2 \section{EMCal OCDB/OADB - Marcel}
4 OCDB is the Offline data base. It contains the different parameters used for simulation or reconstruction of the detectors or even the LHC machine parameters that might change for the different run conditions.
6 OADB is the Offline Analysis data base.
8 The EMCAL OCDB (and other detectors OCDB) is divided in 3 directories that can be found in
10 $ALICE_ROOT/OCDB/EMCAL
13 \item Calib: Very different type of information, from hardware mapping to calibration parameters.
14 \item Align: Survey misplacements in geometry.
15 \item Config: Detector configuration, temperatures
18 Inside these directories you will find other subdirectories with more specific types of parameters. Each of the directories contains a file named in this way:
20 Run(FirstRun)_(LastRun)_v(version)_s(version).root
22 being the default and what you will find in the trunk
24 Run0_999999999_v0_s0.root
27 What is actually used for the real data reconstruction can be found in alien here:
29 /alice/data/20XX/OCDB/EMCAL
31 There are different repositories for different years (20XX). For the simulation productions, there is another repository on the grid:
33 /alice/simulation/2008/v4-15-Release/XXX/EMCAL
35 which is divided into 3 other repositories: Ideal, Full and Residual. Each one is meant to reproduce the detector with different precision. For EMCAL, right now these 3 repositories contain the same parameters.
37 The following section explain the elements stored and how to read and fill OCDB parameters.
39 \subsection{Accessing a different OCDB}
41 In the simulation/reconstruction macro a default OCDB needs to be specified if different from
45 When running on the grid, one needs to set for example in a reconstruction of simulated data:
47 reco.SetDefaultStorage("alien://Folder=/alice/simulation/2008/v4-15-Release/Residual/");
49 If one or several OCDB files have been modified, the following line has to be added in the simulation or reconstruction macro:
51 reco.SetSpecificStorage("EMCAL/Calib/Pedestals","local://your/modified/local/OCDB");
54 The file with the calibration coefficients needs to be stored in the directory :
56 /your/modified/local/OCDB/EMCAL/Calib/Data
59 If more of the OCDB files are modified, add the following line :
61 reco.SetSpecificStorage("EMCAL/Calib/","local:/your/modified/local/OCDB");
63 with all the directories inside \begin{lstlisting} EMCAL/Calib \end{lstlisting} and corresponding files put in
65 /your/modified/local/OCDB/EMCAL/Calib/
68 \subsection{Energy calibration}
70 Calibration Coefficients tower by towers are stored in the following directory :
74 What is stored is an object of the class AliEMCALCalibData which is a container of gains and pedestals per tower. These coefficients are used in:
76 \item Simulation: during the digitization, in AliEMCALDigitizer::Digitizer(), when calling AliEMCALDigitizer::DigitizeEnergy(), to transform the deposited energy into ADC counts.
77 \item Reconstruction: in AliEMCALClusterizerv1::Calibrate() called in AliEMCALClusterizer::MakeClusters(), when forming the cluster, to get the final cluster energy.
81 $ALICE_ROOT/EMCAL/macros/CalibrationDB/AliEMCALSetCDB.C
83 is an example on how to set the calibration coefficients per channel, or how to read them from the OCDB file. This macro can set all channels with the same selected value or with random values given a uniform or gaussian smearing of a selected input value. A simple example that shows how to print the parameters is PrintEMCALCalibData.C
85 All channels in the simulation have the same value for the gains (0.0153 GeV/ADC counts) and pedestal (set to 0 since the calorimeter works with Zero Suppressed data).
87 \subsection{Bad channels}
89 Storage for the bad channels map found in hardware are here :
93 The object stored is from the class AliCaloCalibPedestal used for monitoring the towers calibration and functionality. This class has the data member TObjArray *fDeadMap which consists of an array of 12 TH2I (as many as Super Modules), and each TH2I has the dimension of 24x48 (number of towers in $\phi\times\eta$ direction), each bin corresponds to a tower. The content of each entry in the histogram is an integer which represents the possible status:
95 enum kDeadMapEntry{kAlive = 0, kDead, kHot, kWarning, kResurrected, kRecentlyDeceased, kNumDeadMapStates};
97 Right now only the status kAlive, kDead, kHot and soon kWarning (soon, not yet) are set but, the code is basically skipping all the channels that are kDead and kHot. The bad channel map is used in the reconstruction code in 3 places:
99 \item AliEMCALRawUtils::Raw2Digits() : Before the raw data time sample is fitted, the status of the tower is checked, and if bad (kHot or kDead), the fit is not done. This avoids trying to fit ill shaped samples. This step is optional though, right now default is to skip the bad channels here. With the RecParam OCDB we can select to use it or not.
100 \item AliEMCALClusterizerv1::Calibrate(): once the cluster is formed, to get the cluster energy from its cells.
101 \item AliEMCALRecPoint::EvalDistanceToBadChannels(): Evaluate the distance of a cluster to the closest bad channel. During the analysis we may want to skip clusters close to a bad channel. This time a bad channel is whatever is not kAlive.
106 $ALICE_ROOT/EMCAL/macros/PedestalDB/AliEMCALPedestalCDB.C
108 is an example on how to set the bad channel map and how to read it from a file. When executed, it displays a menu that allows to set randomly as bad a given \% of the towers. It also allows to set the map from an input txt file, with the format like\\ \$ALICE\_ROOT/EMCAL/macros/PedestalDB/map.txt (this map file is the one used in the last mapping in the raw OCDB). It can also read the OCDB file and display the 12 TH2I histograms on screen.
