Experimental neutrino physics: natural beams, reactors and LBL

Barbara Caccianiga-INFN Milano

EPS- Conference on High Energy Physics 2015 22-29 July 2015 Vienna Neutrino Physics: the puzzle-making

2 Neutrino Physics: the puzzle-making

Dm2 n2 12

2 Dm 13

3 Neutrino Physics: the puzzle-making

q ~9o o 13 o ne q23~45 q12~33 n1

The Pontecorvo-Maki-Nakagawa-Sakata (PMNS) Matrix i n e  1 0 0   Dc13m2 0 s13e   c12 s12 0 n1    n  12    n  0 c s   8x100 -5eV21 0   sn2 c 0 n     23 23     12 12   2       i      n  0  s23 c23   s13e 0 c13   0 0 1 n 3 

Dm2 13 n n 3x10-3eV2 3

44 Experimental neutrino physics: the puzzle making

To complete the neutrino puzzle • Perform appearance and/or disappearance experiments using different neutrino sources and baselines;

E n L

n source n DETECTOR

• Characteristic E/L sets the reach of the experiment in term of Dm2; • The possibility of probing different E/L within the same experiment allows to see the oscillatory pattern of appearance or disappearance thus enhancing sensitivity;

5 Experimental neutrino physics: the puzzle making

To complete the neutrino puzzle • Perform appearance and/or disappearance experiments using different neutrino sources and baselines;

E n L

n source n DETECTOR

Oscillations in vacuum (2 flavours)

2  Δmxy L  P(ν  ν )~sin 2 2θ sin 2   2 x y xy   • Depends on E, L, Dm , q  4E  6 Experimental neutrino physics: the puzzle making

To complete the neutrino puzzle • Perform appearance and/or disappearance experiments using different neutrino sources and baselines;

E n L

n source n DETECTOR

Oscillations in matter (2 flavours)

• Resonant effects for neutrinos 2 crossing matter; 2 M 2  (Δmxy )M L    2 P(νx  νy )~sin 2θxy sin • Depends on E, L, Dm (also on  4E    its sign!), q and r;

7 Experimental neutrino physics: the puzzle making

To complete the neutrino puzzle • Perform appearance and/or disappearance experiments using different neutrino sources and baselines;

E n L

n source n DETECTOR

Oscillations in matter (3 flavours)

2 • Depends on E, L, Dm ij, qi, CP.,..

8 Experimental neutrino physics: the puzzle making

To complete the neutrino puzzle • Perform appearance and/or disappearance experiments using different neutrino sources and baselines;

E n L

n source n DETECTOR

NEUTRINO SOURCES - Natural sources (solar, atmosferic neutrinos) - Reactor neutrinos - Accelerator neutrinos (Long Baseline) 9 Experimental Neutrino Physics: the puzzle-making

The Pontecorvo-Maki-Nakagawa-Sakata (PMNS) Matrix

i cij  cosqij n e  1 0 0   c13 0 s13e   c12 s12 0 n1       sij  sinqij n  0 c s   0 1 0   s c 0 n     23 23     12 12   2       i      n  0  s23 c23   s13e 0 c13   0 0 1 n 3 

atmosferic n SBL reactor n solar n accelerator n accelerator n LBL reactor n

NEUTRINO SOURCES - Natural sources (solar, atmosferic neutrinos) - Reactor neutrinos - Accelerator neutrinos (Long Baseline) 10 Natural beams

• Solar neutrinos • Atmosferic neutrinos

11 Natural beams Solar neutrinos E~ 1 MeV L~ 1011 m

The Sun is powered by nuclear reactions which produce neutrinos

pp CYCLE: ~99% of the sun energy

CNO CYCLE: <1% of the sun energy

Natural beams Solar neutrinos E~ 1 MeV L~ 1011 m

E/L ~ 10-11 eV2 N.B.: resonance due to matter effects for E>1 MeV

2 ne disappearance: sensitive to (Dm )12+ q12

i n e  1 0 0   c13 0 s13e   c12 s12 0 n1        n  0 c s   0 1 0   s c 0 n     23 23     12 12   2       i      n  0  s23 c23   s13e 0 c13   0 0 1 n 3 

• L is set by Nature, cannot be changed; • Investigating different solar neutrino from different reactions it is

possible to probe P(ne  ne) as a function of E;

