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MiniBooNE and Pion Production Measurements at HARP

MiniBooNE and Pion Production Measurements at HARP. Motivation Experiments Results. Linda R. Coney Hope College Pheno2007. Motivation. A simple truth in neutrino physics:. Contains everything interesting: oscillation physics, exotic event rates, cross sections, etc.

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MiniBooNE and Pion Production Measurements at HARP

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  1. MiniBooNE and Pion Production Measurements at HARP Motivation Experiments Results Linda R. Coney Hope College Pheno2007 Linda R. Coney

  2. Motivation • A simple truth in neutrino physics: Contains everything interesting: oscillation physics, exotic event rates, cross sections, etc. The subject of this talk Linda R. Coney

  3. Neutrino Beam Fluxes • Neutrino beams are produced in the laboratory by the weak decays of nuclei, nucleons, and , , and K mesons. • The spectrum of neutrinos from these decays is known extremely well • The only significant flux uncertainty comes from the production cross section of the parent particle and its subsequent scattering in target materials (ignoring neutrino oscillation parameters that is!) • In decay-at-rest beams, this is simply an overall normalization factor. A single well-understood neutrino cross section is enough to completely determine the neutrino flux (e.g. e elastic process, or an inverse -decay transition) However, in decay-in-flight beams, the complete differential production cross sections of the parent particles are needed, along with their interactions in material along their flight paths Linda R. Coney

  4. Decay-in-Flight  Beams • The calculation of secondary-production cross sections of  and K mesons in proton-nucleus collisions is not reliable, although new data is challenging modelers to make improvements • Phenomenological parameterizations can be valid over limited energy and angle ranges, more useful at higher energies (> ~15 GeV) (e.g. Sanford-Wang or others) • There are large discrepancies in the various hadron production models used in MC generators (MARS, FLUKA, MCNP, GHEISHA, etc.), although the situation is has been improving In order to predict fluxes with uncertainties less than ~10%, direct measurements of the production cross sections of the parent particles in the appropriate energy and angular ranges are necessary Linda R. Coney

  5. MiniBooNE Overview: Experimental Setup Decay region 25 m 50 m 450 m • MiniBooNE receives 8.9 GeV/c protons from the Fermilab Booster. • Protons are focused onto a 1.7 interaction length beryllium target producing various secondaries (p’s, p’s, K’s). • Secondaries are focused via a magnetic focusing horn surrounding the target. The horn receives 170 kA pulses at up to 10 Hz. Linda R. Coney

  6. MiniBooNE Overview: Experimental Setup Decay region 25 m 50 m 450 m Primary beam Secondary beamNeutrino beam • Short lived pions and kaons decay to produce a forward beam of mixed neutrinos aimed at the MiniBooNE detector • Need to understand the flux of neutrinos of different flavors through detectors where want to make cross-section or oscillation measurements • Crucial to understand hadron production and interactions a HARP Linda R. Coney

  7. Variation in MC Predictions of  Flux (MiniBooNE)  (old) Conclusion: the neutrino beam is sensitive to poorly understood, forward (small angle), pion production rates (D. Schmitz) Various studies have shown that the largest uncertainty in the  flux prediction is the knowledge of the /K production cross sections Linda R. Coney

  8. Solutions to the Problem • Experimental design helps in neutrino oscillation measurements (although not in cross section measurements) • near/far ratio (two detectors): (K2K/MINOS) • This is the simplest solution, although somewhat more costly. Useful in both appearance and disappearance measurements, a large signal helps! • e / “ratio”: (MiniBooNE) • In appearance experiments, the source neutrino channel (usually ) can be used to measure the expected oscillated flux under a particular oscillation hypothesis. This assumes only “lepton-universality” in the reaction cross sections, but accurate background measurements are important. Nevertheless, flux uncertainties can result in much poorer experimental sensitivities and better flux predictions are warranted Linda R. Coney

  9. Experimental Meson Production Data • Significant amount of data exists but a match between energy, angular range, and nuclear target is required to avoid systematic errors due to interpolation or extrapolation in (Ebeam,,A) • At energies above ~15 GeV and in certain angular ranges, “x-scaling” seems to be reliable for extrapolating to nearby energies • Most “historical” data is in the form of single-arm spectrometer measurements of meson inclusive production cross sections. • high statistics, good spectral shape determination, but they can suffer from knowledge of the absolute efficiency. • somewhat limited value in neutrino flux predictions Recently, modern 4 detector technology efforts have been mounted to measure absolute meson-production in proton-nucleus over a variety of nuclei ranging from hydrogen to uranium Linda R. Coney

  10. HARP (Hadron Production Experiment) at CERN • Neutrino factory studies • Atmospheric neutrino predictions • Neutrino flux predictions for current accelerator based neutrino beam experiments • K2K • MiniBooNE • Input for hadron generators (GEANT4) Harp is a large angle spectrometer designed to measure hadron production from various targets and a range of incident beam momenta Linda R. Coney

  11. HARP at CERN Designed to measure secondary meson production on wide range of target nuclei – Hydrogen-Lead • Beam particles: p, p, e+- • Beam momenta: 1.5 - 15 GeV/c • 400 Million events • Target thickness: l = 2-100% • ( about 1-40cm) • Target materials: • Be,C,Al,Cu,Sn,Ta,Pb,H2,O2,N2, D2 • MiniBooNE, K2K • Measure particle production for: p, p, K • Overlapping Particle ID detectors (ToF, Ckov, Cal) Linda R. Coney

  12. Harp Data: MiniBooNE Relevance • The first goal was to measure p+ production cross sections for Be at pproton = 8.9 GeV/c. • Additional measurements include: • p- production cross section (for anti-n running) • K+ production cross section ( important for intrinsic ne backgrounds) • Thick target secondary yields (effect of reinteractions) • No extrapolations in Ebeam or A, only angle 1.75 l Linda R. Coney

