CORTONA 2014 New Frontiers in Theoretical Physics XXXIV Convegno Naz. di Fisica Teorica, Cortona, May 28th–31st 2014 V.Antonelli – Milano University and I.N.F.N. Milano Present and future of neutrino physics and its impact on elementary particle physics and astrophysics.

Historical role and future neutrino physics Neutrinos fundamental for elementary particle physics and astrophysics and in creating a connection between the two. Historical view helps in understanding present situation and future outlooks. More than 60 years of discoveries, puzzles and surprises (oscillations, massive neutrinos, lightness of the masses, large mixing angles, possible existence of sterile particles, etc.) fundamental for the confirmation of the Standard Model and then for the indication of the need to go beyond. Powerful tool to investigate astrophysical objects (Sun, Supernovas, etc.) and face cosmological problems. New attitude: from disappearance to appearance, from natural to artificial, from discovery to precision measurements, but also possibility to tackle fundamental questions.

Taken from recent presentation of the neutrino W. G Taken from recent presentation of the neutrino W.G. at the “What next” I.N.F.N. meeting

Taken from recent presentation of the neutrino W. G Taken from recent presentation of the neutrino W.G. at the “What next” I.N.F.N. meeting

Solar neutrino physics Solar n after 2002: important results by ‘‘hystorical’’ (SNO, SK, KamLAND) and new experiments (Borexino) and global analyses. Still many open questions, relevant also for astrophysics. Projects for different future experiments. Different SNO phases: SNO II (salt), SNO III (3He proportional chambers) improvement of fluxes and mixing angles determination; LETA (2010) analysis of SNO I and II with lowered E threshold and better signal/bckg. ratio. SNO only analysis: best fit point in LOW region. Including KL and/or Borexino: LMA solution. SuperKamiokande: SK II and SK III, confirmation of SK I (LMA solution, tan2 q12 slightly larger) ; SK IV (since sept. ‘08). Lower Ethr(possible spectrum distortion at about 1.1-1.9 s). Possible tension between solar global and KL. KamLAND data. The 2002-04 campaign (confirmation of oscillation at 99.96% C.L.) and the following (up to ‘07) analysis (reduced radioactive bckg and systematic uncertainty and enlarging fiducial volume). Good agreement with solar data with slight tension towards larger values of 1-2 mixing parameters

Recent advancements SNO 3 phases combined analysis: (Phys.Rev. C88 (2013) 025501) (pulse shape analysis of NCD data; data fitted to MC derived PDFs for signal and bckg; new way to parametrize 8B signal) From combined analysis of all SNO data: - 8B n flux: f=5.25±0.16(stat.)±0.12(syst.)×106 cm-2 s-1 , consistent both with SSMs high-Z (BPS09 (GS98) f=5.88±0.65×106 cm-2 s-1 ) and low-Z (BPS09 (AGSS09) (f=4.85±0.58×106 cm-2 s-1 )) Global analysis (all solar + KL): In 3 flavor analysis (reduction of the slight tension between solar and KL). No evidence of D-N asymmetry from SNO; no seasonal variation apart from the annual modulation due to Earth’s orbital eccentricity. 

Toward the sub-MeV analysis: Borexino SK, SNO and KL investigated only the high energy part of solar n spectrum (above 4-5 MeV). Up to 4 years ago the low energy part (main component) of the spectrum studied only by radiochemical exp. Borexino: first real time exp. exploring the sub-MeV region and isolating the monochromatic Berillium line. Measurement of 7Be line (0.862 MeV) and 8B spectrum No oscill. hypothesis ruled out at 5; good agreement with LMA: 48±4 counts/(day∙100 tons) - 2009 Calibration campaign: reduce systematic uncertainties and tune reconstruction algorithm and MC simulations. Significant reduction of uncertainties on the E scale and fiducial volume: from a 6% for both factors to a global uncertainty of 2.7%. 7Be Interaction Rate: 46.0±1.5(stat)±1.3(syst) counts/(day∙100 tons). Cannot discriminate between high and low Z SSM. 8B , with low Ethresh. (T_e > 3 MeV): compatible but less stringent

