The reaction dynamics of exotic nuclei near the drip line is one of the main research topics of current interest.Elastic scattering is a useful probe for investigating the size and surface diffuseness of exotic nuclei...The reaction dynamics of exotic nuclei near the drip line is one of the main research topics of current interest.Elastic scattering is a useful probe for investigating the size and surface diffuseness of exotic nuclei.The development of rare isotope accelerators offers opportunities for such studies.To date,many relevant measurements have been performed at accelerators using the projectile fragmentation technique,while the measurements at accelerators using isotope separator on-line(ISOL)systems are still quite scarce.In this work,we present the first proof-of-principle experiment with a post-accelerated ISOL beam at the Beijing Radioactive Ion Beam Facility(BRIF)by measuring the angular distribution of elastic scattering for the stable nucleus^(23)Na from the doubly magic nucleus^(40)Ca at energies above the Coulomb barrier.The angular distribution measured by a silicon strip detector array in a scattering chamber using the ISOL beam at BRIF is in good agreement with that measured by the high-precision Q3 D magnetic spectrograph using the nonISOL beam at nearly the same energy.This work provides useful background for making BRIF a powerful tool for the investigation of the reaction dynamics of exotic nuclei.展开更多
The combination of a velocity mapping imaging technique and mathematical transformation is adopted to study the angular distribution of electrons ejected from the Eu 4f76p1/26 d autoionizing states, which are excited ...The combination of a velocity mapping imaging technique and mathematical transformation is adopted to study the angular distribution of electrons ejected from the Eu 4f76p1/26 d autoionizing states, which are excited with a three-step excitation scheme via different Eu 4f76s6d8 D J（J = 5/2, 7/2, and 9/2） intermediate states. In order to determine the energy dependence of angular distribution of the ejected electrons, the anisotropic parameters are measured in the spectral profile of the 6p1/26 d autoionizing states by tuning the wavelength of the third-step laser across the ionic resonance lines of the Eu 6s＋→ 6p＋. The configuration interaction is discussed by comparing the angular distributions of ejected electrons from the different states. The present study reveals the profound variations of anisotropic parameters in the entire region of autoionization resonance, highlighting the complicated nature of the autoionization process for the lowest member of6p1/26 d autoionization series.展开更多
We present photoelectron angular distribution of the aligned molecular ion H2^＋ by intense ultrashort attosecond extreme ultraviolet laser pulses from numerical solutions of timedependent Schrodinger equations. Photo...We present photoelectron angular distribution of the aligned molecular ion H2^＋ by intense ultrashort attosecond extreme ultraviolet laser pulses from numerical solutions of timedependent Schrodinger equations. Photoionization from a superposition state of the ground 1sσg and the excited 2pσu states with pulses at photon energies above the ionization potential, hω〉Ip, and intensity 10^14 W/cm^2, yields pulse duration dependent asymmetry of photoelectron angular distributions. We attribute the asymmetry to the periodical oscillation of the coherent electron wave packets, resulting from the interference of the two electronic states. For the processes with long pulse durations, such duration dependence is absent and symmetric angular distributions are obtained.展开更多
Element contents of tree rings and soils near tree roots collected from Deodar cedar (Cedrus deodara (Roxb.) G. Don) and Masson pine (Picks massoniana lamb.) were determined to study the relationship between the angul...Element contents of tree rings and soils near tree roots collected from Deodar cedar (Cedrus deodara (Roxb.) G. Don) and Masson pine (Picks massoniana lamb.) were determined to study the relationship between the angular distribution of element contents in tree rings and the environmental information. The chemical composition and properties of soils are very much complicated, which leads to the non-uniform distribution of the element contents in tree rings. The statistical multi-variable regression method was used to got the information of the tree-centered distribution of element contents in the environment (soil) (C’), C’(z, θj ), from the distribution of element contents in tree rings (C), C(Z, θi), which depends on the plane azimuth angle (θi), i. e., C=C(Z,θi), where Z is the atomic number of the element, with a satisfactory result,though this study is only a primary one.展开更多
The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_（1/2）nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ion...The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_（1/2）nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ionizing states,the relevant bound Rydberg states have to be detected first.Two new bound Rydberg states are identified in the region between41150 cm^（-1）and 44580 cm^（-1）,from which auto-ionization spectra of the Eu 4f^76p_（1/2）nd states are observed with isolated core excitation method.With all preparations above,the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically.Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed,followed by a qualitative interpretation.展开更多
