2018 Fiscal Year Final Research Report
Study of Majorana nature of neutrino by 48Ca and development of ultra high resolution technique
| Project Area | Revealing the history of the universe with underground particle and nuclear research |
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| Project/Area Number |
26104003
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| Research Category |
Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
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| Allocation Type | Single-year Grants |
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| Review Section |
Science and Engineering
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| Research Institution | Osaka University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
吉田 斉 大阪大学, 理学研究科, 准教授 (60400230)
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| Research Collaborator |
Nomachi Masaharu
Tamagawa Youichi
Ogawa Izumi
Hazama Ryuta
Umehara Saori
Yoshida Sei
Iida Takashi
Nakajima Kyohei
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| Project Period (FY) |
2014-07-10 – 2019-03-31
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| Keywords | 二重ベータ崩壊 / ニュートリノ / カルシウム48 / 原子核実験 / 素粒子実験 |
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| Outline of Final Research Achievements |
The purpose of this research is to develop the way to meV reagion of effective neutrino mass by neutrinoless double beta decay of 48Ca. We studied (1)48Ca enrichment technique, (2) Scintillating bolometer technique to achieve high resolution with particle ID, (3) Measurement of 48Ca 0nDBD by CANDLES experiment. (1) We aimed to enrich 48Ca from the natural abundance (0.19%) to more than 2%. We dveloped a method MCCCE (Multi-channel counter current electrophoresis) by which we were able to obtain 16% which is surprizingly a high enrichment and 10 times more than our original goal. It has a potential of furtehr improvement. (2) We developed scinitillating bolometer to improve energy resolution with particle ID. We successfully demonstrated that the technique works for CaF2 crystals. (3) We constructed shielding system for CANDLES by which we successfully reduced backgrounds from outside. We gave the world best limit on the lifetime of 48Ca 0nDBD.
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| Free Research Field |
素粒子原子核宇宙
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| 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(0nDBD)の観測は、粒子数の保存則が破れていることを示し、宇宙が物質だけの世界になった原因を解明するだけでなく、現代物理学の理解を根本から変える発見になる。本研究では48Caの0nDBDの観測のための研究を進めた。本研究計画で開発した同位体濃縮法のMCCCE法は簡便な装置で高い濃縮度が得られ、既存の技術で不可能であった同位体が実用化でき0nDBD研究の地図が塗り替えられるポテンシャルを有す。また、他の分野や用途の発展が期待でき、その社会的な意義は大きい。温度変化でエネルギーを測定する方法に蛍光観測を組み合わせる方法0nDBD研究の今後の発展を加速する。
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