Thursday, 16 August 2012

Outreach at York

This is a quick public service announcement on behalf of my redoubtable colleague David Jenkins at the University of York. The Physics Department there have a 1-year position going for an Outreach Officer. If you are fancy it, do apply - and tell Dave I sent you :-)

Sunday, 12 August 2012

Holiday in Scotland

[Beach at Ayr]

I've just had an enjoyable week in Ayrshire, Scotland, in the company of some of the scottish part of my family. While I was away, I reached the ripe old age of 38, and it was nice to do it in the presence of my parents, who came up too to stay with my cousin, her husband and their children in the slightly chaotic house they've moved to.

The train journey up went pretty smoothly, though I've never seen such a busy train on a Sunday from Guildford to London. This was presumably due to the olympics. I ended up sitting at a table with a family, while my girlfriend and daughter, Flora, sat together further down the carriage. The little girl opposite me showed great interest in my Saturday prize Independent crossword, which I was trying to finish. I'm not sure that I was really able to give a good answer to her question she asked after some studying of the grid, which was "why haven't you done 16 across yet?"

The holiday was a nice combination of homely relaxation and day trips to fun things. The fun farm just outside Ayr was great. Flora liked feeding the animals and I could hardly peel her away from the "bouncy pillow" trampoline-like thing. This was especially nice as normally she shies away from both physical activity and things crowded with other boisterous children. The Glasgow Science Centre was also really good, easily among the best of such things I've been to, though swimming in the sea in Ayr was just a nice in a different way.

For my birthday itself, my Dad took me to the Ayr Brewing Company's only outlet; a hotel which has the brewery in its garage. Their beer was pretty good, and it was nice to hang out with my Dad, who I don't really see often enough. My girlfriend then took me for a pre-meal glass of champagne in a wine bar, and we then went off to meet everyone else for a meal.

Travelling back yesterday, I learned that alas I yet again failed to win the Saturday prize crossword in the Independent. On the other hand, I'm quite proud of the clue I submitted for the informal competition in the Guardian Crossword Blog this week.

Over all, it was a fairly nuclear-physics free week, though I may have done a little work on a paper about isotope shifts in lead radii - hopefully will submit that one in the next week or so.

Friday, 3 August 2012

Going for Gold!

If you're around my age, the phrase "Going for Gold," which I've been hearing quite a lot lately, will remind you of this. You're very welcome.

Thursday, 2 August 2012

Ring-shaped nuclei

Nuclei are tricksome little beasts.  Made of two types of particles that interact in a quite complex way, according to the rules of quantum mechanics, and via the residual strong force, they can exhibit all sorts of interesting behaviour.

They can come in many shapes.  Their ground states are either spherical, or squashed or stretched spheres (smartie or rugby ball-shaped respectively), or possibly pear-shaped, or even tetrahedral.  If you excite them into some of their natural exitation modes, they can start vibrating, wobbling, or deforming in to new metastable shape configurations.

Over the years, physicists have searched, both experimentally and theoretically for interesting new shape configurations.  Perhaps the most famous topic within the nuclear physics community has been so-called "bubble nuclei" which have largely empty cores, thanks to the decreasing proportion of occupied s-orbitals.  A new paper on the arXiv server appeared earlier this week which looks at toroidal nuclei; those shaped like a lifebuoy or doughnut.  Previous calculations had shown them to be unstable, spontaneously returning to a spherical-like state, but new calculations show that a large amount of angular momentum can stabilise the torus-shaped nucleus, at least for the case of 40Ca that they calculated.

This nucleons in this nucleus would be kept in the ring by the strong nuclear force, and kept out of the centre by the centrifugal barrier.  The alignment of angular momentum would mean that they nucleons would be circulating in the same direction, creating a phenomenal magnetic field.

How such an excited state could actually be made in experiment is not clear.  The predicted excitation energy is extremely high - in a region where most if not all other excited states would quickly lead to fission, but the calculations are certainly interesting.  If the predictions are correct, we are likely to see the thing in nature sooner or later.

edit: I've added a pretty picture from the preprint to the top of the post.  It show a slice through the starting configuration they used for their iteration procedure on the left, and the resulting stable smooth ring predicted by the nuclear force on the right.

T. Ichikawa, J. A. Maruhn, N. Itagaki, K. Matsuyanagi, P. -G. Reinhard, & S. Ohkubo (2012). Existence of exotic torus configuration in high-spin excited states of
  $^{40}$Ca ArXiv arXiv: 1207.6250v1

Wednesday, 1 August 2012

What are Universities for?

I've just read an interesting post on the blog To the left of Centre partially concerning the recent behaviour of Queen Mary University.   It's worth a read, though it is quite depressing.