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VERSION:2.0
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BEGIN:VEVENT
SUMMARY:Path integral MC in real-time for open systems: challenges and app
lications
DTSTART;VALUE=DATE-TIME:20130220T165000Z
DTEND;VALUE=DATE-TIME:20130220T173000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-24@cern.ch
DESCRIPTION:Speakers: ANKERHOLD\, Joachim (Ulm)\nQuantum systems interacti
ng with surrounding reservoirs are of fundamental interest in atomic\, mol
ecular\, and condensed matter physics. Due to the impressive experimental
progress in tailoring and controlling quantum devices on nano- and microsc
ales\, theory is challenged to provide a detailed understanding of the non
equilibrum dynamics also in presence of external forces.\nA formally exact
description is based on path integrals which can efficiently been evaluat
ed with corresponding MC techniques. These have been substantially\nimprov
ed in the last decade to capture interactions with bosonic as well as ferm
ionic reservoirs. In this talk I will describe the main challenges\, numer
ical techniques\, and typical applications.\n\nhttps://indico.desy.de/indi
co/event/6196/contribution/24
LOCATION:DESY Hamburg
URL:https://indico.desy.de/indico/event/6196/contribution/24
END:VEVENT
BEGIN:VEVENT
SUMMARY:Approximate Bayesian computation (ABC): advances and questions
DTSTART;VALUE=DATE-TIME:20130220T134000Z
DTEND;VALUE=DATE-TIME:20130220T142000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-20@cern.ch
DESCRIPTION:Speakers: ROBERT\, Christian (Université Paris Dauphine\, Fra
nce)\nThe lack of closed form likelihoods has been the bane of Bayesian co
mputation for many years and\, prior to the introduction of MCMC methods\,
a strong impediment to the propagation of the Bayesian paradigm. We are n
ow facing models where an MCMC completion of the model towards closed-form
likelihoods seems unachievable and where a further degree of approximatio
n appears unavoidable. In this tutorial\, I will present the motivation fo
r approximative Bayesian computation (ABC) methods\, the various implement
ations found in the current literature\, as well as the inferential\, rath
er than computational\,\nchallenges set by these methods.\n\nhttps://indic
o.desy.de/indico/event/6196/contribution/20
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/20
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ensemble Methods in Atmospheric Data Assimilation
DTSTART;VALUE=DATE-TIME:20130220T161000Z
DTEND;VALUE=DATE-TIME:20130220T165000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-21@cern.ch
DESCRIPTION:Speakers: ANLAUF\, Harald (Deutscher Wetterdienst)\nIn numeric
al weather prediction\, data assimilation estimates the initial conditions
for the forecast model by a statistical process that combines observation
al data with past information. In recent years\, ensemble methods in data
assimilation have matured to the extent that they are considered benefici
al for operational numerical weather prediction. After a brief introducti
on to data assimilation\, the presentation describes popular and efficient
incarnations of Ensemble Kalman Filters and provides an outlook to Partic
le Filters for non-linear data assimilation which is a subject of current
research.\n\nhttps://indico.desy.de/indico/event/6196/contribution/21
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/21
END:VEVENT
BEGIN:VEVENT
SUMMARY:Welcome and introduction
DTSTART;VALUE=DATE-TIME:20130219T123000Z
DTEND;VALUE=DATE-TIME:20130219T130000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-23@cern.ch
DESCRIPTION:Speakers: \nhttps://indico.desy.de/indico/event/6196/contribut
ion/23
LOCATION:DESY Hamburg Lecture hall
URL:https://indico.desy.de/indico/event/6196/contribution/23
END:VEVENT
BEGIN:VEVENT
SUMMARY:DESY Seminar: Fifty Years Later\, Are Those Random Numbers Finally
Good Enough?
DTSTART;VALUE=DATE-TIME:20130219T154500Z
DTEND;VALUE=DATE-TIME:20130219T173000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-1@cern.ch
DESCRIPTION:Speakers: Dr. JAMES\, Frederick (CERN)\nAs a grad student in 1
962\, I discovered that the funny MC results I was getting were caused by
a poor random number generator. Thirty years after that\, the Phys Rev Le
tters paper of Ferrenberg et al showed that things had not yet improved\,
relative to the increased complexity of problems we were trying to solve.