Natural beams Solar neutrinos

• I recall that the Solar Neutrino Problem was the first hint towards nu oscillations • Huge detectors based on hundreds/thousands of tons of detecting material Homestake Borexino Superkamiokande

Gallex/SAGE SNO

Natural beams Solar neutrinos

Cerenkov Clorine Scintillator Gallium

15

Natural• Barbara beams Caccianiga -INFN Milano 50th Rencontres de Moriond- La Thuile, March 14th 21st 2015 Borexino: Nature 512, 383-386 (2014) observation of pp neutrinos

(6.6  0.7)1010 cm-2s1 measured 10 -2 1 pp  (5.98  0.04)10 cm s expected (high - Z) (6.03 0.04)1010 cm-2s1 expected (low - Z) Luminosity in neutrinos consistent with luminosity in photons Natural beams Solar neutrinos+KamLAND KamLAND+SOLAR 2 arXiV: 1409.4515 combined results on (Dm )12+ q12

Results from solar and KamLAND

Survival probability P(ne ne) 2 0.18 5 2 Dm12  7.530.18 10 eV 2.3% precision 2 0.029 tan q12  0.4360.025 6.6% precision Oscillations Oscillations in vacuum in matter

Natural beams Solar neutrinos+KamLAND What Next?

Small tension (~2s ) in Dm2 between solar and KamLAND data

Gonzales-Garcia,Maltoni,Schwetz . arXiV: 1409.5439

Tension comes from 1) no up-turn seen in the 8B spectrum so far; 2) indication for a non vanishing D/N asymmetry in SK;

Non-standard interactions and super-light sterile neutrino? arXiV:1101.3875, arXiV:1307.3092, arXiV:1012.5627 Study transition region between vacuum and matter oscillation regime

Natural beams Atmosferic neutrinos E~ 1 GeV L~ 104-107 m

Secondary products of cosmic rays in the atmosphere ne, anti- ne, n, anti- n;

BASELINE L

ENERGY

selecting q is equivalent to select L

Natural beams Atmosferic neutrinos E~ 1 GeV L~ 104-107 m

E/L ~ 10-3 eV2

n , anti- n disappearance   2 sensitive to (Dm )23+ q23 ne , anti- ne appearance

First evidence of oscillations in this sector! Y. Fukudae (Super-Kamiokande Collaboration) et al. (1998). "Evidence for Oscillation of Atmospheric Neutrinos". Physical Review Letters 81 (8): 1562–1567.

Natural beams Atmosferic neutrinos and neutrino mass hierarchy

• Matter effects introduce a dependence on the sign of Dm2 and on the sign of A, where for n and anti- n respectively

(Dm2 )m L PM (ν  ν )  PM (ν  ν )  sin 2θ sin 2 2θmsin 2 13 e μ μ e 23 13 4E

sin22θ sin22θm  13 13 2    2 2G N E  sin22q  cos2q  F e • resonance occurs when 13  13   Δm2   13  2 2 Dm13 cos(2q13 )  2 2GF Ne E    2 2G N E  (Dm2 )m  Δm2 sin22q  cos2q  F e 13 13 13  13   Δm2   13 

• This condition is met when E~30 GeV/r [g cm-3] for 1 GeV

Natural beams Atmosferic neutrinos and neutrino mass hierarchy

P(n  n ) • Map upward n flux in bins Normal Hierarchy Inverted Hierarchy of (E,cosq); • cosq= -1 L~12000 Km;

Letter of Intent PINGU- arXiV:1401.2046

Natural beams Atmosferic neutrinos and neutrino mass hierarchy

P(anti-n  anti-n ) Inverted Hierarchy Normal Hierarchy Note that:

P(n  n  ) in NH  P(n  n  )in IH • If it is not possible to distinguish between n and anti-n  the effect of hierarchy washes out; • Fortunately

s (n  )  s (n  ) and (n  )  (n  )

 possible to see a few % effect due to hierarchy

Letter of Intent PINGU- arXiV:1401.2046

Natural beams Atmosferic neutrinos and neutrino mass hierarchy

• In the framework of IceCube and Km3NET; • Instrument ~ Mtons of ice (PINGU) or sea-water (ORCA) • Fine granularity to have low threshold; PINGU ORCA

