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A number of spheres of different radii and masses have been dropped in liquid helium I and II, liquid air, ethyl acetate, and water. The terminal velocity of each sphere falling in the confined liquid was measured. When falling at constant velocity, the hydrodynamic drag force, D, is equal to the weight of the sphere, and the drag coefficient, CD, in the formula for the drag force, D = CD( 12rv2 )A could be evaluated as a function of Reynolds number, NR = rvah , and ball radius, a. In these formulas D is the drag force on a sphere of cross sectional area A, moving through a liquid of density r and viscosity h with a velocity v. The drag coefficient for spheres falling in an infinite liquid has been measured by many observers and found to be a function only of the Reynolds number, NR. Our experiments were done in a cylinder of radius, R; spheres have been used with radii such that 0.18 ≲ a/R ≲ 0.83. By comparing our results for the drag coefficient, CD, with the published values of the drag coefficient in an infinite liquid, C D a wall correction factor, K = CD/ CExpD , has been determined as a function of NR and aR . Due to the equality of the drag coefficients in helium I and helium II at high Reynolds numbers it has been shown that at high Reynolds numbers helium II behaves as an ordinary fluid of density r=rn+rs .

A study of the disintegration of nitrogen and oxygen when bombarded by neutrons has been made by means of a cloud chamber. By observing the particles produced in the disintegration of the oxygen and nitrogen nuclei, data have been taken on several phenomena; the energy levels of carbon-13, boron-11, nitrogen-15, nitrogen-16, and carbon-14 have been studied; the range---energy relations of boron-11 and carbon-13 have been established over certain portions of their ranges; the relative probabilities of disintegration of the compound nuclei by different modes have been observed. In certain cases the angular distributions of the emitted particles have also been studied.

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In this work with atomic Strontium, the atoms are first laser cooled and subsequently trapped, in a MOT operating on the strong E1 allowed transition at 461 nm. During the operation of this blue MOT, a fraction of the atoms decay into the 3P2 and 3P1 states, but can be recovered by applying light from repumper lasers at 679 nm, and 707 nm. Atoms trapped in the blue MOT are subsequently transferred into a magneto-optical trap operating on the intercombination line at 689 nm, known as the red MOT. Photoassociation experiments are carried out on these atoms using an independent tunable source of blue light at 461 nm. These experiments map out the underlying molecular potentials, and are useful in determining the atom-atom interaction strength. Additionally, atoms trapped in the red MOT can be transferred into an optical dipole trap (ODT) operating at 1064 nm, resulting in a cold dense sample suitable for collision studies, lifetime measurements, and evaporative cooling towards Bose-Einstein condensation.