{"id":14933,"date":"2025-06-22T22:00:00","date_gmt":"2025-06-22T22:00:00","guid":{"rendered":"https:\/\/modernsciences.org\/staging\/4414\/?p=14933"},"modified":"2025-06-13T08:14:02","modified_gmt":"2025-06-13T08:14:02","slug":"astatine-188-heaviest-proton-emitter-discovery-june-2025","status":"publish","type":"post","link":"https:\/\/modernsciences.org\/staging\/4414\/astatine-188-heaviest-proton-emitter-discovery-june-2025\/","title":{"rendered":"Physicists discover astatine-188, the heaviest known proton-emitting nucleus"},"content":{"rendered":"\n<div class=\"wp-block-group has-gray-200-background-color has-background\"><div class=\"wp-block-group__inner-container is-layout-constrained wp-block-group-is-layout-constrained\">\n<h1 id=\"at-a-glance\" class=\"wp-block-heading\">At a Glance<\/h1>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"\">An international team of physicists has discovered astatine-188 (<sup>188<\/sup>At), the heaviest known atomic nucleus that undergoes the rare decay process of proton emission.<\/li>\n\n\n\n<li class=\"\">Researchers created this extremely short-lived isotope at the University of Jyv\u00e4skyl\u00e4 by colliding a high-energy strontium-84 beam with a target made of natural silver.<\/li>\n\n\n\n<li class=\"\">Analysis of the new nucleus revealed that it has a highly deformed prolate shape, similar to a watermelon, and decays in a way that defied theoretical predictions.<\/li>\n\n\n\n<li class=\"\">The isotope\u2019s unexpected decay behavior provides the first experimental evidence of a quantum mechanical interaction called the Thomas-Ehrman shift within a very heavy atomic nucleus.<\/li>\n\n\n\n<li class=\"\">This groundbreaking research advances our understanding of nuclear structure at the limits of stability and provides a crucial new benchmark for testing and refining theoretical models.<\/li>\n<\/ul>\n<\/div><\/div>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<p class=\"\">An international team of physicists has announced the discovery of astatine-188 <sup>188<\/sup>At, a new atomic nucleus that is now the heaviest known to decay by emitting a proton. The breakthrough, achieved at the <a href=\"https:\/\/www.jyu.fi\/en\" target=\"_blank\" rel=\"noreferrer noopener\">University of Jyv\u00e4skyl\u00e4<\/a> in Finland, pushes the known limits of matter and provides new insight into the forces that hold atoms together. The findings were published in the journal <a href=\"https:\/\/www.nature.com\/articles\/s41467-025-60259-6\" target=\"_blank\" rel=\"noreferrer noopener\"><em>Nature Communications<\/em><\/a>. Most atomic nuclei decay by emitting other particles, such as electrons or alpha particles. Proton emission, however, is a much rarer process. \u201cProton emission is a rare form of radioactive decay, in which the nucleus emits a proton to take a step toward stability,\u201d said <a href=\"https:\/\/www.jyu.fi\/en\/people\/henna-kokkonen\" target=\"_blank\" rel=\"noreferrer noopener\">Henna Kokkonen<\/a>, a doctoral researcher at the University of Jyv\u00e4skyl\u00e4 and a key member of the research team.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img  decoding=\"async\"  src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAAP+KeNJXAAAAAXRSTlMAQObYZgAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=\"  alt=\"\"  class=\" pk-lazyload\"  data-pk-sizes=\"auto\"  data-pk-src=\"https:\/\/scx2.b-cdn.net\/gfx\/news\/2025\/the-heaviest-proton-em-1.jpg\" ><figcaption class=\"wp-element-caption\">This diagram shows the two primary ways the newly discovered astatine-188 nucleus decays. The first path (1) illustrates the rare proton emission (p), where the nucleus releases a proton to become polonium-187 (<sup>187<\/sup>Po). The second path (2) shows its decay via alpha particle emission (\u03b1). Each step in the chain includes the measured energy and half-life, which shows how quickly the decay occurs. (Kokkonen et al., 2025)<\/figcaption><\/figure>\n\n\n\n<p class=\"\">The new isotope, which consists of 85 protons and 103 neutrons, was created through a process known as a fusion-evaporation reaction. In the experiment, scientists bombarded a target made of natural silver with a high-energy beam of strontium-84 (<sup>84<\/sup>Sr) ions. The collision occasionally fused the two nuclei, which immediately evaporated three neutrons to form <sup>188<\/sup>At. Because these exotic nuclei are incredibly short-lived and have a low production cross-section, they are challenging to create; to address this, the team used a highly sensitive detector setup called the <a href=\"https:\/\/www.jyu.fi\/en\/science\/accelerator-laboratory\/facilities-and-instruments\/nuclear-physics-facilities#RITU\" target=\"_blank\" rel=\"noreferrer noopener\">RITU recoil separator<\/a> to isolate and identify the new isotope just moments after its formation.<\/p>\n\n\n\n<p class=\"\">The researchers paired their experimental data with a sophisticated theoretical model to fully understand the new discovery. The model\u2019s calculations suggest that the <sup>188<\/sup>At nucleus is not spherical but is instead extremely \u201cprolate,\u201d meaning it is deformed into a shape resembling a watermelon. The measured decay rate revealed an unexpected deviation in the nucleus\u2019s binding energy. The energy required to remove its outermost proton differed from what established trends predicted. The team interprets this as the first evidence of a quantum mechanical effect in a heavy nucleus known as the Thomas-Ehrman shift. This interaction can influence the stability of nuclei with loosely bound protons.