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1.
The study of cluster structures in light nuclei is extending to the heavy nuclei in these years. As for the stable N = Z nuclei, from the lighter 8Be, 12C nuclei to the heavier 20Ne and even the 40Ca and 44Ti medium nuclei, the α cluster structures have been well studied and confirmed. In heavy nuclei, due to the dominated mean field, the existence of α cluster structure is not clear as light nuclei but some clues were found for indicating the core+α cluster structure in some nuclei, in particular, the 208Pb+α structure in 212Po. We review some recent progress about the theoretical and experimental explorations of the α-clustering effects in heavy nuclei. We also discuss the possible α cluster structure of heavy nuclei from the view of α decay. 相似文献
2.
反转岛附近原子核奇特性质的研究是当前核物理研究的热点。 首先简要回顾和介绍了反转岛附近原子核奇特性质的实验进展, 然后介绍了对这些奇特核性质的理论研究进展。 主要包括相对论平均场模型、 壳模型、 Hartree Fock模型和宏观 微观模型在该区域的发展和研究结果。 重点介绍了宏观 微观模型在反转岛附近原子核奇特性质研究中的进展。 此外, 还分析和比较了各种理论模型在描述反转岛附近原子核性质上取得的成功和模型之间的差异。 相似文献
3.
电荷半径是原子核最基本的物理观测量之一,反映了原子核内的质子分布。精确的电荷半径测量是研究奇特原子核结构的重要手段。在相对论能区,通过高精度测量原子核的电荷改变截面来提取电荷半径是近年来发展起来的一种新方法,这种方法尤其适于探索产额很低的奇特原子核。自2013年以来,北京航空航天大学-中国科学院近代物理研究所课题组基于兰州第二条次级束流线(RIBLL2),提出并建成原子核电荷改变截面测量平台,研制了相关的TOF-△E探测器系统,开展了轻核区二十余个原子核的电荷改变截面的实验测量工作。介绍了实验平台研制情况、初步结果以及下一步计划。Charge radius is one of the most fundamental observables of atomic nuclei, reflecting the proton distributions in nuclei. Their precision measurements have severed as a key tool to study nuclear structure. Recently, a novel method to deduce charge radii has been developed via precise measurements of charge-changing cross sections(CCCS) of exotic nuclei at relativistic energies. This method is in particular suitable for investigation of exotic nuclei with low production yield. In 2013, we proposed to make such measurements for exotic nuclei lighter than oxygen based on the RIBLL2 beam line. Since then, the TOF-△E detector system for particleidentification(PID) and the CCCS platform have been constructed, continuously optimized and tested. So far CCCS measurements on a carbon target have been performed for more than 20 isotopes. In this contribution, we will introduce the progress of detector development, the progress in PID, and our experimental progress and plan. 相似文献
4.
Particle-vibration coupling: Recent advances in microscopic calculations with the Skyrme Hamiltonian
In this contribution, we report some recent progress in our understanding of particle-vibration coupling (PVC) in nuclei. In particular, we first review the formal development that has allowed some of us to deduce the PVC equations within the Green’s functionmethod. Applications are then discussed, both in the case of single-particle states and giant resonances in magic nuclei. We also present a new model that extends the PVC ansatz and is meant to account for the complete low-lying spectra of odd nuclei. 相似文献
6.
K. M. Nollett 《The European physical journal. Special topics》2007,144(1):155-160
Over the last fifteen years, there has been tremendous
progress in understanding how nuclear structure arises from the
nucleon-nucleon interaction. I describe the contribution to this
progress made by quantum Monte Carlo computational methods, as well as
directions to be taken in future work. Most effort in the past has
concentrated on energy spectra, and we have had good success in
computing the spectra of systems with A≤12. We are now shifting
our attention to off-diagonal and scattering/reaction properties of
the light nuclei. I also discuss briefly the relation of quantum
Monte Carlo methods to other ab initio methods and their
particular relevance for weakly-bound nuclei produced at
radioactive-beam facilities. 相似文献
7.
Automatic quantification and classification of leukocytes in microscopic images are of paramount importance in the perspective of disease identification, its progress and drugs development. Extracting numerical values of leukocytes from microscopic images of blood or tissue sections represents a tricky challenge. Research efforts in quantification of these cells include normalization of images, segmentation of its nuclei and cytoplasm followed by their classification. However, there are several related problems viz., coarse background, overlapped nuclei, conversion of 3-D nuclei into 2-D nuclei etc. In this review, we have categorized, evaluated, and discussed recently developed methods for leukocyte identification. After reviewing these methods and finding their constraints, a future research perspective has been presented. Further, the challenges faced by the pathologists with respect to these problems are also discussed. 相似文献
8.
