Recent results from the OPERA experiment

Recent results from theOPERA experiment

Maximiliano Sioli (Bologna University and INFN)on behalf of the OPERA Collaboration

SLAC Experimental Seminar - June 22, 2010

The OPERA CollaborationBelgiumIIHE BrusselsBulgariaSofiaCroatiaIRB ZagrebFranceLAPP Annecy, IPNL Lyon, IRES StrasbourgGermanyHamburg, Münster, RostockIsraelTechnion HaifaItalyBari, Bologna, LNF Frascati, L’Aquila, LNGS, Naples, Padova, Rome La Sapienza, SalernoJapanAichi, Kobe, Nagoya, Toho, UtsunomiyaKoreaJinjuRussiaINR Moscow, NPI Moscow, ITEP Moscow, SINP MSU Moscow, JINR Dubna, ObninskSwitzerlandBern, ZurichTurkeyMETU Ankara

2M. Sioli - SLAC Experimental Seminar - June 22, 2010

Outline

• Introduction• The OPERA experiment

– The physics case– Detector description

• Experimental results– Oscillation physics

First nt candidate event

– Non-Oscillation physics Atmospheric muon charge ratio

• Conclusions


Sub. to Physics Letters B (Acc 11/Jun/2010)arXiv:1006.1623

Published in EPJC 67 (2010) 25.arXiv:1003.1907

Introduction

• The OPERA experiment was mainly designed to unambiguously prove the oscillation phenomenon through direct nt appearance– Definitely close of the discovery phase of neutrino

oscillations• The detector - although optimized for beam

neutrino detection - can also be exploited for non-oscillation studies– Cosmic ray physics at the Gran Sasso Lab.

M. Sioli - SLAC Experimental Seminar - June 22, 2010 4

OPERAOscillation Project with Emulsion tRacking Apparatus

5

Long baseline neutrino oscillation experiment:search for tau neutrino appearance at Gran Sasso laboratory

in a quasi-pure muon neutrino beam produced at CERN (732 km)

First direct observation of nm ↔ nt oscillation

M. Sioli - SLAC Experimental Seminar - June 22, 2010

CNGSCERN Neutrino to Gran Sasso beam

• Protons from SPS: 400 GeV/c• Cycle length: 6 s• 2 extractions separated by 50 ms• Pulse length: 10.5 ms• Beam intensity: 2.4 1013

proton/extr.

732 km


dEEEEPEMNN CCDA )()()()(

ttm

m nnnnt

CNGS beam optimized for nt appearance, i.e. optimized for the maximal number of nt charged current interactions: nm flux spectrum above t threshold. Taken into account the nt CC cross section.

nm flux “off peak” w.r.t the maximum oscillation probability.

“off peak”

CNGSCERN Neutrino to Gran Sasso beam

Beam main features

L 732 km<En> 17 GeV

(ne+ne)/nm 0.87%nm / nm 2.1%nt

promptnegligibl

e )E

LΔm.(θ)νtP(νm

2232

232 271sin)2(sin»

Limiting for nm ne searches


CNGS PERFORMANCE

8

2006 0.076x1019 pot no bricks Commissioning

2007 0.082x1019 pot 38 ev. Commissioning

2008 1.78x1019 pot 1698 ev. First physics run

2009 3.52x1019 pot 3693 ev. Physics run

2010 0.60x1019 pot (23 May) 579 ev. Physics run2010

2009

2008

5970 events collected until 23 May 2010 (within 1 in agreement with expectations)

Improving features, high CNGS efficiency (97% in 2008-2009)

2010: close to nominal year; Multi Turn Extraction routinely running

Aim at high-intensity runs in 2011 and 2012

DaysM. Sioli - SLAC Experimental Seminar - June 22, 2010

9

Detection of the nt appearance signal

Two conflicting requirements:

Large mass ~O(kton) High granularity ~1mm resolution

The challenge is to discriminate nt interactions

from nm interactions:identify t leptons via their

decay topology

nm

nm

m-

Decay “kink”

nt

n

t-

~1 mm

nm oscillation

m-

m- nt nm

h- nt n(po)

e- nt ne

p+ p- p- nt n(po)

B. R. ~ 17%

B. R. ~ 50%

B. R. ~ 18%

B. R. ~ 14%

dEEEmEPEMNN CCDA )()(),()( 2

ttm

m nnnnt

signal selection background rejection

ECC concept adopted


10

Emulsion Cloud Chamber concept

8.3 Kg

The brick is the target basic component: 57 nuclear emulsion films interleaved by 1 mm thick lead plates

125.1 mm

99.8 mm Emulsion Resolution:dx = 1 µm dq = 2 mrad

ECC = sequence of emulsion-lead layers

High resolution and large mass in a modular way.

Total number of bricks: ~150000 (1350 tons)


11

Tracks in OPERA emulsions

Passing-through tracks rejection

Vertex reconstruction in the brick

Track segment: aligned clusters

44 mm

15 tomographic views

Track segments found in 8 consecutive plates

Automated emulsion scanning: based on the tomographic acquisition of emulsion layers.

44 mm

Scanning speed: 20 cm2/h

Field of view

390 μm × 310 μm


12

20m

10m

10m

nTarget sections (6.7 m2):29 brick walls (77500 bricks)31 Target Tracker walls (TT)

Magnetic spectrometers (6×10 m2):22 RPC planes 6 drift tube planesB = 1.55 T

Total target mass = 1.35 ktons

Brick selectionCalorimetry

Target SuperModule(side view)OPERA general structure


13

SM2

Veto plane (RPC)

High Precision Tracker(6 drift tube stations)

Bricks (lead + emulsions) and Target Tracker (plastic scintillators)

Instrumented dipole magnet (22 RPC planes in total)

The OPERA detector


14

Detector concept

0 max

p.h.

The brick is the solution to the requirements of high granularity and large mass.Need of electronic detectors in order to: trigger for a neutrino interaction locate the candidate brick muon identification and momentum/charge measurement

hybrid detector needed

n

On-line analysis of electronic data Brick finding algorithm Pb/Em. brick

8 cm


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

15

The first nt candidate

A. Ereditato - LNGS - 31 May 2010 16

OPERA nominal analysis flow applied to the hadronic kink candidates:

• kink occurring within 2 lead plates downstream

• kink angle larger than 20 mrad

• daughter momentum higher than 2 GeV

• decay Pt higher than 600 MeV, 300 MeV if ≥ 1 gamma pointing to the decay vertex

• missing Pt at primary vertex lower than 1 GeV

• Azimuthal angle between the resulting hadron momentum direction and the parent track direction larger than p/2 radians

ANALYSIS


po mass r mass

1st g and 2nd g 90 ± 30 MeV 515 +110-60 MeV

(1stg+3rdg) and 2nd g

110 ± 40 MeV 560 +110-60 MeV

Invariant mass reconstruction

• The event passes all cuts, with the presence of at least one gamma pointing to the secondary vertex, and is therefore a candidate to the t -> 1-hadron decay mode.

• The presence of the charged prong and of two gammas pointing to the secondary vertex allows to attempt to the reconstruction of the r(770) invariant mass from the

t -> p- p0 nt decay mode

• According to the gammas assignment scheme shown before, we have then:


We observe 1 event in the 1-prong hadron topology with a background expectation (assuming a conservative 50% error) of:

0.011±0.005 (syst) events 1-prong (hadron re-interaction) 0.007±0.003 (syst) events 1-prong (charm) 0.024±0.012 (syst) events 3-prongs, m and e decay channels

Considering all decay modes the probability to observe 1 event due to background fluctuations is 4.3%. This corresponds to a statistical significance of 2.03 on the measurement of a first t candidate event in OPERA.

Considering the 1-prong channel only, the background fluctuation has a probability of 1.9%, for a significance of 2.35

OPERA as a cosmic ray detector


Gran Sasso underground lab: 1400 m of rock (3800 m.w.e) shielding, cosmic ray flux reduced by a factor 106 w.r.t. surface, very reduced environmental radioactivity.

OPERA vs previous and current underground experiments:a deep underground detector with charge and momentum reconstruction and excellent timing capabilities (~10 ns).Analyses under way:

Atmospheric neutrino induced muonsCoincidences among experiments (OPERA/LVD)Atmospheric muon charge ratio this talk

1400

m

Atmospheric muon charge ratio• The atmospheric muon charge ratio Rm ≡ Nm+/Nm-

is being studied and measured since many decades– Depends on the chemical composition and energy spectrum of the

primary cosmic rays– Depends on the hadronic interaction feautures– At high energy, depends on the prompt component

• It provides the possibility to check HE hadronic interaction models (E>1TeV) in the fragmentation region, where no data exists

