Study of the systematic due to the time calibration procedure

1. Telephone meeting, March 12, 2008 Study of the systematic due to the time calibration procedure Vera Kovalenko, JINR/IPHC, Dubna Plan • Comparison of two time calibrations (version 0 and version 5). • Calibration modifications. Different versions and their comparison.

2. Time calibration: different versions • Version 0: for all experimental data always the prehistoric time calibration TsRelease = 4 TsVersion = 1 TsType=3 in the data base is used. No LTCs. • Version 5: default time calibration procedure: there are LTCs, individual TE curves and time calibrations of each period of the calibration (each period defined by the EC application date). Data: laser runs from 1361 (15/2/2003) to 6341 (10/1/2008); noalpha runs from 1071 to 3974 EC Release 5-60; all betabeta runs from 1869 (15/2/2003) to 6538 (17/12/2007) with Status=1.

3. The reduce of the exposition time • Using the standard procedure (v5) we loose the data equivalent to ~1.2% of the maximal time exposition (v0). It happens due to the absence of good laser runs near a ββ run or when nearest following and preceding laser runs are too far (>24h) from each other. • The most important reduction was in 2005 (2.7%) and in 2003 (2.1%).

4. Comparison of versions 0 and 5

5. Comparison of versions 0 and 5 Effect of LTCs is seen clearly in 2005-2007, but not in 2003! Why? The laser runs are only once per day in 2003?!

6. Comparison of versions 0 and 5 Probably our problems in describing the energy and angular spectra in Tenat and Cu for the Phase 1 are due to the imperfect “Laser Time Correction” procedure? How to feel it and what are the possibilities to improve the time calibration procedure ?

7. Time calibration: add different versions • Version 0: for all experimental data always the prehistoric time calibration TsRelease = 4 TsVersion = 1 TsType=3 in the data base is used. No LTCs. • Version 5: default time calibration procedure: there are LTCs, individual TE curves and time calibrations of each period of the calibration (each period defined by the EC application date). • Version 6: time calibration is made once in early 2003 (EC release 5) with the use of individual TE curves (table “te” in db). No LTCs. No division on the periods. • Version 7: individual TE curves and time calibration for each calibration period. No LTCs. • Version 8: individual TE curves, LTCs (from version 5) and no divisions on the periods. 1 set of TS from early 2003 (TsReasease=5, TsVersion=5). Data: laser runs from 1361 (15/2/2003) to 6341 (10/1/2008); noalpha runs from 1071 to 3974 EC Release 5-60; all betabeta runs from 1869 (15/2/2003) to 6538 (17/12/2007) with Status=1.

8. Compare all versions using the same list of ββruns Version 5 looks to be the best for the moment, but results of version 8 look suspicious. Conclusion: probably we should use reference laser runs for each laser period (given by Christine) when there was an intervention to the laser system.

9. The procedure of the calibration, version 10 • Find the best laser run in each Laser period (when there is no TDC jumps, neither bad PMs). • Associate this laser run as the reference one for all laser runs of given Laser period. • Do the rest of the calibration procedure as previously. Seen problems: • For Periods 6-11/13/16/20 it was impossible to find good reference laser run. The appropriate run of the period 5/12/18/18 has been used instead. • The start of the Release Application Date given by Christine is not exactly the end of the previous Release. It resulted the problems in the data processing and will lead to the data loosing. In our data base only starts of the application dates are used, so runs between the end of the Release and the start of the next Release are associated to the “previous” Release. This is not correct! See the illustration on the next slide

10. Wrongly associated laser runs Period #L13: 21/07/2006 17:30 – 31/10/2006 10:30 LASER4 1rst: laser_2_4831 21/07/2006 18:24 LASER4 last: laser_2_5011 31/10/2006 10:45 Ec38 : 21/07/2006 17:30 – 28/08/2006 23:59 Ec39 : 29/08/2006 00:00 – 06/10/2006 23:59 Ec40 : 07/10/2006 00:00 – 31/10/2006 10:30 Period #L14: 07/11/2006 08:00 – 17/01/2007 10:00 LASER4 1rst: laser_2_5027 07/11/2006 08:00 LASER4 last: laser_2_5199 17/01/2007 09:40 Ec41 : 07/11/2006 08:00 – 17/11/2006 23:59 Ec42 : 18/11/2006 00:00 - 08/12/2006 23:59 Ec43 : 09/12/2006 00:00 - 29/12/2006 23:59 Ec44 : 30/12/2006 00:00 - 17/01/2007 10:00 Runs from 31/10/2006 to 07/11/2006 are automatically associated to the Release 40, but must be to the Release 41 (because the intervention to the laser system was 31/10/06). I had to remove them for LTCs calculation  no nearest laser run for ββ data  less useful ββ data.

