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 1 st brick 5 are predicted as 2 nd brick 1 is predicted as 3 rd 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 W7 SIDE -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: Wall finding including the second brick: Brick finding efficiency: 1 brick extraction: bricks extraction: bricks extraction: 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 NCCCTotal Bricks assigned Bricks received in the labs Scanning started CS to brick connected Vertices located in the brick Passing through82230 Vertices in the dead material178 Upper limit in the event location NC: 91% CC: 95% Lower limit NC: 70% CC: 84% Dead material 8/369 = 2.2%

Vertex location as a function of time in Europe achieved ~ 90/month in October

Vertex location (all)

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 Missing segments make IP larger Important 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 Bari820,152 Bern1370,254 Bologna590,109 Frascati40,0074 Naples1330,247 Padova240,044 Roma40,0074 Salerno950,176 Bari0,167 Bern0,222 Bologna0,167 Naples0,222 Padova0,055 Salerno0,167 Initial value Current brick sharing

Event location in Europe (as of March 5th) Bari Bern Bologna Frascati Lyon Naples Padova Rome Salerno Total 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 Bari0,162 Bern0,271 Bologna0,117 Naples0,263 Salerno0,188 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 analysis First 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 fraction NCCCTotal Predictions for CS scanning 139 (19.3%) Found in CS84 (15.6%) Located in ECC 48 (13.0 %)322370