P. Marmier

Investigation of excited states of 4He via the 2H(d, p)3H and 2H(d, n)3He reactions using a polarized deuteron beam

Abstract The differential cross section σ 0 (θ) and the analysing powers iT 11 ( θ ), T 20 ( θ ), T 21 ( θ ) and T 22 ( θ ) of the reactions 2 H(d, p) 3 H and 2 H(d, n) 3 He have been measured. The 2 H(d, p) 3 H reaction was measured at 9 energies between 3.0 and 11.5 MeV at lab angles between 7.5° and 160°. The reaction 2 H(d, n) 3 He was measured at 10.0 and 11.5 MeV at c.m. angles ranging from 95° to 156°. The results were fitted with Legendre polynomials and the resulting coefficients analysed for possible resonances in 4 He. Differences in the analysing powers between the 2 H(d, p) 3 H and the 2 H(d, n) 3 He reactions can be explained by Coulomb effects.

Phase-Shift Analysis of p-d Elastic Scattering

Abstract Phase shifts for p-d elastic scattering were extracted from the differential cross sections, proton polarization, vector and tensor analysing powers of the 1 H(d, d) 1 H scattering between E d = 6.0 and 11.5 MeV. Good fits to all the experimental data analysed could be obtained if, in the analysis, all physically expected degrees of freedom such as the splitting of phase shifts, mixing of states of different orbital angular momentum and non-conservation of channel spin were allowed. The angular momenta were restricted to L ≦ 4. The results are discussed and the influence of splitting and mixing on the observables are investigated. The Wolfenstein parameters of the proton scattering are predicted for the present solution and their insensitivity to changes in the phase shifts and mixing parameters is shown.

The differential cross section and the analysing powers iT11,T20,T21 and T22 of the reaction 3He(d, p)4He between 2.8 and 11.5 MeV

Abstract The differential cross section σ 0 (θ) and the analysing powers iT 11 ( θ ), T 20 ( θ ), T 21 ( θ ) and T 22 ( θ ) of the reaction 3 He(d, p) 4 He have been measured for 7 energies between 2.8 MeV and 11.5 MeV at lab angles between 0° and 160°. The results were fitted with Legendre polynomials. The energy dependence of the resulting Legendre coefficients indicate resonance-like behaviour at energies corresponding to excitations of 16.6 MeV, 17.5 MeV, 20.0 MeV, 20.9 MeV and 22.4 MeV in 5 Li. The reaction 3 He(d, p) 4 He is an excellent analyser for deuteron vector and tensor polarization when specific angles for the different analysing power are chosen.

Phase-shift analysis of d-α elastic scattering

Phase shifts of angular momenta l ≦ 3 for d-α elastic scattering were extracted from differential cross sections and the vector and tensor analysing powers of the 4He(2He(d→,d)4He scattering between 3 and 11.5 MeV. Good fits to all the experimental data analysed could be obtained and the total reaction cross section correctly predicted. Continuous extension of the phase shifts to lower and higher energies is possible, and the P-wave phase shifts are well fixed by the analysed data. Single-level parameters of the 2+ and 1+ (T = 0) resonances were determined. The coupling between the S- and D-waves for J = 1 was found to be very small. No alternative solution could be found from the data used in this analysis.

The 3He(d, p)4He reaction at 0° as an analyser for tensor polarized deuterons

Abstract The tensor analysing power T 20 of the 3 He(d, p) 4 He reaction has been measured at π = 0° between 2 and 11.2 MeV. This reaction shows excellent properties as an analyser for tensor polarized deuteron beams.

Direct determination of a short nuclear lifetime (≈10−20s) by the proximity scattering method

Abstract A nuclear reaction with three outgoing particles can proceed in two sequential stages, one of the product particles (R) of the first step being unstable. Under certain conditions, two of the three particles in the final state can undergo a further nuclear (“proximity scattering”). The probability for such a process to occur depends on the lifetime of the unstable particle R, as shown by a simple classical analysis. A quantal estimate of the proximity scattering cross section is presented and an experiment described in which the correlations between the protons and neutrons of the reaction 12C(d, pn)12C at a deuteron energy of 5.39 MeV were measured. A lifetime of τ = 0.7 × 10−20s can be assigned to the level group at 3.5 MeV in 13N.

Absolute calibration of tensor analysing powers of the 3He(d, p)4He and the 4He(d, d)4He reactions

Abstract The tensor analysing power T 20 of 3 He(d, p) 4 He has been calibrated absolutely at θ lab = 0° and E d = 6.49 and 9.30 MeV with the 16 O ( d , α 1 ) 14 N ∗ reaction. These measurements have been used to calibrate T 20 and T 22 in 4 He(d, d) 4 He elastic scattering absolutely at two corresponding energies and θ lab = 30°, 60° and 75°.

The analysing powers iT11, T20, T21 and T22 in deuteron-deuteron elastic scattering between 6 and 11.5 MeV

Abstract The angular distributions of the analysing powers iT 11 ( θ ), T 20 ( θ ), T 21 ( θ ) and T 22 ( θ ) of the elastic scattering of polarized deuterons on deuterons have been measured at deuteron energies of 6.0, 8.0, 10.0 and 11.5 MeV. The vector component has small but non-zero values which change sign between 6.0 and 10.0 MeV. The tensor components have increasing values with increasing energy. The results are discussed in respect of resonances in 4 He and a term scheme is proposed for a complete phase-shift analysis.

Measurement of the analysing powers iT11, T20, T21 and T22 in elastic deuteron-proton scattering

Abstract The analysing powers iT 11 , T 20 , T 21 and T 22 for the elastic scattering of polarized deuterons by protons have been measured at deuteron energies of 6, 8, 10 and 11.5 MeV with the polarized deuteron beam from a tandem accelerator. The measurements cover the c.m. angular range from 40° to 155° and show small but non-zero analysing powers at all energies.

Energy dependence of proximity scattering

Abstract The dependence of proximity scattering on the energy of the incident particles has been investigated in the reaction 7 Li(d, nα) 4 He.