AGING IN WIRE CHAMBER FILLED WITH DIMETHYL ETHER

The different methods for the measurement of wire chamber aging were a nalyzed and a more correct procedure was proposed. A study of aging ef fects under intense radiation in drift chambers filled with dimethyl e ther (DME), argon/carbon dioxide and argon/isobutane was performed. Th e influence of the materials and gain on the aging rate with DME was i nvestigated. With a drift tube in clean conditions the relative gain d rop R of 1.7%/(C/cm) was measured. For the drift chamber of the KEDR d etector R is 45%/(C/cm). This corresponds to a 2% pulse height decreas e per year at a gain of 10(5) and flux of the charged particles of 1 k Hz/cm(2). We conclude that, providing careful choice of the wire chamb er and tubing materials, the DME filled drift chamber can be run witho ut considerable aging effects.