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Accelerator Neutrino Experiments Accelerator Neutrino Experiments And DEEP CORE Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Accelerator Long-Baseline Neutrino Physics Goals νe appearance • Test the ν to ν oscillation ⎛ν ⎞UUU⎛ ⎞⎛ν ⎞ μ x ⎜ e ⎟ ⎜ e1 e 2 e⎟ 3⎜ 1 ⎟ hypothesis ν UUU= ν 2 ⎜ μ ⎟ ⎜ μ1 μ 2 μ⎟ 3⎜ 2 ⎟ • Measure precisely |Δm 32| 2 ⎜ ⎟ ⎜ ⎟⎜ ⎟ and sin (2θ23) ⎝ντ ⎠UUU⎝ τ1 τ 2 τ ⎠ 3⎝ν 3 ⎠ • Search for νμ to νe ν disappearance oscillations μ • sensitive to θ13 • Determine the mass hierarchy 2 2 2 Δm 32 = m3 –m2 • Measure δCP Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics 2 MiniBooNE - A search for νe appearance at Δm2 ~ 1 eV2 LSND Best fit: sin2(2θ) = 0.003, Δm2 = 1.2 eV2 Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Observed no excess consistent with the LSND two- neutrino oscillation νμ Æ νe signal region low energy excess region 128.8 ± 43.4 excess events (3.0σ) No sign of excess in recent νμ Æ νe data Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Neutrino Beam (NuMI) • 120 GeV protons strike target Low 13 • 10 μs long pulse of 3x10 protons Med. every 2.2 seconds (275 kW) High • Two magnetic horns focus secondary π/K • decay of π/K produce neutrinos • Variable neutrino beam energy Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics 5 MINOS |Δm2| =(2.43±0.13) x 10-3 eV2 (68% C.L.) Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Far Detector Energy Spectrum • A blind analysis was performed: – all procedures for calculating background and signal were finalised before the Far detector data were looked at • Expected background: 27 ± 5(stat) ± 2(sys) • Observed events: 35 • A 1.5σ excess over background prediction Fit the data to the oscillation hypothesis, obtain the signal prediction for the best fit point Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Jeff Hartnell, La Thuile 2009 7 Allowed Region • A Feldman-Cousins method was used • Fit simply to the number of events from 1-8 GeV • Best fit and 90% C.L. limits are shown: • for both mass hierarchies Allowed region (Δm2>0) • at MINOS best fit value 2 2 for Δm 32 & sin (2θ23) • Results: Normal hierarchy (δCP=0): 2 sin (2θ13) < 0.29 (90% C.L.) Inverted hierarchy (δCP=0): 2 sin (2θ13) < 0.42 (90% C.L.) Workshop on “Low Energy” Scott Menary –York University Jeff Hartnell, La Thuile 2009 Neutrino Physics and Astrophysics 8 CERN Neutrinos to Gran Sasso 9 long base-line appearance experiment: • Produce muon neutrino beam at CERN • Measure tau neutrinos in Gran Sasso Experiments: OPERA (1200 ton), ICARUS (600 ton) CERN 4.5·1019 pot/year (200 days, nominal intensity) Gran Sasso 17 17 Æ 2.2·10 pot/day ~10 νμ 11 /day~10 νμ /day in detector Æ 3600 νμ interactions/year in OPERA (charged current interactions) 19 ~1ντ observed interaction with 2·10 pot Æ 2-3 ντ interactions detected/year in OPERA CNGS Run 2008: 1.78·1019 pot Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics E. Gschwendtner, AB/ATB BENE08, 2 Dec 2008 The Known and Unknown in Neutrino Physics The CP Violation Parameter Three Neutrino PMNS Mixing Matrix: From Long Baseline From Atmospheric Appearance and Long Baseline Measurements Disappearance From Reactor Measurements From Solar Neutrino Disappearance Measurements Measurements Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics In Vacuum the Oscillation Probability is: ● P(νμ→νe) = P1 + P2 + P3 + P4 2 2 2 2 – P1 = sin (θ23) sin (2θ13) sin (1.27 Δm13 L/E) 2 2 2 2 – P2 = cos (θ23) sin (2θ12) sin (1.27 Δm12 L/E) 2 – P3 = J sin(δ) sin(1.27 Δm13 L/E) 2 – P4 = J cos(δ) cos(1.27 Δm13 L/E) where J = cos(θ13) sin (2θ12) sin (2θ13) sin (2θ23) x 2 2 sin (1.27 Δm13 L/E) sin (1.27 Δm12 L/E) Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics MINOS MC Event Composition in 2 Detectors • Primary background from NC events, also • high-y νμ CC, beam νe, oscillated ντ at Far detector • Right plot: purple shows an appearance 2 signal at the Chooz limit (sin 2θ13=0.15) Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Jeff Hartnell, La Thuile 2009 12 ● In matter, P1 will be approximately multiplied by (1 ± 2E/ER) and P3 and P4 will be approximately multiplied by (1 ± E/ER), where the top sign is for neutrinos with normal mass hierarchy and antineutrinos with inverted mass hierarchy. ● Different baselines “pick out” different terms which helps to break some of the degeneracies. 