1. Radon Reduced Air and SNOLAB Aksel Hallin Queen’s University August, 2006

2. Radon is a major issue for low background experiments SNO Acrylic vessel and NCD’s Kamland Scintillator Borexino purification system SNO Cover gas Majorana, DEAP internal parts Average air in Canada 20 Bq/m 3 ; u/g 130 Bq/m 3 More serious problem as detectors get bigger

3. There is a significant effort in the community (See LRT proceedings and theses)

4. Radon daughters are electrically charged,and drift in electrical fields. They plate out on various surfaces. Also have physical and chemical adsorbtion of radon and its daughters. (See Michael Leung’s thesis)

5. Four aspects of radon Monitoring Radon reduced environments Desorption of daughters into detector volumes Cleaning surfaces

6. Monitoring Techniques typically involve concentrating radon into an active volume cryogenically or using electrostatics to concentrate the daughters and then counting alphas. Technology is well developed

7. Radon reduced environments SNO covergas system SNO water system Highest purity, low flow Limited by radon ingress Excludes personnel

8. Andrea Pocar, PhD Thesis, Princeton, 2003

9. Radon Clean Laboratory Concept Radon scrubber HEPA Lab Equipment 20 Bq/m 3 9.4x10 6 222 Rn/m 3 30 m 3 /min (100 cfm) People/ processes.0002 Bq/m 3 94 222 Rn/m 3 8460 222 Rn total Class 1000 Clean Room?.00002 Bq/m 3 9.4 222 Rn/m 3.02 Bq/m 3 9,400 222 Rn/m 3 2 Bq/m 3 940,000 222 Rn/m 3 3m x 10m x 10m 90 m 3 room 140 m 2 area emanation 23 Rn/min If walls 10 Rn/m 2 hr Air Lock #1 Air Lock #2 3 m 3 /min 80 Rn/min 48 Rn/min Leaks/diffusion 23 Rn/min 28 Rn/min Tolerable Rn load = Rn scrubber flow rate times Acceptable Rn concentration = 3 m 3 /min x 94 Rn/m 3 = 282 Rn/min Electrostatic deposition plates Chemical Baths? Lights Cooler Radon scrubber (1 cfm) K. McFarlane May 16, 2006 Baffle 9,400 222 Rn in lungs 125,000 222 Rn dissolved o o Continuous radon monitoring

10. Cleaning contaminated acrylic Cleaning quartz and other materials discussed in Michael Leung’s thesis