Collider Detector at Fermilab - Layer 2: Silicon Detector

Layer 2: Silicon Detector

Surrounding the beam pipe is the silicon detector. This detector is used to track the path of charged particles as they travel through the detector. The silicon detector begins at a radius of r = 1.5 cm from the beam line and extends to a radius of r = 28 cm from the beam line. The silicon detector is composed of seven layers of silicon arranged in a barrel shape around the beam pipe. Silicon is often used in charged particle detectors because of its high sensitivity, allowing for high-resolution vertex and tracking. The first layer of silicon, known as Layer 00, is a single sided detector designed to separate signal from background even under extreme radiation. The remaining layers are double sided and radiation-hard, meaning that the layers are protected from damage from radioactivity. The silicon works to track the paths of charged particles as they pass through the detector by ionizing the silicon. The density of the silicon, coupled with the low ionization energy of silicon, allow ionization signals to travel quickly. As a particle travels through the silicon, its position will be recorded in 3 dimensions. The silicon detector has a track hit resolution of 10 um, and impact parameter resolution of 30 um. Physicists can look at this trail of ions and determine the path that the particle took. As the silicon detector is located within a magnetic field, the curvature of the path through the silicon allows physicists to calculate the momentum of the particle. More curvature means less momentum and vice versa.