H. Riedesel

The optical potential for vector-polarized deuterons of 52 MeV

Abstract The vector analysing power for elastic scattering of 52 MeV polarized deuterons was measured for 12 C, 16 O, 20 Ne, 28 Si, 32 S, 40 Ar, 58 Ni, 90 Zr and 197 Au. The data were analysed together with previously measured differential cross sections in the framework of the optical model. Best-fit and average optical-model parameters were obtained both for surface and volume absorption. Fits with surface absorption are superior to those with volume absorption, especially for heavier nuclei. Typical parameters of the spin-orbit part of the best-fit optical potentials are found to be V s.o. ∼- 5.5 MeV, r s.o. ∼- 1.15 fm and a s.o. ∼- 0.4 fm, and there is no evidence for an imaginary component. The volume integrals and rms radii of real, imaginary and l · s potentials show a smooth mass dependence and differ insignificantly for different sets of potentials.

Strong exhaustion of 1gsol92 strength by deeply-bound proton-hole states in Pm isotopes☆

Abstract The 1 g 9 2 proton-hole strength distributions in Pm isotopes have been investigated by the 144, 148, 152 Sm (d,τ) reactions at 52 MeV. Other than for corresponding neutron-hole states most of the shell-model strength is exhausted by one gross structure peak.

Deformation of 1p shells in (2s, 1d) shell nuclei from a systematic study of (d, τ) reactions

Abstract Vector-analyzing powers for l = 0, 1 and 2 transitions induced by the ( d , τ) reaction on12C, 14N, 16O, 18O, 22Ne and 28Si have been measured at E = 52 MeV. A characteristic j-dependence of the analyzing power has been observed for the different l-values, which depends only weakly on target mass and Q-value and which is qualitatively described by conventional DWBA calculations. These features allow reliable spin determinations. As a result we present new spin assignments for 17N and 21F. Combined with the results of a parallel measurement of the (d, τ) and (d, t) reactions on 18O and 22Ne, the information on new spins in 17N and 21F could be transferred to their analog ( T = 3 2 ) states in 17O and 21Ne. A survey of energies and spectroscopic strengths of the lowest 1 2 − and 3 2 − states in odd-A nuclei (17 ⩽ A ⩽ 27) reveals systematic trends which are better reproduced by a strong coupling model than by a weak coupling model. This allows one to deduce the deformation of the 1p orbits in the odd-A final states.

Giant resonance decays in 20Ne, 22Ne and interference effects with quasifree scattering processes

Abstract The charged particle (c) decay from excited states up to the giant quadrupole resonance (GQR) in 20Ne has been studied in a kinematically complete 20Ne(α, α′ c) coincident experiment at Eα = 155 MeV. Angular correlation functions and branching ratios are extracted for the α0, α1 and p0 decay channels. The (α, α′ α0) angular correlation functions are analysed in PWBA in terms of coherent interference with the quasifree scattering process leading to the same final states. Good fits to the data are achieved over a large range of excitation energies. Branching ratios have been extracted and compared to results of Hauser-Feshbach calculations. Above Ex = 12.5 MeV excitation energy a discrepancy was found between the experimentally observed α0 branching ratios and the HF predictions. These results yield evidence for a direct α0 decay mechanism of the split isoscalar giant quadrupole resonance in 20Ne. Some results are presented also for a 22Ne(α, α′ c) coincidence experiment. Qualitative comparison has been made between the general decay behaviour of the two Ne isotopes.

Spin determination of states with stretched configurations in 16N and 32P via the (d, α) reaction at 52 MeV

The reactions 12C(d, α)10B, 18O(d, α)16N and 34S(d, α)32P have been investigated at Ed = 52 MeV. Vector analyzing powers as large as ¦iT11¦=0.85 are observed. They exhibit patterns characteristic for final spins I = |L−1|, L or L + 1 and provide spin determinations at least for states of unique L-transfer. Local, zero-range DWBA calculations assuming deuteron-cluster pick-up reproduce qualitatively the observed effects. The method has been tested for states of known spin, and then has been applied to determine spins of states with stretched coupling in 16N: Jπ = 3+(3.96 MeV), 4−(6.17 MeV) and in 32P: Jπ = 5+(4.75 MeV). There is strong evidence for further 5+ states in 32P at 6.43, 7.96, 8.09 and 8.54 MeV.

Importance of nucleon knock-out in inelasticα and6Li scattering

At 26 MeV/A, inelastic scattering of6Li ions from28Si proceeds predominantly via direct one-nucleon removal, while inelasticα scattering leads, in addition, to excitation of the target nucleus.

Configuration mixing of particle‐hole states in A=16 nuclei studied by the 17O(d↘,t)16O and 17O(d↘,τ)16N reaction

The reactions 17O(d↘,t)16O and 17O(d↘,τ)16N have been measured simultaneously at Ed=52 MeV. The analyzing powers for l=1 pick‐up, which differ characteristically for 1p1/2 and 1p3/2 transfer, allow to determine the degree of j‐mixing in 2− and 3− states in 16O(T=O and T=1) and in 16N. All observed strongly excited states appear to have rather pure particle‐hole configurations.