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NuMI Off-Axis Experiment. Alfons Weber University of Oxford & Rutherford Appleton Laboratory EPS2003, Aachen July 19, 2003. Content. What is the physics? Why off-axis? The beam The site What experiment to build? Scintillator Resistive plate chambers (Liquid Argon) Sensitivity.
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NuMI Off-Axis Experiment Alfons Weber University of Oxford & Rutherford Appleton Laboratory EPS2003, AachenJuly 19, 2003
Content • What is the physics? • Why off-axis? • The beam • The site • What experiment to build? • Scintillator • Resistive plate chambers • (Liquid Argon) • Sensitivity
What is the Physics? • Precision Experiment to determine • m23 • sin2223 • Look for sub-dominant oscillation mode • sin213 • Needed: low background • Low e beam contamination • Few wrong energy neutrinos
Why Off-Axis NC (visible energy), no rejection nm spectrum NuMI beam can produce 1-3 GeV intense beams with well defined energyin a cone around the nominal beam direction ne background ne (|Ue32| = 0.01)
Canada U.S. Soudan L. Superior Possible Sites • NuMI beam • 120 GeV protons from FNAL main injector • 3-15 GeV neutrinos • 3.8x1020 PoT / year • 0.5 MW beam power • Baselines • 700-950 km • Several sites with infrastructure • Road • Electricity • Network
Experimental Challenge • Small signal • huge # NC • Surface detector • No or light over-burden • cosmic • induced n • But:Duty factor 10-5
Detector Challenge • NC versus Electron CC separation • Fine grain • Low Z • Build affordable & massive detector • 50+ kton fiducial mass • >400k readout channels • Technologies: • Solid scintillator (MegaMINOS, but not Mton) • Liquid scintillator • Glass RPCs • (Liquid Argon TPC)
Solid/Liquid Sintillator • Alternating horizontal and vertical scintillator planes • Passive material: woodOriented Strand Board (density .6 - .7 g/cm3) • Sampling: 1/3 rad. length Fiducial fraction (1 m cut at all edges) 80% readout 15 m 180 m readout readout 9.4 tons 6 = 1 plane 5300 = detector 48 ft 15 m 15 m 885 planes = detector 8 in Scintillator modules 4 ft 8 ft 8 ft
MINOS WLS Fiber Relative Light Yield Length in cm Scintillator and WLS Fibre • Scintillator Length 15 m • Looped fibre readout • Scintillator Material • Solid • MINOS like co-extruded (3.8x1 cm2) • Liquid • Bicron 517 L (3.8x2.9 cm2) • WLS Fiber • Kuraray (0.7 mm ø) • Photodetector • APD • PMT: M64 400,000 m2 ( 16 x MINOS) ( 2 x MINOS) 680,000 channels ( 30 x MINOS)
Glass RPCs / LSTs • Used successfully • Belle: 4 years operation • Virginia Tech: 5 years testing Wood/plastic absorber
Signal & BG Events typical signal event BG event Fuzzy track = e- Clean track = muon 2 tracks = π0
Phase I (2008-2014) 4x1020 PoT / year 50 kton detector (fiducial) 1.5 years neutrinos 5 years anti-neutrinos Phase II (2014-2020) A factor of 25 more:PoT x detector mass 1.5 years neutrinos 5 years anti-neutrinos Physics Reach (I)
Physics Reach (II) • Some Math: • need more than one experiment to determine oscillation parameters P (nm ne) = P1 + P2 + P3 + P4 A. Cervera et al., Nuclear Physics B 579 (2000) 17 – 55, expansion to second order in
Physics Reach (III) • Measurement is oscillation probability • Depends simultaneously on: • Mass hierarchy • CP phase • Mixing angles Typical Errors
Summary • The NuMI OA group is seriously trying to bring froward a credible & affordable proposal • Combination of • JPARC/SuperK and NuMI OA • neutrino and anti-neutrino running • might reveal neutrino mixing parameters • Masses & hierarchy • Angles • CP phase • For more information: http://www-off-axis.fnal.gov
Liquid Argon TPC • Excellent pattern recognition capabilities • High efficiency for electron identification • Excellent e/p0 rejection