Neutrino observatoriesGravitational-wave Physics&Astronomy Workshop, January 28, 2011

M.NakahataKamioka observatoryICRR/IPMU, Univ. of Tokyo

SN1987A

Contents Supernova burst neutrinos

How they are produced SN1987A Current detectors in the world What information neutrino detectors can provide

High energy astrophysical neutrinos How they are produced Detectors in the world

Core-collapse supernova

HHe

C+OSi

Fe

n n

n

n

Neutrino trapping

n

nn

n

n

n nnNeutron star

Standard scenario of the core-collapse supernova

Figure from K.Sato

Core-collapse Core bounce

Shock wave at coreShock wave propagationSupernova burst

Neutrino emission from supernova burst

Livermore simulation

T.Totani, K.Sato, H.E.Dalhed and J.R.Wilson, ApJ.496,216(1998)

Released gravitational energy: ~3x1053 erg

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

Energy for explosion and optical emission is only ~1%(~1051erg).

Expected time profile

Mean neutrino energy

(x=m,t)

(x=m,t)

SN1987A: supernova at LMC(50kpc)Kamiokande-II IMB-3 BAKSAN

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

Tot

al B

indi

ng E

nerg

y

95 % CLContours

Spectral ne Temperature_

Theory

from G.Raffelt

Feb.23, 1987 at 7:35UT

24 events total

Supernova burst detectors in the world(running and near future experiments) Super-Kamiokande

KamLAND

BaksanLVD Borexino

SNO+

(under construction)

IceCube

HALO

The Baksan underground scintillation telescope (Russia)

Total number of standard detectors…………..3150Total 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.

E.N.Alexeyev, L.N.Alexeyeva, astro-ph/0212499

From E.N.Alexeyev

Fulgione@to.infn.itTwenty Years after SN1987A  

LVD detector LVD consists of an array of 840 counters, 1.5 m3 each. Total target: 1000 t liquid scintillator

At Gran Sasso Lab., Italy

4MeV thresholdWith 　 <1MeV 　 threshold for delayed signal (neutron tagging efficiency of 50 +- 10 %)

E resolution: 13%(1s) at 15MeV

~300 nep e+n events expected for 10 kpc SN.

From W.Flugione

Single volume liquid scintillator detectorsKamLAND Borexino SNO+

1000ton liq.sci.Running since 2002.

300ton liq.sci.Running since 2007.

1000ton liq.sci.Under construction.

(Kamioka, Japan) (Gran Sasso, Italy) (SNO Lab.,Canada)

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

Liquid scinitillator detectorsExpected number of events(for 10kpc SN)

Events/1000 tons

Inverse beta( ne+p→e++n) : ～ 300 eventsSpectrum measurement with good energy resolution, e.g. for spectrum distortion of earth matter effect. CC on 12C (ne+12C→e+12N(12B)) : ～ 30

eventsTagged by 12N(12B) beta decay Electron scattering (n+e-→ n+e-) : ～ 20

events NC g from 12C (n+12C→n+12C+g): 　　　～ 60

eventsTotal neutrino flux, 15.11MeV mono-energetic gamma n+p scattering （ n+p→ n+p ） : ～

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

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

HALO - a Helium and Lead Observatory

HALO-1 is using an available 76 tonnes of Pb

CC:

NC:

SNO 3He neutron detectors with lead target

In HALO-1 for a SN @ 10kpc†,• Assuming FD distribution with T=8 MeV for nμ’s, nτ’s.• 65 neutrons through ne charged current channels• 20 neutrons through νx neutral current channels

~ 85 neutrons liberated; with ~50% of detection efficiency, ~40 events

expected. HALO-2 is a future kt-scale detector

(SNO Lab., Canada)

From C.Virtue

IceCube: The Giga-ton Detector Array

• Fully digital detector concept• Number of strings – 75• Number of surface tanks – 160• Number of Optical modules

(DOMs) – 4820• Instrumented volume – 1 km3

Design Specifications

Construction finished on Dec.18, 2010.

IceTop

InIce AMANDA Supernova neutrinos coherently

increase single rates of PMTs.

