SND@LHC (Scattering and Neutrino Detector at the LHC) is an experiment designed to study neutrinos, fundamental particles that have no electrical charge and whose mass is extremely small.
Although particle colliders produce neutrinos in large quantities, a neutrino has never been directly observed in a collider. This is because they interact very weakly with matter, so they often go undetected in conventional detectors. Furthermore, most of the neutrinos generated at the LHC are in a little-explored energy range, making their study especially interesting.
The SND@LHC detector consists of a neutrino target, followed by a device that measures its energy and detects the muons—particles similar to electrons, but heavier—produced when neutrinos interact with the target.
This system is installed underground, near the ATLAS experiment, in a disused tunnel connecting the LHC to the Super Proton Synchrotron (SPS). Located slightly outside the LHC beamline, the detector can detect neutrinos produced in LHC collisions that emerge at small angles to the beam. These angles are wider than those covered by FASERν, a subdetector of the FASER experiment that also studies neutrino interactions at high energies, but is located directly above the beamline.
A large proportion of the neutrinos detected by SND@LHC come from the decays of particles made of heavy quarks, so the experiment also allows the production of these types of particles to be studied in an angular range inaccessible to other LHC experiments.
In addition, SND@LHC searches for weakly interacting particles not predicted by the Standard Model, which could constitute dark matter.
The experiment was approved in 2021, built, installed, and put into operation underground in about a year. It began collecting data during LHC Run 3, which began in July 2022.
The SAPHIR Millennium Institute has steadily expanded its involvement in the SND@LHC experiment, a pioneering CERN initiative dedicated to studying neutrinos produced in collisions at the Large Hadron Collider (LHC) and searching for signs of new physics. Within this collaboration, SAPHIR has played a key role in various stages of the design, testing, and production of key detector components.
Among its most notable contributions is its work with TOF (Time-of-Flight) modules, where Chilean researchers have led the design, laboratory testing, and validation through beam tests, all aimed at improving temporal resolution for the precise identification of particles. In addition, the SAPHIR team has participated in the production of a prototype of the Shashlik-type electromagnetic calorimeter, using SiPMs (Silicon Photomultipliers), and has collaborated on its testing with particle beams directly at CERN. An innovative aspect of the institute’s work is the development of data analysis using scanning microscopy at Andrés Bello University, a critical technique for the precise characterization of interactions recorded by the detector. Finally, SAPHIR actively collaborates on joint research and development tasks with pion beams, contributing to a detailed understanding of the detector’s performance with different types of particles. This participation reinforces the institute’s commitment to high-energy physics and positions Chile as an emerging player in cutting-edge experimental research.
