The discovery of X-rays

It’s November 8th in 1895 and you’re standing still in a pitch-black room. Although you can’t see it, in front of you is a Crookes’s tube. Inside the Crookes’s tube, a small spark ignites from an induction coil which would normally give off light but today, the light is carefully shielded so that not a single ray escapes. In front of the shielded tube is a single cardboard sheet painted with barium platinocyanide. As the Crookes’s tube is switched on and the spark ignites, the painted cardboard starts to fluoresce.

This is the experiment performed by Wilhelm Röntgen that led him to win the first ever Nobel Prize for physics. He saw that a new type of radiation was escaping from the Crookes’s tube and he started to investigate. He quickly found that the radiation would pass through thick books and even wood which was astonishing at the time. He also saw that the radiation was blocked by even thin sheets metal like gold or copper. Then Röntgen performed one of the most iconic experiments in medical physics. He took his wife’s, hand and placed it on a photographic plate in front of the Crookes’s tube. The radiation passed easily through her tissue but was blocked by her bones and wedding ring. Röntgen’s wife, Anna Bertha Ludwig, had just had the world’s first X-ray.

Since 1895, X-rays have come a long way. If you’ve ever had an X-ray yourself, you’ll know that they are much higher resolution than Anna Bertha Ludwig’s hand. We also generate X-rays at synchrotrons, but they are much brighter than hospital X-rays because we produce them in a very specific way. Firstly we accelerate electrons to within a fraction of the speed of light before we send them through magnets. This causes them to lose some energy that is given of as X-rays. These X-rays are very bright because at a synchrotron, we can produce many more X-ray photons per second that in a medical X-ray machine. The X-rays are then channelled through tubes, mirrors and gratings to produce a very specific light that can be used to perform experiments.

The types of experiments done at a synchrotron vary from molecular biology to quantum physics. For example, using X-rays, we can determine the structure of proteins or make movies of enzymes catalysing chemical reactions. We can also look at materials and see how atoms are arranged, or even see the spin on electrons. These experiments help us to understand diseases to develop new treatments as well as developing new batteries and ways to store digital information.

For more information about the types of experiments being done at synchrotrons around the world, visit lightsources.org.

This work was done in collaboration with Diamond Light Source.