22,687 research outputs found
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
Flow with PMD: Past and Future
Measurements of azimuthal distribution of inclusive photons using the fine
granularity preshower photon multiplicity detector (PMD) at CERN SPS are used
to obtain anisotropy in the azimuthal distributions. These results are used to
estimate the anisotropy in the neutral pion distributions. The results are
compared with results of charged particle data, both for first order and second
order anisotropy. Assuming the same anisotropy for charged and neutral pions,
the anisotropy in photons is estimated and compared with the measured
anisotropy. The effect of neutral pion decay on the correlation between the
first order and the second order event plane is also discussed. Data from PMD
can also be used to estimate the reaction plane for studying any anisotropy in
particle emission characteristics in the ALICE experiment at the Large Hadron
Collider. In particular, we show that using the event plane from the PMD, it
will be possible to measure the anisotropy in Jpsi absorption (if any) in the
ALICE experiment.Comment: Invited talk in the Fourth International Conference on the Physics
and Astrophysics of Quark Gluon Plasma, 26-30 Nov.2001, Jaipur, Indi
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
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