The first layer of the ATLAS detector’s calorimeter is made of 8’200 lead plates and electrodes folded into an accordion shape and immersed in liquid argon. ATLAS (A Toroidal LHC ApparatuS) is the largest, general-purpose particle detector experiment at the Large Hadron Collider (LHC). As particles cross the folds and interact with the lead atoms, electrons and photons are ejected. There is a knock-on effect and as they continue on into the argon, a whole shower of secondary particles is produced. The electrodes register a signal that gives a measurement of the energy of the initial particle. As with most of the LHC detectors, the structural design challenge is to hold the heavy elements in place without affecting the measurements of the particles. Here, the layers of honeycomb spacer are designed to do just that. They separate the copper electrode layer from the lead and stainless steel absorber, allowing the liquid argon to flow freely in between.

Radioactive nuclei are produced at the ISOLDE facility by shooting a high-energy beam of protons on a thick target. By studying some of these nuclei, physicists are improving the knowledge of nucleosynthesis, the process through which stars produce chemical elements. This is a prototype that was developed for the CERN Open Days, in 2019.

An ionization chamber with fast timing properties was built at CERN for measuring fission cross-sections of minor actinides at the n_TOF neutron beam. The design of this chamber and of the front-end electronics was optimized to match the innovative features of the n_TOF facility, in particular the high instantaneous neutron flux and low background. Micromegas (Micro-MEsh Gaseous Structure) detectors are gas detectors consisting of a stack of one ionization and one proportional chamber. A micromesh separates the two communicating regions, where two different electric fields establish respectively a charge drift and a charge multiplication regime. The n_TOF facility at CERN provides a white neutron beam (from thermal up to GeV neutrons) for neutron induced cross section measurements.

An alternative method of detecting particles spraying out of collisions in the inner regions of experiments uses scintillating fibres.

A good dozen different targets are available for ISOLDE, made of different materials and equipped with different kinds of ion-sources, according to the needs of the experiments. Each separator (GPS: general purpose; HRS: high resolution) has its own target. Because of the high radiation levels, robots effect the target changes, about 80 times per year. In the standard unit shown in picture _01, the target is the cylindrical object in the front. It contains uranium-carbide kept at a temperature of 2200 deg C, necessary for the isotopes to be able to escape. At either end, one sees the heater current leads, carrying 700 A. The Booster beam, some 3E13 protons per pulse, enters the target from left. The evaporated isotope atoms enter a hot-plasma ion source (the black object behind the target). The whole unit sits at 60 kV potential (pulsed in synchronism with the arrival of the Booster beam) which accelerates the ions (away from the viewer) towards one of the 2 separators.

Particles coming from the universe are crossing the earth all the time – they are harmless but invisible to us. Cloud Chambers are detectors which make the tracks of the particles visible. Some decades ago these detectors were used at CERN in the first particle physics experiments.

The CMS (Compact Muon Solenoid) Tile Calorimeter is a pivotal component of the CMS detector, which is one of the major experiments at the Large Hadron Collider (LHC) at CERN. Designed to measure the energy of particles, the calorimeter plays an essential role in the study of high-energy physics.