How to open session:
use static method AliRunLoader::Open("galice.root","AlicE","update")
How to get total number of events in galice.root:
- use AliRun::GetEventsPerRun()
+ use AliRun::GetEventsPerRun() or AliRunLoader::GetNumberOfEvents()
How to avoid using gAlice:
detector->GetLoader()->GetRunLoader()->GetAliRun() returns gAlice global pointer.
How to retrieve pointer to alice run loader:
gMC->IsTrackAlive()
gMC->IsTrackStop()
gMC->IsTrackDisappeared()
-How is sdigit produced from hit:
- Responsible method is AliRICH::Hits2SDigits
- One hit may affect one or more pads.
- Hit position is taken on the anode wires plane as the most of avalanche is developed there.
- This position is not directly available, track intersections with entrance and exit of amplification gap are only stored.
- So the position in the middle of the gap is calculated as average out of pHit->In() and pHit->Out() positions.
- Then, total charge collected for this hit is calculated by AliRICHParam::Hit2Qdc.
- Area of disintegration is a list of pads affected by current hit. This is a parameter of Mathienson
How to get pad number for a local position:
use static TVector AliRICHParam::Loc2Pad(TVector2 position);
Why list of chambers belongs to AliRICHParam:
}//hits loop
}//TreeH loop
}//events loop
+
+
+RICH full simulation-reconstruction sequence
+
+hits->sdigit:
+ Responsible method is AliRICH::Hits2SDigits
+ One hit may affect one or more pads.
+ Hit position is taken on the anode wires plane as the most of avalanche is developed there.
+ This position is not directly available, track intersections with entrance and exit of amplification gap are only stored.
+ So the position in the middle of the gap is calculated as average out of pHit->In() and pHit->Out() positions.
+ Then, total charge collected for this hit is calculated by AliRICHParam::Hit2Qdc.
+ Area of disintegration is a list of pads affected by current hit. This is a parameter of Mathienson
+sdigits->digits:
+ The necessety of sdigits is dictated by the fact that trasport engine transports tracks in a continious sequence track by track.
+ It means that it may happen that the same pad is affected by few tracks. But this might be known only after the trasport of full event is finished.
+
+digits->clusters
+ A set of neighbouring digits compose cluster. The aim of this trasformation is to construct a list of clusters out of digits list.
+ The calling sequence is:
+ AliReconstruction::Run()
+
+ AliRICHReconstructor::Reconstruct() creates an empty clusters list, loops on chambers, retrives a list of digits for a given chamber, gives it to the methode Dig2Clu() and finally serializes
+ the list
+
+ AliRICHReconstructor::Dig2Clu() which knows no details about
+
+
+clusters+tracks->theta cerenkov
+
+
+
+
+
+
+
+
+
+
+
+Generalized structure of AliReconstruction:
+
+Run()
+{
+ if(there is galice.root) <-|
+ AliRunLoader::Open(....) |
+ else | this is done in InitRunLoader()
+ if(raw data process requested) |
+ create galice.root on the base of AliRawReader::NextEvent <-|
+
+ for(all detectors){ <-|
+ if(detector not selected to run) skip this detector | this is done in RunLocalReconstruction()
+ reconstructor=get detector's reconstructor |
+ |
+ if(detector HasLocalReconstruction) skip this detector | IMPORTANT! if HasLocalReconstruction() returns YES use RunLocalEventReconstruction instead
+ if(run upon raw data) |
+ reconstructor->Reconstruct(fRunLoader, fRawReader); |
+ else | <- this approach is currently used by RICH as all branches are mounted in AliRICH.cxx
+ reconstructor->Reconstruct(fRunLoader); |
+ } <-|
+
+ for(all events){
+
+ for(all detectors){ |
+ if(detector not selected to run) skip this detector |
+ reconstructor=get detector's reconstructor |
+ loader=get detector's loader | this is done in RunLocalEventReconstruction()
+ if(raw data process requested and detector HasDigitConversion){ |
+ loader->LoadDigits("update"); | open file and invoke detector->SetTreeAddress();
+ loader->CleanDigits(); |
+ loader->MakeDigitsContainer(); | create tree
+ reconstructor->Reconstruct(fRawReader,loader->TreeD()); | expected to fill TreeD out of raw reader
+ loader->WriteDigits("overwrite"); |
+ loader->UnloadDigits(); |
+ } |
+ if(detector do not HasLocalReconstruction) skip this detector | IMPORTANT! assumed that this detector is already processed in RunLocalReconstruction()
+ loader->LoadRecPoints("update"); |
+ loader->CleanRecPoints(); |
+ loader->MakeRecPointsContainer(); |
+ if(fRawReader && reconstructor do not HasDigitConversion()){ |
+ reconstructor->Reconstruct(fRawReader, loader->TreeR()); | expected to fill TreeR out of raw reader
+ }else{ |
+ loader->LoadDigits("read"); |
+ reconstructor->Reconstruct(loader->TreeD(),loader->TreeR()); | the only operations inside are pDigTree->GetEntry(0) and pCluTree->Fill();
+ loader->UnloadDigits(); |
+ } |
+ loader->WriteRecPoints("OVERWRITE"); |
+ loader->UnloadRecPoints(); |
+ }//detectors loop |
+
+ }//events loop
+}
+
+
+RICH calibration and alignment.
