A radiation logging tool is provided that includes a scintillator detector for use on a wellbore tool string to characterize earth formations. The scintillator detector has a shutter to allow for the collection of data differentiating between incident radiation, such as backscatter signal, and system noise, such as dark current, vibration noise, electronics thermal noise, and electrostatic noise. The radiation logging tool provides for a method of calibrating and measuring incident radiation by the removal of system noise. The shutter is positioned between the photosensor and scintillation member of the scintillator detector, and is able to switch between open and closed states while the scintillation detector is deployed. Measurements of signal noise can be used to calibrate the sampling signal of incident radiation on the scintillator detector.

A radiation logging tool is provided that includes a scintillator detector for use on a wellbore tool string to characterize earth formations. The scintillator detector has a shutter to allow for the collection of data differentiating between incident radiation, such as backscatter signal, and system noise, such as dark current, vibration noise, electronics thermal noise, and electrostatic noise. The radiation logging tool provides for a method of calibrating and measuring incident radiation by the removal of system noise. The shutter is positioned between the photosensor and scintillation member of the scintillator detector, and is able to switch between open and closed states while the scintillation detector is deployed. Measurements of signal noise can be used to calibrate the sampling signal of incident radiation on the scintillator detector.

An apparatus and method for protecting sensitive electronics in a gamma radiation detector tool configured to be disposed in a borehole. The apparatus comprises a scintillator crystal and a photomultiplier tube disposed in either a single or individual housings. The housing(s) are bordered by springs configured to dampen axial vibrations. The housing(s) may be dampened from lateral vibrations by a lateral shock reducer on a sleeve that circumscribes the housing(s). The method comprises dampening axial and lateral vibrations to the crystal/photomultiplier during a drilling operation.

A single crystal yttrium aluminum perovskite scintillator has a minimum thickness of at least 5 mm and a transmittance of at least 50% at a wavelength of 370 nm. A method for fabricating the yttrium aluminum perovskite scintillator includes acquiring a yttrium aluminum perovskite single crystal boule, annealing the yttrium aluminum perovskite single crystal boule in an oxygen containing environment to obtain a partially annealed crystal, and annealing the partially annealed crystal in an inert environment or a reducing environment to obtain the yttrium aluminum perovskite single crystal scintillator.

A single crystal yttrium aluminum perovskite scintillator has a minimum thickness of at least 5 mm and a transmittance of at least 50% at a wavelength of 370 nm. A method for fabricating the yttrium aluminum perovskite scintillator includes acquiring a yttrium aluminum perovskite single crystal boule, annealing the yttrium aluminum perovskite single crystal boule in an oxygen containing environment to obtain a partially annealed crystal, and annealing the partially annealed crystal in an inert environment or a reducing environment to obtain the yttrium aluminum perovskite single crystal scintillator.

A device to measure the activity of a radioactive liquid, including a detection module, which extends around a measurement chamber that is intended to contain the liquid, and which is configured to detect ionizing radiation and to generate a detection signal; and a processing unit, which is connected to the detection module, and programmed to estimate an activity of the radioactive liquid based on the detection signal. The detection module comprises a solid-state scintillator detector, extending around the measurement chamber; and at least two photodetectors that are optically coupled to the scintillator detector. The device comprises a capillary tube, extending around a longitudinal axis, the capillary tube being arranged to be placed in a measurement position, and the capillary tube forming the measurement chamber.

The use of scintillator compositions having a cubic garnet structure for gamma detection in downhole oil and gas explorations is provided. Specifically, two primary compositions of interest are disclosed, Ca.sub.2LnHf.sub.2Al.sub.3O.sub.12 and NaLn.sub.2Hf.sub.2Al.sub.3O.sub.12, where Ln is Y, Gd, Tb, or La. Under gamma ray excitation, the electron-hole pairs produced in the garnet lattice structure are trapped by an activator ion to yield an efficient emission in the visible portion of the electromagnetic spectrum. The cubic garnet structure enables the use of these materials as ceramic scintillators with considerable advantages over related single crystals in various ways as disclosed herein, including reduction in cost and improvement in overall performance and durability.

A device to measure the activity of a radioactive liquid, including a detection module, which extends around a measurement chamber that is intended to contain the liquid, and which is configured to detect ionizing radiation and to generate a detection signal; and a processing unit, which is connected to the detection module, and programmed to estimate an activity of the radioactive liquid based on the detection signal. The detection module comprises a solid-state scintillator detector, extending around the measurement chamber; and at least two photodetectors that are optically coupled to the scintillator detector. The device comprises a capillary tube, extending around a longitudinal axis, the capillary tube being arranged to be placed in a measurement position, and the capillary tube forming the measurement chamber.