A semi-empirical formula for the neutron total cross section and the interpretation of the empirical formula forA ⩾ 40

Isotopically resolved neutron total cross sections at intermediate energies

“…Each water sample was contained by a cylindrical brass vessel with thin brass endcaps (0.002 inches), and an empty brass vessel served as the blank. 16,18 O cross sections were calculated by subtracting the well-known H cross section from the raw H 2 O results. We used H σ tot data sets from Clement et al [32] and Abfalterer et al [12], which together cover the range 0.5 ≤ E n ≤ 500 MeV and are in excellent agreement where their energy ranges overlap.…”

“…Producing an isotopically-enriched sample of this size is often prohibitively expensive. As a result, there is a dearth of σ tot data on isotopically-resolved targets from 1-300 MeV, even for closed-shell isotopes of special importance like 3,4 He, 18 O, 64 Ni, 112,124 Sn, and 204,206 Pb (Fig. 1.3 from [26]).…”

“…The data from that measurement were incorporated into several DOM analyses [28][29][30] that yielded proton and neutron SFs, charge radii, and initial estimates of the neutron skins [1] for these nuclei. Here we significantly expand on that effort by providing σ tot results for the important closed-shell nuclides 16,18 O, 58,64 Ni, and 112,124 Sn. We also present a measurement on a very thin sample of the naturally-monoisotopic 103 Rh to demonstrate that σ tot experiments over a broad energy range using only a few grams of material are feasible.…”

“…Thus these σ tot oscillations have been referred to as "anti-resonances" or "echoes" [6,17]. Other authors [18] have exposed weaknesses in Angeli and Csikai's interpretation of Eq. ( 2) and have provided a more general semi-empirical equation for σ tot .…”

“…

The neutron total cross sections σtot of 16,18 O, 58,64 Ni, 103 Rh, and 112,124 Sn have been measured at the Los Alamos Neutron Science Center (LANSCE) from low to intermediate energies (3 ≤ E lab ≤ 450 MeV) by leveraging waveform-digitizer technology. The σtot relative differences between isotopes are presented, revealing additional information about the isovector components needed for an accurate optical-model (OM) description away from stability.

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