... and major new discoveries in this area ceased to be made in Cambridge

In Charles Clement's biographical article on Tony Lane, the following matter of fact description of the demise of nuclear and high energy physics in Cambridge is summarized neatly as

"In the late 1950s, theorists in high-energy fundamental-particle physics in Cambridge moved out of the Cavendish Laboratory away from experiment into the Department of Applied Mathematics and Theoretical Physics (DAMTP), and major new discoveries in this area ceased to be made in Cambridge."

 - a salutory warning to us all!

 

My name will live on forever

Some time ago, I blogged about the over-use of girls' names used to name physics things.  This was prompted by a Tweet stating "we are not decoration!"

Today I learnt about a new facility in South Africa called PAUL.  This is my name, and it's a male name, so I guess it slowly helps redress the balance. 

It's an underground facility for the kind of experiment where you want a low background of cosmic radiation.  Here's a picture below of a CAD picture of part of the setup, from the website above.

Solid State Physics: Ashcroft and Mermin

 So... at the beginning of last month I posted about a plan to take one of the books I have on my physics bookshelf each month and do something worthwhile with it - learn something that I didn't know, work through some problem and see what enlightenment I get, even kick-start a research project, and then report back here with what I've learnt.

The first book, as prompted by a post on X (a website I have left in favour of BlueSky), was Ashcroft and Mermin's weighty textbook on Solid State Physics.  I should preface this whole post by saying that I'm a bit disappointed (with myself) for not carefully managing my time to get more out of the book, but, you know, life.  It's been probably a busier September than most years.  It's the one year that all 4 of my kids are in school, with the youngest starting Reception Year and the oldest in Year 13, and its freshers flu season, and all sorts of other reasons ... I got "promoted" to be the representative of nuclear physics at STFC's science board at very short notice and that knocked out a couple of days. 

Well, so much for the excuses.  What about the book?  

I picked up a copy of the book when I was a PhD student, bought from Oxford's Blackwell's bookshop.  There's still a sticker on the back of the book telling me that I paid £25.95 for it, which even in the late 90s was not a bad price for a hefty 800-page hardback advanced-level textbook.  Despite the pretty poor rate of the PhD stipend in those days, it was the first time in my life I felt rich enough to splash out £26 on textbooks.  My PhD was not in Solid State Physics but I recognised it as an interesting area that I understood to be a ripe area for a would-be theoretical physics to do a PhD in.  Probably it was foolish of me to go fo nuclear physics over solid state, but I had largely found the teaching of Solid State physics uninspiring as an undergraduate and had not been motivated to learn very much of it, and felt ill-prepared for further study.  Well, I bought the textbook to have as a reference and perhaps I thought I'd even study it and learn from it, an indication that I was not as self-aware then as I am now.  Or at least I saw a practically endless life with copious spare time stretching in front of me in a way I don't now.

Picking up the book now, I started by reading from the beginning with the Drude Theory of Metals - a picture in which mobile electrons form a gas following the laws of kinetic theory.  The theory dates back to only just after the discovery of the electron, but before the structure of atoms was understood, and before the laws of quantum mechanics, so vital for atomic and solid state structure so generally, were known.  As a model it does a reasonable job (order of magnitude or better) of giving free electron densities and resistivities of metals; it can describe the Hall effect, and thermal conductivity.  The Drude model was something I had studied once upon a time, but I would have been hard pressed to say anything about it now, before re-learning from Ashcroft and Mermin.  

I carried on skimming through the following chapters to get an idea of the broad brush of development of ideas, but then decided that I wanted to learn at least something that might be a bit more useful to me, so I jumped way ahead to near the end of the book, to the chapter on Electron Interactions and Magnetic Structure.  It contains introductions to the kinds of spin Hamiltonians familar as standard models to me as a quantum many-body physicist: the Heisenberg model and the Hubbard model.  I realise I had a very facile view of the development of these models, supposing that they started from the assumptions that you could imagine lattices in atoms with magnetic moments were fixed in place and you supposed a very simple interaction between the atoms based on the relative orientation of the neighbouring spins.  In reality, there is much more to it, and this is brought out nicely in the book.  For a start, though they are models of magnetism, the authors emphasise the electrostatic origin of the magnetic effects.  Mainly because of the required antisymmetry of the overall wave function, the spin orientation of atoms in a lattice can be determined, with the spin having to match (or "anti-match", I suppose) with the spatial part of the wave function, which itself is determined mainly by electrostatic effects.  Actual magnetic interactions between atoms are a smaller effect when it comes to how the atoms line up to give macroscopic magnetism.  Interesting!  

