Effective ionization coefficients, electron drift velocities, and limiting breakdown fields for gas mixtures of possible interest to particle detectors

Conference · Tue Jan 01 00:00:00 EST 1991

DOI:https://doi.org/10.1109/CEIDP.1991.763859· OSTI ID:5402014

Datskos, P G ^[1]; Christophorou, L G; Carter, J G ^[2]

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1. Tennessee Univ., Knoxville, TN (United States). Dept. of Physics
2. Oak Ridge National Lab., TN (United States)

We have measured the gas-density, N, normalized effective ionization coefficient, {bar a}/N, and the electron drift velocity, w, as a function of the density-reduced electric field, E/N, and obtained the limiting, (E/N){sub lim}, value of E/N for the unitary gases Ar, CO{sub 2}, and CF{sub 4}, the binary gas mixtures CO{sub 2}:Ar (20: 80), CO{sub 2}:CH{sub 4} (20:80), and CF{sub 4}:Ar (20:80), and the ternary gas mixtures CO{sub 2}:CF{sub 4}:Ar (10:10:80) and H{sub 2}O: CF{sub 4}:Ar (2:18:80). Addition of the strongly electron thermalizing gas CO{sub 2} or H{sub 2}O to the binary mixture CF{sub 4}:Ar (1) cools'' the mixture (i.e., lowers the electron energies), (2) has only a small effect on the magnitude of w(E/N) in the E/N range employed in the particle detectors, and (3) increases {bar a}/N for E/N {ge} 50 {times} 10{sup {minus}17} V cm{sup 2}. The increase in {bar a}/N, even though the electron energies are lower in the ternary mixture, is due to the Penning ionization of CO{sub 2}(or H{sub 2}O) in collisions with excited Ar* atoms. The ternary mixtures -- being fast, cool, and efficient -- have potential for advanced gas-filled particle detectors such as those for the SCC muon chambers. 17 refs., 8 figs., 1 tab.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5402014
• Report Number(s): CONF-911087-1; ON: DE91015921
• Resource Relation: Conference: Electrical insulation and dielectric phenomena conference, Knoxville, TN (United States), 20-24 Oct 1991
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
74 ATOMIC AND MOLECULAR PHYSICS
GASES
BREAKDOWN
ELECTRON DRIFT
IONIZATION
ARGON
CARBON DIOXIDE
CARBON TETRAFLUORIDE
ELECTRIC FIELDS
SHOWER COUNTERS
SUPERCONDUCTING SUPER COLLIDER
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
ELEMENTS
FLUIDS
FLUORINATED ALIPHATIC HYDROCARBONS
HALOGENATED ALIPHATIC HYDROCARBONS
MEASURING INSTRUMENTS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RADIATION DETECTORS
RARE GASES
STORAGE RINGS
440104* - Radiation Instrumentation- High Energy Physics Instrumentation
640302 - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory