrophysics Data System (ADS)

    Krekeler, Mark P. S.; Morton, Julie; Lepp, Jill; Tselepis, Cynthia M.; Samsonov, Mikhail; Kearns, Lance E.

    2008-07-01

    Clay-rich mine tailings from phosphate mine operations in Florida are a major environmental and economic problem. Options for reclamation and restoration for these tailings are very limited and are fundamentally restricted by poor physical properties such as low mechanical strength, low hydraulic conductivity, and heavy metal content. The major control on these bulk physical properties is the mineralogy of the materials. Eight continuous push borings were obtained to investigate stratigraphy, mineralogy, aspects of geochemistry, and bulk properties of a deposit of clay-rich mine tailings from a phosphate mine near Bartow, Florida that ceased operations in the early 1970s. Stratigraphy is dominated by laminated clay-rich sediment with minor units of silt and sand. An intact kaolinite liner occurs near the impoundment walls and the impoundment floor has approximately 4 m of relief. Moisture content varies from 4.35 to 57.40 wt% and organic content varies from 0.41 to 9.53 wt%. Bulk XRF investigation indicates that the P2O5 concentrations vary from approximately 4 to 21 wt%. A very strong correlation ( r 2 = 0.92) between CaO and P2O5 indicates that apatite is a major control on the phosphate. The strong correlation ( r 2 = 0.77) of Al2O3 and TiO2 suggests that the source materials for this deposit are comparatively uniform. A number of heavy metal elements and trace elements occur. Cr, V, Ni, Cu are interpreted to be in phosphate minerals, largely apatite. Sr and Pb are interpreted to be in both phyllosilicates and phosphate minerals. Two populations of apatite were observed in the clay-sized fraction, one that was Fe and Si- bearing and another that was only Si-bearing. Fe-bearing apatite had Fe2O3 contents that varied from 0.38 to 5.32 wt% and SiO2 contents that varied from 0.90 to 3.32 wt%. The other apatite population had a wider range of SiO2 contents that varied from 0.77 to 8.80 wt%. TEM imaging shows that apatite grains are dominantly single crystals with

  6. Half-life determination of Tz = -1 and Tz = - {{1}/{2}} proton-rich nuclei and the β decay of 58Zn

    NASA Astrophysics Data System (ADS)

    Kucuk, L.; Orrigo, S. E. A.; Montaner-Pizá, A.; Rubio, B.; Fujita, Y.; Gelletly, W.; Blank, B.; Oktem, Y.; Adachi, T.; Algora, A.; Ascher, P.; Cakirli, R. B.; de France, G.; Fujita, H.; Ganioğlu, E.; Giovinazzo, J.; Grévy, S.; Marqués, F. M.; Molina, F.; de Oliveira Santos, F.; Perrot, L.; Raabe, R.; Srivastava, P. C.; Susoy, G.; Tamii, A.; Thomas, J. C.

    2017-06-01

    We have measured the β -decay half-lives of 16 neutron-deficient nuclei with Tz = -1/2 and -1 , ranging from chromium to germanium. They were produced in an experiment carried out at GANIL and optimized for the production of 58Zn , for which in addition we present the decay scheme and absolute Fermi and Gamow-Teller transition strengths. Since all of these nuclei lie on the rp -process pathway, the T_{1/2} values are important ingredients for the rp -process reaction flow calculations and for models of X-ray bursters.

  7. Spectroscopy of neutron-rich {sup 168,170}Dy: Yrast band evolution close to the N{sub p}N{sub n} valence maximum

    SciTech Connect

    Soederstroem, P.-A.; Nyberg, J.; Regan, P. H.; Ashley, S. F.; Catford, W. N.; Gelletly, W.; Jones, G. A.; Liu, Z.; Pietri, S.; Podolyak, Zs.; Steer, S. J.; Thompson, N. J.; Williams, S. J.; Algora, A.; Angelis, G. de; Corradi, L.; Fioretto, E.; Gottardo, A.; Grodner, E.; He, C. Y.

    2010-03-15

    The yrast sequence of the neutron-rich dysprosium isotope {sup 168}Dy has been studied using multinucleon transfer reactions following collisions between a 460-MeV {sup 82}Se beam and an {sup 170}Er target. The reaction products were identified using the PRISMA magnetic spectrometer and the gamma rays detected using the CLARA HPGe-detector array. The 2{sup +} and 4{sup +} members of the previously measured ground-state rotational band of {sup 168}Dy have been confirmed and the yrast band extended up to 10{sup +}. A tentative candidate for the 4{sup +}->2{sup +} transition in {sup 170}Dy was also identified. The data on these nuclei and on the lighter even-even dysprosium isotopes are interpreted in terms of total Routhian surface calculations and the evolution of collectivity in the vicinity of the proton-neutron valence product maximum is discussed.

  8. Microscopic description of the competition between spontaneous fission and α-decay in neutron-rich Ra, U and Pu nuclei

    NASA Astrophysics Data System (ADS)

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

    2017-06-01

    Constrained mean-field calculations, based on the Gogny-D1M energy density functional, have been carried out to describe fission in Ra, U and Pu nuclei with neutron number 144 ≤ N ≤ 176. Fission paths, collective masses and zero-point quantum vibrational and rotational corrections are used to compute the spontaneous fission half-lives. We also pay attention to isomeric states along the considered fission paths. Alpha decay half-lives have also been computed using a parametrization of the Viola-Seaborg formula. Though there exists a strong variance of the predicted fission rates with respect to the details involved in their computation a robust trend is obtained indicating, that with increasing neutron number fission dominates over α-decay. Our results also suggest that a dynamical treatment of pairing correlations is required within the microscopic studies of the fission process in heavy nuclear systems.

  9. Physics of Unstable Nuclei

    NASA Astrophysics Data System (ADS)

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

    2008-04-01

    Studies at the RIKEN RI beam factory / T. Motobayashi -- Dilute nuclear states / M. Freer -- Studies of exotic systems using transfer reactions at GANIL / D. Beaumel et al. -- First results from the Magnex large-acceptance spectrometer / A. Cunsolo et al. -- The ICHOR project and spin-isospin physics with unstable beams / H. Sakai -- Structure and low-lying states of the [symbol]He exotic nucleus via direct reactions on proton / V. Lapoux et al. -- Shell gap below [symbol]Sn based on the excited states in [symbol]Cd and [symbol]In / M. Górska -- Heavy neutron-rich nuclei produced in the fragmentation of a [symbol]Pb beam / Zs. Podolyák et al. -- Breakup and incomplete fusion in reactions of weakly-bound nuclei / D.J. Hinde et al. -- Excited states of [symbol]B and [symbol]He and their cluster aspect / Y. Kanada-En'yo et al. -- Nuclear reactions with weakly-bound systems: the treatment of the continuum / C. H. Dasso, A. Vitturi -- Dynamic evolution of three-body decaying resonances / A. S. Jensen et al. -- Prerainbow oscillations in [symbol]He scattering from the Hoyle state of [symbol]C and alpha particle condensation / S. Ohkubo, Y. Hirabayashi -- Angular dispersion behavior in heavy ion elastic scattering / Q. Wang et al. -- Microscopic optical potential in relativistic approach / Z.Yu. Ma et al. -- Exotic nuclei studied in direct reactions at low momentum transfer - recent results and future perspectives at fair / P. Egelhof -- Isotopic temperatures and symmetry energy in spectator fragmentation / M. De Napoli et al. -- Multi-channel algebraic scattering theory and the structure of exotic compound nuclei / K. Amos et al. -- Results for the first feasibility study for the EXL project at the experimental storage ring at GSI / N. Kalantar-Nayestanaki et al. -- Coulomb excitation of ISOLDE neutron-rich beams along the Z = 28 chain / P. Van Duppen -- The gamma decay of the pygmy resonance far from stability and the GDR at finite temperature / G. Benzoni et al

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

    NASA Astrophysics Data System (ADS)

    Nayak, R. C.; Pattnaik, S.

    2015-11-01

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

  11. Moment of inertia of even-even proton-rich nuclei using a particle-number conserving approach in the isovector neutron-proton pairing case

    NASA Astrophysics Data System (ADS)

    Hammache, Faiza; Allal, N. H.; Fellah, M.; Oudih, M. R.

    2016-05-01

    An expression of the particle-number projected nuclear moment of inertia (MOI) has been established in the neutron-proton (np) isovector pairing case within the cranking model. It generalizes the one obtained in the like-particles pairing case. The formalism has been, as a first step, applied to the picket-fence model. As a second step, it has been applied to deformed even-even nuclei such as (N - Z) = 0, 2, 4, and of which the experimentally deduced values of the pairing gap parameters Δtt‧, t,t‧ = n,p, are known. The single-particle energies and eigenstates used are those of a deformed Woods-Saxon mean-field. It was shown, in both models, that the np pairing effect and the projection one are non-negligible. In realistic cases, it also appears that the np pairing effect strongly depends on (N - Z), whereas the projection effect is practically independent from the same quantity.

  12. The close binary central star of the planetary nebula Abell 41 - A helium-rich subdwarf primary

    NASA Astrophysics Data System (ADS)

    Green, R. F.; Liebert, J.; Wesemael, F.

    1984-05-01

    He II, He I, and H absorption features were detected in spectroscopy with 2 A resolution of the Abell 41 planetary nebula central star, which was recently reported by Grauer and Bond to be a close binary with a 2 hour 43 minute period. This subdwarf O spectrum has been analyzed with a grid of hot, high-gravity, LTE atmosphere models. T(eff) = 50,000 + or 5000 K, log g = 6 + or - 1, n(He)/n(H) = 10 exp -1.0 + or - 1. This temperature is a factor of 1.4-2.9 lower than the range used by Grauer and Bond, and the required secondary star heating is considerably reduced. Nevertheless, close agreement is found with their estimates for the distance, reddening, and the systemic parameters for the binary star. Their interpretation of Abell 41 as a precataclysmic variable object remains valid for a cool main-sequence or hotter evolved secondary star. The object should be a promising target for high-resolution (coude/echelle) follow-up spectroscopy.

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

    SciTech Connect

    Saxena, G.; Singh, D.

    2013-04-15

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

  14. Petrology and mineralogy of Type II, FeO-rich chondrules in Semarkona (LL3.0) - Origin by closed-system fractional crystallization, with evidence for supercooling

    NASA Technical Reports Server (NTRS)

    Jones, Rhian H.

    1990-01-01

    The petrology of type II porphyritic olivine chondrules in Semarkona (LL3.0) has been studied in detail. Olivines in these chondrules are euhedral, Fe-rich, and are strongly zoned from cores to rims of grains in FeO (Fa10-30), Cr2O3 (0.2-0.6 wt pct), MnO (0.2-0.7 wt pct), and CaO (0.1-0.4 wt pct). Interstitial mesostasis is rich in Si, Al, and Ca and is glassy with abundant microcrystallites. Minor minerals include troilite, Fe,Ni metal, and chromite. Some olivine grains contain euhedral, fayalite-rich cores that are probably produced during initial supercooling of the chondrule melt. Rare relict grains of forsteritic olivine have compositions very similar to olivines in type IA chondrules in Semarkona and may result from disaggregation of such chondrules. Apart from these relics, all properties of type II chondrules can be described by closed-system fractional crystallization of droplets which were essentially entirely molten. Type IA chondrules may have formed from type II chondrules by loss of Fe and volatiles. Alternatively, the two chondrule types may have formed in regions of considerable diversity in the solar nebula from precursor materials with different Fe/Mg ratios.

  15. Petrology and mineralogy of Type II, FeO-rich chondrules in Semarkona (LL3.0) - Origin by closed-system fractional crystallization, with evidence for supercooling

    NASA Technical Reports Server (NTRS)

    Jones, Rhian H.

    1990-01-01

    The petrology of type II porphyritic olivine chondrules in Semarkona (LL3.0) has been studied in detail. Olivines in these chondrules are euhedral, Fe-rich, and are strongly zoned from cores to rims of grains in FeO (Fa10-30), Cr2O3 (0.2-0.6 wt pct), MnO (0.2-0.7 wt pct), and CaO (0.1-0.4 wt pct). Interstitial mesostasis is rich in Si, Al, and Ca and is glassy with abundant microcrystallites. Minor minerals include troilite, Fe,Ni metal, and chromite. Some olivine grains contain euhedral, fayalite-rich cores that are probably produced during initial supercooling of the chondrule melt. Rare relict grains of forsteritic olivine have compositions very similar to olivines in type IA chondrules in Semarkona and may result from disaggregation of such chondrules. Apart from these relics, all properties of type II chondrules can be described by closed-system fractional crystallization of droplets which were essentially entirely molten. Type IA chondrules may have formed from type II chondrules by loss of Fe and volatiles. Alternatively, the two chondrule types may have formed in regions of considerable diversity in the solar nebula from precursor materials with different Fe/Mg ratios.

  16. 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.

  17. In-beam gamma-ray spectroscopy of very neutron-rich nuclei: excited states in 46S and 48Ar.

    PubMed

    Gade, A; Adrich, P; Bazin, D; Brown, B A; Cook, J M; Diget, C Aa; Glasmacher, T; McDaniel, S; Ratkiewicz, A; Siwek, K; Weisshaar, D

    2009-05-08

    We report on the first in-beam gamma-ray spectroscopy study of the very neutron-rich nucleus 46S. The N=30 isotones 46S and 48Ar were produced in a novel way in two steps that both necessarily involve nucleon exchange and neutron pickup reactions 9Be(48Ca,48K)X followed by 9Be(48K,48Ar+gamma)X at 85.7 MeV/u midtarget energy and 9Be(48Ca,46Cl)X followed by 9Be(46Cl,46S+gamma)X at 87.0 MeV/u midtarget energy, respectively. The results are compared to large-scale shell-model calculations in the sd-pf shell using the SDPF-NR effective interaction and Z-dependent modifications.

  18. In-Beam {gamma}-Ray Spectroscopy of Very Neutron-Rich Nuclei: Excited States in {sup 46}S and {sup 48}Ar

    SciTech Connect

    Gade, A.; Brown, B. A.; Cook, J. M.; Glasmacher, T.; McDaniel, S.; Ratkiewicz, A.; Siwek, K.; Adrich, P.; Bazin, D.; Diget, C. A.; Weisshaar, D.

    2009-05-08

    We report on the first in-beam {gamma}-ray spectroscopy study of the very neutron-rich nucleus {sup 46}S. The N=30 isotones {sup 46}S and {sup 48}Ar were produced in a novel way in two steps that both necessarily involve nucleon exchange and neutron pickup reactions {sup 9}Be({sup 48}Ca,{sup 48}K)X followed by {sup 9}Be({sup 48}K,{sup 48}Ar+{gamma})X at 85.7 MeV/u midtarget energy and {sup 9}Be({sup 48}Ca,{sup 46}Cl)X followed by {sup 9}Be({sup 46}Cl,{sup 46}S+{gamma})X at 87.0 MeV/u midtarget energy, respectively. The results are compared to large-scale shell-model calculations in the sd-pf shell using the SDPF-NR effective interaction and Z-dependent modifications.

  19. Dynamic polarization of light halo nuclei in strong fields: {sup 6}He+{sup 209}Bi elastic scattering below and close to the Coulomb barrier

    SciTech Connect

    Borowska, L.; Terenetsky, K.; Verbitsky, V.; Fritzsche, S.

    2007-09-15

    The elastic scattering of light halo nuclei in the field of heavy targets has been studied for collision energies below the Coulomb barrier. Based on the assumption that the neutron halo follows the projectile adiabatically along its classical trajectory, a dynamic polarization potential is derived which describes both the (electrical) polarization as well as the breakup of the projectile in the field of the target. Detailed computations have been carried out for the elastic scattering of {sup 6}He+{sup 209}Bi at energies between 14.7 MeV and 19.1 MeV near to the Coulomb barrier. It is demonstrated that the polarization of the halo nucleus leads to a clear decrease of the (elastic) scattering cross section in excellent agreement with a recent measurement by Aguilera et al. [Phys. Rev. Lett. 84, 5058 (2000)].

  20. Improvements to the on-line mass separator, RAMA, and the beta-delayed charged-particle emission of proton-rich sd shell nuclei

    SciTech Connect

    Ognibene, Theodore Joseph

    1996-03-01

    To overcome the extreme difficulties encountered in the experimental decay studies of proton drip line nuclei, several techniques have been utilized, including a helium-jet transport system, particle identification detectors and mass separation. Improvements to the ion source/extraction region of the He-jet coupled on-line Recoil Atom Mass Analyzer (RAMA) and its target/ion source coupling resulted in significant increases in RAMA efficiencies and its mass resolution, as well as reductions in the overall transit time. At the 88-Inch Cyclotron at LBNL, the decays of 31Cl, 27P and 28P, with half-lives of 150 msec, 260 msec and 270.3 msec, respectively, were examined using a he-jet and low-energy gas ΔE-gas ΔE-silicon E detector telescopes. Total beta-delayed proton branches of 0.3% and 0.07% in 31Cl and 27P, respectively, were estimated. Several proton peaks that had been previously assigned to the decay of 31Cl were shown to be from the decay of 25Si. In 27P, two proton groups at 459 ± 14 keV and 610 ± 11 keV, with intensities of 7 ± 3% and 92 ± 4% relative to the main (100%) group were discovered. The Gamow-Teller component of the preceding beta-decay of each observed proton transition was compared to results from shell model calculations. Finally, a new proton transition was identified, following the β-decay of 28P, at 1,444 ± 12 keV with a 1.7 ± 0.5% relative intensity to the 100% group. Using similar low-energy detector telescopes and the mass separator TISOL at TRIUMF, the 109 msec and 173 msec activities, 17Ne and 33Ar, were studied. A new proton group with energy 729 ± 15 keV was observed following the beta-decay of 17Ne. Several discrepancies between earlier works as to the energies, intensities and assignments of several proton transitions from 17Ne and 33Ar were resolved.

  1. 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.

  2. β -Decay Half-Lives of 110 Neutron-Rich Nuclei across the N =82 Shell Gap: Implications for the Mechanism and Universality of the Astrophysical r Process

    NASA Astrophysics Data System (ADS)

    Lorusso, G.; Nishimura, S.; Xu, Z. Y.; Jungclaus, A.; Shimizu, Y.; Simpson, G. S.; Söderström, P.-A.; Watanabe, H.; Browne, F.; Doornenbal, P.; Gey, G.; Jung, H. S.; Meyer, B.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Wu, J.; Baba, H.; Benzoni, G.; Chae, K. Y.; Crespi, F. C. L.; Fukuda, N.; Gernhäuser, R.; Inabe, N.; Isobe, T.; Kajino, T.; Kameda, D.; Kim, G. D.; Kim, Y.-K.; Kojouharov, I.; Kondev, F. G.; Kubo, T.; Kurz, N.; Kwon, Y. K.; Lane, G. J.; Li, Z.; Montaner-Pizá, A.; Moschner, K.; Naqvi, F.; Niikura, M.; Nishibata, H.; Odahara, A.; Orlandi, R.; Patel, Z.; Podolyák, Zs.; Sakurai, H.; Schaffner, H.; Schury, P.; Shibagaki, S.; Steiger, K.; Suzuki, H.; Takeda, H.; Wendt, A.; Yagi, A.; Yoshinaga, K.

    2015-05-01

    The β -decay half-lives of 110 neutron-rich isotopes of the elements from Rb 37 to Sn 50 were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for r -process calculations and reinforce the notion that the second (A ≈130 ) and the rare-earth-element (A ≈160 ) abundance peaks may result from the freeze-out of an (n ,γ )⇄(γ ,n ) equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the r process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual r -process events.

  3. 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.

  4. Nucleon-nucleon momentum-correlation function as a probe of the density distribution of valence neutrons in neutron-rich nuclei

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    Proton-neutron, neutron-neutron, and proton-proton momentum-correlation functions (Cpn,Cnn, and Cpp) are systematically investigated for 15C and other C-isotope-induced collisions at different entrance channel conditions within the framework of the isospin-dependent quantum-molecular-dynamics model complemented by the correlation after burner (crab) computation code. 15C is a prime exotic nucleus candidate due to the weakly bound valence neutron coupling with closed-neutron-shell nucleus 14C. To study density dependence of the correlation function by removing the isospin effect, the initialized 15C projectiles are sampled from two kinds of density distribution from the relativistic mean-field (RMF) model in which the valence neutron of 15C is populated in both 1d5/2 and 2s1/2 states, respectively. The results show that the density distributions of the valence neutron significantly influence the nucleon-nucleon momentum-correlation function at large impact parameters and high incident energies. The extended density distribution of the valence neutron largely weakens the strength of the correlation function. The size of the emission source is extracted by fitting the correlation function by using the Gaussian source method. The emission source size as well as the size of the final-state phase space are larger for projectile samplings from more extended density distributions of the valence neutron, which corresponds to the 2s1/2 state in the RMF model. Therefore, the nucleon-nucleon momentum-correlation function can be considered as a potentially valuable tool to diagnose exotic nuclear structures, such as the skin and halo.

  5. Evidence for {open_quotes}magnetic rotation{close_quotes} in nuclei: New results on the M1-bands of {sup 198,199}Pb

    SciTech Connect

    Clark, R.M.

    1996-12-31

    Lifetimes of states in four of the M1-bands in {sup 198,199}Pb have been determined through a Doppler Shift Attenuation Method measurement performed using the Gammasphere array. The deduced B(M1) values, which are a sensitive probe of the underlying mechanism for generating these sequences, show remarkable agreement with Tilted Axis Cranking (TAC) calculations. Evidence is also presented for the possible termination of the bands. The results represent clear evidence for a new concept in nuclear excitations: {open_quote}magnetic rotation{close_quote}.

  6. 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.

  7. In-rich Al x In1-x N grown by RF-sputtering on sapphire: from closely-packed columnar to high-surface quality compact layers

    NASA Astrophysics Data System (ADS)

    Núñez-Cascajero, A.; Valdueza-Felip, S.; Monteagudo-Lerma, L.; Monroy, E.; Taylor-Shaw, E.; Martin, R. W.; González-Herráez, M.; Naranjo, F. B.

    2017-02-01

    The structural, morphological, electrical and optical properties of In-rich Al x In1-x N (0  <  x  <  0.39) layers grown by reactive radio-frequency (RF) sputtering on sapphire are investigated as a function of the deposition parameters. The RF power applied to the aluminum target (0 W-150 W) and substrate temperature (300 °C-550 °C) are varied. X-ray diffraction measurements reveal that all samples have a wurtzite crystallographic structure oriented with the c-axis along the growth direction. The aluminum composition is tuned by changing the power applied to the aluminum target while keeping the power applied to the indium target fixed at 40 W. When increasing the Al content from 0 to 0.39, the room-temperature optical band gap is observed to blue-shift from 1.76 eV to 2.0  eV, strongly influenced by the Burstein-Moss effect. Increasing the substrate temperature, results in an evolution of the morphology from closely-packed columnar to compact. For a substrate temperature of 500 °C and RF power for Al of 150 W, compact Al0.39In0.61N films with a smooth surface (root-mean-square surface roughness below 1 nm) are produced.

  8. Few-nucleon transfer reactions on deformed nuclei

    SciTech Connect

    van den Berg, A.M.

    1985-01-01

    Recent developments discussed include: alpha-transfer reactions on deformed nuclei, quasi-elastic neutron transfer reactions induced by /sup 58/Ni beams on spherical and deformed samarium nuclei, and the population of low-lying states in neutron rich nuclei using (particle,..gamma..) or (particle,e) coincidence methods. 37 refs., 10 figs. (LEW)

  9. The Growth of Melt Inclusion- and Water-Rich Zones in Clinopyroxene Phenocrysts of the Powai Ankaramite Flow, Deccan Traps, India: Rapid Closed System Oscillatory Mineral Growth

    NASA Astrophysics Data System (ADS)

    Seaman, S. J.

    2015-12-01

    Water concentrations were measured and mapped using FTIR spectroscopy in clinopyroxene phenocrysts of the Powai ankaramite flow, located near Mumbai, west of the Western Ghats escarpment of the Deccan province, India. Samples were provided by Dr. Hetu Sheth of the Indian Institute of Technology, Mumbai. Chatterjee and Sheth (2015) showed that phenocrysts in the flow were part of a cumulate layer intruded by high-temperature basaltic melt at ~ 6 kb and ~1230oC. Cpx phenocrysts are euhedral and have concentric bands (100 to 200 microns thick) of fine (10-20 micron diameter) melt inclusions. Cpx bands that host melt inclusions have higher concentrations of water than inclusion-free bands. Water concentrations of cpx and ol were used to calculate water concentrations in the melt from which the crystals formed. Water concentrations in the parent magma were between 4.35 and 8.26 wt. % based on water concentrations in cpx, and between 8.24 and 9.41 wt. % based on those in ol. Both Mg and Fe are relatively depleted in the water- and melt inclusion-rich zones in cpx, and Ca is enriched in these zones. We suggest that oscillatory zoning in cpx is a result of repeated growth of cpx in water-richer and water-poorer boundary layers in which water lowered melt viscosity and enhanced diffusion and crystal growth rates. Water-enhanced growth rates may have resulted in preferential capture of melt inclusions preserved in water-rich cpx zones. Mg was preferentially incorporated into the cpx, causing Ca and water to build up in the boundary layer, and Mg and Fe to become relatively depleted in the boundary layer, as discussed for oscillatorially-zoned minerals by Wang and Merino (1993). Application of the equations for growth of oscillatory zones in crystals given by Wang and Merino (1993) to the growth of cpx crystals in the Powai ankaramite indicate that crystal growth occurred relatively quickly, on the order of days, although the width of the boundary zone, which is uncertain

  10. Three-cluster model for the α-accompanied fission of californium nuclei

    NASA Astrophysics Data System (ADS)

    Manimaran, K.; Balasubramaniam, M.

