Search

Your search keyword '"Zhao, D. M."' showing total 159 results
Start Over Author "Zhao, D. M."
159 results on '"Zhao, D. M."'

2. Measurement of n-resolved State-Selective Charge Exchange in Ne(8,9)+ Collision with He and H2

Author

Xu, J. W., Xu, C. X., Zhang, R. T., Zhu, X. L., Feng, W. T., Gu, L., Liang, G. Y., Guo, D. L., Gao, Y., Zhao, D. M., Zhang, S. F., Su, M. G., and Ma, X.

Subjects
Astrophysics - Astrophysics of Galaxies, Physics - Atomic Physics
Abstract

Charge exchange between highly charged ions and neutral atoms and molecules has been considered as one of the important mechanisms controlling soft X ray emissions in many astrophysical objects and environments. However, for modeling charge exchange soft X ray emission, the data of n and l resolved state selective capture cross sections are often obtained by empirical and semiclassical theory calculations. With a newly built cold target recoil ion momentum spectroscopy (COLTRIMS) apparatus, we perform a series of measurements of the charge exchange of Ne(8,9)+ ions with He and H2 for collision energy ranging from 1 to 24.75 keV/u. n resolved state selective capture cross-sections are reported. By comparing the measured state selective capture cross sections to those calculated by the multichannel Landau Zener method (MCLZ), it is found that MCLZ calculations are in good agreement with the measurement for the dominant n capture for He target. Furthermore, by using nl resolved cross sections calculated by MCLZ and applying l distributions commonly used in the astrophysical literature to experimentally derived n resolved cross sections, we calculate the soft X ray emissions in the charge exchange between 4 keV/u Ne8+ and He by considering the radiative cascade from the excited Ne7+ ions. Reasonable agreement is found in comparison to the measurement for even and separable models, and MCLZ calculations give results in a better agreement.

Published
2021
Full Text
View/download PDF

3. State-selective single-electron capture in 30 keV N3+-He collisions

Author

Xua, J. W., Zhu, X. L., Feng, W. T., Zhao, D. M., Guo, D. L., Gao, Y., Zhang, S. F., and Ma, X

Subjects
Physics - Atomic Physics
Abstract

The Cold-target recoil-ion momentum spectroscopy (COLTRIMS) has been employed to study the single-electron capture processes in collisions of N3+ ions with He atoms at an impact energy of 30 keV. The relative differential cross sections for the capture to different orbitals of N3+ ions are obtained and are compared with other experiments at low energy. The predictions of the molecular Columbic barrier model have been made. From the longitudinal momentum spectrum of recoil ions, the different electronic configuration was identified and the metastable projectile ions were distinguished. The single electron capture into the N2+ (1s22s22p 2P) state from the ground state N3+ (1s22s2 1S) projectile is the dominant reaction channel. The fraction of the metastable state N3+(2s2p 3P) of the incident projectile beam is about 46%.

Published
2019
Full Text
View/download PDF

6. A high resolution reaction microscope with universal two-region time-focusing method.

Author

Gao, Y., Cao, T., Lin, K. Z., Guo, D. L., Zhang, S. F., Zhu, X. L., Zhang, R. T., Yan, S. C., Xu, S., Zhao, D. M., and Ma, X.

Subjects
ATOMIC beams, ION-atom collisions, ELECTRON capture, HELIUM ions, ION beams
Abstract

This paper presents a novel reaction microscope designed for ion–atom collision investigations, established at the Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China. Its time-of-flight (TOF) spectrometer employs an innovative flight-time focusing method consisting of two acceleration regions, providing optimal time focusing conditions for charged fragments with diverse initial velocities. The TOF spectrometer's axis intentionally tilts by 12° relative to the ion beam direction, preventing potential obstructions from the TOF grid electrodes. The introduced focusing method allows for a flexible time-focusing TOF spectrometer design without restricting the length ratio of the two regions. In addition, this configuration in our case significantly suppresses noise on the recoil ion detector produced by residual gas in the ion beam trajectory, which is a considerable challenge in longitudinal spectrometers. In a test experiment on the single electron capture reaction involving 62.5 keV/u He2+ ions and a helium atomic beam, the recoil longitudinal momentum resolution achieved 0.068 atomic units. This novel configuration and successful test run show excellent precision for ion–atom collision studies. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

7. Two- and three-body dissociations of C3H6 isomer dications investigated by 4 keV/u Ar8+ impact.

Author

Guo, D. L., Lin, K. Z., Zhu, X. L., Zhang, R. T., Gao, Y., Zhao, D. M., Zhu, X. B., Zhang, S. F., and Ma, X.

