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R. Sulej National Centre for Nuclear Research, Otwock/Swierk Poland

Sterile n search with the ICARUS T600 in the CNGS beam. R. Sulej National Centre for Nuclear Research, Otwock/Swierk Poland for the ICARUS Collaboration. XV International Workshop on Neutrino Telescope Venice 11-15 March 2013. Outline. 1 . Sterile n and LSND/MiniBooNE anomaly

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R. Sulej National Centre for Nuclear Research, Otwock/Swierk Poland

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  1. Sterile n search with the ICARUS T600 in the CNGS beam R. Sulej National Centre for Nuclear Research, Otwock/Swierk Poland for the ICARUS Collaboration XV International Workshop on Neutrino TelescopeVenice 11-15 March 2013

  2. Outline • 1. Sterile n and LSND/MiniBooNE anomaly • 2. ICARUS T600 LAr TPC at LNGS • Detector operation and performance • 3. Sterile neutrinos search in the CNGS beam • Experimental search for the „LSND anomaly” with theICARUS detector in the CNGS neutrino beam, Eur. Phys. J. C (arXiv:1209.0122) • ne signal selection • Results • 4. Conclusions Neutrino Telescopes, 11-15 March 2013

  3. The new frontier • The discovery of a Higgs boson at CERN/LHC has crowned the successful Standard Model (SM) and will call for a verification of the Higgs couplings to the gauge bosons and to the fermions. • Neutrino masses and oscillations represent today a main experimental evidence of physics beyond the Standard Model. • Being the only elementary fermions whose basic properties are still largely unknown, neutrinos must naturally be one of the main priorities to complete our knowledge of the SM. • Albeit still unknown precisely, the incredible smallness of the neutrino rest masses, compared to those of other elementary fermions points to some specific scenario, awaiting to be elucidated. • The astrophysical importance of neutrinos is immense, so is their cosmic evolution. Neutrino Telescopes, 11-15 March 2013

  4. Sterile neutrinos ? • Sterile neutrinos:hypothesized in a seminal paper by B.Pontecorvo in 1957, as particles not interacting via any of fundamental interactions of SM except gravity. • Since per se they may not interact directly, they are extremely difficult to detect. If they are heavy enough, they may also contribute to cold dark matter or warm dark matter. • Sterile n’s may mix with ordinary neutrinos via a mass term. Evidence may be building up by “anomalies” observed by several experiments: • - sterile n(s) with Dm2≈10-2-1 eV2 from ne observation in nm beam • accelerator experiment, „LSND anomaly” • -ndisappearance may have been observed in nuclear reactors and • very intense (megaCurie) e-conversion n sources withmaybe • comparable mass differences. Neutrino Telescopes, 11-15 March 2013

  5. Overall evidence Combined evidence s ≈ 3.8 Zhang, Qian, Vogel: „Reactor (…) with known θ13” (arXiv:1303.0900) →s ≈ 1.4 ? Combined evidence for some possible anomaly: many standard deviations. Neutrino Telescopes, 11-15 March 2013

  6. Neutrino related anomalies Allowed LSND and MiniBooNE signals ICARUS T600 search for the LSND like nm→ne signal from the CNGS nm beam at 730 km and 10 ≤ En ≤ 30 GeV is presented. Neutrino Telescopes, 11-15 March 2013

