Mostrando recursos 1 - 20 de 53

  1. An empirical approach combining nuclear physics and dense nucleonic matter

    Margueron, J.
    International audience

  2. Magnetic Hexadecapole γ Transitions and Neutrino-Nuclear Responses in Medium-Heavy Nuclei

    Lotta Jokiniemi; Jouni Suhonen; Hiroyasu Ejiri
    Neutrino-nuclear responses in the form of squares of nuclear matrix elements, NMEs, are crucial for studies of neutrino-induced processes in nuclei. In this work we investigate magnetic hexadecapole (M4) NMEs in medium-heavy nuclei. The experimentally derived NMEs, MEXP(M4), deduced from observed M4 γ transition half-lives are compared with the single-quasiparticle (QP) NMEs, MQP(M4), and the microscopic quasiparticle-phonon model (MQPM) NMEs MMQPM(M4). The experimentally derived M4 NMEs are found to be reduced by a coefficient k≈0.29 with respect to MQP(M4) and by k≈0.33 with respect to MMQPM(M4). The M4 NMEs are reduced a little by the quasiparticle-phonon correlations of the MQPM...

  3. Nuclear shape phase transitions

    Vretenar D.
    The evolution of shapes and shape (phase) transitions, including regions of short-lived exotic nuclei that are becoming accessible in experiments at radioactive-beam facilities, are governed by the shell structure of single-nucleon orbitals. In most cases the transition between different shapes is gradual but in a number of examples, with the addition or subtraction of only few nucleons, signatures of abrupt changes in observables are noticed. A quantitative analysis necessitates accurate modelling of the underlying nucleonic dynamics. Important advances have been reported in theoretical studies of complex shapes, especially in the “beyond mean-field” framework based on density functionals.

  4. Excited nuclear matter at Fermi energies: From transport properties to the equation of state

    Lopez O.; Durand D.; Lehaut G.
    Properties of excited nuclear matter are one of the main subject of investigation in Nuclear Physics. Indeed, the response of nuclear matter under extreme conditions encountered in heavy-ion induced reactions (large compression, thermal and collective excitations, isopin diffusion) around the Fermi energy is strongly needed when studying the nuclear equation of state and the underlying in-medium properties concerning the nuclear interaction. In this contribution, we will present some experimental results concerning the transport properties of nuclear matter, focusing specifically on the determination of in-medium quantities such as mean free pathes and nucleon-nucleon cross sections around the Fermi energy. We will...

  5. Mesonic Decay of Charm Hypernuclei Λc+

    Ghosh Sabyasachi; Fontoura Carlos E.; Krein Gastão
    Λc+ hypernuclei are expected to have binding energies and other properties similar to those of strange hypernuclei in view of the similarity between the quark structures of the strange and charmed hyperons, namely Λ(uds) and Λc+(udc). One striking difference however occurs in their mesonic decays, as there is almost no Pauli blocking in the nucleonic decay of a charm hypernucleus because the final-state nucleons leave the nucleus at high energies. The nuclear medium nevertheless affects the mesonic decays of charm hypernucleus because the nuclear mean fields modify the masses of the charm hyperon. In the present communication we present results...

  6. General Description of Fission Observables: GEF Model Code

    Schmidt, Karl-Heinz; Jurado, Beatriz; Amouroux, Charlotte; Schmitt, C.
    The GEF (" GEneral description of Fission observables ") model code is documented. It describes the observables for spontaneous fission, neutron-induced fission and, more generally, for fission of a compound nucleus from any other entrance channel, with given excitation energy and angular momentum. The GEF model is applicable for a wide range of isotopes from Z = 80 to Z = 112 and beyond, up to excitation energies of about 100 MeV. The results of the GEF model are compared with fission barriers, fission probabilities, fission-fragment mass-and nuclide distributions, isomeric ratios, total kinetic energies, and prompt-neutron and prompt-gamma yields and...

