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Flux Error Analysis

Flux Error Analysis. Žarko Pavlović For Beam Systematics Group. Systematic Uncertainties. Goal of the study was to produce an “error-band” for neutrino flux Effects considered Uncertainty on number of protons on target Misaligned angle of horn 1 & horn 2

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Flux Error Analysis

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  1. Flux Error Analysis Žarko Pavlović For Beam Systematics Group MINOS Collaboration Meeting, 10-15-05

  2. Systematic Uncertainties • Goal of the study was to produce an “error-band” for neutrino flux • Effects considered • Uncertainty on number of protons on target • Misaligned angle of horn 1 & horn 2 • Misalignment offset of horn 1 & horn 2 • Uncertainty on the location of the chase shielding blocks • Incorrect calibration of horn current • Incorrect description of horn current in the inner conductor of the horns (skin depth effect) • Proton beam scraping on the baffle • Hadron production model • Used old MC studies and PBEAM to estimate how much of an effect these uncertainties cause MINOS Collaboration Meeting, 10-15-05

  3. Protons on Target • Old beam MC was off in scale by 4.8%. This had 2 contributions: • The toroids TOR101 and TORTGT were miscalibrated. Disagreement with Main Injector Toroid (called I:BEAM) at the level of ~4% has been known for some time. • The full NuMI beam does not hit the target. On average, 0.6% misses to the left and right and goes to the hadron absorber. • The net result of these two effects is that the beam MC was too high by 4.8%. • Since the toroids were calibrated net uncertainty on POT is ~1%. Will use this value for an error band. MINOS Collaboration Meeting, 10-15-05

  4. Fraction of beam on Target • The proton beam size increases as we go to higher intensity. Also varies from day-to-day (“bad” quality beam). • We directly measure the size at (near) the target, so can correct for any fraction missing the target. • Must look at this repeatedly throughout our analyses. • Through July 1, ~0.6% of beam misses the target and goes down the aperture between the target and baffle. target size s=1.2mm PMTGT (1 spill) p beam profile MINOS Collaboration Meeting, 10-15-05

  5. Horn Offsets & Angles • Bob Zwaska performed beam-based alignment. • www.hep.utexas.edu/numi/beamMC/ • Net outcome of his work: • Horns are not on the exact same line as the target by (0.5-1.0) 0.2 mm • The horns make angles with respect to the primary beam at the (0.1-0.2)0.1mrad level. • To be conservative we take an uncertainty of 1mm (offset) and 0.2mrad (angle) MINOS Collaboration Meeting, 10-15-05

  6. Incorrect Horn Current calibration • GNuMI-v17 MC (used in R1.18) used nominal values for Horn Current • Jim Hylen measured the current and found the true current to be 1.60.5% lower than the nominal values • New GNuMI-V18 MC run with true values • Assume ~1% uncertainty on Horn Current MINOS Collaboration Meeting, 10-15-05

  7. Skin Depth Effect Current on inner sheet of IC • Field between conductors is known and can be measured but the field in the inner conductor is worrisome • Can model if we know the skin depth of the current • Difficult since the conductor will change as it heats and is irradiated. • This plot (shown at Ely ’04) gives GNUMI calculation if d=0 or if d= (latter closer to truth) • Variation shown here probably overstates the uncertainty on the flux from this effect. • To get uncertainty, we modeled • Current uniformly distributed throughout the IC (d= ) • Current exponentially falling as a function of radius with d=6mm (cf J. Hylen). Current fills IC M. Messier MINOS Collaboration Meeting, 10-15-05

  8. Baffle Scraping • Collimating baffle can also act as a target. • Halo of proton beam scrapes on the baffle. • We measure the halo using PMTGT (<1%, ) G3NuMI Monte Carlo G3NuMI Monte Carlo M. Messier MINOS Collaboration Meeting, 10-15-05

  9. (Almost) Final Uncertainties: LE Beam Uncertainty on ND Spectrum Uncertainty on F/N Extrapolation • All effects excluding Hadron Production! Focusing Peak Focusing Peak MINOS Collaboration Meeting, 10-15-05

  10. (Almost) Final Uncertainties: LE(-10) Beam Uncertainty on ND Spectrum Uncertainty on F/N Extrapolation • All effects excluding Hadron Production! Focusing Peak Focusing Peak MINOS Collaboration Meeting, 10-15-05

  11. (Almost) Final Uncertainties: pME Beam Uncertainty on ND Spectrum Uncertainty on F/N Extrapolation • All effects excluding Hadron Production! Focusing Peak Focusing Peak MINOS Collaboration Meeting, 10-15-05

  12. (Almost) Final Uncertainties: pHE Beam Uncertainty on ND Spectrum Uncertainty on F/N Extrapolation • All effects excluding Hadron Production! Focusing Peak Focusing Peak MINOS Collaboration Meeting, 10-15-05

  13. Hadron Production Uncertainties • Spread of models is not the same as uncertainty • Correlated models (eg. Kaon content). • Some models known to have ‘flaws’ at certain kinematic regions • Assumed 8-15% error on near spectrum coming from hadron production See NuMI-B-768 Figure from F. Yumiceva MINOS Collaboration Meeting, 10-15-05

  14. Hadron Production & F/N Semi-ME Beam Semi-HE Beam Nominal LE Beam • To estimate the error on F/N coming from hadron production used older cocktail of MARS, BMPT and Malensek • We implement some ‘smoothing’ to the above curves: • Clearly statistical fluctuations in the MC. • Remove GFLUKA effect at high energies Estimated Uncertainty Estimated Uncertainty Estimated Uncertainty See NuMI-B-768 MINOS Collaboration Meeting, 10-15-05

  15. Final Uncertainties:ND Spectrum LE Beam LE(-10) Beam • All effects including Hadron Production! pHE Beam pME Beam Box height indicates magnitude of systematic uncertainty MINOS Collaboration Meeting, 10-15-05

  16. Final Uncertainties:F/N Ratio • All effects including Hadron Production! LE Beam LE(-10) Beam Box height indicates magnitude of systematic uncertainty pME Beam pHE Beam MINOS Collaboration Meeting, 10-15-05

  17. NuMI-BooNE Flux • Flux at MiniBooNE from pi/K decay-in-flight • Working on the error band on flux at MiniBooNE coming from NuMI beam • Expect small errors on flux p+ decays LE-10 K+ decays Figure from Alexis Aguilar Arevalo MINOS Collaboration Meeting, 10-15-05

  18. LE & LE-10 Flux LE Beam LE-10 Beam • Biggest contribution to the error comes from: • Uncertainty of neutrino interaction location • Hadron production (10% for pi and 15% for K?) MINOS Collaboration Meeting, 10-15-05

  19. pME & pHE Flux pME Beam pHE Beam MINOS Collaboration Meeting, 10-15-05

  20. Summary • Uncertainties from a variety of effects have been investigated for LE, LE(-10), pME, and pHE beams. • Vectors of uncertainties now are available for the G3NUMI beam MC: http://www.hep.utexas.edu/numi/beamMC • Flux at MiniBooNE is not sensitive to any misalignment or the uncertainties considered in this study gives opportunity to measure hadron production MINOS Collaboration Meeting, 10-15-05

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