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Supernova neutrino detection

Supernova neutrino detection. Kate Scholberg, Duke University. Neutrino Champagne 2009. OUTLINE. Neutrinos from supernovae Supernova neutrino detection Inverse beta decay Other CC interactions NC interactions Summary of current and near future detectors

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Supernova neutrino detection

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  1. Supernova neutrino detection Kate Scholberg, Duke University Neutrino Champagne 2009

  2. OUTLINE Neutrinos from supernovae Supernova neutrino detection Inverse beta decay Other CC interactions NC interactions Summary of current and near future detectors Farther future detectors Extra galactic neutrinos Relic neutrinos Pointing to a supernova with neutrinos Summary

  3. Sensitivity to different flavors and ability to tag interactions is key! ne vs ne vs nx What do we want in a SN n detector? - Need ~ 1kton for ~ few 100 interactions for burst at the Galactic center (8.5 kpc away) - Must have bg rate << rate in ~10 sec burst (typically easy for underground detectors, even thinkable at the surface) • Timing • Energy resolution • Pointing Also want: Require NC sensitivity for nm,t , since SN n energies below CC threshold • Flavor sensitivity

  4. Good old CC inverse beta decay , the workhorse of neutrino physics, serves us well for SN neutrino detection: 0.511 MeV g ne + p  e+ + n e+ ne 0.511 MeV n g 2.2 MeV g Inverse Beta Decay (CC) Can often exploit delayed (~180 ms) coincidence of n + p  d + g (or other neutron capture) as tag (also possibly g's from e+ annihilation) In any detector with lots of free protons (e.g. water, scint) this dominates by orders of magnitude

  5. WATER CHERENKOV DETECTORS Volume of clear water viewed by PMTs - few 100 events/kton - typical energy threshold ~ several MeV makes 2.2 MeV neutron tag difficult Super-Kamiokande IV 22.5 kton f.v.: ~8000 inverse beta decay events @ 10 kpc

  6. use gadolinium to capture neutrons for tag of ne ne + p e+ + n Possible enhancement: Gd has a huge n capture cross-section: 49,000 barns, vs 0.3 b for free protons; n + Gd  Gd*  Gd + g Previously used in small scintillator detectors; may be possible for large water detectors with Gd compounds in solution Beacom & Vagins, hep-ph/0309300 R&D is currently underway for SK with half kton test tank in the Kamioka mine

  7. Nominally multi-GeV energy threshold... but, may see burst of low energy ne's as coincident increase in single PMT count rates (Meff~ 0.4 kton/PMT) LONG STRING WATER CHERENKOV DETECTORS ~kilometer long strings of PMTs in very clear water or ice cannot tag flavor, or other interaction info, but gives overall rate and time structure IceCube at the South Pole

  8. Halzen & Raffelt, arXiv:0908.2317 Few ~ms timing may be possible @ 10 kpc w/IceCube

  9. SCINTILLATION DETECTORS Liquid scintillator CnH2n volume surrounded by photomultipliers - few 100 events/kton - low threshold, good neutron tagging possible - little pointing capability (light is ~isotropic) KamLAND (Japan) LVD (Italy) SNO+ (Canada) Borexino (Italy) Mini-BooNE (USA) (+Cherenkov) +Double Chooz, Daya Bay and RENO

  10. NOnA: long baseline oscillation experiment (Ash River, MN) 15 kton scintillator, near surface K. Arms, CIPANP ‘09

  11. For most existing (and planned) large detectors, inverse beta decay dominates, (and is potentially taggable) so primary sensitivity is to ne CC interactions on nuclei play a role, too (cross-sections smaller for bound nucleons) ne + (N,Z)  (N-1, Z+1) + e- ne + n  p + e-: ne + p  n + e+: ne + (N, Z)  (N+1, Z-1) + e+ - charged lepton e+/- - possibly ejected nucleons - possibly de-excitation g's Observables for tagging depends on nucleus Nuclear physics important in understanding cross-sections and observables! ... often large uncertainties, need to measure!

