The interim status of the 1998/9 ECFA/DESY simulation programme is described. The fast simulation program, SIMDET, and the full GEANT simulation, BRAHMS, are shown to be working and being used in physics and detector studies for a future linear collider. An alternative fast simulation program, SGV, is also available. A selection of physics and detector study results are shown and an overview given of which tools to use for which purpose

Blair, G A

CERN Document Server

OPEN-99-18513/09/99'&$%Detector SimulationGrahame A. BlairRoyal Holloway, Univ. of Londonemail: g.blair@rhbnc.ac.ukOverview: Overview of available simulation tools Status of Geant3 BRAHMS Tracking results with BRAHMS (K.Monig) Occupancy studies (M.Battaglia) Other studies planned or in progress Fast simulator tools: SIMDET,SGV Event Output Code Management Agenda for Parallel Session. Summary.ECFA/DESY Workshop, Frascati, November 8-10, 1998'&$%Overview of Simulation tools:A variety of complementary simulation tools are available. Detaileddetector and physics studies are already underway using these tools.Links to the code and documentation can be found at:http://rsl3eth2.cern.ch/~pohl/sim_home.html SIMDET v2 authors S Schreiber, M Pohl et al. is a FASTsimulation for general physics studies. It applies an energy owalgorithm obtained using the full simulation BRAHMS. Thisprogram is an updated version of the one used in the previousECFA/DESY study. SGL author M Berggren is an alternative FAST simulation forgeneral physics studies. It is based on code developed originallyfor the DELPHI experiment. P.Steen has been modifying SIMDET to produce a a MEDIUMspeed program using the GFLASH parametrisation developedoriginally for the H1 experiment; eectively a fast version ofGEANT3. Aimed towards detailed studies of granularity, jetmass studies etc. BRAHMS authors T.Behnke,G.Blair,K.Monig,M.Pohl et al. is aFULL simulation using GEANT3. Ideal for detailed calorimeterand tracking studies. Track reconstruction and (rudimentary)clustering are present. No detailed pattern recognition. 2'&$%Fast Simulation:SIMDET:SIMDET v2.0 is now available on the Web. It contains Gaussiansmearing for resolution eects, energy ow and will be matched toBRAHMS for more detailed calorimeter eects. A common outputformat is planned. You can nd the code at:http://www.ifh.de/~pohl/sim_guide.htmlSIMDET v3 is almost ready for release. It will include: Shower shape of CDR detector, as determined from BRAHMS. Parametrisation and implementation in fast monte-carlo. Cluster nder (from L3) Commonly-agreed output structure Energy FlowThe Energy Flow alogorithm will be of use in any monte-carlo. Plansexist to incorporate it into BRAHMS.SGV: This is an alternative fast simulator which can be used as across-check on the SIMDET output, as well as in its own right. Seetalk by Andre Sopczak for examples of its use. M.B. has generatedbackground events of WW,ZZ, qq, We, Zee and tt with PYTHIA(in total 16 000 000 events corresponding to 500 pb 1, without anyproblems ). These events are being used in physics studies. You cannd the code at:http://home.cern.ch/~berggren/lc/sgv_lc.html 3'&$%The CDR Detector as coded in BRAHMS: Beampipe (Depends on Vertex Detector Option) Vertex Detector (CCD or APS) geometries plus basic hits Intermediate Tracker material only Silicon Intermediate Tracker not yet included Main tracker (TPC) material, with basic hits Presampler material plus basic hits E-M Calorimeter (Lead-Scintillator Shashlik), material plus hits Hadron Calorimeter (Copper-Scintillator Shashlik), material plushits Tail Catcher, muon id material plus very basic hits Luminosity Calorimeter material plus basic hits Instrumented Mask material only Forward Tracker material plus hits Forward Muon Tracker not yet included Muon Trackers not yet included 4'&$%End View of the Detector as coded inBRAHMS: 3T Magnetic Field 50 Calorimeter towers around phi in barrel region. 5'&$%Side View of the Detector as coded inBRAHMS: Projective Calorimeter towers Calorimeter within coil. 6'&$%Inner Detector as coded in BRAHMS: Vertical scale enlarged 4 times APS VXD option shown Side view - FTD disks appear as lines. LCAL visible within mask. 7'&$%Calorimeter Towers as coded in BRAHMS: Projective Cells ECAL: 8 8 cells in transverse segmentation HCAL: 4 4 cells in transverse segmentation ECAL,HCAL each have 3 longitudinal segments. ECAL: Lead-Scintillator HCAL: Copper-Scintillator Electronics: included as material at both ends of tower. 8'&$%A tracking study using BRAHMS:Klaus Monig has been using his code within BRAHMS to study thetracking performance as specied in the CDR.1. hits as supplied by BRAHMS2. no allowances for multiple scattering3. no pattern recognition.400 GeV single Muons7o<  < 173o050100150200250300350400450-5 -4 -3 -2 -1 0 1 2 3 4 5  75.94    /    72Constant   385.1Mean  -.1004E-01Sigma   1.008Figure 1: pull distribution for1p 9'&$%Plotting the relative momentum error as a function of polar angle for400 GeV muons:00.050.10.150.20.250.30.3510 20 30 40 50 60 70 80 90θ∆p/pp=400GeVFigure 2: Relative momentum error vs angle (CDR Detector) 10'&$%and the resolution (m) on r and z impact parameter:02.557.51012.51517.52022.510 20 30 40 50 60 70 80 90rφθ∆ip/µmzpixel-VDFigure 3: resolution on r and z impact parameter(CDR Detector)In summary: a very useful tracking study is in progress using the fullsimulation. See KM's talk for further details. 