Subjects
BRANCHING ratios, SCISSION (Chemistry), ISOMERS, CYCLOPROPANE, POTASSIUM channels, PROPENE
Abstract

The fragmentation dynamics of two isomers of C3H6, cyclopropane and propene, induced by 4 keV/u Ar8+ are investigated employing a reaction microscope. Four two-body and two three-body dissociation channels of C 3 H 6 2 + dications are identified for each isomer, among which the channels involving CC bond breaking are found to be much more favored than H 3 + and H 2 + formation channels. The observation of the CH 3 + or H 3 + formation channels from cyclopropane are direct evidence of the proton migration within the carbon skeleton before dissociation. Obvious isomer effects are revealed by comparing the relative branching ratios of different channels of the two isomers. Moreover, it was shown that a sequential dissociation mechanism with H elimination prior to CC bond cleavage may be dominant for the two three-body dissociation channels for both isomers. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

8. Longitudinal Schottky spectra of a bunched Ne10+ ion beam at the CSRe

Author

Wen, W. Q., Ma, X., Zhang, D. C., Zhu, X. L., Meng, L. J., Li, J., Liu, H. P., Zhao, D. M., Wang, Z. S., Mao, R. S., Zhao, T. C., Wu, J. X., Ma, X. M., Yan, T. L., Li, G. H., Yang, X. D., Liu, Y., Yang, J. C., Yuan, Y. J., Xia, J. W., Xu, H. S., Xiao, G. Q., and Zhao, H. W.

Subjects
Physics - Accelerator Physics
Abstract

The longitudinal Schottky spectra of a radio-frequency (RF) bunched and electron cooled 22Ne10+ ion beam at 70 MeV/u have been studied by a newly installed resonant Schottky pick-up at the experimental cooler storage ring (CSRe), at IMP. For an RF-bunched ion beam, a longitudinal momentum spread of has been reached with less than 107 stored ions. The reduction of momentum spread compared with coasting ion beam was observed from Schottky noise signal of the bunched ion beam. In order to prepare the future laser cooling experiment at the CSRe, the RF-bunching power was modulated at 25th, 50th and 75th harmonic of the revolution frequency, effective bunching amplitudes were extracted from the Schottky spectrum analysis. Applications of Schottky noise for measuring beam lifetime with ultra-low intensity of ion beams are presented, and it is relevant to upcoming experiments on laser cooling of relativistic heavy ion beams and nuclear physics at the CSRe., Comment: to be published in Chinese Physics C

Published
2013
Full Text
View/download PDF

9. Study of state-selective single-electron capture in slow Ne 7+ colliding with He and H2 target.

Author

Zhu, X B, Xing, D D, Lin, K Z, Cui, S C, Zhu, X L, Gao, Y, Guo, D L, Zhao, D M, Zhang, S F, and Ma, X

Subjects
ELECTRON capture, DIFFERENTIAL cross sections, COLLISIONS (Nuclear physics), ANGULAR distribution (Nuclear physics), COLLISION broadening, ION-atom collisions
Abstract

Using the cold target recoil-ion momentum spectroscopy, we measured the state-selective single electron capture in collisions of 3.5–6.3 keV u−1 Ne7+ ions and He and H2. The Q -value spectra and angular distributions as a function of the projectile incident energy were obtained. The results show that the single electron capture into n = 4 states is the dominant reaction channel for the Ne7+-He system, while the capture into n = 4 and n = 5 states both are dominant processes for the Ne7+-H2 system. The molecular coulombic barrier model and the potential energy curves can qualitatively explain the measured state populations for both systems. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

20. Absolute rate coefficients for dielectronic recombination of Na-like Kr25+

Author

Huang, Z. K., primary, Wen, W. Q., additional, Wang, S. X., additional, Khan, N., additional, Wang, H. B., additional, Chen, C. Y., additional, Zhang, C. Y., additional, Preval, S. P., additional, Badnell, N. R., additional, Ma, W. L., additional, Liu, X., additional, Chen, D. Y., additional, Zhu, X. L., additional, Zhao, D. M., additional, Mao, L. J., additional, Ma, X. M., additional, Li, J., additional, Tang, M. T., additional, Mao, R. S., additional, Yin, D. Y., additional, Yang, W. Q., additional, Yang, J. C., additional, Yuan, Y. J., additional, Zhu, L. F., additional, and Ma, X., additional

