status and oscillation results of the opera experiment

Status and oscillation results of the OPERA

experimentFlorian Brunet

LAPP - Annecy

24th Rencontres de Blois 29/05/2012

Outline Goal & principle of the OPERA experiment Description of the OPERA detector Status of OPERA Oscillation results

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F. Brunet - LAPP Annecy - Blois 2012

Super- Kamiokande oscillations with atmospheric neutrinos Oscillation phenomenon confirmed with solar neutrinos Hints for appearance with recent T2K/MINOS resultsThe direct observation of the oscillation appearance with

accelerator beams needs to be proven in the atmospheric sector

The PMNS 3-flavor oscillation formalism predicts:

OPERA requires : 1) long baseline, 2) high neutrino energy, 3) high beam intensity 4) detection of short lived τ’s

OPERA: FIRST DIRECT DETECTION OF NEUTRINO OSCILLATIONS IN APPEARANCE MODE

P() ~ sin2223cos413sin2(m223L/4E)

4

OPERA

CNGS

LNGS under 1400m of rock

L = 730 km

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● The beam is optimized for ντ appearance in the atmospheric oscillation region. The present best fit is now:

● Although the maximum of oscillation probability at 730 km is at about 1.5 GeV, the ντ CC cross section and the production threshold of 3.5 GeV should be taken into account

<Eμ> 17 Gev

(e +e)/ μ 0.87%

μ / μ 4 %

prompt negligible

Total p.o.t 22.5x 1019

μ CC + NC ~23600

e +e CC ~160

~115


CNGS APPEARANCE POTENTIAL

5

32.0+29.0-

2

+0.220.08-23

2

35.2=mΔ

0.42=θsin

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G. L. Fogli, E. Lisi, A. Marrone, A. Palazzo, A. M. Rotunno, arXiv:1106.6028 [hep-ph]

with the OPERA target mass of 1.25kt

-

● The detector must fulfil the following requests: 1. Small ν cross section large fiducial mass (lead target) 2. Kink topology detection micrometric and milliradian resolution

(emulsions) 3. Select neutrino interactions electronic detectors (trigger efficiency ~

99%) 4. μ-ID and charge to reduce charm background (precision tracker &

spectrometer)3h e (17.9%)

(17.4%) h (49.2%) 3h (15.2%)

- e-, -, h-


DETECTION PRINCIPLE

OPERA: hybrid detector (emulsions + electronic detectors)629/05/2012

Long decay

Short decay

THE IMPLEMENTATION OF THE PRINCIPLE

8F. Brunet - LAPP Annecy - Blois 2012

22 RPC + 6 Drift Tubes planesmagnetic field (1.5 T)

Extract 25-50 bricks per day

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10.3 cm

12.8 cm7.5 cm = 10 X0

ν

27 brick walls alternated withscintillator planesmip : detection efficiency of ~ 99%.

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Hybrid target structure.

(CS)

1. Trigger on event “on time” with CNGS and selection of the brick using electronic detectors information

2. Brick extracted by BMS

3. Electronic tracks validated with CS

4. Brick is sent to one of 12 scanning labs in Europe and Japan.

OPERA : A HYBRID DETECTOR (ELECTRONIC + EMULSIONS)

Scanning : Determine the topology of the event to possibly find a kink

microtracks basetracks tracks vertices

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45μm300μm

4.2 cm

5.2 cm

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OPERA data : an example of νμ CC interaction : charm eventReconstruction in electronic detectors

Reconstruction in emulsions

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Data taking

• We collected a large sample of events and since march 2012 run is on going.

The analysis of 2008 and 2009 data is complete (New J.Phys. 14 (2012) 033017)).

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2008-2009 : 5.3 x 1019 p.o.t.

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Charm sample 2008-2009

● OPERA 2008-09■ MCAngle in the transverse plane between charmed hadron and

primary µ

● OPERA 2008-09■ MC

Decay length

The charm sample offers the opportunity to benchmark the efficiency thanks to the similar topologies


ντ Oscillation signal• In the 2008-2009 data we found a ντ candidate (Phys. Lett. B 691 (2010) 138 ).

