Summary of Workshop on Calibration and Alignment Database Magali Gruwé CERN PH/AIP ALICE Computing Day February 28 th 2005

2 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Goals of the workshop  Primary: offline calibration and alignment database:  Discussion and summary of user requirements:  Boundary conditions for the offline database  Relations with external databases and basis for discussion with the groups which develop them  Access methods and related framework  Minimal set of metadata requirements  Also important: alignment and calibration algorithms:  Detector specific tasks:  Common implementation strategy in AliROOT and Geometrical Modeller (for alignment)  External software – what will be needed to make it work  Global alignment and calibration:  Preliminary ideas

3 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Agenda  February 22 nd and 23 rd  Introduction and context (Latchezar betev)  Full day session on User Requirements  Detectors presentations  HLT presentation (Timm Steinbeck)  Summary (Magali Gruwé)  DCS point of view (Peter Chochula)  AliRoot classes for access to the Calibration and Alignment Database (Magali Gruwé)  First thoughts about detector alignment (Karel Safarik)  Work plan (Latchezar Betev)

4 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Layout  User Requirements  Call for User Requirements  Answers from detectors (including HLT)  Remaining questions  DCS  Detector Alignment  Work plan  Conclusion

5 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Session on User Requirements  Quite successful:  Presentations from 12 (out of 14) detectors  EMCAL has same requirements as PHOS  ACORDE couldn’t make it, but has sent requirements by  HLT has presented its requirements as well  But:  Some points to be clarified  Some questions not quite answered  One detector didn’t give enough thought to the question  Positive:  Presentations have triggered a lot of discussion  Detectors have realized it is an important topic to be dealt with now  They have started working seriously on calibration, and to a less extent on alignment

6 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Call for user requirements (I)  Essential parameters of the Alignment and Calibration DBs:  Access pattern and frequency  Only offline reconstruction?  Typical record size  Very difficult to estimate from first principles  Frequency of updates  We expect the majority of the updates to be infrequent  This probably will not be the case  Validity range parameters  Run, event, time, version – what else?  These all have to come from the user community More details/explanations in next slides…

7 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Call for User Requirements (II)  Context:  The alignment and calibration constants will be ROOT files, registered in a distributed file catalogue. The files will have proper tags, described in the AliEn (gLite) metadata catalogue:  validity period – run, event, time  Version  Questions:  What type and size of Root objects will be needed for the alignment and calibration procedures?  For example:  One calibration object could be a set of gain constants of a calorimeter, written in a root file. This object will have a certain size and will be valid for a given period of time, until the next calibration is taken or the present one is refined (new version).

8 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Call for User Requirements (III)  Questions (cont’d)  How frequently will these root objects have to be updated (new version produced)?  How frequently will these root objects have to be accessed?  What kind of and how much access to external databases will be needed?  External databases could be:  Construction database (DCDB)  ECS  DAQ  DCS  Trigger  HLT

9 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Answers from detectors (I)  Answers received from all 14 detectors + HLT  Some by mail  Last ones during the workshop  But:  Some are still preliminary:  Need update  Most are incomplete:  Need to be thought about and completed  Some show misunderstanding:  Need clarifications from both sides

10 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Answers from detectors (II)  Three types of objects:  Calibration related  Alignment related  Dead/bad channel maps  Note:  Some detectors specify “one object per channel”  This will NOT happen: there will be ONE object for all channels  Examples:  One “gain” object being an array containing all gains of all channels  One calibration object being and array of all gains and pedestals of all channels

11 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Answers from detectors (III)  Size: (rough counting)  ITS: ~80 MB  TRD: few MB  PHOS: ~1MB  EMCAL: ~1MB  RICH: ~1MB?  CRT: few kB  MUON: ~70MB  ZDC: few kB  V0: 3.5 kB  PMD: few MB  TOF: ~7MB  TPC: ??? !

12 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Answers from detectors (IV)  Update frequency:  In general: anything between 1/run and 1/year  Note:  Some parameters vary quickly (every minute or so), but update frequency will not be higher than once per run. Stored objects would be histograms for example.  Example:  One drift velocity object being a histogram with the time dependence of the drift velocity within a run

13 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Answers from detectors (V)  Access pattern/frequency:  For most detectors: no answer, or there seems to be confusion with update frequency  Questions:  How often do you need the data?  Only in reconstruction jobs?  Is there an iterative procedure?  Clearly, there is better understanding thanks to workshop:  In most cases access frequency one per run reconstruction job

14 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Answers from detectors (VI)  External Database access:  Very little input from detectors:  Most detectors said:  No external database access needed  Or did/could not answer  Some input:  FMD:  Need to know how the detector was operated at the time of data acquisition, beam species, etc…  ITS:  DCDB, DCS  TRD:  ESD only?  CRT:  Need run header  ZDC:  General run conditions  Machine Database!  V0:  General trigger  T0:  DCDB

15 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 HLT  Special in that it is only a consumer, not a producer, of Alignment and Calibration data  Alignment and Calibration data read and processed then maybe sent to database  Reading:  size depends on input from detectors  frequency depends on update frequency of detectors  Writing:  update frequency of detectors  size less than raw data (depends on detector)

16 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Remaining questions…  A lot of information received from detector people ( s and presentations):  These give us an excellent starting point  Problem with respect to size of objects needed for some detectors:  Need to find a way to reduce it  Home work for detector groups:  Think again about requirements (with the highlight of the other detectors’ presentations)  And more specifically about External Database access  A note is being written summarizing our understanding of detectors requirements. It will be circulated soon.

17 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Layout  User Requirements  Call for User Requirements  Answers from detectors (including HLT)  Remaining questions  DCS  Detector Alignment  Work plan  Conclusion

18 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 DCS’s point of view  Presented by Peter Chochula:  “Calibration data provided by the DCS”  Some calibration data  is acquired and provided by the DCS  should be sent back to DCS  Architecture  Type of data, going to  Configuration database  Archives  Peter stressed the sooooo many points to be discussed, defined, sorted out, …  Database API, access patterns, …  Calibration procedures, time slots, …  Data from alignment systems, from CCDs, …

19 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Layout  User Requirements  Call for User Requirements  Answers from detectors (including HLT)  Remaining questions  DCS  Detector Alignment  Work plan  Conclusion

20 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Detector Alignment  Presented by Karel Safarik  Detector Alignment to be done in 3 steps:  Positioning  Survey   Calibration   Alignment  With straight tracks  With magnetic field  Changing magnetic field polarity  Alignment procedure should be studied  Software for no-field data  Define the histograms to control the alignment after ramping the magnetic field  Online control of alignment

21 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Layout  User Requirements  Call for User Requirements  Answers from detectors (including HLT)  Remaining questions  DCS  Detector Alignment  Work plan  Conclusion

22 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Work plan  Presented by Latchezar Betev  Only one year to complete the task:  Ready for full functionality tests during PDC 2006  Next immediate steps:  Complete User Requirements collection by end of March  AliRoot access framework:  Prototyping by April  Some detectors are awaiting  Alignment procedures and Geometrical Modeler  Future steps:  Access to external databases

23 Magali Gruwé CERN PH/AIP ALICE Computing Day, February 28 th, 2005 Conclusion  Quite a successful workshop  Loads of information gathered  Loads of fruitful discussions  Loads of ideas and comments  A lot to do now…