Theoretical study on fusion dynamics and evaporation residue cross sections for superheavy elements

The nuclear dynamical deformation,the fusion probability and the evaporation residue(ER) cross sections for the synthesis of superheavy nuclei are studied with the di-nuclear system model and the related dynamical potential energy surface.The intrinsic energy and the maximum dynamical deformations for48Ca+248Cm are calculated.The effect of dynamical deformation on the potential energy surface and fusion is investigated.It is found that the dynamical deformation influences the potential energy surface and fusion probability significantly.The dependence of the fusion probability on the angular momentum is investigated.The ER cross sections for some superheavy nuclei in48Ca induced reactions are calculated and it is found that the theoretical results are in good agreement with the experimental results.

Cr-induced fusion reactions to synthesize superheavy elements

We investigated ^(50,52-54)Cr-induced fusion reactions for the synthesis of the superheavy element in the 104≤Z≤122 range.The cross sections produced in this investigation using ^(54)Cr projectiles were compared with those obtained in prior experiments.The estimated cross sections from this analysis are consistent with the findings of prior studies.From the current study,the predicted cross section was found to be 42fb at 236 MeV for ^(53)Cr+^(243)Am,23.2 fb at 236 MeV for ^(54)Cr+^(247)Cm,95.6 fb at 240 MeV for ^(53)Cr+248Bk,and 1.33 fb at 242 MeV for ^(53)Cr+250Cf.Consequently,these projected cross sections with excitation energy and beam energy will be useful in future Cr-induced fusion reaction investigations.

Activation Cross Sections for Generation of Long-Lived Radionuclides

A summary is given on the activation cross section measurements performed byChina Institute of Atomic Energy（CIAE）,Lanzhou University（LU）,Peking University（PU）and Sichuan University（SU）from 1989 to 1994 for generation of long-lived radionuclides of im-portance in fusion reactor technology.The cross sections are measured for the reactions 109Ag（n,2n）108Agm,151Eu（n,2n）150Eum,153Eu（n,2n）152Eu8,159Tb（n,2n）158Tb,179Hf（n,2n ）178Hfm2,182W（n,n′α）178Hfm2,187Re（n,2n）186Rem and 193Ir（n,2n）192Irm2at 14 MeV,109Ag（n,2n）108Agm,151Eu（n,2n）150Eum,159Tb（n,2n）158Tb and 179Hf（n,2n）178Hfm2at 9.5 and 9.9 MeV,and98Mo（n,γ）199Mo（β-）→99Tc,165Ho（n.γ）166Hom and 151Eu（n,γ）152Eu8 in the energy range of20～1100 keV.Some of them were calculated by systematic and HFTT code,which was basedon the compound nucleus evaporation and the preequilibrium exciton model.

Theoretical determination of (d, n) and (d, 2n) excitation functions of some structural fusion materials irradiated by deuterons

Nuclear fusion is one of the world's primary energy sources. Studies on the structural fusion materials are very important in terms of the development of fusion technology. Chromium, nickel, zinc, scandium, titanium,and yttrium are important structural fusion materials. In this paper, for use in nuclear science and technology applications, the excitation functions of the ^(50)Cr(d, n)^(51)Mn,^(58)Ni(d, n)^(59)Cu,^(64)Zn(d, n)^(65)Ga,^(66)Zn(d, n)^(67)Ga,^(45)Sc(d,2n)^(45)Ti,^(47)Ti(d, 2n)^(47)V,^(48)Ti(d, 2n)^(48)V, and ^(89)Y(d, 2n)^(89)Zr nuclear reactions were investigated. The calculations that are based on the pre-equilibrium and equilibrium reaction processes were performed using ALICE–ASH computer code. A comparison with geometry-dependent hybrid model has been made using the initial exciton numbers n_0= 4–6 and level density parameters α = A/5; A/8; A/11.Also, the present model-based calculations were compared with the cross sections obtained using the formulae suggested from our previous studies. Furthermore, the cross section results have been compared with TENDL data based on TALYS computer code and the measured data in the literature.

Effects of Isospin Equilibrium on Cold Fusion of Superheavy Nuclei

The neutron flow model predicts that neutrons start to flow freely between the approaching nuclei ^58Fe and ^208 pb at s=3fm, a length in which the effective surfaces of these nuclei are 3 fm apart. As a result of neutron flow, the N/Z value rapidly reaches an equilibrium distribution. Meanwhile the system, originally in the fusion valley, is injected into the asymmetric fission valley. The dynamic process of the composite nucleus in the asymmetric fission valley is treated with a two-parameter Smoluchowski equation. It is shown that the probability to overcome the asymmetric fission barrier and to achieve compound nucleus configuration, hence the fusion cross section is obviously suppressed due to the effect of isospin equilibrium.

