Supernovae Conference, Kyoto, October 31, 2013

Detection of supernova Neutrinos
M.Nakahata
Kamioka observatory
ICRR/IPMU, Univ. of TokyoSN1987A

Contents
 Supernova burst neutrinos
 SN1987A
 Current detectors in the world What information neutrino detectors can provide Supernova relic neutrinos(Diffuse Supernova Neutrino Background) Expected signals
 GADZOOKS! project at Super-K
 Current R&D status

 Future large volume detectors
 Liquid Ar Water Cherenkov

 For nearby (e.g. betelgeuse) supernova
 Activity at Super-K
 Can we detect precursor (Si burning neutrinos) ?

Neutrino emission from core collapse supernova
Released gravitational energy: ~3x1053 erg

Expected time profile

Neutrinos carry almost all (99%) of the energy.

So, neutrino detection is important toinvestigate energy flow of the core collapse.

Livermore simulation(x=m,t)(often used for signal estimation for neutrino detectors)

Mean neutrino energy(x=m,t)T.Totani, K.Sato, H.E.Dalhed and J.R.Wilson, ApJ.496,216(1998)

SN1987A: supernova at LMC(50kpc)
Kamiokande-IIFeb.23, 1987 at 7:35UT

IMB-3

BAKSANInterpreting SN 1987A Neutrinos

Kam-II (11 evts.)
IMB-3 (8 evts.)
Baksan (5 evts.)

24 events total

Jegerlehner, Neubig & Raffelt, PRD 54 (1996) 1194

History of supernova detectors
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 29 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0
8 8 8 8 8 8 8 8 8 8 9 9 9 9 9 9 9 9 9 9 0 0 0 0 0 0 0 0 0 0 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3

BAKSAN (330t liq.sci.)
IMB (7000t water)
Kamiokande (2140t water)

LSD(90t liq. sci.)
LVD (3301000t liq. sci.)
SN1987aSuper-Kamiokande (32000t water)
Amanda/IceCube
SNO (1000t D2O)
KamLAND(1000t liq.sci.)
Borexino(300t liq.sci.)

HALO (76t Pb, 3He counter)5Supernova burst detectors in the world(running and near future experiments)
Super-Kamiokande
Borexino LVD
BaksanSNO+KamLAND(under construction)

HALO

IceCubeThe Baksan underground scintillation telescope (Russia)
Each detector

E.N.Alexeyev, L.N.Alexeyeva, astro-ph/0212499
A. Gaponenko et al., ICRC2013, Paper ID: 621

Total number of standard detectors…………..3150
Total target mass…………………….…...330 tons of oil-based scintillator~100 nep e+n events expected for 10 kpc SN.
Running since 1980 with ~90% live time.
No candidate for 28 years’ observation time from 1980 to 2013.
Upper limit of SN rate: < 0.082 /yr
From E.N.Alexeyev, A. Gaponenko

LVD detector (at Gran Sasso, Italy)
LVD consists of an array of840 counters, 1.5 m3 each.

Total target:
1000 t liquid scintillator
4MeV thresholdWith <1MeV threshold fordelayed signal (neutron tagging
efficiency of 50 +- 10 %)E resolution: 13%(1s) at 15MeV~300 nep e+n events
expected for 10 kpc SN.
No candidate for 19.3 years from1992 to 2013.
Upper limit of SN rate: < 0.12 /yr
C.Vigorito et al., ICRC2013, Paper ID: 453
From W.Flugione

Single volume liquid scintillator detectors
KamLAND

Borexino(Kamioka, Japan)(Gran Sasso, Italy)

SNO+(SNO Lab.,Canada)

300ton liq.sci.
Running since 2007.

1000ton liq.sci.
1000ton liq.sci.
Running since 2002.

From K.Inoue, G.Bellini, M.Chen

Under construction.

Liquid scinitillator detectors
Expected number of events(for 10kpc SN)
Events/1000 tons
 Inverse beta( ne+p→e++n) :～300 events

Spectrum measurement with good energy resolution, e.g. forspectrum distortion of earth matter effect.
 CC on 12C (ne+12C→e+12N(12B)) :～30 events

 Electron scattering (n+e-→ n+e-) : NC g from 12C (n+12C→n+12C+g):～20 events～60 events

Tagged by 12N(12B) beta decay

Total neutrino flux, 15.11MeV mono-energetic gamma

 n+p scattering（ n+p→ n+p）:～300 events

Sensitive to all types of neutrinos.
(Independent from neutrino oscillation)
Spectrum measurement of higher energy component.

From K.Inoue, G.Bellini, M.Chen

HALO (SNOLAB, Canada)
SNO 3He neutron detectors with lead target
CC:

NC:

HALO is using 76 tonnes of Pb
For a SN @ 10kpc†,• Assuming FD distribution with T=8 MeV for nμ’s, nτ’s.
• 68 neutrons through ne charged current channels• 20 neutrons through νx neutral current channels~ 88 neutrons liberated;with ~50% of detection efficiency, ~40 events expected.