  13. HARP Forward Spectrometer 8.9 GeV/c + beam Linda R. Coney

  14. Relevance to  Physics • HARP • Primarily relevant to MiniBooNE and K2K • 8.9 GeV/c on Be target and 12 GeV/c on Al target • 4 angular acceptance however initial analyses only used forward spectrometer • No extrapolation needed in Ebeam or A, only needed for angles > 210 mrad • Results on thin Al and Be, 5% targets at 12.9 and 8.9 GeV/c resp. Linda R. Coney

  15. HARP Results: 12.9 GeV/c Al Thin Target Data • Directly applicable to K2K’s results • K2K’s oscillation result is mostly insensitive to this because they measure a near/far ratio Nucl.Phys.B732:1-45,2006 hep-ex/0510039 Linda R. Coney

  16. Comparison to Previous Aluminum Data Near 12.9 GeV/c beam momentum: (M. Sorel) Linda R. Coney

  17. HARP Be Results hep-ex/0702024 Linda R. Coney

  18. Conclusions for Recent HARP Results • p-Be + production cross sections at 8.9 GeV/c are now well determined • We are now in a better position to understand neutrino cross sections from beams in this energy range • Results folded into MiniBooNE neutrino flux prediction • MiniBooNE first results are out (see talks from earlier today) • flux uncertainty 10% • HARP thick target analysis is next • p-Al + cross sections at 12.9 GeV/c are now well determined • The cross section is different by as much as 20% from extrapolations that neutrino experiments have used in this energy region, however it is still consistent with the systematic errors of previous measurements • We are now in a better position to understand neutrino cross sections in this energy range Linda R. Coney

  19. Outlook • HARP: • Analysis of thick target data will shed light on secondary interactions in K2K and MiniBooNE and measure yields below 30 mrad • p- data analysis for MiniBooNE is in progress for antineutrino running • Are looking at Kaons • New results coming out of HARP – large angle using TPC • Tantalum, Copper, Tin, Carbon Linda R. Coney

  20. End Linda R. Coney

  21. The MiniBooNE Neutrino Beam nmne? • Many studies have shown that the largest uncertainty in the  flux prediction is the knowledge of the /K production cross sections • Various models are known to have large differencesin neutrino rate predictions • It is vital to calibrate neutrino production target in a proton beam Linda R. Coney

  22. Modern 4 Experiments • The E910 experiment at Brookhaven NL • designed to measure intra-nuclear cascade effects in strange particle and resonance production by comparing production from light and heavy nuclei • Proton momenta in the range of 6-18 GeV/c • The PS214 experiment (HARP) at CERN • designed to measure secondary meson production on a wide range of nuclei hydrogen - lead • Proton momenta in the range1.5-15 GeV/c • included liquid cryogenic targets (H2, D2) and (N2, O2), relevant for atmospheric neutrino production • Data with beam energies and target configurations specific to MiniBooNE (8.9 GeV/c, Be target) and K2K (12.9 GeV/c, Al target) Linda R. Coney

  23. HARP at the CERN PS • CERN PS: • 200 meters in diameter • 28 GeV maximum energy • Feeds into SPS • Used to make anti-protons • Used for target expr. - HARP Linda R. Coney

  24. BNL/E910 Apparatus 20M Triggers 6/12/18 GeV/c Beam Be/Cu/Au/U Targets Linda R. Coney

  25. Particle Identification TPC dE/dx Time of Flight p Used below 1.2 GeV/c Good below 5.4 GeV/c K p π K π Log dE/dx vs. Momentum 1/β vs. Momentum (J. Link) Linda R. Coney

  26. HARP: Cross Section Measurement • Count number of well reconstructed charged particles • Identify particle type using PID detectors (ToF, Che, Cal) • Account for geometric acceptance, tracking efficiency, particle id efficiency, trigger efficiency • Unfold from reconstructed quantities to “true” quantities as a function of momentum and angle • Subtract background due to tracks not from target – Empty target subtraction acceptance migration matrix pion purity pion yield tracking efficiency pion efficiency Linda R. Coney

  27. Relevance to  Physics • The E910 experiment at Brookhaven NL • designed to measure intra-nuclear cascade effects in strange particle and resonance production by comparing production from light and heavy nuclei • Proton momenta in the range of 6-18 GeV/c • The E910 experiment at Brookhaven NL • Primarily relevant to MiniBooNE • 6.4, 12.3 GeV/c on Be target with ~ 4 angular acceptance • 6.4 GeV/c data has poor statistics • Must extrapolate to 8.9 GeV/c • Results for Be pion/kaon production at 6/12 GeV/c • HARP at CERN • Primarily relevant to MiniBooNE and K2K • 8.9 GeV/c on Be target and 12 GeV/c on Al target • 4 angular acceptance however initial analyses only used forward spectrometer • No extrapolation needed in Ebeam or A, only needed for angles > 210 mrad • Results on thin Al and Be, 5% targets at 12.9 and 8.9 GeV/c resp. Linda R. Coney

  28. K2K Near/Far Ratio Predicted Flux Shape Predicted Far/Near Ratio Near Detector Near/Far Ratio Far Detector Near/far ratio errors are greatly reduced with the inclusion of Harp Data Linda R. Coney

  29. E910 TPC results (<1.2 GeV/c) TPC performance (H. Kirk) Linda R. Coney

  30. E910: Preliminary+ Production on Be Curve is a Sanford-Wang Fit 6.4 GeV/c 12.3 GeV/c (J.M. Link) Linda R. Coney

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