Then suddenly\, due to the work of theoretical physicists\, the situation
changed dramatically\, both with respect to pseudorandom numbers (the kind
most of us use) and quasirandom points (the kind that are supposed to giv
e convergence faster than 1/sqrt(N) ). But very few MC users seem to be a
ware of the recent results in this field traditionally reserved for number
theorists.\n\nhttps://indico.desy.de/indico/event/6196/contribution/1
LOCATION:DESY Hamburg Lecture hall
URL:https://indico.desy.de/indico/event/6196/contribution/1
END:VEVENT
BEGIN:VEVENT
SUMMARY:Guided tour of DESY
DTSTART;VALUE=DATE-TIME:20130221T140000Z
DTEND;VALUE=DATE-TIME:20130221T154500Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-0@cern.ch
DESCRIPTION:Speakers: \nhttps://indico.desy.de/indico/event/6196/contribut
ion/0
LOCATION:DESY Hamburg
URL:https://indico.desy.de/indico/event/6196/contribution/0
END:VEVENT
BEGIN:VEVENT
SUMMARY:Uncertainty management in traffic modelling
DTSTART;VALUE=DATE-TIME:20130220T084000Z
DTEND;VALUE=DATE-TIME:20130220T092000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-3@cern.ch
DESCRIPTION:Speakers: PUNZO\, Vincenzo (UNINA)\, CIUFFO\, Biagio (UNINA)\n
In the last century\, contributions from engineers\, physicists\, mathemat
icians\, and behavioural psychologists have lad to a better understanding
of driver behaviour and vehicular traffic flow. The focus is the ability t
o forecast the effect on real systems of different applications ranging fr
om novel driver-assistance systems\, to intelligent approaches to optimizi
ng traffic flow\, to the precise detection of traffic jams and the short-t
erm forecasting of traffic for dynamic navigation aids.\nIncreasingly soph
isticated models have been therefore developed in the attempt of reproduci
ng the intrinsic complexity of traffic behavior (and that of its component
s). The challenge and anxiety of providing “certain” answers has howev
er diverted the attention from a basic consideration: "What makes modeling
and scientific inquiry in general so painful is uncertainty. Uncertainty
is not an accident of the scientific method\, but its substance" (Saltelli
et al.\, 2008).\nAs a matter of fact\, (commercially) available traffic s
imulation models are “fancy” tools of (almost) non-demonstrated utilit
y. In addition\, the scientific community is only marginally contributing
to identify correct ways to use what is available dealing in a proper mann
er with the underlying uncertainties of our tools. This is leading to the
paradoxical situation in which the outputs of a traffic simulation are lik
ely to be more affected by the assumptions made to define proper distribut
ions for the model inputs than from the model itself.\nThis deep quandary
stems from two main factors: i) traffic dynamics are the results of the co
mbination of several mutually correlated stochastic elements (drivers' beh
avior\, environmental conditions\, system performances\, etc.)\, and any o
bservation of the transportation system is just one of the possible occurr
ence generated by the same inputs.\nThese elements of intrinsic complexity
call for the definition of suitable frameworks for the management of mode
ling uncertainties. Objective of the present work is to show how Monte Car
lo methods can be fruitfully applied to make these frameworks operational.