  7. ICARUS Collaboration M. Antonelloa, P. Aprilia, B. Baibussinovb, M. Baldo Ceolinb,, P. Benettic, E. Calligarichc, N. Cancia, S. Centrob, A. Cesanaf, K. Cieslikg, D. B. Clineh, A.G. Coccod, A. Dabrowskag, D. Dequalb, A. Dermenevi, R. Dolfinic, C. Farneseb, A. Favab, A. Ferrarij, G. Fiorillod, D. Gibinb, A. Gigli Berzolaric,, S. Gninenkoi, A. Guglielmib, M. Haranczykg, J. Holeczekl, A. Ivashkini, J. Kisiell, I. Kochanekl, J. Lagodam, S. Manial, G. Mannocchin, A. Menegollic, G. Mengb, C. Montanaric, S. Otwinowskih, L. Perialen, A. Piazzolic, P. Picchin, F. Pietropaolob, P. Plonskio, A. Rappoldic, G.L. Rasellic, M. Rossellac, C. Rubbiaa,j, P. Salaf, E. Scantamburloe, A. Scaramellif, E. Segretoa, F. Sergiampietrip, D. Stefana, J. Stepaniakm, R. Sulejm,a, M. Szarskag, M. Terranif, F. Varaninib, S. Venturab, C. Vignolia, H. Wangh, X. Yangh, A. Zalewskag, A. Zanic, K. Zarembao. a Laboratori Nazionali del Gran Sasso dell'INFN, Assergi (AQ), Italy b Dipartimento di Fisica e INFN, Università di Padova, Via Marzolo 8, I-35131 Padova, Italy c Dipartimento di Fisica Nucleare e Teorica e INFN, Università di Pavia, Via Bassi 6, I-27100 Pavia, Italy d Dipartimento di Scienze Fisiche, INFN e Università Federico II, Napoli, Italy e Dipartimento di Fisica, Università di L'Aquila, via Vetoio Località Coppito, I-67100 L'Aquila, Italy f INFN, Sezione di Milano e Politecnico, Via Celoria 16, I-20133 Milano, Italy g Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Science, Krakow, Poland h Department of Physics and Astronomy, University of California, Los Angeles, USA i INR RAS, prospekt 60-letiya Oktyabrya 7a, Moscow 117312, Russia j CERN, CH-1211 Geneve 23, Switzerland k Institute of Theoretical Physics, Wroclaw University, Wroclaw, Poland l Institute of Physics, University of Silesia, 4 Uniwersytecka st., 40-007 Katowice, Poland m National Centre for Nuclear Research, A. Soltana 7, 05-400 Otwock/Swierk, Poland n Laboratori Nazionali di Frascati (INFN), Via Fermi 40, I-00044 Frascati, Italy o Institute of Radioelectronics, Warsaw University of Technology, Nowowiejska, 00665 Warsaw, Poland p INFN, Sezione di Pisa. Largo B. Pontecorvo, 3, I-56127 Pisa, Italy Neutrino Telescopes, 11-15 March 2013

  8. ICARUS @ LNGS: the first LARGE LAr-TPC Hall B cathode LN2 vessels cryogenics (behind) 1.5m readout electronics T300 T300 E E T300 module: two TPCs with the common cathode • Twoidentical T300 modules (2 TPC chambers per module) • LAractive mass 476 t: • (17.9 x 3.1 x 1.5 for each TPC) m3; • driftlength = 1.5 m; • Edrift = 0.5 kV/cm; vdrift = 1.6 mm/ms • 3 readout wire planesat 0°, ±60°,3mm planespacing (for each TPC chamber): •  53000 wires, 3 mm pitch • 2 Induction planes, 1 Collection • PMT for scintillation light (128 nm): • (20+54) PMTs • trigger and t0 readoutwirearrays • Total energy reconstruction of events from charge integration. • Full sampling, homogeneouscalorimeter;excellent accuracy for containedevents. Neutrino Telescopes, 11-15 March 2013

  9. ICARUS LAr-TPC detection technique • 2D projection for each of 3 wire planes per TPC • 3D spatial reconstruction from stereoscopic 2D projections • charge measurement from Collection plane signals Collection (top view) Induction 2 (top view) Induction 1 (frontal view) CNGSnm charge current interaction, one of TPC’s shown Neutrino Telescopes, 11-15 March 2013

  10. Key feature: LAr purity I MODULE II MODULE 60 ppt O2 equiv. max drift Impurities from electro-negative molecules: O2, H2O, CO2 • Ultra High Vacuum techniques; highlyefficient filters based on Oxysorb/Hydrosorb; • Continuous purification by recirculation in liquid & gas phases; • During data taking: te > 5ms ≈ 60 ppt O2 equivalent impurities  max. 17% signal attenuation after 1.5m for the longest e– drift length, Edrift =0.5kV/cm. Neutrino Telescopes, 11-15 March 2013

