共查询到20条相似文献,搜索用时 15 毫秒
1.
M. Kopytin 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):575-577
Measurements of azimuthal cross-section asymmetries from deeply virtual Compton scattering on transversely and longitudinally
polarized hydrogen and longitudinally polarized deuterium targets at HERMES are reported. By comparing the HERMES results
on the transverse target-spin asymmetry with theoretical calculations based on a phenomenological model of generalized parton
distributions, a model-dependent constraint on the total angular momentum carried by quarks in the nucleon is obtained. 相似文献
2.
H. E. Jackson 《中国物理 C》2010,34(9):1247-1253
Results are presented from the Hermes experiment which uses semi-inclusive deep inelastic lepton scattering to study the flavor structure of the nucleon.Data have been accumulated for pion and kaon double spin asymmetries,single-spin azimuthal asymmetries for meson electroproduction,deep virtual Compton scattering (DVCS),and meson multiplicities.These results provide information on the properties of the strange sea in the proton,constraints on transverse momentum dependent quark parton distributions,and demonstrate the promise of DVCS for isolating the total angular momentum carried by the quarks in the proton. 相似文献
3.
H.E.Jackson 《中国物理C(英文版)》2010,34(9)
Results are presented from the Hermes experiment which uses semi-inclusive deep inelastic lepton scattering to study the flavor structure of the nucleon. Data have been accumulated for pion and kaon double spin asymmetries, single-spin azimuthal asymmetries for meson electroproduction, deep virtual Compton scattering (DVCS), and meson multiplicities. These results provide information on the properties of the strange sea in the proton, constraints on transverse momentum dependent quark parton distributions, and demonstrate the promise of DVCS for isolating the total angular momentum carried by the quarks in the proton. 相似文献
4.
Recent trends in Low-Temperature Nuclear Orientation (LTNO) and its site-selective derivative, Nuclear Magnetic Resonance
on Oriented Nuclei (NMRON), are reviewed. Traditional areas of endeavour using elemental ferromagnetic hosts remain strong
with significant improvements in methodology since last reviewed [1]; but there are new emphases emerging in solid-state physics
and especially magnetism. Exotic single crystals hosts and MBE-grown multi-layers are gaining increased prominence as the
principal focus of LTNO study. Increasingly, in off-line work and very recent on-line implantation into insulators [2], the
radioactive probes are often chosen to be isoelectronic with an abundant chemical species within the host, rather than representing
an extremely dilute, electronic impurity spy. Recent NMRON on a heavy rare earth, isoelectronic probe in an ordered rare earth
halide opens up new dimensions.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
5.
D. Lunney C. Monsanglant G. Audi G. Bollen C. Borcea H. Doubre C. Gaulard S. Henry M. deSaintSimon C. Thibault C. Toader N. Vieira 《Hyperfine Interactions》2001,132(1-4):297-305
The MISTRAL experiment (Mass measurements at ISOLDE with a Transmission and Radiofrequency spectrometer on-Line), conceived
for very short-lived nuclides, has reached the end of its commissioning phase. Installed in 1997, results have been obtained
consistent with all aspects of the projected spectrometer performance: nuclides with half-lives as short as 30 ms have been
measured and accuracies of 0.4 ppm have been achieved, despite the presence of a systematic shift and difficulties with isobaric
contamination. Masses of several nuclides, including 25–26Ne and 32Mg that forms the famous island of inversion around N=20, have been significantly improved.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
The three-body force effects on the equation of state and its iso-spin dependence of asymmetric nuclearmatter and on the proton fraction in neutron star matter have been investigated within Brueckner-Hartree-Fock approachby using a microscopic three-body force. It is shown that, even in the presence of the three-body force, the empiricalparabolic law of the energy per nucleon vs. isospin asymmetry β= ( N - Z) /A is fulfilled in the whole asymmetry range0≤β≤1 and also up to high density. The three-body force provides a strong enhancement of symmetry energy at highdensity in agreement with relativistic approaches. It also shows that the three-body force leads to a much more rapidincreasing of symmetry energy with density in relatively high density region and to a much lower threshold density forthe direct URCA process to occur in a neutron star as compared to the predictions adopting only pure two-body force. 相似文献
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8.