..or alternatively use a magnetized 50 kton detector which is capable of distinguishing neutrinos from anti-neutrinos (INO project).. Natural beams Reactor neutrinos

25 Reactors Reactor neutrinos

Reactor neutrinos: anti- ne mainly coming from the beta-decay of the fission products of 235U, 238U, 239Pu and 241Pu;

E~ 5 MeV Detecting reaction: 3- 5 inverse beta decay L~ 10 10 m

• CRITICAL: Systematics associated to the reactor n spectrum (depending on the fuel composition)  Near and far detector;

Reactors Reactor neutrinos

antine disappearance  Dm2 L Dm2 L  Dm2 L 2  2 2 13 2 2 23  4 2 2 12 P(n e n e ) 1  sin 2q13 cos 2q12 sin  sin 2q12 sin   cos q13 sin 2q12 sin  4E 4E  4E

Daya Bay ~60 km ~180 km JUNO KamLAND

L ~ 180 Km

2 sensitive to (Dm )12+ q12 (solar term)

Reactors Reactor neutrinos

antine disappearance  Dm2 L Dm2 L  Dm2 L 2  2 2 13 2 2 23  4 2 2 12 P(n e n e ) 1  sin 2q13 cos 2q12 sin  sin 2q12 sin   cos q13 sin 2q12 sin  4E 4E  4E

Daya Bay 2 2  2 Dmee L  ~60 km sin 2q sin  ~180 km 13  4E  JUNO KamLAND  

L ~ 1.5 Km

2 sensitive to (Dm )13+ q13

Reactors Reactor neutrinos: Double-Chooz, RENO and Daya-Bay

Double Chooz: • so far results only with the far detector • near detector takes data since dec 2014 (first results with both detectors by end of 2015)

Daya-Bay: deeper, higher nuclear plant power, more far/near detectors, more favourable baseline;

Reactors Reactor neutrinos:

results on q13

RESULTS FROM DAYA-BAY (Moriond 2015)

• Best precision on q13 measurement (~6%)

2 0.005 sin 213  0.0840.005 2 0.10 3 2 Δmee  2.440.11 10 eV χ 2/NDF 134.7/146

Reactors Reactor neutrinos

antine disappearance  Dm2 L Dm2 L  Dm2 L 2  2 2 13 2 2 23  4 2 2 12 P(n e n e ) 1  sin 2q13 cos 2q12 sin  sin 2q12 sin   cos q13 sin 2q12 sin  4E 4E  4E

Daya Bay ~60 km JUNO ~180 km KamLAND

L ~ 60 Km

sensitive to mass hierarchy

Reactors Reactor neutrinos: the JUNO proposal

antine disappearance  Dm2 L Dm2 L  Dm2 L 2  2 2 13 2 2 23  4 2 2 12 P(n e n e ) 1  sin 2q13 cos 2q12 sin  sin 2q12 sin   cos q13 sin 2q12 sin  4E 4E  4E

Daya Bay ~60 km JUNO ~180 km Exploit interference in KamLAND n oscillations between atmospheric and solar term;

• It is feasible because

q13 is relatively large! • Unlike accelerator or atmosferic experiments this technique doesn’t

depend on CP and q23 ;

Reactors Reactor neutrinos: the JUNO proposal

antine disappearance  Dm2 L Dm2 L  Dm2 L 2  2 2 13 2 2 23  4 2 2 12 P(n e n e ) 1  sin 2q13 cos 2q12 sin  sin 2q12 sin   cos q13 sin 2q12 sin  4E 4E  4E

Exploit interference in n oscillations between atmospheric and solar term;

Requires exceptional energy resolution

Reactors Reactor neutrinos: the JUNO proposal

Precision < 1% !