    2009-02-01

    A three-cluster model is proposed to explain the particle-accompanied binary fission of radioactive nuclei. The model is developed as an extension of the preformed cluster model of Gupta and collaborators. The advantage of this model is that, for a fixed third fragment, we can calculate the fragmentation potential minimized in charge coordinate. For our study we chose the various neutron-deficient to neutron-rich californium nuclei, whose analysis reveals that the closed-shell effect of any one of the fragments in ternary fragmentation presents itself as the most favorable configuration to be observed. As one goes from a neutron-deficient to a neutron-rich californium isotope, the role of the neutron closed shell associated with any one of the preferred fragments changes to that of the proton closed shell, and for very neutron rich isotopes of californium the presence of a double closed shell nucleus enhances the decay probability. The quadrupole deformation of the light fragment (A2) associated with the preferred configuration in the symmetric mass region also has a transition from positive to negative deformation as one goes from neutron-deficient to neutron-rich californium isotopes. The calculated relative yields of different fragmentation channels are compared with the available experimental yields for Cf252.

  11. Three-cluster model for the {alpha}-accompanied fission of californium nuclei

    SciTech Connect

    Manimaran, K.; Balasubramaniam, M.

    2009-02-15

    A three-cluster model is proposed to explain the particle-accompanied binary fission of radioactive nuclei. The model is developed as an extension of the preformed cluster model of Gupta and collaborators. The advantage of this model is that, for a fixed third fragment, we can calculate the fragmentation potential minimized in charge coordinate. For our study we chose the various neutron-deficient to neutron-rich californium nuclei, whose analysis reveals that the closed-shell effect of any one of the fragments in ternary fragmentation presents itself as the most favorable configuration to be observed. As one goes from a neutron-deficient to a neutron-rich californium isotope, the role of the neutron closed shell associated with any one of the preferred fragments changes to that of the proton closed shell, and for very neutron rich isotopes of californium the presence of a double closed shell nucleus enhances the decay probability. The quadrupole deformation of the light fragment (A{sub 2}) associated with the preferred configuration in the symmetric mass region also has a transition from positive to negative deformation as one goes from neutron-deficient to neutron-rich californium isotopes. The calculated relative yields of different fragmentation channels are compared with the available experimental yields for {sup 252}Cf.

  12. The K2-ESPRINT Project III: A Close-in Super-Earth around a Metal-rich Mid-M Dwarf

    NASA Astrophysics Data System (ADS)

    Hirano, Teruyuki; Fukui, Akihiko; Mann, Andrew W.; Sanchis-Ojeda, Roberto; Gaidos, Eric; Narita, Norio; Dai, Fei; Van Eylen, Vincent; Lee, Chien-Hsiu; Onozato, Hiroki; Ryu, Tsuguru; Kusakabe, Nobuhiko; Ito, Ayaka; Kuzuhara, Masayuki; Onitsuka, Masahiro; Tatsuuma, Misako; Nowak, Grzegorz; Pallè, Enric; Ribas, Ignasi; Tamura, Motohide; Yu, Liang

    2016-03-01

    We validate a {R}p=2.32+/- 0.24{R}\\oplus planet on a close-in orbit (P = 2.260455 ± 0.000041 days) around K2-28 (EPIC 206318379), a metal-rich M4-type dwarf in the Campaign 3 field of the K2 mission. Our follow-up observations included multi-band transit observations from the optical to the near-infrared, low-resolution spectroscopy, and high-resolution adaptive optics (AO) imaging. We perform a global fit to all of the observed transits using a Gaussian process-based method and show that the transit depths in all of the passbands adopted for the ground-based transit follow-ups ({r}2\\prime ,{z}s,2,J,H,{K}s) are within ˜2σ of the K2 value. Based on a model of the background stellar population and the absence of nearby sources in our AO imaging, we estimate the probability that a background eclipsing binary could cause a false positive to be <2 × 10-5. We also show that K2-28 cannot have a physically associated companion of stellar type later than M4, based on the measurement of almost identical transit depths in multiple passbands. There is a low probability for an M4 dwarf companion (≈ {0.072}-0.04+0.02), but even if this were the case, the size of K2-28b falls within the planetary regime. K2-28b has the same radius (within 1σ) and experiences irradiation from its host star similar to the well-studied GJ 1214b. Given the relative brightness of K2-28 in the near-infrared ({m}{Kep}=14.85 mag and mH = 11.03 mag) and relatively deep transit (0.6%-0.7%), a comparison between the atmospheric properties of these two planets with future observations would be especially interesting.

  13. 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.

  14. Localization and clustering in atomic nuclei

    NASA Astrophysics Data System (ADS)

    Ebran, J.-P.; Khan, E.; Nikšić, T.; Vretenar, D.

    2017-10-01

    Nucleon localization, and formation of clusters in nucleonic matter and finite nuclei are explored in a framework based on nuclear energy density functionals. The liquid-cluster transition is investigated and different measures of localization are discussed. The formation and evolution of α-clusters in excited states of both N = Z and neutron-rich nuclei are analysed. The effects of spin-orbit coupling are discussed in relation to the confining potential.

  15. Coupled-cluster computations of atomic nuclei.

    PubMed

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

    2014-09-01

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

  16. Direct mass measurements of proton-rich isotopes of Ge, As, Se, and Br

    NASA Astrophysics Data System (ADS)

    Lima, G. F.; Lépine-Szily, A.; Audi, G.; Mittig, W.; Chartier, M.; Orr, N. A.; Lichtenthaler, R.; Angelique, J. C.; Casandjian, J. M.; Cunsolo, A.; Donzaud, C.; Foti, A.; Gillibert, A.; Lewitowicz, M.; Lukyanov, S.; MacCormick, M.; Morrissey, D. J.; Ostrowski, A. N.; Sherrill, B. M.; Stephan, C.; Suomijarvi, T.; Tassan-Got, L.; Vieira, D. J.; Villari, A. C.; Wouters, J. M.

    2002-04-01

    The masses of neutron-deficient nuclei close to the proton drip line are an important input for the rapid proton-capture process modeling above 56Ni. The measurement of the masses of proton-rich nuclei with 32<=Z<=35 has been made using a direct time-of-flight technique. The masses of the nuclides 66As,68Se, and 71Br are reported for the first time, with mass excesses of -51 500(680), -53 620(1000), and -57 060(570) keV being found. The masses agree well in most cases with the Audi-Wapstra systematics.

  17. 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

  18. Electron-capture Rates for pf-shell Nuclei in Stellar Environments and Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshio; Honma, Michio; Mori, Kanji; Famiano, Michael A.; Kajino, Toshitaka; Hidakai, Jun; Otsuka, Takaharu

    Gamow-Teller strengths in pf-shell nuclei obtained by a new shell-model Hamltonian, GXPF1J, are used to evaluate electron-capture rates in pf-shell nuclei at stellar environments. The nuclear weak rates with GXPF1J, which are generally smaller than previous evaluations for proton-rich nuclei, are applied to nucleosynthesis in type Ia supernova explosions. The updated rates are found to lead to less production of neutron-rich nuclei such as 58Ni and 54Cr, thus toward a solution of the problem of over-production of neutron-rich isotopes of iron-group nuclei compared to the solar abundance.

  19. 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.

  20. Closing the poor-rich gap in contraceptive use in urban Kenya: are family planning programs increasingly reaching the urban poor?

    PubMed

    Fotso, Jean Christophe; Speizer, Ilene S; Mukiira, Carol; Kizito, Paul; Lumumba, Vane

    2013-08-27

    Kenya is characterized by high unmet need for family planning (FP) and high unplanned pregnancy, in a context of urban population explosion and increased urban poverty. It witnessed an improvement of its FP and reproductive health (RH) indicators in the recent past, after a period of stalled progress. The objectives of the paper are to: a) describe inequities in modern contraceptive use, types of methods used, and the main sources of contraceptives in urban Kenya; b) examine the extent to which differences in contraceptive use between the poor and the rich widened or shrank over time; and c) attempt to relate these findings to the FP programming context, with a focus on whether the services are increasingly reaching the urban poor. We use data from the 1993, 1998, 2003 and 2008/09 Kenya demographic and health survey. Bivariate analyses describe the patterns of modern contraceptive use and the types and sources of methods used, while multivariate logistic regression models assess how the gap between the poor and the rich varied over time. The quantitative analysis is complemented by a review on the major FP/RH programs carried out in Kenya. There was a dramatic change in contraceptive use between 2003 and 2008/09 that resulted in virtually no gap between the poor and the rich in 2008/09, by contrast to the period 1993-1998 during which the improvement in contraceptive use did not significantly benefit the urban poor. Indeed, the late 1990s marked the realization by the Government of Kenya and its development partners, of the need to deliberately target the poor with family planning services. Most urban women use short-term and less effective methods, with the proportion of long-acting method users dropping by half during the review period. The proportion of private sector users also declined between 2003 and 2008/09. The narrowing gap in the recent past between the urban poor and the urban rich in the use of modern contraception is undoubtedly good news, which

  1. Closing the poor-rich gap in contraceptive use in urban Kenya: are family planning programs increasingly reaching the urban poor?

    PubMed Central

    2013-01-01

    Introduction Kenya is characterized by high unmet need for family planning (FP) and high unplanned pregnancy, in a context of urban population explosion and increased urban poverty. It witnessed an improvement of its FP and reproductive health (RH) indicators in the recent past, after a period of stalled progress. The objectives of the paper are to: a) describe inequities in modern contraceptive use, types of methods used, and the main sources of contraceptives in urban Kenya; b) examine the extent to which differences in contraceptive use between the poor and the rich widened or shrank over time; and c) attempt to relate these findings to the FP programming context, with a focus on whether the services are increasingly reaching the urban poor. Methods We use data from the 1993, 1998, 2003 and 2008/09 Kenya demographic and health survey. Bivariate analyses describe the patterns of modern contraceptive use and the types and sources of methods used, while multivariate logistic regression models assess how the gap between the poor and the rich varied over time. The quantitative analysis is complemented by a review on the major FP/RH programs carried out in Kenya. Results There was a dramatic change in contraceptive use between 2003 and 2008/09 that resulted in virtually no gap between the poor and the rich in 2008/09, by contrast to the period 1993–1998 during which the improvement in contraceptive use did not significantly benefit the urban poor. Indeed, the late 1990s marked the realization by the Government of Kenya and its development partners, of the need to deliberately target the poor with family planning services. Most urban women use short-term and less effective methods, with the proportion of long-acting method users dropping by half during the review period. The proportion of private sector users also declined between 2003 and 2008/09. Conclusion The narrowing gap in the recent past between the urban poor and the urban rich in the use of modern

  2. Systematics of proton and diproton separation energies for light nuclei

    SciTech Connect

    Cole, B.J.

    1997-10-01

    A simple method to estimate proton and two-proton separation energies of proton-rich nuclei is presented that is sufficiently accurate to allow the prediction of suitable candidates for observable diproton decay. The method is based on the systematics of measured particle separation energies. Predictions for proton-rich nuclei with Z=18{minus}24 are compared with the results of previous calculations. {copyright} {ital 1997} {ital The American Physical Society}

  3. 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.

  4. Spectroscopy of the neutron-rich actinide nucleus 240U following multinucleon-transfer reactions

    NASA Astrophysics Data System (ADS)

    Birkenbach, B.; Vogt, A.; Geibel, K.; Recchia, F.; Reiter, P.; Valiente-Dobón, J. J.; Bazzacco, D.; Bowry, M.; Bracco, A.; Bruyneel, B.; Corradi, L.; Crespi, F. C. L.; de Angelis, G.; Désesquelles, P.; Eberth, J.; Farnea, E.; Fioretto, E.; Gadea, A.; Gengelbach, A.; Giaz, A.; Görgen, A.; Gottardo, A.; Grebosz, J.; Hess, H.; John, P. R.; Jolie, J.; Judson, D. S.; Jungclaus, A.; Korten, W.; Lenzi, S.; Leoni, S.; Lunardi, S.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Mijatović, T.; Montagnoli, G.; Montanari, D.; Napoli, D.; Pellegri, L.; Pollarolo, G.; Pullia, A.; Quintana, B.; Radeck, F.; Rosso, D.; Şahin, E.; Salsac, M. D.; Scarlassara, F.; Söderström, P.-A.; Stefanini, A. M.; Steinbach, T.; Stezowski, O.; Szilner, S.; Szpak, B.; Theisen, Ch.; Ur, C.; Vandone, V.; Wiens, A.

    2015-10-01

    Background: Nuclear structure information for the neutron-rich actinide nuclei is important since it is the benchmark for theoretical models that provide predictions for the heaviest nuclei. Purpose: γ -ray spectroscopy of neutron-rich heavy nuclei in the actinide region.

  5. 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

  6. Halo nuclei, stepping stones across the drip-lines

    NASA Astrophysics Data System (ADS)

    Simon, H.

    2013-01-01

    The availability of intense secondary beams in conjunction with modern efficient detection setups allows for the production and detailed study of the most extreme nuclear systems, in terms of asymmetry of proton and neutron number, in the continuum. Nuclei close to the drip-lines, exhibiting exotic properties themselves, can be used as a basis in order to populate these even more exotic nuclear systems, e.g. in transfer and knockout reactions. The latter challenge nuclear structure theory by being open quantum systems far from the valley of beta stability as well as reaction aiming at a description of their production mechanisms. Experiments provide data on momentum distributions, while relative energy spectra, and spin alignment during the reaction can be extracted and lead to the observation of energy and angular correlations as well as to dependent quantities such as, e.g., the profile function denoting a momentum width as a function of relative energy. They are determined from reaction products and gamma radiation emerging from the reaction zone. The link to intrinsic properties of these unbound systems has to be explored by gathering precise knowledge of the properties of the seed nuclei and compare them to structures observed in the continuum. In this paper, examples of the above-mentioned methods are presented. The current knowledge about light systems such as 5,7H, 7-10He, 10-13Li and the most neutron-rich oxygen systems is reviewed.

  7. Evolutional schemes for objects with active nuclei

    NASA Technical Reports Server (NTRS)

    Komberg, B. V.

    1979-01-01

    The observational properties of quasistellar objects (QSO) reveal that they are extremely violent nuclei of distant galaxies, but the evolutionary stage of these galaxies is still undetermined. Various published attempts to classify QSO under different criteria - including the one based on the morphological type of the surrounding galaxy E- or S- are analyzed. There are evidences that radioactive quasars reside in E-, while radio-quiet quasars reside in both E- and S- systems. The latter may be evolutionary connected to Seyfert-like objects. A correlation between the nuclei activity level in systems of different morphological type and the relative amount of gas in them is noted. From the point of view of activity level and the duration of active stage of nuclei it is concluded that an interaction of galaxies with the intergalactic medium is of particular importance and must be most conspicuous in spheriodal systems of central regions of rich clusters, in tight groups and binary galaxies.

  8. 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.

  9. Major new sources of biological ice nuclei

    NASA Astrophysics Data System (ADS)

    Moffett, B. F.; Hill, T.; Henderson-Begg, S. K.

    2009-12-01

    Almost all research on biological ice nucleation has focussed on a limited number of bacteria. Here we characterise several major new sources of biogenic ice nuclei. These include mosses, hornworts, liverworts and cyanobacteria. Ice nucleation in the eukaryotic bryophytes appears to be ubiquitous. The temperature at which these organisms nucleate is that at which the difference in vapour pressure over ice and water is at or close to its maximum. At these temperatures (-8 to -18 degrees C) ice will grow at the expense of supercooled water. These organisms are dependent for their water on occult precipitation - fog, dew and cloudwater which by its nature is not collected in conventional rain gauges. Therefore we suggest that these organism produce ice nuclei as a water harvesting mechanism. Since the same mechanism would also drive the Bergeron-Findeisen process, and as moss is known to become airborne, these nuclei may have a role in the initiation of precipitation. The properties of these ice nuclei are very different from the well characterised bacterial nuclei. We will also present DNA sequence data showing that, although related, the proteins responsible are only very distantly related to the classical bacterial ice nuclei.

  10. 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.

  11. 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.

  12. 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)

  13. 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)

  14. 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.

  15. β-Decay Half-Lives of 110 Neutron-Rich Nuclei across the N=82 Shell Gap: Implications for the Mechanism and Universality of the Astrophysical r Process.

    PubMed

    Lorusso, G; Nishimura, S; Xu, Z Y; Jungclaus, A; Shimizu, Y; Simpson, G S; Söderström, P-A; Watanabe, H; Browne, F; Doornenbal, P; Gey, G; Jung, H S; Meyer, B; Sumikama, T; Taprogge, J; Vajta, Zs; Wu, J; Baba, H; Benzoni, G; Chae, K Y; Crespi, F C L; Fukuda, N; Gernhäuser, R; Inabe, N; Isobe, T; Kajino, T; Kameda, D; Kim, G D; Kim, Y-K; Kojouharov, I; Kondev, F G; Kubo, T; Kurz, N; Kwon, Y K; Lane, G J; Li, Z; Montaner-Pizá, A; Moschner, K; Naqvi, F; Niikura, M; Nishibata, H; Odahara, A; Orlandi, R; Patel, Z; Podolyák, Zs; Sakurai, H; Schaffner, H; Schury, P; Shibagaki, S; Steiger, K; Suzuki, H; Takeda, H; Wendt, A; Yagi, A; Yoshinaga, K

    2015-05-15

    The β-decay half-lives of 110 neutron-rich isotopes of the elements from _{37}Rb to _{50}Sn were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for r-process calculations and reinforce the notion that the second (A≈130) and the rare-earth-element (A≈160) abundance peaks may result from the freeze-out of an (n,γ)⇄(γ,n) equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the r process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual r-process events.

  16. Empirical formula for β --decay half-lives of r-process nuclei

    NASA Astrophysics Data System (ADS)

    Zhou, Yong; Li, ZhiHong; Wang, YouBao; Chen, YongShou; Guo, Bing; Su, Jun; Li, YunJu; Yan, ShengQuan; Li, XinYue; Han, ZhiYu; Shen, YangPing; Gan, Lin; Zeng, Sheng; Lian, Gang; Liu, WeiPing

    2017-08-01

    Experimental data of β --decay half-lives of nuclei with atomic number between 20 and 190 are investigated. A systematic formula has been proposed to calculate β --decay half-lives of neutron-rich nuclei, with a particular consideration on shell and pair effects, the decay energy Q as well as the nucleon numbers (Z, N). Although the formula has relatively few parameters, it reproduces the experimental —decay half-lives of neutron-rich nuclei very well. The predicted half-lives for the r-process relevant nuclei obtained with the current formula serve as reliable input in the r-process model calculations.

  17. 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.

  18. Isomer spectroscopy of neutron-rich $$^{165,167}$$Tb

    DOE PAGES

    Gurgi, L. A.; Regan, P. H.; Soderstrom, P. -A.; ...

    2017-01-01

    We present information on the excited states in the prolate-deformed, neutron-rich nuclei 165,167Tb100,102. The nuclei of interest were synthesised following in-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm 9Be target at the Radioactive Ion-Beam Factory (RIBF), RIKEN, Japan. The exotic nuclei were separated and identified event-by-event using the BigRIPS separator, with discrete energy gamma-ray decays from isomeric states with half-lives in the μs regime measured using the EURICA gamma-ray spectrometer. Metastable-state decays are identified in 165Tb and 167Tb and interpreted as arising from hindered E1 decay from the 72–[523] single quasi-proton Nilsson configurationmore » to rotational states built on the 32–[411] single quasi-proton ground state. Lastly, these data correspond to the first spectroscopic information in the heaviest, odd-A terbium isotopes reported to date and provide information on proton Nilsson configurations which reside close to the Fermi surface as the 170Dy doubly-midshell nucleus is approached.« less

  19. Isomer spectroscopy of neutron-rich $^{165,167}$Tb

    SciTech Connect

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

    2017-01-01

    We present information on the excited states in the prolate-deformed, neutron-rich nuclei 165,167Tb100,102. The nuclei of interest were synthesised following in-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm 9Be target at the Radioactive Ion-Beam Factory (RIBF), RIKEN, Japan. The exotic nuclei were separated and identified event-by-event using the BigRIPS separator, with discrete energy gamma-ray decays from isomeric states with half-lives in the μs regime measured using the EURICA gamma-ray spectrometer. Metastable-state decays are identified in 165Tb and 167Tb and interpreted as arising from hindered E1 decay from the 72[523] single quasi-proton Nilsson configuration to rotational states built on the 32[411] single quasi-proton ground state. Lastly, these data correspond to the first spectroscopic information in the heaviest, odd-A terbium isotopes reported to date and provide information on proton Nilsson configurations which reside close to the Fermi surface as the 170Dy doubly-midshell nucleus is approached.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Four-Body Correlations in Nuclei

    NASA Astrophysics Data System (ADS)

    Sambataro, M.; Sandulescu, N.

    2015-09-01

    Low-energy spectra of 4 n nuclei are described with high accuracy in terms of four-body correlated structures ("quartets"). The states of all N ≥Z nuclei belonging to the A =24 isobaric chain are represented as a superposition of two-quartet states, with quartets being characterized by isospin T and angular momentum J . These quartets are assumed to be those describing the lowest states in 20Ne (Tz=0 ), 20F (Tz=1 ), and 20O (Tz=2 ). We find that the spectrum of the self-conjugate nucleus 24Mg can be well reproduced in terms of T =0 quartets only and that, among these, the J =0 quartet plays by far the leading role in the structure of the ground state. The same conclusion is drawn in the case of the three-quartet N =Z nucleus 28Si. As an application of the quartet formalism to nuclei not confined to the s d shell, we provide a description of the low-lying spectrum of the proton-rich 92Pd. The results achieved indicate that, in 4 n nuclei, four-body degrees of freedom are more important and more general than usually expected.

  5. Precision lifetime measurements in light exotic nuclei

    NASA Astrophysics Data System (ADS)

    McCutchan, Elizabeth

    2017-01-01

    A new generation of ab-initio calculations, based on realistic two- and three-body forces have had a profound impact on our understanding of nuclei. They have shed light on topics such as the origin of effective forces (like spin-orbit and tensor interactions) and the mechanisms behind cluster and pairing correlations. New precise data are required to both better parameterize the three body forces and to improve numerical methods. A sensitive probe of the structure of light nuclei comes from their electromagnetic transition rates. A refined Doppler Shift Attenuation Method (DSAM) will be outlined which is used to precisely measure lifetimes in light nuclei and helps to reduce and quantity systematic uncertainties in the measurement. Using this careful DSAM, we have made a series of precise measurements of electromagnetic transition strengths in Li isotopes, A =10 nuclei, and the exotic halo nucleus, 12Be. Various phenomena, such as alpha clustering and meson-exchange currents, can be investigated in these seemingly simple systems, while the collection of data spanning stable to neutron-rich, allows us to probe the influence of additional valence neutrons. This talk will report on what has been learned, and the challenges that lie in the future, both in experiment and theory, as we push to describing and measuring even more exotic systems. Work supported by the Office of Nuclear Physics, Office of Science of the U.S. Department of Energy under contract No. DE-AC02-98CH10886.

  6. 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.

  7. 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)

  8. Recent progress in the studies of neutron-rich and high-$Z$ systems within the covariant density functional theory

    SciTech Connect

    Afanasjev, Anatoli V.; Agbemava, S. E.; Ray, D.; Ring, P.

    2017-01-01

    Here, the analysis of statistical and systematic uncertainties and their propagation to nuclear extremes has been performed. Two extremes of nuclear landscape (neutron-rich nuclei and superheavy nuclei) have been investigated. For the first extreme, we focus on the ground state properties. For the second extreme, we pay a particular attention to theoretical uncertainties in the description of fission barriers of superheavy nuclei and their evolution on going to neutron-rich nuclei.

  9. 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.…

  10. 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.…

  11. Exotic structure in light neutron-rich nuclei

    SciTech Connect

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

    2015-10-15

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

  12. Stellar (n, gamma) cross sections of neutron-rich nuclei

    SciTech Connect

    Marganiec, J.; Domingo Pardo, C.; Kaeppeler, F.

