Simulation Project Leaders Meeting 12-September-2006 ==== Attendees John Apostolakis (JA), Alfredo Ferrari (AF), John Harvey (JH), Witek Pokorski (WP), Alberto Ribon (AR), Pere Mato (PM), Rob Veenhof (RV), Gabriele Cosmo (GC). Excused: Paolo Bartalini (PB). --------------------------------------------------------------------- ==== Minutes - Paolo Bartalini resigned from the coordination of the Generator Services sub-project. Also in the name of the Simulation Leaders, I wish to thank him for the great and professional work he has done by leading the Generator Services sub-project over the last 3 years. - I would like to welcome Witold Pokorski (CERN PH/SFT) as the new leader of the Generator Services sub-project. Witek will dedicate a good portion of his time to the new job and will share it with the responsibilities he is already taking in leading the Simulation Framework sub-project; this will also enable him to follow and consolidate the activities of the two sub-projects in a coherent view. Thanks to Witek for accepting the position and to John Harvey and Pere Mato for their efforts and help in identifying the new leader. - The meeting has been also focused on the preparation for the Application Area Internal Review at CERN, 18-20th September: http://agenda.cern.ch/fullAgenda.php?ida=a063165 The proposed agenda agenda for the Simulation Project presentations: Tuesday 19th, 11:30 - Simulation Project Overview, G.Cosmo - 10+5 - Generator Services, A.Ribon & W.Pokorski - 20+5 - Physics Validation, A.Ribon - 15+5 Tuesday 19th, 14:00 - Geant4 status & plans, J.Apostolakis - 15+5 - Fluka status & plans, A.Ferrari - 15+5 - Simulation Framework & GDML, W.Pokorski - 15+5 Presentations will focus on a summary of the activity done in the past 18 months (since April 2005) and planned activities. Documentation page for the Simulation Project: http://lcgapp.cern.ch/project/simu/simurev200609.html --------------------------------------------------------------------- ==== Simulation physics validation - Alberto - Meetings: o A Workshop on validation and verification of Geant4 hadronic physics was held in July. o An Hadronic Shower Workshop was held at Fermilab on September 6-8th; presentations can be found from the web site: http://conferences.fnal.gov/hss06 - Progress has been made to correct test-beam data from experiments in order to allow MC engines to compare independently the results; corrections of the order of 10% for digitisation, noise, ... to the data, using a technique also applied by experiments for cross-sections calculations. A presentation on the subject is to be scheduled for one of the next validation meetings; first results were presented by Tancredi-Carli at the ATLAS Calibration Workshop in Barcelona last. - 3rd simple benchmark: o The work for the analysis has been completed and plots produced. The results look reasonable for both Geant4 and Fluka; they have been discussed already with the Geant4 experts, further discussion to be done with Fluka experts. Preliminary results will be presented at the review. - CMS HCAL analysis: the analysis has been reiterated using release 7.1 of Geant4 and the results show no significant improvement for the longitudinal shower-shapes (while for ATLAS a slight improvement was observed from release 7.1). The analysis will be repeated also with the latest available release 8.1.p01. - ATLAS TileCal analysis: the discrepancy of 5% when shooting electrons or muons seems to be reduced in a simple benchmark setup. By using a simplified setup shooting at 90 degrees, similar results are obtained, confirming that a geometrical effect applies in the case of the full geometry setup induced by the physics. Everything is now ready to start the production. Some time will be required to teach people to use the framework also for other studies. --------------------------------------------------------------------- ==== Generator services - Paolo - No report. --------------------------------------------------------------------- ==== Fluka - Alfredo - New release of Fluka: Fluka-2006.3. Among the new features also cited in the minutes of the previous meeting are: o generation of primary ionisation events (request by ALICE); o optional possibility to use the new high-energy generator; o first implementation of photon-muon pair prodution (mu-pair). The new version will be released on September 12th; will be made available on the web along with updated documentation. It is also agreed it will be installed in the LCG AFS area. - Some consensus in Fluka Coordination committee to open the source also to other scientific institutions. - Also a new version of FLUGG with bug fixes and updates to recent version of Geant4 is to be released and its web page to be updated. - Meetings: o invited talk at the 11th International Conference on Nuclear Reaction Mechanisms, Varenna, June 2006; o invited talk at the Committee on Space Research, 36th COSPAR Scientific Assembly, Bejing, July 2006; o invited talk at the XIV International Symposium on Very High Energy Cosmic Ray Interactions, ISVHECRI2006, Weihai, August 2006; o invited talk and hands-on session at the Workshop on Use of Monte Carlo Techniques for Design and Analysis of Radiation Detectors, Coimbra, September 2006; o invited talk at PSI in October; o invited talk in Catania (Italy) in October, for radiotherapy. - Work in progress with the CNGS neutrino beam project. - Migration of CMS radiation studies to the official FLUKA software: a project is being setup with the help of LCG/SFT group. --------------------------------------------------------------------- ==== Simulation framework - Witek - FLUGG: o Validation work and checks have been going on to verify that no bias is introduced by the tool and the GDML extensions in the measurements. A