Measurement of the Electron-Neutrino Charged-Current Cross Sections on \({}^{127}\)I with the COHERENT NaI\(\nu\)E detector

Using an 185-kg NaI[Tl] array, COHERENT has measured the inclusive electron-neutrino charged-current cross section on \({}^{127}\)I with pion decay-at-rest neutrinos produced by the Spallation Neutron Source at Oak Ridge National Laboratory. Iodine is one the heaviest targets for which low-energy (\(\leq\) 50 MeV) inelastic neutrino-nucleus processes have been measured, and this is the first measurement of its inclusive cross section. After a five-year detector exposure, COHERENT reports a flux-averaged cross section for electron neutrinos of \(9.2^{+2.1}_{-1.8} \times 10^{-40}\) cm\(^2\). This corresponds to a value that is \(\sim\)41% lower than predicted using the MARLEY event generator with a measured Gamow-Teller strength distribution. In addition, the observed visible spectrum from charged-current scattering on \(^{127}\)I has been measured between 10 and 55 MeV, and the exclusive zero-neutron and one-or-more-neutron emission cross sections are measured to be \(5.2^{+3.4}_{-3.1} \times 10^{-40}\) and \(2.2^{+3.5}_{-2.2} \times 10^{-40}\) cm\(^2\), respectively.