    2010-03-01

    The present measurements were performed by means of the activation technique. Neutrons were produced at the Karlsruhe Van de Graaff accelerator via the {sup 7}Li(p,n){sup 7}Be reaction. For proton energies just above threshold, one obtains a neutron spectrum similar to a Maxwellian distribution for kT = 25 keV. This quasi-stellar neutron spectrum allowed us to measure the Maxwellian averaged cross sections directly. The experimental results of {sup 174,176}Yb, {sup 184,186}W, {sup 190,192}Os, {sup 196,198}Pt, and {sup 202}Hg were extrapolated from kT = 25 keV to lower and higher temperatures.

  13. Beta Decay Spectroscopy of Neutron-Rich Nuclei at RIBF

    NASA Astrophysics Data System (ADS)

    Lorusso, G.; Nishimura, S.; Baba, H.; Doornenbal, P.; Isobe, T.; Söderström, P.-A.; Browne, F.; Daido, R.; Yifan, F.; Nishibata, H.; Yagi, A.; Gey, G.; Li, Z.; Wu, J.; Lubos, D.; Moschner, K.; Patel, Z.; Rice, S.; Sinclair, L.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Watanabe, H.; Xu, Z. Y.; Yoshinaga, K.

    2015-11-01

    The development of a high intensity 238U beam at the Radioactive Isotope Beam Factory (RIBF) has opened a new opportunity to explore exotic regions of the nuclear chart that were not accessible before. Along with beam development, the installation of the high efficiency γ-detector EURICA has made β-decay spectroscopy measurements of these regions possible, and a large international effort named the EURICA project has been launched to take advantage of this new opportunity.

  14. 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.

  15. 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).

  16. Cluster aspects of p-shell and sd-shell nuclei

    SciTech Connect

    Kanada-En'yo, Y.; Kobayashi, F.; Suhara, T.; Kimura, M.; Taniguchi, Y.

    2011-05-06

    We report some topics on cluster structures studied by using a theoretical method of antisymmetrized molecular dynamics(AMD). Cluster features of p-shell and sd-shell nuclei are discussed. In particular, three alpha cluster structures in the excited states of {sup 12}C and {sup 14}C are focused. Dineutron correlations in neutron-rich nuclei are also discussed.

  17. 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.

  18. Structure and symmetries of odd-odd triaxial nuclei

    NASA Astrophysics Data System (ADS)

    Palit, R.; Bhat, G. H.; Sheikh, J. A.

    2017-05-01

    Rotational spectra of odd-odd Rh and Ag isotopes are investigated with the primary motivation to search for the spontaneous chiral symmetry breaking phenomenon in these nuclei. The experimental results obtained on the degenerate dipole bands of some of these isotopes using a large array of gamma detectors are discussed and studied using the triaxial projected shell (TPSM) approach. It is shown that, first of all, to reproduce the odd-even staggering of the known yrast bands of these nuclei, large triaxial deformation is needed. This large triaxial deformation also gives rise to doublet band structures in many of these studied nuclei. The observed doublet bands in these isotopes are shown to be reproduced reasonably well by the TPSM calculations. Further, the TPSM calculations for neutron-rich nuclei indicate that the ideal manifestation of the chirality can be realised in 106Rh and 112Ag , where the doublet bands have similar electromagnetic properties along with small differences in excitation energies.

  19. Light element production by low energy nuclei from massive stars

    NASA Technical Reports Server (NTRS)

    Vangioni-Flam, E.; Casse, M.; Ramaty, R.

    1997-01-01

    The Orion complex is a source of gamma rays attributed to the de-excitation of fast carbon and oxygen nuclei excited through interactions with ambient hydrogen and helium. This has consequences for the production and evolution of light isotopes in the Galaxy, as massive stars appear as prolific sources of C-O rich low energy nuclei. The different stages of massive star evolution are considered in relation to the acceleration of nuclei to moderate energies. It is concluded that the low energy nuclear component originating from massive stars plays a larger role than the usual Galactic cosmic rays in shaping the evolution of Li-6, Be-9, B-10 and B-11, especially in the early Galactic evolution. The enhancement of the B-11/B-10 ratio observed in meteorites and in the interstellar medium is attributed to the interaction of low energy carbon nuclei with ambient H and to a lesser degree, to neutrino spallation.

  20. Light element production by low energy nuclei from massive stars

    NASA Technical Reports Server (NTRS)

    Vangioni-Flam, E.; Casse, M.; Ramaty, R.

    1997-01-01

    The Orion complex is a source of gamma rays attributed to the de-excitation of fast carbon and oxygen nuclei excited through interactions with ambient hydrogen and helium. This has consequences for the production and evolution of light isotopes in the Galaxy, as massive stars appear as prolific sources of C-O rich low energy nuclei. The different stages of massive star evolution are considered in relation to the acceleration of nuclei to moderate energies. It is concluded that the low energy nuclear component originating from massive stars plays a larger role than the usual Galactic cosmic rays in shaping the evolution of Li-6, Be-9, B-10 and B-11, especially in the early Galactic evolution. The enhancement of the B-11/B-10 ratio observed in meteorites and in the interstellar medium is attributed to the interaction of low energy carbon nuclei with ambient H and to a lesser degree, to neutrino spallation.

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

    SciTech Connect

    Borcea, C.; Audi, G.

    1998-12-21

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

  2. [The distribution of NADPH-diaphorase and neuronal no synthase in rat medulla oblongata nuclei].

    PubMed

    Chertok, V M; Kotsuba, A E

    2013-01-01

    The distribution of nitroxide ergic neurons in the medulla oblongata nuclei in Wistar rats (n = 8) was studied histochemically (NADPH-diaphorase) and using immunohistochemistry with an antiserum against neuronal form of nitric oxide synthase (nNOS). NADPH-diaphorase activity was found in large and small neurons of the sensory, autonomic and motor nuclei. The latter were especially rich in the cells demonstrating the activity of the enzyme. Unlike NADPH-diaphorase, nNOS in the corresponding nuclei was always detected in the fewer number of neurons, predominantly of small sizes. The sensory nuclei (nucleus of solitary tract, reticular parvocellular and lateral nuclei, spinal nucleus of the trigeminal nerve) contained 1.5-3 times more nNOS neurons than in motor nuclei. In some nuclei (nucleus ambiguus, hypoglossal nerve nucleus), containing numerous NADPH-diaphorase-positive neurons, immunoreactive cells were particularly rare.

  3. Reactions and structure of exotic nuclei

    SciTech Connect

    Esbensen, H.

    1993-08-01

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

  4. Physics of Exotic Nuclei at RIBF

    NASA Astrophysics Data System (ADS)

    Sakurai, Hiroyoshi

    2014-09-01

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

  5. Quasars in rich galaxy clusters

    NASA Technical Reports Server (NTRS)

    Ellingson, Erica; Yee, Howard K. C.

    1993-01-01

    The evolution of AGN activity in rich clusters of galaxies is found to be approximately 5 times more rapid than that in poor clusters. This rapid evolution may be driven by evolution in the dynamics of galaxy cluster cores. Results from our spectroscopic studies of galaxies associated with quasars are consistent with this scenario, in that bright AGN are preferentially found in regions of lower velocity dispersion. Alternately, the evolution may be driven by formation of a dense intra-cluster medium (ICM). Galaxies close to quasars in rich cluster cores are much bluer (presumably gas rich) than galaxies in the cores of other rich clusters, in support of this model.

  6. Experiments with neutron-rich isomeric beams

    SciTech Connect

    Rykaczewski, K. |; Grzywacz, R. |; Lewitowicz, M.; Pfuetzner, M.; Grawe, H.

    1998-01-01

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

  7. Coupled-Channel Computation of Direct Neutron Capture on Non-Spherical Nuclei

    NASA Astrophysics Data System (ADS)

    Arbanas, Goran; Thompson, Ian; Escher, Jutta; Nunes, Filomena; Elster, Charlotte; Zhang, Shi-Sheng

    2014-09-01

    Models of direct neutron capture of neutrons have so far accounted for the effects of non-spherical nuclei either in the incoming wave functions (via non-spherical optical model potentials), or in the final bound states (via non-spherical real potential wells), but not in both. Since it is known that spherical optical potentials do not give a good reproduction of low energy neutron-scattering observables of deformed nuclei, we have performed calculations in which the initial and final states are both treated in a self-consistent, non-spherical-nucleus picture. We have done this in the coupled-channels model of nuclear reactions implemented in the FRESCO code by using the same deformation-length for the couplings to the rotational-band states in the incoming and the final state configurations. We compute direct capture using this method for even-mass calcium isotopes 40 , 42 , 44 , 46 , 48Ca to study the effect across the two closed neutron shells, for neutron-rich even-mass tin isotopes relevant to models of astrophysical nucleosynthesis, and for 56Fe that is an important structural material used in nuclear applications. Models of direct neutron capture of neutrons have so far accounted for the effects of non-spherical nuclei either in the incoming wave functions (via non-spherical optical model potentials), or in the final bound states (via non-spherical real potential wells), but not in both. Since it is known that spherical optical potentials do not give a good reproduction of low energy neutron-scattering observables of deformed nuclei, we have performed calculations in which the initial and final states are both treated in a self-consistent, non-spherical-nucleus picture. We have done this in the coupled-channels model of nuclear reactions implemented in the FRESCO code by using the same deformation-length for the couplings to the rotational-band states in the incoming and the final state configurations. We compute direct capture using this method for even

  8. Fusion excitation functions involving transitional nuclei

    SciTech Connect

    Rehm, K.E.; Jiang, C.L.; Esbensen, H.

    1995-08-01

    Measurements of fusion excitation functions involving transitional nuclei {sup 78}Kr and {sup 100}Mo showed a different behavior at low energies, if compared to measurements with {sup 86}Kr and {sup 92}Mo. This points to a possible influence of nuclear structure on the fusion process. One way to characterize the structure of vibrational nuclei is via their restoring force parameters C{sub 2} which can be calculated from the energy of the lowest 2{sup +} state and the corresponding B(E2) value. A survey of the even-even nuclei between A = 28-150 shows strong variations in C{sub 2} values spanning two orders of magnitude. The lowest values for C{sub 2} are observed for {sup 78}Kr, {sup 104}Ru and {sup 124}Xe followed by {sup 74,76}Ge, {sup 74,76}Se, {sup 100}Mo and {sup 110}Pd. In order to learn more about the influence of {open_quotes}softness{close_quotes} on the sub-barrier fusion enhancement, we measured cross sections for evaporation residue production for the systems {sup 78}Kr + {sup 104}Ru and {sup 78}Kr + {sup 76}Ge with the gas-filled magnet technique. For both systems, fusion excitation functions involving the closed neutron shell nucleus {sup 86}Kr were measured previously. The data are presently being analyzed.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Unified studies of structure and reactions in light unstable nuclei

    NASA Astrophysics Data System (ADS)

    Ito, Makoto

    2016-06-01

    The generalized two-center cluster model (GTCM), which can treat covalent, ionic and atomic configurations in general systems with two inert cores plus valence nucleons, is formulated in the basis of the microscopic cluster model. In this model, the covalent configurations constructed by the molecular orbital (MO) method and the atomic (or ionic) configuration obtained by the valence bonding (VB) method can be described in a consistent manner. GTCM is applied to the light neutron-rich system, 10,12Be = α + α + XN (X = 2,4), and the unified studies of the structural changes and the reaction problem are performed. In the structure study, the calculated energy levels are characterized in terms of the chemical bonding like structures, such as the covalent MO or ionic VB structures. The chemical bonding structures changes from level to level within a small energy interval. In the unbound region, the structure problem with the total system of α + α + XN and the reaction problem, induced by the collision of an asymptotic VB state of α+6,8He, are combined by GTCM. The properties of unbound resonant states are discussed in a close connection to the reaction mechanism, and some enhancement factors originated from the properties of the intrinsic states are predicted in the reaction observables. The unified calculation of the structures and the reactions is applied to the Coulomb shift problem in the mirror system, such the 10Be and 10C nuclei. The Coulomb displacement energy of the mirror systems are discussed.

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

    SciTech Connect

    Li Lulu; Meng Jie; Zhao Enguang; Zhou Shangui

    2013-05-06

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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. Probing the hidden secrets of Seyfert nuclei.

    NASA Astrophysics Data System (ADS)

    Appenzeller, I.; Wagner, S.

    1990-06-01

    The nuclei of active galaxies are clearly among the most spectacular and violent places that can be found in our present universe. Most extreme are the bright Quasars, where we observe a total energy output equivalent to a large galaxy cluster from galactic core regions comparable in size to our solar system. In addition to optical and radio radiation we often observe intense X-ray and even energetic Gamma radiation as well as collimated streams of matter moving at velocities close to the velocity of light.

  5. Quantitative microspectral evaluation of the ratio of arginine-rich to lysine-rich histones in neurons and neuroglial cells.

    PubMed

    Pevzner, L Z; Raygorodskaya, T G; Agroskin, L S

    1978-09-01

    Staining of nervous tissue sections with ammoniacal silver according to Black et al. has been confirmed to be a reliable histochemical colour reaction for quantitative evaluation of arginine-rich and lysine-rich histones in cell structures on the basis of determinations of the position of spectral curve maximum. Neurons of several brain nuclei which differed in predominating neurotransmitter did not differ in the ratio of arginine-rich to lysine-rich histones while some differences in this ratio were found out in the glial satelite cells adjacent to the corresponding neurons of these nuclei. Moderate circadian fluctuations were observed in the arginine-rich to lysine-rich histone ratio, these fluctuations being rather similar in the neurons studied and in the cells of perineuronal neuroglia.

  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. Description of Exotic Nuclei with the Interacting Boson Model

    SciTech Connect

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

    2008-11-11

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

  8. 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.

  9. Fission of actinide nuclei using multi-nucleon transfer reactions

    NASA Astrophysics Data System (ADS)

    Léguillon, Romain; Nishio, Katsuhisa; Hirose, Kentaro; Orlandi, Riccardo; Makii, Hiroyuki; Nishinaka, Ichiro; Ishii, Tetsuro; Tsukada, Kazuaki; Asai, Masato; Chiba, Satoshi; Ohtsuki, Tsutomu; Araki, Shohei; Watanabe, Yukinobu; Tatsuzawa, Ryotaro; Takaki, Naoyuki

    2014-09-01

    We are promoting a campaign to measure fission-fragment mass distributions for neutron-rich actinide nuclei populated by transfer reactions from their ground state up to an excitation energy of several tens MeV. We thus obtain the excitation energy dependence of the mass distribution. The experiment was carried out at the 20 MV JAEA tandem facility at Tokai. We report on the data obtained in the direct reaction 18 O + 232 Th . Transfer-channels and excitation energies of the fissioning nuclei were identified using silicon dE-E detectors located at forward angle. Two fission fragments were detected in coincidence using multi-wire proportional counters. Fission fragment masses were determined by kinematic consideration. We obtained the fission fragment mass distributions for 13 nuclei from actinium to uranium and some fission barrier heights. We are promoting a campaign to measure fission-fragment mass distributions for neutron-rich actinide nuclei populated by transfer reactions from their ground state up to an excitation energy of several tens MeV. We thus obtain the excitation energy dependence of the mass distribution. The experiment was carried out at the 20 MV JAEA tandem facility at Tokai. We report on the data obtained in the direct reaction 18 O + 232 Th . Transfer-channels and excitation energies of the fissioning nuclei were identified using silicon dE-E detectors located at forward angle. Two fission fragments were detected in coincidence using multi-wire proportional counters. Fission fragment masses were determined by kinematic consideration. We obtained the fission fragment mass distributions for 13 nuclei from actinium to uranium and some fission barrier heights. Present study is supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan.

  10. 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.

  11. 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.

  12. Nuclei at extreme conditions. A relativistic study

    SciTech Connect

    Afanasjev, Anatoli

    2014-11-14

    The major goals of the current project were further development of covariant density functional theory (CDFT), better understanding of its features, its application to different nuclear structure and nuclear astrophysics phenomena and training of graduate and undergraduate students. The investigations have proceeded in a number of directions which are discussed in detail in the part “Accomplishments” of this report. We have studied the role of isovector and isoscalar proton-neutron pairings in rotating nuclei; based on available experimental data it was concluded that there are no evidences for the existence of isoscalar proton-neutron pairing. Generalized theoretical approach has been developed for pycnonuclear reaction rates in the crust of neutron stars and interior of white dwarfs. Using this approach, extensive database for considerable number of pycnonuclear reactions involving stable and neutron-rich light nuclei has been created; it can be used in future for the study of various nuclear burning phenomena in different environments. Time-odd mean fields and their manifestations in terminating states, non-rotating and rotating nuclei have been studied in the framework of covariant density functional theory. Contrary to non-relativistic density functional theories these fields, which are important for a proper description of nuclear systems with broken time-reversal symmetry, are uniquely defined in the CDFT framework. Hyperdeformed nuclear shapes (with semi-axis ratio 2.5:1 and larger) have been studied in the Z = 40-58 part of nuclear chart. We strongly believe that such shapes could be studied experimentally in the future with full scale GRETA detector.

  13. Pygmy Dipole Strength and Neutron Skins in Exotic Nuclei

    NASA Astrophysics Data System (ADS)

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

    2008-05-01

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

  14. The quest for novel modes of excitation in exotic nuclei

    NASA Astrophysics Data System (ADS)

    Paar, N.

    2010-06-01

    This paper provides an insight into several open problems in the quest for novel modes of excitation in nuclei with isospin asymmetry, deformation and finite-temperature characteristics in stellar environments. Major unsolved problems include the nature of pygmy dipole resonances, the quest for various multipole and spin-isospin excitations both in neutron-rich and proton drip-line nuclei mainly driven by loosely bound nucleons, excitations in unstable deformed nuclei and evolution of their properties with the shape phase transition. Exotic modes of excitation in nuclei at finite temperatures characteristic of supernova evolution present open problems with a possible impact in modeling astrophysically relevant weak interaction rates. All these issues challenge self-consistent many-body theory frameworks at the frontiers of on-going research, including nuclear energy density functionals, both phenomenological and constrained by the strong interaction physics of QCD, models based on low-momentum two-nucleon interaction Vlow-k and correlated realistic nucleon-nucleon interaction VUCOM, supplemented by three-body force, as well as two-nucleon and three-nucleon interactions derived from the chiral effective field theory. Joined theoretical and experimental efforts, including research with radioactive isotope beams, are needed to provide insight into dynamical properties of nuclei away from the valley of stability, involving the interplay of isospin asymmetry, deformation and finite temperature.

  15. Deformed halo nuclei probed by breakup reactions

    NASA Astrophysics Data System (ADS)

    Nakamura, Takashi

    2013-07-01

    Breakup reactions play important roles in elucidating the structures near the drip lines, such as nuclear halo. The recent experimental results using the Coulomb and nuclear breakup reactions for the neutron-drip-line nuclei at the new-generation RI beam facility, RIBF at RIKEN, are presented. Focuses are put on the results on the newly found halo nucleus 31Ne, which is intriguing also in that this nucleus is in the island-of-inversion and thus could be strongly deformed. The results on other Ne/Mg/Si neutron rich isotopes ranging from N=20 towards N=28 are also briefly reported. The first breakup experiments using SAMURAI facility at RIBF and future perspectives are also presented.

  16. Spin Modes in Nuclei and Nuclear Forces

    SciTech Connect

    Suzuki, Toshio; Otsuka, Takaharu

    2011-05-06

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

  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. The morphology of cometary nuclei

    NASA Astrophysics Data System (ADS)

    Keller, H. U.; Jorda, L.

    the planetary system (4.5 Gy). Therefore, observed comets could only recently have arrived on their orbits dipping inside the inner Solar System. This reservoir of comets must have been established during the formation process of the planetary system itself. Cometesimals were agglomerated from interstellar/interplanetary gas and dust and scattered out of the inner Solar System by the giant outer planets (Section 2.3). This scheme implies that a central part of a comet, its nucleus, is stable enough to survive these perturbations. It must also be stable enough to pass the vicinity of the sun for many times in the case of a short-period comet. Comets are bright and large when they are close to the sun and fade quickly when they recede beyond about 2AU. Only with the advent of photography and large astronomical telescopes could a comet be followed until it becomes a starlike point source. What makes comets active near the Sun, blowing their appearances up to the order of 105 km? Bright comets often develop tails two orders of magnitude longer. In an attempt to explain the cometary appearance, Bredichin (1903) introduced a mechanical model where repulsive forces drive the particles away from a central condensation. Spectroscopy revealed that dust grains reflect the solar irradiation. In addition, simple molecules, radicals and ions were found as constituents of the cometary coma and tail. The nature of the central condensation remained mysterious for a long time because of the observational dilemma. When the comet is close to the Earth and therefore to the Sun the dense coma obscures the view into its centre. When activity recedes the comet is too far away and too dim for detailed observations of its central condensation. During the middle of the nineteenth century the connection between comets and meteor streams was established. Schiaparelli (1866) calculated the dispersion of cometary dust within the orbital plane. From this time on the perception that the central

  19. 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.

  20. 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.

  1. 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.

  2. Probing neutron rich matter with parity violation

    NASA Astrophysics Data System (ADS)

    Horowitz, Charles

    2016-03-01

    Many compact and energetic astrophysical systems are made of neutron rich matter. In contrast, most terrestrial nuclei involve approximately symmetric nuclear matter with more equal numbers of neutrons and protons. However, heavy nuclei have a surface region that contains many extra neutrons. Precision measurements of this neutron rich skin can determine properties of neutron rich matter. Parity violating electron scattering provides a uniquely clean probe of neutrons, because the weak charge of a neutron is much larger than that of a proton. We describe first results and future plans for the Jefferson Laboratory experiment PREX that measures the thickness of the neutron skin in 208Pb. Another JLAB experiment CREX will measure the neutron radius of 48Ca and test recent microscopic calculations of this neutron rich 48 nucleon system. Finally, we show how measuring parity violation at multiple momentum transfers can determine not just the neutron radius but the full radial structure of the neutron density in 48Ca. A neutron star is eighteen orders of magnitude larger than a nucleus (km vs fm) but both the star and the neutron rich nuclear skin are made of the same neutrons, with the same strong interactions, and the same equation of state. A large pressure pushes neutrons out against surface tension and gives a thick neutron skin. Therefore, PREX will constrain the equation of state of neutron rich matter and improve predictions for the structure of neutron stars. Supported in part by DOE Grants DE-FG02-87ER40365 (Indiana University) and DE-SC0008808 (NUCLEI SciDAC Collaboration).

  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. Meson properties from mesic atoms and mesic nuclei

    NASA Astrophysics Data System (ADS)

    Hirenzaki, Satoru; Ikeno, Natsumi; Nagahiro, Hideko; Higashi, Yuko

    2014-11-01

    Meson properties are believed to have close connection to the fundamental theory, QCD, and have been studied for a long time both theoretically and experimentally. In this report, we study the recent activities in this field and consider the η(958) mesic nuclei and the deeply bound pionic atoms. We summarize the possible formation of the η(958) mesic nuclei by the (p, d) reactions and report the new possibilities of the spectroscopic study of the pionic atoms using the (d,3He) reactions.

  5. 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.

  6. Superheavy Nuclei: Which Regions of Nuclear Map are Accessible for the Nearest Studies

    NASA Astrophysics Data System (ADS)

    Karpov, A. V.; Zagrebaev, V. I.; Greiner, W.

    2015-11-01

    Use of fusion reactions for synthesis and studying new superheavy nuclei is considered in the paper. Perspectives of synthesis of new elements with Z > 118 are discussed. The gap of unknown SH nuclei, located between the isotopes which were produced earlier in the cold and hot fusion reactions, can be filled in fusion reactions of 48Ca with available lighter isotopes of Pu, Am, and Cm. Cross sections for the production of these nuclei are predicted to be rather large. The found area of β+-decaying SH nuclei with 111 ≤ Z ≤ 115 located to the "right" (more neutron-rich) to those synthesized recently in Dubna in 48Ca-induced fusion reactions gives a unique chance to synthesize in fusion reactions the most stable SH nuclei located at the center of the island of stability.

  7. Closing in on Close Reading

    ERIC Educational Resources Information Center

    Boyles, Nancy

    2013-01-01

    "A significant body of research links the close reading of complex text--whether the student is a struggling reader or advanced--to significant gains in reading proficiency and finds close reading to be a key component of college and career readiness" (Partnership for Assessment of Readiness for College and Careers, 2011, p. 7). When the author…

  8. Surface Photometry of Reverberation-Mapped Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Bower, Gary A.

    2015-01-01

    I present a statistical analysis of the surface photometry obtained for a sample of Hubble Space Telescope (HST) archival images of the host galaxies containing active galactic nuclei (AGN), whose time-delay between continuum and broad emission line variations have been analyzed (i.e., reverberation mapping). For quiescent galaxies, strong correlations exist between central black hole mass and host galaxy structure. If there are similar correlations for AGN between central black hole masses derived from reverberation mapping and the host galaxy structure that I have derived from archival HST images, this would imply some validation of the assumptions underlying reverberation mapping concerning the structure, kinematics, and orientation of the broad line regions in AGN.The correlations for quiescent galaxies bewteen central black hole mass and host galaxy structure imply that there might be a strong causal connection between the formation and evolution of the black hole and the galaxy bulge. A current hypothesis is that bulges, black holes, and quasars formed, grew, or turned on as parts of the same process, in part because the collapse or merger of bulges might provide a rich fuel supply to a central black hole. One way of testing this hypothesis would be to plot AGN as a function of redshift on these correlations. However, two severe obstacles limit the ability to measure black hole masses in AGN using HST to analyze the central stellar and/or gas dynamics: (1) since spatial resolution becomes more limited at larger distances, only two reverberation-mapped AGN are close enough to Earth to render the analysis feasible, and (2) it isdifficult to obtain useful spectra of the stars and/or gas in the presence of the bright nonstellar nucleus. The most useful alternative is to exploit reverberation mapping, which uses the time delay in a given AGN between variations in the continuum emission and broad emission lines.

