EXO Progress Update Laurentian University Jacques Farine EXO

EXO Progress Update Laurentian University Jacques Farine

EXO Gas Option Simulation First step: containment efficiencies • Pressure and mass dependence • Cylinder, take H=2 R to minimize S/V • Filled with 136 Xe • Cu walls • 0 decay, Q = 2457. 8 ke. V • Differentiate e–/ /both crossing fid. vol.

Uncertainties obtained from 20 independent simulations. + Points include detailed low energy processes, scintillation and E=1 k. V/cm (. . 30 x CPU cycles).

2 / 0 differential c at edges • Simulations for 1 T at 5 atm, equator • 10, 000 evts ea. • Contam. of 2 in 0 increases towards the edge • > Optimize fiduc. volume and/or vary fraction of contamination

0 events (1 T, square=1 m) 1 atm 20 atm > Investigate single/ discrimination

Next steps • Add chemical composition / drift / attenuation / absorption / attachment // light+charge readout • Add backgrounds as source of singles • Write code to detect Bragg peaks • For single/double separation, determine: – Contamination / sacrifice – Effect of Bremsstrahlung • Light collection options > E resolution

Studies related to both L+G Options

Material screening - radon emanation tests • • • Continued program at SNOLAB Sensitivity 10 220 Rn/day, 20 222 Rn/day Measure EXO-200 plumbing No substantial source Clean !

Characterize counters for Ar/Xe • Allow for: – Absolute emanation measurements – Diffusion studies in • Absolute cross-calibration between gases N 2 = Ar; Xe 23% lower

Radon Trap Development 1) ESC on EXO-200 • Augmented with: – – – CO 2 trap Rn source Water vapour trap Radon trap Mark I (LN 2) Heat exchanger Recirculation pump • Study Rn removal efficiency: – In misc. gases Air/N 2/Ar > Xe – Rn trap Mark I

Radon trap tests at ES-III (Stanford) Ø Mark I trap: 2” of SS wool at LN 2, multiple passes Ø efficiency too low (60% in 160 mbar N 2) - sets scope

Radon Trap Development 2) At SNOLAB • • 222 Rn and 210 Rn sources development Radon extractor board as trap testbed Refrigerator purchased Cold head integration underway Xenon purchased Xe plumbing assembly initiated (w/ RCV vessels) ESC integration underway

Xenon heat exchanger in construction

Diffusion of Rn in Xe Gas at p, T L Reduction factor along dead legs • Known, irreducible source term • Want max. ingress rate at distance L • For 220/222 Rn in N 2/Ar/Xe Theory - KTG in binary, dilute mixture, calculate D 12 • 1 D diffusion model with decay Experimental check Ø Diffusion length for 222 Rn at 1 atm: d = 2 m in Ar; 1. 2 m in Xe