1 Icarus-T600 Collaboration Carlo Rubbia Univ. of Pavia, Italy and INFN, Sezione Pavia (Oct. 3,2006) Progress Report to the SPS-C

SPS-C Oct 3, 2006Slide# : 2 Which is the future of neutrino physics ? lThe experimental results of the recent years have profoundly changed the pattern of neutrino physics.And, very likely, this is only a beginning. lNeutrinos 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. lAll 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. lMaybe 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. lIf 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, 2006Slide# : 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 independent  m 2. lBut 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. lThe 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., l 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, 2006Slide# : 4 LSND: Evidence for (   e ) Beam related backgrounds Excess of events: 87.9  22.4  6.0 Expectation for oscillations Data points after background subtraction lThe experimental evidence is very strong, namely 3.8 s.d. lThe experimental result so far has not been challenged experimentally

SPS-C Oct 3, 2006Slide# : 5 Present experimental status with many possible explanations allowed regions left 1.CPT violation, with LSND related to anti- neutrino and no need of more neutrinos ?? 2.CPT conservation and one or more sterile neutrinos, weakly coupled to ordinary neutrinos. They do interact weakly via W or Z, but standard might oscillate to them ? 3.Which connections to Cosmology ?? Needs experimental confirmations: MiniBoone at FermiLab ICARUS-T600 at CNGS Explanations ??

SPS-C Oct 3, 2006Slide# : 6 BooNE: Booster Neutrino Experiment 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 protonsmesons neutrinos ● 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 horn and targetdecay region absorber dirt (~ 450m ) detector

SPS-C Oct 3, 2006Slide# : 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, 2006Slide# : 8 MiniBoone method for searching for oscillations ? ? ?

SPS-C Oct 3, 2006Slide# : 9 CNGS physics potentials of ICARUS T600 lThe SPS schedule of CNGS foresees nominally 4.5 x10 19 pot/y for the next five years ( ). é This corresponds to a beam related rate ≈ 2500 ev/kton/year with 90 % efficiency of collection. é The T600 raw fiducial volume ≈ 480 t is equivalent nominally 1200 ev/y for 5 years, corresponding to ≈6000 beam related neutrino events. lThe T600 is also collecting simultaneously “self triggered” events. This in particular represents: é ≈ 100 ev/year of individually recorded atmospheric CC cosmic rays. é Solar neutrino electron rates >5 MeV. é A zero background proton decay with 3 x nucleons for”exotic” channels. lT600 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: é 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  m 2 being already measured elsewhere by Soudan and S-K and in the future by OPERA.

SPS-C Oct 3, 2006Slide# : 10 Search for sterile neutrinos at LNGS lBoth LSND and MiniBoone experiments are characterised by é << 1 GeV quasi-elastic events in C with elaborate selection criteria é a relatively short oscillation path from the source to the detector é 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. lIn 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  m 2, which can also be measured.

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

SPS-C Oct 3, 2006Slide# : 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%. lElectron shower events are extremely well identified experimentally, because of the ionization behaviour in the first cells after the vertex. electron (right) and pion (left) in T600

SPS-C Oct 3, 2006Slide# : 13  Single wire performance 10 MeV3.2 MeV 1.8 MeV Two consecutive wires Noise  Threshold above noise ≈ 200 keV

SPS-C Oct 3, 2006Slide# : 14 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 Indicative energy spectra for LSND signals Hypothetical sterile neutrino oscillations (LSDN)  m 2 = 0.4 eV 2 Hypothetical sterile neutrino oscillations (LSDN)  m 2 = 0.2 eV 2 E resolution for contained events ≤ 0.17sqrt(E)

SPS-C Oct 3, 2006Slide# : 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 GeV. The  m 2 distribution extends widely beyond the LNSD and MiniBoone regions. lTwo 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, 2006Slide# : 16 Searching for the  signature. e -, 9.5 GeV, p T =0.47 GeV/c  -  e - + e +  _ CNGS  interaction, E =18.7 GeV 280 cm 105 cm 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. lThe 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, 2006Slide# : 17 How many  are necessary for a “signature”  At the effective neutrino energy of 20 GeV and  m 2 = 2.5E-3 eV 2, 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  m 2 being already measured elsewhere in Soudan and S-K.

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

SPS-C Oct 3, 2006Slide# : 19 General T600 layout Dewar LN 2 (30 m 3 ) Dewar LAr (30 m 3 ) Passive heaters

SPS-C Oct 3, 2006Slide# : 20 SITE T600 Modules T600 parking site Control Rooms ICARUS & OPERA OPERA buildingBAM OPERA Service Area Hall B logistics

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

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

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

SPS-C Oct 3, 2006Slide# : 24 New anti seismic and safety structures underground The steel structure has an anti seismic function. It also contributes to hold a maximum over-pressure of 100 mbar. The insulation will be a closed box, in order to contain hypothetical cryogenic leaks.

SPS-C Oct 3, 2006Slide# : 25 JANFEBMARMAYJUN JUL 2006 Top insulation assembled Instrumentation Cryo roof pass-through 2 nd cryostat in place Projected T600 planning of cryogenics

SPS-C Oct 3, 2006Slide# : 26 ICARUS Cool-down lFilling 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. lThe initial start-up procedure will be as follows: 1.Vacuum phase and cryostat fill with GasAr: 1 LAr truck to be kept in Hall B 2.N2 “pre-cooling”: 7 days duration 1 LN2 truck/2-3 days 3.N2 cooling: 7 days duration 1-2 LN2 trucks/ day 4.LAr filling:10-20 days duration 1-2 LN2 trucks/ day 2-4 LAr trucks/ day lThe normal running procedure will be as follows: é Permanent general LNGS N2 facility: Stierling liquefiers inside the laboratory, presumably ready only by the end of the 2007 é 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, 2006Slide# : 27 SPS 2007 Accelerator Schedule (draft)

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