Chemistry of radiation damage to wire chambers

Thesis/Dissertation · Sat Aug 01 00:00:00 EDT 1992

DOI:https://doi.org/10.2172/10183880· OSTI ID:10183880

Wise, Jonathan ^[1]

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1. Univ. of California, Berkeley, CA (United States)

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 CF₄/iC₄H₁₀ 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 CF₄-rich gases. A four-part model considering plasma polymerization of the hydrocarbon, etching of wire deposits by CF₄, acceleration of deposition processes in strongly etching environments, and reactivity of the wire surface is developed to understand anode wire aging in CF₄/iC₄H₁₀ 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/C₂H₆. Apparent loss of gain is explained by attachment of primary electrons to a continuously increasing concentration of Freon 11 (CCl₃F) 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
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 10183880
• Report Number(s): LBL--32500; ON: DE93000627
• Country of Publication: United States
• Language: English

Related Subjects

2-METHYLPROPANE
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
440104
440200
AGING
ANODES
BINARY MIXTURES
CARBON TETRAFLUORIDE
DAMAGE
DEPOSITS
FREONS
GOLD
HIGH ENERGY PHYSICS INSTRUMENTATION
MULTIWIRE PROPORTIONAL CHAMBERS
RADIATION EFFECTS
RADIATION EFFECTS ON INSTRUMENT COMPONENTS
INSTRUMENTS
OR ELECTRONIC SYSTEMS
TUNGSTEN
WIRE SPARK CHAMBERS