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The MINOS Detectors

The MINOS Detectors. Outline The MINOS Experiment Detector Technology Far, Near and Calibration Detector Detector Performance Summary. Chris Smith California Institute of Technology EPS Conference 2003. Far. Near. The MINOS Experiment.

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The MINOS Detectors

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  1. The MINOS Detectors Outline • The MINOS Experiment • Detector Technology • Far, Near and Calibration Detector • Detector Performance • Summary Chris Smith California Institute of Technology EPS Conference 2003

  2. Far Near The MINOS Experiment • Two Detector, long baseline, neutrino oscillation experiment: • NuMI beam (Neutrinos at theMain Injector) • Near Detector - on site at Fermilab • Far Detector – 730km away in Soudan mine, Minnesota • Calibration Detector – in a series of test-beams at CERN • Oscillations lead to differences in Near-Far event rates, energy spectra • Confirm Super-K result • Measure parameters to 10% Chris Smith , Caltech

  3. Detector Technology • Iron/Scintillator tracking calorimeters • 4.1 x 1cm scintillator strips, up to 8m long • Extruded polystyrene (co-extruded TiO2 coating) • PPO (1%), POPOP (0.03%) fluors • Readout via wavelength shifting fibres • Kuraray 1.2mm fibre (Y-11 fluor, 175 ppm) • Hamamatsu Multi-anode PMTs • Alternate planes rotated by  90o for 3D hits • Near and Far detectors magnetised Chris Smith , Caltech

  4. u v Far, Near and Calibration Detector • Detectors are designed to be as similar as possible • Far: Large octagon, 5400 tons • Near: Squashed octagon, 980 tons • Calibration: Small section, 12 tons Chris Smith , Caltech

  5. Near Detector - FNAL • 241 planes in 4 sections: • Veto • Target • Hadron Shower • Muon Spectrometer • Planes already constructed at FNAL • Beneficial occupancy in cavern from Dec 2003 • Installation ~ 12 months Chris Smith , Caltech

  6. Far Detector – Soudan • 2 supermodules, 484 planes • Plane installation completed June • 2nd Coil installed July • Cosmic ray veto shield • Unmanned running expected August • Already taking CR and atmos n data Chris Smith , Caltech

  7. Calibration Strategy • MINOS designed for 2% relative (detector-detector) and 5% absolute energy calibration • Light Injection System • Electronics/PMT non-linearity • PMT gain shift • Cosmic ray muons • Strip-to-strip normalisation • Calibration Detector (CalDet) • Characterise muon, electron and hadron responses • Understand event topologies • Test calibration procedures • 1 month running at FarDet  1 hour at CalDet Chris Smith , Caltech

  8. T11 3.6 GeV/c T7 10 GeV/c 1m 24 strips Scintillator x 60 (3.7 m) 1m Steel 5.9 cm CalDet – CERN • 1x1m cut-out section of larger MINOS detectors • 60 planes x 24 strips for (x,y,z) • Double-ended read-out • Not magnetised • CalDet exposed to T7 and T11 beams at CERN PS in summer 2001, 2002 • Provides e, m, p, p from 0.2 – 10 GeV Chris Smith , Caltech

  9. Event Topologies at CalDet • Particle ID using TOF and Cerenkov detectors. • 2 GeV topologies (single view): (Without Single PEs) Electron Pion Muon Proton Strip Plane Chris Smith , Caltech

  10. MC expectation Particle Response and Resolution • Preliminary results from CalDet agree well with predictions Chris Smith , Caltech

  11. Timing Resolution at the Far Detector Time Residuals for CR Muons • Resolution determined by decay time of Y-11 fluor in WLS fibre ~8 ns • Resolution measurement using down-going muons at Far Detector ~2.6 ns/plane • Expect ~2.5 ns based on photoelectron statistics for muons • Direction of muons can be determined with ~10 planes for contained vertex events • To distinguish up and down through-going muons need ~20 planes  ~ 2.6 ns Time (ns) Chris Smith , Caltech

  12. Map of scintillator strip (Far Detector) Fit to a muon energy spectrum Light Output • Factors affecting light at phototube include • Scintillator light output • Path-length in strip • Attenuation in WLS fibres • Connector efficiency • Apply corrections to infer response for perpendicular plane crossing (through 1cm scintillator) • Observe ~8-10 PEs/strip for cosmic ray muons at surface Chris Smith , Caltech

  13. Strip vs Plane Strip vs Plane U view V view Y vs X Candidate Neutrino Events at FarDet • Contained vertex atmospheric neutrino event? • NO! • CR muons entering between planes mimic atmospheric nevents • MINOS uses a double layer of scintillator to give  95% efficiency and to prevent gaps y x z Chris Smith , Caltech

  14. Time vs Y Time vs Z Y vs Z Y vs X Strip vs Plane Candidate Neutrino Events at FarDet y • Up-going muons produced by n interactions in Earth’s crust x z • Example event: m+ p = 5.4GeV/c • Expect ~450 up-going events in 5 year exposure of MINOS • B field allows m charge to be measured up to ~100 GeV Chris Smith , Caltech

  15. Summary • Far Detector construction completed on schedule • Very successful installation • CR and atmospheric neutrino data regularly being taken • Data analysis underway • Near Detector preparations underway • Planes assembled on surface ready for installation • Beneficial occupancy in cavern from December ‘03 • CalDet data-taking and analysis has produced preliminary results • Good agreement with predictions • Test-beam run this summer will be used to compare Near and Far detector electronics • MINOS is in good shape for NuMI beam in Dec ‘04! Chris Smith , Caltech

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