Accession Number : AD0874155

Title :   Electron Ionization Cross Sections.

Descriptive Note : Annual progress rept. 1 Aug 68-1 Aug 69,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE PARTICLE OPTICS LAB

Personal Author(s) : Wang, K. L. ; Crawford, C. K.

Report Date : FEB 1970

Pagination or Media Count : 88

Abstract : A new carbon beam source which can be operated at high temperature was designed and built for the study of ionization cross sections of atomic carbon. The power required to operate at 2400K, about 165 watts, is close to the expected value; the power increases as T to the 5th power. Problems were experienced with the ion trap, which itself emitted ions from hot internal surfaces. A redesigned trap reduced the stray electron current to a comparable value. The detection efficiency and count loss in the electron multiplier was calculated by use of generating functions and compared with experimental results. Fragmentation has been studied using time-of-flight techniques in the frequency domain. The experiments show that fragmentation is responsible for less than 10% of total ion current. The relative ionization cross sections for C1, C2, and C3 have been measured using a chopped beam method. Absolute values were then calculated. (Author)

Descriptors :   *IONIZATION), (*CARBON, (*MASS SPECTROSCOPY, CARBON), ION BEAMS, MOLECULAR BEAMS, DIFFERENTIAL CROSS SECTIONS, ATOMS, ELECTRON IRRADIATION, SPECTRUM ANALYZERS, WIRING DIAGRAMS.

Subject Categories : Test Facilities, Equipment and Methods
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE