LHCb Detector

The LHCb experiment consists of essentially the same detector components as any other particle physics experiment (details: CMS model).

The detector consists of:

• Tracking detectors for a precise measurement of charged particle tracks, the collision point of the LHC protons, and the decay vertices of short-lived particles.
• A strong magnet that deflects charged particles. The curvature of the tracks allows the determination of the charge and momentum of the particles.
• In the calorimeters almost all particles are stopped and their energy is measured.
• Muons are not stopped in the calorimeters and are detected in special muon chambers.
• A speciality of the LHCb experiment is detectors that allow measurement of the velocity of charged particles. Combined with the measurement of momentum, this allows the identification of different types of charged particles.

The LHCb experiment specialises in studying the properties of particles containing so-called "beauty" quarks. Since these particles are preferentially produced at small angles with respect to the colliding proton beams, the experiment covers only an angular range of about 14° around the proton beam.

The tracking detector in front of the magnet was built at UZH. It consists of 4 layers of finely segmented semiconductor detectors. Each of these layers consists of 0.5 mm thick silicon with readout strips about 0.2 mm wide and 10 to 40 cm long.  Charged particles flying through the silicon release electrons from the atomic lattice. The electrical charge released in the process is collected on the readout strips, electronically amplified, and then used with signals from the other track detectors to reconstruct the tracks of charged particles. The detector was in operation from 2010 to 2019, it was 160 cm wide and 130 cm high and the 4 layers had a total area of 8.4 m2 and 144,000 readout channels. A prototype of the detector with readout electronics is exhibited here.

Principle of operation of a silicon detector:  Charged particles penetrating or traversing the detector create electron-hole pairs. The electron-hole pairs are separated by an electric field and drift to the electrodes.