本文建立了基于核磁共振氢谱(1H NMR)测定新药替格瑞洛绝对含量的方法.采用Bruker Avance 300型NMR谱仪,以磺胺多辛为内标;以替格瑞洛中质子信号δH 7.14(2H,m)和δH 7.04(1H,s),磺胺多辛质子信号δH 8.04(1H,s)、δH 7.73(2H,d)和δH 6.54(2H,d)作为定量峰;以氘代甲醇(CD3OD)为溶剂进行测定.测定条件为:探头温度为308 K,谱宽为3 511.5 Hz,中心频率为1 470.6 Hz,脉冲翻转角为θ=30°,延迟时间为10 s,采样次数为16,线宽因子为0.3 Hz.在此实验条件下,替格瑞洛样品与内标磺胺多辛的定量峰分离良好,实验结果精密度较高、重复性较好、线性范围较宽,其线性拟合方程为:Y=1.053X-0.081(r=0.996,n=5).最终测得样品中替格瑞洛含量为99.4%,相对标准偏差(RSD)为0.20%.该方法简便、准确、快速,适用于替格瑞洛样品的绝对含量测定. 相似文献
9.
The possible use of a polarized proton target in the investigation of low-energy nucleon-nucleon interactions is reviewed. The reconstruction of the scattering matrix and verification of P-, T-and isotopical invariances are briefly discussed. Possible sources and detectors of polarized particles are considered. The problem of phase-shift analysis and nucleon-nucleon potentials are treated in the appendices. Tables of experimental values are given for the polarization of nucleons scattered on nucleons. Experimental quantities determined from the phase-shift analysis are given in graphs for the energies 14.5 and 23.1 MeV. 相似文献
10.
Based on Glauber Multiple Scattering Theory, high-energy proton elastic scattering on halo-like nucleus 13C is studied in a single nucleon wave function with low angular momentum configurations. A great agreement with experimental data is obtained and the theoretical prediction clearly shows that 13 C has a neutron halo-like structure.Then, the origin and nature of nuclear halo phenomena are explained in terms of nuclear short-range correlations. Our conclusion shows that the origin of nuclear halo-like phenomena originates from short range nuclear correlation. 相似文献
11.
K.C.Chung C.S.Wang A.J.Santiago 《理论物理通讯》2001,(11)
The extraction of nuclear matter properties from measured nuclear masses is investigated in the energy density functional formalism of nuclei.It is shown that the volume energy a1 and the nuclear incompressibility Ko depend essentially on μnN - - pZ - 2EN,whereas the symmetry energy J and the density symmetry coefficient L as well as symmetry incompressibility Ks depend essentially on μn - μp,where μp =μp - Ec/ Z,μn and μp are the neutron and proton chemical potentials respectively,EN the nuclear energy,and Ec the Coulomb energy.The obtained symmetry energy is J = 28.5 MeV,while other coefficients are uncertain within ranges depending on the model of nuclear equation of state.`` 相似文献
12.
MAWei-Xing HUZhao-Hui ZHOULi-Juan ZHUJi-Zhen LUJuan 《理论物理通讯》2003,40(6):699-701
Based on Glauber Multiple Scattering Theory, high-energy proton elastic scattering on halo-like nucleus ^13C is studied in a single nucleon wave function with low angular momentum configurations. A great agreement with experimental data is obtained and the theoretical prediction clearly shows that 13U has a neutron halo-like structure.Then, the origin and nature of nuclear halo phenomena are explained in terms of nuclear short-range correlations. Our conclnsion shows ttiat the origin of nuclear halo-like phenomena originates from short range nuclear correlation. 相似文献
13.
