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Exponentially Correlated Hylleraas–Configuration Interaction Studies of Atomic Systems. III. Upper and Lower Bounds to He-Sequence Oscillator Strengths for the Resonance 1S→1P Transition 原子系统的指数相关海勒原子组态相互作用研究。III、 谐振1S的He序列振子强度的上下界→1P过渡
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-07-22 DOI: 10.3390/atoms11070107
J. Sims, B. Padhy, María Belén Ruiz Ruiz
The exponentially correlated Hylleraas–configuration interaction method (E-Hy-CI) is a generalization of the Hylleraas–configuration interaction method (Hy-CI) in which the single rij of an Hy-CI wave function is generalized to a form of the generic type rijνije−ωijrij. This work continues the exploration, begun in the first two papers in this series (on the helium atom and on ground and excited S states of Li II), of whether wave functions containing both linear and exponential rij factors converge more rapidly than either one alone. In the present study, we examined not only 1s2 1S states but 1s2p 1P states for the He I, Li II, Be III, C V and O VII members of the He isoelectronic sequence as well. All 1P energies except He I are better than previous results. The wave functions obtained were used to calculate oscillator strengths, including upper and lower bounds, for the He-sequence lowest (resonance) 1S→1P transition. Interpolation techniques were used to make a graphical study of the oscillator strength behavior along the isoelectronic sequence. Comparisons were made with previous experimental and theoretical results. The results of this study are oscillator strengths for the 1s2 1S→ 1s2p1P He isoelectronic sequence with rigorous non-relativistic quantum mechanical upper and lower bounds of (0.001–0.003)% and probable precision ≤ 0.0000003, and were obtained by extending the previously developed E-Hy-CI formalism to include the calculation of transition moments (oscillator strengths).
指数相关hylleraas -组态相互作用方法(E-Hy-CI)是hylleraas -组态相互作用方法(Hy-CI)的推广,其中hylleraas -组态相互作用方法将hylleraas -组态波函数的单个rij推广为一般类型rijjjije - ωijrij的形式。这项工作继续了本系列前两篇论文(关于氦原子和Li II的基态和激发态)中开始的探索,即包含线性和指数rij因子的波函数是否比单独的任何一个收敛得更快。在本研究中,我们不仅检测了He等电子序列中He I, Li II, Be III, C V和O VII成员的1s2 1S态,还检测了He等电子序列中He I, Li II, Be III, C V和O VII成员的1s2 1S态。除了He I之外,所有的p能量都比以前的结果好。得到的波函数用于计算he序列最低(共振)1S→1P跃迁的振荡强度,包括上界和下界。利用插值技术对振荡器强度沿等电子序列的行为进行了图形化研究。并与以往的实验和理论结果进行了比较。本研究结果为1s2 1S→1s2p1P He等电子序列的振子强度,具有严格的非相对论量子力学上界和下界为(0.001-0.003)%,可能精度≤0.0000003,并通过扩展先前开发的E-Hy-CI形式来包含跃迁矩(振子强度)的计算而得到。
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引用次数: 0
Towards Understanding Incomplete Fusion Reactions at Low Beam Energies: Modified Sum Rule Model 理解低束流能量下的不完全聚变反应:修正和规则模型
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-07-21 DOI: 10.3390/atoms11070106
Bhushan Bhujang, Pragya Das
We investigated the enhanced production of nuclei formed via incomplete fusion (ICF) reactions near and above the Coulomb barrier energies (5–8 MeV/A). The cross-sections of the evaporation residues formed in the reactions—11B+124Sn, 10B+124Sn and 11B+122Sn—were measured using off-line gamma-ray spectrometry. The sum rule model (SRM) by Wilczyński et al. predicted the cross-section values too low compared to our experimental results. In earlier studies, the same model has been very successful in explaining ICF reactions at high beam energies (>10 MeV/A). We, therefore, modified the SRM, specifically incorporating the energy dependence in the definition of critical angular momentum ℓcr. The resulting modified SRM gave an improved theoretical estimate for the reactions we studied.
