Category Archives: projects


The upgrade of the Advanced Light Source (ALS-U), the project I’m working on, has received CD-2 approval from the US Department of Energy, meaning that we are gearing up towards final design and will soon start ordering tons of magnets and mirrors, and transform our beloved light source into a laser-like source of x-rays, to enable the next generation in batteries, solar cells, computers and medicines (among many other things:)

Advanced Light Source Upgrade Project Achieves Major Milestone

Here’s a few recent highlights from the research enabled by the little synchrotron that could:

Jennifer Doudna, chair of the Advanced Light Source Users’ Executive Committee (around 2001)

A last bit of research by my colleague Alex Frañó (and friend from the ALS Users’ Executive Committee) gets my neurons randomly firing up at night: Rethinking the fundamental way electrons interact in superconducting quantum materials. It progressively appear that skyrmions and superconductivity may be intimately related: A New Twist Reveals Superconductivity’s Secrets (Quanta magazine.) If this is true, we’re on the verge of a major shift: we could potentially engineer interfaces to create room temperature superconductivity. That would be a revolution: we could transfer power from a place to another with no loss (electrical line losses are about 50%) and we could democratize magnetic levitation for transportation.


I made it – I finally reached a dream, a promise I made to my mom at the dawn of my life, thirty years ago:

I have become a savant!

We’re going through difficult times, but this news obviously bring some light into this darkness.

Education in synchrotron

A new year is always a good time to try something new, and because we’re all stuck home because of the pandemic, it’s also a good occasion to learn more about some topics in science. I’ve consolidated here some resources that I have enjoyed over the years, or that are not easily accessible (the information about x-rays tend to be scattered, which is something x-ray do very well)

To get started, I recommend going through the free course by Philip Wilmott from PSI on EdX: Synchrotrons and X-Ray Free Electron Lasers. It is pretty comprehensive and covers a lot of the basis of x-ray science; it’s basically a boiled down version of the companion book “An Introduction to Synchrotron Radiation: Techniques and Applications” he wrote in 2011. This would take probably a week full-time, but you can probably stretch them over a few month if you’re not into binge watch (but it is probably as captivating as the Queen’s Gambit.)

The blue glow of the synchrotron radiation (AW 2020)

To mention also: if you’re a grad student working with synchrotrons, I would recommend applying for the three-week National School on Neutron and X-ray Scattering, generally at Argonne National Lab in the summer, but online this time around. I’m not sure if they will increase their cap of 60 participants.

Light source 101

For the ALS User Meeting this year (held remotely), Fanny Rodolakis and Monika Blum organized a new edition of the Light Source 101 workshop, where beamline scientists from the Advanced Light Source explain their science. Luckily, these talks where recorded (they are available as bulk here), and I have edited them in sizeable, 30-min chunks about most of the cool techniques we offer.

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Some thoughts about gender gaps in STEM

Liminary note: I am not a social scientist, but I try to educate myself about some issues facing academia, and this is the result of my inquiries. If you think some elements are incorrect or if you have good resources to share, please let me know!

In this short Life
that only merely lasts an hour
How much – how
little – is
within our

Emily Dickinson

Gender gaps in academia are pretty dire, and while it seems to get acknowledged and addressed, it’s not clear whether the root causes – especially social norms – are fully understood and can be solved. The paper Understanding persistent gender gaps in STEM (Science 368, 6497; June 2020, pdf) offers interesting statistics and insights.

Gender gap in physical science majors

The problem does not seem to be a difference in achievement, but social factors rather.

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Scientific mentoring of interns – covid edition

(I owe this piece to a conversation with Laleh Coté – she’s doing an incredible job on STEM mentorship, and even in these difficult times, she documents her observations on how it impacts these efforts.)

I’m always happy to mentor students, for it gives you a change to light a candle, but also forces you to explain things in a legible way – and if you can’t perhaps you don’t really understand things yourself.

