KamLAND (Kamioka Liquid Scintillator Antineutrino Detector) is an electron antineutrino detector at the Kamioka Observatory, an underground neutrino detection facility located in the Japanese Alps, near the border of Gifu and Toyama prefectures. This project is conducted by the Research Center for Neutrino Science, Tohoku University, and involves numerous universities and institutes from around the world.

Goals of Physics

Reactor Neutrinos

At the heart of the detector is approximately 1 kiloton of liquid scintillator (LS), a highly sensitive medium capable of detecting faint signals from antineutrino interactions. KamLAND was originally designed to detect antineutrinos emitted from nuclear reactors located hundreds of kilometers away, providing groundbreaking confirmation of neutrino oscillations and thus evidence for neutrino mass.

First Ever Observation: Geoneutrinos

In addition to reactor antineutrinos, KamLAND has also made pioneering contributions to the field of geoneutrino research by detecting antineutrinos originating from radioactive decays within the Earth’s interior (Nature, 2005). These measurements offer unique insights into the Earth’s composition and heat production, highlighting KamLAND’s crucial role in both particle physics and geoscience.

KamLAND-Zen Period: 0νββ

Since 2011, a small balloon filled with several hundred kilograms of xenon (Xe) has been installed inside the detector, initiating the KamLAND-Zen experiment, which aims to search for neutrinoless double-beta decay (0νββ). The name KamLAND-Zen is rich in meaning: “Zen” stands for zero neutrino double beta decay, reflecting the nature of the process under investigation. It also alludes to the meditative patience required for waiting for such rare events to occur, resonating with the spirit of Zen. Moreover, the working isotope, xenon, is sometimes pronounced similarly to zenon, adding a phonetic twist. As this search could help answer some of the most profound questions in particle physics and cosmology, KamLAND-Zen continues to be one of the most prominent topics in the current KamLAND program.

For more information about KamLAND, please visit the official website of the KamLAND experiment.