1. Particle Physics Design Group Studies Big Liquid Argon Neutrino Detector Subgroup Particle Physics Design Group Studies: The BLAND Subgroup BLAND

2. The BLAND Group Patrick Owen – Resolution and Efficiency Laurie Hudson – General design and Charge readout Stewart Hawkley – Triggering and Event reconstruction Cheryl Shepherd and James Mugliston – Magnetics and Cryogenics Oliver Cartz and Jeanette Avon – Calibration and Background Dee Campbell-Jackson – Avalanche Photodiodes and Purification Particle Physics Design Group Studies: The BLAND Subgroup

3. Introduction General Setup and Material Choice Collection Plate Magnetisation Photomultipliers Electronics Calibration Background and Location Purification Triggering Simulations Sensitivity & Resolution Cost Summary Particle Physics Design Group Studies: The BLAND Subgroup

4. General Setup Particle Physics Design Group Studies: The BLAND Subgroup -Tank has cylindrical geometry - Gaseous argon at the top for bi- phase LEM that will used in charge readout. - Non-magnetic tank and dome. - Anti-coincidence shield - This will all be contained within a cryostat. (Liquid Nitrogen) - Magnet & a return yoke to provide a uniform B field.

5. Near Detector Exactly the same (except size) Cylindrical shape 6m diameter, 5m height Identical in functionality - Used for measuring cross sections and initial energy spectrum Particle Physics Design Group Studies: The BLAND Subgroup

6. Material Choice Particle Physics Design Group Studies: The BLAND Subgroup $0.6 kg -1 ≈ $10 million (for 1 detector) High density (1.4 gcm -3 ) and stability. ε r = 1.6 μ = 475 cm 2 V -1 s -1 High scintillation yield; 40,000 γ per MeV Background rejection of NC and junk CC interactions

7. Collection Plate Particle Physics Design Group Studies: The BLAND Subgroup

8. Far detector - magnetises ~ 17 kTonnes of liquid argon Solenoid produces a uniform field of 0.55 T Correction currents with a return yoke Total coil ~ 5.5 kTonnes Iron yoke ~ 16.1 kTonnes Magnet Cooling system Feasible power consumption of 19.2MW Magnet

9. Particle Physics Design Group Studies: The BLAND Subgroup BLAND magnet demonstration

10. Particle Physics Design Group Studies: The BLAND Subgroup Simulation result

11. Photomultipliers Avalanche photodiodes (APD) – Small size – Low dead time Low temperatures High B-field Gain 10 6 Particle Physics Design Group Studies: The BLAND Subgroup

12. Electronics Particle Physics Design Group Studies: The BLAND Subgroup Current collected is of order pC. Install pre-amps inside cryostat to reduce capacitance. Extended lifetime of electronics High signal: noise ratio 4 bytes per digitisation, 2.5MHz. Bandwidth distributed around PC farm. Pre-amplifier ADC Collection Plate Cryostat

13. Calibration Why calibrate? Initial – Signal Level-> Energy – Test beam – Cosmic ray muons (anti-coincidence shield) – Electronics Ongoing calibration – Constantly changing variables – Correction factors – Cosmic ray muons Particle Physics Design Group Studies: The BLAND Subgroup Before After

14. Background Projected direction Known energy range Location Expected background: – 10 -8 s -1 neutrinos – 1s -1 cosmic ray muons at 1km underground Particle Physics Design Group Studies: The BLAND Subgroup

15. Location Underground Low background radiation Few nuclear power plants High available energy Existing underground facilities Particle Physics Design Group Studies: The BLAND Subgroup

16. Average data rate ~45MB/s. Trigger above background pedestal. Scintillation light detected by PMTs used to trigger for 'interesting' events. Effectively segments detector, only reading out locally active regions. An anti-coincidence shield is used to reject background. Triggering

17. Purification of LAr Particle Physics Design Group Studies: The BLAND Subgroup Electron drift ~ 25m Minimisation of recombination Purity of <0.1ppb –Monitor contact materials –Hermetic system –Continual purification 100Watts

18. Purity Testing Particle Physics Design Group Studies: The BLAND Subgroup SchematicsSignals

19. Simulations Particle Physics Design Group Studies: The BLAND Subgroup

21. Charged current muon production Charged current electron production Incident neutrinos

22. Sensitivity Particle Physics Design Group Studies: The BLAND Subgroup The QECC cross section (red line) is found to be 7.5x10 -43 m 2 and 6x10 -43 m 2 for the far detector and middle detector respectively (Half these values for antineutrinos). http://www.fnal.gov/directorate/DirReviews/Neutrino_Wrkshp_files/Fleming.pdf

23. Sensitivity Particle Physics Design Group Studies: The BLAND Subgroup The average active thickness for the detector, t = 2d/π =14.1m The number density under the average pressure, n = 2.0x10 28 d =22m Again these values are halved for antineutrinos

24. Energy Resolution A 1GeV electron will ionise 1.45x10 7 atoms The contribution from quantum fluctuations is Another contribution is from the time resolution which is a systematic error. Noise and avalanche variation is expected to be negligible. Other effects such as electronics and dead zones. These values are best estimates. Particle Physics Design Group Studies: The BLAND Subgroup

25. Momentum Resolution Spatial resolution arises from diffusion and channel size Total spatial resolution is 6.7mm Momentum resolution: Radiation length calculated to be 5.6km – multiple scattering contribution is negligible. Heavily dependent on path length, L – not constant. Particle Physics Design Group Studies: The BLAND Subgroup

26. Average fractional momentum resolution is 1% and 3% for the middle and far detectors respectively (worse than energy resolution). Momentum Resolution

27. Cost Particle Physics Design Group Studies: The BLAND Subgroup EquipmentNumberCost ($) Liquid Argon2x17KT + small25 mil Magnet & Yoke224 mil PMs (1/m 2 )~4000120 k Liquid Nitrogen2x10 4 m 3 2 mil LEM Channels + E-field12x10 6 12 mil Underground factorn/a2 PC Farm110 mil Contingencyn/a80 mil Engineers & Scientists20048 mil (over 6 years) Total264 mil + running costs

28. Summary… Liquid Argon Time Projection Chamber LEM readout Uniform 0.55T B-field Triggering using APDs Calibration using test beams Underground Data Rate 45MB/sec Purity < 0.1ppb Great energy resolution, good momentum resolution Cost ~ $264 mil + running costs Particle Physics Design Group Studies: The BLAND Subgroup

29. References Neutrino Scattering in Liquid Argon TPC Detectors, Fleming. Radiation Detection and Measurement; 2nd ed, Knoll. Measurement of the muon decay spectrum with the ICARUS liquid Argon TPC, ICARUS Collaboration. Detectors for particle radiation, Kleinknecht. Calorimetry, Wigmans. Particle Physics Design Group Studies: The BLAND Subgroup

30. Questions? Particle Physics Design Group Studies: The BLAND Subgroup