WG4 Modelling of Physics Processes and Software Tools

Contact Conveners: You can contact the conveners by composing their email addresses as
  • Ozkan Sahin
  • Rob Veenhof
  • Piet Verwilligen

Main Research Topics

Disclaimer: here below you can find a selected list of papers and talks. This list is by definition incomplete and items are not ordered neither chronologically neither according to importance.

Integration, Maintenance & Development of Simulation Tools

Data Link Name Description
RD51 Dec 2018 Slides neBEM source files for Garfield++ Supratik Mukhopadhyay (Saha) neBEM (Fortran) as field mapper for Garfield++. Class that reads neBEM fieldmap in Garfield++
RD51 Jun 2016 Slides Bodnia Comsol interface for Garfield++



Data Link Name Description
RD51 Dec 2018 Slides Steve Biagi Towards inclusion of HFO1234ze in Magboltz
RD51 Jun 2018 Slides Steve Biagi Improvements in Magboltz & Degrad: NO2
RD51 Dec 2017 Slides Steve Biagi Improvements in H2O
RD51 Dec 2017 Slides Steve Biagi Improvements in H2O

Essential papers:

  • H. Skullerud, The stochastic computer simulation of ion motion in a gas subjected to a constant electric field,Journal of Physics D: Applied Physics 1 (11) (1968) 1567.
  • S. Biagi, Accurate solution of the boltzmann transport equation, Nuclear Instruments and Methods in PhysicsResearch Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 273 (2-3) (1988) 533535.[23] S. Biagi, A multiterm boltzmann analysis of drift velocity, diffusion, gain and magnetic-field effects in argon-methane-water-vapour mixtures, Nuclear Instruments and Methods in Physics Research Section A: Accelerators,Spectrometers, Detectors and Associated Equipment 283 (3) (1989) 716722.[24]
  • G. Fraser, E. Mathieson, Monte carlo calculation of electron transport coefficients in counting gas mixtures:I. argon-methane mixtures, Nuclear Instruments and Methods in Physics Research Section A: Accelerators,Spectrometers, Detectors and Associated Equipment 247 (3) (1986) 544565.
  • S. Biagi, Monte carlo simulation of electron drift and diffusion in counting gases under the influence of electric andmagnetic fields, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers,Detectors and Associated Equipment 421 (1-2) (1999) 234240.

Code CERN page
Other links old MIT page

Conversion of Magboltz code from Fortran into Cython to allow for developments by other people than the main author of Magboltz. Maintained by Ben Jones & Bashar Atoum (Arlington).

Talks RD-51 Collab Meeting Oct-2019 DUNE High Pressure TPC meeting Oct-2019
Papers Arxiv 1910.06983 2019  
Code github  
Examples See talks  

Particle Swarm simulations

RD51 Jun 2016 Slides (Belgrado) Swarm Simulations for MPGD
RD51 Jun 2016 Slides (Belgrado) Swarm simulations for RPC

LXCAT Cross-sections database

Review Paper LXCat: an Open-Access, Web-Based Platform for Data Needed for Modeling Low Temperature Plasmas, L.C.Pitchford, Plasma Process. Polym. 2017, 14, 1600098

Time Dependent weighting field to simulate Signal formation in Resistive Detectors

Data Link Name Description
RD50 Jun 2019 Slides H.Schindler  
RD50 Jun 2019 Slides Paper W.Riegler Extension of Ramo-Shockley theorem for signals in detectors that contain non-linear materials of arbitrary permittivity and finite conductivity (volume resistivity) as well as a static space-charge
RD51 Feb 2020 Slides W.Riegler (CERN) Inclusion of electrode resistivity for signal calculation in MPGDs: a road towards implementation in Garfield
RD51 Oct 2020 Slides D.Janssens (VUB) Signals in Resistive MPGDs: an introduction
RD51 Feb 2021 Slides D.Janssens (VUB) An update on the modeling of signal formation in detectors with resistive elements

