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USNO is procuring a system that can be used as a calcium or strontium source for atomic spectroscopy for an optical clock. A molecular beam epitaxy (MBE) effusion cell source works well for this purpo... USNO is procuring a system that can be used as a calcium or strontium source for atomic spectroscopy for an optical clock. A molecular beam epitaxy (MBE) effusion cell source works well for this purpose; however, the dual filament design alone does not provide the necessary temperature stability for achieving required levels of clock performance. Additional thermal control, provided by an integrated water cooling system, would provide additional temperate stability and, therefore, improve ultimate performance of our clock. The following specifications must be met: We require that the source be capable of heating granules of calcium or strontium to 900 deg C. The source must have two independent heating elements to enable a ‘hot lip’ configuration, where the aperture can be heated above the main reservoir. The source must have an integrated water cooling system around the main reservoir area. The source must be mounted on a 4.5” Conflat (CF) flange and must be able to be integrated into a vacuum system using a Conflat seal. The source must be made of materials/components that are compatible with ultra-high vacuum (UHV). The source must be able to hold a crucible for the granules of calcium with a volume of at least 150 cc. A removable nozzle insert for the crucible must provide an aperture of dimensions 2 mm diameter and 2 cm length. Dimensions close to these may be acceptable. The aperture must be coaxial with the center of the Conflat flange. The crucible and insert must be removable and must be made of 316 stainless steel. Changes to nozzle dimensions and/or crucible and insert material may be acceptable but will need to be approved. The system must include all power supplies, temperature controllers, and electronics to make the dual filament MBE source work without any user supplied components.