The positron was quickly slowed down by the water and was annihilated by an electron. This annihilation created two photons, each with an energy of about 0.5 MeV. These photons were registered in coincidence in the two scintillation detectors above and below the target where the interaction took place. The neutron also slowed down in the water and was eventually captured by a cadmium nucleus. The experiment was hampered by both a low counting rate, about three events per hour, and a large background. Nevertheless Reines and Cowan succeeded in their attempt to prove the existence of the neutrino as a free particle.
Several publications describe the course of the experiment and the results.
Reines has also been engaged in pioneering experiments probing decay modes of the proton. The big underground facilities used for this purpose can also act as neutrino detectors and give valuable information on cosmic processes. As an example, underground detectors registered neutrinos from the supernova SN1987a on the 23rd of February 1987. One of the detectors, in the Kamioka mine in Japan, registered 11 neutrinos from the supernova. These experiments provided, for the first time, astrophysicists with valuable information on supernovas as well as giving a limit for the neutrino rest mass.