- Poisson CCD22 solver by Craig Lage - - PowerPoint PPT Presentation

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poisson ccd22 solver by craig lage
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- Poisson CCD22 solver by Craig Lage - - PowerPoint PPT Presentation

Dec 23, 2023 474 likes •647 views

Documenting and validating imSim sensor models Sergey Karpov Institute of Physics, Czech Academy of Sciences Sensor Characterization, Analysis and Simulation Aug 14, 2018 #lsst2018 #lsst2018 LSST Project and Community

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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Documenting and validating imSim sensor models



 Sergey Karpov
 Institute of Physics, Czech Academy of Sciences
 


Sensor Characterization, Analysis and Simulation
 Aug 14, 2018

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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  • Poisson CCD22 solver by Craig Lage

https://github.com/craiglagegit/Poisson_CCD22

  • Low-level simulation of electric fields and charges in silicon
  • Most detailed and advanced CCD simulation
  • Extremely slow
  • GalSim

https://github.com/GalSim-developers/GalSim

  • Modular astro image simulation toolkit
  • Simplified / approximate low-level sensor effects
  • imSim

https://github.com/LSSTDESC/imSim

  • LSST-specific configs and scripts on top of GalSim

imSim

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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Documenting imSim models

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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  • Electron Diffusion
  • GalSim: Silicon.cpp + sensor.py
  • random displacement with amplitude

dependent on Vbb, temperature, conversion depth

  • Tree Rings
  • GalSim: Silicon.cpp / imSim: tree_rings.py
  • Static distortion map with randomized

radial profile

  • Brighter-Fatter
  • GalSim: Silicon.cpp
  • Dynamically adjusted distortion

imSim sensor model

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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  • Model
  • Diffusion + electric field drift
  • Effective reduction of electron mass

(~0.27) following Green et al (1990)

  • Front voltage adjustment based on

simulations (~1 um above bottom)

  • Scaling with (wavelength + angle

dependent) conversion depth

Electron Diffusion

σ = SensorThickness ⋅ 1 − ConversionDepth SensorThickness ⋅ 2kT q(Vfront − Vbb) ⋅ MobilityFactor

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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  • Validation
  • Fe55 data acquired at BNL
  • NGMIX fitting of well isolated hits
  • Model fit for surface conversion value

Electron Diffusion

https://github.com/LSSTDESC/imSim/wiki/diffusion_validation

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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Electron Diffusion

Model is mostly consistent with experimental data

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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  • Doping variations during wafer growth
  • Voltage (and conversion depth) dependent

electron drift

  • Seen in both E2V and ITL sensors,

amplitudes similar

  • Photon Displacement
  • Shape distortion
  • Pattern in flats

Tree Rings

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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  • Radial displacement map based on random

Fourier components

  • 15 components: Gaussian(60, 10) pix
  • 5 frequencies: Gaussian(35, 10) pix
  • Qualitatively based on profiles measured in

BNL (Hye-Yun Park)

  • Pre-loaded at sensor construction
  • Scales with conversion depth
  • Does not scale with bias voltage

Tree Rings: imSim model

60% "good" 40% "bad"

δr = (∑ sin(ωir + ϕi)/ωi − ∑ cos(ωjr + ϕj)/ωj) ⋅ (A + Br4) δS = (∑ cos(ωir + ϕi) + ∑ sin(ωjr + ϕj)) ⋅ (A + Br4)

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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Tree Rings Validation

BNL data imSim

https://github.com/LSSTDESC/imSim/wiki/tree_ring_validation

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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Tree Rings Validation: periodograms

BNL data imSim

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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Tree Rings Validation: frequency structure

BNL data imSim

Real tree rings have faster oscillations at larger radii

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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Tree Rings Validation: amplitudes

BNL data imSim BNL data imSim

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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  • Exact simulation of electron

repulsion for single pixel using Craig' Poisson solver

  • Vertices displacements imported

into GalSim and co-added for all pixels

  • linear scaling with pixel charge
  • Pixels are assigned based on

displaced edge vertices

  • non-linear conversion depth scaling
  • Iteratively repeated while collecting

the image

Brighter-Fatter model

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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  • Inter-pixel correlations in simulated flats
  • Direct spot size dependence on flux

Brighter-Fatter validation

Poisson GalSim

https://github.com/LSSTDESC/imSim/wiki/brighter_fatter_validation

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LSST Project and Community Workshop 2018 • Tucson • August 13 - 17

#lsst2018

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  • Improve Wiki documentation
  • reflect all implementation details
  • demo notebooks for effects visualization / characterization
  • general overview pages for different subsystems
  • Validation and model adjustments
  • Diffusion: acquire homogeneous dataset for a single sensor
  • Tree Rings: modify the model to include more realistic frequency and

radial structure

  • Brighter-Fatter: simulation vs experiment?

Plans