Gravitational-wave Physics& Workshop, January 28, 2011 observatories

M.Nakahata ICRR/IPMU, Univ. of Tokyo

SN1987A Contents n burst Ø How they are produced Ø SN1987A Ø Current detectors in the world Ø What information neutrino detectors can provide n High astrophysical neutrinos Ø How they are produced Ø Detectors in the world Core-collapse supernova Standard scenario of the core-collapse supernova

Core-collapse Neutrino trapping Core bounce

C+O He Si ν H ν Fe ν

ν ν ν ν

Supernova burst propagation Shock wave at core

ν

Neutron star ν ν ν ν Figure from K.Sato Neutrino emission from supernova burst 53 Released gravitational energy: ~3x10 erg Expected time profile Neutrinos carry almost all (99%) of the energy. Energy for explosion and optical emission is only ~1%(~1051erg).

Livermore simulation (x=µ,τ)

Mean neutrino energy (x=µ,τ)

T.Totani, K.Sato, H.E.Dalhed and J.R.Wilson, ApJ.496,216(1998) SN1987A: supernova at LMC(50kpc) Kamiokande-II IMB-3 BAKSAN

Feb.23, 1987 at 7:35UT Kam-II (11 evts.) IMB-3 (8 evts.) Baksan (5 evts.) 24 events total 95 % CL Contours

Total Binding Energy Total Theory

_

from G.Raffelt Spectral νe Temperature Supernova burst detectors in the world (running and near future experiments) Super-Kamiokande Borexino LVD Baksan

SNO+

KamLAND

(under construction) HALO

IceCube The Baksan underground scintillation telescope (Russia)

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

Total number of standard detectors…………..3150 Total target mass…………………….…...330 tons of oil-based

+ ~100 νep àe n events expected for 10 kpc SN. Running since 1980 with ~90% live time.

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

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

E resolution: 13%(1σ) at 15MeV

+ ~300 νep àe n events expected for 10 kpc SN.

TwentyFrom W.FlugioneYears after SN1987A At Gran [email protected] Lab., Single volume liquid scintillator detectors KamLAND Borexino SNO+ (Kamioka, Japan) (Gran Sasso, Italy) (SNO Lab.,Canada)

300ton liq.sci. Running since 2007.

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

From K.Inoue, G.Bellini, M.Chen Liquid scinitillator detectors Expected number of events(for 10kpc SN) Events/1000 tons

+ n Inverse beta( νe+p→e +n) : ～300 events Spectrum measurement with good energy resolution, e.g. for spectrum distortion of matter effect. 12 12 12 12 n CC on C (νe+ C→e+ N( B)) : ～30 events Tagged by 12N(12B) beta decay n (ν+e-→ ν+e-) : ～20 events n NC γ from 12C (ν+12C→ν+12C+γ): ～60 events Total neutrino flux, 15.11MeV mono-energetic gamma n ν+p scattering（ ν+p→ ν+p）: ～300 events Sensitive to all types of neutrinos. (Independent from ) Spectrum measurement of higher energy component.

From K.Inoue, G.Bellini, M.Chen HALO - a Helium and Observatory (SNO Lab., Canada) SNO 3He neutron detectors with lead target

CC:

NC:

HALO-1 is using an available 76 tonnes of Pb In HALO-1 for a SN @ 10kpc†,

• Assuming FD distribution with T=8 MeV for νµ’s, ντ’s.

• 65 neutrons through νe 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 From C.Virtue IceCube: The Giga-ton Detector Array (South pole) IceTop

Design Specifications

• Fully digital detector concept • Number of strings – 75 • Number of surface tanks – 160 1450m • Number of Optical modules (DOMs) – 4820 InIce • Instrumented volume – 1 km3

AMANDA coherently 2450m increase single rates of PMTs.

Construction finished on Dec.18, 2010.

From L.Koepke, S.Yoshida IceCube as MeV ν detector Advantage: 10 kpc to SN F high statistics Simulation based on Livermore model (0.75% stat. error @ 0.5s and 100ms bins) Good for fine time structures (noise low)!

