  We discuss a possibility of detecting a coherent photon pair emission and
related radiative neutrino pair emission from excited atoms. It is shown that
atoms of lambda- and ladder-type three level system placed in a pencil-like
cylinder give a back to back emission of two photons of equal energy
$\Delta/2$, sharply peaked with a width $\propto $ 1/(target size) and well
collimated along the cylinder axis. This process has a measurable rate
$\propto$ (target number density) $^2 \times$ target volume, while a broader
spectral feature of one-photon distribution separated by (mass sum of a
neutrino pair)$^2/(2\Delta)$ from the two photon peak may arise from radiative
neutrino pair emission, with a much smaller rate.
