A master list of research seminars

Having previously posted about some online seminar series of interest to nuclear physicists, I have since come across the site https://researchseminars.org/, which contains a big list of research seminars that can be watched live online.  They are hosted by institutes around the world, so you can almost keep watching them 24h a day.  I see that the nuclear reaction seminar series are included there already.  There is a lot of maths and quite a bit of physics, as well as a smaller selection of computer science and biology (at least as I type this post.  Hopefully it will become more inclusive as time goes on).  There's a search and filtering facility, or you can just browse and try something that sounds interesting.  Big mapping class groups fail the Tits alternative, for example.

Not on the list are the UK nuclear physics lockdown seminars, which are perhaps not supposed to be opened to the world community.  I enjoyed hearing about an ex-Surrey undergraduate student's PhD work yesterday when he gave a seminar.  Here's a picture of the seminar just getting ready to start.

David Rowe 1936 – 2020

I learnt from a tweet today from one of his past post-docs that David Rowe died yesterday.  David was a theoretician who worked mainly on nuclear physics, famous for, amongst other things, his application of group theoretical methods in the latter part of his career and on the equations of motion approach to many-body physics earlier on.  I very much enjoyed his first book, covering many-body physics in general and covering in detail the equations of motion approach, and when it came to leaving my office for the last day before lock-down,  I decided that the one book I would fit into my bag would be his book Fundamentals of Nuclear Models, co-written with John Wood. 

David was British-Canadian, with dual nationality, following moving to Canada after study at Cambridge and Oxford, and a research position at the UKAEA with Tony Lane.  He spent the bulk of his career at the University of Toronto and though he retired in 1998, his interest and activities in nuclear theory did not wane.  Indeed, he published a paper in this month's edition of Physical Review C (on a quantized algebraic version of the Bohr-Mottelson Unified Model)

Nuclear Physics Meetings in 2021

Here is my annual post of (low-energy, mostly) nuclear physics meetings taking place around the world.  This is for 2021 and includes some meetings postponed from 2020

18/07–23/07: 14th Nucleus-Nucleus Collisions Conference, Whistler BC, Canada
A conference on collisions between nuclei at a wide range of energies, from superheavy-element fusion to quark-gluon plasma.  I have never been to one of these, but I'm certainly interested in this area, particularly in heavy-ion reactions around the fusion barrier.  I dare say Whistler is a nice place to visit. [website]

New Royal Society Fellows

I see a list of newly-elected members of the Royal Society has appeared.  I carefully checked, but did not see my name there.  Oh well.  Searching on the word 'nuclear' brought up a link of Nobel laureate Donna Strickland's work to nuclear fusion, and the words 'Nuclear Magentic Resonance'.  Next year, then...

UK Lockdown seminars

The UK nuclear physics community has just announced its own series of lockdown seminars to deal with the present situation where were are all working from home.  The idea is to include the sort of people who different nuclear groups from around the UK were planning to have to speak before all live events were cancelled.  The webpage for the initiative is here. 

The first seminar is 3pm BST this Friday, with Alessandro Pastore from York, and there are three seminars every week - on Mondays, Wednesdays, and Fridays.  This fits in well with the nuclear reaction seminar series I'm already (mostly) watching (https://reactionseminar.github.io/schedule), which are on Tuesday and Thursdays.   It's almost like being at a conference...

HIAS Proceedings Online

Way back in ancient times (i.e. before Covid-19), academics used to go and meet up with each other to talk about science and stand around awkwardly in coffee breaks.  Such a thing happened to me last September when I was in Canberra, Australia.  I attended the HIAS conference at the Australian National University (ANU) in Canberra.  HIAS stands for Heavy Ion Accelerator Symposium and it is a regular meeting to showcase the kind of science they can do at their own on-site accelerator facility, though speakers are invited from competing and complementary facilities around the world.  They ask the participants to write up their presentations for the conference proceedings.  I duly did this, and the collected proceedings have been published today in the EPJ Web of Conferences vol 232.

As a (rather large) figure to accompany the post, here is Figure 1 from the first paper in the proceedings.  The paper is an overview of the kind of work they do at the ANU accelerator, written by Andrew Stuchbery.

My own contribution is about what heavy-ion reactions can tell you about the surface energy of nuclei (not much): P. D. Stevenson, EPJ Web of Conferences 232, 03005 (2020)

A rare pair of mirror nuclei

Yesterday a paper appeared in Nature which describes on the second case of a pair of "mirror nuclei" (which differ from each other by having the number of protons and neutrons swapped) in which the ground states have different spin.

The pair in question is strontium-73 (Z=38, N=35) and bromine-73 (Z=35, N=38) which have been measured to have spin-parity assignments of 5/2^– and 1/2^– respectively. The states of mirror nuclei are pretty close to identical, thanks to the isospin symmetry of the nuclear force:  To a good approximation the nuclear force looks the same between pairs of protons, pairs of neutrons and neutron-proton pairs.  There are a couple of ways in which differences appear in mirror nuclei - e.g. because there is also the Coulomb force in play which acts between protons but not neutrons, and these small differences can sometimes cause an effect like the one seen in the Sr-Br pair.  In this case, the small differences are enough to give a different ground state as there seems to be a very low-lying state close to the ground state in these nuclei and the small differences happen to be enough to swap the order of these levels in the two nuclei.  

The figure to the right is part of one of the figures in the supplementary material on the paper.  It's a section in the nuclear chart of isotopes in which the line of N=Z nuclei appears as a vertical line in the middle, and nuclei close to this line are shown - the ones for which mirror pairs are known to exist.  The two pairs coloured in black with little cracks in, are the two cases in which the mirror ground state symmetry is broken.  The other case which was previously known is ¹⁶F/¹⁶N.  In that case the fluorine isotope has its last proton unbound, and it only exists as a nucleus thanks to the Coulomb barrier.  The nitrogen valence proton is not unbound and this significant difference is enough to cause the difference in the ground states.  The same effect is not in play in the Sr-Br case.