Università di Roma III27 Gennaio 2003

L.Ludovici INFN Roma I

Prospettive Sperimentali della

Fisica delle Oscillazioni di Neutrini

Scenario attuale

LCPV - Factory

13 – Superbeam

Presente

Futuro RemotoFuturo

Prossimo

2

Short Abstract...Long-term goal: Leptonic CPV at the Factory

Uncertain perspective: technology, cost, physics.

Mid-term goal: 13 discovery

LMA ? 13 large?CPV already

found?

FactoryDoubtful...Only if Coll

3

500+ Cited papers 1990-20021. EVIDENCE FOR OSCILLATION OF ATMOSPHERIC NEUTRINOS

Super-Kamiokande Collaboration (Y. Fukuda et al.). Phys.Rev.Lett.81:1562 (1998) hep-ex/98070031597

2. OBSERVATION OF TOP QUARK PRODUCTION IN ANTI-P P COLLISIONSCDF Collaboration (F. Abe et al.). Phys.Rev.Lett.74:2626 (1995) hep-ex/9503002 9193. OBSERVATION OF THE TOP QUARK. D0 Collaboration (S. Abachi et al.). Phys.Rev.Lett.74:2632 (1995) hep-ex/9503003 8784. ATMOSPHERIC /e RATIO IN THE MULTIGEV ENERGY RANGEKamiokande Collaboration (Y. Fukuda et al.). Phys.Lett.B335:237 (1994) 7295. INITIAL RESULTS FROM THE CHOOZ LONG BASELINE REACTOR NEUTRINO OSCILLATION EXPERIMENT.CHOOZ Collaboration (M. Apollonio et al.). Phys.Lett.B420:397 (1998) hep-ex/9711002 6596. OBSERVATION OF A SMALL ATMOSPHERIC /e RATIO IN KAMIOKANDE.Kamiokande-II Collaboration (K.S. Hirata et al.). Phys.Lett.B280:146 (1992) 6137. FIRST MEASUREMENT OF THE RATE FOR THE INCLUSIVE RADIATIVE PENGUIN DECAY b s .CLEO Collaboration (M.S. Alam et al.). Phys.Rev.Lett.74:2885 (1995) 6118. LIMITS ON NEUTRINO OSCILLATIONS FROM THE CHOOZ EXPERIMENT.CHOOZ Collaboration (M. Apollonio et al.). Phys.Lett.B466:415 (1999) hep-ex/9907037 5789. EVIDENCE FOR e OSCILLATIONS FROM THE LSND EXPERIMENT AT LAMPF.LSND Collaboration (C. Athanassopoulos et al.). Phys.Rev.Lett.77:3082 (1996) nucl-ex/9605003 55310. EVIDENCE FOR TOP QUARK PRODUCTION IN p p COLLISIONS AT S 1/2 = 1.8-TeV.CDF Collaboration (F. Abe et al.). Phys.Rev.D50:2966 (1994) 54411. MEASUREMENT OF A SMALL ATMOSPHERIC MUON-NEUTRINO / ELECTRON-NEUTRINO RATIO.Super-Kamiokande Collaboration (Y. Fukuda et al.).Phys.Lett.B433:9 (1998) hep-ex/9803006 53412. MEASUREMENT OF THE RATE OF e + d p + p + e- INTERACTIONS PRODUCED BY B8 SOLAR NEUTRINOS AT

THE SUDBURY NEUTRINO OBSERVATORY.SNO Collaboration (Q.R. Ahmad et al.). Phys.Rev.Lett.87:071301 (2001) nucl-ex/0106015 52513. STUDY OF THE ATMOSPHERIC NEUTRINO FLUX IN THE MULTI-GEV ENERGY RANGE. Super-Kamiokande Collaboration (Y. Fukuda et al.). Phys.Lett.B436:33 (1998) hep-ex/9805006 52514. MEASUREMENT OF THE SOLAR ELECTRON NEUTRINO FLUX WITH THE HOMESTAKE CHLORINE DETECTOR.Bruce T. Cleveland et al. Astrophys.J.496:505 (1998) 52415. THE e AND CONTENT OF THE ATMOSPHERIC FLUX.R. Becker-Szendy et al (IMB Coll.) Phys.Rev.D46:3720 (1992) 521

4

Present evidences of neutrino mass and mixing

e, with m2 ≈ 10-4 eV2, almost (not fully) maximal mixing.

