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Total and differential cross sections for {nu}{sub {mu}}{ital e}{r arrow}{nu}{sub {mu}}{ital e} and {bar {nu}}{sub {mu}}{ital e}{r arrow}{bar {nu}}{sub {mu}}{ital e} are measured. Values for the model-independent neutral-current couplings of the electron are found to be {ital g}{sub {ital V}}={minus}0.107{plus minus}0.035(stat){plus minus}0.028(syst) and {ital g}{sub {ital A}}={minus}0.514{plus minus}0.023(stat){plus minus}0.028(syst). The electroweak mixing parameter sin{sup 2}{theta}{sub {ital W}} is determined to be 0.195{plus minus}0.018(stat){plus minus}0.013(syst). Limits are set for the charge radius and magnetic moment of the neutrino as ({l angle}{ital r}{sup 2}{r angle}){lt}0.24{times}10{sup {minus}32} cm{sup 2} and {ital f}{sub {mu}}{lt}0.85{times}10{sup {minus}9} Bohr magnetons, respectively.

This paper describes the design criteria, construction, and performance of a detector to study neutral and charged current elastic neutrino interactions induced by neutrinos of average energy approximately 1 GeV from the Brookhaven National Laboratory Alternating Gradient Synchrotron.

Measurements of the semileptonic weak neutral-current reactions ..nu../sub ..mu../p..--> nu../sub ..mu../p and nu-bar/sub ..mu../p..-->..nu-bar/sub ..mu../p which yield the absolute differential cross sections dsigma(..nu../sub ..mu../p)/dQ/sup 2/ and dsigma(nu-bar/sub ..mu../p)/dQ/sup 2/ described. The weak-neutral-current parameter, sin/sup 2/theta/sub W/, is determined to be sin/sup 2/theta/sub W/ = 0.220 +- 0.016 (stat)/sub -0.031//sup +0.023/(syst).

A hierarchical, distributed intelligence data acquisition system which has been used for the past two years in neutrino experiments at Brookhaven National Laboratory is described. Performance characteristics and the nature of problems encountered in bringing the system to maturity are discussed and some generalizations of the experience are suggested.

The result of a measurement of sigma(..nu../sub ..mu../+e/sup -/..--> nu../sub ..mu../+e/sup -/) is presented. With use of neutrinos of mean energy 1.5 GeV from the Brookhaven National Laboratory alternating gradient synchrotron and a massive, active, high-resolution detector, a signal of 51 +- 9 events with a average signal-to-background ratio greater than 2:1 is observed. sigma(..nu../sub ..mu../e/sup -/..--> nu../sub ..mu../+e/sup -/) = (1.60 +- 0.29(stat) +- 0.26(sys)) E/sub ..nu../ (GeV) x 10/sup -42/ cm/sup 2/ is obtained.

Measurements have been made of the reactions ${\ensuremath{\nu}}_{e}$n\ensuremath{\rightarrow}${e}^{\mathrm{\ensuremath{-}}}$p and ${\ensuremath{\nu}}_{\ensuremath{\mu}}$n\ensuremath{\rightarrow}${\ensuremath{\mu}}^{\mathrm{\ensuremath{-}}}$p in a detector located an effective distance of 96 m from a neutrino source. These measurements yield directly the energy-dependent ratio of the neutrino fluxes [\ensuremath{\Phi}(E(${\ensuremath{\nu}}_{e}$))/\ensuremath{\Phi}(E(${\ensuremath{\nu}}_{\ensuremath{\mu}}$${))\phantom{\rule{0ex}{0ex}}]}_{\mathrm{obs}}$ incident on the detector. When combined with an estimate of the flux ratio emanating from the source [\ensuremath{\Phi}(E(${\ensuremath{\nu}}_{e}$))/\ensuremath{\Phi}(E(${\ensuremath{\nu}}_{\ensuremath{\mu}}$${))\phantom{\rule{0ex}{0ex}}]}_{\mathrm{calc}}$, the measured ratio provides an upper limit on the strength of mixing between ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${\ensuremath{\nu}}_{e}$. We obtain ${\mathrm{sin}}^{2}$2\ensuremath{\alpha}3.4\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}3}$ (90% C.L.) in the limit of large mass difference \ensuremath{\Delta}${m}^{2}$ (\ensuremath{\equiv}\ensuremath{\Vert}${m}_{1}$${}^{2}$-${m}_{2}$${}^{2}$\ensuremath{\Vert}) between neutrino mass eigenstates, ${m}_{1}$ and ${m}_{2}$; and an upper limit on the product \ensuremath{\Delta}${m}^{2}$ sin2\ensuremath{\alpha}0.43 ${\mathrm{eV}}^{2}$ in the limit of small mass difference.

The neutrino fluxes phi(E-italic(..nu../sub ..mu../)), phi(E-italic(nu-bar/sub ..mu../)), and phi(E-italic(..nu../sub e-italic/)) in the Brookhaven Alternating Gradient Synchrotron wide-band beams have been determined by measurements of quasielastic interactions observed in a massive, high-resolution detector. These fluxes are accurately reproduced by Monte Carlo calculations.

Measurements of the ratio R of the purely leptonic weak neutral-current cross sections sigma(..nu../sub ..mu../e..--> nu../sub ..mu../e)/sigma(nu-bar/sub ..mu../e..-->..nu-bar /sub ..mu../e) and of the absolute value of sigma(nu-bar/sub ..mu../e..-->..nu-bar/sub ..mu../e) are reported. These yield R = 1.38/sub -0.31//sup +0.40/(stat) +- 0.17(syst) and sigma(nu-bar/sub ..mu../e..-->..nu-bar/sub ..mu../e)/E..mu.. = (1.16 +- 0.20(stat) +- 0.14(syst)) x 10/sup -42/ cm/sup 2//GeV. This value of R determines the fundamental weak neutral-current parameter to be sin/sup 2/theta/sub W/ = 0.209 +- 0.029(stat) +- 0.013(syst).

This paper describes measurements of the semileptonic weak-neutral-current reactions $\ensuremath{\nu}_{\ensuremath{\mu}}p\ensuremath{\rightarrow}\ensuremath{\nu}_{\ensuremath{\mu}}p$ and $\overline{\ensuremath{\nu}}_{\ensuremath{\mu}}p\ensuremath{\rightarrow}\overline{\ensuremath{\nu}}_{\ensuremath{\mu}}p$ which yield the absolute differential cross sections $\frac{d\ensuremath{\sigma}(\ensuremath{\nu}_{\ensuremath{\mu}}p)}{d{Q}^{2}}$ and $\frac{d\ensuremath{\sigma}(\overline{\ensuremath{\nu}}_{\ensuremath{\mu}}p)}{d{Q}^{2}}$. The weak-neutral-current parameter, ${{sin}^{2}\ensuremath{\theta}}_{\mathrm{W}}$, is determined to be ${{sin}^{2}\ensuremath{\theta}}_{\mathrm{W}}=0.220\ifmmode\pm\else\textpm\fi{}0.016(\mathrm{stat}.)_{\ensuremath{-}0.031}^{+0.023}(\mathrm{syst}.)$.