Development of precise measuring technology of MeV electrons with nuclear emulsion for search for neutrinoless double-beta decay

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K18627
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 15:Particle-, nuclear-, astro-physics, and related fields
• Research Institution: Nagoya University
• Principal Investigator: Fukuda Tsutomu 名古屋大学, 高等研究院, 特任講師 (10444390)
• Project Period (FY): 2021-07-09 – 2023-03-31
• Keywords: 原子核乾板 / 素粒子実験 / 二重ベータ崩壊 / MeV電子 / 平板状ハロゲン化銀結晶 / マヨラナ粒子

Outline of Final Research Achievements

In order to elucidate the origin of the extreme lightness of elementary particle neutrinos and the reason why the universe is filled with matter (the origin of the matter-dominated universe), I have proposed a new experimental method using nuclear emulsions and developed a new nuclear emulsion gel that is completely different from conventional emulsion gel.
The newly developed nuclear emulsion gel with flat-type silver bromide crystals is expected to suppress the uncertainty of the passage distance of charged particles within the crystal compared to the conventional nuclear emulsion gel with octahedral-type silver bromide crystals, and to dramatically improve the energy resolution of MeV electrons emitted from 0νββ.

Free Research Field

素粒子実験

Academic Significance and Societal Importance of the Research Achievements

本研究では半世紀以上手が付けられていなかった原子核乳剤の結晶形状を抜本的に改良するという野心的な研究に挑戦し、新たに平板状の臭化銀結晶を持つ原子核乳剤の作製に成功した。この成果は、将来の原子核乾板を用いた0νββ探索実験の実現に向けた極めて重要な一里塚である。また、今後取り組む実用化研究が達成された暁には、素粒子検出器としても全く新しいデバイスが開発される可能性があり、その波及効果は計り知れない。