First Study of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Ba</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>139</mml:mn></mml:mrow></mml:mmultiscripts><mml:mo stretchy="false">(</mml:mo><mml:mi>n</mml:mi><mml:mo>,</mml:mo><mml:mi>γ</mml:mi><mml:mo stretchy="false">)</mml:mo><mml:mmultiscripts><mml:mrow><mml:mi>Ba</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>140</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> Reaction to Constrain the Conditions for the Astrophysical <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>i</mml:mi></mml:math> Process
A. Spyrou, D. Mücher, Pavel A. Denissenkov, Falk Herwig, E. Good, G. Balk, H. C. Berg, D. L. Bleuel, J. A. Clark, C. Dembski, P. A. DeYoung, B. Greaves, M. Guttormsen, Craig Harris, A. C. Larsen, S. N. Liddick, S. Lyons, M. Markova, M. J. Mogannam, S. Nikas, J. Owens-Fryar, A. Palmisano-Kyle, G. Perdikakis, Francesco Pogliano, M. Quintieri, A. Richard, D. Santiago-Gonzalez, G. Savard, M. K. Smith, A. Sweet, A. Tsantiri, M. Wiedeking
Abstract
New astronomical observations point to a nucleosynthesis picture that goes beyond what was accepted until recently. The intermediate "i" process was proposed as a plausible scenario to explain some of the unusual abundance patterns observed in metal-poor stars. The most important nuclear physics properties entering i-process calculations are the neutron-capture cross sections and they are almost exclusively not known experimentally. Here we provide the first experimental constraints on the ^{139}Ba(n,γ)^{140}Ba reaction rate, which is the dominant source of uncertainty for the production of lanthanum, a key indicator of i-process conditions. This is an important step towards identifying the exact astrophysical site of stars carrying the i-process signature.