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Background estimation improvements

• Reduction by the systematical tracks follow down for the candidate events to improve

the muon identification Reduce charm background & hadronic background from

CC with misID

• Evaluate the hadronic reinteraction using MC simulations. (MC validated by analysing pion test beam data & 14m of hadron tracks in OPERA data)

• Implementation of state-of-the art charm cross section from CHORUS


Significance of this result

• In the analyzed sample one observed in the h channel compatible with the expectation of 1.65 signal events. • The statistical significance of the observation (i.e.

the probability of not being a fluctuation of the background) is 95%.

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5.3e19 pot


The additional oscillation study : νμ→νe channel

• We have detected 19 νe candidate events in the 2008-09 analyzed sample.

Physics motivation Signal νμ ↔ νe : νe

CC interaction e + hadronic shower Background : Processes which contain electrons

νe beam: νeCC interaction e + hadronic shower

ντCC

interaction τ + hadronic shower & τ→eνν

νμ beam : νμNC interaction ν + hadronic shower with π0 & π0 →γγ

νμ beam : νμCC interaction μ missed νμ

NC interaction

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Electron energy = 7.4 GeV

OPERA target mass hypothesis = 1.25kt

2008-2009 : 5.3e19 pot

5 years : 22.5e19 pot

e (prompt) 1.6 6.7

( e)+NCp0 0.6 2.6

sin2213 = 0.11 0.7 3.1Efficiencies taken from : M. Komatsu, P. Migliozzi, F. Terranova, J. Phys. G G29 (2003) 443

Prel

imin

ary

est

imat

ion


νe study : electromagnetic shower reconstruction• An energy estimation of electromagnetic showers is available by

using OPERA bricks as a calorimeter and the following improvements are under finalization :

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• A recalibration with a full MC simulation• A recalibration with OPERA bricks exposed to an

electron beam at CERN (4GeV & 2 GeV, 100mrd angle)

• An updated systematic errors estimation • An updated efficiency estimation with the full MC

simulation

• Developments in progress about energy estimation • Due to relative small size of bricks, an extended shower

reconstruction with one adjacent or downstream brick to achieve a better estimation of the energy is on going

Preliminary


• The OPERA detector has been taking physics data successfully since 2008.• The electronic detector response is well understood and the agreement between data and simulation is quite good.• 2008 and 2009 data analysis is finished and one ντ candidate has been observed and 19 νe candidates.• We have already collected data to increase the statistics by a factor of 2.7: the vertex location is being performed on the 2010 data and on the 2011 data.• The τ search goes on and OPERA will present an update of all its studies at the Neutrino 2012 conference.• Knowing recent results about θ13, a specific search for νe candidates is on-going, since OPERA could contribute to the numu-nue oscillation study at high ∆m2.

Summary

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Backup slides


"Results from OPERA" S. Dusini INFN-PD 21

-TOF

Basic ingredients:

- CNGS-OPERA synchronization at ~1ns (GPS common view mode)- Calibrations of the timing chains at CERN and OPERA- time distribution at CERN through proton waveforms with BCT- High n energy - high statistics (~ 15k events) or beam with fine time structure- Geodesy: L= 731278.0 ± 0.2 m (error dominated by extrapolation to underground)

arXiv:1109.4897

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-TOF:

An experimental setup and analysis method has been used to estimate the neutrino time of flight CERN-LNGS

BUT, two issues that could significantly affect the reported TOF anomaly have been identified recently

The new bunched beam analysis will provide a clarified picture and possibly a limit on the departure of neutrino velocity from the speed of light.

status and oscillation results of the opera experiment

Documents

brunet lapp annecy blois

opera experimentdescription

detection principle

opera target mass

oscillation appearance

detection efficiency

atmospheric oscillation

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