1 by Giovanni Marsella, Università del Salento and INFN (for the NESSiE collaboration) NeSSiE and the quest for sterile neutrinos Neutrino Oscillation Workshop - Conca Specchiulla (Otranto, Lecce, Italy) September 7-14, 2014

Outline 2 The “sterile” issue at 1 eV mass scale The FNAL proposals The CERN neutrino platform: WA104-NESSiE

3 The NESSiE Collaboration Spectrometers at a neutrino beam. Extended studies: -SPSC-P-343, arXiv: SPSC-P347, arXiv: ESPP, arXiv: LOI CENF: -L. Stanco et al., AHEP 2013 (2013) ID , arXiv: v2 -FNAL-P-1057, arXiv: Make a conclusive experiment to clarify the  disappearance behavior at 1 eV scale, by using spectrometers to allow muon charge and momentum measurement Neutrino Experiment with SpectrometerS in Europe Neutrino Experiment with SpectrometerS in FERMILAB

4 The NESSiE Collaboration INFN and Physics Departments (Italy), Lebedev Institue (Russia). MSU (Russia), Boskovic Institute (Croatia), CERN. All these groups have long experience in Neutrino Physics and Hardware (Chorus, Macro, Nomad, Opera, T2K …)

5 The “sterile” issue From masses to flavours: U is the 3 × 3 Neutrino Mixing Matrix mixing given by 3 angles,  23,  12,  13 transition amplitudes driven by ∆m 2 solar = ∆m 2 21 ∆m 2 atm = |∆m 2 31 | ≈ |∆m 2 32 | The wonderful frame pinpointed for the 3 standard neutrinos, beautifully adjusted by the  13 measurement, left out some relevant questions: -Leptonic CP violation -Mass values -Dark Matter -Anomalies and discrepancies in several results

6 The “sterile” issue (cnt’d) The previous picture is working wonderfully. So it should stay whenever extensions are allowed ! Exploit 3+1 or even 3+2 oscillating models, by adding one or more “sterile” neutrinos Sterile neutrino: not weakly interacting neutrinos ( B. Pontecorvo, JETP, 53, 1717, 1967) APPEARANCE DISAPPEARANCE with for APPEARANCE for DISAPPEARANCE when and

7 The “sterile” issue (cnt’d)  Experimental hints for more than 3 standard neutrinos, at eV scale  Strong tension with any formal extension of 3x3 mixing matrix Reactor anomaly ~2.5σ Re-analysis of data on anti- neutrino flux from reactor short-baseline (L~ m) shows a small deficit of R=0.943 ±0.023 G.Mention et al, Phys.Rev.D83, (2011), A.Mueller et al. Phys.Rev.C 83, (2011). Gallex/SAGE anomaly ~3σ Deficit observed by Gallex in neutrinos coming from a 51 Cr and 37 Ar sources R = −0.08 C. Giunti and M. Laveder, Phys.Rev. C83, (2011), arXiv: Accelerator anomaly ~3.8σ Appearance of anti-ν e in a anti-ν μ beam (LSND). A.Aguilar et al. LSND Collaboration Phys.Rev.D (2001). Confirmed (?) by miniBooNE (which also sees appearance of ν e in a ν μ beam) A.Aguilar et al. (MiniBooNE Collaboration) Phys.Rev.Lett (2013) e disappearance e appearance ?? Where is  disappearance ??

8 Possible explanation: mixing of the active flavours with a sterile neutrino ∆m 2 ~ 1 eV 2 But there are STRONG tensions between e (appearance and disappearance) and  disappearance (by J. Kopp at Neutrino2014 and references therein) What is the community undergoing ? Many proposals and experiments to confirm the anomalies. Why not directly going to measure the  disappearance ? SK 2014 Mixing (AMPLITUDE) Mass scale (PHASE) MINOS(2014)

9 FNAL-P-1057 and arXiv: Submitted to FNAL-PAC: Prospects for the measurement of  disappearance at the FNAL-Booster The NESSiE Collaboration BOOSTER BEAM

