Neutrino Oscillations what next - University of Miami · mixing in 1963 by Cabibbo) 1) ... Luca Stanco - Padova Neutrino Oscillations: what next ? ... Padova Neutrino Oscillations:

Neutrino Oscillations what next ?

( k d t )(some remarks and prospects)

PERSONAL

Luca Stanco – INFN Padova

PERSONAL

1Neutrino Oscillations: what next ? - MIAMI 2010Luca Stanco - Padova

The experimental observation of neutrinooscillationsoscillations

• A touch of physics • A touch of physics

• How the recent history enlightened the path,How the recent history enlightened the path,opening up to new questionsand drives us into the future

• OPERA and MINOS and MiniBooNE

• Expectations… Europe ?


CHOOZ looked for e → oscillations (disappearance)

l Mainly after KamLAND…re-interpretation

of Chooz result in terms of f foscillations of Mass eigenstates

PLB 420 (1998) 397

Gaugeeigenstates

Masseigenstates

PLB 420 (1998) 397

Maki-Nakagawa-Sakata(1962)

Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 3Luca Stanco - Padova 3

Lepton mixing arranged (and quark mixing in 1963 by Cabibbo)

1) Phase violates CP and 2) so phases 1,2 in Majorana picture3) Matrix unitarity if no sterile neutrinoBUT with 3 BIG questions : 3) Matrix unitarity if no sterile neutrinoU w th B G qu n

(1) Quests for 13

(2) Neutrinoless Double Beta Decay

(3) Different experimental results. No straightforward way

Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 4

What is the pattern of neutrino masses?

Log m2

It “probably” looks something like this

m3m3

m223 ~ 2.5 x 10-3 eV2

m1

m2m2

12 ~ 7 x 10-5 eV2

m1


e

What is the pattern of neutrino masses?

Log m2 But it could look like that

m3 m2m3 m2

m1

m1

m2

mm1 m3


e

Even more significant is the absolute scale.Log m

1 eVThis? m

m3m2This? m1

10-1 eV Or that?

m3

What if more

10-2 eV m1

m2 Neutrinos (STERILE) ?


e

Favorite Four-Neutrino scheme: 3+1Log m

1 eV

2 1 V2

10-1 eVm2

SBL ~ 1 eV2

more than m2atm and m2

sol t i dd d

m3

a new mass parameter is added

10-2 eV m1

m2


e

Then what to measure?

Three angles (12, 13, 23)g ( 12, 13, 23) Two mass differences (m2

12, m223)

The sign of the mass difference m2 (±m223)

One CP phase () The source of atmospheric oscillations (detect appearance) The absolute mass scale The absolute mass scale Are neutrino Dirac or Majorana particles (or both)?

Are there more neutrinos (sterile ones)?

the BIG items can be studied with LBL experiments


and be prepared to the unexpected !

There are also experimental controversials …

99.6% prob.99.6% prob.


LSND


%99.4% prob.97.0% prob. Excess (against NULL hypothesis)



Personal Conclusions

MiniBooNE data are themselves not conclusive (not yet conclusive) evidence for anti-neutrino oscillation (not yet conclusive) evidence for none neutrino oscillation There is an excess for low energy neutrinos that may be not there for anti-neu

3+1(2)+CP models can reconcile all appearance data but not the 3+1(2)+CP models can reconcile all appearance data, but not the disappearance ones

Models with sterile neutrinos and exotic physics have been therefore proposed

A fact: the experimental situation is confused!Tensions between neutrino/antineutrino and yes/no steriles Tensions between neutrino/antineutrino and yes/no steriles

Can OPERA/MINOS help?


MINOS actually…Hint for CPT violations ?t o C o at o s


… and no hint for 13 yet …


…while waiting for appearance in OPERA !!!

1998 SK atmospheric neutrino anomaly:deficit of μ ( and not e) with zenith angle dependence: OSCILLATION !!!

CHOOZ: final fl t ( l )

zenith angle dependence OSCILLATION !!!

1999 CNGS beam design

flavour not (only) e ...