Berkeley Lab has a great program for interns, and it comes with some resources: WD&E Mentor Handbook (pdf)

Because of the pandemic, all the summer internships have morphed into virtual internship. While everyone is still trying to figure out how to make it work best, some initial best practices where collected here:  Virtual Remote Mentor Guide -DOE-SC-WDTS Programs- May 2020 (pdf)

Virtual summer internship

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It’s the units, stupid

Whenever I see scientific code without units I scream inside my heart.

Everytime you write simulations of physical phenomena (often using numpy or matlab), make sure to always have variables where the units are clear, e.g. :

lambda_m = 633e-9 #wavelentgh in meters
c_mps = 3e8 #speed of light in meters per seconds
freq_Hz = c_mps/lambda_m

Failure to keep good track of the units has led to disasters. Yet complete lack of clarity  happens more often than not – just look at the code of a random scientist on github to witness the extent of the damage.

The reason why I am adamant about this is because a lot of time is wasted trying to debug code where it there’s a silly unit mismatch, and because we are doing physics.

Math versus physics

Why is coding without units such a terrible practice? It all boils down to the fact that computing is mostly about math and logic, and therefore not geared towards physical quantities. There is beauty in mathematical abstraction, but sometimes it doesn’t mean anything.

Take a mathematical statement that should be true:


Now ask yourself: what does it mean? If I add one orange to one apple:

1 orange + 1 apple = ?

It might sound silly but it’s actually pretty deep. You cannot add quantities which are not congruent. Yes, you may say that by adding one fruit with another fruit you get two fruits, but you’re cheating then.

This is somehow why object-oriented programming was invented: with the notion of “classes”, you can add entities which are compatible, through the game of function overloading and other niceties. In an ideal world, physical quantities in simulations should all have their own class, where the units would be defined.

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Effective online presentations

Thomas Danthony

respect the flow

Nowadays, many conferences and workshops are going online because of the pandemic, and we all are ill-prepared for this kind of shift forced upon us. Delivering an online presentation is very different from delivering an in-person presentation, for a few reasons, and we need cognizant of the nuances.

While many talks are indeed disastrous (people lack proper training), going to a conference is often not only about the content of the talks (you could just read the papers), but about visual and vocal cues which are often absent from literature. These cues help you figure out what are the important points and make clear what what other people are interested in.

Therefore, it is important to establish and maintain contact with the audience. For this, there are many things we can learn from news anchor: they also talk to the camera, they have dedicated studios and they alternate between speaking and news content.

I attended an online workshop by Jean-Luc Doumont on delivering an online presentation, and I found it useful. Here are some of my takeaways.

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It’s getting pretty crammed at the bottom

Let us represent a dot by a small spot of one metal, the next dash by an adjacent spot of another metal, and so on. Suppose, to be conservative, that a bit of information is going to require a little cube of atoms 5 x 5 x 5 – that is 125 atoms. Perhaps we need a hundred and some odd atoms to make sure that the information is not lost through diffusion, or through some other process.
– Richard Feynman

Spoiler alert: we are nearly there!

* *

These very old line (1959) fro Feynman’s famous speech “There’s Plenty of Room at the Bottom” is still valid, though nowadays are getting very close to the bottom!

With my colleague Gautam Gunjala, we published an article in Berkeley Science Review on the ongoing contributions of UC Berkeley and Berkeley Lab to photolithography, the process of making microchips: Room to Shrink.

Photolithography is how you make tiny circuits

It was supposed to be part of the BSR Issue 38 (Spring 2020) but I guess it got covided.

Here are other pieces from yours truly on the topic:


The topic is getting red hot politically:
Lawmakers Propose Multibillion Dollar Semiconductor R&D Push  (American Institute of Physics, June 24, 2020)

if not down right nasty:
Trump administration pressed Dutch hard to cancel China chip-equipment sale: sources (Reuters, January 2, 2020)

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Broken Berkeley social scene

I haven’t had a drink in a bar for four months now, so I’m trying to remember where are all the places I used to go… All these great places that I miss dearly (if you’re looking for things to do in the meantime, check out you hikes in the East Bay and the Bay Area.)

Berkeley Art Museum / Pacific Film Archive during the Covid-19 pandemic


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