The Majorana Demonstrator has an impenetrable shield made up of six layers of various materials designed to block out minute traces of radiation. Extra care needs to be taken with the last layer—12 inches of polyethylene, a combustible material that requires a defense-in-depth fire protection plan to mitigate fire hazards.
In football, a coach has to be pretty desperate to put in the second string. The Majorana Demonstrator does things a little differently. Its second string—or cryostat—likely is the best.
“Our experiment design includes a prototype, followed by two cryostats,” said Adam Bradley, a postdoc with Lawrence Berkeley National Laboratory who works on the Majorana Demonstrator project. “With each cryostat, we’ve learned what not to do or what to do better or how to be more efficient.”
In the movie “Shrek,” the title character tells Donkey, “Ogres are like onions!… They have layers.” Vince Guiseppe uses the same analogy to describe the Majorana Demonstrator shield.
Since 2011, Guiseppe, Assistant Professor of Physics at the University of South Carolina, has been overseeing the construction of Majorana’s six-layered shield. In September, they began work on the final, and most pivotal layer: the electroformed copper shield, or as Guiseppe calls it, “The innermost part of the onion.”