Particle astrophysics group at the RWTH-Aachen (Lichtenberg Professorship by the VW-Foundation)

Welcome to the particle astrophysics group! We are conducting research in experimental astrophysics and are part of two research collaborations, CDMS II and XENON

The CDMS II experiment uses germanium and silicon semiconductor detectors cooled to about 20 mK to look for the extremely rare events in which a dark matter particle bound to our galaxy will elastically scatter off a nucleus in the crystal. The experiment is located in the Soudan Mine in Northern Minnesota,about half a mile beneath the earth's surface to prevent cosmic rays from interacting in the detectors. It is also shielded by several layers of low radioactivity lead and polyethylene against radiation coming from the Soudan rock and is surrounded by an active plastic scintillator to tag muons making it through the rock.CDMS II measures both the phonon (or lattice vibration) and the small charge signal produced when a particle interacts in the silicon or germanium material. The ratio of the two can tell us whether the interaction was caused by dark matter particles, or just by background radiation.

A more detailed description can be found on the official CDMS website at the UC Berkeley.

The XENON experiment is also designed to look for dark matter particles originating from the Milky Way halo. In this case, the detection medium is liquid Xenon, and the measured signals are electrical charge and xenon scintillation light in the UV-region. Similar as in the case of CDMS, the ratio of charge to light is used to differentiate dark matter interactions from background radiation. Liquid xenon has a high density, and thus a large self-shielding power. It can be made into a large, homogeneous detector with excellent energy and 3-D position resolution if both charge and light are detected. The first prototype, XENON10, with a total of about 22 kg of liquid xenon, has been operating stably at the Gran Sasso Laboratory in Italy and has delivered first results in 2007. While a larger module is currently in planning, the proposed final experiment will contain 1 tonne of liquid xenon. Such an experiment will not only have a fair chance of detecting dark matter particles, but may also be able to measure their interaction rate with high precision.

For a detailed description see the official XENON website at Columbia University.