287 research outputs found
Deep learning driven self-adaptive hp finite element method
The fi nite element method (FEM) is a popular tool for solving engineering problems governed by Partial Di fferential Equations (PDEs). The accuracy of the numerical solution depends on the quality of the computational mesh. We consider the self-adaptive hp-FEM, which generates optimal mesh refi nements and delivers exponential convergence of the numerical error with respect to the mesh size. Thus, it enables solving di ficult engineering problems with the highest possible numerical accuracy. We replace the computationally expensive kernel of the refi nement algorithm with a deep neural network in this work. The network learns how to optimally re fine the elements and modify the orders of the polynomials. In this way, the deterministic algorithm is replaced
by a neural network that selects similar quality refi nements in a fraction of the time needed by the original algorithm
Freeze-out configuration properties in the 197Au + 197Au reaction at 23 AMeV
Data from the experiment on the 197Au + 197Au reaction at 23 AMeV are
analyzed with an aim to find signatures of exotic nuclear configurations such
as toroid-shaped objects. The experimental data are compared with predictions
of the ETNA code dedicated to look for such configurations and with the QMD
model. A novel criterion of selecting events possibly resulting from the
formation of exotic freeze-out configurations, "the efficiency factor", is
tested. Comparison between experimental data and model predictions may indicate
for the formation of flat/toroidal nuclear systems
Kinematical coincidence method in transfer reactions
A new method to extract high resolution angular distributions from
kinematical coincidence measurements in binary reactions is presented.
Kinematic is used to extract the center of mass angular distribution from the
measured energy spectrum of light particles. Results obtained in the case of
10Be+p-->9Be+d reaction measured with the CHIMERA detector are shown. An
angular resolution of few degrees in the center of mass is obtained.Comment: 6 Page 10 Figures submitted to Nuclear Instruments and Methods
Projected Quasi-particle Perturbation theory
The BCS and/or HFB theories are extended by treating the effect of four
quasi-particle states perturbatively. The approach is tested on the pairing
hamiltonian, showing that it combines the advantage of standard perturbation
theory valid at low pairing strength and of non-perturbative approaches
breaking particle number valid at higher pairing strength. Including the
restoration of particle number, further improves the description of pairing
correlation. In the presented test, the agreement between the exact solution
and the combined perturbative + projection is almost perfect. The proposed
method scales friendly when the number of particles increases and provides a
simple alternative to other more complicated approaches
Mass and charge identification of fragments detected with the Chimera Silicon-CsI(Tl) telescopes
Mass and charge identification of charged products detected with
Silicon-CsI(Tl) telescopes of the Chimera apparatus is presented. An
identification function, based on the Bethe-Bloch formula, is used to fit
empirical correlation between Delta E and E ADC readings, in order to
determine, event by event, the atomic and mass numbers of the detected charged
reaction products prior to energy calibration.Comment: 24 pages, 7 .jpg figures, submitted to Nucl.Instr.
