# Why did they need such short lived isotopes to find pear shaped nuclei?

Recently, pear-shaped nuclei have been discovered. This discovery has interesting implications, as noted in this question: Do pear-shaped nuclei really have anything to do with time travel?

At the moment, the nuclei known to be pear-shaped are 220Rn (half-life of 55.6 s), 224Rn (half-life of 3.63 days) [1] and 144Ba (half-life of 11.5 s) [2].

Why are all pear-shaped nuclei so short lived? Is there any reason preventing pear-shaped nuclei to be stable?

[1] L. P. Gaffney, P. A. Butler et al.:Studies of pear-shaped nuclei using accelerated radioactive beams. Nature 497, 199–204 (09 May 2013) (E-print on L.P. Gaffney's L.U. page)
[2] Bucher, B. et al.: Direct Evidence of Octupole Deformation in Neutron-Rich 144Ba. Phys. Rev. Lett. 116, 112503 (2016) (link to arXiv preprint)

• Hi Matthew, I think you should write a little more about your question, I voted to close because your single line link looks like you are asking a very non mainstream question. Push the link down a bit on the page and expand on it, it might get closed by mistake – user108787 Sep 8 '16 at 7:29
• Hi @Matthew, I've reworded your question to make clear what are you asking. – Bosoneando Sep 8 '16 at 9:04
• Those are actually fairly long lived isotopes (compared with nanoseconds or less). – Jon Custer Sep 8 '16 at 12:27
• @JonCuster Maybe add that as an answer? – Emilio Pisanty Jan 10 '17 at 17:32
• @EmilioPisanty - I appreciate the suggestion, but that really isn't an answer to the question. Of course, I'm still trying to figure out how folks get lifetime measurements of ~1E-22 for, say H-4... – Jon Custer Jan 10 '17 at 17:56

The question is ill formed. That is because these are not short half-lives for nuclei in those regions. Exploring around this interactive table of nuclides shows that $^{220}$Rn's neighbors have half lives of 4.9 minutes ($^{221}$Fr), 25 minutes ($^{221}$Rn), 56 seconds ($^{219}$At), and 3.96 seconds ($^{219}$Rn) and similarly, $^{144}$Ba's neighbors vary from 1.791 seconds to 24.8 seconds. $^{224}$Rn does have an unusually long half life of 107 minutes (not 3.63 days, maybe you meant $^{222}$Rn?) when it's immediate neighbor $^{223}$Rn is only 24.3 minutes (even so, $^{226}$Ra with only two more protons has a half life of 1600 years).