The Future of Astrophysical Neutrino Measurements

November 17, 2014
A microfabricated array of TES bolometers

Figure 8:An example of a microfabricated array of TES bolometers, an 88 pixel, dual polarization TES bolometer array made at NIST for the SPTpol experiment. TES detectors are micro-machined from thin films deposited on silicon wafer substrates which means TES-based devices are fundamentally fabricated as arrays. [from K.N. Abazajian, et al., "Neutrino physics from the cosmic microwave background and large scale structure," Astroparticle Physics, v. 63.]

A new paper published in Astroparticle Physics by an international group of physicists and astronomers, including Harvard's Prof. John Kovac, reports on the status and prospects of the quantification of neutrino properties through the cosmological neutrino background for the Cosmic Frontier of the Division of Particles and Fields Community Summer Study long-term planning exercise. Experiments planned and underway are prepared to study the cosmological neutrino background in detail via its influence on distance-redshift relations and the growth of structure. The program for the next decade described in this document, including upcoming spectroscopic galaxy surveys eBOSS and DESI and a new Stage-IV CMB polarization experiment CMB-S4, will achieve σ (σmν)(σmν) = 16 meV and σ (Neff) = 0.020. Such a mass measurement will produce a high significance detection of non-zero σmνσmν, whose lower bound derived from atmospheric and solar neutrino oscillation data is about 58 meV. If neutrinos have a minimal normal mass hierarchy, this measurement will definitively rule out the inverted neutrino mass hierarchy, shedding light on one of the most puzzling aspects of the Standard Model of particle physics — the origin of mass. This precise a measurement of Neff will allow for high sensitivity to any light and dark degrees of freedom produced in the big bang and a precision test of the standard cosmological model prediction that Neff = 3.046.