measurement of the neutrino velocity with the opera detector in the cngs beam
DESCRIPTION
Measurement of the neutrino velocity with the OPERA detector in the CNGS beam. Gabriele Sirri Istituto Nazionale di Fisica Nucleare BOLOGNA, ITALY on behalf of the OPERA COLLABORATION. Time and Matter , Venice , 04 March 2013 . Contents. OPERA Experiment and CNGS Neutrino Beam - PowerPoint PPT PresentationTRANSCRIPT
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Time and Matter, Venice, 04 March 2013
Measurement of the neutrino velocity with the OPERA detector in the CNGS beam
Gabriele SirriIstituto Nazionale di Fisica NucleareBOLOGNA, ITALY
on behalf of the OPERA COLLABORATION
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• OPERA Experiment and CNGS Neutrino Beam• Neutrino TOF measurements• Geodesy• Data analysis
– Statistical analysis (2009-2011 data) – 2011 bunched-beam analysis – 2012 bunched-beam analysis
• Conclusions
Contents
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OPERA Experiment CNGS Neutrino Beam
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OPERA Collaboration
LAPP AnnecyIPHC Strasbourg
INR MoscowNPI MoscowITEP MoscowSINP NSU Moscow
IRB ZagrebBari BolognaLNF Frascati L’Aquila LNGSNapoliPadovaRoma Salerno
LHEP Bern IHE Brussels Hamburg
JINR Dubna
AichiTohoKobeNagoyaUtsunomiya
Technion Haifa
METU Ankara
Jinjiu
International collaboration of 150 physicists ∼from 28 institutions
and 11 countries
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http://operaweb.lngs.infn.it/
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Physics goal detection of oscillation in direct appearance mode in channel
Signature identification of lepton from CC interaction
Basic principle long baseline beam beam energy to maximize apperance and CC interactionsat the atmospheric neutrino scale eV
Requirements - high target mass ( kt)
- high spatial resolution ( 1 μm)- low background rate
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OPERA: Oscillation Project with Emulsion tRacking Apparatus
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CNGS CERN Neutrino to Gran Sasso beam
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730 Km
CERN
LNGS
In addition: the experiment is well suited to determine the neutrino velocitywith high accuracy throuhg the measurements of the Time Of Flight and the distance between the source of CNGS neutrino beam at CERN and the OPERA detector at LNGS
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CNGS
targetmagnetichorns
decay tunnel
hadron absorber
muon detector pit 1
muon detector pit 2
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p + C (interactions) p+, K+ (decay in flight) m+ + nm
vacuum
800m 100m 1000m 67m26m
Scheme for production of neutrinos
(graphite)
Two extractions separated by 50 ms, each pulse length: 10.5 msProton intensity: 2 x1013 protons on target (p.o.t)/extractionExpected performance: 4.5x1019 p.o.t./year~ pure muon neutrino beam (<E> = 17 GeV) travelling through the Earth’s crust →LNGS
SPS LNGS
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3.50
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730 km
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Beam parameters
<> 17 GeV
p.o.t./year
Beam Contamination (interaction rates in OPERA)
)/ 0.89% , 0.06%
2.1 %
prompt negligible
nominal intensity in 5 years
expected identified by OPERA: 7.6 signal 0.8 background
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CNGS Beam Performance
[New Journal of Physics 14(2012)033017]
production threshold (3.5 GeV) high energy beam “off peak" w.r.t. maximum oscillation prob. (1.5 GeV)
... and ~20000 in-target events
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The LNGS underground physics laboratory
OPERA
CNGS
1400 m
1400 m rock coverageCosmic µ reduction = 10-6 (1 µ/m2/h)Underground area: 18 000 m2
External facilitiesEasy access800 scientists from 25 countries
Research lines• Neutrino physics
(mass, oscillations, stellar physics)• Dark matter• Nuclear reactions of
astrophysics interest• Gravitational waves• Geophysics• Biology
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wall
Pb/emulsionSM1 SM2 brick wall
scintillatorstrips
ν brick(56 Pb/Em.)
