增益噪声温度比(Gain to Noise Temperature Ratio,G/T)是衡量卫星地面接收系统性能的关键指标,其测量精度直接影响系统性能评估的有效性。为提高G/T值的测量精度,系统阐述了利用射电源进行G/T值测试的原理和方法,提出了射电源大气吸收...增益噪声温度比(Gain to Noise Temperature Ratio,G/T)是衡量卫星地面接收系统性能的关键指标,其测量精度直接影响系统性能评估的有效性。为提高G/T值的测量精度,系统阐述了利用射电源进行G/T值测试的原理和方法,提出了射电源大气吸收修正因子、波束展宽修正因子、射电源流量随时间变化修正因子的精确计算模型,并给出了射电源通量密度曲线及修正因子曲线。在此基础上,利用月亮和仙后座A对中等口径天线进行G/T值测量,系统分析了G/T值的测量误差,验证了所提计算模型的有效性,为提高G/T值测量的精确性与可靠性提供了科学依据和实践指导。展开更多
We present an experimental determination on the Lande g-factors for the 5 s^2 ^1 S0 and 5 s5 p ^3P0 states in ultra-cold atomic systems, which is important for evaluating the Zeeman shift of the clock transition in th...We present an experimental determination on the Lande g-factors for the 5 s^2 ^1 S0 and 5 s5 p ^3P0 states in ultra-cold atomic systems, which is important for evaluating the Zeeman shift of the clock transition in the ^87Sr optical lattice clock. The Zeeman shift of the 5 s5 p ^3 P0-5 s^2 ^1 S0 forbidden transition is measured with the π-polarized and σ^±-polarized interrogations at different magnetic field strengths. Moreover, in the g-factor measurement with the σ^±-transition spectra, it is unnecessary to calibrate the external magnetic field. By this means, the ground state 5 s^2 ^1 S0 g-factor for the ^87Sr atom is-1.306（52） ×10^-4, which is the first experimental determination to the best of our knowledge, and the result matches very well with the theoretical estimation. The differential g-factorδg between the 5 s5 p^3 P0 state and the 5 s^2 ^1 S0 state of the ^87Sr atoms is measured in the experiment as well,which are-7.67（36） ×10^-5 with π-transition spectra and-7.72（43） X 10^-5 with σ^±-transition spectra, in good agreement with the previous report [Phys. Rev. A 76（2007） 022510]. This work can also be used for determining the differential g-factor of the clock states for the optical clocks based on other atoms.展开更多
When analyzing an Electron’s orbit’s and movements, a “classical” bare g-factor of “1” must be used, but when analyzing just the Electron itself, a bare g-factor and gyromagnetic ratio of twice the “classical”...When analyzing an Electron’s orbit’s and movements, a “classical” bare g-factor of “1” must be used, but when analyzing just the Electron itself, a bare g-factor and gyromagnetic ratio of twice the “classical” value is needed to fit reality. Nobody has fully explained this yet. By examining the electromagnetic wave nature of the electron, it is possible to show a simple reason why its bare g-factor must be 2, without resorting to superluminal velocities or dismissing it as mystically intrinsic. A simple charged electromagnetic wave loop (CEWL) model of the electron that maintains the same electromagnetic wave nature as the high-energy photons from which electron-positron pairs form, will have exactly half of its energy in the form of magnetic energy who’s field lines are perpendicular to the direction of the charge rotation, which leads to the conclusion that only half of the electron’s electromagnetic mass is rotational mass, from which it is easy to calculate a bare g-factor of 2 using Feynman’s equation for the electron’s g-factor.展开更多
The g-factors of the intra-band states 12, 13, 14, 15 in a magnetic-rotational band built on the 11 state in S2Rb are measured for the first time by using a transient magnetic field-ion implantation perturbed angular ...The g-factors of the intra-band states 12, 13, 14, 15 in a magnetic-rotational band built on the 11 state in S2Rb are measured for the first time by using a transient magnetic field-ion implantation perturbed angular distribution （TMF-IMPAD） method. The magnetic-rotational band in ^82Rb is populated by the ^60Ni（27A1,4pn）^82Rb reaction, and the time-integral Larmor precessions are measured after recoil implantation into a polarized Fe foil. The calculation of g-factors is also carried out in terms of a semi-classical model of independent particle angular momentum coupling on the basis of the four-quasiparticle configuration π（99/2）^2 Оπ（p3/2, f5/2） О v （g9/2）. The measured and calculated g-factors are in good agreement with each other. The g-factors and deduced shear angles decrease with the increase of spin along the band. This clearly illustrates the shear effect of a step-by-step alignment of the valence protons and neutrons in magnetic rotation. The semi-classical calculation also shows that the alignment of the valence neutron angular momentum is faster than that of the valence protons, which results in a decrease of g-factors with increasing spin. The present results provide solid evidence of the shear mechanism of magnetic rotation.展开更多
