Abstract: The invention is a gamma ray detector that locates a source, both horizontally and vertically. The detector comprises a tubular shield surrounded by scintillator panels. Gammas incident from one side can fully strike the scintillator facing the source, but are blocked from reaching the scintillators on the opposite side of the shield. The scintillator counting rates thus indicate the lateral direction of the source. By iteratively rotating toward the highest-counting scintillator, the detector converges to the source. An additional, central detector can be mounted within the tubular shield. When analyzed with the outer scintillators, the central detector determines the overall angular separation between the source and the detector axis, thereby locating the source in two dimensions automatically. The invention enables rapid detection and precise localization of clandestine nuclear and radiological weapons, despite shielding and clutter obfuscation, while quickly passing clean loads.

Abstract: Nano-level evaluation of kerogen-rich reservoir rock is described. A nano-scale beam is formed from kerogen-rich reservoir rock. The nano-scale beam includes reservoir rock and kerogen having polymeric properties. A mechanical experiment is performed on the nano-scale beam. The mechanical experiment is imaged using a scanning electron microscope (SEM) or a transmission electron microscope (TEM). A material parameter of the kerogen in the nano-scale beam is determined based on the mechanical experiment and images obtained responsive to the imaging.

Abstract: Beam configuration data obtained during the commissioning and/or quality assurance (QA) testing of a radiation therapy device can be validated against other radiation therapy devices within the radiotherapy community. Data and parameters from previously commissioned or QA-tested devices can be compiled and analyzed at a remote module. At the remote module, data and parameters obtained from a radiation therapy device undergoing commissioning or QA testing can be compared to the previously compiled data and/or parameters, to factory data and/or parameters, and/or to predetermined device limits, in order to provide an indication to an end user of potential issues or errors. Warnings, feedback, and/or suggestions can be provided to the end user of the radiation therapy device based on the comparison.

Abstract: Methods and downhole tools involving neutron-absorbing gamma ray windows are provided. One such method involves emitting neutrons from a neutron source in a downhole tool in a well into a surrounding geological formation. This may produce formation gamma rays through interactions between the neutrons and elements of the geological formation. The formation gamma rays may be detected by a gamma ray detector when the gamma rays pass via a gamma ray window that includes a neutron-absorbing material disposed in a substrate material of the downhole tool. The gamma ray window may be both more transmissive of gamma rays than the substrate material and less transmissive of neutrons than a window without the neutron-absorbing material. This may decrease a neutron flux that would otherwise reach the gamma ray detector and the tool materials surrounding it and thus would otherwise lead to a background signal contaminating a signal corresponding to the detected formation gamma rays.

Abstract: The present invention relates to a logging tool for logging formational changes in a borehole, the logging tool having a longitudinal axis. The logging tool comprises a radiating source (5) for emitting an interaction signal, a detector (6) for detecting a reaction signal, and a screen (7) for limiting a volume (53) investigated by the radiating source and the detector, wherein the tool comprises a first part (8) and a second part (9), the second part being able to rotate around the longitudinal axis relative to the first part during use, and the second part comprising the screen (7), and wherein a speed of rotation of the second part is controlled by the rotation unit to be proportional to an output signal of the detector. Furthermore, the present invention relates to a method of characterizing a geological formation surrounding a borehole by a logging tool according to the present invention.

Abstract: The subject matter described herein provides methods for developing an IMRT treatment plan for a radiotherapy system. In one aspect, the method can include providing initial treatment parameters. These parameters can include a number of isotopic beams, a transmission angle for each beam, a prescribed dose for a target, and dose volume histogram constraints. The method can further include determining an initial fluence map including one or more beamlets. The initial fluence map can specify a fluence value for each beamlet. The method can further include determining a delivery sequence for the fluence values in the initial fluence map. The delivery sequence can include one or more apertures formed by the leaves of a collimator. These apertures can have a specified size constrained to substantially less than a maximum size associated with the collimator, when the isotopic beam is near a critical structure. Related apparatus and systems are also described.

Abstract: A method of evaluating a reservoir includes a multi-energy X-ray CT scan of a sample, obtaining bulk density and photoelectric effect index effect for the sample, estimation of at least mineral property using data obtained from at least one of a core gamma scan, a spectral gamma ray scan, an X-ray fluorescence (XRF) analysis, or an X-ray diffraction (XRD) analysis of the sample, and determination of at least one sample property by combining the bulk density, photoelectric effect index, and the at least one mineral property (e.g., total clay content). Reservoir properties, such as one or more of formation brittleness, porosity, organic material content, and permeability, can be determined by the method without need of detailed lab physical measurements or destruction of the sample. A system for evaluating a reservoir also is provided.

