New Prospects with Beta-beams Cristina VOLPE (Institut de Physique Nucléaire Orsay, FRANCE)

Recent discoveries in neutrino physics OUTLINE Low-energy beta-beams: potential and feasibility Conclusions and Pespectives The beta-beam project and

THE first OBSERVATION of SOLAR e From fusion reactions, like p+p  2 H+e + + e Raymond Davis, 2002 Nobel Prize with M. Koshiba and R. Giacconi 1970 the detector Homestake mine (South Dakota) 600 tons of C 2 Cl 4 e + 37 Cl 37 Ar + e - « We observe much less neutrinos than we expect. » « THE SOLAR NEUTRINO PUZZLE »

And if neutrinos oscillate ?? Pontecorvo, 1957 e cos  sin  1 =  - sin  cos  2 There are two neutrino basis, the mass (or propagation) basis and the interaction (or flavour) basis : e  1 2    flavour basis mass basis mixing angle If we start with a neutrino source of one flavour, the time evolution is given by ? L m1m1 m2m2

 and  m 2 are called the mixing parameters.  governs the oscillations’ amplitude  m 2 governs the oscillations’ frequency.  m 2 =m m 1 2 E – Neutrino Energy L – Source Detector distance The probability for the appearance of a new neutrino flavor, at a given distance from the neutrino source -- neutrino oscillation -- THE SEARCH LASTED SEVERAL DECADES. SOURCE EnergyL  m 2 (eV 2 ) reactor 5 MeV200 km accelerator 3030 m 1. atmosphere 1 GeV10 4 km10 -4 Varying the E/L ratio, one can explore different oscillation frequencies.

THE DISCOVERY --June EARTH Cosmic ray cos  = 1 20 km km Cosmic ray cos  = -1 Electron and muon neutrinos are produced by the interaction of primary cosmic rays with the atmosphere : The Super-Kamiokande detector       e    e protons PRL81, cos   deficit atmospheric neutrinos NEUTRINOS HAVE MASSES !!!

THE OSCILLATION PARAMETERS In the case of three families, there are three mass eigenstates ( 1, 2, 3 ) and three flavour eigenstates ( e, ,  ).  3  e  1  12  23  13 1  3 e   The two basis are related by a “rotation” (unitary) matrix, called The Maki-Nakagawa-Sakata- Pontecorvo (MNSP) matrix, which is the analog of the Cabibbo-Kobayashi- Maskawa (CKM) matrix for quarks.  INTRODUCES A DIFFERENCE BETWEEN AND : CP Violation.  12  13  23

The beta 6 He Zucchelli, PLB 2002 Lorentz boost 6 He -beam concept Pure, collimated, well-known neutrino fluxes can be obtained by boosted ions decaying through beta-decay.

THE  -BEAM PROJECT ISOL target & Ion source Linac ECR Fast cycling synchrotron SPL (2.2 GeV 2.3x10 14 p/pulse) -STRONG SYNERGY WITH EURISOL -USE CERN EXISTING ACCELERATORS -NEED for A DECAY RING. EURISOL Decay ring Brho= 1500 Tm B=5 T L ss =2500 m Decay Ring 6 He or 18 Ne Autin et al., J. Phys. G 29 (2003). PS SPS  = ions/s Zucchelli, PLB 2002

CERN-to-FREJUS -BEAMS 130 km UNO like Detector 400 kTon Water Cerenkov Detector CERN Geneve FREJUS ( Frejus Underground Laboratory) Neutrino experiments : Study of CP and T violation, by comparing the following oscillation probabilities : CP T (with Beta-beams) (with conventional beams) e   (  +)    e (  + ) e   (  -)    e (  - ) …a rich physics program! Astrophysics studies Supernova neutrinos Proton decay Besides :

M. Mezzetto, Talk at NUFACT05, June 2005, Rome. CP violation sensitivity ONE CAN EXPLORE  13 values as small as 1 degree and  VALUES AS LOW AS 20 degrees. Mezzetto, Nucl. Phys. 143, (2005).

