Fri·May 19, 2017Friday·May 19, 2017

1. 01*

   Two-step nuclear reactions: The Surrogate Method, the Trojan Horse Method and their common foundations

   Mahir S. Hussein🇧🇷

   In this Letter I argue that the Surrogate Method, used to extract the fast neutron capture cross section on actinide target nuclei, which has important practical application for the next generation of breeder reactors, and the Trojan Horse Method employed to extract reactions of importance to nuclear astrophysics, have a common foundation, the Inclusive Non-Elastic Breakup (INEB)Theory. Whereas the Surrogate Method relies on the premise that the extracted neutron cross section in a (d,p) reaction is predominantly a compound nucleus one, the Trojan Horse Method, assumes a predominantly direct process for the secondary reaction induced by the surrogate fragment. In general, both methods contain both direct and compound contributions, and I show how theses seemingly distinct methods are in fact the same but at different energies and different kinematic regions. The unifying theory is the rather well developed INEB theory.

   ↳ nucl-thnucl-exEPJA(2017)·8 citations
2. 02*

   $\Phi$-meson--nucleus bound states

   J. J. Cobos-Martínez🇲🇽 · K. Tsushima🇧🇷 · G. Krein🇧🇷 · A. W. Thomas🇦🇺

   $\varphi$-meson--nucleus bound state energies and absorption widths are calculated for seven selected nuclei by solving the Klein-Gordon equation with complex optical potentials. Essential input for the calculations, namely the medium-modified $K$ and $\overline{K}$ meson masses, as well as the density distributions in nuclei, are obtained from the quark-meson coupling model. The attractive potential for the $\varphi$-meson in the nuclear medium originates from the in-medium enhanced $K\overline{K}$ loop in the $\varphi$-meson self-energy. The results suggest that the $\varphi$-meson should form bound states with all the nuclei considered. However, the identification of the signal for these predicted bound states will need careful investigation because of their sizable absorption widths.

   ↳ nucl-thhep-exhep-phnucl-exPRC(2017)·42 citations
3. 03*

   Developing diagnostic tools for low-burnup reactor samples

   Patrick Jaffke🇺🇸 · Benjamin Byerly · Jamie Doyle · Anna Hayes🇺🇸 · Gerard Jungman🇺🇸 · Steven Myers · Angela Olson · Donivan Porterfield · Lav Tandon

   We test common fluence diagnostics in the regime of very low burnup natural uranium reactor samples. The fluence diagnostics considered are the uranium isotopics ratios ${}^{235}$U/${}^{238}$U and ${}^{236}$U/${}^{235}$U, for which we find simple analytic formulas agree well with full reactor simulation predictions. Both ratios agree reasonably well with one another for fluences in the mid $10^{19}n/c{\mathrm{m}}^2$ range. However, below about $10^{19}n/c{\mathrm{m}}^2$ the concentrations of ${}^{236}$U are found to be sufficiently low that the measured ${}^{236}$U/${}^{235}$U ratios become unreliable. We also derive and test diagnostics for determining sample cooling times in situations where very low burnup and very long cooling times render many standard diagnostics, such as the ${}^{241}$Am/${}^{241}$Pu ratio, impractical. We find that using several fragment ratios are necessary to detect the presence of systematic errors, such as fractionation.

   ↳ physics.ins-detcond-mat.mtrl-scinucl-exnucl-thPhys.Rev.Applied(2017)·0 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.