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Software week, E. Lamanna
Annecy - June 2, 1998
Bogus - Babar Object-Oriented Geant4-based Unified Simulation
DCH in framework-based Simulation
(C. Dallapiccola, E. Lamanna, C. Perri, M. Posocco, F. Safai )
- Packages involved in the drift chamber simulation:
-
- BgsDchSim
- Build the geometry for three different models
- Produces hits from tracement only for "layer" model
- DchBgsModules
- Fast tracking using the Billoir filter
- Output: reco-like track objects
Description of the packages
BgsDchSim
-
- Retrieved from the dbio file dch.db used for bbsim.
- Available models:
- "fast-cylinder" : simple cylindrical fast simulation, the
example as implemented by Torre.
- "cylinder": the chamber is made of cylindrical volumes
made of different materials.
-
-
- - DCHA main volume containing:
- DCHG Sensitive
gas volume
- DCHO Outer
wall
- DCHI Inner
wall
- DCRP Rear
plate
- DCFP Front
plate
- "layer" : includes the "cylinder" model to define the
external materials and volumes of the chamber.
The volume is subdivided in 40 sub-volumes, one for
each layer ( DL01, DL02 ...... DL40 ) delimited from
the sense wires surfaces.
- hit structure:
-
- The G4Navigator tracks the particles in the DCH.
- The particle crosses the layer surfaces and stores it the hit
some information computed in the intersection point:
-
- .
- the information stored in the hit are:
-
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| Number |
Information |
Name |
Type |
| 1 |
x at intersection |
_xPosition |
G4double |
| 2 |
y at intersection |
_yPosition |
G4double |
| 3 |
z at intersection |
_zPosition |
G4double |
| 4 |
px at intersection |
_px |
G4double |
| 5 |
py at intersection |
_py |
G4double |
| 6 |
pz at intersection |
_pz |
G4double |
| 7 |
current layer |
_layer |
G4int |
| 8 |
current cell |
_cell |
G4int |
| 9 |
particle ID |
_particlePDG |
G4int |
| 10 |
track ID |
_track |
G4int |
| 11 |
path |
_path |
G4doublr |
| 12 |
energy loss |
_energyLoss |
G4double |
| 13 |
# of crossed rad length |
_crossedRadLeng |
G4double |
| 14 |
distance to sense wire |
_wireDistance |
G4double |
| 15 |
intrinsic resolution |
_resolution |
G4double |
DchBgsModules
-
- Downstream module which access to fast Dch hits stored in the event.
- Fast tracking procedure using the Billoir method to transport matrix
elements from one hit to the next, until reaching the first one (Aslund like).
- Output of the fit (referenced to a single point):
-
- error matrix-
- track parameters
Current implementation takes into account only DCH materials;
the position of the first hit in the hit list is considered as the reference point.
- Used TrkMiniMaker (in TrkFitter package) to construct the TrkRecoTrk objects without detailed information which only the full simulation and real data has (time information, etc.).
- The helix parameters are available at one point: the production vertex of the track or PCA.
-
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Information stored in TrkRecoTrk
|
Type
|
Name
|
Function
|
Description
|
| double |
d0 |
theHelix.d0() |
x-y distance of beginning of track (PCA or production vertex)
relative to the origin |
| double |
phi0 |
theHelix.phi0() |
phi direction (azimuthal angle) of track at PCA |
| double |
curvature |
theHelix.omega() |
1/radius of curvature |
| double |
z0 |
theHelix.z0() |
z position at PCA |
| double |
tanDip |
theHelix.tanDip() |
tangent of the dip angle of the track = cot(theta) |
| HepMatrix |
covMatrix |
theHelix.covariance() |
error matrix |
Man Power and Milestones
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- Update in BgsDchSim including Hype volumes.
(E. Lamanna, C. Perri, F. Safai - Roma)
- Tuning of hits smearing to obtain comparable results to the bbsim full chain.
(E. Lamanna, C. Perri - Roma)
- Inclusion of SVT hits in DchBgsModules.
(C. Dallapiccola - Maryland)
- Parametrization of dE/dx making DchPid Reco objects.
(M. Posocco - Padova)
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