From C.Virtue

IceCube (South pole)
IceTopDesign Specifications

InIce
AMANDA

From L.Koepke, S.Yoshida• Fully digital detector concept• Number of strings – 75
• Number of surface tanks – 160• Number of Optical modules(DOMs)– 4820• Instrumented volume – 1 km3

Supernova neutrinos coherently
increase single rates of PMTs.

Running with full detectorconfiguration since Dec.,
2010.

IceCube signal
10 kpc to SN
Simulation based on Livermore model

Advantage:
 high statistics(0.75% stat. error@ 0.5s and 100ms bins)
Good for fine time
structures (noise low)!
Disadvantage:
 no pointing
 no energy intrinsic noise
Significance:
Galactic center: ~200 s
LMC: ~5 sSMC: ~4 sGalactic
CenterIceCubeLMC

SMC
AmandaFrom L.Koepke

High frequency signal variation by SASI
SASI=standing accretion shock instability
luminosity

2-D(axially symmetric) simulation
with PROMETHEUS-VERTEX codeSupernova at 10kpc
IceCube “event” rateenergyT.Lund et al., Phys. Rev. D82, 063007(2010).

Super-K: Expected number of events
Neutrino flux and energy spectrum from Livermore simulation(T.Totani, K.Sato, H.E.Dalhed and J.R.Wilson, ApJ.496,216(1998))

32kton water Cherenkov~7,300 ne+p events~300 n+e events~360 16O NC g events~100 16O CC events(with 5MeV thr.)

for 10 kpc supernova

Model dependence of Super-K prediction
Livermore simulation T.Totani, K.Sato, H.E.Dalhed and J.R.Wilson, ApJ.496,216(1998)
Nakazato et al. K.Nakazato, K.Sumiyoshi, H.Suzuki, T.Totani, H.Umeda, and S.Yamada,
ApJ.Suppl. 205 (2013) 2, (20Msun, trev=200msec, z=0.02 case)Total number of events
Number of events comparison

Livermore

Nakazato

ne+p7300

3100

n+e320170

16O CC110

57for 10 kpc supernova
32kton SK volume
4.5MeV(kin) thresholdwithout n oscillation

Factor of ~2 difference
Ethr=3.5MeV(kin)Summary of current supernova n detectors# of events expected for 10kpc.

Baksan(1980-)

LVD(1992-)

Super-K(1996-)

KamLAND(2002-)ICECUBE(2005-)

Directionality

330 ton liquid scintillator~100 nep e+n events.

No1000 ton liquid scintillator. 840 counters 1.5m3 each. 4 MeVthres., ~50% eff. for tagging decayed signal.
~300 nep e+n events.

No32,000 tons of water target.
~7300 nep e+n, ~300 nene scattering events.

Yes

1000 ton liquid scintillator, single volume.
~300 nep , several 10 CC on 12C, ~60 NC g, ~300 np  np
Gigaton ice target.
By coherent increase of PMT single rates.
High precision time structure measurement.

NoBOREXINO 300 ton liquid scintillator, single volume.
(2007-)~100 nep , ~10 CC on 12C, ~20 NC g, ~100 np  np

HALO

SNO 3He neutron detectors with 76 ton lead target.
~40 events expected.

(2010-)

NoNo
No

Super-K: simulation of angular distribution
n+en+eSN at 10kpc

ne+pne+pn+en+e
Direction of supernova canbe determined with anaccuracy of ~5 degree.

ne+pne+p

Neutrino flux and spectrum
from Livermore simulation

Supernova Relic Neutrinos
SRN flux from Horiuchi et al.
PRD, 79, 083013 (2009)

SRN predictions(ne fluxes)

Expected SRN events
1.3 -6.7 events/year/22.5kt(10-30MeV)
SK fiducial
volumeLarge target mass and highbackground reduction arenecessary.

GADZOOKS! project at Super-K

Identify nep events by neutron tagging with Gadolinium.

neCaptures on Gd

Gadolinium has large neutron capture cross section and emit
8MeV gamma cascade.
0.1% Gd gives
np+eGdγ

100% ~90% efficiency
for n capture
In Super-K this means~100 tons of water soluble
80% Gd (SO )24 360%

8 MeV

ΔT~20μs
Vertices within 50cm

40%20%0%
0.0001% 0.001%

0.01%

0.1%

Gd in Water

1%

Expected SRN signal and background at Super-K
33~45 ev.

26~34 ev.

Expect number of
events in 10 years in
Etotal =10-30 MeV
Assuming

Capture efficiency of
90% and Gd gamma
detection efficiency of74%.

13~16 ev.

12~16 ev.

Invisible muon B.G. is
35% of the SK-IV
invisible muon BG.

Min/nominal/Max are
due to uncertainties inastronomy.

