71 research outputs found

    Statistical Multifragmentation in Thermodynamic Limit

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    An exact analytical solution of the statistical multifragmentation model is found in thermodynamic limit. The model exhibits a 1-st order phase transition of the liquid-gas type. The mixed phase region of the phase diagram, where the gas of nuclear fragments coexists with the infinite liquid condensate, is unambiguously identified. The peculiar thermodynamic properties of the model near the boundary between the mixed phase and the pure gaseous phase are studied. The results for the caloric curve and specific heat are presented and a physical picture of the nuclear liquid-gas phase transition is clarified.Comment: 4 figure

    Strange hadron matter and SU(3) symmetry

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    We calculate saturation curves for strange hadron matter using recently constructed baryon-baryon potentials which are constrained by SU(3) symmetry. All possible interaction channels within the baryon octet (consisting of NN, Λ\Lambda, Σ\Sigma, and Ξ\Xi) are considered. It is found that a small Λ\Lambda fraction in nuclear matter slightly increases binding, but that larger fractions (>10>10%) rapidly cause a decrease. Charge-neutral N,Λ,Ξ{N,\Lambda,\Xi} systems, with equal densities for nucleons and cascades, are only very weakly bound. The dependence of the binding energies on the strangeness per baryon, fsf_s, is predicted for various N,Λ,Ξ{N,\Lambda,\Xi} and N,Λ,Σ,Ξ{N,\Lambda,\Sigma,\Xi} systems. The implications of our results in relativistic heavy-ion collisions and the core of a dense star are discussed. We also discuss the differences between our results and previous hadron matter calculations.Comment: 14 pages RevTeX, 7 postscript figure

    Properties of Fe, Ni and Zn isotope chains near the drip-line

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    The location of proton and neutron drip-lines and the characteristics of the neutron-deficient and the neutron-rich isotopes Fe, Ni and Zn on the basis of Hartree-Fock method with Skyrme forces (Ska, SkM*, Sly4) taking into account deformation was investigated. The calculations predict a big jump of deformation parameter up to β ~ 0.4 for Ni isotopes in the neighborhood of N ~ 62. The manifestation of magic numbers for isotopes ⁴⁸Ni, ⁵⁶Ni, ⁷⁸Ni and also for the stable isotope in the respect to neutron emission ¹¹⁰Ni which is situated beyond the neutron drip-line is discussed.На основі метода Хартрі-Фока з силами Скірма (Ska, SkM*, Sly4) при врахуванні деформації досліджено положення протонної і нейтронної границі стабільності і характеристики нейтронодефіцітних і нейтрононадлишкових изотопів Fe, Ni и Zn. Розрахунки зазбачають, що для изотопів Ni в околі N ~ 62 спостерігається великий стрибок величини параметра деформації до β ~ 0.4. Обговорюються прояви магічних чисел для изотопів нікеля ⁴⁸Ni, ⁵⁶Ni, ⁷⁸Ni, а також для нейтроностабільного изотопа ¹¹⁰Ni , який знаходиться за межами границі стабильності.На основе метода Хартри-Фока с силами Скирма (Ska, SkM*, Sly4) при учете деформации исследовано положение протонной и нейтронной границы стабильности и характеристики нейтронодефицитных и нейтроноизбыточных изотопов Fe, Ni и Zn. Расчеты предсказывают, что для изотопов Ni в окрестности N ~ 62 наблюдается большой скачок величины параметра деформации до β ~ 0.4. Обсуждается проявление магических чисел для изотопов никеля ⁴⁸Ni, ⁵⁶Ni, ⁷⁸Ni, а также для нейтроностабильного изотопа ¹¹⁰Ni, который находится за пределами границы стабильности

    Space-time evolution and HBT analysis of relativistic heavy ion collisions in a chiral SU(3) x SU(3) model

