Data Acquisition and Processing Techniques for Voltage Contrast Measurements

The effects of several data acquisition techniques on the accuracy of voltage contrast measurements are studied. In particular, the effect of using a voltage reference region directly connected to an external voltage source in performing the image intensity-to-voltage mapping of a node whose voltage is to be determined is examined. This is found to allow improved voltage measurement. The actual reference curves were obtained by least squares fitting the measured intensity-voltage reference data alternately to a quadratic and a cubic function. In addition, various mapping algorithms are considered including ones based alternately on the use of unprocessed, subtracted and normalized data. Using these techniques, one should expect voltage errors with means of approximately 25 mV and standard deviations of approximately 160 mV even with an unmodified commercial SEM incorporating no additional hardware to increase precision

Search for anti-neutrino induced muon+ e- events

The authors have examined 1200 interactions with visible energies greater than 7.5 GeV produced by an anti-neutrino beam in the Fermilab 15-foot bubble chamber filled with a light neon hydrogen mixture. They have found one event with a {mu}{sup +}e{sup -} and hadrons in the final state, but with no evidence of strange particle production. This event may be an example of dilepton production by an anti-neutrino interaction, but other interpretations are possible. With 90% confidence, they conclude that the rate for the process {bar {nu}} + N {yields} e{sup -} + {mu}{sup +} + hadrons is {le} .8% of charged current anti-neutrino interactions with visible energy > 7.5 GeV

pipi--pipi phase shifts in the energy region 0.6 to 1.42 GeV

Results are presented on pi - pi scattering via the reaction pi /sup +/n yields pi /sup +/ pi /sup -/p at 6 GeV/c. Using a one-pion exchange model modified by absorption and I = 2 phase shifts from other experiments S, P, and D wave pi - pi phase shifts were extracted under certain energy dependent assumptions. The data sample consists of approximately 13,000 events in the energy region 0.6 to 1.42 GeV. (auth

Measurement of y-Distributions for High Energy Antineutrino Scattering in Hydrogen-Neon

Distributions in the scaling variable y are presented based on a study of approximately 700 antineutrino events in the energy range 10-200 GeV obtained using the Fermilab 15-ft bubble chamber filled with a light Hydrogen-Neon mixture. The distributions are inconsistent with a (1 -y){sup 2} form predicted by the simple quark parton model of the nucleon without antiquarks, but can be well fitted assuming a relative antiquark contribution of (10 {+-} 5)%. For small values of the Bjorken scaling variable (x < 0.1) the y-distribution can be well fitted assuming a relative antiquark contribution of (20 {+-} 5)%. For events at small x in the energy range 30-200 GeV the y-distribution is in good agreement with the results reported by the HPWF group