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Near Detector Report

Near Detector Report. International Scoping Study UC Irvine 21 August 2006 Paul Soler University of Glasgow. Contents. MINOS near to far ratio methods Beam simulation near detector Inverse muon decay Beam diagnostics Near Detector spectra Near Detector design R&D plans.

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Near Detector Report

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  1. Near Detector Report International Scoping Study UC Irvine 21 August 2006 Paul Soler University of Glasgow

  2. Contents • MINOS near to far ratio methods • Beam simulation near detector • Inverse muon decay • Beam diagnostics • Near Detector spectra • Near Detector design • R&D plans International Scoping Study UC Irvine, 21 August 2006

  3. 1. MINOS Near to Far Ratio Methods Prediction far detector spectrum from near detector (MINOS methods, Weber) • 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 UC Irvine, 21 August 2006 Not used in the fit

  4. 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 measured Near Detector distribution and extrapolates it using a BEAM Matrix to the Far Detector. International Scoping Study UC Irvine, 21 August 2006

  5. 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 UC Irvine, 21 August 2006

  6. 2. Beam Simulation Near Detector • Flux determination with near detector (Karadzhov, Tsenov) • Muon beam parameters : • polarization : 1, -1 and 0. • beam energies : 20, 30, 40 GeV. • energy distribution : Gaussian (σ = 80 MeV) • angular distribution : Gaussian (σ = 0.5x10-3) • Distribution in a plane perpendicular to the beam : Gaussian (σ = 5cm) International Scoping Study UC Irvine, 21 August 2006

  7. 2. Beam Simulation Near Detector • Muon decay matrix element For νμ For anti νe where x = 2Eν/mµ , Pµ is the polarization of the muon and θ is the angle between polarization vector and neutrino direction. • Distributions of points where νμ and anti νe cross a plane situated at 500 m from the end of the straight section and perpendicular to the beam axis for polarization 1 and -1 . International Scoping Study UC Irvine, 21 August 2006

  8. 2. Beam Simulation Near Detector • Number of neutrinos per cm2 in the same plane for 100000 muon decays simulated Muon energy 40 GeV. International Scoping Study UC Irvine, 21 August 2006

  9. 2. Beam Simulation Near Detector • Number of neutrinos per cm2 in the same plane for 100000 muon decays simulated Muon energy 40 GeV. International Scoping Study UC Irvine, 21 August 2006

  10. 2. Beam Simulation Near Detector • Number of neutrinos per cm2 in the same plane for 100000 muon decays simulated Muon energy 40 GeV. International Scoping Study UC Irvine, 21 August 2006

  11. 3. Inverse muon decay • Inverse muon decay: scattering off electrons in the near detector(Karadzhov, Tsenov) • Cross sections (in C.M. system): International Scoping Study UC Irvine, 21 August 2006

  12. 3. Inverse muon decay • Energy spectra for νμ(green) and anti νe(blue).Muon energy 40 GeV. Cylinder radius 1 m, thickness 30 cm 500 m distance Threshold International Scoping Study UC Irvine, 21 August 2006

  13. 3. Inverse muon decay • Energy spectra for νμ(green) and anti νe(blue). Muon energy 40 GeV. International Scoping Study UC Irvine, 21 August 2006

  14. 3. Inverse muon decay • Polar angle for νμ(green) and anti νe(blue). Muon energy 20 GeV. International Scoping Study UC Irvine, 21 August 2006

  15. 3. Inverse muon decay • Total number of muons per year (1021 muon decays per year) produced in a cylindrical detector with radius 1 m, thickness 30 cm and density 1.032 g/cm3(scintillator, total mass ~1 ton), • 400m long straight section is used for these simulations. E = 40GeV , P = 1 6.87x105 5.81x105 1.92x109 E = 40GeV , P = -1 1.67x106 6.97x104 2.81x109 E = 30GeV , P = 1 2.02x105 1.97x105 1.32x109 E = 30GeV , P = -1 5.89x105 1.60x104 1.91x109 E = 20GeV , P = 1 1.83x104 1.14x104 8.07x108 E = 20GeV , P = -1 7.83x104 7.76x102 1.14x109 Muon energy 20 GeV. International Scoping Study UC Irvine, 21 August 2006

  16. shielding the charm and DIS detector Cherenkov Polarimeter the leptonic detector BCT storage ring 4. 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 UC Irvine, 21 August 2006

  17. 4. Beam Diagnostics • Muon polarization: Build prototype of polarimeter Fourier transform of muon energy spectrum amplitude=> polarization frequency => energy decay => energy spread. International Scoping Study UC Irvine, 21 August 2006

  18. shielding the charm and DIS detector Cherenkov Polarimeter the leptonic detector d storage ring 5. Near Detector Beam Spectra • 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 UC Irvine, 21 August 2006

  19. 34.1 GeV 21.6 GeV 17.8 GeV 18.5GeV 29.2 GeV 15.3 GeV 5. Near Detector Beam Spectra 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 decay length not taken into account) Anti-nm ne International Scoping Study UC Irvine, 21 August 2006

  20. 5. Near Detector Event Spectra 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 UC Irvine, 21 August 2006

  21. 38.1 GeV 35.8 GeV 30.0 GeV 33.3 GeV 5. Near Detector Event Spectra Compared to far detector: d=2500 km, r=20 m Event rates Flux Anti-nm Near Detector at 1 km has similar spectra to Far Detector ne International Scoping Study UC Irvine, 21 August 2006

  22. 6. 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 UC Irvine, 21 August 2006

  23. EM calorimeter Hadronic Calorimeter Muon chambers 6. Near Detector Design Possible design near detector around UA1/NOMAD/T2K magnet International Scoping Study UC Irvine, 21 August 2006

  24. 6. Near Detector Design • Vertex detector • Identification of charm by impact parameter signature • Demonstration of charm measurement with silicon detector: NOMAD-STAR • Impact parameter resolution • sx~33 mm • Pull: • s~1.02 International Scoping Study UC Irvine, 21 August 2006

  25. 6. Near Detector Design • 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 with 2D space points (ie. Pixels) and more measurement 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 (~0.4 X0) • Fully pixelated detector with pixel size: 50 mm x 400 mm 200 M pixels • Double sided silicon strips, long ladders: 50 cm x 50 mm  360 k pixels International Scoping Study UC Irvine, 21 August 2006

  26. 7. 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 UC Irvine, 21 August 2006

  27. 7. 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 UC Irvine, 21 August 2006

  28. 40k/yr 80k/yr 120k/yr 40k/yr 80k/yr 120k/yr 7. Near Detector R&D Plans • Request plan : International Scoping Study UC Irvine, 21 August 2006

  29. 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 UC Irvine, 21 August 2006

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