2000 DONUT “sees” the in the nuclear

2000 OPERA proposal

emulsions provide an unambiguous evidence for μ→ oscillation in the region of

atmospheric neutrinos by looking for


2000 OPERA proposal atmospheric neutrinos by looking for

appearance in a pure μ beam

The presentThe present


RUN RUN RUN [CNGS]

[OPERA]

CERN

Gran Sasso• From SPS: 400 GeV/c• Cycle length: 6 s• Extractions:

– 2 separated by 50 ms2 separated by 50 ms• Pulse length: 10.5 s• Beam intensity:

– 2.4 · 1013 proton per extrE d f

Cern-Neutrino-to-Gran-Sasso• Expected performance:

– 4.5 1019 pot/yearp.o.t. : protons on target

CNGS: a 17 GeV beam from CERN to Gran Sasso (730 km)



CNGS performanceYear Days

beamPOT SPS

efficiencyEvents Run

2006 0.076×1019 no bricks Commissioning

2007 0 082 1019 38 C i i iyear 2008year 2009year 2010

2007 0.082×1019 38 Commissioning

2008 123 1.78×1019 61% 1698 First physics run

2009 155 3.52×1019 70% 3693 Physics run

POT

year 2010 2009 155 3 5 0 70% 3693 Physics run

2010 187 4.04×1019 81% 4248 Physics run

9639 events collected (within 1 in agreement with expectations from pot)→ 2.1 nominal years in 3 years.

2010y y

2010: 90% of nominal year 4.04×1019 pot

CNGS efficiency: 97% in 2008 20102009 CNGS efficiency: 97% in 2008-2010CERN complex efficiency: 81% in 2010

2008Days


… for tau neutrino CC detection in OPERA

CC interaction + N + X

oscillation

B. R. ~ 17%h n(o) B. R. ~ 49%e B. R. ~ 18% ➙

n(o) B. R. ~ 15%

Decay “kink”

-

oscillation-

Decay “kink”

-

oscillation

h

-

coscillation

c~ 87 m (≈ 600 m of path) (with ≈ 35% of Non-Scaling QE and 65% DIS)

coscillation

no-oscillation

h

no-oscillation

CC NCno oscillation

(with ≈ 11% of Non-Scaling QE and 89% DIS)

no oscillation


OPERA adopts the ECC concept (Emulsion Cloud Chamber):

The OPERA way (the principle)

OPERA adopts the ECC concept (Emulsion Cloud Chamber):

1 mm 1 mm thick Pb plate interleaved with emulsion film with 1 m space resolution

(2 emulsion layers (m thick) poured on a 205 m plastic base)

(2 emulsion layers (m thick) poured on a 205 m plastic base)

emul

sion

Pb

Emulsion layers

e

emul

sion

supp

ort

12.5cm

10.2cm

Track reconstruction accuracy inside emulsion film: x 1 µm 1 mrad

arranged in a “BRICK”:- 57 emulsion sets- 56 Pb layers Plus 2 external emulsion sets for

“i t l ” ith El t i D t C

plus downstream

8.3 kg

“interplay” with Electronics Data,arranged in a white plastic box

CS


The completion of the OPERA construction(*)

OPERA is based on the only proven technology (DONUT) to identify on an

4018

,200

9

event-by-event basis (nucl.emuls.&lead driven by real time detectors). It iscelebrated as a major engineering achievement since it brought suchtechnology to an immense size (1.25 kton)

m”;

JIN

ST, 4

:P04

RN

to G

S

beam

imen

t in

the

CER

The

Ope

ra e

xper

iaf

redd

a et

al.,

“T

1019 sensitive points of measurement !1% to be spanned through…of which 1% to be recorded

(*) R

.Acq

ua of which 1% to be recorded…


Global efficiency 0-~

Event statistics (2008-2010 runs)

Global efficiency 0 Brick tagging efficiency * 1-~ <Brick extracted per event> 1.45vertex location efficiency all :

Interaction in the target

Events with at least 1 brick extracted

E h lEvents with a positive CS result

Interactions located in the bricks

Decay Search completed StatDecay Search completed

PER

Statavailable

OPERAis here


ECC bricks : standalone detectors :e and detection and 0 mass reconstruction

1602 E.M. showers ~ invM MeV

8 1

0.5 E GeV

8.1 E GeV


EM shower energy measured by NN ‐ Shower longitudinal development‐ Coulomb multiple scattering

