{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"8f36818ed87cd7a18b647dc873614b8218f1ae9b19d8b7c7d079583e03393a1e","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"2e7aa8e40bd0bed0befb3742f6332f13026cc185d9d1594c437a5e000a203555","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"nuc.limits-of-existence.element-120-synthesis","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"The heaviest element made so far is oganesson (element 118), produced with calcium-48 beams that cannot go higher with available targets. Element 120 requires heavier beams such as titanium-50, which produce new elements far more rarely.","posed_since":"","precise":"Measure or bound the fusion-evaporation cross section for $50\\mathrm{Ti} + 249\\mathrm{Cf} \\to 120$ (and $54\\mathrm{Cr} + 248\\mathrm{Cm}$) at optimal excitation energy. LBNL produced two atoms of $290\\mathrm{Lv}$ via $50\\mathrm{Ti} + 244\\mathrm{Pu}$ (Gates et al., PRL 133, 172502, 2024), demonstrating the beam route. Answer: observed decay chains establishing $Z = 120$, or a cross-section limit testing fusion-evaporation models.","problem_ref":null,"references":"","settled_by":"Observation of correlated decay chains assigned to $Z = 120$ in a separator experiment, confirmed by a second laboratory.","status_note":"LBNL demonstrated the 50Ti route with livermorium in 2024 and planned a $Z = 120$ search; no element 120 event had been reported, to our knowledge, as of mid-2026.","title":"Can element 120 be made with titanium-50 beams?","topic_ref":"f67ee392625d78a3fea14458356613de3359df8e05ba08b64e875b372b6c34e3"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"9a9965fe0e1a2ef9ebc1ed4b1d928222b8506e4e66e1b6f86269f98469381cbe","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"2378a52f6096c42d9847334fa5afd703be7a05e63b942f38c1d9a43c0cb5d70c","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"t_rzz1tdvWJKGcb8nTgVg9fGsyAA9tJkR2vqRnh-DYwtJ3CAtfWs9d2G3w640K49Q72igVJkbM7fyflyujPpCQ"},"schema":"pubphys.envelope/1"},"record_hash":"9a9965fe0e1a2ef9ebc1ed4b1d928222b8506e4e66e1b6f86269f98469381cbe","leaf_index":1767}