Highly charged nickel ions have been suggested as candidates for the ultra-precise optical clock, meanwhile the relevant experiment has been carried out. In the framework of the multiconfiguration Dirac–Hartree–Fock...Highly charged nickel ions have been suggested as candidates for the ultra-precise optical clock, meanwhile the relevant experiment has been carried out. In the framework of the multiconfiguration Dirac–Hartree–Fock(MCDHF)method, we calculated the hyperfine interaction constants, the Landég-factors, and the electric quadrupole moments for the low-lying states in the 61Ni11+,61Ni12+,61Ni14+, and61Ni15+ ions. These states are clock states of the selected clock transitions in highly charged nickel ions(see Fig. 1). Based on discussing the effects of the electron correlations, the Breit interaction, and quantum electrodynamics(QED) effect on these physical quantities, reasonable uncertainties were obtained for our calculated results. In addition, the electric quadrupole frequency shifts and the Zeeman frequency shifts of the clock transitions concerned were analyzed.展开更多
The study of magnetic field effects on the clock transition of Mg and Cd optical lattice clocks is scarce.In this work,the hyperfine-induced Landég-factors and quadratic Zeeman shift coefficients of the nsnp ^(3)...The study of magnetic field effects on the clock transition of Mg and Cd optical lattice clocks is scarce.In this work,the hyperfine-induced Landég-factors and quadratic Zeeman shift coefficients of the nsnp ^(3)P_(0)^(o) clock states for ^(111,113)Cd and ^(25)Mg were calculated by using the multi-configuration Dirac–Hartree–Fock theory.To obtain accurate values of these parameters,the impact of electron correlations and furthermore the Breit interaction and quantum electrodynamical effects on the Zeeman and hyperfine interaction matrix elements,and energy separations were investigated in detail.We also estimated the contributions from perturbing states to the Landég-factors and quadratic Zeeman shift coefficients concerned so as to truncate the summation over the perturbing states without loss of accuracy.Our calculations provide important data for estimating the first-and second-order Zeeman shifts of the clock transition for the Cd and Mg optical lattice clocks.展开更多
The electron g-factor relates the magnetic moment to the spin angular momentum. It was originally theoretically calculated to have a value of exactly 2. Experiments yielded a value of 2 plus a very small fraction, ref...The electron g-factor relates the magnetic moment to the spin angular momentum. It was originally theoretically calculated to have a value of exactly 2. Experiments yielded a value of 2 plus a very small fraction, referred to as the g-factor anomaly. This anomaly has been calculated theoretically as a power series of the fine structure constant. This document shows that the anomaly is the result of the electron charge thickness. If the thickness were to be zero, g = 2 exactly, and there would be no anomaly. As the thickness increases, the anomaly increases. An equation relating the g-factor and the surface charge thickness is presented. The thickness is calculated to be 0.23% of the electron radius. The cause of the anomaly is very clear, but why is the charge thickness greater than zero? Using the model of the interior structure of the electron previously proposed by the author, it is shown that the non-zero thickness, and thus the g-factor anomaly, are due to the proposed positive charge at the electron center and compressibility of the electron material. The author’s previous publication proposes a theory for splitting the electron into three equal charges when subjected to a strong external magnetic field. That theory is revised in this document, and the result is an error reduced to 0.4% in the polar angle where the splits occur and a reduced magnetic field required to cause the splits.展开更多
This study determined the lifetime of the first excited state(5∕2_(1)^(+))in ^(139)La via β-γ time-difference measurement using a LaBr_(3)+plastic scintillator array.This state is populated following the decay of ^...This study determined the lifetime of the first excited state(5∕2_(1)^(+))in ^(139)La via β-γ time-difference measurement using a LaBr_(3)+plastic scintillator array.This state is populated following the decay of ^(139)Ba produced in the^(138)Ba(n,γ)reaction.Compared with previous experiments using only stilbene/plastic crystals,this experiment separates the background contribution in the γ-ray spectrum owing to the high energy resolution of LaBr_(3).The L-forbidden M1 transition strength,B(M1,5∕2_(1)^(+)→7∕2_(1)^(+)),in^(139)La was measured and compared with detailed large-scale shell model calculations,with a special focus on the core-excitation effect.The results showed the importance of both proton and neutron core-excitations in explaining the M1 transition strength.Meanwhile,the effective g-factor for the tensor term of the M1 operator was smaller than the previously reported value in this region or around ^(208)Pb.展开更多
文摘增益噪声温度比(Gain to Noise Temperature Ratio,G/T)是衡量卫星地面接收系统性能的关键指标,其测量精度直接影响系统性能评估的有效性。为提高G/T值的测量精度,系统阐述了利用射电源进行G/T值测试的原理和方法,提出了射电源大气吸收修正因子、波束展宽修正因子、射电源流量随时间变化修正因子的精确计算模型,并给出了射电源通量密度曲线及修正因子曲线。在此基础上,利用月亮和仙后座A对中等口径天线进行G/T值测量,系统分析了G/T值的测量误差,验证了所提计算模型的有效性,为提高G/T值测量的精确性与可靠性提供了科学依据和实践指导。
