Journal ArticleShedding Light on the Origin of <math display='inline'><mrow><mmultiscripts><mrow><mi>Pb</mi></mrow><mprescripts/><none/><mrow><mn>204</mn></mrow></mmultiscripts></mrow></math> , the Heaviest <math display='inline'><mrow><mi>s</mi></mrow></math> -Process–Only Isotope in the Solar SystemCasanovas-Hoste, A; Domingo-Pardo, C; Lerendegui-Marco, J; Guerrero, C; Tarifeño-Saldivia, A; Krtička, M; Pignatari, M; Calviño, F; Schumann, D; Heinitz, S; Dressler, R; Köster, U; Aberle, O; Andrzejewski, J; Audouin, L; Bécares, V; Bacak, M; Balibrea-Correa, J; Barbagallo, M; Barros, S; Bečvář, F; Beinrucker, C; Berthoumieux, E; Billowes, J; Bosnar, D; Brugger, M; Caamaño, M; Calviani, M; Cano-Ott, D; Cardella, R; Castelluccio, D M; Cerutti, F; Chen, Y H; Chiaveri, E; Colonna, N; Cortés, G; Cortés-Giraldo, M A; Cosentino, L; Damone, L A; Diakaki, M; Dupont, E; Durán, I; Fernández-Domínguez, B; Ferrari, A; Ferreira, P; Finocchiaro, P; Furman, V; Göbel, K; García, A R; Gawlik-Ramięga, A; Glodariu, T; Gonçalves, I F; González-Romero, E; Goverdovski, A; Griesmayer, E; Gunsing, F; Harada, H; Heftrich, T; Heyse, J; Jenkins, D G; Jericha, E; Käppeler, F; Kadi, Y; Katabuchi, T; Kavrigin, P; Ketlerov, V; Khryachkov, V; Kimura, A; Kivel, N; Kokkoris, M; Leal-Cidoncha, E; Lederer-Woods, C; Leeb, H; Lo_Meo, S; Lonsdale, S J; Losito, R; Macina, D; Marganiec, J; Martínez, T; Massimi, C; Mastinu, P; Mastromarco, M; Matteucci, F; Maugeri, E A; Mendoza, E; Mengoni, A; Milazzo, P M; Mingrone, F; Mirea, M; Montesano, S; Musumarra, A; Nolte, R; Oprea, A; Patronis, N; Pavlik, A; Perkowski, J; Porras, I; Praena, J; Quesada, J M; Rajeev, K; Rauscher, T; Reifarth, R; Riego-Perez, A; Romanets, Y; Rout, P C; Rubbia, C; Ryan, J A; Sabaté-Gilarte, M; Saxena, A; Schillebeeckx, P; Schmidt, S; Sedyshev, P; Smith, A G; Stamatopoulos, A; Tagliente, G; Tain, J L; Tassan-Got, L; Tsinganis, A; Valenta, S; Vannini, G; Variale, V; Vaz, P; Ventura, A; Vlachoudis, V; Vlastou, R; Wallner, A; Warren, S; Weigand, M; Weiss, C; Wolf, C; Woods, P J; Wright, T; Žugec, Pn_TOF_Collaboration<p>Asymptotic giant branch stars are responsible for the production of most of the heavy isotopes beyond Sr observed in the solar system. Among them, isotopes shielded from the<math display='inline'><mrow><mi>r</mi></mrow></math>-process contribution by their stable isobars are defined as<math display='inline'><mrow><mi>s</mi></mrow></math>-only nuclei. For a long time the abundance of<math display='inline'><mrow><mmultiscripts><mrow><mi>Pb</mi></mrow><mprescripts/><none/><mrow><mn>204</mn></mrow></mmultiscripts></mrow></math>, the heaviest<math display='inline'><mrow><mi>s</mi></mrow></math>-only isotope, has been a topic of debate because state-of-the-art stellar models appeared to systematically underestimate its solar abundance. Besides the impact of uncertainties from stellar models and galactic chemical evolution simulations, this discrepancy was further obscured by rather divergent theoretical estimates for the neutron capture cross section of its radioactive precursor in the neutron-capture flow,<math