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Gravitational-wave Physics&Astronomy Workshop, January 28, 2011 . M.Nakahata. Neutrino observatories. Kamioka observatory ICRR/IPMU, Univ. of Tokyo. SN1987A. Contents. Supernova burst neutrinos How they are produced SN1987A Current detectors in the world
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Gravitational-wave Physics&Astronomy Workshop, January 28, 2011 M.Nakahata Neutrino observatories Kamioka observatory ICRR/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
Neutron star Core-collapse supernova Standard scenario of the core-collapse supernova Core-collapse Neutrino trapping Core bounce C+O He Si n n H Fe n n n n n Supernova burst Shock wave propagation Shock wave at core n n n n n Figure from K.Sato
Neutrino emission from supernova burst Released gravitational energy: ~3x1053erg Neutrinos carry almost all (99%) of the energy. Energy for explosion and optical emission is only ~1%(~1051erg). Expected time profile (x=m,t) Livermore simulation 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) 95 % CL Contours 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 Total Binding Energy Theory _ Spectral neTemperature from G.Raffelt
Supernova burst detectors in the world (running and near future experiments) Super-Kamiokande Borexino Baksan LVD SNO+ KamLAND (under construction) HALO IceCube
The Baksan underground scintillation telescope (Russia) Total number of standard detectors…………..3150 Total target mass…………………….…...330 tons of oil-based scintillator E.N.Alexeyev, L.N.Alexeyeva, astro-ph/0212499 • ~100 nepe+nevents 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<1MeVthreshold for delayed signal (neutron tagging efficiency of 50 +- 10 %) E resolution: 13%(1s) at 15MeV • ~300 nepe+nevents expected for 10 kpc SN. At Gran Sasso Lab., Italy From W.Flugione
Single volume liquid scintillator detectors KamLAND Borexino SNO+ (Kamioka, Japan) (Gran Sasso, Italy) (SNO Lab.,Canada) • 300ton liq.sci. • Running since 2007. 1000ton liq.sci. 1000ton liq.sci. Running since 2002. Under construction. From K.Inoue, G.Bellini, M.Chen
Liquid scinitillator detectors Expected number of events(for 10kpc SN) • Inverse beta( ne+p→e++n) : ~300 events Spectrum measurement with good energy resolution, e.g. for spectrum distortion of earth matter effect. • CC on 12C (ne+12C→e+12N(12B)) : ~30 events Tagged by 12N(12B) beta decay • Electron scattering (n+e-→ n+e-) : ~20 events • NC gfrom 12C (n+12C→n+12C+g):~60 events 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. Events/1000 tons From K.Inoue, G.Bellini, M.Chen
CC: NC: HALO - a Helium and Lead Observatory (SNO Lab., Canada) SNO 3He neutron detectors with lead target HALO-1is using an available 76 tonnes of Pb • 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 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 • Number of Optical modules (DOMs) – 4820 • Instrumented volume – 1 km3 1450m InIce AMANDA Supernova neutrinos coherently increase single rates of PMTs. 2450m Construction finished on Dec.18, 2010. From L.Koepke, S.Yoshida
IceCube as MeV detector • 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 10 kpc to SN Simulation based on Livermore model Significance: Galactic center: ~200 s LMC : ~5 s SMC : ~4 s Galactic Center LMC IceCube SMC Amanda From L.Koepke
Super-Kamiokande detector (Kamioka, Japan) • 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 LINAC Electronics hut Water and air purification system Control room Atotsu entrance ID 41.4m OD 1km (2700mwe) Ikeno-yama Kamioka-cho, Gifu Japan 3km 2km SK Mozumi Atotsu 39.3m
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 ne+p events ~300 n+eevents ~360 16O NC g events ~100 16O CC events (with 5MeV thr.) for 10 kpcsupernova
Summary of current supernova n detectors # of events expected for 10kpc. Directionality
Super-Kamiokande: Water Cherenkov detector Cherenkov lightEmitted when particle travels faster than speed of light in water(c/1.33). e q Emission angle = cos-1(1/nb)=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 νe+p→e++n νe+16O→e++16N Cross section (H2O target) Angular distribution ν+e-→ν+e- Supernova n νe+16O→e-+16F COSqSN Neutrino
Super-K: simulation of angular distribution ne+p ne+p ne+p ne+p n+e SN at 10kpc n+e n+e n+e Direction of supernova can be determined with an accuracy of ~5 degree. Neutrino flux and spectrum from Livermore simulation
Future possible improvement in Super-K 100% 80% 60% 40% 20% 0% Captures on Gd 0.1% Gd gives>90% efficiencyfor n capture In Super-K this means ~100 tons of water solubleGdCl3 or Gd2(SO4)3 • Identify nep events by neutron tagging with Gadolinium. • Gadolinium has large neutron capture cross section and emit 8MeV gamma cascade. ne n p Gd + e γ 8 MeV ΔT~20μs Vertices within 50cm The main purpose of this project is to detect diffuse supernova neutrinos. 0.0001% 0.001% 0.01% 0.1% 1% Gd in Water
Super-K: Angular distribution (with Gd) ne+p ne+p ne+p ne+p With nepidentification by neutron tagging n+e n+e n+e Direction accuracy can be improved to ~3 degree. n+e 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) cos = t / d d = 38 msec q IceCube (90˚S) If Super-K and IceCube has ~2 msec rise time resolution, cos() = ~0.1 (i.e. about 25 deg.). Super-K resolution by electron-scattering is much better.
