This paper gives the results of a study of single-pion production by the weak charged current utilizing the wide-band muon-type-neutrino beam at the Argonne Zero Gradient Synchrotron. The data were obtained from hydrogen and deuterium fillings of the 12-ft bubble chamber. The methods of event selection and separation from background are given as are the details of the corrections and systematic effects in the data sample. The energy-dependent cross sections and differential distributions are presented for the three single-pion production reactions vp -p p y + , vn +p and vn -p -n r f . An isospin decomposition shows that the ratio of I = , to I = amplitudes is 0.68k0.04 with a relative phase of (90.7k4.6)" for M ( N a ) < 1.4 GeV. This agrees with theoretical models, particularly the detailed calculation of Adler. Using the data of the reaction vp -p-pa+, the characteristic mass of the nucleon axial-vector elastic form factor is measured to be 0.98' ::;GeV when analyzed within the context of the Adler model. The data are also compared to other parametrizations of the nucleon axial-vector form factor.
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This paper gives a detailed description of an experiment which studies the interactions of muon-type neutrinos in hydrogen and deuterium. The experiment was performed at the Zero Gradient Synchrotron using the wide-band neutrino beam incident on the Argonne 12-foot bubble chamber filled with hydrogen and deuterium. The neutrino energy spectrum peaks at 0.5 GeV and has a tail extending to 6 GeV. The shape and intensity of the flux is determined using measurements of pion yields from beryllium. The produced pions are focused by one or (for the latter part of the experiment) two magnetic horns. A total of 364000 pictures were taken with a hydrogen filling of the bubble chamber and 903000 with a deuterium filling. The scanning and other analyses of the events are described. The most abundant reaction occurs off neutrons and is quasi-elastic scattering vd +p-pp,. The separation of these events from background channels is discussed. The total and differentla] cross sections are analyzed to obtain the axial-vector form factor of the nucleon. Our result, expressed in terms of a dipole form factor, gives an axial-vector mass of 0.95 k 0 . 0 9 GeV. A comparison is made to previous measurements using neutrino beams, and also to determinations based upon threshold pion electroproduct~on experiments. In addition, the data are used to measure the weak vector form factor and so check the conserved-vector-current hypothesis.
This paper reports a determination of the axial-vector form factor of the nucleon using the momentum-transfer distribution for 1737 events of the type vPd+p-pps. The events were obtained from a 2 . 4~ lo6-frame exposure of the Argonne 12-foot bubble chamber to a neutrino beam at the Argonne Zero Gradient Synchrotron. After fitting and applying selection criteria, the background was estimated to be at the 2% level. The axial-vector mass in the dipole parametrization was measured to be MA = 1.00k0.05 GeV/c2, in good agreement both with earlier measurements from this experiment and with other recent results. A test of the conserved-vector-current hypothesis, made by simultaneously fitting MA and M v using dipole form factors, gave MA =0.80+0.10 GeV/c2 and MV=0.96 k0.04 Gev/c2.
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