In 1987 Greenberg and Mohaparra proposed that the spin statistics theorem could have small violations. With the help of very precise calculations for states of the He atom that violate the Pauli exclusion principle, Deilamian, Gillaspy and Kelleher looked for the 1s2s S 0 of He using an atomic beam spectrometer. The search was unsuccessful with an upper limit of 5×10.