1

NuFact’01

WG1 : Neutrino Oscillation PhysicsMay 24-30, 2001

An appearance experiment to search for - oscillations

in the CNGS beam CNGS1

Oscillation Project with Emulsion-tRacking Apparatus

May 25, Nagoya University M. Komatsu

2

The experimental technique

• Emulsion Cloud Chamber (ECC)– Emulsions for tracking, passive material as target– Basic technique works

• charmed “X-particle” first observed in cosmic rays (1971)• DONUT/FNAL beam-dump experiment: events observed

• m2 = (1.5 - 5) x10-3 eV2 ( SuperK) Mtarget ~ 2 kton of ECC

– large detector sensitivity, complexity– modular structure (“bricks”): basic performance is preserved

• Ongoing developments in the emulsion technique, required by the large vertex detector mass:

– industrially produced emulsion films– automatic scanning microscopes with ultra high-speed

Pb

Emulsion layers

1 mm

Experience with emulsions and/or searches : E531, CHORUS, NOMAD and DONUT

3

~ 10 m

The detector at Gran Sasso(modular structure, configuration with three “supermodules”)

spectrometerMagnetised Iron Dipoles

Drift tubes and RPCs

target and decay detectorEach “supermodule” is

a sequence of 24 “modules” consisting of - a “wall” of Pb/emulsion “bricks”- planes of orthogonal scintillator strips

scintillator strips

brick wall

module

brick(56 Pb/Em. “cells”)

8 cm (10X0)

supermodule

4

8 m

Target Trackers

Pb/Em. target

Electronic detectors select interaction brick

A “hybrid” experiment

Emulsion scanning vertex search

Extract selected brick  

Pb/Em. brick

8 cmPb 1 mm

Basic “cell”

Emulsion

decay search

spectrometer

e/ ID, kinematics ID, charge and p

(DONUT)

5

Origami packed ECC brick for OPERA

Origami packing = vacuum packing (1) Protection against light and humidity variations. (2) Keep the position between films and Pb plates. (3) Vacuum preserved over 10 years

10X0 ( 56 emulsion films ) 8kg for each brick

12.5cm

235k bricks for 3 supermodules

Similar packing was usedfor E531,CHORUS,etc. DONUT did not use thispacking then we had trouble.

6

Structure: OPERA ECC = DONUT ECC Material : Lead Iron

Better performance for physics analysis

has been detected in the DONUT

ECC hadron

Emulsion Cloud Chamber for detection

1mmFe plate

Emulsion film

7

The First detection in ECC • Iron-Emulsion ECC target

– 50cm x 50cm x 7cm(47 Iron plate : 2.7X0)– Topology, momentum and e-ID in ECC

• Beam– 3.5x1017 POT , Apr.-Sep. ‘97– Approximately 1,100 three flavor neutrino interactions – 785 events in target region.

• Data taking– 337 events located and 289 decay search done.– We are waiting faster scanning system for high multipli

city at TT events. • Tau and charm events

– 6 tau events– 2 charged and 2 neutral charms

8

6th tau event in DONUT ECC

cGeV

cGeV

cGeV

/208.09.18

/401.034.3

/132.077.7

7.2079.6

16.171.0

62.396.1

9

Momentum measurement

in DONUT ECC

Momentum measurementby multiple scattering

Consistent result withmomentum measuredby spectrometer.

10

• Developed in DONUT analysis– 3D tracking in emulsion using fast automatic scanning

system(UTS)– Reconstruct all tracks recorded in emulsion

• Application in CHORUS “Phase II”– 1.5mm x 1.5mm x 6.3mm(8 plates)– Tau search(0 events) and charm physics– Offline event reconstruction and event selection

• Data taking– 13,000 events/month (440 events/day)– Data taking finished for 107,590 events.

NETSCAN in CHORUS Phase II

We have started our phase II analysis with the aim of reaching our design sensitivity of P= 10-4

11Nov. ‘99

CHORUS Phase II data taking

12

Netscan (Chorus phase II)

1.5 mm

1.5 mm

All track segments(6k hits)

8 plates overlappe

d

6.3 mm

Yellow : UpstreamRed : Downstream

13

1.5 mm

1.5 mm

Small impact

parameter

Netscan (Chorus phase II) Yellow : Upstream

Red : Downstream

CC D0

14

Charm search in CHORUS

NETSCAN • 108k Data sets are ready for analysis• Offline charm selection

– 23,244 CC events done– ~900 events selected (~4%)– 568+ charms (manual confirm is going on)

• ~70% purity for charm• ~15% hadronic re-interactions, electron pairs and other int.• The other ~15% are junk.

• Preliminary charm detection efficiency– Selection require TT track reconstruction

• Reconstruction efficiency for hadron tracks are 47-64%– 26,63,58 and 75% for 1,2,3 and 4 prong decays

• Lower efficiency for D+ and c+ due to long and short life tim

e.

Preliminary

15

• Emulsion readout system– ‘94 : We decided to apply full automatic

scanning for CHORUS analysis.• Emulsion became “Tracking detector”.

– ‘96 : ECC for DONUT target• Pure tracking device

– ‘98 : Establish “NETSCAN”• Current readout system “UTS” make us possible to

perform volume scanning.

• These changes were driven by faster emulsion readout system.

