- README file for ALICE Time Of Flight Detector Oflfine Code
+ README file for ALICE Time Of Flight Detector Offline Code
==========================================================
Intorduction
------------
This is a short overview of the TOF code within the AliROOT framework.
-
+Some additional details have been introduced to
Structure
---------
AliTOFQADataMakerRec:
+TOF Calibration:
+----------------
+
+1. Online Calibration
+
+1.1. New Calibration Schema
+
+1.1.1. Configuration
+
+The online calibration which is performed by the TOF preprocessor is
+configured according to a CDB object (stored in /TOF/Calib/Config), where
+a flag for the computation of the delays is set according to the type
+of data taking (cosmics ---> kFALSE / beam ---> kTRUE), and where the
+starting validity of the calibration objects that will be written in the
+OCDB is defined (see sec. 1.1.3.). The data are stored in the CDB object
+as entries in a TMap, with IDs "ComputingDelays" and "StartingRun"
+respectively.
+
+1.1.2. Objects
+
+- AliTOFChannelOnlineArray: array of floats containing the delay value
+ calculated for each TOF channel by the TOF preprocessor starting from
+ the DAQ DA for PHYSICS runs (see TOFda.cxx). Inheriting from TObject.
+
+- AliTOFChannelOnlineStatusArray: array of chars defining the status for each
+ TOF channel according to the processing of the data coming from PULSER and
+ NOISE runs (TOFpulserda.cxx, TOFnoiseda.cxx). The status is defined also
+ according to the FEE map written in the DCS FXS, where the status ON/OFF
+ of the channels is stored. The first (least significant) two bits refer to the
+ FEE status, the second two to the pulser data, and the third two to the noise
+ data, leaving the last two empy. The status is always (FEE/pulser/noise)
+ defined as:
+ 00 --> Unknown;
+ 01 --> Good;
+ 10 --> Bad.
+ Inheriting from TObject.
+
+1.1.3. OCDB
+
+- /TOF/Calib/ParOnlineDelay: directory where the AliTOFChannelOnlineArray
+ calibration objects are stored, with validity [0, 999999999], increasing the
+ sv number every time. After offline calibration takes place, in case a reset
+ is needed at run XYZ, the validity changes to [XYZ, 999999999], again
+ with increasing sv.
+
+- /TOF/Calib/Status: directory where the AliTOFChannelOnlineStatusArray
+ calibration objects are stored, with validity [current_run, 999999999]. In
+ case of a PHYSICS run, the update occurs only if the FEE map has changed.
+ In case of a PULSER/NOISE run, the update occurs once at the very end of the
+ processing, so to merge the information from the FEE status map and those
+ from the TOFpulserda/TOFnoiseda.
+
+1.1.4. Reference Data
+
+- /TOF/Calib/DAQData: directory to store the histograms at run level that
+ are produced by the TOFda.
+
+- /TOF/Calib/DCSData: directory to store the data that come out from the
+ processing of the TOF DCS DPs.
+
+- /TOF/Calib/PulserData: directory to store the histograms that are produced
+ by the TOFpulserda.
+
+- /TOF/Calib/NoiseData: directory to store the histograms that are produced
+ by the TOFnoiseda.
+
+- /TOF/Calib/FEEData: directory to store the histogram reproducing the FEE
+ status of the TOF channels.
+
+1.1.5. Usage in Reconstruction
+
+During reconstruction, both the AliTOFChannelOnlineArray and the
+AliTOFChannelOnlineStatusArray corresponding to the current run have to be
+loaded from OCDB in the AliTOFReconstructor class instance. From there,
+they are passed to the AliTOFClusterFinder, where the status of the channel is
+used in order to decide whether to use it or not, while the delay is used to
+calibrate when the offline calibration information is not yet available.
+
+1.2. Old Calibration Schema
+
+1.2.1. Configuration
+
+No OCDB configuration entry is foreseen.
+
+1.2.2. Objects
+
+- AliTOFChannelOnline: object containing the value of the delay for a
+ certain TOF channel. Inheriting from TObject. An TObjArray of 157248 of such
+ objects is used to store the information coming from the TOF online
+ calibration. Inheriting from TObject.
