Odd-Z Transactinide Compound Nucleus Reactions Including the Discovery of 260Bh - Wilk - Dance Your PhD 2012

My PhD research was on studying pairs of heavy-element reactions to see if there was a better way to make these isotopes. By shooting an ion beam of a particular energy from an accelerator at a target and measuring the decays of the particular isotope we made in a detector further away, we can determine the reaction probability (cross section) of that reaction. The cross section is a ratio of the production rate of the thing you want to make by the beam dose per unit area by the number of target nuclei per unit area. If you make the same isotope two different ways and one way has a significantly higher cross section, it indicates a favored reaction. In my dissertation research I looked at eight different reactions, or four pairs, making the elements Db, Bh, Mt, and Rg. If you aren’t familiar with those elements, look at the bottom of the transition metals on the periodic table.

The cyclotron accelerates beam ions in an outwardly spiraling horizontal path. If you look closely you can see that the beam ball color and the target hoop color are combined in the hoop color of the product atom, most of the time. (I didn’t have any white LED beam balls.) I used t-shirts of different colors with their element symbols to show that the combination of the beam ball and target hoop made something completely different. The product atom recoils out of the target and travels along with unreacted beam and gets separated along the way to the detector. The decaying atom of Mt first undergoes alpha decay by getting rid of the yellow ball. The so-called “daughter” product Bh also decays by alpha emission to Db, but the Db atom grabs a red ball representing an electron and turns into Rf. This isotope of Rf spontaneously fissions – or splits in two – and that ends the decay chain. I used this same kind of experimental method to discover the new isotope 260Bh, which is so awesome I had to use fire to represent it.

You see eight “data points” towards the end of the video but I only list five reactions plus the new isotope because those are the ones I did myself. The other three data points were added to my results from a thorough meta-analysis of the literature. The short answer to the question of “is there a favored reaction method?” is NO. The statistical uncertainty in the cross sections of each reaction pair overlap, represented at the end by the rotating hoops.

Thanks for watching!