PHOTODETACHMENT OF THE 1S2S2P P-4 STATE OF HE- FROM THRESHOLD TO 100 EV

Calculations of cross sections and photoelectron angular distributions from the photodetachment of the 1s2s2p P-4 metastable state of He- ha ve been performed from threshold to 100 eV using multiconfiguration Ha rtree-Fock wave functions for discrete states and coupling continuum c hannels with closed channels to include resonances. Ejection of each e lectron was considered and ejection plus excitation was included in co nnection with is photoabsorption. The 1s2p(2) and 2s2p(2) P-4 resonanc es were found in good agreement with recent experiments and calculatio ns; the reason that the former lies above the 2s threshold while the l atter lies below the is threshold is discussed. The nonresonant 2p cro ss section is in excellent agreement with experiments and other calcul ations. The 2s results, in which Cooper minima are predicted, an not i n agreement with a similar calculation, particularly for the beta para meter. The is cross section shows a large maximum just above threshold , much larger than the 1s cross section in neutral He, and at somewhat higher energy the cross section is dominated by 1s detachment plus ex citation to the (2s3p+/-3s2p) P-3 and 3s3p P-3 autoionizing states of He.