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Use of an atom trap for measuring electron-impact excitation cross sections out of the excited states of rubidium

M. Larsen, Todd A. Zimmerman, John B. Boffard +2 more

APSMay 1, 20020 citations

Methods of Measuring Electron–Atom Collision Cross Sections with an Atom Trap

R. Scott Schappe, M. L. Keeler, Todd A. Zimmerman +7 more

Advances in atomic, molecular, and optical physicsJan 1, 20026 citations

Absolute Electron-Impact Ionization Cross Section Measurements Using a Magneto-Optical Trap

R. Scott Schappe, Thad G Walker, L. W. Anderson +1 more

We present a new method for measuring absolute total electron-impact ionization cross sections. The technique measures fractional loss rates from a magneto-optical trap due to electron-impact ionization. The method requires only relative measurements of the number of target atoms and therefore eliminates a major source of difficulty in previous experiments. We report total ionization cross sections of Rb for electron energies from 50 to 500 eV.

Physical Review LettersJun 3, 199657 citations

Measurements of electron-impact total cross section for Cs using cold trapped atoms

D. M. B. P. Milori, A M Tuboy, José Roberto Garbin +1 more

Jan 1, 19980 citations

Electron-atom collisions: From Franck-Hertz experiment to atom traps

Chang-Chun Lin

The key features of the cross sections for electron-impact excitation out of the ground levels of the rare-gas atoms are summarized and application of these cross section data is shown. This is followed by discussions of recent experiments on determination of electron-impact cross sections for excitation out of the metastable levels of He and Ar. The metastiable atom targets are produced by two different methods, i.e., hollow-cathode discharges and charge-exchange collisions of rare-gas ions with Cs atoms. The former method is simple but is limited to low electron energies because of the very small metastable concentration, whereas the latter method yields a fast target beam with predominantly metastable atoms allowing measurements up to the keV range. The measured cross sections show features very different from those of excitation out of the ground levels. Another new development in electron-atom collision is the use of atom traps for measuring ionization cross sections. The experiment is conducted by passing an electron beam pulse through magneto-optically trapped Rb atoms while the trap is momentarily turned off. Turning the trap back on immediately after the electron beam pulse recaptures the unionized atoms allowing only the ions to escape. The ionization cross section is determined bymore » measuring the electron beam current density at the trapped atom region and the fractional loss of trapped atoms due to the electron beam. This method avoids measurements of the absolute number of the target atoms and the overlap between the atomic and electron beams and therefore eliminates the major sources of uncertainty associated with the crossed-beam method for measuring ionization cross section.« lessThe key features of the cross sections for electron-impact excitation out of the ground levels of the rare-gas atoms are summarized and application of these cross section data is shown. This is followed by discussions of recent experiments on determination of electron-impact cross sections for excitation out of the metastable levels of He and Ar. The metastiable atom targets are produced by two different methods, i.e., hollow-cathode discharges and charge-exchange collisions of rare-gas ions with Cs atoms. The former method is simple but is limited to low electron energies because of the very small metastable concentration, whereas the latter method yields a fast target beam with predominantly metastable atoms allowing measurements up to the keV range. The measured cross sections show features very different from those of excitation out of the ground levels. Another new development in electron-atom collision is the use of atom traps for measuring ionization cross sections. The experiment is conducted by passing an electron beam pulse through magneto-optically trapped Rb atoms while the trap is momentarily turned off. Turning the trap back on immediately after the electron beam pulse recaptures the unionized atoms allowing only the ions to escape. The ionization cross section is determined bymore » measuring the electron beam current density at the trapped atom region and the fractional loss of trapped atoms due to the electron beam. This method avoids measurements of the absolute number of the target atoms and the overlap between the atomic and electron beams and therefore eliminates the major sources of uncertainty associated with the crossed-beam method for measuring ionization cross section.« less

Bulletin of the American Physical SocietyMay 1, 19960 citations

Absolute atomic collision cross section measurements using Rb atoms confined in magneto-optic and magnetic traps

David E. Fagnan, J. Wang, Bruce G. Klappauf +2 more

Bulletin of the American Physical SocietyMay 21, 20090 citations

Measurement of Electron-Impact Cross Sections using Trapped Rb atoms

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