Nuclear Science and Techniques分享 NST报道核科学与技术研究领域的科学发现、技术创新和重要成果



已有 1562 次阅读 2022-12-2 11:42 |系统分类:论文交流

Article title: Systematics on production of superheavy nuclei Z = 119 − 122 in fusion-evaporation reactions


DOI: 10.1007/s41365-021-00946-3

One sentence summary:


This study highlighted the effective techniques to produce superheavy nuclei with Z = 119 – 122.



The Novelty (What)


While attempting to produce superheavy nuclei (SHN) with Z = 119 – 122 in the fusion-evaporation reactions within the dinuclear system (DNS) model, this study discovered that 44Sc+252Es was the optimal combination in the 3n channel with a cross-section of 3 pb. Maximum cross-sections of the evaporation residues (ER) were found in the (2-5)n evaporation channels, i.e., approximately 1 pb in the 3n evaporation channel. The results were in good agreement with the experimental data from Dubna. The SHN were produced by bombarding the actinide nuclides with the transition elements from Period 4. Since the orientations were the main determining factor of the ER cross-sections, all possible collision orientations were included by applying the Monte Carlo approach in the nucleon transfer process. Using these results as a reference, future investigations should be conducted to uncover other potentially promising reaction mechanisms to produce SHN.

本研究在双核系统(DNS)模型的聚变-蒸发反应中试图产生Z=119-122的超重核(SHN)时,发现在截面为3Pb3n通道中,t 44Sc+252Es是最优的组合。 蒸发残留物(ER)的最大截面在(2-5) n个蒸发通道中,即在3n个蒸发通道中约为1 Pb 结果与Dubna的实验数据吻合较好。 SHN是由周期4的过渡元素轰击锕系核素产生的。 由于取向是ER截面的主要决定因素,所以用Monte Carlo方法将核子转移过程中所有可能的碰撞取向都包括在内。 参考这些结果,未来可以进行相关的研究,以发现其他可以产生SHN的潜在的、有希望的反应机制。



The Background (Why)


SHN (Z ≥ 106) are given rise by the strong binding shell effect when the Coulomb repulsion is overcome. The initial synthesis of SHN nearly half a decade ago involved multinucleon transfer reactions in collisions of two actinide nuclei. Meanwhile, the formation dynamics of SHN in massive fusion and multinucleon transfer reactions have been the main focus. Hence, systematic studies on the production of SHN are needed to predict the reaction mechanism, including optimal projectile-target combinations. This study conducted a comprehensive study on the fusion dynamics of the formation of superheavy nuclei within the DNS model by adopting the Monte Carlo approach. The findings shed some light on the fusion-evaporation reactions applied for synthesizing SHN with Z = 119 – 122, bringing SHN research one step closer to discovering “island of stability.”

当克服库仑斥力时,强束缚壳层效应引起SHN(z≥106) 近五年前,合成SHN的最初过程涉及到两个锕系原子核的碰撞中的多核转移反应。 同时,大体积聚变和多核转移反应中SHN的形成动力学一直是人们关注的焦点。 因此,需要对SHN的产生进行系统的研究,以预测反应机理,包括最佳的弹靶组合。 本研究采用蒙特卡罗方法,在DNS模型内对超重核形成的聚变动力学进行了全面的研究。 这一发现为合成Z=119-122SHN的熔融-蒸发反应提供了一些线索,使SHN研究离发现稳定岛又近了一步。

The SDG impact (Big Why)


Superheavy elements (SHE) are rare naturally and only exist briefly under highly controlled circumstances. Their common applications include smoke detectors (americium), neutron radiography and neutron interrogation (curium and californium), and nuclear weapons (plutonium). Thus, besides exploring the concept of “magic numbers” and “island of stability,” a better understanding of the formation mechanism of SHE could lead to a significant advancement of nuclear technology. By focusing on the synthesis of various SHN via fusion-evaporations reactions, the output of this in-depth study contributed to the progress of SHN synthesis. Therefore, it fulfilled UNSDG9: Industry, Innovation & Infrastructure.

超重元素(SHE)是天然稀有元素,只有在高度控制的情况下才会短暂存在。 它们的常见应用包括烟雾探测器(镅)、中子射线照相和中子询问(铈和加利福尼亚)以及核武器(钚)。 因此,除了探索幻数稳定岛的概念外,更好地理解SHE的形成机制可能会导致核技术的重大进步。 通过聚变-蒸发反应合成各种SHN,本研究的成果为SHN合成的进展做出了贡献。 因此,它支持了UNSDG9:工业、创新和基础设施。

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