display='inline'><mrow><mmultiscripts><mrow><mi>Tl</mi></mrow><mprescripts/><none/><mrow><mn>204</mn></mrow></mmultiscripts></mrow></math>(<math display='inline'><mrow><msub><mrow><mi>t</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub><mo>=</mo><mn>3.78</mn><mtext> </mtext><mtext> </mtext><mi>yr</mi></mrow></math>), and by the lack of experimental data on this reaction. We present the first ever neutron capture measurement on<math display='inline'><mrow><mmultiscripts><mrow><mi>Tl</mi></mrow><mprescripts/><none/><mrow><mn>204</mn></mrow></mmultiscripts></mrow></math>, conducted at the CERN neutron time-of-flight facility n_TOF, employing a sample of only 9 mg of<math display='inline'><mrow><mmultiscripts><mrow><mi>Tl</mi></mrow><mprescripts/><none/><mrow><mn>204</mn></mrow></mmultiscripts></mrow></math>produced at the Institute Laue Langevin high flux reactor. By complementing our new results with semiempirical calculations we obtained, at the<math display='inline'><mrow><mi>s</mi></mrow></math>-process temperatures of<math display='inline'><mi>k</mi><mi>T</mi><mo>≈</mo><mn>8</mn><mtext> </mtext><mtext> </mtext><mi>keV</mi></math>and<math display='inline'><mi>k</mi><mi>T</mi><mo>≈</mo><mn>30</mn><mtext> </mtext><mtext> </mtext><mi>keV</mi></math>, Maxwellian-averaged cross sections (MACS) of 580(168) mb and 260(90) mb, respectively. These figures are about 3% lower and 20% higher than the corresponding values widely used in astrophysical calculations, which were based only on theoretical calculations. By using the new<math display='inline'><mrow><mmultiscripts><mrow><mi>Tl</mi></mrow><mprescripts/><none/><mrow><mn>204</mn></mrow></mmultiscripts></mrow></math>MACS, the uncertainty arising from the<math display='inline'><mrow><mrow><mmultiscripts><mrow><mi>Tl</mi></mrow><mprescripts/><none/><mrow><mn>204</mn></mrow></mmultiscripts></mrow><mo stretchy='false'>(</mo><mi mathvariant='normal'>n</mi><mo>,</mo><mi>γ</mi><mo stretchy='false'>)</mo></mrow></math>cross section on the<math display='inline'><mrow><mi>s</mi></mrow></math>-process abundance of<math display='inline'><mrow><mmultiscripts><mrow><mi>Pb</mi></mrow><mprescripts/><none/><mrow><mn>204</mn></mrow></mmultiscripts></mrow></math>has been reduced from<math display='inline'><mo>∼</mo><mn>30</mn><mo>%</mo></math>down to<math display='inline'><mrow><mo>+</mo><mn>8</mn><mo>%</mo><mo>/</mo><mo>−</mo><mn>6</mn><mo>%</mo></mrow></math>, and the<math display='inline'><mrow><mi>s</mi></mrow></math>-process calculations are in agreement with the latest solar system abundance of<math display='inline'><mrow><mmultiscripts><mrow><mi>Pb</mi></mrow><mprescripts/><none/><mrow><mn>204</mn></mrow></mmultiscripts></mrow></math>reported by K. Lodders in 2021.</p> <sec><title/><supplementary-material><permissions><copyright-statement>Published by the American Physical Society</copyright-statement><copyright-year>2024</copyright-year></permissions></supplementary-material></sec>American Physical Society2024-07-0110543045Physical Review Letters13350031-9007https://doi.org/10.1103/PhysRevLett.133.0527021927130National Science Foundation