Data Link Name Description Code Integrated?
RD51 Feb 2021 Slides M.Slater (Birmingham) Garfield++ parallellization (GPU) NO
RD51 Jun 2020 Slides H.Schindler (CERN) interface for neBEM in Garfield++ YES
RD51 Jun 2018 Slides O.Bouhali (Texas A&M Qatar) Speeding up Garfield in complex geometries with many cells: 20x time increase by optimization of "FindElement" github YES
RD51 Jun 2018 Slides D.Pfeiffer (CERN/ESS) Garfield-Geant: Introduction, Physics, Implementation Garfield++ website YES
RD51 Feb 2018 Slides D.Pfeiffer (CERN/ESS) Status of Garfield-Geant Integration  
RD51 Sep 2017 Slides D.Pfeiffer (CERN/ESS) Interfacing Geant4 and Garfield Physics evaluation  

Simulation of MPGD detectors (Examples)

Data Link Name Description Paper/Proceeding
RD51 Oct 2019 Slides Djunes Janssens (VUB) Surface Potential, Hole Asymm, Sec Ele Emission, Transport Alg.  
RD51 Oct 2019 Slides Henning Keller (Aachen) Effect of hole shape on GEM Gain: Measurements vs Simulation [][JINST 2020]]
RD51 Jun 2016 Slides Karadzhinova Effect of hole shape on GEM gain  

Data Link Name Description
RD51 Dec 2018 SlidesPaper Flux Model (2003) Ratza (Bonn) Model Eres, IBF & gain of Alice TPC QGEMs using electron and ion collection and extraction efficiencies, where these efficiencies are calculated based on a flux model (see 2nd link)
RD51 Dec 2018 Slides Ottnad (Bonn) Optimization of Alice TPC QGEM Stack. Using simulations to reduce transfer fields
RD51 Oct 2019 Slides Paper Lavezzi / Farinelli (INFN TO) Parametrized simulation for Triple-GEMs in BES-III (BEPC); Gain tuned with factor 6.8 for Triple-GEMs
RD51 Oct 2019 Slides Brio/Cisbani (INFN CT/RM) Multi-step approach for Triple-GEM of Super-BigBite (JLAB); GMSH+Elmer shows 50% higher gain than ANSYS.
RD51 Feb 2020 Slides Movies Bal/Dubey (VECC) Simulating Triple-GEMs (3/2/2/2) with gmhs & elmer up to 500V per single-GEM, avalanche limited to 1000, multiple-peak structure in arriving times observed for primary ionization from 1 GeV muon (as expected). No data-mc confrontation for gain
RD51 Dec 2017 Slides Supratik (SINP) Simulation of picosec detector with neBEM&Garfield (fortran)


RD51 Jun 2020 Slides Paper R. Ward (Birmingham) Simulation of SPC with framework that performs tracking with Geant, passes <2keV electrons to Heed for primary ionization and then passes secondary electrons to microscopic tracking in Garfield++
RD51 Jun 2018 Slides L.De Keukeleere (KUL) Example of Garfield-Geant interface: simulation of multi-wire drift chamber

Simulation of charging-up & Space Charge

Data Link Name Description
RD51 Feb 2021 arXiv submission Slides Supratik Mukhopadhyay Fast simulation of avalanche and streamer in GEM detector using hydrodynamic approach
RD51 Oct 2020 slides Antonello Pellecchia Simulation of Space-charge in MPGDs with Elmer
RD51 Feb 2019 Slides Deb Shankar (Wurzburg) Simulation of discharges in Micromegas
RD51 Dec 2017 Slides Filippo Resnati (CERN) Modelling of dynamic and transient behaviours of gaseous detectors

Development of Ouroboros package (SW that calculates field (BEM) and performs microscopic tracking using LXCAT cross sections on heavy GPU servers)


Data Link Name Description Code
RD51 Dec 2018 Slides Hauer (Bonn) Precise measurements + Iterative Simulation Procedure to simulate Charging Up  
RD51 Jun 2019 Slides Pitt (Weismann/Aveiro) _Extension of Aveiro toolkit to add experimentally determined charging down (due to charge diffusion in FR4) _ github
RD51 Mar 2016 Slides Correia (Aveiro) Improved Iterative method (Superposition) + first trials for parallellization  


