Direct mass measurements of super heavy elements using a novel low-energy RI-beam production method

2016 Fiscal Year Final Research Report

• Project/Area Number: 24224008
• Research Category: Grant-in-Aid for Scientific Research (S)
• Allocation Type: Single-year Grants
• Research Field: Particle/Nuclear/Cosmic ray/Astro physics
• Research Institution: High Energy Accelerator Research Organization (2016); Institute of Physical and Chemical Research (2012-2015)
• Principal Investigator: Wada Michiharu 大学共同利用機関法人高エネルギー加速器研究機構, 素粒子原子核研究所, 教授 (50240560)
• Co-Investigator(Kenkyū-buntansha): 森本 幸司 国立研究開発法人理化学研究所, 仁科加速器研究センター, チームリーダー (00332247) ; 加治 大哉 国立研究開発法人理化学研究所, 仁科加速器研究センター, 研究員 (00391912) ; 小浦 寛之 国立研究開発法人日本原子力研究開発機構, 先端基礎研究センター, 研究主幹 (50391264) ; 羽場 宏光 国立研究開発法人理化学研究所, 仁科加速器研究センター, チームリーダー (60360624) ; 園田 哲 国立研究開発法人理化学研究所, 仁科加速器研究センター, 研究員 (60525583) ; SCHURY P.H 筑波大学, 数理物質科学研究科(系), 講師 (30462724)
• Co-Investigator(Renkei-kenkyūsha): OZAWA Akira 筑波大学, 数理物質科学研究科, 教授 (80260214) ; TAKAMINE Aiko 国立研究開発法人理化学研究所, 仁科加速器研究センター, 研究員 (10462699) ; OKADA Kunihiro 上智大学, 理工学部, 教授 (90311993) ; MIYATAKE Hiroari 高エネルギー加速器研究機構, 素粒子原子核研究所, 教授 (50190799) ; SCHURY Peter 高エネルギー加速器研究機構, 素粒子原子核研究所, 助教 (30462724)
• Research Collaborator: WOLLNIK Hermann ニューメキシコ州立大学, 教授
• Project Period (FY): 2012-05-31 – 2017-03-31
• Keywords: 短寿命原子核 / 質量 / イオントラップ / 超重元素 / MRTOF

Outline of Final Research Achievements

With a novel ion trapping method, cryogenic rf-carpet ion guide, and a multi-reflection time-of-flight mass spectrograph, the masses of more than 80 nuclear fusion reaction products including short-lived Ra isotopes (T1/2= 10 ms) and several trans-uranium isotopes of Es, Md were measured. The highest precisions of ~0.03 ppm were achieved for Ga isotopes and most of well-known nuclides, our masses agree with the literature values. However, some discrepancies were found in old indirect measurements. It suggested that such indirect measurements must be revised with comprehensive direct mass measurements.
The masses of four isotopes in Es and Md were measured for the first time. From them, the masses of 7 isotopes in super-heavy elements up to Mt were indirectly determined and comparison with various nuclear models and confirmation of N=152 shell closure were performed.

Free Research Field

原子核物理学