J-PARC News November 2020 (Issue #187)

■ The 2020 (the 66th) Nishina Memorial Prize Awarded to Dr. Kazuma Nakazawa, Senior Professor at Gifu University, Project Leader at J-PARC E07 (November 9)

The Nishina Memorial Prize was awarded to Senior Professor Kazuma Nakazawa of Faculty of Education, and Graduate School of Engineering, Gifu University, Tokai National Higher Education and Research System for "Study of Double Strangeness Nuclei Using Nuclear Emulsion Plates." He utilized J-PARC and the KEK Proton Synchrotron (KEK-PS) for this study. This award is given to researchers who have made outstanding research achievements in the field of atomic and sub-atomic physics and its applications in Japan in commemoration of the achievements made by the late Dr. Yoshio Nishina. In order to understand the existence of a wide variety of atomic nuclei, it is essential to understand the nuclear force that acts between the protons and neutrons (nucleons) that make up the atomic nucleus. Therefore, in the research, Xi-particles containing two strange quarks produced using accelerator beam were injected into a nuclear emulsion plate. Then, double strangeness nuclei containing two strange quarks (double-Lambda nuclei or Xi nuclei) generated in the nuclear emulsion were searched for to study the nuclear force between Lambda particles, Xi-particle-nucleon that act inside the double strangeness nuclei. Because beam intensity at J-PARC are much higher than that at KEK-PS, it has become possible to produce significantly more double strangeness nuclei. With this benefit, Professor Nakazawa and his colleagues have developed methods to efficiently look for double strangeness nuclei using an optical microscope scanning the trajectories of particles recorded in the emulsion plate. As a result, they discovered several new types of double strangeness nuclei and gained new insights into the nuclear forces between their constituent particles, namely Lambda-Lambda and Xi-nucleon. The results of further analysis are expected in the future.


■ Two Groups Receive Technology Award and Two People Receive President's Choice Award from J-PARC Center by the 20th Annual Meeting of Japanese Society of Neutron Science (November 9)

[Technology Award]

At the 20th Annual Meeting of the Japan Neutron Science Society held online from November 9 to 11, two groups from the J-PARC Center received the Technology Award. This award is given to individuals or groups who have made significant contributions to the technological development of neutron science. The group of Dr. Shin-ichiro Meigo, Dr. Motoki Ooi, Dr. Hiroshi Fujimori, and Dr. Shinichi Sakamoto (former member of the J-PARC Center) were awarded for the achievements of "Proton Beam Control Technology Development for High-intensity Pulsed Neutron Generation." The other award was given to the group of Mr. Shuki Torii, Dr. Kenichi Oikawa, Dr. Masato Hagihara, Dr. Cho Kwanghee, and Dr. Takashi Kamiyama for the achievement of "Development of the World's Highest Resolution TOF Type Powder Neutron Diffractometer, SuperHRPD." The former is a beam shaping technology that makes full use of nonlinear optics by installing octupole electromagnets in the system where proton beam is injected into the neutron source of the Material and Life Science Experimental Facility (MLF). As a result, they were able to reduce damage to the neutron generation target window, contributing to the safe operation of the facility. The press announcement was made in July 2020. The latter achievement promotes the development of accurate structural analysis methods and structural studies of functional materials. In 2008, by using a high-resolution neutron source developed by the neutron source group, they achieved the world's highest resolution in a diffraction experiment with a silicon single crystal. In 2015, they conducted powder diffraction with the world's highest resolution by using a silicon powder sample. A commemorative lecture was given at the science session on the 11th.

[President's Choice Award]

The President of the Japanese Society for Neutron Science gives the President's Choice awards biannually at the annual meeting to those the president chooses from various articles published in "Hamon," which is published every quarter. This time, five articles were selected from the articles published in the November 2018 issue to the August 2020 issue. Two articles from the J-PARC Center were included in the selection and were awarded at the 20th annual meeting. One is "Search for Time Reversal Violation using Composite Nuclei" by Dr. Takuya Okudaira (Vol.29 No.3 p.126 2019). The other is "Recent Progress in the Development of Polarizing Supermirror" by Dr. Ryuji Maruyama (Vol.30 No.3 p.130 2020). Please do try and read them.


