Operation of the DIRC at the High Luminosity PEP-II Collider
These include (1) the stability of PMT windows immersed in
ultra-pure water; (2) backgrounds from soft photons that interact in the water tank; (3) maintainance of the pure water system; (4) the
long term stability of photon detection efficiencies; and (5) issues that might be expected to arise as the machine luminosity increases
to 10x design .