1

RUN 2008 OPERA events:Status Report

M. Ievaon behalf ofBari Emulsion Lab

OPERA Collaboration Meeting, April 1st - 5th, 2009

2

Summary tables (updated to March 28th)

CC NC Total

Received bricks (events) 67 (65) 13 (12) 80 (77)

Analysed bricks 67 13 80

Muon found in CS

Muon not found in CS

Black CS

Analysed bricks 39 24 4

At least 1 SB track

39 19 3

Vertex found 32 15 2

Passing-through 4 0 0

Pending events 3 4 2

CS re-analysis requested

0 5 0

Analysed bricks 13

At least 1 SB track

12

Vertex found 9*

Passing-through 2

Pending events 1

CS re-analysis requested

1

* 2/9 single hadron stops

3

HF

4

Overview of pending events

Black CSB1009968 (tape, no µ candidate, still under investigation)

B1005212 (tape, SB + TS done, working on reconstruction)

NC events B1051633+B1052615 (tape, HF, SB running)

CC events with µ

B1083436 (tape, possible edge-out, under investigation )

B1121253 (tape, HF > 14, problems in track reconstruction due to HF)

CC events no µ

B1120658 (HF, details in next slides)

B1012652 (1/1 LNGS preds connected, only 1 seg (film 57), TS done, 2 µ cands to be validated in CS )

B1129069 (tape, SB running )

B1092404 (tape, SB running )

Total: 10

B1117209 (HF, µ stop under investigation )

details in next slides

5

Event 229132071 (CC) – Brick 1120658 PENDINGPENDING

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 236770829 (CC) – Brick 1005212 (black CS)

green track:sx = 0.051sy = 0.006

SB and TS done, muon stop in film 15

still under investigation

PENDINGPENDING

8

Event 234996823 (CC) – Brick 1009968 (black CS)

GS in films 52 ÷ 57, up to now no µ candidates confirmed, still working on reconstruction (very marginal event!)

PENDINGPENDING

9

Event 235109819 (NC) – Brick 1018966

2 out of 4 LNGS predictions successfully connected

LOCATED!

LOCATED!

10

Scan back

“red” track track stops in film 49“black” track stops in film 57

TS volume 1measured area ~ 1cm2 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 ~ 1cm2 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 m 0

- at least one track with nseg ≥ 3, DZ < 3000 m 3

- slopes of the line connecting vertex and e+e- pair 0.5 0

TS volume 2

11

TS volume 3

measured area ~ 9 cm2 in 10 films (27 ÷ 36)

Final volume scan data analysis (films 27 to 57)

5-prongs vertex inbase of film 29

i.p. 6.5 mX = 27329, Y =78650

e+e- pair from conversion

from LNGS pred(film 49)

12tracks 1495 and 2697 searched for in CS for vertex validationtrack 1495 found, VERTEX CONFIRMED!

Track usx usy Ip (µm)

2692 0.120 0.037 12.8

1495 - 0.07 0.169 2.87

2684 - 0.248 - 0.110 4.73

2697 - 0.029 0.113 5.98

747 0.164 0.292 28.0

…from vertex recostruction

all tracks confirmed by visual inspection and followed down

Track Stop Film

2692 53

1495 57

2684 52

2697 55

747 37

13

Some nice events…

14

kink 3-prong vertex

lead plate between films 32 and 33i.p. 2.6 m

daughter: sx=-0.012 sy=0.281parent: sx=-0.131 sy=0.048

lead plate between films 26 and 27i.p. 3.8 m

the parent track was followed back and found to be a passing-through track

Event 227917085 (CC) – Brick 1018630

6 out of 7 LNGS predictions successfully connected (no muon candidate)

p1, p3, p5 are passing-through p2 stops in film 51p6 stops in film 57

Scan back

p4 stops in film 34

TS volumes

Volume 1, measured area ~ 1cm2 in 11 films (29 ÷ 39)

Volume 2, measured area ~ 1cm2 in 11 films (22 ÷ 32)

General scan of films 1 ÷ 4 (~ 2 cm2/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 1036025

CS-brick connection (no muon candidate)

P1 110320.95 11984.67 - 0,039 0,033 110313.55 12027.21 - 0.037 0.031

P2 110268.2 12056.14 - 0.056 0.105

110317.0 12041.46 - 0.029 0.099

slopes similar to charged primary track of 3 prong vertex in brick 18630: sx = - 0.038, sy = 0.063

slopes similar to one of passing-through tracks in brick 18630 : sx = - 0.02, sy = 0.08

clear signal of track convergence in most downstream films, direct TS volume

primary vertexlead plate between films 55 and 56

i.p. 0.84 mX = 110363, y =11995

muon candidatep1

lead plate between films 55 and 56

16

stop in film 55

Scan back

TS results

measured area ~ 1cm2 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 54i.p. 33.2 m

X = 99668, y =7725

LNGS preds

Event 234531427 (NC) – Brick 1051633

2 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 42i.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 mlead plate between

films 25 and 26 parent track

muon candidate

primary vertex

Event 230771147 (CC) – Brick 1055609

2 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 cm2) 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 1cm2, 5 films up + 5 films down now, 1cm2, 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)