+
+Abstract
+RICH calibrartion and alignment strategy is described with emphasis put on those aspects of the procedure which are relevant for reconstruction and thus the final detector
+figure of merit. In particulare, the refractive index calibration tecknique based on mass plot shifts analisys and chamber alignment with respect to core detectors
+are explained in details. External sources of calibration and alignment data are aslo mentioned as well as the way RICH intends to handle those data, including initial CDB
+creater.
+
+Calibration.
+Looking on RICH chamber structure, full description of which is availbale elsewhere (ref RichTDR), easy to compile the table of all possible parameters affecting reconstruction.
+The first one of major importance is a freon refractive index. Although the full optical path visiable by photons includes freon vessel, proximity and amplification gaps filled
+with methane and quartz window seperating above mentioned volumes, only freon refractive index is subject for calibration. Refractive index of SiO2 window is not practically
+affected by any external parameters, while influence of methane temperature to it's refractive index is negligable. So it's enough to measure there optical curves just once.
+In the rest, the only changable parameter is refractive index of freon. Temperature influence on freon refractive index was measured experimentally. The parametrization
+found to be:
+ n=n0-0.0005(T-20) where T is freon temperature in degrees Celsius
+ n0=Sqrt(1+ 0.554*lamda^2/(lamda^2-5796)) where lamda is photon wavelength in nm taken at 20 degress Celsius
+Preliminary, the parametrization itself is considered to be permamnent one. The only parameter to store and retrieve is freon temperature. Since this value is available from
+DCS DB and expected to be served by a SHUTTLE program which is not yet ready, the following temporaroly solution has been adopted.
+In local CDB storage (deafult directory is $ALICE_ROOT) two versions of freon refractive index are written by external macro RichCdb.C :
+Run0_0_v0_s0.root contains DiMauro's parametrization and the temperature is set to 20 degrees. To be used as default for simulation and reconstruction.
+Run0_0_v0_s1.root contains DiMauro's parametrization and the temperature is set to 50 degrees. To be used in special uncalibrated reconstruction to test calibration procedure.
+Both of them are valid in run range from run number 0 to run number 0, thus in no way affecting any normal operations.
+
+Refractive index of freon (C6F14) is taken in AliRICHRecon for 3 different photon energies by means of 2 methodes: Set
+
+
+
+Alignment.
+Information about detector position and orientation is needed during reconstruction phase. This information affects track-cluster matching procedure, the relevant peace of
+code comes to AliRICHTracker::PropogateBack(). Matching precedure consists in prolongation of the track reconstructed in core detectores up to each RICH chamber plane in
+a sequenmce. The plane used is the entrance to RICH radiators. If the intersection exists and inside the sensitive area, the point of intersection is to be tranformed to RICH
+local reference system. Note, that in this check, the dead zones inbetween radiators are not taken into account. This operation requiring MARS to LORS transformations is done
+in AliRICHHelix::RichIntersection(). Plane to be intersected is defined by a point beloging to that plane served by AliRICHParam::Center(ChamberNumber) and a vector normal
+to the plane served by AliRICHParam::Norm(ChamberNumber). Transformations itself are done in AliRICHParam::Mars2Lors() and AliRICHParam::Lors2Mars(). Internaly in AliRICHParam,
+each chamber is reresented by TGeoHMatrix. It's worth to stress again that geometry related operations are needed to be done for 3 different planes per chamber, namly entrance
+to radiator, anod wires plane and photocathode plane. So AliRICHParam sustains 7*3=21 planes. Also important to say, that direct usage of TGeoHMatrix::MasterToLocal()
+and virce versa is not possible due to special nature of RICH LORS. According to the decision made about 3 years ago, RICH local reference system is centered in low left
+hand corner of the chamber if one looks from outside to direction pointing to interection point.
