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1.
The competition between α-decay and spontaneous fission of superheavy nuclei(SHN) is investigated by the generalized liquid drop model(GLDM) and the modified Swiatecki's formula respectively. The theoretical decay modes are in good agreement with the experimental results. Predictions are made for as-yet unobserved superheavy nuclei. The theoretical calculations show that the nuclei~(298)120,~(295)119,~(290)118,~(291)117,~(287)117,~(294)116,~(289)116,~(286)116,~(285)116,~(284)115,~(283)115,~(283)114,~(282)114,~(280)113,~(276)112,~(275)112,~(274)112,~(273)111,~(272)110,~(265)109 may be synthesized experimentally in the near future since they not only have relatively large predicted cross sections but can also be identified via α-decay chains.  相似文献   

2.
3.
Studies on some superheavy nuclei are performed. The α decay energies are calculated by an improved local binding energy formula, and the α decay half-lives are calculated by the Viola-Seaborg formula. Good agreements between theoretical and experimental results are reached.  相似文献   

4.
Studies on some superheavy nuclei are performed. The α decay energies are calculated by an improved local binding energy formula, and the α decay half-lives are calculated by the Viola-Seaborg formula. Good agreements between theoretical and experimental results are reached.  相似文献   

5.
本文考察和研究了将来可能在实验上合成的超重新元素和新核素的基态性质。研究的重点主要放在原子核的alpha衰变能和半衰期。详细比较和讨论了不同理论模型计算的alpha衰变能和半衰期。通过这些计算和比较,从理论上提出了将来在实验上比较容易合成的超重新元素和新核素的性质。理论计算结果可为将来的超重核实验提供理论参考。  相似文献   

6.
We investigate the ground state properties of some superheavy nuclei, which may be synthesized in future experiments. Special emphases are placed on the alpha decay energies and half-lives. The alpha decay energies and half-lives from different theoretical models are compared and discussed comprehensively. Through these calculations and comparisons, the optimal superheavy elements to be synthesized in future experiments are proposed theoretically.  相似文献   

7.
Investigation of the 246Cm spontaneous ternary decay into nearly equal clusters using polyethyleneterephthalate track detectors has been carried out. The possibility of ternary cluster decay has been found out to be of less than 10−6 with respect to all fission modes of 246Cm.  相似文献   

8.
The stability of excited superheavy nuclei (SHN) with 100 Z 134 against neutron emission and fission is investigated by using a statistical model. In particular, a systematic study of the survival probability against fission in the 1n-channel of these SHN is made. The present calculations consistently take the neutron separation energies and shell correction energies from the calculated results of the finite range droplet model which predicts an island of stability of SHN around Z = 115 and N = 179. It turn...  相似文献   

9.
Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Qα value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the DensityDependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.  相似文献   

10.
Theoretical α-decay half-lives of the heaviest nuclei are calculated using the experimental Qα value. The barriers in the quasi-molecular shape path is determined within a Generalized Liquid Drop Model (GLDM) and the WKB approximation is used. The results are compared with calculations using the Density-Dependent M3Y (DDM3Y) effective interaction and the Viola-Seaborg-Sobiczewski (VSS) formulae. The calculations provide consistent estimates for the half-lives of the α decay chains of these superheavy elements. The experimental data stand between the GLDM calculations and VSS ones in the most time.  相似文献   

11.
自发裂变和α衰变是影响超重核稳定性的两个主要因素。为了探索270Ds附近的长寿命的超重核,系统地计算了电荷数在104 ≤ Z ≤ 112范围内的α衰变与自发裂变之间的竞争。采用推广的液滴模型和唯象的解析公式计算了α衰变半衰期。基于包括壳效应和同位旋效应的WKB近似方法估算了相同超重核的自发裂变半衰期,进而预测了未知超重核274-276,279Cn与267-269Ds的衰变模式。The stability of superheavy nuclei (SHN) is controlled mainly by spontaneous fission and α decay processes. To investigate whether long lived SHN could really exist around 270Ds, the competition between α decay and spontaneous fission in the region 104 ≤ Z ≤ 112 are studied systematically. The α decay half-lives are investigated by employing a generalized liquid drop model (GLDM) and phenomenological analytical formula. Calculations of spontaneous fission half-lives for the same SHN are carried out based on the Wenzel-Kramers-Brillouin(WKB) approximation with both the shell effect and the isospin effect included. Decay modes are predicted for the unknown nuclei 274-276,279Cn and 267-269Ds.  相似文献   

12.
Magic islands for extra-stable nuclei in the midst of the sea of fission-instability were predicted to be around Z=114, 124 or, 126 with N=184, and Z=120, with N=172. Whether these fission-survived superheavy nuclei with high Z and N would live long enough for detection or, undergo α-decay in a very short time, remains an open question. α-decay half lives of nuclei with 130≥Z≥100 have been calculated in a WKB framework using density-dependent M3Y interaction with Q-values from different mass formulae. The results are in excellent agreement with the experimental data. Fission survived Sg nuclei with Z=106, N=162 is predicted to have the highest α-decay half life (∼3.2 h) in the Z=106-108, N=160-164 region called small island/peninsula. Superheavy nuclei with Z>118 are found to have α-decay half lives of the order of microseconds or less.  相似文献   

13.
α decay half-lives of some new synthesized superheavy elements, possibly synthesized superheavy elements and decay products are calculated theoretically within the WKB approximation by using microscopic m-nucleus interaction potentials. These nuclear potentials between the α particle and daughter nuclei are obtained by using the double folding integral of the matter density distribution of the α particle and daughter nuclei with a density-dependent effective nucleon-nucleon interaction, in which the zero-range exchange term is supplemented. The calculated α decay half-lives are compared with those of the different models and experimental data. It is shown that the present calculation successfully provides the half-lives of the observed αdecays for some new superheavy elements and therefore gives reliable predictions for α decay of possibly synthesized superheavy elements in future experiments.  相似文献   