We theoretically study the dependence of photoelectron angular distribution on laser polarization direction in nitrogen molecules. The approach is based on the time-dependent density functional theory at the level of ...We theoretically study the dependence of photoelectron angular distribution on laser polarization direction in nitrogen molecules. The approach is based on the time-dependent density functional theory at the level of local density approximation complemented by self-interaction correction. It is found that photoelectron emission in one photon regime could be considered as a probing tool for the main character of different types of molecular orbitals （σ or π）. The pattern of emitted photoelectrons strongly depends on the polarized angle of the laser, for σ orbital, the number of photoelectron decreases with increasing the polarized angle, while for π orbital, it has the inverse relation to the polarized angle, which reveals the multi-electron effect in molecules. On the other hand, concerning the total photoelectron emission, one should take into account a few occupied orbitals instead of only the outmost one.展开更多
In this paper a systematic study is carried out on the angular distribution and polarization of photons emitted following radiative recombination of H-like ions by a non-relativistic dipole approximation. In order to ...In this paper a systematic study is carried out on the angular distribution and polarization of photons emitted following radiative recombination of H-like ions by a non-relativistic dipole approximation. In order to incorporate the screening effect due to inner-shell electrons, a distorted wave approazh is used. The dependences of the calculated angular distribution and polarization on the reduced energy and nuclear charge are fitted by the corresponding empirical formulas respectively.展开更多
The photoelectron angular distributions （PADs） of hydrogen atoms in an intense laser field of linear polarization are studied using the S-matrix theory in the length gauge. The PADs show main lobes along the laser p...The photoelectron angular distributions （PADs） of hydrogen atoms in an intense laser field of linear polarization are studied using the S-matrix theory in the length gauge. The PADs show main lobes along the laser polarization and jet-like structures sticking from the waist of main lobes. Our previous prediction, based on a nonperturbative scattering theory of photoionization developed by Guo et al, showing that the number of jets on one side of PADs may increase by one, three, or other odd numbers and may decrease by one when one more photon is absorbed, is confirmed by this treatment. Within the strong-field approximation, good agreement is obtained between these two quite different treatments. We further study the influence of the Coulomb attraction to PADs, by taking a Coulomb-Volkov state as the continuum state of photoelectrons. We find that under the influence of the Coulomb attraction, the PADs change greatly but the predicted phenomena still appear. This study verifies that the jet-like structures have no relation with the angular momentum of photoelectrons.展开更多
We theoretically investigate the strong-field ionization of H＋2 molecules in four different electronic states by calculating photoelectron angular distributions in circularly polarized fields. We find that the struct...We theoretically investigate the strong-field ionization of H＋2 molecules in four different electronic states by calculating photoelectron angular distributions in circularly polarized fields. We find that the structure of photoelectron angular distribution depends on the molecular orbital as well as the energy of the photoelectron. The location of main lobes changes with the symmetric property of the molecular orbital. Generally, for molecules with bonding electronic states, the photoelectron’s angular distribution shows a rotation of π/2 with respect to the molecular axis, while for molecules with antibonding electronic states, no rotation occurs. We use an interference scenario to interpret these phenomena. We also find that, due to the interference effect, a new pair of jets appears in the waist of the main lobes, and the main lobes or jets of the photoelectron’s angular distribution are split into two parts if the photoelectron energy is sufficiently high.展开更多
