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A brief discussion about Gaseous Detectors How to boost simulations - - PowerPoint PPT Presentation

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Split, 2015 A brief discussion about Gaseous Detectors How to boost simulations Pedro Correia PhD Student University of Aveiro, Portugal

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A brief discussion about Gaseous Detectors

How to boost simulations

Pedro Correia PhD Student University of Aveiro, Portugal Split, 2015

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About Gaseous Detectors

  • Radiation/particle detectors. Applications for HEP,

Medical Physics, Homeland, etc…

  • Depending on applied voltage[1]

Measure deposited energy and/or count number of particles

  • MicroPatterned Gaseous Detectors (MPGD) -

CERN RD51 Collaboration. App: Compass-RICH (as photodetectors), ATLAS and CMS (muons)

  • MPGD examples: GEM[2]:

2

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How does a GEM work?

  • GEM - Gas Electron Multiplier
  • Its all about electric charge creation/movement

and interaction with the medium (gas and detector)

  • Excitations
  • Ionizations (avalanches)
  • Others (attachments)
  • Important parameter: Signal obtained (aka Gain).
  • Avalanche simulation of an incoming charged

particle

3

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How does a GEM work?

  • GEM - Gas Electron Multiplier
  • Its all about electric charge creation/movement

and interaction with the medium (gas and detector)

  • Excitations
  • Ionizations (avalanches)
  • Others (attachments)
  • Important parameter: Signal obtained (aka Gain).
  • Avalanche simulation of an incoming charged

particle

3

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Simulation toolkit: GARFIELD

  • Created at CERN in 1984 (Fortran version), now Garf++
  • “Toolkit for the detailed simulation of particle detectors

that use gas and semi-conductors as sensitive medium.” - Garfield website

  • http://garfieldpp.web.cern.ch/garfieldpp/
  • Tracking particles with Monte-Carlo techniques.

Create charged particles in gas Track every collision Simulate interactions (ex:ionizat.) Calculate properties (gain, drift velocity, etc)

(Monte-Carlo magic) Code example

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Boosting simulations

Create Electric field Map (ex: Ansys) Upload to Garfield Simulate up to 102 …106 independent primary electrons Gains up to 105 secondary particles

Days/weeks/months of simulations !

Repeat for a range of Electric Potentials (ex: 200-600V)

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Boosting simulations

Create Electric field Map (ex: Ansys) Upload to Garfield Simulate up to 102 …106 independent primary electrons Gains up to 105 secondary particles

Days/weeks/months of simulations !

Repeat for a range of Electric Potentials (ex: 200-600V)

5

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Boosting simulations

Create Electric field Map (ex: Ansys) Upload to Garfield Simulate up to 102 …106 independent primary electrons Gains up to 105 secondary particles

Days/weeks/months of simulations !

Repeat for a range of Electric Potentials (ex: 200-600V)

5

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Boosting simulations

Create Electric field Map (ex: Ansys) Upload to Garfield Simulate up to 102 …106 independent primary electrons Gains up to 105 secondary particles

Days/weeks/months of simulations !

Repeat for a range of Electric Potentials (ex: 200-600V) Parallelization of this simulations is now being developed (tools OpenMP, CUDA, …)

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Boosting simulations

Create Electric field Map (ex: Ansys) Upload to Garfield Simulate up to 102 …106 dependent primary electrons Gains up to 105 secondary particles

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What if the physical behavior changes with time? Ex: Avalanches are dependent of the previous…

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Boosting simulations

Create Electric field Map (ex: Ansys) Upload to Garfield Simulate up to 102 …106 dependent primary electrons Gains up to 105 secondary particles Iterative method to simulate time evolution (few seconds - minutes)

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What if the physical behavior changes with time? Ex: Avalanches are dependent of the previous…

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Final Message

  • Sometimes hard work in parallelization is not enough. Better and

reliable algorithms are crucial, specially if you are developing your

  • wn applications.

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References

  • 1. G. F. Knoll, Radiation Detection and Measurements, third edition. John Wiley & Sons, Inc., 3rd ed.,

1999.

  • 2. CERN Courier, Dec 7, 2009: The continuing rise of micropattern detectors, http://cerncourier.com/

cws/article/cern/41011

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Backups

  • Charging-up effect: Dynamic accumulation of

charges in the insulator changes the local electric field, thus the response of the detector

  • ver the time

Azmoun, B.et al"A Study of Gain Stability and Charging Effects in GEM Foils," Nuclear Science Symposium Conference Record, 2006. IEEE , vol.6, no., pp. 3847,3851, Oct. 29 2006-Nov. 1 2006 doi: 10.1109/NSSMIC.2006.353830

9 Illustration of charing-up on a GEM Electric field intensity evolution over the time

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Backups

  • Charging-up effect: Dynamic accumulation of

charges in the insulator changes the local electric field, thus the response of the detector

  • ver the time

Azmoun, B.et al"A Study of Gain Stability and Charging Effects in GEM Foils," Nuclear Science Symposium Conference Record, 2006. IEEE , vol.6, no., pp. 3847,3851, Oct. 29 2006-Nov. 1 2006 doi: 10.1109/NSSMIC.2006.353830

9 Illustration of charing-up on a GEM Electric field intensity evolution over the time

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Backups

  • Charging-up effect: Dynamic accumulation of

charges in the insulator changes the local electric field, thus the response of the detector

  • ver the time

Azmoun, B.et al"A Study of Gain Stability and Charging Effects in GEM Foils," Nuclear Science Symposium Conference Record, 2006. IEEE , vol.6, no., pp. 3847,3851, Oct. 29 2006-Nov. 1 2006 doi: 10.1109/NSSMIC.2006.353830

9 Illustration of charing-up on a GEM Electric field intensity evolution over the time