Neutrinos from supernova 1987A

The neutrino detection associated with the recent supernova SN1987A is reexamined in terms of a newtonian cooling model, and the results confronted with the so far fragmentary theoretical simulations of post-explosion cooling. We find a binding energy for the compact remnant of (2.0 ± 0.50) × 10⁵³ erg, a mass 1.1–1.7 M_⊙, and an initial cooling temperature of 5.0 ± 0.6 MeV. T extraction of a neutrino mass limit is considered in this framework and found, in agreement with some previous work, to give a slightly superior limit to present terrestrial experiments.     

Inverted hierarchy of neutrino masses disfavored by supernova 1987A

We discuss the flavor conversion of supernova neutrinos in the three-flavor mixing scheme of neutrinos. We point out that by neutrino observation from supernova one can discriminate the inverted hierarchy of neutrino masses from the normal one if s₁₃²≳a few×10⁻⁴, irrespective of which oscillation solution to the solar neutrino problem is realized in nature. We perform an analysis of data of SN1987A and obtain a strong indication that the inverted mass hierarchy is disfavored unless s₁₃²≲a few×10⁻⁴.     

Cosmic rays and supernova SN 1987a

Summary We discuss the possibility of obtaining information on the contribution to the galactic cosmic-ray flux by young pulsars searching for high-energy gamma-rays from SN 1987a. A small extensive air shower array operating in Chacaltaya (Bolivia, 5200 m a.s.l.) could give significant information at primary energiesE ₀∼10¹⁴ eV.     

Massive photinos and ultraviolet astronomy

The ionisation of hydrogen and helium in the intergalactic medium and of silicon and carbon in galactic halos, including our own, have already tentatively been attributed to photons emitted by decaying neutrinos created in the hot big bang. This hypothesis would require a neutrino mass ～ 100 eV and a radiative lifetime ～ 10²⁷ s. Here we point out that the same ideas could apply instead to photinos. If the photino mass is determined by the grand unification scale ～ 10¹⁵ GeV, then a mass ～ 100 eV would be compatible with experiment and the radiative lifetime of the photino would indeed be expected to be ～ 10²⁷ s.     

The LAPEX experiment for observation of the supernova SN 1987A in hard X-rays

Summary The LAPEX payload is described in the configuration that will be launched to observe the supernova SN 1987A. The balloon flight will be performed from Alice Springs (Australia) in April 1989 as a part of a NASA balloon campaign. The experiment will allow simultaneous observations of source and background in order to minimize systematic errors due to background variations. The limiting flux sensitivity of the instrument in the (20÷200) keV energy band is 4·10⁻⁶ ph/(cm²s keV) or ∼2.5 mCrab for a 10⁴ s observation of SN 1987A. The presence of a⁵⁷Co emission line in the SN 1987A photon spectrum could be detected down to an intensity level of ∼8·10⁻⁵ photons/cm²s as at 99.7% confidence level. The high resolution of the event timing (<0.1 ms) will make it possible to detect millisecond pulsations with amplitudes down to ∼4% of the expected average flux from SN 1987A in the (20÷60) keV band. To speed up publication, the proofs were not sent to the authors and were supervised by the Scientific Committee.     

A search for massive photinos at petra

We have searched for the supersymmetric partner of the photon, the photino, by investigating two-photon and single photon final states in e⁺e^? collisions. No significant signals were observed, which excludes the existence of the photino in the mass range 0.08–18 GeV/c² at the 95% confidence level, subject to the assumptions d=(100 GeV)² and $\text{m}{}_{\mathrm{<mtext>e</mtext><mtext>?</mtext>}}\text{=40}\text{GeV}\text{/c}{}^2$, where d is the supersymmetry breaking scale parameter and $\text{m}{}_{\mathrm{<mtext>e</mtext><mtext>?</mtext>}}$ is the scalar electron mass.     

A statistical analysis of angular distribution of neutrino events observed in Kamiokande II and IMB detectors from supernova SN 1987 A

A detailed statistical analysis of angular distribution of neutrino events observed in Kamiokande II and IMB detectors on UT 07∶35, 2/23'87 is carried out. Distribution functions of the mean scattering angles in the reactions \(\bar \upsilon _e p \to e^ + n\) andve→ve are constructed with account taken of the multiple Coulomb scattering and the experimental angular errors. The Smirnov and Wald-Wolfowitz run tests are used to test the hypothesis that the angular distributions of events from the two detectors agree with each other. We test with the use of the Kolmogorov and Mises statistical criterions the hypothesis that the recorded events all represent \(\bar \upsilon _e p \to e^ + n\) inelastic scatterings. Then the Neyman-Pearson test is applied to each event in testing the hypothesis \(\bar \upsilon _e p \to e^ + n\) against the alternativeve→ve. The hypotheses that the number of elastic events equalss=0, 1, 2, ... against the alternativess≠0, 1, 2, ... are tested on the basis of the generalized likelihood ratio criterion. The confidence intervals for the number of elastic events are also constructed. The current supernova models fail to give a satisfactory account of the angular distribution data.