Prospect for detection of supernova neutrino

1. Prospect for detection of supernova neutrino NOW2014 Sep. 9th, 2014 Otranto, Lecce, Italy 森俊彰Takaaki Mori for the Super-Kamiokande Collaboration Okayama University, Japan

2. Contents Supernova burst neutrinos Supernova relic neutrinos GADZOOKS! Pre-supernova neutrinos

3. Neutrino from supernova • A supernova explosion happens when a star at least 8 times more massive than the sun collapses. • Released gravitational energy: ~3x1053 erg. Neutrinos carry almost all (99%) of the energy. • Supernova neutrinos detection provides a lot of information • Collapse physics • Neutrino Physics • Detection of SN neutrino is very important Luminosity Average E Livermore simulation: APJ, 496, 216 (1998)

4. Supernova burst detectors in the world (running and near future underground experiments) Borexino LVD Baksan Super-K SNO+ (under construction) HALO KamLAND Detectors on surface like NOvA (14kton liquid scintillator(LS)), Daya Bay (160ton Gd-doped LS) can also be supernova detectors. IceCube

5. Super-Kamiokande • 32 kton water Cherenkov detector • Dominant interaction is IBD (ne+p)( ~7300 events in total ~8000 events for 10kpc SN) • Enough statistics to discuss model predictions • Good directionality for ne scattering (~300 events) • SN monitor is running 24 hours a day • Announce the SN neutrino detection and its direction to the world within an hour

6. IceCube • ~kilometer long strings of PMTs in clear ice • Although multi-GeV energy threshold, may see burst as coincident increase in single PMT count rate • Cannot tag flavor, or other event-by-event info, but map overall burst time structure • High statistics • 0.75% stat. error @ 0.5 sec and 100 ms bins [sec] From L.Koepke

7. Liquid scintillator detectors Expected number of events for 10 kpc SN • Inverse beta : ~300 events/kton • Spectrum measurement with good energy resolution • CC on 12C : ~ 30 events/kton • Electron scattering : ~20 events/kton • NC g from 12C : ~60 events/kton • Total neutrino flux, 15.11 MeV mono energetic g • n + p NC : ~ 300 events/kton • Sensitive to all types of neutrinos ( Independent from neutrino osc.) Spectrum @KamLAND (Flux:PRD67,023004 (2003)) From K.Inoue, G.Belliini, M.Chen

8. Supernova Relic Neutrino

9. Supernova Relic Neutrino • In the Universe, there exist SRN emitted from the past supernovae explosion Time SRNmode : PRD, 79, 083013 (2009) SRN predictions (ne fluxes) Neutrino flux (/cm2/sec/MeV) Neutrino Energy[ MeV] • Expected SRN events : 1.3~6.7 events/year/22.5kton ( 10-30 MeV ) • Large target mass and high background reduction are necessary

10. SRN search at Super-K K.Bays et al.,PRD85(2012) • Super-K has the best sensitivity to the SRN via IBD interaction • flux<2.9 ne (1/cm2/sec) ne neutron proton proton g data νμ CC νe CC NC elastic μ/π > C. thr. all background SRN e+ 2.2 MeV g(Not efficiently detected) • Search for SRN is limited by background • Need to identify neutron to suppress the atmospheric neutrino background Energy [MeV] 50 75 25

11. GADZOOKS! Beacom and Vagins PRL93,171101 (2004)(Gadolinium Antineutrino Detector Zealously Outperforming Old Kamiokande, Super!) neutron • Large cross section for thermal neutron (~ 90% @ 0.1 % Gd) • Neutron captured Gd emits 3-4g ray in total 8 MeV proton ne Gd g e+ SRN mode:PRD79,083013(2009)

12. SN n detection w/ neutron tagging Direction of SN can be determined with an accuracy of ~ 5 deg. ->By neutron tagging, direction accuracy can be improved to ~3 deg. SN @ 10 kpc Flux and spectrum : Livermore simulation

13. EGADS experiment(Evaluating Gadolinium’s Action on Detector System) • Item to study with EGADS • Effect to Water transparency • Water purification system • Neutron detection efficiency • Etc.