11. Reference laser runs for LTCs calculation (version of the time calibration 10). • Reference laser runs: Releases 5÷6 run 1404; Releases 7÷10 run 1687; Releases 11÷12 run 2024; Releases 13÷28 run 2109; Releases 29÷38 run 4125; Releases 41÷44 run 5027; Releases 45÷47 run 5213; Releases 48÷60 run 5879.

12. Bad results of the calibration Version 10 There was chosen wrong reference run 5879 There was chosen wrong reference run 4125

13. Sigma of DeltaT(ns) vs TDC card (io*20+sector) and EC Release (versions 5 and 10). No real improvement. Sigma of ΔT, ns Sigma of ΔT, ns io*20+sector io*20+sector Why the time resolution is better in the TDC cards with big jumps?

14. Few hypothesis: • With current ideology of time corrections we correct only big clear jumps. when small fluctuation happened, PMs were not removed from the analysis. • There is some real systematic time resolution of each TDC card; Try to prove or disprove first hypothesis. For this one use more strict criteria when look TDC change between each laser run in order to detect bad PM (table “lb”).

15. Difference between mean TDC of each PM for two closest laser runs AFTER:kill 443 PM BEFORE: kill 54 PM 3·σ 3·σ 250ps 250ps σ19.5 ps

16. Mean number of killed PM is 82 NbadPM Analysis of the TDC shift between closest laser runs. Put implicitly number of bad PMs=1940 if two closest laser runs are too far from each other (>50h) or there is the change of the Laser Period. Almost all cases when Nbad > 200 correspond to the electrical shutdown (ESD) or some interventions to the detector.