10 Key-points of the proposal: 1.The muon-neutrino disappearance is mandatory - either in case of null result on electron-neutrino (the sterile possibility might still be there due to interference modes and data mis-interpretation) - or in case of positive result (to address the correct interpretation of sterile, see current tension between appearance/disappearance) 2.Standalone measurement of muon-neutrinos (fully compatible with upstream LAr, or, in case, a small active scintillator target may be foreseen at Near-site for NC/CC and absolute rate control) 3.Interplay between systematic and statistical errors: optimized configuration for Near and Far site 4.IDENTICAL near and far detector (the same iron slab will be cut in two pieces to be put corresponding in the Near and the Far) 5.No R&D/refurbishing/upgrade: robustness of the program (80% of re-used well proven detectors, straightforward extension; 100 kWatt needed for each site)

11 Careful study of the FNAL-Booster neutrino beam, based on previous knowledge from MiniBooNE, SciBooNE and data obtained by HARP and E910. -full simulation of the beam with GEANT4 and FLUKA (from proton to neutrinos) -detailed systematic error source analysis (use of Sanford-Wang parametrization) -Several configurations analyzed, on/off-axis including MicroBooNE site and different detector sizes A possibility Near: SciBooNE enclosure Far: NOvA surface building Far site Near site meters

12 Near-siteFar Near-off Far Near-size Far chosen configuration Near almost on axis Far on surface, Full “NESSiE” configuration

13 Near site Far site E neutrinos p muons ABSOLUTE nb. interactions in the FAR fiducial volume, 3 years data taking

MINOS (Neutrino 2014) 14 from here (now) to here (NESSiE) a full simulation and a careful treatment of 1% systematics error Sensitivity with strong cuts plus statistical error plus systematics only on p  reconstruction Three independent analyses, with different statistical approaches

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The CERN Neutrino Platform: WA104-NESSiE Proposed strategy A) The “conservative” approach Air Core Magnet spectrometer coupled to Iron Core Magnet spectrometer – Coupling to upstream LAr TPC B) The advanced solution (R&D) - Superconducting ACM spectrometer – Coupling to upstream LAr TPC -Magnetization of Large Volume LAr-TPC Precision measurement of muon momentum & charge in the 0.5 GeV - 10 GeV range - relevant to disentangle ν anomalies in ν / anti-ν channels - relevant in LBL exps to limit ν / anti-ν related systematics

WA104 -NESSiE R&D program First step- construction and operation of 13/39 ACM coils R&D on Tracking Detectors in Magnetic Field - Scintillator bars + SiPM in analog and digital readout - Other tracking devices (RPC in analog readout) Charged beam tests - charge and momentum measurement - Test on LAr-TPC –ACM matching Cold ACM in NbTi : design, simulation, demonstrator MgB2 Conductor: R&D actvity Synergy with LAr –TPC magnetization.

Design constrained by -Low power consumption -Low “budget” of material along the beam -Low cost -Large magnetized volume -Large acceptance The Air Core Magnet Optimized parameters Field Volume Depth 130 cm Magnetic Field ~ 0.1 T Aluminum Conductor 1 mm Tracking Detector Resolution y z x getting rid of multiple scattering at low energy

Assuming: Normal incidence Toroid width 130 cm Uniform magnetic field NbTi: proven successful technology – Operating at 4 K Exploring new materials as MgB 2 (operating at 20 K). Long term R&D required -cabled conductor development -coil winding technology -demonstration coils -qualification of coil operation 19 Cold ACM Bending Power Superconductor Materials: The choice Cryostat Superconducting Coil 1.5 m SC Air Core Magnet à la Atlas

Thank you ! 20

21 BACKUP

22 Resolutions: Momentum measured by range (ICM) up to 3.5 GeV, then ≈30% are provided (goal ≥ 250 MeV) Sensitivities from the actual NESSiE configurations (full simulation, with neutrino beam) Charge-ID measured by iron slabs (ICM: blue line)

23 absolute number of  CC interactions, seen by the Near detector at 110 m, either in the E or the p  variables, normalized to the expected luminosity in 3 years of data taking at FNAL–Booster, or 6.6 × 1020 p.o.t. (full simulation including RPC digitalization, muon momentum resolution 10%) DATA COLLECTION Number of events in 3 year (6.6 x pot) TriggerNEARFAR num. planes ≥ 25.1 x x 10 5 num. planes ≥ 34.1 x x 10 5 num. planes ≥ 52.7 x x 10 5

24 Schedule and Costs A bit aggressive, but reliable schedule based on successful OPERA experience Both Near and Far (new Electronics, new DAQ, 2 x coil number)