Comparison of neutron resonance spacings with microscopic theory for spherical nuclei

The nuclear level spacings determined from neutron resonance experiments for nuclei with 20 ≦ A ≦ 148 and 181 ≦ A ≦ 209 are compared with spacings calculated for spherical nuclei with a microscopic theory which includes the nuclear pairing interaction. Single particle levels of Seeger et al. and Nilsson et al. are used in the calculations. The gross features of the experimental data due to nuclear shells are reproduced with the microscopic theory. In addition, the absolute agreement between experiment and theory is reasonable (67 % of the 151 cases examined agree to within a factor of 2) in view of uncertainties in the experimental data, the theoretical single particle levels and the pairing strength. Values of the spin cutoff parameter σ²(E), calculated with a microscopic theory, are included also for several doubly even nuclei and discussed in terms of nuclear shells.     

Multicluster solutions to a multinucleon problem and clustering phenomena

Various concepts of clustering phenomena are discussed. Precise multicluster solutions constructed by the present authors for an A-nucleon problem whose dynamical properties are described by a generalized Elliott Hamiltonian are used as a mathematical formalism of the theory of clustering phenomena in nuclei. It is shown that qualitative features of various clustering phenomena, such as the very fact of the existence of cluster states, their classification, and selectivity of reactions that populate them, are explained within the concept being discussed. The 2α + bineutron three-cluster states of the ¹⁰Be nucleus are classified, and their spectrum is calculated. It is demonstrated that the results of these calculations are in good agreement with experimental data.     

Charge radii and quadrupole-deformation parameters of high-spin isomers

Experimental data on the differences of charge radii of nuclei in the ground and high-spin isomeric states are surveyed. High-resolution laser-spectroscopy methods were used for measurements. The results obtained for the differences of these radii by two methods—from measurements of isomeric shifts of the levels of atoms containing the nuclei being studied and from measurements of their quadrupole moments in both states under the assumption that the differences of the radii are determined by the difference in their quadrupole deformations—were compared. Two-particle isomers in odd—odd nuclei, isomers formed upon the break of one or several nucleon pairs, and isomers featuring the 1i _13/2 configuration of the odd neutron in mercury nuclei were considered. The observed distinctions between the aforementioned differences of charged radii are discussed for isomeric states of different nature.     

Synthesis of superheavy elements at the Dubna gas-filled recoil separator

A survey of experiments at the Dubna gas-filled recoil separator (Laboratory of Nuclear Reactions, JINR, Dubna) aimed at the detection and study of the “island of stability” of superheavy nuclei produced in complete fusion reactions of ⁴⁸Са ions and ²³⁸U–²⁴⁹Cf target nuclei is given. The problems of synthesis of superheavy nuclei, methods for their identification, and investigation of their decay properties, including the results of recent experiments at other separators (SHIP, BGS, TASCA) and chemical setups, are discussed. The studied properties of the new nuclei, the isotopes of elements 112–118, as well as the properties of their decay products, indicate substantial growth of stability of the heaviest nuclei with increasing number of neutrons in the nucleus as the magic number of neutrons N = 184 is approached.     

Application of the vector ε and ρ extrapolation methods in the acceleration of the Richardson-Lucy algorithm

The vector ε and ρ extrapolation methods are applied in accelerating the convergence of the Richardson-Lucy (R-L) algorithm and its damped version. The theory and implementation are discussed in detail, and relevant numerical results are given, including the cases of noise-free images and images corrupted by the Poisson noise. The results show that the vector ε and ρ extrapolations of 9 orders can speed the convergence quite efficiently, and the ρ(9) method is more powerful than the ε(9) method for noisy degraded images. The extra computation burden due to the extrapolation is limited, and is well paid back by the accelerated convergence. The performances of these two methods are compared with the famous automatic acceleration method. For noise-free degraded images, the vector ε(9) and ρ(9) methods are more stable than the automatic method. For noisy degraded images, the damped R-L algorithm accelerated by vector ρ(9) or automatic methods is more powerful, and the instability of the automatic method is restrained by the damping strategy. We explain the instability of the method in accelerating the normal R-L algorithm by the numerical noise due to its frequent applications in the run.     

基于I-BGLAM纹理和光谱融合的高光谱显微成像木材树种分类

为了提高木材树种分类的正确率,提出了一种基于I-BGLAM纹理特征和光谱特征融合的高光谱图像的木材树种分类方法。实验数据是利用SOC710VP高光谱成像仪获取的可见光/近红外（372.53~1 038.57 nm）范围内的高光谱图像。首先,利用基于OIF的特征波段选择方法降低高光谱图像的维数,选择出含有信息量大的波段。其次,对选择出的波段图像使用NSCT及NSCT逆变换得到融合图像,对得到的融合图像使用I-BGLAM提取其纹理特征。与此同时,对高光谱图像的全波段求取平均光谱并进行S-G（Savitzky-Golay）平滑得到光谱特征。最后,将得到的纹理特征和光谱特征融合后送进极限学习机（ELM）中进行分类。此外,还和基于灰度共生矩阵（GLCM）的木材识别的传统方法以及近几年木材树种识别领域内被提出的主流方法进行了比较。该研究主要创新点有两个：一是将强纹理提取器I-BGLAM用于高光谱图像中提取其纹理特征;二是提出一种新的特征融合的模型用于高光谱图像的分类。针对8个树种的实验结果表明,单独使用I-BGLAM提取的纹理特征来进行分类的正确率最高可到达88.54%,而使用GLCM提取纹理特征的传统方法正确率最高只有76.04%,该结果可以得出本文使用I-BGLAM在纹理特征提取方面要优于GLCM,这为后面建立的融合模型打下很好的基础,单独使用平均光谱特征来分类的正确率最高可以达到92.71%,使用所提出的特征融合方法所得到的分类正确率最高可达到100%,这说明使用所提出的融合模型来分类要比以前单独使用某一种特征的分类模型要好。此外,使用所提出的方法得到的分类正确率要高于本领域内其他两种主流的识别方法。因此,所提出的基于I-BGLAM纹理特征和光谱特征融合的方法能够提高木材树种分类的正确率,该方法在木材树种分类方面有着一定的利用价值。     

Effect of properties of superheavy nuclei on their production and decay

Properties and stability of superheavy nuclei resulting from hot fusion are discussed. It is shown that the microscopic–macroscopic approach allows obtaining the closed proton shell at Z ≥ 120. Isotopic trends of K-isomeric states in superheavy nuclei are predicted. Evaporation residue cross sections in hot fusion reactions are calculated using the predicted properties of superheavy nuclei. Interruption of α decay chains by spontaneous fission is analyzed. Alpha decay chains through isomeric states are considered. Internal level densities in superheavy nuclei are microscopically calculated.     

Self-consistent approaches in the microscopic theory of the nucleus: Static moments of odd-odd nuclei

Self-consistent mean-field theory and the method of the energy density functional, which are two modern self-consistent approaches in the microscopic theory of the nucleus that possess the highest predictive power for describing unstable nuclei, are briefly discussed. Themost recent results of calculations performed within these approaches are presented. The mean energies of E1 excitations in the range of 0–30 MeV are calculated for 15 stable and unstable tin isotopes (A = 100–176) on the basis of the self-consistent version of the generalized theory of finite Fermi systems by employing SLy4 Skyrme forces. A parameter-dependent expression that takes into account the existence of a pygmy dipole resonance is obtained for this quantity. The density-functional method is used within the self-consistent theory of finite Fermi systems on the basis of the Fayans-Tolokonnikov-Trykov-Zawischa functional in order to calculate the ground-state static quadrupole and magnetic moments of odd and odd-odd stable and unstable spherical near-magic nuclei. Good agreement with available experimental data is attained. The respective features are predicted for unstable nuclei.     

Self-consistent charge-up simulation for the microscopic feature of SiO2 layer in rf capacitive discharge

The charge-up simulation of the microscopic feature with SiO₂ layer was investigated in various conditions of rf capacitive discharge by using the three-dimensional (3-D) particle-in-cell (PIC) charge-up simulation coupled with the one-dimensional (1-D) particle-in-cell Monte Carlo collision (PIC-MCC) simulation of rf capacitive argon discharge. The result showed that the charge-up effect on the micro-trench was greatly influenced by the conditions of the gas pressure and the discharge voltage in rf capacitive discharge. Based on the analysis of the distributions of electrons and ions arriving at the substrate in various plasma conditions, the charge-up effect and its reduction mechanisms on the micro-trench of capacitive discharge were discussed. This article is expected to provide qualitative and quantitative insight for the understanding of charging and its reduction mechanism on many plasma processes performed by the rf capacitive discharge.     

