physics validation meeting w. pokorski / cern
DESCRIPTION
Physics validation meeting W. Pokorski / CERN. Simulation Application for the LHC b Experiment. Physics validation. comparison to the test-beam data validation of Rayleigh scattering, Cherenkov radiation, photoelectric effect, energy loss in the Silicon for RICH detectors - PowerPoint PPT PresentationTRANSCRIPT
16/04/2003 Simulation Application for the LHCb Experiment
Physics validation meeting
W. Pokorski / CERN
Simulation Application for the LHCb Experiment
16/04/2003 Simulation Application for the LHCb Experiment
Physics validation
comparison to the test-beam datavalidation of Rayleigh scattering, Cherenkov radiation, photoelectric effect, energy loss in the Silicon for RICH detectors
studies of different hadronic physics models in hadronic calorimeter simulations
comparison to the Geant 3 simulationoccupancies, momentum distributions, time of flight, energy deposition distributions, etc
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16/04/2003 Simulation Application for the LHCb Experiment
• To identify charged particles in the momentum range 1-150 GeV/c.• Two detectors: RICH1, RICH2.
RICH1: Aerogel 210 GeV/c C4F10 < 70 GeV/c RICH2: CF4 <150 GeV/c.
• Photo Detectors: Baseline solution- HybridPhotodiodes (HPD).
• RICH test beam presented: To test the performance of the Aerogel radiator.
Momentum range
S. Easo
RICH detectors in LHCb
16/04/2003 Simulation Application for the LHCb Experiment
TestTest beam Set-up at CERNTestTest beam Set-up at CERN
Beam from CERN-PS: πˉ and p/π in the range 6 – 10 GeV/c (Δp/p = 1%)
S. Easo
16/04/2003 Simulation Application for the LHCb Experiment
Simulation of the Testbeam Setup.
Mirror Rad. of Curvature=1185 mm.Four Pad Hpds are used.
Mirror
Hpd
Aerogel
Filter
Vessel
S. Easo
16/04/2003 Simulation Application for the LHCb Experiment
Red lines: Charged particleGreen lines : Photons.
Transmission in Aerogel, Cherenkov radiation, Rayleigh scattering, etc, simulated properly
S. Easo
A Typical event in the Testbeam
16/04/2003 Simulation Application for the LHCb Experiment
Thickness No filter Filter D263
θc σθ θc σθ
4 cm 250.0 5.4248.7 4.0
247.1 5.0246.8 3.1
8 cm 246.8 5.8245.0 3.9
245.4 4.8243.7 3.0
DataMC
Aerogel fromNovosibirsk
• Results per single photoelectronsingle photoelectron in (mrad):
DataMC
Cherenkov Angle reconstruction
Components of σθ
in mrad for the case with filter.
Pixel size : 1.3Chromatic: 2.5Emission Pt: 1.1
Beam divergence: 0.7
Misalignment: ~ 2.2 (not included in σθ MC )
MC resolutionWithoutMisalignment
16/04/2003 Simulation Application for the LHCb Experiment
•Standard Geant4 processes not applicable in this case (tabularized quantum efficiency data available from the manufacturer)
•A Special class created to generate the photoelectrons, which is derived from a GEANT4 base class.
•This process uses the quantum efficiency data and the results of Fountain focussing tests. Electron Energy: High Voltage applied.
Direction: From Fountain focussing.
• The quantum efficiency data includes the loss of photons by reflection at the Hpd quartz window surface.
S. Easo
Photoelectric Effect at the HPD
16/04/2003 Simulation Application for the LHCb Experiment
• Implemented using a special process class since the standard Geant4 procedure too complex for this purpose
• the only important point: photoelectrons loose all their energy in the Si
• The backscattering causes a loss of efficiency in creating hits Parameterized efficiency = 1.0 - B* N/S
where N = threshold cut in terms of width of the pedestal = 4 S= Signal to noise ratio=10 B= backscattering probability=0.18.
