Slow neutron scattering parameters for stable nuclei with nucleon numbers betweenA=79 andA=96

Abstract

Coherent neutron scattering lengths and free cross sections were measured for separated isotopes and ordinary elements in the mass region from A=79 to A=96. Using the Christiansen filter technique values of scattering lengths have been determined for the bound atoms of the isotopes 79Br, 81Br, SSRb, 87Rb, S6Sr, 87Sr, SSSr, 89y, 90Zr ' 92Zr ' 94Zr and 96Zr as well as for the ordinary elements. Transmission experiments with neutrons of 0.51 meV, 1.26 eV and 5.19 eV yielded data for the free scattering cross sections of the elements. Data for the incoherent cross sections and for the spin state scattering lengths have been derived from the experimental results. The obtained low energy scattering parameters were compared with the results from neutron resonance spectroscopy. Clear evidence has been gained for bound levels of the neutron-nucleus systems.

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

“…These bound levels reproduced the energy dependence of the measured total cross sections (compare Table 3 well as the potential radius of R'= 6.50 (20)fro, which agrees very well with the prediction of optical model calculation.…”

“…The following new fitted bound levels (the parameters recommended in [12] are in brackets) lead for slV to a potential radius of R' =5.20 (20) {6.9 __+ 0.3} fm, which is also at variance with the value in [12], but consistent with optical model calculations. The cross section calculation using this new bound level set reproduced the measured value (compare Table 3 …”

“…The Christiansen filter measurements on 6 different natural Ti-compounds yielded a mean value for the coherent scattering length of b=-3.370(13)fm (see Table 1), which was slightly outside the standard deviation for the scattering length determined from its isotope values (compiled in Table 2) = -3.327 (20) fro.…”

“…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 -The solid samples of Ti and V had a metallic purity of 99.95% and [ 17] and some other unpublished measurements, bsi = 4.148 (1) fin [ 18], bso , = 26.08 (2) fm [ 17,18], bcl = 9.5792(8) fm [19] and bBr = 6.77(2) fm [20] (116) a abundance of the Ti-isotope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.…”

Experimental evidence for two different dynamical regimes in liquid rubidium

“…Rubidium is a nearly coherent scatterer with an incoherent contribution of less than 0.04 barn compared to the coherent cross section of 6.24 barn [22]. Rubidium (99.9 % purity) was filled in a cylindrical aluminium can with 16 mm diameter (9 % scatterer) inside a glove box.…”