WIXLIB

Neutrino Flux Requirements for DUNELeo AliagaWG1: Neutrino FluxOctober 16, 2017

OutlineLBNF beamline designs.Current flux uncertainties.Reducing the flux uncertainties210-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

LBNF Beamline Designs310-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

LBNF BeamlinePrimary proton beam in 60-120 GeV.Initial 1.2 MW beam power, upgradable to 2.4 MW.Wide-band beam on-axis with tunable energy spectrum.Decay pipe 200 m long, He filled.Currently considering two different beamline designs: Reference (NuMI-like). Optimized (for CP violation).Decision regarding which one will go forward to preliminarydesign will be made soon.410-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

LBNF Reference BeamlineTwo horns, nearly identical to those used in NuMI, run at slightly higher current (230 kA).1 m long graphite fin target, similar to but not identical to NuMI targetFigures courtesy Amit Bashyal510-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

LBNF Optimized BeamlineThree horns, not similar to NuMI, run at 300 kA2 m long graphite fin target, but development of alternative graphite cylindrical targetdesign is ongoing at RALFigures courtesy Amit Bashyal610-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

LBNF Reference Beamline710-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

LBNF Beamline Options810-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

LBNF/DUNE Long Baseline PhysicsAssuming:1. 5% uncertainties on the normalizationsof the νe appearance correlated with theνμ disappearance.2. Additional uncertainties of 1%, 2% or3% that are uncorrelated with the νμspectrumGoing from 3% vs 1% uncertainty isequivalent to nearly doubling exposuretime.910-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNEDUNE CDRUsing GLoBES

LBNF/DUNE Long Baseline PhysicsFlux uncertainties enter:1. Directly (after constraint by the neardetector) the uncertainty 1, that iscorrelated between νe and νμ,2. Indirectly to the uncertainty 2, sinceflux uncertainties couple touncertainties in cross sections:DUNE CDRUsing GLoBESFinal uncertainties should include the flux shape uncertainty as well.1010-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Current Flux Uncertainties1110-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Focusing UncertaintiesL. Fields ((NA61 Workshop 2017)ReferenceOptimizedPOT counting and water layer are the most significant at the peak.Horn current and target longitudinal offset are the most significant at the fallingedge for the reference design.1210-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

HP UncertaintiesDUNE uses PPFX (Package to Predict the Flux) developed by MINERvA thatuses all relevant HP data (currently it corrects FTFP BERT G4 model).DUNE uses QGSP hadronic model and then only the uncertainties can becalculated using PPFX.PPFX calculates two kind of uncertainties related to the corrections of the HP:1. Beam attenuation.2. Hadron production.1309-19-2017Leonidas Aliaga NuMI Neutrino Flux Prediction

1. Beam AttenuationWhen the particle interacts in a volumeExample: Absorption crosssection of pion on AluminumamebcleitraprmaterialWhen the particle passes through thevolume without interacting the survivalprobability is calculated.Reference (Geant4):σabsorption 344 mbarMost of the cross-section discrepancies areless than 6%.1410-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

2. Hadron ProductionFor thin target data (NA49 for instance):pC - π XContours: 2.5, 10, 25, 50 and 75 % of the π yields.( f Ed3σ/dp3: invariant production crosssection)ReferenceThe scale allows us to use NA49for proton on carbon in 12-120GeV (calculated with FLUKA).It was checked by comparing withNA61 at 31 GeV (negligibledifference).Systematic uncertainties 3.8%(added in quadrature).1510-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Hadron Production Needsπ, K and nucleons productions from pC based on data (mainly NA49).nucleon-A: quasi-elastics, extension from carbon to other materials, etc.No data applied to meson incidents: assuming large uncertainties.totaltotalL. Fields ((NA61 Workshop 2017)2.5Reference21.5number of interactionsnumber of interactions2.5Total HPOptimizedpC-- π XpC-- KXnC-- π XpC-- nucleonXmeson inc.2nucleon-Aothers1.5110.50.5Average number of interactions per neutrino at the near detector0024681012 14 16 18 20neutrino energy (GeV)0024681012 14 16 18 20neutrino energy (GeV) 2.2 for very low Eν and 1.2-1.5 for the rest1610-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Hadron Production UncertaintiesSame procedure as MINERvAapplied to DUNE beamsimulationTotal HP uncertainty 7% in thepeak and 12% for very lowenergies.1710-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNEReferenceL. Fields (NBI 2017)

Hadron Production UncertaintiesParticle production in proton carboninteractions:Pions (pC - π)Kaons (pC - K)Nucleons (pC - N)All covered by external data (mainlyNA49).(for high energy kaons, a combinationof NA49 MIPP k/π )The magnitude of this uncertaintydepends both on uncertainties reportedby experiments.The correlations of the datasets are notreported by experiments. We assumed100% for the systematics (conservativeapproach from MINERvA).1810-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNEReference

Hadron Production UncertaintiesExtending the data coverage:Nucleon interactions (NucleonA)ReferenceConstrain these interactions with pCadding an additional uncertainty foundby comparing A dependence of Barton,Skubic and Eichten.When there is not data coverage, like:Incident Mesons (Meson Inc)Guided by the agreement with otherdatasets: processes categorized bymeson and produced particle. 40% errorassigned in 4 xF bins.1910-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Reference and Optimized Beam UncertaintiesOptimizedReferenceVery similar in focusing peak; Optimized has slightly larger uncertainties at high energy,primarily due to having more interactions not covered by data2010-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Beam Uncertainty Correlation Matrix for the Optimized beamOptimizedFluxes are highlycorrelated across mostbinsFocusing regions andhigh energy bins are theexceptionsDepends strongly oncorrelations ofunderlying datasets; inmany cases, we have toguess at these.L. Fields (NA61 Workshop 2017)2110-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Reducing the flux uncertainties2210-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

