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Unofficial* summary of the Long Baseline Neutrino Experiment (LBNE) physics workshop Seattle, Aug 9 to Aug 11. David Webber August 24, 2010.
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Unofficial* summary of the Long Baseline Neutrino Experiment (LBNE) physics workshopSeattle, Aug 9 to Aug 11 David Webber August 24, 2010 *Many studies/plots are preliminary. These slides are a representation of the workshop’s discussion. An official report is in preparation by the collab.
Why Study Neutrinos? • Neutrinos are half the known stable particles in the universe • n1, n2, n3, p, e, g • Neutrinos are a major component of the universe • ~300 n/cm3, roughly same as CMB photons • nucleons and electrons are ~10-7/cm3 • Neutrinos allow for the study of particle physics, without the complications of strong and electromagnetic forces. Svoboda
Neutrino Physics Goals Svoboda
neutrino Svoboda
Far Detector Options Water • 100 kTfiducial module. • 4850 ft depth. • 15% or 30% HQE PMT coverage? • Gadolineum or not? • 1,2,3 modules? • More signal! • Larger volume Liquid Argon • 17 kTfiducial module. • 300, 800, 4850 ft depth? • 3, 4, 5 mm wire spacing? • Probably will be 3 mm • photon trigger? • 1,2,3 modules? • Less background! • Better p0 identification 100 kT water ~= 17 kT liquid Ar for beam physics sensitivity
300 kT water ~= 50 kT liquid Ar for beam physics sensitivity Svoboda
LBNE could push to 3-4 x 10-3 (see talk by Zeller)
Neutrino hierarchy determination from a galactic supernova burst David Webber August 20, 2010
Neutrino energies at infinity(1 second late-time slice of 10-second burst spectrum) H. Duan and A. Friedland, http://arxiv.org/abs/1006.2359
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
n 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) n flux at detector WC 30% coverage WC 15% coverage Liquid Ar
Inverted Hierarchy: Observed Spectra(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? 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? • 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
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
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
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
c2 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 Hierarchy Inverted Hierarchy Water Cherenkov 30% PMT coverage 4000 events Liquid Argon 630 events
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
Confidence vs. Events See other slides • SNB Hierarchy study improvements: • Allow more parameters to fit in my study to allow for spectral shifts and broadening, eg. E --> E_0 + m*E • Perform a multi-module simultaneous for Argon (nue) and Water (nuebar).
LBNE Workshop Summary • Choice of far detector is currently undecided • There are many choices • Liquid Argon has not been attempted at this size • possibility for something new • technical risk • Details of each detector are still under consideration
Far Detector Options Water • 100 kTfiducial module. • 4850 ft depth. • 15% or 30% HQE PMT coverage? • Gadolineum or not? • 1,2,3 modules? • More signal! • Larger volume Liquid Argon • 17 kTfiducial module. • 300, 800, 4850 ft depth? • 3, 4, 5 mm wire spacing? • Probably will be 3 mm • photon trigger? • 1,2,3 modules? • Less background! • Better p0 identification 100 kT water ~= 17 kT liquid Ar for beam physics sensitivity
References • http://www.int.washington.edu/talks/WorkShops/int_10_2b/, Aug 9-10