UCLA High Energy & Astro-Particle (HEAP) Seminar “The Hunt for Majorana Neutrinos: A Cold-Hearted Approach” Presented by Thomas O’Donnell, UC Berkeley In the last decade the culmination of several impressive experiments has placed the phenomenon of neutrino flavor oscillation on a firm experimental footing and with it the existence of nonzero neutrino masses. Consequences of this discovery include the possibility of beyond-the-Standard-Model processes such as neutrinoless double-beta (0νββ) decay. This decay has a relatively unambiguous experimental signature and its discovery would demonstrate lepton number violation and establish that neutrinos are Majorana fermions. The latter property is a key ingredient in theories of leptogenesis which attempt to explain the matter-antimatter asymmetry in the Universe. Naturally, the potential fundamental impact has made searching for 0νββ decay a top priority in neutrino physics. The Cryogenic Underground Observatory for Rare Events (CUORE*) is addressing this search with an array of 988 TeO2 bolometers that must operate 10mK above absolute zero. With an active mass of ~750 kg, it will be by far the largest ultra-low-temperature bolometer array ever operated. I will describe CUORE, its unique bolometer array, and discuss what has been learned from a recently completed prototype experiment, CUORE-0. Our data demonstrate the bolometer performance will allow CUORE to achieve a half-life sensitivity of T1/2 = 9.5×1025 yr (90% C.L) and thus begin to probe the inverted hierarchy of neutrino masses. Finally I will describe a new initiative dubbed CUPID (CUORE Upgrade with Particle Identification) which aims to improve the sensitivity of the CUORE technique to realize a next generation experiment capable of fully probing the inverted hierarchy. (*Italian for Heart) Location: PAB 4-330 Date: Thursday, March 17th, 2016 Time: 12:30pm Refreshments at 12:15pm