Disadvantage: F no pointing F no energy F intrinsic noise

Significance: Galactic Galactic center: ~200 Center σ LMC : ~5 σ IceCube LMC SMC : ~4 σ SMC Amanda

From L.Koepke Super-Kamiokande detector (Kamioka, Japan)

LINAC Electronics hut and air n 50,000 ton water purification system n 32,000 ton photo- Control room Atotsu entrance sensitive volume n ~2m OD viewed by 1885 8-inch 41.4m ID PMTs n 32kt ID viewed by 11,100 20-inch OD PMTs Ikeno-yama 1km n Kamioka-cho, Gifu 22.5kt fid. vol. (2700mwe) (2m from wall) Japan 3km 2km n ~4.5MeV energy Mozumi 39.3m SK Atotsu threshold n SK-I: April 1996~ n SK-IV is running 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))

~7,300 νe+p events ~300 ν+e events ~360 16O NC γ events ~100 16O CC events (with 5MeV thr.) for 10 kpc supernova Summary of current supernova ν detectors # of events expected for 10kpc. Directionality Baksan 330 ton liquid scintillator No + (1980-) ~100 νep àe n events. LVD 1000 ton liquid scintillator. 840 counters 1.5m3 each. 4 MeV No (1992-) thres., ~50% eff. for tagging decayed signal. + ~300 νep àe n events. Super-K 32,000 tons of water target. Yes + (1996-) ~7300 νep àe n, ~300 νeàνe scattering events. KamLAND 1000 ton liquid scintillator, single volume. No 12 (2002-) ~300 νep , several 10 CC on C, ~60 NC γ, ~300 νp à νp ICECUBE Gigaton ice target. No (2005-) By coherent increase of PMT single rates. High precision time structure measurement. BOREXINO 300 ton liquid scintillator, single volume. No 12 (2007-) ~100 νep , ~10 CC on C, ~20 NC γ, ~100 νp à νp HALO SNO 3He neutron detectors with 76 ton lead target. No (2010-) ~40 events expected. Super-Kamiokande: Water Cherenkov detector Cherenkov light Emitted when particle travels faster than speed e of light in water(c/1.33）.

θ Emission angle = cos-1(1/nβ)=42°

• Using hit PMT timing, vertex position is reconstructed.! • Then, direction is reconstructed using hit PMT pattern.!

One of the SN1987A events in Kamiokande! Neutrino interaction in water

Cross section (H2O target) Angular distribution

‐ ‐ Supernova ν ν＋e →ν＋ｅ

+ νｅ＋ｐ→ｅ +n

１６ - １６ νｅ+ O→e + F １６ + １６ νｅ+ O→e + N

COSθ Neutrino! SN! Super-K: simulation of angular distribution

ν+e ν+e SN at 10kpc

νe+p

νe+p

ν+e ν+e

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

νe+p νe+p Neutrino flux and spectrum from Livermore simulation Future possible improvement in Super-K Identify νep events by neutron tagging with Gadolinium. Gadolinium has large neutron capture cross section and emit 8MeV gamma cascade. 100% 0.1% Gd gives n >90% efficiency for n capture νe! p Gd In Super-K this means + ~100 tons of water soluble e 80% γ GdCl or Gd (SO ) 3 2 4 3

8 MeV Captureson Gd 60% ΔT~20µs Vertices within 50cm 40%

The main purpose of this project is to detect diffuse 20% supernova neutrinos. 0%0.0001% 0.001% 0.01% 0.1% 1% Gd in Water Super-K: Angular distribution (with Gd)

With ν p ν+e e ν+e identification by neutron tagging νe+p νe+p

ν+e Direction accuracy can be ν+e improved to ~3 degree. νe+p νe+p

SN at 10kpc Burst onset time Simulation of initial stage of a burst (10kpc supernova) Super-Kamiokande IceCube Halzen, Raffelt, arXiv:0908.2317

IceCube example

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

Super-K (36˚N) cosθ = Δt / d

θ

IceCube (90˚S)

If Super-K and IceCube has ~2 msec rise time resolution, Δcos(θ) = ~0.1 (i.e. about 25 deg.). Super-K resolution by electron-scattering is much better. SuperNova Early Warning System snews.bnl.gov Details: arXiv:astro-ph/0406214

arXiv:0803.0531 Individual supernova-sensitive experiments send burst datagrams to SNEWS coincidence computer at Brookhaven National Lab(backup at U. of Bologna) Email alert to astronomers if coincidence in 10 seconds Participating experiments:

