Category: Research

Scientists from the international XENON collaboration, an international experimental group including the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), University of Tokyo; the Institute for Cosmic Ray Research (ICRR), University of Tokyo; the Institute for Space-Earth Environmental Research (ISEE), Nagoya University; the Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University; and the Graduate School of Science, Kobe University, announced today that data from their XENON1T, the world’s most sensitive dark …

Prototype Schwarzschild–Couder Telescope (pSCT, see Fig. 1), one of prototype telescopes developed for the Cherenkov Telescope Array (CTA) project, observed the Crab Nebula and successfully detected very-high-energy gamma rays from the object with a statistical significance of 8.3σ (Figs. 2–4). The viability of two new technologies used in pSCT, the Schwarzschild–Couder optical system with a large field of view of 8 degrees and a small camera pixel size of 6 mm realized by using silicone photomultipliers (SiPMs), have been proved …

  The Belle II experiment—an international collaboration of physicists searching for signs of undiscovered particles—has published the experiment’s first results in a paper selected as an Editors’ Suggestion in Physical Review Letters. The results offer physicists new clues in their hunt for dark matter, a substance believed to make up some 85% of the universe. The Belle II experiment, which operates at the SuperKEKB electron-positron collider in Tsukuba, Japan, searched for a hypothetical new particle called the Z’ that may …

Novel mechanism to avoid theoretical bound on kaon rare decays Researchers try to revisit a theoretical bound, which is based on symmetries, between the charged and neutral kaon rare decays into the pion and neutrinos. Last September, KOTO experiment searching for neutral kaon rare decay reported events with an unexpected rate, which is much bigger than the standard model predictions. So far, KOTO experiment has not claimed that these events are the rare kaon decay signals. On the other hand, …

  A research group including Associate Professor Kazuhiro Nakazawa, of the Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University, detected a downward burst of gamma rays during lightning discharge with scintillation detectors at the Kashiwazaki-Kariwa Nuclear Power Station at sea level in Japan. This research was published in Physical Review Letters on August 7, 2019.   Although lightning is a familiar natural phenomenon, thunderclouds still hold many mysteries. Terrestrial gamma ray flashes (TGFs), which are …

A research group including Associate Professor Kazuhiro Nakazawa, KMI, Nagoya University has observed high-energy radiation phenomena coming from thunder-clouds, and found a prolonged steady emission resulted in a short burst of radiation associated with a lightning discharge. The evolution of the phenomena strongly suggests the initial long emission is related with the triggering of the lightning. The research group was performing ground-based gamma-ray observation campaign aiming at winter thunder-clouds in Hokuriku-region. In the work, they observed a minute-long radiation from …

“Neutron is a massive and chargeless particle, which can be used for various precision measurements”, Associate Professor Masaaki Kitaguchi of KMI says. “We have successfully developed a new type of position sensitive detector with extremely-high resolution of 11 nm. It can be a strong tool for experiments with neutrons.” Nuclear emulsion is used for various experiments for particle physics with muons and neutrinos, which is also applied to imaging through a pyramid today. Nagoya University team is continuing to develop …

  On March 11th, 2019, Phase 3 operation of the SuperKEKB/Belle II project began successfully, marking a major milestone in the development of Japan’s leading particle collider. This phase will be the physics run of the project, in which the Belle II experiment will start taking data with a fully instrumented detector. The KEKB accelerator, operated from 1999 to 2010, currently holds the world record luminosity for an electron-positron collider. SuperKEKB, its successor, plans to reach a luminosity 40 times …

Using the powerful Japanese Subaru telescope, the Hyper Suprime-Cam (HSC) survey collaboration team has made and analyzed the deepest wide field map of the three-dimensional distribution of matter in the Universe. The reserach team, including researchers from Nagoya University, Professor Naoshi Sugiyama at KMI/Graduate School of Science, Lecturer Atsushi Nishizawa and Assistant Professor Hironao Miyatake at Institute for Advanced Research, has used the gravitational distortion of images of about 10 million galaxies to make a precise measurement of the lumpiness …