201 research outputs found
Particle and light fragment emission in peripheral heavy ion collisions at Fermi energies
A systematic investigation of the average multiplicities of light charged
particles and intermediate mass fragments emitted in peripheral and
semiperipheral collisions is presented as a function of the beam energy,
violence of the collision and mass of the system.
The data have been collected with the "Fiasco" setup in the reactions
93Nb+93Nb at 17, 23, 30, 38AMeV and 116Sn+116Sn at 30, 38AMeV.
The midvelocity emission has been separated from the emission of the
projectile-like fragment. This last component appears to be compatible with an
evaporation from an equilibrated source at normal density, as described by the
statistical code Gemini at the appropriate excitation energy.
On the contrary, the midvelocity emission presents remarkable differences for
what concerns both the dependence of the multiplicities on the energy deposited
in the midvelocity region and the isotopic composition of the emitted light
charged particles.Comment: 18 pages, 17 figures, Revtex
Space and Time pattern of mid-velocity IMF emission in peripheral heavy-ion collisions at Fermi energies
The emission pattern in the V_perp - V_par plane of Intermediate Mass
Fragments with Z=3-7 (IMF) has been studied in the collision 116Sn + 93Nb at
29.5 AMeV as a function of the Total Kinetic Energy Loss of the reaction. This
pattern shows that for peripheral reactions most of IMF's are emitted at
mid-velocity. Coulomb trajectory calculations demonstrate that these IMF's are
produced in the early stages of the reaction and shed light on geometrical
details of these emissions, suggesting that the IMF's originate both from the
neck and the surface of the interacting nuclei.Comment: 4 pages, 3 figures, RevTex 3.1, submitted to Phys. Rev. Letter
Fragmentation in Peripheral Heavy-Ion Collisions: from Neck Emission to Spectator Decays
Invariant cross sections of intermediate mass fragments in peripheral
collisions of Au on Au at incident energies between 40 and 150 AMeV have been
measured with the 4-pi multi-detector INDRA. The maximum of the fragment
production is located near mid-rapidity at the lower energies and moves
gradually towards the projectile and target rapidities as the energy is
increased. Schematic calculations within an extended Goldhaber model suggest
that the observed cross-section distributions and their evolution with energy
are predominantly the result of the clustering requirement for the emerging
fragments and of their Coulomb repulsion from the projectile and target
residues. The quantitative comparison with transverse energy spectra and
fragment charge distributions emphasizes the role of hard scattered nucleons in
the fragmentation process.Comment: 5 pages, 5 eps figures, RevTeX4, submitted to Phys. Lett.
Statistical Multifragmentation of Non-Spherical Expanding Sources in Central Heavy-Ion Collisions
We study the anisotropy effects measured with INDRA at GSI in central
collisions of Xe+Sn at 50 A.MeV and Au+Au at 60, 80, 100 A.MeV incident energy.
The microcanonical multifragmentation model with non-spherical sources is used
to simulate an incomplete shape relaxation of the multifragmenting system. This
model is employed to interpret observed anisotropic distributions in the
fragment size and mean kinetic energy. The data can be well reproduced if an
expanding prolate source aligned along the beam direction is assumed. An either
non-Hubblean or non-isotropic radial expansion is required to describe the
fragment kinetic energies and their anisotropy. The qualitative similarity of
the results for the studied reactions suggests that the concept of a
longitudinally elongated freeze-out configuration is generally applicable for
central collisions of heavy systems. The deformation decreases slightly with
increasing beam energy.Comment: 35 pages, 19 figures, submitted to Nuclear Physics
Transition from participant to spectator fragmentation in Au+Au reaction between 60 AMeV and 150 AMeV
Using the quantum molecular dynamics approach, we analyze the results of the
recent INDRA Au+Au experiments at GSI in the energy range between 60 AMeV and
150 AMeV. It turns out that in this energy region the transition toward a
participant-spectator scenario takes place. The large Au+Au system displays in
the simulations as in the experiment simultaneously dynamical and statistical
behavior which we analyze in detail: The composition of fragments close to
midrapidity follows statistical laws and the system shows bi-modality, i.e. a
sudden transition between different fragmentation pattern as a function of the
centrality as expected for a phase transition. The fragment spectra at small
and large rapidities, on the other hand, are determined by dynamics and the
system as a whole does not come to equilibrium, an observation which is
confirmed by FOPI experiments for the same system.Comment: published versio
Conformal Yano-Killing tensor for the Kerr metric and conserved quantities
Properties of (skew-symmetric) conformal Yano--Killing tensors are reviewed.
