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Icarus-T600 Collaboration Carlo Rubbia Univ. of Pavia, Italy and INFN, Sezione Pavia (Oct. 3,2006)

Icarus-T600 Collaboration Carlo Rubbia Univ. of Pavia, Italy and INFN, Sezione Pavia (Oct. 3,2006). Progress Report to the SPS-C. Which is the future of neutrino physics ?.

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Icarus-T600 Collaboration Carlo Rubbia Univ. of Pavia, Italy and INFN, Sezione Pavia (Oct. 3,2006)

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  1. Icarus-T600 CollaborationCarlo RubbiaUniv. of Pavia, Italyand INFN, Sezione Pavia(Oct. 3,2006) Progress Report to the SPS-C

  2. Which is the future of neutrino physics ? • The experimental results of the recent years have profoundly changed the pattern of neutrino physics.And, very likely, this is only a beginning. • Neutrinos have been shown to strongly oscillate between available flavours while they propagate through space, whenever a sufficient distance is provided from the source (solar, cosmic, accelerator or reactor) and the detector. • All produced and observed neutrinos and antineutrino have left-handed or right-handed helicities. These are the only chiralities included in the Standard Model. But since they have mass, the presence of other chiralities is not without problems. • Maybe their counterparts (right-handed neutrinos and left-handed antineutrinos) simply do not exist and neutrino and antineutrino are in fact the same particle. The key experiment for the search of Majorana neutrinos is the neutrino-less double beta decay, actively investigated at the Gran Sasso. • If their counterparts instead do exist, it may be that their properties are substantially different from the ones of observable neutrinos and antineutrinos. SPS-C Oct 3, 2006

  3. How many neutrinos are present in nature ? • According to the LEP result, three different neutrinos are coupled with Z-bosons. Consequently there are only 2 independentDm2. • But the possibility of one or more additional, “sterile” kinds of neutrino — namely of neutrinos which do not participate in the weak interactions — is unaffected by these Z-boson-based measurements. • The existence for such additional neutrino particles has been claimed by a Los Alamos experiment called LSND, in which they have been created through oscillations from ordinary neutrinos. , • It is possible that neutrinos are something very different than just a neutral counterpart of charged leptons and may couple to another segment of the Universe, the one of sterile neutrinos, which do not see fully ordinary electro-weak interactions but still introduce mixing oscillations with ordinary neutrinos. SPS-C Oct 3, 2006

  4. LSND: Evidence for(e) Expectation for oscillations Beam related backgrounds Data points after background subtraction Excess of events: 87.9  22.4  6.0 • The experimental evidence is very strong, namely 3.8 s.d. • The experimental result so far has not been challenged experimentally SPS-C Oct 3, 2006

  5. Present experimental status with many possible explanations Explanations ?? allowed regions left • CPT violation, with LSND related to anti-neutrino and no need of more neutrinos ?? • CPT conservation and one or more sterile neutrinos, weakly coupled to ordinary neutrinos. They do interact weakly via W or Z, but standard nmight oscillate tothem ? • Which connections to Cosmology ?? • Needs experimental confirmations: • MiniBoone at FermiLab • ICARUS-T600 at CNGS SPS-C Oct 3, 2006

  6. BooNE: Booster Neutrino Experiment horn and target decay region absorber dirt (~450m) detector protons mesons neutrinos Y. Liu, I. Stancu Alabama S. Koutsoliotas Bucknell E. Hawker, R.A. Johnson, J.L. Raaf Cincinnati T. Hart, E.D. Zimmerman Colorado Aguilar-Azevedo, L. Bugel, J.M. Conrad, J. Formaggio, J. Link, J. Monroe, D. Schmitz, M.H. Shaevitz, M. Sorel, G.P. Zeller Columbia D. Smith Embry Riddle L. Bartozek, C. Bhat, S.J. Brice, B.C. Brown, D.A. Finley, B.T. Fleming, R. Ford, F.G. Garcia, P. Kasper, T. Kobilarcik, I. Kourbanis, A. Malensek, W. Marsh, P. Martin, F. Mills, C. Moore, P.J. Nienaber, E. Prebys, A.D. Russell, P. Spentzouris, R. Stefanski, T. Williams Fermilab D.C. Cox, A. Green, H.O. Meyer, R. Tayloe Indiana G.T. Garvey, C. Green, W.C. Louis, G. McGregor, S. McKenney, G.B. Mills, V. Sandberg, B. Sapp, R. Schirato, R. Van de Water, D.H. White Los Alamos R. Imlay, W. Metcalf, M. Sung, M.O. Wascko Louisiana State J. Cao, Y. Liu, B.P. Roe Michigan A.O. Bazarko, P.D. Meyers, R.B. Patterson, F.C. Shoemaker, H.A. Tanaka Princeton • 12 meters spherical steel tank • 250,000 gallons of mineral oil (800 tons) • 1280 PMT's in the main region (5.75 meters) • 240 PMT in veto region • Neutrino interactions in oil produce light (Cherenkov and scintillation) • We measure time and charge for each tube SPS-C Oct 3, 2006

