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Buoyancy Testing of PMT's

J. Messimore

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