J. Bouchez CEA/DAPNIA CHIPP Neuchâtel June 21, 2004 A NEW UNDERGROUND LABORATORY AT FREJUS Motivations and prospects

EDELWEISS II Set up Paraffin Ge Lead He NEMO 3 PRESENT EXPERIMENTS

How to overcome superbeam limitations ? Main problem : SPL protons produce less negative pions, so less antineutrinos antineutrino cross-section ~ 5 times smaller than neutrinos So 10 SPL years have to be shared as ~ 2 neutrino + 8 antineutrino years The solution : Produce a e beam to study e    oscillation and run it SIMULTANEOUSLY with   beam from SPL Compare   e and e    (T asymetry, equivalent to CP asymetry) THIS WAS THE INITIAL MOTIVATION FOR A BETA BEAM

BETA BEAMS Concept proposed by Piero Zucchelli Produce radioactive ions (ISOL technique) Accelerate them in the CERN accelerator complex up to  of order 100 Store ions in a storage ring with long straight sections aimed at a far detector Advantages strongly focussed neutrino beam due to small Q value of beta decays (quality factor  /Q) very pure flavour composition (   contamination ~ ) perfectly known energy spectrum Baseline scenario studied at CERN (Mats Lindroos and collaborators) Possible synergy between beta beams and EURISOL (Moriond workshop) Updated study of expected performances (Mauro Mezzetto)

Intensities (original design) Stage 6 He 18 Ne (single target) From ECR source: 2.0x10 13 ions per second0.8x10 11 ions per second Storage ring: 1.0x10 12 ions per bunch4.1x10 10 ions per bunch Fast cycling synch: 1.0x10 12 ion per bunch4.1x10 10 ion per bunch PS after acceleration: 1.0x10 13 ions per batch5.2x10 11 ions per batch SPS after acceleration: 0.9x10 13 ions per batch4.9x10 11 ions per batch Decay ring: 2.0x10 14 ions in four 10 ns long bunch 9.1x10 12 ions in four 10 ns long bunch Only  -decay losses accounted for, add efficiency losses (50%)

baseline scenario updated for new conditions: simultaneous running of He 6 and Ne 18 new values of gamma factors 3 Eurisol targets for Ne 18 antineutrino flux from He 6 ( γ=60) /second neutrino flux from Ne 18 ( γ=100) /second

How to improve the fluxes ? R&D on ISOL targets Increase ion collection time (factor 1.5 to 2) Flat bottom in the SPS (factor 1.5) Faster PS (factor 2 or more due to less transmission losses) Improvement factors of 5 or more seem realistic For the sensitivity studies, improvement factors of 2.8 for He 6 and 6.3 for Ne 18 have been chosen. These numbers will be refined (among others) in the new version of the baseline scenario within 1 year antineutrino flux from He 6 ( γ=60) /second neutrino flux from Ne 18 ( γ=100) /second

Performances of super + beta beams Working hypotheses (Mauro Mezzetto): Announced intensities for e and anti  e (with 3 ISOL targets for Neon ) UNO-like detector installed at a new Frejus underground laboratory 10 years running of both SPL and beta beam : - 2 years of  - 8 years of anti  - 10 years of e - 10 years of anti e Since 18 Ne and 6 He ions do not have the same rigidity, the anti e energy will be 1.67 times the e energy THIS NEEDS TUNING TO FIND THE BEST COMPROMISE

Lorentz boost optimization : Preferred values between  = 55 and 75

Rates for 4400 kT.years cc evts (no osc, nocuts) oscillated at Chooz limit total oscillated (δ=90 0,  =3 0 ) δ term beam background detector background beta beam superbeam He 6 Ne 18 ν μ anti ν γ=60 γ=100 2 y 8 y

 13 sensitivity (δ=0) after 5 years (Minos 2 years) 90%CL

   and  measurements using superbeam and betabeam SPL: 2 years in  + 8 years in anti  BETABEAM: 10 years of 6 He AND 18 Ne (Mauro Mezzetto)

90%CL sensitivity after 5 years (Superbeams νμ only)

99%CL sensitivity to maximal CP violation after 10 years (SPL-SB 2 years + 8 years)

3 σ discovery potential after 10 years

Conclusions Frejus (or TGV) tunnels offer an excellent quality underground site for megaton physics It is a the right distance from CERN to receive neutrino super and/or betabeams The Cerenkov technique is adequate given the low energy of the beams It offers the best sensitivity on  13 and δ compared to similar projects (HyperK, BNL/FNAL) France (IN2P3/CEA) and Italy (INFN) have agreed to join efforts for the promotion of this project There is a successful coordination between nuclear physicists pushing EURISOL and neutrino physicists (common TDS) The first experiment able to detect CP violation could be installed in Europe before 2020, and it would also address the fundamental question of proton stability with some chance of discovery.

Short term: present the project to the SPSC at Villars prestudy results for the cavity write a white paper continue simulations and optimizations

THE END (but to be continued) My warmest thanks to the all the people who have worked hard on this project Special thanks to Mats Lindroos Mauro Mezzetto

Design Study EURISOL Beta-beam Coordination Beta-beam parameter group Above 100 MeV/u Targets 60 GHz ECR Low energy beta-beam And many more… USERS Frejus Gran Sasso High Gamma Astro-Physics Nuclear Physics ( , intensity and duty factor) OTHER LABS TRIUMF FFAG Tracking Collimators US study Neutrino Factory DS Conceptual Design # with price ### M€

scenario 1 (refurbished SPS) He6 350 Ne scenario 2 (LHC)

scenario 1

scenario kt detector at 730 km (off peak)

: to be studied : Is it possible to reach equilibrium at higher gamma ? Need sizeable increase in accelerating power Size of the decay ring cost Which schedule? scenario 1: 2 year stop of SPS, after several years of LHC scenario 2: After LHC programm I consider this project as a potential 2 nd generation beta-beam, not a competitor to the standard beta-beam