HIRFL上合成的第一个新核素—208Hg

本文简述在中科院近物所HIRFL上发现的第一个新核素208Hg的合成和鉴别,兼论利用HIRFL提供的中能重离子束开展远离β稳定线核素合成和衰变研究的优势、困难以及拟采用的物理和技术路线。 The synthesis and identification of the first discovered new nuclide 208Hg on HIRFL(Heavy Ion Research Facility of Lanzhou) were described. In this paper the superiorities, difficultiesas well as the physical and technical line about the synthesis and decay study for the nuclides far fromβ-stability line to be made at HIRFL were discussed.     

用1-苯基-3-甲基-4-苯甲酰基-5-吡唑啉酮从硝酸介质中萃取钪

用1-苯基-3-甲基-4-苯甲酰基-5-吡唑啉酮(PMBP)做萃取剂研究了从HNO3介质中痕量钪的溶剂萃取行为。发现在很低的酸度下,PMBP几乎可以定量地萃取痕量的钪。同时,也讨论了用PMBP从^18O离子辐照过的铀靶溶液中萃取分离钍时钪的沾污。     

14 MeV中子反应和远离核研究

指出了中子源的重要性,扼要地说明了加速器中子源的特点。简单地介绍了14MeV中子引起的核反应,发现了14MeV中子可以引起重核的奇异(n,2p)反应,并以此为基础,形成了合成和研究重丰中子新核素的一条物理思想和生成、分离鉴别技术路线;先后合成和研究了^185Hf、^237Th、^175Er和^197Os等四种重丰中子新核素。     

从14MeV中子辐照过的锇靶中分离钨

用14MeV中子轰击天然锇靶,取道^192Os(n,α)反应生成^189W。利用改进的锇蒸馏装置蒸馏O8O4,完成锇与反应产物的分离;通过四苯砷铼沉淀除去铼。使用HPGe探测器测量了分离的钨样品的γ射线谱,该γ射线谱显示钨样品中杂质元素的去污是令人满意的。     

230Acβ延发裂变的观测

搜索了230Ac β延发裂变. 由60MeV/u18O离子照射232Th,通过多核子转移反应产生230Ra. 经放射化学分离和薄的230Raβ- 230 Ac源的制备,获得了108个230Ac原子. 该源对云母裂变径迹探测器曝光. 借助于所测的γ能谱和两个裂变事件,鉴别了β延发裂变核230Ac,得到了它的β延发裂变几率为(1.19±0.85)×10-8.     

重丰中子核237Th半衰期的测量

通过60MeV/u的¹⁸O离子束轰击天然铀靶,利用多核子转移反应并由放射化学分离方法准备了²³⁷Th的存在,测得它的半衰期为(4.69±0.60)min.这个新的值不仅与我们较早获得的(5.0±0.9)min值一致,而且提高了实验精度.     

搜索同质异能态的一种简便方法

介绍搜索同质异能态的一种简便方法,通过14 MeV中子引起的反应产生目标核,利用γ(X)谱学方法,经由已知的基态γ射线随时间变化的观测来搜索未知短寿命的同质异能态.     

关于重丰中子远离核研究的实验方法

简单地介绍了重丰中子远离核研究的科学意义,报告了重丰中子新核素的产生、分离和鉴别方法。     

液-液萃取从Th中分离Ac

用234Th、228Ac和139Ce 3做示踪剂,二(2-乙基己基)磷酸做萃取剂,研究了初始HNO3浓度对234Th、228Ac和139Ce 3萃取效率的影响。发现在广泛的酸度范围内,234Th均能被定量地萃取;当HNO3浓度大于2.0mol/L时,228Ac和139Ce3 的萃取效率下降到2%以下。研究了震荡时间对234Th萃取效率的影响,数据显示,1min便可达到萃取平衡。从含大量钍的溶液中分离痕量Ac的实验结果显示,用二(2-乙基己基)磷酸-苯的萃取流程,可使Ac与大量的钍分离,同时Ac的损失又较小。     

Dependence of the cross sections for Ir isotopes on the values of Qgg in the heavy ion collision

¹⁹⁷Au were irradiated with 47 MeV/u ¹²C ions. Iridium was produced via the multinucleon transfer reactions in bombardments of ¹⁹⁷Au with ¹²C. and was separated radiochemically from Au and the mixture of the reaction products. The γ radioactivities of Ir isotopes were measured by using a HPGe detector. The production cross sections of Ir isotopes were determined from activities of Ir isotopes at the end of bombardment and the other relative data. It has been found that the cross sections for neutron-rich isotopes of iridium show an exponential dependence on the values of Q_gg. Our experimental results also demonstrate lack of correlation between the cross sections and Q_gg in the case of neutron-deficient isotopes of iridium. The fact can be explained from that neutron-rich isotopes of iridium were produced in the deep inelastic transfer reactions.