Polymer growth rate in a wire chamber with oxygen, water, or alcohol gas additives

The rate of polymer growth on wires was measured in a wire chamber while the chamber was aged initially with helium:isobutane (80:20) gas, and then with either oxygen, water, or alcohol added to the gas. At the completion of the aging process for each gas mixture, the carbon content on the wires was measured in a scanning electron microscope/energy dispersive X-ray (SEM/EDX) instrument. The same physical wires were used in all the gas mixtures, allowing measurement of polymer build-up or polymer depletion by each gas additive. It is found that the rate of polymer growth is not changed by the presence of oxygen, water, or alcohol. Conjecture that oxygen reduces breakdown by removing polymer deposits on field wires is negated by these measurements. Instead, it appears that the reduced breakdown is due to lower resistance in the polymer from oxygen ions being transported into the polymer. It is also observed that field wires bombarded by the electrons in the SEM and then placed back into the chamber show an abundance of single electrons being emitted, indicating that electron charge is trapped in the polymer layer and that a high electric field is necessary to remove the charge.