110 \subsection{Reconstruction parameters}
112 The storage of the parameters used in reconstruction is done in
114 EMCAL/Calib/RecoParam
116 What is stored is an object of the class AliEMCALRecParam which is a container for all the parameters used. There are different kind of parameters, we can distinguish them depending on which step of the reconstruction are used as explained below.
118 \paragraph*{Raw data fitting and mapping}
121 \item Double\_t fHighLowGainFactor; // gain factor to convert between high and low gain
123 \item Int\_t fOrderParameter; // order parameter for raw signal fit
125 \item Double\_t fTau; // decay constant for raw signal fit
127 \item Int\_t fNoiseThreshold; // threshold to consider signal or noise
129 \item Int\_t fNPedSamples; // number of time samples to use in pedestal calculation
131 \item Bool\_t fRemoveBadChannels; // select if bad channels are removed before fitting
133 \item Int\_t fFittingAlgorithm; // select the fitting algorithm
135 \item static TObjArray* fgkMaps; // ALTRO mappings for RCU0..RCUX
138 \paragraph*{Clusterization }
141 \item Float\_t fClusteringThreshold ; // Minimum energy to seed a EC digit in a cluster
143 \item Float\_t fW0 ; // Logarithmic weight for the cluster center of gravity calculation
145 \item Float\_t fMinECut; // Minimum energy for a digit to be a member of a cluster
147 \item Bool\_t fUnfold; // Flag to perform cluster unfolding
149 \item Float\_t fLocMaxCut; // Minimum energy difference to consider local maxima in a cluster
151 \item Float\_t fTimeCut ; // Maximum difference time of digits in EMC cluster
153 \item Float\_t fTimeMin ; // Minimum time of digits
155 \item Float\_t fTimeMax ; // Maximum time of digits
158 \paragraph*{Track Matching}
161 \item Double\_t fTrkCutX; // X-difference cut for track matching
163 \item Double\_t fTrkCutY; // Y-difference cut for track matching
165 \item Double\_t fTrkCutZ; // Z-difference cut for track matching
167 \item Double\_t fTrkCutR; // cut on allowed track-cluster distance
169 \item Double\_t fTrkCutAlphaMin; // cut on 'alpha' parameter for track matching (min)
171 \item Double\_t fTrkCutAlphaMax; // cut on 'alpha' parameter for track matching (min)
173 \item Double\_t fTrkCutAngle; // cut on relative angle between different track points for track matching
175 \item Double\_t fTrkCutNITS; // Number of ITS hits for track matching
177 \item Double\_t fTrkCutNTPC; // Number of TPC hits for track matching
183 \item Double\_t fGamma[6][6]; // Parameter to Compute PID for photons
185 \item Double\_t fGamma1to10[6][6]; // Parameter to Compute PID not used
187 \item Double\_t fHadron[6][6]; // Parameter to Compute PID for hadrons
189 \item Double\_t fHadron1to10[6][6]; // Parameter to Compute PID for hadrons between 1 and 10 GeV
191 \item Double\_t fHadronEnergyProb[6]; // Parameter to Compute PID for energy ponderation for hadrons
193 \item Double\_t fPiZeroEnergyProb[6]; // Parameter to Compute PID for energy ponderation for Pi0
195 \item Double\_t fGammaEnergyProb[6]; // Parameter to Compute PID for energy ponderation for gamma
197 \item Double\_t fPiZero[6][6]; // Parameter to Compute PID for pi0
204 $ALICE_ROOT/EMCAL/macros/RecParamDB/AliEMCALSetRecParamCDB.C
206 is an example on how to set the parameters. There are different event types that we might record, and each event type may require different reconstruction parameters. The event types that are now defined in STEER/AliRecoParam.h are:
208 enum EventSpecie\_t {kDefault = 1, kLowMult = 2, kHighMult = 4, kCosmic = 8, kCalib = 16};
212 The default event species that we have is kLowMult (low multiplicity). For AliRoot versions smaller than release 4.17 it was set to be kHighMult (high multiplicity). Today, the code is as follow :
214 kDefault=kLowMult=kCosmic=kCalib.
216 kHighMult differs only from the other two in 2 clusterization parameters, for low multiplicity they are fMinECut=10 MeV and fClusteringThreshold=100 MeV and for high multiplicity they are fMinECut=0.45 GeV and fClusteringThreshold=0.5 GeV.
218 A simple example that shows how to print the parameters for the different event species is PrintEMCALRecParam.C
221 \subsection{Simulation parameters}
224 The parameters used in the simulation are stored in EMCAL/Calib/SimParam. What is stored is an object of the class AliEMCALSimParam which is a container of all the parameters used. There are different kind of parameters depending on the step of the simulation :
226 \paragraph*{SDigitization}
228 \item Float\_t fA ; // Pedestal parameter
230 \item Float\_t fB ; // Slope Digitizition parameters
232 \item Float\_t fECPrimThreshold ; // To store primary if Shower Energy loss > threshold
235 \paragraph*{Digitization}
237 \item Int\_t fDigitThreshold ; // Threshold for storing digits in EMC = 3 ADC counts
239 \item Int\_t fMeanPhotonElectron ; // number of photon electrons per GeV deposited energy = 4400 MeV/photon
241 \item Float\_t fPinNoise ; // Electronics noise in EMC = 12 MeV
243 \item Double\_t fTimeResolution ; // Time resolution of FEE electronics = 600 ns
245 \item Int\_t fNADCEC ; // number of channels in EC section ADC =
249 The macro \$ALICE\_ROOT/EMCAL/macros/SimParamDB/AliEMCALSetSimParamCDB.C, is an example on how to set the parameters. A simple example that shows how to print the parameters is PrintEMCALSimParam.C
251 \subsection{Alignment}