The radiation budget at the top of the atmosphere plays a critical role in climate research. Compared to the broadband flux, the spectrally resolved outgoing longwave radiation or flux （OLR）, with rich atmospheric i...The radiation budget at the top of the atmosphere plays a critical role in climate research. Compared to the broadband flux, the spectrally resolved outgoing longwave radiation or flux （OLR）, with rich atmospheric information in different bands, has obvious advantages in the evaluation of GCMs. Unlike methods that need auxiliary measurements and information, here we take atmospheric infrared sounder （AIRS） observations as an example to build a self-consistent algorithm by an angular distribution model （ADM）, based solely on radiance observations, to estimate clear-sky spectrally resolved fluxes over tropical oceans. As the key step for such an ADM, scene type estimations are obtained from radiance and brightness temperature in selected AIRS channels. Then, broadband OLR as well as synthetic spectral fluxes are derived by the spectral ADM and validated using both synthetic spectra and CERES （Clouds and the Earth＇s Radiant Energy System） observations. In most situations, the mean OLR differences between the spectral ADM products and the CERES observations are within -4-2 W m-2, which is less than 1% of the typical mean clear-sky OLR over tropical oceans. The whole algorithm described in this study can be easily extended to other similar hyperspectral radiance measurements.展开更多
We investigate the intensity effect of ultrashort assisting infrared laser pulse on the single-XUV-photon double ionization of helium atoms by solving full six-dimensional time-dependent Schrodinger equation with impl...We investigate the intensity effect of ultrashort assisting infrared laser pulse on the single-XUV-photon double ionization of helium atoms by solving full six-dimensional time-dependent Schrodinger equation with implement of finite element discrete variable representation.The studies of joint energy distributions and joint angular distributions of the two photoelectrons reveal the competition for ionized probabilities between the photoelectrons with odd parity and photoelectrons with even parity in single-XUV-photon double ionization process in the presence of weak infrared laser field,and such a competition can be modulated by changing the intensity of the weak assisting-IR laser pulses.The emission angles of the two photoelectrons can be adjusted by changing the laser parameters as well.We depict how the assisting-IR laser field enhances and/or enables the back-to-back and side-by-side emission of photoelectrons created in double ionization process.展开更多
Angular distribution of radiation temperature from a laser-driven hohlraum is vital for investigations on the radiation field inside the hohlraum, code validation, and predication of drive on the capsule in indirect-d...Angular distribution of radiation temperature from a laser-driven hohlraum is vital for investigations on the radiation field inside the hohlraum, code validation, and predication of drive on the capsule in indirect-drive inertial confinement fusion. A modified version of the view-factor method including plasma filling is proposed, which improves the accuracy of the description of angular distribution of radiation temperature. Firstly, the radial velocity of the gold bubble motion is scaled from a simple data-based model in a gas-filled hohlraum experiment performed on a hundreds of kJ laser facility in China. Then, an equivalent radiative volume model is advanced to approximately characterize the contribution of the blow-off bubble in the new view-factor method incorporate into IRAD3D. The simulation shows reasonable agreement with experimental measurements in a gas-filled hollow hohlraum. Furthermore, the influence of the electron density and temperature distribution, and bubble velocity, is analyzed. The value of the method is that it can be used as an approximate 'first-look' at hohlraum energy balance prior to a more detailed radiation hydrodynamic modeling.展开更多
The angular distribution of CH3I is investigated experimentally using a single Fourier transform-limited laser pulse and a pulse train, where a 90-fs 800-nm linearly polarized laser field with a moderate intensity of ...The angular distribution of CH3I is investigated experimentally using a single Fourier transform-limited laser pulse and a pulse train, where a 90-fs 800-nm linearly polarized laser field with a moderate intensity of 2.8 × 10^13 W/cm2 is used. The dynamic alignment is demonstrated in a single pulse experiment. Moreover, a pulse train is used to optimize the molecular alignment, and the alignment degree is almost identical to that with the single pulse. The results are analysed by using chirped femtosecond laser pulses, and it demonstrates that the structure of pulse train rather than its effective duration is crucial to the molecular alignment.展开更多
This paper uses a nonperturbative scattering theory to study photoelectron angular distributions of homonuclear diatomic molecules irradiated by circularly polarized laser fields. This study shows that the nonisotropi...This paper uses a nonperturbative scattering theory to study photoelectron angular distributions of homonuclear diatomic molecules irradiated by circularly polarized laser fields. This study shows that the nonisotropic feature of photoelectron angular distributions is not due to the polarization of the laser field but the internuclear vector of the molecules. It suggests a method to measure the molecular orientation and the internuclear distance of molecules through the measurement of photoelectron angular distributions.展开更多
