The OPERA long baseline neutrino experiment: status and first results Luigi Salvatore Esposito...

The OPERA long baseline neutrino experiment: status

and first results

Luigi Salvatore Esposito

Laboratori Nazionali del Gran Sasso

on behalf of the OPERA collaboration

23-29 May, 2008 QUARKS-2008, Sergiev Posad L.S.Esposito 2

Summary

• Aim and strategy of the experiment• OPERA detector• CNGS 2007 run• Neutrino interactions in a lead-emulsion

target• CNGS 2008 run• Conclusions


The OPERA collaboration

36 INSTITUTIONS, ~200 PHYSICISTS

Annecy, Lyon, Strasbourg

Dubna, Moscow(INR,LPI,ITEP,SINP

MSU) Obninsk

Zagreb

L’Aquila, Bari, Bologna, Frascati,

LNGS, Napoli, Padova, Roma, Salerno

BernNeuchatel

Zurich

Brussels

Hamburg, Münster,Rostock

Sofia

Aichi, TohoKobe, NagoyaUtsunomiya

Technion Haifa

METU Ankara

Gyeongsang


OPERA is designed for the direct observation of appearance in a pure νμ beam in order to provide a final confirmation of neutrino oscillations in the atmospheric sector

Physics motivations

best fit:

M.C. Gonzalez-Garcia et M.Maltoni arXiv:0704.1800 [hep-ph]

E(GeV)

L(Km)m27.1sin)(cos)2(sin)νν(P

2312

134

232

τμ


The Cern Neutrino to Gran Sasso (CNGS) program

CERN beam optimized to study the appearance by detection

Beam mean features:

L=730 km ; <E>=17 GeV

/ = 2.1% (e+ e)/ = 0.68% prompt negligible

730 Km

CERN

LNGS


Detection of the appearance signal

The challenge is to identify interactions from interactions

-

Decay “kink”

-

~1 mm

oscillation

-

h-n(

e- e

+--n(

B. R. ~ 17%

B. R. ~ 50%

B. R. ~ 18%

B. R. ~ 14%

decay modes

OPERA solution is a OPERA solution is a hybrid hybrid technique:technique:tracking apparatus with “many” tracking apparatus with “many” Emulsion Cloud Chamber target Emulsion Cloud Chamber target units (units (lead/emulsion structure)lead/emulsion structure)

• Long-baseline, flavour oscillation: small fraction of Long-baseline, flavour oscillation: small fraction of νν ::

Far-away source, low flux, weak interaction: Far-away source, low flux, weak interaction: →→ large large targettarget massmass required (as usual for required (as usual for ’s …)’s …)

• CC interactions of CC interactions of νν tagged by the tagged by the decaydecay (c(c = 87 = 87 μμmm)) : :

→→ need need high spatial resolutionhigh spatial resolution & & lepton Id lepton Id


Pb

Emulsion layers

1 mm

The brick is the target basic component:• 57 nuclear emulsion films interleaved by 1 mm thick lead plates • “Changeable Sheets doublet” made of two double refreshed emulsion films,vacuum packed and glued onto the bottom of each brick to connect TT- brick

2 emulsion layers (44 m thick)poured on a

205 m plastic base

130 000 m²

12.5cm

10.2cm

8.3 Kg

10 X0

Electron trackEmulsion:Measuring a vector in space(δx=1 μm δθ=1 mrad)

The OPERA target is composed of 155000 bricks

Emulsion analysis:

Vertex, decay kink, e/ ID, multiple scattering, kinematics measurements

on event-by-event basis! … limited by statistics

The OPERA target


Target Tracker + Brick Walls

Spectrometer

0 max

p.h.