  7. MiniBoone proposal:signal and backgrounds (Montecarlo) Cross sections estimates for nuclear target, especially at low energies, have been widely underestimated in the original proposal SPS-C Oct 3, 2006

  8. MiniBoone method for searching for oscillations ? ? ? SPS-C Oct 3, 2006

  9. CNGS physics potentials of ICARUS T600 • The SPS schedule of CNGS foresees nominally 4.5 x1019 pot/y for the next five years (2007-2012). • This corresponds to a beam related rate ≈ 2500 ev/kton/year with 90 % efficiency of collection. • The T600 raw fiducial volume ≈ 480 t is equivalent nominally 1200 ev/y for 5 years, corresponding to ≈6000 beam related neutrino events. • The T600 is also collecting simultaneously “self triggered” events. This in particular represents: • ≈ 100 ev/year of individually recorded atmospheric CC cosmic rays. • Solar neutrino electron rates >5 MeV. • A zero background proton decay with 3 x 1032 nucleons for”exotic” channels. • T600 is a necessary intermediate technical step towards a much more massive LAr detector (3.3 kT LAr are equivalent to 20 kt NOVA scintillator), now being actively studied by INFN and US(Fermilab), but it offers also some interesting physics in itself. In the presentation I shall limit myself to two main topics: • Searching for sterile neutrinos in T600 with deep e-like inelastic CC events, complementary to MiniBoone • The proof of existence of decay with T600, the actual value of m2 being already measured elsewhere by Soudan and S-K and in the future by OPERA. SPS-C Oct 3, 2006

  10. Search for sterile neutrinos at LNGS • Both LSND and MiniBoone experiments are characterised by • << 1 GeV quasi-elastic events in C with elaborate selection criteria • a relatively short oscillation path from the source to the detector • The addition of substantial competing backgrounds due to misinterpreted events. • Therefore the signal should appear as an event excess peaking at low values of the visible energy. • In contrast, the CNGS beam and the ICARUS “bubble chamber” identification is based on: • Deep inelastic -e CC events recorded in the minimum bias mode. • Extremely good background discrimination, limited only to the intrinsic beam e contamination: ≤0.5% in the chosen E interval of 10 ÷ 30 GeV. • Excellent electron discrimination against converted ’s because of the differences in ionization losses in the earliest part of the track (No NC backgrounds). • Very long path-length which ensures several oscillations from source to detector in the foreseen LSND window, but still wide enough in order to identify maxima and minima related to m2, which can also be measured. SPS-C Oct 3, 2006

  11. Reconstructed CC events in T600 e-,15 GeV, pT=1.16 GeV/c 120 cm CNGS e interaction, E=16.6 GeV Vertex: 10,2p,3n,2 ,1e- 290 cm CNGS  interaction, E=21.3 GeV 80 cm Vertex: 3,5p,9n,3,1 300 cm SPS-C Oct 3, 2006

  12. Events with leading electron signature. • The basic spectrum of LNGS is made of  with a most probable energy in the order of 25 GeV. • The  spectrum has also been calculated and found to to be accurate to about 5%. • Electron shower events are extremely well identified experimentally, because of the ionization behaviour in the first cells after the vertex. SPS-C Oct 3, 2006 electron (right) and pion (left) in T600

  13. Single wireperformance   1.8 MeV 3.2 MeV 10 MeV Two consecutive wires Noise SPS-C Oct 3, 2006 Threshold above noise ≈ 200 keV

  14. Indicative energy spectra for LSND signals Hypothetical sterile neutrino oscillations (LSDN) m2 = 0.4 eV2 Hypothetical sterile neutrino oscillations (LSDN) m2 = 0.2 eV2 E resolution for contained events ≤ 0.17sqrt(E) E:10 ÷ 30 GeV N():4635 N(e,beam): 18.8 N(e,oscill): 45.5 E:10 ÷ 30 GeV N():4635 N(e,beam): 18.8 N(e,oscill): 94.9 SPS-C Oct 3, 2006

