宇宙線観測アプリ[宙豆]そらまめ

iOS and Android app for observing cosmic rays

We have developed a radiation detection application for smartphones and tablets that allows users to easily observe and monitor cosmic rays. Cosmic rays are radiation particles that originate from outer space and pass through our bodies at a rate of over 100 particles per second. This application enables users to observe these cosmic rays, which are invisible to the naked eye, in a simple and accessible way. The app was developed and made available through a joint research project with the HIBINO Laboratory in the Department of Applied Physics at Kanagawa University.

Turn your old smartphones and tablets into Cosmic Ray Detector

The number of smartphones in use worldwide has surpassed 6 billion, and when including devices such as tablets and laptops that can connect to the internet, the number exceeds 8 billion. New versions are released almost every year, leading people to replace their devices within short periods of time. What happens to these devices after they become obsolete within a few years? These devices may be small, but they are still sophisticated computers that contain many valuable components. One of these components is the camera sensor, which is included in most devices. The sensor is made of a silicon-based semiconductor known as a CMOS camera image sensor. This sensor has been used to develop the "Soramame" cosmic ray observation app. By utilizing used smartphones and tablets to make global network of detectors, we can contribute to cutting-edge research in astrophysics.

New method that utilizes the billions of CMOS sensors spread around the world

Cosmic rays are highly energetic particles of various types that originate from sources within and outside of the Milky Way galaxy, and that arrive at Earth's atmosphere. When they interact with the atmospheric nuclei, a shower of secondary particles is generated. The objective is to detect these secondary particles with the camera sensor of a smartphone. On average, the frequency of secondary particles from cosmic rays that reach Earth's surface is approximately one particle per minute per square centimeter, and they can penetrate through different materials, including human bodies, rocks, and concrete, due to their high energy. As cosmic rays traverse through the silicon camera sensor, they produce a minuscule trail, akin to a scratch, which is then detected in digital images.

Using the "Soramame" app to observe cosmic rays worldwide has the potential to enable the detection of rare air showers created by ultra-high-energy cosmic rays, which are among the most high-energy-density phenomena currently observed on earth. These cosmic rays are believed to be extremely high-energy particles originating from beyond the Milky Way, with energy levels that cannot be generated on Earth. However, the origin and acceleration mechanisms of these particles are still not fully understood.

By observing these particles, we may also be able to gain valuable insights into the physics of dark matter and dark energy, which are two of the most challenging and elusive areas of modern astrophysics. The study of ultra-high-energy cosmic rays may thus open up a window to a previously unexplored world of the universe beyond our current understanding.
2023.03.26

CONTACT: Wakiko Takano r201970105fg_at_jindai.jp
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