Published
2020
Full Text
View/download PDF

21. Rate Coefficients for Dielectronic Recombination of Carbon-like 40Ca14+

Author

Wen, W. Q., primary, Huang, Z. K., additional, Wang, S. X., additional, Khan, N., additional, Wang, H. B., additional, Chen, C. Y., additional, Zhang, C. Y., additional, Preval, S., additional, Badnell, N. R., additional, Ma, W. L., additional, Chen, D. Y., additional, Liu, X., additional, Zhao, D. M., additional, Mao, L. J., additional, Li, J., additional, Ma, X. M., additional, Tang, M. T., additional, Yin, D. Y., additional, Yang, W. Q., additional, Yuan, Y. J., additional, Yang, J. C., additional, Zhu, L. F., additional, and Ma, X., additional

Published
2020
Full Text
View/download PDF

25. Electron-ion recombination rate coefficients of carbon-like Ar12+

Author

Mahmood, S, primary, Huang, Z K, additional, Wen, W Q, additional, Wang, S X, additional, Chen, C Y, additional, Khan, N, additional, Xu, X, additional, Dou, L J, additional, Wang, H B, additional, Zhu, X L., additional, Zhao, D M, additional, Mao, L J, additional, Ma, X M, additional, Li, J, additional, Tang, M T, additional, Mao, R S, additional, Yang, W Q, additional, Yin, D Y, additional, Yuan, Y J, additional, Yang, J C, additional, Zhu, L F, additional, and Ma, X, additional

Published
2020
Full Text
View/download PDF

37. Rate Coefficients for Dielectronic Recombination of Carbon-like 40Ca14+.

Author

Wen, W. Q., Huang, Z. K., Wang, S. X., Khan, N., Wang, H. B., Chen, C. Y., Zhang, C. Y., Preval, S., Badnell, N. R., Ma, W. L., Chen, D. Y., Liu, X., Zhao, D. M., Mao, L. J., Li, J., Ma, X. M., Tang, M. T., Yin, D. Y., Yang, W. Q., and Yuan, Y. J.

Subjects
ION recombination, DELOCALIZATION energy, STORAGE rings, LOW temperatures, PLASMA temperature, CALCIUM ions
Abstract

Dielectronic recombination (DR) rate coefficients for carbon-like 40Ca14+ forming nitrogen-like 40Ca13+ have been measured using the electron–ion merged-beam technique at the heavy-ion storage ring CSRm at the Institute of Modern Physics in Lanzhou, China. The measured DR rate coefficients in the energy range from 0 to 92 eV cover most of the DR resonances associated with 2s22p2 → 2s22p2 and 2s22p2 → 2s2p3 core transitions (ΔN = 0). Theoretical calculations of the DR cross sections were carried out by using two different state-of-the-art atomic theoretical techniques, multiconfiguration Breit–Pauli (MCBP) code AUTOSTRUCTURE and relativistic configuration interaction code FAC, to compare with the experimental rate coefficients. The theoretical calculations agree with the experimental results at collision energy higher than 10 eV. However, significant discrepancies of resonance energies and strengths can be found at collision energy below 8 eV. Temperature-dependent plasma recombination rate coefficients were derived from the measured DR rate coefficients in the energy range from 0.1 to 1000 eV and compared with the recommended atomic data from the literature. The theoretical data of Gu et al. and Zatsarinny et al. are 30% lower than the experimental results at the temperatures of photoionized plasmas, but have a very good agreement at the temperatures of collisionally ionized plasmas. Other previously published theoretical data of Jacobs et al. and Mazzotta et al. by using Burgess formula and LS-coupling calculations significantly underestimate the plasma rate coefficients in the low temperature range. The present results comprise a set of benchmark data suitable for astrophysical modeling. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

38. Measurement of the lifetime and the proportion of 12C3+ ions in stored relativistic ion beams as a preparation for laser cooling experiments at the CSRe

Author

Wang, H. B., Wen, W. Q., Huang, Z. K., Zhang, D. C., Hai, B., Zhu, X. L., Zhao, D. M., Yang, J., Li, J., Li, X. N., Mao, L. J., Mao, R. S., Wu, J. X., Yang, J. C., Yuan, Y. J., Eidam, L., Winters, D., Beck, T., Kiefer, D., Rein, B., Walther, T., Loeser, M., Schramm, U., Siebold, M., Bussmann, M., and Ma, X.

Subjects
Laser cooling, Electron cooling, Schottky pick-up, dynamics, Storage ring, bunched beam
Abstract

We report on an experiment that was conducted in preparation of laser cooling experiments at the heavy-ion storage ring CSRe. The lifetimes of ion beams made up of 12C3+ and 16O4+ ions stored at an energy of 122MeV/u in the CSRe were determined by two independent methods, firstly via a DC current transformer (DCCT) and secondly via a Schottky resonator. Using electron-cooling, the signals of the 12C3+ and 16O4+ ions could be separated and clearly observed in the Schottky spectrum. The obtained individual lifetimes of the 12C3+ and 16O4+ components were 23.6s and 17.8s, respectively. The proportion of 12C3+ ions in the stored ion beam was measured to be more than 70% at the beginning of the injection and increasing as a function of time. In addition to these measurements, the operation and remote control of a pulsed laser system placed directly next to the storage ring was tested in a setup similar to the one envisaged for future laser experiments.

