Underground elves at work in Majorana
Sanford lab photographer Matt Kapust recently spent a day with researchers constructing the Majorana Demonstrator experiment in the Davis Campus on the 4,850-foot level.
All Majorana wants for Christmas is a super-clean, radiation-free environment. That’s why strings of germanium detectors (not popcorn) are being assembled in a clean room, inside nitrogen-filled glove boxes. Critical parts of the experiment are being machined underground, in the world’s deepest clean-room machine shop, from ultra-pure copper that was electroformed on the 4850 Level to protect it from cosmic radiation.
Majorana began electroforming copper in 2011. Principal Investigator John Wilkerson of the University of North Carolina reported last week that more than half the ultra-pure copper needed for the experiment has been electroformed—enough to build the first of two cryostats that will hold hockey-puck sized germanium detectors made of a very high concentration of the isotope 76Ge.
Strings of “detector units” are being assembled and tested in seven special aluminum “string-test cryostats.” (To work properly, germanium detectors must be cooled to minus 321 degrees F.) The best Christmas present of all for members of the Majorana collaboration will be a detector quiet enough and cold enough to detect neutrinoless double-beta decay.