Civil construction: 2015-2017; Detector Installation:2016-2019; Filling and data-taking: 2020;

KamLAND Borexino JUNO

LS Mass 1 ktons 0.5 kton 20 kton

Energy 6% / E 5% / E 3% / E resolution Light Yield 250 511 1200 p.e./MeV p.e./MeV p.e./MeV

Similar concept and design for the RENO-50 proposal in Korea

Reactors Accelerator neutrinos: Long Baseline Experiments

35 Accelerator neutrinos: LBL experiments Accelerator neutrinos: long baseline experiments

n and anti(n) beams produced @ accelerators BASELINE • L ~300 Km - 1300 Km (depending on the experiment) ENERGY • E between ~0.6 GeV- 20 GeV E/L ~ 10 -3 eV2

i n e  1 0 0   c13 0 s13e   c12 s12 0 n1        n  0 c s   0 1 0   s c 0 n     23 23     12 12   2       i      n  0  s23 c23   s13e 0 c13   0 0 1 n 3 

2 ne appearance: sensitive to q13 + (Dm )23+ q23 2 n disappearance: sensitive to (Dm )23+ q23 2 n appearance: sensitive to (Dm )23+ q23

Sensitivity also for q23 octant, CP, mass hierarchy

Accelerator neutrinos: LBL experiments Accelerator neutrinos: long baseline experiments

ne appearance (To 1-st order in matter effect)

• Sensitive to q13 ;

• More complicated to extract info on q13 with respect to reactor experiments (measurement dependent on CP and other unknowns);

Accelerator neutrinos: LBL experiments Accelerator neutrinos: long baseline experiments

ne appearance (To 1-st order in matter effect)

CP-violating term

Matter terms

• Sensitivity to CP is greatly improved by running in n and anti- n mode; • BUT: a neutrino/anti-neutrino asymmetry is induced both by CP violation and by

matter effect (both CP and a change sign going from n to anti-n) ; • ALSO: the matter terms depend on Mass hierarchy  complicated interplay with

CP; Accelerator neutrinos: LBL experiments Accelerator neutrinos: long baseline experiments

ne appearance

CP-violating term

Matter terms

P(n  ne) for L=295m P(anti-n  anti-ne) for L=295m

For example

39 Accelerator neutrinos: LBL experiments Accelerator neutrinos: long baseline experiments

ne appearance (To 1-st order in matter effect)

CP-violating term

Matter terms

• Combination with n disappearance helps constraining some of the parameters 2 (for example, q23 and Dm 23)

Accelerator neutrinos: LBL experiments Accelerator neutrinos: long baseline experiments

E L E/L Experiment Status n n beam n type (GeV) (Km) (eV2) KEK T2K Running 0.6 295 2x10-3 n /anti-n J-PARC   Fermilab MINOS Completed 2 735 2.5x10-3 n /anti-n NuMI   Fermilab MINOS+ Running 5 735 6.8x10-3 n /anti-n NuMI   Fermilab NOVA Running 2 810 2.5x10-3 n /anti-n NuMI   CERN OPERA Completed 17 730 2.3x10-2 n CNGS  Fermilab DUNE Future 5 1300 3.8x10-3 n /anti-n newbeam   KEK n /anti-n HYPERK Future 0.6 295 2x10-3 J-PARC   (improved)

Accelerator neutrinos: LBL experiments Accelerator neutrinos: OPERA

NEWS: the 5-th n! Null hypothesis excluded at 5.1 s

arXiV:1507.01417

Accelerator neutrinos: LBL experiments Accelerator neutrinos: long baseline experiments

E L E/L Experiment Status n n beam n type (GeV) (Km) (eV2) KEK T2K Running 0.6 295 2x10-3 n /anti-n J-PARC   Fermilab MINOS Completed 2 735 2.5x10-3 n /anti-n NuMI   Fermilab MINOS+ Running 5 735 6.8x10-3 n /anti-n NuMI   Fermilab NOVA Running 2 810 2.5x10-3 n /anti-n NuMI   CERN OPERA Completed 17 730 2.3x10-2 n CNGS  Fermilab DUNE Future 5 1300 3.8x10-3 n /anti-n newbeam   KEK n /anti-n HYPERK Future 0.6 295 2x10-3 J-PARC   (improved)

Accelerator neutrinos: LBL experiments Accelerator neutrinos: T2K

Accelerator neutrinos: LBL experiments Accelerator neutrinos: T2K

• Off-axis beam allows to select a very narrow energy around oscillation maximum (E~ 0.6 GeV)

