Neutrino hierarchy determination from a galactic supernova burst
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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 energies at infinity 1 second time slice of 10 second burst spectrum
Neutrino energies at infinity burst(1 second time-slice of 10-second burst spectrum?)

H. Duan and A. Friedland, http://arxiv.org/abs/1006.2359


Consider 3 detector possibilities
Consider 3 detector possibilities burst

  • 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


N reaction cross sections
n burst reaction cross-sections

Water

Argon

Dominant reaction:

Dominant reaction:

https://wiki.bnl.gov/dusel/index.php/Event_Rate_Calculations


Normal hierarchy observed spectra accounts for detector acceptance
Normal Hierarchy: Observed Spectra burst(accounts for detector acceptance)

n flux at detector

WC 30% coverage

WC 15% coverage

Liquid Ar


Inverted hierarchy observed spectra accounts for detector acceptance
Inverted Hierarchy: Observed Spectra burst(accounts for detector acceptance)

n flux at detector

WC 30% coverage

WC 15% coverage

Liquid Ar


How many events are needed to distinguish normal from inverted hierarchy in water
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


How many events for 3 sigma exclusion
How many events for 3 sigma exclusion? inverted hierarchy in water?

  • 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


C 2 vs events wc 30 coverage
c inverted hierarchy in water?2 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


C 2 vs events wc 15 coverage
c inverted hierarchy in water?2 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


How many events are needed to distinguish normal from inverted hierarchy in argon
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


C 2 vs events liquid argon
c inverted hierarchy in argon?2 vs. events, liquid argon

Normal fit

Inverted fit

Normal

hierarchy

Inverted

hierarchy

~102.7-2.8 = 500-630 events are needed


Normal and inverted hierarchy neutrino spectra for 99 7 confidence
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


Summary
Summary confidence.

  • 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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