PTOLEMY: Relic neutrino direct detection

Though their imprint upon the CMB and large-scale structure of the universe remains to this day, Big Bang relic neutrinos (the C𝜈B) have never been directly observed. This remains an outstanding test of the Standard Model in CDM cosmology and would provide the earliest picture of the universe at only one second after the Big Bang. PTOLEMY aims to make the first direct observation of the C𝜈B by resolving the 𝛽-decay endpoint of atomic tritium. The concept relies upon amassing a target of atomic tritium, developing RF-based trigger and tracking, an EM transverse drift filter, and a cryogenic micro-calorimeter - each of which present novel R&D challenges. A prototype will soon be based at Gran Sasso National Laboratory. Intermediate measurements will be made of the lowest neutrino mass ahead of C𝜈B physics runs set to begin in the 2030s.