I. Kreslo, LHEP, Bern Bern Scanning Laboratory Hunting muonless interactions...

I. Kreslo, LHEP, Bern

NC event

I. Kreslo, LHEP, Bern muonless event ;391;neut; :46:34;1;1;W25;R13;C25; ;391;neut; :46:34;1;1;W25;R13;C24; ;391;neut; :46:34;1;1;W25;R13;C26; ;391;neut; :46:34;1;1;W25;R14;C25; ;391;neut; :46:34;1;1;W25;R12;C25; Bricks are developed /10/ /10/ /10/

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 – P57 Error 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,CS1 Full 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

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 scan No additional tracks related to vertex are found 2x2cm x 9 plates

I. Kreslo, LHEP, Bern Check presence of tracks in VD (Veto Dublet) 1 st alignment2 nd alignment Pl 57Pl 58Pl 59Pl 58Pl BTMT(8) BT--MT(8)- 101 BT BT BTMTBT 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/brick Strong 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: 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 consider 4.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 57 DX=1mm NO FOUND ? YES Scanback with IC 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 2x2cm 57pl + VETO around first TT cluster CG Find all alignments Erase tracks, present in VD Pre-vertexing 3 prong, IP<300microns NO Located ? YES Prediction location e- Shower search In 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 ( ν μ CC events,Tau-> e, Tau-h channels) => firther optimisation (minimisation) is crucial.