Neutron scattering lengths and cross sections of the barium isotopes

Abstract

Coherent neutron scattering lengths and total cross sections have been measured for barium compounds and on isotopically enriched samples for neutron energies from 0.5meV up to 132eV using different techniques. From the experimental data the following quantities were obtained: -the coherent scattering lengths (in fro) of Ba (5.07_+0.03) and of the isotopes with mass numbers 130 (-3.6+_0.6); 132 (7.8_+0.3); 134 (5.7_+0.1); 135 (4.66_+0.10); 136 (4.90 +_0.08); 137 (6.82+0.10); and 138 (4.83 +_0.08). -the absorption cross sections o-s (at 0.025 eV in barn): of Ba (1.1_+0.1) and of the isotopes: 130 (30_+5); 136 (0.68+_0:17); 137 (3.6+_0.2); and 138 (0.27 +_0.14).-zero-energy scattering cross sections for Ba and the isotopes 136, 137 and 138. On the basis of these data, the isotopic-and spin-incoherent cross sections and the (s)resonance contributions to the coherent scattering lengths have been determined and discussed.

Experimental estimates on radiative strength function of low-energy ?-quanta following even-odd heavy nuclei decay

“…The measured intensity of primary ?,-transitions, I~ = ~, i~ + ~ i~, amounts to about 80% of the total intensity of primary y-transitions for many compound-nuclei (see Table 1) including the a37Ba and 181Hf nuclei. The large error in the determination of ~, i~ in the 137Ba experiment comes from uncertainty in determination of the thermal neutron capture cross section [26].…”

“…The thermal neutron capture cross section is a~ = 0.68(17) b according to [26]. It differs from the value of a~ = 0.4(4) in [37] and is mainly defined by the resonance E o = -250 eV.…”