Transcript Supernova neutrinos at ICARUS

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
H-R DIAGRAM for M3
He and H shell
He core burning 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
  56 Fe  13  4n
Pressure lost via e- capture on nuclei
e   ZA X  ZA1 X  e
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
Revival of a stalled Supernova shock by neutrino heating
Radial trajectories of equal mass shells
shock wave
Shock
propagation
Hot
bubble
Shock
formation
Accretion onto the
PNS
Supernova
ejecta
Proto
Neutron
Star
Neutrino sphere
From Janka
- Wilson, Proc. Univ. Illinois, Meeting on Numerical Astrophysics (1982)
- Bethe & Wilson, ApJ 295 (1985) 14
1- D Failed Explosions
Mezzacappa et al., PRL 86 (2001) 1935
Rampp & Janka,
ApJ 539 (2000) L33
Spherically symmetric simulations, Newtonian and General
Relativistic, with the most advanced treatment of neutrino
transport do not produce explosions.
prompt e burst
shock breaks through neutrino sphere:
nuclei dissociation
protons liberated allow for quick neutronization
e  p  n  e

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)
Supernova Neutrinos: Numerical Neutrino Signal
Totani, Sato, Dalhed & Wilson, ApJ 496 (1998) 216
NC
CC
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
Total luminosity
Etot ~ GM2/R ~ 1053 erg
tdiff = O(1 s)
Neutrino energy distribution
3
E
dL

E / T 
dE 1  e
T ~ <E>/3
e
<E> ~ 10 –12 MeV
e
<E> ~ 14 –17 MeV
opacity regulated by scattering
on (less abundant) protons
, , , <E> ~ 24 –27 MeV
opacity regulated by neutral
current only
Fermi-Dirac-like =2
0.8
Maxwell-Boltzmann-like
0.6
L(e) ~ L( e) ~ L(x) ~ L( x)
Cross-sections
depends on
energy; T and
density profile
0.4
0.2
1
2
3
Equipartition of flux
4
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:
 e  p  n  e
KII and IMB
 e 16 O 16 F  e 
 x  e  x  e
 e  p  n  e
Baksan
 e 16 C 16 N  e 
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)
Detection tecnique
- Elastic scattering
Recoil electron direction
highly correlated to 
direction
Larger for e (prompt pulse)
 ( e e  )  9.2 10 45 E ( MeV ) cm 2
 ( e e  )  3.8 10 45 E ( MeV ) cm 2
 (  , e  )  1.6 10 45 E ( MeV ) cm 2
 (  , e  )  1.3 10 45 E ( MeV ) cm 2
e e
ICARUS initial
physics program
e e
SN @ d=10Kpc
, e
dn 
d ( Ee , E )
N
L
(
t
)

(
E
)
dEe dE dt
e
2
4 d
Ee
, e
total
TMeV
3.5
5
8
8
.6Ktons
4
2
1
1
8
1.2Ktons
8
4
2
2
16
-e capture
 e  40 Ar  e   40 K *
super allowed Fermi
and GT transitions
40
T MeV 0.6ktons
Fermi 11
15
GT
11
30
total
45
Good sensitivity to prompt e burst
and to first 100 ms flux
K   rays
1.2ktons
30
60
90
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)
15.4 MeV
threshold
e flux raises
after prompt
burst
Thompson et al 2002
SNO D2O detector (1 ktons)
Eth  2.2MeV
 x  D  n  p  x
 x  D  n  p  x
Eth  1.4 MeV
x  D  p pe
Eth  4 MeV
x  D  nne


Thompson et al 2002
LVD scintillator counters
e p  e n

 e 12C 12Ne 
 e C  Be
12
12
expected
events: 102 CC

 x ( x ) C   x ( x ) C *
12
12
 x ( x )e   x ( x )e


10 NC
Oscillations
(under study)
General expectations:
1. Prompt e much harder to observe
(reduced x interactions)
2. Harder e flux, due to mixing
3. 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, neutrinosphere parameters
L
dN A ( Ee , t ) 
d B ( E , t ' ) N T
2  B
4 d
dσ A
PBA ( E )
( E , Ee ) ε(E e )
dE
 (t  t 't )dt ' dEe dEdt
Star evolution
thermal pressure:
negative specific heat
Stellar structure
degeneracy pressure:
positive specific heat
- Hydrostatic equilibrium
dp
M (r )  (r )
 G
dr
r2
- Energy conservation
- Energy transfer
   nucl   grav  
dL(r )
 4 r 2 
dr
 1    1   e 1
4 r 2 d (aT 4 )
L( r )  3   dr