effect on flux from target z-position smearing · simulation parameters g4lbne with...

Effect on flux from target z-position smearing

Timur BeremkulovBIWG meeting 07/11/2019

MotivationProton beam

Graphite target

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Pions, kaons Neutrinos

● To measure the oscillation angle with desired precision flux needs to be constrained within 1-2%

● Need to know upper bound on z-position measurement precision for NA-61/SHINE

Simulation Parameters

● g4lbne with OptimizedEngineedredNov2017.mac● 2*10^6 protons @ 120 GeV● Graphite target 2.2 m long

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Nominal NuMu flux at far detector

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● Get info about particles that exit the target● Scramble the z-position of particles● Feed them back into the simulation

● Two ways how scrambling was done:○ Gaussian smearing: Z_new = gaus(Z_old, sigma)○ Smearing within bins: break 2.2 m into N-1 bins + 1

downstream bin, if z_old is in bin M => Z_new = uniform(length of bin M)

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Example of Target Exit Z position plot, with gaussian smearing, sigma = 50cm

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Example of Target Exit Z position plot, with gaussian smearing, sigma = 5cm

Relative difference in flux for gaussian smearing

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(Flux_before_smearing - Flux_after_smearing)/Flux_before_smearing

Energy, GeV

Example of Target Exit Z position plot, with gaussian smearing, N_bins = 5

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Relative difference in flux for smearing within bins

Energy, GeV

Summary

● Effect of gaussian smearing and smearing within bins on NuMu flux at far detector were studied.

● Both methods show that z-position should be known within 10 cm.

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