Comment on a search for a 0- → 0+ pair transition in 16O

The possible 0- → 0+ ground-state pair decay of the 16O 10.95- MeV 0- state was reinvestigated using the 19F (p,α)16O reaction at E/sub p/ = 5.4--5.7 MeV and a magnetic pair spectrometer. A previously reported pair peak of 3.84 MeV due to the 10.952 → 7.117-MeV transition was not observed. The data indicate a much smaller relative population of the 10.95-MeV state in this reaction than reported previously and this places doubt on the upper limit derived earlier for the 0- → 0+ ground-state pair decay. In a test of the 14N(3He,p)16O reaction at E/sub 3He/ = 4 MeV the yield was too low to study the 10.95-MeV state. Using the 13C(d,p)14C reaction at E/sub d/ = 4.5 MeV the 0- → 0+ ground-state branch from the 6.90-MeV 0- state of 14C was found to be <1.1 x 10-4 via pair decay. The corresponding lifetime limit, tau (0- → 0+)/sub e/+e-> 3 x 10-10 sec, is not considered significant. It is concluded that a sensitive search for M0 pair transitions remains to be made