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Quasi-Elastic Neutrino Scattering measured with MINERvA

Quasi-Elastic Neutrino Scattering measured with MINERvA. Ronald Ransome. Rutgers, The State University of New Jersey. Piscataway, NJ. D. Drakoulakos, P. Stamoulis, G. Tzanakos, M. Zois University of Athens, Athens, Greece

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Quasi-Elastic Neutrino Scattering measured with MINERvA

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  1. Quasi-Elastic Neutrino Scattering measured with MINERvA Ronald Ransome Rutgers, The State University of New Jersey Piscataway, NJ DNP Oct. 2008

  2. D. Drakoulakos, P. Stamoulis, G. Tzanakos, M. ZoisUniversity of Athens, Athens, Greece C. Castromonte, H. da Motta, M. Vaz, J.L. Palomino Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, Brazil D. Casper, C. Simon, J. Tatar, B. ZiemerUniversity of California, Irvine, California E. PaschosUniversity of Dortmund, Dortmund, Germany M. Andrews, B. Baldin, D. Boehnlein, C. Gingu, N. Grossman, D. A. Harris#, J. Kilmer, M. Kostin, J.G. Morfin*, J. Olsen, A. Pla-Dalmau, P. Rubinov, P. Shanahan Fermi National Accelerator Laboratory, Batavia, Illinois J. Felix, G. Moreno, M. Reyes, G. ZavalaUniversidad de Guanajuato -- Instituto de Fisica, Guanajuato, Mexico I. Albayrak, M.E. Christy, C.E. Keppel, V. TvaskisHampton University, Hampton, Virginia A. Butkevich, S. KulaginInstitute for Nuclear Research, Moscow, Russia I. Niculescu. G. NiculescuJames Madison University, Harrisonburg, Virginia W.K. Brooks, A. Bruell, R. Ent, D. Gaskell, D. Meekins, W. Melnitchouk, S. WoodJefferson Lab, Newport News, Virginia E. MaherMassachusetts College of Liberal Arts, North Adams, Massachusetts R. Gran, C. RudeUniversity of Minnesota-Duluth, Duluth, Minnesota A. Jeffers, D. Buchholz, B. Gobbi, A. Loveridge, J. Hobbs, V. Kuznetsov, L. Patrick, H. SchellmanNorthwestern University, Evanston, Illinois L. Aliaga, J.L. Bazo, A. GagoPontificia Universidad Catolica del Peru, Lima, Peru S. Boyd, S. Dytman, I. Danko, D. Naples, V. PaoloneUniversity of Pittsburgh, Pittsburgh, Pennsylvania S. Avvakumov, A. Bodek, R. Bradford, H. Budd, J. Chvojka, M. Day, R. Flight, H. Lee, S. Manly, K. McFarland*, A. McGowan, A. Mislevic, J. Park, G. PerdueUniversity of Rochester, Rochester, New York R. Gilman, G. Kumbartzki, R. Ransome#, E. SchulteRutgers University, New Brunswick, New Jersey S. Kopp, L. Loiacono, M. ProgaUniversity of Texas, Austin, Texas H. Gallagher, T. Kafka, W.A. Mann, W. OliverTufts University, Medford, Massachusetts R. Ochoa, O. Pereyra, J. SolanaUniversidad Nacional de Ingenieria, Lima, Peru D.B. Beringer, M.A. Kordosky, A.G. Leister, J.K. NelsonThe College of William and Mary, Williamsburg, Virginia * Co-Spokespersons# Members of the MINERvA Executive Committee The MINERvA Collaboration A collaboration of ~80 Particle, Nuclear, andTheoretical physicists from 23 Institutions DNP Oct. 2008

  3. MINERvA Experiment • Main INjector ExpeRiment ν-A (at Fermi-Lab) • Placed upstream of MINOS near-detector in NuMI beam line • Fully active detector designed to make high precision measurements of neutrino-nucleus interactions • Built around central tracking volume of fine-grained scintillator • Measure cross-sections • Full event reconstruction • Liquid 4He, C, Fe, and Pb nuclear targets

  4. NuMI Neutrino Flux Intense neutrino beam with broad energy range MINERvA will use mixture of LE, ME, HE beam DNP Oct. 2008

  5. Neutrino-Nucleon Cross section NuMI flux range 1-20 GeV DNP Oct. 2008

  6. Event Rates13 Million total CC events in a 4 year run Assume16.0x1020 in LE, ME, and HE configurations in 4 years Fiducial Volume = 3 tons CH, ≈ 0.6 t C, ≈ .6 t Fe and ≈ .6 t Pb Expected CC event samples: 8.6 M n events in CH 1.4 M n events in C 1.4 M n events in Fe 1.4 M n events in Pb Main CC Physics Topics with Expected Produced nStatistics in 3 tons of CH • Quasi-elastic 0.8 M events • Resonance Production 1.6 M total • Transition: Resonance to DIS 2 M events • DIS and Structure Functions 4.1 M DIS events • Coherent Pion Production 85 K CC / 37 K NC • Strange and Charm Particle Production > 230 K fullyreconstructed events • Generalized Parton Distributionsorder 10 K events • Nuclear Effects C:1.4 M, Fe: 1.4 M and Pb: 1.4 M DNP Oct. 2008