Of course, I would have liked to have gone further, and worked through some examples to do actual calculations, and maybe worked through a problem or two at the end of the chapters.   I am already a week late writing this up here, though, and a week late starting the October book, so alas I will leave A&M behind for now.  On the other hand, I have to submit some ideas for BSc final year projects for Physics students at Surrey, so maybe I'll set one on the Heisenberg model, and vicariously live my continuing interest in this stuff through my student. 

To my regret, this exercise resulted in a nasty splodge on the fore-edge of the book when I left it in my bag with a too-ripe banana.  Still, perhaps that's better than having the book look pristine through being barely touched since its purchase nearly 30 years ago

Commenting on research

 I recently submited my first comment on another research paper.  The paper I commented on is "Full quantum eigensolvers based on variance" by Li et al., Phys. Scr. 99, 095207 (2024).  It caught my eye because I am interested in variance-minimization techniques in quantum computers, and have used them myself to solve some problems.  

The paper of Li used as one example the case of the deuteron nucleus as given in a highly-cited paper by Dumitrescu et al., but unfortunately they made several mistakes when applying it, and I wanted to make a comment to help correct the record. 

In brief, though the Dumitrescu work deals with a deuteron nucleus and calculates the binding of a proton an neutron, Li et al. describe it as a molecular system giving results in units incorrect by orders of magnitude.  The Dumitrescu Hamiltonian is a bit unusual compared with the majority of many-body quantum formalism in that it is a one-body model for a two-body system, so the deuteron is treated as a single particle, in which the number of occupied levels in an oscillator basis translates directly to the number of deuterons.  Mathematically, the model can give you back a "zero deutron" solution in which nothing is present.  The energy associated with that is zero, and the result is "trivial" in that there is no actual calculation to be done to get it.  Li et al. appeared not to understand any of this, and presented results as if they were all deuteron results, including the result with no deuterons present.  Thanks to some rounding, they also had the no-particle solution at a non-zero energy.  They showed how remarkably quickly their algorithm found this and other trivial solutions, not realising that these "solutions" could not test their algorithm at all.

This was one example among a few in their paper, but it seemed like enough for a comment.  Not to say that the whole paper was wrong, but to flag up some things that should not be propagating through the open literature.  

So, I wrote a brief comment paper and sent it to Physica Scripta.  I got a rejection from them, and as per IoP journal policy, there is no right to query a rejection.  If there was, I would have argued back that the referee actually agreed that misidentifying units and nuclear nature were problems in the paper (possibly a "clerical error" and that it didn't matter because someone else had made the same mistake before them).  The referee appeared not to understand probably the most important point, or just did not address it in the referee report, that the nature of the model and its trivial solutions was not understood by Li et al.  They concluded that in any case, mistakes in one example did not justify the publication of a comment.  Before submitting the comment, I checked the Physica Scripta guidance about comments to check that indeed only a single problem sufficed to justify a comment and not a slew of problems. 

Well ... I could try to find the email address of the editorial board, since the notification email I got with the judgement is from a junk address at the editorial management system, and present my case, but I feel like writing the comment paper has been shouting into the void enough, and so instead I'm writing this blog post where at least it is on the record.

edit:  Let me add, too, that I couldn't put the comment paper on the arXiv because they do not allow such things (comments on papers that are not themselves in the arXiv).  It would be nice to find somewhere to post the paper.

Working through books

To me, when learning things, I still consider books an important go-to resource.  When I was at school, I would use my pocket money for some typical child things – copies of the Beano, 7" singles, sweets, but I also, especially when a bit older, but still very much a child, bought books specifically to teach me things.  At early teenage, that was mainly computing, mathematics, astronomy and electronics, though somtimes I managed to pick up some books on what would become my main academic interest of physics.

As I became a physics student, as an undergraduate, I continued to get my own copies of books when I could afford to and/or found intereting things in second hand shops.  As time has gone on, I have carried on getting hold of books through second hand shops or websites, buying them new, getting given them by retiring colleagues, and from closing-down sections of University libraries who gave staff first refusal before dumping them.  

As of today, there are somewhere between 200 and 300 books that I can reach for when I am sitting at my desk working, and I realise that some of them I may never feel the need to pick up and open ever again.  That's not because there's nothing in the books of use or interest to me, but rather that unless I make there effort, then one day that I don't pick up a given book, followed by another, can lead to all my remaining days without making use of them.  Of course, it doesn't really matter, and I needn't let the rest of my life be dictated by what books I happen to have to hand right now, but ... I have a plan.

