J-PARC News June 2024 (Issue #230)
■The World’s Most Powerful Pulsed Neuron Source at J-PARC MLF Achieved Target Performance
-Realizing Long-Term Operation at the World's Highest Intensity- (May 31st)
The pulsed neutron source at Materials and Life Science Experimental Facility (MLF) in J-PARC has achieved its long-term operational goal of "continuous operation with a proton beam power equivalent to 1000 KW" for over 50 days starting from April 8, 2024. This is the result of gradually increasing the power through improvements and verification of various equipment including the mercury target. While countries around the world such as the United States, EU countries, and China are competing to develop high-power and high-performance pulse neutron sources, the neuron intensity per pulse has reached more than twice that of the SNS in the United States which is the next highest intensity pulsed neutron source in the world.
Experiments using pulse neutrons are a very effective means for conducting advanced research in materials science and life science. In the future, we will continue to accumulate stable operational performance and advance the sophistication of facilities, including extending their lifespan, to contribute to the creation of more research results,
Furthermore, the muon source, installed upstream of the MLF pulsed neutron source, has also achieved the world’s highest intensity and long-term operation simultaneously.
■Press study session held (June 5)
World's first cooling and acceleration of muon
- The first muon accelerator finally coming to a reality. -
In the Materials and Life Science Experimental Facility (MLF) at J-PARC, a research group has succeeded for the first time in the world in accelerating cooled elementary muons to about 4% of the speed of light. The realization of unprecedented muon acceleration makes 2024 the "First Year of Muon Acceleration".
The positive muons produced at MLF which is around 30% of the speed of light was decelerated and cooled to about 0.002% of the speed of light with alignment of their direction. By injecting them into a radio-frequency acceleration cavity, researchers have successfully accelerated the muons back to approximately 4% of the speed of light. This is big step towards starting ultra-precise test of the standard model of particle physics. Furthermore, by using accelerated muons, completely new imaging such as muon microscopy and interdisciplinary research can also be expected.
To make this achievement understood by many people, we held a press study session. On the day, there were 9 participants from 8 companies and 12 people from 11 companies including online. After explaining J-PARC as a whole and muons, we conducted a tour of the S2, HI, and H2 areas of the MLF. The study session was a success, as hands of questions went up one after another, such as the final goal of the muon acceleration energy, the current situation in other countries, and so on.
■Revealing the secret of silica enhancing tire performance with neutron and hydrogen spins
~ Contribute to the high functionality of composite materials with a new technology to observe “buried interfaces” ~ (May 16th)
Tires for automobiles achieve a balance between grip performance and fuel efficiency by adding silica nanoparticles to rubber materials. Although coupling agents are added to strengthen this bond, there was no method to confirm how they function.
The research group has developed a new neutron and hydrogen spin-controlled spin-contrast-variation neutron reflectometry using BL17 SHARAKU, Polarized Neutron Reflectometer at MLF, which enables the observation of monolayer of coupling agent formed at the interface between rubber and silica. The structure and composition of the 2nm thick coupling agent layer generated at the interface have been determined, and it has been revealed that the strength of the bond between the rubber material and silica varies depending on the addition method.
It is expected that in the future tires with significantly improved wear resistance will be developed because of this achievement. Furthermore, the method developed this time can determine the interface state in various composite materials, so it is expected to contribute to material development in various fields.
■Is Ruthenium Oxide really the Altermagnet?
-Challenging the 'Devil's Proof' with elementary particle muons and first-principles calculations- (May 20th)
Metallic magnetic materials are broadly classified into two types: ferromagnets where atomic spins are all aligned in the same direction, and antiferromagnets where spins are aligned in opposite directions to each other. However, recently the existence of a new type of magnetic material called ‘altermagnet', which shares some properties of ferromagnets within antiferromagnets, has been theoretically predicted. Ruthenium Oxide (RuO2) has been attracting attention as a candidate for such a third magnetic material.
Antiferromagnetic materials, which are not attracted to magnets, are indistinguishable from non-magnetic metals (referred to as paramagnetic materials) in appearance. Therefore, the research group conducted μSR measurements using the ARTEMIS/S1 at MLF to investigate the presence or absence of antiferromagnetism, which is a prerequisite for altermagnetism in RuO2. As a result, it was found that RuO2 is very close to being an ordinary paramagnetic material.
Antiferromagnetic materials exhibiting altermagnetism are expected to be next- generation electrical and magnetic device materials with favorable properties such as being unaffected by surrounding magnetic fields. Aside from the "devil’s proof" that there is no altermagnetism in RuO2, it may provide an opportunity for a reexamination from a basic understanding of its electronic property. On the other hand, it is also suggested that the magnetic properties of RuO2 can be controlled by impurities and defects, which could provide new guidelines for future material development.
■J-PARC Safety Day (May 30th)
J-PARC center has held "J-PARC Safety Day" every year around May 23, the day of the incident since the radioactive material leakage incident at the Hadron Experimental Facility in 2013. This year, 352 people participated in the event at the real venue and online.
In the morning, there were reports from representatives of each division and section regarding case studies on fire prevention as part of the safety information exchange meeting. In the afternoon, under the title of ‘the Workshop for Fostering a Safety Culture', we first presented the Safety Contribution Award and the Best Practices Award. Next, there was a lecture by Dr. FUKUWA Nobuo, Honorary Professor of Nagoya University and Director of the Aichi-Nagoya Resilience Co-creation Center, titled "Preparing for Large-Scale Earthquakes with Wisdom from the Past’.