  7. Real time processing of neutron monitor data using the edge editor algorithm

    Mavromichalaki Helen; Paschalis Pavlos
    The nucleonic component of the secondary cosmic rays is measured by the worldwide network of neutron monitors (NMs). In most cases, a NM station publishes the measured data in a real time basis in order to be available for instant use from the scientific community. The space weather centers and the online applications such as the ground level enhancement (GLE) alert make use of the online data and are highly dependent on their quality. However, the primary data in some cases are distorted due to unpredictable instrument variations. For this reason, the real time primary data processing of the measured...

  8. Dense nucleonic matter and the renormalization group

    Drews Matthias; Hell Thomas; Klein Bertram; Weise Wolfram
    Fluctuations are included in a chiral nucleon-meson model within the framework of the functional renormalization group. The model, with parameters fitted to reproduce the nuclear liquid-gas phase transition, is used to study the phase diagram of QCD. We find good agreement with results from chiral effective field theory. Moreover, the results show a separation of the chemical freeze-out line and chiral symmetry restoration at large baryon chemical potentials.

  9. The detection of solar proton produced 14CO

    P. Jöckel; C. A. M. Brenninkmeijer; M. G. Lawrence; P. Siegmund
    Major solar eruptions (coronal mass ejections) are accompanied by massive ejections of protons. When these charged particles head for the Earth through the interplanetary magnetic field with high flux and energy, a solar proton event (SPE) is recorded. Strong SPEs, in which energetic protons penetrate the atmosphere in large numbers are rare, but do have chemical effects (Crutzen, 1975; Jackman et al., 1990, 2001).  They also have nucleonic effects by which they can almost instantaneously increase the atmospheric production of radio-nuclides, including 14C (radiocarbon), but this has never been demonstrated. We show, using satellite observations and modeling, that the 2nd...

  10. From crystalline to exotic arrangements of matter in neutron star crusts

    Figerou S.; Sébille F.; de la Mota V.; Eudes Ph.
    We investigate the occurrence of exotic structures in the outermost layers of neutron stars within the framework of a microscopic model describing the nucleonic dynamics through a time-dependent mean field approach at around zero temperature. In this model starting from an initial crystalline lattice of nuclei at subnuclear densities the system evolves and self-organizes in various low-lying energy structures without assumption of final shapes. These structures are studied in terms of a density phase diagram. We investigate their sensitivity to the isotopic composition and to the symmetries of the lattice.

  11. Atmospheric electric field effects of cosmic rays detected in Mexico City

    J. F. Valdés-Galicia; L. X. González
    We studied the possible effects of atmospheric electric fields, generated in thunderstorms, on the cosmic ray intensity detected at the Earth’s surface by investigating the variations of the counting rates of the cosmic-ray nucleonic component, obtained from the neutron monitor installed in Mexico City, for thunderstorms during 1996 and 1997. These were years of minimum solar activity. We compare our experimental results with the general theory of cosmic ray meteorological effects by Dorman (1995).The observed intensity variation is about 0.2%. According to Dorman (1995), the effect should be between 0.27% and 0.81% on the counting rate of the neutron monitor...

  12. Electroweak reactions with light nuclei

    Bacca S.
    The investigation of light nuclei with ab-initio methods provides an optimal setting to probe our knowledge on nuclear forces, because the few-nucleon problem can be solved accurately. Nucleons interact not only in pairs but also via many-body forces. Theoretical efforts need to be taken towards the identification of nuclear observables sensitive to the less known many-nucleon forces. Electromagnetic reactions can potentially provide useful information on this. We present results on photo-absorption and electron scattering off light nuclei, emphasizing the role of three-body forces and the comparison with experimental data. On the other hand, reactions induced by weak probes, like neutrino...

