ITS Calibration Database Requirements Updated By Bjørn S. Nilsen On behalf of the ALICE ITS Sub-detector Group

Feb ALICE February Offline Week, Calibration Database Workshop 2 Outline Alignment Calibration Data SPD Calibration Data SDD Calibration Data SSD Assess patterns and usage Conclusions

Feb ALICE February Offline Week, Calibration Database Workshop 3 Alignment AliITSgeom & AliITSgeomMatrix 2198 Detectors, 6 degrees of Freedom Must be fast and compact Must allow for multiple instantiations and easily switch between different instantiations easily and quickly Needs to handle different coordinate system Needs to be useful in simulation, reconstruction, tracking, and alignment

Feb ALICE February Offline Week, Calibration Database Workshop 4 Alignment AliITSgeom & AliITSgeomMatrix AliITSgeomMatrix. –Sizeof(AliITSgoemMatrix) = 164Bytes (in memory), 126Bytes on disk uncompressed. –Minimum required 64Bytes (require much computation so slow). AliITSgeom. –Sizeof(AliITSgeom) = 60Bytes + allocated memory ( Bytes) = Bytes total. –Minimum required Bytes.

Feb ALICE February Offline Week, Calibration Database Workshop 5 Response & Calibration Data Can, and should, be different between simulation and reconstruction. Will depend on run/event number in some almost unpredictable way. Will need to be changed with time as newer and better methods are developed. Will need to be able to retrieve and use older values at any point in the future.

Feb ALICE February Offline Week, Calibration Database Workshop 6 SPD Data 240 Detectors, pixels/detector, 4% Simulation Thresholds/cell (16bits) Noise levels/cell (16 bits) List of Dead Pixels and Chips –Bit pattern  5120Bytes/detector –At 2% dead pixels +16σ  2600Bytes/detector A dead Chip  20% Bytes/det  Bytes total Reconstruction List of Dead Pixels and Chips – Bit pattern  5120Bytes/detector –At 2% dead pixels +16σ  2600Bytes/detector A dead Chip  20% List of Extra-noisy pixels? 4 136Bytes/det  Bytes total

Feb ALICE February Offline Week, Calibration Database Workshop 7 SPD Data Dead pixels will not come back to life. Small chance that new dead pixels will be added. Noisy pixels are very unlikely to improve. New noisy pixels very rare.  Data update will be uncommon.

Feb ALICE February Offline Week, Calibration Database Workshop 8 SDD Data 2X256 anodes, ~200 time-bins, 6X33 injectors, 260 detectors For Both Simulation and Reconstruction For each Anode  3 Bytes. –Thresholds (Not needed for Reconstruction). Low (4 bits). High (4 bits). –Baseline (6 bits). –Gain (6 bits). –Noise ( ). Amplitude (4 bits). Pedestals, 2 per detector (8 bits total) Thermal map ( sets drift velocity ). –198 measurements (24 bits/measur. = 8 amplitude + 16 time)  594 Bytes. Dopant concentration map ( shifts in both time and anode mean values ). – measurements (2*10 bits/cell)  Bytes. –Maximum deviation of 500μm Bytes/detector  Bytes for all SDD such a detailed measure of the noise may only be possible for zero non-suppressed data/events

Feb ALICE February Offline Week, Calibration Database Workshop 9 SDD Data Thresholds, baseline, gains. –Set at start of run. Noise. –Tests show to be stable, but may change. Temperature map. –Transient at startup (half life ?). –Then, should remain stable. Dopant map. –Fixed and measured in lab. –In construction data base.  Generally Stable or minimal changes over time.

Feb ALICE February Offline Week, Calibration Database Workshop 10 SSD Data 2X768 Anodes/cathodes, 1698 detectors Simulation and Reconstruction For each Anode and Cathode  4 Bytes. –Pedestal (8 bits). –Threshold (8 bits). –Noise & always-off/on flag (8 bits). –Gain (8 bits) Bytes/det  Bytes total.

Feb ALICE February Offline Week, Calibration Database Workshop 11 SSD Data Pedestal, Threshold, & Gain. –Set at beginning of run. –Will not change during run. Noise. –Measured in special runs. –Should not change much with time.  Generally stable or minimal changes over time. Total ITS reconstruction data volume Bytes

Feb ALICE February Offline Week, Calibration Database Workshop 12 Access Patters My point of view

Feb ALICE February Offline Week, Calibration Database Workshop 13 Access Patters Continued Data Base. –Each Value “separate”, individually queriable. Value may vary by time/event/run Value may even be represented by some function of some time/event/run range –Full history of each value. When last changed Who made change Calibration File. –Specific values needed to analyze specific events/runs at a give sight and/or cpu. –Minimal size and fast access required Ali???Calibration (e.g. AliITSCalibrationSDD). –Class with specific data for a specific event as used inside of AliRoot. –Must be quickly updated from Calibration file for next event (possibly next detectors) –Must be in a form efficiently usable by reconstruction.

Feb ALICE February Offline Week, Calibration Database Workshop 14 Conclusion Alignment takes Bytes Calibration takes Bytes –Calibration data is made up of fixed, slowly changing, and rarely but abruptly changing values. –Generally the changes in the calibration data set is expected to be rather stable. –This is a realistic yet minimum data size ( more likely to rise then drop ). The “master” calibration data is best kept in a data-base. Usage requires much faster access, and therefore a local copy in a form similar to that used in AliRoot. } Bytes