August 8, 2022
Link Estadão

The machine behind the “God Particles” searches for dark matter

The particle accelerator at CERN was responsible for the discovery of the Higgs boson, also known as the ‘God particle’.

Ten years ago, a team running the world’s largest particle accelerator made history by discovering the Higgs boson, central to understanding the creation of the universe, and which earned it the nickname “God Particle.”

After a hiatus of more than three years for improvements, the accelerator, operated by the European Organization for Nuclear Research (CERN, in French), is collecting data again. The goal this time is to prove the existence of another mysterious substance – dark matter.

Although most scientists believe in the existence of dark matter, no one has been able to see it or its formation. Data collection and energy improvements being made at a particle accelerator, called the Large Hadron Collider (LHC), could give researchers one of their best chances to visualize and understand matter.

“If we can discover the properties of dark matter, we will find out what our galaxy is made of,” said Joshua Ruderman, a professor of physics at New York University. “It would be revolutionary.”

Dark matter has fascinated physicists for decades. Many believe that it forms an important part of the universe, and knowing more about it can give clues to how the universe came into being.

According to CERN scientists, all stars, planets and galaxies in the universe make up only 5% of the matter in it. About 27% of the universe is believed to be made up of dark matter that does not absorb, reflect or emit light, making it extremely difficult to detect. The researchers say it’s there because they’ve seen its gravitational pull on objects — and how it helps distort light.

They hope the LHC can help. The accelerator was built over a decade by the European Organization for Nuclear Research to help answer outstanding questions in particle physics. The device is located at a depth of about 100 meters underground, in a tunnel near the French-Swiss border and the city of Geneva. Its circumference extends for nearly 27 kilometers.

Inside the accelerator, superconducting magnets are cooled to nearly minus 271 degrees Celsius – colder than space – as two beams of particles moving at close to the speed of light collide. Using sophisticated sensors and screens, scientists are analyzing the material from these collisions, which cause conditions similar to the Big Bang. This allows them to learn about the first moments of the universe.

The device began operating in September 2008, but has been turned off several times to make improvements. Over the past three years, engineers have been improving the throttle so it can detect more data and operate at higher speeds. Now the accelerator can operate at its highest energy level ever: 13.6 trillion electronvolts; It allows scientists to conduct larger and more complex experiments that could yield new insights into particle physics.

“This is a significant increase,” said Mike Lamont, director of accelerators and technology at CERN. “It opens the way to new discoveries.”

In the early universe, particles were massless, so scientists have long wondered how stars, planets, and life forms were formed. In 1964, physicists François Englert, Peter Higgs and others hypothesized that a force field gives particles mass when they come into contact, but they were unable to document the existence of the system.

The discovery of the Higgs boson, part of the hypothetical force field, earned Englert and Higgs the Nobel Prize in Physics.

The particle has astonished scientists as well as the general public. CERN and the metronome feature prominently in Dan Brown’s book and in the film adaptation of the novel of the same name, “Angels and Demons”.

But now researchers want to answer more troubling questions, especially those related to dark matter.

During the LHC’s four-year experiment, scientists hope to find evidence of dark matter. While the device is running, the protons rotate at nearly the speed of light. The hope, according to the researchers, is that when they collide, they will create new particles that have similar properties to dark matter.

They also hope to learn more about how the Higgs boson behaves. On Tuesday, shortly after the accelerator began collecting data, scientists at CERN announced that they had found three new “strange” particles that could give clues to how subatomic particles communicate with each other.

“High-energy accelerators remain the most powerful microscope at our disposal to explore nature on the smallest scales and discover the fundamental laws that govern the universe,” said Gian Giudice, Head of Theory Department at CERN.

New York University’s Ruderman said CERN’s journey to learn about dark matter and explain the origins of the universe makes him anxiously await the results of the experiment. Research excites him a lot. “That’s why I get up in the morning,” he said.

Once he starts producing data from the experiment, Ruderman will check to see if there are new particles emerging. Even if it did, it would be difficult to immediately determine whether or not it was dark matter.

First, you will need to evaluate whether or not the particle in question is emitting light. If so, this reduces the possibility of it being dark matter. Second, the particle should show signs of being in the vicinity for a long time and not immediately decay, because dark matter, in theory, should be able to survive for billions of years. They also expect the particle to behave similarly to current theories about dark matter.

It could take more than four years, Ruderman said, to make the discovery.

If CERN scientists do not detect dark matter in the next four years, they will have more updates in progress. Improvements are likely to take three years after the last hiatus, leaving the fourth round of data collection and trials expected to begin in 2029.

As planned, the attempt could collect 10 times more data than previous experiments, according to the CERN website. But revealing the secrets of the universe is not easy.

“It’s challenging and the research can take a lifetime,” Rodman said. / ROMINA CACIA translation