SUPERNOVA NEUTRINOS AT ICARUS G. Mangano INFN, Napoli

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

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

SN explosion dynamics Progenitor Proto Neutron Star ~ 109 g/cm3  ~ 3 1014 g/cm3 T ~ 1010 K T ~ 1011 K MFe ~ 1.4 M MPNS ~ 1.4 – 1.7 M RFe ~ 6 103 Km RPNS ~ 10 - 15 Km Energetics E ~ G MNS2/RNS =1.6 1053 erg (MNS/ M)2 (10 km/RNS) 99% neutrinos 1% kinetic energy 0.01% photons !!

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 400-700 s-1) subsonic for the inner part supersonic for the outer part

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

shock wave From Janka

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)

Neutrino flux spectra and overall features Neutrinos trapped in the high density neutrino-sphere at the emission surface (R ~ 10-20 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 ~ 1053 erg

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

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

SN1987A at Kamiokande and IMB Supernova explosion of Sanduleak-69202 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 1987. Optical brightness at 10.38 UT Detection: KII and IMB Baksan

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

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)

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 SN @ d=10Kpc

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

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

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

Thompson et al 2002

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

Thompson et al 2002

LVD scintillator counters expected events: 102 CC 10 NC

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

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 10-80 MeV SN parameters which may be significantly distinguished : e.o.s., neutrino oscillations, density profile, neutrino mass, neutrino- sphere parameters

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