Saturday, 12 June 2010

IoP Schools Lectures

I've been shortlisted as a possible Schools Lecturer for the Institute of Physics next year. My pitch is about applications of nuclear physics to medicine. Any clever ideas of how to present this to school kids would be most welcome. Please comment!

Thursday, 10 June 2010

Understanding the triple-alpha process

All nuclei heavier than lithium (atomic number 3) are made in stars. It's only pretty recently we've understood that and the confirmation that stars are giant nuclear reactors is one of the great stories of modern physics (which I will not tell here right now!) One of the stumbling blocks to realising that nuclear fusion happens in stars is that it seemed at first like there was no way helium nuclei could fuse to form anything, as they can't fuse with any single thing that's available in stars to make something stable.

The breakthrough was the realisation by Fred Hoyle that what must happen is that three helium nuclei must interact together to form carbon-12. This highly improbably process turns out to happen thanks to a resonance in carbon-12 just around the energy that is available when three helium nuclei meet inside stars. Without it, we would not be here. Some collaborators of mine have just published a really fantastic paper running simulations of this reaction and show how the alpha particles interact. It's available here and it takes the understanding of the process to a new microscopic level. Good work collaborators!

New isotopes

I reported not long ago that there's a new element known to science. Some recent news should be just as exciting as that, but somehow hasn't made the same splash. The news is that 45 new isotopes have been discovered. Discovering a new element means finding a nucleus with a number of protons never before seen, whereas discovering a new isotope means discovering a nucleus where both the number of protons and neutrons in combination have never been seen. In either case, they are nuclei seen for the first time in experiment, and they push our boundaries of knowledge and test our understanding of how nuclei are made.

The press release from the Japanese lab does a good job of explaining their experiment (smashing two known nuclei together and seeing what fragments you end up with). It's pretty exciting: They're getting really close to the r-process path: The route through the table of isotopes that happens in supernovae and is responsible for making much of the matter heavier then iron.

I suppose it makes a recent paper of mine less exciting. We only discovered two new isotopes ;-)