G. Roy

Information about the 12C(α,γ)16O reaction from the β-delayed proton decay of 17Ne

We are studying the β-delayed proton decay of 17Ne with the goal of determining the E2 part of the 12C(α,γ)16O cross section at energies relevant to helium burning in stars. We have determined branching ratios for proton and α-decay for states in 17F from 8.08 to 11.193 MeV. In addition, we have observed the break-up of the isobaric analogue state (IAS) at 11.193 MeV into three particles via two channels: proton decay to the 9.59 MeV state in 16O which breaks up into an α-particle plus 12C; and α-decay to the 2.365 MeV state in 13N which breaks up into a proton plus 12C. This is the first reported observation of the decay of the IAS to the 1− state in 16O at 9.59 MeV.

Complete Set of Deuteron Analyzing Powers in Deuteron-Proton Elastic Scattering: Measurement and Realistic Potential Predictions

Tensor analyzing powersiT11,T20,T21 andT22, have been measured for deuteron laboratory energiesElabd=75, 85, 95, 106, 119, 131, 144, 156, 172, and 187 MeV. The data are compared to rigorous Faddeev calculations with realistic nucleon-nucleon potentials. A generally good description of the data at all energies is obtained.

The design and calibration of the AHEAD deuteron polarimeter for 120 < Ed < 250 MeV

A new type of deuteron polarimeter to work in the energy range 120 < Ed < 250 MeV has been designed, constructed, and calibrated. The figure of merit (√ϵTkq) has been determined for various polarization components from the calibration data.

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.

A monitor of beam polarization profiles for the TRIUMF parity experiment

TRIUMF experiment E497 is a study of parity violation in pp scattering at an energy where the leading term in the analyzing power is expected to vanish, thus measuring a unique combination of weak-interaction flavor-conserving terms. It is desired to reach a level of sensitivity of 2×10−8 in both statistical and systematic errors. The leading systematic errors depend on transverse polarization components and, at least, the first moment of transverse polarization. A novel polarimeter that measures profiles of both transverse components of polarization as a function of position is described.

Results of 21Na+p experiments at ISAC

Abstract Several resonances in 22 Mg have been observed with a radioactive beam of 21 Na impinging on a hydrogen target at ISAC. Both elastic scattering as well as radiative capture have been investigated. Some results together with the experimental methods used will be reported.

Parity violation in proton-proton scattering

Abstract Measurements of parity-violating longitudinal analyzing powers (normalized asymmetries) in polarized proton-proton scattering provide a unique window on the interplay between the weak and strong interactions between and within hadrons. Several new proton-proton parity violation experiments are presently either being performed or are being prepared for execution in the near future: at TRIUMF at 221 MeV and 450 MeV and at COSY (Kernforschungsanlage Julich) at 230 MeV and near 1.3 GeV. These experiments are intended to provide stringent constraints on the set of six effective weak meson-nucleon coupling constants, which characterize the weak interaction between hadrons in the energy domain where meson exchange models provide an appropriate description. The 221 MeV is unique in that it selects a single transition amplitude ( 3 P 2 - 1 D 2 ) and consequently constrains the weak meson-nucleon coupling constant h ϱ pp . The TRIUMF 221 MeV proton-proton parity violation experiment is described in some detail. A preliminary result for the longitudinal analyzing power is A z = (1.1 ± 0.4 ± 0.4) × 10 −7 . Further proton-proton parity violation experiments are commented on. The anomaly at 6 GeV/c requires that a new multi-GeV proton-proton parity violation experiment be performed.

Investigation of the 12C(α, γ)16O reaction via the β-delayed proton decay of 17Ne

Abstract We have determined the branching ratios for the β-delayed proton decay of excited states in 17 F to excited states in 16 O by measuring proton-γ-ray coincidences. We have observed transitions to the 2 + state at 6.917 MeV in 16 O from 17 F states at 11.193, 10.0, 9.45, 8.83 and 8.44 MeV. In particular, the transition from the 9.45 MeV state is an order of magnitude stronger than the accompanying transitions to the 1 − state at 7.117 MeV and the 3 − state at 6.130 MeV, and seems a favourable case for the observation of 16 O break-up into α + 12 C .

The TRIUMF parity violation experiment

An experiment (E497) is underway at TRIUMF to measure the angle-integrated, parity violating longitudinal analyzing power, A{sub z}, in proton-proton elastic scattering, to a precision of {plus_minus}0.2{times}10{sup {minus}7}. The experiment uses a 221 MeV longitudinally polarized proton beam incident on a 40 cm liquid hydrogen target. The beam energy is carefully chosen so that the contribution to A{sub z} from the J=0 parity mixed partial wave ({sup 1}S{sub 0}{minus}{sup 3}P{sub 0}) integrates to zero over the acceptance of the apparatus, leaving the experiment sensitive mainly ({gt}95{percent}) to A{sub z} arising from the {sup 3}P{sub 2}{minus}{sup 1}D{sub 2}, J=2 wave. To minimize sources of systematic error, the TRIUMF ion source and cyclotron parameters have been refined to the extent that helicity correlated beam changes are at an extremely low level, and specialized instrumentation on the E497 beamline is able to measure residual helicity correlated modulations to a precision consistent with the goals of the experiment. A data taking run in February-March, 1997 logged approximately 12{percent} of the desired data and produced a preliminary result, A{sub z}=(1.1{plus_minus}0.4{plus_minus}0.4){times}10{sup {minus}7}, where the error is statistical only. {copyright} {ital 1997 American Institute of Physics.}