Study of aging in BaBar RPCs

The BaBar detector, at the PEPII B factory of the Stanford Linear Accelerator Center (SLAC), operated over 700 Resistive Plate Chambers (RPCs) from 1999 to 2008. The original production RPCs showed serious aging problems within one year, necessitating replacement of the forward endcap and barrel RPCs. The more than 200 2nd generation Resistive Plate Chambers (RPCs) installed in the forward endcap in 2002 performed much better, but required several improvements to maintain good efficiency over the remaining life of the experiment. Our present understanding of the behavior and aging of the BaBar RPCs are summarized, as well as, the actions necessary to maintain good efficiency.