对称性及其破缺是基本的科学问题。手征对称性在自然界中广泛存在,大至星系旋臂、行星自转,小到矿物晶体、有机分子、基本粒子,都与手征对称性密切相关。原子核层次的手征对称性概念于1997年提出,随后成为核物理研究的热点问题。目前,实验上已经在核素图上的80,100,130和190质量核区发现了30多例可能具有手征对称性的原子核。简要介绍原子核中的手征对称性概念;手性原子核的预言、识别以及实验验证;并通过展示手性原子核结构的多样性(MχD),回顾了理论和实验研究进展;介绍最新发现的原子核中手性和空间反射对称性的联立自发破缺,对未来手性原子核研究的前景进行了展望。Symmetry and its breaking are basic scientific problems. Chiral symmetries are common in nature, for example, the macroscopic spiral arms of galaxies and the rotation of planets; the microscopic spirals of the mineral crystalline, the organic molecules and the elementary particles. The concept of chirality in atomic nuclei was first proposed in 1997. Since then many efforts have been made to understand chiral symmetry and its spontaneous breaking in atomic nuclei. Up to now, more than 30 candidates of chiral nuclei have been reported in the 80, 100, 130, and 190 mass regions. The concept of the chirality in atomic nuclei, the prediction, the signal, and the experimental verification of the chiral nuclei are briefly introduced; the recent theoretical and experimental progress are reviewed, in particular the existence of multiple chiral doublets (MχD), i.e., more than one pair of chiral doublet bands in one single nucleus; the simultaneous spontaneous breaking of chiral and reflection symmetry in the newly observed atomic nuclei is introduced, together with a prospect on the future study on nuclear chiral symmetry. 相似文献
9.
Isobaric degrees of freedom δδ in nuclei are determined from the quark cluster model of a nucleus. These additional degrees
of freedom are brought in by the coloured quark exchange between different nucleon clusters present in nuclei. They are found
to be important in the region of momentum transfer near 3.5 fm−1. The mass dependence of these isobaric degrees of freedom in nuclei turns out to beA
5/6. 相似文献
10.
V. S. Letokhov 《Optics & Laser Technology》1981,13(3):131-140
This article describes recent progress in the application of laser atomic spectroscopy to study parameters of nuclei available in very small quantities; radioactive nuclei, rare isotopes, nuclear isomers, etc, for which study by conventional spectroscopic methods is difficult. 相似文献
11.
Wu Xue-bing 《Frontiers of Physics in China》2006,1(2):135-142
The determination of the mass of black holes in our universe is crucial to understand their physics nature but is a great
challenge to scientists. In this paper I briefly review some methods that are currently used to estimate the mass of black
holes, especially those in X-ray binary systems and in galactic nuclei. Our recent progress in improving the mass estimates
of supermassive black holes in active galactic nuclei by involving some empirical relations is presented. Finally I point
out the similarities and common physics in Galactic black hole X-ray binaries and active galactic nuclei, and demonstrate
that the black hole mass estimation is very much helpful to understand the accretion physics around black holes. 相似文献
12.
C. Scheidenberger F. Attallah K. Beckert P. Beller F. Bosch D. Boutin H. Eickhoff T. Faestermann M. Falch B. Franczak B. Franzke H. Geissel M. Hausmann M. Hellström E. Kaza Th. Kerscher O. Klepper H. -J. Kluge R. Koyama C. Kozhuharov K. -L. Kratz Yu. A. Litvinov K. Löbner L. Maier M. Matos G. Münzenberg F. Nolden Yu. N. Novikov T. Ohtsubo A. Ostrowski A. Ozawa Z. Patyk B. Pfeiffer M. Portillo W. Quint T. Radon V. Shishkin J. Stadlmann M. Steck M. Sümmerer T. Suzuki M. B. Trzhaskovskaja D. J. Vieira S. Watanabe H. Weick M. Winkler H. Wollnik T. Yamaguchi 《Acta Physica Hungarica A》2004,19(1-2):165-170
Recent progress in experiments with exotic nuclear beams at the SIS-FRS-ESR facility is summarized. New results on gross properties of exotic nuclei like binding energy, half-lives, and decay modes are presented. A brief outlook to future experiments is given. 相似文献
13.
重核大集团(14C-34Si)发射的半衰期在理论上用Wentzel-Kramers-Brillouin近似进行了计算.利用双折叠模型计算大集团和剩余子核间的核相互作用,在折叠积分中选取了密度依赖的、零力程交换项的核子-核子相互作用.计算得到的半衰期和液滴模型结果、系统公式的结果以及实验数据进行了比较,表明目前的计算能够很好地给出重核大集团(14C-34Si)发射的寿命.这可为重核其他大集团(15N, 46Ar,48Ca等)的发射提供可靠的预测.
关键词:
半衰期
双折叠模型
集团发射 相似文献
14.
