1 of 14 NuMI Beam Flux Sacha E. Kopp University of Texas at AustinUniversity of Texas at Austin – 41 University of Southern California – 38

2 of 14 Neutrino Beams 101: g4numi Ž. Pavlović

3 of 14 Neutrino Beams 102: ND and FD spectra similar, but not identical ff Near Detector to far Detector Decay Pipe   (soft) (stiff) nn target LE Beam ND

4 of 14 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 Ž. Pavlović

5 of 14 Hadron Production Uncertainty (I) M. Messier LE10/185kA Beam pHE Beam

6 of 14 Hadron Production Uncertainty (II) Spread due to models:  8% (peak)  15% (tail) Spread due to models:  8% (peak)  15% (tail) Marino, Kang, Yang, Yumiceva, Marino, Kang, Yang, Yumiceva,

7 of 14 Hadron Production Uncertainties (III) Can in principle fit ND data to beam MC by weighting/deweighting as a function of pion x F and p T. For now, attempted crude approach to parameterize the effect via several pion p T distributions. Fluka 2005 Before Neutrino Weighting After Neutrino Weighting Ž. Pavlović

8 of 14 Effect of Hadron Reweighting p T reweighting by an amount consistent with Fluka/MARS models’ spread gives similar 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 x F and p T. Ž. Pavlović

9 of 14 Energy Scan Data a)Satisfactory  Agreement is better than 20-30% originally feared.  We are likely therefore within the error budget from Trisha/Jenny. b)Not satisfactory  Want to fit this to constrain hadron production in the MC  By eye, a tweak of  p T  alone cannot accommodate all 3 beams.  Proper fit requires evolution of  p T  vs.x F of pions (not yet attempted). Trish Vahle Data Beam MC + Error HE ME LE Question: the agreement in these plots is (choose one)...

10 of 14 Alternate Horn Currents Alternate horn currents sample different pion p T ’s – information which complements energy scan. Beam MC not yet propagated through GMINOS. At present, ceci n’est pas un analysis. Trish Vahle Ž. Pavlović PBEAM MC ND Data (R1.16) LE10/200kA LE10/185kA LE10/170kA

11 of 14 For  m 2, 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 of 14 Can We Demonstrate Beam Extrapolation? K2K says  m 2 <5  eV 2  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 of 14 Antineutrinos Focusing uncertainties (current, alignment) haven’t been studied! Strongly urge ’s be eliminated from the POT data. ‘Bare target’ beam spectrum (   sneaking through horn necks). GNuMI-v.17 was incorrect on this flux! Significant model differences (noted in NuMI-B-768 but not understood). Marino, Kang, Yang, Yumiceva, Marino, Kang, Yang, Yumiceva,

14 of 14 Conclusions GNuMI-v.18 is our best effort. No major known ‘outstanding issues’. 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  m 2 not affected by uncertainties Short-term: demonstration of understanding of the beam requires ~3 months  Fit our beam MC to the ND data as function of pion/kion x F and p T  Uses LE/ME/HE energy scan & 170/200 kA running in LE10 position (won’t change the central value of  m 2, but affects confidence in its error) 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). Long-term: upgrades to this analysis will require 6-12 mo. to achieve:  Study of  /K production ratio using MiniBooNE (6 mo.)  g4numi (has significant geometry changes) (6 mo.)  Use  Mon’s to constrain ME and HE fluxes (6-12 mo.)  Survey of hadro-production data, inclusion of NA49 & MIPP (12 mo.)