A BaF2 time differential perturbed angular distribution spectrometer has been established at the HI-13 tandem accelerator in CIAE. The time resolution of the spectrometer is 195 ps and the nonlinearity is less than 2 ...A BaF2 time differential perturbed angular distribution spectrometer has been established at the HI-13 tandem accelerator in CIAE. The time resolution of the spectrometer is 195 ps and the nonlinearity is less than 2 %. The spectrometer works very stably and no time drift is found over a period of experimelltal ruffs. This spectrometer has been successfully used in the g-factor measurement of 43 Sc (19/2-,3.1232 MeV).展开更多
An experiment investigating gamma emission in hadron therapy was performed at Cyclotron Centre Bronowice (CCB), Cracow, Poland, using two different phantom materials—carbon and poly(methyl methacrylate) PMMA. The mea...An experiment investigating gamma emission in hadron therapy was performed at Cyclotron Centre Bronowice (CCB), Cracow, Poland, using two different phantom materials—carbon and poly(methyl methacrylate) PMMA. The measurements were carried out at 70 MeV proton beam energy and the gamma quanta were registered with the use of HP Ge detector with scintillation anti-Compton shielding. Although the primary aim was to establish a solid experimental data base for future applications in prompt gamma imaging, the data have also been analyzed with regards to the position and shape of the spectral line stemming from deexcitation of the carbon excited state 4.44 MeV. Measurements potentially useful to determine the cross section were performed only at 90° laboratory polar angle. However, benefiting from the very good energy resolution it turned out possible to extract information on angular distribution of the C* (4.44 MeV) deexcitation by analyzing the associated line shape. This paper presents the scheme of model calculations assuming the whole process can be divided into two stages: excitation of carbon nuclei by impinging protons and deexcitation of the C* (4.44 MeV) state.展开更多
The g-factor hence the magnetic moment,of the isomeric state <sup>43</sup>Sc（|9/2<sup>-</sup>,3.1232 MeV）has been measured by the time differential perturbed angular distributionmethod.The me...The g-factor hence the magnetic moment,of the isomeric state <sup>43</sup>Sc（|9/2<sup>-</sup>,3.1232 MeV）has been measured by the time differential perturbed angular distributionmethod.The measured values are g=0.3279（19）and μ=3.108（18）nm.展开更多
A method based on the dinuclear system(DNS)is proposed to describe the angular distribution of products in multinucleon transfer(MNT)reactions.By considering fluctuation effects,the angular distributions of reactions ...A method based on the dinuclear system(DNS)is proposed to describe the angular distribution of products in multinucleon transfer(MNT)reactions.By considering fluctuation effects,the angular distributions of reactions involving^(136)Xe+^(208)Pb,^(136)Xe+^(209)Bi,^(86)Kr+^(166)Er,^(84)Kr+^(209)Bi,and^(84)Kr+^(208)Pb are examined,demonstrating good agreement with experimental data.Moreover,the double differential cross-sections(dσ^(2)/dl_(i)dΘand dσ^(2)/dZdΘ)of reactions^(136)Xe+^(208)Pb and^(136)Xe+^(209)Bi are analyzed to explore the mechanism of angular distribution in MNT reactions.Additionally,the optimal angles for detecting N=126 isotopes are determined via an analysis on the influence of proton and neutron numbers of the projectiles on the angular distribution of the N=126 isotopic line.The results of this study can provide valuable insights for experimental detection.展开更多
The angular distribution of 1 H（ 6 He,p） 6 He elastic scattering has been measured at E c.m. = 4.3 MeV by using a thick-target inverse kinematic method. The experimental differential cross sections are reproduced by...The angular distribution of 1 H（ 6 He,p） 6 He elastic scattering has been measured at E c.m. = 4.3 MeV by using a thick-target inverse kinematic method. The experimental differential cross sections are reproduced by the distorted-wave Born approximation calculation utilizing the CH89 global optical potential parameter set. The real part of CH89 is reduced comparing with other potentials, which may be attributed to the couplings necessary for the weakly bound nuclei.展开更多
Photoelectron angular distributions （PADs） from two-photon ionization of atoms in linearly polarized strong laser fields are obtained in accordance with the nonperturbative quantum scattering theory. We also study t...Photoelectron angular distributions （PADs） from two-photon ionization of atoms in linearly polarized strong laser fields are obtained in accordance with the nonperturbative quantum scattering theory. We also study the influence of laser wavelength on PADs. For two-photon ionization very close to the ionization threshold, most of the ionized electrons are vertically ejected to the laser polarization. PADs from two- photon ionization of atoms are determined by the second order generalized phased Bessel function at which the ponderomotive parameter plays a key role. In terms of dependence of PADs on laser wavelength, corresponding variations for the ponderomotive parameter are demonstrated.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11490561,11635015,11961141003,11805280,11975316,12075045,12005304,U1867212,U1867214)the National Key Research and Development Project(Nos.2016YFA0400502,2018YFA0404404)+1 种基金the Continuous Basic Scientific Research Project(No.WDJC-2019-13)the Leading Innovation Project(Nos.LC192209000701,LC202309000201).
