IMB

Type 2 Supernova J. van der Velde University of Michigan 2 April. 2007 Blue Giant star 1 After (only) 1 million yrs….. Shell supported by pressure of nuclear fusion burning 2 Core Collapse (~ 1 sec) 3 Rebound 4 5 6 7 1055 neutrinos 8 9 10 You Me 11 The last two nearby ones were in 1604 and 1572 ~ 30 light yrs diam. 12 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. 13 IMB Supernova 1987a A History Of Dumb Luck ? Or…. Intelligent Design ? 14 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…….. 15 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! 16 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 ! 17 Sandulek in the LMC 18 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…. 19 6.02 X 1026 protons/Kg This is not a small number 29 compared to 10 years Make that 6 X 10 29 protons/tonne ……gives 6 decays per tonne per year! Hmmm….that‟s only a cubic meter of water 20 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 !” 21 OK, but why not look?  1954, Reines, Cowan, and Goldhaber: 22 t >10 years (Phys Rev 96, 1157) 1960 Backenstoss et al. (Nuovo Cimento 16 749)  t > 10 years  26 1974, Reines and Crouch: (Phys Rev Lett 32 493) t > 10 years (for modes with muon) 22 30 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. 23 3 Months Later…. 24 25 26 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 27 Proposal Presentation,Washington, May 31, 1979 28 “That was a motley crew…. I wonder if they‟ll amount to anything ?” 29 28 November ‟79… Big Day! Official approval from D.O.E.  Dosco machine starts digging  30 31 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 32 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 33 One year (and $200K) later… 34 35 September 1981 36 Turn on the watah Hank 37  30 November: 10 ft of water, small leaks develop Divers called in to patch them  38 December „81 Cosmic ray muon signals look good in 10 ft of water Yes, it really works…. Nice and clean 39 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 ! 40 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” 41 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? 42 G: Hey, are those IMB characters getting our messages? The SN1987A neutrinos are 99.997% of the way there ! 43 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? 44 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) 45 October 7, 1982 10 million triggers 20 contained events Any candidates for PDK ? 46 This one looks interesting 47 • Check opening angle Opening angle = 135 deg (Should be 150-180) 48 Hmmm…. Total energy ? 1230 MeV (Should be ≤ 1100)  Muon decay ? 49 Slow time scale window Clear evidence for muon decay Cancel that call to the NY Times 50 January „83 First public report: 80 days of live time + 0 No candidates for P e π t/b ≥ 5 X 10 yr 31 51 Spring of ‟83 the theorists regroup… “How about µ k …… etc ?” May ‟83…. Kamiokande taking data + 0 We need more light collection ! G: Uhhhh…. No kidding ! 52 Pictures for Upgrade Proposal to D.O.E. Us Them ! 53 July „83  Set limit on PDK to (µ k )… ≥ 10 + 0 31 yr  Set limits on Monopole Catalysis of PDK 54 September „83  Upgrade proposal presented to D.O.E. 8-inch Hamamatsu PMT‟s imbedded in wave shifter plates 4X light collection ($1.7 M) April ‟84: D.O.E. agrees to $1.5 M, spread out over 3 years. We order 8-inch tubes from Hamamatsu.  Meanwhile we are installing wave shifters on our 5-inch tubes… = “IMB-2” (Still not much good for SN‟s)  G: These people are running out of time ! 55 January „85 “Big List” of limits on 34 decay modes of nucleons published in PRL. Nine “candidates” could be various off-beat modes, but all are consistent with neutrino background, e.g…..  56 Event 663-1770 This is a candidate for neutron decay into e π + - But it could also be a cosmic ray neutrino interaction. “The value of a candidate depends on his background” ……Maurice Goldhaber 57 A tough time for theorists… American Way, July, 1983 58 Sept. 1986….IMB-3 is ready! 59 October „86 We now have four times the Light collection of IMB-1 At a collaboration meeting Eric Shumard revives (again) the idea to upgrade our data acquisition system to facilitate automatic supernova detection. Decision: No $$$, No time, No urgency Rule #One: Listen to your graduate students ! 60 A Few Months Later…. February 23, 1987 UT 02:30 G: Neutrinos just passed Pluto What‟s going on? g: Every one is asleep. 62 UT 05:00 G: the neutrino pulse is just passing Saturn. What gives at IMB? g: Detector on auto…Nobody there, no supernova alert system in place. G: Punish them! 63 UT 05:00:00.001 One of four HV power supplies shuts down at IMB. On-line data analysis system shuts down. Detector limps ahead with ¾ tubes and raw data tapes only Two hours later……. 64 UT 07:35:41 Thirty thousand trillion neutrinos pass through the IMB detector Only 8 are left behind 65 UT 7:35:41.4 66 UT 7:35:41.8 67 UT 7:35:42.0 68 UT 7:35:42.5 69 UT 7:35:42.9 70 UT 7:35:44.1 71 UT 7:35:46.4 72 UT 7:35:46.9 73 The rest is history…. It took us a while to dig out these events from the raw data tape, but once we did the signal was dramatic.  The normal rate of similar events is one every 5 days.  From random probability, 8 such events in 6 sec will occur: Once every 2X10 34 years ! 74 What a crazy coincidence… That‟s just a little greater than the lifetime limits on the proton! G: It‟s not a coincidence… Gabi, have you been playing with the numbers again? g: I cannot tell a lie Boss… I installed a string theory with proton lifetime = 2.137 X 10 years 34 75 The Cast 76 The Diaspora, 1987 77 The Data Phys Rev D37 3361 (1988)78 We‟ll hear a lot more in the next three days about the nice things we have learned from the SN1987a data. We sure would like to see another one! Hint, hint There‟s a lot more to be learned, Including clearing up some mysteries like… 79 The Angle-energy Distribution 80 Hopefully, that will be accomplished by some of you intelligent designers in the audience! 81 Whoops!... More of the Cast: g G: 82 g: “Boss, There‟s a lot of physicists down there that still don‟t believe in Intelligent Design. Maybe they need another Big Lucky Break to convince them.” G: “Send „em to Hawaii !” 83