\n\nhttps://indico.desy.de/indico/event/6196/contribution/3
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/3
END:VEVENT
BEGIN:VEVENT
SUMMARY:Iterated transport microsimulations
DTSTART;VALUE=DATE-TIME:20130220T080000Z
DTEND;VALUE=DATE-TIME:20130220T084000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-2@cern.ch
DESCRIPTION:Speakers: FLOETTEROED\, Gunnar (KTH Stockholm)\nUrban transpor
tation simulations typically iterate between a demand simulator (describin
g how humans plan their travel given the transportation network's state) a
nd a supply simulator (describing how the transportation network performs
given a certain travel behavior). If these iterations attain stationarity\
, the model is considered to be solved\, in that mutually consistent deman
d and supply are found. We discuss this type of model system from a MCMC p
erspective.\n\nhttps://indico.desy.de/indico/event/6196/contribution/2
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/2
END:VEVENT
BEGIN:VEVENT
SUMMARY:MC in Quantum Chemistry: Quantum Monte Carlo for Electronic Struct
ure
DTSTART;VALUE=DATE-TIME:20130220T102000Z
DTEND;VALUE=DATE-TIME:20130220T110000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-5@cern.ch
DESCRIPTION:Speakers: LESTER\, William A. (LBNL)\nBackground on the electr
onic structure of molecules will be presented leading to\nhow QMC for mole
cules arose. Versions of the approach will be summarized\nincluding the al
gorithm that has dominated computations to date. Aspects that\nimpact comp
utational efficiency will be described and selected applications\npresente
d to provide insight on the capability of the method.\n\nhttps://indico.de
sy.de/indico/event/6196/contribution/5
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/5
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monte Carlo methods of electron kinetics in laser excited solids
DTSTART;VALUE=DATE-TIME:20130220T094000Z
DTEND;VALUE=DATE-TIME:20130220T102000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-4@cern.ch
DESCRIPTION:Speakers: MEDVEDEV\, Nikita (DESY / CFEL)\nIn this talk I will
present a Monte Carlo based methods of modeling ultrafast electron kineti
cs in laser irradiated materials. I will briefly talk about the hierarchy
of the statistical methods used in modeling electron excitation and relaxa
tion processes in solids. It will be presented a standard Monte Carlo appr
oach for electron kinetics and transport\, most commonly used in studies o
f excited matter. It is based on the approach of individual particles and
independent events. Some more advanced techniques\, accounting for correla
ted events in electronic system\, will be discussed. A combination of Mont
e Carlo methods with other approaches and techniques will be conclude the
talk.\n\nhttps://indico.desy.de/indico/event/6196/contribution/4
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/4
END:VEVENT
BEGIN:VEVENT
SUMMARY:Monte Carlo generators based on GPUs
DTSTART;VALUE=DATE-TIME:20130219T130000Z
DTEND;VALUE=DATE-TIME:20130219T134000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-7@cern.ch
DESCRIPTION:Speakers: BARNAFÖLDI\, Gergely Gabor (Wigner Institut Budapes
t)\nMonte Carlo-based particle generators widely used in particle and dete
ctor simulations require enormous number of Central Processing Units (CPU)
and huge calculational time. Using a faster computing method might give a
unique capability for collaborations to speed up their data analysis or s
imulations. Recently\, programming frameworks of fast General Purpose Grap
hical Processing Units (GPGPU) reached the level to optimize some programm
ing sub-processes running on GPUs. This is a challenging task\, but might
result 10 − 100 times faster calculation – theoretically. \n\nAs a fir
st step on this way\, an inclusion of a GPU implemented pseudo-random gene
rators (PRNG) into a Monte Carlo-based particle generator (MC) is presente
d here. We performed the diehard-algorithms tests of PRNGs: a Mersenne –
Twister-based PRNG on CPU\, a SIMD-oriented Mersenne – Twister PRNG on
GPU\, and a linear-congruent MWC64X PRNG on GPU. Comparison of PRNGs were
done within the AliROOT MC generator framework for both by CPU and GPU run
s. Hadron production in proton-proton (pp) and lead-lead (PbPb) collisions
