Three experiments are described about the measurement of pressures over the range from 10^-7 to 10^-11 Torr or lower. That is, (1) the pressure measurements by the Bayard-Alpert gauge, (2) the dependence of the discharge current in the getter ion pump on pressure, and (3) the decreasing characteristics, of the emission current with pressure and time in the field emission diode.
In the range of 10^-11 Torr, the pressure error measurement by B-A gauge is considerably laige due to the X-ray effect and the instability. The discharge current is proportional to the power from one to three halves of pressure. Also, the decreasing time of the emission current is inversely proportional, to the pressure, approximately. From results of the experiment (2) and (3), the pressure of 10^-11 Torr or lower is presumed to be obtained.

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Thin D-Zr target for pulsed neutron generator of D-D reaction has been prepared by impregnation of deuterium gas in vacuum-deposited Zr film on Cu base. Cu bases used are made of OFHC, electrolytic Cu and electrolytic Cu pre-coated with thin Pt film by vacuum deposition. As similar sorption abilities for deuterium gas to Zr films deposited on these three kinds of bases, above materials seem to be suitable for the target base. The atomic ratio of deuterium to zirconium in the target has been determined as 11.5 (D/Zr).
Temperature of Cu base placed on the holder is kept under 100°C by water cooling for elimination of reactions between residual gases in the evaporator and Zr atoms deposited on the base during the deposition process.
Precautions should be payed for purity of deuterium gas introduced in the apparatus for impregnation. If active gases (H₂O, O₂ and N₂ etc.) are included in deuterium gas, Zr film reacts with these gases and amount of absorption of deuterium gas is markedly reduced.
Apparatus and methods used for preparation of target are illustrated. Discussions are also carried out on total amount and components of gases impregnated in target.

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