Nu MI Beam Flux Sacha E Kopp University

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

Neutrino Beams 101: g 4 numi Ž. Pavlović 2

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

Focusing peak ND Flux Error Ž. Pavlović • 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 4 up by actual beam instrumentation measurements.

Hadron Production Uncertainty (I) LE 10/185 k. A Beam p. HE Beam M. Messier 5

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

Hadron Production Uncertainties (III) Before Neutrino Weighting After Neutrino Weighting Fluka 2005 Ž. Pavlović • 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. 7

Effect of Hadron Reweighting Ž. Pavlović • p. T 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 x. F and p. T. 8

Energy Scan Data Question: the agreement in these plots is (choose one). . . Trish Vahle a) Satisfactory v v Data Beam MC + Error b) Not satisfactory v LE ME Agreement is better than 20 -30% originally feared. We are likely therefore within the error budget from Trisha/Jenny. HE v v 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). 9

Alternate Horn Currents LE 10/200 k. A LE 10/185 k. A LE 10/170 k. A PBEAM MC Trish Vahle ND Data (R 1. 16) Ž. Pavlović • 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. 10

For Dm 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 v v Ž. Pavlović 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’ 11

Can We Demonstrate Beam Extrapolation? Predicted FD Spectrum • • Jenny Thomas, Trisha Vahle K 2 K says Dm 2<5 10 -3 e. V 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. = 5 E 18 POT) 12

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

Conclusions • GNu. MI-v. 18 is our best effort. No major known ‘outstanding issues’. • Systematic errors should cover us for now. v v Several have been supplied as correlated error distortions Hadron production currently supplied as an ‘error envelope’ (no correlations). • Short-term: demonstration of understanding of the beam requires ~3 months v v 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 k. A running in LE 10 position (won’t change the central value of Dm 2, but affects confidence in its error) • Long-term: upgrades to this analysis will require 6 -12 mo. to achieve: v v Study of p/K production ratio using Mini. Boo. NE (6 mo. ) g 4 numi (has significant geometry changes) (6 mo. ) Use m. Mon’s to constrain ME and HE fluxes (6 -12 mo. ) Survey of hadro-production data, inclusion of NA 49 & MIPP (12 mo. ) • It is a central discussion how we want to present the results v v Have enough analysis done to demonstrate understanding of the beam Have enough analysis done to claim Dm 2 not affected by uncertainties 14