Measurement of Flux numu Flux measurement strategy CC

Measurement of Flux

numu Flux measurement • strategy: CC QE exclusive reconstruction in offaxis detector. mu(MIP)+p(highly ionizing) – – non-QE (1 pi)/QE measurement to get purity of sample off-axis, can separate easily pi and kaon contributions reference cross-section “well understood” high efficiency in ND 280 is important in order to minimize systematic error on efficiency • need a quantitative goal for this systematic

forming an error budget • make reference to disappearance measurement – current studies assumed 20% uncertainty in non-QE/QE ratio at super. K – this was roughly equivalent to statistical

predicting far flux at SK • studies exist of how hadron producting impacts far/near ratio – effect is small in peak region (few-5% effect) – effect is larger in high energy tail (non-kaon part) – can we make reference to ORIGINAL hadron production uncertainties from the data? – can we use these studies to set requirements for hadron production EXPERIMENTS?

moving the detector? • technical impact on infrastructure is very large, so we should try to decide soon • another way to view this… moving the detector provides a good cross-check on the far prediction • can we cover “enough” angle by not moving? (detector transverse size) – can build on MC work by Konaka and colleagues

most extreme version: on-axis • is on-axis spectrum measurement useful for near/far ratio? – we know this is not helpful for K/pi for example • also, how do we measure spectrum on axis technically? (measurement, 14 m deeper, etc…) • one counter argument… cross-sections are easier to understand, e. g. QE at high E flat(E) – counter-counter argument. backgrounds are larger to QE measurement

electron neutrino prediction • contributions: pi->mu, K+, K 0 – 1. 0: 0. 8: 0. 2 mu: K+: K 0 in ND (without veto on final state particle). somewhat higher muon contribution in far detector • pi and Ks are well measured off-axis in ND • concerns: – no handle on neutral kaons (get from production experiments only) – concerned about robust pi->mu->nu chain? • accuracy needed is not high. – 10 ev/5 yrs, 20% uncertainty allowed in far detector? ? should do better

electron neutrino measurement in ND 280 • technique : electron+proton final state • what does this measurement constrain? – ND sees a different mix of kaon and muon background – it’s a cross-check rather than a robust prediction, but want much better than 20% in ND • minor concern: we should check calculations of QE cross-section ratio for electron and muon neutrinos – 4% at 500 Me. V, so probably no worries…

anti-neutrinos? • is it important to measure in near detector? – do we plan to ever run anti-neutrinos? don’t want a situation where ND PROHIBITS anti neutrino running – other reasons: some of HE tail is wrong sign. Wrong sign helps to constraint neutral kaons • technically, want to make sure we can add the capability “in a summer shutdown”

predicting backgrounds at SK

non-QE background at SK • this is a SEPARATE issue from measurement of the flux using QE and subtracting backgroun intrinsic to the near detector • here we want to PREDICT the non-QE background at SK using measurements at ND 280

issues for non-QE background at SK • probably need to measure on oxygen since nuclear absorption is different • dominant non-QE background at SK is single pion – measure exclusive final state rates relative to QE rate at ND 280 – differential cross-sections • two types of background. real muons and fake muons – fake muons (e. g. , pions) are probably not a big issue at SK – are they a background to exclusive states at the near detector?

is off-axis detector enough? • do we need to move the detector to vary the spectrum (separate peak region from high energy tail)

what is the role of electron scattering? • in principle, very valuable information about nuclear effects with very high statistics • does it work? • probably need the option at least in reserve to have an oxygen rich ND 280 part

pi 0 background at super. K • similar comments about carbon/oxygen difference • 2/3 of background at super. K is resonant single pion – coherent production is estimated ~15%, but essentially unknown

a coherent program… • • can measure in CC and NC both in fully active detector, can measure in carbon what does that tell us about oxygen? there will at least be upper limits from K 2 K 1 k. T data • even CC coherent is a challenge to the detector. NC coherent is a very hard final state • it is enough to have CC in oxygen and carbon plus NC in carbon

resonance pi 0 • need total and differential cross-sections • does NC pi 0 resonant production require a variety of beam energies to do correctly? • CC allows you to deconvolute and CC can feed models of NC(Energy) • also, we need to temper severe requirements here with the knowledge that it can be measured directly at super. K. – are there ND measurements that help reduce these systematics? such as backgrounds to pi 0 at SK

search for single gamma • in principle, there are direct single photons – through radiative effects any contribution from coherent nucleus? – Δ Nγ • merits theoretical and experimental? study – probably are existing limits from old experiments on this process

detector discussion

muon monitor

thoughts on muon monitor • position well established – need sensitivity to >~5 Ge. V muons • fluence (10^8 mu/spill/cm^2) requirements limit detector technology • Nakaya: “choose technology that is not too exotic” – ionization chamber for example (get input from MINOS) • Konaka: “diamond detector” – we should begin R&D here. beam tests at TRIUMF, K 2 K • can we afford only one detector technology? – what if one fails? • homework for Jan. : conceptual design and cost est. – TRIUMF/UK(? ) for diamond; Kyoto/KEK for I. C.