8 cm(10X0)10 X
Target Tracker0
+ brick walls(2x31) muon spectrometer 150000 bricks
(1.25 kt)(RPC + drift tubes) 8.3kg
The OPERA detector
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Target Tracker plasticscintillator strips
(26.4 mm), σ~8 mm
The spectrometersDipole magnet + Drift tubesRPC (inner tracker) (precision tracker)
y Inner tracker coilx (RPC in magnet,
σ ~ 13 mm)
12 Feslabs trigger to PTin total
8.2
m
Fe RPC(5 cm)
slabs
62 walls (496 modules)7.5x7.5 m2
Hamamatsu multianode PMTs (64 channels)
Precision TrackerB= 1
.55
T
base Tube: vertical, =38∅mm, length=8mσ<0.5 mm
The Electronic Detectors
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«internal» and «external» events
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just few slides about neutrino oscillations…
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Event-by-event direct observation of the τ lepton decay
Topology Decay mode B.R.
o Micrometric resolution achieved to detect the τ decay kink o Target segmented in small units called «bricks». Brick: 57 layers of nuclear emulsion interleaved with 56 layers of lead1 mm thick. o Initial total target mass ~ 1.25 kt (about 150000 bricks)
10X0
Emulsion Cloud Chamber
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detection technique
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The automatic emulsion scanning
Developedgrains
frame
2-3 µm
15-16 frames/45 microns
1. S-UTS automatic microscopes generation (Japan)2. European Scanning System.
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CNGS data taking
Bunched beam run periods2011 22/10 to 6/112012 10/05 to 24/05
integrated intensity of 18.2x p.o.t.
Event location in emulsion bricks
located neutrino interactions
4898
Fully analyzed events 4190
candidate events 2
expected 2.1
BG expected 0.2
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Data Analysis Progress
Run Proton on Target
(p.o.t.)
In-target events
2008 1.8 · 1019 16982009 3.5 · 1019 35572010 4.0 · 1019 39122011 4.8 · 1019 42102012 3.9 · 1019 3493
Preliminary
In target ev.
located
extracted
scanned
Preliminary
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𝜏−→h−𝜈𝜏
Phys. Lett. B 691(2010)138
Oscillation Results: First candidate
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2° tau candidate
𝜏−→h+¿ h−h−𝜈𝜏¿
NEUTRINO 2012
Oscillation Results: Second candidate
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Neutrino TOF measurements
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FNAL experiment (Phys. Rev. Lett. 43 (1979) 1361)
high energy (En > 30 GeV) short baseline experiment. Tested deviations down to |v-c|/c ≤ 4×10-5 (comparison of muon-neutrino and muon velocities) at 95% C.L.
SN1987A (see e.g. Phys. Lett. B 201 (1988) 353)
electron (anti) neutrinos, 10 MeV range, 168’000 light years baseline.|v-c|/c ≤ 2×10-9 at 95% C.L.Performed with observation of neutrino and light arrival time.
MINOS (Phys. Rev. D 76 072005 2007)
muon neutrinos, 730 km baseline, Eν peaking at ~3 GeV with a tail extending above 100 GeV. (v-c)/c = (5.1 ± 2.9) ×10-5 at 68% C.L. (significance 1.8 s).
Past experimental results
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tagging of neutrino production time
tagging of neutrino interaction time
Precise Time link ~ 2 nsec by GPS Common View Mode
Operation + All Possible correctionsPolaRx2e +Cs atomic Clock
Precise Distance Measurement
by GPS + Optical Geodesy measurement
𝝂𝝁BCT OPERA
731278.0 ± 0.2 m
GPS Satellite
Observed Proton Time Profile = Neutrino Production Time Profile
Predicted Neutrino Event Time Profile
C
CERN LNGS
PolaRx2e +Cs atomic Clock
18/26
BCT
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Principle of the neutrino velocity measurement
𝒗𝝂=𝒙𝟐−𝒙𝟏
𝒕𝟐−𝒕𝟏=𝜟𝒙𝜟𝒕
long baseline needed for high accuracy
Observed Neutrino Event time Profile
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already existingsystem (not enough
accurate)
newsystem
Time-transfer Time-transferequipment equipment
CERN-LNGS Synchronization
already existingsystem (not enough
accurate)
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PolaRx2e, calibrated by METAS (Swiss metrology institute)
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Standard GPS operation:resolves x, y, z, t with ≥ 4 satellite observations
Common-view mode (same satellite for two sites, for each comparison): x, y, z known from former dedicated measurementsdetermine time differences of local clocks (both sites) w.r.t. the satellite, by offline data exchange
730 km << 20000 km (satellite altitude) similar paths in ionosphere(and make use of more than one frequency !)
