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 neutrinos How they are produced Detectors in the world

Core-collapse supernova

HHe

C+OSi

Fe

Neutrino trapping

Neutron 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 burstNeutrino emission from supernova burst

Livermore simulation

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

Neutrinos carry almost all (99%) of the released gravitational energy (~3x1053 erg.)

Kinetic and optical energies are only ~1%(~1051erg).

Expected time profile

Mean neutrino energy

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 e Temperature__

TheoryTheory

from G.Raffelt

Feb.23, 1987 at 7:35UT

24 events total

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

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 ep e+n events expected for 10 kpc SN.Running since 1980 with ~90% live time.

Criteria of serious candidate: ≥ 9 events/20sec in inner 130ton detectors.(sensitive up to ~20kpc)

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 of CnH2n 900 t of Fe

At Gran Sasso Lab., Italy

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

E resolution: 13%(1) at 15MeV

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

From W.Flugione

Single volume liq. 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( e+p→e++n) : ～ 300 eventsSpectrum measurement with good energy resolution, e.g. for spectrum distortion of earth matter effect.

CC on 12C (e+12C→e+12N(12B)) : ～ 30 eventsTagged by 12N(12B) beta decay

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

Total neutrino flux, 15.11MeV mono-energetic gamma +p scattering （ +p→ +p ） : ～ 300 events

Spectrum measurement of higher energy component.Independent from neutrino oscillation.

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 μ’s, τ’s.• 65 neutrons through e 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 DOMs – 4820• Instrumented volume – 1 km3

• Angular resolution < 1.0°

Design Specifications

Construction finished on Dec.18, 2010.

IceTop

InIce

AMANDA

19 Strings

677 Modules

Supernova neutrinos coherently increase signal rates of PMTs.

(South pole)

From L.Koepke, S.Yoshida

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 detector10 kpc to SN

LMC

Galactic Center

SMC

IceCube

Amanda

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

From L.Koepke

Super-Kamiokande detectorSuper-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 eventsSuper-K: Expected number of events

~7,300 e+p events~300 +e events~360 16O NC 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 detector

Baksan (1980-)

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

No

Super-K(1996-)

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

Yes

KamLAND(2002-)

1000 ton liquid scintillator, single volume. ~300 ep , several 10 CC on 12C, ~60 NC , ~300 p p

No

ICECUBE(2005-)

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

No

BOREXINO(2007-)

300 ton liquid scintillator, single volume. ~100 ep , ~10 CC on 12C, ~20 NC , ~100 p p

No

HALO(2010-)

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

No

# of events expected for 10kpc. Directionality

Distance to Galactic supernovaDistance 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

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

e

Super-Kamiokande: Water Cherenkov detector

One of the SN1987A events in Kamiokande

Emission angle = cos-1(1/n)=42°

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

COSSN

Cross section Angular distribution

Neutrino

Supernova

Angular distribution of Angular distribution of νν ｅｅ＋ｐ→＋ｐ→ｅｅ +++n+n

ν ｅ＋ｐ→ｅ + ＋ n

　

COSSN

neutrino energy

P.Vogel and J.F.Beacom, Phys.Rev.D60(1999)053002.

e+p

e+p

e+p e+p

+e +e

+e +e

Super-K: simulation of angular distributionSuper-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 ep events by neutron tagging with Gadolinium.

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

γ

p

n

Gd

e+

8 MeV

ΔT~20μsVertices within 50cm

Future possible improvement in Super-KFuture possible improvement in Super-K

e

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

Ca

ptu

res

on

G

d

Gd in Water

0.0001% 0.001% 0.01% 0.1% 1%

100%

80%

60%

40%

20%

0%

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

e+p

e+p

e+p e+p

+e +e

+e +e

Super-K: Angular distribution (without Gd)Super-K: Angular distribution (without Gd)

SN at 10kpc

Without ep identification by neutron tagging

e+p e+p

e+p e+p

+e +e

+e

+e

Super-K: Angular distribution (with Gd)Super-K: Angular distribution (with Gd)

With ep identification by neutron tagging

SN at 10kpc

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 sin213>10-3

b: inv. hierarchy sin213>10-3

c: any hierarchy sin213<10-3

IceCube example

Precision of burst onset timePrecision of 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)

cos = t / d

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

Beacom, Vogel, Phys.Rev.D60, 033007, 1999

Triangulation on supernova directionTriangulation on supernova direction

Super-K (36˚N)

d =

38 m

sec

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:0803.0531

arXiv:astro-ph/0406214

From K. Scholberg

High energy accelerators in the universe

Black holeaccretion disk

synce-

p

+

+

e+

e

sync

Possible sources: AGN, supernova remnants, ….

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

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

np

}{ ee

(due to osc.) 1:1:1:: e

Neutrinos

GZK neutrinos

Detectors for Cosmic High Energy 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 km 0.2 kmhVolume: 0.01 km3

Running from 2006

Diffuse limitNow below the Waxman-Bahcall limit

IceCube Preliminary

This work

only

Sean Grullon (UW-Madison)From S.Yoshida

GZK searchIceCube Preliminary

eAll 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.– 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

Super-K: Neutronization burstSuper-K: Neutronization burstSN at 10kpc

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

No oscillation

Normal PH=1 orInverted hierarchy

(e(e--+p+pn+n+ee))

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 +e scattering events)

Event rate of e+p events

Super-K: Time variation measurement by e+pAssuming a supernova at 10kpc.

Time variation of event rate Time variation of mean energy

Enough statistics to discuss model predictions

ep e+n events give direct energy information (Ee = E – 1.3MeV).

e

e

Solid: sum of all

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

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

Expected spectrumSensitivity of temperature measurement

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

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