■ Installation of an Ultrahigh Precision Neutron Focusing Mirror for Nanostructure Analysis Technology for Electrode Interfaces -A major milestone for dramatically improving measurement accuracy- (October 26, Press Release)

Inside a lithium-ion battery, lithium ions, the "carriers" of electricity, swim in the electrolyte between the electrodes. They store and use electricity by moving to the opposite electrode through a thin layer deposited on the surface of the electrode. In order to further improve the performance of batteries, it is important to know the behavior of moving ions, and neutron reflectometry is one of the few methods that can observe the interface between the electrode and the electrolyte. However, the signal of the neutron beam is still weak for the real-time measurements conducted while charging and discharging the battery even with the latest beam source. Therefore, Dr. Norifumi Yamada of J-PARC Center (Assistant Professor of KEK) and his colleagues used the neutron reflectometer SOFIA at J-PARC, which utilizes high intensity (meaning large number of particles) neutron beam, with an ultrahigh precision elliptical neutron-focusing mirror with only about 0.001degree swell compared to an ideal surface. They succeeded in focusing the neutron beam with about twice the intensity of the conventional method, and confirmed that the measurement time could be cut in half. They also showed that by an optics combining multiple focusing-mirrors, the beam could be introduced on a sample with two different incident angles at the same time. This allows simultaneous real-time measurement of thick and thin films, which was not possible with the conventional method. It is expected that the ultrahigh precision focusing-mirror put into practical use in this research will promote the use of real-time measurements using neutron reflectometry for various devices such as fuel cells and organic EL. Its application on the development of all-solid-state batteries, which are expected to be the next-generation of lithium-ion batteries, is also underway.


■ Elucidation of the Cause of Brittle Titanium Alloy Beam Window Receiving a Proton Beams -Development of accelerator target and beam window material through RaDIATE international collaboration- (November 6, Press Release)

The J-PARC’s neutrino experiment, in which elementary particles called neutrinos that react very rarely with matter are created with an accelerator and observed 295 km away at Super-Kamiokande and Hyper-Kamiokande (under construction), requires proton beams with unprecedented intensity to produce neutrinos. A common problem in high-intensity accelerator facilities around the world is that by proton beam irradiation, targets for producing secondary particles such as neutrinos (by injecting a proton beam) and the material of the "beam window" at the entrance of the target station are sometimes damaged at the atomic level and become brittle. In order to solve this problem, RaDIATE international collaboration was organized with the participation of Japan, the United States and Europe. Various material test pieces used for targets and beam windows are irradiated with high-intensity proton beams at Brookhaven National Laboratory in the United States and transported to Pacific Northwest National Laboratory in the United States in order to be tested in hot cells. This time, Dr. Taku Ishida, Lecturer of KEK Research Institute, and Dr. Eiichi Wakai, JAEA Senior Principal Researcher, of J-PARC Center led the research and found the cause of the high-strength 64 titanium alloy used for the beam window of the neutrino facility becoming brittle was due to irradiation. 64 Titanium alloy consists of two phases of particles: α (alpha) phase (hexagonal close packed crystal) and β (beta) phase (body centered cubic crystal). And, after irradiation, its ductility decreased significantly compared to titanium alloy with a smaller proportion of β phase. Furthermore, from electron diffraction and observations by electron microscopy, it was discovered for the first time that more ω (omega) phase (hexagonal crystal) particles, which reduce the ductility of the material, precipitated in the β phase of the 64 titanium alloy as the beam irradiation number increases. It is suggested that this irradiation-induced ω phase is the cause of the rapid decrease in ductility of the 64 titanium alloy. It is expected that this result will lead to the development of targets and beam window materials that can withstand high-intensity proton beams, and will contribute to the promotion of many studies including neutrino experiments.

