When we think of restarting a machine, we often envision simply pressing a button and watching it come to life. However, the reality is much different when it comes to major physics experiments like the Large Hadron Collider (LHC) at CERN. Unlike regular devices, the LHC requires a meticulous process of resetting and recalibrating to ensure accuracy in data collection. As a CERN physicist involved in the reset process of the ATLAS experiment, I have experienced firsthand the intricate nature of maintaining and restarting these massive experiments.
Each winter, the collider and its experiments at CERN go into hibernation. This break serves multiple purposes, including the need to replace parts, install new components, and avoid high electricity costs during the winter months. The complexity of the machines used at CERN necessitates this annual downtime to ensure everything is in optimal working condition. As spring approaches, teams at CERN gear up for a new season of data collection by preparing the LHC and its experiments for operation.
The first phase of restarting the LHC involves waking up the particle detectors using cosmic rays. These subatomic particles, created by energetic particles from space interacting with Earth’s atmosphere, serve as a natural source for testing the detectors. By analyzing the trajectory and energy of cosmic rays passing through the detectors, physicists can ensure everything is functioning as expected. While cosmic rays provide valuable initial testing, they are not sufficient for more in-depth verification.
To conduct further tests on the detectors, physicists at CERN utilize subatomic splashes created within the LHC’s accelerator pipe. These splashes, generated by protons colliding with a metal collimator, offer a denser and more predictable source of particles for analysis. By observing how the detectors respond to these controlled collisions, researchers can verify the detectors’ accuracy and ability to record data at the required speed. This testing phase is critical in ensuring that the experiments are ready for data collection.
One of the challenges in restarting experiments like ATLAS is calibrating specific detectors, such as the Tile calorimeter, which measures the energy of particles like neutrons and protons. To accurately calibrate this detector, researchers need to generate muons, which are particles that can pass through multiple sensor rows without losing much energy. By setting up controlled collisions with the collimator, physicists can produce horizontal muons that traverse the calorimeter’s tiles in a row, allowing for precise data collection and calibration.
After weeks of meticulous testing and calibration, the LHC is finally ready to accelerate protons to their maximum energy levels and initiate collisions. This marks the beginning of a new season of data gathering, where physicists and researchers at CERN eagerly await the possibility of uncovering new discoveries about the universe’s fundamental particles. The intricate process of restarting experiments after annual upgrades highlights the dedication and precision required in the field of particle physics.
The restart process of experiments at CERN showcases the complex and detailed work undertaken by physicists and engineers to ensure the success of groundbreaking research. From utilizing cosmic rays for initial testing to generating controlled splashes of particles for calibration, every step in the restart process is crucial for the accurate collection of data. As we continue to push the boundaries of particle physics, the meticulous nature of experiments at CERN serves as a testament to the commitment to advancing scientific knowledge and understanding the fundamental building blocks of the universe.
Leave a Reply