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New proton emitter 188 At implies an interaction unprecedented in heavy nuclei

Kokkonen, Henna [Univ. of Jyvaskyla (Finland)] (ORCID:000900040311537X)·Auranen, Kalle [Univ. of Jyvaskyla (Finland)] (ORCID:0000000266047659)·Siwach, Pooja [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)]·Arumugam, Paramasivan [Indian Inst. of Technology (IIT), Roorkee (India)] (ORCID:0000000196248024)·Briscoe, Andrew D. [Univ. of Liverpool (United Kingdom)]·Eeckhaudt, Sarah [Univ. of Jyvaskyla (Finland)]·Ferreira, Lidia S. [Univ. de Lisboa (Portugal)] (ORCID:0000000312780297)·Grahn, Tuomas [Univ. of Jyvaskyla (Finland)] (ORCID:0000000262552279)·Greenlees, Paul T. [Univ. of Jyvaskyla (Finland)]·Jones, Pete [Univ. of Jyvaskyla (Finland); iThemba LABS, Somerset West (South Africa)] (ORCID:0000000174806603)·Julin, Rauno [Univ. of Jyvaskyla (Finland)]·Juutinen, Sakari [Univ. of Jyvaskyla (Finland)]·Leino, Matti [Univ. of Jyvaskyla (Finland)]·Leppänen, Ari-Pekka [Univ. of Jyvaskyla (Finland); European Commission, Eggenstein-Leopoldshafen (Germany). Joint Research Centre (JRC)] (ORCID:0000000297765223)·Maglione, Enrico [Univ. de Lisboa (Portugal)]·Nyman, Markus [Univ. of Jyvaskyla (Finland); Univ. of Helsinki (Finland)]·Page, Robert D. [Univ. of Liverpool (United Kingdom)] (ORCID:000900097062711X)·Pakarinen, Janne [Univ. of Jyvaskyla (Finland)] (ORCID:0000000189448757)·Rahkila, Panu [Univ. of Jyvaskyla (Finland)] (ORCID:0000000343920782)·Sarén, Jan [Univ. of Jyvaskyla (Finland)] (ORCID:0000000163834633)·Scholey, Catherine [Univ. of Jyvaskyla (Finland); MTC Limited, Coventry (United Kingdom)]·Sorri, Juha [Univ. of Jyvaskyla (Finland); Radiation and Nuclear Safety Authority (STUK), Vantaa (Finland)] (ORCID:0000000336932638)·Uusitalo, Juha [Univ. of Jyvaskyla (Finland)]·Venhart, Martin [Univ. of Jyvaskyla (Finland); Slovak Academy of Sciences, Bratislava (Slovakia)]
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Abstract

We report the discovery of a new atomic nucleus 188 At, which is the heaviest proton-emitting isotope known to date. The new activity was observed through the 107 Ag( 84 Sr, 3n) 188 At fusion-evaporation reaction using the focal-plane spectrometer of the gas-filled recoil separator in the Accelerator Laboratory of the University of Jyväskylä, Finland. To fully interpret the experimental data, we have expanded the non-adiabatic quasiparticle model to treat nuclei in the beyond-lead region. The description reproduced the measured decay rate and pointed towards emission from an extremely prolate-deformed state with a dominant s 1/2 proton component in the wave function. The Thomas-Ehrman shift can be enhanced in low angular momentum states, but such effects have not been observed in heavy nuclei. The single-proton separation energy of 188 At deviates from that extrapolated from the systematics, which can be interpreted as the first evidence of this effect in heavy nuclei.

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BibTeXRIS

Kokkonen, Henna [Univ. of Jyvaskyla (Finland)] (ORCID:000900040311537X), Auranen, Kalle [Univ. of Jyvaskyla (Finland)] (ORCID:0000000266047659), Siwach, Pooja [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)], Arumugam, Paramasivan [Indian Inst. of Technology (IIT), Roorkee (India)] (ORCID:0000000196248024), Briscoe, Andrew D. [Univ. of Liverpool (United Kingdom)], Eeckhaudt, Sarah [Univ. of Jyvaskyla (Finland)], Ferreira, Lidia S. [Univ. de Lisboa (Portugal)] (ORCID:0000000312780297), Grahn, Tuomas [Univ. of Jyvaskyla (Finland)] (ORCID:0000000262552279), Greenlees, Paul T. [Univ. of Jyvaskyla (Finland)], Jones, Pete [Univ. of Jyvaskyla (Finland); iThemba LABS, Somerset West (South Africa)] (ORCID:0000000174806603), Julin, Rauno [Univ. of Jyvaskyla (Finland)], Juutinen, Sakari [Univ. of Jyvaskyla (Finland)], Leino, Matti [Univ. of Jyvaskyla (Finland)], Leppänen, Ari-Pekka [Univ. of Jyvaskyla (Finland); European Commission, Eggenstein-Leopoldshafen (Germany). Joint Research Centre (JRC)] (ORCID:0000000297765223), Maglione, Enrico [Univ. de Lisboa (Portugal)], Nyman, Markus [Univ. of Jyvaskyla (Finland); Univ. of Helsinki (Finland)], Page, Robert D. [Univ. of Liverpool (United Kingdom)] (ORCID:000900097062711X), Pakarinen, Janne [Univ. of Jyvaskyla (Finland)] (ORCID:0000000189448757), Rahkila, Panu [Univ. of Jyvaskyla (Finland)] (ORCID:0000000343920782), Sarén, Jan [Univ. of Jyvaskyla (Finland)] (ORCID:0000000163834633), Scholey, Catherine [Univ. of Jyvaskyla (Finland); MTC Limited, Coventry (United Kingdom)], Sorri, Juha [Univ. of Jyvaskyla (Finland); Radiation and Nuclear Safety Authority (STUK), Vantaa (Finland)] (ORCID:0000000336932638), Uusitalo, Juha [Univ. of Jyvaskyla (Finland)], Venhart, Martin [Univ. of Jyvaskyla (Finland); Slovak Academy of Sciences, Bratislava (Slovakia)]. 2025-05-29. New proton emitter 188 At implies an interaction unprecedented in heavy nuclei. https://doi.org/10.1038/s41467-025-60259-6

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