  13. Nuclear stopping for heavy-ion induced reactions in the Fermi energy range : from 1-Body to 2-Body dissipation

    Lopez O.; Lehaut G.; Durand D.; Aouadi M.
    We study the stopping in heavy-ion induced reactions around the Fermi energy in central collisions. The stopping is minimal around the Fermi energy and corresponds to the crossover between the Mean-Field and the nucleonic regimes. This is attributed to the change in the energy dissipation going from 1-body (Mean-Field) to 2-body (nucleonnucleon collisions) dissipation. For this latter, a connection to in-medium transport properties of nuclear matter is proposed and comprehensive values of the nucleon mean free path and nucleon-nucleon cross section are extracted.

  14. CONTROL OF ACTIVATORS OF SHARP INTESTINAL INFECTIONS OVER BASIS PCR-RT Контроль возбудителей острых кишечных инфекций на основе ПЦР-РТ

    Brovkina A. N.
    The "multiplex" PCR technique in a combination with automatic extraction of nucleonic acids allows to carry out the control of activators of sharp intestinal infections of the bacterial and virus nature over objects of an environment with high speed, specificity and sensitivity

  15. Neutron spectroscopic factors of 55Ni hole-states from (p,d) transfer reactions

    A. Sanetullaev; M.B. Tsang; W.G. Lynch; Jenny Lee; D. Bazin; K.P. Chan; D. Coupland; V. Henzl; D. Henzlova; M. Kilburn; A.M. Rogers; Z.Y. Sun; M. Youngs; R.J. Charity; L.G. Sobotka; M. Famiano; S. Hudan; D. Shapira; W.A. Peters; C. Barbieri; M. Hjorth-Jensen; M. Horoi; T. Otsuka; T. Suzuki; Y. Utsuno
    Spectroscopic information has been extracted on the hole-states of 55Ni, the least known of the quartet of nuclei (55Ni, 57Ni, 55Co and 57Cu), one nucleon away from 56Ni, the N=Z=28 double magic nucleus. Using the H1(Ni56,d)Ni55 transfer reaction in inverse kinematics, neutron spectroscopic factors, spins and parities have been extracted for the f7/2, p3/2 and the s1/2 hole-states of 55Ni. These new data provide a benchmark for large basis calculations that include nucleonic orbits in both the sd and pf shells. State of the art calculations have been performed to describe the excitation energies and spectroscopic factors of the s1/2...

  16. Neutron–proton effective mass splitting in neutron-rich matter at normal density from analyzing nucleon–nucleus scattering data within an isospin dependent optical model

    Xiao-Hua Li; Wen-Jun Guo; Bao-An Li; Lie-Wen Chen; Farrukh J. Fattoyev; William G. Newton
    The neutron–proton effective mass splitting in asymmetric nucleonic matter of isospin asymmetry δ and normal density is found to be mn−p⁎≡(mn⁎−mp⁎)/m=(0.41±0.15)δ from analyzing globally 1088 sets of reaction and angular differential cross sections of proton elastic scattering on 130 targets with beam energies from 0.783 MeV to 200 MeV, and 1161 sets of data of neutron elastic scattering on 104 targets with beam energies from 0.05 MeV to 200 MeV within an isospin dependent non-relativistic optical potential model. It sets a useful reference for testing model predictions on the momentum dependence of the nucleon isovector potential necessary for understanding novel...