If I choose one book per month then I should be able to cover the collection, more or less, by the time I retire, depending when I do that, and what "retirement" means for projects like working through these books.  By "working through" I mean that I will devote as much time as I can manage in each month to reading the book, and seeing what value I can get out of it.  That might be anywhere from reminding myself of something I used to know as an undergraduate, or maybe half-learned but didn't understand once, to triggering a research project leading to an original result and a publication, to an interesting anecdote, to running a final year BSc project on the topic.

I slightly fear for my ability to strike the right balance of finding enough time to get something useful from each book without it taking up time for other things, but I'm hoping that there will be net benefit of serendipitous finds and general intellectual enrichment that will make it worthwhile.  If not, why do I even have all these books?

So, it's 1st September today, so I should pick a book for September 2024.  This is going to be a hard part of the project.  I will do that quickly, and edit this post with the result,  If you can see from the enlarged version of tha attached image anything that you want me to pick, please comment and I may well start with that.

edit: So I've had a request on X to start with Ashcroft and Mermin's Solid State Physics, and so it begins

I'd be interested in your live reading of Solid State Physics.

— Panagiota Papakonstantinou (@PPapakonNucl) September 1, 2024

Solving Diophantine Equations with Grover's Algorithm

Today on the arXiv a paper appeared, written by Lara Tatli and me.  The paper is on solving Diophantine equations on a quantum computer using Grover's algorithm.  

The project started last summer when Lara (an undergraduate physics student at Durham) got in touch to ask if she could do a summer project with me.  I had an idea to use a quantum search algorithm to find roots of equations in a more efficient way than a classical algorithm might, and I suggested to her we could start looking at that.  My initial idea was very vague but I thought perhaps we could encode floating point numbers in an interesting way search for values of x which solve f(x)=0 for some hopefully interesting functions.  This "root finding" is a common basic tool of numerical analysis and many problems can be formualted this way.

When looking at how to encode the numbers on a quantum computer, it became clear that starting from the simplest case - where the numbers are just straight binary representations of integers - would be the easiest place to start, but still interesting enough.  Equations where the numbers can only take on integer values are called Diophantine equations after Diophantus of Alexandria who studied them in the 3rd century.  The standard definition of Diophantine equations has them acting in at least two variables, and a simple example is finding all the Pythagorean Triples - the set of right-angled triangles with integer sides.  The basic example there is {3,4,5} since these integers satisfy Pythagoras' theorem 3²+4²=5².  There are an infinite number of solutions of the equation x²+y²=z² where x,y,z are all positive integers.  Fermat's Last theorem famously states that there are no solutions of xⁿ+yⁿ=zⁿ where x, y, and z are positive integers and n is an integer greater than 2.  

Anyway - our ambition is, at this stage, at the level of a simpler Diophantine equation, and we just looked at x+y=5, arbitrarily chosen.  Here, there are lots of solutions if you allow x and y to be negative integers, while if you restrict to x,y>=0 then there are solutions (x,y)=(0,5), (1,4), (2,3), (3,2), (4,1), (5,0).  This is what we were hoping to find.  

Grover's algorithm works by constructing a quantum phase oracle that can take a linear superposition of encodings of all possible (x,y) pairs within some range of values of x and y (we encoded each with 3 bits, so from 0 to 7) and change the phase of the quantum amplitude for each component of the linear superposition that represents a valid solution.  Then a neat trick uses quantum interference to amplify those states which had been marked out, while reducing the amplitude of the others.  In general several cycles of this marking and amplification can be needed to pick out the answers, but - crucially - fewer cycles than a non-quantum search.  It's a very standard quantum algorithm, first worked out by Grover in the 90s.  Applying it to simple Diophantine equations like we have done doesn't seem to be something that people have done before, though I dare say now our paper is up on arXiv, someone will come along and point out that it has been implemented already.  It's a pretty simple thing, but has the potential to be worked up in to a more powerful solver of more interesting equations.

Here's the final plot from the paper where we show the quantum state of the quantum comptuer after two iterations of Grover's algorithm, where we see that there are four quantum states picked out which we have labelled with the encoding of the x and y values.  If you split the 6-bit binary strings into two 3-bit strings for the values of x and y, you'll see they add up to 5.

What Englishman?

In older scientific journals,  you get the situation where one paper would end half way down a page and the next article would start on the same page.  So when, in this modern age, we download a pdf of a paper, we sometimes get the start of another paper, and sometimes they can be interesting things, if only because they are very much of their time and not something that we would deliberately download to read for its enduring relevance. 

