Speaker
Description
Measuring the $^{135}$Xe neutron-capture cross section ($^{135}$Xe($n,\gamma$)$^{136}$Xe) has been identified as a top priority for its role in reactor design, stockpile stewardship, nonproliferation, and astrophysics [1]. Current cross section data does not extend above thermal neutron energies and data evaluations differ by an order of magnitude. Performing direct neutron-capture measurements on unstable nuclei is challenging, making it necessary to rely on indirect measurements that utilize the statistical properties of nuclei, namely the nuclear level density and gamma-ray strength function. These quantities are used as inputs for Hauser-Feshbach reaction calculations that ultimately provide neutron-capture constraints. However, the predicted statistical properties exhibit large theoretical uncertainties themselves and need to be better constrained for more accurate predictions. This work focuses on experimentally constraining the non-thermal $^{135}$Xe neutron-capture rate by simultaneously extracting the aforementioned statistical properties of $^{136}$Xe using two experimental methods. One experiment will use the $\beta$-Oslo method [2] to measure the $\beta$-decays of $^{136}$I and $^{136}$Te using the nuCARIBU facility at Argonne National Laboratory. The other will use the inverse-Oslo method [3] to measure inelastic proton scattering with the p($^{136}$Xe,$p’\gamma$)$^{136}$Xe reaction with DAPPER at Texas A&M University. Current development and preparation of these two experiments will be discussed along with preliminary results from the $\beta$-Oslo experiment.
This work was supported by the Office of Defense Nuclear Nonproliferation Research and Development within the U.S. Department of Energy’s National Nuclear Security Administration and performed under the auspices the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and Berkeley Lab under Contract AC02-05CH11231.
References:
[1] Root, S. J. et al. (2023) Nuclear Engineering and Design, 414, 112606.
[2] Spyrou, A. et al. (2014) Phys. Rev. Lett., 113, 232502.
[3] Ingeberg, V. W. et al. (2020) Eur. Phys. J. A., 56, 68.