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Commissioning and Full Realization of the PLASEN System at BRIF

W. C. Mei, H. R. Hu, Y. F. Guo, Z. Yan, X. F. Yang, S. J. Chen, D. Y. Chen, Y. P. Lin, Y. S. Liu, C. Zhang, Y. P. Jing, T. X. Gao, X. Shen, Y. Y. Jia, Y. T. Lin, H. X. Zhang, S. W. Bai, B. Tang, X. Ma, G. F. Song, S. Ye, M. Y. Lu, J. Y. Dong, B. K. Dong, J. H. Lv, S. Y. Dong, F. C. Liu, Z. Hu, X. Liu, S. T. Zhu, Y. L. Yi, C. Y. He, A. Takamine, B. Q. Cui, J. Yang, Z. Y. Liu, J. Su, H. N. Liu, Y. L. Ye, B. Guo

Abstract

A PLASEN (Precision LAser Spectroscopy for Exotic Nuclei) system, consisting of a compact radio-frequency quadrupole cooler-buncher (RFQ-cb) and a collinear resonance ionization spectroscopy setup, has now been fully commissioned with radioactive ion beams at the Beijing Radioactive Ion-beam Facility (BRIF). Using both stable and radioactive Rb ion beams from BRIF, we demonstrated that the large beam energy spread observed at BRIF has been successfully handled by employing the RFQ-cb, enabling the delivery of high-quality bunched radioactive ion beams for collinear resonance ionization spectroscopy experiments. Under these conditions, we performed laser spectroscopy of exotic nuclei, achieving high resolution (about 100 MHz spectral linewidth) and high sensitivity (up to 1:200 efficiency). This fully operational PLASEN system will serve as a state-of-the-art experimental platform at BRIF for research in multiple fields such as nuclear, atomic and molecular physics.

Commissioning and Full Realization of the PLASEN System at BRIF

Abstract

A PLASEN (Precision LAser Spectroscopy for Exotic Nuclei) system, consisting of a compact radio-frequency quadrupole cooler-buncher (RFQ-cb) and a collinear resonance ionization spectroscopy setup, has now been fully commissioned with radioactive ion beams at the Beijing Radioactive Ion-beam Facility (BRIF). Using both stable and radioactive Rb ion beams from BRIF, we demonstrated that the large beam energy spread observed at BRIF has been successfully handled by employing the RFQ-cb, enabling the delivery of high-quality bunched radioactive ion beams for collinear resonance ionization spectroscopy experiments. Under these conditions, we performed laser spectroscopy of exotic nuclei, achieving high resolution (about 100 MHz spectral linewidth) and high sensitivity (up to 1:200 efficiency). This fully operational PLASEN system will serve as a state-of-the-art experimental platform at BRIF for research in multiple fields such as nuclear, atomic and molecular physics.
Paper Structure (12 sections, 1 equation, 3 figures, 1 table)

This paper contains 12 sections, 1 equation, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. Online PLASEN system at BRIF
  3. BRIF
  4. RFQ cooler buncher
  5. CLS setup
  6. Control and DAQ system
  7. Laser system
  8. Results of online commissioning
  9. Evaluation of the ion-beam energy spread at BRIF
  10. RFQ-cb performance for energy-spread reduction of ion beam at BRIF
  11. High resolution HFS spectra of unstable Rb isotopes
  12. Summary and Outlook

Figures (3)

  • Figure 1: Schematic layout of the online PLASEN system at BRIF. A 100-MeV proton beam bombards a solid target at BRIF to produce radioactive isotopes, which are ionized, accelerated and mass-separated. This continuous ion beam from BRIF is then cooled and bunched by the RFQ-cb. In the CLS beamline, ion bunches are neutralized in the charge-exchange cell, and then resonantly re-ionized by three step laser beams in the interaction region. The re-ionized ion bunches are detected to obtain the hyperfine-structure spectrum. The BRIF shown in the top-right inset is schematically scaled down and not to scale. See text for details.
  • Figure 2: (a) Energy fluctuation and (b) voltage distributions of ion-beam delivery platform at BRIF, with proton (blue) and without proton (red) on target. The vertical axis were presented in arbitrary units (a.u.) for panel (b). (c) Power spectral density (PSD) of noise in the 20-kV HV with proton (blue) and without proton (red) on target, exhibiting typical response characteristics of a moving average filter. Under proton irradiation, the HV noise with proton shows a significant increase at all frequencies. (d) High resolution spectrum of $\mathrm{^{87}Rb}$ measured under the conditions with (blue) and without proton (red) on target. The dashed line represents the simulated spectrum after accounting for Doppler broadening from the $22.04$ eV energy spread, while the solid line shows a simulated spectrum with a best resolution achievable of about 30 MHz. $\mathit{\Gamma}$ is the total FWHM of the spectral line. See text for details.
  • Figure 3: Measured high resolution HFS spectra in the unstable $\mathrm{^{92,95}Rb}$ fitted with a asymmetric pseudo-Voigt line profile (solid line). See text for details.