I was prompted, by a talk at the CNR*24 conference that I went to last week, to look at a paper by Eugene Wigner entitled "Nuclear Reactions and Level Widths", Am. J. Phys. 17, 99 (1949).  The journal it's in - the American Journal of Physics - is a long-running educational journal with articles aimed at those interested in teaching physics, generally at the undergraduate level.  I am yet to read through the paper, but I did see on the last page an extra thing which is a poem reproduced from the British satirital magazine Punch.  I reproduce an excerpt as (I hope) fair usage, since I think the poem is still in copyright.  It's about some characters in electromagnetism and begins:

and then in verse 4 we have

where the "Englishman" referred to is James Watt (scientist, not the BrewDog guy).  I'm sure Scots everywhere will snort Irn Bru out their noses at this claim of Watt's nationality. 

I do remember Punch from the final years of its existence.  It carried on until 1992 (and was revived briefly later).  I don't think I ever read it much outside doctors' waiting rooms but I did struggle to see what ever was funny about it.  Perhaps I was too young to appreciate it, but perhaps also it was a rather old and conservative kind of humour.  Anyway, the poem, lighthearted in style as it is written, has an unwelcome nationalism to it, as well as that affectation that still continues to this day – that it's just fine to be a kind of intellectual and at the same time to admit in a happy way that you don't understand science.

Oh Vienna

 I'm making my first trip to the International Atomic Energy Agency (IAEA), my first trip to Vienna, and my first trip to Austria.  I'm attending the CNR'24 (Compound Nuclear Reaction) conference on the IAEA premises which is part of the UN buildings in Vienna.  It's a pretty amazing and iconic venue, though having to go through airport-type security to get in is a slight pain.  

The compound nucleus is the name given to the state of a reacting nucleus that occurs typically after the capture of a neutron or a heavier ion to form a highly excited state which is relatively long-lived and which quickly redistributes the nucleons from the impinging system in such a way that details of the initial reaction are 'forgotten' by the system.  The picture is sometimes given of marbles sitting in shallow bowl, or depression, with another marble coming in from outside with enough energy to pass through the depression, except that it knocks into the marbles already in there, shares its kinetic energy with them so that it gets captured and no individual marble has enough energy to leave.  In principle there is enough energy there so that after enough collisions one of the marbles can be kicked out, and eventually, in a frictionless ideal situation, such an even will happen.  In real compound nuclei sometimes this does really happen, and very narrow neutron resonances can be found which correspond to very long-lived states.  

The term "compound nucleus" was coined by Niels Bohr in the early days of nuclear physics when trying to understand some of the first-observed phenomena in nuclei and its impressive that the ideas were sufficiently correct that they have survived today.  Some of the calculations I am interested in, such as those creating giant resonances, causing fission, or during fusion to make superheavy elements, have this compound nuclear state as an intermediate nucleus.  I've never really thought about the properties of this compound nucleus in detail, but having talked to one of the conference co-organisers earlier in the year, I realised that I would find the conference pretty interesting, and so it has been.

I've been to many conferences over the years, and one of the things I've seen is the people who enjoy meeting up with colleagues who they have seen throughout their careers at different occasions and throguh such meetings form friendships which endure over the years.  I've somewhat felt that that's part of the conference experience that I've missed out on, partly through a natural diffidence that has perhaps affected my ability to form friendships outside of my professional life as much as in it, but here I have indeed bumped into a few people who I have really been able to catch up with and talk about the last time we have seen each other, mixing up asking about latest work results alongside how they are doing and how life has changed since seeing each other last.  It's a nice part of the conference experience.

Here's my obligatory blogpost picture - me standing in the plaza area of the UN complex

 

Proceedings from COMEX

 Last year, I attended COMEX7 in Catania, Italy.  This week, I spied a big brown envelope for me in the post room at work, and saw that it was from Italy, and couldn't quite figure out what might be inside.  At first I wondered if it was a hard copy of the new NuPECC Long Range Plan document.  But, no, it was a hard copy of the COMEX7 proceedings, published in a special issue of Nuovo Cimento C. 

Nuovo Cimento is a famous journal from Italy, set up by the Italian Physical Society, in which many interesting articles have appeared over the years - particularly on theoretical physics, and particularly from some of the famous Italian names, such as Fermi and Majorana.  As happens with many journals the original Nuovo Cimento split into different series with different specialities, and eventually almost all of them merged with other European national journals to form the European Physical Journal series.  But a few rump Nuovo Cimento journals live on.  Nuovo Cimento C survives to publish proceedings of conference and workshops held (mainly? solely?) in Italy.  And so, I have a hard copy of a special edition of this famous and historic journal, which includes my first, and perhaps only, Nuovo Cimento paper

The front cover

My paper!

