J-PARC News July 2025 (Issue #243)
■ Press Release
(1) Giant Hall Effect on Highly Conductive Frustrated Magnetic Materials
— Demonstration of a New Mechanism for the Anomalous Hall Effect in Magnetic Materials — (June 20)
In magnetic materials, the Hall effect is categorized into the "ordinary Hall effect" and the "anomalous Hall effect." The anomalous Hall effect is further divided into two mechanisms: an "intrinsic mechanism" and an "extrinsic mechanism," where conduction electrons are asymmetrically scattered depending on their spin direction due to slight impurities. Recent theoretical studies proposed that fluctuations of localized spins with special spatial arrangements can produce an anomalous Hall effect, like this impurity scattering mechanism. This has attracted significant attention, although experimental studies have so far been limited to only a few materials.
In this study, a high-quality single crystal of GdCu2 (Gd: Gadolinium, Cu: Copper), which exhibits extremely high conductivity at low temperatures, was fabricated. A neutron diffraction measurement of this crystal at "SENJU", the extreme environment single crystal neutron diffractometer at the Materials and Life Science Experimental Facility (MLF), confirmed that the rapid increase in magnetization under a magnetic field is due only to changes in the solid angle of the spins, without altering the periodic pattern of the magnetic structure. Furthermore, they observed the Hall conductivity 10 to 100 times greater than typical values seen in magnetic materials, along with complex magnetic field-dependent behavior, including sign reversal. Computational analysis revealed that this giant Hall effect can be explained by a new electron scattering mechanism caused by abrupt changes in the electronic state and fluctuations arising from the unique spatial arrangement of spins.
These findings are expected to significantly contribute to the understanding and further exploration of the microscopic mechanisms behind the complex Hall effects in highly conductive frustrated magnetic materials.
For more details (available in Japanese only), please visit the J-PARC website.
https://j-parc.jp/c/press-release/2025/06/20001564.html
(2) Captured the Reaction Process of a Cancer-Related Enzyme!
— Observing Enzymatic Mechanisms Using X-rays and Neutrons — (July 15)
Reactive oxygen species generated within the body can oxidize not only DNA, which carries genetic information, but also its building blocks—nucleotides. The human enzyme MTH1, which is associated with cancer, functions to eliminate oxidized nucleotides within cells. It is also believed to be overexpressed in cancer cells, helping protect them from oxidative stress. Since the discovery that MTH1 inhibitors can suppress cancer cell proliferation, MTH1 has attracted attention as a novel target for anticancer drugs with a unique mechanism of action.
In this study, researchers used X-ray crystallography and neutron crystallography with “iBIX,” the IBARAKI Biological Crystal Diffractometer at MLF, to determine the structure of MTH1’s substrate including hydrogen atoms and inhibitor binding sites with high precision. By visualizing the enzymatic reaction process of MTH1, the team was able to clarify the reaction mechanism—something that had remained a topic of debate for many years using conventional research methods.
The high-resolution structural data of MTH1 obtained in this study is expected to contribute to the improvement of existing inhibitors and the design of new ones, paving the way for the development of next-generation anticancer drugs.
For more details (available in Japanese only), please visit the J-PARC website:
https://j-parc.jp/c/press-release/2025/07/15001586.html
■Hello Science: “Friend or Foe!? Interaction Between Beam and Gas” (June 27)
Dr. YAMADA Ippei from the Accelerator Division gave a talk on the interaction between beams and gas inside accelerators.
At J-PARC, the proton beam travels up to approximately 800,000 km through three accelerators before reaching the experimental facilities. However, if gas is present along the beam path, its molecules interfere with the beam’s progress.
“If it’s impossible to eliminate gas molecules even with our best efforts to create a vacuum, could we instead make use of them?”
Dr. YAMADA developed a monitor that introduces a thin sheet of gas into the vacuum chamber, enabling the measurement of the beam’s cross-sectional shape. The effectiveness of this method was demonstrated. Building on this success, researchers examined the impact of the monitor on the beam as it passes through. They found that the interaction with gas molecules suppresses beam spread, due to their electromagnetic repulsive force, enabling the production of higher-quality and higher-intensity beams.
With the right ideas, gas molecules—once considered adversaries—can become powerful allies for high-intensity accelerators, contributing to the further advancement of J-PARC.
■Exhibited at Eco-Fes Hitachi 2025 (June 28, Hitachi Civic Center and other venues)
Eco-Fes Hitachi is one of the most prominent environmental events in Ibaraki Prefecture, organized by the City of Hitachi. The event features a variety of hands-on booths offering activities such as crafts and experiments using familiar materials. J-PARC participates in the event every year.
As in previous years, the Cryogenics Section featured live demonstrations of a magnetic slide and a superconducting coaster, attracting 337 visitors to the booth. Visitors of all ages were fascinated by the magnetic slide, which demonstrated how the falling speed of a magnet changes depending on the type of metal and its temperature. The superconducting coaster, where a material cooled to nearly −200°C glides effortlessly along magnetic rails, also elicited wide-eyed amazement and excitement.