  7. LHe n Detector Design • Thin modules hang like file folders on a stand • Attached together to form completed detector • Different absorbers for different detector regions 108 Frames in total Side HCAL (OD) SideECAL Fully Active Target NuclearTargets DownstreamHCAL Downstream ECAL Veto Wall Fully Active Target: 8.3 tons Nuclear Targets: 6.2 tons (40% scint.) DNP Oct. 2008

  8. Active Scintillator Target Triangular scintillators are arranged into planes – Wave length shifting fiber is read out by Multi-Anode PMT 1.7 cm WLS fiber Particle trajectory 3.3 cm 2.5 mm resolution with charge sharing Light yield 6.5 photo-electron/MeV PMT WLS Clear Fiber Scintillator DNP Oct. 2008

  9. Nuclear Target region XUXVXUXV (4 tracking points) between each layer Main detector Beam Carbon, Iron, Lead – mixed elements in layers to give same systematics DNP Oct. 2008

  10.   W+ n p Quasi-Elastic Neutrino Interactions (QE) Charged current: n p scc~ c1GE2 + c2GM2+ c3FA2 • GE2 , GM2extracted from electron-proton elastic scattering • FA2 is the axial form factor(extracted from neutrino-neutron scattering cross section) • c1, c2, c3 kinematic factors • c3FA2 accounts for about half of cross section

  11. Experimental Challenges • No free neutron targets, must use nuclei! • Need to isolate QE events from other processes • Use of nuclei introduces complications: • Non-zero total transverse momentum • Fermi momentum • Final state interactions (FSI) • FSI: • Particle production • Proton Loss • Non-QE processes can mimic QE • Possible modification of form factor • Projected to be a few percent (theoretical) • Thick targets cause: • Particle absorption

  12. Quasi-elastic scattering • Signature is mp with no other final state particles and zero transverse momentum • If reaction occurs in nucleus – • Fermi momentum gives non-zero transverse momentum • FSI can give additional particles • Resonance and DIS can produce proton + unobserved neutrons, mimicking QE • QE ranges from 30% of total cross section for 2 GeV neutrinos to less than 5% of total cross section for 10 GeV neutrinos • Requires good background rejection DNP Oct. 2008

  13. Quasi-elastic • Question – what is the nuclear dependence of extracted form factor due to contamination and losses, i.e. experimental effects? • Question – what is the effect due to nucleon being in nuclear medium, i.e. intrinsic modification? DNP Oct. 2008

  14. Anticipated statistics on Axial FF 800 K QE on C 150 K QE on Fe and Pb Comparisons in low Q2 better than 1% statistical uncertainty DNP Oct. 2008

  15. Simulation • Use GENIE: • Neutrino event generator • Uses combination of theoretical models and world neutrino data to generate events • Generates events on multiple nuclei • For this simulation – use fixed neutrino energies • http://howto.genie-mc.org/ • Model Detector • Check for track overlap (reduces observed multiplicity) • Particles stopped in interaction target • Count observed tracks • For this simulation – assume perfect particle ID

  16. Analysis • Analysis Cuts: • Number of tracks • mp – ideal case for QE event, or single muon • Also looked at higher multiplicities – improves efficiency, decreases purity • Particle ID: Non-QE processes produce pions • Vetoed charged and neutral pions • Q2 (GeV/c)2 • 0-1.2 (GeV/c)2 bins of 0.3 (GeV/c)2 • 1.2 (GeV/c)2 and greater • Total Transverse Momentum • Less than 0.25 GeV/c cut • No Transverse Momentum cut for this simulation • Event type (supplied by event generator) • Efficiency = QE with cuts/Total QE • Purity = QE with cuts/(all processes with cuts)

  17. m or mp events DNP Oct. 2008

  18. Results • Efficiency is high in low Q2 region (80-100%) • Nearly identical for C and Pb • Little energy dependence • Purity – decreases with Q2 and neutrino energy • Remains above 70%, even for 10 GeV neutrino • C and Pb have similar Q2 dependence, with Pb 5-10% less than C DNP Oct. 2008

  19. Conclusions • Corrections for C and Pb are not dramatically different • Relatively small energy dependence • Magnitude of correction 30% or less • Will need to compare actual data with GENIE output to determine accuracy of GENIE • Expect that we can compare extracted cross sections to better than 5% systematics • Comparison to He still underway DNP Oct. 2008

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