Yet Another Paper on Sn1987a: Large Angle Oscillations, and the Electron Neutrino Mass

We supplement \ML methods with a \MC simulation to re-investigate the SN1987A neutrino burst detection by the IMB and Kamiokande experiments. The detector simulations include background in the the latter and ``dead-time'' in the former. We consider simple neutrinosphere cooling models, explored previously in the literature, to explore the case for or against neutrino vacuum mixing and massive neutrinos. In the former case, involving kinematically irrelevant masses, we find that the full range of vacuum mixing angles, $0 \le \svac \le 1$, is permitted, and the \ML mixing angle is $\svac = .45.$ In the latter case we find that the inclusion of ``dead-time'' reduces previous $\mnue$ upper bounds by 10\%, and supplementing the \ML analysis with a \MC goodness-of-fit test results in a further 15\% reduction in the $\mnue$ upper limit. Our 95\% C.L. upper limit for $\mnue$ is 19.6eV, while the best fit value is $\sim$ 0eV.