on axis 280 m detector

opening thoughts on on-axis 280 m detector • physics need not as well established as other detectors – how is it not redundant with muon monitor? – how is it not redundant with 280 m off axis? • Some ideas: – position of neutrino beam (independent of muons) – is high rate important during commissioning for establishing neutrino beam? (first check) – important to measure the spectrum for checking pion spectrum? (for example, Konaka matrix argument) • Need to understand soon – digging deep requires ¥ ¥ ¥ (building cost ~ volume)

more comments • neutrino position measurement is important for sensitivity to low energy pions – so need to identify low energy neutrinos • detector could be extremely simple – need to select energy; need to preserve rate in order to make day-by-day measurements of beam – can there be a simple structure to house it? – is it worth working very hard to try to be clever and save money, or does it cost most to be clever in the end? • how complicated a detector would be needed to implement the on-axis matrix method?

homework for on-axis detector • Ichikawa’s detector is costed – grid detector covering large area • should we cost a large area detector? – scaling from OPERA (magnetized) MRD? • anyone to study a more “sparse” design? • need more complete understanding of building costs with these design concepts in mind – i. e. , for monolithic large detector, is there a floor load problem? • Konaka will study matrix method and which detector positions are needed

off-axis 280 m detector

opening thoughts on off-axis 280 m • physics need is crucial (yesterday’s discussion) – flux and neutrino interaction background – how will role change when 2 km is present? • many detector concepts – – – integrated nuclear targets vs localized “external targets” how can oxygen rich targets be made active? gamma converter inside vs outside detector outer muon detector design? magnetized? test ideas in K 2 K beam or at NUMI • our job today: need to establish physics benchmarks to test these

magnetization and MRD • this is possibly independent from other physics studies • maybe good to design a detector that can be run magnetized or not – can magnetization replace some of the mass of the detector (the compromise would be that high energy muons are not measured as precisely) – what is the requirement for energy resolution at high muon energies? • what is the requirement for low energy muons (drives sampling) [this is a question for later]

what is the required size of the FGD? • total mass of the detector is driven by size of the fine-grained part (because MRD size scales as square of the transverse size of the FGD)

technical risk • how do we evaluate “new” technologies that are proposed for this detector? – e. g. , “exotic” photosensors, stability of plastic scintillator in a water bath, active water detectors • specific questions – do we know the operational costs of VLPCs? (Clark wants to lead an R&D investigation on this)

physics signatures for study • quasi-elastics (proton tag, mu+p or e+p) – selection with high efficiency important? • unbiased efficiency as a function of angle. well-understood proton inefficiency as a function of momentum – requires understanding of both very soft and showering (interacting) protons? – opening angle also angle • the critical test: should be able to understand efficiency and background as a function of neutrino energy • is it important to identify by PID (rather than kinematically) the lepton to reject pions? • ability to observe additional activity as a inelastic tag – this leads to small systematic error on flux – configuration of absorber will change results… simulation!

physics signatures (cont’d) • resonant (and multi-pion) pi 0 production in NC and CC – pi 0 momentum and angle (unbiased) – additional activity… can the detector predict which events would give no additional activity in Super. K – ability to reconstruct events without tracks starting from the vertex (e. g. , nu+n->nu+n+pi 0) • systematic uncertainty in identifying fiducial volume • measurement of the pi 0 s from oxygen – possible techniques: statistical subtraction, event-byevent, active water target

coherent • full program to understand coherent rate requires NC and CC measurements • NC covered on previous page • CC: need to separate the two tracks (mu and pi) in the final state – role of magnetization? • effectiveness of vertex activity anti-tag – or kinematic subtraction?

measuring exclusive prcesses that produce backgrounds at SK • pion multiplicity in “DIS” (NSDIS “not so deep inelastic scattering) region • pi/p separation in DIS events

anti-neutrinos • QE in anti-neutrino? – vertex anti-tag – neutrons? (look along presumed direction? )

anything else? • study mu->e decay • ability to identify single gamma (discriminate from single electron or pi 0)

a proposal and a thank you • thank you all for contributing to a very successful meeting • thank you to our hosts • a proposal: NUINT 04 is 17 -21 March at Gran Sasso or Rome? maybe we will hold a ND 280 meeting at Gran Sasso March 16? • (also, afternoon December meeting at Stony Brook on or about December 12 th)