G. Perrin

A systematic study of elastic scattering of polarized deuterons around 30 MeV by complex nuclei

Abstract Cross section, vector and some tensor polarization data have been measured in the elastic scattering of 30 MeV polarized douterons by 10 nuclei: 12C, 28Si, 40Ca, 56Fe, 58Ni, 64Zn, 90Zr, 118Sn, 120Sn, 208Pb. Best-fit optical model parameters are deduced in an analysis without tensor potential and smooth average parameters are given. Real and imaginary volume integral and mean-square radii are calculated. The effect of a TR tensor potential is studied. It is shown that its effect is small on the tensor parameters T20 and T22, but that it is needed to give flt the tensor quantity X 2 = T 22 −√ 3 2 T 20 .

Diffusion élastique des deutons polarisés par 12C de 20 À 30 MeV

Abstract Angular distributions of the vector polarization of deuterons elastically scattered by 12 C have been measured at 20.5, 25.2 and 29.5 MeV. Asymmetries were measured with semiconductor telescopes. The beam polarization was determined simultaneously with a carbon polarimeter whose analysing power was calibrated by means of the d- 4 He scattering. Differential cross sections at 20.5 and 29.5 MeV are also presented. The results are analyzed in terms of the optical model. Two energy dependent average potentials are deduced.

Evidence for the deuteron-nucleus tensor interaction

Abstract Measurements for the elastic scattering of polarized deuterons from 40 Ca and 56 Fe at 30 MeV and from 90 Zr and 208 Pb at 28.8 MeV are presented. Angular distributions of the cross section, of the vector analyzing power iT 11 and of the quantity T 22 − √ 3 2 T 20 were deduced. Analyses of the data in terms of the optical model present evidence for the deuteron-nucleus tensor interaction.

Elastic and inelasttic scattering of polarized deuterons by 120Sn at 28.6 MeV

Abstract Angular distributions of the differential cross section and of the vector and tensor analyzing powers were measured for the elastic scattering of 28.6 MeV polarized deuterons from 120 Sn. The data could be fitted satisfactorily by optical-model calculations. The agreement with the experimental values of the tensor quantity T 22 −( 3 2 ) 1 2 T 20 was improved by inclusion of a tensor term T R in the optical potential. Cross sections and vector analysing powers were also measured for the inelastic scatterings from the 1,18 MeV (2 + ) and 2.44 MeV (3 − ) states. An acceptable description of the data was obtained by coupled-channels calculations in the framework of the vibrational model.

Polarisation et section efficace de la diffusion élastique p+3H À 19 et 30 MeV

Abstract With a polarized proton beam, the differential cross section and the proton analyzing power of the p+ 3 H elastic scattering at 19 and 30 MeV have been measured and compared to the p+ 3 He data. The proton analyzing power of the latter scattering has also been measured at 30 MeV to supplement the existing data. Real phase shifts from a preliminary analysis are deduced for both of the scatterings.

Vector and tensor analyzing powers in deuteron-proton elastic scattering atEd=70 MeV

Angular distributions of analyzing powersAyandAyyhave been measured ind-p elastic scattering at 70 MeV. The data are compared with Faddeev calcuiations using various tensor nucleon-nucleon interactions.

Absolute calibration of a 12C polarimeter for deuterons between 20 and 30 MeV

Abstract Angular distributions have been measured of asymmetries produced by vector polarized deuterons scattered by 12 C at 20.5, 25.2 and 29.5 MeV. The absolute normalization has been performed by comparison with the d- 4 He elastic scattering at 15 MeV.

Octupole excitation of the 6.88 level of28Si by deuteron inelastic scattering at 29.5 MeV

The experiments have been performed with the Grenoble Isochronous Cyclotron beam, focused on a 4 mg/cm ~ thin foil target of natural silicon. The scattered deuterons are detected by two 3 mm thick Si(Li) detectors, mounted on the two rotable arms of a chamber of 65 cm internal diameter. The positioning accuracy of the arms is 0.05 ~ Each detector has an angular resolution of • ~ delimited by a 4 • 8 mm tanta lum diaphragm. A monitoring detector is fixed at 45 ~ and a Faraday cup collects the beam charge. The detectors are cooled to about 2 0 ~ Each detector is connected to a charge preamplifier which gives rise to an analogue channel and a logic channel. This logic channel used an antipile-eup circuit which eliminates the pile-up effects by cancelling the pulse arriving at interval of t ime less than 30 ~s. The spectra from the multichalmel analyser are stored on magnetic tapes and handled by a PD1)-9 computer. An example of the spectra obtained is given in Fig. I. The overall energy resolution is (I00--150) keV. The beam energy is measured with a (CD2) ~ thin foil target, by crossover techniques. The angular distributions of deuterons scattered from the ground state, the first 2+-state and the 6.88 MeV level are shown in Fig. 2 together with the optical model and DWBA calculations. The first excited level of 2ssi has been well explained by Hartree-Fock and HartreeFoek-Bogoliubov calculations (1) as a rotational state of the ground band. Some recent experiments and calculations suggested an oblate deformation (2.3). :For the 6.88 level, gamma-ray double and triple angular-correlation measurements (4) from the 2:Al(p, T)2sSi reaction let to the spin-3 assignment and suggested the od,t narity, supported by some transfer reactions, particularly the 27 Al(aiie, d)2ssi reaction (a). According to the Blair

COMPARISON OF THE p→ + 3H AND p→ + 3He ELASTIC SCATTERINGS AT 19 AND 30 MeV

Publisher Summary This chapter presents the comparison between p + 3 H and p + 3 He elastic scatterings. With a polarized proton beam, the differential cross -section σ(θ) and the proton analyzing power P p (θ) of the p+ 3 H elastic scattering at19 and 30 MeV is measured and compared to the p+ 3 He data. The P p (θ) of the latter scattering is also measured at 30 MeV to supplement the existing data. A Ti-tritium thin foil target, a helium-3 cell, and Si(Li) detectors are used. The beam polarization, the direction of which is reversed every 0.2 sec by RF techniques is monitored by a carbone polarimeter. The Tombrello formula, which has also been described in the chapter, is applied in a preliminary analysis that neglects the isospin dependence and the absorption effects. The scattering matrix diagonalization uses the phase shifts, the spin and tensor coupling parameters. The optimized phase shifts are very sensitive to the coupling parameters. The order of magnitude of these phase shifts is in agreement with the results from resonating-group calculations.

ASYMMETRY MEASUREMENTS IN THE ELASTIC SCATTERING OF POLARIZED DEUTERONS BY H AND 4He BETWEEN 20 AND 30 MeV

Publisher Summary The Grenoble variable energy cyclotron is equipped with a source giving vector- and tensor-polarized deuterons. This source is on the top of the cyclotron and the polarized beam is injected through a hole drilled in the upper pole piece. In a reference frame where the quantization axis is along the magnetic field, the beam polarization can be described by a vector-polarization parameter and a tensor-polarization parameter. They are related to the spherical tensor moments, defined in a reference frame with the quantization axis along the direction of the particle. The maximum theoretically achievable polarization for a beam is both vector- and tensor-polarized. The beam energy can be measured by crossover techniques with uncertainty of order of 200 keV. The given uncertainties include both systematic and statistical errors. When no error bar is given, the uncertainty is of the order of the dot size.