 

2023 Journal Impact Factors

I see that the 2023 Journal Impact Factors (JIFs) have been announced.  While I take them with a pinch of salt, as I am able to judge quality of articles by actually reading them, JIFs are an interesting artifact of the research environment, not least because so many people seem to take them seriously.

In the "PHYSICS, NUCLEAR" category, there are 20 journals, with the top two predictably being review-only journals.  For the regular journals, where you can openly submit papers, there are not too many surprises:  The journals which combine particle and nuclear phsyics, but which are nevertheless included in the "PHYSICS, NUCLEAR" category, do better than nuclear-physics-only journals.  So Physics Letters B, Chinese Physics C and J Phys G outrank Phys Rev C, European Physical Journal A and Nuclear Physics A.    

The one unexpected result for me is the high score of Nuclear Science and Techniques.  The journal combines nuclear physics of the sort I do, with "nuclear science" - meaning things to do with applications of nuclear physics, such as nuclear reactors, or radiation physics.  Such areas do not usually bring JIFs up as applied physics tends not to be highly cited.  The journal has been somewhat under my radar.  I don't make a habit of looking there for new papers, though I see there are some interesting nuclear physics papers there, alongside nuclear science articles a bit far from my main interests.  It's a China-based journal, though published by Springer, and the authorship is heavily China-based.  

One may speculate why it is doing so well in impact factor. The JIF number has jumped out quite a bit this year to put it in the top quartile by category.  I don't know the answer as to why.  It may simply be the fact that the journal is heavily used in China and the volume of reesarch coming out from China, whose authors are aware of and citing other work from China, is ever-increasing.  Let me know what you think!

Since I like to include a picture for each post, I scanned a list of open access papers in the journal and found the one closest to my own interests - The 5𝛼 Condensate State in Ne-20 by non-Chinese author Takahiro Kawabata.  It shows a schematic picture of an alpha-cluster state in neon-20 compared to the non-clustered ground state.

Hackathon wrap-up

As mentioned in a previous post, we (me, postdoc Abhishek, and student Grant) were in Edinburgh attending a hackathon run by DiRAC, the computing arm of the UK STFC funding agency, and Codeplay, an Edinburgh-based company with expertise particularly in the Intel architecture of hardware and software.

At the start, we had our code (Sky3d) which runs on CPU and makes extensive use of a CPU-based fast Fourier transform library (fftw).  By the end, we had, with extensive help from the DiRAC and Codeplay engineers, a code which was mainly hosted on the CPU but which offloaded parts of its operation to a GPU coprocessor.  In particular, we were able to interface to a custom set of fft routines which are part of the Intel MKL library and which we were able to use fftw wrappers for.  This was all pretty exciting - we are using the latest hardware, with very new compiler technology, to run our code.  The hope is that it should end up running so much faster that we will be able to attack physics questions that are just too hard / time consuming to answer right now. The down side is that so far, the GPUified code actually runs slower than the CPU-only code.  This is presumably because it is spending time shunting too much data between the CPU memory and the GPU memory and not enough time powering through calculations on the GPU.  So we still have a lot of work to do to get a fully optimised GPU version of Sky3d, but at least we have started now.

At the end of the three day event, Grant and I went to a chip shop.  Grant tried the local delicacy of a deep-fried battered Mars bar.  He liked it.  I didn't fancy one but have tried one before and think they're pretty good! 

Grant with a deep-fried battered Mars bar

Developing quantum computing algorithms for the nuclear shell model

Today our new paper appeared (as an "in press" draft) in the New Journal of Physics.  In it, we develop quantum computing circuits that can produce eigenstates in the nuclear shell mode.  This nuclear model, called "configuration interaction" in other areas of many-body quantum mechanics, such as quantum chemsitry, is probably the main approach that realistic calculations of nuclei have been attempted on quantum computers by various groups.

Our paper is by no means the first to explore how to apply quantum computing to the shell model.  What we have done, though, is to use a circuit ansatz inspired by the nuclear physics and the symmetries involved to use a small number of gates, and a small number of variational parameters in order to turn the initial "zero" state of the quantum computer register into a state which simulates the nuclear wave function. 

The result is that we are able to find, with relatively low-depth circuits, the ground state, lowest 2+ and 4+ states, on a simulated quantum computer with good accuracy.  