• Since atmospheric muons are kinematically related to atmospheric neutrinos (same sources), Rm constitus a benchmark for atmospheric n computations (background for neutrino telescopes)


The physics of CR TeV muons


m

m

(ordinary) meson decay: dNm/d cosq ~ 1/ cosq

p

K

hadronic interaction: multiparticle production (A,E), dN/dx(A,E) extensive air shower

m

short-lifetimemeson production and prompt decay

(e.g. charmed mesons)Isotropic angular

distribution

detection: Nm(A,E), dNm/dr

transverse size of bundle PT(A,E)

TeV muon propagation in the rock: radiative processes andfluctuations

Primary C.R. proton/nucleus: A, E, isotropic

Analytic predictions• Naive prediction:

– Since charged multiplicity grows with the energy, the extra-charge of the primary proton is diluited and Rm 1 in the HE limit (WRONG!)

• A more elaborate model:– Suppose only primary protons with a spectrum dN/dE = N0E-(1+g)

– Suppose only pions and neglect decays (HE limit)– Consider the inclusive cross-section for pions

– The pion spectrum is then


p

pppp

Ed

dEEEf pinelpp

pp

),(

),()()( )1(pp

E

EEfdEEE

constE ppg

pp

p

p

-

p

p (primary)air

nucleus

– This expression can be simplified under the assumption

and becomes

– Finally we have

Analytic predictions (cont’d)


)(),(~

xfEd

dEEEf pEp

inelpp

pp

pp

pppp

Feynmanscaling

- p

gppp

pZEconstE )1()()( -

1

0

1~

)( dxxxfZ ppg

pp

SpectrumWeightedMoments

-

-

-

p

p

p

p

m

mm p

pmm

p

p

Z

Z

EE

EE

R)()(

)()(

Interpretation of the result• Interpretation of the result

– The result is valid only in the fragmentation region, since in the central region Feynman scaling is strongly violated

– But the steeply falling primary spectrum (g ~ 2.7) in the SWM suppresses the contribution of the central region in the secondary production scaling holds (at least for E < 1 TeV);In other words: each pion is likely to have an energy close tothe one of the projectile (primary CR proton) and comes fromits fragmentation (valence quarks) positive charge

– Rm does not depend on Ep (or Em) nor on the target nature– Rm depends on the primary spectrum g


Neutrons in the primary flux• Further refinements

– Introducing the neutron component in the primary flux (in heavy nuclei) and considering the isospin symmetries:

one obtains:


-- pppp npnp

ZZZZ ,

82.0)np/()np( 00000 »-d

)ZZ/()ZZ1()ZZ/()ZZ(

where

22.111R

pnpppnpp

pppp

0

0

--

-

»d-d

-- pppp

Proton excess

Kaon contribution• At higher energy (>100 GeV) the

contribution of K becomes important• In general, the contribution of each

component to the muon flux Npar = (p, K, charmed, etc.) depends on the relative contributionof decays and interaction probabilities:

where


-

parN

i ii

Nii

NN

N

bZa

Z 1 )(/11)(

qm

mm E

E

)1)(1()()1()(

1

--

gmg

g

i

iii r

iBrraa

)/log)(1)(1())(1)(2()( 2

1

Niii

Niiii r

rbbg

gg g

g

---

2)/( ii mmr m

i = i(q) is the “critical energy”, i.e. the energy above which interactions dominate over decays. Along the vertical (q = 0o) i(0)= mich/ti (h = 6.5 km)

p 115 GeV K 850 GeVX > 107 GeV

q = 0o

q = 60op K

Kaon contribution to Rm

• However, for kaons:

Because of their strangeness (S = +1), K+ and K0 can be yielded in association with a leading barion Λ o Σ. On the other hand, the production of K−,K0 requires the creation of a sea-quark pair s − s together with the leading nucleon and this is a superior order process.