Background: ~18 ev.
SRN flux from Horiuchi et al.
PRD, 79, 083013 (2009)

EGADS
Evaluating Gadolinium’s Action on Detector Systems
200 m3 tank with 240 PMTs

15m3 tank to dissolve Gd

Gd water circulation system(purify water with Gd)

Transparency measurement(UDEAL)

Transparency of Gd-loaded water (before mounting PMTs)
Cherenkov Light Left(%)

9085

80
75
70
65
60

The light left at 15 m in the 200m3 tank (stainless steel) was ~69% for 0.2%
Gd2(SO4)3 , which corresponds to ~84% of pure water.

240 PMTs were mounted in the 200 m3 tank in thissummer.

Pure water circulation was started.
Gd-loaded test is expected start soon.

Super-K: Angular distribution (without Gd)
n+en+eWithout nep
identification by
neutron tagging

ne+pne+pn+ene+pn+ene+p

SN at 10kpc

Super-K: Angular distribution (with Gd)
n+en+eWith nep
identification by
neutron tagging

ne+pne+pn+ene+pne+pn+e

Direction accuracy can be
improved to ~3 degree.

SN at 10kpc

Future Large Volume Detectors
Hyper-Kamiokande

LBNE (US)(0.74 Mton Water Cherenkov)(10 – 34 kton Liq. Ar detector)

LBNO (Europe)(20kton Liq. Ar, 50kton Liq. scintillator) JUNO(China)(20kton Liq. Sci.)

RENO-50(Korea)(18kton Liq. Sci.)

Supernova events at Hyper-Kamiokande~200,000 ne+p events
7,000~8000 n+e events(-)~10,000 ne+16O eventsfor 10 kpc supernova

30~50 events even for M31
supernova

Each band covers, no osc.,
N.H. and I.H. cases

Hyper-K: Neutronization burst(e-+pn+ne)
SN at 10kpc
Neutrino flux and spectrum from Livermore simulation
Event rate of ne+p events

Event rate of neutronization burst(forward peaked n+e scattering events)

No oscillation
Normal PH=1 orInverted hierarchy

Normal hierarchy PH=0PH: crossing probability at H resonance(PH=0: adiabatic)

Number of events from neutronization burst is 20~130 events for SN@10kpc.
nep events during this 10msec is about 190 - 200 events.
N.H. +adiamacitc case: neutronization=~20ev., nep = ~350 ev.(~35 for SN direction).

SASI Detection Perspective
I. Tamborra (TAUP2013)

Their 3D 27 MSUN progenitor shows
pronounced SASI.

SASI sinusoidal modulation of theneutrino signal will be detectable byIceCube and Hyper-K.

I.Tamborra et al., arXiv:1307.7936

Expected signal in Liquid Ar
For 34 kton Liq. ArSN @ 10 kpc

ChannelNo. of events(observed),
LivermoreInteractions, as a function of neutrino energy
No of events(observed),
GKVM, 34kton

Nue-Ar40 2848

2308

NuebarAr40

134

194

ES

178

296

Total

3160

2798

Dominated by ne

From K. Scholberg

If Betelgeuse explodes…

Image credits: © 2010 Haubois / Perrin(LESIA, Paris Observatory)

Betelgeuse shrank by 15% in
15 years. (cf. ApJ 697, L127)

It may explode tomorrow or 500,000 years from now.
(from Nomoto-san)It is only ~640 light-years (0.2kpc) from us.

Event Rate [Hz]New electronics for Betelgeuse at Super-K
•

107
106
105
104
103

•

102

If Betelgeuse explodes,– #events@SK: > 30M / 10s– Max. event rate: > 30MHz
Current DAQ– Handles up to 6M events/10s– Records only first 20%• Bottleneck: disk access speed

time [s]Data flow to the new electronics

Front-endelectronics

The new electronics will record sum of PMT
hits with 60kHz continuously, and 60MHz
data for ~1 minute around the burst.

Thermal Neutrinos during Si burning phase
A.Odrzywolek, M.Misiaszek, M.Kutschera, AIP Conf. Proc. 944, 109(2007)

This means only neutron signals inne+p interactions.

In case of Betelgeuseνｅ spectrum

Flux@1pc(106/cm2/s/MeV)

Neutrino-cooled stage of the 15 x Msun star48, 24, 12, 6 and 3
hours before corecollapse.

123

45 MeVIn this paper, distance is assumed to be 0.13kpc. So, the numbers must be reduced to 50%.

Neutrinos during the Si-burning phase can be used for precursor ofcore collapse.

Conclusions• Supernova burst neutrinos– Many detectors in the world with various types of signals.
– ~8,000 events expected at Super-K for 10kpc SN.
– High precision time profile by Icecube.
– ~5 deg. accuracy in direction of supernova by Super-K
neutron-electron scattering events.
– Onset time with ~2 msec resolution by Super-K andIceCube.

• Supernova relic Neutrinos– R&D for GADZOOKS! project is ongoing.

• Nearby (Betelgeuse) supernova– New electronics at Super-K.
– KamLAND and Super-K(GADZOOKS!) can get precursor
using Si-burning neutrinos.