OPERA: a hybrid detector

What the brick cannot do: trigger for a neutrino interaction muon identification and momentum/charge measurement need a hybrid detector

On-line analysis of electronic data

Brick finding algorithm

Selected brick is removed from the target and exposed to cosmic rays (alignment). Emulsions are developed and sent to scanning stations / labs


The OPERA detector

SM1 SM2

VetoBMS

Target tracker Spectrometer:XPC, HPT, RPC, magnet

Modular,Modular, Hybrid Hybrid Detector:Detector:Two Two supermodulessupermodules, each containing, each containing a a Target Target SectionSection - 31 Target - 31 Target WallsWalls to host target units ( to host target units (ECC bricksECC bricks)) - 31 Target - 31 Target Tracker modulesTracker modules (scintillator strips) (scintillator strips) a a Magnetic SpectrometerMagnetic Spectrometer (XPC, RPC, Drift tubes) (XPC, RPC, Drift tubes)• Upstream:Upstream: VETO (glass RPC) VETO (glass RPC)• Both sides:Both sides: BBrick rick MManipulation anipulation SSystem (BMS)ystem (BMS)• Nearby: Nearby: BBrick rick AAssembly ssembly MMachine (BAM) - achine (BAM) - Hall BHall B • Data Taking: (1) Data Taking: (1) DAQ DAQ nodes + time stamp [Gran Sasso]nodes + time stamp [Gran Sasso] (2) (2) Emulsion scanning Emulsion scanning [Europe and Japan][Europe and Japan]

… … && several facilities for brick & emulsion film handling several facilities for brick & emulsion film handling (X-ray systems, “Changeable sheets” refreshing and assembly, (X-ray systems, “Changeable sheets” refreshing and assembly, cosmic-ray exposure, film development)cosmic-ray exposure, film development)

CNGS beamCNGS beam

1919 mm

10 m10 m8 m8 m

Hall C Hall C -- Gran Sasso Gran Sasso Underground Lab (Italy)Underground Lab (Italy)


Status of brick production

Brick Assembly Machine: piling/pressing section

Brick Assembly Machine:wrapping section

• 9*106 emulsions & lead plates• 155 000 bricks to be produced• production rate ~ 700/day

Filling under completion, ~ 88% now

brick production/filling

020000400006000080000

100000120000140000160000180000

1 8 15 22 29 36 43 50 57 64 71 78 85 92

weeks

bri

ck

s

2 drums/day

2.5 drums/day

3 drums/day

real

June 10th July 28th


High speed CCD Camera (3 kHz)

Piezo-controlled objective lens

Constant speed stage

Synchronization of objective lens and stage

Off-line Data Taking~ 30 bricks will be daily extracted from target and analyzed using high-

speed automatic systemsSeveral labs distributed in Europe and Japan

S-UTS (Japan)

Customized commercial optics and mechanics + asynchronous DAQ software

Hard-coded algorithms

scanning speed ~ 20 cm2 / h

European Scanning System

Automated emulsion scanning


Automated emulsion analysis

• Predictions from electronic detectors are searched in the Changeable Sheet doublet.

• If an interaction is detected in the CS, the brick is exposed to cosmic rays (alignment) and the emulsions are developed and sent to scanning stations/labs

• The tracks measured in CSd are followed back inside the brick until tracks stop.

• A full scanning around neutrino interaction vertex is performed

• Finally the event topology and kinematics reconstructed is performed

Emulsion scanning is performed in a fully automatic way. About 40 microscopes are operational in the various OPERA scanning laboratories (Europe and Japan).

CC interaction

h

muon

2 cm

2 m

m

ECC brick

CS doublet


Track segments found in 8 consecutive plates

Passing-through tracks rejection

Vertex reconstruction

Momentum measurement by Multiple ScatteringdE/dx for /µ separation at low energy

Electron identification and energy measurement

3D reconstruction of particle tracks

16 tomographic images

2D Imageprocessing

40m emulsion sheet

Emulsion scanning

200 m

Field of viewField of view

0.2 m


Status of the experiment

May 2003: start of detector construction

May 2006: completion of electronic detectors commissioning

Aug 2006: technical run, 0.76*1018 pot collected

319 interactions in the rock, mechanical structure and iron of the spectrometer

Oct 2006: start of brick production

Oct 2007: short physics run (~40% target) 0.824*1018 pot collected

38 events collected in the target

May 2008: 135000 bricks inserted (~88% target)

Jun 2008: OPERA target will be completed. Start of full data taking, expected about 2.1*1019 pot in 130 days of SPS running.


