Tuesday, 30 October 2018

COMEX6: Day 1

We've had a first, and rather full, day at the COMEX6 conference.  From the hotel at 7:45 to get a bus to iThemba Labs, who are organising the conference (though for the rest of the week we will use the hotel conference room, so no busing back and forth).  The labs are about a 30m ride from downtown Cape Town, and are a fairly typical nuclear physics facility with their big buildings housing accelerators, and their own unique set of animals wandering around outside (different from GANIL's many rabbits) .  The conference room is great, with probably the most comfortable lecture room seats I have come across.  Well done iThemba Labs.

As at most conference, they handed out a pad of paper on which we delegates can make notes.  No doubt we don't all use it:  some will not make notes, some will do it on computer or in their own notebooks.  I did make notes, filling up about half the 50-page A5 notebook, as well as start a list of calculations I can make that relate to the talks (that's taken up one of the pages, so far).  So plenty of interesting ideas out there in the conference for me.  I've started some of the calculations going, to try to understand the question posed in the title of one of the talks; "Are the molybdenums fluffy too?"  If course, the answer given in the talk follows the rule that the answer to questions posed in the title of science talks is "no".

The day ended with a tour of the lab, during which I took the pictures posted here.  Then we had the poster session and a dinner, which was mostly a braai (a kind of barbecue) except for us vegetarians, who got vegetable curry.  Yummy.

Monday, 29 October 2018

Puns in author lists

A tweet, below, that I saw yesterday asks (jokingly, I assume) for potential scientific collaborators just to make amusing author lists:
There is already a famous example in nuclear (astro-)physics: The Alpher, Bethe, Gamow paper whose author list was partly contrived to make a play on the first three letters of the Greek alphabet.

With my surname (Stevenson) I don't see much scope for good co-authorship puns.  Perhaps I should marry my partner, and take her surname, Fox.  Then I can collaborate with a Hunt, Hunter, Cub or Trot (if those are even names), or perhaps just changed my title to "Fantastic Mr".

Readers, are you aware of any other such punning author lists, or have any aspirations of your own?

Sunday, 28 October 2018


 I'm in Cape Town for COMEX6: COllective Motion in nuclei under EXtreme conditions.  I've not been to sub-saharan Africa before, and this is about as sub as it gets, I guess.  I have been a sporadic attender of the COMEX conference because part of my work involves studying giant resonances -- excited states of nuclei which are collective, meaning many or all the protons and neutrons in the nucleus are acting together in the excitation.  In particular, my most recent PhD student and I looked at the magnetic spin-dipole excitation, and how often-neglected terms in the nuclear interaction have a strong effect on the structure of these excitations.  We put a paper up on the arXiv about it (https://arxiv.org/abs/1709.07823) last year.  Now, here in Cape Town while immersed in the topic, may be the time I do one final supplementary calculation on the results in that paper to get it finally published in a journal.

Saturday, 20 October 2018

People's Vote March

Today I was one of the c.650,000 people who marched in central London, hoping to push for a vote on any final deal on Brexit.  Hopefully a "Leave with the presented deal, or Remain" kind of vote.  Not only were there a lot of people there, but what seemed to me a very wide cross section of people.  Clearly in terms of age there were, but also in terms of, say, proxies on social indicators and lifestyles such as dress.  In other words, it wasn't a group of semi-professional protestors, but a lot of people frustrated at the omnishambolic brexit route we are currently heading down.  Guess we'll see if it has any effect.

Friday, 19 October 2018

Piers review

Since my last post about my contribution to Piers Morgan's #papoosegate, I have found myself appearing in various places in the media.  

Here I am in Huffington Post; here in BuzzFeed; here MSN; here bento.de.

Fortunately, though media attention can be unwelcome, it is not the dads with children in slings who are being mauled here.  The whole thing is somewhat silly, prompted by a ridiculous statement from Piers Morgan that couldn't be left unchallenged.  The men who are walking round carrying their children in slings are not heroes.  We are just doing what we are supposed to -- parenting.  Too bad that some prominent men try to put us off doing it.

Tuesday, 16 October 2018

Carrying the baby

My good deed for this morning was to respond to a tweet by Piers Morgan, in which he bemoans that James Bond actor Daniel Craig should be so emasculated as to carry his child in a sling:
Already, there are a lot of great responses to the tweet.  A lot of pictures of men happily carrying their children.  I couldn't resist posting the same:
The picture is actually a little over a year old.  I carried the same child, now bigger, in the same sling, as I dropped one of his sisters off at school this morning, but I seem not to have taken a sling-selfie with him for quite a while!

