Norwegian researchers develop powerful radiation sensor

Oslo, Norway- Scientists at the Norwegian Micro and Nano Laboratory have created one of the most advanced radiation sensors in the world.

According to the researchers, the X-ray detector is able to reveal the composition of materials within a fraction of a second- a capability increasingly in demand in advanced manufacturing processes.

The type of sensor developed, known as a silicon drift diode (SDD), is the basic component of instruments used in everything from medical X-ray systems to monitoring experiments at CERN.

It is made of a double-sided microstructure that is fabricated on silicon wafers. Despite its tiny size – just 8 x 8 millimetres – it takes around eight weeks to produce and requires strict environmental controls.

A single grain of dust is capable of destroying the whole process by short-circuiting the equipment or damaging its nano-scale structures.

“This is why the advanced laboratory is equipped with vibration-reducing foundations and air-filtration systems that remove particles as small as 100 nanometres from the laboratory,” said research scientist Niaz Ahmed.

The sensor is produced by oxidising the silicon wafer in several stages, creating a physical structure on nanometre scale. Once this has been done, the scientists dope it with charged atoms at various levels.

The result is a light-sensitive diode which, when connected to electronics, can reveal changes in the physical structure of most materials.

“To put it simply, we can say that the sensor sorts the light into its individual energy levels by counting the photons and calculating their energy,” said Ahmed.

By distinguishing between different materials using differences in the absorption energy of their component elements, the chip can be used to identify potentially dangerous substances such as lead, cadmium and mercury.