SuperNova Early Warning System snews.bnl.gov arXiv:0803.0531 Details: arXiv:astro-ph/0406214 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 Volume Detector (Italy) Super- Kamiokande (Japan) IceCube (South Pole) SNO (Canada) until end of 2006 From K. Scholberg
High Energy Astrophysical Neutrinos There are high energy accelerators in the universe. We know cosmic rays(p, He, ..) exist. So, there much be cosmic high energy neutrinos. e e+ Possible sources: AGN, supernova remnants, …. + + sync p sync e- Black hole accretion disk
Cosmic Ultra High Energy neutrinos galactic Extra- galactic Neutrinos Ultra High Energy Cosmic Ray(UHECR) exists. “Horizon” of UHECR is ~50Mpc. GZK neutrinos cosmic rays interact with the microwave background (due to n osc.)
Detectors for High Energy Astrophysical Neutrinos Antares • Mediterranean sea • 0.2x0.2x0.4km • Volume: 0.01 km3 • Running since May 2008 • South pole • Volume:1 km3 • Construction finished in Dec.2010 NT200+ • Lake Bikal • 0.2 kmf 0.2 kmh • Volume: 0.01 km3 • Running from 2006
Diffuse n limit Now below the Waxman-Bahcall limit IceCube Preliminary nmonly Atmospheric n This work From S.Yoshida Sean Grullon (UW-Madison)
GZK n search All flavor (ne + nm + nt) limits Systematic errors included 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-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.
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 < 3.16 kpc > x10 statistics 16% probability < 5 kpc > x 4 statistics 3% probability > 20 kpc < 1/4 statistics
Super-K: Angular distribution (without Gd) ne+p ne+p ne+p ne+p Without nepidentification by neutron tagging n+e n+e n+e n+e SN at 10kpc
Accuracy of supernova direction with neutron tag Thomas, Sekikoz, Raffelt, Kachelriess, Dighe, hep-ph/0307050v2 Accuracy of SN direction with 40000 simulated supernova Tagging efficiency vs. accuracy (95% CL) G: Garching model, L: Livermore model a: normal hierarchy sin2q13>10-3 b: inv. hierarchy sin2q13>10-3 c: any hierarchy sin2q13<10-3 Accuracy can be improved by a factor of two with neutron tagging.
Angular distribution of νe+p→e++n νe+p→e++ n 5MeV 10MeV 20MeV 30MeV neutrino energy A. Strumia and F. Vissani, Phys.Lett.B564:42-54,2003. COSqSN
Super-K: Neutronizationburst (e-+pn+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 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. 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).
n+p elastic signal( n+p→ n+p) at liq. Scintillator detectors nmnmntnt Solid: sum of all ne ne Beacom, Farr, and Vogel, PRD66, 033001(2002) Sensitivity of temperature measurement Expected spectrum Determine original nm, nm, nt, nttemperature with ~10% accuracy. (free from neutrino oscillation.) ~300 events/ktabove 200keV ~150 events/ktabove 500keV Current Borexino threshold: 200keV Current KamLAND threshold: 600~700keV(will be lowered after 2008 distillation.)