Wednesday, 10 October 2018

A journal from Croydon

Croydon, erstwhile part of Surrey (until 1965), is a place subject to much comedy at its expense.  Mind you, this is true of Surrey in general, which is England's archetype of a Home County.  Any comedy writer wishing to evoke a sense of smug  conservative, curtain-twitching, self-satisfied middle-Englandness, or just plain suburban mundanity need look no further than the county of Surrey.  Where else would the Durselys live in the Harry Potter series?  Where would Ford Prefect claim to have come from as cover in The Hitchhikers' Guide to the Galaxy?  Where would Tom and Barbara Good play out their dreams of self-sufficiency, outraging their neighbours' sense of propriety in The Good Life, if not in Surrey?  

I think Croydon is a fine place.  One thing that I didn't know about it until today is that it once had a Natural History and Scientific Society.  It was in existence around 100 years ago, when the terms Natural History and Science had about equal currency.  I found it out because I came across a reference to a paper published in its Proceedings:

Now I want to publish all my papers there, but I rather suspect the journal is defunct.  Presumably I would have to go and read my papers to the society first before publication.  

In the source I found this reference from (annual report of the British Association for the Advancement of Science, 1910) there are a bunch of neat parochial journals cited: Bradford Scientific Journal, Report Royal Cornwall Poly. Soc., Report Ealing Sci. Mic. Soc., Journal of Ipswich and District Field Club.  All, I suppose, have ceased publishing.

The picture at the top is of passengers waiting at East Croydon station.

edit: I'm quite wrong about the Croydon Society being defunct.  Not only does it still exist, but it still publishes proceedings: https://cnhss.co.uk/booksproceedings/

Wednesday, 3 October 2018

The actual Nobel Prize

Following yesterday's Physics Nobel prize announcement, and my post on the perspectives for a nuclear physicist to win any time soon, my colleague Prof Jeremy Allam has written a nice post on the work of two of the three winners of this year's prize.  I re–blog it below, and attach a picture (pre–beard) of the author:

By Prof Jeremy Allam, University of Surrey, 2 Oct 2018
You might have seen yesterday’s announcement of the 2018 Nobel Prize for Physics. Here’s my attempt to explain the work of two of the recipients, with a bit more detail than most of the press releases – but hopefully not too much physics jargon.

