J-PARC News February 2021 (Issue #190)

■Discovering the World's Best-Class Oxide-ion Conductor Free of Rare-Earths: Acceleration of Fuel Cell, Sensor, and Electronic Material Development (January 25, Press Release)

There are high expectations for fuel cell development as one of the tools to mitigate the climate change problem, an urgent issue for our society. Oxide-ion conductors with high conductivity have the potential to accelerate the development of solid oxide fuel cells. Professor Masatomo Yashima of Tokyo Institute of Technology and his colleagues have discovered a new oxide-ion conductor, Ba7Nb3.9Mo1.1O20.05, which exhibits the world's highest-level oxide-ion conductivity. It has a hexagonal perovskite-related structure that is extremely rare in oxide-ion conductors. While many conventional high oxide-ion conductors contain rare earths, bismuth, lead, or titanium, the materials found do not contain these elements and are excellent in stability, safety, and resource security. In order to investigate the mechanism of the high oxide-ion conductivity of this material, crystal structure analysis by a neutron diffraction experiment using super high resolution powder diffractometer at J-PARC, SuperHRPD, was used at high temperature where oxide-ion conductivity is elevated. As a result, they discovered that a part of the site O1, where oxygen should originally be located, is vacant on the so-called (001) plane in the crystal shown in the figure. Furthermore, by using an analysis method called the "maximum entropy method," the research group visualized the conduction path of oxide-ions connecting O1 to the vacant position (O5 interstitial oxygen), not the original location of oxygen. The result showed that interstitial oxygen is essential for oxide-ion conduction. There is a prospect of scientific development of ionic conductors of hexagonal perovskite-related oxides and advancement in the development of solid oxide fuel cells, oxygen separation membranes, catalysts, gas sensors, and electronic materials.

Please refer to the URL below for further details.


■Explore New Species of Neutrinos!: Data Acquisition of JSNS2 Experiment at J-PARC Has Begun (February 9, Press Release)

・ Online press briefing

On February 9, the J-PARC Center held an online press briefing at the J-PARC Research Building in conjunction with the following press release. Eighteen reporters from 10 companies participated, and Associate Professor Takasumi Maruyama, the project leader of the experiment in the Neutrino Section of the Particle & Nuclear Physics Division, explained principles and characteristics of the experiment, which was followed by a question and answer session. A facility tour using photos and videos of the experimental equipment was also held. After the briefing, multiple interviewers asked questions individually with Zoom's feature, Breakout Rooms, and J-PARC Center Director Naohito Saito, Osaka University Assistant Professor Yorihito Sugaya, and JAEA Principal Scientist Shoichi Hasegawa also joined in. Many questions asked at the press conference implied a high level of interest in the new experiment of sterile neutrino observation.


・ Summary of the Press Briefing

It is thought that there are only three types of neutrinos that feel weak force and gravity in the standard model of elementary particle physics, but in 1990, an experiment conducted at the Los Alamos Institute in the United States had shown a possibility that there is a sterile neutrino that feels only gravity. No definitive results proving its existence have been obtained to date, and various experiments around the world are in operation or are scheduled to start to settle this matter. Recently, the JSNS2 experiment* started at J-PARC. This experiment will investigate the existence of muon anti-neutrino to electron anti-neutrino oscillation at a short distance of 24m. Neutrino oscillation, neutrinos changing from muon anti-neutrinos to electron anti-neutrinos, rarely occurs with long distances such as in the T2K experiment (flying 295 km from J-PARC to Kamioka). However, if sterile neutrinos exist, the oscillation can occur in a short distance, from muon anti-neutrinos via sterile neutrinos. At the mercury target of the J-PARC Center for Materials and Life Science Experimental Facility (MLF), muon anti-neutrinos are produced at the same time of the production of a large amount of neutrons for Material and Life science. Therefore, a 50ton liquid scintillator detector was installed 24m from the mercury target. The oscillation, changing from muon anti-neutrino to electron anti-neutrino while the muon anti-neutrino travels this distance, is captured by signals of the detector. "If this oscillation exists, we will be able to see it from data accumulated over the next three years or so," said Maruyama, the principal investigator. Sterile neutrinos are new particles beyond the standard model and are considered one of the candidates for dark matter. If discovered, it will have a great impact on particle physics. Stay tuned for the progress of this experiment.

* JSNS2 experiment: Abbreviation for J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source. This is an international collaborative experiment conducted by 65 researchers from four collaborating countries: the United States, the United Kingdom, South Korea, and Japan.


■J-PARC Advisory Committees held online (January 22 – February 22)

From January 22 to February 22, the J-PARC Center held four advisory committees* online. The purpose of these committees is to receive advice and suggestions from experts in and out of Japan on the status of J-PARC accelerators and experimental facilities, research progress, and future plans, and other topics. At the beginning of each committee, Director Naohito Saito explained the current status of J-PARC and requested discussion topics for the committee, followed by the facility and equipment managers' report on the current status and future plans of each facility.  In return, the committee gave them advice regarding the reports. The summary of the committees will be reported to and discussed by the J-PARC International Advisory Committee (IAC), which is scheduled in early March.