• This leads to a larger Rm ratio at high energy


-- KKK»>> pnp ZZZ

General form for Rm

• Let us consider again the general form for the muon flux

where we have explicited the i(q) dependence on q

where q* is the zenith angle at the production point• The correct variable to describe the evolution of Rm is

therefore Emcosq*

• The Rm evolution as a function of Emcosq* spans over the different sourcesRm = wpRm

p + wKRmK + wcharmRm

charm +…


-

parNi

N

i ii

i

NN

N

bZa

Z 1* )0(/cos11

)(qm

mm E

E

*cos/)0()( qq ii Earth

q*q

POWERFUL HANDLE TODISCRIMINATE MODELS

OPERA (2009): Emcosq ≈ 2000 GeV The (magnetized) experiment withthe largest Emcosq

Cosmic-event reconstruction

• Cosmic-event tagging:– Outside the CNGS spill window

• Dedicated pattern recognition and track finding/fitting:– Cosmic events are passing-through– Cosmic events comes from all directions– Cosmic events may have multiple parallel tracks (in

OPERA 5% of the events are muon bundles)– Different reconstruction philosophy


Pattern recognition• Tracking philosophy

– we know a priori which is the target: single tracks or bundle of tracks almost parallel (RMS is ~1 deg, mainly due to MCS in the overburden)

• Hybrid strategy– global method (Hough Transform) to individuate the event direction– scan the Hough Space and select the slope corresponding to the

maximum used to set the qslice of the slice– local method (pivot points) on slices around the direction

“resolutions” < 1 degboth for zenith andazimuth directionreconstruction


q

Pattern recognition (cont’d)

Real double muon event

31M. Sioli - SLAC Experimental Seminar - June 22, 2010Z

original coordinate plane

q

r1

2

3

Y

ypeak

r

y

Track finding and fitting• Within each slice, build straight lines defined by all possible

couples of external points (pivot points), then search for points aligned with the previous two according to pre-defined tolerances

• Fit the selected points and iterate the procedure to merge or reject extra points

• “resolutions” < 1 deg both for zenith and azimuth direction reconstruction

• Merge the tracks inthe XZ and YZ views 3D track


q

PT track reconstruction


3D tracks are used to “guide”track finding and fitting in the PTsystem: Find the line tangent to the

drift circles with the best c2

250 mm position resolution 0.15 (1) mrad angular resolution

for doublets (singlets) for = 0 (improve for > 0)

Residuals ~250 mm

• In each side of the magnet arm we can reconstruct an independent angle j, j=1,...,6.• Each j can be reconstructed with one station (singlets) or two stations (doublets)• We compute k = i – j , k=1,...,4, angle differences between adjacent station-pairs

– 55% of ’s comes from doublets– 9% from singlets– 36% are mixed

34

Momentum reconstruction


2

2

11

]/)/(exp[1)/(

xz

yzk s

sBedxdE

dxdElp

-

l

B ≡ Bd/l = effective magnetic field

B B

Charge reconstruction

• Charge is reconstructed according to the sign• If each track contributes to multiple angles, a

weighted average is computed– weights = angular experimental errors


4

1

4

1

kk

kkk p

p

4

1

4

1

kk

kkkq

q

k)(1

2 qd

where

• Consider the magnetic field bending and the total deflection spoiling (detector + MCS)

• Requiring />1 we obtain (for =0):– pmax(doublets) = 1.25 TeV

– pmax(singlets) = 190 TeV– pmax(mixed) = 260 TeV

Maximum Detectable Momentum


0

222 0136.021 X

dp

pBd

B3.0

Exact computation at all angles (MC) ~500 GeV/c

Charge mis-identification


Rm = (1.9 ± 0.9) %

Cross-check with beam data

pm

Monte Carlo simulation

• MC simulation used for different purposes:a) Calibrate and correct (unfold) experimental datab) Estimate surface muon energy and

primary-cosmic-ray related quantities• Two MCs used:

a) Parametrized generator- Fast but approximate

b) Full Monte Carlo simulation- Slow but reliable


Monte Carlo simulation (MC1)Generates multiple muon events at the level of the Underground Halls of the LNGS Laboratory

– each primary type and its energy are sampled according to the composition model (MACRO-fit model)

– the direction is sampled isotropically and the corresponding amount of rock overburden is computed (from Gran Sasso map)

– given the primary type, its energy, the direction and the rock, the probability to have nm muons at underground level is computedusing tables obtained from a full MC simulation, the same used to derive the primary composition model SELF-CONSISTENCY

– Then the residual energy for each muon is computed from a parameterized function [PRD 44 (1991) 3543]

– The lateral dispersion Rm of each muon w.r.t. the shower axis is again parameterized according to a full MC simulation

– The muon charge ratio is introduced by hand (Rm = 1.4)


Muon flux

)%3.09.95(1

MC

DATA

RateRate

Monte Carlo simulation (MC2)


• Based on the FLUKA code• Full simulation chain:

– Detailed geometry description (atmosphere, mountain)

– HE hadronic interactions (h-N and N-N) handled by DPMJET

– Primary composition model from APP 19 (2003) 193

– Predictive of the atmosperic muon charge ratio

• Usage:– Surface muon energy estimation– Link between underground variables and

primary cosmic ray parameter

Aknee

A2

Aknee

A1

EE,EKdEdN

EE,EKdEdN

A2

A1

>

g-

g-

EEcut

g~2.7÷3Ecut~3000 TeV

Data pre-selection• Data taken during 2008

CNGS physics run:– from June 18th until November

10th 2008

• The data acquisition was segmented in “extraction periods”of ~12 hours each.

• Each “extraction” wasselected or rejected on the basis of:

– Run stability– Global distributions (see

figure)

• Livetime: 113.4 days• Total number of events:

403069


Data reduction

A set of progressive cuts applied in order to isolate a clean data sample:a) at least one reconstructed angle

(acceptance cut)b) Remove events with large number of PT hits (clean

PT cut)c) Remove events with bendings smaller than the

experimental resolution (deflection cut)c’) Remove events with very large bendings

(effective for pm<5 GeV/c)


Clean PT cut

Remove events with a large number of PT tubes fired (d-rays, secondary interactions, electronic noise etc) can induce wrong matching


M = M() N’ = N - M()

Deflection cut

Tracks with a bending below the experimental resolution are removed:

/ > n, n=3


The robustness of the cut with respect to n was checked, i.e. the results do not depend on n, when n>2

Deflection cut: effects on and h


m+m-

m+m-

w/o deflection cut

with deflection cut

The charge mis-identification h is stronglyreduced.Possible differences between MC andreal h is a source of systematic uncertaintyon Rm will be reported later

h ~ 3%

Data reduction - statistics


DATA MC

evt/day f1 f2 evt/day f1 f2

Acceptance 992 100.0% - 1222 100.0% -

Clean PT 515 51.9% - 959 78.5% -

Deflection 391 39.4% 76.0% 708 58.0% 73.8%

Single m 379 38.2% 96.9% 673 55.1% 95.1%

Multiple m 12 1.2% 3.1% 35 2.9% 4.9%

Quality cuts vs reconstructed pm


No cuts Clean PT

<100 mrad / > 3

Alignment of the PT system• Rm strongly depends on the alignment precision of the PT system• Two stages of correction:

– Mechanical: gross corrections using a theodolite– Cosmic rays: finer corrections using HE muons

(with and w/o magnetic field)• Mis-alignment may have different contributions:

– Global: each PT station can be roto-translated as a whole w.r.t. the master reference frame

• Accounted for with the present statistics– Local: each PT station may have distortions which vary from point-to-

point• Not yet accounted for with the present statistics


Alignment of the PT systemPhase1: Align two stations of a doublet treating them as rigid bodies

- first shifts, in x, y and z- then rotation, in x, y and z

Phase2: Align two doublets on both sides of an iron arm using CR data w/o magnetic field

Phase3: Estimate bending effects


Underground muon charge ratio

• Rm computed separately for the three categories and then unfolded:

• Finally compute Rmunf as the weighted average of the 3 samples:


Nm+ Nm- Rmmeas h Rm

unf

Doublets 13595 9993 1.360 ± 0.018 0.0165 ± 0.0012 1.375 ± 0.019

Mixed 8951 6603 1.355 ± 0.022 0.0403 ± 0.0022 1.393 ± 0.025

Singlets 2181 1704 1.28 ± 0.06 0.064 ± 0.005 1.33 ± 0.05

Rm = 1.377 ± 0.014

)1()1(

hhhh

m

mm --

-- meas

measunf

RR

R 2

2222

)]1([)()1()()21(

hhdhdh

dm

mmm --

-- meas

measmeasunf

RRR

R

Rm computed separately for single and multiple muon events– check of the hypotheis of “diluition” of Rm when proton-Air and

neutron-Air interactions change their relative contributions– in practice: compute Rm when the 3D

multiplicity is > 1, independently on the number of measured charges in the event

Underground muon charge ratio


Nm ‹A› ‹E/A›primary[TeV]

