The newest experiment at CERN, the European Organization for Nuclear Research, is now in place at the Large Hadron Collider in Geneva. , or Forward Search Experiment, was approved by CERN’s research board in March 2019. Now installed in the LHC tunnel, this experiment, which seeks to understand particles that scientists believe may interact with dark matter, is undergoing tests before data collection commences next year.

“This is a great milestone for the experiment,” said , a FASER scientist and 91̽�� associate professor of physics. “FASER will be ready to collect data from collisions at the Large Hadron Collider when they resume in spring 2022.”

FASER is designed to study the interactions of high-energy and to search for new, as-yet-undiscovered light and weakly interacting particles, which some scientists believe interact with . Unlike visible matter, which makes up us and our world, most matter in the universe — about 85% — consists of dark matter. Studying light and weakly interacting particles may reveal clues to the nature of dark matter and other longstanding puzzles, such as the origin of neutrino masses.

�ճ���� consists of 70 members from 19 institutions and eight countries. FASER scientists at the 91̽��include Hsu, postdoctoral researcher Ke Li, doctoral student John Spencer and undergraduates Murtaza Jafry and Jeffrey Gao. The 91̽��team has been involved in efforts to develop software and evaluate the performance of portions of the FASER detector, as well as scrutinize data from the detector during its commissioning period. They will also monitor the performance of instruments in the detector and analyze data when collisions at LHC resume next year.

Researchers believe that LHC’s collisions produce the light and weakly interacting particles that FASER is designed to detect. These may be long-lived particles, travelling hundreds of meters before they decay into other particles that FASER will measure.

The experiment is located in an unused service tunnel along the beam collision axis, just 480 meters — or almost 1,600 feet — from the interaction point of the LHC’s six-story . That proximity puts FASER in an optimal position for detecting the decay products of the light and weakly interacting particles.

The first civil engineering works for FASER started in May 2020. In the summer, the first services and power systems were installed, and in November, FASER’s three magnets were put in place in the trench.

“We are extremely excited to see this project come to life so quickly and smoothly,” said CERN scientist Jamie Boyd, a FASER co-spokesperson. “Of course, this would not have been possible without the expert help of the many CERN teams involved!”

The FASER detector is 5 meters long, or about 16.5 feet, and two scintillator stations sit at its entrance. The stations will remove background interference by charged particles coming through the cavern wall from the ATLAS interaction point. Next is a dipole magnet 1.5 meters, or about 5 feet, long. It is followed by a spectrometer that consists of two dipole magnets, each 1 meter or just over 3 feet long, with three tracking stations, two at either end and one between the magnets. Each tracking station consists of layers of precision silicon strip detectors. Scintillator stations for triggering and precision time measurements are located at the entrance and exit of the spectrometer.

The final component is the electromagnetic calorimeter. This will identify high-energy electrons and photons and measure the total electromagnetic energy. The whole detector is cooled down to 15 C, or 59 F, by an independent cooling station.

Some of these components were assembled from spare parts of other LHC experiments, including ATLAS and , according to Boyd.

FASER will also have a subdetector, called FASERν, which is specifically designed to detect neutrinos. No neutrino produced at a particle collider has ever been detected, despite colliders producing them in huge numbers and at high energies. FASERν is made up of emulsion films and tungsten plates to act as both the target and the detector to see the neutrino interactions. FASERν should be ready for installation by the end of the year. The whole experiment will start taking data during Run 3 of the LHC, starting in 2022.

FASER is supported by the Heising-Simons Foundation and the Simons Foundation.

For more information, contact Hsu at schsu@uw.edu.

Adapted from a by CERN.

The research board of CERN, the European Organization for Nuclear Research, on March 5 approved a new experiment at the Large Hadron Collider in Geneva, the world’s largest particle accelerator, to search for evidence of fundamental dark matter particles. The Forward Search Experiment — or FASER — seeks to answer one of the outstanding questions in particle physics: What is dark matter made of?

“There is strong evidence that most of the matter in the universe — about 85 percent — is dark matter, and that dark matter is made up of an unknown class of fundamental particles,” said , an associate professor of physics at the 91̽�� and member of the FASER team. “The identity of dark matter particles is a major mystery in particle physics, and one that we think FASER could help solve by identifying a class of particles associated with dark matter.”

FASER is a partnership of 16 institutions around the globe, including the UW, and co-led by scientists at the University of California, Irvine and CERN, which operates the Large Hadron Collider, or LHC. The five-year FASER project is funded by grants of $1 million each from the Heising-Simons Foundation in California and the Simons Foundation in New York, with additional support from CERN.

FASER is trying to find indirect evidence for the light, weakly interacting particles that may interact with dark matter. So far, these particles have eluded scientists. But the FASER team will try to detect traces of these particles as they decay from the LHC’s proton beams.

“Seven years ago, scientists discovered the Higgs boson at the Large Hadron Collider, completing one chapter in our search for the fundamental building blocks of the universe, but now we are looking for new particles,” said Jonathan Feng, FASER co-spokesperson and professor of physics and astronomy at UC Irvine. “The dark matter problem shows that we don’t know what most of the universe is made of, so we’re sure new particles are out there.”

The FASER instrument is designed to be compact, measuring about 1 meter in diameter and 5 meters long. It will be placed at a specific point along the 16-mile loop of the LHC, about 480 meters, or 1,574 feet, away from the hulking, six-story instrument used by the Collaboration to discover the .

