1. Energy Dependence and Physics Reach in regard to Beta/EC Beams J. Bernabeu U. Valencia and IFIC B. Pontecorvo School September 2007

2. Energy Dependence and Physics potential in regard to Beta/EC Beams  Third generation proposals for the CP phase δ  ß Beams: combination 6 He ( )- 18 Ne( ) at the same γ  EC Beams: combination of two energies for the same ion 150 Dy  Comparison between ( low energy E p (SPS) ≤ 450 GeV, Frejus) and (high energy Ep(SPS) ≤ 1000 GeV, Canfranc )

3. The Pontecorvo MNS Matrix  For Flavour oscillations U: 3 mixings, 1 phase Atmospheric KEK More LBL-beams Appearance   e ! Reactor Matter in Atmospheric… Solar KAMLAND Even if they are Majorana After diagonalization of the neutrino mass matrix,

4. Beta Beam Concept P. Zuchelli Design and performance: M. Benedikt, M. Lindroos, M. Mezzetto…

5. Neutrino Oscillation Physics After atmospheric and solar discoveries and accelerator and reactor measurements → θ 13, δ Appearance probability: For Beta Beams, 6 He antineutrino beam combined with 18 Ne neutrino beam 5 years each Intensity of 2.9x10 18 6 He and 1.1x10 18 18 Ne decays per year Detection by charged-current event with a muon in the final state  440 Kton fiducial mass water Cherenkov detector

6. Beta Beams Neutrino Continuous Spectrum implies the need of the reconstruction of the energy in the detector for each event, based on the quasi elastic channel 6 He 18 Ne

7. Fixing the CERN-Frejus baseline  Is the sensitivity to CP Violation and θ 13 changing with energy? For γ > 80, the sensitivity changes rather slowly because the flux at low energies does not reduce significantly. Then it is not advantageous to increase the energy if the baseline is not correspondingly scaled to remain closed to the atmospheric oscillation maximum: remember L/E ! J. Burguet-Castell et al.

8. Fixing γ The maximum energy reachable with the present SPS is γ=150. L = 300 Km is clearly favoured, but … Is the sensitivity to θ13 and δ changing with the baseline?

9. Comparison of two set-ups  Setups with the same γ for both ions  Set up I : γ =120, L=130 Km (Frejus)  Set up II : γ =330, L=650 Km (Canfranc) Set up II needs the upgrade of SPS until E p =1000 GeV Conclusion: Set up II is clearly better. It provides better precision and resolves the degeneracies. J. Burguet - Castell et al.

10. Comparison of two set-ups CP violation exclusion plot at 99% CL. Exclusion plot for θ 13 at 99 % CL. Outlook: R & D effort to design Beta-beams for the upgraded CERN-SPS (E p =1000 GeV) appears justified.

11. Interest of energy dependence in suppressed neutrino oscillations Appearance probability: |Ue3| gives the strength of P(n e → ν μ ) δ acts as a phase shift δ gives the interference pattern: CP odd term is odd in E/L This result is a consequence of a theorem under the assumptions of CPT invariance and absence of absorptive parts This suggests the idea of a monochromatic neutrino beam to separate δ and |Ue3| by energy dependence!

12. Interest of energy dependence in suppressed neutrino oscillations CanfrancFrejus

13. Neutrinos from electron capture Electron capture: From the single energy e - -capture neutrino spectrum, we can get a pure and monochromatic beam by accelerating ec-unstable ions  No need to reconstruct the neutrino energy in the detector ! 2 body decay!  a single discrete energy if a single final nuclear level is populated How can we obtain a monochromatic neutrino beam? Forward direction Z protons N neutrons Z-1 protons N+1 neutrons boost J. Bernabeu et al

14. An idea whose time has arrived ! - In heavy nuclei (rate proportional to square wave function at the origin) and proton rich nuclei (to restore the same orbital angular momentum for protons and neutrons )  Superallowed Gamow-Teller transition The “breakthrough” came thanks to the recent discovery of isotopes with half-lives of a few minutes or less, which decay in neutrino channels near 100% through electron capture to a single Gamow-Teller resonance.