couple of bugs in FLUGG were also fixed. o Cross-checks of the geometry is done by shooting geantinos and comparing the intersections with boundaries, or by computing the radiation-length with the materials defined in the setup. o It is felt important that FLUGG is released regularly with up-to-date web-page, and installed regularly in the LCG AFS area together with the GDML extensions developed for it. - GDML: o The paper submitted to IEEE-TNS has been accepted and will be soon published. o Lot of progress made in the past months, thanks also to the students assigned to the project (Daniele Kruse and Ben Lloyd) summers students. Two releases of GDML in the past month, now 2.8.0. o Added stand-alone converter of CAD STEP files from STEViewer to GDML. o Added new solids to the schema: tessellated solids, tetrahedron and twisted solids; all solids in Geant4 are now supported. o Added support for optical properties and surfaces. o Introduced support for modular GDML files, which works for both writing and reading. A GDML file can also be split in several files to separate for example the material definition from the geometrical setup. o Added support for loops and matrices. o Binding to GDML is now added in Root; performance has been improved; reader and writer are now integrated. It supports all solids provided in Root. Now working to implement the reader (currently written in Python), in C++ using the Root XML parser. o Extensions for allowing attachment of user data is being studied to define a recipy; external contribution is expected in this area. - Meetings: o July EuroPython conference: presented talk on Reflex/PyRoot for Python binding in Geant4. --------------------------------------------------------------------- ==== Geant4 - John - A patch (8.1.p01) was released at the end of July with fixes mainly in the hadron elastic processes; also included fixes to physics lists for use of precision neutrons. - A workshop on Geant4 Verification and Validation Workshop was held at CERN July 17-19. A majority of the presentations were on hadronic physics, covering the status of the validation of hadronic physics models. Updates from test beam comparisons and EM validation were also presented. - Workshop on Hadronic Showers held at Fermilab: o Key aspects for hadronic showering were identified: exact pi0 simulation; neutrons in final hadronic energy deposition; high energy protons simulation. o There have been cross comparisons of the codes for several test-cases; Geant4 results were prepared for 3 of the seven benchmarks. Geant4 performance showed a number of strengths (e.g. EM interactions above 1 GeV) and weaknesses (e.g. pi- production in NA49). The remaining benchmarks and other calorimeter benchmarks are to be exercised in the near future. o A workshop summary will be planned for a group meeting in early October. o Next Workshop will be held in Europe, potentially at CERN, in 18-24 months time. - In the energy range between 5 and 20 GeV, including the published HARP measurements, there is a deficit of applicable physics models in Geant4. An action is to be undertaken to investigate potential alternatives, including other QGS/DPM implementations. - The Geant4 Workshop will be held in Lisbon, October 9th-14th. --------------------------------------------------------------------- ==== Garfield - Rob - Completed study on the reliability of transport parameters in the presence of a magnetic field (to be presented by Kalliopi Mermigka). - Clarified issue of the new cross section components for CO2 and water, which have lead to significant improvement in the simulations done by Atlas (MDT). - Minor studies for Babar ongoing (related to calibration). - BOINC production well in progress, move to GRID foreseen, mainly with a view to obtaining calibration in the presence of a magnetic field, but also for a systematic scan of the impact of impurities - BEM (boundary element methods): This is an alternative to field calculations using analytic methods and using finite element methods (FEM). Analytic methods are the preferred choice if applicable. For several years now, FEM is the usual method to solve other cases - this choice is motivated by the broad availability of commercial FEM programs: the method is popular in engineering. Unfortunately, FEM is not well suited for electrostatics: the electric field computed with FEM is, by construction, not continuous across element boundaries; the fields are approximated by polynomials which do not satisfy the Maxwell equation; the method is best suited for structures with a small range in scales, which is not the case for typical detectors (drift volumes of several meters, combined with anode wires of 10s of microns diameter). A group in India is currently working on a BEM program specifically for detectors. BEM differs from FEM in many key aspects: the problem domain is not broken up in elements but charges are placed outside the domain until the boundary conditions are satisfied. The field is approximated using potential functions that do satisfy the Maxwell equations. As a result, the method doesn't suffer from the FEM drawbacks. It has been used very little in detector studies sofar, mainly due to the limited availability of commercial BEM programs. Using their program, it is planned to investigate the practical applicability of the BEM method to the Alice TPC. - K0s / lambda thesis in NA60 (Atila Neves) nearing completion - Development plan for the next few weeks: MC diffusion in convergent fields, in the presence of a B field. This is related to the earlier topic of non-Gaussian diffusion which is now becoming relevant for the LHC experiments. --------------------------------------------------------------------- ==== AOB Next meeting scheduled for October 24th.