Developing a 60 kg bubble chamber for dark matter detection

The COUPP collaboration is developing the technology of continuously sensitive bubble chambers in the pursuit of direct detection of galactic dark matter. We have built and operated a 2 kg device in an underground area at Fermilab. From that run we obtained competitive spin-dependent interaction dark matter limits. Currently we are building a 60 kg detector, which will eventually be situated deep underground. This paper describes the design of that detector and discusses the challenges associated with it.