Indirect measurement of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mmultiscripts> <mml:mi>Sr</mml:mi> <mml:mprescripts/> <mml:none/> <mml:mn>90</mml:mn> </mml:mmultiscripts> <mml:mo>(</mml:mo> <mml:mi>n</mml:mi> <mml:mo>,</mml:mo> <mml:mi>γ</mml:mi> <mml:mo>)</mml:mo> <mml:mmultiscripts> <mml:mi>Sr</mml:mi> <mml:mprescripts/> <mml:none/> <mml:mn>91</mml:mn> </mml:mmultiscripts> </mml:mrow> </mml:math> reaction cross section and the implications for astrophysical Zr production

The intermediate neutron-capture process ($i$ process) has gained notable traction within the past decade as a way to describe stellar abundance observations which cannot be explained by the slow and rapid neutron-capture processes. Despite the general success of $i$-process models, many open questions remain. Among the observations, Zr stands out, as its elemental abundance is difficult to replicate with available $i$-process models, while the reactions that affect its production through the $i$ process are close enough to stability to study experimentally. Here, we present the experimental constraint of the nuclear level density and $\ensuremath{\gamma}$-strength function ($\ensuremath{\gamma}\phantom{\rule{0.16em}{0ex}}\mathrm{SF}$) of $^{91}\mathrm{Sr}$ using the $\ensuremath{\beta}$-Oslo method, which were then input into the TALYS Hauser-Feshbach code to produce the first experimental constraint of the $^{90}\mathrm{Sr}(n,\ensuremath{\gamma})^{91}\mathrm{Sr}$ capture reaction. This constraint was used alongside that of $^{92}\mathrm{Sr}(n,\ensuremath{\gamma})^{93}\mathrm{Sr}$ for a reduction in the uncertainty of [Y/Zr] production in the $i$-process relevant environmental neutron density of ${10}^{13.5}$ and ${10}^{14.5} \text{neutrons}/{\mathrm{cm}}^{3}$.