Type 2 Supernova
Blue
J. van der Velde
Giant
University of
star
Michigan
2 April. 2007 1
After (only) 1 million yrs…..
Shell supported by
pressure of nuclear
fusion burning
2
Core Collapse (~ 1 sec)
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Rebound
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5
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7
1055
neutrinos
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9
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You
Me
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The last two nearby ones were in 1604 and 1572
~ 30 light yrs diam.
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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.
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IMB
Supernova 1987a
A History
Of Dumb Luck ?
Or….
Intelligent Design ?
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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 !
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Sandulek in the LMC
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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….
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6.02 X 1026 protons/Kg
This is not a small number
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compared to 10 years
29
Make that 6 X 10 protons/tonne
……gives 6 decays per tonne per year!
Hmmm….that‟s only a cubic meter of water
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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 !”
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OK, but why not look?
1954, Reines, Cowan, and Goldhaber:
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t >10 years (Phys Rev 96, 1157)
1960 Backenstoss et al. (Nuovo Cimento 16 749)
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t > 10 years
1974, Reines and Crouch: (Phys Rev Lett 32 493)
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t > 10 years (for modes with muon)
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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.
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3 Months Later….
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25
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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
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Proposal Presentation,Washington, May 31, 1979
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“That was a motley crew….
I wonder if they‟ll amount to anything ?”
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28 November ‟79… Big Day!
Official approval from D.O.E.
Dosco machine starts digging
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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
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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
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One year (and $200K) later…
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September
1981
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Turn on the watah
Hank
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30 November: 10 ft of water, small leaks
develop
Divers called in to patch them
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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 !
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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”
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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?
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G: Hey, are those IMB
characters getting our
messages?
The SN1987A neutrinos
are
99.997% of the way there
!
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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?
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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)
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October 7, 1982
10 million triggers
20 contained events
Any candidates for PDK ?
46
This one looks interesting
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• Check opening angle
Opening angle = 135 deg
(Should be 150-180)
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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
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January „83
First public report:
80 days of live time
+ 0
No candidates for P e π
t/b ≥ 5 X 10 yr
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Spring of ‟83
the theorists regroup…
+ 0
“How about µ k …… etc ?”
May ‟83…. Kamiokande taking data
We need more light collection !
G: Uhhhh…. No kidding !
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Pictures for Upgrade Proposal to D.O.E.
Us Them !
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July „83
+ 0 31
Set limit on PDK to (µ k )… ≥ 10 yr
Set limits on Monopole Catalysis of PDK
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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…..
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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!
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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.
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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!
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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
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Two hours later…….
UT 07:35:41
Thirty thousand trillion neutrinos
pass through the IMB detector
Only 8 are left behind
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UT 7:35:41.4
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UT 7:35:41.8
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UT 7:35:42.0
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UT 7:35:42.5
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UT 7:35:42.9
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UT 7:35:44.1
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UT 7:35:46.4
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UT 7:35:46.9
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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:
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Once every 2X10 years !
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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
34
proton lifetime = 2.137 X 10
years 75
The Cast
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The Diaspora, 1987
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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…
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The Angle-energy Distribution
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Hopefully, that will be accomplished by
some of you intelligent designers in the
audience!
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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 !”
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