Chemistry of radiation damage to wire chambers

Technical Report · Sat Aug 01 00:00:00 EDT 1992

DOI:https://doi.org/10.2172/7035484· OSTI ID:7035484

Wise, J

Proportional counters are used to study aspects of radiation damage to wire chambers (wire aging). Principles of low-pressure, rf plasma chemistry are used to predict the plasma chemistry in electron avalanches (1 atm, dc). (1) Aging is studied in CF{sub 4}/iC{sub 4}H{sub 10} gas mixtures. Wire deposits are analyzed by Auger electron spectroscopy. An apparent cathode aging process resulting in loss of gain rather than in a self-sustained current is observed in CF{sub 4}-rich gases. A four-part model considering plasma polymerization of the hydrocarbon, etching of wire deposits by CF{sub 4}, acceleration of deposition processes in strongly etching environments, and reactivity of the wire surface is developed to understand anode wire aging in CF{sub 4}/iC{sub 4}H{sub 10} gases. Practical guidelines suggested by the model are discussed. (2) Data are presented to suggest that trace amounts of Freons do not affect aging rates in either dimethyl ether or Ar/C{sub 2}H{sub 6}. Apparent loss of gain is explained by attachment of primary electrons to a continuously increasing concentration of Freon 11 (CCl{sub 3}F) in the counter gas. An increase in the concentration of Freon 11 in dimethyl ether is caused by a distillation process in the gas supply bottle and is a natural consequence of the unequal volatilities of the two compounds.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7035484
• Report Number(s): LBL-32500; ON: DE93000627
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
MULTIWIRE PROPORTIONAL CHAMBERS
AGING
RADIATION EFFECTS
WIRE SPARK CHAMBERS
2-METHYLPROPANE
ANODES
BINARY MIXTURES
CARBON TETRAFLUORIDE
DAMAGE
DEPOSITS
FREONS
GOLD
TUNGSTEN
ALKANES
DISPERSIONS
ELECTRODES
ELEMENTS
FILMLESS SPARK CHAMBERS
FLUORINATED ALIPHATIC HYDROCARBONS
GAS TRACK DETECTORS
HALOGENATED ALIPHATIC HYDROCARBONS
HYDROCARBONS
MEASURING INSTRUMENTS
METALS
MIXTURES
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
PROPORTIONAL COUNTERS
RADIATION DETECTORS
SPARK CHAMBERS
TRANSITION ELEMENTS
440200* - Radiation Effects on Instrument Components
Instruments
or Electronic Systems
440104 - Radiation Instrumentation- High Energy Physics Instrumentation