501 research outputs found

    The Design, Construction, and Performance of a Magnetic Focusing, Semi-Circular, Low Energy Beta-Ray Spectrometer

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    A semi-circular beta-ray spectrometer (Fig. 1) has been constructed for operation between 2 and 120 kev electron energy. This instrument was designed to supplement the ring- focusing beta-ray spectrometer whose lower limit is approximately 25 kev. The 180° spectrometer has an electron trajectory radius of 12 cm. The field is produced by two iron free coils spaced to give a nearly homogeneous field (with some second order focusing) in the region of the electron trajectories . The field current is supplied by a one kw motor- generator set. Stabilization is obtained to 2 parts in 10, 000 with a rotating electro- mechanical unit and an electronic servo system. Source and Geiger counter window dimensions for a standard resolution of 0 .8% are 0.1 cm x 4 cm. With a 10 μ.g/cm^2 formvar window, transmission is assured down to 2 kev electron energy. A recording potentiometer traces the counting rate vs. electron energy. Several examples of chart recordings are reproduced to illustrate the performance of the semi- circular beta-ray spectrometer

    Investigations of fast neutron production by 190 GeV/c muon interactions on different targets

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    The production of fast neutrons (1 MeV - 1 GeV) in high energy muon-nucleus interactions is poorly understood, yet it is fundamental to the understanding of the background in many underground experiments. The aim of the present experiment (CERN NA55) was to measure spallation neutrons produced by 190 GeV/c muons scattering on carbon, copper and lead targets. We have investigated the energy spectrum and angular distribution of spallation neutrons, and we report the result of our measurement of the neutron production differential cross section.Comment: 19 pages, 11 figures ep

    Determination of Strong-Interaction Widths and Shifts of Pionic X-Rays with a Crystal Spectrometer

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    Pionic 3d-2p atomic transitions in F, Na, and Mg have been studied using a bent crystal spectrometer. The pionic atoms were formed in the production target placed in the external proton beam of the Space Radiation Effects Laboratory synchrocyclotron. The observed energies and widths of the transitions are E=41679(3) eV and Γ=21(8) eV, E=62434(18) eV and Γ=22(80) eV, E=74389(9) eV and Γ=67(35) eV, in F, Na, and Mg, respectively. The results are compared with calculations based on a pion-nucleus optical potential

    Results from the Palo Verde neutrino oscillation experiment

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    The ν̅e flux and spectrum have been measured at a distance of about 800 m from the reactors of the Palo Verde Nuclear Generating Station using a segmented Gd-loaded liquid scintillator detector. Correlated positron-neutron events from the reaction ν̅ep→e+n were recorded for a period of 200 d including 55 d with one of the three reactors off for refueling. Backgrounds were accounted for by making use of the reactor-on and reactor-off cycles, and also with a novel technique based on the difference between signal and background under reversal of the e+ and n portions of the events. A detailed description of the detector calibration, background subtraction, and data analysis is presented here. Results from the experiment show no evidence for neutrino oscillations. ν̅e→ν̅x oscillations were excluded at 90% C.L. for Δm2>1.12×10-3 eV2 for full mixing and sin22θ>0.21 for large Δm2. These results support the conclusion that the observed atmospheric neutrino oscillations do not involve νe
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