  9. Closing remarks

    PubMed Central

    Daykin, C. D.

    1997-01-01

    Closing remarks to Human genetics - uncertainties and the financial implications ahead. A Discussion held at the Royal Society on 25 and 26 September 1996, and organized and edited by R. M. Anderson.

  10. Dense serotonergic innervation of principal nuclei of the superior olivary complex in mouse.

    PubMed

    Thompson, Ann M; Hurley, Laura M

    2004-02-19

    To evaluate species differences in the serotonergic innervation of the superior olivary complex, serotonergic fibers and varicosities were labeled with immunohistochemistry in mouse. Many immunoreactive fibers and varicosities were observed in two of the three principal nuclei, in addition to some periolivary nuclei. This pattern of staining differs greatly from that observed in other mammals in which periolivary, but not principal nuclei are richly innervated by serotonin (5-HT). These results indicate a functional relationship between the 5-HT system and both the ascending and descending auditory systems in the mouse.

  11. Cloud Condensation Nuclei Measurements in Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    Hudson, J. G.; Simpson, J.

    2002-01-01

    The first measurements of cloud condensation nuclei (CCN) within and around tropical cyclones were made with the Desert Research Institute (DRI) CCN spectrometer (Hudson 1909) from a NOAA P-3 Hurricane Hunter aircraft throughout the 2001 season. Two penetrations of the closed eye of Hurricane Erin off the northeast US coast on Sept. 10 showed concentrations consistently well in excess of 1000 per cubic cm at approximately 1.4% supersaturation. Simultaneous condensation nuclei (CN--total particle) concentrations were consistently well in excess of 2000 per cubic cm throughout these closed eye penetrations. These within eye measurements at 4 km altitude for exceeded CCN and CN measurements just outside of the storm at similar altitudes--300 and 600 per cubic cm respectively. These CCN and CN concentrations within this closed eye were far above concentrations in maritime air masses; they are characteristic of continental or polluted air masses. Although there was a possibility that Saharan duct may have gotten into this storm these sub tenth micrometer particles are much too small and much too numerous to be dust. Such high concentrations may have originated from European air pollution, which may have been transported by similar airflow patterns to those that carry Saharan dust across the Atlantic. These high concentrations may be a manifestation of descending air that brings higher concentrations that are often characteristic of the upper troposphere (Clarke and Kapustin 2002). Later in the month measurements in Humberto showed highly variable CCN and CN concentrations that ranged from lots than 5 per cubic cm to more than 1000 per Cubic cm over km scale distances within and around the open eye of this tropical storm/hurricane. These very low concentrations suggest strong cloud scavenging.

  12. Cloud Condensation Nuclei Measurements in Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Hudson, J. G.; Simpson, J.

    2002-05-01

    The first measurements of cloud condensation nuclei (CCN) within and around tropical cyclones were made with the Desert Research Institute (DRI) CCN spectrometer (Hudson 1989) from a NOAA P-3 Hurricane Hunter aircraft throughout the 2001 season. Two penetrations of the closed eye of Hurricane Erin off the northeast US coast on Sept. 10 showed concentrations consistently well in excess of 1000 per cubic cm at approximately 1.4% supersaturation. Simultaneous condensation nuclei (CN--total particle) concentrations were consistently well in excess of 2000 per cubic cm throughout these closed eye penetrations. These within eye measurements at 4 km altitude far exceeded CCN and CN measurements just outside of the storm at similar altitudes--300 and 600 per cubic cm respectively. These CCN and CN concentrations within this closed eye were far above concentrations in maritime air masses; they are characteristic of continental or polluted air masses. Although there was a possibility that Saharan dust may have gotten into this storm these sub tenth micrometer particles are much too small and much too numerous to be dust. Such high concentrations may have originated from European air pollution, which may have been transported by similar airflow patterns to those that carry Saharan dust across the Atlantic. These high concentrations may be a manifestation of descending air that brings higher concentrations that are often characteristic of the upper troposphere (Clarke and Kapustin 2002). Later in the month measurements in Humberto showed highly variable CCN and CN concentrations that ranged from less than 5 per cubic cm to more than 1000 per cubic cm over km scale distances within and around the open eye of this tropical storm/hurricane. These very low concentrations suggest strong cloud scavenging. Clarke, A.D. and V.N. Kapustin, J. Atmos. Sci., 59, 363-382, 2002. Hudson, J.G., J. Atmos. & Ocean. Tech., 6, 1055-1065, 1989.

  13. Cloud Condensation Nuclei Measurements in Tropical Cyclones

    NASA Technical Reports Server (NTRS)

    Hudson, J. G.; Simpson, J.

    2002-01-01

    The first measurements of cloud condensation nuclei (CCN) within and around tropical cyclones were made with the Desert Research Institute (DRI) CCN spectrometer (Hudson 1909) from a NOAA P-3 Hurricane Hunter aircraft throughout the 2001 season. Two penetrations of the closed eye of Hurricane Erin off the northeast US coast on Sept. 10 showed concentrations consistently well in excess of 1000 per cubic cm at approximately 1.4% supersaturation. Simultaneous condensation nuclei (CN--total particle) concentrations were consistently well in excess of 2000 per cubic cm throughout these closed eye penetrations. These within eye measurements at 4 km altitude for exceeded CCN and CN measurements just outside of the storm at similar altitudes--300 and 600 per cubic cm respectively. These CCN and CN concentrations within this closed eye were far above concentrations in maritime air masses; they are characteristic of continental or polluted air masses. Although there was a possibility that Saharan duct may have gotten into this storm these sub tenth micrometer particles are much too small and much too numerous to be dust. Such high concentrations may have originated from European air pollution, which may have been transported by similar airflow patterns to those that carry Saharan dust across the Atlantic. These high concentrations may be a manifestation of descending air that brings higher concentrations that are often characteristic of the upper troposphere (Clarke and Kapustin 2002). Later in the month measurements in Humberto showed highly variable CCN and CN concentrations that ranged from lots than 5 per cubic cm to more than 1000 per Cubic cm over km scale distances within and around the open eye of this tropical storm/hurricane. These very low concentrations suggest strong cloud scavenging.

  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. 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.

  17. 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

  18. 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.

  19. Neutrino-induced nucleosynthesis of A>64 nuclei: the nu p process.

    PubMed

    Fröhlich, C; Martínez-Pinedo, G; Liebendörfer, M; Thielemann, F-K; Bravo, E; Hix, W R; Langanke, K; Zinner, N T

    2006-04-14

    We present a new nucleosynthesis process that we denote as the nu p process, which occurs in supernovae (and possibly gamma-ray bursts) when strong neutrino fluxes create proton-rich ejecta. In this process, antineutrino absorptions in the proton-rich environment produce neutrons that are immediately captured by neutron-deficient nuclei. This allows for the nucleosynthesis of nuclei with mass numbers A>64, , making this process a possible candidate to explain the origin of the solar abundances of (92,94)Mo and (96,98)Ru. This process also offers a natural explanation for the large abundance of Sr seen in a hyper-metal-poor star.

  20. Nuclear obscuration in active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Ramos Almeida, Cristina; Ricci, Claudio

    2017-09-01

    The material surrounding accreting supermassive black holes connects the active galactic nucleus with its host galaxy and, besides being responsible for feeding the black hole, provides important information on the feedback that nuclear activity produces on the galaxy. In this Review, we summarize our current understanding of the close environment of accreting supermassive black holes obtained from studies of local active galactic nuclei carried out in the infrared and X-ray regimes. The structure of this circumnuclear material is complex, clumpy and dynamic, and its covering factor depends on the accretion properties of the active galactic nucleus. In the infrared, this obscuring material is a transition zone between the broad- and narrow-line regions, and, at least in some galaxies, it consists of two structures: an equatorial disk/torus and a polar component. In the X-ray regime, the obscuration is produced by multiple absorbers across various spatial scales, mostly associated with the torus and the broad-line region. In the coming decade, the new generation of infrared and X-ray facilities will greatly contribute to our understanding of the structure and physical properties of nuclear obscuration in active galactic nuclei.

  1. Nuclear obscuration in active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Almeida, Cristina Ramos; Ricci, Claudio

    2017-10-01

    The material surrounding accreting supermassive black holes connects the active galactic nucleus with its host galaxy and, besides being responsible for feeding the black hole, provides important information on the feedback that nuclear activity produces on the galaxy. In this Review, we summarize our current understanding of the close environment of accreting supermassive black holes obtained from studies of local active galactic nuclei carried out in the infrared and X-ray regimes. The structure of this circumnuclear material is complex, clumpy and dynamic, and its covering factor depends on the accretion properties of the active galactic nucleus. In the infrared, this obscuring material is a transition zone between the broad- and narrow-line regions, and, at least in some galaxies, it consists of two structures: an equatorial disk/torus and a polar component. In the X-ray regime, the obscuration is produced by multiple absorbers across various spatial scales, mostly associated with the torus and the broad-line region. In the coming decade, the new generation of infrared and X-ray facilities will greatly contribute to our understanding of the structure and physical properties of nuclear obscuration in active galactic nuclei.

  2. STELLAR TRANSITS IN ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Beky, Bence; Kocsis, Bence E-mail: bkocsis@cfa.harvard.edu

    2013-01-01

    Supermassive black holes (SMBHs) are typically surrounded by a dense stellar population in galactic nuclei. Stars crossing the line of site in active galactic nuclei (AGNs) produce a characteristic transit light curve, just like extrasolar planets do when they transit their host star. We examine the possibility of finding such AGN transits in deep optical, UV, and X-ray surveys. We calculate transit light curves using the Novikov-Thorne thin accretion disk model, including general relativistic effects. Based on the expected properties of stellar cusps, we find that around 10{sup 6} solar mass SMBHs, transits of red giants are most common for stars on close orbits with transit durations of a few weeks and orbital periods of a few years. We find that detecting AGN transits requires repeated observations of thousands of low-mass AGNs to 1% photometric accuracy in optical, or {approx}10% in UV bands or soft X-ray. It may be possible to identify stellar transits in the Pan-STARRS and LSST optical and the eROSITA X-ray surveys. Such observations could be used to constrain black hole mass, spin, inclination, and accretion rate. Transit rates and durations could give valuable information on the circumnuclear stellar clusters as well. Transit light curves could be used to image accretion disks with unprecedented resolution, allowing us to resolve the SMBH silhouette in distant AGNs.

  3. 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.

  4. 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.

  5. Saturation with chiral interactions and consequences for finite nuclei

    NASA Astrophysics Data System (ADS)

    Simonis, J.; Stroberg, S. R.; Hebeler, K.; Holt, J. D.; Schwenk, A.

    2017-07-01

    We explore the impact of nuclear matter saturation on the properties and systematics of finite nuclei across the nuclear chart. By using the ab initio in-medium similarity renormalization group (IM-SRG), we study ground-state energies and charge radii of closed-shell nuclei from 4He to 78Ni based on a set of low-resolution two- and three-nucleon interactions that predict realistic saturation properties. We first investigate in detail the convergence properties of these Hamiltonians with respect to model-space truncations for both two- and three-body interactions. We find one particular interaction that reproduces well the ground-state energies of all closed-shell nuclei studied. As expected from their saturation points relative to this interaction, the other Hamiltonians underbind nuclei but lead to a remarkably similar systematics of ground-state energies. Extending our calculations to complete isotopic chains in the s d and p f shells with the valence-space IM-SRG, the same interaction reproduces not only experimental ground states but two-neutron-separation energies and first-excited 2+ states. We also extend the valence-space IM-SRG to calculate radii. Since this particular interaction saturates at too high density, charge radii are still too small compared with experiment. Except for this underprediction, the radius systematics is, however, well reproduced. Our results highlight the renewed importance of nuclear matter as a theoretical benchmark for the development of next-generation chiral interactions.

  6. Cloud condensation nuclei near marine cumulus

    NASA Technical Reports Server (NTRS)

    Hudson, James G.

    1993-01-01

    Extensive airborne measurements of cloud condensation nucleus (CCN) spectra and condensation nuclei below, in, between, and above the cumulus clouds near Hawaii point to important aerosol-cloud interactions. Consistent particle concentrations of 200/cu cm were found above the marine boundary layer and within the noncloudy marine boundary layer. Lower and more variable CCN concentrations within the cloudy boundary layer, especially very close to the clouds, appear to be a result of cloud scavenging processes. Gravitational coagulation of cloud droplets may be the principal cause of this difference in the vertical distribution of CCN. The results suggest a reservoir of CCN in the free troposphere which can act as a source for the marine boundary layer.

  7. Cloud condensation nuclei near marine cumulus

    NASA Technical Reports Server (NTRS)

    Hudson, James G.

    1993-01-01

    Extensive airborne measurements of cloud condensation nucleus (CCN) spectra and condensation nuclei below, in, between, and above the cumulus clouds near Hawaii point to important aerosol-cloud interactions. Consistent particle concentrations of 200/cu cm were found above the marine boundary layer and within the noncloudy marine boundary layer. Lower and more variable CCN concentrations within the cloudy boundary layer, especially very close to the clouds, appear to be a result of cloud scavenging processes. Gravitational coagulation of cloud droplets may be the principal cause of this difference in the vertical distribution of CCN. The results suggest a reservoir of CCN in the free troposphere which can act as a source for the marine boundary layer.

  8. International Symposium on Exotic Nuclei

    NASA Astrophysics Data System (ADS)

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

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

  9. 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.)

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Dynamical effects in fusion with exotic nuclei

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  19. How Close Is Close Reading?

    ERIC Educational Resources Information Center

    Saccomano, Doreen

    2014-01-01

    Close Reading is a strategy that can be used when reading challenging text. This strategy requires teachers to provide scaffolding, and create opportunities for think-alouds and rereading of text in order to help students become active readers who focus on finding text-based support for their answers. In addition, teachers must also be aware of…

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

    SciTech Connect

    De Angelis, Giacomo

    2008-11-11

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

  1. 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.

  2. 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.

  3. Production of actinide nuclei by multi-nucleon transfer

    SciTech Connect

    Lauritsen, T.; Ahmad, I.; Carpenter, M.P.

    1995-08-01

    Multi-nucleon transfers have increasingly allowed us to reach parts of the nuclear chart where regular compound nuclear reactions are prohibited. The interesting region of Ra and Rn, where a rich tapestry of nuclear structure manifests itself, is now accessible using this technique of deep inelastic scattering. In particular, these nuclei are predicted to lie at the onset of octupole deformation and the region is rich in examples of shape coexistence. There are several theoretical predictions of nuclear structure of these nuclei that have not been experimentally tested. Moreover, there is serious disagreement among these theories. We used a beam of {sup 136}Xe at 720 MeV from ATLAS on a target of {sup 232}Th to produce a range of Rn isotopes, with a mass from 220 to 224, and Ra isotopes with masses greater than 222. The beam energy, target and beam were selected carefully to enhance the cross-section for production of these nuclei and reduce the Doppler broadening of the gamma rays that were observed in the Argonne Notre Dame gamma-ray facility. The 12 germanium detectors of this array allowed the observation of gamma-gamma coincidences. The inner ball of 50 BGO detectors allowed us to record the multiplicity and sum-energy information for each event. The latter should permit us to determine the entry region in the products of the transfer reaction. We had four successful days of beam-time, when we collected in excess of 8 x 10{sup 7} events. Data analysis is in progress at the University of Liverpool. A complete set of spectroscopic information on the yrast structure of the many nuclei produced in this reaction is being extracted.

  4. Adaptive segmentation of nuclei in H&S stained tendon microscopy

    NASA Astrophysics Data System (ADS)

    Chuang, Bo-I.; Wu, Po-Ting; Hsu, Jian-Han; Jou, I.-Ming; Su, Fong-Chin; Sun, Yung-Nien

    2015-12-01

    Tendiopathy is a popular clinical issue in recent years. In most cases like trigger finger or tennis elbow, the pathology change can be observed under H and E stained tendon microscopy. However, the qualitative analysis is too subjective and thus the results heavily depend on the observers. We develop an automatic segmentation procedure which segments and counts the nuclei in H and E stained tendon microscopy fast and precisely. This procedure first determines the complexity of images and then segments the nuclei from the image. For the complex images, the proposed method adopts sampling-based thresholding to segment the nuclei. While for the simple images, the Laplacian-based thresholding is employed to re-segment the nuclei more accurately. In the experiments, the proposed method is compared with the experts outlined results. The nuclei number of proposed method is closed to the experts counted, and the processing time of proposed method is much faster than the experts'.

  5. 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.

  6. Medium-spin states of the neutron-rich 87,89Br isotopes: configurations and shapes

    NASA Astrophysics Data System (ADS)

    Nyakó, B. M.; Timár, J.; Csatlós, M.; Dombrádi, Zs; Krasznahorkay, A.; Kuti, I.; Sohler, D.; Tornyi, T. G.; Czerwiński, M.; Rząca-Urban, T.; Urban, W.; Bączyk, P.; Atanasova, L.; Balabanski, D. L.; Sieja, K.; Blanc, A.; Jentschel, M.; Köster, U.; Mutti, P.; Soldner, T.; de France, G.; Simpson, G. S.; Ur, C. A.

    2016-06-01

    Medium-spin excited states of the neutron-rich 87Br and 89Br nuclei were observed and studied for the first time. They were populated in fission of 235U induced by the cold-neutron beam of the PF1B facility of the Institut Laue-Langevin, Grenoble. The measurement of γ radiation following fission has been performed using the EXILL array of Ge detectors. The observed level schemes were compared with results of large valence space shell model calculations. Both medium-spin level schemes consist of band-like structures, which can be understood as bands built on the πf 5/2, πp 3/2 and πg 9/2 configurations. Both nuclei have 5/2- ground state spin-parity contrary to the odd-mass Br isotopes containing fewer neutrons, which have 3/2- ground state spin-parity. On the basis of the properties of the πg 9/2 decoupled bands the deformations of the 87Br and 89Br fit to the systematics of nuclei in the region. 87Br is close to the vibrational limit, while 89Br is more rotational.

  7. Epigenetics of eu- and heterochromatin in inverted and conventional nuclei from mouse retina.

    PubMed

    Eberhart, Anja; Feodorova, Yana; Song, Congdi; Wanner, Gerhard; Kiseleva, Elena; Furukawa, Takahisa; Kimura, Hiroshi; Schotta, Gunnar; Leonhardt, Heinrich; Joffe, Boris; Solovei, Irina

    2013-08-01

    To improve light propagation through the retina, the rod nuclei of nocturnal mammals are uniquely changed compared to the nuclei of other cells. In particular, the main classes of chromatin are segregated in them and form regular concentric shells in order; inverted in comparison to conventional nuclei. A broad study of the epigenetic landscape of the inverted and conventional mouse retinal nuclei indicated several differences between them and several features of general interest for the organization of the mammalian nuclei. In difference to nuclei with conventional architecture, the packing density of pericentromeric satellites and LINE-rich chromatin is similar in inverted rod nuclei; euchromatin has a lower packing density in both cases. A high global chromatin condensation in rod nuclei minimizes the structural difference between active and inactive X chromosome homologues. DNA methylation is observed primarily in the chromocenter, Dnmt1 is primarily associated with the euchromatic shell. Heterochromatin proteins HP1-alpha and HP1-beta localize in heterochromatic shells, whereas HP1-gamma is associated with euchromatin. For most of the 25 studied histone modifications, we observed predominant colocalization with a certain main chromatin class. Both inversions in rod nuclei and maintenance of peripheral heterochromatin in conventional nuclei are not affected by a loss or depletion of the major silencing core histone modifications in respective knock-out mice, but for different reasons. Maintenance of peripheral heterochromatin appears to be ensured by redundancy both at the level of enzymes setting the epigenetic code (writers) and the code itself, whereas inversion in rods rely on the absence of the peripheral heterochromatin tethers (absence of code readers).

  8. 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.

  9. 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.

  10. Isospin-symmetry-breaking effects in A˜70 nuclei within beyond-mean-field approach

    NASA Astrophysics Data System (ADS)

    Petrovici, A.; Andrei, O.

    2015-02-01

    Particular isospin-symmetry-breaking probes including Coulomb energy differences (CED), mirror energy differences (MED), and triplet energy differences (TED) manifest anomalies in the A˜70 isovector triplets of nuclei. The structure of proton-rich nuclei in the A˜70 mass region suggests shape coexistence and competition between pairing correlations in different channels. Recent results concerning the interplay between isospin-mixing and shape-coexistence effects on exotic phenomena in A˜70 nuclei obtained within the beyond-mean-field complex Excited Vampir variational model with symmetry projection before variation using a realistic effective interaction in a relatively large model space are presented. Excited Vampir predictions concerning the Gamow-Teller β decay to the odd-odd N=Z 66As and 70Br nuclei correlated with the pair structure analysis in the T=1 and T=0 channel of the involved wave functions are discussed.

  11. Isospin-symmetry-breaking effects in A∼70 nuclei within beyond-mean-field approach

    SciTech Connect

    Petrovici, A.; Andrei, O.

    2015-02-24

    Particular isospin-symmetry-breaking probes including Coulomb energy differences (CED), mirror energy differences (MED), and triplet energy differences (TED) manifest anomalies in the A∼70 isovector triplets of nuclei. The structure of proton-rich nuclei in the A∼70 mass region suggests shape coexistence and competition between pairing correlations in different channels. Recent results concerning the interplay between isospin-mixing and shape-coexistence effects on exotic phenomena in A∼70 nuclei obtained within the beyond-mean-field complex Excited Vampir variational model with symmetry projection before variation using a realistic effective interaction in a relatively large model space are presented. Excited Vampir predictions concerning the Gamow-Teller β decay to the odd-odd N=Z {sup 66}As and {sup 70}Br nuclei correlated with the pair structure analysis in the T=1 and T=0 channel of the involved wave functions are discussed.

  12. Localization of chromosome regions in potoroo nuclei ( Potorous tridactylus Marsupialia: Potoroinae).

    PubMed

    Rens, W; O'Brien, P C M; Graves, J A M; Ferguson-Smith, M A

    2003-08-01

    Chromosome paints of the rat kangaroo ( Aepyprymnus rufuscens, 2 n=32) were used to define chromosome regions in the long nosed potoroo ( Potorous tridactylus, 2 n=12 female, 13 male) karyotype and localize these regions in three-dimensionally preserved nuclei of the potoroo to test the hypothesis that marsupial chromosomes have a radial distribution. In human nuclei chromosomes are distributed in a proposed radial fashion. Gene-rich chromosomes in the human interphase nucleus are preferentially located in the central area while gene-poor chromosomes are found more at the periphery of the nucleus; this feature is conserved in primates and chicken. Chromosome ordering in nuclei of P. tridactylus is related to their size and centromere position. Its relationship with replication patterns in interphase nuclei and metaphase was studied. In addition it was observed that the nucleus was not a smooth entity but had projections occupied by specific chromosome regions.

  13. 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.

  14. 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.

  15. Close-up View of Homestake Vein

    NASA Image and Video Library

    2011-12-07

    This close-up view of a mineral vein called Homestake comes from the microscopic imager on NASA Mars Exploration Rover Opportunity; the vein is found to be rich in calcium and sulfur, possibly the calcium-sulfate mineral gypsum.

  16. 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.

  17. Evolution Of Shapes And Collectivity In Exotic Nuclei

    SciTech Connect

    Goergen, Andreas; Ljungvall, Joa

    2010-04-30

    The coexistence of prolate and oblate shapes in light selenium and krypton isotopes has been investigated using the complementary techniques of low-energy Coulomb excitation with radioactive ions beams and lifetime measurements of excited states after fusion-evaporation reactions. The resulting B(E2) values and spectroscopic quadrupole moments represent a sensitive test for configuration mixing calculations going beyond the mean-field approach. The onset of collectivity for neutron-rich nuclei near {sup 68}Ni has been investigated using a new technique to measure lifetimes with the recoil distance Doppler shift method after multi-nucleon transfer reactions.