1. and/or NC appearance from the Sun in SNO.2. “Lab Test”: reactor e disappearance at L200Km in Kamland (4.6)

with m2 = (1.63.9).10-3 eV2, sin22> 0.92 at 90%CL

1. Super-K upward-going atmospheric disappearance.2. Most likely from o and matter effects in Super-K (2÷3)3. “Lab Test”:disappearance in accelerator from K2K-I (2÷3)

ewith m2~ 0.1 eV2

1. LSND claimed evidence of neutrino oscillation.2. Unseen by KARMEN with marginal sensitivity3. Controversy to be solved by Mini-BooNE (results in 2004-5)

5

1 0 0

0 C23 S23

0 -S23 C23

C13 0 S13ei

0 1 0

-S13e-i 0 C13

C12 S12 0

-S12 C12

0

0 0 1

U = UA.U13

.US =

3 neutrinos 2 mass differences, 3 angles and 1 CP phase m2

12 m223 12 23 13

atmospheric

solar??

The Mixing Matrix

e

= Ui

1

2

3

pure flavour eigenstate

back to flavour

eigenstateseach mass eigenstate takes a different phase

jk = m2jk(eV2)L(Km)/E(GeV) , W= Uj Uj Uk

Uk

P() = - 4 Re[W] sin2 jk 2 Im[W] sin 2jk ( ) ( ) jk

k>j k>j( ) jk

CP oddjk

6

Knowledge of mixing parameters

Solar do mix. NC appearance in SNO“Lab” confirmation: claim of disappearance in KamLand

Atmospheric disappear.Up/Down asymmetry in Super-K “Lab” confirmation: indication of disappearance in K2K

e Negative result in CHOOZ

m223 = m2

atm1.64.10-3 eV2

m212 = m2

sun...10-4 or 1...10-4 eV2

23 45o

12 45o

13 < 13o

No idea.

<

7

For experiments at terrestrial baselines, with 12<<1:

P(e) sin2213 sin223 sin2 23 = sin22e sin2 23

P() cos413 sin2223 sin2 23 = sin22sin2 23

P(e) sin2213 cos223 sin2 23 =P() 1 –

(sin22+ sin22e) sin2 23

P(ee) 1sin2213 sin2 23 Only 3 parameters: 23 m23 13 Reduce to two flavour mixings with effective mixing angles:

sin22= cos413 sin2223 sin2223

sin22e = sin2213 sin223 0.5 sin2213

Effective Mixing Angles

jk = m2jk(eV2)L(Km)/E(GeV) , W= Uj Uj Uk

Uk

P() = - 4 Re[W] sin2 jk 2 Im[W] sin 2jk ( ) ( ) jk

k>j k>j( ) jk

CP oddjk

8

LCP AsymmetryBeing 13 small, if m2

12 is only 10100 times smaller than m223

(LMA):P(e) sin223 sin2213 sin2 13 + + cos223 sin2212 sin2 12 + + J 12 sin 13 cos( - 13) J = cos 13 sin212sin223sin213

large large large ??

( ) ( )

( )

LCP asymmetry vanishes for small 13.

“atmospheric”“solar”

“interference” J determinant

e gives the best opportunity for LCPV due to the suppression of the leading CP conserving contributions

Discovery of non-zero 13 is a pre-requisite of any sensible experimental strategy to attack the difficult

problem of LCPV.

9

-Factory Kosharev 1974Wojcicki 1974Collins 1975Geer 1998

-collider Budker 1969Skrinski 1971Neuffer 1979

SBL (1001000 Km)LBL (10005000 Km)VLBL (12 REARTH )

10-1000kt Mass

DetectorSRe(e)

+(-) ()

Conventional “pion” beams are dominantly () with a few percentcontaminations of () e e. Difficult to access all transitions and oscillation parameters are measured with uncertainty O(10%) while NuFact beams could allow O(1%) precision.

E/m

The Neutrino Factory Idea

10

E= 5,10,20,40 GeV

L = 1000 Km e

P. Lipari, hep-ph/0102046

Well known flux ( decay kinematic, polarisation) Clean beam composition: 1:1 +e (or +e) Flux scales with NE2 /L2 Average neutrino energy scales with E Interaction rate scales with MDETNE3/L2

(y) = 2y2 (3-2y) (y) (1-y)e (y) = 12y2 (1-y) (y) (1-y)

dN E2N

dydSm

2L2=0

(y)

Neutrino Factory Fluxes

0.67 . 10-38 . E (GeV) cm2

0.34 . 10-38 . E (GeV) cm2

11

2 possible ways: Ae =

Ae =

Earth is CP-odd. In LBL and VLBL experiments (L>1000 Km) the effects of propagation in matter are in general large and P() P() even if CP is conserved.