Accelerator neutrinos: LBL experiments Accelerator neutrinos: T2K

2 Results on n disappearance: sensitive to (Dm )23+ q23

2 0.0055 sin θ23  0.5140.0056 (N.H.) • Most precise measurement of q (11%) 23 sin 2θ  0.5110.0055 (I.H.) • Phys.Rev.Lett.112,181801 (2014) 23 0.0055

Accelerator neutrinos: LBL experiments Accelerator neutrinos: T2K

2 Results on ne appearance: sensitive to (Dm )23+ q23+ q13 Phys.Rev.Lett.112,061802 (2014)

• Discovery of n  ne at 7.3 s (28 ne)

• T2K finds a value of q13 slightly larger than reactors;

• This small tension provides early sensitivity to CP;

Accelerator neutrinos: LBL experiments Accelerator neutrinos: T2K

Combined results on ne appearance, n disappearance and reactors

• Possible small hint

towards CP = -p/2;

Now running in anti-n mode. Still very low statistics

• 3 anti-ne events detected

• results with anti- n beam consistent with the one with n beam

Accelerator neutrinos: LBL experiments Accelerator neutrinos: MINOS, MINOS+ and NOnA

Start taking data NOvA (far) MINOS (far) operating • Great advantageoctober with 2014 respectSurface to atmosfericat 2340 nu: ft level separatesince 2005 n from anti-n 14 kton 5 kton 350 kW (>400 kW)

MINOS (near)

MINERvA

MiniBooNE

NOvA (near) MicroBooNE (LAr TPC) 49 Accelerator neutrinos: LBL experiments Accelerator neutrinos: MINOS, MINOS+

+ MINOS and MINOS n disappearance

Most precise 2 determination of (Dm23) Uncertainty ~4% approaching the size of 2 (Dm12)

Accelerator neutrinos: LBL experiments Accelerator neutrinos: Nona

• Off-axis beam (0.84°)  narrow energy spectrum (@2 GeV); • Run both in neutrino and anti-neutrino mode; • High degree of complementarity between NOnA and T2K; • Different detector techniques (scintillator vs Cerenkov) different systematic errors; • Matter effect much larger in Nona: different interplay between unknown parameters  data from both could be used to break degeneracy); • Combining results from Nona and T2K will provide more information on oscillation parameters

Accelerator neutrinos: LBL experiments Accelerator neutrinos: future LBL experiments

E L E/L Experiment Status n n beam n type (GeV) (Km) (eV2) KEK GoalsT2K of futureRunning LBL experiments0.6 295 2x10-3 n /anti-n J-PARC   • Collect high statistics of disappearance (~10000 n) and appearance -3 Fermilab MINOS Completed 2 735 2.5x10 n /anti-n (~1000 ne ) samples; NuMI Fermilab • MINOSSearch+ for CPRunning-invariance/violation;5 735 6.8x10-3 n /anti-n NuMI   • Determine neutrino mass hierarchy; Fermilab NOVA Running 2 810 2.5x10-3 n /anti-n • Significantly improve precision of neutrino mixing parameters;NuMI   CERN • OPERATest the threeCompleted neutrino mixing17 hypothesis;730 2.3x10 -2 n CNGS  Future Fermilab DUNE 5 1300 3.8x10-3 n /anti-n (end of 2020s) newbeam   Future KEK n /anti-n HYPERK (end of 2020s) 0.6 295 2x10-3 J-PARC   (improved) Future LBL experiments: DUNE

Start taking data NOvA (far) MINOS (far) operating • Great advantageoctober with 2014 respectSurface to atmosfericat 2340 nu: ft level separatesince 2005 n from anti-n 14 kton 5 kton 350 kW (>400 kW)

MINOS (near)

MINERvA

MiniBooNE

NOvA (near) MicroBooNE (LAr TPC) 53 Future LBL experiments: HyperK Accelerator neutrinos: DUNE and HYPERK

Same L/E but different L and E (factor 5); – DUNE longer baseline L better sensitivity to Mass Hierarchy; – Matter effects (DUNE=yes; HYPERK=small): different interplay between unknown parameters data from both could be used to break degeneracy;

– DUNE higher energy  possible to see n appearance; – Possible to test non-standard effects depending separately from E and L; Different beams (DUNE=on axis; HYPERK=off axis); – Different backgrounds; – Energy range wider for DUNE, narrower for HYPERK; Different detector techniques (LAr vs Cerenkov) different systematics (n interaction cross-sections...)