Present situation Low-energy Beta-beams (Standard or “low”) Beta-beams High-energy Beta-beams  =  = 100  >> 100 C. Volpe, Journ. Phys. G. 30 (2004), hep-ph/ G.C. McLaughlin and C. Volpe, Phys. Lett. B 591 (2004),. J. Serreau and C. Volpe, PRC70 (2004), hep-ph/ McLaughlin, Phys. Rev. C70, (2004), nucl-th/ M. Mezzetto, Nucl. Phys. Proc. Suppl.143, (2005). J. Bouchez, M. Lindroos, M. Mezzetto, AIP Conf.Proc.721, 37 (2004). Autin et al., J. Phys. G 29, 1785 (2003), physics/ M. Mezzetto, J. Phys. G29, 1771 (2003) hep-ex/ J. Bernabeu, J. Burguet-Castell, C. Espinoza, M. Lindroos, hep-ph/ electron-capture …. J. Burguet-Castell et al., hep-ph/ J. Burguet-Castell, D. Casper, JJ Gomez-Cadenas, P. Hernandez, F. Sanchez, Nucl. Phys. B695, 217 (2004), hep-ph/ F. Terranova et al, Eur. Phys. J. C38, (2004), hep-ph/ A. Donini et al., Nucl. Phys. B710, 402 (2005), hep-ph/ P. Huber, M. Lindner, M. Rolinec, W. Winter, hep-ph/ See EURISOLDSEURISOLDS

Volpe, Journ. Phys. G. 30 (2004), hep-ph/ Low-energy Beta-beams To exploit the beta-beam concept to produce intense and pure low energy ( MeV, i.e.  = 7-14) neutrino beams. Neutrino scattering on electrons, nuclei C N e e FUNDAMENTAL INTERACTIONS NUCLEAR STRUCTURE C N e e ASTROPHYSICS Joao de Jesus : « Electroweak tests »Nathalie Jachowitz : « Supernovae II »

When a neutrino encounters a nucleus… Nuclear Degrees of Freedom (MeV) 500 Nucleon Degrees of Freedom Neutrino-Energy Nucleus behaves like a Fermi Gas Collective excitations n p It excites collective (and non-collective) states with a change in the spin and/or isospin of the nucleons. e Pb 208 Bi + e - = 30 MeV 50 MeV EXAMPLEEXAMPLE Gamow-Teller IAS spin-dipole little or no experimental information is available.

-Nucleus Interactions: Present status Experimental data are very scarce ( D and 56 F, 12 C). Theoretical predictions are absolutely necessary. Many calculations exist (based on Shell Model, RPA, Effective Field Theory, Elementary Particle Model) : see eg. Brown, Hayes, Kolbe, Fuller, Haxton, Jachowitz, Kubodera, Langanke, Martinez-Pinedo, Mintz, McLaughlin, Oset, Pourkaviani, Vogel, Volpe, Singh, Towner, etc.. The study of such reactions is of interest for: - a better understanding of the nuclear excitations involved, - neutrino experiments (e.g. knowledge of detector response), - nuclear astrophysics (nucleosynthesis of heavy elements). Getting precise predictions in the low-energy range ( MeV) is a challenging task. See the examples of the discrepancies (exp/th) for - 12 C and (between calculations) for Pb. NEED for MORE MEASUREMENTS !

Superallowed (0+ 0+) beta-decay and the Unitarity of the CKM Matrix A better understanding of the isospin breaking in nuclei. A test of the Standard Model.

76 Ge Bobyk et al PRC2001 Contributions to the half-life T 0 1/2 Neutrino-nucleus interactions & Neutrino Nature Majorana or Dirac ?  = 76 Ge 76 As 76 Se  (0 ) Dirac Majorana How do we search for the -nature? Volpe, J. Phys. G 31 (2005), hep-ph/ The states involved in neutrinoless double-beta decay half-lives are the same states as those excited in neutrino- nucleus interactions. 76 Se 76 Ge 76 As NUCLEUS CAN HELP CONSTRAINING THE HALF-LIFE CALCULATIONS.

Low-energy Beta-beams : Feasibility Study A first calculation has shown that a small devoted storage ring is more appropriate for such applications. Serreau and Volpe, PRC 70 (2004) hep-ph/ close detector Injection from PS and SPS is needed (to reach  =7-14) for both 6 He and 18 Ne. Lindroos and Benedikt

close detector PS SPS EURISOLEURISOL Beta-beam baseline at CERN Storage Ring Low-energy Beta-beams : Feasibility Study PRELIMINARY CALCULATIONS! Payet and Chancé (CEA, Saclay) have performed preliminary calculations on the storage ring (size, intensities). Space-charge effects and the duty factor need to be studied. They depend on the filling of PS and SPS -- acceleration issues, by Benedikt and Lindroos.

Conclusions and Perspectives With Beta-beams (  =100) we can study the less known mixing angle  13 and CP violation in the lepton sector (phase  ). Low-energy beta-beams represent a unique opportunity to perform neutrino scattering studies of interest for nuclear structure, for the study of fundamental interactions and for astrophysics. Preliminary calculations on the feasibility. More to come… Low-energy beta-beams might furnish the very first beta-beam.

Andromeda Thank you !