GPS Common View Mode
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Result: TOF time-link correction (event by event)
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Independent twin-system calibration by the Physikalisch-Technische Bundesanstalt
High accuracy/stability portable time-transfer setup @ CERN and LNGS
GTR50 GPS receiver, thermalised, external Cs frequency source, embedded Time Interval Counter
Correction to the time-link:tCERN - tLNGS= (2.3 ± 0.9) ns
Blue: Code based common-view (P3 ionosphre free linear combination),fixed positions, TR position estimated by PPP
Red: Precise Point Positioning (PPP)
Relative calibration of CERN-to-LNGS GPS time link
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[http://operaweb.lngs.infn.it/Opera/publicnotes/note134.pdf]
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30-90 cmWLS
FPGA
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LNGS Timing
FPGA 10 MHz
O/E
ESATGPS2
OPERAMasterClock
GPS Antenna
T10
Ts
ROC
PMT
TRIGGER
DAQ RESETevery 600 PPmS
MC PPmS
TMC
N*10 nsM*0.6 s
20 MHz
HERTZ
100 MHz
DAQTime Stamp
121 …122…123…
ESAT PPmS8 km
Exte
rnal
Lab
Und
ergr
ound
OPERA Event Time StampingTriggers from Target Tracker : time-stamped by an FPGA (100MHz)
DAQ cycle : 0.6 s ; Reset and Clock provided by OPERA Master Clock (hall C)
FPGA increments two counters: M: coarse counter incremented by DAQ RESET . N : fine counter which increments every 10 ns
When a trigger is issued the FPGA assigns to it the reading of the two counters.
DAQ Time-Stamps delayed by the time to transfer the GPS information to the FPGA (red path).
Master Clock oscillator:10 MHz VECTRON OC-050 (stability 10-12/s)
<59.6 > ± 3.8 ns
Scint. Strip
TEVENT
CTRI
PolaRx2e
GPS Antenna
PPS
121 …122…123…
CTRI Log
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PatchPanel
8 km
ESATGPS2
LASER TX
ESAT PPmS
PatchPanel
Splitter
HERTZ
Fibe
r 23
LNGS
Ext
erna
l Lab
LNGS
Und
ergr
ound
OPERAMasterClock
5 m Fiber
MC PPmS
5.9 ns
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Time delay from the external Lab to the OPERA Master Clock
To FEBs
GPS Antenna
LVDBOREXINO
TX
tBtA
ICARUS
Time delay tA between 2 reference points:
HERTZ reference of the GPS2 ESAT UTC time.
MC PPmS generated by the OPERA Master Clock,
synchronous with the ESAT PPmS
The “two-way” technique
measure : tA – tB and tA + tB
TX
RXScope
RXScope
tA – tB
tA + tB
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OPERA data: narrow peaks of the order of the spill width (10.5 µs)
Negligible cosmic-ray background: O(10-4)
Offline selection procedure kept unchanged since first events in 2006
cosmics
D. Autiero - CERN - 23 September 2011
Tagging Neutrino INTERACTION Time
@LNGS Typical neutrino event time distributions w.r.t kicker magnet trigger pulse
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BCT Target Decay TunnelSPS
CERN Timing
Kickersignal
743.40 m
protons π,K ν
ts1
CTRI
BCT
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Polarx2e
Wave Form Digitizer (WFD)
XLi
CTRI
PrevessinCentr. Cont.
Room
HCA442
General Machine Timing (GMT)
High PrecisionGPS
time
CTRI in HCA442tags the reference and the kicker signaland produces a replica of kicker to trigger the WFD
Typical waveform (2011)
Shape reflects the PS extraction
CTRI in Prevessincompares GPS Clock Reference Signal
Beam CurrentTransformer : a toroidal transformercoaxial to the beam signal current
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CNGS
SPS
2010 calibration with Cs clock
Proton timing by Beam Current Transformer
Fast BCT 400344 (~ 400 MHz)
Tagging Neutrino Production Time = Proton Timing
Proton pulse digitization:
• Acquires DP110 1GS/s waveform digitizer (WFD)
• WFD triggered by a replica of the kicker signal
• Waveforms UTC-stamped and stored in CNGS database for offline analysis
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Dedicated beam experiment:BCT plus two pick-ups (~1 ns) using the LHC beam (12 bunches, 50 ns spacing)
WFD
: derived by measurement and survey
ZOOM
result: signal comparisonafter ΔtBCT compensation
Ampl
itude
[a.u
.]
LHC beamtime [ns]time [ns]
BCT Calibration
ns
BPK1 BPK2 BCT
WFD𝑡 4
𝑡 3𝑡 2𝑡1
SPSCNGS
LHC
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24.5
BCT OPERATarget Decay TunnelSPS
LNGSCERN
Time Corrections (ns)
41068.6
4262.9
59.6
10085.0
30
580
2.3
Controller Board FPGA
TTstrip
CTRI
Kickersignal
GPSReceivers
BASELINE = 731278.0 ± 0.2 m
p π,K ν
* C
ts1
ts2
other time corrections
OPERA M.C.
