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The LAr TPC for the T2K 2 km station

The LAr TPC for the T2K 2 km station. A proposed 100 ton fine-grain detector for the 2 km station at T2K to complement the 1 kton water Cherenkov. CHIPP Workshop on Neutrino Physics Bern, 19./20. October 2006. A. Badertscher, ETH Zurich. Detector installation. Shock absorber.

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The LAr TPC for the T2K 2 km station

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  1. The LAr TPC for the T2K 2 km station A proposed 100 ton fine-grain detector for the 2 km station at T2K to complement the 1 kton water Cherenkov CHIPP Workshop on Neutrino Physics Bern, 19./20. October 2006 • A. Badertscher, ETH Zurich

  2. Detector installation Shock absorber

  3. Alternative method of charge readout avoiding use of long wires Charge readout electronics LEM readout in gas phase HV 4.5m Liquid Argon imaging volume Scintillation light readout H2O/CO2 inner target 4.5m Field shaping electrodes Cathode ≈7,2 m

  4. Underground cryogenic infrastructure A: Detector dewar B: LAr Purification C: Buffer D: Heat exchanger and expansion valve E: Argon pipes F: Shock absorbers G: Dedicated shaft (ventilation+piping) G E D B A C F

  5. Liquid argon recirculation circuit LAr Vent + compressor B: Liquid Purification Pressure-relief valve High p GAr Burst-disk Vent valve D: Heat exchanger and expansion valve C: Buffer A: Dewar Vacuum insulation + Double liquid Argon containment

  6. A schematic layout (III) A: Detector B: Compressor C: Argon Storage D: Ventilation E: Vaporizers A E C D B

  7. What the Liquid Argon TPC provides • Bubble-chamber-like event reconstruction capability • Tracking with unbiased imaging & reconstruction AND full-sampling calorimetry • Fully active, homogeneous and isotropic • Very good resolution (energy (calorimetry), angular (tracking)) • Broad energy range (from MeV … multi-GeV) with high event reconstruction efficiency • Low particle identification thresholds • Muon, pion, kaon, proton particle ID and separation (dE/dx vs range) • e/p0separation • µ/p±separation • Shallow depth conceivable • Possible to embed in magnetic field for charge discrimination Implementation conceivable at different mass scale (e.g. 100 ton …100 kton)

  8. Example: proton detection thresholds Protons En = 1 GeV (MC) Range>1 cm C-threshold

  9. Design of prototype dewar

  10. 50 ton prototype dewarW. Bachmann and M. Baer, ETH Zurich A prototype dewar with a total LAr mass of 54 tons was designed. It consists of two stainless steel cylinders with D-shaped end caps, reinforced with 4 rings and supported by 6 stands. 6 m 3.6 m

  11. 3D engineering: Thermal analysis: Finite element analysis:

  12. Parameters of the final dewar (proposal May 2005) Geometrical parameters of the cryostat Cryogenic parameters Total LAr mass: 315 t Total heat input: 500 W (300 W through the supports, 100 W through cylinder and 100 W through the cables), corresponds to 200 liter of LAr boil-off per day (approx. 10-3 of total LAr volume). With recirculation: Additional 400 liter per day.

  13. A note on inner target and nuclear effects The error on the nuclear correction when extrapolating from Ar to H2O will be highly reduced thanks to the inner target. The difference between LAr and Water is a correction of the order of 30% and for the events in the inner target we are dominated by the systematics on the reconstruction (about 10%?) rather than the statistics (about 3% after 1 year). This means that the error on the extrapolation is of the order of 3% (30% times 10%), smaller than the systematics in WC detector.

  14. Preliminary design study for the water tankW. Bachmann, D-Phys, ETH Zurich Stainless steel container: 6m x 6m (too high!), reinforced, consists of two spherical shells. wall thickness 6 mm Water to steel mass ratio ca. 2:1

  15. Summary • The LAr TPC would be an excellent FGD for the T2K 2 km station at T2K. • A prototype dewar has been designed and a strong detector R&D program is being pursued. • Safety issues to operate a 100 ton LAr TPC in the 2 km underground hall are being studied together with cryogenics center at KEK.

  16. Additional slides

  17. Contained particle ID neural network (II) Protons efficiency >99% Kaons mis-id as protons <1% Pions/muons << 1% Reconstructed mass by combining measured dE/dx and kinetic energy

  18. Examples of 0 background as seen in LAr misid. in WC

  19. e appearance analysis in 2km WC • The LAr can reproduce the electron appearance analysis done at 2km/SK Water Cerenkov detectors, in particular, independently for beam e CC and NC backgrounds • Control the MC prediction at every single step of the analysis. • Determination of the electron efficiency in WC • MC analysis in WC demonstrates that with similar analysis (e.g. different reconstruction functions) it is possible to obtain similar results in 2km and SK. What is the systematic error associated to this? What if there is no agreement between Data and MC @ 2km WC? • A cross check on the 2km MC can be done using a different detector (i.e. introducing different systematics) to perform the same analysis can cross-check MC at 2km. • The LAr detector can reproduce the cuts of the analysis and measure the different components of the BG separately. In this way the cut efficiencies and BG will be over-constrained and an overall consistency will be demonstrated.

  20. Neutrino energy resolution (full sim + automatic reconstruction) nQE

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