11'&$%Occupancy Studies and other studies:Marco Battaglia and Kenneth Osterberg have been using GEANT tostudy:1. The occupancies in the vtx tracker for the 1 cm beam-piperadius2. The occupancies in the ITC.3. Some proposals of geometryThey have implemented their code in BRAHMS and this will beincluded in the next release. For details, see the talk by M.B in thedetector parallel sessions.Calorimetry: Volker Korbel and Sergey Kotelnikov are usingBRAHMS to investigate calorimeter performance in the full detector.One aim is to study how resolution and tails are aected by theamount of calorimetry inside the coil.Study outline: Simulating single pions at normal incidence. full geant calorimeter simulation using `porridge'scintillator/absorber material. 12'&$%In addition they intend to: measure visible energy in ECAL and HCAL , all cells. measure visible energy in coil. measure visible energy in tail catcher (not fully reconstructed butsmeared with resolution130%pE). Calculate resolution and tails from 10,20,50,100,200,400 GeVparticles or jets. Study eect of reducing number of  inside coil.Requirement: Needs many events (pions) of xed energy. Such anevent sample could be of use to many studies; so : we should thinkof coordinating this centrally.Forward Region: Albert de Roeck and B.Surrow are planning to look into the thesimulation program in the vicinity of the beamline: Mask, lumidetector, magnets... M.Piccolo is also interested in this region. Some of this is already included in Brahms, but needs to bestudied by experts.Again, this will need many events which will be of used to the entireworkshop. : We should think of coordinating this centrally. 13'&$%Event Output:A group of interested people, coordinated by M. Pohl, havediscussed a possible event output format for the workshop. This hasbeen written up and put on the web page:http://www.ifh.de/~pohl/sim_guide.htmlA summary of the content of this web page follows: List of generator particles (straight copy from input):Number of particle recordsParticle record:status code, particle code, mother(s)px, py, pz, E, Mx, y, z, t of origin vertex List of reconstructed energy ow objects:Number of energy ow recordsEnergy ow record:status code, object type, mother(s)best estimate: px, py, pz, E, Mtracker: p, theta, phi, DCAxy, DCAz, covarianceEcal cluster: E, theta, phi, CemHcal cluster: E, theta, phi, CmipMuon system: E, theta, phi, CpunchThe intention is to use such a common output format for bothSIMDET and BRAHMS, to allow a direct comparison. 14'&$%Code Management:This has become a priority.Harald Vogt is setting up a central afs area for the workshop. It willbe in:/afs/ifh.de/group/lc Harald will act as code manager We will continue to use PATCHY/CMZ. Source code will go into a src subdirectory. Documentation will go into a doc subdirectory. An example directory will be created which contains examples ofhow to use the programs.A web-based system TUOVI is also being investigated on a trialbasis.http://pia.desy.de:8135/TWDM/cgi/twdmproto.pm 15'&$%OO Plans and Activities:This is gaining some momentum Harald Vogt and Martin Pohl are collaborating on OO plans tocreate an interface between Fortran based simulation programsfor the LC and OO graphic tools now on the market . In their case this is hepvis ! OpenInventor ! OpenGL ! X11 Ralf Gerhards has been involved with the installing GEANT 4 atDESY. He has been looking at taking the geometry rz le ofBRAHMS and employing a conversion to put it into GEANT 4. It is becoming time to think about longer-term reconstructionissues in the context of OO. There is clearly a good opportunity to collaborate with ourUS/Japanese colleagues here. This is on the Agenda for the parallel session. 16'&$%Simulation Group Parallel meetingAGENDAAll talks 20 mins (approx).1. G.Blair: Status of BRAHMS2. J.Schreiber: Status of SIMDET3. M.Berggren: Status of SGV (?)4. R.Dubois: US simulation5. H.Vogt: European OO plans and activities6. R. Gerhards: Geant 4 and trigger issues.7. M.Battaglia: VXD simulation.8. V.Korbel: Calorimeter simulation.9. M.Piccolo: Instrumented mask10. D.Schulte: Comments on beampipe/forward geometry.11. Discussion: What changes do we want with respect to what wehave, especially: what changes to the baseline CDR detector? Whatpattern recognition/reconstruction tools do we want to study? 17'&$%Summary: \what you should use" BRAHMS, SIMDET, SGV are up and running for theECFA/DESY study. If you are starting a physics analysis, the recommendation is tostart with SIMDET and if you would like a check: use SGV. If you are using SGV and you would like a check: use SIMDET. If you want to do detailed detector studies including materialeects: use BRAHMS. Detailed physics studies as well as detector design studies are nowpossible and some are already started. Code management is now being implemented Common backround data sets are still on the agenda. GEANT4 is being considered for the medium term. BRAHMS, SIMDET, SGV are up and running for theECFA/DESY study.Final Comment: The simulation tools will not change much on thetimescale of Sitges unless there is a signicant input of eort fromthe users (or future users). If you don't like it, change it! 18

Detector Simulation

Abstract

Similar works

Full text

Available Versions

CERN Document Server