Isotope correlations as a probe for freeze-out characterization: central 124Sn+64Ni, 112Sn+58Ni collisions
124Sn+64Ni and 112Sn+58Ni reactions at 35 AMeV incident energy were studied
with the forward part of CHIMERA multi-detector. The most central collisions
were selected by means of a multidimensional analysis. The characteristics of
the source formed in the central collisions, as size, temperature and volume,
were inspected. The measured isotopes of light fragments (3 <= Z <=8) were used
to examine isotope yield ratios that provide information on the free neutron to
proton densities.Comment: 4 pages, Contribution to 8th International Conference on
Nucleus-Nucleus Collisions, Moscow 200
Pion emission from the T2K replica target: method, results and application
The T2K long-baseline neutrino oscillation experiment in Japan needs precise
predictions of the initial neutrino flux. The highest precision can be reached
based on detailed measurements of hadron emission from the same target as used
by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. The
corresponding data were recorded in 2007-2010 by the NA61/SHINE experiment at
the CERN SPS using a replica of the T2K graphite target. In this paper details
of the experiment, data taking, data analysis method and results from the 2007
pilot run are presented. Furthermore, the application of the NA61/SHINE
measurements to the predictions of the T2K initial neutrino flux is described
and discussed.Comment: updated version as published by NIM
Measurement of Production Properties of Positively Charged Kaons in Proton-Carbon Interactions at 31 GeV/c
Spectra of positively charged kaons in p+C interactions at 31 GeV/c were
measured with the NA61/SHINE spectrometer at the CERN SPS. The analysis is
based on the full set of data collected in 2007 with a graphite target with a
thickness of 4% of a nuclear interaction length. Interaction cross sections and
charged pion spectra were already measured using the same set of data. These
new measurements in combination with the published ones are required to improve
predictions of the neutrino flux for the T2K long baseline neutrino oscillation
experiment in Japan. In particular, the knowledge of kaon production is crucial
for precisely predicting the intrinsic electron neutrino component and the high
energy tail of the T2K beam. The results are presented as a function of
laboratory momentum in 2 intervals of the laboratory polar angle covering the
range from 20 up to 240 mrad. The kaon spectra are compared with predictions of
several hadron production models. Using the published pion results and the new
kaon data, the K+/\pi+ ratios are computed.Comment: 10 pages, 11 figure
Measurement of negatively charged pion spectra in inelastic p+p interactions at = 20, 31, 40, 80 and 158 GeV/c
We present experimental results on inclusive spectra and mean multiplicities
of negatively charged pions produced in inelastic p+p interactions at incident
projectile momenta of 20, 31, 40, 80 and 158 GeV/c ( 6.3, 7.7,
8.8, 12.3 and 17.3 GeV, respectively). The measurements were performed using
the large acceptance NA61/SHINE hadron spectrometer at the CERN Super Proton
Synchrotron.
Two-dimensional spectra are determined in terms of rapidity and transverse
momentum. Their properties such as the width of rapidity distributions and the
inverse slope parameter of transverse mass spectra are extracted and their
collision energy dependences are presented. The results on inelastic p+p
interactions are compared with the corresponding data on central Pb+Pb
collisions measured by the NA49 experiment at the CERN SPS.
The results presented in this paper are part of the NA61/SHINE ion program
devoted to the study of the properties of the onset of deconfinement and search
for the critical point of strongly interacting matter. They are required for
interpretation of results on nucleus-nucleus and proton-nucleus collisions.Comment: Numerical results available at: https://edms.cern.ch/document/1314605
Updates in v3: Updated version, as accepted for publicatio
Multiplicity and transverse momentum fluctuations in inelastic proton-proton interactions at the CERN Super Proton Synchrotron
Measurements of multiplicity and transverse momentum fluctuations of charged
particles were performed in inelastic p+p interactions at 20, 31, 40, 80 and
158 GeV/c beam momentum. Results for the scaled variance of the multiplicity
distribution and for three strongly intensive measures of multiplicity and
transverse momentum fluctuations \$\Delta[P_{T},N]\$, \$\Sigma[P_{T},N]\$ and
\$\Phi_{p_T}\$ are presented. For the first time the results on fluctuations
are fully corrected for experimental biases. The results on multiplicity and
transverse momentum fluctuations significantly deviate from expectations for
the independent particle production. They also depend on charges of selected
hadrons. The string-resonance Monte Carlo models EPOS and UrQMD do not describe
the data. The scaled variance of multiplicity fluctuations is significantly
higher in inelastic p+p interactions than in central Pb+Pb collisions measured
by NA49 at the same energy per nucleon. This is in qualitative disagreement
with the predictions of the Wounded Nucleon Model. Within the statistical
framework the enhanced multiplicity fluctuations in inelastic p+p interactions
can be interpreted as due to event-by-event fluctuations of the fireball energy
and/or volume.Comment: 18 pages, 12 figure
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