Energy dependence of analyzing power Ay and cross section for p+d scattering below 18 MeV

The vector analyzing power Ay(θ) of the 2H(rvec p,p)2H scattering has been measured at Ep=5, 6, 6.5, 7, 8, 8.5, 9, 10, 12, 14, 16, and 18 MeV with a typical statistical accuracy of 0.0009 and an uncertainty in the beam polarization of less than 0.7%. The differential cross section σ(θ) of the 2H(p,p)2H scattering has also been measured with a typical uncertainty of 0.8% using unpolarized beams of the same energies and of 2, 2.5, 3, and 4 MeV. A large discrepancy of about 25% between the experiment and the Faddeev calculation with the Paris NN potential is observed at the maximum of Ay(θ) around θc.m.=120 degree. This discrepancy is shown to be reduced by modifying LS force in the NN potential, though a discrepancy still remains in the energy dependence of the Ay(θ) maximum. At the minimum of σ(θ) around θc.m.=120 degree, a large discrepancy ranging from -19% at 2 MeV to +24% at 18 MeV is observed between the experiment and the calculations with either of the original and the LS-modified NN potentials. This indicates that an improvement is also necessary in the scalar part of the potential. The difference in the Ay(θ) maximum between the rvec p+d and the rvec n+d scatterings is discussed