Aging in wire chamber filled with dimethyl ether

The different methods for the measurement of wire chamber aging were analyzed and a more correct procedure was proposed. A study of aging effects under intense radiation in drift chambers filled with dimethyl ether (DME), argon/carbon dioxide and argon/isobutane was performed. The influence of the materials and gain on the aging rate with DME was investigated. With a drift tube in clean conditions the relative gain drop R of 1.7%/(C/cm) was measured. For the drift chamber of the KEDR detector R is 45%/(C/cm). This corresponds to a 2% pulse height decrease per year at a gain of 105 and flux of the charged particles of 1 kHz/cm2. We conclude that, providing careful choice of the wire chamber and tubing materials, the DME filled drift chamber can be run without considerable aging effects.