我们研究了在库仑势垒能量(5–8MeV/A)附近和之上通过不完全聚变(ICF)反应形成的核的增强产生。在反应中形成的蒸发残留物11B+124Sn、10B+124Sn和11B+122Sn的横截面是使用离线伽马射线光谱法测量的。Wilczyński等人的总和规则模型(SRM)预测,与我们的实验结果相比,横截面值过低。在早期的研究中,同样的模型在解释高能束(>10MeV/A)下的ICF反应方面非常成功。因此,我们修改了SRM,特别是在临界角动量的定义中加入了能量依赖性ℓcr.由此得到的改进的SRM对我们研究的反应给出了改进的理论估计。
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引用次数: 0
On Invariant Vectors in the Presence of Electric and Magnetic Fields 电场和磁场存在下的不变向量
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-07-20 DOI: 10.3390/atoms11070105
J. Pain
In this non-exhaustive review, we discuss the importance of invariant vectors in atomic physics, such as the Laplace–Runge–Lenz vector, the Redmond vector in the presence of an electric field, the Landau–Avron–Sivardièrevector when the system is subject to a magnetic field, and the supergeneralized Runge–Lenz vector for the two-center problem. The application to the Stark and Zeeman effects are outlined. The existence of constants of motion in the charge-dyon system is also briefly mentioned.
在这篇不详尽的综述中,我们讨论了不变向量在原子物理中的重要性,如拉普拉斯-龙格-伦茨向量,电场存在下的雷德蒙向量,系统受磁场作用时的朗道-阿夫龙-西瓦迪矢量,以及双中心问题的超广义龙格-伦茨矢量。概述了Stark和Zeeman效应的应用。简要地讨论了电荷-dyon系统中运动常数的存在性。
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引用次数: 0
Role of Simple Spatial Gradient in Reinforcing the Accuracy of Temperature Determination of HED Plasma via Spectral Line-Area Ratios 简单空间梯度在提高谱线面积比法测定HED等离子体温度精度中的作用
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-07-12 DOI: 10.3390/atoms11070104
G. Riggs, M. Koepke, T. Lane, T. Steinberger, P. Kozlowski, I. Golovkin
We report on the simulation of temperature gradients in tamped NaFMgO target-foil plasma, heated and backlit by z-pinch dynamic hohlraum radiation. Our approach compares the spectroscopic output of a collisional-radiative model (prismspect) with soft X-ray absorption spectra collected on Sandia National Laboratories’ (SNL) Z Pulsed Power Facility. The pattern of minimum χ2 is seen to agree with an efficient, three-parameter model. Results show that a negligible gradient in electron temperature Te is consistent with experimental data, justifying the assumptions of previous work. The predicted sensitivity of line spectra to the gradient-aligned profile of Te is documented for each spectral feature, so that the line-area ratio between a pair of spectral features may be assessed as a proxy for the existence and quantification of such gradients.
本文报道了用z-pinch动态热腔辐射加热和背光的压缩NaFMgO靶箔等离子体中的温度梯度模拟。我们的方法将碰撞辐射模型(棱镜)的光谱输出与桑迪亚国家实验室(SNL) Z脉冲功率设备收集的软x射线吸收光谱进行了比较。最小χ2的模式与有效的三参数模型一致。结果表明,电子温度Te的梯度可以忽略不计,与实验数据一致,证明了先前工作的假设是正确的。对于每个光谱特征,线光谱对梯度对准的Te剖面的预测灵敏度被记录下来,因此,可以评估一对光谱特征之间的线面积比,作为这种梯度存在和量化的代理。
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引用次数: 0
Role of Gas Pressure in Quasi-Phase Matching in High Harmonics Driven by Two-Color Laser Field 气压在双色激光场驱动的高次谐波准相位匹配中的作用
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-07-07 DOI: 10.3390/atoms11070103
S. Stremoukhov
The results of a study on the effect of pressure in a medium consisting of a set of gas jets separated by vacuum gaps, interacting with two-color laser fields formed by the fundamental and the second harmonics of a laser, are presented herein. It has been demonstrated that a decrease in pressure leads to a shift in the region of harmonics where quasi-phase matching (QPM) occurs towards shorter wavelength radiation, accompanied by an increase in the efficiency of amplification of these harmonics. A feature of this process is the identical power-law character of the shift in the region and the increase in the efficiency of harmonic QPM amplification. Additionally, the study presents the results of the effect of inaccurately setting the width of the gas jets on the shape of the spectrum of harmonic QPM amplification.
