n Low energy neutrino scattering: from nuclear physics to neutrino (astro)physics n Cristina VOLPE (Institut de Physique Nucléaire Orsay, France)

OUTLINE Neutrino physics : status and open questions Core-collapse SN neutrinos and neutrino scattering OUTLINE Low energy n-scattering: General aspects Future n-scattering experiments Conclusions

IT REQUIRES THAT NEUTRINOS The conjecture of neutrino oscillations Pontecorvo, 1957 Neutrinos can modify their flavor while travelling. This is the neutrino oscillation phenomenon. SOURCE L DETECTOR ne nm ne nm The oscillation probability Bruno Pontecorvo (1913 – 1993) oscillation amplitude The phenomenon depends on oscillation paramaters. oscillation frequency Dm2 = m22-m12 IT REQUIRES THAT NEUTRINOS ARE MASSIVE.

Recent Advances in Neutrino Physics 1998 : Super-Kamiokande discovers neutrino oscillations. 2000 : SNO measures the total (ne, nm, nt ) solar neutrino flux. 2001 : K2K confirms Super-Kamiokande result. 2002 : KAMLAND determines the solar solution (LMA). 2006 : MINOS measures precisely the atmospheric Dm2. 2007 : Mini-BOONE does not confirm the LSND observation. AN IMPRESSIVE PROGRESS IN THE LAST DECADE in our knowledge of its properties. Ln/En ratio [km/GeV] 1 10 102 103 104 oscillation decoherence decay 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 data/expectation Many puzzles have been solved with an incredible impact on various domains of physics.

THEORETICAL DESCRIPTION ? n3=nt mixing angle q ne nm n1 n2 ne cos q sin q n1 = nm -sin q cos q n2 Dm2 = m22-m12 flavour basis mass basis The time evolution is :

THE 3-flavours OSCILLATION PARAMETERS In the case of three families, there are three mass eigenstates (n1,n2,n3) and three flavour eigenstates (ne,nm,nt). Only two Dm2 are independent. Dm212 Dm322 n3 nm nt q23 The two basis are related by a unitary matrix, called the Maki-Nakagawa-Sakata- Pontecorvo (MNSP) matrix. n2 ne n1 q12 q13 ne n1 nm q13 n2 q23 q12 nt n3 THE CP violating phase INTRODUCES A n-n ASYMMETRY.

THE PRESENT STATUS ? To reconstruct the MNSP mixing matrix : 3 mixing angles, 1 CP Dirac phase, 2 Majorana phases (SNO, Kamland) (Super-Kamiokande, K2K, MINOS, …OPERA) ? ( CHOOZ,...) The Dirac and Majorana phases are unknown. The Dirac phase influence neutrino oscillations, Majorana ones do not. To reconstruct the mass pattern: Experimentally only mass squared differences are known.

A wealth of experiments are under construction or at a R&D level. THE key OPEN QUESTIONS To reconstruct the MNSP mixing matrix The third mixing angle q13 Double-CHOOZ, Daya-Bay, T2K,.. KATRIN, MARE,… Gerda, Cuore, Super-Nemo,… from beta-beams, super-beams, neutrino factories, double-beta decay experiments supernovae, n-factories, double-beta,… The Dirac and Majorana phases (CP violation) To reconstruct the mass pattern The absolute mass scale The mass hierarchy Dm212 Dm213 m2 m1 m3 Mass scale? Inverted Normal The neutrino nature A wealth of experiments are under construction or at a R&D level. exciting discoveries might be close…

q13 – expected sensitivities P. Huber, M. Lindner, T. Schwetz, W. Winter, arXiv: 0907.1861 Discovery potential (90% CL) for sin2 2q13 from reactors and accelerators THE VALUE OF Q13 CRUCIAL FOR FUTURE CP SEARCHES.

Neutrinos in Nature Two diffuse neutrino backgrounds never observed : 10-12 10-8 10-4 100 104 108 1012 1016 1020 1024 Flux (cm-2 s-1 MeV-1) 10-6 10-3 1 103 106 109 1015 1018 meV meV eV keV MeV GeV TeV PeV EeV Neutrino Energy (eV) Cosmological neutrinos Solar n Supernova neutrinos Geo-neutrinos Reactor neutrinos Athmospheric neutrinos n from quasars 330 / cm3 65 milliards / cm2 / s 1058 en 10 s Two diffuse neutrino backgrounds never observed : from the Early Universe and from supernovae

n-oscillations in astrophysics & cosmology Neutrino oscillations are crucial to understand and predict neutrino evolution in several contexts : Neutrinos emitted from the Sun A wealth of solar experiments. Neutrino time and energy spectra from massive stars (core-collapse supernovae) and accretion disk-black hole (AD-BH) scenarios Observatories existing (ex. SK, KamLAND, LVD) or under study, as « megaton detectors »: MEMPHYS, GLACIER, LENA -- LAGUNA Design Study in FP7 -- one of the 7 ASPERA (astroparticle in Europe) priorities Neutrino evolution in the Early Universe Just before Big-Bang Nucleosynthesis

