The world machines
© Getty
December 2018

The world machines

By Dr. Christian Heinrich
Physicists use particle accelerators to smash tiniest particles against each other in a quest for new answers to humanity’s big questions. Particle accelerators are even utilized to fight cancer and to produce computer chips.

​The world around us, our bodies and even the paper of this magazine – what exactly does all this consist of? Sure, we know by now that everything’s made up of atoms. And atoms consist of even smaller components, of electrons, neutrons and protons. But what are the absolutely smallest components that everything is made up of? Or could there be parts even smaller than that? And what about the very beginning, how did the universe suddenly form out of nothing? To answer humanity’s biggest questions, scientists around the world examine the smallest components of the cosmos and the so-called particle accelerators are their most important tools in their quest for knowledge.

As the name says, they accelerate charged particles like protons or atoms so that they collide with each other at an enormous speed. When this happens scientists attempt to catch a brief glimpse of new, even smaller particles that may have been created in the process.

It’s the length that does it

There are various types of particle accelerators that make it possible to achieve respectively high velocities of the particles.

The linear accelerator is a very long pipe with a wall consisting of various so-called drift tubes. These drift tubes generate a constantly changing voltage. Similar to the way a magnet works, the particle is attracted by the respective front drift tube and repelled by the rear one. In this way, the particle accelerates with every drift tube it passes. To achieve the desired velocities, a linear accelerator has to be several kilometers long.

The synchrotron operates according to a similar principle. However, it includes magnets that slightly divert the particles. This allows them to be guided on a type of circular path which they travel on over and over. While this enables high acceleration, it also requires a lot of space because the bends in the pipes must not be sharp. The world’s largest synchroton-type particle accelerator, the so-called Large Hadron Collider (LHC), is located near Geneva, Switzerland, on the premises of the European Organization for Nuclear Research (CERN) and has a length of nearly 27 kilometers (17 miles).

The world machines
The CERN particle accelerators are located 100 m (328 ft) deep in the ground below Geneva. The biggest one, the Large Hadron Collider (LHC), has a circumference of 26.66 km (16.56 mi). In December 2018, it was shut down for a two-year period of maintenance and upgrading© DESY
On a collision course at the speed of light

However, not only the size of the accelerators is breathtaking in the light of the tiny particles. The design of these systems is extremely complex as well. It takes 1,232 magnets, each 14 meters (46 feet) long and weighing 35 metric tons  (38.5 short tons), to keep the smallest particles on their circular path at the LHC in Geneva. The facility requires enormous cooling as well: down to minus 270 degrees centigrade (minus 454 degrees Fahrenheit)! Plus, the tiny particles should not collide with other ones during the acceleration phase, so a so-called ultra-high vacuum has been created inside the pipe. There’s no air in it and practically no atoms either.

3,000 people

work at CERN, making it the world’s biggest research center in the field of particle physics. Even larger is the number of visiting scientists: More than 10,000 experts from 85 nations are involved in CERN experiments of the “world’s largest knowledge machine.” The things they’re looking for include the so-called super-symmetry (SUSY) particles that might also provide an explanation of the Dark Matter that holds universes together. Tracking them down is even trickier and more energy-intensive than the confirmation of the Higgs bosons.

This complexity pays off, though. A particle accelerator like the LHC achieves extremes that are unique in the world: When the particles collide with each other they’re traveling nearly at the speed of light. The smallest particles pass the 27-km (17-mi) tunnel 11,000 times per second. When the ions crash into each other, they generate temperatures of over 4,000 billion degrees! That’s about 300,000 times hotter than the center of the Sun. In the process, quarks and gluons “cook” to a kind of primeval plasma soup that takes the scientists as close as never before to the conditions prevailing at the time of the Big Bang.

In 2009

the movie based on Dan Brown’s thriller “Angels & Demons” shines the spotlight on the work done at CERN. In the book, a visible amount of antimatter is stolen from the research center – which is pure fiction. Although about one million “antiprotons” per year are in fact produced at CERN it’s impossible to produce the quantity shown in the movie. It would take one billion years just to produce one gram (0.03 ounces) of antimatter.

But all this has to be measured as well. At the LHC, this is done by means of the ATLAS detector, a huge receptacle for atomic debris with a length of 45 meters (148 feet) and a width and height of 22 meters (72 feet). For the physicists, the detectors are a kind of high-performance camera taking more than 40 million pictures per second.

Particle accelerators like the LHC in Geneva or the DESY in Hamburg advance physics and our entire understanding of the world by producing new findings – about the behavior of the smallest particles or their existence in the first place. Scientists at CERN, for instance, in a one-billion-euro experiment, discovered a new elementary particle that was subsequently confirmed as the Higgs boson. The tiny particle that’s also referred to as the “God particle” has an extremely short life span of about 10 to 22 seconds, but, put in very simple terms – is responsible for particles having mass.

Chemists, material scientists and biologists use accelerators to create the brightest X-ray light in the world (See info box below) in order to examine diverse materials, from aircraft turbines to vital proteins.

Deployed in medicine and manufacturing

However, only a few hundred of the more than 17,000 particle accelerators that exist around the world are used for scientific research. Another large field is medicine or, more precisely, radiation therapy. Smallest, extremely accelerated parts serve to specifically treat cancer as well. Somewhat smaller particle accelerators, so-called cyclotrons, are frequently used for this purpose. Here, in a spiral-like path, the electrons are accelerated also by means of magnets until they’ve finally achieved the desired speed. Cyclotrons often have a diameter of three to four meters (10 to 13 feet) which means that they can still be accommodated by hospital facilities. Some 7,000 particle accelerators are used for medical purposes worldwide to treat 30 million patients per year. The other systems are mainly found in manufacturing operations or, more precisely, in semiconductor production. The utilization of ion accelerators makes it possible to build fast transistors in chips which are essentially used in all areas of digital electronics.

Meanwhile the scientists who are primarily focused on gaining new insights produce new knowledge from time to time. Last winter, for instance, CERN scientists found out further details about the physical ­behavior of the Higgs bosons. And that’s just the beginning. The world of the smallest particles still holds an abundance of other great discoveries in store for us.

The world machines© DESY
DESY and the fastest X-ray images in the world

5 million flashes per second can be fired by the new X-ray laser “European XFEL” (pictured) at Deutsches Elektronen-Synchrotron (DESY) – 40,000 times as many as the previous best pulse rate of an X-ray laser. For instance, the 3.4 kilometer (2.11 mile) long accelerator that shoots the world’s fastest serial X-ray images, made it possible to reveal the previously unknown structure of an antibiotics killer. Installed upstream of the X-ray laser is a 1.7-km (1.05-mi) – and thus the world’s longest – superconducting linear accelerator, a proprietary DESY development. In addition to particle physics and photon research, the development and construction of new particle accelerators is another focal area at DESY. The DESY tunnel system in Hamburg meanders underground all the way to the neighboring state of Schleswig-Holstein. DESY is part of the Helmholtz Association that Schaeffler cooperates with in research projects as well and, by its own account, ranks among the world’s leading accelerator centers. The LHC particle accelerator alone produces data volumes per year of a magnitude that could fill a million DVDs.