15.
B. G. Turrell 《Hyperfine Interactions》1985,22(1-4):97-110
This paper reviews how certain problems in solid state physics have been clarified by low temperature nuclear orientation and nuclear magnetic resonance of oriented nuclei. The advantages of these techniques are discussed; a brief survey of recent progress in traditional applications is given; new developments are discussed, and, finally, future trends are suggested. 相似文献
16.
The Gamow-Teller transitions for pf shell nuclei with proton number less than 40 and neutron number larger than 40 were believed to be blocked, due to the full filling of the neutron orbit. However, recent experimental research shows that the Gamow-Teller transitions for these kinds of nuclei are not blocked. In this paper, we systematically calculate the GT transition of pf shell nuclei 76Se in different truncations, and the results are compared with experimental results. It is shown that, due to correlations, the believed blocked GT transition occurs, and the shell model calculations reproduce the experimental GT strength. In addition, the electron capture rates in a stellar environment are calculated and discussed. 相似文献
17.
Pavel V. Kostryukov Artur Dobrowolski Bo?ena Nerlo-Pomorska Micha? Warda Zhigang Xiao Yongjing Chen Lile Liu Jun-Long Tian Krzysztof Pomorski 《中国物理C(英文版)》2021,45(12):124108-124108-20
Potential energy surfaces and fission barriers of superheavy nuclei are analyzed in a macroscopic-microscopic model. The Lublin-Strasbourg Drop (LSD) model is used to obtain the macroscopic part of the energy, whereas the shell and pairing energy corrections are evaluated using the Yukawa-folded potential; a standard flooding technique is utilized to determine barrier heights. A Fourier shape parametrization containing only three deformation parameters is shown to effectively reproduce the nuclear shapes of nuclei approaching fission. In addition, a non-axial degree of freedom is taken into account to better describe the structure of nuclei around the ground state and in the saddle region. In addition to the symmetric fission valley, a new highly asymmetric fission mode is predicted in most superheavy nuclei. The fission fragment mass distributions of the considered nuclei are obtained by solving 3D Langevin equations. 相似文献
18.
19.
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
20.
一个模型适合描述哪些物理量? 这个问题可以通过模型的物理来源来回答。比如,液滴模型适合描述重核和远离满壳核。这是因为液滴近似更适用于核子数多的核以及液滴模型不包含壳效应。这样的回答是定性的并需要清楚模型的物理来源。是否可能仅通过模型的数学形式和实验数据就能给出半定量的解答? 利用最近提出的不确定度分解方法尝试对液滴模型适合描述哪些核这一问题进行半定量的回答。并且不需已知液滴模型的物理来源,仅需其数学形式以及实验数据。通过不确定度分解方法,液滴模型与实验数据间的残差可以分解为系统不确定度和统计不确定度。两者分别代表了模型的缺陷和模型不精确的参数带来的不确定度。基于这一分解,核素图上的原子核可以按其对应的残差被半定量地划分为系统不确定度主导、统计不确定度主导、以及中间区域。液滴模型适合描述的核就是统计不确定度主导残差的核而不是像通常认为的是残差最小的核。从核素图上看,统计不确定度主导残差的核正是重核以及远离满壳核,与液滴模型物理来源一致,但得到这一结果的过程是半定量的且仅需液滴模型的数学形式以及实验数据。如果对由统计不确定度主导残差的核重新拟合液滴模型的参数,模型可以很好地描述这些核(标准差小于0.7 MeV)。Which data are well described by a theoretical model? Such questions can be answered through the physical origin of the model. For example, the liquid drop model (LDM) well describes the heavy and far from shell nuclei. Because the liquid-drop assumption is more suitable for nuclei with more nucleons and LDM does not include the shell effect. Such answer is qualitative and needs a clear view on the physical origin of the model. Is it possible to give an semi-quantitatively answer only from the mathematical form of the model and the observed data. In the present work, the recently suggested uncertainty decomposition method (UDM) is used to answer which nuclei are well described by LDM. The residues between LDM and the observed data can be decomposed through UDM to systematic and statistical uncertainties, which represent the uncertainty of the deficiency of the model and the indeterminate parameters, respectively. Based on UDM, the chart of nuclides are semi-quantitatively divided into three parts, areas dominated by the systematic and statistical uncertainties, and the cross area. Contrary to the common sense, the well described nuclei by LDM are not the nuclei with small residues, but actually the nuclei of which the residues are dominated by the statistical uncertainty. These nuclei are indeed the heavy and far from shell nuclei, which agrees with the physical consideration of LDM. But only the mathematical form of the model and the experimental data are needed during the use of UDM. The nuclides dominated by the statistical uncertainty can be well described by LDM (standard deviation less than 0.7 MeV) with parameters fitting to these nuclei. 相似文献