Detection of supernova Neutrinos

Transcription

1 Supernovae Conference, Kyoto, October 3, 3 Detection of supernova Neutrinos M.Nakahata Kamioka observatory ICRR/IPMU, Univ. of Tokyo SN87A

2 Contents Supernova burst neutrinos SN87A 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)?

3 Neutrino emission from core collapse supernova Released gravitational energy: ~3x 53 erg Neutrinos carry almost all (%) of the energy. So, neutrino detection is important to investigate energy flow of the core collapse. Expected time profile Livermore simulation (often used for signal estimation for neutrino detectors) (x=m,t) Mean neutrino energy (x=m,t) T.Totani, K.Sato, H.E.Dalhed and J.R.Wilson, ApJ.46,6(8)

4 SN87A: supernova at LMC(5kpc) Kamiokande-II IMB-3 BAKSAN Feb.3, 87 at 7:35UT Kam-II ( evts.) IMB-3 (8 evts.) Baksan (5 evts.) 4 events total Interpreting SN 87A Neutrinos Jegerlehner, Neubig & Raffelt, PRD 54 (6) 4

5 History of supernova detectors BAKSAN (33t liq.sci.) IMB (7t water) LVD (33 t liq. sci.) Super-Kamiokande (3t water) Amanda/IceCube Borexino(3t liq.sci.) SN87a Kamiokande (4t water) SNO (t D O) KamLAND(t liq.sci.) LSD(t liq. sci.) HALO (76t Pb, 3 He counter) 5

6 Supernova burst detectors in the world (running and near future experiments) Borexino LVD Super-Kamiokande Baksan SNO+ (under construction) HALO KamLAND IceCube

7 The Baksan underground scintillation telescope (Russia) Each detector Total number of standard detectors..35 Total target mass tons of oil-based scintillator ~ n e p e + n events expected for kpc SN. Running since 8 with ~% live time. From E.N.Alexeyev, A. Gaponenko E.N.Alexeyev, L.N.Alexeyeva, astro-ph/4 A. Gaponenko et al., ICRC3, Paper ID: 6 No candidate for 8 years observation time from 8 to 3. Upper limit of SN rate: <.8 /yr

8 LVD detector (at Gran Sasso, Italy) LVD consists of an array of 84 counters,.5 m 3 each. Total target: t liquid scintillator 4MeV threshold With <MeV threshold for delayed signal (neutron tagging efficiency of 5 +- %) E resolution: 3%(s) at 5MeV ~3 n e p e + n events expected for kpc SN. No candidate for.3 years from to 3. Upper limit of SN rate: <. /yr From W.Flugione C.Vigorito et al., ICRC3, Paper ID: 453

9 Single volume liquid scintillator detectors KamLAND Borexino SNO+ (Kamioka, Japan) (Gran Sasso, Italy) (SNO Lab.,Canada) 3ton liq.sci. Running since 7. ton liq.sci. Running since. ton liq.sci. Under construction. From K.Inoue, G.Bellini, M.Chen

10 Liquid scinitillator detectors Expected number of events(for kpc SN) Events/ tons Inverse beta( n e +p e + +n) : ~3 events Spectrum measurement with good energy resolution, e.g. for spectrum distortion of earth matter effect. CC on C (n e + C e+ N( B)) : Tagged by N( B) beta decay Electron scattering (n+e - n+e - ) : NC g from C (n+ C n+ C+g): Total neutrino flux, 5.MeV mono-energetic gamma n+p scattering( n+p n+p): Sensitive to all types of neutrinos. (Independent from neutrino oscillation) Spectrum measurement of higher energy component. ~3 events ~ events ~6 events ~3 events From K.Inoue, G.Bellini, M.Chen

11 HALO (SNOLAB, Canada) SNO 3 He neutron detectors with lead target CC: NC: HALO is using 76 tonnes of Pb For a kpc, Assuming FD distribution with T=8 MeV for n μ s, n τ s. 68 neutrons through n e charged current channels neutrons through ν x neutral current channels ~ 88 neutrons liberated; with ~5% of detection efficiency, ~4 events expected. From C.Virtue

12 IceCube (South pole) IceTop Design Specifications InIce AMANDA Fully digital detector concept Number of strings 75 Number of surface tanks 6 Number of Optical modules (DOMs) 48 Instrumented volume km 3 Supernova neutrinos coherently increase single rates of PMTs. From L.Koepke, S.Yoshida Running with full detector configuration since Dec.,.

