G. V. O'Rielly

Charge symmetry breaking in np-->dpi(0).

The forward-backward asymmetry in np-->dpi(0), which must be zero in the center-of-mass system if charge symmetry is respected, has been measured to be [17.2+/-8.0(stat)+/-5.5(syst)]x10(-4), at an incident neutron energy of 279.5 MeV. This observable is compared to recent chiral effective field theory calculations, with implications regarding the du quark mass difference.

Apparatus for a measurement of charge symmetry breaking in np→dπ0☆

Abstract TRIUMF experiment E704 is a study of Charge Symmetry Breaking in the reaction np→dπ 0 . The observable is the forward–backward asymmetry in the centre-of-mass differential cross-section, predicted to be −0.0035 at 5 MeV above threshold. As a check on the understanding of certain systematic effects the reaction pp→dπ + , which cannot have an asymmetry, is measured also. Similarly, neutron–proton elastic scattering is used to verify spectrometer acceptance. We describe the beams, target, and detectors developed for this experiment.

Reaction mechanisms in {sup 12}C({gamma},{ital pp}) near 200 MeV

Inclusive {sup 12}C({gamma},{ital pp}) cross sections have been measured with tagged photons in the range {ital E}{sub {gamma}}=187{endash}227 MeV using the Saskatchewan-Alberta Large Acceptance Detector (SALAD). The large angular acceptance allowed the measurement of noncoplanar {ital pp} emission. The cross sections were compared to a Monte Carlo intranuclear cascade calculation. Agreement was reasonable for the shapes of the cross sections but the calculated total cross section was 3.9 times larger than the data. {copyright} {ital 1996 The American Physical Society.}

Deexcitation gamma rays following the photodisintegration of 17O.

Bremsstrahlung-weighted integrated cross sections for photoproton and photoneutron emission from /sup 17/O to excited residual states in /sup 16/N and /sup 16/O have been measured by detecting the deexcitation ..gamma.. rays emitted from these states in the residual nuclei. The results are compared with the previously reported /sup 17/O(..gamma..,/ital p/) and /sup 17/O(..gamma..,/ital n/) cross sections. About 90% of photoproton emission from /sup 17/O populates the ground-state (2/sup /minus//) and the 0.298-MeV (3/sup /minus//) level in /sup 16/N. It is concluded that this is the result of a single-particle excitation and emission process. The remaining photoproton emission, leading to the 0.120-MeV (0/sup /minus//) and 0.397-MeV (1/sup /minus//) levels, occurs during the preequilibrium stage or from the compound nucleus. The results further indicate that these decay fractions are approximately independent of excitation energy in /sup 17/O. For the /sup 17/O(..gamma..,/ital n/)/sup 16/O reaction, the results show that emission to bound states in /sup 16/O is predominantly to the /sup 16/O ground state (0/sup +/), with 4% of the decay from the /sup 17/O giant dipole resonance going to the 6.13-MeV (3/sup /minus//) excited state; population of other bound states is not observed.