World’s Largest Machine Uses Off-the-shelf Automation Gear to Ensure Safe Operation
A peek behind the curtain at European particle physics lab CERN reveals the role that several hundred Siemens systems play in ensuring the high availability, operational reliability, and safety of all critical systems–especially for its Large Hadron Collider.
Sitting astride the border of France and Switzerland, CERN (Conseil Européen pour la Recherche Nucléaire), the European Organization for Nuclear Research, is one of the world’s largest and most respected centers for scientific research. Its business is fundamental physics, finding out what the universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter: the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of nature.
The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.
The Mother of All Machines
The centerpiece of CERN is a particle accelerator known as the Large Hadron Collider (LHC). This machine accelerates elementary atomic particles to nearly the speed of light, sending them along a 17-mile circuit until they collide with high energy. The results of such collisions are measured by one of four detectors along the LHC. The largest detector is called ATLAS (an acronym for “a toroidal LHC apparatus”), which is 72 feet in diameter and weighs 7,000 pounds. Scientists at CERN are using ATLAS to find what they call the “Higgs boson.” Higgs, they believe, is a particle, or set of particles, that might give others mass. The Higgs boson is often referred to as “the God particle” by the media after the title of Leon Lederman’s book, The God Particle: If the Universe Is the Answer, What is the Question?
Due to its size and complexity, the LHC is frequently called the world’s largest machine. For instance, to archive all the measured data from a single year (at least 15 million gigabytes) would require 1.7 million double-sided data DVDs.
Getting Performance Down Cold
To keep the speeding atomic particles in their track, the LHC uses 9,600 magnets, each with a length of nearly 46 feet. 1,200 of these magnets are superconductive, requiring cooling to -271.3° C—close to absolute zero. To achieve this temperature, several tons of gaseous helium, 10,000 tons of liquid nitrate, and 60 tons of liquid helium are required. The refrigeration units have a power rating of 18 kilowatts each.
To enable experiments to be conducted with the necessary precision, safety, and stability, numerous powerful control systems are required. Siemens provides the hundreds of systems installed at CERN, ensuring the high availability and operational reliability of all critical systems. “The cooling process on its own is controlled with the help of 16 Simatic S7-400 programmable logic controllers,” says Patrick Leidi, Siemens’ technical account manager at CERN.
Approximately 250 closed-loop controls and 500 alarms and locks monitor the controls, communicating via PROFIBUS or WorldFIP fieldbus. They also access 15,000 radiation-resistant sensors and actuators in the direct environment of the LHC. Further, Siemens subsidiary ETM Professional Control provides the system responsible for visualizing and monitoring most of the systems in the LHC.
Since measurement and operating devices in the LHC are exposed to a high level of radiation. Scientists use proton bombardment to test the reliability of new components before they are installed. The field devices of the Simatic ET 200M distributed I/O systems were subjected to this endurance and reliability test, passing with flying colors.
CERN uses a train inspection monorail (TIM) for fully automatic inspections and measurements in areas of the linear accelerator that would be too dangerous for personnel. The TIM is equipped with a laser scanner designed to detect obstacles; it is controlled by a fail-proof Simatic S7-300 that triggers an emergency stop via PROFIsafe should the need arise.
“It must be possible to bring the vehicle to an immediate stop if it encounters people or an unexpected obstacle in the tunnel,” says Leidi. The modules communicate to each other by means of an industrial wireless LAN (IWLAN).
The largest and most sophisticated scientific instruments in the world are used at CERN. Scientists from every corner of the globe go there to research the origin and development of the universe. “Siemens is proud is be making a vital contribution to this effort,” says Leidi. “Anyone who works at a facility like this—whether for CERN, Siemens, or any other contributing company—is immediately captivated by the research work being done and the technologies it employs. We all share the unique feeling of working directly at the interface between the past and the future.”
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