文摘The reaction dynamics of exotic nuclei near the drip line is one of the main research topics of current interest.Elastic scattering is a useful probe for investigating the size and surface diffuseness of exotic nuclei.The development of rare isotope accelerators offers opportunities for such studies.To date,many relevant measurements have been performed at accelerators using the projectile fragmentation technique,while the measurements at accelerators using isotope separator on-line(ISOL)systems are still quite scarce.In this work,we present the first proof-of-principle experiment with a post-accelerated ISOL beam at the Beijing Radioactive Ion Beam Facility(BRIF)by measuring the angular distribution of elastic scattering for the stable nucleus^(23)Na from the doubly magic nucleus^(40)Ca at energies above the Coulomb barrier.The angular distribution measured by a silicon strip detector array in a scattering chamber using the ISOL beam at BRIF is in good agreement with that measured by the high-precision Q3 D magnetic spectrograph using the nonISOL beam at nearly the same energy.This work provides useful background for making BRIF a powerful tool for the investigation of the reaction dynamics of exotic nuclei.
基金Project supported by the National Natural Science Foundation of China(Grant No.11174218)
文摘The combination of a velocity mapping imaging technique and mathematical transformation is adopted to study the angular distribution of electrons ejected from the Eu 4f76p1/26 d autoionizing states, which are excited with a three-step excitation scheme via different Eu 4f76s6d8 D J（J = 5/2, 7/2, and 9/2） intermediate states. In order to determine the energy dependence of angular distribution of the ejected electrons, the anisotropic parameters are measured in the spectral profile of the 6p1/26 d autoionizing states by tuning the wavelength of the third-step laser across the ionic resonance lines of the Eu 6s＋→ 6p＋. The configuration interaction is discussed by comparing the angular distributions of ejected electrons from the different states. The present study reveals the profound variations of anisotropic parameters in the entire region of autoionization resonance, highlighting the complicated nature of the autoionization process for the lowest member of6p1/26 d autoionization series.
基金This work was supported by the National Natural Science Foundation of China （No.21222308, No.21103187, and No.21133006）, the Chinese Academy of Sciences, and the National Basic Research Program of China （No. 2013CB922200）.
文摘We present photoelectron angular distribution of the aligned molecular ion H2^＋ by intense ultrashort attosecond extreme ultraviolet laser pulses from numerical solutions of timedependent Schrodinger equations. Photoionization from a superposition state of the ground 1sσg and the excited 2pσu states with pulses at photon energies above the ionization potential, hω〉Ip, and intensity 10^14 W/cm^2, yields pulse duration dependent asymmetry of photoelectron angular distributions. We attribute the asymmetry to the periodical oscillation of the coherent electron wave packets, resulting from the interference of the two electronic states. For the processes with long pulse durations, such duration dependence is absent and symmetric angular distributions are obtained.
文摘Element contents of tree rings and soils near tree roots collected from Deodar cedar (Cedrus deodara (Roxb.) G. Don) and Masson pine (Picks massoniana lamb.) were determined to study the relationship between the angular distribution of element contents in tree rings and the environmental information. The chemical composition and properties of soils are very much complicated, which leads to the non-uniform distribution of the element contents in tree rings. The statistical multi-variable regression method was used to got the information of the tree-centered distribution of element contents in the environment (soil) (C’), C’(z, θj ), from the distribution of element contents in tree rings (C), C(Z, θi), which depends on the plane azimuth angle (θi), i. e., C=C(Z,θi), where Z is the atomic number of the element, with a satisfactory result,though this study is only a primary one.
基金Project supported by the National Natural Science Foundation of China(Grant No.11174218)
文摘The branching ratios of ions and the angular distributions of electrons ejected from the Eu 4f^76p_（1/2）nd auto-ionizing states are investigated with the velocity-map-imaging technique.To populate the above auto-ionizing states,the relevant bound Rydberg states have to be detected first.Two new bound Rydberg states are identified in the region between41150 cm^（-1）and 44580 cm^（-1）,from which auto-ionization spectra of the Eu 4f^76p_（1/2）nd states are observed with isolated core excitation method.With all preparations above,the branching ratios from the above auto-ionizing states to different final ionic states and the angular distributions of electrons ejected from these processes are measured systematically.Energy dependence of branching ratios and anisotropy parameters within the auto-ionization spectra are carefully analyzed,followed by a qualitative interpretation.
文摘We theoretically study the dependence of photoelectron angular distribution on laser polarization direction in nitrogen molecules. The approach is based on the time-dependent density functional theory at the level of local density approximation complemented by self-interaction correction. It is found that photoelectron emission in one photon regime could be considered as a probing tool for the main character of different types of molecular orbitals （σ or π）. The pattern of emitted photoelectrons strongly depends on the polarized angle of the laser, for σ orbital, the number of photoelectron decreases with increasing the polarized angle, while for π orbital, it has the inverse relation to the polarized angle, which reveals the multi-electron effect in molecules. On the other hand, concerning the total photoelectron emission, one should take into account a few occupied orbitals instead of only the outmost one.
基金Project supported by the National Science Foundation of China （Grant Nos 10574029 and 10434050）, the Chinese Association of Atomic and Molecular Data and National High-Tech ICF Committee in China.
文摘In this paper a systematic study is carried out on the angular distribution and polarization of photons emitted following radiative recombination of H-like ions by a non-relativistic dipole approximation. In order to incorporate the screening effect due to inner-shell electrons, a distorted wave approazh is used. The dependences of the calculated angular distribution and polarization on the reduced energy and nuclear charge are fitted by the corresponding empirical formulas respectively.
基金Project supported by the Rising Star Programme of Shanghai,the National Natural Science Foundation of China (Grant No 10774153)the National Key Basic Research Program of China (Grant No 2006CD806000)
文摘The photoelectron angular distributions （PADs） of hydrogen atoms in an intense laser field of linear polarization are studied using the S-matrix theory in the length gauge. The PADs show main lobes along the laser polarization and jet-like structures sticking from the waist of main lobes. Our previous prediction, based on a nonperturbative scattering theory of photoionization developed by Guo et al, showing that the number of jets on one side of PADs may increase by one, three, or other odd numbers and may decrease by one when one more photon is absorbed, is confirmed by this treatment. Within the strong-field approximation, good agreement is obtained between these two quite different treatments. We further study the influence of the Coulomb attraction to PADs, by taking a Coulomb-Volkov state as the continuum state of photoelectrons. We find that under the influence of the Coulomb attraction, the PADs change greatly but the predicted phenomena still appear. This study verifies that the jet-like structures have no relation with the angular momentum of photoelectrons.
基金the National Natural Science Foundation of China(Grant Nos.11104167,11174304,and 61078080)the Excellent Middle-Aged and Youth Scientist Award of Shandong Province,China(Grant No.BS2011SF021) and the Scientific Research Foundation for the Returned Overseas Chinese Scholars
文摘We theoretically investigate the strong-field ionization of H＋2 molecules in four different electronic states by calculating photoelectron angular distributions in circularly polarized fields. We find that the structure of photoelectron angular distribution depends on the molecular orbital as well as the energy of the photoelectron. The location of main lobes changes with the symmetric property of the molecular orbital. Generally, for molecules with bonding electronic states, the photoelectron’s angular distribution shows a rotation of π/2 with respect to the molecular axis, while for molecules with antibonding electronic states, no rotation occurs. We use an interference scenario to interpret these phenomena. We also find that, due to the interference effect, a new pair of jets appears in the waist of the main lobes, and the main lobes or jets of the photoelectron’s angular distribution are split into two parts if the photoelectron energy is sufficiently high.