基金Supported by the National Natural Science Foundation of China under Grant Nos 61127901,11404025 and 91536106the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No XDB21030700+1 种基金the Key Research Project of Frontier Science of Chinese Academy of Sciences under Grant No QYZDB-SSW-JSC004the China Postdoctoral Science Foundation under Grant No 2014M560061
文摘We present an experimental determination on the Lande g-factors for the 5 s^2 ^1 S0 and 5 s5 p ^3P0 states in ultra-cold atomic systems, which is important for evaluating the Zeeman shift of the clock transition in the ^87Sr optical lattice clock. The Zeeman shift of the 5 s5 p ^3 P0-5 s^2 ^1 S0 forbidden transition is measured with the π-polarized and σ^±-polarized interrogations at different magnetic field strengths. Moreover, in the g-factor measurement with the σ^±-transition spectra, it is unnecessary to calibrate the external magnetic field. By this means, the ground state 5 s^2 ^1 S0 g-factor for the ^87Sr atom is-1.306（52） ×10^-4, which is the first experimental determination to the best of our knowledge, and the result matches very well with the theoretical estimation. The differential g-factorδg between the 5 s5 p^3 P0 state and the 5 s^2 ^1 S0 state of the ^87Sr atoms is measured in the experiment as well,which are-7.67（36） ×10^-5 with π-transition spectra and-7.72（43） X 10^-5 with σ^±-transition spectra, in good agreement with the previous report [Phys. Rev. A 76（2007） 022510]. This work can also be used for determining the differential g-factor of the clock states for the optical clocks based on other atoms.
文摘When analyzing an Electron’s orbit’s and movements, a “classical” bare g-factor of “1” must be used, but when analyzing just the Electron itself, a bare g-factor and gyromagnetic ratio of twice the “classical” value is needed to fit reality. Nobody has fully explained this yet. By examining the electromagnetic wave nature of the electron, it is possible to show a simple reason why its bare g-factor must be 2, without resorting to superluminal velocities or dismissing it as mystically intrinsic. A simple charged electromagnetic wave loop (CEWL) model of the electron that maintains the same electromagnetic wave nature as the high-energy photons from which electron-positron pairs form, will have exactly half of its energy in the form of magnetic energy who’s field lines are perpendicular to the direction of the charge rotation, which leads to the conclusion that only half of the electron’s electromagnetic mass is rotational mass, from which it is easy to calculate a bare g-factor of 2 using Feynman’s equation for the electron’s g-factor.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.10435010 and 10375093)
文摘The g-factors of the intra-band states 12, 13, 14, 15 in a magnetic-rotational band built on the 11 state in S2Rb are measured for the first time by using a transient magnetic field-ion implantation perturbed angular distribution （TMF-IMPAD） method. The magnetic-rotational band in ^82Rb is populated by the ^60Ni（27A1,4pn）^82Rb reaction, and the time-integral Larmor precessions are measured after recoil implantation into a polarized Fe foil. The calculation of g-factors is also carried out in terms of a semi-classical model of independent particle angular momentum coupling on the basis of the four-quasiparticle configuration π（99/2）^2 Оπ（p3/2, f5/2） О v （g9/2）. The measured and calculated g-factors are in good agreement with each other. The g-factors and deduced shear angles decrease with the increase of spin along the band. This clearly illustrates the shear effect of a step-by-step alignment of the valence protons and neutrons in magnetic rotation. The semi-classical calculation also shows that the alignment of the valence neutron angular momentum is faster than that of the valence protons, which results in a decrease of g-factors with increasing spin. The present results provide solid evidence of the shear mechanism of magnetic rotation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11704398 and 11934014)the National Key Research and Development Program of China(Grant No.2017YFA0304402)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21030300)。
文摘Highly charged nickel ions have been suggested as candidates for the ultra-precise optical clock, meanwhile the relevant experiment has been carried out. In the framework of the multiconfiguration Dirac–Hartree–Fock(MCDHF)method, we calculated the hyperfine interaction constants, the Landég-factors, and the electric quadrupole moments for the low-lying states in the 61Ni11+,61Ni12+,61Ni14+, and61Ni15+ ions. These states are clock states of the selected clock transitions in highly charged nickel ions(see Fig. 1). Based on discussing the effects of the electron correlations, the Breit interaction, and quantum electrodynamics(QED) effect on these physical quantities, reasonable uncertainties were obtained for our calculated results. In addition, the electric quadrupole frequency shifts and the Zeeman frequency shifts of the clock transitions concerned were analyzed.
基金Project supported by the National Natural Science Foundation of China (Grant No.61775220)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDB21030100)the Key Research Project of Frontier Science of the Chinese Academy of Sciences (Grant No.QYZDB-SSW-JSC004)。
文摘The study of magnetic field effects on the clock transition of Mg and Cd optical lattice clocks is scarce.In this work,the hyperfine-induced Landég-factors and quadratic Zeeman shift coefficients of the nsnp ^(3)P_(0)^(o) clock states for ^(111,113)Cd and ^(25)Mg were calculated by using the multi-configuration Dirac–Hartree–Fock theory.To obtain accurate values of these parameters,the impact of electron correlations and furthermore the Breit interaction and quantum electrodynamical effects on the Zeeman and hyperfine interaction matrix elements,and energy separations were investigated in detail.We also estimated the contributions from perturbing states to the Landég-factors and quadratic Zeeman shift coefficients concerned so as to truncate the summation over the perturbing states without loss of accuracy.Our calculations provide important data for estimating the first-and second-order Zeeman shifts of the clock transition for the Cd and Mg optical lattice clocks.
文摘The electron g-factor relates the magnetic moment to the spin angular momentum. It was originally theoretically calculated to have a value of exactly 2. Experiments yielded a value of 2 plus a very small fraction, referred to as the g-factor anomaly. This anomaly has been calculated theoretically as a power series of the fine structure constant. This document shows that the anomaly is the result of the electron charge thickness. If the thickness were to be zero, g = 2 exactly, and there would be no anomaly. As the thickness increases, the anomaly increases. An equation relating the g-factor and the surface charge thickness is presented. The thickness is calculated to be 0.23% of the electron radius. The cause of the anomaly is very clear, but why is the charge thickness greater than zero? Using the model of the interior structure of the electron previously proposed by the author, it is shown that the non-zero thickness, and thus the g-factor anomaly, are due to the proposed positive charge at the electron center and compressibility of the electron material. The author’s previous publication proposes a theory for splitting the electron into three equal charges when subjected to a strong external magnetic field. That theory is revised in this document, and the result is an error reduced to 0.4% in the polar angle where the splits occur and a reduced magnetic field required to cause the splits.
基金supported by the Guangdong Major Project of Basic and Applied Basic Research (No. 2021B0301030006)Young Scientists Fund of the National Natural Science Foundation of China (No. 12405144)+3 种基金the National Natural Science Foundation of China (No. 12475129)the International Atomic Energy Agency Coordinatated Research Project F41034 (No. 28649)the computational resources from Sun Yat-sen University the National Supercomputer Center in Guangzhouthe Natural Science Foundation of Guangdong Province,China (No. 2025A1515012112)
文摘This study determined the lifetime of the first excited state(5∕2_(1)^(+))in ^(139)La via β-γ time-difference measurement using a LaBr_(3)+plastic scintillator array.This state is populated following the decay of ^(139)Ba produced in the^(138)Ba(n,γ)reaction.Compared with previous experiments using only stilbene/plastic crystals,this experiment separates the background contribution in the γ-ray spectrum owing to the high energy resolution of LaBr_(3).The L-forbidden M1 transition strength,B(M1,5∕2_(1)^(+)→7∕2_(1)^(+)),in^(139)La was measured and compared with detailed large-scale shell model calculations,with a special focus on the core-excitation effect.The results showed the importance of both proton and neutron core-excitations in explaining the M1 transition strength.Meanwhile,the effective g-factor for the tensor term of the M1 operator was smaller than the previously reported value in this region or around ^(208)Pb.