  11. CNGS data taking: 2010-2012 • CNGS data taking (Oct. 2010 – Dec. 2012) • large sample of n interactions • superluminal n searches • 1. Cherenkov-like e+e– emissions: P. L. B711 (2012) 270 • 2. timing measurement: P. L. B713 (2012), 17 • 3. precision measurement: JHEP 11 (2012) 049 • n oscillations • nm→ntt-→ e– ne nt • nm→ne ”LSND/MiniBooNE” anomaly • in press: Eur. Phys. J. C,arXiv:1209.0122 detector live-time > 93% total 8.6 x 1019 pot collected 2010: Oct. 1 – Nov. 22 5.8 1018 pot 2011: Mar. 19 – Nov. 14 4.44 1019 pot 2012: Mar. 23 – Dec.3 3.54 1019 pot Neutrino Telescopes, 11-15 March 2013

  12. LAr TPC performance Total energy reconstr. from charge integration • Full sampling, homogeneous calorimeter with excellent accuracy for contained events Tracking device • Precise 3D topology and accurate ionization • Muon momentum via multiple scattering Measurement of local energy deposition dE/dx • e/gremarkable separation (0.02 X0 samples) • Particle identification by dE/dx vs range nmCC energy deposit Low energy electrons: σ(E)/E = 11% / √ E(MeV)+2% Electromagn. showers: σ(E)/E = 3% / √ E(GeV) Hadron showers: σ(E)/E ≈ 30% / √ E(GeV) 1 m.i.p. data dE/dx vs residual range compared to Bethe-Bloch curves 2 m.i.p. Neutrino Telescopes, 11-15 March 2013

  13. Precise particle tracking and identification CNGS beam primary vertex kaon New 2D => 3D approach for LAr TPC (in press: AHEP, arXiv:1210.5089) 3D objectdriven by optimization of its 2D projections (no need for driftmatching) cathode Induction Collection p 3D reconstruction dE/dx based PID K  μ Neutrino Telescopes, 11-15 March 2013

  14. dE/dx of muon tracks in CNGS Ek = 2.14GeV, length = 10.0 m Collection long muon from nm CC interaction Induction2 • muon track: • reconstructed withCollection and Induction2 • projected to Induction1 MC: m=2.37 MeV/cm; RMS=1.37 data: μ=2.32 MeV/cm; RMS=1.31 Induction1 (a) Induction1 (b) dE/dx in 3 mm track segments (3D), after removing d rays and e.m. cascades MC – data agreement on the level of 2% signal/noise from Landau + gaussian ≈10 Neutrino Telescopes, 11-15 March 2013

  15. e/g separation: dE/dx in cascade initial part pπo = 912 ± 26 MeV/c mπo = 127 ± 19 MeV/c² θ = 28.0 ± 2.5º p0 reconstruction: Ek = 102 ± 10 MeV θ • MC: single electrons (Compton) • MC: e+ e– pairs (g conversions) • data: EM cascades (from p0 decays) Ek = 685 ± 25 MeV Collection 2 m.i.p. • ~0.02 X0sampling; g’s separated from vtx; • g rejection increases with energy; • e selection efficiency const with energy; 1 m.i.p. 2 m.i.p. 1 m.i.p. MC Neutrino Telescopes, 11-15 March 2013

  16. A search for LSND effects with ICARUS at CNGS • nm→ne signal from the CNGS nm beam at: L = 730 km, 10 ≤ En ≤ 30 GeV • Differences w.r.t. the LSND experiment: • L/En ≈ 1 m/MeV at LSND, butL/En≈36.5 m/MeV at CNGS • LSND-like short distance oscillation signal • averages to: sin2(1.27Dm2new L /E) ≈½ • and: <P>nm→ne≈ 1/2 sin2(2qnew) • When compared to other long baseline results (MINOS and T2K) ICARUS operates in a L/En region in which contributions fromstandard neutrino oscillations are not yet too relevant. • Unique detection properties of LAr-TPC allows to identify individual neeventswith high efficiency. Neutrino Telescopes, 11-15 March 2013

