J-PARC News December 2020 (Issue #188)
■ Discovery of New Method to Control Order Pattern of Atomic Vacancies (November 24, Press Release)
The function of oxides (ceramics) used as functional materials everywhere around us is determined by order patterns (crystal structure) of atoms of metal and oxygen in crystal. However, at high temperatures above 1000 ℃, where synthesis usually occurs, it has not been possible to produce oxides having specific crystal structure. Professor Hiroshi Kageyama of Kyoto University iCeMS (Cell-Material Sciences) and his colleagues tried to control the oxide crystal structure using stress of a thin film. When oxide thin films of strontium and vanadium are grown on a substrate, the thin films receive various stress depending on the lattice size of the substrate. In this study, Professor Kageyama’s team prepared samples under various stress at 600 °C (lower than the conventional level) to show topochemical reaction, such as part of oxygen being replaced with nitrogen or escaping and becoming vacant. They found that the position and period of oxygen vacancies change depending on when there is no stress, when stress is applied in the tensile direction, and when compressive stress is applied. This result was obtained from the crystal structure of oxynitride, which is starting material produced by neutron diffraction experiments using iMATERIA and NOVA of the J-PARC Materials and Life Science Experimental Facility (MLF) along with X-ray diffraction. In particular, neutrons are sensitive probes to oxygen and nitrogen sequences with deficits (of atoms) and have greatly contributed to the structural evaluation. By combining the results of this study with machine learning and information technology, the situation of inorganic substance synthesis, which was thought to be impossible to design, will change completely. Moreover, on-demand function development will become possible, and as a result, development of materials with functions such as magnetism, ion conduction, superconductivity, and catalysts will become possible.
■ Successful Measurement of Muon Beam Stopping Distribution Using Optical Imaging: Promising Technological Development for Beam Accuracy Diagnosis and Future Research and Applications (November 30, Press Release)
High-intensity muon beams generated by accelerators are used for a variety of sciences, such as non-destructive element analysis, in-situ microscopic study of magnetism, and simulating the hydrogen behavior in materials. In such studies, it is important to know the energy and spatial distribution of muons in the beam. Dr. Seiichi Yamamoto of Nagoya University and his colleagues attempted to obtain the information of muon stopping distribution from the luminescence in water associated with the muon beam injection at J-PARC. When a positively charged muon beam is injected into the water, the muon decays at the stopping position and emits positron with relatively high energy. The positron emits photons (Cherenkov light) as they pass through the water. This time, they successfully conducted an optical imaging experiment with a high-sensitivity CCD camera. Also, it was confirmed that the higher energy muon beam stops deeper inside, and the light distribution reflects the stopping position. Moreover, it was confirmed that the energy and spatial distribution of muon beams could be obtained from analyzing these optical images. The device combined with water and a CCD camera is relatively easy to make, and will likely be applied to beam diagnosis in various studies using muon beams in the future.
■ Measurement Systems Research Meeting 2020 -Current Situation and Future Prospects for Utilization of Measurement Systems in Experiments with High-Intensity and High-Brightness Beams- (November 26 – 27, KEK Tokai Campus/J-PARC)
The objective of this research meeting is to discuss the high-intensity and high-brightness beam uses from the perspective of measurement systems. It is a common issue in various fields such as elementary particle nuclei, materials and life science and accelerator science for their experiments using accelerators. This time, the J-PARC Center hosted the meeting with a theme of future developments and issues in various research fields based on the achievements made in three years of R&D mainly in the J-PARC experiments. The meeting was conducted in-person as well as remotely to prevent the spread of coronavirus. In addition, each speaker reported on not only the results but also the technical issues and future development, and the participants were able to discuss topics that are not typically discussed at conferences.
■ J-PARC Safety Audit (December 7, J-PARC)
The J-PARC Center Safety Audit in FY2020 was conducted by two external audit committee members specializing in safety engineering and radiation safety. In the audit, Dr. Tetsuro Ishii, Deputy Director in charge of the Safety, reported on the current situation of J-PARC, the outline of all safety activities at J-PARC, and the actions made in response to the suggestions given by the committee members in the safety audit of 2019. Following that, an on-site inspection of the works at the MLF facility was conducted. Afterwards, the person in charge of each facility explained the safety management activities, and were interviewed by the audit committee members. The audit committee members made recommendations on safety measures with a consideration of the development of J-PARC over the next 10 years.
■ J-PARC Hello Science “Where Does Weight of Things Come From?” (November 27, Tokai-mura Industry and Information Plaza “iVil”)
This time, Dr. Kazuya Aoki of the Particle and Nuclear Physics Division gave a lecture on the origin of mass and related research at J-PARC. Most of matter’s mass comes from protons and neutrons. Protons and neutrons are made of three quarks, but they are heavier than the sum of the three quark masses! Dr. Aoki introduced the E16 experiment, which is about to begin at the J-PARC Hadron Experimental Facility to study this mystery. It is theoretically suggested that mass changes with changes in the environment, such as temperature and density. In fact, data obtained in a previous experiment conducted at KEK Tsukuba Campus, can be interpreted that the mass of the meson called φ (phi) decreases in the nucleus. The E16 experiment will collect an order of magnitude more events, allowing more detailed and systematic study of the mass shift of mesons. Participants were very interested in matter’s mass and asked many questions.