+So the most obvious candidate for alignable objects to be stored are thess 21 TGeoHMatrix objects.
+The approach suggested in AliAlignObj is not quite feasable mainly due to the fact it relays on incrementing procedure using import from geometry.root. RICH geometry is defined
+in a way that there is no volumes exactly corresponding to the RICH planes.
+
+Geometry of RICH chambers.
+After the decision to rotate the whole RICH setup from 12 o'clock position to 2 o'clock position we have the following situtation:
+
+Theta = 109.5 degress for chambers 1,3
+Theta = 90.0 degress for chambers 2,4,6
+Theta = 70.5 degress for chambers 5,7
+
+Phi = 50.0 degress for chambers 6,7
+Phi = 30.0 degress for chambers 3,4,5
+Phi = 10.0 degress for chambers 1,2
+
+
+Old parametrisation by AliRICHChamber:
+RICH chamber 1 (454.877118 , 80.207109 , -163.565361)(rho,theta,phi)=(490.0,109.5,10.0)
+RICH chamber 2 (482.555799 , 85.087607 , 0.000000)(rho,theta,phi)=(490.0, 90.0,10.0)
+RICH chamber 3 (400.012224 , 230.947165 , -163.565361)(rho,theta,phi)=(490.0,109.5,30.0)
+RICH chamber 4 (424.352448 , 245.000000 , 0.000000)(rho,theta,phi)=(490.0, 90.0,30.0)
+RICH chamber 5 (400.012224 , 230.947165 , 163.565361)(rho,theta,phi)=(490.0, 70.5,30.0)
+RICH chamber 6 (314.965929 , 375.361777 , 0.000000)(rho,theta,phi)=(490.0, 90.0,50.0)
+RICH chamber 7 (296.899953 , 353.831585 , 163.565361)(rho,theta,phi)=(490.0, 70.5,50.0)
+
+New parametrization by TGeoHMatrix:
+RICH 1
+ -0.328736 -0.173648 0.928321 Tx = 454.877118
+ -0.057965 0.984808 0.163688 Ty = 80.207109
+ -0.942641 0.000000 -0.333807 Tz = -163.565361
+RICH 2
+ 0.000000 -0.173648 0.984808 Tx = 482.555799
+ 0.000000 0.984808 0.173648 Ty = 85.087607
+ -1.000000 0.000000 0.000000 Tz = 0.000000
+RICH 3
+ -0.289085 -0.500000 0.816351 Tx = 400.012224
+ -0.166903 0.866025 0.471321 Ty = 230.947165
+ -0.942641 0.000000 -0.333807 Tz = -163.565361
+RICH 4
+ 0.000000 -0.500000 0.866025 Tx = 424.352448
+ 0.000000 0.866025 0.500000 Ty = 245.000000
+ -1.000000 0.000000 0.000000 Tz = 0.000000
+RICH 5
+ 0.289085 -0.500000 0.816351 Tx = 400.012224
+ 0.166903 0.866025 0.471321 Ty = 230.947165
+ -0.942641 0.000000 0.333807 Tz = 163.565361
+RICH 6
+ 0.000000 -0.766044 0.642788 Tx = 314.965929
+ 0.000000 0.642788 0.766044 Ty = 375.361777
+ -1.000000 0.000000 0.000000 Tz = 0.000000
+RICH 7
+ 0.214567 -0.766044 0.605918 Tx = 296.899953
+ 0.255711 0.642788 0.722105 Ty = 353.831585
+ -0.942641 0.000000 0.333807 Tz = 163.565361
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff