{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"27e4aad6a01cd65a0b133735c38c21cb7fec7a4ab0954a60c7fd3ee3363fcc90","created":"2026-10-03T07:18:08Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"ca62dc8466b45f7a0c1ca55a3bf842a5a7b9c6d9b3bc25ece6d6450e2d2cd704","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"nuc.stellar-reaction-rates.electron-screening-excess","kind":"phenomenon","literature_status":"open","n":"1","parents":[],"plain":"The electrons around target atoms partly hide the electric repulsion between colliding nuclei, which raises measured low-energy reaction rates. The measured boost is larger than the maximum that atomic physics seems to allow, and nobody knows why.","posed_since":"","precise":"Low-energy measurements of $3\\mathrm{He}(d,p)4\\mathrm{He}$, $6,7\\mathrm{Li}(p,\\alpha)$ and $d(d,p)t$ yield screening potentials $U_e$, defined by $\\sigma_{\\mathrm{screened}}(E)/\\sigma_{\\mathrm{bare}}(E)\\sim \\operatorname{exp}(\\pi \\eta U_e/E)$ with $\\eta$ the Sommerfeld parameter, that exceed the adiabatic limit $U_{\\mathrm{ad}}$ (the difference in electron binding between the separated atoms and the united atom) by up to a factor $\\sim 2$ in gas targets and by an order of magnitude for deuterons in some metal hosts. Explain the excess quantitatively, and determine whether the error lies in the screening physics, in stopping-power corrections, or in the extrapolated bare S-factors.","problem_ref":null,"references":"","settled_by":"A calculation of $U_e$ from atomic and solid-state theory that reproduces gas and metal data for the same reaction, or an independent determination of the bare $S$-factor (for example by the Trojan-horse method) that removes the excess.","status_note":"A 2023 palladium measurement found $U_{e}$ up to ten times model values, and a 2023 analysis argued that resonance strengths need no laboratory screening correction at all.","title":"Why laboratory electron-screening potentials exceed the adiabatic limit","topic_ref":"a34c6b5ed7af37b4290d97a2613b13b71248636c2138e338345ab4d03e765618"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"4ea2db8d2c3f108a98346aea06c8b728ceb2fa32cea785043977ab5a8fb15532","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"6db3565026fc3c89cf3b8f72ce1a2434569d01cbae2a0db4b8e8fc9715f16f74","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"czBz3VE6aAlITtaHcbIrMl-LxrCEUc12NW9envDHYpmSKPru3DkdnlKVKyMJsu3BjoChlQaIUqGq4jr0gwi5Aw"},"schema":"pubphys.envelope/1"},"record_hash":"4ea2db8d2c3f108a98346aea06c8b728ceb2fa32cea785043977ab5a8fb15532","leaf_index":1814}