Large Super- Volume IceCube SNO Kamiokande Detector (South Pole) (Canada) (Japan) (Italy) until end of 2006 From K. Scholberg High Energy Astrophysical Neutrinos! There are high energy accelerators in the . We know cosmic rays(p, He, ..) exist. So, there much be cosmic high energy neutrinos. νe e+ νµ Possible sources: AGN, supernova remnants, …. µ+ νµ

π+ γ sync p γsync e-

Black hole accretion disk Cosmic Ultra High Energy neutrinos! Ultra High Energy (UHECR) exists. “Horizon” of UHECR is ~50Mpc.

Neutrinos

galactic

Extra- galactic

cosmic rays interact with the GZK neutrinos microwave background p +γ → Δ+ → n +π +

π → µ +υµ →{e +υµ +υe}+υµ (due to osc.) ν e :ν µ :ντ =1:1:1 ν Detectors for High Energy Astrophysical Neutrinos!

Antares 0.2x0.2x0.4km Volume: 0.01 km3 Running since May 2008

South pole Volume:1 km3 NT200+ Construction finished in Dec.2010 Lake Bikal 0.2 kmφ 0.2 kmh Volume: 0.01 km3 Running from 2006 Diffuse ν limit Now below the Waxman-Bahcall limit IceCube Preliminary

νµ only Atmospheric ν

This work

From S.Yoshida Sean Grullon (UW-Madison) GZK ν search Systematic errors included All flavor (νe + νµ + ντ) limits IceCube Preliminary

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- 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 supernova Mirizzi, Raffelt and Serpico, JCAP 0605,012(2006), astro-ph/0604300 Based on birth location of neutron stars

Core collapse type mean: 10.7 kpc r.m.s.: 4.9 kpc Type Ia

0 10kpc 20kpc

7% probability 16% probability 3% probability < 3.16 kpc < 5 kpc > 20 kpc > x10 statistics > x 4 statistics < 1/4 statistics Super-K: Angular distribution (without Gd)

Without ν p ν+e e ν+e identification by neutron tagging νe+p

νe+p

ν+e ν+e

νe+p νe+p SN at 10kpc Accuracy of supernova direction with neutron tag Thomas, Sekikoz, Raffelt, Kachelriess, Dighe, hep-ph/0307050v2 Accuracy of SN direction with Tagging efficiency vs. 40000 simulated supernova accuracy (95% CL)

G: Garching model, L: Livermore model Accuracy can be improved by a factor 2 -3 a: normal hierarchy sin θ13>10 of two with neutron tagging. 2 -3 b: inv. hierarchy sin θ13>10 2 -3 c: any hierarchy sin θ13<10 + Angular distribution of νｅ＋ｐ→ｅ +n

+ νｅ＋ｐ→ｅ ＋ n

5MeV 10MeV neutrino energy! 20MeV 30MeV

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

COSθSN! - Super-K: Neutronization burst (e +pàn+νe) SN at 10kpc Neutrino flux and spectrum from Livermore simulation

Event rate of νe+p events

Event rate of neutronization burst (forward peaked ν+e scattering events) No oscillation

Normal PH=1 or Inverted hierarchy

Normal hierarchy PH=0

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

Number of events from neutronization burst is 0.9~6 events for SN@10kpc.

νep events during this 10msec is about 8 - 30 events. N.H. +adiamacitc case: neutronization=0.9ev., νep = 14 ev.(1.4 for SN direction).

ν+p elastic signal（ ν+p→ ν+p） at liq. Scintillator detectors Beacom, Farr, and Vogel, PRD66, 033001(2002) Sensitivity of temperature Expected spectrum measurement

νe Solid: sum of all νe

Determine original temperature ~300 events/kt above 200keV νµ, νµ, ντ, ντ with ~10% accuracy. ~150 events/kt above 500keV (free from neutrino oscillation.） Current Borexino threshold: 200keV Current KamLAND threshold: 600~700keV(will be lowered after 2008 distillation.)