  15. Limits at T600 with 6000 events. • Sensitivity region, in terms of Standard Deviations , for 6000 raw CNGS neutrino events. The potential signal is above the background generated by the intrinsic e beam contamination, in the deep inelastic interval 10-30 GeV. • The m2 distribution extends widely beyond the LNSD and MiniBoone regions. • Two indicated points are reference values of MiniBoone proposal and of previous slide T600 at the CNGS offers an unique possibility of searching for sterile neutrinos, largely complementary and comparable to the Fermilab programme. SPS-C Oct 3, 2006

  16. Searching for the  signature. CNGS  interaction, E=18.7 GeV 280 cm e-, 9.5 GeV, pT=0.47 GeV/c 105 cm _ -  e- +  e +  • The original international proposal for T1800, recently cancelled by lack of funding, would have ensured a number of events adequate to cover the signature with a sensitivity comparable to the one OPERA. • The electron decay channel is however quite significant goal also for the presently reduced T600 mass, uniquely characterized by a large transverse momentum unbalance due to the emission of the two neutrinos. SPS-C Oct 3, 2006

  17. How many  are necessary for a “signature”  • At the effective neutrino energy of 20 GeV and m2 = 2.5E-3 eV2, the expected =>  is 1.4%. Therefore for 6000 CNGS events in the T600 we expect 84 raw  events. • The branching ratio for  => eis 16%; hence we expect 13.4 electron deep inelastic events, in addition to the ≈ 14 intrinsic beam associated e with energy <20 GeV. This is already “per-se” a significant effect, namely with 27.4 electron events observed vs. 14 ± 3.7 expected (3.6 s.d.). • Events are absolutely clean and they are characterised by a momentum unbalance because of neutrino emission and a relatively low electron momentum. Selection criteria suggest a sufficiently clean separation from intrinsic beam associated e with kinematic cuts and an efficiency of 50%. • Therefore one should expect about 7 ± 2.6  => e events, some of which, hopefully, gold plated. • This should be sufficient for a proof of existence, the actual value of m2 being already measured elsewhere in Soudan and S-K. SPS-C Oct 3, 2006

  18. e balanced events or tau decays ? + LSND like sterile neutrinos  -> e decays Likelihood weight Likelihood distributions may separate an hypothetical LSND excess from the expected presence of  decays SPS-C Oct 3, 2006

  19. General T600 layout Dewar LN2 (30 m3) Dewar LAr (30 m3) T600 Passive heaters SPS-C Oct 3, 2006

  20. Hall B logistics OPERA building BAM north Control Rooms ICARUS & OPERA SITE T600 OPERA Service Area WARP Modules T600 parking site SPS-C Oct 3, 2006

  21. Transport to LNGS Leaving from Seregno September 18th. The base insulation at Seregno SPS-C Oct 3, 2006

  22. Incoming Flying over OPERA. to the working area. … in the Hall Sept. 20th@ HALL B! Incoming… SPS-C Oct 3, 2006

  23. Sept. 22th,@ Seregno The lateral panels on the road. SPS-C Oct 3, 2006

  24. New anti seismic and safety structures underground • The steel structure has an anti seismic function. It also contributesto hold a maximum over-pressure of100 mbar. • The insulation will be a closed box, in order to contain hypothetical cryogenic leaks. SPS-C Oct 3, 2006

  25. Projected T600 planning of cryogenics 2006 JUL JAN FEB MAR MAY JUN 2nd cryostat in place Cryo roof pass-through Top insulation assembled Instrumentation SPS-C Oct 3, 2006

  26. ICARUS Cool-down • Filling the T600 requires 2 x 275’000 litres (786.5 tons) of L Ar to be transported by trucks from the outside into Hall B. • The initial start-up procedure will be as follows: • Vacuum phase and cryostat fill with GasAr: 1 LAr truck to be kept in Hall B • N2 “pre-cooling”: 7 days duration 1 LN2 truck/2-3 days • N2 cooling: 7 days duration 1-2 LN2 trucks/ day • LAr filling: 10-20 days duration 1-2 LN2 trucks/ day 2-4 LAr trucks/ day • The normal running procedure will be as follows: • Permanent general LNGS N2 facility: Stierling liquefiers inside the laboratory, presumably ready only by the end of the 2007 • Intermediate start up phase with additional N2 trucks from outside (to be authorized) for the duration period before STIERLING/tank delivery 1 LN2 trucks/ 1-3 days SPS-C Oct 3, 2006

  27. SPS 2007 Accelerator Schedule (draft) SPS-C Oct 3, 2006

  28. Conclusion In all likelihood, the T600 detector may be able to run for a major fraction of the 2007 schedule ! SPS-C Oct 3, 2006

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