The experiment used charged pion beams generated with the Alternating Gradient Synchrotron at Brookhaven National Laboratory. The pions decayed to muons which were detected in front of a steel wall; the neutrinos were detected in spark chambers installed behind the wall. The coincidence of muons and neutrinos demonstrated that a second kind of neutrino was created in association with muons. Subsequent experiments proved this neutrino to be distinct from the first kind (electron-type). Steinberger, Lederman and Schwartz published their work in "Physical Review Letters" in 1962.