{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"050b14eed6a830a33f022aa2198481b477e8e508cf7cc6a2e7fd93bf84dff432","created":"2026-10-03T07:18:07Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"bdc4c14705283168f967ac2eca81b6fd3f54919734045cebb08e7d2e7cf17c02","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"nuc.fission-theory.mercury-asymmetric","kind":"phenomenon","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Mercury-180 was expected to split into two equal halves, zirconium-90 nuclei, but a 2010 experiment found it splits unevenly. Which nuclear structure makes the split uneven in this region, far from the uranium-like nuclei where uneven fission is common, is only partly understood.","posed_since":"2010","precise":"Explain the asymmetric mass distribution observed in beta-delayed fission of $180\\mathrm{Hg}$ (peaks near $A \\sim 80$ and 100) and the evolution toward symmetric fission in heavier Hg and Pb isotopes. The answer is the shell structure of the pre-scission configuration or of the nascent fragments (for example octupole-deformed proton or neutron numbers) that controls the asymmetry, with quantitative yield predictions for neighbouring isotopes.","problem_ref":null,"references":"","settled_by":"A microscopic calculation that reproduces the measured mass yields of 178,180,182Hg and correctly predicts the asymmetric-to-symmetric transition across the region before it is measured.","status_note":"Calculations attribute the asymmetry to deformed shell effects in the nascent fragments, and 2025 work studied how excitation energy and angular momentum move the transition in 180Hg.","title":"Origin of asymmetric fission in neutron-deficient mercury isotopes","topic_ref":"4682ec98f6efef769b56a4880afd87dd00cb0bc4ad4f0a7af1b11de1483f7592"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"9bc80af0e0e83d6720070154bfb4e21df138f016f1632f272882b385f2c0c46f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"b29e7d7fde2f02ba7dad0375fafc40e471613e71a614904296ee1adae5611d4b","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"tNmKggeHbv8ybEy7LSnwTeN5LAilxwgUZTtzb7yjIrId4cf3-3CrPzHk7m7Ti6ck7FOild3Yx5q7CQ8vD-ZsCA"},"schema":"pubphys.envelope/1"},"record_hash":"9bc80af0e0e83d6720070154bfb4e21df138f016f1632f272882b385f2c0c46f","leaf_index":1753}