were generated\nusing GPU generated numbers.\n\nhttps://indico.desy.de/in
dico/event/6196/contribution/7
LOCATION:DESY Hamburg Lecture hall
URL:https://indico.desy.de/indico/event/6196/contribution/7
END:VEVENT
BEGIN:VEVENT
SUMMARY:MC methods in pricing and risk assessment
DTSTART;VALUE=DATE-TIME:20130220T110000Z
DTEND;VALUE=DATE-TIME:20130220T114500Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-6@cern.ch
DESCRIPTION:Speakers: MOLNAR-SASKA\, Gabor (Morgan-Stanley)\nMonte Carlo s
imulation is used extensively in financial mathematics since analytic solu
tion for complex pricing problems does not exist. First\, I will give some
introduction on financial products and then the basic concept of pricing
will be shown through a simple example. The advantages and challenges of M
onte Carlo method will be presented in terms of valuation and risk calcula
tions. A typical example of use of Monte Carlo methodology is the American
type option\, where the payout function of the product depends not only o
n the final value\, rather the whole trajectory of the underlying products
. In the presentation I will show some basic American type option problem\
, and show how we can avoid generating bushy Monte Carlo paths based on a
linear regression following the Longstaff-Schwartz methodology. Finally\,
I will present some possible extensions of this approach.\n\nhttps://indic
o.desy.de/indico/event/6196/contribution/6
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/6
END:VEVENT
BEGIN:VEVENT
SUMMARY:Current methods for lattice QCD
DTSTART;VALUE=DATE-TIME:20130219T134000Z
DTEND;VALUE=DATE-TIME:20130219T142000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-9@cern.ch
DESCRIPTION:Speakers: SCHÄFER\, Stefan (CERN)\nAlgorithms for lattice QCD
have become much faster during the last decade. This\nis mainly because o
f a better understanding of the system which we simulate. After a short in
troduction to the concepts and the general algorithmic approach\nof lattic
e QCD calculations\, the talk will highlight some of the ideas which\nhave
driven recent developments. A particular focus will be given to decomposi
tions of the physical system and their interplay with the algorithms used
for its simulation.\n\nhttps://indico.desy.de/indico/event/6196/contributi
on/9
LOCATION:DESY Hamburg Lecture hall
URL:https://indico.desy.de/indico/event/6196/contribution/9
END:VEVENT
BEGIN:VEVENT
SUMMARY:MCs in computational biology (protein folding and aggregation)
DTSTART;VALUE=DATE-TIME:20130220T130000Z
DTEND;VALUE=DATE-TIME:20130220T134000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-8@cern.ch
DESCRIPTION:Speakers: MOHANTY\, Sandipan (FZ Juelich)\nhttps://indico.desy
.de/indico/event/6196/contribution/8
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/8
END:VEVENT
BEGIN:VEVENT
SUMMARY:An introduction to particle filtering and sequential Monte Carlo m
ethods
DTSTART;VALUE=DATE-TIME:20130219T142000Z
DTEND;VALUE=DATE-TIME:20130219T150000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-11@cern.ch
DESCRIPTION:Speakers: KUENSCH\, Hans-Rudolph (ETHZ)\nhttps://indico.desy.d
e/indico/event/6196/contribution/11
LOCATION:DESY Hamburg Lecture hall
URL:https://indico.desy.de/indico/event/6196/contribution/11
END:VEVENT
BEGIN:VEVENT
SUMMARY:MC event generators in high-energy physics and astro-particle phys
ics
DTSTART;VALUE=DATE-TIME:20130220T142000Z
DTEND;VALUE=DATE-TIME:20130220T150000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-10@cern.ch
DESCRIPTION:Speakers: LÖNNBLAD\, Leif (Lund University)\nI will discuss t
he use of Monte Carlo methods in the simulation of\nhigh energy collisions
between elementary particles. Such simulations\,\nimplemented in programs
called Event Generators\, have developed into indispensable tools for lar
ge-scale particle physics experiments such as the LHC at CERN. In particul
ar\, I will concentrate on the modeling of so-called parton showers\, wher
e a large number of particles are produced and described in an approximate
way\, and its interplay with the generation of few-particle states where
more exact methods can be used.\n\nhttps://indico.desy.de/indico/event/619
6/contribution/10
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/10
END:VEVENT
BEGIN:VEVENT
SUMMARY:Plasma / fusion physics 2: EMC3 etc.