  17. Data sample • CNGS neutrinos:almost pure nmpeaked in the range 10 ≤ En ≤ 30GeV • beam associated ne about ~1% • CNGS events triggered by PMT signal inside SPS proton extraction gate • empty events rejection, few n interactions/day • Present sample: 1091neutrino events (within 6% with MC expectation) • data from 2010 and 2011, 3.3 x 1019 pot (out of total 8.6 x 1019 pot collected) • nm CC events identified by L>250 cm track from primary vtx, no hadr interaction • the signature of the nm→ne signal is observed visually • Fiducial volume: • primary vertex min. 5 cm from each side, min. 50 cm from downstream wall to allowshower identification • Energy deposition cut: < 30 GeV • optimized signal/background ratio (necontamination extends to higher En), only 15% signal events rejected • excellent MC/data agreement for deposited energy  negligible syst. error on signal and bkg expectations • 10% syst. error due to ne beam component Neutrino Telescopes, 11-15 March 2013

  18. Signal selection Visibility cuts for nm→ne event identification: Charged track from the vertex, m.i.p. over 8 wires (dE/dx < 3.1 MeV/cm excluding d-rays), developing into EM-shower Spatial separation (150 mrad) from other tracks at the vertex, at least in one transverse (±60°) view • Expected conventional ne– like events: • (cuts: vtx in fiducial volume; visible energy ≤ 30 GeV) • 3.0 ± 0.4ev. due to the intrinsic nebeam contamination • 1.3 ± 0.3 ev. due to q13 oscillations, sin2(q13) = 0.0242 ± 0.0026 • 0.7 ± 0.05 ev. of nm→ntoscillations with electron production, 3n mixing predictions. • The total is therefore of 5.0 ± 0.6 expected events(uncertainty on the NC and CC contaminationsincluded) • Selection efficiency, validated on MC sample of ne events: h=0.74±.05 • in a good approximation, h independent from shape of energy spectrum • 3.7 ± 0.6 expected background events after cuts. Neutrino Telescopes, 11-15 March 2013

  19. Signal selection efficiency in MC simulation • ne events generated according to nm spectrum in order to reproduce oscillation behaviour; • full physics and detector MC simulation in agreement with data • 122 events over 171 simulated inside the detector, satisfy fiducial volume and energy cuts; • visibility cuts: (3 independent scanners), leading to 0.74 ± 0.05 efficiency; • < 1% systematic error from dE/dx cut on the initial part of cascade; • no ne-like events selected among NC simulated sample of 800 events. Typical MC event En= 11 GeV, pt= 1.0 GeV/c. (only the vertex region is shown) Neutrino Telescopes, 11-15 March 2013

  20. Signal selection efficiency check in MC simulation • automatic cutsmimickingdata selection, largesample of MC • C1: inside fiducial volume and Edep < 30 GeV; • C2: no identified muon, at least one shower; • C3: one shower: initial point (orgconversion point)< 1 cm from vtx, separated from other tracks; • C4: ionisation signal from single mipin the first 8 wires. Signal selection efficiency (after the fiducial and energy cuts): 0.6/0.81=0.74,in agreement with the visual scanning method. Neutrino Telescopes, 11-15 March 2013

  21. 2 events observed in data a b (a)Etot = 11.5 ± 1.8 GeV, pt = 1.8 ± 0.4 GeV/c (b)vis Etot = 17 GeV, pt = 1.3 ±0.18 GeV/c In both events: single electron shower in the transverse plane clearly opposite to hadronic component Neutrino Telescopes, 11-15 March 2013

  22. The observation is presently compatible with the absence of a LSND anomaly • The limits on no. of events due to the LSND anomaly are respectively 3.41 (90% CL) and 7.13 (99% CL) • Given the present data sample of, the limits to the oscillation probability are: Pνμ→νe ≤ 5.4 x 10-3 (90% CL) Pνμ→νe ≤ 1.1 x 10-2 (99% CL) • The exclusion area is shown for the plotDm2vs sin2(2q). At small Dm2 ICARUS strongly enhances the probability with respect to short baseline experiments. with (Dm2, sin2(2q)) = (0.11 eV2, 0.10)as many as 30events should have been seen. Neutrino Telescopes, 11-15 March 2013

  23. Result combined with the low energy excess 1:MiniBooNE best fit in the combined 3+1 model 1-5:excluded by present ICARUS result (=> excessive osc. P @ large L/En) 6:best value including ICARUS result 6-9:compatible with present ICARUS Neutrino Telescopes, 11-15 March 2013

