| ■ J-PARC News - December 2015 (Issue #127) |
●Researchers Discover Phenomenon in which a "Strange Particle" Breaks Charge Symmetry of the Atomic Nucleus (November 25, Press Release) - E13 International Collaborative Experiment at the Hadron Experimental Facility - |
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| An international research group centered around Tohoku University, the High Energy Accelerator Research Organization (KEK), and the Japan Atomic Energy Agency (JAEA), and working within the E13 international collaborative experiment carried out using the K1.8 beamline of J-PARC's Hadron Experimental Facility, has discovered a large break in charge symmetry-the basic symmetry of the atomic nucleus-by adding to the nucleus a lambda particle (Λ) with a strange quark (s), i.e., what is called a "strange particle." An atomic nucleus in which the number of protons and the number of neutrons has been interchanged (a mirror nucleus) has the property called "charge symmetry" in which mass and structure are the same as the original nucleus. As shown in Fig. 1 (image at left), the tritium (3H) nucleus and helium-3 (3He) nucleus are mirror images of each other. In the 3He nucleus, there is an electrical repulsion effect between protons, but if that effect is subtracted, it is evident that the mass is almost equal to 3H, and the structure is the same. However, a mysterious phenomenon was discovered in which, if a single lambda particle is added to each nucleus as shown in Fig. 1 (image at right), then a large difference in mass appears between the hydrogen-4 hypernucleus 4ΛH and the helium-4 hypernucleus 4ΛHe. This discovery is an important step toward elucidating the forces which act between the lambda particle and protons/neutrons, and was featured in the journal Physical Review Letters (published November 24, 2015). The paper was also chosen as an Editors' Suggestion of the journal. |
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| KEK and the Canadian TRIUMF Laboratory have previously signed cooperative agreements and carried out collaborative research in fields such as elementary particle physics and materials science. At J-PARC too, researchers from TRIUMF are actively participating in neutrino research, and research on materials science, basic physics, and related areas using muon particles. Recently, KEK and TRIUMF concluded an agreement to mutually establish satellite offices to provide the support necessary for further promotion of joint research. A signing ceremony by the directors of the two organizations was held on December 4 at the Canadian Embassy in Japan, in the presence of the Canadian Ambassador to Japan, and the Chief of the Research Promotion Bureau of the Ministry of Education, Culture, Sports, Science and Technology. Naohito Saito, Director of the J-PARC Center, also attended the signing ceremony, and confirmed that J-PARC will continue to promote research using J-PARC together with the involved parties. |
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| The 10th Asia-Oceania Neutron Facility Directors Meeting (FDM) was held on December 3 and the 15th AONSA-EC (Asia-Oceania Neutron Scattering Association - Executive Committee) Meeting was held on December 4, at the Neutron Science Laboratory, Institute for Solid State Physics, University of Tokyo, located in Tokai Village. These meetings were attended by interested parties from the countries and regions belonging to AONSA. The FDM was attended by five representatives from typical neutron experimental facilities in Asia and Oceania, as well as interested observers, and there were reports on current conditions at each facility. Dr. Toshiji Kanaya, Head of the Material and Life Science Division, attended from J-PARC, and he reported on research results, the latest news on the neutron source, and other topics. At AONSA-EC, the committee approved admission of the newly established Indonesia Neutron Society. It was reported that the next AONSA Neutron School will be held in Mumbai in November of next year. The selection results for the AONSA Young Research Fellowship were also announced, and it was agreed that one of the three selected young researchers will be accepted by J-PARC. There was also discussion of replacement of the executives whose terms of office will expire. The current Vice Chairman Dr. Sung-Min Choi (Korea Advanced Institute of Science and Technology, KAIST) was appointed as Chairman, and Dr. Kazuyoshi Yamada, Director of the Institute of Materials Structure Science, KEK, was appointed as Vice Chairman. |
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| On December 10-12, the 15th Meeting of the Japanese Society for Neutron Science (JSNS) was held in Saitama Prefecture. At the society's awards ceremony on the 10th, research achievements relating to J-PARC were recognized for excellence, with Dr. Susumu Ikeda, Professor Emeritus of KEK (and former Deputy Head of the MLF) receiving an Achievement Award, Professor Yoshiaki Kiyanagi of Nagoya University receiving the Society Award, and Dr. Takanori Hattori and Dr. Asami Sano of the Neutron Science Section receiving the Technology Award together with Dr. Hiroshi Arima of Tohoku University (formerly of J-PARC). On the same day, Dr. Yoshiaki Kiyanagi, Chairman of JSNS, gave a special talk in tribute to the late Noboru Watanabe, Professor Emeritus of KEK (and former fellow at the J-PARC Center), in recognition of his major international contributions to the development of a pulsed neutron source. |
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Achievement Award : Susumu Ikeda, Professor Emeritus, KEK (former Deputy Head of MLF) "Observation of Quantum States of Hydrogen in Matter Using a Pulsed Neutron Source" Details : This award recognized a number of achievements, including contributions to the construction of a spallation neutron source, promotion of materials science research, and efforts to increase utilization at the KEK Booster Synchrotron Facility (KENS), and after Professor Ikeda's move from KENS to J-PARC, research in hydrogen science using a pulsed neutron source, and efforts in the area of facility operations. |
Society Award : Yoshiaki Kiyanagi, Professor, Nagoya University "Research and Development on an Accelerator Neutron Source" Details : This award recognized efforts such as contributions to the development of the J-PARC neutron source, and construction of the BL22 Energy Resolved Neutron Imaging System (RADEN). |