DTSTART;VALUE=DATE-TIME:20130221T084000Z
DTEND;VALUE=DATE-TIME:20130221T092000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-13@cern.ch
DESCRIPTION:Speakers: FENG\, Yuhe (IPP Greifswald)\nThe fluid model widely
used for understanding plasma transport in the edge of magnetic confineme
nt devices consists of a set of Braginskii’s equations. Mathematically\,
they fall in the category of second-order partial differential equations
of parabolic type. Numerical solutions of these equations for magnetically
confined plasmas in realistic 3D geometry encounter the difficulty of dea
ling with highly anisotropic transport in rather complex magnetic field st
ructures. Attempts of directly adopting conventional finite difference/ele
ment concepts can fail already when constructing a suitable computational
mesh. The extremely high transport anisotropy necessitates field-aligned c
oordinates for a clean separation of the small cross-field transport from
the much larger parallel one. In most of the practical 3D cases\, where th
e fields usually exhibit a certain degree of stochastic behavior\, it is v
ery difficult to find a rule for ordering the stochastic field lines into
a mesh acceptable by the conventional methods.\nThis paper presents a Lang
evin approach to this problem\, which is valid for arbitrarily complex mag
netic field structures. First of all\, the fluid equations are rearranged\
, not only for adapting them to the Langevin scheme but also for reasons o
f numerical stability of the strongly coupled\, non-linear system. A Monte
Carlo procedure for integrating the Langevin stochastic equations is form
ulated locally over a finite field line\, following a generalized Stratono
vich definition. The field-lines required for transport alignment are inte
rpolated from the pre-calculated ones stored on a 3D mesh by employing a r
eversible field line mapping technique. The toroidal component of the 3D m
esh carries the full magnetic field information\, while the choice of the
other two components is left free from magnetic fields. All these techniqu
es/methods are integrated into the EMC3 (Edge Monte Carlo 3D) code. As the
re is no limitation in magnetic structures\, the code has been widely appl
ied to magnetic confinement fusion devices\, including a wide variety of t
okamaks and stellarators. The paper gives a brief introduction to the EMC3
code and shows examples of some applications.\n\nhttps://indico.desy.de/i
ndico/event/6196/contribution/13
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/13
END:VEVENT
BEGIN:VEVENT
SUMMARY:Coupled CFD - Monte Carlo Transport Simulations for Magnetic Fusio
n Reactors
DTSTART;VALUE=DATE-TIME:20130221T080000Z
DTEND;VALUE=DATE-TIME:20130221T084000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-12@cern.ch
DESCRIPTION:Speakers: REITER\, Detlev (FZ Juelich)\nWith the first nuclear
fusion reactor (ITER\, Cadarche\, France) currently being under construct
ion\, Monte Carlo particle transport simulations (radiation\, atoms\, mole
cules) in the plasma near high heat flux wall components of the burning ch
amber are challenged\, because the interaction of these particles\nwith th
e fusion plasma largely determine and control the macroscopic plasma flow
and the response of exposed wall components of the reactor\, and vice ver
sa.\n\nLinear multi-species Monte Carlo transport algorithms are integrate
d\, iteratively\, into specialised solvers for magnetised plasma flow equa
tions (Navier Stokes type). Whereas each individual Monte Carlo part is fa
st and fully parallelised\, the combined highly non-linear problem (plasma
flow plus neutral particle transport) can be extremely CPU demanding\, de
pending on convergence requirements. The current status of the numerical s
cheme as well as sample applications from the ongoing ITER design computat
ions will be presented.\n\nhttps://indico.desy.de/indico/event/6196/contri
bution/12
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/12
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ensemble Kalman Methods for Inverse Problems
DTSTART;VALUE=DATE-TIME:20130220T153000Z
DTEND;VALUE=DATE-TIME:20130220T161000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-15@cern.ch
DESCRIPTION:Speakers: STUART\, Andrew (Warwick University)\nMany problems
in the physical sciences require the determination of an unknown\nfield fr
