Basic Study of a New Approach to Super Heavy Elements by Incomplete Fusion Reactions

不完全聚变反应超重元素新方法的基础研究

• 批准号: 04452023
• 负责人: NOMURA Toru
• 金额: $ 4.35万
• 依托单位: Institute for Nuclear Study, University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1992
• 资助国家: 日本
• 起止时间: 1992 至 1993
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04452023/
• 关键词: Superheavy elements; In complete Fusion; Pre-equilibrium alpha emission; Gas-filled separator; Position-sensitive detector; alpha decay; Spontaneous fission; 稀事象; 超重原子核; 気体充填型反跳核分析器

1. Development of experimental apparatus and method(a) A new type solid-state detector striped on both sides has been made to improve position resolution even for alpha decays having low energy deposition. (b) The usual gas-filled separator (GARIS) utilizing a thin foil to separate the vacuum and gas-filled regions cannot stand high-intensity beam due to breakdown of the foil. We have adopted a differential pumping method to overcome this difficulty. (c) Careful calibration on pulse-height defects of the SSD for very heavy nuclei has been made to enable their mass analysis using their time-of-flight and energy measurements.2. Use of pre-equilibrium alpha emission for production of very heavy nucleiWe have performed a measurement on the ^<238>U(^<40>Ar, alpha2n)^<272>108 reaction using the GARIS to collect reaction products recoiling out of a thin target. Their velocities and energies were measured by a time-of-flight system and a position-sensitive detector (PSD) placed upstream and at the focal plane of the GARIS, respectivery. Subsequent alpha decays and spontaneous fissions were also measured in the same PSD.Based on the analysis of the time- and position-correlations, we have succeeded in identifying new alpha-decay events, which are considered to take place from the nucleus ^<272>108. The cross section of the above reacton is roughly 1nb, which is much larger than that obtained in the usual (HI,xn) type reaction.

1. 实验装置和方法的开发(a) 制作了一种新型两侧条纹固态探测器，即使对于低能量沉积的α衰变也能提高位置分辨率。 （b）通常的充气分离器（GARIS）利用薄箔来分隔真空和充气区域，由于箔的击穿而无法承受高强度光束。我们采用了差动泵送方法来克服这个困难。 (c) 对非常重核的 SSD 脉冲高度缺陷进行了仔细校准，以便能够使用其飞行时间和能量测量进行质量分析。2。使用预平衡α发射来产生非常重的核我们已经使用GARIS对^<238>U(^<40>Ar, alpha2n)^<272>108反应进行了测量，以收集从薄靶材反冲出来的反应产物。它们的速度和能量由分别放置在 GARIS 上游和焦平面的飞行时间系统和位置敏感探测器 (PSD) 测量。随后的α衰变和自发裂变也在同一PSD中进行了测量。基于时间和位置相关性的分析，我们成功地识别了新的α衰变事件，这些事件被认为是从原子核^<272>108发生的。上述反应的横截面大约为1nb，比通常的(HI,xn)型反应获得的横截面大得多。

项目成果

Y.Shirakabe: "Bunching of Radioactive Ion Beam in the Millisecond Region -a Pulsed Gating-potential Method in an Ion Source for On-line Isotope Separation-" Nuclear Instruments & Methods in Physics Research. A337. 11-15 (1993)

Y.Shirakabe：“毫秒区域放射性离子束的集束 - 离子源中用于在线同位素分离的脉冲门控电位方法 -”核仪器

T.Nomura: "Search for Very heavy Nuclei by the (HI, alphaxn) Reaction" Proc.6th Franco-Japanese Colloquium on Nuclear Structure and Interdisciplinary Topics (Saclay 93223). 392-398 (1993)

T.Nomura：“通过（HI，alphaxn）反应寻找非常重的原子核”Proc.6th 法日核结构和跨学科主题研讨会（Saclay 93223）。

T.Nomura: "Study of alpha Decays Following ^<40>Ar Bombardment on ^<238>U" Proc.RIKEN Int.Workshop on Heavy Ion Riacsions with Neutron-Rich Beam (World Scientific, Singapore). 269-277 (1994)

T.Nomura：“^<40>Ar Bombardment on ^<238>U 后的 α 衰变研究”Proc.RIKEN Int.Workshop on Heavy Ion Riacsions with Neutron-Rich Beam（世界科学公司，新加坡）。

Y.Shirakabe: "Bunching of radioactive ion beam in the millisecond region -a pulsed gating-potential method in an ion source for on-line isotope separation-" Nuclear Instruments & Mthods in Physics Research. A337. 11-15 (1993)

Y.Shirakabe：“毫秒范围内放射性离子束的聚束 - 离子源中用于在线同位素分离的脉冲门控电位方法 -” Nuclear Instruments

大槻義彦ら(共著): "現代物理学小辞典" 講談社, 741 (1993)

大月义彦等人（合著者）：《现代物理学小辞典》讲谈社，741（1993）