S. Easo
Hit Creation in the Si Detector
16/04/2003 Simulation Application for the LHCb Experiment
RICH1 with SingleParticleGun
Pion with 7 GeV/c. Cherenkov PhotonsIn Aerogel and C4F10.
RICH1 Event
Rayleigh scatteringSwitched off forIllustration.
S. Easo
16/04/2003 Simulation Application for the LHCb Experiment
RICH Simulation Plans.
• At least one test beam expected in October 2003 with gas radiators and new versions of the Photodetectors.
• Another testbeam with new versions of Aerogel also possible in October.
• All these will be simulated using GEANT4.
• In addition, we are expecting the LHCb-RICH simulation within the GAUSS framework to be in production by the end of 2003.
S.Easo, RAL,14-04-2003
16/04/2003 Simulation Application for the LHCb Experiment
• HCAL is a sampling device made out of steel as absorber and scintillating tiles are active material.
• The scintillating tiles run parallel to the beam axis.
• It will provide data for the LHCb hadron trigger.
• Testbeam studies of the response to particles incident at various angles is studied
• comparison to simulation I. Belyaev +A. Berdiouguine et al.
HCAL Test beam
16/04/2003 Simulation Application for the LHCb Experiment
Response to 50 GeV/c Pions
• Testbeam (1) Data , GEANT3 (MICAP +FLUKA).• HCAL TDR.
•Testbeam (2) Data, GEANT4.
Histogram : Real DataDots: Simulation
I. Belyaev +A. Berdiouguine et al.
Energy Response in HCAL
16/04/2003 Simulation Application for the LHCb Experiment
Energy Resolution of HCAL
• Testbeam Data, GEANT3• GEANT3 with GEISHA, FLUKA,MICAP
• Testbeam Data , GEANT4• G4+GEISHA agrees with G3+GEISHA.• Need help to understand and use G4 with QGS+CHIPS
• Data G4 (QGS+CHIPS) G4(GEISHA)
Data and G3
Data and G4
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I. Belyaev +A. Berdiouguine et al.
16/04/2003 Simulation Application for the LHCb Experiment
Calorimeters test-beam
ALL LHCb calorimeters Spd/Prs/Ecal/HCal will have test beam periods this summer between the middle of June and end of August
very detailed and realistic Xml description of all our complex modules calorimeters in Gauss (the LHCb simulation application) - no plans to perform a stand alone G4 simulation for our calorimeters
if needed, addition (simplified) geometry will be implemented to be used within Gauss
full simulation of test beam setups will be performed with Geant4 (Gauss) and the data will compared
I. Belyaev
16/04/2003 Simulation Application for the LHCb Experiment
Vertex Locator physics validation (1/2)
Geant3Geant4
Number of hits per event Energy deposition in the silicon (eV)
Geant3
Geant4
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16/04/2003 Simulation Application for the LHCb Experiment
Vertex Locator physics validation (2/2)
Geant3
Geant4
Geant3
Geant4
Time of Flight (ns) Particle energy (GeV)
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16/04/2003 Simulation Application for the LHCb Experiment
Outer Tracker physics validation (1/2)
Geant3Geant4
XY distributionNumber of hits per event
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16/04/2003 Simulation Application for the LHCb Experiment
Outer Tracker physics validation (2/2)
Time Of Flight (ns)Momentum distribution (GeV)
Geant3Geant4
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16/04/2003 Simulation Application for the LHCb Experiment 16
Summary
LHCb puts no further effort on developing G3 based application, all of it has been moved to G4 based one
we can run GEANT4 simulation with all the subdetectors included (complete LHCb detector geometry), realistic Pythia events and Geant4 proposed physics list
we are testing/validating subdetector specific code and physics processes
we are planning large test productions starting from the summer
definite move from the old Geant3 simulation to the new Geant4 based one, early next year
conclusion: we are serious about Geant4 and we are very interested in the physics validation