How can we reduce the a priori uncertaintiesMore thin target datatotaltotal2.5Reference21.5123Total HPInelastic cross-sections of π, K and protons indifferent materials (C, Fe, Al, He).pC-- π XpC-- KXnC-- π XpC-- nucleonXmeson inc.2nucleon-ADifferential cross-sections in different materialsothers π - π at a wide range 10-60 GeV. pA- π (K) X, where X ! C1.51Average number of interactions per neutrino atProtonthe near detectorquasi0.500number of interactionsnumber of interactions2.5elastic cross-sections0.52410-16-2017681012 14 16 18 20neutrino energy (GeV)00246Leonidas Aliaga Neutrino Flux Requirements for DUNE81012 14 16 18 20neutrino energy (GeV)

How can we reduce the a priori uncertaintiesReplica target data: MINERvA experience. 5% using MIPP NuMI target data primarily.A reduction to 5%Phys. Rev. D 94, 092005 (2016)Checking the consistency with the low-nu measurement, MINERvA decidedto use a prediction based only on thin target corrections2410-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

LBNF Flux SpectrometerA concept to measure hadron production after the horns (See Paul Le Brun’s talk)2510-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Reducing the Focusing UncertaintiesAfter reducing the HP, the focusing uncertaintieswill become dominant.ReferencePOT counting and water layer arethe most significant at the peak.Horn current and target longitudinaloffset are the most significant at thefalling edge for the reference design.2610-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

ConclusionsReducing the HP uncertainties is possible with dedicated experiments: Replica target data would be the best option but timescale is a challenge(DUNE expects to receive beam in 2026) and it is likely that no replica will beavailable. Thin target data would likely to have big impact on DUNE.2710-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

backup2810-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

LBNF/DUNE Long Baseline PhysicsRespect to the shape (flux shape can have a big impact):LBNE PhysicsBookThis omission means that systematics likely have an even bigger impact than shownon previous page (which is already impressive!)2910-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

MINERvA Strategy for Predicting the FluxAccounting for every optical modeling uncertainty.1. Calculate an a-priori fluxCorrecting the hadron production in the beam lineto constrain to external hadron production data.Checking our results with the low recoil eventrates (low-nu method): flux shape measurement.2. Use in-situ measurementsApplying an additional constraint from theneutrino - electron scattering events.3. Package to Predict the FluX3010-16-2017Develop every tool in such a way they can be usedby any experiment at NuMI (PPFX).Leonidas Aliaga Neutrino Flux Requirements for DUNE

Some geometrical improvementsEffect of 1mm water layer around the Horn 1inner conductorFlux ratiowater layer addition / nominalLE at MINERvA4% effect around the LE flux peak.More accurate description of the innerconductor (IC) of Horn 1 designed for LBNF- Improved segmentation of the IC surface- Check the neck shape (cylinder).5% (14%) effect in the LE (ME) fallingedge of the flux peak at MINERvA.3110-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE(Implemented by Paul Le Brun)

External Data? What Sort of Data is Available? Hadron production data at the relevant energies for NuMI (references in thebackup slides):Inelastic/absorptionThin Target DataπpKpππpThick Target Dataπ pKppππChecking the consistency with the MINERvA low-nu measurement, wedecided to use a prediction based only on thin target correction3210-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

1. Beam AttenuationWhen the particle interacts in a volumepaeambelrticrWhen the particle passes through thevolume without interactingTwo variables areimportant here:3310-16-2017amebcleitrapmaterialr materialThe amount of material: rNAρ/A .The σData and σMC disagreement .Leonidas Aliaga Neutrino Flux Requirements for DUNE

Amount of Material TraversedMuon neutrino parent:LELE ModeMode atat MINERvAMINERvAReferences:- C: 6 mol/cm2 40 cm- Al: 1 mol/cm2 10 cm- He: 1 mol/cm2 500 m3410-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Data - MC ComparisonInelastic cross sectionProton on CarbonReference (Geant4):σabsorption 243.2 mbar3510-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNEAbsorption cross sectionPion on AluminumReference (Geant4):σabsorption 344 mbar

2. Hadron ProductionFor thin target data (NA49 for instance):( f Ed3σ/dp3: invariant production cross section)The scale allows us to use NA49 for proton on carbon in 12-120 GeV(calculated with FLUKA).It was checked by comparing with NA61 at 31 GeV (negligible difference).For thick target data (MIPP):3610-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE

Example: NA49 Data/MC comparison (closed circles statistical error 2.5%, Opencircles statistical error 2.5-5.0%, Crosses 5%).pC - π XLE Mode at MINERvAcorrection (Data/MC))Contours: 2.5, 10, 25, 50and 75 % of the pion yields.- Systematics are highlycorrelated bin-to-bin.- Systematics and statisticalerrors are considereduncorrelated each other.Systematic uncertainties 3.8%(added in quadrature).3710-16-2017Leonidas Aliaga Neutrino Flux Requirements for DUNE