Simulations for SuperBelle
Peter Križan
University of Ljubljana and J. Stefan Institute
SuperB computing mini workshop, Dec 7, 2007
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Super-Belle Detector
Barrel-KLM (RPC)
TOP
ECL
RICH
CDC
EndCap-KLM
(sintillator)
SVD
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Belle upgrade – side view
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Simulations for upgraded detector
Two levels of sophistication:
• Full Geant4 MC of the upgraded detector
• Fast simulator for feasibility studies
Full Geant4 simulation:
• Realistic response of components
• Investigation of the interactions between the components
(e.g. PID devices in front of the calorimeter)
• Investigation of backgrounds
• Determination of parameters for the fast MC
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Full MC
g4superb
kernel
io, table
svd
cdc
top
rich
ecl
klm
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Full MC
g4superb
kernel
io, table
DetectorConstruction
construct sub-detectors
svd
PhysicsList
cdc
define physics and particles
top
PrimaryGeneratorAction
rich
generator interface
ecl
EventAction
klm
control digitization timing & output
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Full MC
g4superb
kernel
io, table
svd
cdc
InputManager
• Interface for generator file/DB
• EvtGen in standard Belle
generator format, provision for
support of others
top
OutputManager
rich
• File/DB-output interface class
• Standard Belle analysis format;
provision for support of others
ecl
klm
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Full MC
g4superb
kernel
io, table
svd
cdc
top
• Materials for objects
• Solids (shapes) for objects
• Detection of particles /
interactions (SensitiveDetector)
• How to make hits
• How to digitize
• Limitations (step-length etc.)
rich
ecl
klm
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Examples: SVD
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Aerogel RICH (forward
region)
•Aerogel radiator (hexagons)
•Photon detectors
added the support
structures, approx.
electronics
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
EventDisplay
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
EventDisplay
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Full MC and reco status
• Removed geometry overlaps within and between subdetectors
• Backgrounds: being added
• Reconstruction for most subdetectors ready
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Example: forward PID device
Simulation
•Particles are tracked through the aerogel RICH
•Cherenkov photons are generated in the aerogel and the
quartz window of the photon detector
•Cherenkov photons are Rayleigh scattered in the aerogel
•Photons are tracked through the quartz window of the
photon detector
•And registered as hits if they are “detected”
•Background hits (determined from random events and
beam test data) are added
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Example: forward PID device
Reconstruction
•Get track parameters from the reconstructed track list
•For hit photon detector pads calculate expected number of
hits for a given track and ID hypothesis
•Construct the likelihood functions for 5 hypotheses
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Fast MC
Input (and tuning) from
• MC for present Belle and data, with extrapolations to
new design – different material distribution, sensors
(most components) resolutions, efficiencies,
backgrounds
• Stand-alone full MC and test beam data for new
components (e.g., barrel and forward PID)
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Fast MC: some details
• photons
– resolutions (energy, angle):
• function of energy + correction for barrel-endcap gaps
• Crystall ball energy resolution
• Gaussian angular resolution
– efficiency
• Simple function of E + correction for gaps
• charged tracks
– resolutions (helix parameters)
• Helix parameter errros are given in mesh of (|p|,theta)
and read in from .dat files
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Fast MC: forward PID device
• Take the smeared track parameters
• Calculate resolution in Cherenkov angle for single
photons, expected number of detected photons
• Get background level
• Generate Cherenkov angle distribution
• Calculate likelhoods for indvidual hypotheses
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana
Fast MC status
• Fast MC is ready, has already been used for some
analyses
• Some discrepancies have been observed, and are
being debugged
Dec 7, 2007
Mini WS, SLAC
Peter Križan, Ljubljana