P(e) - P(e)P(e) + P(e)P(e) - P( e)P(e) + P( e)

CP

T

ACP at NuFact comparing wrong sign - in a beam from + with the charge conjugate process and beam. Need subtraction of matter induced CP effects (two detectors at different baselines). Need precise knowledge of the relative neutrino (anti-) cross-sections.

AT free from matter induced effects but it requires the lepton ID and charge determination not only for muons but also for electrons, very difficult in practice in a large O(50Kt) detector.

LCPV at the Factory

12

Road

ma

pNOW

2020

2010

2005

2015

K2K-II

JHF

? Off-Axis

HARP

MICE

? Factory

? JHF-HK

CNGSNuMI

disappearance

1 down to 1o

appearanceNC/CC

LCP violation 1 down to 0.1o

LCP violation

F R

&D

MiniBooNE

LSND?

KamLand

m212,12 at 2%

1

13

JHF Physics Programme

High intensity neutrino beam from JHF (0.75 MW) to Super-K (50kt)

1. Discovery of 13 down to sin2213 > 0.0062. Precision measurement of sin2223 and m2

23

3. Search for sterile components through NC interactions

Phase I

JHF upgrade to 4 MW power. Construction of Hyper-K (1Mt)

1. Discovery of 13 down to sin2213 > 0.0012. Leptonic CP violation. down to 10-20 degrees if sin2213 > 0.01

Phase II

14

JHF facility

Energy(GeV)

Cu

rren

t(A

)

• KEK-JAERI joint project• JAERI@Tokai-mura, 295 Km from Super-K (60Km NE of KEK)• Construction 2001-2007• Cost: 1335(1890) Oku Yen (1 Oku=108)

JHF K2K NuMI CNGS

E(GeV) 50 12 120 400

Intensity(1012ppp)

330 6 40 48

Rate(Hz)

0.29 0.45 0.53 0.10

Power(MW)

0.75 0.0052

0.41 0.3

15

Off-Axis neutrino BeamsHornsTarget Decay Pipe Detector

BNL proposal E889 http://minos.phy.bnl.gov/nwg/papers/E889

E=m

2 – m2

2 (E- pcos)

m2 – m

2

m2 (1 + 22)

E

E >>m, and<<1

Much higher flux than old-style NBB. Strong cut-off of HE tail. Reduced e contamination. Tune energy to maximise sensitivity= 1.27 . m2(eV2) . L(Km) / E(GeV) Beam energy almost fixed by geometry

=

L2

1

m

E 2

(1 + 22)2

1

L2

1

(E- pcos)2

m2

16

JHF Beam

=1o

=2o

=3o

• Beam steering angle 2.5o0.5o.• Tune energy between 0.4 and 1 GeV• Best tuning to m2=(1.64).10-3 eV2Beam

Epeak Flux (106/cm2/yr)

e/ (%)

All, CC events(events/22.5kt/yr)

e total @peak

e

OA2o 0.7 19.2

0.19 1.00 0.21 31002200

6045

OA3o 0.55 10.6

0.13 1.21 0.20 1100800

2922

• 3.3.1014 ppp at 0.285 Hz (0.75 MW, 2.64 MJ/pulse)• 1021 pot/yr in 130 days/yr• SC proton transport line• Carbon target• Secondary pions focused by horns• Decay pipe 130m length from target• Near detector at 280m from target• Intermediate detector at 1.5Km• Super-K at 295 Km. (22.5 kt fiducial)

17

JHF Near DetectorsFlux.L2 @ Super-KFlux.L2 @ 1.5 KmFlux.L2 @ 0.28 Km • Covers from 0o to 3o.

• Monitor the beam stability and flux.• High rate: 60 events/kt/spill.• Study and e interactions: CCQE, CC, NC.• Non point-like source, different target, different detector technology: flux extrapolation to Super-K problem.

• Off-Axis as Super-K• Water-Cherenkov (100t fiducial mass) to cancel most of the flux extrapolation syst.• Spectrum differences < 10% 2% systematic due to e background subtraction.

60% difference

Better than 10%

Intermediate detector at 1.5 Km

Near detector at 280 m

18

Detector at 1.5Km

Conceptual design.