Why were Donna Strickland and Gerard Mourou Awarded the Nobel Prize?
In 1985 they invented the technique of “chirped pulse amplification” (CPA) which made it possible to generate laser light pulses of extremely high intensity and extremely short duration.
What’s so Great About Short Duration Light Pulses?
Light pulses that persist for only a very short time have many applications. For example, the speed at which data can be sent via the internet depends on the number of separate laser pulses you can send down an optical fibre in a given time: this web page reaches you on the back of laser pulses each of which is shorter than a thousandth of a millionth of a second. But modern “ultrafast” lasers can generate a flash of light that lasts only a few femtoseconds (or less): a femtosecond is a thousandth of a millionth of a millionth of a second, or 0.000000000000001 seconds. This time is short compared to many processes in physics, chemistry and biology, so femtosecond laser pulses make a great ‘stopwatch’ that allows us to study, for example, how long a pair of molecules takes to react, or how long the initial stages of vision take within the human eye. Such times are much too short to measure directly, but a stream of femtosecond light pulses can make the process visible on slower timescales, in much the same way that a strobe light in a disco seems to slow down the movements of a dancer.
What About the Very High Intensities?
A continuous (always on) laser beam with similar power to a domestic light bulb, if tightly focused to a small spot on a material, can cause damage or even cut through materials such as  steel. The energy from the light melts the material rather like a blow torch. In an ultrashort laser pulse, the energy of the light is concentrated in a very short but very bright flash, and the effect on material is more like a lightning strike. The laser pulse may have enough energy to directly vaporise material, or even to rip apart atoms. A consequence is that laser cutting of materials is much cleaner and more precise when ultrashort pulses are used, and femtosecond laser micromachining has quickly become a standard manufacturing process. Another well-known application is in corrective eye surgery, where a femtosecond laser is used to precisely cut a flap in the surface of the eye, before reshaping of the underlying material and reattachment of the flap; here the reduced damage of surrounding areas is an important advantage from the use of ultrashort laser pulses. Another use in scientific research is the generation of light pulses with a wide range of colours (wavelengths from the ultraviolet to the far-infrared). Light pulses travelling in certain materials can change their colour, and the more intense the pulse, the more efficient is the colour conversion. The response of materials to the different colours (‘spectroscopy’) can be used to identify or characterise the materials.
How Does Chirped Pulse Amplification (CPA) Work?
Lasers and laser amplifiers make use of a process (predicted by Einstein in 1917) called stimulated emission, where under special conditions a material can make copies of the packets of light that pass through it, leading to an increase in the intensity of the light beam. The difficulty in amplifying short, intense light pulses is that they damage the material they pass through, so there is an upper limit on the intensity that can be reached. Strickland and Mourou overcame this problem in a very clever way, that made use of the fact that a short light pulse always contains a mixture of colours.  It has been known since Newton’s experiment in 1666 that passing light through a prism* will separate the different colours, which can then be made to travel along different paths before being reassembled into a beam by a second prism. The red colours can be made to arrive before the blue colours: this changing colour (or frequency) of the light is a bit like the change in pitch of a note in a bird song – hence the name “chirp”. Because the energy of the pulse has been stretched in time, its intensity is reduced and it can be safely amplified. The amplified chirped pulse can then be passed through a pair of prisms that are a mirror image of the first pair, which reassembles the different colours back into an ultrashort light pulse, that can be many orders of magnitude brighter than the initial pulse.
CPA laser amplifiers are now commercially available in table-top systems that are widely represented in research labs including the Advanced Technology Institute at the University of Surrey (https://www.surrey.ac.uk/photonics-quantum-sciences-group/facilities/ultrafast-laser-laboratory). Such systems may have peak powers of a few Gigawatts (a thousand million Watts) – comparable (for a very short time!) to the output of a nuclear power station. Large scale facilities such as the Vulcan laser at the Rutherford Appleton Laboratory (https://www.clf.stfc.ac.uk/Pages/Vulcan.aspx) achieve quite staggering powers in the Petawatt range (a thousand million million Watts or 1,000,000,000,000,000 Watts). Such intense light pulses can be used as compact particle accelerators, or as sources of bright X-rays that reveal not only the structure of solids but also how they move. They can recreate, within the laboratory, conditions similar to those inside stars or in remnants of supernova, or be used to contain nuclear fusion reactions. By a technique called harmonic generation, even shorter (attosecond) light pulses have been produced that allow the motion of electrons in atoms and molecules to be tracked. Even more powerful systems are under construction, in facilities such as the Extreme Light Infrastructure project (https://eli-laser.eu/the-eli-project/), and will open up the study of extreme states of matter as well as future applications in fields including oncology and medical imaging.

(*Strickland and Mourou used a diffraction grating instead of a prism, but the principle is the same).
Why are Female Physicists in the News?
Shockingly, Donna Strickland is only the third ever female recipient of a Nobel prize in physics – although it is not difficult to think of worthy candidates. Today’s news comes shortly after media reports of some daft comments on the contribution of male and female physicists made by a Professor from Pisa University at a workshop organised by CERN (https://www.bbc.co.uk/news/world-europe-45703700). But amongst the media noise it’s important to remember that the 2018 Nobel prize was awarded to Donna Strickland due to the originality of her research and its profound implications for science and technology.

Tuesday, 2 October 2018

Nuclear nobel prize

It's the beginning of the first week of semester here on campus, which makes life hectic, but also reminds me that it's the time of year when the Nobel prizes are announced.  I idly thought, "oh, I wonder if it will go to a nuclear physicist," before pessimistically recalling that nuclear physics is a dead field.  Then, with second thoughts about my cynicism, I tried to think of any likely candidates.

I think the nuclear physics front–runner has to be from the various teams that have led the discovery of the superheavy elements, particularly those leading to the recently–authorised namings up to element 118.  That would put Yuri Oganessian, from Dubna, Russia, in the forefront, with members of the GSI, Germany, team being in serious contention, too.  In particular Sigurd Hofmann, Gottfried Münzenberg, and Peter Armbruster.  Of course, the teams included many others, but the Nobel prize works by placing all the glory on a few (up to three).

Still, I think it's unlikely to go to nuclear physics, but you never know.  I asked my colleague last night if she had any ideas who might be in the running.  She didn't except to say "I bet it'll be men,"  which is a good point, so at least my suggestion above has already cleared the biggest hurdle to winning the prize.

Here's a selfie I took with Prof Oganessian earlier this year.

edit:  Making the post only a few hours before the announcement is not necessarily a great idea.  The prize has gone to  Dr Ashkin, Mourou and Strickland for work on high–intensity lasers.  As my colleague has pointed out, the work is relevant for nuclear physics research.  And more than that, one of the winners, Dr Strickland, is the first woman to win the prize since Marie Göppert-Mayer, who won the prize (for nuclear physics) in 1963.