13 IceCube signal kpc to SN Simulation based on Livermore model Advantage: high statistics (.75% stat. and ms bins) Good for fine time structures (noise low)! Disadvantage: no pointing no energy intrinsic noise Galactic Center IceCube Amanda LMC SMC Significance: Galactic center: ~ s LMC : ~5 s SMC : ~4 s From L.Koepke

14 T.Lund et al., Phys. Rev. D8, 637(). High frequency signal variation by SASI SASI=standing accretion shock instability luminosity -D(axially symmetric) simulation with PROMETHEUS-VERTEX code Supernova at kpc IceCube event rate energy

15 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.46,6(8)) 3kton water Cherenkov ~7,3 n e +p events ~3 n+e events ~36 6 O NC g events ~ 6 O CC events (with 5MeV thr.) for kpc supernova

16 Model dependence of Super-K prediction Livermore simulation T.Totani, K.Sato, H.E.Dalhed and J.R.Wilson, ApJ.46,6(8) Nakazato et al. K.Nakazato, K.Sumiyoshi, H.Suzuki, T.Totani, H.Umeda, and S.Yamada, ApJ.Suppl. 5 (3), (M sun, trev=msec, z=. case) Total number of events Ethr=3.5MeV(kin) Number of events comparison Livermore Nakazato n e +p 73 3 n+e O CC 57 for kpc supernova 3kton SK volume 4.5MeV(kin) threshold without n oscillation Factor of ~ difference

17 Summary of current supernova n detectors # of events expected for kpc. Directionality Baksan (8-) LVD (-) Super-K (6-) KamLAND (-) ICECUBE (5-) BOREXINO (7-) HALO (-) 33 ton liquid scintillator ~ n e p e + n events. ton liquid scintillator. 84 counters.5m 3 each. 4 MeV thres., ~5% eff. for tagging decayed signal. ~3 n e p e + n events. 3, tons of water target. ~73 n e p e + n, ~3 ne ne scattering events. ton liquid scintillator, single volume. ~3 n e p, several CC on C, ~6 NC g, ~3 np np Gigaton ice target. By coherent increase of PMT single rates. High precision time structure measurement. 3 ton liquid scintillator, single volume. ~ n e p, ~ CC on C, ~ NC g, ~ np np SNO 3 He neutron detectors with 76 ton lead target. ~4 events expected. No No Yes No No No No

18 Super-K: simulation of angular distribution n+e n+e SN at kpc ne+p ne+p n+e n+e ne+p ne+p Direction of supernova can be determined with an accuracy of ~5 degree. Neutrino flux and spectrum from Livermore simulation

19 Supernova Relic Neutrinos SRN flux from Horiuchi et al. PRD, 7, 833 () SRN predictions (n e fluxes) Expected SRN events events/year/.5kt (-3MeV) SK fiducial volume Large target mass and high background reduction are necessary.

20 Captures on Gd Identify n e p events by neutron tagging with Gadolinium. Gadolinium has large neutron capture cross section and emit 8MeV gamma cascade. n e GADZOOKS! project at Super-K p e + n Gd γ % 8%.% Gd gives ~% efficiency for n capture In Super-K this means ~ tons of water soluble Gd (SO 4 ) 3 8 MeV ΔT~μs Vertices within 5cm 6% 4% % %.%.%.%.% % Gd in Water

21 Expected SRN signal and background at Super-K 33~45 ev. 6~34 ev. Expect number of events in years in E total =-3 MeV Assuming Capture efficiency of % and Gd gamma detection efficiency of 74%. 3~6 ev. ~6 ev. Invisible muon B.G. is 35% of the SK-IV invisible muon BG. Min/nominal/Max are due to uncertainties in astronomy. Background: ~8 ev. SRN flux from Horiuchi et al. PRD, 7, 833 ()

22 EGADS Evaluating Gadolinium s Action on Detector Systems m 3 tank with 4 PMTs Transparency measurement (UDEAL) 5m 3 tank to dissolve Gd Gd water circulation system (purify water with Gd)

23 Cherenkov Light Left(%) Transparency of Gd-loaded water (before mounting PMTs) The light left at 5 m in the m 3 tank (stainless steel) was ~6% for.% Gd (SO 4 ) 3, which corresponds to ~84% of pure water.

