Non-spherical components of light nuclei

The relation between non-spherical components in the bound state wavefunctions of light nuclei Α ≤ 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 η and to its relation with the NN interaction. It is shown that the sign and magnitude of η in the Α + 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, γ)3He and 2H(d, γ)4He radiative capture reactions are discussed and the present status of the experimental and theoretical determinations of η and D2 is reviewed. (author)