Neutron capture cross section of Mn53 from irradiation with cold and reactor neutrons

The neutron capture cross section of $^{53}\mathrm{Mn}$ was measured with cold and reactor neutrons by the activation method, relative to the well-known cross section of $^{59}\mathrm{Co}$. Three targets containing a total of $\ensuremath{\approx}{10}^{18}$ atoms $^{53}\mathrm{Mn}$ in the form of chloride salt were prepared using a stock solution obtained from activated accelerator waste in the course of the ERAWAST initiative at Paul Scherrer Institute, Switzerland (PSI). Natural cobalt salt was added to the sample material as an internal neutron flux monitor. The total numbers of $^{53}\mathrm{Mn}$ and $^{59}\mathrm{Co}$ atoms in the target were deduced via mass spectrometric measurements at PSI. Cold-neutron activation was carried out at the ICON beamline at PSI. Reactor activation was performed at the LVR-15 research reactor of Research Centre \ifmmode \check{R}\else \v{R}\fi{}e\ifmmode \check{z}\else \v{z}\fi{} in a well-moderated neutron field of an outer reactor channel. The thermal-neutron capture cross section and the resonance integral were determined by the cadmium ratio method. The induced activities of $^{54}\mathrm{Mn}$ and $^{60}\mathrm{Co}$ were quantified by high-resolution $\ensuremath{\gamma}$-ray spectrometry. The obtained thermal-neutron capture cross section of $76.5\ifmmode\pm\else\textpm\fi{}1.4\phantom{\rule{0.222222em}{0ex}}\mathrm{b}$ agrees well with previously reported results. The uncertainty of this value could be reduced by almost an order of magnitude with respect to older measurements and is on a level comparable to stable nuclides. The resonance integral of $43.1\ifmmode\pm\else\textpm\fi{}1.2\phantom{\rule{0.222222em}{0ex}}\mathrm{b}$ was obtained for the real reactor spectrum with epithermal-spectrum shape factor $\ensuremath{\alpha}=0.025$.