Uncertainty is hanging over the future of a key particle physics experiment. The facility, a detector built for studying neutrinos, is housed deep below the New Mexico desert alongside the United States' only deep geological repository for nuclear waste. But researchers have not had access to the underground site since February, when an accident at the repository released radioactivity, and so they have been forced to mothball the experiment.

The Enriched Xenon Observatory-200 (EXO-200) was installed in 2007 at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, a repository 655 metres underground dug out of a salt bed. By the time of the accident, researchers working around the clock had accumulated two years of data; the findings appear in Nature today1.

The accident could not have happened at a worse time, says Giorgio Gratta, a physicist at Stanford University in California, and EXO-200's principal investigator. The detector was in the middle of an upgrade to improve its sensitivity; it was intended to run for a further two to three years, but that plan is now in question, he says. "The present situation at WIPP is very bad."

EXO-200 is one of a handful of experiments worldwide trying to resolve the quandary of whether neutrinos are their own anti-particles by looking for an elusive phenomenon known as neutrinoless double β decay.

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http://www.nature.com/news/radioacti...-study-1.15360