Kamioka ObservatoryICRR, The University of Tokyo

Yuki Kanemura

3rd year PhD student in the Faculty of Science & Graduate School of Science, The University of Tokyo (As of April 2024)

Try to achieve more results with the methods which no one has tried ever.

have two studies. One is an experiment detecting Supernova Relic Neutrino (SRN) with a Neural Network. SK- Gd experiment started in July.2020. Thanks to that, we could achieve increasing Super-Kamiokande (SK) sensitivity to SRN. We also need an algorithm that could efficiently select the SRN signals and reject noise events. Therefore, I am trying to distinguish them with a Neural Network, which is one of the machine learning.
The other is the automation of the measurement of radon concentration in SK water. Because radon is one of the BG events for Solar neutrino analysis, we must remove it as much as possible and monitor it in SK water. As part of that work, we sample the water from the SK detector, give the radon off to pure air, and measure the concentration. By automating the work with an automatic system and ladder circuit, I try to make the work easier while maintaining accurate measurements.
Both studies are rewarding because I use methods that no one has tried in SK. 。

I live in an apartment several ten minutes from the institute. It may be inconvenient in terms of transportation, etc., but we could control SK, the Number One detector in Japan, to take and analyze the data. It is the best place for people who would like to do cosmic particle physics experiments hard. I am looking forward to doing the unique studies in SK with you. Thank you.

Shintaro Miki

1st year PhD student in the Faculty of Science & Graduate School of Science, The University of Tokyo (As of April 2022)

Enjoy forms of trial and error that nobody has ever done before

I am mainly conducting two studies, one of which is the testing of photosensors manufactured for Hyper-Kamiokande. We place the photosensors in a darkroom to test the response when a weak light is applied. Photosensors, one of the essential components of Hyper-Kamiokande, affect the overall performance of the detector and are very interesting to investigate. Further, it is exciting to imagine that the light sensor that we are investigating now will capture the light from neutrinos at the bottom of Hyper-Kamiokande in a few years. Another study is the analysis of atmospheric neutrino oscillations at Super-Kamiokande. We aim to observe neutrinos more accurately using the information from neutrons, which are now more visible due to the dissolution of gadolinium in the water of the detector in 2020. It is a series of trial and error as nobody has ever done this before. However, I enjoy seeing the results of what we have tried.

When I entered the doctoral course, I moved to an apartment about 20 minutes by car from the research institute, and I plan to make my life as a researcher in Kamioka more fulfilling. There is even no convenience store around the research center, but when I explore nature here and there, I enjoy the feeling of returning to elementary school. While walking around, I talk with neighboring residents and enjoy the relaxed lifestyle unique to countryside areas.

I hope that we can work together with many people to conduct research that will bring out the potential of the Super-Kamiokande and Hyper-Kamiokande.

Yuri Kashiwagi

2nd year master’s degree student in the Faculty of Science & Graduate School of Science, The University of Tokyo (As of April 2022)

Upgrading the supernova explosion alarm system with researchers all over the world at Kamioka

I am a member of the Super-Kamiokande Supernova Explosion Warning System Development Team. The introduction of gadolinium to Super-Kamiokande in 2020 improved the accuracy when determining the direction of the supernova from the information of neutrinos emitted by the explosion. Therefore, the development team has been upgrading the original supernova explosion alarm system. As part of this, I have been in charge of incorporating the simulation results of various supernova explosion models proposed by researchers around the world into the system. Since there are some researchers from France in the development team, the progress report meeting once a week is held in English. Being able to engage with researchers from various countries based in Japan is one of the attractions of the Kamioka Group. My research field has changed since graduate school, so I have many things to learn; however, I am taking small steps every day with the help of various people.

I go back and forth between Tokyo (living on my own) and Kamioka every few weeks to two months since it has been a type of research that can be performed remotely so far. Biggest merit of visiting Kamioka is that I can quickly solve trivial problems in my research through casual discussions with professors, senior members, and colleagues. The delicious and well-balanced meals served in the research facility also contribute to my comfortable stay in Kamioka. On Sundays and holidays, there are no meals, so I enjoy driving a shared car with senior members and colleagues into Toyama to have lunch (although we need to eat silently now) and to go shopping. There are few women, but this does not cause any problems.

Ryota Kaneshima

2nd year master’s degree student in the Faculty of Science & Graduate School of Science, The University of Tokyo(As of April 2022)

Development of Electronics to Support Observations with the Next-Generation Large Detector

I am developing electronics for the Hyper-Kamiokande. The Hyper-Kamiokande is designed to observe a wide range of physical phenomena and requires optical sensor signal processing electronics with a wide dynamic range and high measurement accuracy. Signal processing electronics have been developed in three countries, and I have developed performance evaluation methods that can reproduce the optical sensor signals at each research institute. Since this study dealt with the optical sensor, which is the basis of Hyper-Kamiokande, I was able to get a closer look at the realization of this frontier experiment. Subsequently, we evaluated the performance of the electronics being developed in Japan and are now developing them to meet the requirements of the Hyper-Kamiokande. Developing hardware for a large detector like the Hyper-Kamiokande is a valuable thing that I can only do now, during the start-up phase, and I find my research challenging and rewarding every day.

Although the accessibility of the Kamioka research facility is not good, many researchers from Japan and overseas come to Kamioka for its unique research environment. Therefore, just by being in Kamioka, I could conduct many experiments and interact with many researchers, and I find this environment attractive, where there is no end to learning. In addition, I usually spend time in Toyama eating fresh and delicious sushi to nourish my energy and feel the four seasons in the nature around the facility to refresh my spirit, which is something I cannot easily experience in the city.

Takuya Tomiya

2nd year master’s degree student in the Faculty of Science & Graduate School of Science, The University of Tokyo(As of April 2022)

Investigation of incredibly sensitive physics phenomena

The photosensors used in the Hyper-Kamiokande experiment were developed in collaboration with researchers and the manufacturer. In cooperation with domestic and international collaborators, preparations are underway for the start of the experiment in 2027, and I am conducting measurements and performance evaluations of the photosensors. The measuring equipment is designed to capture ultrasmall signals, so it is necessary to eliminate noise sources around the equipment. We are working on improving the equipment to measure clean signals. In particular, I am mainly in charge of the study of the effects of magnetic fields. The photosensors are affected by the earth’s magnetic fields and other small influences, so we need to consider these effects. It is interesting to evaluate problems such as what causes poor measurements and how to make good measurements.

I usually live in Chiba prefecture, but I travel to the Kamioka Observatory to work on the photosensors once every two weeks. Professors, senior members, colleagues, technicians and foreign researchers participate in the work. It is very stimulating to discuss the measurements with them. Also, when I stay in the Kamioka facility, I enjoy talking about various things with colleagues from physics to private topics.