Analysis of experimental data of the doublet neutron-deuteron scattering below the deuteron breakup threshold on the basis of the pole approximation of the effective-range function

For the effective-range function k ctgδ, a pole approximation that is optimal for the description of neutron- deuteron system in doublet spin state is derived on the basis of the Bargmann representation of the S matrix. By using experimental values of the triton binding energy ET, doublet scattering length a2 and experimental phase shifts of van Oers-Seagrave below the deuteron breakup threshold, the doublet low-energy parameters of neutron-deuteron scattering are obtained. The results are r0 = 412.469 fm,v2 = -35495.62 fm3, and D = 172.678 fm2 for the pole parameter. With allowance for the values found for the low-energy scattering parameters and for the pole parameter, the pole approximation of the effective-range function provides a very good description of the doublet phase shift for neutron-deuteron scattering below the deuteron breakup threshold, to within the relative error not exceeding 1%. The physical properties of the triton in the ground (T) and virtual (v) states are calculated. The results are Bv 0.608 MeV for the energy of the virtual level and CT2 = 2.866, Cv2 0.0586 for the dimensionless asymptotic constants. It is shown that features of the virtual triton are determined to a very good accuracy in the Whiting-Fuda approximation by one parameter, namely, by the doublet neutron-deuteron scattering length a2. The effective ranges of the triton in the ground ρT = 1.711 fm and virtual ρv = 74.184 fm states are calculated for the first time