Speaker
Ms
Cabot-Ann Christofferson
(South Dakota School of Mines of Technology)
Description
Locating neutrinoless double beta decay experiments deep underground mitigates backgrounds originating from cosmic rays. Of equal importance is constructing the inner shielding and detector components using ultra-low-background materials that contain the lowest levels of radio-contaminates to aid in the mitigation of backgrounds from natural sources. Because of the favorable thermal and electrical properties, ultrapure copper is an ideal material when levels of naturally occurring radioactive uranium and thorium, or troublesome cosmogenically induced radioisotopes such as Co-60, have been greatly reduced. Producing such copper is possible under stringently clean conditions within an underground electroforming facility. All copper comprising the inner shield and detector components in the MAJORANA DEMONSTRATOR experiment were electroformed at the 4850 level of the Sanford Underground Research Facility and the Pacific Northwest National Laboratory shallow underground facility. The material produced has exceeded the 10ksi tensile strength design criteria and the purity is better than the 0.3 µBq Th or U/kg Cu determined to be below the levels required for use in the DEMONSTRATOR.
Primary author
Ms
Cabot-Ann Christofferson
(South Dakota School of Mines of Technology)
