{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"96590ec06eaa876243b863cd71656baf1696cf475258fb0f1fc9352935c964ab","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"b6276b563031302f213ec06e955fa1960d8007349b0ac5931393284bfc1f8f4e","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"nuc.limits-of-existence.next-proton-shell","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Theory predicts an 'island of stability' of unusually long-lived superheavy nuclei centred on a magic neutron number 184 and a proton number that models place at 114, 120 or 126. No known nucleus has reached 184 neutrons.","posed_since":"","precise":"Determine which proton number $Z$ (114, 120 or 126) gives the next spherical shell gap above $Z = 82$ for $N$ near 184, from measured $\\alpha$-decay $Q$ values, fission half-lives and spectroscopy of nuclei with $Z \\ge 110$, and from theory with quantified spin-orbit and density-functional uncertainty. Answer: the $Z$ of the shell closure and the predicted half-life of the doubly magic nucleus.","problem_ref":null,"references":"","settled_by":"Synthesis, for example through multinucleon-transfer reactions, of superheavy nuclei with $N \\ge 180$ and measurement of their decay chains.","status_note":"The most neutron-rich known superheavy nuclei reach $N = 177$ ($294\\mathrm{Ts}$), seven neutrons short of 184, as of 2026.","title":"Next spherical proton shell closure in superheavy nuclei","topic_ref":"f67ee392625d78a3fea14458356613de3359df8e05ba08b64e875b372b6c34e3"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"59ed6e3e7af6ecdb1055d3e49fe28822608fe600552db146f1e50a77894e0514","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"dc4f0e017d1729a0f81158daabac8da4817858485ea3e03bdc009d29d1c7f90e","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"ijEihsYun5eQrXwJR-dMFxvw3jFOFTbfpDBh0qaLfDpgdmP-ikkA3orBlM4kB8C5PFiJET2c_wxF4_zipFAYCA"},"schema":"pubphys.envelope/1"},"record_hash":"59ed6e3e7af6ecdb1055d3e49fe28822608fe600552db146f1e50a77894e0514","leaf_index":1769}