Frederick Reines' and ClydeL. Cowan's first observation of neutrinos was a pioneering contribution that opened the doors to the region of "impossible" neutrinoexperiments.
Reines and Cowan realised the importance of detecting both the neutron and the positron to reduce the risk of erroneous interpretation.
Nevertheless Reines and Cowan succeeded in a feat considered to border on the impossible: They had raised the neutrino from its status as a figure of the imagination to an existence as a free particle.