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Near Detector Report

Near Detector Report. International Scoping Study Detector Meeting 4 July 2006 Paul Soler University of Glasgow. Contents. MINOS near to far ratio methods Beam diagnostics Near Detector flux and event rates Near Detector design R&D plans. Ranged out in ECAL: momentum measurement.

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Near Detector Report

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  1. Near Detector Report International Scoping Study Detector Meeting 4 July 2006 Paul Soler University of Glasgow

  2. Contents • MINOS near to far ratio methods • Beam diagnostics • Near Detector flux and event rates • Near Detector design • R&D plans International Scoping Study CERN, 4 July 2006

  3. Ranged out in ECAL: momentum measurement SciBooNE Proposal hep-ex/0601022 1. MINOS Near to Far Ratio Methods Last ISS meeting: talk by Weber Prediction far detector spectrum from near detector Look for a deficit of νμ events at Far Detector SciBooNE is less peaked, and has a much smaller high-energy tail νμ spectrum Spectrum ratio Monte Carlo Monte Carlo Unoscillated Oscillated The Million $ Question: How to predict the Far Detector spectrum? International Scoping Study CERN, 4 July 2006

  4. to Far Detector p+ target (stiff) p+ qf qn (soft) Decay Pipe ND Ranged out in ECAL: momentum measurement 1. MINOS Near to Far Ratio Methods Three beams in MINOS • Problems • Hadron production uncertainties • Cross-section uncertainties • Near and Far Detector energy spectra are not identical • Both detectors cover different solid angles • Near Detector sees extended line source International Scoping Study CERN, 4 July 2006

  5. 1. MINOS Near to Far Ratio Methods • Four possible methods for beam flux extrapolation • NDFit method • 2D Grid method • Near to far ratio • Beam matrix method • NDFit: Reweighting hadronic distributions LE-10/185kA pME/200kA pHE/200kA Weights applied as a function of hadronic xF and pT. LE-10/Horns off LE-10 events International Scoping Study CERN, 4 July 2006 Not used in the fit

  6. Ranged out in ECAL: momentum measurement 1. MINOS Near to Far Ratio Methods • 2D Grid method • Bin data in reconstructed Eν & y • Fit weight as a function of true Eν & y • Near to far ratio • Look at differences between data and MC in Near Detector as a function of reconstructed Energy • Apply correction factor to each bin of re-constructed energy to Far Detector MC: c= ndata / nMC • Beam matrix • It uses the measure Near Detector distribution and extrapolates it using a BEAM Matrix to the Far Detector. International Scoping Study CERN, 4 July 2006

  7. 1. MINOS Near to Far Ratio Methods • Predictions for far detector do not give perfect agreement but well controlled. Predicted FD true spectrum from the Matrix Method 0.931020 POT Predicted spectrum • Four methods agree very well • Different systematics Nominal MC International Scoping Study CERN, 4 July 2006

  8. 2. Beam Diagnostics • Flux determination at a neutrino factory (Blondel) m polarization controls ne flux: m+ -X> nein forward direction Main parameters to MONITOR 1. Total number of muons circulating in the ring: BCT, near detector for purely leptonic processes 2. muon beam polarisation, polarimeter 3. muon beam energy and energy spread, race-track or triangle. NO BOW-TIE! +polarimeter 4. muon beam angle and angular divergence. straight section design +beam divergence monitors e.g. Cerenkov? 5. Theory of m decay, including radiative effects OK We believe that the neutrino flux can be monitored to 10-3 IF + design of accelerator foresees sufficient diagnostics. + quite a lot of work to do to design and simulate these diagnostics. International Scoping Study CERN, 4 July 2006

  9. shielding the charm and DIS detector Cherenkov Polarimeter the leptonic detector BCT storage ring 2. Beam Diagnostics • Beam Current Transformer (BCT) to be included at entrance of straight section: large diameter, with accuracy ~10-3. • Beam Cherenkov for divergence measurement? Could affect quality of beam. International Scoping Study CERN, 4 July 2006

