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Beta Beam based on machine upgrades for the LHC

Beta Beam based on machine upgrades for the LHC. Luca Scotto Lavina Università ”Federico II” and INFN, Napoli, Italy. A. Donini, E. Fernandez Martinez, P. Migliozzi, S. Rigolin, L. S. L., T. Tabarelli de Fatis, F. Terranova, hep-ph/0604229 . Otranto, Italy, 15/09/2006. Motivations.

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Beta Beam based on machine upgrades for the LHC

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  1. Beta Beam based on machine upgrades for the LHC Luca Scotto Lavina Università ”Federico II” and INFN, Napoli, Italy A. Donini, E. Fernandez Martinez, P. Migliozzi, S. Rigolin, L. S. L., T. Tabarelli de Fatis, F. Terranova, hep-ph/0604229 Otranto, Italy, 15/09/2006

  2. Motivations • Is there a window of opportunity for neutrino oscillation physics compatible with the machine upgrades of the LHC (>2015)? • Can we immagine an affordable facility that could fully exploit european infrastructures during the LHC era? • Is the sensitivity adequate for an experiment aiming at closure of the PMNS (precision measurement of the 1-3 sector)? Luca Scotto Lavina NOW 2006 15/09/2006

  3. Sensitivity plot vs time for Phase I experiments hep-ph/0606111 1.7° @ 2015 Phase I Phase II 2022 2009 2012 2014 Beam upgrade and HK construction T2K - Nona Data taking... q13 discovery ? 2022 2007 2012 2015 “Phase 2” lumi upgrade of the LHC LHC Energy upgrade? LHC and Double CHOOZ startup End of CNGS

  4. How to approach Phase II in Europe? • Many ideas have been put on the market • Different accelerator technologies • Different baselines • Different detector technologies • We think that Phase II in Europe should be part of a common effort of the Elementary Particle community • Exploit as much as possible technologies common to other fields (e.g. LHC upgrades, EURISOL) • Exploit already existing infrastucture (e.g. LNGS halls) • Costs reduction! Luca Scotto Lavina NOW 2006 15/09/2006

  5. Multi-MW SuperBeam • Technology similar to conventional n beams  • Neutrino beam has contamination from other flavours  • Main source of systematics • Proton driver to be built from scratch  • Useful for Neutrino Factory • Low energy neutrino beams  • Huge low density detectors mandatory (i.e. water Č) • Underground laboratory to be built from scratch (e.g. SPL-Frejus)  • Gran Sasso halls are too small to host Mton detectors Luca Scotto Lavina NOW 2006 15/09/2006

  6. Neutrino Factory • Excellent neutrino beam  • Flux composition very well known • Very challenging technology  • Start operations > 2020 (not suitable in a short term period) • No relevant overlap with CERN accelerators  • Possible the study of the “silver channel” (νe→ν)  • If built at CERN, Gran Sasso Lab maybe too close  Luca Scotto Lavina NOW 2006 15/09/2006

  7. Beta Beam • Excellent neutrino beam  • Flux composition very well known • Possibility to work in νμ appearance mode • νμ CC are an easier channel than ne CC and allows for dense detector • No need to distinguish νμ from anti-νμ • No need for magnetic detectors! • Many energy configurations are envisaged: • g ~ 150 (current design), • g ~ 350 (S-SPS based design), • g > 1000 (LHC based design) Luca Scotto Lavina NOW 2006 15/09/2006

  8. Comparison of the different designs • Current design (EURISOL DS) • Strong synergy with present CERN accelerator complex  • Low energy beam: needs huge and low density detectors  • Underground lab to be built from scratch (e.g. Frejus)  • Counting experiment  • Excellent θ13 and δ sensitivity  • No sensitivity to neutrino hierarchy  • S-SPS • Strong synergy with a LHC energy/luminosity upgrade  • Medium energy beam: small and high density detectors start to be effective  • Underground lab already exists (e.g. Gran Sasso)  • Spectrum analysis possible  • Very good θ13 and δ sensitivity (slightly smaller than current desing)  • Sensitivity to neutrino hierarchy  • NB both designs need an ion decay ring! Luca Scotto Lavina NOW 2006 15/09/2006

  9. The Beta Beam complex . . . + a decay ring Not needed for a Beta Beam Present design lenght: 6880m useful decays: 36% 5 T magnets S-SPS based design lenght: 6880m useful decays: 23% 8.3 T magnets (LHC) Luca Scotto Lavina NOW 2006 15/09/2006

  10. ν Why S-SPS is so interesting? • It is able to bring 6He up to g≤350 (18Ne up to g ≤580) • Neutrino energy above 1 GeV (spectrum analysis) • It is not in contrast with the LHC running ν ν • Iron detectorsare already effective • Fermi motion is no more dominant (energy reconstruction) • Baseline fits the CERN-LNGS distance (730 km) and is large enough to study neutrino hierarchy

  11. The detector at the Gran Sasso See e.g. T.Tabarelli @ LCWS05 Expected unoscillated e CC events per kton-year • 40 ktoniron (4 cm thickness) and glass RPC • Digital readout (2x2 cm2 pads) • No magnetic field • Full GEANT3 simulation but event selection based on inclusive variables only (n. hits, layers etc.)  can be improved with pattern recognition