22222 2 P = f (,sin 2θ13 ,δ ,sgn(Δm13 ),ΔΔm12,,sin2,sinm 13 θθ12 2 23 L,E) 3 unknowns, 3 parameters under control L,E + νμ /anti νμ To fight neutral-current background could use a narrow-band beam and a detector technology which does a good job of e VS π0 identification Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Canada The “Off-axis” Beam Pmax for L/E ~ 500 so for E ~ 2 GeV you want detector at L~1000 km - Canada Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Where to Put NOνA? “The Ash River site is the furthest available site from Fermilab along the NuMI beamline. This maximizes NOνA’s sensitivity to the mass ordering.” M. Goodman, NOW 2008 (Sept) Voyageurs National Park (shaded brown) Ash River V. Barger, P. Huber, D. Marfatia, W. Winter arXiv:hep-ph/0703029 Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics T2K – J-PARC to SuperK •30 GeV Protons first transported to J- PARC Hadron Experimental Hall in January of this year. •Were on track for first neutrinos this year. •Opposite situation to NOνA–here they have a detector but not a beam. •Much smaller matter effect than NOνA Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics 2 2 Main T2K Measurements: sin 2θ23, Δm 23 ` Phase 1: ` 5 years X 0.75 MW beam ` 5x1021 pot ` Measurement of mixing angles νμ disappearance • Use CC Quasi Elastic 2 sin 2θ23 Events – Can reconstruct Neutrino Energy. – Background from non- 2 Δm23 CCQE interactions. Eν (MeV) Workshop on “Low Energy” Scott Menary –York University Neutrino17 Physics and Astrophysics The narrow-band beam at first seemed ideal but the energy at which the oscillation maximum occurs can be quite dependent on the value of δcp. The Report of the US long baseline neutrino experiment study arXiv:0705.4396 recognized that there is a great deal of power in using a wide-band beam (the first two oscillation maxima in the same experiment) but you must have excellent e versus π0 recognition - you need a Liquid Argon TPC (LArTPC) Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Electrons versus π0's at 1.5 GeV in a Liquid Argon TPC Dot indicates hit- colour indicates collected charge X green=1 mip, red=2 mips plane cm zoom in X plane cm Y plane cm zoom in zoom in Y plane cm zoom in Multiple secondary tracks can Electrons- Single track (mip scale) starting from a single vertex be traced back to the same primary vertex Use both topology and dE/dx to identify interactions Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics The Future In the US, a wideband νμ beam from Fermilab to DUSEL (Homestake) Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Beta-Beam Far (ever?) Future H- linac 2.2 GeV, 4 MW Existing at CERN Accumulator EURISOL ring + bunch Proton DECAY compressor driver RING Magnetic capture Isol target B = 5T Target SPS Ionization & ion source L=6880 m Drift New RFQ cooling Linac Phase rotation PSB PS Linac → 2 GeV Recirculating Linacs 2 → 50 GeV Decay ring – 50 GeV T2KK ≈2000 m circumference ν beam to far detector ν beam to near detector Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics Conclusions • Long-baseline neutrino accelerator experiments will always have the advantage of control of the neutrino source • There are a number of upcoming experiments designed to measure/improve the limit on θ13 but, of course, one is constrained by a complete lack of knowledge of this angle. If it has a high value (near the Chooz limit) then “traditional” long-baseline experiments have a chance but if it is “small” then really only a Neutrino Factory has a chance of making useful measurements. Workshop on “Low Energy” Scott Menary –York University Neutrino Physics and Astrophysics.
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