Abstract: A borehole logging tool and cryostat therefor to maintain a semiconductor detector at cryogenic temperatures. The cryostat has an elongate single-phase heat sink of solid, thermally conductive material on which the detector is removably mounted. The other end of the heat sink is arranged to receive a liquid cryogen or the cold finger of a helium refrigerator, which is removed before a logging run; the detector being maintained at cryogenic temperatures during the logging run by absorption and retention of heat in the solid, single-phase heat sink.

Abstract: A borehole logging tool and cryostat therefor to maintain a semiconductor detector at cryogenic temperatures. The cryostat has an elongate single-phase heat sink of solid, thermally conductive material on which the detector is removably mounted. The other end of the heat sink is arranged to receive a liquid cryogen or the cold finger of a helium refrigerator, which is removed before a logging run; the detector being maintained at cryogenic temperatures during the logging run by absorption and retention of heat in the solid, single-phase heat sink. A rigid tube having similar thermal capacity and similarly pre-cooled to cryogenic temperatures, surrounds but is spaced from the heat sink. The tube and heat sink are supported by low thermal conductivity supports, the tube supports being arranged to permit changes in length of the tube.

Abstract: A borehole logging tool and cryostat therefor to maintain a semiconductor detector at cryogenic temperatures. The cryostat has an elongate single-phase heat sink of solid, thermally conductive material on which the detector is removably mounted. The other end of the heat sink is arranged to receive a liquid cryogen or the cold finger of a helium refrigerator, which is removed before a logging run; the detector being maintained at cryogenic temperatures during the logging run by absorption and retention of heat in the solid, single-phase heat sink. A rigid tube having similar thermal capacity and similarly pre-cooled to cryogenic temperatures, surrounds but is spaced from the heat sink.

Abstract: In the specific embodiments of the invention disclosed, a semiconductor radiation detector located in a logging tool sized for passage through a borehole is maintained at cryogenic temperatures by a cryostat housed in the tool. The cryostat includes a cryogen chamber containing a melting-solid type cryogen. Thermal insulation in the form of radiation heat shields and a vacuum chamber surround the cryogen chamber. The integrity of the vacuum insulation is maintained by an active vacuum pump. The pump may be mounted either externally of the cryostat, such that its operation is independent of temperature conditions within the cryostat, or internally thereof, so as to be cooled by the cryogen. Alternatively, a second cryostat may be provided to cool the pump.

Abstract: The present invention relates to ionizing radiation sensors, and, more particularly, to semiconductor spectrometers with thermoelectric cooling, and can most advantageously be used in mineral raw material exploration and evaluation under field conditions. The spectrometer comprises a vacuum chamber with an entrance window for passing the radiation therethrough. The vacuum chamber accommodates a thermoelectric cooler formed by a set of Peltier elements. A heat conducting plate is mounted on the cold side of the thermoelectric cooler, and its hot side is provided with a radiator. Mounted on the heat conducting plate are sets of Peltier elements, integral with the thermoelectric cooler and independent of one another. The Peltier elements of these sets are stacked so as to develop the minimum temperature conditions on one set carrying a semiconductor detector and to provide the maximum refrigeration capacity conditions on the other set provided with the field-effect transistor mounted thereon.

Abstract: An improved cryostat for the superconducting magnet of an NMR spectrometer comprises a nested structure of isothermal shells surrounding a thermally conductive central reservoir of substantially spherical shape containing liquid helium in which the superconducting solenoid remains operational when only partially immersed. A radiation shield surrounding the central reservoir is cooled by the boil-off of escaping helium vapor. The radiation shield is enclosed within an isothermal shell maintained at the temperature of liquid nitrogen by thermal contact with a liquid nitrogen reservoir disposed above the region of the central reservoir and shielded therefrom by a wall of the isothermal shell. An outer radiation shield surrounds the liquid nitrogen reservoir and associated isothermal shell and the outer radiation shield is maintained at a temperatures of the order of 235.degree. K. by vapor cooling from the boil-off of escaping nitrogen and helium.

Abstract: Fluid in a pipeline or container at a refinery or at any of various petroleum producing operations is bombarded with neutrons, and high energy gamma rays resulting from capture of thermal neutrons are detected. The spectra of the detected gamma rays are then analyzed to determine the concentration of the element chlorine, which gives an indication of the presence and concentration of salt water in the fluid. The concentration of sulfur and the percentage gas in the fluid may be determined simultaneously with the concentration of chlorine.

Abstract: A high-gain Josephson-type two-particle tunneling detector is positioned in a borehole penetrating an earth formation and tuned for response in a frequency range of 8400 to 9600 gigahertz. Result: IR emission due to "stretching" vibration of the C-H bonds of adjacently situated hydrocarbons can be detected in surprising fashion.

Abstract: Apparatus for correcting measurement errors due to cycle skipping in acoustic-wave transit time measurements.The measurement made during sequence N-1 is stored in an auxiliary memory and compared with the next measurement (sequence N). If the difference between the two successive measurements is smaller than a given fraction of the average period of the acoustic waves used, the measurement of sequence N is transmitted to a measurement memory and recorded. Otherwise, it is the last measurement considered good which is recorded. Moreover, in case of erroneous measurement, the transfer of the control signal for the gain applied to the reception signal is stopped and the gain remains at its former value.Significant improvement in the quality of acoustic well-logging recordings is achieved.

Abstract: A borehole logging tool includes a steady-state source of fast neutrons, two epithermal neutron detectors, and two thermal neutron detectors. A count rate meter is connected to each neutron detector. A first ratio detector provides an indication of the porosity of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two epithermal neutron detectors. A second ratio detector provides an indication of both porosity and macroscopic absorption cross section of the formation surrounding the borehole by determining the ratio of the outputs of the two count rate meters connected to the two thermal neutron detectors. By comparing the signals of the two ratio detectors, oil bearing zones and salt water bearing zones within the formation being logged can be distinguished and the amount of oil saturation can be determined.

Abstract: A system for logging earth formations traversed by a borehole wherein a high energy pulsed neutron source (14 MeV) repetitively irradiates earth formations. Two time gates operated after each neutron pulse are provided for detecting count rates from which the decay time and the macroscopic capture cross-section .SIGMA. can be determined. Background gate means are also provided to eliminate the effects of background and detector radiation. In the detection system, output pulses whose voltage level is proportional to the energy detected are produced. A cut-off voltage level is set at approximately 0.8 MeV, which is above the energy of gamma rays produced following neutron capture by the element Boron and below the energy of most gamma rays produced following capture by all other significant formation elements. By comparison of the count rates (obtained by summing these voltage pulses) in a Boron containing formation with macroscopic capture cross-section .SIGMA.

Abstract: An improved well logging system of the type utilizing a single conductor cable to provide power from the surface equipment to a down hole subsurface unit and for simultaneously supplying current mode telemetry signals from one or more radiation detectors in the subsurface unit to the surface equipment. The surface equipment includes a power supply for the subsurface unit comprising a constant current source having a high output impedance connected to a series pass voltage regulator having a low output impedance. A switching mode voltage regulator is employed within the subsurface unit to compensate for variations in the voltage supplied to the subsurface unit which result from variations in cable resistance and other factors.