Core-collapse supernovae (SN) 99 % of the energy is emitted as neutrinos of all flavours in a short burst of about 10 s. ne nt nm NS Supernova 1987A Totani et al., Astr.. J. 1998 t (s) 0.1 1. 10 collapse accretion cooling of the neutron star Neutrinos follow closely the explosion. Bring CRUCIAL INFORMATION ON THE EXPLOSION AND unknown n-PROPERTIES.

IMPRESSIVE PROGRESS in the last years Supernova simulations have reached a high degree of complexity (2D-3D, convection, accurate nuclear networks, neutrino transport, the SASI mode,…) Mezzacappa et al, « Ascertaining the core-collapse supernova mechanism: An emerging picture ? », AIP conf. Proc. 924(2007)234 The understanding of neutrino flavour conversion in these explosive phenomna is undergoing a major progress (coupling to matter, to the neutrino-neutrino interaction, shock wave and turbulence effects). Duan, Fuller and Qian,``Collective Neutrino Oscillations,'' arXiv:1001.2799; Duan and Kneller,``Neutrino flavour transformation in supernovae,'' J. Phys. G 36, 113201 (2009) [arXiv:0904.0974. Neutrino-nucleus interactions are important : to understand the nucleosynthesis of heavy elements (neutrino interactions on protons and neutrons «  kills » the r-process in these sites). to determine the response of supernovae observatories)

Future SN observations Several detectors are running (ex. Borexino, Kamland, Super-K,…) . Large-size detectors are under study (LAGUNA DS, FP7, 2008-2010). Future strategy Ando,Beacom,Yuksel PRL95 (2005) To measure the neutrino luminosity curve from a future (extra)galactic explosion (ex. 105 events in MEMPHYS). II. To measure the diffuse supernova neutrino background (sensitive to the star formation rate as well).

ne detection: n-nucleus measurements necessary to determine the supernovae observatories’s response HALO, LENA, GLACIER, MEMPHYS 208Pb 12C 40Ar 16O

SN neutrinos and n-properties : q13 For a supernolva at 10 kpc, Present limit : sin22q13< 0.1 (CHOOZ) In a lead observatory the signal is: (20 MeV) (10 MeV) Engel, McLaughlin,Volpe, PRD67(2003) CC + 2n events depend on the ne average energy and therefore on the value of the third neutrino mixing angle. HALO PROJECT Planned AT SNOLAB.

The search for the third n-mixing angle First calculation including the n-n interaction and shock wave effects. Gava, Kneller, Volpe, McLaughlin, Phys. Rev. Lett. 103 (2009), arXiv:0902.0317 FLUXES ON EARTH adiabatic non-adiabatic ne + p n + e+ POSITRON TIME SIGNAL 29 MeV 15 MeV The dip (bump) can be seen at 3.5 (1) sigma in Super-Kamiokande if a supernova at 10 kpc explodes.. A SIGNATURE IN THE POSITRON TIME SIGNAL IF sin22q13 > 10-5 OR sin2q13 < 10-5

The supernova neutrino background Present limits : 1.08 ne cm-2s-1 from SK (Ene > 19.3 MeV) Malek et al, PRL 90 (2003) & 2009 6.8 103 ne cm-2 s-1 from LSD (25 < Ene < 50 MeV) Aglietta et al. A Phys 1 (1992) The star formation rate is nowadays constrained by various observations. Uncertanties remains, especially at small redshifts (a factor of 2 at z = 0). The star formation rate Yuksel, et al Astrophys. J.683, L5(2008). C. Lunardini, Astr. Phys., 26, 190 (2006) Theoretical predictions on the relic neutrino fluxes are very close to the present upper limit.

DSNB event rates in -observatories There is an energy window free from backgrounds, where neutrinos from past supernovae can be discovered either with advanced technologies or with large size observatories. Wurm et al, PRD 75 (2007) Argon detectors (100 kton). after 10 years Normal Hierarchy Nevents Detection window L S 17.5-41.5 MeV 66 58 4.5-41.5 MeV 106 96 S.Galais, J.Kneller, C.Volpe and J.Gava, to appear in PRD, arxiv:0906.5294

? n  n n = n The neutrino nature bb The search for the nature neutrinoless bb decay bb 76Ge 76As 76Se ? Dirac particle Majorana p. due to Majorana neutrino exchange, physics beyond the Standard Model. bb : 2n  2p + 2e- Lepton-violating process Experiments search THE bb-DECAY observation : A MAJOR DISCOVERY.

