Construction and Measurements of an Improved Vacuum-Swing-Adsorption Radon-Mitigation System

In order to reduce backgrounds from radon-daughter plate-out onto detector surfaces, an ultra-low-radon cleanroom is being commissioned at the South Dakota School of Mines and Technology. An improved vacuum-swing-adsorption radon mitigation system and cleanroom build upon a previous design implemented at Syracuse University that achieved radon levels of $\sim$0.2$$Bq$$m${}^{-3}$. This improved system will employ a better pump and larger carbon beds feeding a redesigned cleanroom with an internal HVAC unit and aged water for humidification. With the rebuilt (original) radon mitigation system, the new low-radon cleanroom has already achieved a $>$$$300$\times$ reduction from an input activity of $58.6\pm 0.7$$$Bq$$m${}^{-3}$ to a cleanroom activity of $0.13\pm 0.06$$$Bq$$m${}^{-3}$.