부산대학교 도서관

Data from the Gamma-Ray Spectrometer on the Solar Maximum Mission satellite has been searched for excess ..gamma..-ray emission coincident with the approx.10-s neutrino burst from supernova 1987A. The absence of a detectable signal allows us to state that the energy in MeV ..gamma.. rays during the burst is <10/sup -10/ of that in supernova neutrinos above 9 MeV. Direct interpretation limits the lifetime of any radiatively unstable massive neutrinos to tau/sub v//sub i//m/sub v//sub i/greater than or equal to6.3 x 10/sup 15/ (B/sub ..gamma..//sub i/f/sub ..gamma..//sub i/) s/eV for m/sub v//sub i/<20 eV, where B/sub ..gamma..//sub i/ and f/sub ..gamma..//sub i/ are the branching ratio for ..gamma.. decay of species i and the fraction of decays giving detectable ..gamma.. rays, respectively.