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According to the new study, fast neutrons released during fusion reactions slam into surrounding metals and lithium.<\/p>\n
This triggers rare nuclear processes that could emit axions capable of escaping the reactor and reaching nearby detectors.<\/p>\n
The work was led by Professor Jure Zupan at the University of Cincinnati (UC<\/a>) in Ohio. His research tracks possible dark matter particles, and treats reactor hardware as a new source of axions<\/a>.<\/p>\n Dark matter remains unseen<\/p>\n Dark matter reveals itself through gravity: galaxies rotate far faster than the pull of their visible stars and gas can account for. <\/p>\n The best measurements show that dark matter makes up about 84.4% of all matter in the universe, dominating the cosmic mass budget.<\/p>\n If axions make up that unseen mass, producing them near reactors could help constrain which theoretical models remain viable.<\/p>\n Axions are difficult to detect<\/p>\n Axions would slip through most materials because they interact only feebly with familiar particles and forces.<\/p>\n Searches often rely on rare conversions into light or electrons, which means even big detectors can wait years.<\/p>\n A clear signal would still need cross-checks, because many models predict related particles that would not make up dark matter.<\/p>\n Fusion reactors release fast neutrons<\/p>\n In a common fusion fuel mix, a helium nucleus stays trapped while a neutron flies out of the plasma.<\/p>\n That escaping neutron carries most of the reaction\u2019s energy, so surrounding structures must absorb a steady beating.<\/p>\n The fusion-reactor axion search proposal depends on this constant bombardment, because it seeds the rare reactions that matter.<\/p>\n Why tritium must be bred<\/p>\n Tritium, radioactive hydrogen that has two neutrons, is scarce in nature, so practical reactors plan to make more during operation.<\/p>\n A 12-year half-life<\/a> and constant fuel use push designers to breed tritium by letting neutrons strike lithium.<\/p>\n Those same neutron hits can also excite nuclei, setting up the chance to release a new light particle.<\/p>\n Wall capture releases particles<\/p>\n Neutron capture can leave a nucleus in the reactor\u2019s lithium or steel wall materials in an excited state, with excess energy that must be released.<\/p>\n A nuclear transition<\/a>, an excited nucleus dropping energy by emission, could send out an axion or another light particle.<\/p>\n Because the particle barely interacts, it can pass through shielding and appear just outside the reactor vessel.<\/p>\n Neutron slowing effects<\/p>\n Neutrons that do not get captured can still scatter, losing energy in many smaller collisions inside surrounding structures.<\/p>\n When a charged particle slows down, it emits braking radiation, releasing energy that can give rise to new particles.<\/p>\n The proposal treats this as a second production channel, although it matters most when neutrons keep enough energy.<\/p>\n Particles reach detectors<\/p>\n The proposal relies on these particles traveling tens of feet from the reactor core, far enough to reach detectors positioned outside the reactor structure.<\/p>\n A detector placed 33 feet (10 meters) away could look for interactions that normal neutrons and gamma rays rarely mimic.<\/p>\n Distance matters because the flux spreads out quickly, so experiments need either big reactors, big detectors, or both.<\/p>\n Heavy water detector<\/p>\n The detection concept uses a large tank of heavy water<\/a> \u2013 made with deuterium instead of regular hydrogen \u2013 near a fusion facility.<\/p>\n When an axion hits a deuterium nucleus, it can split the pair into a free proton and neutron.<\/p>\n That breakup leaves a clear signature, since the outgoing neutron can be counted and the proton can be tracked.<\/p>\n Fusion reactor signal versus noise<\/p>\n A real test would compare detector rates when the reactor is running with rates when it is shut down.<\/p>\n The biggest background comes from solar neutrinos<\/a>, tiny particles made in the Sun\u2019s core, that also break deuterium, so timing helps.<\/p>\n Even with backgrounds, the proposal could rule out large slices of parameter space if no excess appears.<\/p>\n Pop culture to physics<\/p>\n In season five of The Big Bang Theory, several episodes tucked the axion puzzle onto whiteboards, with no dialogue explaining it.<\/p>\n \u201cNeutrons interact with material in the walls,\u201d said Professor Zupan. The show\u2019s sun-based math misses the wall reactions, and that is exactly where the proposal finds its advantage.<\/p>\n Limitations of theory<\/p>\n Some production estimates rely on quick scaling arguments, because the exact nuclear reactions in wall materials are not fully mapped.<\/p>\n Better reactor-specific simulations would track where neutrons slow down and which atom types they hit, using measured reaction probabilities.<\/p>\n Until those inputs improve, the proposal can sketch promising reach but cannot guarantee a detectable rate at any single facility.<\/p>\n The future of fusion reactors<\/p>\n The International Thermonuclear Experimental Reactor (ITER<\/a>) site in southern France shows the scale of machines now under construction.<\/p>\n ITER will test key technologies like tritium breeding, and later plants could run longer and produce more neutrons.<\/p>\n If engineers can reserve nearby space for detectors, ITER-class facilities could double as particle laboratories without changing their energy mission.<\/p>\n Neutron-rich fusion linings could become controlled sources for testing one candidate for dark matter directly.<\/p>\n Next, researchers need reactor-specific simulations and detector designs that can confirm or refute the proposal with clear controls.<\/p>\n The study is published in the Journal of High Energy Physics<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"Fusion reactors are designed to produce clean energy, but new theory suggests they could also generate one of…\n","protected":false},"author":2,"featured_media":341709,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[24],"tags":[2302,90,56,54,55],"class_list":{"0":"post-341708","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-physics","8":"tag-physics","9":"tag-science","10":"tag-uk","11":"tag-united-kingdom","12":"tag-unitedkingdom"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/341708","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/comments?post=341708"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/posts\/341708\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media\/341709"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/media?parent=341708"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/categories?post=341708"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/uk\/wp-json\/wp\/v2\/tags?post=341708"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}