  12. Event classification Neutrinos with  = 350 Antineutrinos with  = 350 Luca Scotto Lavina NOW 2006 15/09/2006

  13. Signal efficiency and background mis-identification as a function of the neutrino energy Neutrino Antineutrino Luca Scotto Lavina NOW 2006 15/09/2006

  14. Assumptions • Oscillation parametersinput taken from: G.L. Fogli, E. Lisi, A. Marrone, A. Palazzo, hep-ph/0506083 • Three flavour analysis, but only the intrinsic degeneracy (δ-θ13 correlation) is taken into account: sign(Δm223) = +1, θ23 = 45° • We assumed for neutrinos  = 350,580 and antineutrinos  = 350 • We assumed 10 years run • We assumed thenominal beta-beam fluxes (F0) assumed also for  = 100. Not a bad assumption given the γ-duty factor impact on the fluxes, the S-SPS intensityx2 • We assumed a 2% systematic error on the cross-sections. • Realistic assumptions. Minerva, T2K-near will measure μ cross-section in our region of interest with an accuracy better than 2% • There is no need of a “conventional” -beam to measure the μ cross-section (e.g. SPL to Frejus) Luca Scotto Lavina NOW 2006 15/09/2006

  15. Expected number of events after 10 years exposure Luca Scotto Lavina NOW 2006 15/09/2006

  16. The analysis Multi-bin likelihood (bin=0.25 GeV of reconstructed energy) 180 0 -180 0 0 15 15 4 7 13 (deg) 13 (deg) Luca Scotto Lavina NOW 2006 15/09/2006

  17. Discovery potential vs Flux Minimum 13 can be discovered, assuming  = 90° Minimum  can be discovered, assuming 13 = 3° Black curves:  (18Ne)=350 ,  (6He)=350, 10y with “nominal” flux (F0), 99% C.L. Red curves:  (18Ne)=580 ,  (6He)=350, 10y with “nominal” flux (F0), 99% C.L.

  18.  discovery potential F0/2 F0 F0x2 For comparison: SPS-based Beta Beam with Mton-size water Cherenkov detector Left curves:  (18Ne)=350 ,  (6He)=350, 10y run, 99% C.L. Right curves:  (18Ne)=580 ,  (6He)=350, 10y run, 99% C.L. F0 is the “nominal” flux

  19. 13 exclusion plot F0/10 F0/2 F0 F0x2 Left curves:  (18Ne)=350 ,  (6He)=350, 10y run, 90% C.L. Right curves:  (18Ne)=580 ,  (6He)=350, 10y run, 90% C.L. F0 is the “nominal” flux

  20. Neutrino hierarchy Matter effects perturb the transition probabilities Sign of m223 can be distinguished A simultaneous fit of the energy distributions for  and -bar allows to improve the measurement of the neutrino hierarchy We assume the normal hierarchy as the true one. If we assume the inverted hierarchy as the true one, the plot is almost symmetric Black curve:  (18Ne)=350 ,  (6He)=350, 10y with “nominal” flux (F0), 99% C.L. Red curve:  (18Ne)=580 ,  (6He)=350, 10y with “nominal” flux (F0), 99% C.L.

  21. Neutrino hierarchy Normal hierarchy Inverted hierarchy Luca Scotto Lavina NOW 2006 15/09/2006

  22. Conclusions • The Super-SPS option for the luminosity/energy upgrade of the LHC strenghten enormously the physics case of a Beta Beam in Europe • No need of ultra-massive (1Mton) detectors • Possibility to leverage existing underground facilities (Gran Sasso laboratories) • Full reconstruction of the event in nm appearance mode • Baseline appropriate for exploitation of matter effects • If Phase I experiments discover θ13, the proposed BB will be able to measure δCP≠0° down to 30° for θ13≥3° and to measure the sign of Δm223 down to 2° (δCP=+90°) We strongly support a more detailed study of this scenario Luca Scotto Lavina NOW 2006 15/09/2006

  23. S-SPS technology (accidentally) ideal for high-energy BB • It provides a fast ramp (dB/dt=1.21.5 T/s) allowing for a reduction of the ion decays during the acceleration phase • Super-SPS more performant than SPS (x2 intensity, faster cycle) • Fluxes could be smaller than Frejus (higher g means higher lifetime) • High field magnets (11-15 T) in the decay ring would increase the number of useful decays (higher flux) OPTIONAL! • We can allocate more ion bunches in the decay ring because we do not need a <10ns bunch length to get rid of the atmospheric background   • We can recover the losses due to the higher g (… see next slide) Luca Scotto Lavina NOW 2006 15/09/2006

  24. ν The duty cycle issue • In order to reduce theatmospheric backgroundthe timing of the parent ion is needed: • Strong constraint on the number of circulating bunches and on the bunch length In the present design: • bunch length 10 ns (very challenging) (10-3 suppression factor) • 8 circulating bunches Frejus S-SPS With the S-SPS based scenario the atmospheric background is reduced by about a factor 10 and the bunch length can be correspondently increased ν ν

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