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img  decoding=\"async\"  src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAAP+KeNJXAAAAAXRSTlMAQObYZgAAAAlwSFlzAAAOxAAADsQBlSsOGwAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=\"  alt=\"\"  class=\" pk-lazyload\"  data-pk-sizes=\"auto\"  data-pk-src=\"https:\/\/scx1.b-cdn.net\/csz\/news\/800a\/2025\/the-heaviest-proton-em.jpg\" ><figcaption class=\"wp-element-caption\">Henna Kokkonen, a doctoral researcher at the University of Jyv\u00e4skyl\u00e4, stands with the detector setup of the RITU recoil separator. This equipment was used to identify the new isotope astatine-188, a key finding in her doctoral research. (Sassi, 2025)<\/figcaption><\/figure>\n\n\n\n<p class=\"\">This discovery marks the second time in recent years that Kokkonen has been part of a team identifying a new isotope, following her master\u2019s thesis work on the discovery of astatine-190 (<sup>190<\/sup>At). The research adds a new member to the chart of nuclides. It provides a crucial test for theoretical models that describe the complex behavior of atomic nuclei at the edge of stability. \u201cIsotope discoveries are rare worldwide, and this is the second time I have had the opportunity to be part of making history,\u201d Kokkonen said. \u201cEvery experiment is challenging, and it feels great to do research that improves understanding of the limits of matter and the structure of atomic nuclei.\u201d<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 id=\"references\" class=\"wp-block-heading\">References<\/h1>\n\n\n\n<ul class=\"wp-block-list\">\n<li class=\"\">Kokkonen, H., Auranen, K., Siwach, P., Arumugam, P., Briscoe, A. D., Eeckhaudt, S., Ferreira, L. S., Grahn, T., Greenlees, P. T., Jones, P., Julin, R., Juutinen, S., Leino, M., Lepp\u00e4nen, A.-P., Maglione, E., Nyman, M., Page, R. D., Pakarinen, J., Rahkila, P., \u2026 Venhart, M. (2025). New proton emitter 188At implies an interaction unprecedented in heavy nuclei. <em>Nature Communications<\/em>, <em>16<\/em>(1), 4985. <a href=\"https:\/\/doi.org\/10.1038\/s41467-025-60259-6\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/doi.org\/10.1038\/s41467-025-60259-6<\/a><\/li>\n\n\n\n<li class=\"\">University of Jyv\u00e4skyl\u00e4. (2025, June 4). <em>The heaviest proton emitter: New type of atomic nucleus discovered<\/em>. Phys.Org; University of Jyv\u00e4skyl\u00e4. <a href=\"https:\/\/phys.org\/news\/2025-06-heaviest-proton-emitter-atomic-nucleus.html\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/phys.org\/news\/2025-06-heaviest-proton-emitter-atomic-nucleus.html<\/a><\/li>\n<\/ul>\n\n\n\n<p class=\"\"><\/p>\n\n\n\n<p class=\"\"><\/p>\n\n\n\n<p class=\"\"><\/p>\n","protected":false},"excerpt":{"rendered":"At a Glance An international team of physicists has announced the discovery of astatine-188 188At, a new atomic&hellip;\n","protected":false},"author":4,"featured_media":14935,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"nf_dc_page":"","fifu_image_url":"https:\/\/upload.wikimedia.org\/wikipedia\/commons\/e\/e2\/Astatine.JPG","fifu_image_alt":"","footnotes":""},"categories":[17,15],"tags":[12622,12603,12602,12613,12612,12611,12616,12619,12609,3811,12605,12621,1849,12610,12606,12620,12601,12604,12614,12608,12607,12618,12617,12615],"class_list":{"0":"post-14933","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-math-and-the-sciences","8":"category-engineering","9":"tag-188at","10":"tag-astatine-188","11":"tag-atomic-nucleus","12":"tag-exotic-nuclei","13":"tag-fusion-evaporation-reaction","14":"tag-heaviest-proton-emitter","15":"tag-henna-kokkonen","16":"tag-lightest-astatine-isotope","17":"tag-limits-of-matter","18":"tag-nature-communications","19":"tag-new-isotope-discovery","20":"tag-nuclear-binding-energy","21":"tag-nuclear-physics","22":"tag-nuclear-structure","23":"tag-particle-accelerator","24":"tag-physics-research","25":"tag-prolate-nucleus","26":"tag-proton-emission","27":"tag-quantum-mechanics-in-nuclei","28":"tag-radioactive-decay","29":"tag-ritu-recoil-separator","30":"tag-science-news","31":"tag-thomas-ehrman-shift","32":"tag-university-of-jyvaskyla","33":"cs-entry","34":"cs-video-wrap"},"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/14933","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/comments?post=14933"}],"version-history":[{"count":1,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/14933\/revisions"}],"predecessor-version":[{"id":14934,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/posts\/14933\/revisions\/14934"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/media\/14935"}],"wp:attachment":[{"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/media?parent=14933"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/categories?post=14933"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/modernsciences.org\/staging\/4414\/wp-json\/wp\/v2\/tags?post=14933"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}