  18. Whole-Cell Properties of Cerebellar Nuclei Neurons In Vivo.

    PubMed

    Canto, Cathrin B; Witter, Laurens; De Zeeuw, Chris I

    2016-01-01

    . Instead, using whole-cell parameters in combination with morphological criteria revealed by intracellular labelling with Neurobiotin (N = 18) allowed for electrophysiological identification of larger (29.3-50 μm soma diameter) and smaller (< 21.2 μm) cerebellar nuclei neurons with significant differences in membrane properties. Larger cells had a lower membrane resistance and a shorter spike, with a tendency for higher capacitance. Thus, in general cerebellar nuclei neurons appear to offer a rich and wide continuum of physiological properties that stand in contrast to neurons in most cortical regions such as those of the cerebral and cerebellar cortex, in which different classes of neurons operate in a narrower territory of electrophysiological parameter space. The current dataset will help computational modelers of the cerebellar nuclei to update and improve their cerebellar motor learning and performance models by incorporating the large variation of the in vivo properties of cerebellar nuclei neurons. The cellular complexity of cerebellar nuclei neurons may endow the nuclei to perform the intricate computations required for sensorimotor coordination.

  19. Whole-Cell Properties of Cerebellar Nuclei Neurons In Vivo

    PubMed Central

    De Zeeuw, Chris I.

    2016-01-01

    . Instead, using whole-cell parameters in combination with morphological criteria revealed by intracellular labelling with Neurobiotin (N = 18) allowed for electrophysiological identification of larger (29.3–50 μm soma diameter) and smaller (< 21.2 μm) cerebellar nuclei neurons with significant differences in membrane properties. Larger cells had a lower membrane resistance and a shorter spike, with a tendency for higher capacitance. Thus, in general cerebellar nuclei neurons appear to offer a rich and wide continuum of physiological properties that stand in contrast to neurons in most cortical regions such as those of the cerebral and cerebellar cortex, in which different classes of neurons operate in a narrower territory of electrophysiological parameter space. The current dataset will help computational modelers of the cerebellar nuclei to update and improve their cerebellar motor learning and performance models by incorporating the large variation of the in vivo properties of cerebellar nuclei neurons. The cellular complexity of cerebellar nuclei neurons may endow the nuclei to perform the intricate computations required for sensorimotor coordination. PMID:27851801

  20. Searching critical-point nuclei in Te- and Xe-isotopic chains using sextic oscillator potential

    SciTech Connect

    Kharb, S.; Chand, F.

    2012-02-15

    We have identified the nuclei in the Te- and Xe-isotopic chains lying close to the critical point, through which the shape phase transition occurs, by using the sextic oscillator potential formalism. It has been found that {sup 110}Te, {sup 124}Te, and {sup 124}Xe isotopes are the most promising candidates for the critical-point nuclei slightly above the Z = 50 proton shell closure.

  1. 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.

  2. 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.

  3. Active galactic nuclei: what's in a name?

    NASA Astrophysics Data System (ADS)

    Padovani, P.; Alexander, D. M.; Assef, R. J.; De Marco, B.; Giommi, P.; Hickox, R. C.; Richards, G. T.; Smolčić, V.; Hatziminaoglou, E.; Mainieri, V.; Salvato, M.

    2017-08-01

    Active galactic nuclei (AGN) are energetic astrophysical sources powered by accretion onto supermassive black holes in galaxies, and present unique observational signatures that cover the full electromagnetic spectrum over more than twenty orders of magnitude in frequency. The rich phenomenology of AGN has resulted in a large number of different "flavours" in the literature that now comprise a complex and confusing AGN "zoo". It is increasingly clear that these classifications are only partially related to intrinsic differences between AGN and primarily reflect variations in a relatively small number of astrophysical parameters as well the method by which each class of AGN is selected. Taken together, observations in different electromagnetic bands as well as variations over time provide complementary windows on the physics of different sub-structures in the AGN. In this review, we present an overview of AGN multi-wavelength properties with the aim of painting their "big picture" through observations in each electromagnetic band from radio to γ -rays as well as AGN variability. We address what we can learn from each observational method, the impact of selection effects, the physics behind the emission at each wavelength, and the potential for future studies. To conclude, we use these observations to piece together the basic architecture of AGN, discuss our current understanding of unification models, and highlight some open questions that present opportunities for future observational and theoretical progress.

  4. Metal-poor Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Bicalho, I. C.; Telles, E.

    2014-10-01

    Active galaxies are considered to be metal-rich, with metallicity ranging from solar to slightly supersolar. This is due to the fact that the active galaxy nuclei are usually found in supermassive galaxies. We aim to test this statement by obtaining near infrared spectra of peculiar dwarf galaxies to see if they host an AGN. We present the results based on analysis of data from Gemini Near Infrared Integral Field Spectrograph (NIFS) of the metal-poor HII galaxy SDSS J1047+0739 (12 + log O/H ˜ 7.85 ± 0.02). The spectrum of this galaxy shows strong permitted emission lines with extended wings, which is atypical for HII regions. We use unconventional methods such as PCA tomography due to the benefits that it provides to data cube analysis. We are studying the kinematics of the nuclear region and the regions of star formation surrounding it, mostly through the Paschen-α and He lines. We find that the broad line emission comes only from the unresolved central region. The results of this analysis agree well with the existence of an AGN in this metal-poor galaxy.

  5. Graph-based segmentation of abnormal nuclei in cervical cytology.

    PubMed

    Zhang, Ling; Kong, Hui; Liu, Shaoxiong; Wang, Tianfu; Chen, Siping; Sonka, Milan

    2017-03-01

    A general method is reported for improving the segmentation of abnormal cell nuclei in cervical cytology images. In automation-assisted reading of cervical cytology, one of the essential steps is the segmentation of nuclei. Despite some progress, there is a need to improve the sensitivity, particularly the segmentation of abnormal nuclei. Our method starts with pre-segmenting the nucleus to define the coarse center and size of nucleus, which is used to construct a graph by image unfolding that maps ellipse-like border in the Cartesian coordinate system to lines in the polar coordinate system. The cost function jointly reflects properties of nucleus border and nucleus region. The prior constraints regarding the context of nucleus-cytoplasm position are utilized to modify the local cost functions. The globally optimal path in the constructed graph is then identified by dynamic programming with an iterative approach ensuring an optimal closed contour. Validation of our method was performed on abnormal nuclei from two cervical cell image datasets, Herlev and H&E stained manual liquid-based cytology (HEMLBC). Compared with five state-of-the-art approaches, our graph-search based method shows superior performance.

  6. IBM-1 calculations towards the neutron-rich nucleus {sup 106}Zr

    SciTech Connect

    Lalkovski, Stefan

    2009-04-15

    The neutron-rich N=66 isotonic and A=106 isobaric chains, covering regions with varying types of collectivity, are interpreted in the framework of the interacting boson model. Level energies and electric quadrupole transition probabilities are compared with available experimental information. The calculations for the known nuclei in the two chains are extrapolated toward the neutron-rich nucleus {sup 106}Zr.

  7. Deep Inelastic Transfer Reactions - A New Way to Exotic Nuclei?

    NASA Astrophysics Data System (ADS)

    Heinz, Sophie; Beliuskina, Olga

    2014-05-01

    We studied deep inelastic multinucleon transfer reactions in collisions of 64Ni+207Pb and 48Ca+238U at energies around the Coulomb barrier. The experiments were performed at the velocity filter SHIP at GSI Darmstadt. One of the goals was to investigate if deep inelastic transfer is superior to fragmentation reactions for producing neutron-rich isotopes in the astrophysically interesting region of nuclei along the magic neutron number N = 126. With both collision systems, rather neutron-rich transfer products were populated, some of them reaching out to the limits of the present chart of nuclides. New isotopes could not be identified. A comparison of the measured transfer cross-sections and yields with those from fragmentation reactions allowed for interesting conclusions.

  8. Production Uncertainties of p-Nuclei in the γ-Process in Massive Stars Using a Monte Carlo Approach

    NASA Astrophysics Data System (ADS)

    Rauscher, T.; Nishimura, N.; Hirschi, R.; Cescutti, G.; Murphy, A. St. J.; Heger, A.

    Proton-rich nuclei, the so-called p-nuclei, are made in photodisintegration processes in outer shells of massive stars in the course of the final supernova explosion. Nuclear uncertainties in the production of these nuclei have been quantified in a Monte Carlo procedure. Bespoke temperature-dependent uncertainties were assigned to different types of reactions involving nuclei from Fe to Bi and all rates were varied randomly within the uncertainties. The resulting total production uncertainties of the p-nuclei are below a factor of two, with few exceptions. Key reactions dominating the final uncertainties have been identified in an automated procedure using correlations between rate and abundance uncertainties. Our results are compared to those of a previous study manually varying reaction rates.

  9. Momentum distributions in light halo nuclei and structure constraints

    NASA Astrophysics Data System (ADS)

    Souza, L. A.; Bellotti, F. F.; Frederico, T.; Yamashita, M. T.; Tomio, Lauro

    2016-03-01

    The core recoil momentum distribution of neutron-rich isotopes of light exotic nuclei is studied within a three-body model, where the nuclei are described by a core and two neutrons, with interactions dominated by the s-wave channel. In our framework, the two-body subsystems should have large scattering lengths in comparison with the interaction range allowing to use a three-body model with a zero-range force. The ground-state halo wave functions in momentum space are obtained by using as inputs the two-neutron separation energy and the energies of the singlet neutron-neutron and neutron-core virtual states. Within our model, we obtain the momentum probability densities for the Borromean exotic nuclei 11Li and 22C. In the case of the core recoil momentum distribution of 11Li, a fair reproduction of the experimental data was obtained, without free parameters, considering only the two-body low-energies. By analysing the obtained core momentum distribution in face of recent experimental data, we verify that such data are constraining the 22C two-neutron separation energy to a value between 100 and 400 keV.

  10. The Array for Nuclear Astrophysics Studies with Exotic Nuclei (anasen)

    NASA Astrophysics Data System (ADS)

    Matos, M.; Blackmon, J. C.; Gardiner, H. E.; Linhardt, L. E.; Macon, K. T.; Mondello, L. L.; Baby, L.; Johnson, E.; Koshchiy, E.; Rogachev, G.; Wiedenhöver, I.; Bardayan, D. W.

    2013-03-01

    Experimental information about most reactions involving short-lived nuclei is limited. New facilities aim to provide wider access to unstable isotopes, but the limited intensities require more efficient and selective techniques and devices. The Array for Nuclear Astrophysics Studies with Exotic Nuclei (ANASEN) is a charged-particle detector array designed primarily for studies of reactions important in the αp- and rp- processes with proton-rich exotic nuclei. The array consists of 40 silicon-strip detectors backed with CsI scintillators. The detectors cover an area of about 1300 cm2 providing essentially complete solid angle coverage for the reactions of interest with good energy and position resolution. ANASEN also includes a position-sensitive annular gas proportional counter that allows it to be used as an active gas target/detector. ANASEN is designed for direct measurement of (α,p) re-actions in inverse kinematics as well as for studies of proton elastic and inelastic scattering, (p, γ) reactions and transfer reactions. The array is being developed by Louisiana State University and Florida State University. Presently it is located at the RESOLUT radioacitve ion beam facility at FSU, where the first experiments are being performed. In the future, the array will be used at the ReA3 facility at the National Superconducting Cyclotron Laboratory.

  11. Spectroscopy of Actinide Nuclei - Perspectives with Position Sensitive HPGe Detectors

    NASA Astrophysics Data System (ADS)

    Reiter, P.; Birkenbach, B.; Kotthaus, T.

    Recent advances in in-beam gamma-ray spectroscopy of actinide nuclei are based on highly efficient arrays of escape-suppressed spectrometers. The sensitivity of these detector arrays is greatly enhanced by the combination with powerful mass separators or particle detector systems. This technique is demonstrated by an experiment to investigate excited states in 234U after the one-neutron-transfer reaction 235U(d,t). In coincidence with the outgoing tritons, γ-rays were detected with the highly efficient MINIBALL spectrometer. In the near future an even enhanced sensitivity will be achieved by utilizing position sensitive HPGe detectors which will exploit the novel detection method of gamma-ray energy tracking in electrically segmented germanium detectors. An example for this novel approach is the investigation neutron-rich actinide Th and U nuclei after multi nucleon transfer reactions employing the AGATA demonstrator and PRISMA setup at LNL, Italy. A primary 136Xe beam hitting a 238U target was used to produce the nuclei of interest. Beam-like reaction products after neutron transfer were selected by the PRISMA spectrometer. Coincident γ-rays from excited states in beam and target like particles were measured with the position sensitive AGATA HPGe detectors. Improved Doppler correction and quality of the γ-spectra is based on the novel γ-ray tracking technique, which was successfully exploited in this region.

  12. Close supermassive binary black holes.

    PubMed

    Gaskell, C Martin

    2010-01-07

    It has been proposed that when the peaks of the broad emission lines in active galactic nuclei (AGNs) are significantly blueshifted or redshifted from the systemic velocity of the host galaxy, this could be a consequence of orbital motion of a supermassive black-hole binary (SMBB). The AGN J1536+0441 ( = SDSS J153636.22+044127.0) has recently been proposed as an example of this phenomenon. It is proposed here instead that J1536+0441 is an example of line emission from a disk. If this is correct, the lack of clear optical spectral evidence for close SMBBs is significant, and argues either that the merging of close SMBBs is much faster than has generally been hitherto thought, or if the approach is slow, that when the separation of the binary is comparable to the size of the torus and broad-line region, the feeding of the black holes is disrupted.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

    Background: Recent observational data on neutron star masses and radii provide stringent constraints on the equation of state of neutron rich matter [Annu. Rev. Nucl. Part. Sci.ARPSDF0163-899810.1146/annurev-nucl-102711-095018 62, 485 (2012)].Purpose: We aim to develop a nuclear energy density functional that can be simultaneously applied to finite nuclei and neutron stars.Methods: We use the self-consistent nuclear density functional theory (DFT) with Skyrme energy density functionals and covariance analysis to assess correlations between observables for finite nuclei and neutron stars. In a first step two energy functionals—a high density energy functional giving reasonable neutron properties, and a low density functional fitted to nuclear properties—are matched. In a second step, we optimize a new functional using exactly the same protocol as in earlier studies pertaining to nuclei but now including neutron star data. This allows direct comparisons of performance of the new functional relative to the standard one.Results: The new functional TOV-min yields results for nuclear bulk properties (energy, rms radius, diffraction radius, and surface thickness) that are of the same quality as those obtained with the established Skyrme functionals, including SV-min. When comparing SV-min and TOV-min, isoscalar nuclear matter indicators vary slightly while isovector properties are changed considerably. We discuss neutron skins, dipole polarizability, separation energies of the heaviest elements, and proton and neutron drip lines. We confirm a correlation between the neutron skin of 208Pb and the neutron star radius.Conclusions: We demonstrate that standard energy density functionals optimized to nuclear data do not carry information on the expected maximum neutron star mass, and that predictions can only be made within an extremely broad uncertainty band. For atomic nuclei, the new functional TOV-min performs at least as well as the standard nuclear functionals, but

  18. Photoneutron cross sections for unstable neutron-rich oxygen isotopes.

    PubMed

    Leistenschneider, A; Aumann, T; Boretzky, K; Cortina, D; Cub, J; Datta Pramanik, U; Dostal, W; Elze, T W; Emling, H; Geissel, H; Grünschloss, A; Hellstr, M; Holzmann, R; Ilievski, S; Iwasa, N; Kaspar, M; Kleinböhl, A; Kratz, J V; Kulessa, R; Leifels, Y; Lubkiewicz, E; Münzenberg, G; Reiter, P; Rejmund, M; Scheidenberger, C; Schlegel, C; Simon, H; Stroth, J; Sümmerer, K; Wajda, E; Walús, W; Wan, S

    2001-06-11

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

  19. Search for octupole deformation in neutron rich Xe isotopes

    SciTech Connect

    Bentaleb, M.; Schulz, N.; Lubkiewicz, E.

    1994-07-01

    A search for octupole deformation in neutron rich Xe isotopes has been conducted through gamma-ray spectroscopy of primary fragments produced in the spontaneous fission of {sup 248}Cm. The spectrometer consisted of the Eurogam array and a set of 5 LEPS detectors. Level schemes were constructed for Xe isotopes with masses ranging from 138 to 144. Except for {sup 139}Xe, none of them exhibit an alternating parity quasimolecular band, {alpha} feature usually encountered in octupole deformed nuclei. Substantial evidence for reflection asymmetric shape in the intrinsic system of the nucleus exists for the light actinide nuclei.

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Segregation of parallel inputs to the anteromedial and anteroventral thalamic nuclei of the rat.

    PubMed

    Wright, Nicholas F; Vann, Seralynne D; Erichsen, Jonathan T; O'Mara, Shane M; Aggleton, John P

    2013-09-01

    Many brain structures project to both the anteroventral thalamic nucleus and the anteromedial thalamic nucleus. In the present study, pairs of different tracers were placed into these two thalamic sites in the same rats to determine the extent to which these nuclei receive segregated inputs. Only inputs from the laterodorsal tegmental nucleus, the principal extrinsic cholinergic source for these thalamic nuclei, showed a marked degree of collateralization, with approximately 13% of all cells labeled in this tegmental area projecting to both nuclei. Elsewhere, double-labeled cells were very scarce, making up ∼1% of all labeled cells. Three general patterns of anterior thalamic innervation were detected in these other areas. In some sites, e.g., prelimbic cortex, anterior cingulate cortex, and secondary motor area, cells projecting to the anteromedial and anteroventral thalamic nuclei were closely intermingled, with often only subtle distribution differences. These same projections were also often intermingled with inputs to the mediodorsal thalamic nucleus, but again there was little or no collateralization. In other sites, e.g., the subiculum and retrosplenial cortex, there was often less overlap of cells projecting to the two anterior thalamic nuclei. A third pattern related to the dense inputs from the medial mammillary nucleus, where well-defined topographies ensured little intermingling of the neurons that innervate the two thalamic nuclei. The finding that a very small minority of cortical and limbic inputs bifurcates to innervate both anterior thalamic nuclei highlights the potential for parallel information streams to control their functions, despite arising from common regions.

  11. Disappearance of Z=120 & 126 magicity and presence of hyper deformations in superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Sharma, M. M.; Farhan, A. R.

    2012-10-01

    Conventional wisdom has it that Z=120 and especially Z=126 are predicted to be magic numbers for extreme superheavy nuclei. We have undertaken a study of structure of superheavy nuclei in the region of Z=120 to Z=126 within the framework of the deformed relativistic Hartree-Bogoliubov (DRHB) approach. Nuclei in this region entail a large density of states and are thus susceptible to a coupling to the continuum especially those which are close to being proton unbound. The DRHB approach which takes into account the coupling to the continuum is suitable for nuclei in the end of the periodic table. Additionally, the pairing in this approach is included within the Bogoliubov quasi-particle scheme, which takes into account the shell gap at the Fermi surface appropriately. Using the successful Lagrangian model NL-SV1 [1] based upon the vector self-coupling of φ-meson, it is shown that the perceived shell gaps at Z=120 and Z=126 disappear, thus making these proton numbers as non-magic. It is also shown that due to very large Coulomb force acting in these nuclei which are virtually at the end of the periodic table, stability to the nuclei in this region is brought about by extremely large elongated shapes with β2 ˜ 0.70-0.80. Consequences on formation of superheavy nuclei in this region will be discussed.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. β-delayed Neutron Decay Studies of r-process Nuclei near ^137Sb

    NASA Astrophysics Data System (ADS)

    Santi, P.; Schatz, H.; Mahmud, H.; Woods, P. J.; Attallah, F.; Geissel, H.; Hausmann, M.; Hellström, M.; Münzenberg, G.; Scheidenberger, C.; Schmidt, K.; Sümmerer, K.; Stadlmann, J.; Mineva, M. N.; Hannawald, M.; Kratz, K.-L.; Pfeiffer, B.; Faestermann, T.; Schneider, R.; Stolz, A.; Wefers, E.; Giesen, U.

    2002-10-01

    In order to understand r-process nucleosynthesis, it is necessary to know the β-decay half lives and neutron emission probabilities (P_n) of the neutron rich nuclei which lie along the r-process path. To this end an experiment was performed at GSI to measure the T_1/2 and Pn values of r-process nuclei around the waiting-point nucleus ^137Sb. The nuclei of interest were produced via the projectile fission of a 750 MeV/nucleon ^238U beam and identified using the FRS fragment separator. A stack of 4 double-sided silicon strip detectors were used to detect the implanted nuclei and subsequent β-decays. Neutrons emitted from β-delayed neutron decays were detected using the Mainz 4π neutron long counter. A set of approximately 10 r-process nuclei in the A=130 region, including the waiting-point nuclei ^136Sn and ^137Sb, were measured during the experiment. Preliminary results of the experiment will be discussed.

  18. Dilute Excited States in Light Nuclei

    NASA Astrophysics Data System (ADS)

    Demyanova, A. S.; Ogloblin, A. A.; Danilov, A. N.; Goncharov, S. A.; Belyaeva, T. L.; Trzaska, W. H.

    2015-11-01

    A review of measurements of the radii of 11B, 12C and 13C nuclei in some excited states, whose structure recently attracted a lot of attention, is presented. The differential cross-sections of the inelastic α-scattering were measured. The radii values were extracted from the date using the Modified Diffraction Model (MDM). The evidence that the famous Hoyle state (0+, 7.65 MeV) in 12C has the enhanced dimensions and is the head of a new rotational band (besides the known band based on the 12C ground state) was obtained. The radius of the second 2+ member state (E* = 9.8 or 9.6 MeV) was seen to be similar to that of the Hoyle state (~3.0 fm). A 4+ state was identified at E* = 13.75 MeV. The radii of the 8.86 MeV, 1/2- state in 13C and 8.56 MeV, 3/2- state in 11B are found to be close to that of the Hoyle state and these states can be considered as analogues of the latter. Comparison of the data with the predictions of some theoretical models, e.g., alpha condensation, has been made. The obtained results show that one may speak only about rudimentary manifestation of the condensate effects.

  19. Multispectral comparison of water ice deposits observed on cometary nuclei

    NASA Astrophysics Data System (ADS)

    Oklay Vincent, Nilda; Sunshine, Jessica M.; Pajola, Maurizio; Pommerol, Antoine; Vincent, Jean-Baptiste; Sierks, Holger; OSIRIS Team

    2016-10-01

    Cometary missions Deep Impact, EPOXI and Rosetta investigated the nuclei of comets 9P/Tempel 1, 103P/Hartley 2 and 67P/Churyumov-Gerasimenko respectively. Each of these three missions was equipped with multispectral cameras, allowing imaging at various wavelengths from NUV to NIR. In this spectral range, water ice-rich features display bluer spectral slopes than the average surface and some have very flat spectra. Features enriched in water ice are bright in the monochromatic images and are blue in the RGB color composites generated by using images taken in NUV, visible and NIR wavelentghs. Using these properties, water ice-rich features were detected on the nuclei of comets 9P [1], 103P [2] and 67P [3] via multispectral imaging cameras. Moreover, there were visual detections of jets and outbursts associated to some of these water ice-rich features when the right observing conditions were fulfilled [4, 5].We analyzed multispectral properties of different types of water ice-rich features [3] observed via OSIRIS NAC on comet 67P in the wavelength range of 260 nm to 1000 nm and then compared with those observed on comets 9P and 103P. Our multispectral analysis shows that the water ice deposits observed on comet 9P are very similar to the large bright blue clusters observed on comet 67P, while the large water ice deposit observed on comet 103P is similar to the large isolated water ice-rich features observed on comet 67P. The ice-rich deposits on comet 103P are the bluest of any comet, which indicates that the deposits on 103P contain more water ice than the ones observed on comets 9P and 67P [6].[1] Sunshine et al 2006, Science[2] Sunshine et al 2011, LPSC[3] Pommerol et al 2015, A&A[4] Oklay et al 2016, A&A[5] Vincent et al 2016, A&A[6] Oklay et al 2016, submitted

  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 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.

  1. β -Decay Half-Lives of 110 Neutron-Rich Nuclei across the N=82 Shell Gap: Implications for the Mechanism and Universality of the Astrophysical r Process

    SciTech Connect

    Lorusso, G.; Nishimura, S.; Xu, Z. Y.; Jungclaus, A.; Shimizu, Y.; Simpson, G. S.; Söderström, P. -A.; Watanabe, H.; Browne, F.; Doornenbal, P.; Gey, G.; Jung, H. S.; Meyer, B.; Sumikama, T.; Taprogge, J.; Vajta, Zs.; Wu, J.; Baba, H.; Benzoni, G.; Chae, K. Y.; Crespi, F. C. L.; Fukuda, N.; Gernhäuser, R.; Inabe, N.; Isobe, T.; Kajino, T.; Kameda, D.; Kim, G. D.; Kim, Y. -K.; Kojouharov, I.; Kondev, F. G.; Kubo, T.; Kurz, N.; Kwon, Y. K.; Lane, G. J.; Li, Z.; Montaner-Pizá, A.; Moschner, K.; Naqvi, F.; Niikura, M.; Nishibata, H.; Odahara, A.; Orlandi, R.; Patel, Z.; Podolyák, Zs.; Sakurai, H.; Schaffner, H.; Schury, P.; Shibagaki, S.; Steiger, K.; Suzuki, H.; Takeda, H.; Wendt, A.; Yagi, A.; Yoshinaga, K.

