{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"f117ae5900814ad2655b043fcae714f3729d14c37578256d8a6ab37b8def4c4f","created":"2026-10-03T07:17:53Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"fac0bcdb53b0e9c6c5f33fe69ac98bf4b666d08f493094cd8a0ab65b24f76996","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"amo.constant-variation.th229-alpha-sensitivity","kind":"well-posed","literature_status":"partially-resolved","n":"1","parents":[],"plain":"The thorium-229 nucleus has an unusually low-energy excited state that can be reached by a laser, and its frequency may react to changes in $\\alpha$ thousands of times more than atomic clocks do. How large that factor is depends on nuclear-structure numbers still poorly known.","posed_since":"2006","precise":"Define $K$ by $\\delta \\nu / \\nu = K \\delta \\alpha / \\alpha$ for the $8.36\\,\\mathrm{eV}$ Th-229 isomer transition. Combining the measured quadrupole-moment ratio ($\\Delta Q_0/Q_0 = 1.791(2)\\%$) with charge-radius data gives $K = 5900(2300)$ under a prolate-spheroid nuclear model (Beeks et al, arXiv 2407.17300, 2024). Determine $K$ with uncertainty below 10%, which requires the isomer-ground mean-square charge-radius difference to that precision and a model-independent treatment of the deformation.","problem_ref":null,"references":"","settled_by":"A measurement of the isomer shift of an electronic transition in Th ions with independent atomic-theory field-shift factors, giving $\\delta(r^{2})$ between isomer and ground state to 10%.","status_note":"The 2024-2025 laser spectroscopy of Th-229 in CaF2 established $K$ of order 1e3 to 1e4; the remaining uncertainty is about 40%.","title":"Sensitivity factor $K$ of the $\\mathrm{Th}-229$ nuclear transition to $\\alpha$","topic_ref":"0d5d25a5bcd4a09341050ed67516a89341dcb76395d21eb07382fa82d8edaaf2"},"content_withheld":"false","files":[],"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"86b2395341c42ef83ffcb9c07000e7dbba8dfd9b5dd3dce408e7f1f1eed5f03f","schema":"pubphys.attested/1"},"id_token":null,"id_token_withheld":"false","envelope":{"attested_hash":"eac74472b4da2093ce1eead1c4964eb855bb32d85cc50ce4c04f2148c3a368f0","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"1QBWgxUiTGxDRJkV_0Fl7R76ZJSjIGPCyJopML_qLz9vtjbiM0Y3C1zXOGnXHXbjPZF-AHQ7BZWZNkXHYTeGAA"},"schema":"pubphys.envelope/1"},"ots":{"attested":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEI6sdEcrTaIJPOHurRxJZOuFW7MthcxQzkwE8hSMOjaPDwIOrHXuMiJY89aXIG21ndhqc3wAcHWByfN5VITnpgiTjlCPEg-NFybNzgy1psVRGPzngZ4qDY5cDnB0gAwAwh4cYuee0I8CC_gUjQr3BwcWcj934YFMTIYe7S-MgRpAOv7nhX9Yhb1gjwIL5CwFs1huEYdhH7AE9u1o0tQismhYHklt8vP_jGTuBFCPEg-GVbZyoHkk-1X408yBUqnWu5UnwNk9y7gF_FMbHvxggI8SCjjDatWYxQuIPoTvdscx8D2fCqMuLPOBtHy3OrwNwC8gjwIN2FS6DCzlIoNJsOlzFJfpd8415mNPVYGL_leeeQC_ARCPAg-i1w8XYTwwLG3qixN1bZO-TzEi1eIMuizBgTKFkarQEI8SAVG4HLRiZRZ26g7AYBWDSI50GY2TGlNC7pHIYc-vQ3UgjxIOUdEg6sSGuGAwm6byKNwNSH-CaFtay_ppzVi8InqIsBCPEgUZCxxJx-baWw4JFRfzCCtSjPn4ATBx_3FQi1O2Yo4-8I8SAQuuTPkAGyvS_wKMy9BtKvnki2puESdY2vXem8hT1uIQjwIBGYo5Vxy-d7U5zKv5vp3Ii7hJPH_BDLCzA13c47p9q7CP_wCHbghVgOFMuNCPAQPZK2lHbTMqcCYUotzOQcmQjwIJ7ruRIs6HnufKxCpmLUgeUl0aUu0ov4_3PqcppS-bddCPEgI530vHzdwz_3o9jYQ3WablSaV64Wfn7Pmby5WLyI-A0I8QRqwKw78AhITF7Tr3a1xACD3-MNLvkMjiwraHR0cHM6Ly9ib2IuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZ_AIfrBm5kAMH2cI8BAGKsbR52Yj2ZyRBj8fybyrCPEg15Kg4Ne2LGSKxM-WnEce5gVwiluZijYEWJ8P_lNnKQ4I8QRqwKw68AhHyujKJ6ONvACD3-MNLvkMji4taHR0cHM6Ly9hbGljZS5idGMuY2FsZW5kYXIub3BlbnRpbWVzdGFtcHMub3Jn"],"envelope":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEIwhuuF7BhnIWDZcXAOqyFArgWyPekAAlHMUzUl7zg-vXxIMIYkvCRGwV7ge9PkHlTv9k4CXN_T-W4zuK1ZAxq9sM4CPEguw4-hliu7MAG_VHKIizE6r1leAYJCkhBFeBsUbicdE4I8SDxjodjjQhTphRJ18lOSzX32rPF8rpP9bzw77OlXBaUvwjwIIj09eonpiU7BjGt3qi0RSrgpixm-VUxO9h2rXFNpxmTCPAgr3qPf3JD7cNc7p5mh6i1ygyRV-Op20428mwNjNEe1ggI8CAWGD8ww52x1ErHo66rmGdI5QSagwsYRJEXhZBqGjapsQjwIPK8--gL55dQh9sHOiNl9wEDwwlnKzW3CPI8bHboo39BCPEgD_N0RSyj69vGSrKrlwSNMl9O9vSUHCEATLrRs-xjrdgI8CCnyvApWpXSVFEeuVGtAaM1DHngynmyhNGrDXAgENc__QjwIG_qk_muz-jg8UolhZs34aKKg3vvCTOQfEn-hyT2gbIDCPEgUZCxxJx-baWw4JFRfzCCtSjPn4ATBx_3FQi1O2Yo4-8I8SAQuuTPkAGyvS_wKMy9BtKvnki2puESdY2vXem8hT1uIQjwIBGYo5Vxy-d7U5zKv5vp3Ii7hJPH_BDLCzA13c47p9q7CP_wCHbghVgOFMuNCPAQPZK2lHbTMqcCYUotzOQcmQjwIJ7ruRIs6HnufKxCpmLUgeUl0aUu0ov4_3PqcppS-bddCPEgI530vHzdwz_3o9jYQ3WablSaV64Wfn7Pmby5WLyI-A0I8QRqwKw78AhITF7Tr3a1xACD3-MNLvkMjiwraHR0cHM6Ly9ib2IuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZ_AIfrBm5kAMH2cI8BAGKsbR52Yj2ZyRBj8fybyrCPEg15Kg4Ne2LGSKxM-WnEce5gVwiluZijYEWJ8P_lNnKQ4I8QRqwKw68AhHyujKJ6ONvACD3-MNLvkMji4taHR0cHM6Ly9hbGljZS5idGMuY2FsZW5kYXIub3BlbnRpbWVzdGFtcHMub3Jn"]},"log":{"leaf_index":"394","tree_size":"2123","proof":["e6b69321b801b9ab9d946d9fc4ed07d26c711b0a2d2f3c2cdef1df42d23c29d1","12f0a5bf0388f0c4f354d25b6f5ab73ea9f7c902a5014ac6b00de364ff6928c9","b09ab1f7f4354c0ba36c1c3ed260cb1ec8864b79b3dcfff89de89c71743bf049","311e2e20b4122107d95351067b441f4ac4c66f6c8b40d0937e7f8ea196caf2bd","ce6dd4f6089bdda1e2b9d78bf386c6e8aa2318f24fca62e260bfdf15cc4a828f","6c79b29d4bd8f358f648c984371bd7603dc13097cb16e4663f5232ef0a23c4d6","fee4eac90485f65bf795b98d81f0db11a620075b807c2ab857d78e08b4577c1e","8a297dac130dc4acd5feaaaa62d42dced2d90d76934cb33aca979c2847f3d565","66e75485ba7a96925034b4901057108fa628371f1fb45b0f70d5231fdba2cfac","163bc19e4d81543929a9858fd69dec06a5e93908e5f6ba4d891e7a5e0a43c278","ec3fa24572dee1df200ec665f3e3244d925b199f0f84e225b820c3b66bd7b094","addcf2e0ff7974e4aa99af5e30d409f90d9f4311a4d85f5baf3e125eeb45b4c1"],"checkpoint":"pubphys.com/log/v1\n2123\npXVcluz7BF4vgChQs6lShuU0386gCH0RxrC1sxyE3rI=\n\n— pubphys.com/log/v1 JFPwIOLzsUD22XoTVyTfk/FMVj/u3f3DxZk4V/Ws10KVSS+8WQSwhunQ//EAhyS9Td5CyM0E++85GMezmKd8240j9Q8=\n","promise":null},"orcid_key_evidence":[],"attesting":null}