Giles Barr

Abstract:

We report the results of a search for νμ disappearance by the Main Injector Neutrino Oscillation Search. The experiment uses two detectors separated by 734 km to observe a beam of neutrinos created by the Neutrinos at the Main Injector facility at Fermi National Accelerator Laboratory. The data were collected in the first 282 days of beam operations and correspond to an exposure of 1.27×1020 protons on target. Based on measurements in the Near Detector, in the absence of neutrino oscillations we expected 336±14 νμ charged-current interactions at the Far Detector but observed 215. This deficit of events corresponds to a significance of 5.2 standard deviations. The deficit is energy dependent and is consistent with two-flavor neutrino oscillations according to |Δm2|=2.74-0.26+0.44×10-3eV2/c4 and sin 22θ>0.87 at 68% confidence level. © 2008 The American Physical Society.

Abstract:

Measurements of the double-differential π± production cross-section in the range of momentum 100 MeV/c p<∈800 MeV/c and angle 0.35 rad∈ θ<∈ 2.15 rad in proton-beryllium, proton-aluminium and proton-lead collisions are presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 GeV/c to 12.9 GeV/c hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was performed using a small-radius cylindrical time projection chamber (TPC) placed inside a solenoidal magnet. Incident particles were identified by an elaborate system of beam detectors. Results are obtained for the double-differential cross-sections d2σ/dpdθ at six incident proton beam momenta (3 GeV/c, 5 GeV/c, 8 GeV/c, 8.9 GeV/c (Be only), 12 GeV/c and 12.9 GeV/c (Al only)) and compared to previously available data. © 2008 Springer-Verlag / Società Italiana di Fisica.

Abstract:

Measurements of double-differential charged pion production cross-sections in interactions of 12 GeV/c protons on O2 and N2 thin targets are presented in the kinematic range 0.5 GeV/c ≤ pπ < 8 GeV/c and 50 mrad ≤ θπ < 250 mrad (in the laboratory frame) and are compared with p-C results. For p-N2 (p-O2) interactions the analysis is performed using 38576 (7522) reconstructed secondary pions. The analysis uses the beam instrumentation and the forward spectrometer of the HARP experiment at CERN PS. The measured cross-sections have a direct impact on the precise calculation of atmospheric neutrino fluxes and on the improved reliability of extensive air shower simulations by reducing the uncertainties of hadronic interaction models in the low energy range. In particular, the present results allow the common hypothesis that p-C data can be used to predict the p-N2 and p-O2 pion production cross-sections to be tested. © 2008 Elsevier B.V. All rights reserved.

Abstract:

A measurement of the double-differential π± production cross-section in proton-carbon, proton-copper and proton-tin collisions in the range of pion momentum 100 MeV/c p<800 MeV/c and angle 0.35 rad θ<2.15 rad is presented. The data were taken with the HARP detector in the T9 beam line of the CERN PS. The pions were produced by proton beams in a momentum range from 3 GeV/c to 12 GeV/c hitting a target with a thickness of 5% of a nuclear interaction length. The tracking and identification of the produced particles was done using a small-radius cylindrical time projection chamber (TPC) placed in a solenoidal magnet. An elaborate system of detectors in the beam line ensured the identification of the incident particles. Results are shown for the double-differential cross-sections d2σ/dpdθ at four incident proton beam momenta (3 GeV/c, 5 GeV/c, 8 GeV/c and 12 GeV/c). © 2007 Springer-Verlag / Società Italiana di Fisica.

Abstract:

The results of the measurements of the double-differential production cross-sections of pions, d2 σπ / d p d Ω, in p-C and π±-C interactions using the forward spectrometer of the HARP experiment are presented. The incident particles are 12 GeV/c protons and charged pions directed onto a carbon target with a thickness of 5% of a nuclear interaction length. For p-C interactions the analysis is performed using 100,035 reconstructed secondary tracks, while the corresponding numbers of tracks for π--C and π+-C analyses are 106,534 and 10,122, respectively. Cross-section results are presented in the kinematic range 0.5 GeV / c ≤ pπ < 8 GeV / c and 30 mrad ≤ θπ < 240 mrad in the laboratory frame. The measured cross-sections have a direct impact on the precise calculation of atmospheric neutrino fluxes and on the improved reliability of extensive air shower simulations by reducing the uncertainties of hadronic interaction models in the low energy range. © 2008 Elsevier B.V. All rights reserved.