om a finite set of indirect measurements. Examples include oceanography\,
oil recovery\, water resource management and weather forecasting.\nThis ma
y be formulated as a least squares problem to match the model output to th
e data. I will demonstrate that ideas from the Ensemble Kalman Filter can
be adapted to solve such problems: by running multiple interacting copies
of the model\, and exposing their output to the (suitably randomized) data
\,\na derivative-free minimization tool is constructed. A key theoretical
result is described and this is used to motivate a series of experiments w
hich demonstrate the efficacy of the algorithm.\n\nIntroductory reading an
d references may be found in:\nhttp://arxiv.org/abs/1209.2736\nhttp://arxi
v.org/abs/1212.1779\nhttp://arxiv.org/abs/1107.4118\n\nhttps://indico.desy
.de/indico/event/6196/contribution/15
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/15
END:VEVENT
BEGIN:VEVENT
SUMMARY:State-of-the-art variance reduction methods for Monte Carlo radiat
ive transfer in atmospheric remote sensing
DTSTART;VALUE=DATE-TIME:20130221T102000Z
DTEND;VALUE=DATE-TIME:20130221T110000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-14@cern.ch
DESCRIPTION:Speakers: BURAS\, Robert (LMU Munich)\nRemote sensing in a clo
udy atmosphere is an inherently three-dimensional problem which is best so
lved using the Monte Carlo method as radiative transfer (RT) solver. Altho
ugh generally much slower than analytic one-dimensional RT solvers\, the r
esults obtained by Monte Carlo solvers can help quantify the errors made b
y the 1D approximation\, and can even be used to parameterize the 3D effec
ts in retrieval algorithms.\n\nHowever\, scattering of radiation on water
droplets and ice crystals is highly anisotropic\, which leads to extremely
slow convergence of the Monte Carlo results in the absence of variance re
duction techniques (VRT).\n\nI will present several VRTs which reduce the
computational time of the Monte Carlo RT solver by several orders of magni
tude\, thereby making the simulation of passive and active remote sensing
instruments feasible. Surprisingly\, for some 1D applications the accelera
ted Monte Carlo method yields to be faster than analytic RT solvers.\n\nht
tps://indico.desy.de/indico/event/6196/contribution/14
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/14
END:VEVENT
BEGIN:VEVENT
SUMMARY:Ultracold atom quantum simulators pass first key test
DTSTART;VALUE=DATE-TIME:20130221T132000Z
DTEND;VALUE=DATE-TIME:20130221T140000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-17@cern.ch
DESCRIPTION:Speakers: POLLET\, Lode (LMU Munich)\nUltracold atoms trapped
by laser beams make artificial materials which can be engineered with a re
markable level of control and tunability. They provide a unique toolbox fo
r emulating the prototypical models of condensed matter physics. Before th
ey can be trusted as quantum simulators\, they need to be checked and vali
dated against known results\, for which quantum Monte Carlo simulations ar
e ideally suited. I will give a brief overview of the state of the art of
quantum simulation for both ultracold bosonic and fermionic systems\, star
ting with time-of-flight interference patterns and single site resolution
techniques. I will proceed with a discussion on recent lattice modulation
experiments addressing the possible existence of a well-defined amplitude
mode in a strongly-interacting two-dimensional superfluid. This mode is a
direct analog of the Higgs boson in particle physics. I will conclude by g
iving a perspective on future directions in simulating strongly correlated
fermionic systems.\n\nhttps://indico.desy.de/indico/event/6196/contributi
on/17
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/17
END:VEVENT
BEGIN:VEVENT
SUMMARY:On Linearisation\, Importance Sampling and Adaptive Variance Reduc
tion Techniques Applied to Solutions of Fredholm Integral Equations in Atm
ospheric Optics
DTSTART;VALUE=DATE-TIME:20130221T120000Z
DTEND;VALUE=DATE-TIME:20130221T124000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-16@cern.ch
DESCRIPTION:Speakers: DEUTSCHMANN\, Tim ()\nThe Monte Carlo method in part
icle transport simulation stems from the context of nuclear reactor physic
s and was ported to atmospheric optics by G.I. Marchuk in the early 1980s.