BCT
time
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8.3 km fiberCTRICTRI
WFD
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2.00.2
2.0
1.0
5.0
3.7
1.0 1.0
3.0 2.3
1.7
BCT OPERATarget Decay TunnelSPS
LNGSCERN
Systematic Uncertainty (ns)
Controller Board FPGA
TTstrip
CTRI
Kickersignal
WFD
GPSReceivers
p π,K ν
CTRICTRIOPERA
M.C.
BCT
time
Baseline: 0.67 (20 cm)
Meson decay point: 0.2 (exponential, 1 side)Interaction point of external events: 2.0 (flat, 1 side)
PMT
0.67
8.3 km fiber
The overall systematic uncertainty wascomputed numerically by taking into account the individual contribution andtheir corresponding probability distribution(gaussian if not written).
Overall systematic uncertainty
( -8.0 , + 8.3 ) ns
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5.5 ns (OPERA)
Summary of time corrections (2011)
5.5 ns (CERN)
Item Time Correction (ns) Method
1 CERN UTC distribution (GMT) 10085 ± 2• Portable Cs• Two-ways
2 WFD trigger 30 ± 1 Scope
3 BTC delay 580 ± 5 • Portable Cs• Dedicated beam experiment
1 CERN-LNGS intercalibration 2.3 ± 1.7 • METAS PolaRx calibration• PTB direct measurement
1 LNGS UTC distribution (fibers) 41068.6 ±3.7 • Two-ways (from new cross checks during 2011 winter shutdown)
2 OPERA master clock distribution
4262.9 ± 1 • Two-ways• Portable Cs
3 FPGA latency, quantization curve
24.5 ± 1 Scope vs DAQ delay scan (0.5 ns steps)
4
Target Tracker delay (Photocathode to FPGA)
50.2 ± 2.3 UV picosecond laser
Target Tracker response (Scintillator-Photocathode,trigger time-walk, quantisation)
9.4 ± 3UV laser, time walk and photon arrival time parametrizations, full detector simulation
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Cross-Checksduring 2011 winter shutdown
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+ ~74 ns
LNGS
Dedicated campaign Dec11-Feb12
OPERA M.C.
Controller Board FPGA
• Two identified issues:
Faulty connection of the optical fiber to the Master Clock artificially increasing the neutrino anticipation by ~74 ns.
Internal Master Clock frequency off by Δf/f = 1.24x10-7 (124 ns/s) artificially decreasing the neutrino anticipation by ~15 ns (DAQ time bin 10 ns → 9.99999877 ns).
• Time when "anomalous" conditions occurred during data taking and stability of these conditions subjected to "a special investigation"
Test of the delay of 8.3 km long optical fiber and of the DAQ internal delays
8.3 kmfiber
- ~15 ns
Frequency distribution
4TT
strip
OPERAν
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ESAT2000
CTRI
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Coincidences using horizontal cosmic muons(Joint OPERA-LVD analysis)
the fiber problem started in 2008 and lasted until end of 2011 when it has been well connected to the OPERA Master Clock (considered data period: 2009-2011). New systematic uncertainties : ± 3.7 ns.
the oscillator is running at a frequency higher than the nominal since 2008. (0.113 ±0.020) ppm
Time drift confirmation
Tim
e di
ff. in
DAQ
cyc
le (n
s)How stable were the «anomalous» conditions ?
"anomalous" period
74 n
s
OPE
RA-L
VD ti
me
dela
y
~ 160 m «Teramo» µ
DAQ cycle (0.6 s)
[Eur. Phys. J. Plus (2012) 127: 71]
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is flat ± 3.7 ns
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Details and updated results in :
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2012 February 23, Press Release The OPERA collaboration has identified two issues …
2012 March 12, Report from the OPERA Collaboration to the scientific committees
http://operaweb.lngs.infn.it/Opera/ptb/pubref/pubref/OPERAReport0312toSC.pdf
2012 March 28, Mini-Workshop - "LNGS results on the neutrino velocity topic"
http://agenda.infn.it/materialDisplay.py?materialId=slides&confId=4896
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Geodesy
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GPS
GPS
Dedicated measurements at LNGS: July-Sept. 2010(Rome Sapienza Geodesy group)
2 new GPS benchmarks on each side of the 10 km highway tunnel
GPS measurements ported underground to OPERA
Geodesy at LNGS
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Resulting distance (BCT – OPERA reference frame)(731278.0 ± 0.2) m
CERN – LNGS measurements (different periods) combined in the ETRF2000 European Global system, accounting for earth dynamics (collaboration with CERN survey group)
Cross-check: simultaneous CERN-LNGS measurement of GPS benchmarks, June 2011
LNGS benchmarksIn ETRF2000
Combination with CERN Geodesy[http://operaweb.lngs.infn.it/Opera/publicnotes/note132.pdf]
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Data analysis Statistical analysis (2009-2011 data)
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δt= TOFc- TOFν
Positive (negative) δt neutrinos arrive earlier (later) than light
statistical error evaluated from log likelihood curves
Maximised versus δt:
• For each neutrino event in OPERA proton waveform of the corresponding extraction
• Sum up and normalize: PDF W(t) separate likelihood for each extraction
Analysis Method
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• ~1020 pot• 7235 internal events• 7988 external events
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• no seasonal effect• no day/night effect• no energy dependence• no beam intensity effect• no difference between internal and external events.