We had some useful comments from the referees pointing us to how we might be able to reduce the circuit depth further, and we will look into that.  We also would like to really test the circuits on a real quantum computer.

Here's an example circuit - probably our most complicated one - that finds the 2+ state of Nickel-58

Hackathon in Edinburgh

 I had an early start today (alarm set for 4:10 am) for a three-day trip to Edinburgh, where I'm attending a hackathon with my colleagues Abhishek and Grant.  The idea is that there will be some experts here in the latest coding technologies for running codes on the latest GPU hardware, and they will help us transfer our CPU-based code to GPU where it should be able to run much faster, enabling us to tackle physics cases that are currently too hard for us. 

So far, it has been going okay - some steps forward and some technical issues holding us back, but we're only half way through the first day of three.

Edinburgh is a pretty city and if I had taken a photos I could include them here.  I haven't (yet), so instead, here is the tweet from the DiRAC_HPC Twitter account, which features our team in the foreground table.  You can see Grant and Abhishek and a tiny bit of me at the right of the picture

Kicking off our 3-day oneAPI Hackathon in Edinburgh, in collaboration with @IntelDevTools and @codeplaysoft!

Looking forward to an exciting event featuring diverse teams with interests ranging from medical imaging to evolutionary studies. pic.twitter.com/vvB9mZyS1O

— DiRAC (@DiRAC_HPC) June 11, 2024

Open Access in Nuclear Physics

 Thanks to the trawling majesty of Google Scholar, I came across a paper published in the Ukrainian journal Nuclear Physics and Atomic Energy which cites a paper of mine.  The article itself presents some nice calculations of giant resonances in tin nuclei.  Though I have been aware of this somewhat obscure journal before, I hadn't quite realised that it is free to publish in and open access.  It is listed in the Directory of Open Access Journals, pointing out that not only is it free to publish in, but authors retain full rights, and the papers are published as CC BY-NC license.  So, all in all, it ticks all the boxes.  I must say, I also like its basic html feel and the idea of supporting a journal published by the Ukrainian nuclear physics community is also appealing.  

The only weird thing about it is that submissions must come with a cover letter signed by your Head of Department. Oh, and the papers must be written in Microsoft Word, which is also a bit of a weird requirement.

Th-229 isomer breakthrough

 A group in Germany has just published a paper showing a huge improvement in accuracy in measuring the energy and lifetime of the lowest-lying nuclear excited state that we know about - the 8.4 eV isomeric in Th-229.  While typical nuclear excitation energies are around one million electron-volts (1 MeV),  the relatively tiny energy of the thorium isomer puts it in the kind of energy range that can be manipulated by optical equipment.  In the case of the published work, the authors developed a bespoke ultraviolet laser that was able to sweep the right candidate frequencies to pin down the isomer energy to an accuracy of nearly 1000 times better then the previously best measurement.  

This isomer is not just a quirky curiosity:  A long-lived low-energy state in a nucleus, which is much better isolated from environmental effects than an electron in an atom or molecule, has the possibility of being used in applications such as a nuclear clock, potentially surpassing atomic clock timekeeping, as well as other possible quantum technology applications such as qubits for a quantum computer, or a quantum sensor to test fundamental physics. 

Plot from the (Creative Commons open access) paper below showing the resonant peak in the frequency scan:

16 year erratum

 There is an erratum published in Physical Review C this week which corrects paper from 16 years ago.  In their opening sentence they own up to adjusting the data in a way they shouldn't have:

In our original publication of level scheme of $104\mathrm{Nb}$, we determined level energies based on certain transitions and subsequently adjusted the raw data for other transitions to fit these energies. This is not correct scientific procedure as it alters original data, and it risks introducing incorrect transition and level energies into the literature. The main purpose of this erratum is to provide the original data.

and go on at the end to 

thank the Physical Review C editors and the data scientists at the National Nuclear Data Center at BNL for calling our attention to these corrections

To me, this shows that processes are working and that the data from their paper, which made its way into databases, was found to be erroneous, the error investigated, and corrected.  Too bad it happened in the first place, but the data remained available for scrutiny and the scrutiny worked.

 

IoP conference at Liverpool

 It's my first day back at work since being at the IoP HEPP/AP/NP (that's High Energy & Particle Physics / Astroparticle Physics / Nuclear Physics) combined conference.  I was there, talking in the plenary session about quantum computing for nuclear structure, and a lot of Surrey postdocs and students also gave talks and posters.  

