极缺中子Ac核的α衰变及ER-γ-α-γ符合测量的实验探索

发布时间：2018-06-23 17:47

本文选题：充气反冲谱仪 + Si-BOX探测器　；参考：《兰州大学》2016年博士论文

【摘要】：兰州充气反冲分离器(SHANS)重点研究超重核的合成机制与衰变特性。目前,我们在此实验平台主要开展了Z=92附近缺中子核素合成及其衰变性质的实验研究。本论文主要阐述以下研究工作:在谱仪终端,利用全熔合蒸发反应169Tm(40Ca,xn)209-xAc,合成极缺中子的Ac同位素核。熔合产物经过两个多丝正比室(MWPC),注入到Si-BOX阻止探测器进行衰变测量。核素的鉴别采用注入核与其衰变产物间位置-时间关联的分析方法。本次研究工作将Eα=7.935(30)MeV,211/2 4T11 ms+-=的未知α衰变指定给新核素205Ac;基于对约化α衰变宽度系统性的分析,认为该α衰变是从母核基态到子核基态的衰变,同时建议了205Ac的基态组态为-2/9)(2/9nph。在兰州充气谱仪终端(SHANS)探索ER-g-α-g关联测量的实验方法。利用40Ca+natHf的弹靶组合,生成N=126附近已知的缺中子核素。通过α和g的衰变谱学研究,鉴别出214,215Th,215Ac和210,212Ra的短寿命同质异能态。实验得到的结果与已知数据完全符合;此外,本实验也观测到了214Ac和215Th等核α衰变谱的精细结构,重复了已有的实验数据。此次实验结果表明了ER-g-α-g关联测量在SHANS上的成功应用,这为我们将来在该领域的研究提供了必要的科学技术条件。
[Abstract]:Lanzhou inflatable recoil separator (SHANS) focuses on the synthesis mechanism and decay characteristics of superheavy nuclei. At present, we have mainly carried out experimental research on the synthesis and decay properties of neutron deficient nuclides near ZX92 on this experimental platform. The main work of this thesis is as follows: at the end of spectrometer, the neutron deficient ac isotopic nuclei were synthesized by fully fusion evaporation reaction 169Tm (40Caxn) 209-xAc. The fusion product passes through two multifilament proportional chambers (MWPC) and is injected into Si-BOX to prevent the detector from decay measurement. Radionuclides are identified by location-time correlation between injected nuclei and their decay products. In this study, the unknown 伪 decay of E 伪 7.935 (30) MeVN 211 / 24T11ms = was assigned to the new nuclide 205Ac.Based on the systematic analysis of the reduced 伪 -decay width, it is considered that the 伪 -decay is the decay from the ground state of the parent nucleus to the ground state of the subnucleus, and the ground state configuration of 205Ac is -2 / 9) (2 / 9nphph. The experimental method of ER-g- 伪 -g correlation measurement was explored at Lanzhou inflatable spectrometer terminal (SHANS). Using 40Ca natHf projectile target combination, a known neutron deficient nuclide near NC126 was generated. The short-lived isomorphic states of 214215Th215Ac and 210212Ra are identified by the decay spectroscopy of 伪 and g. In addition, the fine structures of nuclear 伪 -decay spectra such as 214Ac and 215Th have been observed, and the experimental data have been repeated. The experimental results show that ER-g- 伪 -g correlation measurement has been successfully applied in SHANS, which provides necessary scientific and technological conditions for our future research in this field.
【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O571.32

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