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Neutrino hierarchy determination from a galactic supernova burst

Neutrino hierarchy determination from a galactic supernova burst. David Webber August 20, 2010. Neutrino energies at infinity (1 second time-slice of 10-second burst spectrum?). H. Duan and A. Friedland , http://arxiv.org/abs/1006.2359. Consider 3 detector possibilities.

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Neutrino hierarchy determination from a galactic supernova burst

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  1. Neutrino hierarchy determination from a galactic supernova burst David Webber August 20, 2010

  2. Neutrino energies at infinity(1 second time-slice of 10-second burst spectrum?) H. Duan and A. Friedland, http://arxiv.org/abs/1006.2359

  3. Consider 3 detector possibilities • Water Cherenkov (WC) with 30% phototube coverage and high quantum-efficiency tubes • This is roughly equivalent to Super-K’s coverage • WC, 15% coverage, HQE • Liquid Argon

  4. n reaction cross-sections Water Argon Dominant reaction: Dominant reaction: https://wiki.bnl.gov/dusel/index.php/Event_Rate_Calculations

  5. Normal Hierarchy: Observed Spectra(accounts for detector acceptance) n flux at detector WC 30% coverage WC 15% coverage Liquid Ar

  6. Inverted Hierarchy: Observed Spectra(accounts for detector acceptance) n flux at detector WC 30% coverage WC 15% coverage Liquid Ar

  7. How many events are needed to distinguish normal from inverted hierarchy in water? Normal Hierarchy Inverted Hierarchy 102 events indistinguishable 105 events clearly distinguishable • Water Detector • 30% PMT coverage • HQE tubes • IBD reaction • c2 shown for “wrong” fit

  8. How many events for 3 sigma exclusion? • Note: c2is not the same as Gaussian • “3 sigma” = 99.73% confidence • 99.73% confidence is… • c2/NDF of 1.6 for 57 degrees of freedom • c2/NDF of 1.8 for 34 degrees of freedom

  9. c2 vs. events, WC, 30% coverage Normal fit Inverted fit Normal hierarchy Inverted hierarchy • Water Detector • 30% PMT coverage • HQE tubes • IBD reaction ~103.5-3.6 = 3200-4000 events are needed

  10. c2 vs. events, WC, 15% coverage Normal fit Inverted fit Normal hierarchy Inverted hierarchy • Water Detector • 15% PMT coverage • HQE tubes • IBD reaction ~103.5-3.6 = 3200-4000 events are needed

  11. How many events are needed to distinguish normal from inverted hierarchy in argon? Normal Hierarchy Inverted Hierarchy 102 events indistinguishable 105 events clearly distinguishable • Liquid Argon • c2 shown for “wrong” fit

  12. c2 vs. events, liquid argon Normal fit Inverted fit Normal hierarchy Inverted hierarchy ~102.7-2.8 = 500-630 events are needed

  13. Normal and inverted hierarchy neutrino spectra for 99.7% confidence. Normal Hierarchy Inverted Hierarchy Water Cherenkov 30% PMT coverage 4000 events Liquid Argon 630 events

  14. Summary • WC phototube coverage has little impact on resolving the hierarchy. • 15% is as good as 30% • To resolve the hierarchy… • ~4000 events must be observed in water, or • ~630 events must be observed in argon • If a SNB occurs at 8.5 kpc… • Need 18.3 kT water • Need 7.6 kTAr • a 100kT water module would have better statistics than a 17 kTLAr module • The LAr module would show more interesting spectral features This study was based on repository revision 754 Volume estimates based on http://arxiv.org/abs/astro-ph/0701081

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