4,726 research outputs found

    Evolution of Efimov states into the continuum in neutron rich (2n-core) nuclei - A general study

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    The nuclear three-body system, with two halo neutrons very weakly coupled to a heavy core, is studied to investigate necessary conditions for the occurrence of Efimov states. Extending the analysis to the scattering sector, we find that these states evolve into Feshbach type resonances. This behaviour is very similar to the 20C nucleus in which the occurrence of Efimov states evolving into resonances in the elastic scattering of n?19C system has been investigated in recent publications. This work, thereby, extends the study of the Efimov effect beyond 20C, showing that 32Ne and 38Mg exhibit a very similar dynamical structure. These nuclei are, therefore, also candidates for probing experimentally the Efimov effect. © 2011 Elsevier B.V

    Electrooptical Evaluation Techniques of Image Intensifier 'Ibbes - Part I

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    Passive night vision devices are used for viewing the military targets at low light levels of illuminations during night. In these passive night vision devices, image intensifier tubes areused to amplify scene imagery. The performance of these tubes depends upon electrooptical parameters. The techniques of evaluating these parameters, eg, luminous gain, automatic rightness control and maximum screen luminance, photocathode sensitivity, radiant gain, equivalent background illumination, magnification and distortion, signal-to-noise ratio, veilingglare, screen brightness variation, etc. have been described

    Electrooptical Evaluation Techniques of Image Intensifier Tubes-Part I1

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    In this paper, electrooptical evaluation techniques of image intensifier tubes for some of the important parameters like resolving power, absolute spectral responses of photocathode,  spectral response of phosphor screen, modulation transfer function, recovery time, gas grade, and fixed-pattern noise have been described

    Efimov states and their Fano resonances in a neutron-rich nucleus

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    Asymmetric resonances in elastic n+19^{19}C scattering are attributed to Efimov states of such neutron-rich nuclei, that is, three-body bound states of the n+n+18^{18}C system when none of the pairs is bound or some of them only weakly bound. By fitting to the general resonance shape described by Fano, we extract resonance position, width, and the "Fano profile index". While Efimov states have been discussed extensively in many areas of physics, there is only one very recent experimental observation in trimers of cesium atoms. The conjunction that we present of the Efimov and Fano phenomena may lead to experimental realization in nuclei.Comment: 4 double-column pages, 3 figure

    Challenges in QCD matter physics - The Compressed Baryonic Matter experiment at FAIR

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    Substantial experimental and theoretical efforts worldwide are devoted to explore the phase diagram of strongly interacting matter. At LHC and top RHIC energies, QCD matter is studied at very high temperatures and nearly vanishing net-baryon densities. There is evidence that a Quark-Gluon-Plasma (QGP) was created at experiments at RHIC and LHC. The transition from the QGP back to the hadron gas is found to be a smooth cross over. For larger net-baryon densities and lower temperatures, it is expected that the QCD phase diagram exhibits a rich structure, such as a first-order phase transition between hadronic and partonic matter which terminates in a critical point, or exotic phases like quarkyonic matter. The discovery of these landmarks would be a breakthrough in our understanding of the strong interaction and is therefore in the focus of various high-energy heavy-ion research programs. The Compressed Baryonic Matter (CBM) experiment at FAIR will play a unique role in the exploration of the QCD phase diagram in the region of high net-baryon densities, because it is designed to run at unprecedented interaction rates. High-rate operation is the key prerequisite for high-precision measurements of multi-differential observables and of rare diagnostic probes which are sensitive to the dense phase of the nuclear fireball. The goal of the CBM experiment at SIS100 (sqrt(s_NN) = 2.7 - 4.9 GeV) is to discover fundamental properties of QCD matter: the phase structure at large baryon-chemical potentials (mu_B > 500 MeV), effects of chiral symmetry, and the equation-of-state at high density as it is expected to occur in the core of neutron stars. In this article, we review the motivation for and the physics programme of CBM, including activities before the start of data taking in 2022, in the context of the worldwide efforts to explore high-density QCD matter.Comment: 15 pages, 11 figures. Published in European Physical Journal

    Nuclear matter at high density: Phase transitions, multiquark states, and supernova outbursts

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    Phase transition from hadronic matter to quark-gluon matter is discussed for various regimes of temperature and baryon number density. For small and medium densities, the phase transition is accurately described in the framework of the Field Correlation Method, whereas at high density predictions are less certain and leave room for the phenomenological models. We study formation of multiquark states (MQS) at zero temperature and high density. Relevant MQS components of the nuclear matter can be described using a previously developed formalism of the quark compound bags (QCB). Partial-wave analysis of nucleon-nucleon scattering indicates the existence of 6QS which manifest themselves as poles of PP-matrix. In the framework of the QCB model, we formulate a self-consistent system of coupled equations for the nucleon and 6QS propagators in nuclear matter and the G-matrix. The approach provides a link between high-density nuclear matter with the MQS components and the cumulative effect observed in reactions on the nuclei, which requires the admixture of MQS in the wave functions of nuclei kinematically. 6QS determine the natural scale of the density for a possible phase transition into the MQS phase of nuclear matter. Such a phase transition can lead to dynamic instability of newly born protoneutron stars and dramatically affect the dynamics of supernovae. Numerical simulations show that the phase transition may be a good remedy for the triggering supernova explosions in the spherically symmetric supernova models. A specific signature of the phase transition is an additional neutrino peak in the neutrino light curve. For a Galactic core-collapse supernova, such a peak could be resolved by the present neutrino detectors. The possibility of extracting the parameters of the phase of transition from observation of the neutrino signal is discussed also.Comment: 57 pages, 22 figures, 7 tables; RevTeX 4; submitted to Phys. Atom. Nuc

    Centrality and Transverse Momentum Dependence of Elliptic Flow of Multistrange Hadrons and \u3cem\u3eϕ\u3c/em\u3e Meson in Au + Au Collisions at √\u3cem\u3e\u3csup\u3es\u3c/sup\u3e\u3csub\u3eNN\u3c/sub\u3e\u3c/em\u3e = 200 GeV

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    We present high precision measurements of elliptic flow near midrapidity (|y| \u3c 1.0) for multistrange hadrons and ϕ meson as a function of centrality and transverse momentum in Au + Au collisions at center of mass energy √sNN = 200  GeV. We observe that the transverse momentum dependence of ϕ and Ω υ2 is similar to that of π and p, respectively, which may indicate that the heavier strange quark flows as strongly as the lighter up and down quarks. This observation constitutes a clear piece of evidence for the development of partonic collectivity in heavy-ion collisions at the top RHIC energy. Number of constituent quark scaling is found to hold within statistical uncertainty for both 0%–30% and 30%–80% collision centrality. There is an indication of the breakdown of previously observed mass ordering between ϕ and proton υ2 at low transverse momentum in the 0%–30% centrality range, possibly indicating late hadronic interactions affecting the proton υ2
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