Wednesday, 24 April 2019

My first video abstract

With my collaborator, Yoritaka Iwata, I have just published a paper in the New Journal Of Physics.  The paper is about conditions under which two nuclei can react in such a way that the final state of the reaction looks just like the initial state, despite a strong interaction taking place between all the nucleons involved.  If we're right, then our calculations might have implications for inert parts of stars' cores, or one day in nuclear fusion reaction. 

This is the first time I've published in the New Journal of Physics.  They offer the possibility of having a video abstract with our paper, so I opened, probably for the first time, the iMovie software on my computer, made some animations, wrote a script and put it all together.  The final result is on the journal website.

Wednesday, 17 April 2019

Peter Butler FRS



The Royal Society has announced its newly-elected set of Fellows. There is a nuclear physicist amongst the cohort:  Prof. Peter Butler from the University of Liverpool has been made a fellow for his work on experimental nuclear physics.  In particular, they cite his work in reflection-asymmetric nuclei, and the leadership of prorgrammes at laboratories around the world such as at Jyväskylä and CERN.  

Congratulations, Peter!

Thursday, 4 April 2019

Mathpix is pretty neat

Here's a neat piece of software I spotted via a re–tweet from @eddedmondson on Twitter:
It's called Mathpix and it lets you take screen captures of equations which it then turns into LaTeX code.  I thought I'd try it out with something quite stretching in the form of a slightly poorly scanned pdf of Max Planck's paper from 1900 Ueber das Gesetz der Energieverteilung im Normalspectrum.  Here is a screencap of the original equation:



As you can see, it's not perfectly scanned in, especially in the horizontal lines of the fractions.  Mathpix, though, did a fine job.  It said "We had trouble reading that.  Try zooming in for a better result." but the result was exactly right.  Its LaTeX result is

\(E=\frac{8 \pi c h}{\lambda^{5}} \cdot \frac{1}{e^{\frac{c h}{k \lambda \vartheta}}-1}\)

and its own graphical rendering comes out as



So pretty good really.
 


Wednesday, 3 April 2019

Welcome to O-11

The discovery of a new isotope was announced last week in Physical Review Letters (paper here, but it seems no open-access version exists, even on the arXiv).  Oxygen–11, aka 11O, has 8 protons (because it's oxygen) and 3 neutrons (to give it overall mass number 11).  That's a pretty extreme form of Oxygen, whose lightest stable isotope has 8 protons and 8 neutrons.

To make it, the experimenters from the NSCL (National Superconducting Cyclotron Laboratory at Michigan State University) started from a beam of stable oxygen–16 nuclei which they collided on a beryllium–9 (4 protons, 5 neutrons) target.  This bombarding produced a range of nuclei lighter than the oxygen–16 beam from which a magnetic separator was used to focus the oxygen–13 component of the debris into a secondary beam.  This was then sent to another beryllium–9 target.  Some of the reactions between the oxygen–13 and beryllium–9 nuclei caused two neutrons to be knocked out of the oxygen–13 to give oxygen–11.  Oxygen–11 quickly decays to carbon–9 (6 protons, 3 neutrons) and two protons.  These decay products were detected;  their coincident detection and the ability to reconstruct from the detection the properties of the parent oxygen–11 nuclei, repeated through thousands of events enabled the research team to confirm that indeed oxygen–11 had been produced.  

Oxygen–11 is so unstable that it decays not by one of the three traditional radioactive decay mechanisms (alpha, beta, or gamma) but by losing two of its protons, and hence undergoing "two proton radioactivity".  This puts it on the borderline of actually existing as a nucleus at all.  The nucleus is so short-lived and unstable that it does not have a well-defined mass (or equivalently its ground state is not a stationary state of the nuclear Hamiltonian).  The experimental values of the observed mass of 11O is seen to have a spread of values ranging over about 3 MeV/c2.

The picture above is taken from Ed Simpson's excellent Colourful Nuclear Chart.  It currently has a blank space where oxygen–11 will no doubt soon go, just above nitrogen–10, and to the left of oxygen–12.  The black tramlines in the plot show the so–called magic numbers which are numbers of protons and/or neutrons which confer extra stability to the nucleus.  These cross each other at oxygen–10.  I doubt if oxygen–10 will really turn out to be noticeably stable compared to its neighbours.  There is already enough evidence that the magic numbers don't apply in light nuclei so far from stability.  I wonder if the odd stray oxygen–10 nucleus was made in the experiment at NSCL, in too little a quantity to get a good measurement of.

Tuesday, 2 April 2019

Nuclear Physics Meetings in 2020

Bormio: Location of meeting in Jan 2020
Here is a post, which I will add to over the next 18 months or so, listing (mostly low-energy) nuclear physics meetings taking place in 2020 that I hear about.  Feel free to contact me or comment below with details of any that you think should be added

20/01–24/01: 58th Winter Meeting on Nuclear Physics, Bormio, Italy
It's blurb calls it a long-standing conference, and indeed at #58, it may hold a record for the most-held nuclear physics meeting.  The remit is very broad, including what might once have been called nuclear physics, but is now particle physics.  It is preceded by a one-day pre-conference school for students, covering the basics of the main physics areas dealt with in the conference. 

Bormio is in the Italian Alps, and I understand that there is ample time in the programme for leisure activities, such as skiing.

24/02–28/02: Conference on Neutrino and Nuclear Physics (CNNP), Cape Town, South Africa
A conference for those working on the interaction between neutrinos and nuclei, whether it be for beta decay, reactor neutrino studies, dark matter searches, solar and supernova modelling and detector technologies.  Or anything else closely related.  This is the followup to a first CNNP meeting held in Catania in 2017 [website] 

06/04–09/04: IoP Nuclear Physics Conferene, Edinburgh, Scotland
The annual UK Institute of Physics Nuclear Physics conference.

01/06–05/06: Nuclear Photonics 2020, Kurashiki, Japan
A conference on the emerging field of direct interaction and manipulation of nuclei with photons, coming about thanks to the new experimental sources of high-intensity lasers and monochromatic gamma rays.  Not sure there is a website yet.  Here is the first circular.

14/06–19/06: ARIS 2020, Avignon, France
ARIS stands for Advances on Radioactive Isotope Science (sic), and the conference series grew out of a combination of the earlier ENAM (Exotic Nuclei and Atomic Masses, I think) and RNB (Radioactive Nuclear Beams) conferences.  It's quite a general, large conference for work coming out of radioactive beam facilities -- i.e. most of the big nuclear physics labs.  At the time of writing they've sent out a save the date email, but there is not a website to link to yet.

29/06–04/07: 10th Intl. Workshop on Quantum Phase Transitions in Nuclei and Many-body Systems, Dubrovnik, Croatia
"Quantum phase transitions" here means things like the change in shape or some other bulk property of a nucleus as a function of the number of particles with the emphasis being on the interpretation of such phenomena with the language and mathematics of phase transitions.  I enjoyed going to a couple of the earlier outings in this series, but don't really feel connected enough to the field to justify attending any more, interesting though it would be [website]