Published
2017

39. Autoionization in the evolution process of dense Rb Rydberg atoms in nP states.

Author

Li, Y. F., Zhao, D. M., Ma, X., and Yang, J.

Subjects
*RYDBERG states, *QUANTUM numbers, *AUGER effect, *BIOLOGICAL evolution, *RADIATION
Abstract

The autoionization mechanisms of dense nP3/2 (n = 20–97) Rydberg gases of 87Rb atoms in the spontaneous evolution were investigated for the first time. By observing the characteristic time of the electrons generated through autoionization process, the dependence of autoionization mechanisms (black‐body radiation, electron–Rydberg collision, and Penning ionization) on the principal quantum number n of initial nP states was demonstrated. The dependence on the number n in nP Rydberg atoms is similar to those in nD Rydberg atoms. [ABSTRACT FROM AUTHOR]

Published
2020
Full Text
View/download PDF

41. Electron–ion Recombination Rate Coefficients of Be-like 40Ca16+

Author

Wang, S. X., primary, Xu, X., additional, Huang, Z. K., additional, Wen, W. Q., additional, Wang, H. B., additional, Khan, N., additional, Preval, S. P., additional, Badnell, N. R., additional, Schippers, S., additional, Mahmood, S., additional, Dou, L. J., additional, Chuai, X. Y., additional, Zhao, D. M., additional, Zhu, X. L., additional, Mao, L. J., additional, Ma, X. M., additional, Li, J., additional, Mao, R. S., additional, Yuan, Y. J., additional, Tang, M. T., additional, Yin, D. Y., additional, Yang, J. C., additional, Ma, X., additional, and Zhu, L. F., additional

Published
2018
Full Text
View/download PDF

42. Orientation effect in Ar dimer fragmentation by highly charged ion impact

Author

Zhu, X L, primary, Yan, S, additional, Feng, W T, additional, Ma, X, additional, Chuai, X Y, additional, Guo, D L, additional, Gao, Y, additional, Zhang, R T, additional, Zhang, P, additional, Zhang, S F, additional, Zhao, D M, additional, Xu, S, additional, Wang, H B, additional, Huang, Z K, additional, and Qian, D B, additional

Published
2018
Full Text
View/download PDF

44. Probing scattering phases via two-center interferences in collisions of He2+ on CO

Author

Gao, Y., primary, Zhang, S. F., additional, Zhu, X. L., additional, Guo, D. L., additional, Schulz, M., additional, Voitkiv, A. B., additional, Zhao, D. M., additional, Hai, B., additional, Zhang, M., additional, Zhang, R. T., additional, Feng, W. T., additional, Yan, S., additional, Wang, H. B., additional, Huang, Z. K., additional, and Ma, X., additional

Published
2018
Full Text
View/download PDF

45. Dielectronic and Trielectronic Recombination Rate Coefficients of Be-like Ar 14+

Author

Huang, Z. K., primary, Wen, W. Q., additional, Xu, X., additional, Mahmood, S., additional, Wang, S. X., additional, Wang, H. B., additional, Dou, L. J., additional, Khan, N., additional, Badnell, N. R., additional, Preval, S. P., additional, Schippers, S., additional, Xu, T. H., additional, Yang, Y., additional, Yao, K., additional, Xu, W. Q., additional, Chuai, X. Y., additional, Zhu, X. L., additional, Zhao, D. M., additional, Mao, L. J., additional, Ma, X. M., additional, Li, J., additional, Mao, R. S., additional, Yuan, Y. J., additional, Wu, B., additional, Sheng, L. N., additional, Yang, J. C., additional, Xu, H. S., additional, Zhu, L. F., additional, and Ma, X., additional

Published
2018
Full Text
View/download PDF

47. Dielectronic recombination of Be-like argon at the CSRm

Author

Huang, Z K, primary, Wen, W Q, additional, Xu, X, additional, Wang, S X, additional, Wang, H B, additional, Dou, L J, additional, Mahmood, S, additional, Khan, N, additional, Xu, W Q, additional, Xu, T H, additional, Yao, K, additional, Chuai, X Y, additional, Zhu, X L, additional, Zhao, D M, additional, Mao, L J, additional, Yang, J C, additional, Yuan, Y J, additional, Zhu, L F., additional, and Ma, X, additional

Published
2017
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results