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E - opera - Infn

CIPANP 2009: Tenth Conference on the Intersections of

Particle and Nuclear Physics

Torrey Pines Hilton—San Diego, California—26 May to 31 May, 2009

L. Patrizii INFN – Bologna, Italy

on behalf of the OPERA Collaboration


35 INSTITUTIONS, ~200 PHYSICISTS

Brussels

Annecy, Lyon,

Strasbourg

Bern,

Zurich

Hamburg, Münster,

Rostock

Zagreb

Sofia

Dubna, Moscow

(INR,LPI,ITEP,SINP

MSU) Obninsk

L’Aquila, Bari,

Bologna, Frascati,

LNGS, Napoli, Padova,

Roma, Salerno

Aichi, Toho

Kobe, Nagoya

Utsunomiya

Technion Haifa

Gyeongsang

METU Ankara

2


CNGS

SK-I

MACRO

Soudan-II

K2K-I

Kamland

SNO-I SNO-II

K2K-II

NUMI

T2K

Provide final

confirmation of neutrino

oscillation in the

atmospheric sector


RUN

[OPERA]

CERN

• From SPS: 400 GeV/c

• Cycle length: 6 s

• Extractions:

– 2 separated by 50 ms

• Pulse length: 10.5 µs

• Beam intensity:

– 2.4 · 10 13 proton per extr

• Expected performance:

Gran Sasso

– 4.5 ⋅ 10 19 pot/year CNGS: a 17 GeV ν µ beam from

CERN to Gran Sasso (732 km)


400 GeV protons on graphite target

1 km decay tunnel

ν µ beam < E > ~ 17 GeV

< E > 17 GeV

ν µ

L

L/E

730 km

43 km/GeV

( ν e + ν e ) / ν µ 0.87%

ν µ / ν µ 4%

ν τ prompt

negligible

In 5 years, 4.5*10 19 pot/y, 200 days/y, 1.3 kton,

Nb. of produced events

~ 25400 ν µ CC+NC

~ 169 ν e + ν e CC

Δm 2 (eV 2 ) Occurring ν τ CC events (∆m 2 ) 2

2.5 x 10 -3 125


underground area: 18 000 m 2

easy access


Adriatic Sea

The INFN LNGS, 900 m asl

(Abruzzo, Italy)

ROME

15 km from the epicenter

The April 6 th Earthquake

caused no damage to the people or the equipment of

the Gran Sasso Laboratory ( acceleration : 0.02 g, (0.6 g

at l’Aquila)

All the running experiments have been working smoothly,

and the external buildings essentially untouched.

May 4 th regular restart of the Staff activity

7


What kind of detector?

ν τ

τ decay “kink”

τ

Detector resolution

must be O(1 µm)

N τ

= N A

M D


φ ν µ

(E)P (E,Δm 2 )σ CC

ν µ →ν ντ

(E)ε(E)dE

τ

Target mass O (1 kton)

for Δm 2 = O (10 -3 eV 2 )


OPERA is based on the only proven technology (DONUT) to

identify ν τ on an event-by-event basis (nucl.emuls.&lead

driven by real time detectors).

8


ν beam

Veto

Target

Spectrometer

• 2 SuperModules (1 SM = 1 target section + 1 spectrometer) each with

• Target section

~75000 bricks arranged in 31 walls (total target mass ~ 1.25 ktons)

Target Tracker (Horizontal/vertical crossed scintillator strips)

• Spectrometer: 1 kton dipolar magnet [ B∼1.52 T ] with drift tubes and RPCs

• Veto system to tag external interactions


Full mixing, 5 years run, 4.5x10 19 pot / year and 1.25 kton

Efficiency before τ identification: trigger x brick x geom x vertex location

99% 80% 94% 90%

ν τ events (∆m 2 ) 2

Discovery probability (%)

4-σ evidence

3-σ evidence

τ→µ 17.5 17.8 2.9 0.17

τ→e 20.8 17.8 3.5 0.17

τ→h 5.8 49.5 3.1 0.24

τ→3h 6.3 15 0.9 0.17

ALL

x BR

=10.6%

10.4 0.75

Δm 2 (10 -2 eV 2 )