■ J-PARC Hello Science at Tokai Village Children’s Science Club (November 9, 16, 30, Tokai-mura Nakamaru Community Center)
Tokai Village Children’s Science Club of the second half of FY 2020 was held in November. Ms. Naoko Inoue of the J-PARC Center’s public relations, Dr. Satoshi Mihara of the Particle and Nuclear Physics Division, Dr. Yasuyuki Sugiyama and Dr. Tomohiro Takayanagi of the Accelerator Division instructed experiments. Seven 5th and 6th grade pupils from elementary schools in the village participated. Titles of the experiments they carried out were: (1) Mysterious Light Experiment, (2) Static Electricity with a “snap”, and (3) Electricity and Magnets are good friends. The pupils learned the nature of waves in the light experiment, the difference in charging by rubbing various objects in the static electricity experiment, and force generated by the electrical current flowing through a coil and magnets (magnetic field lines) in the electricity and magnet experiment. In addition, the researchers explained how these experiments are connected with J-PARC research work. Some children commented that they wanted to learn more about J-PARC.
■ J-PARC Photo Contest 2020
The J-PARC Photo Contest, which is held every autumn, was held this year for the 7th time. We had a total of 28 art works submitted by 16 people who are involved with the operation of J-PARC and J-PARC users. One grand prize, two outstanding prizes, and seven runners-up were selected. Two external judges also helped to select them this time. The award ceremony was held on November 12, and the J-PARC Center Director Naohito Saito handed each award winner a certificate and a gift. Dr. Taihei Adachi of the Muon Section won the Best Photo for his work, “Hanagata.” The photo was taken through a blue protective film. A scene made by the light reflecting in a flower-shaped beam duct installed in the muon beamline at MLF. The winning works will be used in various public relations materials.
■ J-PARC Hello Science at Tama Rokuto Science Center “Let’s Make a Top That Leans While Spinning!” -The World of Accelerator Research Seen from Top’s Rotation- (November 29, Nishitokyo City)
On November 29, the J-PARC Center introduced the world of J-PARC’s advanced research through craft-making and experiments themed on tops at the scientific experiment event of Tama Rokuto Science Center*. We called out to invite 12 participants in 5th and 6th grades and up for each morning and afternoon session, and the applications exceeded the capacity. From the J-PARC Center, two researchers, Dr. Masashi Otani of the Accelerator Division and Dr. Koichiro Shimomura, the Deputy Head of the Materials and Life Science Division, who are involved in muon research, and Ms. Minako Abe leader and Ms. Naoko Inoue in public relations gave lecturers. All the participants enthusiastically worked on making and experimenting. They learned about special rotation, i.e. spin of elementary particles from the experiments of electric current and magnets using compasses and by making tops with different positions of the fulcrum and center of gravity. During the questions and answers session afterwards, adults in both morning and afternoon sessions asked enthusiastic questions, such as “What kind of university or field of study should my child go to in order to do research like you?” This event suggested that many have a high level of interest in electricity, muons, and precession, and also that we were able to captivate their interest in J-PARC.
* Tama Rokuto Science Center, which is in Nishi-Tokyo City, is operated by four surrounding cities, and has a planetarium certified the best in the world. It is an experience-based museum where you can observe, experiment, and create.
■Sanpo-michi #5 -Bird Watering Hole-
In December, evergreen leaves fall and sunlight directly hits the ground. There is a bird watering hole, which was built by pulling water in a corner of the forest that was left untouched during the construction of J-PARC. The water surface was sparkling and fallen leaves were accumulating at the bottom. The area was so bright, and we who were taking pictures had no place to hide, but we saw a Yamagara, Varied Tit had perched on a nearby branch and quickly flew down onto the edge of the watering hole.
During the summer months, this area is an oasis for many animals. It was lively with creatures: insects coming for water, frogs eyeing the insects, and snakes eyeing the frogs, and so on. But, now those animals are hibernating, and birds are dominating the area.
Yamagara is tame and has a high learning ability. They probably know that it is safe now that summer has passed. Where the J-PARC research building and the Materials and Life Science Experiment Building rise and the transformers of the 50GeV substation roar, Yamagara is taking a bath and calling to friends.
Due to the raging coronavirus pandemic, J-PARC’s facilities are closed to the public and our public outreach activities and facility tours are all cancelled. It may seem that public relations have entered hibernation. However, like what is happening at this small watering hole, we are actively disseminating information online and continuing to carry out our projects while making our utmost efforts to mitigate the infectious disease.
We look forward to seeing you in person again next year when the infection of coronavirus subsides.
