15,456 research outputs found
Discrepancies in Atomic Data and Suggestions for their Resolutions
The analysis and modelling of a range of plasmas (for example: astrophysical,
laser-produced and fusion), require atomic data for a number of parameters,
such as energy levels, radiative rates and electron impact excitation rates, or
equivalently the effective collision strengths. Such data are desired for a
wide range of elements and their many ions, although all elements are not
useful for all types of plasmas. Since measurements of atomic data are mostly
confined to only a few energy levels of some ions, calculations for all
parameters are highly important. However, often there are large discrepancies
among different calculations for almost all parameters, which makes it
difficult to apply the data with confidence. Many such discrepancies (and the
possible remedies) were discussed earlier (Fusion Sci. Tech. 2013, 63, 363).
Since then a lot more anomalies for almost all of these atomic parameters have
come to notice. Therefore, this paper is a revisit of various atomic parameters
to highlight the large discrepancies, their possible sources and some
suggestions to avoid those, so that comparatively more accurate and reliable
atomic data may be available in the future.Comment: 18 pages of text including 7 figures will appear in Atoms 5 (2017
Energy Levels and Radiative Rates for Transitions in F-like Sc~XIII and Ne-like Sc~XII and Y~XXX
Energy levels, radiative rates and lifetimes are reported for F-like Sc~XIII
and Ne-like Sc~XII and Y~XXX for which the general-purpose relativistic atomic
structure package ({\sc grasp}) has been adopted. For all three ions limited
data exist in the literature but comparisons have been made wherever possible
to assess the accuracy of the calculations. In the present work the lowest 102,
125 and 139 levels have been considered for the respective ions. Additionally,
calculations have also been performed with the flexible atomic code ({\sc fac})
to (particularly) confirm the accuracy of energy levels.Comment: 24pp of Text including 12 Tables will appear in Atoms 6 (2018
Electron impact excitation of F-like W LXVI
Electron impact excitation collision strengths are calculated for all
transitions among 113 levels of the 2s2p, 2s2p,
2s2p3, 2s2p3, and 2p3 configurations of
F-like W~LXVI. For this purpose Dirac Atomic R-matrix Code (DARC) has been
adopted and results are listed over a wide energy range of 1000 to 6000 Ryd.
For comparison purpose analogous calculations have also been performed with the
Flexible Atomic Code (FAC), and the results obtained are comparable with those
from DARC.Comment: 17p paper including 2 Tables and 4 Figures will appear in vol. 4 of
ATOMS in 201
Photon Multiplicity Measurements : From SPS to RHIC and LHC
Results from the photon multiplicity measurements using a fine granularity
preshower photon multiplicity detector (PMD) at CERN SPS are discussed. These
include study of pseudo-rapidity distributions of photons, scaling of photon
multiplicity with number of participating nucleons, centrality dependence of
mean transverse momentum of photons, event-by-event fluctuations in photon
multiplicity and localised charged-neutral fluctuations. Basic features of the
PMD to be used in STAR experiment at RHIC and in ALICE experiment at LHC are
also discussed.Comment: 12 pages, Invited talk at the 4th International Conference on the
Physcis and Astrophysics of the Quark-Gluon-Plasma, November 2001, Jaipur,
India, to appear in Praman
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