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NuMI Beam Flux

University of Texas at Austin – 41 University of Southern California – 38. NuMI Beam Flux. Sacha E. Kopp University of Texas at Austin. Neutrino Beams 101:. g4numi. Ž . Pavlovi ć. Neutrino Beams 102:. p +. to far Detector. (stiff). target.

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NuMI Beam Flux

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  1. University of Texas at Austin – 41 University of Southern California – 38 NuMI Beam Flux Sacha E. Kopp University of Texas at Austin

  2. Neutrino Beams 101: g4numi Ž. Pavlović

  3. Neutrino Beams 102: p+ to far Detector (stiff) target • ND and FD spectra similar, but not identical qf p+ qn (soft) Decay Pipe ND Near Detector LE Beam

  4. ND Flux Error • All effects not including hadron production uncertainties. • Some uninvestigated effects noted in position paper (minos-doc-1278) were since studied in supporting document (minos-doc-1283) • As discussed in minos-doc-1283, in many cases these errors backed up by actual beam instrumentation measurements. Focusing peak Focusing peak Focusing peak Ž. Pavlović

  5. Hadron Production Uncertainty (I) LE10/185kA Beam pHE Beam M. Messier

  6. Hadron Production Uncertainty (II) Spread due to models: • 8% (peak) • 15% (tail) Marino, Kang, Yang, Yumiceva,

  7. Hadron Production Uncertainties (III) After Neutrino Weighting Before Neutrino Weighting • Can in principle fit ND data to beam MC by weighting/deweighting as a function of pion xF and pT. • For now, attempted crude approach to parameterize the effect via several pion pT distributions. Fluka 2005 Ž. Pavlović

  8. Effect of Hadron Reweighting • pT reweighting by an amount consistent with Fluka/MARS models’ spread gives similar n flux spread (comforting). • Allows us also to explore the correlations between the LE/ME/HE beams – we can fit this? • In principle can expand to fits to work in both xF and pT. Ž. Pavlović

  9. Energy Scan Data Question: the agreement in these plots is (choose one)... • Satisfactory • Agreement is better than 20-30% originally feared. • We are likely therefore within the error budget from Trisha/Jenny. • Not satisfactory • Want to fit this to constrain hadron production in the MC • By eye, a tweak of pT alone cannot accommodate all 3 beams. • Proper fit requires evolution of pT vs.xF of pions (not yet attempted). Trish Vahle Data Beam MC + Error HE ME LE

  10. Alternate Horn Currents LE10/200kA LE10/185kA LE10/170kA • Alternate horn currents sample different pion pT’s –information which complements energy scan. • Beam MC not yet propagated through GMINOS. • At present, ceci n’est pas un analysis. PBEAM MC ND Data (R1.16) Trish Vahle Ž. Pavlović

  11. For Dm2, why do we really care? • Answer #1: If David tweaks hadron production to match ND data with MC, he will induce change in predicted FD flux • 5% in the tail • 1-2% in the peak • Answer #2: If Trish uses F/N method and takes ND as ‘truth’, the right plot is FD ‘uncertainty band’ Ž. Pavlović

  12. Can We Demonstrate Beam Extrapolation? • K2K says Dm2<510-3 eV2 HE beam does not have oscillations. • Compare FD data with extrapolated spectrum from ND. • Different issues in HE and LE beams, but can serve as a nice ‘check’. • Requires more data to make this meaningful (1 wk. = 5E18 POT) Jenny Thomas, Trisha Vahle Predicted FD Spectrum

  13. Antineutrinos • ‘Bare target’ beam spectrum (p- sneaking through horn necks). • GNuMI-v.17 was incorrect on this flux! • Significant model differences (noted in NuMI-B-768 but not understood). • Focusing uncertainties (current, alignment) haven’t been studied! • Strongly urge n’s be eliminated from the 1020POT data. Marino, Kang, Yang, Yumiceva,

  14. Conclusions • Systematic errors should cover us for now. • Several have been supplied as correlated error distortions • Hadron production currently supplied as an ‘error envelope’ (no correlations). • GNuMI-v.18 is our best effort. No major known ‘outstanding issues’. • Short-term: demonstration of understanding of the beam requires ~3 months • Fit our beam MC to the ND data as function of pion/kion xF and pT • Uses LE/ME/HE energy scan & 170/200 kA running in LE10 position (won’t change the central value of Dm2, but affects confidence in its error) • Long-term: upgrades to this analysis will require 6-12 mo. to achieve: • Study of p/K production ratio using MiniBooNE (6 mo.) • g4numi (has significant geometry changes) (6 mo.) • Use mMon’s to constrain ME and HE fluxes (6-12 mo.) • Survey of hadro-production data, inclusion of NA49 & MIPP (12 mo.) • It is a central discussion how we want to present the results • Have enough analysis done to demonstrate understanding of the beam • Have enough analysis done to claim Dm2 not affected by uncertainties

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