19

Far detector

20

Neutrino Energy Measure

=80MeV

Ereco - Etrue (MeV)

Etrue (MeV)

Ere

co (

MeV

)

non-QE background

CCQE

Erec =mnEl – ml

2/2mn – El + Plcosl

Almost exact (Fermi motion) for QE interactions: l n l p

non-QE CC interactions of higher energy neutrinos background for disappearance

Coherent o production from NC interactions of higher energy neutrinos is a background for e appearance

21

13 (e appearance)CC NC Beam

e

Oscillatede

Events in FV 10713.6

4080.3 292.1 301.6

1Ring e-like 14.3 247.1 68.4 203.7

e/o separation 3.5 23.0 21.9 152.2

0.4GeV<E<1.2GeV

1.8 9.3 11.1 123.2

1. Forward cut2. high inv.mass cut3. 1-2 rings likelihood cut4. Ring balance cut

e/o separation

m2=3.10-3

sin213=0.1

22

13 sensitivity

23

m23, 23 ( disappearance)

Fit with: P() = 1 - sin2223 cos413

sin2 23

Measured spectrum in Super-K:Muon-like FC events in SKNeutrino energy reconstructionSubtraction of non-QE backg.

Non-oscillated spectrum:Muon-like events in Near Detec.Neutrino energy reconstructionSubtraction of non-QE backg.Near-Far extrapolation

Survival probabilityMeasured/Non-Oscillated22.5kt x 5 year

Oscillation pattern clearly visibleHigh precision determination: sin2223 = 0.01 m2

23 = 4.10-5 eV2

m2

sin22

24

Search for sterile neutrinos

NC interactions sensitive to all active neutrinos. Together with and e, NC provide a measurement of and s.

NC selection of single o, lepton-less events: N N o

90%CL bands

Expected single o events22.5kt x 5 year

o production cross-section accurately measured (better than 5%) in the near detectors.

No way to reconstruct the neutrino energy. Narrow Band neutrino beam essential.

25

JHF-II (>2012)0.75 4MW beam power50 kt 1 Mt water Cherenkov(Hyper-Kamiokande)

3x105 events/yearLeptonic CPV

26

CPV Sensitivity of JHF-II

0.14

0.12

0.10

0.08

0.06

0.04

0.02

00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

Stat+BG 10%syst

Stat+BG 5%syst

Stat+BG 2%syst

Stat+BG no syst

Stat. Only. No BG

13 excluded by CHOOZ

13 not reachable by JHF-I

sin

Sin

22

13

If JHF-I discovers non-zero 13, than JHF-II will be sensitive to LCPV down to =10-20 degrees.

P(e) - P(e)P(e) + P(e)

CPAe = = m2

12L 4 E

sin2212

sin 13

sin . .(without matter

effects)

27

Status of JHF• La costruzione di JHF è iniziata nel 2001 e il primo fascio è atteso nel 2007.• La fase-I (0.75MW) è approvata e finanziata (oltre 1M€).• Il programma di neutrini è una delle principali motivazioni per la costruzione della facility.• L’approvazione e il finanziamento della neutrino beam-line è atteso per questa estate in Giappone (MEXT).• Una prima LoI è apparsa nel 2001.• Nel 2002 si sono tenuti due workshop internazionali, con partecipanti da Giappone, Canada, Francia, Italia, Corea, Russia, Spagna, UK e USA. • Sono stati formati dei working groups internazionali.• Una LoI aggiornata è stata inviata nel gennaio 2003, firmata da istituti in Giappone, Canada, Francia, Italia (Bari,Napoli,Padova,Roma I), Corea, Polonia, Russia, Spagna, Svizzera, UK and USA.JHFn è il progetto più interessante per scala dei tempi, strategia sperimentale, flessibilità e ricchezza del programma scientifico.

La partecipazione italiana deve rafforzarsi per contribuire in modo rilevante e visibile.

28

Conclusioni• La fisica delle oscillazioni di neutrini vive anni di importanti risultati.• I neutrini solari oscillano. Evidenza di neutrini attivi non-e dal sole. Conferma da una sorgente artificiale.• Forte indicazione di sparizione dei atmosferici. Conferma (non conclusiva) da una sorgente artificiale.

• K2K-II: Conferma sparizione . Pattern di oscillazione.• NuMi: NC/CC, sterili/tau• CNGS: apparizione diretta di tau• MiniBooNE: LSND?

• Ricerca di 13. Segno di m223 (gerarchia) ?.

• Misura di precisione dei parametri (GUT test, mass models,...)

Finora

Next (qualche anno)

Next2 (entro il decennio)

• Leptonic CP violation.• Test del triangolo di unitarietà

Next3 (....)

29

Road

ma

pNOW

2020

2010

2005

2015

K2K-II

JHF

? Off-Axis

HARP

MICE

? Factory

? JHF-HK

CNGSNuMI

disappearance

1 down to 1o

appearanceNC/CC

LCP violation 1 down to 0.1o

LCP violation

F R

&D

MiniBooNE

LSND?

KamLand

m212,12 at 2%

1