1 of 14 numi beam flux sacha e. kopp university of texas at austinuniversity of texas at austin –...
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NuMI Beam Flux
Sacha E. Kopp
University of Texas at AustinUniversity of Texas at Austin – 41
University of Southern California – 38
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Neutrino Beams 101:
g4numig4numi
Ž. PavlovićŽ. Pavlović
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Neutrino Beams 102:
• ND and FD spectra similar, but not identical
f
Near Detector
to farDetector
Decay Pipe
(soft)
(stiff)
n
target
2
222 1
11
L
Flux
221
43.0
EE
LE Beam
ND
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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.
Focu
sing
pe
ak
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pe
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pe
ak
Ž. PavlovićŽ. Pavlović
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Hadron Production Uncertainty (I)
M. MessierM. Messier
LE10/185kA BeamLE10/185kA Beam pHE BeampHE Beam
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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,
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Hadron Production Uncertainties (III)
• 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
Before Neutrino Weighting After Neutrino Weighting
Ž. PavlovićŽ. Pavlović
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Effect of Hadron Reweighting
• pT 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 xF and pT.
Ž. PavlovićŽ. Pavlović
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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 pT alone cannot accommodate all 3 beams.
Proper fit requires evolution of pT vs.xF of pions (not yet attempted).
Trish VahleTrish Vahle
Data
Beam MC + Error
HEME
LE
Question: the agreement in these plots is (choose one)...
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Alternate Horn Currents
• 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.
Trish VahleTrish Vahle
Ž. PavlovićŽ. Pavlović
PBEAM MCND Data(R1.16)
LE10/200kALE10/185kALE10/170kA
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For m2, 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. PavlovićŽ. Pavlović
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Can We Demonstrate Beam Extrapolation?
• K2K says m2<510-3 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 VahlePredicted
FD Spectrum
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Antineutrinos
• Focusing uncertainties (current, alignment) haven’t been studied!
• Strongly urge ’s be eliminated from the 1020POT 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,
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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 m2 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 xF and pT Uses LE/ME/HE energy scan & 170/200 kA running in LE10 position
(won’t change the central value of m2, 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.)