(South pole)

From L.Koepke, S.Yoshida

1450m

2450m

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

IceCube as MeV n detector10 kpc to SN

LMC

Galactic Center

SMC

IceCubeAmand

a

Significance: Galactic center: ~200 s LMC : ~5 s SMC : ~4 s

From L.Koepke

Super-Kamiokande detector 50,000 ton water 32,000 ton photo-

sensitive volume ~2m OD viewed

by 1885 8-inch PMTs

32kt ID viewed by 11,100 20-inch PMTs

22.5kt fid. vol. (2m from wall)

~4.5MeV energy threshold

SK-I: April 1996~ SK-IV is running

Electronics hutLINAC

Control room

Water and air purification system

SK

2km3km

1km(2700mwe)

39.3m

41.4m

Atotsuentrance

AtotsuMozumi

Ikeno-yamaKamioka-cho, GifuJapan

ID

OD

(Kamioka, Japan)

Super-K: Expected number of events

~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

Neutrino flux and energy spectrum from Livermore simulation (T.Totani, K.Sato, H.E.Dalhed and J.R.Wilson, ApJ.496,216(1998))

Summary of current supernova n detectorsBaksan (1980-)

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

No

LVD(1992-)

1000 ton liquid scintillator. 840 counters 1.5m3 each. 4 MeV thres., ~50% eff. for tagging decayed signal.~300 nep e+n events.

No

Super-K(1996-)

32,000 tons of water target.~7300 nep e+n, ~300 nene scattering events.

Yes

KamLAND(2002-)

1000 ton liquid scintillator, single volume. ~300 nep , several 10 CC on 12C, ~60 NC g, ~300 np np

No

ICECUBE(2005-)

Gigaton ice target.By coherent increase of PMT single rates.High precision time structure measurement.

No

BOREXINO(2007-)

300 ton liquid scintillator, single volume. ~100 nep , ~10 CC on 12C, ~20 NC g, ~100 np np

No

HALO(2010-)

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

No

# of events expected for 10kpc. Directionality

Cherenkov light 　　　　　　Emitted when particle travels faster than speed of light in water(c/1.33 ） .

e

Super-Kamiokande: Water Cherenkov detector

q

One of the SN1987A events in Kamiokande

Emission angle = cos-1(1/nb)=42°

• Using hit PMT timing, vertex position is reconstructed.

• Then, direction is reconstructed using hit PMT pattern.

Neutrino interaction in water

ν ｅ + １６ O→e-

+ １６ F

ν ｅ＋ｐ→ｅ ++n　

ν ＋ e －→ ν ＋ｅ－

ν ｅ + １６ O→e+

+ １６ N

COSqSN

Cross section (H2O target) Angular distribution

Neutrino

Supernova n

ne+p

ne+p

ne+p ne+p

n+e n+e

n+e n+e

Super-K: simulation of angular distribution

SN at 10kpc

Direction of supernova can be determined with an accuracy of ~5 degree.

Neutrino flux and spectrum from Livermore simulation

• Identify nep events by neutron tagging with Gadolinium.

•Gadolinium has large neutron capture cross section and emit 8MeV gamma cascade.

γ

p

n

Gde+

8 MeV

ΔT~20μsVertices within 50cm

Future possible improvement in Super-K

ne

0.1% Gd gives>90% efficiencyfor n captureIn Super-K this means ~100 tons of water solubleGdCl3 or Gd2(SO4)3

Cap

ture

s on

Gd

Gd in Water0.0001% 0.001% 0.01% 0.1% 1%

100%

80%

60%

40%

20%

0%

The main purpose of this project is to detect diffuse supernova neutrinos.

ne+p ne+p

ne+p ne+p

n+e n+e

n+en+e

Super-K: Angular distribution (with Gd)

With nep identification by neutron tagging

SN at 10kpc

Direction accuracy can be improved to ~3 degree.

IceCube example

Burst onset timeSimulation of initial stage of a burst (10kpc supernova)

Super-Kamiokande IceCubeHalzen, Raffelt, arXiv:0908.2317

10~40 events in the first 20msec. ±3.5 msec at 95% C.L.

Super-K and IceCube have a few msec precision on onset time.

IceCube (90˚S)

cosq = t / d

If Super-K and IceCube has ~2 msec rise time resolution,cos(q) = ~0.1 (i.e. about 25 deg.).

Beacom, Vogel, Phys.Rev.D60, 033007, 1999 Triangulation on supernova direction

Super-K (36˚N)

d =

38 m

sec

q

Super-K resolution by electron-scattering is much better.

