POLARIZATION AND WEAK DECAY OF LAMBDA-HYPERNUCLEI

The (C(pi+,K+)-C-12 reaction was used to produce polarized LAMBDA hypernuclei for the first time. Asymmetries of weak decay particles were measured. In the high excitation region, where quasifree production of LAMBDA hyperons is dominant, the polarization of LAMBDA was derived. It is found to be consistent with that for the elementary n(pi+K+)LAMBDA reaction which demonstrates that the spin characteristics of the elementary reaction is not modified by the nuclear medium. In the low excitation region, where hypernuclei are dominantly produced, asymmetries of the non-mesonic decay protons were measured. The measurement and calculated polarization gave large asymmetry parameter (approximately -1). It will elucidate the non-mesonic decay mechanism and open a new field of hypernuclear physics.