It was pointed out that Japan's seismic design standards are uniform nationwide regardless of the ground conditions, the vulnerability of major cities and the lack of places to learn about the history of disasters. It was emphasized the need for the country and individuals to rethink their response to earthquakes together. Following that, a documentary video titled "The Radioactive
Material Leak Incident at J-PARC: How Society Viewed the Incident” was screened, and the event concluded.
J-PARC will continue to hold this event every year not to let the incident in 2013 fade away. The entire staff shall continue to promote research activities while always placing the highest priority on safety.
■Hello Science "J-PARC Accelerator Beam Power Increase" (May 31st）
Dr. IGARASHI Susumu of the Accelerator Division introduced the accelerator called Main Ring Synchrotron (MR) at J-PARC, which is now more powerful.
The beam power of the MR has been increased since its operation started in 2008 and exceeded the initial target of 750 kW last year. Currently, 220 trillion protons with a kinetic energy of 30 GeV are supplied to the neutrino experimental facility in 1.3 second cycles. This is the result of efforts to shorten the acceleration period by enhancing the electromagnet power supplies and high-frequency acceleration cavities, and by making various other technological improvements.
The success of particle and nuclear experiments depends greatly on the number of protons supplied to the experimental facility. If the number of protons accelerated by the accelerator can be increased and the beam can be emitted with a shorter period, the beam power can be increased, and more sensitive experiments can be performed.
The research group members plan to continue to enhance the accelerator to further shorten the acceleration cycle. They also plan to suppress the growth of the beam size due to repulsive forces between protons by adjusting the beam tuning parameters, increase the number of protons supplied, and almost double the beam power to 1.3 MW in four years.
■MR Achieved User Operation with Beam Power that Broke Previous Record.
Commemorative Photographs Were Taken (June 21st)
MR has achieved a record-breaking beam power in user operation. Stable operation was achieved with a beam power of 800 kW for fast extraction (FX) to the Neutrino Experimental Facility and 80 kW for slow extraction (SX) to the Hadron Experimental Facility. To celebrate this achievement, all concerned parties gathered in the Central Control Building and photos with a banner were taken to mark the occasion.
■J-PARC Lectures at Gunma National College of Technology and Tsuyama National College of Technology (June 17th and 18th)
The theme of the lecture was "Accelerator Mechanisms to See the Microscopic World: Muon Acceleration Technology to See Through from Elementary Particle Phenomena to Large Structures," and about 20 to 25 students respectively attended.
The lecturer was Dr. OHTANI Masashi of Accelerator Section Ⅶ, who introduced the mechanism of accelerators, their medical and industrial applications, and research on physical properties and elementary particles using muons. In the questionnaire after the lecture, some of the participants commented, "The explanations were easy to understand and enjoyable to listen to, based on basic knowledge." and “I would like to know more about the accelerators and what we can get from them”. The lecture was a good opportunity to arouse interests in subatomic particles and accelerators.
■"The Cosmic Ray Muon Project to See Through Burial Mounds" Has Started Activities (June 23rd, at History and the future community house)
The project started last April. The first meeting of its second phase was held on June 23rd, and 18 children out of 24 members gathered at History and the future community house. At the opening ceremony, they listened to a lecture on Muon by Dr. SHIMOMURA of Materials and Life Science Division, and a speech of Mr. YAMADA, the Mayor of Tokai Village. After that they made cloud chambers under the guidance of Dr. FUJII of Particle and Nuclear Physics Division. A cup was covered with a black cloth, filled with alcohol, and a radiation source was placed in the center. The alpha rays emitted from the source looked like contrails when they cooled it down with dry ice.
This project is scheduled to be held once a month. This year, children will continue their activities with the aim to start the "Detector for History and Future" made last year to challenge the mysteries of the burial mounds and to build another one.
■[Summer Special Exhibition] Science x Tokai-Village x J-PARC, - Our World is Made Up of Particles - (History and the future community house: July 20th to September 29th)
Tokai Village History and the future community house is going to be the Particle World! There will be lots of fun events such as a riddle-solving mission, "Tokai Science Lab," a science experiment class, and workshops you can play anytime! Also, the special exhibition "The Real Faces of Scientists" will be held at the same time. Please come and join us.
■J-PARC Sanpomichi ㊼ Tour of MLF
When I take visitors to the experimental hall of MLF, they are often amazed. From the catwalk in the building, which can hold two jumbo jets, they can see the neutron beamlines radiating out from the huge dark blue cylinder that houses the neutron source, and the complicated muon beamlines branching off behind it.
As mentioned in this J-PARC News, the two major news at MLF are the achievement of the target performance of the world's most powerful pulsed neutron source and the successful acceleration of particle muons. You might think that the experimental halls of MLF would now be buzzing with researchers and engineers, but not so much, since most of them are watching the results of their experiments live from their cabins, huts near the beamline or their own office rooms, while MLF is in operation. Of course, MLF staff members are busier than ever as more detailed and unknown data is coming in.
J-PARC will be shut down for maintenance during the summer season starting in July. You might see many staff members working in the experimental hall to replace or adjust samples and measurement instruments in the meantime.