Predictions for production of superheavy nuclei with Z=105–112 in hot fusion reactions

Abstract The effects of mass asymmetry on the production of superheavy nuclei(SHN),within the dinuclear system model,are investigated in this study.It is observed that the fusion probability decreases with decreasing mass asymmetry.A total of 192 possible combinations of projectiles from O to Ti and targets with half-lives longer than30 days for producing SHN^(264)Db,^(265)Db,^(267)Sg,^(268)Bh,268Sg,^(269)Bh,^(271)Hs,^(271)Mt,^(272)Hs,^(272)Mt,^(273)Mt,^(274)Ds,275Ds,^(275)Rg,^(276)Ds,^(276)Rg,^(277)Rg,^(278)Cn,^(279)Cn,and^(280)Cn are examined.Further,the optimal combinations and incident energies for synthesizing these nuclei are predicted.Most of the cross sections for production of SHNare larger than 10 pb;therefore,the process can be carried out with the available experimental equipment.

Effect of tritium reduction in determining energy gain by using R-matrix method direct laser fusion in D-T reaction

The laser fusion criterion is known as the ρR-Criterion, also called high-gain condition. This parameter is temperature dependent and can be calculated by R-matrix method. This method is applied for determining improved fusion cross-section for the reactions T(d,n)4He, 3He(d,p)4He, D(d,p)T, D(d,n)3He. In this paper the time dependent reaction rate equations for fusion reaction T(d,n)4He are solved and by using the obtained results we computed the fu- sion power density, energy gain versus temperature and ρR-parameter. The obtained results show that a suitable com- bination may be a deuterium fraction fD=0.65 and fT=0.35 which would lead 30% reduction in the tritium content of the fuel mixture, and this choice would not change the energy gain value very much. Finally, the obtained energy gain for D-T reaction by using R-matrix is in good agreement with other theories.

基于多源数据融合的地铁隧道断面收敛精准测量研究

为精准完成地铁隧道断面收敛变形测量,提出基于多源数据融合的地铁隧道断面收敛精准测量方法。该方法利用激光扫描仪和全站仪,采集隧道断面的点云数据和高程数据,通过联邦学习算法融合采集的隧道多源数据后,利用隧道结构中心线方法批量切片处理融合后的数据,快速提取地铁隧道断面,在此基础上,对其进行转换后构建隧道断面独立平面坐标,并拟合隧道半径结果和设计结果之间的差值,获取断面收敛变形量。测试结果显示:该方法具有较好的隧道数据采集能力,依据采集结果有效完成隧道断面椭圆度计算,完成隧道断面拟合,计算隧道不同角度下的变形量,角度在100°和340°时,断面收敛变形量最大,最大值达30.1 mm。

基于两阶段注意力层Transformer的弹道目标多站融合识别

多站弹道目标融合识别旨在利用多个雷达站点信息的互补性提升弹道目标识别性能,而传统多站下弹道目标识别方法未直接考虑多站数据间的关联特性,难以取得准确、稳健的识别性能。针对多站下基于雷达散射截面积(RCS)高速飞行目标的识别问题,提出了一种基于两阶段注意力的弹道目标多站融合识别方法。首先,在现有的Transformer模型上添加维度分段模块将多站雷达数据嵌入于二维向量中,保留站内数据时序及站间关联信息;然后,添加了两阶段注意力层,有效地捕获站内时序信息及跨站维度的依赖关系;最后,基于仿真动态RCS数据模拟多站场景开展了融合识别实验。实验结果表明该方法能够有效提升多站条件下的弹道目标识别性能。

Nuclear matter incompressibility effect on the cross-section of fusion reactions with a weakly bound projectile

Fusion reactions with a weakly bound projectile are studied using the double-folding model along with a repulsive interaction modifying term. Using this modified potential, including nuclear matter incompressibility effects, the fusion reaction cross sections and suppression parameters are calculated for 9Be＋209Bi, 208spb, 29Si and 27A1 reactions. The results show that applying these effects at agreement between the calculated and experimental cross sections parameter. energies near the Coulomb barrier improves the and modifies the mean values of the suppression

核聚变中的核物理问题

采用标准的量子力学方位阱加库伦位垒,计算了氘 氚聚变截面。给出了0.2～280keV能区内的截面数据,与实验符合得很好。此模型说明了不可用Breit Wigner公式来讨论轻核聚变反应。将此模型运用于束缚态带电粒子之间的核反应,可以解释一系列"异常现象",并展现了开发不带强放射性的聚变能的前景。

QMD模型的改进及其在低能重离子反应中的应用

丰中子核以及重核熔合机制的研究以及中能重离子碰撞中多重碎裂的研究都迫切需要一个统一的、自洽的微观动力学模型.经过对量子分子动力学模型进行根本的改进,发展了一个新的、适用于低能以及中能重离子反应的统一描述的微观动力学模型.改进的量子分子动力学(ImQMD)模型能够将整个熔合反应过程中的动力学效应、同位旋效应以及弹靶质量不对称效应等比较全面地、自洽地考虑进来,从而给熔合反应的研究提供了一个新的途径.ImQMD模型能够很好地再现一系列核的基态性质以及10多个熔合反应的激发函数(包括丰中子核熔合体系以及实验最新测量的132Sn+64Ni熔合体系).此外还运用该模型初步探索了重核熔合过程中复合体系的寿命与体系的入射能量、体系大小以及体系的中子质子比的依赖关系.

