Abstract: Systems and techniques are provided for optimizing the performance of a target for a downhole neutron generator. An example method can include disposing a first source material and a first substrate in a vacuum chamber at an initial temperature, evaporating the first source material to be deposited onto a surface of the first substrate, monitoring a temperature of the first substrate during the evaporation of the first source material, and determining a thermal equilibrium process temperature at which the temperature of the first substrate is stabilized. The example method can further include disposing a second source material and a second substrate in the vacuum chamber at the thermal equilibrium process temperature, evaporating the second source material to be deposited onto a surface of the second substrate, and obtaining the second substrate deposited with the second source material for a target of a downhole neutron generator.

Abstract: A system for determining fluid flow characteristics and relaying the information to the surface. The system is ideal for use in horizontal or deviated wellbores since orientation of the wellbore with respect to the vertical will not appreciably affect the system's operation. In the described embodiment, a fluid-driven siren flowmeter is placed within a production string downstream of the location of a completion zone, the flowmeter relays representative information downstream via a fluid column to a signal detection assembly. The flowmeter includes a stationary stator, a rotatable rotor and a turbine deflector which is positioned upstream of the rotor and angularly directs the flow of passing fluid to rotate the rotor. In the case of multiple completed zones described, multiple flowmeters are sequentially mounted along the same production string, each providing signals of different characteristics.