10


ν µ ↔ ν e oscillation channel

Due to its good e-ID capability, OPERA is well suited for ν µ ↔ν e

searches

Sensitivity fully dominated by statistics

11


CNGS
Beam


4


OPERA in Hall C

Scin/llator
strip


CNGS
Beam


Brick


Target


150,
000
bricks
(total)


Scin/llator
strips
:

Brick


selec/on






































Calorimetry


4


OPERA in Hall C

CNGS
Beam


Muon
spectrometer


for
momentum
and
charge
iden0fica0on



of
penetra0ng
par0cles


Target


150,
000
bricks
(total)


Scin/llator
strips
:

Brick


selec/on






































Calorimetry


4


The OPERA ECC brick

56 Pb sheets (1 mm thick) / 57 Emulsion layers (300 µm thick) = 10 X 0

2 additional Emulsion layers (CS, Changeable Sheets) downstream to confirm

brick predictions from electronic detectors

Plastic base 200 µm

Changeable sheets box

1 mm

ν

τ

12.9 cm

8.3 kg

10.2cm

12.5cm

Pb

Emulsion

layers 45 µm

ECC provides

• Neutrino interaction vertex and decay topology reconstruction

• Measurement of charged particles momenta by Multiple Coulomb Scattering

(20-30% resolution up to 4-5 GeV/c )

• dE/dx for π/µ separation at the end of their range

• Electron identification and energy measurement


Target Filling

150000 bricks today

1.25 kton

BAM (Brick Assembling Machine)

Automatic lead/

emulsion piling in

a dark room

(~700 bricks/day)

The BMS(Brick Manipulator System)

6 m

one robot on

each side of the

detector

Insertion and

extraction of bricks

following complex

procedures.

16

now


OPERA Target Mass

~1. 25 kton

~ 9M emulsion films

The Gran Sasso Mountain is called “the Giant”

2590 m

2914 m

OPERA will be firstly celebrated as a major

engineering achievement since it brought

the ECC technology to a gigantic size


Brick finding

υ

Brick extracted from the wall using the

the Brick Manipulator System

Fully automatized scanning

(> 20 cm 2 /h)

Spatial resolution < 1 µm


Automatic emulsion scanning

Based on the tomographic acquisition of emulsion layers.

Scanning speed of ~20 cm 2 /h.

~ 30 bricks daily extracted thousands of cm 2 /day

The European Scanning System

The S-UTS (Japan)

Customized commercial

optics and mechanics

Hard-coded algorithms

19


Target Tracker - CS connection

σ~8.7 mm

σ~9.5 mm

σ~21 mrad

σ~22 mrad

2009/05/14 20

M.

Pozz

ato


CS – Brick connection

σ~64 µm

σ~69 µm

σ~10 mrad σ~12 mrad

2009/05/14 21

M.

Pozz

ato


Event reconstruction in emulsions.

An example: the 1st OPERA event

Muon track parameters from Target Tracker:

Kalman sx: 0.039 sy: 0.172

Linear sx: 0.035 sy: 0.197

Momentum: ~7.5 GeV

22


Event reconstruction procedure

CSd general scan:

50 cm 2 around TT prediction

(±400 mrad)

alignment between emulsion sheets

with X – ray marks (10µm accuracy)

‐ CS
–
Brick
connec/on


scanning around the CS predictions

look for tracks

- DeltaPos: 300 µm

- DeltaSlope: 0.03 rad

1

2

ν µ

1


48

49

50

51

52

53

54

55

56

57

2

Scan
back:



alignment using cosmic ray

tracks (2 µm accuracy)

stopping point

Volume Scan:

• 1 cm 2 , 13 plates

• reconstruct tracks inside the volume;

• Analyze scan back reconstructed tracks (stopping

tracks, passing through, attached to multiprong

vertex).


The 2008 run : the very first physics run for the CNGS

• 2006 : Pilot run, few bricks in OPERA.

• 2007 : Major problems in the radiation shielding of the

ventilation system. Only 8·10 17 pot.

• 2008 OPERA fully operational.

After the LHC accident, further increase of the integrated

intensity for OPERA (duty cycle 37.5% →83%).

