1. SUPERNOVA NEUTRINOS AT ICARUS
G. Mangano
INFN, Napoli

2. Summary - SN explosion dynamics - Neutrino spectra and overall features - SN 1987A at Kamiokande and IMB - SN & ICARUS - SNO, SK, LVD - Oscillations - Issues to be studied

3. He and H shell burning
He core burning
He flash
growing He core
turn-off
white dwarfs
H burning

4. SN explosion dynamics Progenitor Proto Neutron Star
~ 109 g/cm3  ~ g/cm3
T ~ 1010 K T ~ 1011 K
MFe ~ 1.4 M MPNS ~ 1.4 – 1.7 M
RFe ~ Km RPNS ~ Km
Energetics
E ~ G MNS2/RNS = erg (MNS/ M)2 (10 km/RNS)
99% neutrinos
1% kinetic energy
0.01% photons !!

5. Evolved massive stars (M> 8 M) have a degenerate core of iron group elements (the most tightly bound nuclei) no further nuclear burning phase
at T125 MeV iron photodissociation: instability and collapse begins
Pressure lost via e- capture on nuclei
Inner core collapse is homologous (v/r  s-1)
subsonic for the inner part
supersonic for the outer part

6. Neutrino sphere: diffusion time (neutral current interactions on nuclei) larger than collapse time:
’s are trapped in a degenerate sea (YL0.1)
at nuclear density (31014 g cm-3) e.o.s. stiffens and subsonic core collapse slows down
supersonic core continues and “rebounces”: shock wave and SN explosion (“prompt” scenario)
However: unsuccesful ! Shock stalls and eventually recollapses
neutrino losses + iron material dissociation
“delayed” scenario: shock revival by neutrino energy deposition

7. shock wave
From Janka

9. prompt e burst
shock breaks through neutrino sphere:
nuclei dissociation
protons liberated allow for quick neutronization
e burst (10-2 s)
Beyond the shock: proto-neutron star (R~30 Km,) which contracts, deleptonizes and cools via all flavor (anti) neutrino emission (10 s)

11. Neutrino flux spectra and overall features
Neutrinos trapped in the high density neutrino-sphere
at the emission surface (R ~ Km)
T ~ 2<E>/3 ~ GMmN/3R ~ 10 – 20 MeV
Emission via diffusion
tdiff ~ R2/  ~ GF2 E2 nN ~ 102 cm tdiff = O(1 s)
Total luminosity
Etot ~ GM2/R ~ erg

12. Neutrino energy distribution T ~ <E>/3
e <E> ~ 10 –12 MeV
e <E> ~ 14 –17 MeV
, , , <E> ~ 24 –27 MeV
opacity regulated by scattering on (less abundant) protons
opacity regulated by neutral current only
Fermi-Dirac-like =2
Equipartition of flux
L(e) ~ L( e) ~ L(x) ~ L( x)
Maxwell-Boltzmann-like
Cross-sections depends on energy; T and density profile

13. Time evolution of neutrino signal
prompt e burst 1051 erg in #10 msec
other flavor (anti)neutrino energy and luminosities raises when shock stalls and matter accretes (100 ms) 10% - 25% of the total luminosity in 0.5 sec
Formed protoneutron star cooling 90% -75% of total luminosity

15. SN1987A at Kamiokande and IMB
Supernova explosion of Sanduleak in the Large Magellanic Cloud (50 Kpc)
Neutrino observed at Kamiokande II, IMB (water cherenkov) and Baksan (scintillation light) at 7:35:40 UT on 23th february Optical brightness at UT
Detection: KII and IMB
Baksan

17. Time energy analysis
(Loredo and Lamb 1995)
T(t)=Tc0/(1+t/3c)

18. SN & ICARUS SN explosion rate
In our galaxy 7.3 h2 per century (from observations in other galaxies)
Large Magellanic Cloud 0.5 per century
but record of hystorical SN suggests a larger number
A rate of 1 per year requires distances of 15 Mpc (Virgo cluster) (too low signal in ICARUS. See later)

19. TMeV .6Ktons 1.2Ktons 3.5 4 8 5 2 1 16 Detection tecnique
- Elastic scattering
Recoil electron direction highly correlated to  direction
Larger for e (prompt pulse)
TMeV
.6Ktons
1.2Ktons
e e
3.5 4 8 5 2
, e 1
total 16
ICARUS initial physics program
d=10Kpc

20. T MeV 0.6ktons 1.2ktons Fermi 11 15 30 GT 60 total 45 90 e capture
super allowed Fermi
and GT transitions
T MeV
0.6ktons
1.2ktons
Fermi 11 15 30 GT 60
total 45 90
Good sensitivity to prompt e burst and to first 100 ms flux

22. caveats: no energy dependent sensitivity and energy threshold
no oscillation effects (some result by Vissani,Cavanna,Palamara Nurzia: full swap)
Similar results in
Thompson et al
2002

23. SNO, SK, LVD SK water Cherenkov detector (32 ktons)
e flux raises after prompt burst
SK water Cherenkov detector (32 ktons)
15.4 MeV threshold

24. Thompson et al 2002

25. SNO D2O detector (1 ktons)
Eth  2.2MeV
Eth  1.4 MeV
Eth  4 MeV

26. Thompson et al 2002

27. LVD scintillator counters
expected events: 102 CC
10 NC

28. Oscillations (under study) General expectations:
Prompt e much harder to observe (reduced x interactions)
Harder e flux, due to mixing
e  , enhances energy transfer from neutrino flux to matter behind the stalled shock

29. Issues to be studied
neutrino fluxes as a diagnostic tool for SN model: prompt e burst, 100 ms shock revival and all flavor neutrino fluxes
ICARUS may be sensible to prompt breakout, O(10) e events, good directionality.
outlook: neutrino oscillations (trigger design)
detection efficiency
neutrino cross section at MeV
SN parameters which may be significantly
distinguished : e.o.s., neutrino oscillations,
density profile, neutrino mass, neutrino-
sphere parameters

31. Star evolution Stellar structure Hydrostatic equilibrium
thermal pressure:
negative specific heat
degeneracy pressure:
positive specific heat
Stellar structure
Hydrostatic equilibrium
Energy conservation
- Energy transfer