Emulsion scanning: present status and plans for the coming run

Giovanni De Lellis

CS scanning

CS scanning at LNGS

Improvements in the Compton alignment of CS

Tagging of CS tracks to reject physics background

Analysis of the 2nd extracted brick

• Sample of 65 analyzed second bricks• 29 with a positive result after CS scanning and analysis• 13/29 were actually 2nd extracted according to the

probability map• 4/29 are now the 1st predicted brick according to the

new version of the software (mu-shower, …) • The remaining 12/29 were extracted according to the

scanning results and display of electronic detector hits• With the software version (not yet available in the

Analysis follower) we have 20/29 events among the first and second most probable brick

Brick finding

• Including 4 events found with new software the finding rate is 17/65 = 26±5% brick finding with 2 bricks 12 ~ 75%

• Including new software release (not yet available on the analysis follower) 20/65 = 31% 12 ~ 77%

• While currently (29/65) is 12 ~ 81%

A look at the 12 events with the algorithm developed by the Dubna group

• 5 are predicted as 1st brick • 5 are predicted as 2nd brick• 1 is predicted as 3rd brick• 1 is wrongly predicted

1st brick according to Dubna algorithm

R11 C24 W11

R11 C24 W12

2nd brick according to Dubna algorithm

R35 C11 W10

R36 C11 W9

Wrongly predicted also by the Dubna algorithm

R17 C26 W6 SIDE -1

R17 C26 W7SIDE -1

What about the other 17 events?

• 10 are 1st brick

• 5 are 2nd brick

• 1 is 3rd, 1 is wrong

15 are among the 2 most probable

25/29 = 86% are among the 2 most probable

Finding efficiency with the Dubna algorithm on already located events

• Number of processed events: 317 located events

• Wall finding efficiency: 0.880126• Wall finding including the second brick: 0.996845

• Brick finding efficiency:

• 1 brick extraction: 0.788644 250• 2 bricks extraction: 0.962145 55• 3 bricks extraction: 0.977918 5

• Number of extracted bricks: 375• Number of not found bricks: 7

Joint effort for brick finding

• Set up a group with the involved people from scanning (Giovanni, Sato, Luillo) and electronic detector reconstruction (Dario, Anselmo, Antoine, Artem, Sergei)

• Further studies on already located events to define a strategy for extraction

Summary of the event location in Europe

NC CC Total

Bricks assigned 84 455 539

Bricks received in the labs 81 425 506

Scanning started 78 413 491

CS to brick connected 71 391 462

Vertices located in the brick 48 322 370

Passing through 8 22 30

Vertices in the dead material 1 7 8

Upper limit in the eventlocation

NC: 91%CC: 95%

Lower limitNC: 70%CC: 84%

Dead material8/369 = 2.2%

Vertex location as a function of timein Europe

0

100

200

300

400

500

600

01-giu 21-lug 09-set 29-ott 18-dic 06-feb 28-mar 17-mag

Assigned

Received

Located in ECC

Located + pt

achieved ~ 90/month in October

Vertex location (all)

0

100

200

300

400

500

600

700

800

900

1000

01-giu 21-lug 09-set 29-ott 18-dic 06-feb 28-mar 17-mag

Assigned

Located

Task of the scanning lab• Event location (priority)

– CS to brick connection– Track scan-back or direct vertex search– Vertex confirmation by volume scan (11 plates)– µ finding for CC events– matching of emulsion tracks with TT – for NC events, the primary VTX is defined by the most upstream stopping

point important to check TT hits

• Decay search– Measurement of all track segments in the plate immediately downstream of

the vertex (important to improve the impact parameter determination)– Topological reconstruction– Daughter tracks of secondary vertices (when neutral) to be followed down

for CS matching – Simulation needed to check the long flight charm efficiency (accounting for

the track inefficiency) and possibly enlarge the scanning volume

• Event publication

IP reconstruction

Pb Pb

Missing segments make IP largerImportant to measure the closest segment

µ IP

CS and brick assignment to the labs

• CS are shared among Europe and Japan in equal parts

• Bricks are shared among Europe and Japan in equal parts at the moment

• Within Europe there is a dynamical approach with an initial value computed according to the number of microscopes

Dynamical approach in the brick assignment in Europe

Initial brick assignment

Bari

Bern

Bologna

Naples

Padova

Salerno

Current sharing

Bari

Bern

Bologna

Frascati

Naples

Padova

Roma

Salerno

Bari 82 0,152

Bern 137 0,254

Bologna 59 0,109

Frascati 4 0,0074

Naples 133 0,247

Padova 24 0,044

Roma 4 0,0074

Salerno 95 0,176

Bari 0,167

Bern 0,222

Bologna 0,167

Naples 0,222

Padova 0,055

Salerno 0,167

Initial value

Current bricksharing

Event location in Europe (as of March 5th)

Bari 12 67 12 60 7 44 2 6 0 0 82

Bern 21 110 20 97 13 78 2 5 1 1 85

Bologna 10 49 10 49 3 32 0 0 0 1 61

Frascati 0 3 0 3 0 2 0 0 0 0

Lyon 1 0 1 0 1 0 0 0 0 0

Naples 21 109 19 92 9 71 2 7 0 3 83

Padova 4 20 4 20 3 16 0 0 0 0 79

Rome 0 3 0 2 0 1 0 0 0 0

Salerno 14 80 12 71 7 49 2 5 0 2 78

Total 83 441 78 394 43 293 8 23 1 7

Lab Assigned Received Located Passing Dead mat MF(%)

MF = (Located + passing through + dead material)/Received

Frascati and Rome started recently, statistics is not enough yet

Current assignment fractions

Bari 0,162

Bern 0,271

Bologna 0,117

Naples 0,263

Salerno 0,188

Current fractions

Bari

Bern

Bologna

Naples

Salerno

The fractions are revised periodically (every 1-2 months)The expected rate is 80 90%

If lower reduce to restore the expected rate (lab overloaded)If above increase to speed up the analysis

Continuous feedback between CS and brick analysisFirst reconstruction from CS double

base-track predictions New predictions from CS with the

¾ method

Vertex in ECC

Additional scanning activities for Monte Carlo validation

• Collect a sample of CC events (fully reconstructed) to check the Monte Carlo event simulation

• Our ultimate goal is to collect ~ 1000 events • Medium term goal: ~200 events by the end of this year • Start with the calibration for momentum measurements

– low energy µ for independent measurements and cross-calibration– event selection is ongoing (~30 events estimated…)

• Then, measure primary tracks– select only upstream events on average ~40 films to be scanned + event

analysis 2 days/event (rough estimation) • Scan-forth of all tracks attached to the primary vertex done at

same time of momentum measurement• For scan-forth measurements already collected need

momentum measurement for Pt analysis

Track multiplicity at primary vertex

QE-like events

Spectrometer momentum

Scattering angle

Transverse momentum

0µ fractionNC CC Total

Predictions for CS scanning

139 (19.3%) 582 721

Found in CS 84 (15.6%) 455 539

Located in ECC

48 (13.0 %) 322 370