Vietnamese scientists explore the universe through some of the world’s largest physics experiments

Through “High Energy Physics Research through Selected International Experiments in Japan,” Vietnamese scientists have joined two of the world’s most advanced particle physics experiments: Belle II and T2K.

It will operate from 2024 to 2026, and is part of an international research collaboration led by Dr. Nguyen Anh Ky of the Institute of Physics of the Vietnam Academy of Science and Technology.

Belle II and T2K are two high-energy physics experiments based in Japan.

Belle II uses the SuperKEKB particle accelerator to study collisions between electrons and their antimatter counterparts, positrons.

T2K uses the J-PARC accelerator and the Super-Kamiokande detector to examine neutrinos, fundamental particles with very small masses that can pass through ordinary matter almost without interacting.

According to Key, both experiments help scientists get closer to understanding the fundamental nature of matter as well as the origin and evolution of the universe.

To conduct studies, researchers accelerate elementary particles to extremely high speeds before they collide and observe how they interact and decay.

These observations are then compared with theoretical predictions. “Our team has the opportunity to work on some of the most important questions in modern fundamental physics while strengthening Vietnam’s scientific and technological capabilities,” Dr. Ky said.

Previously, Vietnamese researchers participated in international trials primarily by learning from collaborators or helping to analyze data, but they now take on a number of core technical responsibilities, he said.

For Belle II, the Vietnamese team, established and led by Ky and with Dr. Dung Van Thanh from Hanoi University of Science and Technology as a key member, contributed to the construction, installation, testing and calibration of the Central Drift Chamber (CDC).

Dr. Dong Van Thanh (second from left) after connecting the Belle-II’s central float chamber. Photo courtesy of Dr. Dong Van Thanh

As a core component of the Belle II detector, the CDC precisely measures the trajectories and torques of charged particles generated during collisions.

Electrons and positrons were accelerated and then subjected to direct collisions.

Antimatter particles have the same mass as regular matter but carry opposite electrical charges.

When matter and antimatter meet, they annihilate each other, releasing energy.

Belle II seeks to answer one of the greatest mysteries of modern physics: why matter was not completely annihilated by antimatter after the Big Bang, leaving enough material to form galaxies, stars, planets, and ultimately life.

The Vietnamese team plays an important role in operating and calibrating many of the detector systems, helping to ensure the accuracy and quality of the experiment’s data.

The SuperKEKB accelerator used by Belle II has repeatedly set world records for instantaneous brightness, a measure of how frequently particle collisions occur, making Belle II one of the most advanced particle physics experiments in the world.

In the T2K experiment, Vietnamese researchers, led by Associate Professor Nguyen Thi Hung Van from the Institute of Physics and Dr. Cao Van Son from the International Center for Interdisciplinary Science and Education, support the operation of the neutrino beam accelerator, manage the nearby detector systems monitoring the neutrino beam, and contribute to simulations and data analysis.

T2K generates a beam of neutrinos by directing high-energy protons toward the target. The resulting neutrinos then travel 295 kilometers to the Super-Kamiokande detector, located approximately 1,000 meters underground, where scientists monitor their interactions.

The large-scale experiment is designed to study neutrino oscillation, the phenomenon in which one type of neutrino transforms into another as it travels long distances. The existence of neutrino oscillation shows that neutrinos have mass, which contradicts the original assumption of the Standard Model that neutrinos are massless or have masses so small that they can be effectively ignored.

Dr. Cao Van Son at the Super Camioncandy neutrino detector located 1,000 meters underground. Photo courtesy of Dr. Cao Van Son

The Vietnamese team works at the end of the experiment, monitoring the direction and interactions of the neutrinos immediately after they are produced. These measurements allow researchers on the detector 295 kilometers away to determine how many neutrinos should arrive and how they have changed during their journey.

“Our responsibilities directly impact the scientific process and results of the entire experiment. Few research groups from other countries have been entrusted with such a position,” Dr. Qi said.

According to the research team, high-energy physics, which explores the deepest structures of matter, has important implications for many other scientific fields, including nuclear physics, astrophysics, cosmology, electronics, and materials science.

Participation in cutting-edge international experiments also enables Vietnamese scientists to gain interdisciplinary knowledge and technical expertise that can later be applied in Vietnam.

Key added that international cooperation makes it possible to share resources and reduce research costs.

High energy physics requires long-term, sustainable investment to develop highly skilled researchers and maintain engagement in experiments that often span several decades, he said, calling for funding mechanisms lasting at least five years per cycle to support long-term scientific planning and development of Vietnam’s basic research workforce.

Professor Nguyen Quang Lim, Chairman of the Evaluation Board of the Vietnam Academy of Science and Technology, praised the project for exceeding its original goals in terms of quantity and quality of publications in leading international journals.

He added that particle physics experiments deserve continued long-term investment to promote Vietnam’s future scientific and technological development.