本文研究了由真空间隙分隔的一组气体射流组成的介质中压力与由激光基次谐波和次谐波形成的双色激光场相互作用的结果。结果表明,压力的减小会导致准相位匹配(QPM)发生的谐波区域向短波辐射方向移动,同时这些谐波的放大效率也会增加。该过程的一个特点是区域内位移具有相同的幂律特性,谐波QPM放大效率提高。此外,本文还研究了射流宽度设置不准确对谐波QPM放大频谱形状的影响。
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引用次数: 0
Variational Approaches to Two-Dimensionally Symmetry-Broken Dipolar Bose–Einstein Condensates 二维对称破缺偶极玻色-爱因斯坦凝聚的变分方法
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-07-06 DOI: 10.3390/atoms11070102
Yongchang Zhang, F. Maucher
It has been shown that quantum fluctuations in dipolar Bose–Einstein condensates (BECs) lead to a stabilisation against collapse, thereby providing access to a range of states with different symmetries. In this paper, we discuss variational approaches to approximately determine the phase diagrams for dipolar BECs that are trapped along the dipolar orientation and otherwise infinite in the perpendicular direction (thermodynamic limit). The two-dimensional symmetry breaking occurs in the plane perpendicular to the polarisation axis. We show in detail how to derive approximate expressions that are valid in a region where modulations to an otherwise unmodulated perfect superfluid emerge gradually with a small modulation amplitude and compare the results to rigorous numerics.
已经证明,偶极玻色-爱因斯坦凝聚体(BECs)中的量子涨落导致抗坍缩的稳定,从而提供了一系列具有不同对称性的状态。在本文中,我们讨论了变分方法来近似确定沿偶极方向捕获和在垂直方向(热力学极限)上无限捕获的偶极bec的相图。二维对称破缺发生在垂直于偏振轴的平面上。我们详细展示了如何推导出在一个区域内有效的近似表达式,在这个区域内,对一个其他未调制的完美超流体的调制以一个小的调制幅度逐渐出现,并将结果与严格的数值进行比较。
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引用次数: 1
Mean-Field Description of Cooperative Scattering by Atomic Clouds 原子云协同散射的平均场描述
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-06-29 DOI: 10.3390/atoms11070101
N. Piovella
We present analytic expressions for the scattering of light by an extended atomic cloud. We obtain the solution for the mean-field excitation of different atomic spherical distributions driven by a uniform laser, including the initial build up, the steady state and the decay after the laser is switched off. We show that the mean-field model does not describe subradiant scattering due to the negative interference of the photons scattered by N discrete atoms.
我们提出了扩展原子云对光散射的解析表达式。我们得到了均匀激光驱动下不同原子球形分布的平均场激发的解,包括初始积累、稳态和关闭激光后的衰减。我们证明了平均场模型不能描述由N个离散原子散射的光子的负干涉引起的次辐射散射。
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引用次数: 1
Decay of Persistent Currents in Annular Atomic Superfluids 环形原子超流体中持续电流的衰减
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-06-20 DOI: 10.3390/atoms11080109
K. Xhani, G. Del Pace, F. Scazza, G. Roati
We investigate the role of vortices in the decay of persistent current states of annular atomic superfluids by solving numerically the Gross–Pitaevskii equation, and we directly compare our results with the 6Li experiment at LENS data. We theoretically model the optical phase-imprinting technique employed to experimentally excite finite-circulation states in the Bose–Einstein condensation regime, accounting for imperfections of the optical gradient imprinting profile. By comparing simulations of this realistic protocol to an ideal imprinting, we show that the introduced density excitations arising from imperfect imprinting are mainly responsible for limiting the maximum reachable winding number wmax in the superfluid ring. We also investigate the effect of a point-like obstacle with variable potential height V0 on the decay of circulating supercurrents. For a given obstacle height, a critical circulation wc exists, such that for an initial circulation w0 larger than wc the supercurrent decays through the emission of vortices, which cross the superflow and thus induce phase slippage. Higher values of the obstacle height V0 further favor the entrance of vortices, thus leading to lower values of wc. Furthermore, the stronger vortex-defect interaction at higher V0 leads to vortices that propagate closer to the center of the ring condensate. The combination of both these effects leads to an increase in the supercurrent decay rate for increasing w0, in agreement with experimental observations.