Borexino: pep and CNO n measurements In SSM, the solar luminosity and the link to pp n constraint the pep n flux, with a small uncertainty (1.2%): ideal probe (after pp) to test SSM. Neutrinos from CNO cycle essential to determine solar core metallicity and important to fuel different stars in various evolution phases 3 continous spectra, with endpoints among 1.19 and 1.74 MeV (N, O, F). Despite their relevance…. until 2011 no direct detection of pep and CNO neutrinos. Electron recoil E spectrum from pep n: Compton like shoulder with 1.22 MeV end point. Bckg reduction even more challenging than in 7Be case (interaction rates at least 10 times lower). New analysis techniques. TFC Three-Fold Coincidence (space and time veto following coincidences between muon signals, cosmogenic neutron and 11C decay ) to reduce main bckg source (for 1<E<2 MeV), that is the b+ emitter 11C produced in scintillator by m and 12C nuclei interactions. Data: Jan ’08- May’10. Addition of pulse shape discrimination. Results (PRL 108 (2012)051302): CNO : f < 7.7x108cm-2s-1 pep: rate=3.1±0.6(stat)±0.3(syst) [c/(day∙100tons] ; f =(1.6 ±0.3)x108cm-2s-1 May 10-Aug 11 purification: very low levels of 86Kr and factor 4 reduction of 210 Bi

Present situation: spectrum consistency Despite the steps forward in 8B and 7Be n study, some key features of oscillation mechanism still must be tested. Example: - the transition between the vacuum dominated and the ‘‘matter enhanced’’ spectrum regions. Partial deficit of low energy 8B neutrinos (explanations?) Theoretical uncertainties on 8B, 7Be and hep n large. Predictions on pp and pep fluxes,instead, strongly constrained by their correlation and by the SSM prediction that pp chain responsible of more than 99% of the Sun energy. Measurement of pp or significant improvements on pep would reduce the indetermination on total luminosity and would be a stringent test of SSM hypothesis. Water Cerenkov (low photon yield): can detect only medium and higher part of the spectrum; Radiochemical exp. measure only integrated n rate above threshold. Important contribution should come from organic scintillators High light yield, large masses and high radiopurity (example Bx):can perform low E solar neutrino spectroscopy. In near future: expected improvements from Borexino (possible also from purification campaign and new signal extraction techniques, like 210Bi bckg reduction) and SNO+

SNO+ New experiment in SNOLAB,that will re-use SNO replacing deuterium with liquid scintillator SNO+ advantages: - mass larger and 2 times deeper than Bx (6080 mwe against 3500 for B and 2700 for KL): better signal/bckg ratio for pep (less 11C); expected 5% uncertainty on pep Physics program: - 0n bb decay; - reactor n and geoneutrinos ; SN n ; - Solar neutrinos: Precision pep flux ; Low E 8B Day-night asimmetry; CNO measurement: solve solar metallicity problem (together with 8B from SNO)?

LENA (Low Energy Neutrino Astronomy) The far future Aim: experiments with LOW E threshold (low signal and radioactive bckg); usually multiporpose devices also for 0n-bb and dark matter searches. Large mass detector and high levels of radiopurity: next generation scintillators, varying from traditional organic scintillators with new technological devices to new materials (noble gases). LENA (Low Energy Neutrino Astronomy) - Next generation liquid scintillator (about 50 ktons). Pyhsalmi underground lab. - ES n-e (as in Bx and SNO+) and CC: ne +13C 13N+e- ) Very precise measurement of 7Be: search for signal modulation; 8B n detection (possible low E: < 3 MeV) ; pep and CNO n difficult, but probably feasible.

