Observation of a neutrino burst from the supernova SN1987A

A neutrino burst was observed in the Kamiokande II detector on 23 February, 7:35:35 UT (±1 min) during a time interval of 13 sec. The signal consisted of 11 electron events of energy 7.5 to 36 MeV, of which the first two point back to the Large Magellanic Cloud with angles 18°±18° and 15°±27°.

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Letters from the Past - A PRL Retrospective

2008 marked PRL’s 50th anniversary. As part of the celebrations a collection of milestone Letters was started. The collection contains Letters that have made long-lived contributions to physics, either by announcing significant discoveries, or by initiating new areas of research.

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I. Shelton, International Astronomical Union (IAU) Circular No. 4316. Note also that R. H. McNaught subsequently communicated visual magnitude of 6.0 on 23.44 UT February. The first confirmed observation of optical brightening was by G. Garradd, 23.44 February (IAU Circular No. 4316). The last confirmed evidence of no optical brightening was by Shelton, 23.059–23.101 February (IAU Circular No. 4330). There was a possible observation of no optical brightening by A. Jones at 23.39 February (IAU Circular No. 4340).
E. W. Beier, in Proceedings of Seventh Workshop on Grand Unification, Toyama, Japan, April 1986 (to be published).
This is for the entire volume inside the PMT array. The detection efficiency for a fiducial volume of 780 tons, 2 m inside the PMT array is 90% at 10 MeV and 50% at 7.6 MeV.
A. Suzuki, in Proceedings of the Twelfth International Conference on Neutrino Physics and Astrophysics, June, 1986, Sendai, Japan, edited by T. Kitagaki (World Scientific, Singapore, 1986), p. 306.
There is a claim of observation of a neutrino burst of five events of energy >eq 7 MeV in 7 sec, 23.124 UT February (IAU Circular No. 4323), 02:52 UT (University of Torino Preprint), by Castagnoli et al., by use of a liquid scintillator detector of 90 tons effective mass, situated 5000 hg/ ${cm}^{2}$ _ under Mt. Blanc. If this were a real neutrino burst, our detector should have given about (5 +- sqrt 5 ) times (2140 / 90 ) times (1/1.29) times 0.3 = 28 +- 12 events in 7 sec at the same UT, where the second factor is the ratio of detector masses, the third factor is the ratio of free protons per unit mass in water and liquid scintillator, and the last factor is our detection efficiency for 7-MeV electrons ( $N_{hit}$ >= 18). We searched carefully for such a burst in our data and found no sign of any burst at or around the claimed UT. In particular, during the 2-min interval centered at 02:52 UT 23 February 1987, the Poisson distribution of events per 10 sec with $N_{hit}$ >= 20 obtained, with n ¯ = 0.219. The maximum observed event multiplicity per 10 sec satisfying $N_{hit}$ >= 20 in that 2-min interval was 2 (one of which just satisfied $N_{hit}$ >= 30 ), which is expected from the Poisson distribution with a probability of 0.019. The probability of finding by change one 10-sec interval in that 2-min period with multiplicity 2 is then 12 times 0.019 = 0.23. We conclude, as stated in the text, that no evidence for an event burst outside of statistics is present in our data at 02:52 UT +- 1 min 23 February 1987.
S. A. Colgate and R. H. White, Astrophys. J. 143, 626 (1966); S. E. Woosley, J. Wilson and R. Mayle, 302, 19 (1986); A. Burrows and J. M. Lattimer, 307, 178 (1986). For a review of the current understanding of the supernova phenomenon, see R. Mayle, Ph.D. thesis, University of California, Berkeley, 1985 (unpublished); S. E. Woosley and Thomas A. Weaver, Annu. Rev. Astron. Astrophys. 24, 205 (1986).

[c1] I. Shelton, International Astronomical Union (IAU) Circular No. 4316. Note also that R. H. McNaught subsequently communicated visual magnitude of 6.0 on 23.44 UT February. The first confirmed observation of optical brightening was by G. Garradd, 23.44 February (IAU Circular No. 4316). The last confirmed evidence of no optical brightening was by Shelton, 23.059–23.101 February (IAU Circular No. 4330). There was a possible observation of no optical brightening by A. Jones at 23.39 February (IAU Circular No. 4340).

[c2] E. W. Beier, in Proceedings of Seventh Workshop on Grand Unification, Toyama, Japan, April 1986 (to be published).

[c3] This is for the entire volume inside the PMT array. The detection efficiency for a fiducial volume of 780 tons, 2 m inside the PMT array is 90% at 10 MeV and 50% at 7.6 MeV.

[c4] A. Suzuki, in Proceedings of the Twelfth International Conference on Neutrino Physics and Astrophysics, June, 1986, Sendai, Japan, edited by T. Kitagaki (World Scientific, Singapore, 1986), p. 306.

[c5] There is a claim of observation of a neutrino burst of five events of energy >eq 7 MeV in 7 sec, 23.124 UT February (IAU Circular No. 4323), 02:52 UT (University of Torino Preprint), by Castagnoli et al., by use of a liquid scintillator detector of 90 tons effective mass, situated 5000 hg/ ${cm}^{2}$ _ under Mt. Blanc. If this were a real neutrino burst, our detector should have given about (5 +- sqrt 5 ) times (2140 / 90 ) times (1/1.29) times 0.3 = 28 +- 12 events in 7 sec at the same UT, where the second factor is the ratio of detector masses, the third factor is the ratio of free protons per unit mass in water and liquid scintillator, and the last factor is our detection efficiency for 7-MeV electrons ( $N_{hit}$ >= 18). We searched carefully for such a burst in our data and found no sign of any burst at or around the claimed UT. In particular, during the 2-min interval centered at 02:52 UT 23 February 1987, the Poisson distribution of events per 10 sec with $N_{hit}$ >= 20 obtained, with n ¯ = 0.219. The maximum observed event multiplicity per 10 sec satisfying $N_{hit}$ >= 20 in that 2-min interval was 2 (one of which just satisfied $N_{hit}$ >= 30 ), which is expected from the Poisson distribution with a probability of 0.019. The probability of finding by change one 10-sec interval in that 2-min period with multiplicity 2 is then 12 times 0.019 = 0.23. We conclude, as stated in the text, that no evidence for an event burst outside of statistics is present in our data at 02:52 UT +- 1 min 23 February 1987.

[c6] S. A. Colgate and R. H. White, Astrophys. J. 143, 626 (1966); S. E. Woosley, J. Wilson and R. Mayle, 302, 19 (1986); A. Burrows and J. M. Lattimer, 307, 178 (1986). For a review of the current understanding of the supernova phenomenon, see R. Mayle, Ph.D. thesis, University of California, Berkeley, 1985 (unpublished); S. E. Woosley and Thomas A. Weaver, Annu. Rev. Astron. Astrophys. 24, 205 (1986).

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Observation of a neutrino burst from the supernova SN1987A

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Letters from the Past - A PRL Retrospective

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