EXO Progress Update

Laurentian University

Jacques Farine

EXO Gas Option Simulation

First step: containment efficiencies

• Pressure and mass dependence

• Cylinder, take H=2R to minimize S/V

• Filled with 136Xe

• Cu walls

• 0 decay, Q = 2457.8 keV

• Differentiate e–//both crossing fid. vol.

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

2 / 0 differential c at edges

• Simulations for 1T 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=1m)

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 bothL+G Options

Material screening - radon emanation tests

• Continued program at SNOLAB• Sensitivity 10 220Rn/day, 20 222Rn/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 gasesN2 = Ar; Xe 23% lower

Radon Trap Development1) ESC on EXO-200• Augmented with:

– CO2 trap

– Rn source

– Water vapour trap

– Radon trap Mark I (LN2)

– Heat exchanger

– Recirculation pump

• Study Rn removal efficiency:– In misc. gases Air/N2/Ar > Xe

– Rn trap Mark I

Radon trap tests at ES-III (Stanford)

Mark I trap: 2” of SS wool at LN2, multiple passes efficiency too low (60% in 160 mbar N2) - sets scope

Radon Trap Development

2) At SNOLAB

• 222Rn and 210Rn 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

Reduction factor along dead legs• Known, irreducible source term• Want max. ingress rate at distance L• For 220/222Rn in N2/Ar/Xe

Theory - KTG in binary, dilute mixture, calculate D12

• 1D diffusion model with decay

Experimental check Diffusion length for 222Rn at 1 atm:

d = 2m in Ar; 1.2m in Xe

LGas at p,T