The experimental challenge A (debated) claim for evidence. CUORE and GERDA will confirm/refute it and reach about 100 meV sensitivity. < mn> < 0.3 – 1.0 eV The best present upper limit. A large number of projects under study.

The theoretical challenge bb(2n) m b ne (3He, t) (d, 2He) 76As bb 76Ge 76Se Constraints on the calculations come from related weak measurements : beta-decay, muon-capture, charge-exchange reactions, double-beta decay process (2n). The predictions on the half-lives present significant uncertainties. Reducing the uncertainties is a major open problem.

Double-beta decay and n-nucleus 2b(0n): 2n  2p + 2e- The half-life calculations involve many transition matrix elements of high multipolarity. F. Simkovic et al, PRC77 (2008) Volpe, hep-ph/0501233, J. Phys.G.31(2005) One can show that the states involved in neutrinoless double-beta decay due to the exchange a Majorana neutrino are the same states as those excited in neutrino-nucleus interactions. n-NUCLEUS MEASUREMENTS TO GET INFORMATION on THE HIGH MULTIPOLE MATRIX ELEMENTS AND THE VALUE OF gA…

n-physics neutrino scattering Fermi Gas astrophysics nuclear physics

Low-energy neutrino scattering Nuclear Degrees of Freedom Nucleon Degrees of Freedom SUPERNOVA ATMOSPHERE SUN,REACTOR ACCELERATORS 10 50 100 1000 (MeV) 500 n-Energy EFT, Microscopic Approaches (RPA, Shell Model), EPT,… Fermi Gas Experimental data are very scarce (d and 56F, 12C). Theoretical predictions are absolutely necessary. Many calculations exist based on various models.

THEORETICAL ASPECTS ISOSPIN AND SPIN-ISOSPIN MODES are EXCITED. ne e The effective V-A interaction Hamiltonian. Using perturbation theory : The nuclear transition probabilities are the key quantities : exclusive inclusive ISOSPIN AND SPIN-ISOSPIN MODES are EXCITED.

An example of current uncertainties Allowed approximation (qr 0) Comparison of different theoretical predictions for the neutrino-iron cross section. Bertulani and Samana, PRC78 (2008) arXiv:0802.1553 NEED FOR NEW MEASUREMENTS !

INTENSE NEUTRINOS SOURCES CONVENTIONAL SOURCES ne p+ m+ + nm m+ e + nm + ne BETA-BEAMS PS SPS E U R I S O L storage ring n 6Li ne P. Zucchelli, Phys. Lett. B (2002)

PHYSICS STUDIED WITHIN THE EURISOL DS (FP6, 2005-2009) C.Volpe, J Phys G 30 (2004). LOW ENERGY BETA-BEAMS A proposal to establish a facility for the production of intense and pure low energy neutrino beams (100 MeV). PS SPS E U R I S O L storage ring n BASELINE n-nucleus cross sections (detector’s response, r-process, 2b-decay) fundamental interactions studies (Weinberg angle, CVC test, mn) PHYSICS POTENTIAL astrophysical applications close detector n PHYSICS STUDIED WITHIN THE EURISOL DS (FP6, 2005-2009)

NEUTRINO-NUCLEUS MEASUREMENTS Lazauskas and Volpe, NPA 2007 ne + 208Pb 208Bi + e- Pb Bi 0+ 1+ 1- 2+ 3- IAS No exp. info A better knowledge is needed Gamow-Teller Low energy beta-beams: A TOOL TO STUDY SPIN-ISOSPIN EXCITATIONS.

n-nucleus scattering measurements at v n-nucleus scattering measurements at future spallation facilities: SNS,JSNS,ESS?,SPL R. Lazauskas and C. Volpe, in preparation. EVENTS (3 107 s) Predictions on the expected number of events for a detector located at different distances from the source. 1470 384 63 12C 16O 998 261 43 ne 1015 /s 40Ar 1 ton cubic detector 8860 2310 380 56Fe 9100 2330 377 100Mo 17300 420 716 208Pb 34500 8820 1430 Distance(m) 10 20 50

Conclusions & Perspectives Low energy neutrino scattering has timely applications for key open issues in neutrino physics and astrophysics. Accurately predicting the cross sections Is challenging. Related or direct measurements are needed, with future facilities - low energy beta-beams or conventional sources.

Danke. Thank you! Andromeda (M31) Grazie. Merci.