14.
The last results of studying radioactive decay of heavy nuclei 232Th, 236U, 236Pu and 242Cm using different dielectric detector types and methods of their development have presented.  相似文献   

15.
We systematically calculate the ground state properties of superheavy even-even nuclei with proton number Z=94–118. The calculations are based on the liquid drop macroscopic model and the microscopic model with the modified single-particle oscillator potential. The calculated binding energies and α-decay energies agree well with the experimental data. The reliability of the macroscopic-microscopic(MM)model for superheavy nuclei is confirmed by the good agreement between calculated results and experimental ones. Detailed comparisons between our calculations and M?ller’s are made. It is found that the calculated results also agree with M?ller’s results and that the MM model is insensitive to the microscopic single-particle potential. Calculated results are also compared with results from relativistic mean-field (RMF) model and from Skyrme-Hatree-Fock(SHF) model. In addition, half-lives, deformations and shape coexistence are also investigated. The properties of some unknown nuclei are predicted and they will be useful for future experimental researches of superheavy nuclei.  相似文献   

16.
A study is made for the search of superheavy nuclei in Marjalahti, Eagle Station and in other pallasite olivines. The olivine crystals are calibrated for heavy ion track lengths by using heavy ion beams from cyclotrons. The calibration for ultra heavy ions which are presently not available with sufficient energy to produce volume tracks in olivine crystals, is based on Katz and Kobetich model of track formation. The length spectrum of volume tracks, revealed by puncturing them with focussed Nd-glass laser beam, is measured and the abundances of different nuclei groups are calculated. Partial annealing has been used at 430°C for 32 hr which eliminates the interfering tracks due to nuclei of atomic numberS ≤ 50. During the scanning 4 cm3 olivine crystals, about 360 long tracks of uranium group as well as two very long tracks have been found. If these tracks belong to superheavy nuclei, the relative abundance of super heavies is found to be 6 × 10−11 in galactic cosmic rays.  相似文献   

17.
包小军 《中国物理C(英文版)》2019,43(5):054105-054105-11
This study investigates the optimal projectile/target combination for the production of new neutron-deficient isotopes of superheavy nuclei(SHN). To this end, the dependence of the evaporation residue cross-section(ERCS) used to synthesize SHN on the mass asymmetry and the isospin of colliding nuclei are analyzed within the dinuclear system(DNS) concept. The predicted ERCSs for the production of new neutron-deficient isotopes of SHN were found to be quite large with the ~(36) S projectile, and the cross-section of SHN decreases slowly with the charge of compound nuclei owing to the increase in their survival probability,. Wsur is not canceled by the decreasing probability, PCN, that the system will evolve from a touching configuration to the compound nucleus in competition with the quasifission process.  相似文献   

18.
K P SANTHOSH 《Pramana》2014,82(4):705-715
We present here, an overview and progress of the theoretical works on the isomeric state α decay, α decay fine structure of even–even, even–odd, odd–even and odd–odd nuclei, a study on the feasibility of observing α decay chains from the isotopes of the superheavy nuclei Z = 115 in the range 271 ≤A ≤ 294 and the isotopes of Z = 117 in the range 270 ≤A ≤ 301, within the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The computed half-lives of the favoured and unfavoured α decay of nuclei in the range 67 ≤Z ≤ 91 from both the ground state and isomeric state, are in good agreement with the experimental data and the standard deviation of half-life is found to be 0.44. From the α fine structure studies done on various ranges of nuclei, it is evident that, for nearly all the transitions, the theoretical values show good match with the experimental values. This reveals that CPPMDN is successful in explaining the fine structure of even–even, even–odd, odd–even and odd–odd nuclei. Our studies on the α decay of the superheavy nuclei 271?294115 and 270?301117 predict 4 α chains consistently from 284,285,286115 nuclei and 5α chains and 3α chains consistently from 288?291117 and 292117, respectively. We thus hope that these studies on 284?286115 and 288?292117 will be a guide to future experiments.  相似文献   

19.
周小红  徐瑚珊 《物理》2019,48(10):640-648
合成新元素拓展元素周期表、探索原子核存在极限是核物理前沿研究领域。相关研究工作涉及的重大物理问题有:存在多少种化学元素?超重元素具有什么样的化学性质?超重元素化学性质是否符合元素周期律的外推预期?最大的核幻数是什么?是否存在稳定的或长寿命的超重核素?在极强库仑场中原子核具有哪些奇特的结构和性质?等等。经过逾半个世纪的不懈努力,元素合成取得了巨大成就,已将周期表从92号扩展至118号元素,完成了周期表上第七周期元素填充。文章回顾了在自然界寻找超重元素的历程,评述了利用人工核反应合成超铀元素和探索理论预言的超重核稳定岛的进展、成果、现状以及目前面临的困难,展望了未来的研究工作,简介了基于国家重大科技基础设施——强流重离子加速器装置开展超重研究的计划。  相似文献   

20.
在双核模型基础上,考虑了熔合与准裂变的竞争,通过数值法求解主方程,计算了50Ti,58Fe+208Pb,209Bi这4个反应系统通过冷熔合反应合成超重元素的激发函数,得到了与实验比较符合的结果.计算了不同入射能量时各角动量分波对熔合概率和超重核存活概率的影响以及对蒸发剩余截面的贡献.这些结果对进一步理解超重核的合成机制有重要意义. 关键词: 超重元素 双核模型 熔合反应 蒸发剩余截面  相似文献   

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