R. Risler

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.

Absolute calibration of the analysing powers T20 for the 3He(d,d, p)4He reaction at 0° and iT11 for 4He(d,d,d)4He scattering

Abstract The tensor analysing power T 20 for the 3 He ( d , p ) 4 He reaction at 0° has been measured between 0.34 and 11.60 MeV. Absolute calibrations of the measurements have been carried out at 6.69 MeV with the aid of the 16 O d ,α 1 14 N ∗ reaction and at 3.92 and 11.56 MeV with the 4 He ( d , d ) 4 He scattering. Excitation functions of the vector analysing power iT11 for d-α elastic scattering have been measured between 2.38 and 13.60 MeV at θlab = 37.5° and 45° and calibrated absolutely at 4.57 and 11.88 MeV.

Investigation of analysing power maxima in d-α elastic scattering

Abstract An investigation of the conditions for which the vector analysing power or a component of the tensor analysing power reaches its theoretical maximum value has been carried out. For d-α elastic scattering, a search for Ayy = 1 and Ay = −1 was made with the aid of a phase shift analysis. Three such points for Ayy and one possible point for Ay were found in the energy range between 3 and 17 MeV. The precise energies and angles for the maxima of Ayy were found experimentally using an interpolation method. The practical interest in using the results to calibrate polarized deuteron beams is discussed. A time reversal invariance test in connection with the findings of this investigation is proposed.

Investigation of the 1+ resonance in 6Li by d-α scattering between 6 and 7 MeV

Abstract Previous analyses of d- 4 He elastic scattering have established the presence of a 1 + resonance near 5.7 MeV excitation energy in 6 Li. The energy dependence of the s-wave to d-wave mixing parameter through this resonance gives an indication of the tensor force contributing to the interaction. In this work, we have made a detailed study of this parameter by obtaining complete angular distributions of the differential cross section and all four analyzing powers for 4 He(d, d) 4 He at seven energies between 6 and 7 MeV. The phase-shift analysis of these data provides a detailed parameterization to compare with theoretical calculations and shows for the first time the necessity for a complex mixing parameter. An R -matrix fit to the phase shifts establishes more precisely the location and width of the resonance.

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.

Global optical-model analysis of the elastic deuteron scattering from medium heavy target nuclei

Abstract Angular distributions for the cross section and the analyzing powers iT 11 , T 20 , T 21 and T 22 in the angular range 20°–175° (lab) have been measured for 12 MeV deuterons scattered elastically from several medium-heavy, spin-zero target nuclei. The data have been analysed using an optical model including complex spin-orbit and tensor terms. With a few exceptions, excellent fits have been obtained to all the measured quantities, yielding a set of global parameters. The depths of the central part of the optical potentials are correlated and depend on the structure of the target nuclei. Contrary to the results for selenium, which exhibit clear shell-closure effects that are well reproduced by optical-model calculations, the data for N = 28 nuclei were found to be very difficult to describe. Irregularities in the optical-model parameters and problems in fitting the measurements are discussed. Possible ways of improving the theoretical description of deuteron scattering are suggested.

A study of the highly excited six nucleon system by elastic d-α scattering with polarized deuterons between 17 and 43 MeV

Abstract Angular distributions of the vector analyzing power A y and the tensor components A y and A xx were measured in the energy range between 17.0 and 42.8 MeV in energy steps of 4 to 5 MeV. These results have been calibrated absolutely. A possible A yy = 1 point was found near 35 MeV and 150° in the c.m.s. The results are discussed and compared with predictions of resonating-group calculations and three-body Faddeev calculations with different interactions.

Investigation of a polarized neutral atomic beam

Abstract An atomic beam apparatus producing a polarized neutral atomic beam is described. The beam intensity, its diameter and the mean velocity of the atoms are measured. The results of the investigation of the dependence of various parameters are presented. The results are used to optimize all parameters involved. An optimum atomic beam intensity of 1.8 × 10 16 atoms per second is measured within a beam diameter of 10 mm.

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°.