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    The space-time dynamics and pion-HBT radii in central heavy ion-collisions at CERN-SPS and BNL-RHIC are investigated within a hydrodynamic simulation. The dependence of the dynamics and the HBT-parameters on the EoS is studied with different parametrisations of a chiral SU(3) sigma-omega model. The selfconsistent collective expansion includes the effects of effective hadron masses, generated by the nonstrange and strange scalar condensates. Different chiral EoS show different types of phase transitions and even a crossover. The influence of the order of the phase transition and of the difference in the latent heat on the space-time dynamics and pion-HBT radii is studied. A small latent heat, i.e. a weak first-order chiral phase transition, or even a smooth crossover leads to distinctly different HBT predictions than a strong first order phase transition. A quantitative description of the data, both at SPS energies as well as at RHIC energies, appears difficult to achieve within the ideal hydrodynamical approach using the SU(3) chiral EoS. A strong first-order quasi-adiabatic chiral phase transition seems to be disfavored by the pion-HBT data from CERN-SPS and BNL-RHIC

    Large atom number dual-species magneto-optical trap for fermionic 6Li and 40K atoms

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    We present the design, implementation and characterization of a dual-species magneto-optical trap (MOT) for fermionic 6Li and 40K atoms with large atom numbers. The MOT simultaneously contains 5.2x10^9 6Li-atoms and 8.0x10^9 40K-atoms, which are continuously loaded by a Zeeman slower for 6Li and a 2D-MOT for 40K. The atom sources induce capture rates of 1.2x10^9 6Li-atoms/s and 1.4x10^9 40K-atoms/s. Trap losses due to light-induced interspecies collisions of ~65% were observed and could be minimized to ~10% by using low magnetic field gradients and low light powers in the repumping light of both atomic species. The described system represents the starting point for the production of a large-atom number quantum degenerate Fermi-Fermi mixture

    Photon-Photon and Pomeron-Pomeron Processes in Peripheral Heavy Ion Collisions

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    We estimate the cross sections for the production of resonances, pion pairs and a central cluster of hadrons in peripheral heavy-ion collisions through two-photon and double-pomeron exchange, at energies that will be available at RHIC and LHC. The effect of the impact parameter in the diffractive reactions is introduced, and imposing the condition for realistic peripheral collisions we verify that in the case of very heavy ions the pomeron-pomeron contribution is indeed smaller than the electromagnetic one. However, they give a non-negligible background in the collision of light ions. This diffractive background will be more important at RHIC than at LHC.Comment: 22 pages, 1 Postscript figures, 4 tables, to appear in Phys. Rev.

    Hadronic freeze-out following a first order hadronization phase transition in ultrarelativistic heavy-ion collisions

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    We analyze the hadronic freeze-out in ultra-relativistic heavy ion collisions at RHIC in a transport approach which combines hydrodynamics for the early, dense, deconfined stage of the reaction with a microscopic non-equilibrium model for the later hadronic stage at which the hydrodynamic equilibrium assumptions are not valid. With this ansatz we are able to self-consistently calculate the freeze-out of the system and determine space-time hypersurfaces for individual hadron species. The space-time domains of the freeze-out for several hadron species are found to be actually four-dimensional, and differ drastically for the individual hadrons species. Freeze-out radii distributions are similar in width for most hadron species, even though the Omega-baryon is found to be emitted rather close to the phase boundary and shows the smallest freeze-out radii and times among all baryon species. The total lifetime of the system does not change by more than 10% when going from SPS to RHIC energies.Comment: 11 pages, 4 eps-figures included, revised versio

    The Misfit Strain Critical Point in the 3D Phase Diagrams of Cuprates

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    At the time of writing, data have been reported on several hundred different cuprates materials, of which a substantial fraction show superconductivity at temperatures as high as 130 K. The existence of several competing phases with comparable energy shows up in different ways in different materials, therefore it has not been possible to converge toward a universal theory for high Tc superconductivity. With the aim to find a unified description the Aeppli-Bianconi 3D phase diagram of cuprates has been proposed where the superlattice misfit strain (eta) is the third variable beyond doping (delta) and temperature T. The 3D phase diagrams for the magnetic order, and for the superconducting order extended to all cuprates families are described. We propose a formula able to describe the Tc (delta,eta) surface, this permits to identify the stripe quantum critical point at (delta)c=1/8 and (eta)c =7percent which is associated with the incommensurate to commensurate stripe phase transition, controlled by the misfit strain.Comment: 12 pages and 2 figure
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