The fact that inclusively produced hyperons are produced with significant polarization was first discovered at Fermilab about seventeen years ago. This and subsequent experiments showed that [Lambda][degree] were produced polarized while [bar [Lambda] [degree]] had no polarization in the same kinematical region. This set the stage for many experiments which showed that most hyperons are produced polarized. Recent Fermilab experiments have showed that this phenomena is even more complex than previously thought and theoretical understanding is still lacking. Nevertheless polarized hyperon beams have been an extremely useful experimental tool in measuring hyperon magnetic moments and hyperon [beta]-decay. Recently, hyperon radiative decays have been studied and magnetic moment precession of channeled particles in bent crystals has been observed.

Final results are presented from an experimental investigation of the .beta. decay of polarized .lambda. hyperons with a large-aperture magnetic spectrometer. The data sample consists of 544 events. The values A/sub .nu./ = 0.72 +- 0.12, A/sub e/ = 0.05 +- 0.12, and A/sub p/ = -0.47 +- 0.12 are obtained for the three spin asymmetry parameters, and A/sub e.nu./ = 0.07 +- 0.12 for the electron-neutrino correlation. The lepton-plane correlation with the .lambda. spin, D = 0.11 +- 0.20, is consistent with no violation of time reversal invariance. The data yield an axial vector to vector form factor ratio of g1/f1 = 0.53/sub -0.09//sup +0.11/. The Cabibbo model value is g1/f1 = 0.71.