B.T. Murdoch

Measurements of p-p and p-4He analyzing powers at medium energies

Abstract High precision proton-proton analyzing power measurements have been made at incident proton energies of 225, 327, and 520 MeV for θ lab = 17°, and at 205, 308, and 499 MeV for θ lab = 24°. The relative uncertainty is ± 1% for the results at 17° and ± 3% for the data at 24°. The p- 4 He analyzing power at θ lab = 15° was measured with ± 1–2% errors at 222, 325, and 518 MeV. These results can be used as accurate calibration standards for polarized proton beams and provide accurate polarization normalizations for phase shift analyses.

Large-angle measurements of the 4He(p, d) 3He reaction at intermediate energies☆

Abstract The differential cross section for the reaction 4 He (p, d) 3 He has been measured at incident proton energies of 275, 300, 350, 400, 440, and 500 MeV in the laboratory angular range between 144° and 168°. Polarization asymmetry has been observed served at 350, 400, and 500 MeV in the same angular range. The differential cross section is strongly backward peaked at all energies. The analyzing power is smaller than that for elastic p− 4 He elastic scattering. The differential cross section, similar in slope and magnitude to that for p− 3 He elastic scattering, indicates that deutron exchange may be the major component of the reaction mechanism.

Large angle cross section and analyzing power for proton-4he elastic scattering between 185 and 500 MeV

Abstract The differential cross section for the elastic scattering of protons from 4He has been measured for ten proton energies between 185 and 500 MeV in the angular range 144° to 168° in the lab system. The analyzing power has also been measured for seven energies in the same angular range. The differential cross section does not show the marked backward peaking that has been observed at both lower and higher energies. The possible structure in the 180° excitation function suggested for energies around 240 MeV is not observed. The analyzing power is large and negative, and shows strong dependence on both energy and angle.

A liquid 3He target system for use at intermediate energies

Abstract A liquid 3 He target system, with remote instrumentation and handling capabilities, has been developed for experiments using the 180–525 MeV TRIUMF cyclotron. 3 He gas is liquified, by means of a 4 He cryostat, into a cylindrical target cell (4.4 cm diameter, 1.6 cm thick) and maintained during operation at ∼1.6 K. This provides an areal target density of ∼2.7×10 22 3 He nuclei/cm 2 (128 mg/cm 2 ), suitable for intermediate energy proton scattering.

A liquid helium-4 target for intermediate energy nuclear physics

Abstract A liquid 4 He target with remote handling has been developed for experiments with the 180–252 MeV TRIUMF cyclotron. Interchangeable sample cells 0.5–2.0 cm thick are provided. Several proton beam experiments are in progress.

Quasifree p‐p scattering on 4He at 350 and 500 MeV

The 4He(p,2p)3H reaction was studied in a coplanar symmetric geometry at 350 MeV and 500 MeV using the proton beam of the TRIUMF cyclotron. At both incident energies we measured the energy sharing spectrum at the quasifree equal angles as well as the symmetric angular distribution. Out data resolve the discrepancy between the zero‐recoil cross sections measured at 460 MeV and at 590 MeV in favor of the 590 MeV SREL result. The excess of high‐momentum components in the 590 MeV angular distribution data, as compared to impulse approximation calculations, is confirmed and extrapolated to higher momenta.

Differential cross sections for p + /sup 3/He scattering from 19. 5 to 47. 5 MeV

Differential cross sections for /sup 3/He(p,p)/sup 3/He elastic scattering have been measured at 11 energies from 19.5 to 47.5 MeV. The most forward center-of-mass angle for the angular distributions varies from 10.1 to 13.4/sup 0/, and the most backward angle varies from 163.2 to 173.4/sup 0/. The relative errors are usually less than 2%, and the scale error is 1.5%. The present data and the existing vector-analyzing power and total-reaction cross-section data are being analyzed in this energy range using the Los Alamos Scientific Laboratory R-matrix code EDA.