BLAND Subgroup Particle Physics Study: Big Liquid Argon Neutrino Detector Design

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

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 -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. Particle Physics Design Group Studies: The BLAND Subgroup

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 • $0.6 kg-1 ≈ $10 million (for 1 detector) • High density (1.4 gcm-3) and stability. • εr = 1.6 • μ = 475 cm2V-1s-1 • High scintillation yield; 40,000 γ per MeV • Background rejection of NC and junk CC interactions Particle Physics Design Group Studies: The BLAND Subgroup

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

8. Magnet • Far detector - magnetises ~ 17 kTonnesof 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

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

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

11. Photomultipliers • Avalanche photodiodes (APD) • Small size • Low dead time • Low temperatures • High B-field • Gain 106 Particle Physics Design Group Studies: The BLAND Subgroup

12. Electronics • 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. Collection Plate Pre-amplifier ADC Cryostat Particle Physics Design Group Studies: The BLAND Subgroup

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 Before After Particle Physics Design Group Studies: The BLAND Subgroup

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. Triggering • 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. Particle Physics Design Group Studies: The BLAND Subgroup

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

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

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

20. Particle Physics Design Group Studies: The BLAND Subgroup

21. Charged current electron production Incident neutrinos Charged current muon production Particle Physics Design Group Studies: The BLAND Subgroup

22. Sensitivity http://www.fnal.gov/directorate/DirReviews/Neutrino_Wrkshp_files/Fleming.pdf The QECC cross section (red line) is found to be 7.5x10-43 m2 and 6x10-43 m2 for the far detector and middle detector respectively (Half these values for antineutrinos). Particle Physics Design Group Studies: The BLAND Subgroup

23. Sensitivity The average active thickness for the detector, t = 2d/π =14.1m The number density under the average pressure, n = 2.0x1028 d =22m Again these values are halved for antineutrinos Particle Physics Design Group Studies: The BLAND Subgroup

24. Energy Resolution • A 1GeV electron will ionise 1.45x107 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. Momentum Resolution Average fractional momentum resolution is 1% and 3% for the middle and far detectors respectively (worse than energy resolution). Particle Physics Design Group Studies: The BLAND Subgroup

27. Cost Particle Physics Design Group Studies: The BLAND Subgroup

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