Supernova Neutrinos Supernova Neutrino Detection!

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1 Supernova Neutrinos Supernova Neutrino Detection! Kate Scholberg, Duke University JINA-CEE International Symposium on Neutron Stars in the Multi-Messenger Era Athens, Ohio, May 2016

2 e e µ µ l Three flavors (families) NEUTRINOS l Tiny masses (< 1 ev) and oscillations (flavor change) l Interact only via weak interaction (& gravity) neutral partners to the charged leptons Chargedand neutral-current weak interactions Neutrinos bring information from deep inside dense objects... but they require heroic efforts to detect

3 Jargon alert! In particle physics, an event is not this... ~ ergs It s an individual recorded neutrino interaction: few times 10-5 ergs e.g., the IMB neutrino detector saw 8 events from 1987A (...58 orders of magnitude difference in energy...)

4 Neutrinos from core collapse When a star's core collapses, ~99% of the gravitational binding energy of the proto-nstar goes into ν's of all flavors with ~tens-of-mev energies (Energy can escape via ν's) Mostly ν-ν pairs from proto-nstar cooling Timescale: prompt after core collapse, overall Δt~10 s of seconds quasi-thermal spectrum expected ( pinched Fermi-Dirac)

5 Expected neutrino luminosity and average energy vs time Vast information in the flavor-energy-time profile neutronization burst Fischer et al., Astron.Astrophys. 517 (2010). arxiv: : Basel model Early: deleptonization Mid: accretion Late: cooling neutrino trapping infall SASI, explosion cooling on diffusion timescale Generic feature: (may or may not be robust) he e i < he e i < he x i

6 SN1987A in LMC ν's seen ~2.5 hours before first light ν e Confirmed baseline model... but still many questions

7 What can we learn from the next neutrino burst? CORE COLLAPSE PHYSICS explosion mechanism proto nstar cooling, quark matter black hole formation accretion, SASI nucleosynthesis from flavor, energy, time structure of burst... ν absolute mass (not competitive) ν mixing from spectra: flavor conversion in SN/Earth input from photon (GW) observations + EARLY ALERT input from neutrino experiments NEUTRINO and OTHER PARTICLE PHYSICS (mass hierarchy) other ν properties: sterile ν's, magnetic moment,... axions, extra dimensions, FCNC,...

8 Reminder on Neutrino Interactions with Matter Neutrinos are aloof but not completely unsociable Charged Current (CC) d u Neutral Current (NC) d d W + ν l l - Z0 ν l + N l ± + N' ν x ν x Produces lepton with flavor corresponding to neutrino flavor Flavor-blind (must have enough energy to make lepton)

9 Supernova-relevant neutrino interactions Electrons! Charged current! Neutral current! Elastic scattering + e! + e ν e e - ν e - Useful for pointing

10 Supernova-relevant neutrino interactions Charged current! Neutral current! Electrons! Protons! Elastic scattering Inverse beta decay + e! + e e + p! e + + n γ ν e e - ν e - Useful for pointing ν e ν e + n γ Elastic scattering very low energy recoils p γ

11 Supernova-relevant neutrino interactions Electrons! Protons! Nuclei! Charged current! Neutral current! Elastic scattering Inverse beta decay + e! + e e + p! e + + n γ ν e e - ν e - Useful for pointing ν e ν e + n γ Elastic scattering very low energy recoils p γ e +(N,Z)! e +(N 1,Z + 1) e +(N,Z)! e + +(N +1,Z 1) ν e γ n γ + A! + A ν γ n γ + A! + A e +/- Various possible ejecta and deexcitation products ν A Coherent elastic (CEvNS)

12 Supernova-relevant neutrino interactions Electrons! Protons! Nuclei! Charged current! Neutral current! Elastic scattering Inverse beta decay + e! + e e + p! e + + n γ ν e e - ν e - Useful for pointing ν e ν e + n γ Elastic scattering very low energy recoils p γ e +(N,Z)! e +(N 1,Z + 1) e +(N,Z)! e + +(N +1,Z 1) ν e γ n γ + A! + A ν γ n γ + A! + A e +/- Various possible ejecta and deexcitation products ν A Coherent elastic (CEvNS) IBD (electron antineutrinos) dominates for current detectors

13 Information is in the energy, flavor, time structure of the burst What do you want in a detector? Size! Low energy threshold! Energy resolution! Angular resolution! Timing resolution! Low background! Flavor sensitivity! High up-time and longevity! ~kton detector mass per kpc ~Few MeV if possible Resolve features in spectrum Point to the supernova! (for directional interactions) Follow the time evolution BG rate << rate in burst; underground location usually excellent; surface detectors conceivably sensitive Ability to tag flavor components Can t miss a ~1/30 year spectacle! Note that many detectors have a day job...

