Thermal neutron scattering parameters for light nuclei (A=12 to 27)

Abstract

Neutron scattering lengths and free scattering cross sections were measured for isolated isotopes and natural elements in the mass region from A = 12 to A = 27. By means of the Christiansen filter technique values for the coherent scattering lengths were obtained for the bound atoms of ~2C, 13C, ~4N, 15N, 260, 170, a80, Mg and a9F. Transmission experiments with neutrons of 0.51meV, 1.26eV and 5.19eV yielded data for the free scattering cross sections of 19F, 23Na, Mg and 19F. From all these results and with previous data the fundamental spin state scattering lengths for the concerned light nuclei have been deduced. The comparison of these values with resonance parameters has shown that the resonance data are complete. Therefore, values for the potential scattering radii could be obtained and discussed.

Interactions of slow neutrons with nuclides of antimony, tellurium and iodine

“…The corrections of a water contamination were calculated on the basis of data obtained from transmission measurements. With the oxygen scattering length b(0)=5.805 _+0.004 fm [11] the measurements resulted in mean These data are consistent with the uncorrected results of a previous work [7] in which faulty corrections of an oxidation of the elemental powders finally led to incorrect values. The new value for Sb can be compared with 5.4_+0.1 fin from diffraction works [12,13].…”

Scattering of slow neutrons by arsenic and selenium isotopes

“…The determinations of the free scattering cross sections at 1.26 eV and 5.19 eV result in a mean free cross section of fl~-,t=5.40_+0.03b which is one barn or ~20% smaller than the value of 6.4_+0.2b taken from [14]. [16]. A contribution due to an hydrogen contamination could not be found.…”

“…The fundamental scattering lengths are relevant also to nuclear physics, especially to the determination of potential parameters for the optical nuclear model. The combination of the "zero-energy" scattering parameters with scattering resonance data at higher neutron energies may provide a complete description of the s-wave neutron-nucleus scattering [3,4]. * Work partially supported by the "Bundesministerium fiir Forschung und Technologie (03-45 A 14I)"…”

Interaction of slow neutrons with nuclides of scandium, titanium, vanadium and manganese

“…If the scattering densities N. b of the powder and of the variable liquid mixture were equal, the small angle scattering vanished with the exception of a small residual part Po, which resulted from some inhomogeneities in the solid grains. The details of the experimental technique and the data reduction process are described in [7]; for a revised computer procedure we refer to [8]. Figure 1 shows some typical scattering curves on a relative scale.…”

“…For higher certainty we also compared the results on solid samples with measurements on a Sc203-compound which was dried at 1270 K in air atmosphere. -The solid samples of Ti and V had a metallic purity of 99.95% and [ 17] and some other unpublished measurements, bsi = 4.148 (1) fin [ 18], bso , = 26.08 (2) fm [ 17,18], bcl = 9.5792(8) fm [19] and bBr = 6.77(2) fm [20] (116) a abundance of the Ti-isotope all samples are air-dried variation in the density give rise to a mixture of crystalline modifications d obtained with b0= 5.807(3) fm [17] and some other unpublished measurements 99.97%, respectively. To eliminate a possible gas content they were heated up to about 1700 K in ultra high vacuum.…”