Buoyancy Testing of PMT's
Since the PMT's will be underwater for the KamLAND experiment, it was necessary to
calculate the torque and buoyant force of the tube, shield and mount. To measure
the buoyant force, weights of known mass and material were used to force the
system underwater. Various weights were removed until the entire setup just
started to float. By simply subtracting the mass and the buoyant force of the
weights, it was calculated that the buoyant force of the tube, mount, and
shielding was 60 kilograms of force.
For the torque test, the tube was forced underwater such that the tube faced the
side of the water tank. However, it was allowed to rotate about the bottom
mounting bracket. Using a spring scale, approximately 16 foot-lbs of torque were
needed to keep the tube from twisting.
Last updated: August 27, 1999