1. CS scanning @ LNGS Current status and perspectives

2. 2 Apr 2009OPERA General Meeting in Ankara2 CS scanning protocol 1.CSd are scanned according to fog level – different cuts are applied for the two samples 2.Double base-track search (STANDARD) 3.Manual check validation 4.Event validation 5.In case of null (double bt) result: (MICRO) – Compton alignment – ¾ search 6.In case of null result after ¾ search: – we rescan the event according to its topology we expect to do it in 10% QE events (see Natalia’s talk) 7.request second brick and send the first back to detector (only after positive result of the second) 8.Support to the labs when the event is not located in ECC Automatic

3. 2 Apr 2009OPERA General Meeting in Ankara3 Current situation Currently using up to 7 microscopes for the scanning + 1 devoted to manual check 24/7 shift – coverage was around 85% before Christmas, significantly reduced afterwards Scanning Station is able to digest 50÷60 CSd/week in this condition SySal2000 (VS6, ST8.5) – Improvements excepted from the release made by Cristiano, tests foreseen

4. 2 Apr 2009OPERA General Meeting in Ankara4 2008 run current numbers Updated up to March 31 st, 2009 From July 2nd, 2008: we received 88 development batches @LNGS CS DEVELOPED971 EVENTS826 CS MEASURED809 BRICK DEVELOPED (including ¾) 514 BLACK CS38 BRICK BACK9 DEVELOP NO COSMICS (new flag implemented) 4

5. 2 Apr 2009OPERA General Meeting in Ankara5 Analysis of the second extracted brick to evaluate the improvement in the location rate Events with a 2 nd brick extracted145 passing through track in 1 st brick19 1 st brick still under analysis20 1 st brick developed14 Both CS black2 Not measured…yet21 2 nd CS scanned68 2 nd brick developed31

6. 2 Apr 2009OPERA General Meeting in Ankara6 Preliminary results MeasuredDevelopedRatio (%) 1 st brick720478 66.4  1.8 2 nd brick6831 45.6  6.0 1 st & 2 nd brick 81.7  2.2 These estimations are VERY PRELIMINARY for the following reasons: some manual check not yet concluded some event validation not yet concluded 3/4 search not yet applied in case of null double base-track result So the value has to be considered as a lower limit

7. 2 Apr 2009OPERA General Meeting in Ankara7 “No results” events CCNC total events662165 -> events with at least one CSd measured584140 -> NO_RESULT events19881 --> not measured NO_RESULT events4822 --> measured NO_RESULT events15059 ---> wrong/complicated measured NO_RESULT events3048 ---> measured NO_RESULT events with candidates624 ----> measured NO_RESULT events near edge with candidates3150±6%4100% ---> measured NO_RESULT events with no candidates587 ----> measured NO_RESULT events near edge with no candidates3560±6%571±17% -> BLACK/other events363 -> CS_CAND_OK_DEVELOP events42881 --> CS_CAND_OK_DEVELOP events near edge14534±2%3341±5%

8. 2 Apr 2009OPERA General Meeting in Ankara8 CS scanning trend All CSd with fog<20 have been measured at least once, the analysis has been completed on a sample of events (see Natalia’s talk) New events are coming and the analysis on old events must be completed

9. 2 Apr 2009OPERA General Meeting in Ankara9 Black CS 1154 is black!

10. 2 Apr 2009OPERA General Meeting in Ankara10 High-fog CS scanning N (Fog > 10) = 114 (13.1 %) N (Fog > 20) = 51 (5.9 %) N (Fog > 30) = 21 (2.4 %) Current protocol: use ScanGrid when Fog > 10 grains/µm 3

11. 2 Apr 2009OPERA General Meeting in Ankara11 Estimates from the previous slide The scanning rate is 50÷60 bricks/week, enough to follow the extraction/development rate  to be doubled for 2009 run (including second brick extraction) The success rate ~ 60% has been slightly improved  ¾ routinely applied but still lengthy especially because of manual checks  rescanning

12. 2 Apr 2009OPERA General Meeting in Ankara12 Scanning speed Standard scanning ScanGrid Data from 7 microscopes, 2 microscopes are used with ScanGrid For the low fog CS, the nominal speed is affected by the reduction of scanning thresholds Scanning speed is strongly affected by fog level ScanGrid will be extensively used. Increasing computing power is planned: an upgrade of the LNGS Scanning Station is on going cm2/h

13. 2 Apr 2009OPERA General Meeting in Ankara13 CS scanning data quality notch

14. 2 Apr 2009OPERA General Meeting in Ankara14 CS track multiplicity

15. 2 Apr 2009OPERA General Meeting in Ankara15 CSd-TT comparison: NC events Nearest CS track with respect to the centroid of the electronic prediction Accuracy ~ 1 cm in both projections

16. 2 Apr 2009OPERA General Meeting in Ankara16 Scanning area per event CC NC

17. 2 Apr 2009OPERA General Meeting in Ankara17 Fading effect in CSd

18. 2 Apr 2009OPERA General Meeting in Ankara18 Fading effect in CSd 0<Days<30 30<Days<60 Days>90 60<Days<90

19. 2 Apr 2009OPERA General Meeting in Ankara19 Estimation of veto track contamination Tracks crossing CS are provided from Russian reconstruction, MORE statistics is NOW available All tracks crossing the CSd scanned @ LNGS have been compared with the scanned and validated tracks in CSd (  2600) One-to-one pairs has been made using a  2 constructed using the tolerances of the reconstructed muons

20. 2 Apr 2009OPERA General Meeting in Ankara20 Tolerances used in the  2 definition ~ 8 mm ~ 7 mm ~ 17 mrad ~ 16 mrad

21. 2 Apr 2009OPERA General Meeting in Ankara21 Veto track selection 420 scanned tracks belong to a different event (90% C.L) Lower limit on candidate contamination: 420/2600 = ~ 15%

22. 2 Apr 2009OPERA General Meeting in Ankara22 Some rock muons Track 16 is our muon candidate for the event (  2 = 0.89) Track 2 (  2 = 0.17) and 10 (  2 = 0.61) are likely two rock muons

23. 2 Apr 2009OPERA General Meeting in Ankara23 Brick developed with a veto track Track 6 (our muon candidate!) with  2 = 0.38 is like to be a veto track

24. 2 Apr 2009OPERA General Meeting in Ankara24 Improvements and conclusions Shift coverage 24/7 (+15%) – Increase number (+3 from Lyon) of microscope (+43%) – Increase scanning speed (+13%) – Total rate increase: + 85% Data quality improvements on going – Test new SySal2000, released by Cristiano – Procedure improvements – Compton alignment and ¾ search – Reduce the number of manual checks by using dedicated data taking (more frames, image analysis,…) under study Minimize the contamination of cosmic ray and rock muon tracks to improve the purity of the selection