For more details, please refer to the following. j-parc/c/en/press-release/2020/11/06000612.html


■ J-PARC Hello Science "There is an Accelerator in the Development of Science" (October 30, Tokai Industry and Information Plaza “iVil”)

Accelerators have made significant contributions to the development of science and Nobel Prize-winning research, and are important devices that keep improving. At Hello Science in October, Dr. Tatsunobu Shibata of the Accelerator Division gave a lecture on scientific development and accelerators. In the first half of the lecture, he talked about the role of accelerators and the various discoveries that were made using accelerators since they were first developed. In addition, he explained the reason why accelerators made for the discovery of new particles require high energy. In the second half, he explained that the accelerators of J-PARC produce the world's highest power level of proton beams and are essential for research using secondary particles. In the T2K experiment *, he explained that the muon neutrino produced by the accelerators was changed to an electron neutrino in 2013, which was directly observed by the neutrino observation device Super Kamiokande for the first time in the world. Many questions were asked throughout the lecture.

Super Kamiokande. Many questions were asked throughout the lecture.

* Long-baseline neutrino oscillation experiments carried out between Tokai Village (T) and 295km-away Kamioka Town (K), Gifu Prefecture that began in 2009.


■ 2020 J-PARC Emergency Drill on October 21 at Hadron Experimental Facility

The J-PARC Center conducted the emergency drill of JFY2020 at the Hadron Experimental Facility. This time the drill was under the coronavirus pandemic, and consideration was given to preventing the spread of infection. The assumption of the drill was a large-dose exposure in case of beam operation with workers in an experimental area of the facility. Included in the training were (1) initial response, (2) evaluation of exposure doses to workers and procedures for their transportation, (3) communication between the incident site and the On-site Command Office and between the Command Office and the NSRI (Nuclear Science Research Institute) Accident Measures Headquarter, and (4) a question-and-answer session at a simulated press conference.


■ Participation at JASIS 2020 Exhibition (November 11 – 13, Makuhari Messe International Exhibition Hall)

JASIS (Japan Analytical & Scientific Instruments Show) is one of the largest exhibitions of analytical and scientific instruments in Asia, sponsored by the Japan Analytical Instruments Manufacturers' Association and the Japan Scientific Instruments Association. J-PARC exhibited in collaboration with JRR-3 to introduce the analytical technique using neutron beam. We explained features of the neutron beam analysis at J-PARC, which have the ability to determine the positions and motions of atoms in various materials using pulsed neutrons generated by a high-intensity proton accelerator, and introduced the latest research developments of high-entropy alloys and post-lithium-ion batteries, and so on. We had a variety of visitors, including those in charge of analytical instruments and their users, as well as the staff of public institutions and universities, and students. They listened enthusiastically to our explanations and asked how to use J-PARC and about facility tours to see the instruments, which showed their high level of interest.


■ Sanpo-michi #4 ~Hare and Neutrino~

These photos show a hare that happened to be on a promenade near the Materials and Life Science Experimental Facility Building. It was a very rare event that the hare did not run away even when I held a camera at such a close distance.

At the Nuclear Science Research Institute, you can find footprints of hares on snow when it accumulates, and if you go into a forest, you can easily find their droppings. There should be quite a few hares in this area, but it's not easy to find them. Hares don't have vocal cords, so they don't call each other like other animals and have a very little animal odor.

There are many of them, but we can't see, hear, or smell them. Neutrinos have same characteristics as hares. Despite the fact that neutrinos are the second most abundant particles in the universe after light, they do not react with most things and penetrate through them, so we are unable to grasp their true identity.

In winter, the hares will grow fur as white as snow, depending on the species. Neutrinos that run through outer space also change color like hares during that time.

Our colleagues are fascinated by these neutrinos and have set up a huge set-net called Super-Kamiokande waiting for the neutrinos to get caught. Then, the footprints of a very small portion of neutrinos that were caught in the net are followed using electric signals to find clues to understand their behavior.

The hares here easily pass through the fence, jump over the stumps, and run around on the sand. They could not care less about us being completely absorbed in neutrinos.