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

DNP Oct The MINERvA Collaboration  D. Drakoulakos, P. Stamoulis, G. Tzanakos, M. Zois University 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. Ziemer University of California, Irvine, California  E. Paschos University 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. Zavala Universidad de Guanajuato -- Instituto de Fisica, Guanajuato, Mexico  I. Albayrak, M.E. Christy, C.E. Keppel, V. Tvaskis Hampton University, Hampton, Virginia  A. Butkevich, S. Kulagin Institute for Nuclear Research, Moscow, Russia  I. Niculescu. G. Niculescu James Madison University, Harrisonburg, Virginia  W.K. Brooks, A. Bruell, R. Ent, D. Gaskell, D. Meekins, W. Melnitchouk, S. Wood Jefferson Lab, Newport News, Virginia  E. Maher Massachusetts College of Liberal Arts, North Adams, Massachusetts  R. Gran, C. Rude University of Minnesota-Duluth, Duluth, Minnesota  A. Jeffers, D. Buchholz, B. Gobbi, A. Loveridge, J. Hobbs, V. Kuznetsov, L. Patrick, H. Schellman Northwestern University, Evanston, Illinois  L. Aliaga, J.L. Bazo, A. Gago Pontificia Universidad Catolica del Peru, Lima, Peru  S. Boyd, S. Dytman, I. Danko, D. Naples, V. Paolone University 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. Perdue University of Rochester, Rochester, New York  R. Gilman, G. Kumbartzki, R. Ransome#, E. Schulte Rutgers University, New Brunswick, New Jersey  S. Kopp, L. Loiacono, M. Proga University of Texas, Austin, Texas  H. Gallagher, T. Kafka, W.A. Mann, W. Oliver Tufts University, Medford, Massachusetts  R. Ochoa, O. Pereyra, J. Solana Universidad Nacional de Ingenieria, Lima, Peru  D.B. Beringer, M.A. Kordosky, A.G. Leister, J.K. Nelson The College of William and Mary, Williamsburg, Virginia  * Co-Spokespersons # Members of the MINERvA Executive Committee A collaboration of ~80 Particle, Nuclear, and Theoretical physicists from 23 Institutions

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 t Measure cross-sections t Full event reconstruction  Liquid 4 He, C, Fe, and Pb nuclear targets

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

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

DNP Oct Event Rates 13 Million total CC events in a 4 year run Assume 16.0x10 20 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 events in CH 1.4 M events in C 1.4 M events in Fe 1.4 M  events in Pb Main CC Physics Topics with Expected Produced Statistics in 3 tons of CH  Quasi-elastic 0.8 M events  Resonance Production 1.6 M total  Transition: Resonance to DIS2 M events  DIS and Structure Functions 4.1 M DIS events  Coherent Pion Production85 K CC / 37 K NC  Strange and Charm Particle Production > 230 K fully reconstructed events  Generalized Parton Distributions order 10 K events  Nuclear Effects C:1.4 M, Fe: 1.4 M and Pb: 1.4 M

DNP Oct Detector Design Fully Active Target: 8.3 tons Nuclear Targets: 6.2 tons (40% scint.) LHe SideECAL Fully Active Target Downstream ECAL Downstream HCAL Nuclear Targets Side HCAL (OD) Veto Wall  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

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

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

10 Quasi-Elastic Neutrino Interactions (QE) Charged current:  W+W+ n p  n   p  cc ~ c 1 G E 2 + c 2 G M 2 + c 3 F A 2  G E 2, G M 2 extracted from electron-proton elastic scattering  F A 2 is the axial form factor (extracted from neutrino- neutron scattering cross section)  c 1, c 2, c 3 kinematic factors  c 3 F A 2 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: t Non-zero total transverse momentum »Fermi momentum »Final state interactions (FSI) t FSI: »Particle production »Proton Loss t Non-QE processes can mimic QE t Possible modification of form factor »Projected to be a few percent (theoretical)  Thick targets cause: t Particle absorption

DNP Oct Quasi-elastic scattering  Signature is  p with no other final state particles and zero transverse momentum  If reaction occurs in nucleus – t Fermi momentum gives non-zero transverse momentum t FSI can give additional particles t 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 t Requires good background rejection

DNP Oct 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 Anticipated statistics on Axial FF 800 K QE on C 150 K QE on Fe and Pb Comparisons in low Q 2 better than 1% statistical uncertainty

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

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

DNP Oct  or  p events

DNP Oct Results  Efficiency is high in low Q 2 region (80-100%) t Nearly identical for C and Pb t Little energy dependence  Purity – decreases with Q 2 and neutrino energy t Remains above 70%, even for 10 GeV neutrino t C and Pb have similar Q 2 dependence, with Pb 5-10% less than C

DNP Oct 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