^(40, 48)Ca+^(90, 96)Zr近垒熔合反应的动力学研究

发展了一种改进的量子分子动力学模型,并用这一模型研究了40,48Ca+90,96Zr的近垒熔合反应.改进的量子分子动力学模型能很好地描述一系列核,从6Li到208Pb,的基态性质及它们的时间演化.在相同参数下计算得到的40Ca+90Zr以及40Ca+96Zr这两个熔合反应的激发函数与实验结果都符合得相当好.在分析丰中子核熔合截面增强机制中,发现丰中子核熔合反应初始阶段颈部的N/Z值明显偏大,促使反应中动态位垒降低,从而引起了丰中子核反应熔合截面的增强.

超重核合成中的靶核形变效应

利用额外推力模型研究了48Ca+238U超重核合成过程中的靶核形变效应.计算表明,在近垒和垒下能区,靶核形变使超重核合成截面明显增强.对于48Ca+238U反应,由于靶核形变蒸发残余截面增大了几倍.同时与球形靶核相比,形变靶核时蒸发残余激发函数的峰位移向较低能量.

雷达目标特征数据库在雷达组网仿真上的应用

传统雷达组网仿真中,认为目标为点目标,目标的RCS(Radar Cross Section)是一个常数;实际上目标的RCS是随雷达频率、目标相对雷达姿态变化的函数。该文通过对复杂雷达目标进行电磁建模,计算其在各姿态和各频点的RCS数据,把计算结果存储在数据库中建立雷达目标特征数据库。建立了雷达组网仿真系统,系统由主控计算机、雷达目标特征数据库、若干雷达站组成。仿真结果表明:利用雷达目标特征数据库获得雷达在每个时刻观察的RCS比传统的把飞行器RCS当成常数,进行雷达组网仿真,仿真结果更接近实际的情况;通过多个雷达组成雷达网进行数据融合共同探测目标,可以大大提高雷达对目标的检测概率。

超重元素(新核素)合成研究进展情况分析和展望

本文在介绍和分析国际、国内在超重元素 (新核素 )合成实验研究与理论研究进展情况的基础上对我国今后如何从理论与实验的结合上开展超重元素 (核 )合成研究工作提出一些看法和建议 。

超重元素合成反应机制研究

回顾了超重元素研究的现状和超重元素合成反应机制研究的发展,指出目前超重元素合成研究中存在的困难和对超重余核鉴别的一些设想.对近对称反应系统的熔合反应机制进行了较深入的讨论,建议对这类反应生成复合核的截面进行理论和实验上的研究.

熔合势垒厚度对熔合截面的影响

用多级势近似的方法计算了不同熔合势垒厚度对反应体系16O+208Pb熔合几率的影响.计算表明,对垒下熔合,随着势垒厚度的增加,隧穿几率快速下降,入射能越低下降的越快;对垒上熔合,隧穿几率会随着势垒厚度的增加而增加,入射能越大上升的越快.如果选择适当的势垒厚度,可以使计算结果与实验数据符合的更好.这为进一步澄清熔合反应中熔合势垒的形状、极端垒下重离子熔合机制等相关研究提供参考.

汕头地区城乡中小学生双眼水平融合力的横断面调查

目的:通过三棱镜融合储备力试验检查了解正常青少年的双眼水平融像性聚散范围。方法:横断面研究,随机分层整群抽样调查。在汕头地区调查9所城乡中小学校,共7 537人。从体检学生中抽取双眼正常学生4 012名,用排状三棱镜检查双眼近距水平聚散力,在融像破裂点记录三棱镜度数。按集合与散开、年龄、性别等因素对结果作分层统计分析。结果:总体检人数7 464人,其中双眼祼眼视力≥0.8为4 012人,占体检人数的53.75%;研究对象的双眼散开运动范围平均为15.87~△±10.74~△,双眼集合运动范围平均为26.41~△±12.04~△;4~8岁组及9~11岁组的双眼集合与散开运动范围均高于12~20岁组,差异有统计学意义(P<0.05);女性的双眼集合能力高于男性。结论:在本调查人群中,双眼集合运动的储备力高于散开运动;年龄越小,双眼异向运动的储备力越强。

组网雷达对隐身飞机的探测概率研究

设计了隐身飞机采取S机动通过分层部署式、环形雷达网的作战场景,得到了飞机相对每部雷达的动态雷达散射截面积;然后,采用swerlingI型雷达检测模型,计算了单部雷达的检测概率;最后,采用秩K判断准则,得到不同秩下,组网雷达的联合探测概率和虚警概率。当秩K=2时的六雷达组网系统,具有较高的检测概率,较低的雷达虚警概率。该文对于雷达组网对隐身飞机的探测、隐身飞机突防具有一定的指导意义。