17. 08:16 start betabeta run 6509 ************************************************* Elrctricity SHUTDOWN (in Modane). ************************************************* 11:11 stop betabeta run 6509 (timeout) multiplicity=2.01808 - too HIGH ***** CALORIMETER ****************************************************** Power supply (crate 31) is OFF after 1 min. of power ON. Message on fan tray: "Fan fail". There are 6 fans: fan in 1-st row right side - no rotation. There is no fan (3 wires, "wiener") to change. AUTO OFF CONTROL - enabled - "in case of fan failing the crate will NOT be set OFF" (VME crate user manual page 17). ************************************************************************ 14:53 start betabeta run 6511 16:07 stop betabeta run 6511 S0/R0-3 - Ich.16-19~10-20uA multiplicity=2.01924 - too HIGH 16:14 start betabeta run 6512 19:57 stop betabeta run 6512 S0/R6-8 - Ich.22-24~10-20uA 5 NEW missing PM: 4/1/1/3 - cr3 bo5 ch14 10/0/0/11 - cr2 bo0 ch10 10/0/0/12 - cr2 bo0 ch18 10/0/2/10 - cr2 bo0 ch2 10/0/2/11 - cr2 bo0 ch2 multiplicity=2.00887 - too HIGH 19:57 start laser_nemo2_auto 6268 *********************************************************************************** Date: 19.08.2005, Friday Operators: Igor *********************************************************************************** TIMEOUT 30000 msec. 282326 events. 09:15 Stop BetaBeta run 4185 -> Geiger - stop EVB - running Global - running Calo - absent RMP_DISK - running !!!!! Calo !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! PM crate 1(B21) is OFF -> Electrical box: switch is in position OFF -> put in ON -> PM crate 1(B21) is OFF. Safety fuse (grey box on the floor just near PC19) is broken. After change of it switch in electrical box is ON -> safaty fuse is broken There is something wrong in power supply. There is found power supply which is prepared for sendig in Orsay (Xavier told). It has a label "There is a problem with 15V". It is installed in B21. !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! 13:15 Calo run 3803 (rate=143.02/438.927 (rate is too LOW), 1 new missing PM (87): 13/1/1/11 - cr2 bo7 ch18, 1 high counting PM: 8/2/3/0 - cr3 bo8 ch5, NO flashy PM). 13:24 laser_nemo2 run 3815 (rate=O.K., NO new missing PM (74), 1 high counting PM: 3/2/3/1 - cr3 bo5 ch4, NO flashy PM, 3 inches <ADC>=311.296 (too LOW), 5 inches <ADC>=370.147 (O.K.)). 22:28 Stop betabeta run 6476 --- Shutting OFF electricity in LSM Noisy hit 17-8 Increase GG HV +1V 3 high counting rate PM 2/1/0/7 HV cr1 bo8 ch3 8/2/3/0 HV cr3 bo8 ch5 9/1/1/12 HV cr3 bo9 ch10 <adc> 3"= 243.701 OK <adc> 5"= 258.253 OK --------------------------------------------------------------- 27.11.2007 Operator Oleg Kochetov -------------------------------------------------------------- 9:00 SWITH ON GG AND CALO ELECTRONIS CRATES 9:18 laser_nemo2_auto run 6232 1 high counting rate PM 9/1/1/12 HV cr3 bo9 ch10 <adc> 3"= 348.424 too low!!! <adc> 5"= 479.159 OK The stop of run 2850 was accidental due to a Geiger crate OFF. Xavier played with the slow control VNC viewer of the Geiger acquisition crates and as usual, vncviewer switched OFF Geiger crate 3 (B30). Cpy and zip manualy betabeta run 2850 Reset Geiger: GeigerInit GeigerSetup 150 12:25 Start BETABETA run 2851. 19:40 Stop BETABETA run 2851. HV-GG: "OFF". R=6.98 / long.eff.peak=98.0% / t1+t2=52.6 (+1V) no noisy cells / noisy PM: 7/1/1/7 - HV - cr.3 b.7 ch.6 / no new mis. PM ( 57). 19:50 Start BETABETA run 2852. HV-GG: +1V and "ON". ********************************************************************** Date: 29.01.2004/Thursday Operator: I.Vanyushin ********************************************************************** 09:00 Stop BETABETA run 2852. HV-GG: "OFF". R=7.00 / long.eff.peak=98.4% / t1+t2=50.8 (-3V) no noisy cells / noisy PM: 7/1/1/7 - HV - cr.3 b.7 ch.6 / no new mis. PM ( 57). 09:01 laser_nemo2 run 2354 (O.K.). 19:25 laser_nemo2 2693 ************************************************************************ Date 06.05.2004 Operator Vladimir + xavier + christine ************************************************************************ !!! CALO 11:10 the cr1 bo3 is OFF (HV with probe = 5 V), slowcontrol : HV ~7V 11:15 Cr1 bo3 switched ON (ch24 first) : OK 11:40 Calo Run 3298 : all OK 11:53 laser_nemo2 2694 ADC 5 inches = 314.78 : too low Why laser run is too late after the ESD??? RunLog information. RUNLOG examples

18. Preliminary results of the calibration 11 • Exposition time is 1.03% less than in version 5. • DeltaT is not sufficient criterion to select the versions (v10 is bad but DeltaT is good). • For the same list of bb runs the acceptance is decreased on ~7-8% vs version 5.

19. Preliminary results of the calibration 11 Spectra’s shape did not change, event acceptance decreased on ~ 7%

20. 5 events are disappeared in energy sum tail > 2.7 MeV. They should be studied in the nearest future.

21. 1 event disappeared in energy sum tail.

22. 1 event disappeared in energy sum tail.

23. Events reduction factor (Nev_v11/Nev_v5) as a function of their vertex position. S/B=0 S/B=40 If removed PMs in version 11 are distributed isotropically in the detector (needs to be checked), then the results in the table would indicate the real reduce of the background events with vertexes near (but not on) the source foils. Then version 11 would be preferable to use…

24. Conclusion • Work on time calibrations is in progress. • There is the systematic error due to the TDC instability. But it is very hard to estimate its value. • To do: • PM TDC stability survey in interactive way in order to verify events over 2.7 MeV. • Try to find the indisputable criteria to prove that the version 11 is better than version 5. • Try to squeeze more the PM selection criteria. • The problem of the TDC(ADC) function seen before; • The time calibration procedure using laser data, is it possible to do better than using e data of 207Bi data?