2 Apr 2009 OPERA General Meeting in Ankara 1

CS scanning @ LNGS

Current status and perspectives

2 Apr 2009 OPERA General Meeting in Ankara 2

CS scanning protocol1. CSd are scanned according to fog level

– different cuts are applied for the two samples

2. Double base-track search (STANDARD)3. Manual check validation4. 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

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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 reducedafterwards

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

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2008 run current numbers• Updated up to March 31st, 2009• From July 2nd, 2008: we received 88 development

batches @LNGS

CS DEVELOPED 971EVENTS 826CS MEASURED 809BRICK DEVELOPED (including ¾) 514

BLACK CS 38BRICK BACK 9DEVELOP NO COSMICS (new flag implemented) 4

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Analysis of the second extracted brick to evaluate the improvement in the location rate

Events with a 2nd brick extracted 145

passing through track in 1st brick 19

1st brick still under analysis 20

1st brick developed 14

Both CS black 2

Not measured…yet 21

2nd CS scanned 68

2nd brick developed 31

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Preliminary resultsMeasured Developed Ratio (%)

1st brick 720 478 66.4 1.82nd brick 68 31 45.6 6.01st & 2nd 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

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“No results” eventsCC NC

total events 662 165

-> events with at least one CSd measured 584 140

-> NO_RESULT events 198 81

--> not measured NO_RESULT events 48 22

--> measured NO_RESULT events 150 59

---> wrong/complicated measured NO_RESULT events 30 48

---> measured NO_RESULT events with candidates 62 4

----> measured NO_RESULT events near edge with candidates 31 50±6% 4 100%

---> measured NO_RESULT events with no candidates 58 7

----> measured NO_RESULT events near edge with no candidates 35 60±6% 5 71±17%

-> BLACK/other events 36 3

-> CS_CAND_OK_DEVELOP events 428 81

--> CS_CAND_OK_DEVELOP events near edge 145 34±2% 33 41±5%

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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

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Black CS

1154 is black!

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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/µm3

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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

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Scanning speedStandard scanningScanGrid

• 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

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CS scanning data quality

notch

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CS track multiplicity

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CSd-TT comparison: NC events

Nearest CS track with respect to the centroid of the electronic predictionAccuracy ~ 1 cm in both projections

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Scanning area per event

CC NC

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Fading effect in CSd

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Fading effect in CSd

0<Days<30 30<Days<60

Days>9060<Days<90

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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

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Tolerances used in the 2 definition~ 8 mm ~ 7 mm

~ 17 mrad~ 16 mrad

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Veto track selection

420 scanned tracks belong to a different event (90% C.L)Lower limit on candidate contamination: 420/2600 = ~ 15%

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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

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Brick developed with a veto track

Track 6 (our muon candidate!) with 2 = 0.38 is like to be a veto track

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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