As proton beams pass through the interaction point at the ATLAS instrument, some theories indicate that they may decay to a candidate particle that interacts with dark matter, a , which in turn could decay into a pair of particles — an electron and a — as it passes through concrete in the LHC tunnel and then into the FASER instrument. The instrument will be able to measure the progress of particle decay, and will collect data when ATLAS is operating.

“The high number of particles at the LHC gives us this irresistible chance to try to detect new lightweight particles — and even trace them as they travel hundreds of meters from their source to the detector,” said Hsu.

At the UW, Hsu’s group studies simulations of detection events by the FASER instrument, working out the instrument parameters and data-analysis tools needed to accurately trace any detected particles back to their sources. These tools will help separate real signals of dark matter-associated particles from background events.

“One of the advantages of our design is that we’ve been able to borrow many of the components of FASER — silicon detectors, calorimeters and electronics — from the ATLAS and collaborations,” said Jamie Boyd, CERN research scientist and co-spokesperson for FASER. “That’s allowing us to assemble an instrument that costs hundreds of times less than the largest experiments at the LHC.”

The detector’s support platform, which will hold intricate magnets and detectors in place, will be designed and manufactured by a 91̽��team led by laboratory engineer Bill Kuykendall in the Department of Mechanical Engineering, with input from 91̽��physics professor .

The FASER detector, which will be one of only eight research instruments at the LHC, is being built and installed during the collider’s current hiatus and will collect data from 2021 to 2023. The LHC will be shut down again from 2024 to 2026. During that time, the team hopes to install the larger FASER 2 detector, which will be capable of unveiling an even wider array of mysterious, hidden particles.

The FASER team will consist of 30 to 40 members, a relatively small number compared to other groups conducting research at the LHC. In addition to CERN, UC Irvine and the UW, other institutions participating in the FASER endeavor are the University of Oregon, Rutgers University, the University of Geneva in Switzerland, the University of Bern in Switzerland, Italy’s National Institute for Nuclear Physics Genoa Section, China’s Tsinghua University, Technion – Israel Institute of Technology, Israel’s Weizmann Institute of Science, the Johannes Gutenberg University of Mainz in Germany, Kyushu University in Japan, Nagoya University in Japan, the “KEK” High Energy Accelerator Research Organization in Japan and the University of Sheffield in the U.K.

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For more information, contact Hsu at schsu@uw.edu or 206-543-2760.

Adapted from a by the University of California, Irvine.

The Large Hadron Collider at CERN, the European research facility, on June 2 started recording data from the highest-energy particle collisions ever achieved on Earth.

Its operators announced they had achieved “stable beams,” or trains of proton bunches moving at almost the speed of light around the 27-kilometer (17-mile) ring of the collider — the signal that they can begin taking data.

This new proton collision data, the first recorded since 2012, will enable an international collaboration of researchers — including many from the 91̽�� — to study the Higgs boson, search for dark matter and develop a more complete understanding of the laws of nature.

“Together with collaborators from around the world, scientists from roughly a hundred U.S. universities and laboratories are exploring a previously unreachable realm of nature,” said James Siegrist, the U.S. Department of Energy’s associate director of science for high-energy physics. “We are very excited to be part of the international community that is pushing the boundaries of our knowledge of the universe.”

Members of the 91̽��team are physics faculty members , , , and , post-doctoral researchers Emma Torró, Nikos Romotis and Lynn Marx and graduate students Heather Russell, Rachel Rosten, Pedro De Bruin and Nikola Whallon. The graduate students and post-doctoral researchers are currently working at CERN.

The Large Hadron Collider, the world’s largest and most powerful particle accelerator, reproduces conditions similar to those that existed immediately after the Big Bang.

In 2012, during the collider’s first run, — a fundamental particle that helps explain why certain elementary particles have mass. U.S. scientists represent about 20 percent and 30 percent, respectively, of the ATLAS and CMS collaborations, the two international teams that co-discovered the Higgs boson. Hundreds of U.S. scientists played vital roles in the Higgs discovery and will continue to study its remarkable properties.

Scientists will use the new data to pin down properties of the Higgs boson and search for new physics and phenomena such as dark matter particles — an invisible form of matter that makes up 25 percent of the entire mass and energy of the universe.

Physicists will also endeavor to answer questions like: Why is there more matter than antimatter? Why is the Higgs boson so light? Are there additional types of Higgs particles? What did matter look like immediately after the Big Bang?

The collider was turned off in early 2013 and engineers spent two years preparing the machine to collide particles at a much higher energy and intensity. During the shutdown U.S. scientists and their international collaborators installed several new components in the four LHC detectors, including components for the ATLAS detector designed and fabricated by the 91̽��team.

These components, together with other upgrades, will allow physicists to record more information about the particles produced during the high-energy collisions.

“The 91̽�� is a key player, in the sense that we contributed enormously to the design and fabrication of the ATLAS detector at the beginning,” said Lubatti. “And we have recently contributed a new detector that will enhance our ability to make discoveries by making measurements very close to the collision point of the protons.

“Having a measurement so close to the collision point greatly increases our ability to identify particles that may be indicators leading to new discoveries. This will enhance our understanding of the fundamental interactions that define the building blocks of matter in the universe,” said Lubatti, who will soon join his colleagues in Geneva, Switzerland.

“The first three-year run of the LHC, which culminated with major discovery in July 2012, was only the start of our journey. It is time for new physics!” said Rolf Heuer, CERN director-general, in a . “We have seen first data beginning to flow. Let’s see what they will reveal to us about how our universe works.”

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For more information, contact Lubatti at 206-962-1602 or .