December 2006, Issue 20
MEETINGS:
DDA-Workshop
http://diogenes.iwt.uni-bremen.de/vt/laser/wriedt/Conferences/DDA-Workshop.html
IWT,
Light scattering programs based on methods
related to the Discrete Dipole Approximation(DDA) are
widely used because a number of programs is freely available and scattering by
particles of almost any shape or composition can easily be computed. With this
workshop we would like to invite young researchers to discuss various topics of
practical interest which arise in the application or adoption of the programs
for specific scattering problems. It is intended to have talks, discussions and
practical information on the Discrete Dipole Approximation (DDA) especially on
the following topics.
Topics
. Available programs
. Accuracy of computational results
. Parallelization
. Validation
. Particle shape input
. Large permittivity
If you are interested to participate or even
like to present a talk or present some input for discussion please send a two
page abstract (PDF) to one of the organizers by 31. Jan. 2007.
Preliminary
list of talks
Maxim Yurkin:
Current capabilities of DDA for very large particles: speed, accuracy, and
computational tricks..
Roman Schuh:
Arbitrary particle shape modelling in DDA and
validation of simulation results.
Venue
Institut für
Werkstofftechnik (IWT), Badgasteiner Str. 3, 28259 Bremen, Germany
Proceedings
We will distribute all abstracts of talks
prior to the workshop by email.
Fee
There will be no fee.
Organizing
Committee
Alfons Hoekstra, Section Computational Science,
Thomas Wriedt,
Institut für Werkstofftechnik, Bremen, Germany, thw@iwt.uni-bremen.de
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ICONO/LAT
2007
International Conference on Coherent and
Nonlinear Optics collocated with Conference on Lasers, Applications, and
Technologies
May 28-June 1, 2007
Call for papers
Abstract and Summary Deadline: February 1st,
2007, on-line paper submission will be open from December 1st, 2006, through the
SUBMISSIONS button at the conference web-site: http://congress.phys.msu.ru/iconolat07/
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NEW PAPERS:
M. Mishchenko, V. Rosenbush, and N. Kiselev, “Weak
Localization of Electromagnetic Waves and Opposition Phenomena Exhibited by
High-Albedo Atrmosphereless
Solar System Objects”, Applied Optics, v. 45, p. 4459-4463, 2006.
Abstract. The
totality of new and previous optical observations of a class of high-albedo solar-system objects at small phase angles reveals a
unique combination of extremely narrow brightness and polarization features
centered at exactly the opposition. The specific morphological parameters of
these features provide an almost unequivocal evidence
that they are caused by the renowned effect of coherent backscattering.
See
the full text at http://www.astro.ufl.edu/~elsnews/2006_AO_45_4459.pdf
Light-Scattering
Codes news:
To: Users, and potential users, of DDSCAT
From: B.T. Draine
(draine@astro.princeton.edu)
P.J. Flatau (pflatau@ucsd.edu)
Re:
DDSCAT 6.1 bug fix
Date: 2006.11.30
DDSCAT 6.1 (releases prior to 06.11.28)
contained an error that caused incorrect values of "Pol."
(= linear polarization of scattered light
when illuminated by unscattered
light) to be calculated and written to the files wxxxryykzzz.sca
and wxxxryyori.avg that are written when
IWRKSC=1 is specified in ddscat.par.
The error did not affect any of the other calculated results. In particular, the efficiency factors (Qext, Qabs, Qsca,
Qbk, Qpha),
scattering moments (<cos>
and <cos^2>), and Muller matrix elements S_ij
(written to the output files wxxxryykzzz.sca and wxxxryyori.avg),
were correct, as
were all quantities written to the files qtable and
qtable2.
The bug was in the output routine WRITESCA (file writesca.f),
and consisted simply of incorrectly evaluating P from the
(correctly-calculated) Mueller matrix
elements. New versions of the complete "plain" and "full"
distributions of DDSCAT 6.1, with the new
version of writesca.f,
can be downloaded from http://www.astro.princeton.edu/~draine/DDSCAT.6.1.html
Users who want only the corrected files version.f
and writesca.f can extract them from the gzipped tarfile with the command
tar xvfz ddscat6.1_plain.tgz src/version.f src/writesca.f
or
tar xvfz ddscat6.1_full.tgz src/version.f src/writesca.f
Note also that previously-calculaed values of the Mueller matrix elements S_{11} and
S_{12} can be used to calculate the correct value
of the polarization
P = -S_{12}/S_{11}.