我们通过数值求解Gross–Pitaevskii方程,研究了涡旋在环形原子超流体持续电流状态衰变中的作用,并将我们的结果与LENS数据下的6Li实验进行了直接比较。我们对用于实验激发Bose–Einstein凝聚态中有限循环态的光学相位印迹技术进行了理论建模,解释了光学梯度印迹轮廓的缺陷。通过将这种现实协议的模拟与理想印迹进行比较,我们表明,由不完美印迹引起的引入的密度激发主要是限制超流体环中最大可达绕组数wmax的原因。我们还研究了具有可变势能高度V0的点状障碍物对循环超流衰减的影响。对于给定的障碍物高度,存在临界循环wc,使得对于大于wc的初始循环w0,超流通过涡流的发射而衰减,涡流穿过超流,从而引起相位滑移。障碍物高度V0的较高值进一步有利于涡流的进入,从而导致wc的较低值。此外,在更高的V0处更强的涡流-缺陷相互作用导致涡流传播得更靠近环形冷凝物的中心。这两种效应的结合导致超电流衰减率随着w0的增加而增加,这与实验观察结果一致。
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引用次数: 3
Scattering of X-ray Ultrashort Laser Pulses on Bound Electrons in Dense Plasma x射线超短激光脉冲在致密等离子体中束缚电子上的散射
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-06-16 DOI: 10.3390/atoms11060100
E. Khramov, V. Astapenko
We considered the resonance scattering of ultrashort laser pulses (USLP) on the bound electrons of hydrogen-like ions in a dense plasma. A process description was proposed in terms of full scattering probability during the time of pulse action. Dense plasma’s effect was demonstrated at the resonance scattering cross-section spectrum, and the probability dependence on USLP carrier frequency and duration was obtained for the cases of isolated ions and ions in a dense plasma.
研究了致密等离子体中超短激光脉冲对类氢离子束缚电子的共振散射。提出了用脉冲作用时的全散射概率来描述过程的方法。在共振散射截面谱上证明了致密等离子体的效应,得到了在致密等离子体中分离离子和离子的情况下,USLP载流子频率和持续时间的概率依赖关系。
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引用次数: 0
Neutron Interferometer Experiments Studying Fundamental Features of Quantum Mechanics 研究量子力学基本特征的中子干涉仪实验
IF 1.8 Q3 PHYSICS, ATOMIC, MOLECULAR & CHEMICAL Pub Date : 2023-06-15 DOI: 10.3390/atoms11060098
Armin Danner, H. Lemmel, R. Wagner, S. Sponar, Y. Hasegawa
Quantum theory provides us with the best account of microscopic components of matter as well as of radiation. It was introduced in the twentieth century and has experienced a wide range of success. Although the theory’s probabilistic predictions of final experimental outcomes is found to be correct with high precision, there is no general consensus regarding what is actually going on with a quantum system “en route”, or rather the perceivable intermediate behavior of a quantum system, e.g., the particle’s behavior in the double-slit experiment. Neutron interferometry using single silicon perfect crystals is established as a versatile tool to test fundamental phenomena in quantum mechanics, where an incident neutron beam is coherently split in two or three beam paths with macroscopic separation of several centimeters. Here, we present quantum optical experiments with these matter-wave interferometers, studying the effect of the quantum Cheshire Cat in some variants, the neutron’s presence in the paths of the interferometer as well as the direct test of a commutation relation. To reduce disturbances induced by the measurement, the interaction strength is lessened and so-called weak interactions are exploited by employing pre- and post-selection procedures. All results of the experiments confirm the predictions of quantum theory; the observed behaviors of the neutron between the pre- and post-selection in space and time emphasize striking and counter-intuitive aspects of quantum theory.
量子理论为我们提供了对物质微观成分和辐射的最佳解释。它是在二十世纪引入的,并取得了广泛的成功。尽管该理论对最终实验结果的概率预测被发现是准确无误的,但对于“途中”量子系统的实际情况,或者更确切地说,量子系统的可感知中间行为,例如双缝实验中粒子的行为,还没有达成普遍共识。使用单晶硅完美晶体的中子干涉测量法是一种测试量子力学基本现象的通用工具,在量子力学中,入射中子束相干分裂为两个或三个束路,宏观间隔为几厘米。在这里,我们用这些物质波干涉仪进行了量子光学实验,研究了量子Cheshire Cat在某些变体中的影响、中子在干涉仪路径中的存在以及换向关系的直接测试。为了减少测量引起的干扰,通过采用预选择和后选择程序来减少相互作用强度,并利用所谓的弱相互作用。所有实验结果都证实了量子理论的预言;在空间和时间上观察到的中子在前后选择之间的行为强调了量子理论的惊人和反直觉方面。
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引用次数: 1
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Atoms
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