Updated limits on the electron neutrino mass and large angle oscillations from SN1987A Original Research Article

We supplement Maximum Likelihood methods with a Monte-Carlo 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 ≤ sin2 2θv ≤ 1, is permitted, and the Maximum Likelihood mixing angle is sin2 2θv = 0.45. In the latter case we find that the inclusion of “dead-time” reduces previous mνe upper bounds by 10%, and supplementing the Maximum Likelihood analysis with a Monte-Carlo goodness-of-fit test results in a further 15% reduction in the mνe upper limit. Our 95% C.L. upper limit for mνe is 19.6 eV, while the best fit value is ∼ 0 eV.