Deployment of COHERENT multi-tonne NaI[Tl] detector (NaIvETe)

The COHERENT collaboration operates a multi-target suite of low-threshold neutrino detectors at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory. These detectors are uniquely equipped to observe the dominant low-energy (Ev ∼ tens of MeV) interaction of coherent elastic neutrino-nucleus scattering (CEvNS). CEvNS is a neutral-current process whose only experimental signal is scintillation from nuclear recoils of mere tens of keV. One characteristic of the Standard Model cross section for CEvNS is its dependence on the number of neutrons squared. In order to probe this N2 scaling with the relatively light 23Na nucleus, COHERENT will deploy a modular, tonne-scale detector with scintillating NaI[Tl] crystals, successor to the 185-kg NaIvE detector that has collected data since 2016. This next generation design not only increases target mass an order of magnitude, but its dual-gain base design also facilitates measurement of CEvNS events on 23Na and CC events on both target nuclei. Each of the five modules will contain 63 of the 7.7-kg crystals, a total mass of over 2.4 T. The construction of the NaI Neutrino Experiment TonnE-scale (NaIvETe) is underway with deployment planned in 2022.