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Status and resultsfrom OPERA experiment
Luca Scotto LavinaA. Einstein Center for Fundamental Physics,
LHEP Bern University
2010 CHIPP Annual Plenary Meeting 23-24 August 2010, Gersau
on behalf of the OPERA swiss groups (Bern and ETHZ)
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 2
A. Badertscher
C. Lazzaro
A. Rubbia
T. Strauss
ETHZ
LHEP
A. Ariga
T. Ariga
A. Bendhabi
A. Ereditato
J. Knüsel
F. Juget
J. Kawada
I. Kreslo
G. Lutter
F. Meisel
U. Moser
C. Pistillo
K. Pretzl
L. Scotto Lavina
J.L. Vuilleumier
OPERA in Switzerland:2 institutions, 19 physicists
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 3
Activities of swiss groups in OPERA
Common for all scanning labs:- Decay search- Kinematic analysis
Unique to Swiss group:- Study of hadron background for tau- Gamma detection, energy estimation, 0 reconstruction- Electron ID, energy estimation- MC studies on tau and charm- Low momentum muon ID- Development of 3D display for event analysis- ECC analysis and event reconstruction
- Conceptual design - Proposal - CNGS beam design and optimization - Construction of the Target Tracker - Lead production monitoring- Development of European microscopes - Emulsion film robot- Test beams - Physics analysis…
Past activities Present activities
Responsibilities of the Swiss researchers
A. Ereditato (spokesperson)
Education
PhD thesis in progress:- J. Knüsel (LHEP):
low momentum muon identification- C. Lazzaro (ETHZ):
determination of the CNGS neutrino energy spectrum from CC events
reconstructed with the electronic detectors - F. Meisel (LHEP):
electron and gamma reconstruction in OPERA experiment
- T. Strauss (ETHZ):neutrino induced charmed particle decays
Emulsion scanning
The largest scanning team in Europe:- 20 physicists- ~35% brick european scanning load at LHEP- ~75% european scanning load for BG studies at LHEP
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 4
90% CL@ 22.5 x 1019 pot
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 5
The CNGS neutrino beam
Run Cumulated pot
2008 1.78 x 1019
2009 3.52 x 1019
2010 2 x 1019 (Aug 2010, 50% of run),goal = 4.25 x 1019
2011 minimum goal > 4.5 x 1019 (as in the proposal)
2012 no beam by CNGS?
2013 ?
Typical cycles: CNGS + FT (tests)
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 6
OPERA detector, 150000 ECC 1.25 kton target
~3100 m.w.e., ~1 cosmic / m2 / hour
Target area Muon spectrometer
Two super-modules
Example of a CC event
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 7
Stack of 57 OPERA films, 56 lead plates
The heart of the experiment: the ECC target bricks
Improvement of muon tracking in TT:C. Lazzaro, ETHZ, PhD thesis
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 8
Parallel analyisis of ECC bricks
Validated bricks are sent to the scanning labs 2 scanning stations share the CS scanning load:
- Nagoya (J)- LNGS (I)
11 scanning labs sharethe brick scanning load:
- Nagoya (J)- LHEP Bern (CH)- Napoli, Bari, Salerno, Bologna, Padova, Roma, Frascati (IT)- Dubna (Ru)- Ankara (Tu)
Swiss scanning station scanned the highest number of bricks in Europe
Bern
Salerno
Napoli
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 9
The Swiss scanning station in LHEP Bern
Largest scanning group in Europe19 physicists (Bern + ETHZ)
5 microscopes with full-automatic plate changer+1 in construction
Capability to scan more than 15 bricks/week
...and many efforts to improve the scanning speed even more!
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 10
First OPERA candidate event
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3) Large area scanning
From CS to vertex location
Event topology
1) CS predictions
2) scan-back
4) Full reconstruction of vertices and gammas
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 12
Electron and gamma reconstruction:F. Meisel, LHEP, PhD Thesis
Very careful measurements of the candidate
attachment to the vertices
Following down all particles
Low energies particle identification (/):J. Knüsel, LHEP, PhD Thesis
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Kinematic analysis
10 years old criteria (@Proposal) → Blind analysis
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 14
Background sources
Prompt ~ 10-7/CCCharm from
e ~ 10-6/CC
Double charm ~ 10-6/CCCharmed particle decay
from interactions~ 10-5/CC
negligible
Hadron interactions
~ 10-5/CC
So far, simulation by using FLUKA:
Two possible methods:1) using state-of-the-art of simulations2) measurement by using OPERA dataEvaluation is based on the study of
charm events in a region where no signal is present.
Very nice data/MC agreement
Expected backgroundfor 1-prong hadron channel
= 0.011 events (50% error)
Expected backgroundfor 1-prong hadron channel
= 0.007±0.004 (syst) events
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 15
Signal region
75% of total scanning load among the whole Collaboration is afforded by
LHEP scanning station
interaction vertex
hadron
hadron interaction
The aim is however to measure the background rate with OPERA data directly, by following down hadrons
It needs a huge scanning effort!
LHEP scanning station is leading the analysis
Measuring hadron interaction BG with OPERA events
9 meters equivalent scanned so far
Goal: ~100 m will fully validate (eventually replace) the MC information
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 16
Study of charm contamination and its rejection: T. Strauss, ETHZ, PhD Thesis
Charm background
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Example of charm events
Short decay
Long decay
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 18
e candidate event
Additional physics subject:study -e oscillations
Now 6 candidates
First e event was found at LHEP
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 19
OPERA status
OPERA collected so far about 2 x 1019 pot events (August 2010)
This is reported in:
N. Agafonova et al. [OPERA Collaboration], Phys. Lett. B691 (2010) 138 [arXiv:1006.1623 [hep-ex]]
At the time of the published paper, about 35% of 2008-2009 statistics was analysed. This would comport:
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 20
Conclusions
The OPERA experiment is taking data in the CNGS beam
OPERA collected so far about 2 x 1019 pot events (August 2010)
The analysis of 2008-2009 data is still in progress. The goal is to finish it within the end of 2010 (as it was planned).
The observation of 1 candidate event is the proof of a continuous and hard work and it is an important step towards the discovery of neutrino oscillation in direct appearance mode
The full evaluation of total efficiencies is ongoing
To meet this goal we require to successfully complete data taking in the CNGS beam and perform the analysis of the full data sample
In addition to the seminal and proposal work, to the key managerial duties and to the qualitative and quantitative role in the OPERA Collaboration, swiss groups have a very active role in the OPERA analysis and are also contributing to the ~35% of the european brick scanning load and to the 75% of the whole scanning load for the evaluation of the hadron background
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Backup slides
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2010 CHIPP Annual Plenary Meeting Luca Scotto Lavina – LHEP Bern University 22
Event statistics
Events collected by 2008-2009 run 5391
Brick tagging efficiency times vertex location efficiency: ~60%
Total found neutrino vertices:1921
This is ~60% of the total 2008-2009 run statistics
Events for which “decay search” was completed: 1088 (187 NC)
This is ~35% of the total 2008-2009 run statistics,corresponding to 1.85 x 1019 pot
With the above statistics, and for ∆m223
= 2.5 x10-3 eV2 and full mixing,OPERA expects:
~0.5 events
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Tails of the distributions
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A very interesting event: brick extraction
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e interaction event
24 mm
8 m
m
Em. Shower
E = 4.71.3 GeVNeutrino vertex
IP = ~m