光谱谐波分析的新型HAC非监督分类器

高光谱影像分类是识别影像信息的重要途径之一,研究其算法对地物识别、动态变化监测和专题信息提取等方面具有重要意义。非监督分类由于其具有无须先验知识的特点,被广泛应用于高光谱影像分类。结合谐波分析理论提出一种新的高光谱影像非监督分类算法,即谐波分析分类器(harmonic analysis classifier,HAC)。首先,该算法统计第一谐波分量并绘制其直方图,根据波峰数目及位置确定初始地物类别和聚类中心像元。然后将待分类像元光谱的波形信息映射到谐波分解次数、振幅和相位的特征空间中,利用同类地物在特征空间中表现聚集性这一特征,根据最小距离原则对待分类像元进行归类。最后,计算聚类中心像元间的欧式距离,通过设置距离阈值完成类间合并,从而达到高光谱影像分类的目的。提取两种地物类别的光谱曲线,经谐波分析后得到谐波分解次数、振幅和相位量,并分析其在特征空间中的分布情况验证了HAC算法的正确性。同时将HAC算法应用到EO-1卫星的Hyperion高光谱影像得到其分类结果,通过对比K-MEANS,ISODATA和HAC算法的高光谱影像分类结果,证实HAC算法作为一种非监督分类方法在高光谱影像分类方面具有较好的应用性。     

Shortcut in DIC error assessment induced by image interpolation used for subpixel shifting

In order to characterize errors of Digital Image Correlation (DIC) algorithms, sets of virtual images are often generated from a reference image by in-plane sub-pixel translations. This leads to the determination of the well-known S-shaped bias error curves and their corresponding random error curves. As images are usually shifted by using interpolation schemes similar to those used in DIC algorithms, the question of the possible bias in the quantification of measurement uncertainties of DIC softwares is raised and constitutes the main problematic of this paper. In this collaborative work, synthetic numerically shifted images are built from two methods: one based on interpolations of the reference image and the other based on the transformation of an analytic texture function. Images are analyzed using an in-house subset-based DIC software and results are compared and discussed. The effect of image noise is also highlighted. The main result is that the a priori choices to numerically shift the reference image modify DIC results and may lead to wrong conclusions in terms of DIC error assessment.     

Rotation of nuclei around a prolate symmetry axis at very high spin states

Classically one expects that nuclei rotate at very high spins (30≦I≦80) around an oblate symmetry axis. It is shown that strong shell correction energies yield for some nuclei at the end of the rare earth region and in the Pb-region yrast states for a rotation around a prolate symmetry axis. Like for the rotation around an oblate symmetry axis one expects also here yrast traps. The deformation energy surfaces for very high spin states are calculated by the Strutinsky method using a Saxon-Woods potential and by a microscopic method built on constraint Nilsson functions. Both methods agree qualitatively. Yrast traps are studied for these nuclei. It is shown that the MONA (Maximisation of theOverlap ofNuclear wave functions byAlignment) effect prefers at high spin rotation around the symmetry axis of a negative deformed shape at the beginning of the shell and of positive deformation at the end of the shell.     

Electron charge form factors and static properties of extremely light 1p-shell nuclei within the anisotropic-oscillator model involving projections

The mirror odd nuclei ⁷Li and ⁷Be and the neutron-rich nucleus ⁶He are considered within a microscopic approach relying on the variational principle. The binding energies of the nuclei, their root-mean-square radii, and the electron charge C0 and C2 form factors are calculated. The resulting form factors are compared with the predictions of the independent-particle model that assumes intermediate coupling. The sensitivity of the nuclear properties obtained here to the choice of nucleon-nucleon potential, to deviations of the nuclear deformation from that which follows from a variation of the total-energy functionals, and to taking projections onto states characterized by definite values of the total angular momentum and its projection is analyzed. A comparison with experimental data is performed.     

Detecting galactic cosmic ray transuranium nuclei in olivine crystals from meteorites

Results from the experimental search for and identification of tracks from the superheavy and transuranium nuclei of galactic cosmic rays in pallacite olivine crystals, conducted as part of project OLIMPIA [1], are presented. To date, 170 crystals from Marjalahti and Eagle Station pallacites have been processed and 6800 tracks corresponding to nuclei with charges Z > 55 have been found; 45 of these are from nuclei with charges of 88 < Z < 92 and three super-long ones were produced by nuclei with Z > 105. The charge of one of these nuclei is estimated in the first approximation as Z = 119(+10,?6). Our data confirm the hypothesis of islands of stability for natural trans-Fermi nuclei.     

Incoherent holographic imaging through thin turbulent media

We introduce and experimentally demonstrate a new method of computing Fresnel holograms of a real-existing, three-dimensional (3-D) scene hidden behind a thin turbulent medium, and illuminated by incoherent white light. From each perspective point of view, we acquire multiple noisy speckled images through the medium vibrated mechanically. These images are fused together to yield a smoothed perspective projection of the hidden 3-D scene. All smoothed projections are processed to yield a Fresnel hologram of the hidden scene. The 3-D image reconstructed from the hologram is further improved by digital blind deconvolution of each of the 3-D image slices with its own estimated impulse response.