Here is a selection of photos from the conference:

My student Sam Sullivan presenting his poster

My student Grant Close presenting his poster

Me giving my talk

My postdoc Bharti giving her talk

My student Isaac giving his talk

The sky looked pretty as I walked to the conference dinner

Conference dinner!

As well as these photos, I had to take one video, as my postdoc Abhishek is a master of making animations, and so a static photo would not have done is presentation justice:

New isotopes project website

For some years Michael Thoennessen at Michigan State University has developed and curated a database of isotope discovery - i.e. when, where, how and by whom was each isotope of each element discovered.   He has just emailed out about a revamp of the website with new design and new features. The site is here. 

 One of the new features (at least, I think this is new) is that you can search discoveries on various fields.  I tried searching for my name ("P. D. Stevenson") and lo and behold you can find the four isotopes that I "helped" discover.  By helped, I mean I was coauthor on the discovery paper, as I contributed to the theoretical analysis.  I didn't set foot in the lab where the experiment actually took place.

Here is the copy-and-paste of the results table:

Search results:found 4 isotopes

In the table below click on an isotope symbol for more information about its discovery. When quoting the abstracts please cite the abstract as: “FRIB Nuclear Data Group, Discovery of Nuclides Project, https://doi.org/10.11578/frib/2279152”.
Newly discovered isotopes will be included after the references are entered in the NSR database.

Isotope	First Author	Lab	Country	Year	Reference
155Ta	R. D. Page	Jyväskylä	Finland	2007	2007PA27
157W	L. Bianco	Jyväskylä	Finland	2010	2010BI03
159Re	D. T. Joss	Jyväskylä	Finland	2006	2006JO10
161Os	L. Bianco	Jyväskylä	Finland	2010	2010BI03

 

Bye bye 12BB03

 Last week I was on a work trip to the USA and on my first day there I got an email from my employer telling me that I have to move offices and I should come and get the key of my newly assigned office.  It came a bit out of the blue and now that I'm back I find some of my colleagues have already moved and I have started the process of clearing out my office.  I'm using the opportunity to get rid of some of the stuff I have accumulated over the 20 years or so I have been in here.  It's a long time in anyone's life, and longer really than almost any other constant in my life - from children to partners to where I live, I'm in a different situation than I was 20 years ago.  In some sense I'm saying goodbye to the longest-lived part of my life that I saw on a near-daily basis.  On the other hand, it's only a room, and my employers can reasonably ask me to move to another room. 

Here are some of the things I have come across and thrown away:

My stash of used train tickets that I kept for no good reason.
Many memories (good and bad) evoked from looking at the journeys.

Once upon a time I used paper diaries from the Institute of Physics
to plan my (work)life.  Here is the week in 2003 where there was going to
be a retirement dinner for Prof Ron Johnson.  I suppose it was moved(?) so
I crossed it out.

I have a bunch of Open University material donated
to me by someone I used to tutor.  After he got his degree
he didn't want to keep the material and I have kept it all in a box
ever since.

RIP Charlotte Froese Fischer 1929–2024

 If Wikipedia is to be believed, then Charlotte Froese Fischer has died, aged 94.  I say "if it is to be believed" because I haven't seen any independent story about it, and the wikipedia author has no profile.  Still, it would be an odd thing to do, to update her page just to change some instances of "is" to "was" and include a year of death.

Like so many of this nearly-gone generation, Froese left eastern Europe due to political upheaval.  Born in what is now Ukraine, in the Donetsk region, her family left the Soviet Union on the last train allowed to depart for Germany in 1929 from where, rather fortunately given what was to come, they were soon granted a visa to go and settle in Canada.  Her scientific career started with her studies at the University of British Columbia where she was interested in mathematics and chemsitry.  She got interested in very early computers and got a PhD position with Douglas Hartree in Cambridge.  As computers got more advanced and portable programming languages, such as Fortran, appeared, she became a leader in computational chemistry, making a famous prediction, which was experimentally confirmed, that calcium can exist as a negative ion.  Normally calcium forms a positive ion by losing one or two electrons, since the outermost two electrons are rather weakly bound.  It turns out that subtleties of the interactions with an extra electron that gets added can lead to a surprisingly stable configuration.  

I don't think I ever met her, but I remember her being mentioned as a kind of guru when I worked at Oak Ridge National Lab in Tennessee in the late 90s and she was at nearby (on an American scale) Vanderbilt University.  I was working with a group who were also very computationally-minded and I think there was some overlap or discussions with her that I was never part of. 

