  The possibility of neutron and neutrino detection using water Cerenkov
detectors doped with gadolinium holds the promise of constructing very large
high-efficiency detectors with wide-ranging application in basic science and
national security. This study addressed a major concern regarding the
feasibility of such detectors: the transparency of the doped water to the
ultraviolet Cerenkov light. We report on experiments conducted using a 19-meter
water transparency measuring instrument and associated materials test tank.
Sensitive measurements of the transparency of water doped with 0.2% GdCl3 at
337nm, 400nm and 420nm were made using this instrument. These measurements
indicate that GdCl3 is not an appropriate dopant in stainless steel constructed
water Cerenkov detectors.
