SuperNO A a longbaseline neutrino experiment with two
Super-NO A a long-baseline neutrino experiment with two off-axis detectors Based on O. Mena, SPR and S. Pascoli hep-ph/0504015 Sergio Palomares-Ruiz June 22, 2005
What we know and what we do not know about neutrinos n We don’t know if there are sterile neutrinos n We don’t know what the absolute mass of neutrinos is n We don’t know what is their nature: Majorana or Dirac n We don’t know what is the mass mechanism n We know that neutrinos do oscillate: have mass n We know that there are only 3 light active neutrinos Sergio Palomares-Ruiz June 22, 2005
n We know Solar sector Reactor sector Atmospheric sector m 221 = (7. 6 - 8. 6) 10 -5 e. V 2 sin 2 13 < 0. 041 | m 231 | = (1. 5 – 3. 4) 10 -3 e. V 2 sin 2 12 = (0. 28 – 0. 33) n n sin 2 2 23 > 0. 92 We don’t know the octant of 23 We don’t know whethere is CP violation in the lepton sector We don’t know the type of mass hierarchy We don’t know whether 13 is different from 0 Sergio Palomares-Ruiz June 22, 2005 O. Mena and S. J. Parke, Phys. Rev. D 69: 117301, 2004
Degeneracies H. Minakata and H. Nunokawa, JHEP 0110: 001, 2001 ( 23 , /2 - 23) n ( , 13) % n n sign( m 231) ~ sin ~ cos % Sergio Palomares-Ruiz June 22, 2005
Resolving degeneracies: ( 23 , /2 - 23) n Atmospheric neutrino experiments n n n Very long-baseline neutrino experiments n n Sub-Ge. V events (solar term) Multi-Ge. V events (matter effect) Through the solar term contribution Neutrino factories and beams n e → and e → Sergio Palomares-Ruiz June 22, 2005
Resolving degeneracies: ( , 13) n Long-baseline neutrino experiments n n Reduce degeneracy under special configurations Reactor neutrino experiments n Only sensitive to 13 n Atmospheric neutrino experiments n Neutrino factories and beams Sergio Palomares-Ruiz June 22, 2005
Resolving degeneracies: sign( m 231) Need of matter effects → 13 0 n Atmospheric neutrino experiments n n Long-baseline neutrino experiments n n Multi-Ge. V events Off-axis experiments Neutrino Factories and beams Sergio Palomares-Ruiz June 22, 2005
Off-axis concept Neutrinos produced in two body decays: → + D. Beavis et al. , BNL Proposal E-889 June 22, 2005 Sergio Palomares-Ruiz
Experimental set-up NO A n n n Medium energy beam 50 (30) kton calorimeter L = 810 km Off-axis distance = 10 km → E = 2. 3 Ge. V 3. 7 (6. 5) x 1020 pot/yr Proton Driver = 18. 5 (25) x 1020 pot/yr Super-NO A n n NO A + another off-axis detector with the same L/E (L = 200 km) We will consider 50 kton Liquid Argon detectors (high efficiency) Only neutrinos 5 years 2 nd detector = Super-No A D. S. Ayres et al. [NO A Collaboration], hep-ph/0503053 June 22, 2005 No A Sergio Palomares-Ruiz
Probabilities n Up to second order in 13, 12/A and 12 L A. Cervera et al. , Nucl. Phys. B 579: 17, 2000 P( → e) = x 2 f 2 + 2 x y f g cos( - ) + y 2 g 2 x ≡ sin 23 sin 2 13 y ≡ ( m 221 / m 231) cos 23 sin 2 12 f ≡ sin( -AL/2)/( - AL/2) g ≡ sin(AL/(2 ))/(AL/(2 )) ≡ m 231 L / (4 E ) June 22, 2005 Sergio Palomares-Ruiz
Asymmetry O. Mena, SPR and S. Pascoli, hep-ph/0504015 June 22, 2005 Sergio Palomares-Ruiz
O. Mena, SPR and S. Pascoli, hep-ph/0504015 June 22, 2005 Sergio Palomares-Ruiz
Bi-event plot for NO A P = A cos + B sin + C It collapses to a line if: P = A cos + B sin + C (AB - AB) cos sin = 0 B=A B = -A cos sin = 0 NO A 0. 9 < < 1. 3 O. Mena, SPR and S. Pascoli, hep-ph/0504015 June 22, 2005 Sergio Palomares-Ruiz
Bi-event plots for Super-NO A PF = AF cos + BF sin + CF PN = AN cos + BN sin + CN It collapses to a line if: (AFBN – ANBF) cos sin = 0 BF = A F BN = A N It is always a line O. Mena, SPR and S. Pascoli, hep-ph/0504015 June 22, 2005 Sergio Palomares-Ruiz
Measurable integrated asymmetry 2 analysis 95% C. L. PD 99% 95% 90% O. Mena, SPR and S. Pascoli, hep-ph/0504015 June 22, 2005 Sergio Palomares-Ruiz
Comparison with NO A and T 2 K D. S. Ayres et al. [NO A Collaboration], hep-ph/0503053 6 yrs + 6 yrs with NO A + 3 yrs with 2 nd detector at second maximum pot/yr = 6. 5 x 1020 pot/yr (PD) = 25 x 1020 12 km off-axis 3 yrs + 3 yrs With Super-No A only 5 yrs to get there Sergio Palomares-Ruiz June 22, 2005
Conclusions n n Resolving degeneracies is a crucial task Super-NO A: 2 off-axis (LAr) detectors with same L/E using the Nu. MI beam → determination of sign( m 231) free of degeneracies Only need of 5 years of neutrino run to resolve the type of hierarchy down to sin 2 2 13 = 0. 02 with Proton Driver (for all values of ) Better capabilities than NO A + T 2 K at HK for determining the type of mass hierarchy Sergio Palomares-Ruiz June 22, 2005
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