She wrote a nice autobiographical article in the journal Molecular Physics, published in 2000, which can be found online on her personal website at Vanderbilt.

The history of exchange forces

 I almost missed this paper submitted to to the history and philosophy section of arXiv last week, but picked it up when reviewing recent cross-post submissions to the nuclear theory section.  It is called "The development of the concept of exchange forces in the 1930s: close encounters between Europe and Japan and the birth of nuclear theory"

Aside from my general interest in history and the history of physics in particular, the last two words of the title definitely put it on-topic for my interests.  Hopefully I will get round to reading it, but thought it might be of enough interest to post here even before (if) I do read it.

RIP Gottfried Münzenberg 1940–2024

 I copy and past below a press release from the FAIR facility at GSI, Darmstadt, Germany:

Press Release, 22 January 2024

Mourning for Gottfried Münzenberg 
 
GSI and FAIR mourn the loss of an outstanding scientist and pioneer of nuclear physics who shaped nuclear physics research at GSI Helmholtzzentrum für Schwerionenforschung for decades. The former GSI division head Professor Dr. Gottfried Münzenberg passed away on January 2, 2024 at the age of 83.
 
Gottfried Münzenberg had a major influence on various areas of modern nuclear physics and leaves behind a significant scientific legacy. His diversified research work ranged from the study of exotic, very light nuclei to super-heavy nuclei, touching on both fundamental physical questions and practical applications. He laid important foundations for the extension of the GSI facilities, shaped the scientific program at the Super-FRS, contributed to the design of the new apparatus and initiated the founding of the NUSTAR collaboration at FAIR.
 
During his time at GSI, he made decisive contributions to the discovery of superheavy elements and played a leading role in the design and construction of the SHIP velocity filter at Justus Liebig University in Giessen. He was head of the SHIP experiment group for the synthesis of the new chemical elements bohrium, hassium and meitnerium and, as a member of the discovery team, was closely involved in the synthesis of the elements darmstadtium, roentgenium and copernicium. Münzenberg was also co-discoverer of the double magic nuclei tin-100 and nickel-78 as well as the proton halo in boron-8. Furthermore, his scientific commitment led to the discovery of over 220 new isotopes and more than 350 new mass measurements of various isotopes.
 
Gottfried Münzenberg gained worldwide international reputation as Professor of Experimental Physics at Johannes Gutenberg University Mainz and head of the Nuclear Structure and Nuclear Chemistry departments at GSI. He initiated and fostered numerous international collaborations and was passionately committed to the promotion of young scientists.
 
For his outstanding scientific achievements, Gottfried Münzenberg has received many high-ranking awards and honors, including the Röntgen Prize of the Justus Liebig University in Giessen, the Physics Prize of the German Physical Society, the Otto Hahn Prize of the City of Frankfurt, the Gold Medal of the Comenius University in Bratislava, the SUNAMCO Medal of the IUPAP, the Lise Meitner Prize of the European Physical Society and the Medal of Honor of the Hellenic Nuclear Physics Society.
 
GSI and FAIR will always remember Gottfried Münzenberg as an outstanding scientist, a valued source of inspiration, and above all as a great person full of warmth and with an incomparable sense of witty humor. His colleagues and friends will keep his wisdom, kindness and friendship in lasting memory. The management of GSI/FAIR extends its deepest condolences to his family.    

This press release with pictures is available on our website:

https://www.gsi.de/en/start/news/details/2024/01/22/trauer-um-gottfried-muenzenberg

@ The Nuclear Physics Community Meeting

 I'm on my way home from the UK Nuclear Physics Community meeting, which takes place every January and gives members of the academic nuclear physics community a chance to get together, update each other on research and community management matters, and to catch up with each other generally.  I've been part of the community since 2000 so I've got to know many of the people well and it was nice to see them.  Getting up to speed with latest new from STFC, from funding panels, and from research projects. If nothing else, I was prompted to send an email to offer collaboration on the calculation of octupole states, following having developed the ability to make the calculations, and then working with experimentalists at Surrey (see here). 

In the evening last night there was a pub reception and meal at a fancy restaurant, but I felt like I had done the socialising I wanted to, and joined my London quiz team for a match.  It was against the league leaders, and though I'm happy with how we did, we didn't manage to beat them.

Meanwhile, it's exam season at University so I've spent part of the last couple of days dealing with questions about Special Relativity for what will be my last time teaching it in its present form, thanks to some rearrangement of modules starting next year. 

Here are some photos from the last couple of days in London

My hotel with St Pancras Station's hotel

On the way to the quiz, the new developments around
King's Cross station