Accelerator neutrinos: LBL experiments Accelerator neutrinos: DUNE and HYPERK

In order to fully exploit the large statistics a great control of systematics must be reached; Main sources of systematic errors: – uncertainties related to the neutrino flux; – uncertainties related to the neutrino cross-sections; – uncertainties related to the detector; Extensive program devoted to address these issues (development of near detector, dedicated tests at the Cern neutrino platform..);

Both DUNE and HYPERK will collect large atmosferic neutrino samples which will be important for:

• Study of detector-related systematics; • Study of neutrino Mass Hierarchy; • Complement accelerator studies by extending the range of L and E;

Accelerator neutrinos: LBL experiments Conclusions and outlook

• Since the first discovery of neutrino oscillations in 1998, many parts of the ‘’neutrino puzzle’’ have been completed; • A rich experimental program is being developed to determine the pieces which are still missing; • The synergy between different experiments will be a crucial element to break degeneracies and reduce the impact of systematic errors; • For favourable combination of the parameter values we may have indications on the missing pieces of the puzzle already with the current generation of experiments (T2K, NOnA); • The wealth of data which will come from future experiments (JUNO, RENO-50, INO, PINGU, ORCA, HYPERK, DUNE) will allow precise determination of all the missing pieces and significant improvement on the already known parameters

Conclusions o o o CP ne q23~45 q13~9 q12~33 n1

Mass hierarchy n2

2 2 Dm 12 Dm 13 n q n n 3 -5 2 23 3x10-3eV2  8x10 eV octant

58 5858 o o o CP ne q23~45 q13~9 q12~33 n1

T H A N K

Mass n hierarchy Y O U !! 2

2 2 Dm 12 Dm 13 n q n n 3 -5 2 23 3x10-3eV2  8x10 eV octant

59 5959 BACKUP-SLIDES

60 Accelerator neutrinos: MINOS, MINOS+

MINOS and MINOS+ disappearance + appearance +atmospheric

° Small preference for inverse hierarchy and q23 < 45

Accelerator neutrinos: LBL experiments Accelerator neutrinos: T2K

T2K disappearance + appearance + reactors

° Small preference for direct hierarchy and q23 > 45

Accelerator neutrinos: LBL experiments Accelerator neutrinos: OPERA E~ 17 GeV L~ 735 Km

E/L ~ 10-2 eV2 N.B.:not optimal for oscillation, but unbalanced towards higher energies in order to have tau production

n appearance Dm2 L P(n n )  sin 2 2q cos2 q sin 2 23   23 13 4E

THE PRINCIPLE • Massive active target (~1.2 kton) • Micrometric space resolution • Detects -lepton production and decay

Accelerator neutrinos: LBL experiments Accelerator neutrinos: OPERA

Visible energy Expected background

• 5 n candidates found; • Exclusion of null hypothesis at 5.1 s ;

arXiV:1507.01417

Accelerator neutrinos: LBL experiments Combining Nova and T2K: potential for 95% evidence of CPV

65 Future LBL experiments: DUNE

Neutrino spectra and oscillation probabilities

neutrino anti-neutrino

----- CP= -p/2 ----- CP= -p/2 ----- CP= 0 ----- CP= 0 ----- CP= +p/2 ----- CP= +p/2

BLACK SOLID CURVE: n (anti-n) un-oscillated spectra

COLORED LINES: P(n  ne )

Accelerator neutrinos: LBL experiments Future LBL experiments: DUNE

Neutrino spectra and oscillation probabilities neutrino

----- CP= -p/2 ----- CP= -p/2 ----- CP= 0 ----- CP= 0 ----- CP= +p/2 ----- CP= +p/2

DUNE is nearly optimal choice of beam and distance for sensitivity to CPV, CP phase, n mass hierarchy and other oscillation parameters in the same experiment

Accelerator neutrinos: LBL experiments Future LBL experiments: DUNE

Sensitivity to Mass hierarchy and CP violation

Sensitivity to Mass Hierarchy Sensitivity to discovery of CPV (CP 0,p) Normal Mass Hierarchy assumed true Normal mass Hierarchy assumed true

Accelerator neutrinos: LBL experiments Marzio Nessi @ NeuTel 2015 69