SuperNova Early Warning System

SNO(Canada)until end of 2006

LargeVolumeDetector(Italy)

Super-Kamiokande(Japan)

Individual supernova-sensitive experiments send burst datagrams to SNEWS coincidence computer at Brookhaven National Lab(backup at U. of Bologna)

snews.bnl.gov

Email alert to astronomers if coincidence in 10 seconds

IceCube(South Pole)

Details:

Participating experiments:

arXiv:0803.0531arXiv:astro-ph/0406214

From K. Scholberg

High Energy Astrophysical Neutrinos

Black holeaccretion disk

gsynce-

p

+

m+ nm

nme+

ne

gsync

Possible sources: AGN, supernova remnants, ….

We know cosmic rays(p, He, ..) exist.So, there much be cosmic high energy neutrinos.

There are high energy accelerators in the universe.

Cosmic Ultra High Energy neutrinos

galactic

Extra-galactic

Ultra High Energy Cosmic Ray(UHECR) exists.

“Horizon” of UHECR is ~50Mpc.

cosmic rays interact with the microwave background

g np

mmm m }{ ee

(due to n osc.) 1:1:1:: tm nnn e

Neutrinos

GZK neutrinos

Detectors for High Energy Astrophysical Neutrinos

South poleVolume:1 km3

Construction finished in Dec.2010

AntaresMediterranean sea0.2x0.2x0.4kmVolume: 0.01 km3

Running since May 2008

NT200+Lake Bikal0.2 kmf 0.2 kmhVolume: 0.01 km3

Running from 2006

Diffuse n limitNow below the Waxman-Bahcall limit

IceCube Preliminary

This work

nm only

Sean Grullon (UW-Madison)From S.Yoshida

Atmospheric n

GZK n searchIceCube Preliminary

(ne nm nt)All flavor limits Systematic errors included

Aya Ishihara (Chiba)From S.Yoshida

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 and

IceCube.• High energy neutrinos

– Construction of the IceCube was finished.– High energy neutrino events are expected in near future.

Backups

Distance to Galactic supernovaMirizzi, Raffelt and Serpico, JCAP 0605,012(2006), astro-ph/0604300

Core collapse type

Type Ia

10kpc0 20kpc

Based on birth location of neutron stars

mean: 10.7 kpcr.m.s.: 4.9 kpc

7% probability< 3.16 kpc> x10 statistics

16% probability< 5 kpc> x 4 statistics

3% probability> 20 kpc< 1/4 statistics

ne+p

ne+p

ne+p ne+p

n+e n+e

n+e n+e

Super-K: Angular distribution (without Gd)

SN at 10kpc

Without nep identification by neutron tagging

Accuracy of supernova direction with neutron tag

Accuracy can be improved by a factor of two with neutron tagging.

Accuracy of SN direction with 40000 simulated supernova

Tagging efficiency vs. accuracy (95% CL)

Thomas, Sekikoz, Raffelt, Kachelriess, Dighe, hep-ph/0307050v2

G: Garching model, L: Livermore modela: normal hierarchy sin2q13>10-3

b: inv. hierarchy sin2q13>10-3

c: any hierarchy sin2q13<10-3

Angular distribution of ν ｅ＋ｐ→ｅ ++n

ν ｅ＋ｐ→ｅ + ＋ n

　

COSqSN

neutrino energy

A. Strumia and F. Vissani, Phys.Lett.B564:42-54,2003.

5MeV10MeV20MeV30MeV

Super-K: Neutronization burstSN at 10kpc

Number of events from neutronization burst is 0.9~6 events for SN@10kpc.nep events during this 10msec is about 8 - 30 events.N.H. +adiamacitc case: neutronization=0.9ev., nep = 14 ev.(1.4 for SN direction).

No oscillation

Normal PH=1 orInverted hierarchy

(e-+pn+ne)

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

Neutrino flux and spectrum from Livermore simulation

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

Event rate of ne+p events

ne

nenm n

m nt n

t Solid: sum of all

n+p elastic signal （ n+p→ n+p ） at liq. Scintillator detectors Beacom, Farr, and Vogel, PRD66, 033001(2002)

~300 events/kt above 200keV~150 events/kt above 500keV

Expected spectrum Sensitivity of temperature measurement

Determine original nm, nm, nt, nt temperaturewith ~10% accuracy.(free from neutrino oscillation. ）

Current Borexino threshold: 200keVCurrent KamLAND threshold: 600~700keV(will be lowered after 2008 distillation.)