Getting to know MAX IV

Today, Sciinno visits the MAX IV synchrotron radiation research facility in Lund.

Think of MAX IV as a 500 million Euro gigantic microscope that can look deeply into the world of atoms and molecules - a microscope that is the size of the Colosseum in Rome (528 meters in circumference, 168 meters in diameter, or covering approximately 3 full-size football pitches1)

Watch introductory video about MAX IV from their webpage (click link) Article in “videnskab.dk” (in danish)

Whereas normal microscopes are smaller and cheaper, even the best ones can only resolve (distinguish details) structures of about 1 micrometer, the size of some bacteria. And bacteria are roughly 10.000 times larger than atoms.

It is a fundamental law of physics that microscopes cannot see things that are smaller than the wavelength of the light they use. So to see atoms, scientist have to use light with a smaller wavelength (than visible light), e.g. X-rays - and this is exactly what MAX IV is designed to create. From this perspective, MAX IV is just a massive flashlight for X-rays.

But MAX IV can do more than just that. The X-rays are very intense(bright) and can be directed and focused to the sample that needs to be studied. Furthermore, the X-rays can come in flashes lasting down to only 100 femto-seconds (split a second into one million billions, then it’s a hundred of those), which is the time it takes for single atomic and molecular reactions to take place.

You might say that with this tool scientists can record movies of molecules as the react with other molecules.

Yearly, the Max-IV has about 2000 international researches using this incredible machine to:

1. study the mechanisms (chemistry) that happens when producing hydrogen for cars. The goal is to improve the fuel by understanding

the mechanism at a fundamental level, enabling this kind of renewable transportation (hydrogen cars). Further reading (click).

2. Improve materials used to assist the conversion of water and CO2

(normally a problem) into a renewable fuel. Further reading (click)

3. develop tools to study the dynamics of proteins at normal temperatures (room or body temperatures). Further reading (click)

4. Improve sensors used in medical imaging (PET scanning, which is a noninvasive scanning technique used primarily for cancer detection). Further reading (click)

1 The full facility is much larger.

Synchrotrons (although not MAX IV) may also be used for cancer treatment where the tumor is bombarded with the high speed particles from the synchrotron, usually protons are used. This novel method of treatment, known as particle therapy, is effective and less harmful to normal tissue. Denmark is currently building its first particle therapy center in Aarhus (although this is based on a slightly different source of particles). Further reading (click)

How are X-rays produced at MAX IV?

The production of X-rays takes place in a narrow ring-shaped steel tube, 528 meters in circumference. This is called a storage ring (see schematics below). In the tube, electrons circle at speeds extremely close to the speed of light, traveling around the storage ring approximately

500.000 times pr. second in a very controlled manner. A large number of big electro-magnets are used to steer the electrons around the storage ring without hitting the walls of the tube. Furthermore, the steel tube is almost completely empty, evacuated such that for every trillion molecules in normal air, only one is left inside the steel tube. This makes sure, that there are almost only electrons in there.

The X-ray radiation used in experiments are created by the electrons on their way around this circular electron racetrack when they pass through a special magnet, called a wiggler/undulator, that ...wiggles the electron path. This wiggling of electrons creates radiation (X-rays) in a similar way as the antenna in your cell phone (although the latter is not dangerous - intense X-rays are).

Schematic layout of the MAX IV synchrotron. The ring named “3 GeV ring” is 128 meters across.