LHC

2xCNGS

MTE/CNGS

4x CNGS

SFTPRO 3xCNGS LHC MD


CNGS Run 2008: 18 June- 03 Nov 2008

Total: 1.78·10 19 pot

CNGS

maintenance

Nominal: 4.5 10 19 pot/yr for 5 years

SPS extraction line:

Magnet ground fault

MD

Beam to

CNGS, MD

SPS timing fault:

vacuum leak &

magnet exchange

PS magnet

exchange,

septum

bakeout

18kV cable

repair

MD

CNGS

maintenance

Beam to CNGS,

LHC, FT, MD

Beam to CNGS,

LHC, FT

MD


OPERA as a real-time detector

CNGS-LNGS synchronization: based on GPS. Present

precision is 100 ns (can be improved up to 10 ns)

DAQ livetime >99%. Overall livetime during CNGS 98.9%

Collected events correlated with CNGS: 10122 on time

(mainly in surrounding material) and 1663 in the target

OK

[Negligible

bkg from

cosmics]

Direction and momentum reconstruction for CNGS event

Charge and momentum reconstruction for off-time

events (cosmic ray analysis)

OK

In progress


OPERA as a hybrid detector

Prediction of the brick where the interaction occurred

Alignment and development of Changeable Sheets

Scanning of the Changable Sheets

Extraction of the Bricks at the rate of CNGS events

Identification of the primary vertex

Kinematic reconstruction and decay search

Part. validated

Fully validated

Fully validated

Fully validated

In progress

In progress


From Brick finding

Check sample of extracted 1° bricks with CS

scanned: 700 events (full stat. results will

follow)

Tracks found in the CS: 60%

1 st Brick finding (corrected for dead material

and CS efficiency): 70% (OK!)

Expectation after 2 nd extraction: 80%

(check with real data in progress)

Manca plot

To Brick extractions

End of CNGS

run

Up to 25 bricks per shift

LPNHE Paris, April

28 th , 2009

GDR Neutrino

2008 – 2009 Week number


To the Scanning of Changable Sheets

LNGS (Italy)

NAGOYA (Japan)

MC independent test of track finding

efficiency in CS in a subsample of fully

located event (ε sb ~ 90%) OK!

LNGS

ν

Brick

CSd


To Vertex finding and decay search

In Japan, it is accomplished in the same site as for CS scanning

in Europe it is outsourced to several laboratories.

Impact Parameter of the µ track in CC

events with respect to the reconstructed

vertices (IP < 12 µm).

Charged track multiplicity distribution

of the events

arXiv:0903.2973v1 [hep-ex].


Vertex location summary, 2008 run as of April 3 rd 2009

NC CC Total

Bricks scanned 162 693 855

CS to brick connected 151 666 817

Vertices located in the brick 100 530 630

Passing through 10 35 45

Vertices in the dead material 2 9 11

At least 1 CS track

connected in brick: 96%

Located events:

77%

Passing through (wall

misidentification): 6%

Interactions in dead

material: ~ 2%


Event Gallery


ECC level

pair opening

angle 10 mrad

E γ

= 157 MeV

low p

track

LPNHE Paris, April 28 th , 2009 GDR Neutrino H. Pessard / 35

35


Charm-candidate event

θ kink =0.204
rad


e.m.shower

kink

Daughter momentum = 3.9 +1.7-0.9

θkink = 0.204 rad

Flight length = 3247 µm

PT = 796 MeV

PTMIN = 606 MeV (90% C.L.)

The main background source is the hadron

reinteraction

The probability that a hadron reinteraction has a Pt

larger than 600 MeV is 4*10 -4


Primary
interac0on


Decay
in
3
prongs


muon


Three charged prongs decay

Flight length : ~1150 µm

Angle (muon – 3 prongs decay) :

~150°

muon


Kaon decay probability : 10 -4 %

Hadron re-interaction probability :

1x10 -5 %

8


Summary

The construction of OPERA is over; the subdetectors and the ancillary

facilities fully operative.

In 2008 CNGS delivered ~2 ⋅ 10 19 p.o.t.: the first real physics run for

OPERA. First long physics run, poor CNGS performance at beginning,

better at the end (more CNGS cycles)

Analysis chain almost fully validated.

Full results in some more months.


RUN 2009 expectations / Conclusions

Beginning June 1 st

Hoped for numbers:

173 days

48s supercycle

80% efficiency

3.6E19 pot

3500 neutrino interactions in the OPERA target

…first tau detection

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