24 4 PMTs were mounted in the m 3 tank in this summer. Pure water circulation was started. Gd-loaded test is expected start soon.

25 Super-K: Angular distribution (without Gd) ne+p n+e n+e Without n e p identification by neutron tagging ne+p n+e n+e ne+p ne+p SN at kpc

26 Super-K: Angular distribution (with Gd) ne+p n+e ne+p n+e With n e p identification by neutron tagging ne+p n+e ne+p n+e Direction accuracy can be improved to ~3 degree. SN at kpc

27 Future Large Volume Detectors Hyper-Kamiokande (.74 Mton Water Cherenkov) LBNE (US) ( 34 kton Liq. Ar detector) LBNO (Europe) (kton Liq. Ar, 5kton Liq. scintillator) JUNO(China) (kton Liq. Sci.) RENO-5(Korea) (8kton Liq. Sci.)

28 Supernova events at Hyper-Kamiokande ~, n e +p events 7,~8 n+e events (-) ~, n e + 6 O events for kpc supernova 3~5 events even for M3 supernova Each band covers, no osc., N.H. and I.H. cases

29 Hyper-K: Neutronization burst Neutrino flux and spectrum from Livermore simulation (e - +p n+n e ) SN at kpc Event rate of n e +p events Event rate of neutronization burst (forward peaked n+e scattering events) No oscillation Normal P H = or Inverted hierarchy Normal hierarchy P H = P H : crossing probability at H resonance (P H =: adiabatic) Number of events from neutronization burst is ~3 events for SN@kpc. n e p events during this msec is about - events. N.H. +adiamacitc case: neutronization=~ev., n e p = ~35 ev.(~35 for SN direction).

30 SASI Detection Perspective I. Tamborra (TAUP3) Their 3D 7 M SUN progenitor shows pronounced SASI. SASI sinusoidal modulation of the neutrino signal will be detectable by IceCube and Hyper-K. I.Tamborra et al., arxiv:37.736

31 Expected signal in Liquid Ar For 34 kton Liq. Ar kpc Interactions, as a function of neutrino energy Channel No of events (observed), GKVM, 34 kton Nue-Ar Nuebar- Ar ES 78 6 Total No. of events (observed), Livermore Dominated by n e From K. Scholberg

32 If Betelgeuse explodes Image credits: Haubois / Perrin (LESIA, Paris Observatory) Betelgeuse shrank by 5% in 5 years. (cf. ApJ 67, L7) It may explode tomorrow or 5, years from now. (from Nomoto-san) It is only ~64 light-years (.kpc) from us.

33 Event Rate [Hz] New electronics for Betelgeuse at Super-K If Betelgeuse explodes, #events@sk: > 3M / s Max. event rate: > 3MHz Current DAQ Handles up to 6M events/s Records only first % Bottleneck: disk access speed time [s] Data flow to the new electronics Front-end electronics The new electronics will record sum of PMT hits with 6kHz continuously, and 6MHz data for ~ minute around the burst.

34 6 /cm /s/mev) Thermal Neutrinos during Si burning phase A.Odrzywolek, M.Misiaszek, M.Kutschera, AIP Conf. Proc. 44, (7) Neutrino-cooled stage of the 5 x M sun star ν e spectrum 48, 4,, 6 and 3 hours before core collapse. In case of Betelgeuse This means only neutron signals in n e +p interactions MeV In this paper, distance is assumed to be.3kpc. So, the numbers must be reduced to 5%. Neutrinos during the Si-burning phase can be used for precursor of core collapse.

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