Core-collapse Supernovae, Neutrinos, and the OMNIS project. Alex Murphy. www.hep.man.ac.uk/omnis/. www.physics.ohio-state.edu/OMNIS. The 7 stages of Core Collapse. For a ~10M star… Stage Temp (K) Ashes Duration H burning 2x10 7 He few x 10 6 yrs
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For a ~10M star…
Stage Temp (K) AshesDuration
H burning 2x107Hefew x 106 yrs
He 2x108C, Ofew x 104 yrs
C 8x108Ne, O~600 yrs
Ne 1.4 x109O, Mg~1 yr..
O 2x109Si, S~6 mo..
Si 3.5x109Fe, Ni~1 day
Collapse ~40 x 109 90%n ~few ms
+Ejecta (some of surface
layers, rich in heavy elements)
Not to scale!
Extreme temp: photodissociates nuclei back to protons, neutrons and alphas.
>8 M evolves ~107 yr
Neutronisation: p+e- n+ne
Huge thermal emission of neutrinos
e++e- g+g ; g+g nx + nx(all flavours equally)
r ~ few x rnuclear
Anglo Australian Observatory
LMC about 50 kpc away.
maybe it went to a black hole…?
¼ MT test (Dominic Truckee, 1962)
<E(ne)> = 11 MeV <E(ne)> = 16 MeV <E(nx)> = 25 MeV
Measurement of energies: primary physics goal
EOS, neutrino transport
Q [ 208Pb(n,n’2n)206Pb] = -14.1 MeV
Q [ 208Pb(n,n’n)207Pb] = -7.4 MeV
Q [ 208Pb(ne,e+n)207Bi] = -9.8 MeV
A New Detection Strategy…
Utilize CC & NC reactions from ‘hi-z’ materials with low n-threshold.
Use the higher energies of m and t-neutrinos to enhance their yields – ‘flavour filter’
Strong dependence of neutron yield on n temperature
Sensitivity to oscillations
Dependence on n temperature different for 1n and 2n channels
Sensitivity to shape of n energy spectrum
The Observatory for Multiflavor NeutrInos from Supernovae
nSo – how to build OMNIS
Loaded scintillator (liquid or plastic)
Astroparticle Physics 8 (1997) 27
Astroparticle Physics 16 (2001) 75
JJ Zach, AStJ Murphy, RN Boyd,
NIMS, 2001, accepted
½ kT module
~3000 5” pmts
Includes reactions on H2O
Dt=1.6 [R/8kpc] [m(nt)/50eV]2 [25MeV/E(nt)]2
s t e t c h e s arrival time
profile. Rise of leading edge is probably best
measure of massBeacom, et al PRL 85, 3568
(2000); PRD 63, 073011 (2001).
Simulation: ‘Standard’ SN @ 8kpc. Calculate number of 1n and 2n eventsdetectedin lead.
What combinations of
range, nm temperature,
oscillation scenario and probability of oscillation
is this compatible with?
Caveat! – Assumes shape of energy spectra known, but if solution to SnP is LMA or LOW MSW then Pb(Cl2O4)2 gives us that for nm ! Which dominate event yields
Neutrino Mixing – Parameter space
Extreme long base line gives sensitivity to very small mass differences
Extreme nuclear density in a supernova gives sensitivity to very small mixing angles (under the MSW effect)
-10 –9 –8 –7 –6 –5 –4 –3 –2 –1 0
How the yield in the lead-slab modules would be affected by a cutoff in nx 2ms earlier than a complete shut off at 0.2 second. Simulation is for Betelgeuse.
Allows for incredible timing sensitivity, including a mass measurement at the few eV level (Beacom, et al PRL 85, 3568 (2000); PRD 63, 073011 (2001))
Somewhat more sophisticated analysis in progress by P.F. Smith
important to maximise an event.
Hence a statistically significant
number of m- and t-neutrinos
must be observed in detail.
OMNIS offers the most cost
efficient method of doing so.