• OPERA needs x20 faster readout system

The key technology for OPERA

16

S-UTS Scanning speed: 20cm2/h 20 faster than the current system (UTS)

S-UTS

‘94 ‘96 ‘98 ‘01 NTS UTS S-UTS

Will be realized by Fast CCD camera (3 k frames/sec) Continuous movement of the X-Y stage Z movement controlled by piezo actuator

late summer 2001 first S-UTS

17

Emulsion Scanning Lab in Nagoya

Upgraded for OPERA

CHORUS, DONUT,OPERA and R&D for next generation

18

Interactions with 1.8 kton target x 5 years

~ 32000 NC+CC

~ 240 CC

for SuperK best fit : sin2 2 = 1 m2 = 3.2x10-3 eV2

The CNGS beam

Shared SPS operation 200 days/year 4.5x1019 pot / year

Nominal beam

( m-2 / pot) 7.45x10-9

CC / pot / kton 5.44x10-17

< E > ( GeV ) 17

(e + e) / 0.85 %

/ 2.0 %

prompt negligible

19

AnalysisstepsBrick finding

Trigger

Vertex location

Decay search“long” or “short”

decays

decay mode

Kinematics

events

Classifyas / e

yes

no

Electronic detectors

Emulsions

Emulsions

Electronic detectors

eat 1ry vtx ? CHORUS

DONUT

20

Summary of detection efficiencies(in % and including BR)

Decay mode DIS long QE long DIS short Overall*

e 3.0 2.6 1.3 3.7 2.7 2.8 - 2.7 h 2.2 2.8 - 2.3Total 8.0 8.3 1.3 8.7

* weighted sum of DIS and QE events

Channels considered in the Progress Report:

e (DIS+QE, long) (DIS+QE, long) Overall efficiency

21

Expected background events (5 years data taking)

e h Total

Charm production 0.15 0.03 0.15 0.33e CC and 0 0.01 - - 0.01Large scattering - 0.10 - 0.10Hadron reinteractionswith kink topology

- - 0.10 0.10

SubTotal 0.16 0.13 0.25 0.54

Charm production 0.03 - - 0.03e CC and 0 «0.01 - - «0.01

SubTotal 0.03 - - 0.03

Total 0.19 0.13 0.25 0.57

Lo

ng

dec

ays

Sh

ort

de

cays

22

m2 = 1.2x10-3 eV2

at full mixing

sin2 (2) = 6.0x10-3

at large m2

(average 90 % CL upper limit for a large number of exp.ts in the absence of a signal)

5 years

3 years

Sensitivity

5 years data taking

23

• Full mixing

• 5 years with shared SPS operation

(2.25x1020 pot)

• Average target mass = 1.8 kton

(accounting for mass reduction with time, due to brick removal for analysis)

Expected events

events

decay m2 (10-3 eV2 ) b.g.1.5 3.2 5.0

e 1.7 7.7 18.5 0.19

1.3 5.7 13.8 0.13

h 1.1 4.9 11.8 0.25

Total 4.1 18.3 44.1 0.57

m2 (eV2)

eve

nts

e

xpe

cte

d in

5 y

ea

rs

(log

scal

e)

24

Summary and conclusionsfor OPERA

• Experience with E531, CHORUS, NOMAD and DONUT

• OPERA : appearance and appearance and mm2 2 measurement at CNGSmeasurement at CNGS

• Basic technique (ECC) works; preserved by modularity Basic technique (ECC) works; preserved by modularity

• Large detector sensitivity, complexity

•Ongoing developments in the emulsion technique:– industrially produced emulsion films– automatic scanning microscopes with ultra high-speed

• The sensitivity covers the SuperK range; very low b.g.

• Start data taking in 2005

25

Future Emulsion experimentfor neutrino factory

• ECC + fast readout system– It is possible to construct very massive detector.

ECC performance preserved by modularity for large detector.

– Using magnetic field: ID• Emulsion works even in strong magnetic field.

tee and ,,,,

ECC is ready for neutrino factory

26

Industrially mass-produced emulsion film

Surface protection by gelatin layerfor Pb plate contact

Products by Fuji Film Co. Suitable for mass production: < 2 years for production for OPERA (13.6M films)Precise mechanical size : emulsion layer thickness (~ 1 m accuracy)

50m emulsion layer

200m base

50m emulsion layers

200m base

27

Cross sectional view of an emulsion layer

30grains/100mgrain diameter ~ 0.6m

Ag grain after development

dx

= 0.06mCompton Electron

Fog

M.I.P. Track

100m

M.I.P. Track

intrinsic tracking accuracy

Intrinsic tracking resolution of the emulsion

28

Electron identification in ECC brick

2h

2e

Shower detected

TEST experiment at CERN PS

Electron

Had

ron

(1) Different energy loss by multiple scattering E(x)=E0e (-x/X0) for electrons 2

e

E(x)=E0(1-(dE/dx)x) for hadrons 2h

(2) Detection of electromagnetic shower Requires low background track density controlled fading Sensitive to electrons close to the Pb critical energy

5X0

1 mm

5 cm

29

detection and energy measurement in ECC brick

Improvement for missing PT analysis h decay mode

charged particle + 0 ( )

M = 157 24 MeV/c2

Test experiment at CERN PS

8 GeV/c - interaction in OPERA type ECC

Example of detection in DONUT( Fe not suited for energy measurement)

-

s from 0