Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Europhysics Letters (EPL)

Electron Collision Cross-Sections Measured with the Use of a Magneto-Optical Trap

R. Scott Schappe, P Feng, L. W. Anderson, Chun Chia Lin, Thad G Walker

Published Feb 20, 1995• 34 citations
Publisher

Abstract

We present the first application of optically trapped atoms as targets for a scattering experiment. We report absolute total electron scattering cross-sections for ground-state Rb atoms in the range of 7-500 eV.
DOI
10.1209/0295-5075/29/6/002

Related papers

Electron-Scattering Measurements using a Magneto-Optical Trap

Thad G Walker

Optically trapped atoms are in many ways ideal replacements for atomic beams for scattering experiments. In a typical such experiment, a particle beam ejects atoms from the trap at a rate {Gamma} = {sigma}{phi}, where {phi} is the particle flux density and {sigma} the scattering cross section. {Gamma} is easily measured from trap decay transients. Since the trapped atoms have neV kinetic energies, the method is sensitive to extremely small momentum transfers. Since the beam flux is measured, the absolute target density is not required, removing an important source of error for most atomic beam experiments. At Wisconsin the authors have integrated an electron beam with a magneto-optical trap and performed electron-scattering experiments on Rb atoms in the range of 10-1000 eV. In the first experiment they measured total cross sections for scattering from the 5s state by lowering the capture velocity of the trap below the recoil velocity of the scattered atoms. In the second experiment they isolated the total ionization cross section by operating the trap such that virtually all elastically and inelastically scattered atoms were captured by the trap. These experimental results will test new theoretical methods for calculating total and ionization cross sections. Straightforward extensions ofmore » these methods should allow similar measurements using excited-state atoms (5p, 5d) as well. The techniques should also be readily adaptable to the important case of the metastable noble gases.« less

Bulletin of the American Physical Society•May 1, 1996•0 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 Letters•Jun 3, 1996•57 citations

Electron Collisions with Laser Cooled and Trapped Metastable Helium Atoms: Total Scattering Cross Sections

L. J. Uhlmann, R. G. Dall, Andrew G. Truscott +3 more

Absolute measurements of total scattering cross sections for low energy (5-70 eV) electrons by metastable helium (2(3)S) atoms are presented. The measurements are performed using a magneto-optical trap which is loaded from a laser-cooled, bright beam of slow He(2(3)S) atoms. The data are compared with predictions from convergent close coupling and R matrix with pseudostate calculations, and we find good agreement between experiment and theory.

Physical Review Letters•May 3, 2005•36 citations

Absolute metastable atom-atom collision cross section measurements using a magneto-optical trap

Kristen Matherson, R. D. Glover, D. E. Laban +1 more

We present a new technique to measure absolute total collision cross sections from metastable neon atoms. The technique is based on the observation of the decay rate of trapped atoms as they collide with room temperature atoms. We present the first measurement of this kind using trapped neon atoms in the (3)P(2) metastable state colliding with thermal ground state argon. The measured cross section has a value of 556+/-26 A(2).

Review of Scientific Instruments•Jul 1, 2007•13 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.« less

Bulletin of the American Physical Society•May 1, 1996•0 citations

Measurements of total absolute collision cross section of ultracold Rb atom using magneto-optic and pure magnetic traps

王继成 Jicheng Wang, 王月媛 Yueyuan Wang, 王跃科 Yueke Wang +2 more

The implementation of a technique to measure total collision cross sections using laser-cooled rubidium atoms along with the introduction of room-temperature background gases, confined in both magnetooptic and magnetic traps, is proposed. Atom loss from the trap and total collision cross section can be inferred from the knowledge of the density of background gases. The measured cross sections from the magneto-optic and magnetic traps are represented, compared, and found to be significantly different. The measurements using this technique have a very small error in the range of approximately 2%-7%.

Chinese Optics Letters•Jan 1, 2011•0 citations
Optically trapped atoms are in many ways ideal replacements for atomic beams for scattering experiments. In a typical such experiment, a particle beam ejects atoms from the trap at a rate {Gamma} = {sigma}{phi}, where {phi} is the particle flux density and {sigma} the scattering cross section. {Gamma} is easily measured from trap decay transients. Since the trapped atoms have neV kinetic energies, the method is sensitive to extremely small momentum transfers. Since the beam flux is measured, the absolute target density is not required, removing an important source of error for most atomic beam experiments. At Wisconsin the authors have integrated an electron beam with a magneto-optical trap and performed electron-scattering experiments on Rb atoms in the range of 10-1000 eV. In the first experiment they measured total cross sections for scattering from the 5s state by lowering the capture velocity of the trap below the recoil velocity of the scattered atoms. In the second experiment they isolated the total ionization cross section by operating the trap such that virtually all elastically and inelastically scattered atoms were captured by the trap. These experimental results will test new theoretical methods for calculating total and ionization cross sections. Straightforward extensions ofmore » these methods should allow similar measurements using excited-state atoms (5p, 5d) as well. The techniques should also be readily adaptable to the important case of the metastable noble gases.« less
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.« less
The implementation of a technique to measure total collision cross sections using laser-cooled rubidium atoms along with the introduction of room-temperature background gases, confined in both magnetooptic and magnetic traps, is proposed. Atom loss from the trap and total collision cross section can be inferred from the knowledge of the density of background gases. The measured cross sections from the magneto-optic and magnetic traps are represented, compared, and found to be significantly different. The measurements using this technique have a very small error in the range of approximately 2%-7%.