The bound coherent neutron scattering lengths of the lanthanoids Pr, Nd, Sm, Eu, Yb and several of their isotopes as determined by neutron Bragg powder diffraction

We have determined the bound coherent neutron scattering lengths b_c of nuclides 141Pr, isoNd (iso = 142, 143, 144, 145, 146, 148, 150), isoSm (iso = 147, 148, 150, 152, 154), 153Eu, 170Yb and 174Yb as well as the natural elements natEu and natNd by using Bragg powder diffraction and analysing relative Bragg peak intensities with the Rietveld procedure. Some of these scattering lengths had never been determined before, to the best of our knowledge. Our investigations were carried out using different neutron diffractometers and different incident neutron energies (i.e. wavelengths) on chemically pure, crystalline, highly-enriched isotopic powder samples having different crystalline structures in order to ensure the consistency and robustness of the results and to reveal potential systematic errors. Our study led to final well-determined values of b_c(141Pr) = 4.44(4) fm, b_c(142Nd) = 7.24(4) fm, b_c(143Nd) = 17.51(6) fm, b_c(144Nd) = 3.06(7) fm, b_c(145Nd) = 10.40(12) fm, b_c(146Nd) = 8.56(9) fm, b_c(148Nd) = 4.44(13) fm, b_c(150Nd) = 6.87(5) fm. b_c(147Sm) = 6.68(5) fm, b_c(148Sm) = 6.67(7) fm, b_c(150Sm) = 10.05(10) fm, b_c(152Sm) = 6.14(12) fm, b_c(154Sm) = 9.34(9) fm, b_c(153Eu) = 8.33(11) fm, b_c(170Yb) = 4.83(3) fm, b_c(170Yb) = 22.02(7) fm, b_c(natNd) = 7.87(11) fm for thermal neutrons, and also b_c(natSm) = 5.29(5) fm for an incident neutron energy of 330.3(9) meV and b_c(natEu) = 5.84(5) fm for an incident neutron energy of 168.10(5) meV. Based on the good precision and self-consistency of our b_c results over so many isotopes, we advocate neutron Bragg powder diffraction as a method of choice for future studies to determine bound coherent neutron scattering lengths.