    2015-05-01

    The β -decay half-lives of 110 neutron-rich isotopes of the elements from Rb 37 to Sn 50 were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for r -process calculations and reinforce the notion that the second (A≈130 ) and the rare-earth-element (A≈160 ) abundance peaks may result from the freeze-out of an (n,γ)⇌(γ,n) equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the r process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual r -process events.

  2. Rich catalytic injection

    SciTech Connect

    Veninger, Albert

    2008-12-30

    A gas turbine engine includes a compressor, a rich catalytic injector, a combustor, and a turbine. The rich catalytic injector includes a rich catalytic device, a mixing zone, and an injection assembly. The injection assembly provides an interface between the mixing zone and the combustor. The injection assembly can inject diffusion fuel into the combustor, provides flame aerodynamic stabilization in the combustor, and may include an ignition device.

  3. Hydrogen rich gas generator

    NASA Technical Reports Server (NTRS)

    Houseman, J. (Inventor)

    1976-01-01

    A process and apparatus is described for producing a hydrogen rich gas by introducing a liquid hydrocarbon fuel in the form of a spray into a partial oxidation region and mixing with a mixture of steam and air that is preheated by indirect heat exchange with the formed hydrogen rich gas, igniting the hydrocarbon fuel spray mixed with the preheated mixture of steam and air within the partial oxidation region to form a hydrogen rich gas.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Informing Neutron-Capture Rates through (d,p) Reactions on Neutron-Rich Tin Isotopes

    NASA Astrophysics Data System (ADS)

    Manning, B.; Cizewski, J. A.; Kozub, R. L.; Ahn, S.; Allmond, J. M.; Bardayan, D. W.; Chae, K. Y.; Chipps, K. A.; Howard, M. E.; Jones, K. L.; Liang, J. F.; Matos, M.; Nunes, F. M.; Nesaraja, C. D.; O'Malley, P. D.; Pain, S. D.; Peters, W. A.; Pittman, S. T.; Ratkiewicz, A.; Schmitt, K. T.; Shapira, D.; Smith, M. S.; Titus, L.

    2014-03-01

    Level energies and spectroscopic information for neutron-rich nuclei provide important input for r-process nucleosynthesis calculations; specifically, the location and strength of single-neutron l = 1 states when calculating neutron-capture rates. Surman and collaborators have performed sensitivity studies to show that varying neutron-capture rates can significantly alter final r-process abundances. However, there are many nuclei important to the r-process that cannot be studied. Extending studies to more neutron-rich nuclei will help constrain the nuclear shell-model in extrapolating to nuclei even further from stability. The (d,p) reaction has been measured with radioactive ion beams of 126Sn and 128Sn to complete the set of (d,p) studies on even mass tin isotopes from doubly-magic 132 to stable 124Sn. Work supported in part by the U.S. Department of Energy and National Science Foundation.

  12. Research: Rags to Rags? Riches to Riches?

    ERIC Educational Resources Information Center

    Bracey, Gerald W.

    2004-01-01

    Everyone has read about what might be called the "gold gap"--how the rich in this country are getting richer and controlling an ever-larger share of the nation's wealth. The Century Foundation has started publishing "Reality Check", a series of guides to campaign issues that sometimes finds gaps in these types of cherished delusions. The guides…

  13. 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.

  14. 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-...

  15. 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.

  16. Prostate cancer grading: use of graph cut and spatial arrangement of nuclei.

    PubMed

    Nguyen, Kien; Sarkar, Anindya; Jain, Anil K

    2014-12-01

    Tissue image grading is one of the most important steps in prostate cancer diagnosis, where the pathologist relies on the gland structure to assign a Gleason grade to the tissue image. In this grading scheme, the discrimination between grade 3 and grade 4 is the most difficult, and receives the most attention from researchers. In this study, we propose a novel method (called nuclei-based method) that 1) utilizes graph theory techniques to segment glands and 2) computes a gland-score (based on the spatial arrangement of nuclei) to estimate how similar a segmented region is to a gland. Next, we create a fusion method by combining this nuclei-based method with the lumen-based method presented in our previous work to improve the performance of grade 3 versus grade 4 classification problem (the accuracy is now improved to 87.3% compared to 81.1% of the lumen-based method alone). To segment glands, we build a graph of nuclei and lumina in the image, and use the normalized cut method to partition the graph into different components, each corresponding to a gland. Unlike most state-of-the-art lumen-based gland segmentation method, the nuclei-based method is able to segment glands without lumen or glands with multiple lumina. Moreover, another important contribution in this research is the development of a set of measures to exploit the difference in nuclei spatial arrangement between grade 3 images (where nuclei form closed chain structure on the gland boundary) and grade 4 image (where nuclei distribute more randomly in the gland). These measures are combined to generate a single gland-score value, which estimates how similar a segmented region (which is a set of nuclei and lumina) is to a gland.

  17. Global patterns of species richness and climate

    SciTech Connect

    Currie, D.J. )

    1994-06-01

    Why are there many species in some places and few in others Several studies have shown that the variation in the number of species over continent-sized areas is closely related to the variation in macroclimatic factors: heat and moisture for terrestrial plants, and heat for terrestrial vertebrates. Yet, most of these studies dealt primarily with temperature areas on single continents. If contemporary climate is the principle determinant of large-scale patterns of richness, then richness should be related to climate in similar ways on different continents, regardless of their evolutionary histories. To test the hypothesis, we have gathered published data on the distributions of birds and mammals in temperature and tropical areas. We found that richness varies as a function of potential evapotranspiration in very similar ways on different continents in temperate areas, although there is some significant variation among continents that is unrelated to climate. In tropical areas, richness is more closely related to precipitation and annual climatic variability. Re-analysis of published data on plant richness is consistent with these observations. We conclude that most of the variation in large-scale patterns of species richness can be accounted for by contemporary climate.

  18. Variability of the central region in active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Wallinder, F. H.; Kato, S.; Abramowicz, M. A.

    We review implications of the observed optical and X-ray variability (periodicities and light-curves), relevant for the understanding of physical conditions in the deep interiors of active galactic nuclei. We discuss in detail kinematical, hydrodynamical, thermal and radiative transfer effects which are theorized to be responsible for observed variability patterns. We put emphasis on theoretical options which can predict basic accretion parameters, such as the mass of the central black hole, the accretion rate, and the inclination angle, in terms of observable quantities. Closed analytical results are given whenever available.

  19. Adiabatic-nuclei calculations of positron scattering from molecular hydrogen

    DOE PAGES

    Zammit, Mark Christian; Fursa, Dmitry V.; Savage, Jeremy S.; ...

    2017-02-06

    The single-center adiabatic-nuclei convergent close-coupling method is used to investigate positron collisions with molecular hydrogen (H2) in the ground and first vibrationally excited states. Cross sections are presented over the energy range from 1 to 1000 eV for elastic scattering, vibrational excitation, total ionization, and the grand total cross section. The present adiabatic-nuclei positron- H2 scattering length is calculated as A = $-$ 2.70 a0 for the ground state and A = $-$ 3.16 a0 for the first vibrationally excited state. The present elastic differential cross sections are also used to “correct” the low-energy grand total cross-section measurements of themore » Trento group [A. Zecca et al., Phys. Rev. A 80, 032702 (2009)] for the forward-angle-scattering effect. In general, the comparison with experiment is good. In conclusion, by performing convergence studies, we estimate that our Rm = 1.448 a0 fixed-nuclei results are converged to within ± 5 % for the major scattering integrated cross sections.« less

  20. Adiabatic-nuclei calculations of positron scattering from molecular hydrogen

    NASA Astrophysics Data System (ADS)

    Zammit, Mark C.; Fursa, Dmitry V.; Savage, Jeremy S.; Bray, Igor; Chiari, Luca; Zecca, Antonio; Brunger, Michael J.

    2017-02-01

    The single-center adiabatic-nuclei convergent close-coupling method is used to investigate positron collisions with molecular hydrogen (H2) in the ground and first vibrationally excited states. Cross sections are presented over the energy range from 1 to 1000 eV for elastic scattering, vibrational excitation, total ionization, and the grand total cross section. The present adiabatic-nuclei positron-H2 scattering length is calculated as A =-2.70 a0 for the ground state and A =-3.16 a0 for the first vibrationally excited state. The present elastic differential cross sections are also used to "correct" the low-energy grand total cross-section measurements of the Trento group [A. Zecca et al., Phys. Rev. A 80, 032702 (2009), 10.1103/PhysRevA.80.032702] for the forward-angle-scattering effect. In general, the comparison with experiment is good. By performing convergence studies, we estimate that our Rm=1.448 a0 fixed-nuclei results are converged to within ±5 % for the major scattering integrated cross sections.

  1. 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...

  2. Mass Measurements of Proton-rich Nuclides at the Cooler Storage Ring at IMP

    SciTech Connect

    Zhang, Y. H.; Xu, H. S.; Wang, M.; Zhou, X. H.; Yuan, Y. J.; Xia, J. W.; Hu, Z. G.; Huang, W. X.; Liu, Y.; Ma, X.; Mao, R. S.; Mei, B.; Sun, Z. Y.; Wang, J. S.; Xiao, G. Q.; Yan, X. L.; Yang, J. C.; Zhao, H. W.; Zhao, T. C.; Zhang, X. Y.; and others

    2011-11-30

    Recent results and progress of mass measurements of proton-rich nuclei using isochronous mass spectrometry (IMS) are reported. The nuclei under investigation were produced via fragmentation of relativistic energy heavy ions of {sup 78}Kr and {sup 58}Ni. After in-flight separation by the fragment separator RIBLL-2, the nuclei were injected and stored in the experimental storage ring CSRe, and their masses were determined from measurements of the revolution times. The impact of these measurements on the stellar nucleosynthesis in the rp-process is discussed.

  3. Hybrid theory and calculation of e-N2 scattering. [quantum mechanics - nuclei (nuclear physics)

    NASA Technical Reports Server (NTRS)

    Chandra, N.; Temkin, A.

    1975-01-01

    A theory of electron-molecule scattering was developed which was a synthesis of close coupling and adiabatic-nuclei theories. The theory is shown to be a close coupling theory with respect to vibrational degrees of freedom but is a adiabatic-nuclei theory with respect to rotation. It can be applied to any number of partial waves required, and the remaining ones can be calculated purely in one or the other approximation. A theoretical criterion based on fixed-nuclei calculations and not on experiment can be given as to which partial waves and energy domains require the various approximations. The theory allows all cross sections (i.e., pure rotational, vibrational, simultaneous vibration-rotation, differential and total) to be calculated. Explicit formulae for all the cross sections are presented.

  4. 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.

  5. 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

  6. 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.

  7. Sensitivity of p-Nuclei to (n,g) Reaction Rates

    NASA Astrophysics Data System (ADS)

    Scriven, Dustin; Naqvi, Farheen; Spyrou, Artemis; Simon, Anna; Mayer, Brad

    2015-10-01

    The astrophysical p-process, which is responsible for the creation of the proton-rich p-nuclei, is still not well understood. A sensitivity study of p-nuclei abundances to (n, γ) and (γ,n) reaction rates was conducted at the National Superconducting Cyclotron Laboratory using a nuclear reaction network created at Clemson University. This network simulates the explosive shock front of a Type II supernova passing through the oxygen/neon layer of a 25 M⊙ star. Reaction rates of many (n, γ) reactions and their inverses were increased and decreased by a factor of 3 and the effects were observed. Probing the sensitivity of p-nuclei abundances aids in pointing out reactions important to the p-process. In turn, this information can be used as a tool to drive experimental research, helping to decrease uncertainties and increase the robustness of p-process and other stellar models.

  8. Comparative anatomical studies on the cerebellar nuclei of the pangolins.

    PubMed

    Ishimoto, Y

    1983-01-01

    The configurations and volumes of the cerebellar nuclei of left and right 10 sides of 5 cases of the pangolins (Manis pentadactyla) were examined with sagittal myelin sheath and toluidine blue stained serial sections and reconstruction models based upon these serial sections respectively. The cerebellar nuclei of the pangolins, same as in other mammals can be divided into four nuclei, nucleus medialis (M), nucleus interpositus posterior (P), nucleus interpositus anterior (A) and nucleus lateralis (L). In all cases from medially to laterally, M, P, A and L appear in order and disappear M, A, P and L in order respectively. The volume of each nucleus in the total volume of the cerebellar nuclei is: M; 5.3-7.9% P; 27.1-31.2% A; 17.6-22.9% L; 42.4-46.2% In right and left each cerebellar nuclei significant difference is not recognized as p is less than 0.05. The posterior protuberance of the nucleus medialis protrudes remarkably in 4 cases of No. 1, No. 2, No. 3 and No. 4 but in only 1 case of No. 5 it protrudes slightly. In nucleus interpositus posterior the ventrolateral protuberance protrudes slightly in 4 cases of No. 1, No. 3, No. 4 and No. 5 but in only 1 case of No. 2 it protrudes remarkably. The anterior protuberance protrudes remarkably in all cases and the superior protuberance protrudes remarkably in 3 cases of No. 2, No. 3 and No. 4 but in 2 cases of No. 1 and No. 5 it protrudes slightly. In sulci, sulcus b and sulcus a' are distinct in all cases and sulcus a, sulcus c, sulcus b' and sulcus c' are considerably remarkable. In the toluidine blue stained serial sections, the nucleus medialis is composed of close small nerve cells, nucleus interpositus posterior is composed of the diffuse medium-sized nerve cells, nucleus interpositus anterior is composed of the close medium-sized nerve cells and nucleus lateralis is composed of the diffuse large nerve cells. In projection pictures of each subnuclei to the cerebellar cortex in each directions in the dorsal view

  9. Short-lived Isotopes from a Close-by AGB Star Triggering the Protosolar Nebula

    NASA Astrophysics Data System (ADS)

    Gallino, R.; Busso, M.; Wasserburg, G. J.; Straniero, O.

    The presence of short-lived isotopes in the early solar system, in particular 26Al, 41Ca, 60Fe, and 107Pd, point to a close-by and fresh nucleosynthesis source, possibly triggering the collapse of the protosolar nebula. We present the results of nucleosynthesis calculations based on an AGB polluting hypothesis. A general concordance of the predicted yields of the above radioactivities relative to 26Al can be obtained in the case of an intermediate mass AGB star with hot bottom burning in the envelope (thus producing 26Al), and mixing through a series of third dredge-up episodes a fraction of the C-rich and s-processed material from the He intershell with the extended envelope. Polution of the protosolar nebula with freshly synthesized material may derive from the efficient winds of the AGB star. In AGB stars, the s-process nucleosynthesis occurs both during the maximum phase of every thermal runaway, driven by the partial activation of the 22Ne(alpha,n)25Mg reaction, and in the interpulse phase, where the 13C nuclei are fully consumed in radiative conditions by the activation of the 13C(alpha,n)16O reaction. We have used different prescriptions for the amount of the 13C nuclei present in the intershell. A minimum amount of 13C is naturally expected in the ashes of H-shell burning. Possible formation of an extra "13C-pocket" derives from the injection of a small amount of protons from the envelope into the 12C-rich intershell during any third dredge-up episode, when the H-shell is inactivated. Prediction for other short-lived, 36Cl, 135Cs, and 205Pb, are given. General consequences for the pollution of the protosolar nebula with newly synthesized stable isotopes from the AGB winds are outlined. The origin of other detected short-lived nuclei, in particular 53Mn, 129I, and 182Hf, which cannot come from an AGB source, is analysed. The alternative trigger hypothesis by a close-by Supernova is discussed.

  10. 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

  11. 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

  12. Synthesis of the lightest nuclei

    NASA Astrophysics Data System (ADS)

    Kneller, James Patrick

    The lightest nuclei are principally synthesized either during the first moments of the Universe or as fragments from the spallation of heavier nuclei when Cosmic Rays interact with the Interstellar Medium and this dissertation investigates each in turn. In the first half the predictions from Big Bang Nucleosynthesis are studied when the requirements of only three relativistic neutrino flavors and a small electron neutrino chemical potential are relaxed. The hope that a small, acceptable region for each can be identified is shown to be unfounded because of a degeneracy amongst the parameters. Additional information is required and this may be obtained from the anisotropies in the Cosmic Microwave Background. The estimates of the baryon to photon ratio are shown to be consistent and a relatively well identified value for the number of relativistic neutrino species can be found but with a variance that exhibits a dependency upon the prior assumptions. By imposing a constraint upon the age of the Universe the number of relativistic neutrino species is shown to be <=6 which then yields an limit to the electron neutrino chemical potential of <=0.3. The second is concerned with the kinetics and evolution of Galactic Cosmic Ray Nucleosynthesis. Two approximations are frequently employed in calculations of the production rates: the termination of the reaction expansion at the `One-Step' term and the Straight-Ahead Approximation for the fragment energies. Relaxing the Straight-Ahead Approximation produces minor differences of order 5% but changes of order 10-50% are found when the Two-Step terms in the reaction expansion are included. The two proposed solutions capable of reconciling the theoretical predictions of the evolution of the abundances of these elements with the observations: the possibility of an enriched cosmic ray composition and a modified Oxygen to Iron relation. From the analysis of a simple model it is found that an enriched component greater than >~ 70% is

  13. Star formation around active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Keel, William C.

    1987-01-01

    Active galactic nuclei (Seyfert nuclei and their relatives) and intense star formation can both deliver substantial amounts of energy to the vicinity of a galactic nucleus. Many luminous nuclei have energetics dominated by one of these mechanisms, but detailed observations show that some have a mixture. Seeing both phenomena at once raises several interesting questions: (1) Is this a general property of some kinds of nuclei? How many AGNs have surround starbursts, and vice versa? (2) As in 1, how many undiscovered AGNs or starbursts are hidden by a more luminous instance of the other? (3) Does one cause the other, and by what means, or do both reflect common influences such as potential well shape or level of gas flow? (4) Can surrounding star formation tell us anything about the central active nuclei, such as lifetimes, kinetic energy output, or mechanical disturbance of the ISM? These are important points in the understanding of activity and star formation in galactic nuclei. Unfortunately, the observational ways of addressing them are as yet not well formulated. Some preliminary studies are reported, aimed at clarifying the issues involved in study of the relationships between stellar and nonstellar excitement in galactic nuclei.

  14. Chemical complexity in galactic nuclei

    NASA Astrophysics Data System (ADS)

    Martin-Pintado, Jesus

    2007-12-01

    In recent years our knowledge of the chemical complexity in the nuclei of galaxies has dramatically changed. Recent observations of the nucleus of the Milky Way, of the starburst galaxy NGC253 and of the ultraluminous infrared galaxy (ULIRG) Arp220 have shown large abundance of complex organic molecules believed to be formed on grains. The Galactic center appears to be the largest repository of complex organic molecule like aldehydes and alcohols in the galaxy. We also measure large abundance of methanol in starburst galaxies and in ULIRGs suggesting that complex organic molecules are also efficiently produced in the central region of galaxies with strong star formation activity. From the systematic observational studies of molecular abundance in regions dominated by different heating processes like shocks, UV radiation, X-rays and cosmic rays in the center of the Milky Way, we are opening the possibility of using chemistry as a diagnostic tool to study the highly obscured regions of galactic centers. The templates found in the nucleus of the Milky Way will be used to establish the main mechanisms driving the heating and the chemistry of the molecular clouds in galaxies with different type of activity. The role of grain chemistry in the chemical complexity observed in the center of galaxies will be also briefly discussed.

  15. Neurotransmitters of the suprachiasmatic nuclei

    PubMed Central

    Reghunandanan, Vallath; Reghunandanan, Rajalaxmy

    2006-01-01

    There has been extensive research in the recent past looking into the molecular basis and mechanisms of the biological clock, situated in the suprachiasmatic nuclei (SCN) of the anterior hypothalamus. Neurotransmitters are a very important component of SCN function. Thorough knowledge of neurotransmitters is not only essential for the understanding of the clock but also for the successful manipulation of the clock with experimental chemicals and therapeutical drugs. This article reviews the current knowledge about neurotransmitters in the SCN, including neurotransmitters that have been identified only recently. An attempt was made to describe the neurotransmitters and hormonal/diffusible signals of the SCN efference, which are necessary for the master clock to exert its overt function. The expression of robust circadian rhythms depends on the integrity of the biological clock and on the integration of thousands of individual cellular clocks found in the clock. Neurotransmitters are required at all levels, at the input, in the clock itself, and in its efferent output for the normal function of the clock. The relationship between neurotransmitter function and gene expression is also discussed because clock gene transcription forms the molecular basis of the clock and its working. PMID:16480518

  16. Molecular outflows in starburst nuclei

    NASA Astrophysics Data System (ADS)

    Roy, Arpita; Nath, Biman B.; Sharma, Prateek; Shchekinov, Yuri

    2016-12-01

    Recent observations have detected molecular outflows in a few nearby starburst nuclei. We discuss the physical processes at work in such an environment in order to outline a scenario that can explain the observed parameters of the phenomenon, such as the molecular mass, speed and size of the outflows. We show that outflows triggered by OB associations, with NOB ≥ 105 (corresponding to a star formation rate (SFR)≥1 M⊙ yr-1 in the nuclear region), in a stratified disc with mid-plane density n0 ˜ 200-1000 cm-3 and scaleheight z0 ≥ 200(n0/102 cm-3)-3/5 pc, can form molecules in a cool dense and expanding shell. The associated molecular mass is ≥107 M⊙ at a distance of a few hundred pc, with a speed of several tens of km s-1. We show that an SFR surface density of 10 ≤ ΣSFR ≤ 50 M⊙ yr-1 kpc-2 favours the production of molecular outflows, consistent with observed values.

  17. Dipole Excitation of Soft and Giant Resonances in 132Sn and neighboring unstable nuclei

    NASA Astrophysics Data System (ADS)

    Boretzky, Konstanze

    2006-04-01

    The evolution of dipole-strength distributions above the one-neutron threshold was investigated for exotic neutron-rich nuclei in a series of experiments using the electromagnetic projectile excitation at beam energies around 500 MeV/u. For halo nuclei, the large observed dipole strength (shown here for 11Be) is explained within the direct-breakup model to be of non-collective character. For neutron-rich oxygen isotopes, the origin of the observed low-lying strength is concluded to be due to single-particle transitions on theoretical grounds. The dipole strength spectra for 130,132Sn exhibit resonance-like structures observed at energies around 10 MeV exhausting a few percent of the Thomas-Reiche-Kuhn (TRK) sum rule, separated clearly from the dominant Giant Dipole Resonance (GDR). The data agree with predictions for a new dipole mode related to the oscillation of excess neutrons versus the core nucleons ("pygmy resonance").

  18. Measuring the Fusion Cross-Section of Light Nuclei with Low-Intensity Beams

    NASA Astrophysics Data System (ADS)

    Steinbach, Tracy; Brown, Kyle; Hudan, Sylvie; Desouza, Romualdo

    2014-03-01

    Reactions between neutron-rich light nuclei have been proposed as a heat source in the crust of an accreting neutron star that triggers an X-ray superburst. To explore the probability of such fusion events as well as better understand the fusion dynamics between neutron-rich nuclei, an experimental program to measure the dependence of the fusion cross-section on neutron number has been initiated. Key to these measurements is developing an approach to measure the total fusion cross-section for beams of low-intensity light nuclei (<105 ions/s) on light targets. Fusion residues resulting from the fusion of oxygen nuclei with 12C at energies near and below the Coulomb barrier are directly measured and distinguished from unreacted beam particles on the basis of their energy and time-of-flight (TOF). The TOF is measured between a microchannel plate (MCP) detector and a segmented Si detector. Two initial problems were charge trapping in the Si detector and slit scattering in the MCP detector. These problems have both been minimized by implementing a gridless MCP detector and a new Si design making the measurement feasible. Supported by the US DOE under Grant No. DEFG02-88ER-40404

  19. Deep inelastic scattering on asymmetric nuclei

    NASA Astrophysics Data System (ADS)

    Saito, K.; Boros, C.; Tsushima, K.; Bissey, F.; Afnan, I. R.; Thomas, A. W.

    2000-11-01

    We study deep inelastic scattering on isospin asymmetric nuclei. In particular, the difference of the nuclear structure functions and the Gottfried sum rule for the lightest mirror nuclei, 3He and 3H, are investigated. It is found that such systems can provide significant information on charge symmetry breaking and flavor asymmetry in the nuclear medium. Furthermore, we propose a new method to extract the neutron structure function from radioactive isotopes far from the line of stability. We also discuss the flavor asymmetry in the Drell-Yan process with isospin asymmetric nuclei.

  20. Separating Cloud Forming Nuclei from Interstitial Aerosol

    SciTech Connect

    Kulkarni, Gourihar R.