Noble liquid scintillators Scintillators with noble gases (Xe, Ar, Ne) - Relatively inexpensive, easy to obtain, dense: large homogeneous detectors; - ‘‘Easily’’ purified, high scintillation yield (30-40 photons/keV), no autoabsorption. CLEAN/DEAP (LNe) - Scaleable technology; Different prototypes in SNOLAB - Aim: Dark matter; real time pp solar n flux (elastic n-e and n-nucleus scattering) - Expected: 15000 photons/MeV and 1% statistical uncertainty on pp -Test of SSM, better determination of q12, study of LMA consistency (in transition region); Try to measure CNO flux with 10-15% accuracy. Alternative LXe (high stopping power and ionization and scint. yields) XMASS - Large massive LXe detector; - Goals: a) WIMPs (dark matter candidates); b) search for 0n bb decay; c) study pp and 7Be solar neutrinos. 2 preliminary phases with prototypes in Kamioka; 20 tons (FV 10 tons). DARWIN (DARk matter Wimp search with Noble liquids)

THE MASS HIERARCHY The recent discovery of non zero and relatively “large” q13 enforced the idea of studying the mass hierarchy by means of new reactor neutrino experiments with medium baseline (tens of km) and high statistic. Idea proposed in 2002 by Petcov & Piai. New generation of liquid scintillator experiments (RENO-50 and JUNO) able to measure precisely the reactor anti-ne energy spectrum and look for shape distortion due to interference effects, which depend on the relative sign of Dm2 (Dm312 and Dm322) with respect to dm122 (dm122=m22-m12) (see also Capolizzi, Lisi and Marrone arXiv:1309.1638 [hep-ph]). The ratio L/E tuned to be at the maximum of the oscillation for the 1-2 sector but also sensitive to the interference with 1-3 and 2-3 oscillation. Sensitivity to mass hierarchy depends on the total mass of neutrino target, E resolution of detector and total thermal power

Experiment is expected to start operation in 2020. JUNO The JUNO (Jiangmen Underground Neutrino Observatory) is a new generation 20 kton liquid scintillator experiment under construction in China, that will study reactor from 2 groups of nuclear reactors, with a medium baseline around 58 km. Target mass around 20 ktons. Large acrylic central detector (d=34.5 m) surrounded by a stainless steel tank: The detector is merged in a water pool, acting as Cerenkov veto detector. E resolution≅(2.5-3)/(E)1/2. Experiment is expected to start operation in 2020.

(taken by Y. Wang PoS (Neutel 2013)) 030 JUNO Main focus: Determine the mass hierarchy (expected 4-5 s level after 6 years) - Precision measurement of oscillation parameters. (taken by Y. Wang PoS (Neutel 2013)) 030 - Study of supernova neutrinos, geoneutrinos and solar neutrinos and search for sterile neutrinos. Current JUNO Dm212 3% 0.6% sin2q12 6% 0.7% Dm223 5% sin2q23 N/A

Mass hierarchy Alternative possibilities for studying mass hierarchy (in addition to very long baselines): analysis of mass effects in atmospheric neutrino oscillations. INO (India-based Neutrino Observatory), magnetized iron calorimeter Cerenkov detectors in ice and water: PINGU (South Pole) and possible implementation in water (ORCA) in the Mediterranean sea (KM3NeT)

BACKUP SLIDES

Estimates for different solar n fluxes SFII – GS98 SFII – AGSS09 Solar pp 5.98∙(1±0.006) 6.03∙(1±0.006) pep 1.44∙(1±0.012) 1.47∙(1±0.012) 7Be 5.00∙(1±0.07) 4.56∙(1±0.07) 8B 5.58∙(1±0.13) 4.59∙(1±0.13) 5.00∙(1±0.03) 13N 2.96∙(1±0.15) 2.17∙(1±0.13) ≤ 6.7 15O 2.23∙(1±0.16) 1.56∙(1±0.15) ≤ 3.2 17F 5.52∙(1±0.18) 3.40∙(1±0.16) ≤ 5.9 Units in cm-2 s-1: 1010 (pp), 109 (7Be), 108 (pep,13N,15O),106 (8B, 17F)