Element 118 has had a sordid past. It literally is a wonderful case study in scientific fraud and how the culture of science always eventually corrects and catches the dishonest individual. Disregarding the juicy aspects of that salacious back-story and moving forward to the recent discovery claim, by Oganessian for element 118. Surprisingly the article wasn’t published in Nature or Physical Review Letters, but in Phys Rev C (PRC). PRC is a journal for nuclear scientists and it just seems odd to me that they didn’t pick a journal with a higher impact factor. Then again Oganessian is already the man in heavyelement’s research so I guess he doesn’t need to be in the lime-light, although he does seem to have a disproportionate number of first author papers. The 118 decay chain is shown below:
Usually, nuclear scientists in the field will make a new element and check to see if it was really made by seeing if the daughters have the same decay characteristics as those already published, we call this a genetic correlation. In this paper we would check to see if the decay characteristics of element 116, 114, and 112 matches with what we have seen previously. The problem is, no one else but the Russians have ever made those isotopes of 116, 114, and 112. So as of yet, they are unconfirmed and still need to be further investigated themselves! That’s the problem of taking a blind leap of faith and running a 118 experiment, the daughters haven’t been investigated, so you end up trying to prove you made what you made by using various theoretical models that point to similar decay characteristics as you expected. To Organessian’s great credit they did not publish their results on 118, which they technically discovered in 2002, but waited until they did further investigations of 116 and 114 and even several chemistry runs for 112. So, in this paper it all matches up, the decay of 118 matches what they saw for 116 and so on.
Unfortunately, the paper has no smoking gun for 118. I define a smoking gun as being an EVR-a-a–a–sf, the bold indicating that the decay occurred when the beam was turned off. Even without that, the background is low enough, that the probability of random correlations seems low and the data still good. One worrisome thing about the 118 claim are the two 118 alphas with 11.65MeV in energy. See their table below highlighted in red.
212Pom has the exact same alpha energy of 11.65MeV. One would also expect to see 212Pom as a common transfer product contaminant in these reactions. Also, from what I understood from their data analysis code, the first alpha in strip 3 should of turned off the beam, and I didn’t see where they explained why it didn’t. Also, having a mean life-time, for 116, ranging from 98ns to 42ms seems too large, even for just 3 events.
In summary, the problem with the work is that 118 doesn’t decay into the known and investigated regions of the periodic table, like element 110(Ds) and 108(Hs). So we can’t say with 100% certainty they made what they said they did. Until the rest of the nuclear community “catches-up” to the Russians with thorough systematic studies all the way from Roentgenium to element 118, we will not be able to evaluate the claim thoughtfully. And since the Americans and the Germans haven’t been able to prove Russia’s 112 element claim thus far, I doubt anyone will be running a 118 confirmation experiment in the near future.
Note 1: You can download the paper here: Oganessian’s element 118 claim
Note 2: No one in the field will ever call element 118 “ununoctium”, so please don’t embarrass yourself.
Note 3: Edited some of my nonsense because of Grejak’s comment below.
Note 4: I think the Swiss did do a 112 chemistry experiment from the short-lived 114 alpha decay, but that is still unpublished to my knowledge.