14 Current main supernova neutrino detector types Water! Scintillator! Argon! Lead! + some others (e.g. DM detectors)

15 Water Cherenkov detectors Inverse Beta Decay (CC) dominates ν e + p e + + n E thr =1.8 MeV Pointing from neutrino-electron elastic scattering G. Raffelt

16 Super-Kamiokande Mozumi, Japan 22.5 kton fid. volume (32 kton total) ~5-10K 10 kpc (mostly anti-νe) ~5o 10 kpc Future: SK-Gd Hyper-Kamiokande 317 kton fiducial volume in two modules* Design & site-selection underway (* was 560 kton, represented in some slides)

17 Supernova signal in a water Cherenkov detector Events seen, as a function of observed energy M. Nakahata IBD (anti ν e ) dominant For 100 kton. 30% PMT 10 kpc Events vs time for SK, for different models

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19 Long string water Cherenkov detectors ~kilometer long strings of PMTs in very clear water or ice (IceCube/PINGU, ANTARES) Nominally multi-gev energy threshold... but, may see burst of low energy ν e 's as coincident increase in single PMT count rates (M eff ~ 0.7 kton/pmt) IceCube collaboration, A&A 535, A109 (2011) Map overall time structure of burst

20 Scintillation detectors Liquid scintillator (C n H 2n ) volume surrounded by photomultipliers - few 100 events/kton (IBD) - low threshold, good energy resolution - little pointing capability (light is ~isotropic) IBD (anti-ν e ) dominant kpc

21 Current and near-future scintillator detectors KamLAND (Japan) 1 kton LVD (Italy) 1 kton NOvA (USA) 14 kton Borexino (Italy) 0.33 kton SNO+ (Canada) 1 kton (on surface, but may be possible to extract counts for known burst)

22 Future detector proposals JUNO (China) 20 kton RENO-50 (S. Korea) 18 kton LENA (Finland) 50 kton

23 Liquid argon time projection chambers fine-grained trackers no Cherenkov threshold high ν e cross section e + 40 Ar! e + 40 K ICARUS (Italy...) 0.6 kton MicroBooNE (USA) 0.2 kton DUNE (USA) 40 kton

24 DUNE/LBNF 40 kt of LAr in 4 modules Cryostat 2 Cryostat 1 Central utility cavern Cryostat 4 Cryostat 3

25 Supernova signal in a liquid argon detector Events seen, as a function of observed energy Electron flavor dominant ~ kpc

26 Example of supernova burst signal in 34 kton of LAr Neutronization burst clearly visible See the ν e light curve! Flux from Huedepohl et al., PRL 104 (2010) ( Garching 10 kpc

27 Can we tag ν e CC interactions in argon using nuclear deexcitation γ s? e + 40 Ar! e + 40 K e - MicroBooNE geometry (LArSoft) 20 MeV ν e, 14.1 MeV e -, simple model based on R. Raghavan, PRD 34 (1986) 2088 Improved modeling based on 40 Ti ( 40 K mirror) β decay measurements in progress Direct measurements (and theory) needed!

