239Pa可能对天体物理研究产生一点影响

扼要介绍利用重计时对的核宇宙年代学来进行宇宙年龄估计的方法. 简单叙述²³⁹Pa的异常长的半衰期对于宇宙年龄估计的影响.     

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.     

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.     

Z=105质量数为259的新同位素的合成和鉴别

利用120MeV的²²Ne离子束轰击²⁴¹Am靶,通过²⁴¹Am(²²Ne,4n)²⁵⁹Db反应合成了一个Z=105,质量数为259的新同位素.反应产物是用氦喷嘴技术和转动轮装置传输收集的.借助一系列金硅面垒探测器探测到了反应产物及其子核的α衰变.新同位素的原子序数Z和质量数A是借助该同位素和已知的²⁵⁵Lr核之间的遗传关系得到了确定的鉴别.新同位素²⁵⁹Db的测量半衰期为(0.51±0.16)s;它的α粒子能量为9.47MeV.由本实验导出的²⁵⁹Db的Qα值同理论预言结果能够较好地符合.     

179Pt转动带性质的研究

利用能量为164—180MeV的³⁵Cl束流,通过¹⁴⁹Sm(³⁵Cl,p4n)反应研究了179Pt的高自旋态能级结构.进行了γ射线的激发函数、X γ和γγt符合测量,建立了基于12^－[521],52^－[512]和72⁺[633]组态的3个转动带.实验上观测到12^－[521]带在hω=0.27MeV附近顺排角动量突然增大,且72⁺[633]带具有较大的旋称劈裂.通过比较奇APt同位素和¹⁷⁹Pt的同中子素能级结构的系统性,对相关现象进行了分析和讨论.     

新核素238Th的鉴别

利用60MeV/u的¹⁸O离子束轰击天然铀靶,通过多核子转移反应生成重丰中子新核素²³⁸Th.观测到了²³⁸Th的子体²³⁸Paγ活性的生长、衰变行为,鉴别了²³⁸Th的存在,并测得它的半衰期为(9.4±2.0)min.同时,发现了一条能量为(89.0±0.3)keV、半衰期为(8.9±1.5)min的新γ射线,指定为²³⁸Th的衰变γ射线.     

266Bh的α衰变性质研究(英文)

报道了利用兰州重离子研究装置提供的26Mg重离子束流轰击243Am靶产生和鉴别已知超重核素266Bh的实验结果。利用转轮收集探测装置依靠母子核遗传关系通过观测Bh同位素与其子核Db和Lr之间的α-α关联事件来鉴别266Bh。实验中观测到266Bh的α能量为（9.03 ± 0.08）MeV, 与日本理化学研究所在合成113号元素中第一个衰变链中观测到266Bh的α能量为9.07 MeV相近。 266Bh的半衰期为0.66+0.59-0.26 s, 从实验得到的Qα也符合Z=107的Qα随中子数变化的系统性。The isotope of 266Bh was produced and identified definitely in bombardments of 243Am target with 162 MeV 26Mg ions at HIRFL. Identification was made by observation of correlated α particle decays between the Bh isotopes and their Db and Lr daughters using a rotating wheel system. The measured α energy for 266Bh is (9.03±0.08) MeV, and this value close to the 9.07 MeV for 266Bh observed in the first chain of element 113 at RIKEN. The half life of 266Bh is 0.66+0.59 -0.26 s. The Qα value derived from this experiment fits well into the general trend in a “Qα N systematics” for the isotopes with Z = 107.     

Comparative studies of silicon photomultipliers and traditional vacuum photomultiplier tubes

Silicon photomultipliers (SiPMs) are a new generation of semiconductor-based photon counting devices with the merits of low weight, low power consumption and low voltage operation, promising to meet the needs of space particle physics experiments. In this paper, comparative studies of SiPMs and traditional vacuum photomultiplier tubes (PMTs) have been performed regarding the basic properties of dark currents, dark counts and excess noise factors. The intrinsic optical crosstalk effect of SiPMs was evaluated.     

新重丰中子同位素^238Th

利用兰州重离子加速器（ＨＩＲＦＬ）所提供的６０ＭｅＶ／ｕ的＾１８Ｏ离子束照射天然铀靶,通过多核子转移反应生成＾２３８Ｔｈ,由快速放射化学分离技术从铀及其反应产物的合物中分离出钍。使用２台高纯锗（ＨＰＧｅ）探测器对样品的γ（Ｘ）活性进行测量,观测到了＾２３８Ｔｈ的β－衰变子本＾２３８Ｐａ的６３５．０ｋｅＶ和１０６０．５ｋｅＶ２条γ射线峰的增长、衰变行为,利用分析递次衰变的计算机程序对其后一条进行了拟