Non-spherical components of light nuclei

The relation between non-spherical components in the bound state wavefunctions of light nuclei A<or=4 and the tensor component of the nuclear force is analysed. A discussion of the methods used to extract information on the D-state components of ²H, ³H, ³He and ⁴He from experiments using tensor polarised deuteron beams is presented. Particular attention is given to the asymptotic D/S state ratio eta and to its relation with the NN interaction. It is shown that the sign and magnitude of eta in the A=2, 3 and 4 systems is closely related to the properties of the tensor force. D-state effects on the polarisation observables of the (d,p), (d,t), (d,³He) and (d,⁴He) transfer reactions and on the ¹H(d, gamma )³He and ²H(d, gamma )⁴He radiative capture reactions are discussed and the present status of the experimental and theoretical determinations of eta and D₂ is reviewed. In A>or=6 the connection between the tensor force and the non-spherical components is less simple than in A<or=4 systems because it involves strong shell effects. A brief discussion is presented.