{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"d6e17547adf0c9528989e9fcd4d13ae8384767c715e62b85afbd6921f6d81f0e","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["2c5794513268a91b15d1ae24d7fd99ca1992f261eecd5d4f3b7c3cee57a4b788","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"06bc13416e388bc8ce226e598d3e6412dd3e1a46be3726403ab3babac4d9009c","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"beams.nb3sn-cavities.exceed-nb","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"The goal of $\\mathrm{Nb_3Sn}$ is to go beyond niobium, but so far niobium still holds the gradient record. The question is whether any $\\mathrm{Nb_3Sn}$ cavity can beat it.","posed_since":"","precise":"Determine whether a $\\mathrm{Nb_3Sn}$-coated 1.3 GHz elliptical cavity can sustain $E_{\\mathrm{acc}}>0.45\\,\\mathrm{MV}/\\mathrm{cm}$ ($B_{\\mathrm{pk}}>1900\\,\\mathrm{G}$) at any temperature with $Q_{0}>10^{10}$, or whether intrinsic film properties (grain boundaries, thin-film thermal limits) forbid it.","problem_ref":"2c5794513268a91b15d1ae24d7fd99ca1992f261eecd5d4f3b7c3cee57a4b788","references":"","settled_by":"A $\\mathrm{Nb_3Sn}$ cavity test exceeding the Nb record gradient, or a demonstrated intrinsic bound below it.","status_note":"","title":"Can a $\\mathrm{Nb_3Sn}$ cavity exceed the gradient of the best niobium cavities?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"7a96dbed5b9be35e46c64d0f2558fd4334e663c3066fc3394c96685d1285bc6f","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"2e9d8d38cf2e0b78b6a0f7d6d73b16151c483d3277b2984c40a80dd9b69bf9ba","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"rTn4jX4cJkzbQJtXEutCNxcnwdmNJlaSloFnIUiNNyl8WuqkeBkXZZwbXMqELDWajChV2kcSxHUgUeEWgcrJAw"},"schema":"pubphys.envelope/1"},"record_hash":"7a96dbed5b9be35e46c64d0f2558fd4334e663c3066fc3394c96685d1285bc6f","leaf_index":2492}