  12. ne + 16O 16N + e+ ne + 12C12N + e- ne + 12C 12B+ e+ Examples of CC interactions of SN n with nuclei: Interactions with oxygen in water ne + 16,18O 16,18F + e- e.g. Super-K, ~few tens @ 8.5 kpc Interactions with carbon in scintillator e.g. LVD, KamLAND, Borexino ~few @ 8.5 kpc

  13. ICARUS: 600 ton LAr ne + 40Ar  e- + 40K* CC Ethr=1.5 MeV _ ne + 40Ar  e- + 40Cl* Ethr=7.48 MeV NC nx + 40Ar nx + 40Ar* Ethr=1.46 MeV ES ne,x + e-ne,x + e- • Tag modes with gamma • spectrum (or lack thereof) • Excellent electron • neutrino sensitivity

  14. HALO at SNOLab nx + 208Pb  208Pb* + nx NC 1n, 2n, g emission Relative rates depend on n energy  spectral sensitivity (oscillation sensitivity) ne + 208Pb 208Bi* + e- CC, Ethr=18 MeV 1n, 2n emission from T. Massicotte thesis SNO 3He counters + 76 tons of Pb: ~85 events @ 10 kpc

  15. ne,x + e-ne,x + e- ne,x e- Also: elastic scattering (CC and NC contributions) Inwater Cherenkov and scintillator, few % of inverse bdk rate POINTING from Cherenkov cone: (degraded by isotropic bg) Super-K: expect few hundred ES for 10 kpc SN  ~ 8o pointing (probably best bet for pointing) Beacom & Vogel, astro-ph/9811359 Tomas et al., hep-ph/0307050

  16. We have sensitivity to electron flavor neutrinos via CC interactions... but ~2/3 of the luminosity is m and t flavor; can be detected via NC interactions only Typically, signature is nucleon emission or nuclear de-excitation products e.g. nx + (A,Z)  (A-1,Z) + n + nx nx + (A,Z)  (A,Z)* + nx sometimes good tag is possible (A,Z) + g Again, nuclear physics matters!

  17. nx + 16O nx +16O* 16O + g's Examples of NC interactions Interactions with oxygen in water K. Langanke et al., nucl-th/9511032 e.g. Super-K, ~few hundreds @ 8.5 kpc Interactions with carbon in scintillator e.g. LVD, KamLAND, Borexino ~few tens @ 8.5 kpc nx + 12 C  nx +12C* 12C + g 15.11 MeV

  18. nx + p nx + p NC neutrino-proton elastic scattering J. Beacom et al., hep-ph/0205220 Recoil energy small, but visible in scintillator (accounting for 'quenching' ) Recoil spectrum in KamLAND Expect ~few 100 events/kton for 8.5 kpc SN

  19. nx + A nx + A Neutrino-nucleus NC elastic scattering in ultra-low energy detectors C. Horowitz et al., astro-ph/0302071 High x-scn but very low recoil energy (10's of keV)  possibly observable in solar pp/DM detectors ~ few events per ton for Galactic SN nx energy information from recoil spectrum e.g. Ar, Ne, Xe, Ge, ... DM detectors, e.g. CLEAN/DEAP Spherical Xe TPC Aune et al.

  20. ne + p  e+ + n Summary of SN neutrino detection channels Inverse beta decay: - dominates for detectors with lots of free p (water, scint) - ne sensitivity; good E resolution; well known x-scn; some tagging, poor pointing CC interactions with nuclei: - lower rates, but still useful, ne tagging useful (e.g. LAr) - cross-sections not always well known Elastic scattering:few % of invbdk, but point! NC interactions with nuclei: - very important for physics, probes m and t flux - some rate in existing detectors, new observatories - some tagging; poor E resolution; x-scns not well known - coherent n-p, n-A scattering in low thresh detectors

  21. Current supernova neutrino detectors Primary sensitivity is to electron antineutrinos via inverse beta decay ne + p e+ + n