extraction 1 extraction 2
New results
Total systematic uncertainties computed numerically by taking into account the individual contributions and their corresponding p.d.f.
[JHEP10(2012)093]
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Data analysis 2011 bunched-beam analysis
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2009-2011 October 22 to November 6 (2011)
• TOFν for each detected neutrino• 4x1016 pot• 6 internal events• 14 external events• events evenly distributed in thefour bunches of the extraction• mode not compatible with OPERAoscillation program.
• statistical method for TOFν extraction• ~1020 pot• 7235 internal events• 7988 external events
Test with short-bunch wide-spacing proton beam
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In agreement with the previous value (6.5±7.4 ns)
Excludes possible biases affecting the statistical analysis based on the proton waveforms
Indicates the absence of significant biases due to:• cumulative response of beam line to long proton
pulses• pulse duration effects in the BCT response.
20 events δt=1.9±3.7 ns (same syst. errors)
[JHEP10(2012)093]
Test with short-bunch wide-spacing proton beam
Results with the RPC data
16 events
Results with the Target Tracker data
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Data analysis 2012 bunched-beam analysis
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10 to 24 May 2012
Δt=100 nsσ~1.8 ns
• 1 extraction per CNGS cycle• 4 batches per extraction• 16 bunches per batch• p.o.t.: ~2 x 1017 (2 weeks)
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New measurements with a short-bunch narrow-spacing proton beam (2012)
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Improvements in the Timing System
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New Calibration Delays
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4.4 ns (OPERA)
1.7 ns (CERN)
Item Time Correction (ns) Method
1 CERN UTC distribution (GMT) 10077.8 ± 1 • Portable Cs• Two-ways
2 WFD trigger 26.6 ± 1 Scope
3 BTC delay 583.7 ± 1 • Portable Cs• Dedicated beam experiment
1 CERN-LNGS intercalibration 2.3 ± 1.7 • METAS PolaRx calibration• PTB direct measurement
1 LNGS UTC distribution (fibers) 41067.0 ±1 • Two-ways
2 OPERA master clock distribution 7046 ± 1 • Two-ways
3 FPGA latency, quantization curve
24.5 ± 1 Scope vs DAQ delay scan (0.5 ns steps)
4
Target Tracker delay (Photocathode to FPGA)
50.2 ± 2.3 UV picosecond laser
Target Tracker response (Scintillator-Photocathode,trigger time-walk, quantisation)
9.4 ± 3UV laser, time walk and photon arrival time parametrizations, full detector simulation
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Four Different (correlated) analysis
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using TT(earliest hit)
using RPC(all muon hits)
RPC usingTrigger Boards
using TT andall muon hits
1-3 Standard DAQ4 Timing Board System
106 Events in total (4 identified as
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Final OPERA Results
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Combining method 2 and 4 (smallest errors and almost uncorrelated) :
ns
Summing in quadrature the systematic errors, separately for and contributions:
ns
ns
Limit on the deviation from the speed of light (90% C.L.)
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Other Experiments
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All experiments consistent with no measurable deviation from the speed of light for neutrinos:
Borexino: ns
PLB716(2012)401
ICARUS: ns
JHEP11(2012)049
LVD: ns
PRL109.070801
OPERA: ns
JHEP01(2013)153
ns
from: P. Adamson, Neutrino 2012, Kyoto
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• OPERA updated the result announced in 2011
• The two issues found affecting the 2011 analysisunderstood and new systematic errors evaluatedJHEP10(2012)093 .
• A new short-bunch narrow-spacing proton beam run performed in 2012
• The new OPERA result from 2012 data is:
• Results published in JHEP01(2013)153 .
Conclusions
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Thank you
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