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Timepix3 was developed to detect elementary particles at the European Organization for Nuclear Research (CERN). It was then carried up to the International Space Station (ISS), where it measures the radiation dose to which astronauts and equipment are exposed. Most recently, Timepix3 has been used on the Zugspitze. Its task is to simultaneously detect the secondary cosmic rays and radon decay products. This radioactive noble gas occurs naturally in rocks and eventually reaches the surface. The German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) installed the Timepix3 at the Environmental Research Station Schneefernerhaus in cooperation with the universities of Augsburg and Prague.

The small semiconductor sensor, which measures just two square centimetres, is installed with an electronics box and a screen in a hut at an altitude of 2650 metres. The high-tech chip conducts measurements in real time. If, for example, round blue spots and narrow stripes appear on the screen, the researchers know immediately that alpha particles, electrons or muons from galactic cosmic rays have arrived. "This makes radiation that is invisible to the human eye 'visible'. The tracks they leave are characteristic of different types of particles," explains Frank Jansen from the DLR Institute of Space Systems in Bremen. Ultimately, it is even possible to determine the trajectory of the particles in Earth's atmosphere and in space.

The Czech Technical University in Prague (CTU) has provided the measurement equipment. In cooperation with the German Remote Sensing Center in Oberpfaffenhofen and the University of Augsburg, it is also being used to investigate the connection between atmospheric gravity waves in the altitude range of the mesopause region and the particle flux at Earth's surface. Gravity waves are fluctuations in air masses driven by gravity. They are excited in the lower layers of the atmosphere when air masses flow over mountains, for example. The mesopause is located at an altitude of 80 to 90 kilometres and is particularly sensitive to climate signals.

The device could be used for interplanetary missions

Scientists are also observing radon decay products. This natural radioactivity is always present, but its intensity varies from region to region. Radon also escapes from alpine rock. Over the coming years, a network of measurement stations is set to be created at a European level, and later globally. This will allow researchers to record the environmental impact on a large scale.

Timepix3 is a hybrid pixel detector originally designed to conduct measurements in accelerator facilities at CERN. "Now, however, we are also seeing extremely interesting results from other areas of physics and medicine," says Jansen. For example, the detector has measured the radiation field in the polar regions from on board the Proba-V satellite. On board the ISS, it detects current values in the Cupola, the dome-shaped observation module. Timepix3 can remain operational for many years. "It could fly to Mars on long-term missions in future, for example," says Jansen.

The detector on the Zugspitze also has a role in observing space weather. Solar flares and coronal mass ejections are capable of disrupting satellite operations. Particularly strong solar storms can overwhelm Earth's protective magnetic field and affect infrastructure on the ground. The recently opened DLR Institute for Solar-Terrestrial Physics in Neustrelitz is conducting research into space weather and establishing a national space weather service.