H fraction Np/Nn Rmunf

(2008)= 1 3.35 ± 0.09 19.4 ± 0.1 0.667 ± 0.007 4.99 ± 0.05 1.377 ± 0.014

> 1 8.5 ± 0.3 77 ± 1 0.352 ± 0.012 2.09 ± 0.07 1.23 ± 0.06

Different at 2.4 level: first indication of a “diluition” effect

OK,nm=3

Systematic uncertainty on Rm

a) Mis-alignment of the PT system can be estimated with the “2-arm” test: consider tracks which cross

both arms of a spectrometer. Neglecting energy losses, the two deflections should be the same:


d() 1 - 2 = 0

d() 0.08 mrad

dRm 0.015

Systematic uncertainty on Rm

Consistency checks:• The 4 Rm values, computed separately for each magnet arm,

fluctuates around the average of 0.017, which is below their statistical accuracy (0.03)

• Run with inverted polarity (9 days): Rminverted = 1.39 ± 0.04

b) Charge mis-identification h• estimate dh = hdata – hMC for a subsample of events again with

the “2-arm” test, then extrapolate to the whole sample• the probability that 1 and 2 have opposite sign is related to h

through a function h = h(p), computed via MCdh = 0.007 dRm = 0.007


The total systematic uncertainty is dRmunf(syst) = +0.017, -0.015

Rm as a function of pm

• Rm was computed in bins of pm (underground momentum) and unfolded (bin migrations taken into account with the Bayes method)

• Evolution with pm is compatible with a constant


Rm = a0 + a1 log10 pm

a0 = 1.29 ± 0.06a1 = 0.05 ± 0.03

Rm = c0

c0 = 1.379 ± 0.015

c2/dof = 2.47/1(compatible with a constant)

• The resolution on Em is dominated by fluctuations in the stochastic of the energy loss

• Different attempts to retrieve Em

– Use of the standard (approximate) formula:

– Back-propagation algorithm• Start from pm and back-propagate the track up to the surface, up

– Use of “crude” MC2• Build a table Em = f(h,pm)

Rm as a function of Emcosq*


EEEdhdE )()( -

mm /)/( - heEE (E) (E)

BEST PERFORMANCE

Rm as a function of Emcosq*


Fixing RKp = 0.149 (Gaisser):Rp = ZNp+/ZNp-= 1.229 ± 0.001RK = ZNK+/ZNK-= 2.12 ± 0.03

Analysis update

Further investigatio on the HE point:-Inclusion of 2009 run data-New estimation of the “surface muon energy”-New estimation of charge mis-identification h

Update with 2009 data (preliminary)

• From June 1st until November 23rd 2009: livetime 2009 = 123.2 days


nm ‹A› ‹E/A›primary[TeV]

H fraction Np/Nn Rmunf

(2008)Rm

unf

(2009)Rm

unf

(2008+2009)

= 1 3.35 ± 0.09 19.4 ± 0.1 0.667 ± 0.007 4.99 ± 0.05 1.377 ± 0.014 1.402 ± 0.014 1.392 ± 0.010

> 1 8.5 ± 0.3 77 ± 1 0.352 ± 0.012 2.09 ± 0.07 1.23 ± 0.06 1.20 ± 0.05 1.22 ± 0.04

Discrepancy now at 4.2 level

2008 data 2009 data

New estimation of the “surface muon energy”

• Same as before, but take the MPV of the Landau distribution instead of the mean better resolution and residuals well centered


h (bin 2)

pm (bin 3)

Emsurface

MPV

Log10(h)

Emsurface(GeV)

Log10(pm/GeV)

New estimation of the “surface muon energy”

• Using MC2 the proper binning was computed:


5 bin in log10(Emcosq*) : 2.9 – 4.2(bin width = 2*RMS = 0.26)

New estimation of charge mis-identification h

• Due to the increased statistics, it is now possible to use only doublet data, for which the charge mis-identification can be extracted directly from data (2-arm test)


Re-evaluation of muon Rm vs Emcosq*

• The anomaly in the HE point still present.


Independenton pm

max!

New fit with world survey


Fixing RKp = 0.149 (Gaisser):Rp = ZNp+/ZNp-= 1.219 ± 0.001RK = ZNK+/ZNK-= 2.43 ± 0.04

Conclusions

• First…


Spares

Brick Assembling Machine



Alignment: phase 1

67

Alignment: phase 1, results


Alignment: phase 2 (rotations)


Alignment: bendings


CR stability as a function of data taking

Event number 71M. Sioli - SLAC Experimental Seminar - June 22, 2010

Documents

Recent results from the OPERA experiment