  17. A new population of very high energy gamma-ray sources in the Milky Way

    Aharonian, F.; G. Akhperjanian, A.; Aye, K.-M.; R. Bazer-Bachi, A.; Beilicke, M.; Benbow, W.; Berge, D.; Berghaus, P.; Bernlöhr, K.; Boisson, C.; Bolz, O.; Borgmeier, C.; Braun, I.; Breitling, F.; M. Brown, A.; Bussons Gordo, J.; M. Chadwick, P.; Chounet, L.-M.; Cornils, R.; Costamante, L.; Degrange, B.; Djannati-Ataï, A.; O'C. Drury, L.; Dubus, G.; Ergin, T.; Espigat, P.; Feinstein, F.; Fleury, P.; Fontaine, G.; Funk, S.; Gallant, Y.A.; Giebels, B.; Gillessen, S.; Goret, P.; Hadjichristidis, C.; Hauser, M.; Heinzelmann, G.; Henri, G.; Hermann, G.; A. Hinton, J.; Hofmann, W.; Holleran, M.; Horns, D.; C. De Jager, O.; Jung, I.; Khélifi, B.; Komin, Nu.; Konopelko, A.; J. Latham, I.; Le Gallou, R.; Lemière, A.; Lemoine, M.; Leroy, N.; Lohse, T.; Marcowith, A.; Masterson, C.; J. L. Mccomb, T.; De Naurois, M.; J. Nolan, S.; Noutsos, A.; J. Orford, K.; L. Osborne, J.; Ouchrif, M.; Panter, M.; Pelletier, G.; Pita, S.; Pühlhofer, G.; Punch, M.; C. Raubenheimer, B.; Raue, M.; Raux, J.; M. Rayner, S.; Redondo, I.; Reimer, A.; Reimer, O.; Ripken, J.; Rob, L.; Rolland, L.; Rowell, G.; Sahakian, V.; Saugé, L.; Schlenker, S.; Schlickeiser, R.; Schuster, C.; Schwanke, U.; Siewert, M.; Sol, H.; Steenkamp, R.; Stegmann, C.; Tavernet, J.-P.; Terrier, R.; Théoret, C.G.; Tluczykont, M.; J. Van Der Walt, D.; Vasileiadis, G.; Venter, C.; Vincent, P.; Visser, B.; J. Völk, H.; J. Wagner, S.
    Very high energy gamma-rays probe the long-standing mystery of the origin of cosmic rays. Produced in the interactions of accelerated particles in astrophysical objects, they can be used to image cosmic particle accelerators. A first sensitive survey of the inner part of the Milky Way with the High Energy Stereoscopic System (H.E.S.S.) reveals a population of eight previously unknown firmly detected sources of very high energy gamma-rays. At least two have no known radio or X-ray counterpart and may be representative of a new class of `dark' nucleonic cosmic ray sources.

  18. Palliser Rockslide cosmogenic 36Cl exposure ages (raw data) and erosion effect on the cosmogenic

    Sturzenegger, Matthieu; Stead, Doug; Gosse, John; Ward, Brent; Froese, Corey
    This paper presents the results of a combined study, using cosmogenic 36Cl exposure dating and terrestrial digital photogrammetry, of the Palliser Rockslide located in the southeastern Canadian Rocky Mountains. This site is particularly well-suited to demonstrate how this multi-disciplinary approach can be used to differentiate distinct rocksliding events, estimate their volume, and establish their chronology and recurrence interval. Observations suggest that rocksliding has been ongoing since the late Pleistocene deglaciation. Two major rockslide events have been dated at 10.0 ± 1.2 kyr and 7.7 ± 0.8 kyr before present, with failure volumes of 40 Mm3 and 8 Mm3, respectively. The...

  19. Properties of deformed Lambda hypernuclei

    Zhou, X. R.; 周先荣
    The properties of Be and B isotopes and the corresponding A hypernuclei are studied by using a deformed Skyrme Hartree-Fock approach with realistic nucleonic Skyrme forces, pairing correlations, and a microscopically determined lambda-nucleon interaction based on calculations of hupernuclear matter. The results suggest. that the core nuclei and die corresponding, hypernuclei have similar deformations with the same sign.

  20. Nonrelativistic mean-field description of the deformation of I > hypernuclei

    Zhou, X. R.; Cui, J. W.; Wei, N.; 周先荣
    The deformations of light I > hypernuclei are studied in an extended nonrelativistic deformed Skyrme-Hartree-Fock approach with realistic modern nucleonic Skyrme forces, pairing correlations, and a microscopical lambda-nucleon interaction derived from Brueckner-Hartree-Fock calculations. Compared to the large effect of an additional I > particle on nuclear deformation in the light soft nuclei within relativistic mean field method, this effect is much smaller in the nonrelativistic mean-field approximation.

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