{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"b0b845748590001ac970e50231992725d37221064c6e4925c9ae4912dccbc5a7","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"1b02421601e0d088cb55883edfb002d2787a262cdf51e0ea17c354d1b8c59d03","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"nuc.limits-of-existence.neutron-drip-line","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"The neutron drip line marks the heaviest isotope of each element that holds on to all its neutrons. It has been mapped experimentally only up to neon, element 10.","posed_since":"","precise":"For $Z=11 \\text{ to } 20$ (sodium to calcium), determine the most neutron-rich isotope bound against one- and multi-neutron emission. 31F and 34Ne are the heaviest bound F and Ne isotopes (Ahn et al., PRL 2019), and 39Na has been observed as bound. Answer: the drip-line nucleus for each $Z$ from Na to Ca, with experimental evidence that the next isotopes are unbound.","problem_ref":null,"references":"","settled_by":"Production cross-section measurements at FRIB at full beam power and at the RIKEN RIBF establishing non-observation limits for the next isotopes.","status_note":"RIKEN reported 39Na as bound (around 2022-2023); the drip line for $Z \\ge 11$ remained unestablished as of 2026.","title":"Location of the neutron drip line beyond neon","topic_ref":"f67ee392625d78a3fea14458356613de3359df8e05ba08b64e875b372b6c34e3"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"423c65cc48bfc3d473c1f0371596b407b81b9543fd4c21376c5bd93ef7ab7b17","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"10619f997e7d896219b7724dd265929681b4490ea89afe28367139568d0350dd","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"4gE1xZ5WrPTzi0onpj4Fje_N0utn8npO92POrreQK_csISYVO6faSqYYLl6hzuAXjZ7SAL3Hn4fBef2exYpFDA"},"schema":"pubphys.envelope/1"},"record_hash":"423c65cc48bfc3d473c1f0371596b407b81b9543fd4c21376c5bd93ef7ab7b17","leaf_index":1768}