0 mass resolution (real data)

35 pairs ~ 45%35 pairs

0Importance of efficient detection and precise mass reconstruction

0 0

0

1. . . 1 37% 75% . . 0

2.

p p

or of

Hadron kink B.G. reduction:

B R h B R h

h N h X h N h X


- e oscillations a e candidate event

eHowever difficult because ~1% beam contamination


0e o e e d cu t because % bea co ta at o

and compatible with in atmospheric sector.Improving current upper limit on is potentially at e .r ach

e

The The candidate eventcandidate event


June 2010

Events statistics used for this study

Neutrino vertices found: 1617

Events for which “decay search” is completed: 1088(187 NC)

Thi i 35% f th t t l 2008 2009 t ti ti This is ~35% of the total 2008-2009 run statistics, corresponding to 1.85 x 1019 pot

With above statistics @ m2 = 2 5 x10-3 eV2 and full mixing : With above statistics @ m223 = 2.5 x10 3 eV2 and full mixing :

expected ~ 0.5 events


Muon-less event 9234119599 on 22 August 2009, 19:27 (UTC)(as seen by the electronic detectors)


Event reconstruction (1)


Invariant masses of decay products and nature of the event

• Event passes all selection cuts candidate to 1-prong hadron decay.

• Invariant mass of the two consistent with mass.

• Invariant mass of the system compatible with (770) mass

o mass mass

p

120 ± 20 ± 35 MeV 640 +125-80

+100-90 MeV

Likely decay mode:

B.R. ( ) ≈ 25%


( )

Statistical Considerations (1)

Background expectation in 1-prong hadron decay channel

0.011 events (hadron re-interactions)0.007 events (charm)

assume conservative 50% error on each component0 018 ± 0 007 (syst ) events 1 prong hadron0.018 ± 0.007 (syst.) events 1-prong hadron

Background expectation all decay modes: 1-prong hadron, 3-prongs + 1-prong μ + 1-prong e :p g p g p g μ p g

0.045 ± 0.020 (syst.) events considering all decay modes

Probability to observe 1 event due to bck fluctuation in 1-prong channel: 1.8%

Statistical significance on the measure of a first candidate event: of 2.36


Considering all decay modes, the background fluctuation probability is 4.5% and thesignificance is 2.01 .

Statistical Considerations (2)

For m223 = 2.5 x 10-3 eV2 and full mixing are expected

0.54 ± 0.13 (syst.) CC events in all decay channels and( ) h 1 h d d h l0.16 ± 0.04 (syst.) CC events in the 1-prong hadron decay channel

and 1 event is observed in 1-prong hadron channel.

This excludes m223 > 7.5 x 10-3 eV2 (full mixing) @ 90% CL


OPERA: tau physics search potential

Full mixing, 5 years run, 4.5x1019 pot/year and MD =1.3 KtonEfficiency before identification: trigger x brick x geom x vertex location= 99% x (≥70%) x 94% x 90%

Expected backgrounds: Occur if primary muon isnot detected and possible

Charmed particles produced in CC and NC interaction Hadron reinteractions in lead Large angle μ scattering: muons produced in CC events 0 mis identification

pwrong charge measurementof secondary muon. MuonID is very crucial issuefor the experiment!

0 mis-identification …


Questions to OPERA:Questions to OPERA:

1. Does the – oscillation exist ?

2. Is it consistent with expectation ?

1. Significance of TAU observation in OPERA

We compute it as function of observed EVENTS(instead of the canonical dependence on LUMINOSITY)


the obtainable significance is quite fluctuating !

# ***

evidence

observation

indication

evidence

# N N

but background is an important issue !


*** NOTE: obtained with OPERA proposal in 2001 (conservative result)


From L. Stanco, arXiv:1006.4826 – June 2010 (conservative result)

2. “Coherence” of the OPERA oscillation measure

# “distant” from MINOS

Need > 2012 runs !!5.3x1019 p.o.t

13 7 101913.7x1019 p.o.t15.5x1019 p.o.t20.5x1019 p.o.t90% C.L.

