By Doug Beck
January 26, 2017
Over the past week, we have taken delivery of two precious shipments with materials from opposite ends of the periodic table. About 200 standard liters of helium-3, valued at something like $200k, arrived on loan from ORNL. It will be used for the nEDM dilution refrigerator and will enable us to reach temperatures of about 0.25 K above absolute zero with the relatively high cooling power of 75 mW. The 3He is used because when it evaporates from a mixture with ordinary helium, it cools the remaining liquid. We also received the first half of a shipment of about half a ton of tungsten powder for the next round of prototypes for the sPHENIX calorimeter. Tungsten, a dense metal, is used because it can stop particles, especially photons, in relatively short distances. The powder will be combined with scintillating fibers to construct the 96 elements of a single ‘module’ for the full detector. Both the dilution refrigerator and the calorimeter prototype will be built and tested at NPL in the coming few months.