基金supported by the National Natural Science Foundation of China (Grant No. 41105015)
文摘The radiation budget at the top of the atmosphere plays a critical role in climate research. Compared to the broadband flux, the spectrally resolved outgoing longwave radiation or flux （OLR）, with rich atmospheric information in different bands, has obvious advantages in the evaluation of GCMs. Unlike methods that need auxiliary measurements and information, here we take atmospheric infrared sounder （AIRS） observations as an example to build a self-consistent algorithm by an angular distribution model （ADM）, based solely on radiance observations, to estimate clear-sky spectrally resolved fluxes over tropical oceans. As the key step for such an ADM, scene type estimations are obtained from radiance and brightness temperature in selected AIRS channels. Then, broadband OLR as well as synthetic spectral fluxes are derived by the spectral ADM and validated using both synthetic spectra and CERES （Clouds and the Earth＇s Radiant Energy System） observations. In most situations, the mean OLR differences between the spectral ADM products and the CERES observations are within -4-2 W m-2, which is less than 1% of the typical mean clear-sky OLR over tropical oceans. The whole algorithm described in this study can be easily extended to other similar hyperspectral radiance measurements.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774131 and 91850114).
文摘We investigate the intensity effect of ultrashort assisting infrared laser pulse on the single-XUV-photon double ionization of helium atoms by solving full six-dimensional time-dependent Schrodinger equation with implement of finite element discrete variable representation.The studies of joint energy distributions and joint angular distributions of the two photoelectrons reveal the competition for ionized probabilities between the photoelectrons with odd parity and photoelectrons with even parity in single-XUV-photon double ionization process in the presence of weak infrared laser field,and such a competition can be modulated by changing the intensity of the weak assisting-IR laser pulses.The emission angles of the two photoelectrons can be adjusted by changing the laser parameters as well.We depict how the assisting-IR laser field enhances and/or enables the back-to-back and side-by-side emission of photoelectrons created in double ionization process.
基金supported by National Natural Science Foundation of China (Nos. 11775204, 11805186, 11805187)Presidential Foundation of China Academy of Engineering Physics (No. YZJJLX2018011)。
文摘Angular distribution of radiation temperature from a laser-driven hohlraum is vital for investigations on the radiation field inside the hohlraum, code validation, and predication of drive on the capsule in indirect-drive inertial confinement fusion. A modified version of the view-factor method including plasma filling is proposed, which improves the accuracy of the description of angular distribution of radiation temperature. Firstly, the radial velocity of the gold bubble motion is scaled from a simple data-based model in a gas-filled hohlraum experiment performed on a hundreds of kJ laser facility in China. Then, an equivalent radiative volume model is advanced to approximately characterize the contribution of the blow-off bubble in the new view-factor method incorporate into IRAD3D. The simulation shows reasonable agreement with experimental measurements in a gas-filled hollow hohlraum. Furthermore, the influence of the electron density and temperature distribution, and bubble velocity, is analyzed. The value of the method is that it can be used as an approximate 'first-look' at hohlraum energy balance prior to a more detailed radiation hydrodynamic modeling.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10774056 and 10974070)the Fundamental Research Funds for the Central Universities, China (Grant No. 200903371)the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20100061110045)
文摘The angular distribution of CH3I is investigated experimentally using a single Fourier transform-limited laser pulse and a pulse train, where a 90-fs 800-nm linearly polarized laser field with a moderate intensity of 2.8 × 10^13 W/cm2 is used. The dynamic alignment is demonstrated in a single pulse experiment. Moreover, a pulse train is used to optimize the molecular alignment, and the alignment degree is almost identical to that with the single pulse. The results are analysed by using chirped femtosecond laser pulses, and it demonstrates that the structure of pulse train rather than its effective duration is crucial to the molecular alignment.
基金supported by the National Natural Science Foundation of China (Grant No. 10774153)the National Basic Research Program of China (Grant No. 2006CD806000)the Shanghai "Phosphor" Science Foundation, China (Grant No. 08QH1402400)
文摘This paper uses a nonperturbative scattering theory to study photoelectron angular distributions of homonuclear diatomic molecules irradiated by circularly polarized laser fields. This study shows that the nonisotropic feature of photoelectron angular distributions is not due to the polarization of the laser field but the internuclear vector of the molecules. It suggests a method to measure the molecular orientation and the internuclear distance of molecules through the measurement of photoelectron angular distributions.