28 Lead-based supernova detectors ν e Pb 208 Bi* + e - CC 1n, 2n emission ν x Pb 208 Pb* + ν x NC Relative 1n/2n rates sharply dependent on neutrino energy spectral sensitivity 1n, 2n, γ emission HALO at SNOLAB SNO 3 He counters + 79 tons of Pb: ~ kpc

29 Coherent Elastic Neutrino Nucleus Scattering (CEvNS) νx + A νx + A C. Horowitz et al., PRD68 (2003) High x-scn but very low recoil energy (10's of kev) observable in dark matter detectors 10 kpc L=1052 erg/s per flavor Eavg = (10,14,15) MeV α = (3,3,2.5) for (νe, νe-bar, νx) ~ handful of events per 10 kpc: sensitive to all flavor components of the flux

30 \begin{aside}! γ n ν e γ e +/- Interactions with nuclei (cross sections & products) very poorly understood... sparse theory & experiment (only measurements at better than ~50% level are for 12 C) ) 2 Fluence (neutrinos per 0.2 MeV per cm Solid: SN Broken: stopped π ν e ν e ν x (ν µ +ν µ +ν τ +ν τ ) SNS ν e SNS ν µ SNS ν µ Neutrinos from pion decay at rest have spectrum overlapping with SN ν spectrum, e.g., at ORNL Spallation Neutron Source and far off-axis at the Fermilab BNB Neutrino Energy (MeV) A. Bolozdynya et al., arxiv:

31 Fluence at ~50 m from the stopped pion source amounts to ~ a supernova a day! (or 0.2 microsupernovae per pulse, 60 Hz of pulses) Fluence from Galactic center / 1 R 2 ν e γ γ n e +/- This is an excellent opportunity to study poorly understood neutrino-nucleus interactions in the supernova energy range

32 Currently measuring neutrino-induced neutrons in lead, (iron, copper),... ν e Pb 208 Bi* + e - CC 1n, 2n emission ν x Pb 208 Pb* + ν x NC 1n, 2n, γ emission Likely a non-negligible background to CEvNS, especially in lead shield

33 NIN measurement in SNS basement - Scintillator inside CsI detector lead shield (now) - Liquid scintillator surrounded by lead (swappable for other NIN targets) inside water shield Phil Barbeau \end{aside}!

34 Summary of supernova neutrino detectors Detector Type Location Mass (kton) 10 kpc Status Galactic sensitivity Super-K Water Japan Running (SK IV) LVD Scintillator Italy Running KamLAND Scintillator Japan Running Borexino Scintillator Italy Running IceCube Long string South Pole (600) (10 6 ) Running Baksan Scintillator Russia Running Mini- BooNE Scintillator USA (Running) HALO Lead Canada Running Daya Bay Scintillator China Running NOνA Scintillator USA Turning on SNO+ Scintillator Canada Under construction MicroBooNE Liquid argon USA Under construction Extragalactic DUNE Liquid argon USA Proposed Hyper-K Water Japan ,000 Proposed JUNO Scintillator China Proposed RENO-50 Scintillator South Korea Proposed PINGU Long string South pole (600) (10 6 ) Proposed plus reactor experiments, DM experiments...

35 Example signals in future detectors Neutronization burst in argon (note logarithmic time bins)

36 Distance reach for future detectors SK will see ~1 event from Andromeda; HK will get a ~dozen

37 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 experiment UT time significance Coincidence Server at BNL 10 second coincidence by UT time stamp alert to astronomers - Running smoothly for more than 10 years, automated since 2005

38 SNEWS: SuperNova Early Warning System Daya Bay snews.bnl.gov LVD Super-K HALO IceCube KamLAND Borexino

39 Sociological comments... level of sustained human interest E.A.U. importance of catching every last bit of data Everybody s hungry for data... Need to close the gap! 1/century 10,000/day

40 The neutrinos are coming! Far side of the Milky Way is ~650 light-centuries away ~2000 core collapses have happened already... x (Figure from Sky&Telescope magazine)

41 Neutrinos from Type I supernovae? A dribble, but could get some useful info for a nearby one with next-generation detectors shaded: before detector smearing W. Wright et al., arxiv: D delayed-detonation explosion model

42 Summary Vast information to be had from a core-collapse burst! - Need energy, flavor, time structure Current & near future detectors: - ~Galactic sensitivity (SK reaches barely to Andromeda) - sensitive mainly to the ν e component of the SN flux - excellent timing from IceCube - early alert network is waiting! - we need to measure some x-scns Farther future megadetectors - huge statistics: extragalactic reach - richer flavor sensitivity (e.g. ν e in LAr) - multimessenger prospects