Thursday, August 5, 2021

What are Synchrotrons For?

As is often the case, synchrotron radiation went from being an annoying by-product of circular accelerators to a highly specialized tool (and one in high demand at that).

Synchrotron radiation is often called synchrotron light, because it is made of photons. But not all these photons are in the visible range. In fact, synchrotron light goes from the microwave to the high energy x-rays, that is, way beyond what human eyes can see.

The Brightest Flashlight and the Largest Microscope

This broad energy range is only one reason why synchrotron light is such a useful tool. It also features a very high intensity and stability. It can point in a specific direction, like a flashlight. It possesses interesting polarization characteristics and can be pulsed into extremely short bursts (tens of ps). Oh, and it is the brightest artificial source of x-rays on the planet, too.

Now, this is not just very, very cool. This is also very, very useful. You may have read my analogy about colliders being like a gigantic microscope. Here, the light source is the beam-shaped synchrotron radiation. Detector sensitive to the right wavelength and fine-tuned to most characteristics of the beam constitute the “optics”. Clever people have put together algorithms that reconstruct the image from the beam, so you usually end up looking at the result on a computer screen.

In a similar way that you bring your eye to the eyepiece of your microscope at home (or at school) and look very close at the surface of your object, a synchrotron will allow you to look very close inside, or at the structure, of an object.

From Molecules to Masterpieces

This object can be a big, complicated molecule (like a protein, a virus or a ribosome), for which you’ll obtain a 3D image. We use synchrotrons to understand biological processes better, develop pharmaceutical drugs, or more efficient radiotherapy treatments. Since a synchrotron is so fast, it can also show us the processes such as structural changes in proteins while they happen.

The “object” can be novel material samples, the properties of which we want to exploit: amorphous or crystals, powder, thin films. We can look at the amount of stress in the materials, their reflectivity, their structure, their surface properties if they are magnetic…

Last but not least, one of my favourite applications relates to historical, archaeological and forensic studies. By nature, synchrotrons are non-destructive tools, which makes them perfect for studying prehistorical artefacts to understand how they were or where they came from, or artistic pieces (e.g. to authenticate them or study the techniques of the era).

What I really love about synchrotrons is how they enable a truly citizen science. Tools like synchrotrons are built with public funding, ie our taxes, but the results of studies conducted there really come back into our lives and improve how we live as a society.

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