  10. 2. Beam Diagnostics • Muon polarization: Build prototype of polarimeter Fourier transform of muon energy spectrum amplitude=> polarization frequency => energy decay => energy spread. International Scoping Study CERN, 4 July 2006

  11. shielding the charm and DIS detector Cherenkov Polarimeter the leptonic detector d storage ring 3. Near Detector Beam Flux • Near detector(s) are some distance (d~30-1000 m) from the end of straight section of the muon storage ring. • Muons decay at different points of straight section: near detector is sampling a different distribution of neutrinos to what is being seen by the far detector • Different far detector baselines: • 730 km, 20 m detector: q~30 mrad • 2500 km, 20 m detector: q~8 mrad • 7500 km: 20 m detector: q~3 mrad If decay straight is L=100m and d =30 m, at 8 mrad, lateral displacement of neutrinos is 0.25-1.0mm to subtend same angle. International Scoping Study CERN, 4 July 2006

  12. 3. Near Detector Beam Flux d=30 m, r=0.5 m d=130 m, r=0.5 m d=1km, r=0.5 m Flux Neutrino point source (muon decays not taken into account) Anti-nm 34.1 GeV 21.6 GeV 17.8 GeV ne 18.5GeV 29.2 GeV 15.3 GeV International Scoping Study CERN, 4 July 2006

  13. 3. Near Detector Event Rates d=30 m, r=0.5 m d=130 m, r=0.5 m d=1km, r=0.5 m Event rates Anti-nm 37.1 GeV 25.5 GeV 26.6 GeV ne 32.5 GeV 22.3 GeV 23.2 GeV International Scoping Study CERN, 4 July 2006

  14. 3. Near Detector Event Rates Compared to far detector: d=2500 km, r=20 m Flux 35.8 GeV Anti-nm 38.1 GeV ND at 1 km has similar spectra to FD Event rates 30.0 GeV 33.3 GeV ne International Scoping Study CERN, 4 July 2006

  15. 4. Near Detector Design • Overall design of a near detector • Vertex detector: Choice of Pixels; eg. Hybrid pixels, Monolithic Active Pixels (MAPS), DEPFET; or silicon strips. • Tracker: scintillating fibres, gaseous trackers (TPC, Drift chambers, …) • PID: • Calorimeter • Muon ID • Old UA1/NOMAD/T2K magnet offers a large magnetised volume with a well known dipole field up to 0.7 T. • Use NOMAD/T2K as basis for design International Scoping Study CERN, 4 July 2006

  16. VERTEX DETECTOR Dipole Magnet: 0.4-0.7 T Nuclear Target Electromagnetic Calorimeter PID Tracker (SciFi or TPC?) Hadronic Calorimeter 4. Near Detector Design International Scoping Study CERN, 4 July 2006

  17. 4. Near Detector Design • Vertex detector • Identification of charm by impact parameter signature • Charm has similar decay time to tau particle search used in NOMAD-STAR International Scoping Study CERN, 4 July 2006

  18. 4. Near Detector Design • Longest silicon microstrip detector ladders ever built: 72cm, 12 detectors, S/N=16:1 • Detectors: Hamamatsu FOXFET p+ on n, 33.5x59.9 mm2, 300 mm thick, 25 mm pitch, 50 mm readout • VA1 readout: 3 ms shaping • NOMAD-STAR International Scoping Study CERN, 4 July 2006

  19. 4. Near Detector Design • NOMAD-STAR • nm CC event • Secondary vertex • Primary vertex International Scoping Study CERN, 4 July 2006

  20. 4. Near Detector Design • Vertex resolution: sy = 19 mm • Impact parameter resolution: 33 mm • sx~33 mm • Pull: • s~1.02 • Double vertex resolution: 18 mm from Ks reconstruction • sz~280 mm • sx~18 mm Point resolution: 6 mm International Scoping Study CERN, 4 July 2006

