I. Kreslo, LHEP, Bern
Bern Scanning Laboratory
Hunting muonless interactions...
I. Kreslo, LHEP, Bern
I. Kreslo, LHEP, Bern
NC event 179312944
I. Kreslo, LHEP, Bern
muonless event 179312944 179312944;391;neut;2007-10-06 11:46:34;1;1;W25;R13;C25; 01011847 179312944;391;neut;2007-10-06 11:46:34;1;1;W25;R13;C24; 01011845 179312944;391;neut;2007-10-06 11:46:34;1;1;W25;R13;C26; 01011669 179312944;391;neut;2007-10-06 11:46:34;1;1;W25;R14;C25; 01012865 179312944;391;neut;2007-10-06 11:46:34;1;1;W25;R12;C25; 01008954
3 Bricks are developed
179312944 11847 09/10/07 1 0.22
179312944 11845 09/10/07 1 0.15
179312944 11669 09/10/07 1 0.14
I. Kreslo, LHEP, Bern
CS predictions
First step – standart: 6 prediction are found in CSD, - not found in any of three bricks.
Need for more sophisticated approach…
I. Kreslo, LHEP, Bern
Veto alignment (pl 57 – veto 58)
500 microns
Two alignments !! Veto was moved during exposure.
Is the situation with CSD the same?If yes => Search area=1x1mm
I. Kreslo, LHEP, Bern
Veto dublet deformations
Is the situation with CSD the same?If yes => Angular tolerance ~30 mrad.
I. Kreslo, LHEP, Bern
Pl 57 deformations
Z Distance CSD – P57Error up to 300 microns
I. Kreslo, LHEP, Bern
Full area scan
IP=300 microns, >3-fold-pre-vertexing
“Pre-vertexing” allows to limit number of SB pathes to 75 (~5%)
Emulsions 57,56,55 + CS0,CS1Full area scan
Total number of tracks not found in CSD: about 1300!
(No angular constraints)
I. Kreslo, LHEP, Bern
Scanback of pre-vertexed tracks
Initially 75 tracks, 32 stops, 28 stops to analyse (pl 3-53), 43 passing
No converging stopping tracks…..
I. Kreslo, LHEP, Bern
Totalscan around stops
I. Kreslo, LHEP, Bern
Visual check : SB path 4248
SB track
Smth. interesting
I. Kreslo, LHEP, Bern
Vertex found
Good vertex ! But there is a sign of incoming track (see prev. slide)
I. Kreslo, LHEP, Bern
Volume scan around vertex
Tracks are visible in veto => This is NOT a neutrino event, but HE cosmics reaction
577748
2938 1211450
I. Kreslo, LHEP, Bern
After scanback of ~1300 tracks two interesting vertices found
I. Kreslo, LHEP, Bern
After scanback of ~1300 tracks two interesting vertices found
I. Kreslo, LHEP, Bern
NC candidate : volume scanNo additional tracks related to vertex are found
2x2cm x 9 plates
I. Kreslo, LHEP, Bern
Check presence of tracks in VD (Veto Dublet)
1st alignment 2nd alignment
Pl 57 Pl 58 Pl 59 Pl 58 Pl 59
662 BT MT(8) - - -
762 BT - - MT(8) -
101 BT BT BT BT -
102 BT BT BT - BT
103 BT MT BT - -
104 BT BT BT - -
201 BT - - BT BT
202 BT BT - BT MT
Confirmed: NOT in VETO !
I. Kreslo, LHEP, Bern
NC candidate 1 : detector view
Hadronic shower CG fit
I. Kreslo, LHEP, Bern
NC candidate 1
Hits in TT correspond to possible interaction=> Likely NC event
I. Kreslo, LHEP, Bern
NC candidate 2 : detector view
I. Kreslo, LHEP, Bern
NC candidate 2
No hits, high IP => unlikely.
I. Kreslo, LHEP, Bern
NC candidates 1,2
Checked presence in the CSD – not found…. .
I. Kreslo, LHEP, Bern
Effect on CR density discussion...
If no CSD predictions found for one of reasons, then:
1300 tracks to follow => Not possible in 24h/brickStrong selection (maybe few% of total) still leads to fake events (3)Reduction of CR density by factor 5 would be very desirable…
I. Kreslo, LHEP, Bern
Predictions from LNGS => Low momentum shower?
• Volume scan 2x2cm 57 plates• VTX reconstruction with IP<50 microns, min Nseg=2:• 5189 2-prong vertices (!)• 86 3-prong (too many to check) (left as the last chance)• 7 4-prong (incoming tracks -> rejected)• 1 5-prong (all 2 seg tracks, high IP – rejected)
• VTX reconstruction with IP<50 microns, min Nseg=5:• 13 2-prong vertices, 2 correlated with prediction: #1 incoming track reconstructed with the gap of 4 plates, #2 incoming track out of volume (re-scanned bigger volume)
I. Kreslo, LHEP, Bern
Summary on the event search
1. Standart prediction search gave no consistent tracks in pl 57,56.2. Volume scan around predicted tracks => Some candidates, rejected for various
reasons.3. Fullarea scan with Veto-in cosmics: 1300 tracks to consider4. Pre-vertexing procedure applied, no converging tracks, however 28 stops. TotalScan
is done visual checks – done. 7-prong CR interaction found, rehearsal of vertex analisys is done on this interaction, all scanning tasks in fully automatic mode.
5. Scanback of all ~1300 tracks from pl57-55, not found in Veto is complete
6. One vertex from external interaction is found and confirmed : - NOT in VETO - YES in TT - NOT in CSD
Extract upstream brick?! Reasonable to say Yes.
Event is not found, but the strategy starts to develop.
I. Kreslo, LHEP, Bern
Prediction location
Location in pl 57DX=1mm
NO FOUND ? YES
Scanback withIC at CG of cluster
NO STOPS ? YES
Totalscan 5x5mmx10pl
1 PRONGS ? >1
Visual check
NO CONFIRMED ? YES
Scanforth to VETO
YES FOUND IN VD ? NO
I. Kreslo, LHEP, Bern
Scenario for muonless event location
NO CS TRACKS ? YES
NO Located ? YES
Prediction location
Volume scan 2x2cm57pl + VETO
around first TT cluster CG
Find all alignmentsErase tracks, present in VD
Pre-vertexing3 prong, IP<300microns
NO Located ? YES
Prediction location
e- Shower searchIn a volume (+VD!)
I. Kreslo, LHEP, Bern
Shower confirmation
Check BT in VETO
YES FOUND IN VD ? NO
Check BT in CSD ?
NO FOUND IN VD ? YES
I. Kreslo, LHEP, Bern
Muonless event location strategy
First picture of the algorithm becomes clear
Worked well for two events so far :
One CR and one neutrino (see next talk by C.Pistillo)
Very time consuming, but very precious (νμCC events,Tau-> e, Tau-h
channels) => firther optimisation (minimisation) is crucial.
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