Talk:Beryllium-8

Natural abundance

“Trace” where? Should the reader expect the infobox to tell about abundance in stars? And not photosphere but in the core, and even not of our Sun but in some red giants, massive stars, or alike. Incnis Mrsi (talk) 08:35, 12 July 2019 (UTC)

@Incnis Mrsi: I changed the abundance to zero in the infobox as there indeed is no source of ⁸Be on Earth, and added a note on its transient existence in the cores of helium-burning stars. ComplexRational (talk) 10:49, 12 July 2019 (UTC)

decay_energy1

Surely is it 6.8 eV not 92 keV? I suppose that 6 eV is indeed the resonance width, another quantity characterizing decay. By the way, what exactly is “92 keV”: the total kinetic energy (CoM) or the energy of one α-particle? For ⁸Be we have the former equal 2× the latter. Incnis Mrsi (talk) 10:47, 30 July 2019 (UTC)

@Incnis Mrsi: Every source I found gives 92 keV or something close to that (e.g. 91.84 keV in NUBASE and [1]). As is explained in several of the references, 92 keV is the difference in energy between the ⁸Be ground state and two ⁴He nuclei; thus, 92 keV is the total amount of energy released during decay (or consumed in production) of ⁸Be. 6 eV, meanwhile, is given as the resonance width in the same sources, and is said to directly correlate with the half-life. I'm leaving 91.84 keV in the infobox until/unless a better source is found. ComplexRational (talk) 15:06, 30 July 2019 (UTC)

⁸Be nucleus is only held together by a low Coulomb barrier

Unfortunately I missed the moment when the rubbish found its way to the article. Both α-particles have positive charge. Guys, you certainly know electrostatics enough to realize implications about the “barrier” when to look from inside. Incnis Mrsi (talk) 17:17, 14 August 2019 (UTC)

For starters, calling statements "rubbish" is incivil; these types of comments certainly will not help in fixing anything or collaboration to achieve that goal.

Regarding this statement, the role of the Coulomb barrier is presented in a similar way in ref 8 (Coc & Vangioni, 2014). Specifically, the Coulomb barrier is described as the only reason the nucleus stays together for 10⁻¹⁶ seconds (on page 27), and may be described as low (or perhaps even nonexistent) because the nucleus is just two alpha particles, with nothing else hindering the escape of an alpha particle. Perhaps it was worded imprecisely (e.g. without 'low' may exactly reflect the source), but the relationship between the Coulomb barrier and the half-life is verified.

Also, would you mind clarifying the latter part of your post (implications...looking from the inside)? This source seems to describe everything that is immediately relevant, and a further analysis or explanation of the physics would require another dedicated source. ComplexRational (talk) 19:24, 14 August 2019 (UTC)

⁸Be is obviously held by the nuclear force, like any other nuclide (except for ¹
H
and ¹
n
). The Coulomb barrier—understood literally as a barrier of the Coulomb force, not a far-reaching generalization—is relevant to its decay energy, not to half-life. Incnis Mrsi (talk) 19:35, 14 August 2019 (UTC)

Damn, I initially missed the adjective low. May we settle on “The system of two α-particles has a low energy of the Coulomb barrier, which enables its existence for any significant length of time”? Incnis Mrsi (talk) 19:42, 14 August 2019 (UTC)

Yes, that would be fine. Thank you. ComplexRational (talk) 19:52, 14 August 2019 (UTC)

Online. Sorry, I overreacted to the thing which was formulated confusingly, but made sense. Additionally I was distracted by the user who undid my wikicode fix. Incnis Mrsi (talk)

I see, it looks good where it is (and I relocated the ref which says this). Again, thank you for understanding and clarifying this matter. ComplexRational (talk) 20:11, 14 August 2019 (UTC)