  21. 4. Near Detector Design • Charm event selection: • Efficiency very low: 3.5% for D0, D+ and 12.7% for Ds+ detection because fiducial volume very small (72cmx36cmx15cm), only 5 layers and only one projection. • From 109 CC events/yr, about 3.1x106 charm events, but efficiencies can be improved. International Scoping Study CERN, 4 July 2006

  22. 4. Near Detector Design • Passive target can provide target mass, but affects vertex and tracking reconstruction efficiency due to scatters • Improve efficiency by having 2D space point measurement and more silicon planes. • For example: 52 kg mass can be provided by 18 layers of Si 500 mm thick, 50 x 50 cm2 (ie. 4.5 m2 Si) and 15 layers of B4C, 5 mm thick • Optimal design: fully pixelated detector (could benefit from Linear Collider developments in MAPS, DEPFET or Column Parallel CCD). With pixel size: 50 mm x 400 mm 200 M pixels, ~0.4 X0 • Could also use silicon “3D” detectors or double sided silicon strips (with long ladders of 50 cm x 50 mm  360 k pixels). • Will start R&D on MAPS and DEPFET at Glasgow from October this year – MI3 collaboration (MAPS) & Bonn University (DEPFET) International Scoping Study CERN, 4 July 2006

  23. 5. Near Detector R&D Plans • What needs to be measured: 1) Number of muons in ring (BCT) 2) Muon beam polarisation (polarimeter) 3) Muon beam angle and angular divergence (Cherenkov, other?) 4) Neutrino flux and energy spectrum (Near Detector) 5) Neutrino cross-sections (Near Detector) 6) Backgrounds to oscillations signal (charm background, pion backgrounds, ….), dependent on far detector technology and energy. (Near Detector) 7) Other near detector physics: PDF, electroweak measurements, …. International Scoping Study CERN, 4 July 2006

  24. 5. Near Detector R&D Plans • R&D programme • Vertex detector options: hybrid pixels, monolithic pixels (ie. CCD, Monolithic Active Pixels MAPS or DEPFET) or strips. Synergy with other fields such as Linear Collider Flavour Identification (LCFI) collaboration. • Tracking: gas TPC (is it fast enough?), scintillation tracker (same composition as far detector), drift chambers?, cathode strips?, liquid argon (if far detector is LAr), … • Particle identification: dE/dx, Cherenkov devices such as Babar DIRC?, Transition Radiation Tracker? • Calorimetry: lead glass, CsI crystals?, sampling calorimeter? • Magnet: UA1/NOMAD/T2K magnet?, dipole or other geometry? • Collaboration with theorists to determine physics measurements to be carried out in near detector and to minimise systematic errors in cross-sections, etc. International Scoping Study CERN, 4 July 2006

  25. 40k/yr 80k/yr 120k/yr 40k/yr 80k/yr 120k/yr 5. Near Detector R&D Plans • Request plan : International Scoping Study CERN, 4 July 2006

  26. Conclusions • There is important synergy between existing (or planned) experiments such as MINOS and T2K and the technology for future near detectors. Cross-sections and fluxes remain an issue. Learning the techniques that these experiments are adopting helps to formalise the problem that we will face at a neutrino factory. • A near detector at a neutrino factory needs to measure flux and cross-sections with unprecedented accuracy. Beam diagnostic devices need to be prototyped • It is worth noting that the beams measured by a near detector if it is close to straight sections (<100m) are quite different from far detector. However, at 1 km, beams start to look very similar. • We should start having some idea of what a near detector should look like. One proposal is to use the old UA1 magnet (like in NOMAD and T2K) once more. • The near detector should have a vertex detector, tracking planes, particle identification, calorimetry and muon identification. The dipole filed between 0.4-0.7 T can provide good muon momentum resolution. • R&D plans are not very well defined at the moment International Scoping Study CERN, 4 July 2006

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