Giles Barr

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 σ^π / 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.

Abstract:

The velocity of a ∼3GeV neutrino beam is measured by comparing detection times at the near and far detectors of the MINOS experiment, separated by 734 km. A total of 473 far detector neutrino events was used to measure (v-c)/c=5.1±2.9×10-5 (at 68% C.L.). By correlating the measured energies of 258 charged-current neutrino events to their arrival times at the far detector, a limit is imposed on the neutrino mass of mν<50MeV/c2 (99% C.L.). © 2007 The American Physical Society.

Abstract:

The 5.4 kton MINOS far detector has been taking charge-separated cosmic ray muon data since the beginning of August, 2003 at a depth of 207 m.w.e. in the Soudan Underground Laboratory, Minnesota, USA. The data with both forward and reversed magnetic field running configurations were combined to minimize systematic errors in the determination of the underground muon charge ratio. When averaged, two independent analyses find the charge ratio underground to be Nμ+/Nμ-=1.374±0.004(stat)-0.010+0.012(sys). Using the map of the Soudan rock overburden, the muon momenta as measured underground were projected to the corresponding values at the surface in the energy range 1-7 TeV. Within this range of energies at the surface, the MINOS data are consistent with the charge ratio being energy independent at the 2 standard deviation level. When the MINOS results are compared with measurements at lower energies, a clear rise in the charge ratio in the energy range 0.3-1.0 TeV is apparent. A qualitative model shows that the rise is consistent with an increasing contribution of kaon decays to the muon charge ratio. © 2007 The American Physical Society.