* Transmutation Experimental Facility (T-TAC), Accelerator Facility (A-TAC), Muon Experimental Facility (MAC), and Neutron Experimental Facility (NAC)


■The 3rd "FC-Cubic Open Symposium" streamed on YouTube (February 2)

FC-Cubic*1 has been conducting research on a shared fundamental technology research for fuel cells and its system development with an aim to realize a hydrogen-based society which leads to building a low-carbon society, diversifying energy, and improving the international competitiveness of industry. On February 2, under the co-sponsorship of NEDO*2, the FC-Cubic Open Symposium was held online from the Tokyo International Exchange Center. J-PARC, which has the MLF that neutrons (superior in observing the behavior of hydrogen) are used, began participating in NEDO's fuel cell research and development project together with FC-Cubic and others this fiscal year. At this symposium, J-PARC and neutrons were the main topic, Director Naohito Saito explained an overview of the entire J-PARC, and Toshiya Otomo, division head of the Materials & Life Science Division explained the effectiveness of neutron beam utilization. Takenao Shinohara, principal researcher of the Neutron Science Section, introduced visualization analysis technology with neutron imaging, and Jun-ichi Suzuki, principal researcher of CROSS*3, introduced structural analysis of fuel cell materials by small-angle neutron scattering. The explanations included their experimental results. In addition, a J-PARC facility tour, presentation of research, and videos were given, as well as online discussions. The total number of viewers of the symposium exceeded 1,800, implying a high level of interest in this theme.

*1 Technology Research Association consisting of 20 domestic companies such as Toyota Motor Corporation, as well as one administrative corporation, and six universities

*2 New Energy and Industrial Technology Development Organization

*3 Registered institutions for facilities use promotion and Comprehensive Research Organization for Science and Society (CROSS) under the Act on the Promotion of Public Utilization of the Specific Advanced Large Research Facilities

■J-PARC Hello Science/Science Experiment Video Class "Can the World's Smallest Top Lead Nobel Prize-class Discovery?!" (February 4, Tokai Village Shirakata Elementary School Science Club)

On February 4, during corona situation, a science experiment class was held using video and craft kits produced by the J-PARC Center for the first time at the Science Club of Shirakata Elementary School. At J-PARC, research using precession of elementary particle muon, and experiments to investigate it in detail has been conducted. In this class, students used tops that move like elementary particles, and Mr. Yuga Nakazawa of Ibaraki University, who is involved in the research at J-PARC, served as a lecturer in the video. The students watched the video explaining about J-PARC and the precession, observed the movement of gyroscopes, and observed each rotation of tops in the different sizes that they made. In the thank-you video from the school, the students were surprised at the tops that continued to rotate even with a large inclination, and enjoyed studying with the teaching materials.


■The 31st J-PARC PAC held remotely (January 20 – 22)

For three days from January 20, the Program Advisory Committee (PAC) for Nuclear and Particle Physics Experiments at the J-PARC was held online using a web conference system. The committee consisted of 16 members (including 9 from abroad), and about 100 participants joined the first overviewing session. It began with a report by the J-PARC Center Director Naohito Saito on the current status of J-PARC. Yoichi Sato of the Accelerator Section 6 explained the accelerators, and Hitoshi Takahashi of the Hadron Section explained the current status and future prospects for the Hadron Experimental Facility. Katsuo Tokushuku, the director of the KEK Institute of Particle and Nuclear Studies, explained the mandates of this meeting. There were presentations by one new proposal and the two proposals having been deferred in the last PAC meeting, followed by eight reports on the progress and future plans in the experiments being underway at the Hadron Experimental Facility and Neutrino Experimental Facility. The recommendations from the committee to the proposals and the reports will be summarized to the minutes and be available soon.

■Sanpo-michi # 7 Public Relations Staff during the Coronavirus Pandemic

The J-PARC public relations staff has been working through a process of trial and error to conduct in-person public outreach activities and tours. We are delighted to see an audience listen enthusiastically to our story, and our explanations tend to become lively without realizing it. If not, we devise a different way of explaining or take the plunge and change the topic. The time we spend with the public is not a one-sided interaction. It is a valuable opportunity for us to learn from them.

Now it has become difficult to meet face-to-face due to the Coronavirus Pandemic. J-PARC makes numerous articles and videos to introduce the latest activities and distributes them online for the public. Recently, for the students of the Shirakata Elementary School Science Club, we sent teaching materials with craft kits and a lecture video to explain precession, which is closely related to J-PARC research. In return, the school sent us a video of the students conducting the experiments along with a thank-you message. Even if we couldn't meet in person, we were very happy and encouraged by watching the video.

Although there is a limit to conducting public relations activities online, it also gives us advantages such as being able to connect with many people regardless of time and location.

Our public relations office is a two-way bridge that connects the public and the researchers. We hope that our public outreach activities will promote mutual understanding not only with the public and J-PARC but also among the entire science and technology.