  22. SNEWS: Supernova Early Warning System SNO (until 2006) LVD Super-K AMANDA/ IceCube Borexino

  23. Current and near-future supernova neutrino detectors Plus: reactor scint detectors, coherent nA scattering detectors, geochemical

  24. Current best neutrino detectors sensitive out to ~ few 100 kpc.. mostly just the Milky Way 31 per century

  25. singles{ doubles Mton SK Looking beyond: number of sources α D3 S. Ando et al., astro-ph/0503321 With Mton scale detector, probability of detecting 1-2 events reasonably close to ~1 at distances where rate is <~1/year Tagging signal over background becomes the issue ⇒ require double n's or grav wave/optical coincidence

  26. Next generation mega-detectors (10-20 years) 5-100 kton-scale LAr detector concepts DUSEL LBNE 10-100 kton-scale scintillator detector concepts Hyper-K LENA, HanoHano Memphys Megaton-scale water detector concepts

  27. M. Goodman 8B  flux hep  flux SRN window! atm. e flux And going even farther out: we are awash in a sea of 'relic' or diffuse SN n's (DSNB), from ancient SNae Learn about star formation rate, which can constrain cosmological models Difficulty is tagging for decent signal/bg (no burst, 2 n coincidences optical SNae...) C. Lunardini

  28. ne + p  e+ + n In water: M. Nakahata, Neutrino 2008 talk - Worst background is 'invisible muons' below Cherenkov threshold from atmospheric neutrinos →reduce by tagging electron antineutrinos with Gd - But for a big detector requires low energy threshold ($) - LAr is also promising (no Cherenkov threshold)

  29. DSNBGalactic SN ~300 events/kt/30 year ~0.1 event/kt/year ~10 events/kt/yr more backgroundless background risky in the short term, but you win in the very long term low rate of return, but a sure thing bonds vs stocks... (Of course if you build a big detector and run it a long time, you may get both! Diversify!) (But we must remember that no experiment is ‘too big to fail’... )

  30. Summary of supernova neutrino detectors Galactic sensitivity Extragalactic

  31. ne,x + e-ne,x + e- ne,x e- POINTING to the supernova with future detectors (should be prompt if possible) Elastic scattering off electrons is the best bet In water Cherenkov few % of total rate G. Raffelt LBNE WC / Hyper-K / MEMPHYS: <~ 1o pointing Other possibilities: - time triangulation - inv. bdke+n separation - ~TeV neutrinos (delayed) Tomas et al. hep-ph/0307050

  32. Another pointing possibility: (if no WC detector running) Use the matter oscillation energy spectrum to find the pathlength L traveled in the Earth (assume parameters favorable, and well known) KS, A. Burgmeier, R. Wendell arXiv: 0910.3174 For a known pathlength, the supernova will be found on a ring on the sky

  33. Inverse energy spectrum, L=6000 km Power spectra for different L A. S. Dighe, et al. hep-ph/ 0311172 Peak in power spectrum vs L for 500,000 simulated SNae, 60,000 events each (perfect energy resolution)  measure kpeak to find allowed L values

  34. Example skymaps One detector Perfect energy resolution 60,000 neutrino events SN at dec=-60o, RA=20h, 0:00 Finland Two detectors Finland+Hawaii Three detectors Finland+Hawaii+SD

  35. Large statistics and good energy resolution needed! Scintillator-like energy resolution, one detector in Finland

  36. Can improve using relative timing information Two scintillator detectors oscillation: red timing: dark One scintillator detector + IceCube (assume ~ 1 ms timing) oscillation: red timing: dark

  37. Summary Current detectors: - ~Galactic sensitivity (SK reaches barely to Andromeda) - sensitive mainly to the ne component of the SN flux Near future - more flavor sensitivity w/ HALO, Icarus Next generation of detectors: - extragalactic reach + DSNB - richer flavor sensitivity - very good neutrino-based pointing

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