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Mitglied der Helmholtz-Gemeinschaft GISAS Data Analysis with BornAgain Céline Durniak, Marina Ganeva, Gennady Pospelov, Walter Van Herck , Joachim Wuttke May 13, 2014
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GISAS Data Analysis with BornAgain Céline Durniak, Marina Ganeva, Gennady Pospelov, Walter Van Herck, Joachim Wuttke May 13, 2014
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§ MLZ Scientific Computing Group § A user story § Future development and support
May 24, 2014 ACA Meeting Albuquerque 2
Outline
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§ MLZ Scientific Computing Group § A user story § Future development and support
May 24, 2014 ACA Meeting Albuquerque 3
Outline
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• MLZ: joint group (TUM, FZJ, HZG, HZB) • FRM-II neutron source in Garching (Munich)
May 24, 2014 ACA Meeting Albuquerque 4
MLZ
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• Group was founded in July 2011 • Currently 6 members:
May 24, 2014 ACA Meeting Albuquerque 5
Scientific Computing Group
• Responsibilities: • Support instruments for questions at the interface of physics and IT • Enhance understanding of experimental results by providing simulations
• First big project: BornAgain
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• Start community project for data analysis and simulation • Grazing incidence small angle scattering as a first task
• different user experiments (neutron and x-rays) • more generally structured than existing software • IsGISAXS as reference software
• Apply acquired experience to other experiments
May 24, 2014 ACA Meeting Albuquerque 6
BornAgain project
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§ MLZ Scientific Computing Group § A user story § Future development and support
May 24, 2014 ACA Meeting Albuquerque 7
Outline
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§ Choice of experiment § Theory of DWBA simulations § Exploring the data (simulations and other techniques) § Fitting the data
May 24, 2014 ACA Meeting Albuquerque 8
From sample to quantitative understanding
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May 24, 2014 ACA Meeting Albuquerque 9
Max’ challenge
What are the dimensions of these nanopar0cles?
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(off-specular) reflectivity
May 24, 2014 ACA Meeting Albuquerque 10
Choice of experiment
GISAS
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(off-specular) reflectivity
May 24, 2014 ACA Meeting Albuquerque 11
Choice of experiment
GISAS
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(off-specular) reflectivity
May 24, 2014 ACA Meeting Albuquerque 12
Choice of experiment
GISAS
ki
kfq
qz
qy
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Other choices to make: • X-rays or neutrons • Wavelength • Required intensity • Polarization • Which instrument/facility
May 24, 2014 ACA Meeting Albuquerque 13
Choice of experiment
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May 24, 2014 ACA Meeting Albuquerque 14
GISAXS data
Remarks: Gaussian noise Rough estimate of particle sizes
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May 24, 2014 ACA Meeting Albuquerque 15
GISAXS data
From the workshop page: … Presently, a major bottleneck preventing GISAXS from reaching its full potential persists in the availability of data analysis and modeling resources for interpreting the data. The problem arises mainly because reflections in GISAXS add to the complexity of the analysis and simulation. A common approach adopted for treating the reflection is the distorted wave Born approximation (DWBA). Several DWBA-based software packages have been developed. …
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May 24, 2014 ACA Meeting Albuquerque 16
DWBA
Perturbed Hamiltonian: H = H0 + V
Born Approxima0on Distorted Wave Born Approxima0on
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May 24, 2014 ACA Meeting Albuquerque 17
DWBA
Scattering amplitude:
Born Approxima0on Distorted Wave Born Approxima0on
Ψ in Ψout
A ki,k f( ) ≈ Ψout V r( ) Ψ in
∝ d3r V (r)∫ exp i ki − k f( ) ⋅ r%& '(
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May 24, 2014 ACA Meeting Albuquerque 18
DWBA: interference between particles The expectation value of the di↵erential cross–section is:
⌧d�
d⌦(q)
�=
X
↵
p↵ |F↵(q)|2 +⇢VV
X
↵,�
p↵p�F↵(q)F⇤� (q)
⇥ZZ
Vd3R↵d
3R�G↵,� (R↵, R�) exp [iq · (R↵ �R�)]
= Id(q) +⌦F↵(q)S↵�(q)F
⇤� (q)
↵↵�
with:
Id(q) ⌘D|F↵(q)|2
E
↵� |hF↵(q)i↵|
2
S↵�(q) ⌘ 1 + ⇢V
Z
Vd3R↵�G↵� (R↵�) exp [iq ·R↵� ]
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May 24, 2014 ACA Meeting Albuquerque 19
DWBA: interference between particles Decoupling Approximation:
⌧d�
d⌦(q)
�= Id(q) + |hF↵(q)i↵|
2 ⇥ S(q)
Local Monodisperse Approximation:
⌧d�
d⌦(q)
�=
D|F↵(q)|2 S↵(q)
E
↵
Size-Spacing Correlation Approximation:
D(↵0,↵1) = D0 + [�R(↵0) +�R(↵1)]
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May 24, 2014 ACA Meeting Albuquerque 20
BornAgain features
As a start, functionality based on successful IsGISAXS software • Reproduce its functionality • Also use DWBA • Extend it (less restricted sample geometry, support for
neutrons, usability) Other requirements: • Open source • Multi platform (Linux, Mac OS, Windows) • Performance
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May 24, 2014 ACA Meeting Albuquerque 21
BornAgain features
§ Multilayer § Interface roughness § Multiple nanoparticles
(shapes, densities) § Interference functions § Nanoparticles assemblies
(mesocrystals) § Polarized neutron
scattering
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May 24, 2014 ACA Meeting Albuquerque 22
Exploring the data
GSL Boost
BornAgain: core library Samples and algorithms
BornAgain: FiAng library
User program/script: C++ or Python
External graphics (e.g. matplotlib)
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May 24, 2014 ACA Meeting Albuquerque 23
Fitting the data
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May 24, 2014 ACA Meeting Albuquerque 24
Fitting the data
I would smile now, if I wasn’t a picture…
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§ MLZ Scientific Computing Group § A user story § Future development and support
May 24, 2014 ACA Meeting Albuquerque 25
Outline
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• GUI: beta release in September 2014
May 24, 2014 ACA Meeting Albuquerque 26
Future development
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• GUI: beta release in September 2014 • Polarized GISANS: interface roughness, magnetic domains • Performance: GPU, cluster • More complex sample structures
May 24, 2014 ACA Meeting Albuquerque 27
Future development
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Issue and bug tracker Agile development model: • Short release cycles • Code quality • Code stability:
functional and unit tests
May 24, 2014 ACA Meeting Albuquerque 28
Support
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For further information or questions: http://www.bornagainproject.org Or email me at: [email protected]
May 24, 2014 ACA Meeting Albuquerque 29
Thank you !
