Update on time calibration with optical beacons

1. Update on time calibration with optical beacons Collaboration Meeting Roma, 7-10 May 2012 Agustín Sánchez Losa IFIC (CSIC – Universitat de València)

2. Outline • Reminder of the time calibration with OBs • Intraline calibration: T0s • Nothing new since CERN’12 • Interline calibration: Time offsets • Laser position and its impact in offsets • Some order in the DB tables of T0s • To-Do List Agustín Sánchez Losa – Roma Collaboration Meeting

3. Reminder of the time calibration F 10 F 9 • Time calibration recipe: • Flash various OMs at the same time by an OB • Plot the distribution of hit arrival times for each ARS • Fit such distribution with a Gauss@Exponential function • Determine Tpeak , the time of the function peak • Plot Tpeakvs distance • Deviations from the straight line fit will be used as corrections to the T0s F 8 F 7 F 6 F 5 F 4 F 3 F 2 Agustín Sánchez Losa – Roma Collaboration Meeting F 1

4. Reminder of the time calibration Intraline calibration • T0 in thesame line • LED OB • Early-photonregion LED Interline calibration LED • time offsets between lines • Laser OB • Photo-electronlevelregion Laser Agustín Sánchez Losa – Roma Collaboration Meeting

5. Nothing new since CERN'12 Intraline T0s in the same line by means of the LED OBs Agustín Sánchez Losa – Roma Collaboration Meeting

6. Interline Time offsets between lines by means of the Laser OB Agustín Sánchez Losa – Roma Collaboration Meeting

7. Interline: Laser position impact on offsets • Was detected the use of an incorrect position of the laser (Ciro’s curiosity fault) • Laser offsets recomputed for all the periods (from Aug'09 to Dec'11) • The impact in the laser offsets has been measured and estimated Agustín Sánchez Losa – Roma Collaboration Meeting

8. Interline: Laser position impact on offsets L8 L4 L1 L2 L1 L2 F 10 F 10 L5 L3 L4 L6 L3 L6 L5 L9 L7 L8 L10 L9 L7 L10 L11 L12 F 8 L11 L12 F 5 F 4 F 1 Early photon Region Photoelectron Level Region F 10 F 8 - F 9 F 3 - F 4 F 1 Agustín Sánchez Losa – Roma Collaboration Meeting

9. Interline: T0s tables in the DB • Someorderhavebeen done in the T0s DB tables: • Allofficial T0s LABEL fieldhave a clearordered #id • OFFICIAL value has a clear use: • OFFICIAL = 2 → Best T0s available without any interline offset added • OFFICIAL = 3 → Best T0s available with interline offset added (see USER_COMMENT field explains which ones) • Now APP_START field is coherent for all the periods • Sample SQL call: select version_id, label, app_start, user_comment, udate, official from antares.ars_t0 where official = 2 or official = 3 order by official, app_startdesc Agustín Sánchez Losa – Roma Collaboration Meeting

10. Interline: T0s tables in the DB • Sample SQL call: Agustín Sánchez Losa – Roma Collaboration Meeting

11. To-Do List • Intraline calibration by OB: • Compute intermediate T0s • Recompute old T0s with updated TVCs and study the impact of using ones or another • Research & Improvement on intraline calibration: Calibrate the first floors of each line, study the impact of a calibration with independent sections, Study unstable PMTs since HV tuning in Summer'10, etc. • Interline calibration by OB: • Research & Improvement on interline calibration. Agustín Sánchez Losa – Roma Collaboration Meeting

12. Thankyou foryourattention