We report a result of (1 ±4) xlO" 7 for the parity-nonconserving component in the p-p nuclear cross section at 15 MeV. Our experiment uses rapid spin reversal of a longitudinally polarized proton beam and an unpolarized H 2 target. Sources of systematic error are discussed and found to be <10" 7 .
The design and operation of resonant linear accelerator tanks suitable for use in high energy proton and electron linacs is described. It is shown that construction of these tanks to operate in the π/2 mode yields systems with extraordinary field stability. Theoretical expressions and corresponding experimental observations are obtained for the behavior of cavity chains operating in the π/2 mode. The synthesis of the side coupled cavity chain, a biperiodic chain which combines high acceleration efficiency with π/2 mode field stability, is described. Extensions of π/2 mode operation to nonperiodic chains is also demonstrated.
A parity-nonconserving asymmetry in the total cross section for 6-GeV/c polarized protons on a water target has been measured. The experiment used two independent detector systems to measure the helicity dependence of the transmission through the target. Special attention was paid to possible sources of systematic errors. The result is A,is the fractional difference of the total cross sections for positive-and negative-helicity protons on an unpolarized target. The first error is statistical and the second is an estimate of systematic uncertainties. This result is much larger than predictions based on mesonexchange calculations but consistent with a recent QCD calculation.-
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