2,009 research outputs found
Effects of nucleus initialization on event-by-event observables
In this work we present a study of the influence of nucleus initializations
on the event-by-event elliptic flow coefficient, . In most Monte-Carlo
models, the initial positions of the nucleons in a nucleus are completely
uncorrelated, which can lead to very high density regions. In a simple, yet
more realistic model where overlapping of the nucleons is avoided, fluctuations
in the initial conditions are reduced. However, distributions are not
very sensitive to the initialization choice.Comment: 4 pages, 5 figures, to appear in the Bras. Jour. Phy
Semihard Interactions in Nuclear Collisions Based on a Unified Approach to High Energy Scattering
Our ultimate goal is the construction of a model for interactions of two
nuclei in the energy range between several tens of GeV up to several TeV per
nucleon in the centre-of-mass system. Such nuclear collisions are very complex,
being composed of many components, and therefore some strategy is needed to
construct a reliable model. The central point of our approach is the
hypothesis, that the behavior of high energy interactions is universal
(universality hypothesis). So, for example, the hadronization of partons in
nuclear interactions follows the same rules as the one in electron-positron
annihilation; the radiation of off-shell partons in nuclear collisions is based
on the same principles as the one in deep inelastic scattering. We construct a
model for nuclear interactions in a modular fashion. The individual modules,
based on the universality hypothesis, are identified as building blocks for
more elementary interactions (like e^+ e^-, lepton-proton), and can therefore
be studied in a much simpler context. With these building blocks under control,
we can provide a quite reliable model for nucleus-nucleus scattering, providing
in particular very useful tests for the complicated numerical procedures using
Monte Carlo techniques.Comment: 10 pages, no figures; Proc. of the ``Workshop on Nuclear Matter in
Different Phases and Transitions'', Les Houches, France, March 31 - April 10,
199
Initial Condition for QGP Evolution from NEXUS
We recently proposed a new approach to high energy nuclear scattering, which
treats the initial stage of heavy ion collisions in a sophisticated way.
We are able to calculate macroscopic quantities like energy density and
velocity flow at the end of this initial stage, after the two nuclei having
penetrated each other.
In other words, we provide the initial conditions for a macroscopic treatment
of the second stage of the collision.
We address in particular the question of how to incorporate the soft
component properly. We find almost perfect "Bjorken scaling": the rapidity
coincides with the space-time rapidity, whereas the transverse flow is
practically zero. The distribution of the energy density in the transverse
plane shows typically a very "bumpy" structure.Comment: 17 pages, 24 figure
Gd(III)-Gd(III) Relaxation-Induced Dipolar Modulation Enhancement for In-Cell Electron Paramagnetic Resonance Distance Determination
In-cell distance determination by electron paramagnetic resonance (EPR) spectroscopy reveals essential structural information about biomacromolecules under native conditions. We demonstrate that the pulsed EPR technique RIDME (relaxation induced dipolar modulation enhancement) can be utilized for such distance determination. The performance of in-cell RIDME has been assessed at Q-band using stiff molecular rulers labeled with Gd(III)-PyMTA and microinjected into Xenopus laevis oocytes. The overtone coefficients are determined to be the same for protonated aqueous solutions and inside cells. As compared to in-cell DEER (double electron-electron resonance, also abbreviated as PELDOR), in-cell RIDME features approximately 5 times larger modulation depth and does not show artificial broadening in the distance distributions due to the effect of pseudosecular terms
Comparison of Hadronic Interaction Models at Auger Energies
The three hadronic interaction models DPMJET 2.55, QGSJET 01, and SIBYLL 2.1,
implemented in the air shower simulation program CORSIKA, are compared in the
energy range of interest for the Pierre Auger experiment. The model dependence
of relevant quantities in individual hadronic interactions and air showers is
investigated.Comment: Contribution to XII Int. Symp. on Very High Energy Cosmic Ray
Interactions, 4 pages, 8 figure
Attosecond transient absorption spectroscopy without inversion symmetry
Transient absorption is a very powerful observable in attosecond experiments on atoms, molecules and solids and is frequently used in experiments employing phase-locked few-cycle infrared and XUV laser pulses derived from high harmonic generation. We show numerically and analytically that in non-centrosymmetric systems, such as many polyatomic molecules, which-way interference enabled by the lack of parity conservation leads to new spectral absorption features, which directly reveal the laser electric field. The extension of attosecond transient absorption spectroscopy (ATAS) to such targets hence becomes sensitive to global and local inversion symmetry. We anticipate that ATAS will find new applications in non-centrosymmetric systems, in which the carrier-to-envelope phase of the infrared pulse becomes a relevant parameter and in which the orientation of the sample and the electronic symmetry of the molecule can be addressed
- âŠ