2,600 research outputs found
NA61-SHINE: Hadron Production Measurements for Cosmic Ray and Neutrino Experiments
As neutrino long baseline experiments enter a new domain of precision,
important systematic errors due to poor knowledge of production cross-sections
for pions and kaons require more dedicated measurements for precise neutrino
flux predictions. The cosmic ray experiments require dedicated hadron
production measurements to tune simulation models used to describe air shower
profiles. Among other goals, the NA61-SHINE (SPS Heavy Ion and Neutrino
Experiment) experiment at the CERN SPS aims at precision measurements (5% and
below) for both neutrino and cosmic ray experiments: those will improve the
prediction of the neutrino flux for the T2K experiment at J-PARC and the
prediction of muon production in the propagation of air showers for the Auger
and KASCADE experiments. Motivations for new hadron production measurements are
briefly discussed. NA61-SHINE took data during a pilot run in 2007 and in 2009
with different Carbon targets. The NA61-SHINE setup and preliminary spectra for
positive and negative pions obtained with the 2007 thin (4% interaction length)
Carbon target data are presented. The use of the NA61 data for the T2K neutrino
flux predictions is finally discussed in further details.Comment: revised versio
A general framework to construct schemes satisfying additional conservation relations. Application to entropy conservative and entropy dissipative schemes
We are interested in the approximation of a steady hyperbolic problem. In
some cases, the solution can satisfy an additional conservation relation, at
least when it is smooth. This is the case of an entropy. In this paper, we
show, starting from the discretisation of the original PDE, how to construct a
scheme that is consistent with the original PDE and the additional conservation
relation. Since one interesting example is given by the systems endowed by an
entropy, we provide one explicit solution, and show that the accuracy of the
new scheme is at most degraded by one order. In the case of a discontinuous
Galerkin scheme and a Residual distribution scheme, we show how not to degrade
the accuracy. This improves the recent results obtained in [1, 2, 3, 4] in the
sense that no particular constraints are set on quadrature formula and that a
priori maximum accuracy can still be achieved. We study the behavior of the
method on a non linear scalar problem. However, the method is not restricted to
scalar problems
The NA61/SHINE long target pilot analysis for T2K
The NA61/SHINE collaboration performed measurements of pC interactions at 31
GeV/c beam momentum with a full size replica of the T2K target (1.9 interaction
length) during a pilot run in 2007. Larger statistics runs were also conducted
in 2009 and 2010. The NA61/SHINE setup consists in a large acceptance
spectrometer located on the H2 beamline of the SPS at CERN. For the first time,
the kinematical phase space of interest for an accelerator based neutrino
experiment (i.e. kinematical phase space of pions/kaons exiting the target and
producing neutrinos in the direction of the near and far detectors) is fully
covered by a single hadron production experiment. In a first stage, yields of
positively charged pions were measured at the surface of the target. The
analysis of the 2007 data set presented here demonstrates that a) high quality
long target data were successfully taken with the NA61/SHINE apparatus, and b)
for the first time, the T2K neutrino flux predictions can effectively be
re-weighted with the NA61/SHINE long target data
Molecular Hydrogen Optical Depth Templates for FUSE Data Analysis
The calculation and use of molecular hydrogen optical depth templates to
quickly identify and model molecular hydrogen absorption features longward of
the Lyman edge at 912 Angstroms are described. Such features are commonly
encountered in spectra obtained by the Far Ultraviolet Spectroscopic Explorer
and also in spectra obtained by the Space Telescope Imaging Spectrograph,
albeit less commonly. Individual templates are calculated containing all the
Lyman and Werner transitions originating from a single rotational state (J'')
of the 0th vibrational level (v'') of the ground electronic state. Templates
are provided with 0.01 Angstrom sampling for doppler parameters ranging from 2
<= b <= 20 km s^-1 and rotational states 0 <= J'' <= 15. Optical depth
templates for excited vibrational states are also available for select doppler
parameters. Each template is calculated for a fiducial column density of
log[N(cm^-2)] = 21 and may be scaled to any column less than this value without
loss of accuracy. These templates will facilitate the determination of the
distribution of molecular hydrogen column density as a function of rotational
level. The use of these templates will free the user from the computationally
intensive task of calculating profiles for a large number of lines and allow
concentration on line profile or curve-of-growth fitting to determine column
densities and doppler parameters. The templates may be downloaded freely from
http://www.pha.jhu.edu/~stephan/h2ools2.htmlComment: 20 pages, 2 tables, 6 figures, submitted to PASP 02-04-2003 Accepted
for publication on 03-05-2003 with revisions, including modified fg1, modifed
fg6 to become fg2 to support improved error discussion. To appear in the June
2003 issue of the PAS
Design of an essentially non-oscillatory reconstruction procedure in finite-element type meshes
An essentially non oscillatory reconstruction for functions defined on finite element type meshes is designed. Two related problems are studied: the interpolation of possibly unsmooth multivariate functions on arbitary meshes and the reconstruction of a function from its averages in the control volumes surrounding the nodes of the mesh. Concerning the first problem, the behavior of the highest coefficients of two polynomial interpolations of a function that may admit discontinuities of locally regular curves is studied: the Lagrange interpolation and an approximation such that the mean of the polynomial on any control volume is equal to that of the function to be approximated. This enables the best stencil for the approximation to be chosen. The choice of the smallest possible number of stencils is addressed. Concerning the reconstruction problem, two methods were studied: one based on an adaptation of the so called reconstruction via deconvolution method to irregular meshes and one that lies on the approximation on the mean as defined above. The first method is conservative up to a quadrature formula and the second one is exactly conservative. The two methods have the expected order of accuracy, but the second one is much less expensive than the first one. Some numerical examples are given which demonstrate the efficiency of the reconstruction
On essentially non-oscillatory schemes on unstructured meshes: Analysis and implementation
A few years ago, the class of Essentially Non-Oscillatory Schemes for the numerical simulation of hyperbolic equations and systems was constructed. Since then, some extensions have been made to multidimensional simulations of compressible flows, mainly in the context of very regular structured meshes. In this paper, we first recall and improve the results of an earlier paper about non-oscillatory reconstruction on unstructured meshes, emphasizing the effective calculation of the reconstruction. Then we describe a class of numerical schemes on unstructured meshes and give some applications for its third order version. This demonstrates that a higher order of accuracy is indeed obtained, even on very irregular meshes
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