Searching for Dark Matter

Gravitational interaction – the force that literally holds our universe together – is proof that there must be an abundance of invisible mass which holds celestial objects in place. Since the 1930s, scientists have been on the hunt for it, sometimes through underground experiments literally conducted below the earth’s surface so they are best shielded from interfering cosmic radiation. And this is where the KNF gas pump comes in.

North of Rome, two kilometers underground, an international consortium called XENON100 headed by New York’s Columbia University is carrying out research inside the Gran Sasso mountain. It is one of the most extensive projects worldwide, and the noble gas xenon has an important role to play in it. Here, deep inside the Apennine mountains, powerful KNF pumps are working as part of a purification system which removes other elements from the gas before it is fed into the system. This requires complete leak-tightness at minus 100 degrees Celsius. When other particles hit xenon atoms, they light up, which can be measured both in liquid and in gaseous xenon using highly sensitive sensors. This allows researchers to determine whether Weakly Interacting Massive Particles (WIMPs) – in other words, dark matter – interact with xenon.

To allow the xenon atoms to encounter other particles, the xenon container is consistently enlarged because more xenon means more possible interactions. The latest enlargement of the container from ca. 50 kg to a ton of xenon creates a real challenge for KNF. The pump that has been employed already has the highest flow rate of any in operation, having been specially customized for the project at our Freiburg-Munzingen location. Achieving a higher flow rate in the purification system requires more pumps, and they have to be adaptable to the research program’s ever-changing design.

KNF companies from Germany, the USA, Italy and other countries collaborate with the researchers to modify the pumps and to make quick adjustments where and when they are needed. KNF has to respond quickly to help the researchers meet their project deadlines, which is a prerequisite for receiving the crucial funding.