文摘A BaF2 time differential perturbed angular distribution spectrometer has been established at the HI-13 tandem accelerator in CIAE. The time resolution of the spectrometer is 195 ps and the nonlinearity is less than 2 %. The spectrometer works very stably and no time drift is found over a period of experimelltal ruffs. This spectrometer has been successfully used in the g-factor measurement of 43 Sc (19/2-,3.1232 MeV).
文摘An experiment investigating gamma emission in hadron therapy was performed at Cyclotron Centre Bronowice (CCB), Cracow, Poland, using two different phantom materials—carbon and poly(methyl methacrylate) PMMA. The measurements were carried out at 70 MeV proton beam energy and the gamma quanta were registered with the use of HP Ge detector with scintillation anti-Compton shielding. Although the primary aim was to establish a solid experimental data base for future applications in prompt gamma imaging, the data have also been analyzed with regards to the position and shape of the spectral line stemming from deexcitation of the carbon excited state 4.44 MeV. Measurements potentially useful to determine the cross section were performed only at 90° laboratory polar angle. However, benefiting from the very good energy resolution it turned out possible to extract information on angular distribution of the C* (4.44 MeV) deexcitation by analyzing the associated line shape. This paper presents the scheme of model calculations assuming the whole process can be divided into two stages: excitation of carbon nuclei by impinging protons and deexcitation of the C* (4.44 MeV) state.
基金supported by National Natural Science Foundation of ChinaNuclear Industry Science Foundation of China
文摘The g-factor hence the magnetic moment,of the isomeric state <sup>43</sup>Sc（|9/2<sup>-</sup>,3.1232 MeV）has been measured by the time differential perturbed angular distributionmethod.The measured values are g=0.3279（19）and μ=3.108（18）nm.
基金Supported by the Guangdong Major Project of Basic and Applied Basic Research(2021B0301030006)the National Natural Science Foundation of China(12175151,12105181,11847235)the Steady Support Program for Higher Education Institutions of Shenzhen(20200817005440001)。
文摘A method based on the dinuclear system(DNS)is proposed to describe the angular distribution of products in multinucleon transfer(MNT)reactions.By considering fluctuation effects,the angular distributions of reactions involving^(136)Xe+^(208)Pb,^(136)Xe+^(209)Bi,^(86)Kr+^(166)Er,^(84)Kr+^(209)Bi,and^(84)Kr+^(208)Pb are examined,demonstrating good agreement with experimental data.Moreover,the double differential cross-sections(dσ^(2)/dl_(i)dΘand dσ^(2)/dZdΘ)of reactions^(136)Xe+^(208)Pb and^(136)Xe+^(209)Bi are analyzed to explore the mechanism of angular distribution in MNT reactions.Additionally,the optimal angles for detecting N=126 isotopes are determined via an analysis on the influence of proton and neutron numbers of the projectiles on the angular distribution of the N=126 isotopic line.The results of this study can provide valuable insights for experimental detection.
基金Supported by National Natural Science Foundation of China(11021504,10875173,11175261,10735100)
文摘The angular distribution of 1 H（ 6 He,p） 6 He elastic scattering has been measured at E c.m. = 4.3 MeV by using a thick-target inverse kinematic method. The experimental differential cross sections are reproduced by the distorted-wave Born approximation calculation utilizing the CH89 global optical potential parameter set. The real part of CH89 is reduced comparing with other potentials, which may be attributed to the couplings necessary for the weakly bound nuclei.
基金supported by the National Natural Science Foundation of China under Grant Nos.60908006,10804067,and 60407007
文摘Photoelectron angular distributions （PADs） from two-photon ionization of atoms in linearly polarized strong laser fields are obtained in accordance with the nonperturbative quantum scattering theory. We also study the influence of laser wavelength on PADs. For two-photon ionization very close to the ionization threshold, most of the ionized electrons are vertically ejected to the laser polarization. PADs from two- photon ionization of atoms are determined by the second order generalized phased Bessel function at which the ponderomotive parameter plays a key role. In terms of dependence of PADs on laser wavelength, corresponding variations for the ponderomotive parameter are demonstrated.