2007 run: Interactions outside the Target

331 events passed the analysis cut303 had been expected:ratio similar to the one observed in 2006

Muon vertical angle Energy of the muon (RPC)


31.5 ± 6 expected events in bricks

38 events registered in the target (bricks + scintillators + walls extra 10% contribution) during the 2007 CNGS run:

• 29 CC-like• 9 NC-like

Brick handling, Film Processing, Scanning : first test on real neutrino interactions

2007 run: Interactions inside the Target

Event analysis is almost completed on this small sample

Unfortunately statistics has been quite limited.

Wall Finding: > 95%Brick Finding: 80% 7%Position accuracy: 2-3 cm


= 22 µm = 5 mrad

CS to brick connection: design accuracy


= 54 µm = 9 mrad

Systematical uncertainties (gap, marks, …) dominate

CS to brick connection: neutrino interactions


Scan-back accuracy

= 4 µm = 2 mrad


Example of CC interaction

5 prongs associated to the neutrino interaction

<IP> = 9 m

Electromagnetic shower pointing to the vertex ( conversion)

19 m

8 m

43 mm

17 m

m


Charm candidate Trk TX TY IP Momentum(GeV) Comment

1 0.005 0.036 3.30 1.7+0.5-0.3

2 0.005 0.139 1.01 - parent

3 0.002 0.064 6.64 >20.0 SB

4 -0.021 0.064 7.15 2.1+0.7-0.4 SB

5 -0.029 0.046 2.83 >8.4 SB

6 -0.031 0.064 7.32 2.4+0.8-0.5 SB

7 -0.076 0.068 4.19 1.8+1.6-0.6 SB

8 -0.089 0.141 6.88 2.5+1.4-0.7

9 -0.183 0.106 5.39 0.7+0.2-0.1

10 -0.297 -0.143 19.17 0.7+0.3-0.1

11 -0.067 0.008 7.26 3.5+3.6-1.2 e-pair

12 -0.069 0.005 16.80 2.0+3.1-0.8 e-pair

Secondary VertexDaughter momentum = 3.9 +1.7

-0.9

kink = 0.204 radFlight length = 3247 μmPt = 796 MeV

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

Kink

PRELIMINARY


OPERA τ search sensitivity

- decay

channels

Signal ÷ m2 (Full mixing)

Background

2.5 x 10-3 (eV2) 3.0 x 10-3 (eV2)

- µ- 2.9 4.2 0.17

- e- 3.5 5.0 0.17

- h- 3.1 4.4 0.24

- 3h 0.9 1.3 0.17

ALL 10.4 15.0 0.76

• 5 years CNGS data taking ( 4.5 1019 pot/year )• 1.35 ktons target mass


OPERA observation probability

SK 90% CL(L/E analysis)

Dis

covery

pro

bab

ilit

y

%

Last MINOS measurement

3 σ sensitivity

4 σ sensitivity


The 2008 OPERA run

130 days for the CNGS (200)2.1*1019 p.o.t (4.5*1019)

Start: ~ June 20th

End: Nov 10th

Total number of interactions

2000

CC events 1500

NC events 450

ee events 13

Charm decay 85

Tau candidate (@2.5 10-3 eV2)

~ 1


The OPERA experiment is running- Electronic detectors fully commissioned- Target filling in progress (completed by June) Scanning labs are ready (~40 microscopes available)

The OPERA 2007 run allowed to test the full operation chain:- Test electronic detectors and data acquisition- Test the brick finding algorithm- Test brick handling- Test CS doublet scanning- Test the target tracker to brick matching and scanning strategy

The concept of the OPERA detector has been experimentally validated by measuring neutrino

events in the detector.

