P.W. Green

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.

Charge Symmetry Breaking innp→dπ0

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.

The neutron beam facility at triumf

Abstract The polarized neutron beam facility at TRIUMF has been upgraded for use in high precision neutron scattering experiments. Polarized neutrons are produced via transverse polarization transfer in the D(p,n)2p reaction at 9° in the lab. Proton beam position on the LD2 production target is stabilized to better than ±0.2 mm using a feedback system controlling beam line elements. The region of uniform neutron beam intensity at the experimental target location is a rectangular area 56 mm wide and 40 mm high. In that area the neutron beam intensity is 9 × 103 (100 nA cm2 s) and the neutron polarization is 50%. The facility is being used to determine charge symmetry breaking in n−p elastic scattering, to study neutron radiative capture by hydrogen, and a measurement of the spin correlation parameter Ann.

Detection equipment for a test of charge symmetry in n−p elastic scattering☆

Detection equipment has been developed to allow precision measurements of n−p elastic scattering of 150 to 500 MeV polarized neutron beams at TRIUMF. The apparatus permits a determination of the difference in angle, ‡θ, at which the neutron and proton analyzing powers An and Ap cross zero with a precision of ±0.04° lab at 500 MeV. From this difference in ‡θ the difference between An and Ap can be obtained to a precision of ±0.001.

A beam intensity profile monitor based on secondary electron emission

Two dual function intensity profile monitors have been designed for a measurement of parity violation in p-p scattering at about 230 MeV using longitudinally polarized protons. Each device contains a set of split secondary electron emission (SEM) foils to determine the median of the beam current distribution (in x and y). The split foils, coupled through servoamplifiers and operational amplifiers to upstream aircore steering magnets, have demonstrated the ability to hold the beam position stable to ±5 μm for beam position fluctuations up to 1000 Hz. These monitors also contain a set of foil strip planes giving information on the intensity distribution projected onto the two orthogonal axes, x and y. Data were acquired using 0.008 mm thick, 0.90 mm wide aluminum foil strips at 1.00 mm centers. The foil strip planes were able to determine the beam centroid to within ±3 μm after one hour of data taking with a 100 nA, 15 mm FWHM Gaussian beam.

Proton target polarization measured with a polarized neutron beam at 477 MeV

Abstract The polarization of a proton target is determined with elastic neutron-proton scattering at 477 MeV. The results agree well with the nuclear magnetic resonance measurements at the error level of 4%.

Parity violation in P‐P scattering at TRIUMF

The TRIUMPF experiment 497 which will measure the (weak) parity violating component of the nucleon‐nucleon interaction with proton‐proton quasi‐elastic scattering at 223 MeV is described. The longitudinal analyzing power Az=(σ+−σ−)/(σ++σ−) where σ+ and σ− are the scattering cross sections for positive and negative beam helicity, respectively, with an expected precision of ±2×10−8. (AIP)

Parity violation in p-p scattering

Abstract An outline is given of an experiment to measure parity violation in p-p scattering at 230 MeV at TRIUMF. The parity-violating longitudinal analysing power A z will be measured to a precision of 2×10 −8 and will isolate the parity-violating 3 P 2 − 1 D 2 partial wave amplitude.

The Saskatchewan-Alberta large acceptance detector for photonuclear physics

Abstract The Saskatchewan-Alberta Large Acceptance Detector (SALAD) is a 4 π detector designed and built for studies of photonuclear reactions with a tagged photon beam. The design and performance of the detector are described. Its characteristics have been studied by examining p-p elastic scattering with a proton beam at TRIUMF.

Quasi‐elastic scattering of polarised protons at 300 MeV

Earlier measurements of the /sup 40/Ca(p vector,2p) reaction at 200 MeV incident energy have been extended to 300 MeV using the TRIUMF polarized proton beam. The angles and energies of both outgoing protons were measured, one being detected in a magnetic spectrometer and the other in a NaI(T) scintillation crystal. Measurements were made in two geometries, in one of which the angles of the outgoing protons were close to equality and the other in which they were very unequal. Values of cross section and analyzing powers for the knockout of protons for ld/sub 3/2/, 2s/sub 1/2/, ad ld/sub 5/2/ shells in /sup 40/Ca were obtained and are compared to DWIA calculations incorporating spin orbit terms in the optical potentials, and also to calculations using optical potentials derived from a relativistic approach based on the Dirac equation. 1 reference.