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Standard Gas Pipette System

Five fully automated pipette systems with nominal 0.1 cc pipette volumes and 4 liter resevoirs deliver reference gasses used to calibrate the Noblesse for isotopic analyses and isotope dilution abundance measurements.  The four of the pipette systems most heavily used in 40Ar/39Ar and (U-Th)/He measurments are connected to the main trunk (e.g., getter section) of the extraction line.  These include: (1) a 40Ar-39Ar-38Ar-36Ar mixture calibrated against atmospheric argon in Faraday monocollection measurements (see current calibration data); (2) purified atmospheric argon; (3) a 1:1 mixture of 4He and 3He; and (4) a 3He spike with 0.5 parts per 1000 4He contamination.  A fifth automated pipette system contains purified neon gas with a 20Ne/22Ne ratio = 2.33.  This pipette is connected to the auxiliary manifold of the line that is also fitted with a Janus 9-325K nude metal cold trap for argon trapping during neon isotopic measurements.  Hardware vacuum logic valves protect the reservoirs from accidental venting.  Tanks are filled via the "gas inlet" which features 1000 Torr and 1 Torr full scale MKS capacitance manometers.  A stand-alone manifold connected to the gas inlet has gas splitting aparatus (leak valve and pipette), a separate 1 Torr FS manometer, and a 50 cc reference volume to facilitate delivery of calibrated gas aliquots to the reservoirs.