  24. LSND anomaly surviving area allowed MiniBooNE allowed LSND 90% allowed LSND 99% limit of KARMEN present ICARUS exlusionarea ICARUS result strongly limits the window of possible parameters for LSND anomaly indicating a narrow region (Dm2, sin22q)= (0.5 eV2, 0.005)where there is an overall agreement(90% CL): •the present ICARUS limit • the limits of KARMEN •the positive signals of LSND and MiniBooNE Collaborations Neutrino Telescopes, 11-15 March 2013

  25. Conclusions • Successfuloperation of ICARUS T600 on CNGS beam. • LAr TPC allowsunambiguousidentification of individualneevents with high efficiency. • ICARUS result strongly limits the window of possible parameters for LSND anomaly indicating a narrow region: (Dm2, sin22q)= (0.5 eV2, 0.005) where there is an overall agreement(90%CL) between: • the present ICARUS limit • the limits of KARMEN • the positive signals of LSND and MiniBooNE • Definitive answer to sterile n search:ICARUS T600 + anew 150 t detectors exposed to new 2GeV n beam at CERN SPS at 1.6 km and 460 m baseline. Neutrino Telescopes, 11-15 March 2013

  26. Thankyou! Neutrino Telescopes, 11-15 March 2013

  27. ICARUS at CERN Far position:1600 m ICARUS-T600 detector + magnetic spectrometer New CERN SPS 2 GeV neutrino facility in North Area 100 GeV primary proton beam fast extracted from SPS in North Area: C-target station next toTCC2 + two magnetic horns, 100 m decay pipe, 15 m of Fe/graphite dump, followed by m stations. Interchangeable n andnfocussing. Near position:330m 150t LAr-TPC detector to be build + magnetic spectrometer Neutrino Telescopes, 11-15 March 2013

  28. ICARUS at CERN minimum ionizing • Clarify the surviving LSND/MiniBooNE(Dm2-sin22q) region • far: ICARUS-T600 + near: T150 at CERN SPS • shorter distances: 1600 m and 330 m from target • lower neutrino energies (~ 2 GeV) than in CNGS beam. proton recoil • increased event rate, reduced overall event multiplicity, enlarge the angular range improving substantially ne selection efficiency • In absence ofoscillations: nspectra at different distances equal • independent of specific experimental event signatures • without any MC comparisons Neutrino Telescopes, 11-15 March 2013

  29. ICARUS at CERN: mass and mixing angle • Dual method, unlike LNSD and MiniBooNE, determines both the mass difference and the value of the mixing angle. • Events rates shown both for [background] and [oscill.+background] at d=330 m and d=1600 m and the Dm2 = 0.4 eV2, sin2(2q) = 0.01 • For d=1.6 km, En < 5 GeV and 4.5 1019 pot (1 y) a ne oscillation signal of ≈1200 events is expected above 5000 backgr. events T150 near detector T600 far detector Neutrino Telescopes, 11-15 March 2013

  30. ICARUS at CERN: expected sensitivities e-appearance: 1 year μbeam (left) 2 year anti-μ beam (right) for 4.5 1019 pot/year,3% syst. uncertainty on n energy spectrum μ→e μ→e LSND allowed regionfully explored in both cases e→e e-disappearance: 1 year μ beam 1 year μ+ 2 years anti-μ beams (right) combined “anomalies”: from reactor ns, Gallex and Sage experiments. Neutrino Telescopes, 11-15 March 2013

  31. L/En nm ICARUS window Neutrino Telescopes, 11-15 March 2013

  32. Precision study, e.g.: nm CC Quasi-elastic interactions CNGS data Collection • proton: • visible part Ek = 121±24 MeV • inelastic interaction at: Ek = 45±9 MeV • init direction w.r.t. beam axis: • cos:(-0.601, -0.779, -0.179) ± 3o p m Induction2 • precision studypossiblethanks to: • particleidentification • energy, momentumreconstruction • vertex region analysis • QE: verycleanevents • single visibleparticleidentified as a stopping/interacting proton • events with high energy and higherparticlemultiplicity and reinteractions Neutrino Telescopes, 11-15 March 2013

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