An apparatus has been developed which permits high pressure Mössbauer resonance studies to 300 kbar. It can be operated with either the source or the absorber under pressure. The pressures are established by x-ray diffraction measurements, and calibration curves are presented for both the supported taper and Bridgman anvils cells. A motion device involving magnets and phosphor bronze springs, with an adjustable mount, is described. Circuits necessary to control the motion, and to distribute the signals from two devices operating in parallel, are outlined.

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The discrepancy between the experimentally observed beam intensities obtained with nozzle sources, and the intensities predicted by the inviscid theory is generally attributed to viscous effects upstream of the ``skimmer.'' Experiments are described which show the scattering of a 1.2-eV nitrogen beam downstream of a ``skimmer'' or collimator. Such scattering can only result from collisions with slow molecules, traveling with the beam, coming from the viscous region upstream. Elimination of this scattering was accomplished by limiting the radial extent of the flow field approaching the ``skimmer,'' and beams were obtained having the theoretically available intensity.