The extraction of nuclear matter properties from measured nuclear masses is investigated in the energy density functional formalism of nuclei.It is shown that the volume energy a1 and the nuclear incompressibility Ko depend essentially on μnN + μpZ - 2EN,whereas the symmetry energy J and the density symmetry coefficient L as well as symmetry incompressibility Ks depend essentially on μn - μp,where μp =μp - ∂Ec/∂Z,μn and μp are the neutron and proton chemical potentials respectively,EN the nuclear energy,and Ec the Coulomb energy.The obtained symmetry energy is J = 28.5 MeV,while other coefficients are uncertain within ranges depending on the model of nuclear equation of state. 相似文献
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The variation of nuclear parameter with mass number elicits information about nuclear compressibility. Analysis of muonic
x-ray transitions provides an elegant method to investigate the behaviour of the nuclear parameterr
0. It is observed from the behaviour ofr
0 that nuclei in the regionA⩽70 are highly compressible while those in the regionA∼210 are almost incompressible. The behaviour ofr
0 is incorporated into the semi-empirical mass formula through the Coulomb energy term. From the modified mass formula thus
obtained binding energies of about 440 spherical nuclei have been calculated. The results suggest that nuclear compressibility
imposes certain relationship between excess binding energies (E
exp−E
cal) and neutron. proton number. The present study also points out that shell effects exhibited by nuclear binding energies cannot
be accounted for by simply varying the coefficients of the mass formula: on the other hand extra terms are necessary to explain
them. 相似文献
16.
介绍了利用加速器质谱技术在核物理与核天体物理中的应用研究工作.包括放射性核素半衰期的测定、核反应截面的测量、超重元素的寻找、宇宙射线和太阳中微子性质等方面的研究工作.The application work which has been done and can be done in the nuclear physics and nuclear astrophysics using accelerator mass spectrometry is reviewed. The half-life measurement of long-lived radio isotopes, cross section measurement of nuclear reaction, searching for super heavy elements, cosmic study and solar neutrino detection are the main components which have been discussed 相似文献
17.
Considerable progress has been made in the study of proton-emitting nuclei since the first observation of direct proton emission nearly half a century ago. This has led to improvements in our understanding of this rare decay process and provided invaluable nuclear structure data far from the valley of beta stability. This paper reviews the implications of some recent results for exotic iridium, rhenium and tantalum isotopes and considers prospects for future experimental studies of proton-emitting nuclei located at and above the N =82 neutron shell closure. 相似文献
18.
核电池材料及核电池的应用 总被引:1,自引:0,他引:1
核电池具有体积小、寿命长、不受外界环境影响等优点,因而在航空航天、深海、极地、心脏起搏器、微型电机等领域得到广泛地应用。核电池的发展与所用材料的发展互相促进。从同位素放射源、电能转换、密封保护的角度介绍了核电池所用材料的发展和最新研究进展,同时也介绍了核电池现有和潜在的应用领域。Nuclear battery has lots of advantages such as small volume, longevity, environal stability and so on, therefore, it was widely used in aerospace, deep-sea , polar region, heart pacemaker, micro-electromotor and other fields etc. The application of nuclear battery and the development of its materials promote each other. In this paper the development and the latest research progress of nuclear battery materials has been introduced from the view of radioisotope, electric energy conversion and encapsulation. And the current and potential applications of the nuclear battery are also summarized. 相似文献
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20.
核能有两个最具影响的应用:一是它的和平利用——核电(第四讲介绍),另一是它的军事应用——核武器.文章将介绍核能和核武器基本原理以及核燃料生产方法.首先简要介绍核裂变能与聚变能;然后比较详细地说明原子弹的基本原理,包括中子增殖、自持裂变链式反应条件、临界质量和两种形式原子弹的结构原理等,对于氢弹、中子弹的原理仅作简单介绍;最后,对核燃料的生产:铀同位素分离和钚—239的反应堆生产作了原理性的介绍。 相似文献