    2012-09-12

    It has become important to characterize the physicochemical properties of aerosol that have initiated the warm and ice clouds. The data is urgently needed to better represent the aerosol-cloud interaction mechanisms in the climate models. The laboratory and in-situ techniques to separate precisely the aerosol particles that act as cloud condensation nuclei (CCN) and ice nuclei (IN), termed as cloud nuclei (CN) henceforth, have become imperative in studying aerosol effects on clouds and the environment. This review summarizes these techniques, design considerations, associated artifacts and challenges, and briefly discusses the need for improved designs to expand the CN measurement database.

  1. The human cuneate nucleus contains discrete subregions whose neurochemical features match those of the relay nuclei for nociceptive information.

    PubMed

    Del Fiacco, Marina; Quartu, Marina; Serra, Maria Pina; Boi, Marianna; Demontis, Roberto; Poddighe, Laura; Picci, Cristina; Melis, Tiziana

    2014-11-01

    The present paper is aimed at defining distinctive subdivisions of the human cuneate nucleus (Cu), evident from prenatal to old life, whose occurrence has never been clearly formalized in the human brain, or described in other species so far. It extends our early observations on the presence of gray matter areas that host strong substance P (SP) immunoreactivity in the territory of the human Cu and adjacent cuneate fascicle. Here we provide a three-dimensional reconstruction of the Cu fields rich in SP and further identify those areas by means of their immunoreactivity to the neuropeptides SP, calcitonin gene-related peptide, methionine- and leucine-enkephalin, peptide histidine-isoleucine, somatostatin and galanin, to the trophins glial cell line-derived neurotrophic factor and brain-derived neurotrophic factor, and to the neuroplasticity proteins polysialylated neural cell adhesion molecule and growth-associated protein-43. The presence, density and distribution of immunoreactivity for each of these molecules closely resemble those occurring in the superficial layers of the caudal spinal trigeminal nucleus (Sp5C). Myelin and Nissl stainings suggest that those Cu subregions and the Sp5C superficial layers share a similar histological aspect. This work establishes the existence of definite subregions, localized within the Cu territory, that bear the neurochemical and histological features of sensory nuclei committed to the neurotransmission of protopathic stimuli, including pain. These findings appear of particular interest when considering that functional, preclinical and clinical studies show that the dorsal column nuclei, classical relay station of fine somatic tactile and proprioceptive sensory stimuli, are also involved in pain neurotransmission.

  2. Bimodal Active Nuclei in Bimodal Galaxies

    NASA Astrophysics Data System (ADS)

    Cavaliere, A.; Menci, N.

    2007-07-01

    By their star content, the galaxies split out into a red and a blue population; their color index peaked around u-r~2.5 or u-r~1, respectively, quantifies the ratio of the blue stars newly formed from cold galactic gas, to the redder ones left over by past generations. On the other hand, on accreting substantial gas amounts the central massive black holes energize active galactic nuclei (AGNs); here we investigate whether these show a similar, and possibly related, bimodal partition as for current accretion activity relative to the past. To this aim we use an updated semianalytic model; based on Monte Carlo simulations, this follows with a large statistics the galaxy assemblage, the star generations, and the black hole accretions in the cosmological framework over the redshift span from z=10 to z=0. We test our simulations for yielding in close detail the observed split of galaxies into a red, early and a blue, late population. We find that the black hole accretion activities likewise give rise to two source populations: early, bright quasars and later, dimmer AGNs. We predict for their Eddington parameter λE-the ratio of the current to the past black hole accretions-a bimodal distribution; the two branches sit now under λE~0.01 (mainly contributed by low-luminosity AGNs) and around λE~0.3-1. These not only mark out the two populations of AGNs, but also will turn out to correlate strongly with the red or blue color of their host galaxies.

  3. 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.

  4. The Stellar Populations of Nuclei, Globular Clusters, and Stars in dE Galaxies in Virgo and Fornax

    NASA Astrophysics Data System (ADS)

    Whitfield Miller, Bryan; Hyazinth Puzia, Thomas; Hilker, Michael; Sanchez-Janssen, Ruben; Kissler-Patig, Markus

    2015-08-01

    We present ages and metallicities for globular clusters, nuclei, and underlying stars in nucleated dwarf elliptical galaxies (dE,N) in the Virgo and Fornax Cluster based on Lick/IDS index measurements and SSP models. Gemini/GMOS spectroscopy shows that the globular clusters are mostly old and metal-poor, very similar to the globular clusters in the Milky Way halo. The nuclei and underlying stars tend to be more metal-rich than the globular clusters and have a wide range of ages. The [α/Fe] ratios for both the globular clusters and nuclei range between 0.0 and 0.3. Formation scenarios for globular clusters and nuclei will be discussed.

  5. Extrasolar Comets in our Solar System Captured During Close Encounters with Nearby Stars?

    NASA Astrophysics Data System (ADS)

    Rocca, M. C. L.; Acevedo, R. D.

    2014-09-01

    It is a fact that many nearby Sun like stars have their own cometary clouds. Close encounters with passing nearby stars may induce to the capture and exchange of cometary nuclei between the Sun and the coming star.

  6. 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.

  7. Study of multi-nucleon transfer reactions with light nuclei

    SciTech Connect

    Benzoni, G.; Montanari, D.; Bracco, A.; Blasi, N.; Camera, F.; Crespi, F. C. L.; Corsi, A.; Leoni, S.; Million, B.; Nicolini, R.; Wieland, O.; Zalite, A.; Zocca, F.; Azaiez, F.; Franchoo, S.; Stefan, I.; Ibrahim, F.; Verney, D.; Battacharyya, S.; De France, G.

    2008-05-12

    Multi-nucleon transfer reactions are useful tools to populate exotic nuclei, particularly the neutron-rich ones. In this view, two different experiments have been performed employing a stable ({sup 22}Ne) and a radioactive ({sup 24}Ne) beam, both impinging on a {sup 208}Pb target. The first reaction has been studied using the CLARA-PRISMA-DANTE set-up at Laboratori Nazionali di Legnaro (Legnaro-Italy), while the second reaction was performed at Ganil (Caen-France) employing a SPIRAL radioactive beam of {sup 24}Ne. In this case recoils and coincident {gamma} rays were detected with the VAMOS-EXOGAM set-up.The data show that MNT reactions can selectively populate states of different nature and, therefore, are a good tool to study nuclear structure further away from stability.

  8. Cerenkov counters for high energy nuclei: Some new developments

    NASA Technical Reports Server (NTRS)

    Swordy, S. P.; Muller, D.

    1985-01-01

    A method to determine with gas Cerenkov counters the Lorentz factor, gamma = E/mc, of cosmic ray nuclei with high accuracy over the range gamma approx. 20 to 100 is discussed. The measurement of the Cerenkov emission angle theta, by use of a suitable imaging system is considered. Imaging counters, the ring imaging Cerenkov counters (RICH), were developed for use on accelerators. The image of off-axis particles to determine the amount of image distortion as a function of the direction of the incoming nucleus is examined and an acceptance solid angle, relative to the optical axis, within which the nucleus produces an image with an acceptable level of distortion is defined. The properties of the image, which becomes elliptical, for off-axis particles are analyzed.

  9. Applications of modern chiral interactions in nuclear matter and nuclei

    NASA Astrophysics Data System (ADS)

    Sammarruca, Francesca

    2016-09-01

    Experimental investigations are in progress, and more are planned for the near future, to set reliable constraints on the isospin asymmetric part of the nuclear equation of state. The latter plays a fundamental role in a broad spectrum of systems and phenomena, including the skins of neutron-rich nuclei and the location of the neutron drip lines. From the theoretical standpoint, microscopic calculations with statistically meaningful uncertainties are essential to guide experiments. We will discuss recent calculations of the nuclear and neutron matter equations of state at different orders of the chiral expansion. We will present applications and discuss the significance of those predictions as a foundation for future studies of convergence of the chiral perturbation series. Anticipating future experiments which may provide reliable information on the weak charge density in nuclei, we discuss the possibility of constraining the size of three-neutron forces in neutron matter. Supported by the U.S. Department of Energy under Grant No. DE-FG02-03ER41270.

  10. 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.

  11. Effective Interactions for Light Nuclei

    NASA Astrophysics Data System (ADS)

    Caldwell, Bryan R.

    The G-matrix technique in which one is able to easily calculate ground and excited states of many-body systems is used to calculate the ground state energies and some excited levels of ^3H and ^4He. Energy independent effective interactions are obtained for these nuclei using the technique of Suzuki and Lee which requires the G-matrix and its derivatives with respect to starting energy. It is found that accurate energy derivatives of the G-matrix are necessary to obtain energy independence and thus analytic expressions are presented for these derivatives in both center-of-mass/relative and shell model coordinate systems. Several rules of thumb are given pertaining to the convergence criteria in both coordinate systems. Further, since the G-matrix includes only intra -channel two-body correlations outside the active space, we explore the effect on the binding energies when the active space is enlarged to include several major shells. By enlarging the active space, we hope to include the most important many-body correlations explicitly. It is found that when the active space includes more than 2 major shells, the effective interaction is well approximated by the G-matrix. Our results essentially agree with exact Faddeev calculations for ^3 H but underbind by about.5 MeV in ^4 He as compared to exact Yabukovsky and Green function Monte Carlo calculations. A possible reason for this underbinding, the inclusion of unlinked diagrams in the energy expansion, is studied. The energy independent G-matrix technique is then applied to the p-shell (^5He, ^6Li and ^7Li) where the active space includes all excitations up to 2 hbaromega. Zero, one, two and three -body effective interactions are extracted and it is found that a schematic two-parameter three-body potential can be used to approximate the effective three-body potential that results from the truncation of the active space.

  12. Where Should the Nuclei Be Located?

    ERIC Educational Resources Information Center

    Ying Liu; Yue Liu; Drew, Michael G. B.

    2005-01-01

    The approach of determining the nature of the electron wave function via orbital representations qualitatively and via numerical calculations quantitatively is demonstrated. The angular part of the wave function provides suitable representation of the positions of the nuclei.

  13. Infrared Observations of Cometary Dust and Nuclei

    NASA Technical Reports Server (NTRS)

    Lisse, Carey

    2004-01-01

    This bibliography lists citations for publications published under the grant. Subjects of the publications include cometary dust, instellar and interplanetary dust, comet nuclei and comae, Comet Hale-Bopp, infrared observations of comets, mass loss, and comet break-up.

  14. 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.

  15. Clusterization and quadrupole deformation in nuclei

    SciTech Connect

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

    2006-04-26

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

  16. Infrared Observations of Cometary Dust and Nuclei

    NASA Technical Reports Server (NTRS)

    Lisse, Carey

    2004-01-01

    This bibliography lists citations for publications published under the grant. Subjects of the publications include cometary dust, instellar and interplanetary dust, comet nuclei and comae, Comet Hale-Bopp, infrared observations of comets, mass loss, and comet break-up.

  17. Perspectives of production of superheavy nuclei

    SciTech Connect

    Adamian, G. G.; Antonenko, N. V. Bezbakh, A. N.; Sargsyan, V. V.; Scheid, W.

    2016-07-07

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

  18. From nucleons to nuclei to fusion reactions

    NASA Astrophysics Data System (ADS)

    Quaglioni, S.; Navrátil, P.; Roth, R.; Horiuchi, W.

    2012-12-01

    Nuclei are prototypes of many-body open quantum systems. Complex aggregates of protons and neutrons that interact through forces arising from quantum chromo-dynamics, nuclei exhibit both bound and unbound states, which can be strongly coupled. In this respect, one of the major challenges for computational nuclear physics, is to provide a unified description of structural and reaction properties of nuclei that is based on the fundamental underlying physics: the constituent nucleons and the realistic interactions among them. This requires a combination of innovative theoretical approaches and high-performance computing. In this contribution, we present one of such promising techniques, the ab initio no-core shell model/resonating-group method, and discuss applications to light nuclei scattering and fusion reactions that power stars and Earth-base fusion facilities.

  19. A focus on shape coexistence in nuclei

    NASA Astrophysics Data System (ADS)

    Wood, J. L.; Heyde, K.

    2016-02-01

    The present collection of articles focuses on new directions and developments under the title of shape coexistence in nuclei, following our 2011 Reviews of Modern Physics article (K Heyde and J L Wood).

  20. From Nucleons To Nuclei To Fusion Reactions

    SciTech Connect

    Quaglioni, S; Navratil, P; Roth, R; Horiuchi, W

    2012-02-15

    Nuclei are prototypes of many-body open quantum systems. Complex aggregates of protons and neutrons that interact through forces arising from quantum chromo-dynamics, nuclei exhibit both bound and unbound states, which can be strongly coupled. In this respect, one of the major challenges for computational nuclear physics, is to provide a unified description of structural and reaction properties of nuclei that is based on the fundamental underlying physics: the constituent nucleons and the realistic interactions among them. This requires a combination of innovative theoretical approaches and high-performance computing. In this contribution, we present one of such promising techniques, the ab initio no-core shell model/resonating-group method, and discuss applications to light nuclei scattering and fusion reactions that power stars and Earth-base fusion facilities.

  1. ULTRA-RELATIVISTIC NUCLEI: A NEW FRONTIER

    SciTech Connect

    MCLERRAN,L.

    1999-10-29

    The collisions of ultra-relativistic nuclei provide a window on the behavior of strong interactions at asymptotically high energies. They also will allow the authors to study the bulk properties of hadronic matter at very high densities.

  2. 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

  3. Quenching of spin matrix elements in nuclei

    NASA Astrophysics Data System (ADS)

    Towner, I. S.

    1987-11-01

    Matrix elements of spin operators evaluated in a nuclear medium are systematically quenched compared to their values in free space. There are a number of contributing reasons for this. Foremost is the traditional nuclear structure difficulty of the inadequacy of the lowest-order shell-model wavefunctions. We use the Rayleigh-Schrödinger perturbation theory to correct for this, arguing that calculations must be carried through at least t o second order. This is a question of the appropriate effective interaction. We review the Landau-Migdal approach in which only RPA graphs are retained and discuss the strength of this interaction in the spin-isospin channel expressed in terms of the parameter g'. We also consider one-boson-exchange models and compare the two. The advantage of the OBEP models is that the two-nucleon meson-exchange current operators can be constructed to be consistent with the potential as required by the continuity equation for vector currents and the partial conservation (PCAC) equation for axial currents. We give a complete derivation of the MEC operators of heavy-meson range starting with the chiral Lagrangians used by Ivanov and Truhlik. Nonlocal terms are retained in the computations. We single out one class of MEC processes involving isobar excitation and demonstrate that in lowest order there is an equivalence between treating the isobar as an MEC correction and treating it as a nuclear constituent through the transition spin formalism. Differences occur in higher orders. There are a number of uncertainties in the isobar calculation involving the neglect of the isobar's natural width, the relativistic propagator being off the mass shell and the coupling constants not being known with any precision. We present a comprehensive calculation of core-polarisation, meson-exchange current and isobar-current corrections to low-energy M1 and Gamow-Teller transitions in closed-shell-plus-one nuclei (at LS and jj closed shells) expressing the results in

  4. Reaction cross sections of unstable nuclei

    SciTech Connect

    Ozawa, Akira

    2006-11-02

    Experimental studies on reaction cross sections are reviewed. The recent developments of radioactive nuclear beams have enabled us to measure reaction cross-sections for unstable nuclei. Using Glauber-model analysis, effective nuclear matter density distributions of unstable nuclei can be studied. Recent measurements in RIBLL at IMP and RIPS at RIKEN are introduced. The effective matter density distributions for 14-18C are also mentioned.

  5. Organization of projections from the raphe nuclei to the vestibular nuclei in rats

    NASA Technical Reports Server (NTRS)

    Halberstadt, A. L.; Balaban, C. D.

    2003-01-01

    Previous anatomic and electrophysiological evidence suggests that serotonin modulates processing in the vestibular nuclei. This study examined the organization of projections from serotonergic raphe nuclei to the vestibular nuclei in rats. The distribution of serotonergic axons in the vestibular nuclei was visualized immunohistochemically in rat brain slices using antisera directed against the serotonin transporter. The density of serotonin transporter-immunopositive fibers is greatest in the superior vestibular nucleus and the medial vestibular nucleus, especially along the border of the fourth ventricle; it declines in more lateral and caudal regions of the vestibular nuclear complex. After unilateral iontophoretic injections of Fluoro-Gold into the vestibular nuclei, retrogradely labeled neurons were found in the dorsal raphe nucleus (including the dorsomedial, ventromedial and lateral subdivisions) and nucleus raphe obscurus, and to a minor extent in nucleus raphe pallidus and nucleus raphe magnus. The combination of retrograde tracing with serotonin immunohistofluorescence in additional experiments revealed that the vestibular nuclei receive both serotonergic and non-serotonergic projections from raphe nuclei. Tracer injections in densely innervated regions (especially the medial and superior vestibular nuclei) were associated with the largest numbers of Fluoro-Gold-labeled cells. Differences were observed in the termination patterns of projections from the individual raphe nuclei. Thus, the dorsal raphe nucleus sends projections that terminate predominantly in the rostral and medial aspects of the vestibular nuclear complex, while nucleus raphe obscurus projects relatively uniformly throughout the vestibular nuclei. Based on the topographical organization of raphe input to the vestibular nuclei, it appears that dense projections from raphe nuclei are colocalized with terminal fields of flocculo-nodular lobe and uvula Purkinje cells. It is hypothesized that

  6. Organization of projections from the raphe nuclei to the vestibular nuclei in rats

    NASA Technical Reports Server (NTRS)

    Halberstadt, A. L.; Balaban, C. D.

    2003-01-01

    Previous anatomic and electrophysiological evidence suggests that serotonin modulates processing in the vestibular nuclei. This study examined the organization of projections from serotonergic raphe nuclei to the vestibular nuclei in rats. The distribution of serotonergic axons in the vestibular nuclei was visualized immunohistochemically in rat brain slices using antisera directed against the serotonin transporter. The density of serotonin transporter-immunopositive fibers is greatest in the superior vestibular nucleus and the medial vestibular nucleus, especially along the border of the fourth ventricle; it declines in more lateral and caudal regions of the vestibular nuclear complex. After unilateral iontophoretic injections of Fluoro-Gold into the vestibular nuclei, retrogradely labeled neurons were found in the dorsal raphe nucleus (including the dorsomedial, ventromedial and lateral subdivisions) and nucleus raphe obscurus, and to a minor extent in nucleus raphe pallidus and nucleus raphe magnus. The combination of retrograde tracing with serotonin immunohistofluorescence in additional experiments revealed that the vestibular nuclei receive both serotonergic and non-serotonergic projections from raphe nuclei. Tracer injections in densely innervated regions (especially the medial and superior vestibular nuclei) were associated with the largest numbers of Fluoro-Gold-labeled cells. Differences were observed in the termination patterns of projections from the individual raphe nuclei. Thus, the dorsal raphe nucleus sends projections that terminate predominantly in the rostral and medial aspects of the vestibular nuclear complex, while nucleus raphe obscurus projects relatively uniformly throughout the vestibular nuclei. Based on the topographical organization of raphe input to the vestibular nuclei, it appears that dense projections from raphe nuclei are colocalized with terminal fields of flocculo-nodular lobe and uvula Purkinje cells. It is hypothesized that

  7. Measurement of picosecond lifetimes in neutron-rich Xe isotopes

    NASA Astrophysics Data System (ADS)

    Ilieva, S.; Kröll, Th.; Régis, J.-M.; Saed-Samii, N.; Blanc, A.; Bruce, A. M.; Fraile, L. M.; de France, G.; Hartig, A.-L.; Henrich, C.; Ignatov, A.; Jentschel, M.; Jolie, J.; Korten, W.; Köster, U.; Lalkovski, S.; Lozeva, R.; Mach, H.; Mǎrginean, N.; Mutti, P.; Paziy, V.; Regan, P. H.; Simpson, G. S.; Soldner, T.; Thürauf, M.; Ur, C. A.; Urban, W.; Warr, N.

    2016-09-01

    Background: Lifetimes of nuclear excited states in fission fragments have been studied in the past following isotope separation, thus giving access mainly to the fragments' daughters and only to long-lived isomeric states in the primary fragments. For the first time now, short-lived excited states in the primary fragments, produced in neutron-induced prompt fission of 235U and 241Pu, were studied within the EXILL&FATIMA campaign at the intense neutron-beam facility of the Institute Laue-Langevin in Grenoble. Purpose: We aim to investigate the quadrupole collective properties of neutron-rich even-even 138,140,142Xe isotopes lying between the double shell closure N =82 and Z =50 and a deformed region with octupole collectivity. Method: The γ rays emitted from the excited fragments were detected with a mixed array consisting of 8 HPGe EXOGAM Clover detectors (EXILL) and 16 LaBr3(Ce) fast scintillators (FATIMA). The detector system has the unique ability to select the interesting fragment making use of the high resolution of the HPGe detectors and determine subnanosecond lifetimes using the fast scintillators. For the analysis the generalized centroid difference method was used. Results: We show that quadrupole collectivity increases smoothly with increasing neutron number above the closed N =82 neutron shell. Our measurements are complemented by state-of-the-art theory calculations based on shell-model descriptions. Conclusions: The observed smooth increase in quadrupole collectivity is similar to the evolution seen in the measured masses of the xenon isotopic chain and is well reproduced by theory. This behavior is in contrast to higher Z even-even nuclei where abrupt change in deformation occurs around N =90 .

  8. The anatomy of the vestibular nuclei.

    PubMed

    Highstein, Stephen M; Holstein, Gay R

    2006-01-01

    The vestibular portion of the eighth cranial nerve informs the brain about the linear and angular movements of the head in space and the position of the head with respect to gravity. The termination sites of these eighth nerve afferents define the territory of the vestibular nuclei in the brainstem. (There is also a subset of afferents that project directly to the cerebellum.) This chapter reviews the anatomical organization of the vestibular nuclei, and the anatomy of the pathways from the nuclei to various target areas in the brain. The cytoarchitectonics of the vestibular brainstem are discussed, since these features have been used to distinguish the individual nuclei. The neurochemical phenotype of vestibular neurons and pathways are also summarized because the chemical anatomy of the system contributes to its signal-processing capabilities. Similarly, the morphologic features of short-axon local circuit neurons and long-axon cells with extrinsic projections are described in detail, since these structural attributes of the neurons are critical to their functional potential. Finally, the composition and hodology of the afferent and efferent pathways of the vestibular nuclei are discussed. In sum, this chapter reviews the morphology, chemoanatomy, connectivity, and synaptology of the vestibular nuclei.

  9. Time-dependent Hartree-Fock Study of Octupole Vibrations in doubly magic nuclei

    NASA Astrophysics Data System (ADS)

    Simenel, C.; Buete, J.; Vo-Phuoc, K.

    2016-09-01

    Octupole vibrations are studied in some doubly magic nuclei using the time-dependent Hartree-Fock (TDHF) theory with a Skyrme energy density functional. Through the use of the linear response theory, the energies and transition amplitudes of the low-lying vibrational modes for each of the nuclei were determined. Energies were found to be close to experimental results. However, transition amplitudes, quantified by the deformation parameter β3, are underestimated by TDHF. A comparison with single-particle excitations on the Hartree-Fock ground-state shows that the collective octupole vibrations have their energy lowered due to attractive RPA residual interaction.

  10. Recent results at ultrahigh spin: Terminating states and beyond in mass 160 rare-earth nuclei

    DOE PAGES

    Paul, E. S.; Rees, J. M.; Hampson, P.; ...

    2015-01-01

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

  11. Recent results at ultrahigh spin: Terminating states and beyond in mass 160 rare-earth nuclei

    SciTech Connect

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

    2015-01-01

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

  12. STORMVEX. Ice Nuclei and Cloud Condensation Nuclei Characterization Field Campaign Report

    SciTech Connect

    Cziczo, D.

    2016-03-01

    The relationship between aerosol particles and the formation of clouds is among the most uncertain aspects in our current understanding of climate change. Warm clouds have been the most extensively studied, in large part because they are normally close to the Earth’s surface and only contain large concentrations of liquid droplets. Ice and mixed-phase clouds have been less studied even though they have extensive global coverage and dominate precipitation formation. Because they require low temperatures to form, both cloud types are infrequently found at ground level, resulting in more difficult field studies. Complex mixtures of liquid and ice elements, normally at much lower concentrations than found in warm clouds, require precise separation techniques and accurate identification of phase. Because they have proved so difficult to study, the climatic impact of ice-containing clouds remains unresolved. In this study, cloud condensation nuclei (CCN) concentrations and associated single particles’ composition and size were measured at a high-elevation research site—Storm Peak Lab, east of Steamboat Springs, Colorado, operated by the Desert Research Institute. Detailed composition analyses were presented to compare CCN activation with single-particle composition. In collaboration with the scientists of the Storm Peak Lab Cloud Property Validation Experiment (STORMVEX), our goal was to relate these findings to the cloud characteristics and the effect of anthropogenic activities.

