Measurement of the neutrino velocity with the OPERA detector in the CNGS beam

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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

http://www.bo.infn.it/

/57G.Sirri - INFN BOLOGNA 2

• 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

TAM, Venice 04/03/2013


OPERA Experiment CNGS Neutrino Beam


/57

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

TAM, Venice 04/03/2013 4G.Sirri - INFN BOLOGNA

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


OPERA: Oscillation Project with Emulsion tRacking Apparatus


CNGS CERN Neutrino to Gran Sasso beam


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

/57TAM, Venice 04/03/2013 G.Sirri - INFN BOLOGNA 7

CNGS

targetmagnetichorns

decay tunnel

hadron absorber

muon detector pit 1

muon detector pit 2


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


/57G.Sirri - INFN BOLOGNA 9 /57

3.50


730 km


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


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


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



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



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



«internal» and «external» events



just few slides about neutrino oscillations…



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


detection technique


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.



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


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


𝜏−→h−𝜈𝜏

Phys. Lett. B 691(2010)138

Oscillation Results: First candidate



2° tau candidate

𝜏−→h+¿ h−h−𝜈𝜏¿

NEUTRINO 2012

Oscillation Results: Second candidate



Neutrino TOF measurements



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



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


Principle of the neutrino velocity measurement

𝒗𝝂=𝒙𝟐−𝒙𝟏

𝒕𝟐−𝒕𝟏=𝜟𝒙𝜟𝒕

long baseline needed for high accuracy

Observed Neutrino Event time Profile


already existingsystem (not enough

accurate)

newsystem

Time-transfer Time-transferequipment equipment

CERN-LNGS Synchronization

already existingsystem (not enough

accurate)


PolaRx2e, calibrated by METAS (Swiss metrology institute)


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



Result: TOF time-link correction (event by event)



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


[http://operaweb.lngs.infn.it/Opera/publicnotes/note134.pdf]


30-90 cmWLS

FPGA


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


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


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


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



BCT Target Decay TunnelSPS

CERN Timing

Kickersignal

743.40 m

protons π,K ν

ts1

CTRI

BCT


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


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



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



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


8.3 km fiberCTRICTRI

WFD


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)


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



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



Cross-Checksduring 2011 winter shutdown



+ ~74 ns

LNGS

Dedicated campaign Dec11-Feb12

OPERA M.C.


• 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


ESAT2000

CTRI


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]


is flat ± 3.7 ns


Details and updated results in :


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


Geodesy



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



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]



Data analysis Statistical analysis (2009-2011 data)



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


•  ~1020 pot•  7235 internal events•  7988 external events


•  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]



Data analysis 2011 bunched-beam analysis



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



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



Data analysis 2012 bunched-beam analysis



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)


New measurements with a short-bunch narrow-spacing proton beam (2012)


Improvements in the Timing System



New Calibration Delays


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


Four Different (correlated) analysis


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


Final OPERA Results


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.)


Other Experiments


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


• 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



Thank you


Measurement of the neutrino velocity with the OPERA detector in the CNGS beam

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