Development of high performance CaF2 crystals for double beta decay measurement

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H03981
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: Osaka University
• Principal Investigator: Umehara Saori 大阪大学, 核物理研究センター, 准教授 (10379282)
• Research Collaborator: Yoshida Sei ; Takemoto Yasuhiro ; Kurosawa Shunsuke
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 二重ベータ崩壊 / 低バックグラウンド / 低放射能

Outline of Final Research Achievements

Study for neutrino-less double beta decay is an important topic. The neutrino-less double beta decay occurs when anti-neutrinos can convert to neutrinos. If this decay can be observed, this would prove that the neutrinos are Majorana particles, and that itself is a remarkable discovery. Now we are developing next generation detector system for measurement of the neutrino-less double beta decay of calcium-48 by using calcium fluoride crystals. In development of the detector system, we need three techniques, which are high purity calcium fluoride crystals, enrichment of calcium-48 and scintillating bolometer. In this research subject, we succeeded in production of the high purity calcium fluoride crystals and studied how to synthesize calcium chloride into calcium fluoride because calcium-48 obtains as calcium chloride. In addition we first succeeded in scintillating bolometer with the calcium fluoride crystal.

Free Research Field

原子核・素粒子実験

Academic Significance and Societal Importance of the Research Achievements

ニュートリノを放出しない二重ベータ崩壊測定は、ニュートリノのマヨラナ粒子性(粒子・反粒子の転換可能性) を検証できる唯一の方法であり、また、ニュートリノの質量の絶対値を観測できる重要な測定である。本研究では、二重ベータ崩壊測定装置開発のために必要な技術開発を行った。これは、現在の二重ベータ崩壊測定の感度を飛躍的に向上した次世代二重ベータ崩壊測定装置構築に有用である。