Incoming energy crucial for your physics result, but only badly known (~50%) Incoming energy crucial for your physics result, but only badly known (~50%) Beam composition not fully known Beam composition not fully known Beam diameter ~ 0.5 m at its source Beam diameter ~ 0.5 m at its source Beamline ~ 300 – 1000 km Beamline ~ 300 – 1000 km Beam diameter ~ 600 m at the detector Beam diameter ~ 600 m at the detector Cross sections ~ mb Cross sections ~ mb Only a small part of the final state known Only a small part of the final state known Winter Park 2011 The Impossible Experiment

Tina Leitner, Oliver Buss, Ulrich Mosel Neutrino Interactions with Nucleons and Nuclei TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAAAAAAAAAA Winter Park 2011

1300 km Winter Park 2011 Soudan Mine, Nova 770 km Homestake Mine Dusel Long Baseline Experiments T2K: JPARC-Kamioka ~ 300 km, OPERA: CERN –Gran Sasso ~730 km

Long baseline experiments M. Wascko Winter Park 2011

Neutrino oscillation search neutrino oscillations: probability for 2 flavors: neutrino oscillations: probability for 2 flavors: Crucial parameter: neutrino energy E Crucial parameter: neutrino energy E Need to understand ‚classical‘ hadronic interactions Flux: obtained from Event-Generators for hadronic production and subsequent weak decay Energy must be reconstructed from hadronic final state Winter Park 2011

Neutrino nucleon cross section QE P. Lipari, Nucl. Phys. Proc. Suppl. 112, 274 (2002) cm² = mb R+R+ ¼ N N' ‚ DIS Winter Park 2011 QE is used for energy reconstruction

Quasielastic scattering axial form factors F A  F P and F A (0) via PCAC dipole ansatz for F A with M A = 1 GeV: W, Z Winter Park 2011

Axial Formfactor of the Nucleon neutrino data agree with electro-pion prod. data neutrino data agree with electro-pion prod. data Winter Park 2011 M A ¼ 1.02 GeV world average M A ¼ 1.07 GeV world average

Axial Formfactor of the Nucleon Recent Data give significantly larger values for M A Recent Data give significantly larger values for M A One difference: all old data use H (or D) as target One difference: all old data use H (or D) as target all new data use nuclei (C, O, Fe) as target all new data use nuclei (C, O, Fe) as target MiniBooNE (2010): M A = 1.35 GeV Winter Park 2011

M A Problem Old neutrino experiments used H and D as targets Old neutrino experiments used H and D as targets All modern experiments use heavy nuclei All modern experiments use heavy nuclei Quasielastic scattering kinematics is used to reconstruct neutrino energy also in oscillation experiments Quasielastic scattering kinematics is used to reconstruct neutrino energy also in oscillation experiments Problem to identify QE on nuclear targets Problem to identify QE on nuclear targets Winter Park 2011

QE Identification Winter Park 2011 Need event generator to reduce data to true QE event

 what is GiBUU? semiclassical coupled channels transport model  general information (and code available):  GiBUU describes (within the same unified theory and code) heavy ion reactions, particle production and flow heavy ion reactions, particle production and flow Pion, proton and antiproton induced reactions Pion, proton and antiproton induced reactions low and high energy photon and electron induced reactions low and high energy photon and electron induced reactions neutrino induced reactions neutrino induced reactions ……..using the same physics input! And the same code! Winter Park 2011 GiBUU transport

Winter Park 2011 CC nucleon knockout:  56 Fe   - N X w FSI w/o FSI E = 1 GeV Dramatic FSI Effect

Detector Types: QE Identification Winter Park 2011 Tracking detector (Sci-BooNE, K2K, SciFi) Cerenkov detector (MiniBooNE, K2K 1kt) Too high QE: misidentifies about 20%, pion-induced fakes QE identification is clean, but 30% of total QE cross section is missed measured

Detector Sensitivities Winter Park 2011 K2K SciFi Example: SciFi sees only 50% of total QE cross section. MiniBooNE sees 20% too much QE Experiments need major corrections from event generators

Detector Sensitivities: T2K Winter Park 2011 T2K has different detector types: 1.Tracking for near detector 2.Cherenkov for far detector Near Detector sees only about 50% of all QE events

Energy Reconstruction and Detector Thresholds Winter Park 2011 Energy reconstruction sensitive to the detector pion thresholds

Energy reconstruction via CCQE Winter Park 2011 Rms energy deviations S ~15% energy uncertainty from quasifree qe kinematics alone ~21% uncertainty for Cerenkov detectors, error grows with neutrino energy ~16% uncertainty for tracking detectors Errors in reconstructed º energies larger than expected

Energy reconstruction via CCQE Energy uncertainties affect mixing masses, Event identification affects mixing angles Winter Park 2011

± CP with LBNE Winter Park 2011 Event reconstruction hampers determination of CP violating phase Wilson, LBNE workshop Uncertainties at the oscillation maximum due to detector as large as dependence on CP violating phase

Experiments have to rely heavily on event-generators to identify QE events needed for energy reconstruction Experiments have to rely heavily on event-generators to identify QE events needed for energy reconstruction Quasielastic scattering events contain admixtures of Delta excitations Quasielastic scattering events contain admixtures of Delta excitations  excitations affect nucleon knockout, contaminate QE experiments  excitations affect nucleon knockout, contaminate QE experiments Energy reconstruction good up to 15 – 20%. Combined error from near and far detectors ~ 20 – 30%. Experiments Energy reconstruction good up to 15 – 20%. Combined error from near and far detectors ~ 20 – 30%. Experiments want 5%! Challenge for event generators! want 5%! Challenge for event generators!  Extraction of axial mass (1 GeV) strongly affected by nuclear structure (RPA correlations), difficult to get both absolute height and slope. both absolute height and slope. Winter Park 2011 Physics Summary

Winter Park 2011 Low-Energy Nuclear Physics determines response of nuclei to neutrinos  Need excellent event generators To extract fundamental science Need for Low Energy Nuclear Physics in Neutrino Physics