■Participation in the “Energy Workshop” (July 12, AEON TOKAI)
As part of Tokai Village’s 70th anniversary celebration, an event titled “Let’s Create the Future of Light! Energy Workshop” was held. The event featured booths where visitors could learn about energy through engaging activities, including hands-on experiments with electricity generation and virtual tours utilizing VR technology.
The J-PARC Center participated with a “frustration maze” modeled after its three accelerators, offering children a fun way to learn about J-PARC. At first, few participants were able to complete the maze, but one fourth-grade boy kept trying and finally made it through. He looked very proud and happy. In addition, a scale model of J-PARC was on display, and information about the upcoming open house was also available at the booth. Many expressed their excitement, saying things like, “I’m looking forward to visiting the facility in August.”
■J-PARC Outreach Lecture
Yunago Elementary School, Hitachi City (July 8)
Under the theme “What is the Universe Made of? – Light,” Dr. MIHARA Satoshi from the Particle and Nuclear Physics Division delivered a lecture.
This outreach class was organized at the request of the Hitachi Civic Center as a parent-child learning session. A total of 34 students and their guardians participated, exploring the concept of light through waves and quanta. They also enjoyed making kaleidoscopes to apply the properties of light.
Participants shared enthusiastic feedback stating, “It was fun!” and “It was interesting!” Some remarked, “I learned that both quanta and light behave like waves,” and “Why does combining blue, red, and green light create white?”
■Muographic Investigation of Ancient Burial Mounds in Tokai: Visiting the Torazuka Kofun and the Jugoro Hole Cave Tombs (June 29, Hitachinaka City)
Under unusually clear skies for the rainy season, a total of 44 participants took part in the second session of the Muographic Investigation of Ancient Burial Mounds in Tokai for 2025, including 20 elementary and junior high school students, along with their parents and staff. The objectives of this session included observing the Torazuka Kofun—a keyhole-shaped burial mound resembling the Funatsuka No. 2 Kofun—gaining insight into the stone chamber currently being explored through muography, and visiting the nationally designated historic site, the Jugoro Hole Cave Tombs.
The visit began with a talk by Professor TANAKA Yutaka from the College of Humanities and Social Sciences at Ibaraki University, who explained the similarities between the Torazuka Kofun and the Funatsuka No. 2 Kofun, as well as the structure of their stone chambers. At the Jugoro Hole Cave Tombs, participants learned that the site is one of the most representative horizontal cave tomb clusters in eastern Japan. These insights heightened expectations for the muography results, especially given the predicted location of the stone chamber in the Funatsuka No. 2 Kofun and its resemblance to that of the Torazuka Kofun. The group then moved to the Hitachinaka Buried Cultural Property Research Center, where Mr. INADA Kenichi gave a presentation on the murals and excavated artifacts, standing before a replica of the Torazuka Kofun’s mural paintings.
The many questions directed at Professor TANAKA and Mr. INADA reflected the participants’ strong interest in the Torazuka Kofun and the Jugoro Hole Cave Tombs.
■Notice: J-PARC & Nuclear Science Research Institute Open House 2025 (August 23)
On Saturday, August 23, J-PARC and the Nuclear Science Research Institute will jointly host their Open House 2025 under the theme “Exploring Tomorrow’s World Through Science.”
Visitors will have a rare opportunity to tour experimental facilities and accelerators that are usually closed to the public (some tours require a reservation). The event will also feature a science café, hands-on experiments, craft workshops, and food trucks .
We warmly invite you to join us!
For more details, please visit the J-PARC & Nuclear Science Research Institute Open House 2025 Special Website:
https://j-parc.jp/OPEN_HOUSE/2025/index_e2025.html
■J-PARC Sanpo-michi Vol. 60
Cicadas and Grasshoppers
J-PARC is a research facility filled with the sound of nature. In the early morning, we hear birdsong; when the sea is rough, we hear the sound of
the waves. These natural sounds encourage and soothe us—and at times, inspire a sense of reverence—as we go about our daily tasks.
As I write this column on July 22, something unusual is occurring among the singing insects on the J-PARC premises. Cicadas, which usually begin to sing impatiently before the end of the rainy season, have yet to make themselves heard. Instead, the grasshoppers near the buildings are already chirping energetically.
There are various theories as to why the cicadas aren’t singing. Some suggest that this year’s low rainfall left the soil dry, and the sudden temperature rise caused the cicadas to miss their timing to emerge from underground. Others say that cicadas don’t sing when the weather is extremely hot.
But why are grasshoppers able to sing in this heat? Perhaps the grassy areas where they live are cooler than the sun-exposed tree trunks where cicadas perch. Unlike cicadas, which spend their larval stage underground, grasshoppers live above ground even as juveniles. Such a lifestyle may mean they were less affected by the dry rainy season and were able to molt and become adults earlier than usual.
At J-PARC, we generate large quantities of secondary particles and use them to probe materials or study the particles themselves, to understand messages from the natural world. At the same time, we also hope to listen closely to the messages that nature delivers around us.
