Type 2 Supernova

1. Type 2 Supernova Blue Giant star J. van der Velde University of Michigan 2 April. 2007

2. After (only) 1 million yrs….. Shell supported by pressure of nuclear fusion burning

3. Core Collapse (~ 1 sec)

4. Rebound

8. 1055 neutrinos

11. You Me

12. The last two nearby ones were in 1604 and 1572 ~ 30 light yrs diam.

13. Which brings us to IMB…. 170,000 years ago a large star, Sandulek, in the Large Magellanic Cloud, underwent gravitational collapse, sending a 10-second wide pulse of neutrinos out into the Universe. This pulse hit the Earth on 23 February, 1987, around UT 04:00, when 3X10**15 neutrinos went through the IMB detector. Six months before, the detector had been upgraded to increase it's photocathode coverage by a factor of four. This gave it just enough sensitivity to record eight neutrino events.

14. IMB Supernova 1987a A History Of Dumb Luck ? Or…. Intelligent Design?

15. Tokyo, August 1978 • The story begins here: XIX th International Conference on High Energy Physics • Actually it began 170,020 years ago in the Large Magelanic Cloud, when humans were still gnawing on bones. They couldn’t even talk let alone do powerpoint …….. Let’s listen in back then, using top-secret “Blue Cloud” technology……..

16. G: Hairy creatures on Earth are starting to show signs of intelligence. In 170,000 years they will have Proton Decay detectors. g: They’ll never find PDK, as you know. Their detectors are 1000 times too small. But what can you expect? Their brains are not made of Silicon. They’re made of meat!

17. G: Yes, too bad. Let’s be nice and send them some supernova neutrinos to appease their funding agencies. g: How about Sandulek in the LMC? G: go for it !

18. Sandulek in the LMC

19. Jump ahead… August, 1978 • The Tokyo conference was all a-buzz with Grand Unification Theories • “Minimal” SU5 was predicting a proton lifetime of 1029 years for the mode p e+ π0 Planes leaving Tokyo were filled with strange characters holding little books and making weird scratches on paper napkins, like….

20. 6.02 X 1026 protons/Kg This is not a small number compared to 1029 years Make that 6 X 1029 protons/tonne ……gives 6 decays per tonne per year! Hmmm….that’s only a cubic meter of water

21. Pre-History • 1925, Hermann Weyl: “ Why doesn’t P+e photons ?” • 1938, E.C.G.Stueckelberg and (1949)E.P. Wigner : “That’s easy there’s something called Baryon Number which is conserved !”

22. OK, but why not look? 1954, Reines, Cowan, and Goldhaber: t >1022 years (Phys Rev 96, 1157) 1960 Backenstoss et al. (Nuovo Cimento 16 749) t> 1026years 1974, Reines and Crouch: (Phys Rev Lett 32 493) t > 1030 years (for modes with muon)

23. 1978 Fall Flurry of Activity • Brookhaven, Irvine, Harvard, Imperial College, Michigan, Oxford, Purdue, Wisconsin….… • For IMB the dust settled in January ’79. A meeting at Irvine signed up: W. Kropp, J. Learned, R. March, F. Reines, J. Schultz, D. Sinclair, H. Sobel, L. Sulak, J. van der Velde. M. Goldhaber was soon added and letters of support were solicited from Glashow, Gell-Mann, Salam and Weinberg.

24. 3 Months Later….

27. Relegated to the appendix, a paragraph about possible supernova detection: “While insensitive to neutrinos below about 50 MeV, [the detector] would give excellent data on the spectrum above this energy and perhaps (uniquely) indicate [the suprnova] source direction.” If their brains were made of Silicon they would have put this up front, not in an appendix

28. Proposal Presentation,Washington, May 31, 1979

29. “That was a motley crew…. I wonder if they’ll amount to anything ?”

30. 28 November ’79… Big Day! • Official approval from D.O.E. • Dosco machine starts digging

32. 28 November ’79… Big Day! • Official approval from D.O.E. • Dosco machine starts digging • 2400 five-inch PMT’s ordered from EMI ------------------------------------------------------------------- • …. One year of salt dust, construction, plumbing, and other grub work ----------------------------------------------------------- • September 1980…. Digging finished! • Schlegel Co. is engaged to install plastic liner

33. Spring of ‘81 G: The neutrino pulse is fast approaching… What’s going on? g: IMB is funded but their PM tubes are too small. Their proposal said they would need an electronics upgrade to detect supernova neutrinos. Kamiokande is thinking much bigger tubes. G: Good for them. They must know about Intelligent Design

34. One year (and $200K) later…

36. September 1981

37. Turn on the watah Hank

38. 30 November: 10 ft of water, small leaks develop • Divers called in to patch them

39. December ‘81 Cosmic ray muon signals look good in 10 ft of water Yes, it really works…. Nice and clean

40. 20 January 1982 Water depth = 13 ft. Larger leaks develop The pool is MT’d We need a better plan Something smooth to support the liner against the water pressure Something that doesn’t dissolve salt !

41. The Answer Use low density (ρ = 1) concrete Pour it in while filling with water Do it in stages to let it harden May, ’82 Dan gives schedule: “Full by August”

42. May 1982 We have some time to think… Idea: (revival) How about installing that hardware which would possibly enable us to see a supernova explosion in our galaxy?

43. G: Hey, are those IMB characters getting our messages? The SN1987A neutrinos are 99.997% of the way there !

44. Hmmmm… • Bethe estimates ≤ one SN /30 years • Essentially all of the signal would be below our threshold Let’s put it on the Back Burner G: Who is Bethe?

45. July 31, 1982 The pool is full: 70 ft, no leaks Reports from Paris ICRC meeting: Soudan-1, NUSEX, KGF are finding “Candidates” We start taking data (slowly)

46. October 7, 1982 10 million triggers 20 contained events Any candidates for PDK ?

47. This one looks interesting

48. Check opening angle Opening angle = 135 deg (Should be 150-180)

49. Hmmm…. • Total energy ? 1230 MeV (Should be ≤ 1100) Muon decay ?

50. Slow time scale window Clear evidence for muon decay Cancel that call to the NY Times