First <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>β</mml:mi></mml:mrow></mml:math> -Delayed Two-Neutron Spectroscopy of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>r</mml:mi></mml:mrow></mml:math> -Process Nucleus <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>In</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>134</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> and Observation of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>i</mml:mi></mml:mrow><mml:mrow><mml:mn>13</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> Single-Particle Neutron State in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Sn</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>133</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math>

Dyszel, P.Grzywacz, R.Xu, Z. Y.Kitamura, N.Karny, M.Korgul, A.Madurga, M.Neupane, S.Algora, A.Andreyev, A. N.Araszkiewicz, M.Bark, R. A.Benito García, JaimeBernier, NikitaBorge, M. J. G.Caballero Rodríguez, MiriamChuchala, P.Cocolios, T. E.Costache, C.Cubiss, J. G.DeWitte, H.Escher, J. E.Fernandez-Ruiz, D.Fijalkowska, A.Fraile Prieto, Luis MarioFynbo, H. O. U.Gouge, J.López Herraiz, JoaquínIllana Sisón, AndrésJones, P. M.Judson, D. S.Kamińska, P.Kawano, T.Kolos, K.Labiche, M.Lică, R.Llanos Expósito, MarioGrarcía de Lorenzo, GabrielMarginean, N.Michelon, I.Mihai, C.Nácher, E.Neacsu, C.Nielsen, J. S.Olaizola, B.Orce, J. N.Page, C. A. A.Page, R. D.Pakarinen, J.Perea, A.Piersa-Silkowska, MonikaPodolyák, Zs.Prieto, J. S.Rajabali, M.Shaw, J.Sison, A. I.Solak, K.Stryjczyk, M.Tengblad, O.Vicente, P. G. T.Warr, N.Wilson, J.Yue, Z.Zajda, S.2026-02-042026-02-042025-10-08Dyszel, P., et al. «First β -Delayed Two-Neutron Spectroscopy of the r -Process Nucleus In 134 and Observation of the i 13 / 2 Single-Particle Neutron State in Sn 133». Physical Review Letters, vol. 135, n.o 15, octubre de 2025, p. 152501. DOI.org (Crossref), https://doi.org/10.1103/l24v-5m31.0031-900710.1103/l24v-5m31https://hdl.handle.net/20.500.14352/131526Group Author: IDS Collaboration. DEFG02-96ER40983. DE-AC05-00OR22725. 89233218CNA000001. DE-AC52-07NA27344. DE-436NA0003899. DE-NA0002132. DE-NA0004068. 1919735. PN 23 21 01 02. 05P18PKCIA. 05P21PKCI1. 05P2018. 05P2021. ST/R004056/1. ST/P004598/1. ST/P003885/1. ST/V001027/1. ST/Y000242/1. ST/V001035/1. 2021B0301030006. 2020/39/B/ST2/02346. 2024/53/N/ST2/03168. 2023/51/D/ST2/02816. 2021/WK/07. CT31/21. CISEJI/2022/25. South African CERN ProgramThis manuscript reports on the direct observation of a β-delayed two-neutron emission in a study of 134In at the ISOLDE Decay Station using neutron spectroscopy. We also report on the first measurement in β-decay of the long-sought 13/2+ excited state in 133Sn, attributed to be the neutron single-particle i13/2 orbital. The observation of sequential neutron emission is used to extract the relative population of the i13/2 state, which was found to be much smaller than the predictions of the statistical model. The experiment was possible because of the innovative use of a neutron array with neutron discrimination and interaction tracking capabilities. This is the first study of the details of the two-neutron emission for a nucleus, which belongs to the r-process path. Understanding β-delayed two-neutron emission probabilities is essential to validate models used in astrophysical r-process nucleosynthesis calculations. Observing two-neutron emissions in β-decay paves the way for new experiments to study energy and angular correlations for β-delayed multineutron emitters.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/First <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>β</mml:mi></mml:mrow></mml:math> -Delayed Two-Neutron Spectroscopy of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>r</mml:mi></mml:mrow></mml:math> -Process Nucleus <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>In</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>134</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math> and Observation of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>i</mml:mi></mml:mrow><mml:mrow><mml:mn>13</mml:mn><mml:mo>/</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math> Single-Particle Neutron State in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>Sn</mml:mi></mml:mrow><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>133</mml:mn></mml:mrow></mml:mmultiscripts></mml:mrow></mml:math>journal article1079-7114https://dx.doi.org/10.1103/l24v-5m3141138100https://journals.aps.org/prl/abstract/10.1103/l24v-5m31open access539.1Versatile arrayDetertorsFissionFísica nuclear2207 Física Atómica y Nuclear