Explicit forms of three symmetric conformal Killing tensors in Kerr spacetime
are obtained from the Yano--Killing tensor. The relation between spin-2 fields
and solutions to the Maxwell equations is used in the construction of a new
conserved quantity which is quadratic in terms of the Weyl tensor. The formula
obtained is similar to the functional obtained from the Bel--Robinson tensor
and is examined in Kerr spacetime. A new interpretation of the conserved
quantity obtained is proposed.Comment: 29 page
Biodegradation of petroleum-waste by biosurfactant-producing bacteria
Abstract The degradation of petroleum waste by mixed bacterial cultures which produce biosurfactants: (reaching up to 29 % in the first 72 h). Similarly, the toxicity of the biodegraded petroleum waste decreased 3 times after 30 days as compared to raw petroleum waste. Thus, the mixed bacterial strains effectively clean-up the petroleum waste and they can be used in other bioremediation processes
Evaluation of the Safety of Neauvia Stimulate Injectable Product in Patients with Autoimmune Thyroid Diseases Based on Histopathological Examinations and Retrospective Analysis of Medical Records
The aim of this study was to test the effect of hyaluronic acid cross-linked with polyethylene glycol containing micronized portions of calcium hydroxyapatite (Neauvia Stimulate) on both local tissue and systemic consequences, which are crucial from the perspective of long-term safety, in patients suffering from Hashimoto's disease. This most common autoimmune disease is a frequently mentioned contraindication to the use of fillers based on hyaluronic acid as well as biostimulants based on calcium hydroxyapatite. Broad-spectrum aspects of histopathology were analyzed to identify key features of inflammatory infiltration before the procedure and 5, 21, and 150 days after the procedure. A statistically significant effect on the reduction of the intensity of the inflammatory infiltration in the tissue in relation to the state before the procedure was demonstrated, combined with a reduction in the occurrence of both antigen-recognizing (CD4) and cytotoxic (CD8) T lymphocytes. With complete statistical certainty, it was demonstrated that the treatment with Neauvia Stimulate had no effect on the levels of these antibodies. All this corresponds with the risk analysis that showed no alarming symptoms during the time of observation. The choice of hyaluronic acid fillers cross-linked with polyethylene glycol should be considered justified and safe in the case of patients suffering from Hashimoto's disease
The ASY-EOS experiment at GSI: investigating the symmetry energy at supra-saturation densities
The elliptic-flow ratio of neutrons with respect to protons in reactions of
neutron rich heavy-ions systems at intermediate energies has been proposed as
an observable sensitive to the strength of the symmetry term in the nuclear
Equation Of State (EOS) at supra-saturation densities. The recent results
obtained from the existing FOPI/LAND data for Au+Au collisions
at 400 MeV/nucleon in comparison with the UrQMD model allowed a first estimate
of the symmetry term of the EOS but suffer from a considerable statistical
uncertainty. In order to obtain an improved data set for Au+Au collisions and
to extend the study to other systems, a new experiment was carried out at the
GSI laboratory by the ASY-EOS collaboration in May 2011.Comment: Talk given by P. Russotto at the 11th International Conference on
Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1,
2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference
Series (JPCS
Multijet production in neutral current deep inelastic scattering at HERA and determination of α_{s}
Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson virtualities 10 5 GeV and –1 < η_{LAB}^{jet} < 2.5. Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant α_{s} (M_{z}), determined from the ratio of the trijet to dijet cross sections, is α_{s} (M_{z}) = 0.1179 ± 0.0013 (stat.)_{-0.0046}^{+0.0028}(exp.)_{-0.0046}^{+0.0028}(th.)
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