Date link Title Authors Code DOI Arxiv Description
April 2012 Link Simulation of the dielectric charging-up effect in a GEM detector M.Alfonsi et al. (CERN) NIM A 671 11 6-9 10.1016/j.nima.2011.12.059   Implementation for the first time of Iterations between FEM and Garfield to simulate charging up. Effect of charging up on electron transparency of single GEM
Jul 2014 Link A dynamic method for charging-up calculations:the case of GEM P.M.M. Correia et al. (Aveiro) JINST 9 P07025 10.1088/1748-0221/9/07/P07025 Ansys model with sliced hole. Iterative procedure for depositing charges on the slices and updating Electric Field. Qualitative reproduction of temporal behaviour of gain in single GEM, however cannot reproduce measured gain
Aug 2016 Link THGEM gain calculations using Garfield++: Solvingdiscrepancies between simulation and experimentaldata P.M.M. Correia et al. (Aveiro)   10.1088/1748-0221/11/08/P08018 Use of Penning transfer fundamental to reproduce Gain of THGEM
Jan 2018 Link Simulation of gain stability of THGEM gas-avalanche particle detectors P.M.M. Correia et al. (Aveiro/Weizmann) JINST 13 P01015 10.1088/1748-0221/13/01/P01015   Dedicated toolkit that integrates Garfield++. Faster solution w.r.t. JINST 9 P07025 with pre-calculated field maps, avoiding such to run FEM programs in the iteration
Mar 2018 Link Measurements of charging up processes in THGEM-based particle detectors M.Pitt et al. (Weizmann/Aveiro) JINST 13 P03009 10.1088/1748-0221/13/03/P03009   Application of Iterative method developed in JINST 13 P01015 to THGEM. Mixed paper discussing more measurements than simulation
Jun 2020 Link Measurements of the charging-up effect in Gas Electron Multipliers F.Hauer et al. (Bonn) j.nima.2020.164205   Very precise measurements of charging up in standard single gem

Data Link Name Description
RD51 Jun 2018 Slides A.Mathis (TUM) Understanding discharge formation in GEMs by modelling how much charge enters in a single hole and applying Raether's criterium

Other Items

RD51 Sep 2018 Slides Ishiura (Kobe) Negative Ion Gas (SF6) for High Pressure TPC
RD51 Jun 2018 Slides shiura (Kobe) Negative Ion Gas (SF6) for High Pressure TPC
RD51 Dec 2018 Slides Cortez (Coimbra) Measurement of Ion mobility in Ne-CF4 mixtures
RD51 Jun 2018 Slides Cortez (Coimbra) Measurement of Ion mobility in Ar-CF4-iC4H10 mixtures
RD51 Feb 2018 Slides Cortez (Coimbra) Measurement of Ion mobility in Ar-CF4-C2H6 mixtures
RD51 Feb 2017 Slides Ion mobility in Xe-CO2 mixtures
RD51 Sep 2017 Slides Veenhof (CERN) Ion tails in ATLAS TRT

Lectures & Training

Open Issues

We are looking for interested and motivated people that can improve the simulation tools. There are several items where we have ideas on how to improve the simulation codes, but where we lack manpower:
  • Discrepancy in Gain between data and simulation in GEM-structures: Simulation underestimates with a factor 2(? check) the gain in a single GEM-foil, and this propagates also to multi-GEM structures. More information can be found [[][here (insert link]]. A possible candidate for this under-estimation of the gain is the fact that the Electric field changes substantially within the volume of a mesh element. Garfield(++) however takes the central value and asks Magboltz to calculate the Mean Free Path before collision. If the electric field varies strongly, the mean free path is over-estimated and the multiplication factor (e-/cm) is under-estimated. A possible solution continue
  • Reading COMSOL fieldmap in Garfield++: Garfield++ has only a function to read a COMSOL fieldmap made of first-order elements (tetraeders with 4 nodes), while more accurate results could be obtained with second order elements (tetraeders with 10 nodes), because these second order elements allow a more precise meshing of volumes with convex or concave structures. Instead the fortran version of Garfield is able to read 2nd order element fieldmaps.
  • Update Magboltz in Garfield++: Garfield++ is interfaced with Magboltz 10.1 (%REDcheck), while the latest version is 11.6 (Nov 2018).
  • Update HEED in Garfield++: the version of HEED actually implemented in Garfield++ does not simulate the Coulomb scattering when passing through a material. Furthermore the specific primary ionisation is calculated based upon the initial kinetic energy of the particle and is not updated if the particle looses energy inside the detector. While this works fine for a Minimum Ionizing Particle passing through a thin absorber, this does not work for layered detectors where some material needs to be perforated or for the simulation of sub-relativistic electrons that loose energy at much higher rate than a MIP and might get stopped in the detector.
  • ...

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Topic revision: r24 - 2022-04-12 - PietVerwilligen
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