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New supernova neutrino spectrum
Gleb SinevLArSoft Coordination Meeting
April 12, 2016
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New SNν energy spectrum
● Original spectrum is not cross-sectionweighted → is not what we expect to see
● New spectrum exposed a bug – fixed
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Input νe spectrum
Livermore model (LArSoft default) GVKM modelcross-section weighted
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Output electron spectrum
Livermore model (LArSoft default) GVKM modelcross-section weighted
All plots in this talk are made for generator-levelMC truth, before detector simulation or LArGeant
This change should greatly increasenumber of observable neutrinos
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Bug in output energy
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Sampling neutrino energy(no interpolation)
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Bug● Problem with the way energy is sampled● Y values normalized to 1 instead of total area● The bug disappears if the total area
is normalized to 1● Doesn't matter if the input TGraph
spectrum does not have gaps (all points are equidistant in energy)
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Sampling neutrino energy now
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Bug is fixed
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Conclusions● New spectrum is already in larsoft_data
(gvkm_nue_spectrum.root)● Would like to change the spectrum
used by default in larsim/EventGenerator/supernova.fcl
● Will merge the bug fix later(I would like to use a ROOT TF1/TH1 method to sample energy – the new spectrum is not affected)
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Backup slides
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Livermore final particle energy spectra
Unfortunately the electron spectrumis quite different from the neutrinospectrum – this will make determination of the initial neutrino energy challenging
All plots in this talk are made for generator-levelMC truth, before detector simulation or LArGeant
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GVKM final particle energy spectra
Input neutrinos are more energetic→ electron energy is much closerto the neutrino energy→ this model doesn't take into account 40Ar excitations above ~7 MeV,so I'm not sure how accurate it isfor higher energy neutrinos All plots in this talk are made for generator-levelMC truth, before detector simulation or LArGeant
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Supernova neutrino generator● A generator written by AJ Roeth
(LBNE-doc-8225-v1)● Calculates νe-40Ar CC cross section
using 21-level model● Produces an electron and several γs
using 73-level model● Simulates νe-40Ar CC interactions in a box
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Simulation model
40Ar 40K
21 levelsto calculate
cross section
νe → e-γ
γ
73 levelsto simulategammas
40K*
Nearest level(not a transition)