neutrino oscillations what next - university of miami · mixing in 1963 by cabibbo) 1) ... luca...
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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 ?
2Neutrino Oscillations: what next ? - MIAMI 2010Luca Stanco - Padova
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 5Luca Stanco - Padova 5
e
What is the pattern of neutrino masses?
Log m2 But it could look like that
m3 m2m3 m2
m1
m1
m2
mm1 m3
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 6Luca Stanco - Padova 6
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) ?
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 7
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 8
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 9
and be prepared to the unexpected !
There are also experimental controversials …
99.6% prob.99.6% prob.
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 10
LSND
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 11
%99.4% prob.97.0% prob. Excess (against NULL hypothesis)
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 12
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 13
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?
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 14
MINOS actually…Hint for CPT violations ?t o C o at o s
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 15
… and no hint for 13 yet …
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 16
…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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 1717
2000 OPERA proposal atmospheric neutrinos by looking for
appearance in a pure μ beam
The presentThe present
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 18
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)
19Neutrino Oscillations: what next ? - MIAMI 2010Luca Stanco - Padova
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 20
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 21
… 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
22Neutrino Oscillations: what next ? - MIAMI 2010Luca Stanco - Padova
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
23Neutrino Oscillations: what next ? - MIAMI 2010Luca Stanco - Padova
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…
24Neutrino Oscillations: what next ? - MIAMI 2010Luca Stanco - Padova
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 25
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 26
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 27
- e oscillations a e candidate event
eHowever difficult because ~1% beam contamination
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 2813
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 29
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 30
Muon-less event 9234119599 on 22 August 2009, 19:27 (UTC)(as seen by the electronic detectors)
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 31
Event reconstruction (1)
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 32
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%
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 33
( )
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 34
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 35
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 …
36Neutrino Oscillations: what next ? - MIAMI 2010Luca Stanco - Padova
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)
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 37
the obtainable significance is quite fluctuating !
# ***
evidence
observation
indication
evidence
# N N
but background is an important issue !
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 38
*** NOTE: obtained with OPERA proposal in 2001 (conservative result)
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 39
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)
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 40
(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
41Neutrino Oscillations: what next ? - MIAMI 2010Luca Stanco - Padova
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 42
Lot of activities at CERN during last year…
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 43
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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 44
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;
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 45
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 ?
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 46
whether the 2 one may be easily funded ?
The possible PS-Neutrino-Facility
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 47
Possible Sterile Neutrino Experiment Layout
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 48
Sterile Neutrino Experiment Requirements
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 49
Expected Neutrinos prodution
and flux rate of intrinsicElectron neutrinos electron background
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 50
(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.
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 51
(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
Luca Stanco - Padova Neutrino Oscillations: what next ? - MIAMI 2010 52
( ) 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 ?
53Neutrino Oscillations: what next ? - MIAMI 2010Luca Stanco - Padova
FAR future does really exist out of approved facilities ?(amazingly similar to present Politics’ situation in Italy)