15. Implementation ● The facility would require a different approach to acceleration and storage of the ion beam compared to the standard beta-beam, as the atomic electrons of the ions cannot be fully stripped. ● Partly charged ions have a short vacuum life-time. The isotope we discuss ( 150 Dy) has a half-life ≤ vacuum half-life ~ few minutes. ● For the rest, setup similar to that of a beta-beam. Due to possible problems with space charge if we want to accumulate 10 18 decaying ions per year  Look for an isotope with all the nice properties pointed out before and a half- life near 1 sec. Electron neutrino flux  Notice the proportionality with γ 2 and the monochromaticity Strategy: Put all the intensity at the energy in which the sensitivity to Physics is higher !

16. Experimental set-up for EC 5 years   90 (close to minimum energy to avoid background) 5 years  = 195 (maximum achievable at present SPS) L = 130 km (CERN-Frejus) ● 440 kton water ckov detector Appearance & Disappearance ● 10 18 decaying ions/year Versus 10 years for each γ  the virtues of two energies Set up I (low energy, Frejus): Combine two different energies for the same ion and baseline Set up II (high energy, Canfranc): 5 years  95 ( maximum achievable at present SPS ) 5 years  = 440 (maximum achievable at upgraded SPS) L = 650 km (CERN - Canfranc)

17. Set up I - Disentangling θ 13 and δ Much better separation for two different energies, even with lower statistics Access to measure the CP phase as a phase- shift

18. The virtues of two energies 130 km

19. Set up I: Fit of  13,  from statistical distribution The principle of an energy dependent measurement is working and a window is open to the discovery of CP violation

20. Set up I: Exclusion plot: sensitivity Total running time: 10 years... Significant below 1 o

21. Set up I: Exclusion plot: CP sensitivity Total running time: 10 years... Significant for θ 13 > 4 0

22. Set up II: The virtues of combining two energies 650 km Conclusion: the separation between  13 and  is much better than that for set up I

23. Set up II: Fit of  13,  from statistical distribution Conclusion: the precision reachable for the CP phase is better than that for set up I WITH NEUTRINOS ONLY, AT TWO SELECTED DIFFERENT ENERGIES δ θ 13

24. Set up II: θ 13 sensitivity 0.1 – 0.4 degrees, depending on δ

25. Set up II: Exclusion plot: CP sensitivity Without any previous information on θ 13 …

26. Set up II: δ sensitivity θ 13 δ δ sensitivity < 45º for θ 13 ≥ 3 º. Asymptotically, a δ sensitivity of ± 18º 99 % C L

27. Set up II: Exclusion plot: CP sensitivity IMPRESSIVE !!! If θ 13 previously known …

28. Set up II: δ sensitivity δ sensitivity < 45º for θ 13 ≥ 0.4 º. Asymptotically, a δ sensitivity of ± 8º δ 50 -50 θ 13 13 99 % C L

29. Conclusions  The simulations of the Physics Output for both Beta and EC beams indicate: THE UPGRADE TO HIGHER ENERGY (Ep = 1000 GeV) IS CRUCIAL TO HAVE A BETTER SENSITIVITY TO CP VIOLATION (the main objective of the third generation neutrino oscillation experiments) IFF ACCOMPANIED BY A LONGER BASELINE.  THE BEST E/L FOR HIGHER SENSITIVITY TO THE MIXING U(e3) IS NOT THE SAME THAN THAT FOR THE CP PHASE. Like the phase-shifts, the presence of δ is easier to observe in the region of the second oscillation: Set up II in EC beams has an impressive sensitivity to CPV, particularly if the mixing is previously known. The mixing is better seen around the first oscillation maximum, instead.  Besides the feasibility studies for the machine, MOST IMPORTANT FOR PHYSICS IS THE STUDY OF THE OPTIMAL CONFIGURATION BY COMBINING - Low energy ( 2017(?)) - Frejus (L=130 Km) with Canfranc (L=650 Km), i.e., the decay “ring” should be a triangle and not a rectangle. - EC monochromatic neutrinos with 6He beta- antineutrinos.  MUST DEFINE A PROGRAM TO DETERMINE INDEPENDENTLY THE RELEVANT CROSS SECTION

30.  The result of the synergy of Neutrino Oscillation Physics with LHC- Physics (SPS upgrade) and, in the case of Beta/EC Beams, with Nuclear Physics (EURISOL) for the Facility at CERN, could be completed with the synergy with Astroparticle Physics for a Multipurpose Detector, common to neutrino oscillation studies with terrestrial beams, Atmospheric Neutrinos (neutrino mass hierarchy), supernova neutrinos and Proton decay!!! Outlook MUCHAS GRACIAS!