1 RUN 2008 OPERA events: Status Report M. Ieva on behalf of Bari Emulsion Lab OPERA Collaboration Meeting, April 1st - 5th, 2009

2 Summary tables (updated to March 28th) CCNCTotal Received bricks (events)67 (65)13 (12)80 (77) Analysed bricks Muon found in CS Muon not found in CS Black CS Analysed bricks39244 At least 1 SB track Vertex found32152 Passing-through400 Pending events342 CS re-analysis requested 050 Analysed bricks13 At least 1 SB track 12 Vertex found9* Passing-through2 Pending events1 CS re-analysis requested 1 * 2/9 single hadron stops

3 HF

4 Overview of pending events Black CS B (tape, no µ candidate, still under investigation) B (tape, SB + TS done, working on reconstruction) NC events B B (tape, HF, SB running) CC events with µ B (tape, possible edge-out, under investigation ) B (tape, HF > 14, problems in track reconstruction due to HF) CC events no µ B (HF, details in next slides) B (1/1 LNGS preds connected, only 1 seg (film 57), TS done, 2 µ cands to be validated in CS ) B (tape, SB running ) B (tape, SB running ) Total: 10 B (HF, µ stop under investigation ) details in next slides

5 Event (CC) – Brick PENDING

6 1/2 LNGS predictions connected, 3 segments only (55-57), stop confirmed by TS and visual inspection TO DO: search for possible muon candidates in TS volume; re-analysis/measurement of CS

7 Event (CC) – Brick (black CS) green track: sx = sy = SB and TS done, muon stop in film 15 still under investigation PENDING

8 Event (CC) – Brick (black CS) GS in films 52 ÷ 57, up to now no µ candidates confirmed, still working on reconstruction (very marginal event!) PENDING

9 Event (NC) – Brick out of 4 LNGS predictions successfully connected LOCATED!

10 Scan back “red” track track stops in film 49 “black” track stops in film 57 TS volume 1 measured area ~ 1cm 2 in 11 films (47 ÷ 57): track stop confirmed in film 49 by visual inspection the track is a e+e- pair from  conversion observed in plastic base of film 49. measured area ~ 1cm 2 in 12 films (37 ÷ 46) Volume scan data analysis (films 37 to 57) Total nr of vertices:61 (I.P.  20  m, DZ < 3900  m) No charged primary track: 10 - at least two tracks with nseg ≥ 3, DZ < 3000  m0 - at least one track with nseg ≥ 3, DZ < 3000  m3 - slopes of the line connecting vertex and e+e- pair  TS volume 2

11 TS volume 3 measured area ~ 9 cm 2 in 10 films (27 ÷ 36) Final volume scan data analysis (films 27 to 57) 5-prongs vertex in base of film 29 i.p. 6.5  m X = 27329, Y =78650 e+e- pair from  conversion from LNGS pred (film 49)

12 tracks 1495 and 2697 searched for in CS for vertex validation track 1495 found, VERTEX CONFIRMED! TrackusxusyIp (µm) …from vertex recostruction all tracks confirmed by visual inspection and followed down TrackStop Film

13 Some nice events…

14 kink 3-prong vertex lead plate between films 32 and 33 i.p. 2.6  m daughter: sx= sy=0.281 parent: sx= sy=0.048 lead plate between films 26 and 27 i.p. 3.8  m the parent track was followed back and found to be a passing-through track Event (CC) – Brick out of 7 LNGS predictions successfully connected (no muon candidate) p1, p3, p5 are passing-through p2 stops in film 51 p6 stops in film 57 Scan back p4 stops in film 34 TS volumes Volume 1, measured area ~ 1cm 2 in 11 films (29 ÷ 39) Volume 2, measured area ~ 1cm 2 in 11 films (22 ÷ 32) General scan of films 1 ÷ 4 (~ 2 cm 2 /film) searching for muon candidates (angular selection : ± 40 mrad w.r.t. ele preds) found 1 µ candidate extrapolated to CS and confirmed by visual inspection upstream brick extracted

15 Upstream Brick CS-brick connection (no muon candidate) P ,0390, P slopes similar to charged primary track of 3 prong vertex in brick 18630: sx = , sy = slopes similar to one of passing-through tracks in brick : sx = , sy = 0.08 clear signal of track convergence in most downstream films, direct TS volume primary vertex lead plate between films 55 and 56 i.p  m X = , y =11995 muon candidate p1 lead plate between films 55 and 56

16 stop in film 55 Scan back TS results measured area ~ 1cm 2 in 11 films (47 ÷ 57) the parent track was followed back and found to be a passing-through track lead plate between films 53 and 54 i.p  m X = 99668, y =7725 LNGS preds Event (NC) – Brick LNGS predictions successfully connected

17 tracks convergence was checked, predicted vertex position in lead plate between films 41 and 42, estimated i.p. ~ 60  m SB skipped, Direct TS performed Muon candidate followed down to film 57 and confirmed in CS by visual inspection primary vertex lead plate between films 41 and 42 i.p. 4.9  m the parent track was followed back up to film 26 where it was found to stop secondary vertex additional TS performed around parent track stop i.p. 1.0  m lead plate between films 25 and 26 parent track muon candidate primary vertex Event (CC) – Brick LNGS predictions successfully connected (no muon candidate)

18 Brick scanning and analysis chain 1.CS to Brick connection:  pointed scanning (3x3 fov) around each CS pred  general scan (~16 cm 2 ) for bricks with black CS  visual check of found candidates 2.Scan-Back:  with 2 or 3 or 4 lateral-marks depending on event type and fog density  in case of problems, visual check of stopping point 3.Total Scan:  until middle of March, scanning of 1cm 2, 5 films up + 5 films down  now, 1cm 2, 5 films up + 10 films down 4.Volume reconstruction and analysis 6.Quality check 7. Data publication to Central DB up to now, attention mainly devoted to event location; now, re-analysis of located events for decay search starting 0. Fog and thickness measurement 5.Vertex confirmation  visual inspection of vertex tracks in 2 films up + 2 films down

19 Status of data publication up to now, 44 scanning processes (25 bricks) and 17 event reconstructions published to OPITA - list of published reconstructions: - list of published processes:

20 Lab news… Software: this week stop of scanning activity for software upgrade (chrysalis version) tuning of scanning parameters for HF bricks in progress Hardware: 1 plate changer installed and working on 1 microscope, tests with DB planned after software upgrade completion.

21 Conclusions Planned: momentum measurement of all tracks of located neutrino events with low energy muons decay search for the whole sample of our neutrino events Scanning of Run 2008 bricks in progress Located neutrino events up to now: 58 (49 CC + 9 NC)