Technology Award : Takanori Hattori, Asami Sano (Neutron Science Section), and Hiroshi Arima (Tohoku University, former member of the same section) "Research and Development on an Accelerator Neutron Source" Details : This award recognized efforts such as contributions to the development of the J-PARC neutron source, and construction of the BL22 Energy Resolved Neutron Imaging System (RADEN). |
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| The 7th AONSA Neutron School and the 3rd MLF School were held concurrently on December 1-5 at the Materials and Life Science Experimental Facility (MLF). These schools are for young researchers and graduate students in the Asia/Oceania region, and there were a total of 41 participants. Of these, 33 were foreign nationals, and this showed the high expectations for these schools held at MLF. In terms of content, there were lectures on topics such as neutron science and muon science, followed by training relating to beams. In this training, the participants were divided into 12 small groups at their request, and they worked to solve experimental problems on various themes using experimental data on neutrons and muons. The persons in charge of each system explained the instruments, sample handling and other topics to the participants, and the participants carried out tasks such as analysis of data using experimental data* collected in the past. On the final day, a session was held to report on the training results for each group, and there was lively discussion among the participants. |
| *The AONSA Neutron School was scheduled to be held in Japan two previous times, in 2011 and 2013, but it had to be cancelled in 2011 due to the Great East Japan Earthquake in March, and in 2013 due to the radioactive material leak accident at the Hadron Experimental Facility in May. This time, a situation arose where experiments using the MLF were shut down immediately before the school was held, but there were no cancellations by those hoping to participate, and the school was a success. |
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| Recently, we have inconvenienced many of our users because of a temporary halt in operations. This is due to problems with the neutron target of the MLF. At present, we are making diligent efforts to investigate the cause and resume operation. We will provide information such as the outlook for resumption of operation by contacting users directly, and posting notices on our home page etc. Thank you for your understanding. |
| The Tamarokuto Science Center holds Science Cafe events together with the High Energy Accelerator Research Organization (KEK). At the Science Cafe in November, Dr. Shinichi Sakamoto of the Public Relations Section was the speaker. At J-PARC, many accelerators and experimental instruments are operating in synchronization with accurate "time." This was an opening to raise the topic of time, and Dr. Sakamoto explored the true nature of mysterious "time" based on various experiments. The venue was filled with participants of all ages, from elementary school students to senior citizens. |
| Every day, we live within the flux of time, but when we deliberately consider what sort of thing time is, it is very strange and elusive. Have you ever thought it would be great if you could turn back time, and return to a period long ago? In the style of the Royal Institution Christmas Lectures, Dr. Sakamoto presented various experiments with the help of the participants, and had them think on their own about time and experience it in a hands-on way. The first half was a warm-up, based on familiar topics such as the mechanisms by which various clocks work, and the body's internal clock. In the second half, the talk became a little more difficult. For example, in the special theory of relativity, time moves more slowly if you move faster, and if a ball is thrown straight up while moving, it will appear to those watching nearby that the ball moves up at a slant. The reason why this happens was explained in an easy to understand way. In today's physics, the very existence of time has become something vague and indefinite, but the talk came to the conclusion that we ourselves actually create our own time. The topic was wide-ranging, covering areas from science to philosophy, and it was a very enjoyable Science Cafe. |
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| Dr. Takaaki Kajita (Director of the Institute for Cosmic Ray Research, University of Tokyo) and Dr. Arthur McDonald (Professor Emeritus, Queen's University, Canada) received this year's Nobel Prize in Physics for their research achievements relating to neutrinos, a type of elementary particle. On December 10 (Sweden time), they received medals at the Nobel Prize Award Ceremony held in Stockholm, the capital of Sweden. They won the prize for "the discovery of neutrino oscillations, which shows that neutrinos have mass," but many people from different walks of life have said they do not really understand this. Therefore, we held a Science Gallery, using the village library as a venue, and Dr. Shinichi Sakamoto of the Public Relations Section provided an easy-to-understand explanation, starting from the question "What is an elementary particle?" and covering the research results which won the prize. Mini-lectures (30 minutes long) were given five times from morning until evening, and a total of about 50 people visited the venue. There was also an explanation of the T2K Experiment (in which Dr. Kajita participates as a collaborator). In this project, research is being carried out by firing a neutrino beam produced by an accelerator from J-PARC to the Super Kamiokande detector with which Dr. Kajita discovered neutrino oscillation. After the talks, Dr. Sakamoto conscientiously answered various questions from the participants while using experimental equipment. He also displayed an actual photomultiplier tube of the type used in the Super Kamiokande, and the participants were overwhelmed by its size. Junior high school students who listened to the talks said they were glad they did, and elderly participants said they gained a good understanding of neutron oscillation. It was a fun and worthwhile science gallery. |
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