  13. Adipocyte nuclei captured from VAT and SAT.

    PubMed

    Ambati, Suresh; Yu, Ping; McKinney, Elizabeth C; Kandasamy, Muthugapatti K; Hartzell, Diane; Baile, Clifton A; Meagher, Richard B

    2016-01-01

    Obesity-related comorbidities are thought to result from the reprogramming of the epigenome in numerous tissues and cell types, and in particular, mature adipocytes within visceral and subcutaneous adipose tissue, VAT and SAT. The cell-type specific chromatin remodeling of mature adipocytes within VAT and SAT is poorly understood, in part, because of the difficulties of isolating and manipulating large fragile mature adipocyte cells from adipose tissues. We constructed MA-INTACT (Mature Adipocyte-Isolation of Nuclei TAgged in specific Cell Types) mice using the adiponectin (ADIPOQ) promoter (ADNp) to tag the surface of mature adipocyte nuclei with a reporter protein. The SUN1mRFP1Flag reporter is comprised of a fragment of the nuclear transmembrane protein SUN1, the fluorescent protein mRFP1, and three copies of the Flag epitope tag. Mature adipocyte nuclei were rapidly and efficiently immuno-captured from VAT and SAT (MVA and MSA nuclei, respectively), of MA-INTACT mice. MVA and MSA nuclei contained 1,000 to 10,000-fold higher levels of adipocyte-specific transcripts, ADIPOQ, PPARg2, EDNRB, and LEP, relative to uncaptured nuclei, while the latter expressed higher levels of leukocyte and endothelial cell markers IKZF1, RETN, SERPINF1, SERPINE1, ILF3, and TNFA. MVA and MSA nuclei differentially expressed several factors linked to adipogenesis or obesity-related health risks including CEBPA, KLF2, RETN, SERPINE1, and TNFA. The various nuclear populations dramatically differentially expressed transcripts encoding chromatin remodeler proteins regulating DNA cytosine methylation and hydroxymethylation (TETs, DNMTs, TDG, GADD45s) and nucleosomal histone modification (ARID1A, KAT2B, KDM4A, PRMT1, PRMT5, PAXIP1). Remarkably, MSA and MVA nuclei expressed 200 to 1000-fold higher levels of thermogenic marker transcripts PRDM16 and UCP1. The MA-INTACT mouse enables a simple way to perform cell-type specific analysis of highly purified mature adipocyte nuclei from VAT and SAT

  14. Characterization of biological ice nuclei from a lichen.

    PubMed Central

    Kieft, T L; Ruscetti, T

    1990-01-01

    Biological ice nuclei (active at approximately -4 degrees C) were extracted from cells of the lichen Rhizoplaca chrysoleuca by sonication. Sensitivity to proteases, guanidine hydrochloride, and urea showed these nuclei to be proteinaceous. The nuclei were relatively heat stable, active from pH 1.5 to 12, and active without lipids, thereby demonstrating significant differences from bacterial ice nuclei. PMID:2188965

  15. The effects of the local environment on active galactic nuclei

    SciTech Connect

    Manzer, L. H.; De Robertis, M. M. E-mail: mmdr@yorku.ca

    2014-06-20

    There continues to be significant controversy regarding the mechanism(s) responsible for the initiation and maintenance of activity in galactic nuclei. In this paper we will investigate possible environmental triggers of nuclear activity through a statistical analysis of a large sample of galaxy groups. The focus of this paper is to identify active galactic nuclei (AGNs) and other emission-line galaxies in these groups and to compare their frequency with a sample of over 260,000 isolated galaxies from the same catalog. The galaxy groups are taken from the catalog of Yang et al., in which over 20,000 virialized groups of galaxies (2 ≤ N ≤ 20) with redshifts between 0.01 and 0.20 are from the Sloan Digital Sky Survey. We first investigate the completeness of our data set and find, though biases are a concern particularly at higher redshift, that our data provide a fair representation of the local universe. After correcting emission-line equivalent widths for extinction and underlying Balmer stellar absorption, we classify galaxies in the sample using traditional emission-line ratios, while incorporating measurement uncertainties. We find a significantly higher fraction of AGNs in groups compared with the isolated sample. Likewise, a significantly higher fraction of absorption-line galaxies are found in groups, while a higher fraction of star-forming galaxies prefer isolated environments. Within grouped environments, AGNs and star-forming galaxies are found more frequently in small- to medium-richness groups, while absorption-line galaxies prefer groups with larger richnesses. Groups containing only emission-line galaxies have smaller virial radii, velocity dispersions, and masses compared with those containing only absorption-line galaxies. Furthermore, the AGN fraction increases with decreasing distance to the group centroid, independent of galaxy morphology. Using properties obtained from Galaxy Zoo, there is an increased fraction of AGNs within merging systems

  16. The CBM RICH detector

    NASA Astrophysics Data System (ADS)

    Adamczewski-Musch, J.; Akishin, P.; Becker, K.-H.; Belogurov, S.; Bendarouach, J.; Boldyreva, N.; Chernogorov, A.; Deveaux, C.; Dobyrn, V.; Dürr, M.; Eschke, J.; Förtsch, J.; Heep, J.; Höohne, C.; Kampert, K.-H.; Kochenda, L.; Kopfer, J.; Kravtsov, P.; Kres, I.; Lebedev, S.; Lebedeva, E.; Leonova, E.; Linev, S.; Mahmoud, T.; Michel, J.; Miftakhov, N.; Niebur, W.; Ovcharenko, E.; Pauly, C.; Pfeifer, D.; Querchfeld, S.; Rautenberg, J.; Reinecke, S.; Riabov, Y.; Roshchin, E.; Samsonov, V.; Tarasenkova, O.; Traxler, M.; Ugur, C.; Vznuzdaev, E.; Vznuzdaev, M.

    2016-05-01

    The CBM RICH detector will use CO2 as radiator gas, focussing glass mirrors with Al+MgF2 reflective and protective coating and Hamamatsu H12700 MAPMTs as photon detectors. The detector will serve for electron to pion separation up to momenta of 8 GeV/c and thus enable in CBM the measurement of electromagnetic radiation from the early and dense fireball in A+A collisions at SIS 100. In this article, the current status of the CBM RICH development will be presented including new measurements of the radiation hardness of the H12700 MAPMT and WLS coatings with p-terphenyl, the new concept for the readout electronics, and optimizations ongoing with respect to the mirror mount structure and overall geometry. Prior to the usage in CBM, part of the already ordered MAPMTs will be used to upgrade the HADES RICH detector for a new measurement campaign at SIS 18 from 2018-2020.

  17. Hydrogen rich gas generator

    NASA Technical Reports Server (NTRS)

    Houseman, J.; Rupe, J. H.; Kushida, R. O. (Inventor)

    1976-01-01

    A process and apparatus is described for producing a hydrogen rich gas by injecting air and hydrocarbon fuel at one end of a cylindrically shaped chamber to form a mixture and igniting the mixture to provide hot combustion gases by partial oxidation of the hydrocarbon fuel. The combustion gases move away from the ignition region to another region where water is injected to be turned into steam by the hot combustion gases. The steam which is formed mixes with the hot gases to yield a uniform hot gas whereby a steam reforming reaction with the hydrocarbon fuel takes place to produce a hydrogen rich gas.

  18. 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.

  19. 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.

  20. 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.}

  1. Flavanol binding of nuclei from tree species.

    PubMed

    Feucht, W; Treutter, D; Polster, J

    2004-01-01

    Light microscopy was used to examine the nuclei of five tree species with respect to the presence of flavanols. Flavanols develop a blue colouration in the presence of a special p-dimethylaminocinnamaldehyde (DMACA) reagent that enables those nuclei loaded with flavanols to be recognized. Staining of the nuclei was most pronounced in both Tsuga canadensis and Taxus baccata, variable in Metasequoia glyptostroboides, faint in Coffea arabica and minimal in Prunus avium. HPLC analysis showed that the five species contained substantial amounts of different flavanols such as catechin, epicatechin and proanthocyanidins. Quantitatively, total flavanols were quite different among the species. The nuclei themselves, as studied in Tsuga seed wings, were found to contain mainly catechin, much lower amounts of epicatechin and traces of proanthocyanidins. Blue-coloured nuclei located centrally in small cells were often found to maximally occupy up to 90% of a cell's radius, and the surrounding small rim of cytoplasm was visibly free of flavanols. A survey of 34 gymnosperm and angiosperm species indicated that the first group has much higher nuclear binding capacities for flavanols than the second group.

  2. Training Nuclei Detection Algorithms with Simple Annotations.

    PubMed

    Kost, Henning; Homeyer, André; Molin, Jesper; Lundström, Claes; Hahn, Horst Karl

    2017-01-01

    Generating good training datasets is essential for machine learning-based nuclei detection methods. However, creating exhaustive nuclei contour annotations, to derive optimal training data from, is often infeasible. We compared different approaches for training nuclei detection methods solely based on nucleus center markers. Such markers contain less accurate information, especially with regard to nuclear boundaries, but can be produced much easier and in greater quantities. The approaches use different automated sample extraction methods to derive image positions and class labels from nucleus center markers. In addition, the approaches use different automated sample selection methods to improve the detection quality of the classification algorithm and reduce the run time of the training process. We evaluated the approaches based on a previously published generic nuclei detection algorithm and a set of Ki-67-stained breast cancer images. A Voronoi tessellation-based sample extraction method produced the best performing training sets. However, subsampling of the extracted training samples was crucial. Even simple class balancing improved the detection quality considerably. The incorporation of active learning led to a further increase in detection quality. With appropriate sample extraction and selection methods, nuclei detection algorithms trained on the basis of simple center marker annotations can produce comparable quality to algorithms trained on conventionally created training sets.

  3. Shape Coexistence in Pb-Rn Nuclei Studied by Particle Decay Spectroscopy

    SciTech Connect

    Andreyev, A. N.

    2006-08-14

    This contribution reviews the results of recent experiments at the velocity filter SHIP (GSI, Darmstadt) in which a number of very neutron-deficient nuclei with Z=83-88 and N< 126 were studied in detail and new nuclides 186,187Po, 192At and 193,194Rn were identified. Complete fusion reactions at beam energies close to the Coulomb barrier were used, followed by particle detection with various detection systems. Peculiarities in {alpha}-decay characteristics of the 186-191Po isotopes are discussed in detail. Very recent results for the neutron-deficient At-Ra nuclei from the gas-filled separator RITU (JYFL, Jyvaeskylae) are also highlighted.The application of a new method to reach nuclei in this region - spallation-evaporation reactions of 238U ions at 1 AGeV on a Be target, followed by the separation with the FRS at GSI is discussed as well.

  4. The composition of cometary nuclei

    NASA Astrophysics Data System (ADS)

    Brownlee, D. E.

    1989-12-01

    The most detailed information on the elemental and molecular composition of comets was obtained during the 1986 apparition of comet Halley. Although there are uncertainties in the dust/gas ratio and the abundances of several gaseous species, there is a reasonably good understanding of the major composition of the comet. The ice component is dominated by water, and the abundances of CO, H2CO, NH3 and other carbon and nitrogen bearing species are sufficiently low that the carbon and nitrogen are underabundant in the ice relative to solar proportions. These elements are abundant in the dust and it is likely that the cumulative composition of dust plus ice is a reasonably close match to solar abundances for those elements that are carried in compounds that condense at temperatures above 30K.

  5. From Rags to Riches

    ERIC Educational Resources Information Center

    Sweet, Colleen

    2008-01-01

    In this article, the author presents the "Rags to Riches" design project she introduced to her students. She assigned each of her students one item from an array to thrift store goods which included old scarves, sweaters, jackets, and even evening gowns. The design problem was to imagine what a clothing tag might look like if the assigned item…

  6. From Rags to Riches

    ERIC Educational Resources Information Center

    Sweet, Colleen

    2008-01-01

    In this article, the author presents the "Rags to Riches" design project she introduced to her students. She assigned each of her students one item from an array to thrift store goods which included old scarves, sweaters, jackets, and even evening gowns. The design problem was to imagine what a clothing tag might look like if the assigned item…

  7. Mangrove bacterial richness

    PubMed Central

    Cleary, Daniel FR; Calado, Ricardo; Costa, Rodrigo

    2011-01-01

    Mangroves are complex and dynamic ecosystems varying in salinity, water level and nutrient availability; they also contain diverse and distinct microbial communities. Studies of microbes and their interactions with other ecosystem components (e.g., tree roots) are critical for our understanding of mangrove ecosystem functioning and remediation. Using a barcoding pyrosequencing approach, we previously noted the persistence of terrestrial bacterial populations on mangrove roots when nursery raised saplings were transplanted back to their natural environment. Here we go into further detail about the potential functional associations of bacterial guilds with distinct mangrove microhabitats including the rhizosphere. We also use a nonparametric richness estimator to show that estimated operational taxonomic unit (OTU) richness is more than twice that observed. In the transplant microhabitat, our estimate suggests that there are almost 7,000 OTU's for a sample size of 10,400 individual sequences with no sign of an asymptote, indicating that “true” richness for this microhabitat is substantially larger. Results on the number of bacterial OTU's should, however, be viewed with caution given that the barcoding pyrosequencing technique used can yield sequencing artifacts that may inflate richness estimates if not properly removed. PMID:21966560

  8. Thinking about "Rich" Tasks

    ERIC Educational Resources Information Center

    Box, Lorna; Watson, Anne

    2010-01-01

    This article presents an e-mail conversation between two teachers discussing how to have a "rich task" lesson in which they get to the heart of mathematical modeling and in which students are motivated into working on mathematics. One teacher emphasizes that the power of maths is in developing mathematical descriptions of situations by…

  9. Thinking about "Rich" Tasks

    ERIC Educational Resources Information Center

    Box, Lorna; Watson, Anne

    2010-01-01

    This article presents an e-mail conversation between two teachers discussing how to have a "rich task" lesson in which they get to the heart of mathematical modeling and in which students are motivated into working on mathematics. One teacher emphasizes that the power of maths is in developing mathematical descriptions of situations by…

  10. Comparative study of water ice exposures on cometary nuclei using multispectral imaging data

    NASA Astrophysics Data System (ADS)

    Oklay, N.; Sunshine, J. M.; Pajola, M.; Pommerol, A.; Vincent, J.-B.; Mottola, S.; Sierks, H.; Fornasier, S.; Barucci, M. A.; Preusker, F.; Scholten, F.; Lara, L. M.; Barbieri, C.; Lamy, P. L.; Rodrigo, R.; Koschny, D.; Rickman, H.; A'Hearn, M. F.; Bertaux, J.-L.; Bertini, I.; Bodewits, D.; Cremonese, G.; Da Deppo, V.; Davidsson, B. J. R.; Debei, S.; De Cecco, M.; Deller, J.; Fulle, M.; Gicquel, A.; Groussin, O.; Gutiérrez, P. J.; Güttler, C.; Hall, I.; Hofmann, M.; Hviid, S. F.; Ip, W.-H.; Jorda, L.; Keller, H. U.; Knollenberg, J.; Kovacs, G.; Kramm, J.-R.; Kührt, E.; Küppers, M.; Lazzarin, M.; Lin, Z.-Y.; Lopez Moreno, J. J.; Marzari, F.; Naletto, G.; Shi, X.; Thomas, N.; Tubiana, C.

    2016-11-01

    Deep Impact, EPOXI and Rosetta missions visited comets 9P/Tempel 1, 103P/Hartley 2 and 67P/Churyumov-Gerasimenko, respectively. Each of these three missions was equipped with both multispectral imagers and infrared spectrometers. Bright blue features containing water ice were detected in each of these comet nuclei. We analysed multispectral properties of enriched water ice features observed via Optical, Spectroscopic, and Infrared Remote Imaging System narrow angle camera on comet 67P in the wavelength range of 260-1000 nm and then compared with multispectral data of water ice deposits observed on comets 9P and 103P. We characterize the UV/VIS properties of water-ice-rich features observed on the nuclei of these three comets. When compared to the average surface of each comet, our analysis shows that the water ice deposits seen on comet 9P are similar to the clustered water-ice-rich features seen on comet 67P, while the water ice deposit seen on comet 103P is more akin to two large isolated water-ice-rich features seen on comet 67P. Our results indicate that the water ice deposit observed on comet 103P contains more water ice than the water-ice-rich features observed on comets 9P and 67P, proportionally to the average surface of each nucleus.

  11. The Size Distribution of Cometary Nuclei

    NASA Astrophysics Data System (ADS)

    Weissman, P. R.; Lowry, S. C.

    2001-11-01

    We are conducting a program of ground-based CCD photometry of distant cometary nuclei, in order to estimate their sizes, shapes, rotation periods and axial ratios. We have combined our data with that reported in the literature by other observers to obtain an estimate of the size distribution of observed Jupiter-family and Halley-type comets. The catalog consists of 79 measurements of 52 JF and HT comets using a variety of techniques, including CCD photometry, IR photometry, and HST imaging. The data has been normalized to an assumed albedo of 0.04 except in cases where the albedo was directly measured. We find that the cumulative number of comets at or larger than a given radius can be described by a power law function with a slope of --1.40 +/- 0.03. This corresponds to a slope of --0.28 +/- 0.01 for the cumulative luminosity function, close to the slope of --0.32 +/- 0.02 found by Lowry (2001), derived from a homogeneously reduced CCD survey of distant JF comets. Both values are considerably less than the slope of --0.53 +/- 0.05 found by Fernández et al. (1999). This inconsistency is most likely attributed to the inhomogeneous nature of the Fernández et al. dataset, and the inclusion of active comets within their sample. Typical values of the CLF slope for Kuiper belt objects are --0.64 to --0.69 (Gladman et al. 2001; Trujillo et al. 2001). The shallower slope of the JF and HT comets, which are considerably smaller than the measured Kuiper belt objects, may be due to intrinsic differences in the KBO size distribution at the different size ranges (Weissman & Levison 1998) or to the physical evolution of JF and HT comets as they lose mass through sublimation and fragmentation (Lowry 2001). This work was supported by the NASA Planetary Astronomy and Planetary Geology & Geophysics Programs. Support from the National Research Council is also gratefully acknowledged.

  12. Downscaling the environmental associations and spatial patterns of species richness.

    PubMed

    Keil, Petr; Jetz, Walter

    2014-06-01

    We introduce a method that enables the estimation of species richness environment association and prediction of geographic patterns of species richness at grains finer than the original grain of observation. The method is based on a hierarchical model that uses coarse-grain values of species richness and fine-grain environmental data as input. In the model, the (unobserved) fine-grain species richness is linked to the observed fine-grain environment and upscaled using a simple species-area relationship (SAR). The upscaled values are then stochastically linked to the observed coarse-grain species richness. We tested the method on Southern African Bird Atlas data by downscaling richness from 2 degrees to 0.25 degrees (-250 km to -30 km) resolution. When prior knowledge of the SAR slope (average species turnover within coarse-grain cells) was available, the method predicted the fine-grain relationship between richness and environment and provided fine-grain predictions of richness that closely resembled results from native fine-grain models. Without the SAR knowledge the method still accurately quantified the richness-environment relationship, but accurately predicted only relative (rank) values of richness. The approach can be easily extended and it is a powerful path for cross-scale statistical modeling of richness-environment relationships, and for the provision of high-resolution maps for basic science and conservation.

  13. Fusion of neutron-rich oxygen isotopes in the crust of accreting neutron stars

    SciTech Connect

    Horowitz, C. J.; Dussan, H.; Berry, D. K.

    2008-04-15

    Fusion reactions in the crust of an accreting neutron star are an important source of heat, and the depth at which these reactions occur is important for determining the temperature profile of the star. Fusion reactions depend strongly on the nuclear charge Z. Nuclei with Z{<=}6 can fuse at low densities in a liquid ocean. However, nuclei with Z=8 or 10 may not burn until higher densities where the crust is solid and electron capture has made the nuclei neutron rich. We calculate the S factor for fusion reactions of neutron rich nuclei including {sup 24}O+{sup 24}O and {sup 28}Ne+{sup 28}Ne. We use a simple barrier penetration model. The S factor could be further enhanced by dynamical effects involving the neutron rich skin. This possible enhancement in S should be studied in the laboratory with neutron rich radioactive beams. We model the structure of the crust with molecular dynamics simulations. We find that the crust of accreting neutron stars may contain micro-crystals or regions of phase separation. Nevertheless, the screening factors that we determine for the enhancement of the rate of thermonuclear reactions are insensitive to these features. Finally, we calculate the rate of thermonuclear {sup 24}O+{sup 24}O fusion and find that {sup 24}O should burn at densities near 10{sup 11} g/cm{sup 3}. The energy released from this and similar reactions may be important for the temperature profile of the star.

  14. Kinetics of osteoclasts and their nuclei in evolving secondary Haversian systems.

    PubMed Central

    Jaworski, Z F; Duck, B; Sekaly, G

    1981-01-01

    A study of osteoclast and osteoclast nuclear population kinetics within evolving secondary osteons was undertaken in young adult Beagle dogs. Autoradiographs of serial longitudinal rib biopsy sections taken from 1 hour to 15 days after tritiated thymidine injection were analysed as to the time and the rate of appearance of the labelled nuclei within the osteoclasts and their nuclei. Such systems contained an average of nine osteoclasts, each containing an average of nine nuclei. Labelled osteoclast nuclei first appeared within 24 hours, peaked at 10% at 4 days, and declined to 1% or less after 11.5 days more. Thus, the entry rate of new nuclei into (and their exit from) the population of osteoclast nuclei under steady state conditions approximates 8% per day. Therefore, the total mononuclear osteoclast population may be viewed as divided into functional units, i.e. osteoclasts. From the ratio of the osteoclast nuclei in the cutting cone to the number of osteoblasts in the closing cone (as well as from their rates of resorption and formation), it was deduced that the osteoclast per nucleus is approximately 20-40 times more efficient than the osteoblast. Because of the intrinsically different efficiencies and life spans of these two cell types, the rates of resorption and formation within evolving Haversian systems and the amounts of bone ultimately resorbed and formed by the system, are determined by the rate and duration of the respective precursor cell proliferation. It is at this level that factors which control the bone remodelling and balance must operate. Images Fig. 1 Fig. 3 PMID:7328046

  15. 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.

  16. 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.

  17. The Scattering of Fast Nucleons from Nuclei

    NASA Astrophysics Data System (ADS)

    Kerman, A. K.; McManus, H.; Thaler, R. M.

    2000-04-01

    The formal theory of the scattering of high-energy nucleons by nuclei is developed in terms of the nucleon-nucleon scattering amplitude. The most important approximations necessary to make numerical calculation feasible are then examined. The optical model potential is derived on this basis and compared with the optical model parameters found from experiment. The elastic scattering and polarization of nucleons from light nuclei is predicted and compared with experiment. The effect of nuclear correlations is discussed. The polarization of inelastically scattered nucleons is discussed and predictions compared with experiments. To within the validity of the approximations the experimental data on the scattering of nucleons from nuclei at energies above ˜100 Mev appears to be consistent with the theory.

  18. 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.

  19. Exploration of High-Dimensional Nuclei Data

    SciTech Connect

    Fuentes, Fernando; Kettani, Houssain; Ostrouchov, George; Stoitsov, Mario; Nam, Hai Ah

    2010-01-01

    Density Functional Theory (DFT) provides the theoretical foundation for a self-consistent mean-field description of the nucleus in terms of one-body densities and currents. The idea is to construct a functional whose input is the proton and neutron densities and currents, and whose output yields the ground-state energy and other properties of the nucleus. Extensive computations of ground-state energies and other observable properties of several thousand nuclei are required in order to find a universal functional that covers the entire chart of nuclei. The analysis looks for hidden relationships between observables to determine a functional that can reliably predict nuclear properties in regions where no experimental data exist. Using methods for dimension reduction and visualization tools, it is hypothesized that the deformation of the neutrons is related to other characteristics of the nuclei. The discovered relationships with the deformation of the neutrons take us a step closer toward the universal functional.

  20. Is Fusion Inhibited for Weakly Bound Nuclei?

    SciTech Connect

    Takahashi, J.; Munhoz, M.; Szanto, E.M.; Carlin, N.; Added, N.; Suaide, A.A.; de Moura, M.M.; Liguori Neto, R.; Szanto de Toledo, A.; Canto, L.F.

    1997-01-01

    Complete fusion of light radioactive nuclei is predicted to be hindered at near-barrier energies. This feature is investigated in the case of the least bound stable nuclei. Evaporation residues resulting from the {sup 6,7}Li+{sup 9}Be and {sup 6,7}Li+{sup 12}C fusion reactions have been measured in order to study common features in reactions involving light weakly bound nuclei. The experimental excitation functions revealed that the fusion cross section is significantly smaller than the total reaction cross section and also smaller than the fusion cross section expected from the available systematics. A clear correlation between the fusion probability and nucleon (cluster) separation energy has been established.The results suggest that the breakup process has a strong influence on the hindrance of the fusion cross section. {copyright} {ital 1996} {ital The American Physical Society}