Jpp PDF time arrival dependence on direction Jordan Seneca August 20 th 2020, update Jordan Seneca 1
cd = 0.74 A few months back, I showed this cd = -0.5 WRONG Plot information Cherenkov RIGHT angle has the least early light Jordan Seneca 2
Jordan Seneca 3
Cos(angle) dependence on the elongated time residual pdf cd = 0.74 Plot information cd = -0.99 Forward: a narrow distribution centered at dt ~ 1 ns and some late contribution Backward: a wide distribution centered at dt ~ 7 ns with early ( up to -25 ns ! ) and late contributions Jordan Seneca 4
Cos(angle) dependence on the elongated time residual pdf cd = 1.0 cd = 0.74 Note! Plot information Plot information earlier light here than at cherenkov angle! cd = -0.5 cd = 0.0 Jordan Seneca 5
Cos(angle) dependence on the raw time residual pdf cd = -0.5 cd = 0.74 Plot information With point-like showers, there is no difference in early light, but more late (scattered) light in the backward direction. → Shower elongation helps with direction estimation! Jordan Seneca 6
How does this work? → Heuristic explanation Jordan Seneca 7
Point-like shower case cos(a) = 0.74 (cherenkov) cos(a) All early light comes from the same point, but some late light is reflected backward from the bright cherenkov cone region shower cos(a) = -0.5 plotted angle late light Jordan Seneca 8
Elongated shower case, with shower max as origin By definiton, light cos(a) = 1.0 from the entire shower arrives to the cherenkov cos(a) = 0.74 (cherenkov) angle point at the same time → no early light In the backward and forward region, light emitted from the start and end of the shower respectively arrives early cos(a) (from shower max) shower plotted angle early light late light cos(a) = -0.5 Jordan Seneca 9
Conclusion: The light arrival time cd = 0.74 distribution is sensitive to the neutrino direction! The elongated shower’s sequential light emittance informs its direction. cd = -0.99 Jordan Seneca 10
Sidenote, elongated pdfs High dt bump for extremely backward directions. Maybe due to interpolation issues in the PDFs? cd = -0.99 cd = -0.5 Jordan Seneca 11
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