In comparison with analytical methods\, the Monte Carlo method is concept
ually simple and is able to describe the underlying physics with arbitrary
accuracy.\n\nRadiation transport (RT) in atmospheric optics is described
by a Fredholm integral equation of the second kind. In applying the Monte
Carlo method to solutions of the RT equation (RTE)\, sequential importance
sampling in combination with the so called local estimate method establis
hed itself as the dominant technique. When calculation certain functionals
of the RTE the importance sampling technique is applied.\n\nI will show\,
how importance sampling is used in order to obtain 1st and 2nd derivative
s and exact corrections for simulating certain physical details such as th
e so called vector Ring effect. Furthermore I will give a small outlook ho
w the importance sampling weight fluctuations can be addressed by using a
variance reduction technique\, the so called weight window method recently
developed in nuclear physics.\n\nhttps://indico.desy.de/indico/event/6196
/contribution/16
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/16
END:VEVENT
BEGIN:VEVENT
SUMMARY:Uncertainty quantification and going beyond the independent-partic
le approximation
DTSTART;VALUE=DATE-TIME:20130221T124000Z
DTEND;VALUE=DATE-TIME:20130221T132000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-19@cern.ch
DESCRIPTION:Speakers: PIA\, Maria Grazia (INFN Genova)\nhttps://indico.des
y.de/indico/event/6196/contribution/19
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/19
END:VEVENT
BEGIN:VEVENT
SUMMARY:MC simulations and radiation transport in medical physics
DTSTART;VALUE=DATE-TIME:20130221T094000Z
DTEND;VALUE=DATE-TIME:20130221T102000Z
DTSTAMP;VALUE=DATE-TIME:20190916T160430Z
UID:indico-contribution-6196-18@cern.ch
DESCRIPTION:Speakers: POPPE\, Björn (U Oldenburg)\, Dr. CHOFOR\, Ndimofor
(Uni Oldenburg)\nWe shall describe typical applications of Monte Carlo (M
C) methods in the computation of radiation transport specifically in the d
omain of radiotherapy and associated applications to derive quantities of
interest such as the deposited energy per unit mass (otherwise known as th
e dose in Gray [J/Kg]). The suitability of MC in radiation physics is favo
ured by the stochastic nature of the underlying physical interaction mecha
nisms involved\, thereby requiring the iterative sampling of multiple part
icle type-dependent variables the most important of which are the particle
energy\, its position and direction of travel. The complexity of the prob
lem of radiation transport within matter renders analytical solutions to t
he Boltzmann transport equation very difficult\, owed to the assumptions r
equired to limit the transport problem to only a few independent variables
. The implementation of sampling by using random numbers\, alongside known
probability distribution functions of the basic interaction mechanisms wo
uld finally lead to a convergence of the result to the true value of the m
acroscopic quantity of interest under investigation\, if sampling is perfo
rmed over a significantly large number of events.\nWhile the simulation of
photon transport is less cumbersome\, electron transport is very delicate
especially at the boundaries between different media. Besides this\, with
regard to the multitude of catastrophic events involved in electron inter
actions\, the computation time to achieve low statistical uncertainties ma
y become very large. Typical techniques to circumvent lengthy tracking of
electron events shall be described. An example is the condensed history te
chnique entailing the grouping of a number of microscopic transport steps
into one fictitious interaction step. To improve efficiency of calculation
s without compromising the results\, typical variance reduction techniques
such as range rejection\, bremsstrahlung splitting and the Russian Roulet
te method shall be described. Furthermore\, energy thresholds are set for
both photons and electrons to values below which the particle is no longer
tracked and its energy locally deposited. The proper choice of the cut-of
f energy significantly affects the simulation time and thereby the overall
efficiency\, keeping in mind that a significant interaction event may occ
ur below this threshold\, depending on the problem under consideration. \n
The roles of the afore-mentioned techniques shall be highlighted in typica
l applications in medical radiation physics such as in the simulation of m
edical linear electron accelerators and dosimetric detector systems. Other
MC applications in treatment planning techniques shall also be described\
, alongside some examples of commercial MC-based systems.\n\nhttps://indic
o.desy.de/indico/event/6196/contribution/18
LOCATION:DESY Hamburg CFEL 1-3
URL:https://indico.desy.de/indico/event/6196/contribution/18
END:VEVENT
END:VCALENDAR