H.R. Bürgi

Determination of the asymptotic d-state normalization of the deuteron

Abstract New data for the tensor polarization in dp scattering at E d = 10 and 20 MeV are analyzed to determine the asymptotic D-state normalization ϱ D of the deuteron wave function. Multiplying the tensor polarization by the cross section we achieve stable extrapolations to the nucleon pole with the result ϱ D = 0.027 ± 0.005.

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.

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.

Shell closure effects in the elastic scattering of polarized deuterons

Abstract An enhancement of the analysing powers i T 11 ( θ ) and T 20 ( θ ) with increasing nuclear mass of the target nuclei is reported for 76,78,80,82 Se ( d , d ) elastic scattering at 12 MeV. Shell closure effects are proposed to account for this effect.

Phase-shift analysis of 3He(d, d)3He scattering

Abstract Between 0.32 and 5.0 MeV deuteron energy a phase-shift analysis of 3He(d, d)3He crosssection and deuteron analyzing-power data has been made. Expressions relating the analyzing powers to the scattering amplitudes are derived and an energy-independent parametrization of threechannel scattering matrices is given. The analysis includes spin-orbit splitting, mixing of states and loss of flux to reaction channels. Excellent fits have been obtained. However, the data set has proved to be too incomplete to permit a unique determination of the relevant parameters. At low energies continuum ambiguities have been found and explored. Common properties of the solutions point to the existence of several broad highly excited states of the 5Li nucleus.

Investigation of charge symmetry violation in the mirror reactions 2H(d, p)3H and 2H(d, n)3He

Abstract Precision measurements of the angular distributions of the vector and the three tensor analysing powers of the mirror reactions 2 H(d, p) 3 H and 2 H(d, n) 3 He are compared betwen 1.5 and 15.5MeV incident deuteron energy. Large and complex differences are observed over the whole energy range. After applying approximate Coulomb corrections, the discrepancies are essentially constant above 4 MeV deuteron energy. Although at present calculations which treat the Coulomb interaction in an exact way cannot be made, there is strong evidence for charge symmetry violation in these mirror reactions.

A study of the elastic scattering of polarized deuterons from 60Ni and 90Zr nuclei

Abstract Five quantities, σ 0 , iT 11 , T 20 , T 21 and T 22 , have been measured for the elastic ( d , d) scattering from 60 Ni at 9 and 12 MeV and from 90 Zr at 10, 11 and 12 MeV over a wide angular range. Excitation functions for σ 0 and T 20 have been also measured at an angle of 175°(lab) in the approximate energy range of 6–13 MeV for both target isotopes. The experimental results, together with similar data published earlier for 15 MeV have now been analysed using the optical model with the complex central, spin-orbit and tensor T R potentials. Excellent fits are obtained for the angular distributions for all five measured quantities. The main features of the excitation functions are also well reproduced. Five of the optical-model parameters can be fixed. Three other parameters can be constrained by simple mass dependence functions. Further evidence for the presence of an imaginary component of the spin-orbit potential is supplied by the analysis of the present data.

Investigation of optical model parameters for deuteron elastic scattering from 40Ar

Abstract Differential cross sections, vector and tensor analysing powers of deuterons elastically scattered by 40 Ar at 9.0, 10.75 and 12.0 MeV have been measured. The results have been analysed in terms of an optical potential containing complex central, spin-orbit and tensor terms. It is found that not only could all five observables be fitted very well but the parameters found also give excellent predictions for the excitation function of the cross section and T 20 at 175°, as well as for the 15 MeV vector analysing power data.

Deuteron optical model analysis

Abstract Differential cross sections and vector and tensor analysing powers of deuterons elastically scattered by 40 Ar, 40 Ca and 60 Ni have been analysed in terms of an optical potential containing tensor terms. The effect of two optical potential tensor terms on the various analysing power components have been investigated. It was found that the quantity T 20 at 180° is particularly sensitive to the optical potential tensor parameters. Although the differential cross section and the vector analysing power data were already well reproduced without any tensor interactions in the optical potential, the inclusion of tensor terms improved greatly the fits to the tensor analysing power data, resulting in a fairly satisfactory agreement.

Analyzing power measurements in deuteron-proton elastic scattering

Abstract The vector and tensor analyzing powers for deuteron-proton elastic scattering have been measured at 3.0, 5.0, 7.0, 10.0 and 13.0 MeV deuteron energy for c.m. angles from 22.6° to 165°. Additional results to 9° c.m. have been obtained for T 20 and show a marked negative minimum near 20° c.m. Proton analyzing powers have also been measured at 2.5, 3.5, 5.0 and 6.5 MeV proton energy from 15° to 170° c.m.