+
+- AliTOFChannelOnlineStatus: object containing the status of a TOF channel
+ as determined during the reading of the FEE map/ during a pulser run/
+ during a noise run. Three TObjArray objects of 157248 of such objects should
+ be present in the OCDB for each run: one related to the FEE status of the
+ channels, one related to pulser run results, and one related to noise
+ run results. The status is defined as:
+ 00 --> Unknown;
+ 01 --> Good;
+ 10 --> Bad.
+ Inheriting from TObject.
+
+1.2.3. OCDB
+
+- /TOF/Calib/ParOnline: directory where a TObjArray of 157248 AliTOFChannelOnline
+ calibration objects are stored, with validity [0, 999999999], increasing the
+ sv number every time. After offline calibration takes place, in case a reset
+ is needed at run XYZ, the validity changes to [XYZ, 999999999], again
+ with increasing sv.
+
+- /TOF/Calib/HW: directory where a TObjArray of 157248 AliTOFChannelOnlineStatus
+ calibration objects are stored, with validity [current_run, 999999999], as
+ obtained from reading the FEE map from the DCS FXS. The update occurs only if
+ the FEE map has changed.
+
+- /TOF/Calib/Pulser: directory where a TObjArray of 157248 AliTOFChannelOnlineStatus
+ calibration objects are stored, with validity [current_run, 999999999], as
+ obtained from a pulser run.
+
+- /TOF/Calib/Noise: directory where a TObjArray of 157248 AliTOFChannelOnlineStatus
+ calibration objects are stored, with validity [current_run, 999999999], as
+ obtained from a noise run.
+
+1.2.4. Reference Data
+
+- /TOF/Calib/DAQData: directory to store the histograms at run level that
+ are produced by the TOFda.
+
+- /TOF/Calib/DCSData: directory to store the data that come out from the
+ processing of the TOF DCS DPs.
+
+- /TOF/Calib/PulserData: directory to store the histograms that are produced
+ by the TOFpulserda.
+
+- /TOF/Calib/NoiseData: directory to store the histograms that are produced
+ by the TOFnoiseda.
+
+- /TOF/Calib/FEEData: directory to store the histogram reproducing the FEE
+ status of the TOF channels.
+
+1.2.5. Usage in Reconstruction
+
+During reconstruction, the TObjArray of AliTOFChannelOnline and the three
+TObjArray objects of AliTOFChannelOnlineStatus coming from the FEE map, the
+pulser run data, and the noise run data corresponding to the current run have to
+be loaded from OCDB in the AliTOFReconstructor class instance. From there,
+they are passed to the AliTOFClusterFinder, where the status of the channel is
+used in order to decide whether to use it or not, while the delay is used to
+calibrate when the offline calibration information is not yet available.
+
+2. TOF Offline Calibration
+
+2.1. Object
+
+- AliTOFChannelOffline: object containing the calibration parameters for
+ each TOF channel that should correct both for the delay introduced by the
+ electronics and the hardware, and for the time slewing effect. A TObjArray
+ of 157248 of such objects is stored in the CDB to perform refined calibration
+ during reconstruction. Inheriting from TObject.
+
+2.2. OCDB
+
+- /TOF/Calib/ParOffline: directory containing the CDB entry corresponding to the
+ offline calibration of the TOF as stored in a TObjArray object of 157248
+ AliTOFChannelOffline objects with validity [0, 999999999], increasing the
+ sv number every time. In case a reset is needed at run XYZ, after collecting
+ the statistics necessary to the offline calibration (when the online
+ calibration object becomes valid again), the validity changes to
+ [XYZ, 999999999], again with increasing sv.
+
+2.3 Usage in Reconstruction
+
+The TObjArray of 157248 AliTOFChannelOffline objects is retrieved for the current
+run in AliTOFReconstructor, and passed to AliTOFClusterFinder. As soon as enough
+statistics is collected for every channel, since the validity
+of the offline calibration object was set, for each channel with a valid
+status, the calibration is performed using the calibration parameters present in
+this TObjArray of AliTOFChannelOffline.
+
Authors:
--------
git://git.uio.no / u / mrichter / AliRoot.git / blobdiff