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

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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

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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

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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.

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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

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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. r = 1.6 = 475 cm 2 V -1 s -1 High scintillation yield; 40,000 per MeV Background rejection of NC and junk CC interactions

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Collection Plate Particle Physics Design Group Studies: The BLAND Subgroup

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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

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

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Particle Physics Design Group Studies: The BLAND Subgroup Simulation result

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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

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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

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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

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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

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

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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

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Purification of LAr Particle Physics Design Group Studies: The BLAND Subgroup Electron drift ~ 25m Minimisation of recombination Purity of