Transcript University of Birmingham LPF Status and Optical Readout

GEO 600 Simulation Group
Andreas Freise
ILIAS WG1 Meeting
CERN (29-Mar-07)
Simulation Work in GEO
 GEO in this sense is not GEO 600 but the people in
GEO related research groups
 Simulation work consists of:
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Theoretical understanding of the physics
Coding the physics (algorithm development)
Coding, maintaining, documenting software
Using simulations to produce modelled data
(commissioning, detector design, table-tops, …
 Understand more about the modelled experiment from the
modelled data
A. Freise
ILIAS WG1 - CERN - 29/03/2007
Slide 2
The GEO Collaboration
Interferometer
Prototypes
Data Analysis
Suspension
Development
Squeezed
Light R+D
A. Freise
Laser
Development
Detector
Commissioning
Design of
future GW
Detectors
LISA
Instrument
Development
ILIAS WG1 - CERN - 29/03/2007
New Materials
R+D
GW Source
Modelling
Interferometry
R+D
Laser
Development
Slide 3
The GEO Collaboration
 Relatively small collaboration
 Entangled with several large projects
 Subgroups develop automatically
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Possible Remedy:
Create topic based groups
Members are contact points to the various activities
Strengthen and develop a GEO 'identity'
Test in progress: the simulation group
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ILIAS WG1 - CERN - 29/03/2007
Slide 4
The GEO Simulation Group
 Members (as of 22.01.07): Andreas Freise, Stefan Hild,
Kentaro Somiya, Sabina Huttner, Roland Schilling, Paul
Cochrane, Jan Harms, Gudrun Diederichs, Simon
Chelkowski, Antonio Perreca, Jonathan Hallam, Oliver
Bock
 Meetings : 16.01.07 (Hannover), 13.03.07 (Hannover)
 Resources: Website (Wiki), mailing list, svn repositories
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Slide 5
The GeoSim Website
 www.sr.bham.ac.uk/dokuwiki/doku.php?id=geosim:home
 A public Wiki with restricted write access
 Hosts
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A. Freise
Meeting dates
Talks of past meetings
References to GEO experiments
Links to simulation programs and software tools
Summaries of current or open tasks
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ILIAS WG1 - CERN - 29/03/2007
Slide 6
Code from the good old days
 OptoCad
 2D CAD program that traces Gaussian beams through an optical
layout (GEO, VIRGO, LISA)
 WaveProp
 FFT propagtion code (somewhat like DarkF)
(GEO)
 LISO
 Numerical electronic circuit simulator, specialised tool for
building electronic filters
 Finesse
 Numerical Interferometer Simulation, uses Hermite-Gauss
modes in the frequency domain (GEO, LIGO, VIRGO, TAMA)
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Slide 7
OptoCad: Alignement tolerancing of the LISA Pathfinder
optical bench (Gudrun Diederichs)
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Slide 8
OptoCad: Alignement tolerancing for LISA Pathfinder
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OptoCad and Finesse
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Slide 10
Simple TwoMirror Cavity
Finesse output
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Slide 11
Finesse: Current Activities
 GEO commissioning
 Using Finesse to 'debug' GEO by matching simulations to
experimental results
 Maintain a configuration file which is in sync with GEO reality
 Quantum noise extension
 For the design and commissioning of future detectors we need a
proper description of quantum noise
 Implementation of quantum noise is 50% complete
 Adding new features
 Phasemaps, Matlab interface, New detector types
 Testing and code documentation
 Unit tests, Code cleaning, Doxygen documentation
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Slide 12
GEO Commissioning
A. Freise
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Slide 13
GEO Commissioning
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Slide 14
Shotnoise
 New algorithm to compute shotnoise for N carrier/
modulation fields and M demodulations (paper
submitted)
New Finesse command
'qshot'
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Slide 15
The missing factor of two
The modelled shotnoise did not match the measured
sensitivity. Often we were apparently missing a factor
of two or sqrt(2). Do we understand why? YES
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Slide 16
Adding Phasemaps to Finesse
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Slide 17
Finesse with Phasemaps
 Analyse the effects
of mirror surface
defects
 Study aperture effects
(clipping)
 Simulate flat beams
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Slide 18
The Finesse Code
 Code is being re-organised and cleaned (Paul
Cochrane)
 It is now hosted in a svn repository and is currenlty
changed regularly by three developers
 Extensive code documentation via Doxygen
 Manual (also extensive) is supplemented by in-depth
explanations of GEO input files
 Started to introduce unit tests of single functions:
about 50% of the code base (43000 lines) is tested
nightly
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Slide 19
New Activities
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LISA BBO Simulator (Jan Harms)
Thermal effects via FFT simulations (Jerome Degallaix)
Non-linear cavity simulator (Nico Latzka)
Simulating mirrors as elastic deformable objects
(Yanbei Chen)
 AdLIGO, Optickle (Kentaro Somiya)
 ….
A. Freise
ILIAS WG1 - CERN - 29/03/2007
Slide 20
Conclusion
 New GEO Simulation Group has been started
 So far it works very well and has initiated or vitalised
several activities related to GEO 600 and/or simulations
 The group aims at forming a communication hub inside
the GEO collaboration
 This will also benefit the links between GEO and other
projects
 Link of the GeoSim meetings with LSC meetings
planned
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end
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Slide 22
GEO Commissioning
 GEO optical layout with OptoCad
 Stores the location of the optics (lengths, angles)
 Is used to understand spurious beams, etc.
 Finesse input file for GEO
 Computes control signals and transfer functions
 Used to compute noise couplings and the detector sensitivity
 WaveProp for thermal lensing
 Is used only for special task which require a time-domain or FFT
approch
 LISA is a mission to detect and observe gravitational
waves
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Slide 23
The GEO Collaboration
 LISA is a mission to detect and observe gravitational
waves
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The GEO Collaboration
 LISA is a mission to detect and observe gravitational
waves
A. Freise
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Slide 25
The GEO Collaboration
 LISA is a mission to detect and observe gravitational
waves
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Slide 26