Conclusions

In June the first high luminosity OPERA run will start. With some luck we will measure the first candidate event by the end of this year!


BACKUP SLIDES


Time Selection of Beam Events

GPS

TCERN = Time Stamp SPS extraction

TOPERA = Event TimeStamp

Tflight = 2.44 msec

TOPERA - (TCERN + Tflight) < ∆TGate

GPS Time Stamp resolution ~ 100 ns


The 2006 commissioning run: CNGS and cosmics

50 ms

10.5 s 10.5 s

August 2006Integrated: 7.6x1017 p.o.t.319 “beam-related” events [New J. Phys. 8 (2006) 303]


τsearch: backgrounds

-

,e,e-

+

e+

h+

D+

Same decay topology as

Charm production in CC,common to the 3 channels

Good muon identification is fundamental

Primary lepton not identified

Coulombian large angle scattering of muons in Lead : Bck. to

Hadronic interactions in Pb: Bck. to hor to if hadron mis-identified as muon)

Expected number of background events after 5 years running with nominal beam:

h h

τe τμ τh τ3h TotalCharm background .173 .008 .134 .181 .496

Large angle μ scattering .096 .096

Hadronic background .077 .095 . .172

Total per channel .173 .181 .229 .181 .764


e oscillation search

13 SIGNAL e beam e NC CC

9° 9.3 18 4.5 5.2 1.0

7° 5.8 18 4.5 5.2 1.0

5° 3.0 18 4.6 5.2 1.0

mm232322 = 2.5 x 10-3 eV2 23 23 = 45° = 45°

nominal CNGS beam

Combined fit of ECombined fit of Eee, E, Evisvis, (pt), (pt)missmiss

to improve S/B ratioto improve S/B ratio

90% C.L. limits on sin90% C.L. limits on sin22(2(21313) and ) and 13 13 ::

sinsin22(2(21313)<0.05 )<0.05 13 13 < 7.1º< 7.1º

5 years

(pt)miss

GeV

2.5x10-3 eV2

7.1o6.4o


CNGS control electronics failure

The failed ventilation electronics were installed along the TSG4 (service gallery), next to the ventilation ducts, and in the TCV4 (ventilation chamber).

In both areas the radiation levels, as predicted by the FLUKA simulations and confirmed by the radiation protection measurements, are far too high for COTS components the electronics should have failed and they did!!

Designated “radiation safe”

areas for electronics

electronic equipment

electronic equipment


Actions for 2008 shutdown

General guideline:• Replace damaged electronics Replace damaged electronics • Move the electronics out of the CNGS tunnels as possibleMove the electronics out of the CNGS tunnels as possible

For the equipment which must stay in the area:For the equipment which must stay in the area:• Create a “radiation-safe” area by adding adequate shielding and move all the electronics Create a “radiation-safe” area by adding adequate shielding and move all the electronics into this areainto this area• Address the sensitivity to radiation of the installed electronics and investigate upgrade Address the sensitivity to radiation of the installed electronics and investigate upgrade possibilitiespossibilities• Install a radiation monitoring system for electronics as in LHCInstall a radiation monitoring system for electronics as in LHC

During the 2007/2008 shutdown, work is organized to remedy the problem and assure nominal running of the facility for 2008 and beyond.

Radiation damages repair and protection:• the work is fully funded• electronics repair and reshuffling has started, shielding plugs defined, civil engineering starting• completion of the work expected by the end of week 23 (June 6th)• stable beam during week 25 (~June 20th)


Summary Event Location & Data analysis

Europe Japan

All event 19 (15 CC, 4 NC)

19 (14 CC, 5 NC)

Events confirmed in the CSd

18 18

Events located in the bricks

14 10

Interactions in dead material

1 1

CS-Brick mismatch 1 1

Analysis in progress 2 6

The OPERA long baseline neutrino experiment: status and first results Luigi Salvatore Esposito...

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