OPERA experiment

T.Toshito (Nagoya univ. 　 Japan)

for the OPERA collaboration

Apr.21 2002APS2002@Albuquerque

CNGS beam

Due to CERN financial situation we have one year delay.The beam will start on spring 2006.

L=732km

<Eν>=17GeV

400GeV protons from SPS

νμbeam

Optimized to study ντ appearance　 @ Δm2=3×10-3eV2 (SK atm. ν)

Construction started on Oct. 2000

Detector

Hall C

Pb

Emulsion layers

1 mm

ECC(Emulsion Cloud Chamber) to detect decay topology of τ

μspectrometer

ECC bricks+scintillator strips

ν

Gran Sasso

1.8kton

proven by DONUT

10 c

m

Brick assignment

Plastic scintillator strips (2.6cm width) 　 (x,y)

Pulse height

8cm58emulsion+57Pb plates

10X0

12.5cm8cm

10cm8kg

235k bricks

Emulsion read-out(Super-Ultra Track Selector)

0.008

0.25

3

60

0.001

0.01

0.1

1

10

100

TS(1994) NTS(1996) UTS(1998) S-UTS(2002)

Scanning Power Roadmapviews/sec(1view=120× 90 m 2)

S-UTS

Scanning speed: 20cm2/h×20 faster than current system (UTS)

Fast CCD camera (3k frames/sec)Continuous movement of the X-Y stageZ movement controlled by piezo actuator

developed at Nagoya Univ.

~30 Events./day = 30 Bricks

Extraction of the Tagged Brick (every day)

emulsion development

Cosmic ray exposure

(for alignment)

emulsion read-out

Quasi on-line ECC analysis

Brick disassembling

scanning station @ Nagoya Univ.

“ Long decaysreconstruct kink topology

“ Short decays detect large impact parameter track

Decay search

I.P.>5~20μm

τ→ e 0.9τ→μ 0.5

τ→ e 3.1τ→μ 2.9τ→ h 3.4

ΔΘkink > 20mradexpected signal@ 2.4×10-3eV2

& full mixing

Electron identification

e

π

Test exp. @ CERN (May2001)

Data

Data

MC

MC

2GeV

4GeV

eff~90%, mis-id prob~5%

Shower detection & χ2 analysis

Electromagnetic shower

MC Data

Test exp. @ CERN (May2001)

)(E

4.0~

GeV

@ a few GeVEnergy determination by calorimetric method

Sensitivity

5 years

3 years

exclusion plot in the absence of a signal

1.8kton

1.2×10-3eV2

expected signal11events@ 2.4×10-3eV2

30k νμCC+NC~120ντCC

Summary

• OPERA ντ appearance experiment at CNGS

sensitive to SK atm. ν region

• S-UTS:

start test operation in this year

• Electron ID and shower analysis in ECC:

required performance is achieved

• Ready for data taking in 2006

one year delay due to CERN financial situation