 A first proposal to test Bell inequality was made by Clauser, Horne, Shimony, and Holt (1969), henceforth CHSH, who suggested that the pairs 1 and 2 be photons produced in an atomic cascade from an initial atomic state with total angular momentum \(J = 0\) to an intermediate atomic state with \(J = 1\) to a final atomic state \(J = 0\), as in an experiment performed with calcium vapor for other purposes by Kocher and Commins (1967). The proposed test was first performed by Freedman and Clauser (1972). The result obtained by Freedman and Clauser was 6.5 standard deviations from the limit allowed by the CHSH inequality but in good agreement with the quantum mechanical prediction. This was a difficult experiment, requiring 200 hours of running time, much longer than in most later tests of Bell’s Inequality, which were able to use lasers for exciting the sources of photon pairs. 