14. UDEAL (Water Transparency measurement device) 15 m3 tank and pre-treatment system 200 m3 detector (240 photo sensor) “Selective filtration system” (Water purification system)

15. Current status of EGADS ←achieve same level pure water transparency ←achieve 86.2% of pure water cases

16. Current status of EGADS

17. Current status of EGADS

18. Current status of EGADS ←we found bad material, which is not used in SK detector

19. Current status of EGADS

20. Transparency of Gd-doped water w/o PMT 90 85 80 Cherenkov light left ( %) 75 70 65 60

21. Measurement of Gd g Delayed signal Gd g Am/Be Promptsignal Scintillation 241Am → 237Np + a 9Be + a→ 12C + g(4.4MeV)+ n Gate：500msec BGO Gd2(SO4)3 concentration: 200 ppm Events / # of prompt trg. Events / # of prompt trg. DT[ms] Total electron Energy[MeV]

22. Pre-supernova neutrino detection

23. Pre-supernova neutrinos ACTA PHYSICAL POLONOCA B 40, 3063 (2009) Neutrino is emitted in Si burning phase before core-collapse supernova Shock breakout Shell Si starts • Importance of detection • Investigation of mechanism of evolution of star at final at stage and collapse • Alarm before the SN neutrino burst Direct pre-collapse stage Core Si burning Log Ln [erg/s] SN neutrino burst • Target • Antares (~170pc) • Betelgeuse (~150pc) • Gamma Velorum (~340pc)

24. Pre-SN neutrino detection @ KamLAND Expected number of events @KamLAND Flux@1pc(106/cm2/s/MeV) Time[day] Significance Normal hierarchy Anti ne energy [ MeV ] Inverted hierarchy The early alarm will be issued from 3 days to 5 hours before from core-collapse From K.Ishidoshiro

25. Pre-SN neutrino detection by GADZOOKS! • In case of Betelgeuse assuming distance is 0.13 kpc Betelgeuse@GADZOOKS! Reactor + spallation A.Odrzywolek et al., AIP Conf. Proc. 944, 109 (2007) # of only neutron signals in IBD interaction Like KamLAND, SK(GADZOOKS) will try for a very early alarm

26. Summary Supernova burst neutrinos • SN neutrino provides a lot of information by energy, flavor, timing.. • Many detectors are waiting a SN burst Supernova relic neutrinos • R&D project for GADZOOKS! is ongoing Supernova neutrino at Si burning stage • Its detection provide the very early alarm for supernova burst • KamLAND and GADZOOKS! can get precursor

27. backup

30. Supernova Relic Neutrinos S.Ando, Astrophys.J.607:20-31,2004. ~1017 supernovae so far. S.Ando, NNN05

32. SNEWS: SuperNova Early Warning System Daya Bay (soon) snews.bnl.gov LVD Super-K KamLAND IceCube Borexino

33. Supernova burst detectors in the world (running and near future underground experiments) HALO Borexino Super-Kamiokande SNO+ (under construction) Baksan LVD KamLAND Detectors on surface like NOvA (14kton liquid scintillator(LS)), Daya Bay (160ton Gd-doped LS) can also be supernova detectors. IceCube

34. Current Liquid scintillator detectors Borexino (0.33kton) SNO+ (1kton) under construction KamLAND (1kton) LVD (1kton) NOnA (14kton)

35. SNEWS: SuperNova Early Warning System - Neutrinos (and GW) precede em radiation by hours or even days - For promptness, require coincidence to suppress false alerts snews.bnl.gov Coincidence Server at BNL alert to astronomers experiment UT time significance 10 second coincidence by UT time stamp - Running smoothly for more than 10 years, automated since 2005 - Amateur astronomer connection

39. UDEAL

40. Pre-treat system

42. Gd removal system

43. v

44. Supernova burst detectors in the world (running and near future underground experiments) Borexino LVD Baksan Super-K SNO+ 1 ktonliq.sci. ~ 300 ev. 0.3ktonliq.sci. ~ 100 ev. 0.33 ktonliq.sci. ~ 100 ev. 32 kton water ~ 8000 ev. Good directionality 1 ktonliq.sci. ~ 300 ev. (under construction) HALO KamLAND 76 ton Pb, 3He counter ~ 40 ev. 1 ktonliq.sci. ~ 300 ev. Giant ice IceCube # of expected ev. for 10 kpc

46. Pre-supernova neutrino