Total cross sections for low-energy ion-atom collisions

Journal Article · Wed Sep 01 00:00:00 EDT 1976 · Sov. Phys. - Tech. Phys. (Engl. Transl.); (United States)

OSTI ID:7124416

Latypov, Z Z; Shaporenko, A A

An experimental apparatus is described for measuring the total absolute cross sections for the production of free electrons in collisions of ions with gas atoms at energies down to threshold. The apparatus makes use of the fact that a homogeneous rf field in the collision chamber causes essentially no changes in the trajectories of the ions of the primary beam but does deflect electrons formed in the collision region from the point at which they are formed. A secondary-electron multiplier operating in the counting mode is used to detect the electrons and, thus, to increase the sensitivity of the method. The calculated and experimental energy spectra of the electrons formed in the collision chamber reveal well-localized groups corresponding to the appearance of electrons from the surfaces and from the target gas. Accordingly, when a two-level retarding system is used to isolate the group of electrons corresponding to ionization of the gas it is possible to avoid the distortion of the function dependence of the ionization cross section on the collision energy which would result from the secondary-emission electrons from the surfaces. The errors of the method are discussed. The collision chamber and the electron detector are designed so that the electrons formed in the ionization of the gas atoms can be corrected efficiently (efficiency approx.48%) under the particular working conditions (field frequency f=50 MHz) and peak value V/sub 0/=200 V). With this experimental apparatus it is possible to measure the absolute values of the total ionization cross section and to study the behavior of these cross sections down to threshold.

• Research Organization: A. F. Ioffe Physicotechnical Institute, Academy of Sciences of the USSR, Leningrad
• OSTI ID: 7124416
• Journal Information: Sov. Phys. - Tech. Phys. (Engl. Transl.); (United States), Vol. 21:9
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ION-ATOM COLLISIONS
TOTAL CROSS SECTIONS
ENERGY SPECTRA
IONIZATION
IONIZATION CHAMBERS
THRESHOLD ENERGY
ATOM COLLISIONS
COLLISIONS
CROSS SECTIONS
ENERGY
ION COLLISIONS
MEASURING INSTRUMENTS
RADIATION DETECTORS
SPECTRA
640304* - Atomic
Molecular & Chemical Physics- Collision Phenomena