95% C.L.

# of observed events

FEW events: difficult but affordable (conservative result)


(conservative result)

From L. Stanco, arXiv:1006.4826 – June 2010

OPERA expectations (personal view) With 2008-10 runsOPERA hopes to confirm at a not so large probab.tau appearance with a OR to exclude tau appearance! reasonable probability

The Collaboration will publish soon (any of) the results over 2008-09

RUNS 2011-2012 expectations

2 * 4 5E19 pot (with LHC permit) 2 * 4.5E19 pot 9000 more nu interactions in OPERA bricks

(with LHC permit)

Just a private h pe: find sh rtly few taus and try t

Main job: pull down the background


Just a private hope: find shortly few taus and try to switch to anti-neutrino mode (but lower and higher bck)

The near futureThe near future


Lot of activities at CERN during last year…


In the near future there are at least 3 possibilities:p

- refurbishing of PS- new neutrino beam from SPS new neutrino beam from SPS - new CNGS

Let us have a look at the 1rst possibility


Two detectors at the PS neutrino beamBack to the (in)famous ( )P311 rejected proposal

Two positions may be foreseen for the detection of the neutrinosThe far (main) location at 850 m from the target: L/E ~ 1;


The far (main) location at 850 m from the target: L/E 1; The near location at a distance of 127 m from the target: L/E 0.15

Small neutrino beam at CERN” e.g. at PS

proposal: a near detector scintillator based and a far detector Liquid Argon based

Enough to do or die for the LSND effect

Enough to measure cross-sections in LArg and compare with Enough to measure cross sections in LArg and compare with scintillator with high precision.

Enough to perform a detailed scan of low energy cross-sections pass muon and pion threshold.

Alain Blondel 28 September 2010 NEU2012 disc ssion

sect ons pass muon and p on threshold.

Should we try ? (chance of CERN refusal are not negligible)

Alain Blondel 28 September 2010 NEU2012 -- discussion

Even better why not 2 near detectors (1rst scint. and 2nd Liq-Ar) whether the 2nd one may be easily funded ?


whether the 2 one may be easily funded ?

The possible PS-Neutrino-Facility


Possible Sterile Neutrino Experiment Layout


Sterile Neutrino Experiment Requirements


Expected Neutrinos prodution

and flux rate of intrinsicElectron neutrinos electron background


(arXiv:0909.0355) C. Rubbia et al., study and proposal

S h f l diff f l lik ifi i i Search for spectral differences of electron like specific signatures in two detectors but at two different neutrino decay distances.

In absence of oscillations apart some beam related small spatial corrections In absence of oscillations, apart some beam related small spatial corrections, the two spectra are a precise copy of each other, independently of the specific experimental event signatures and without any Monte Carlo comparison.


(arXiv:0909.0355)

beam anti beam

Expected sensitivity for the proposed experiment exposed at the CERN-PSneutrino beam (left) for 2.5 1020 pot and twice as much for anti-neutrino


( ) p(right) . The LSND allowed region is fully explored both for neutrinos. Theexpectations from one year of at LNGS are also shown.

Conclusions• Neutrinos mass and oscillations new historyy

(many results in last 10 years but still far from settling them)

• Matrix of leptonic mixing clue issue

MNS elements: more measurements, better resolutions... MiniBooNE/MINOS/OPERA challenges:M n NE/M N / E cha ng

1) Collect more statistics2) Confirm the taus ! Measure 13 (if > 70)

/3) Find/Exclude STERILE presences4) Disentangle the physics measurements !5) Confirm the unexpected !) p

NEXT few years exciting (and unclear)FAR future does really exist out of approved facilities ?


FAR future does really exist out of approved facilities ?(amazingly similar to present Politics’ situation in Italy)

Documents

Neutrino Oscillations what next - University of Miami · mixing in 1963 by Cabibbo) 1) ... Luca Stanco - Padova Neutrino Oscillations: what next ? ... Padova Neutrino Oscillations: