Thursday, 5 March 2015

... and then there were three

The University of York has announced the appointment of Prof. Jacek Dobaczewski as the head of their newly-created theoretical nuclear physics group.  

This brings the number of nuclear theory groups in the UK to three (though see footnote on a previous post).  Soon there will be an advert for a lectureship at York, too, and the historical anomaly of nuclear theory being conspicuously undermanned will start to reverse.  

From my point of view, it's great to have Jacek here.  His research area, in density functional theory, has a large overlap with my own, and for the first time since I've been an academic in the UK, my PhD students will now have the possibility of moving to another UK group for a post-doctoral position after completing their PhD.  

Friday, 20 February 2015


I'm going to see Deerhoof in London next week.  If you're as excited about it as me, you might want to check out the video below

Monday, 16 February 2015

No physics PhDs were awarded in the UK before 1990

The panel which judged the physics submissions as part of the recent REF has written an overview report on its findings.  The panel was responsible for several subjects across science and engineering, and the report consists of a general section covering its whole remit, followed by sections on each individual discipline. 

The specific mention of nuclear physics in the report was a little damning.  It reads
Nuclear physics had a smaller share of world-leading outputs compared with other areas. This may be due to the failure of the UK to invest in major international facilities in the last 20 years, thus reducing the scope of UK research and influence in this field. There is concern that the small number of theoretical nuclear physicists is sub-critical and that this weakens the theoretical underpinning of the subject.
The comparison in the first sentence is unfortunate, and even if the outputs (research papers, basically) are good on some kind of absolute scale, the reading is that nuclear groups drag their departments down a bit, on average.  It's curious where the panel suggests the blame may lie – not that we are (necessarily) duffers, but are struggling along with sub-critical support. 

The earlier part of the report has some interesting statistics in it. For example, it gives the number of PhDs awarded in each of the panel's sub-areas, including physics.  I decided to make a plot of the numbers, which they give for the years 2009, 2010, 2011, 2012 & 2013.  The results are in the left-hand panel of the attached plot, represented by squares.  I include, too, a line of best fit, showing the clear trend of steady increase. 

In the right-hand panel, that trend line is extended back, and it is seen that it the line crosses the zero mark around the year 1990.  Clearly, then, one should treat with scepticism any claims by people who say they got a PhD in physics in the UK prior to 1990.

Monday, 2 February 2015

Isotopes from 2014

The annual update from the Isotope Discovery Project hit the arXiv preprint server last week.   According to it, 2014 saw the first ever human observation of Neon–15, Cobalt–77, Nickel–80, Iridium–164, Actinium–205 and Lawrencium–266.  Welcome, new nuclides!  Oh, except you've all decayed already.  Well,  It was nice to see you all, albeit fleetingly.

Tuesday, 20 January 2015

REF submissions online

Just before Christmas I posted about the results of the REF2014 exercise, which the British government will use to decide how to allocate research funding to Universities.  

Yesterday, the submissions from each University were added to the REF site, so if you want to put yourself through the same experience as the panel members tasked with reading the judging the submissions, you are now in a position to do so.  Try not to make the server fall over.

Thursday, 15 January 2015

Samarium from the stars

Over the Christmas period, I enjoyed time with my family, sharing presents, eating more food than normal, and suchlike.  One of the perks of my job is that the University shuts down between Christmas and new year, and we are not expected to be in the office.  Not so the stakhanovites at the American Physical Society.  They beavered away producing a regular weekly edition of Physical Review Letters, and the edition for the week ending 31st Dec came out as usual, with online articles being populated during the week in question. 

One of the articles in that edition is entitled Isomer Decay Spectroscopy of 164Sm and 166Gd: Midshell Collectivity around N=100.  It may not sound like the catchiest title, but it does the job, and its lead author is none other than University of Surrey PhD student Zena Patel.

The purpose of the work was to explore nuclei in the large unknown region of the nuclear chart - the rather neutron rich isotopes of elements in the middle of the mass range.  Isotopes that only ever exist in nature fleetingly in supernovae or other fast astrophysical processes.  The elements mentioned in the title, Sm = Samarium and Gd = Gadolinium, both exist on the earth, but only in certain isotopic forms.  Samarium has atomic number 62, so the nuclei have 62 protons.  They can in principle have any number of neutrons to help bind the nucleus together, but only certain quantities are sufficiently stable to last long enough to be found on Earth.  The most common isotope is 152Sm (having 90 neutrons because 90+62=152), which is observed to be stable, and 154Sm (92 neutrons) is also observed to be stable.  The isotope made in the experiments described in the paper is 164Sm, with 102 neutrons.  They make it not by trying to add neutrons to lighter isotopes, but by smashing uranium nuclei against a target, causing them to split up, and selecting those cases in which one of the fragments is a isotope of 164Sm.

The fragments are made in highly excited states, which soon decay to their ground state by emitting gamma rays.  Only, sometimes they don't emit those gamma rays quite so quickly, if the nuclei get caught in isomeric states -- states effectively defined as those that don't decay as quickly as you might expect.  The reasons usually translate into details of the structure of those states;  they could be spinning in such a way that makes them a bit more stable, for example.  My colleagues here at Surrey, with their collaborators from around the world, not least at RIKEN in Japan where the experiment took place, deduced from the experiments that having 100 neutrons conferred an extra stability to nuclei in that region corresponding to what we call a "magic" number.  Their results help explain why certain elements are more common than others;  all to do with how nucleosynthesis processes work in stars.  They worked it out not by going to stars and making experiments there, but by going to Japan.

The researchers here at Surrey, with the help of the marketing department, did a good job of writing a press-release that got picked up by a lot of places.  The snapshot attached to this post is from a YouTube channel called DNews, who presented a story about the research.

citation details are below:

Patel, Z., Söderström, P., Podolyák, Z., Regan, P., Walker, P., Watanabe, H., Ideguchi, E., Simpson, G., Liu, H., Nishimura, S., Wu, Q., Xu, F., Browne, F., Doornenbal, P., Lorusso, G., Rice, S., Sinclair, L., Sumikama, T., Wu, J., Xu, Z., Aoi, N., Baba, H., Bello Garrote, F., Benzoni, G., Daido, R., Fang, Y., Fukuda, N., Gey, G., Go, S., Gottardo, A., Inabe, N., Isobe, T., Kameda, D., Kobayashi, K., Kobayashi, M., Komatsubara, T., Kojouharov, I., Kubo, T., Kurz, N., Kuti, I., Li, Z., Matsushita, M., Michimasa, S., Moon, C., Nishibata, H., Nishizuka, I., Odahara, A., Şahin, E., Sakurai, H., Schaffner, H., Suzuki, H., Takeda, H., Tanaka, M., Taprogge, J., Vajta, Z., Yagi, A., & Yokoyama, R. (2014). Isomer Decay Spectroscopy of Sm164 and Gd166: Midshell Collectivity Around N=100 Physical Review Letters, 113 (26) DOI: 10.1103/PhysRevLett.113.262502

Friday, 9 January 2015

Reflections on time in Oxford

A friend from my undergraduate days has just written a very thoughtful blog post on his time there.  It's kind of aimed at students who have just discovered they had not got into Oxbridge, and how he rather wishes he hadn't too.  Well worth a read, in my opinion.  I was certainly aware of quite a few people who went to Oxford who would have benefitted from being somewhere else.

The post is here

As ever, I like to include a picture with each post.  I hope Alex won't mind me linking to this one I found by searching for him!