  The Coherent Neutrino-Nucleus Interaction Experiment (CONNIE) is taking data
at the Angra 2 nuclear reactor with the aim of detecting the coherent elastic
scattering of reactor antineutrinos with silicon nuclei using charge-coupled
devices (CCDs). In 2019 the experiment operated with a hardware binning applied
to the readout stage, leading to lower levels of readout noise and improving
the detection threshold down to 50 eV. The results of the analysis of 2019 data
are reported here, corresponding to the detector array of 8 CCDs with a
fiducial mass of 36.2 g and a total exposure of 2.2 kg-days. The difference
between the reactor-on and reactor-off spectra shows no excess at low energies
and yields upper limits at 95% confidence level for the neutrino interaction
rates. In the lowest-energy range, 50-180 eV, the expected limit stands at 34
(39) times the standard model prediction, while the observed limit is 66 (75)
times the standard model prediction with Sarkis (Chavarria) quenching factors.
