bern scanning laboratory

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.