Measurement of the Pr141(n,γ) cross section up to stellar s-process temperatures at the China Spallation Neutron Source Back-n facility

In nuclear astrophysics, $^{141}\mathrm{Pr}$ is mainly produced by an $s$ process, which has a neutron magic number $(N=82)$ leading to its low capture cross section and strongly affecting the $s$ process. Its neutron capture cross section is an important input parameter for nuclear astrophysical network calculations. According to the EXFOR database, the measurement precision for the $^{141}\mathrm{Pr}(n,\ensuremath{\gamma})$ cross section should be improved in the resolved and unresolved resonance region. The $(n,\ensuremath{\gamma})$ cross section of $^{141}\mathrm{Pr}$ was measured between 1 eV and 500 keV at the Back-n facility of the Chinese Spallation Neutron Source using the time-of-flight (TOF) method. The prompt $\ensuremath{\gamma}$ rays were detected by four ${\mathrm{C}}_{6}{\mathrm{D}}_{6}$ liquid scintillator detectors, and the data was analyzed using the pulse-height weighting technique (PHWT). The majority of results are in agreement with the evaluated data libraries ENDF/B-VIII.0, JENDL-5.0, and TENDL-2021, with some significant exceptions for small resonances. The multilevel $R$-matrix Bayesian code sammy was used to extract the resonance parameters of $^{141}\mathrm{Pr}$ in the resolved resonance region. And the Maxwell average cross section (MACS) from $kT=5$ to 100 keV is calculated in the temperature range of the $s$-process nucleosynthesis model. In particular, at $kT=30$ keV the MACS value of $^{141}\mathrm{Pr}$ is $145.0\ifmmode\pm\else\textpm\fi{}13.7$ mb, which shows an obvious discrepancy with the Karlsruhe Astrophysical Database of Nucleosynthesis in Stars (KADoNiS) recommended value $111.4\ifmmode\pm\else\textpm\fi{}1.4$ mb.