Abstract: A shield for a well logging instrument includes an outer layer including a reinforcing fiber disposed in a matrix and an inner layer including a thermal neutron absorbing material disposed in a matrix. The thermal neutron absorbing material is selected to emit capture gamma rays having energy outside a selected energy range.

Abstract: A muon monitoring system for particle radiation therapy includes: a shield for a selective passing, by eliminating particles and radiation produced due to the high energy particles and radiation pulses, of the delay positrons emitted due to decay of muons stopped at a position corresponding to the Bragg peak position; a positron detector for detecting positrons from a designated direction and detecting the delay positrons passed through the shield opening by each of positron detecting plates for providing information of positron produced positions and time of delay simultaneous signals; and a control/analysis apparatus generating a delay signal at a timing delayed by a predetermined time period from a completion of irradiation of the high energy particle radiation pulses, and performing a process to generate ?SR signals segmented for each positron generating position by analyzing detected results obtained by operating the positron detector for a predetermined number of times.

Abstract: An apparatus can measure characteristics of a formation surrounding a borehole. The apparatus includes a tool body having a neutron measurement section and a density measurement section. The neutron measurement section includes a neutron source and a neutron detector arrangement spaced in an axial direction from the neutron source. The density measurement section includes a gamma ray source and a gamma ray detector arrangement spaced in an axial direction from the gamma ray source. The neutron measurement section and the density measurement section are positioned in the tool body so that the sections overlap in the axial direction and are azimuthally spaced apart in the tool body. The tool body also includes shielding to block a direct signal path from the neutron source to the gamma ray detector arrangement and to block a direct signal path from the gamma ray source to the neutron detector arrangement.

Abstract: A well-logging device may include a housing to be positioned within a borehole of a subterranean formation, and at least one radiation source carried by the housing to direct radiation into the subterranean formation. The well-logging device may also include noble gas-based radiation detectors carried by the housing in azimuthally spaced relation to detect radiation from the subterranean formation. A controller may determine at least one property of the subterranean formation based upon the detected radiation from the noble gas-based radiation detectors.

Abstract: A well-logging device may include a housing to be positioned within a borehole of a subterranean formation and at least one radiation source carried by the housing to direct radiation into the subterranean formation. The well-logging device may also include noble gas-based radiation detectors carried by the housing to detect radiation from the subterranean formation. At least one of the noble detectors is at a first axial spacing from the at least one radiation source, and at least one other of the noble gas-based radiation detectors is at a second axial spacing from the at least one radiation source different from the first axial spacing. A controller may determine at least one property of the subterranean formation based upon the detected radiation from the noble gas-based radiation detectors.

Abstract: A neutron logging tool has multiple detectors spaced about the circumference of the tool. The detectors are shielded from each other such that each detector detects gamma rays from the area of the borehole and formation to which it is closest. The log readings from each detector can be associated with the orientation of that detector. The orientation-specific log readings can then be aggregated to form an azimuthal log which can be used to analyze pre-fractured and/or post-fractured formations.

Abstract: A downhole tool for performing measurement of a formation. The tool comprising a housing surrounding a source for generating neutrons and a detector for detecting the neutrons. A shield is located outside of, or embedded in, the housing and focuses the neutrons.

Abstract: The present invention relates to a scanning tool (1) for scanning an object downhole. The tool has a longitudinal axis and comprises an emitting device (2) for emitting radiation, a lens (3) for transmitting the radiation in a predetermined pattern (4) of radiation, and a receiving device (5). In a first position of the tool, the pattern of radiation is reflected on the object (6) to be scanned and the reflected radiation is received in the receiving device resulting in a first measurement.

Abstract: A device and a process for performing high temporal- and spatial-resolution MR imaging of the anatomy of a patient during intensity modulated radiation therapy (IMRT) to directly measure and control the highly conformal ionizing radiation dose delivered to the patient for the treatment of diseases caused by proliferative tissue disorders. This invention combines the technologies of open MRI, multileaf-collimator or compensating filter-based IMRT delivery, and cobalt teletherapy into a single co-registered and gantry mounted system.

Abstract: Hourly CO2 concentration, amount of solar radiation, and plant distribution information are calculated through observation from predetermined satellites. A concentration of CO2 absorbed by plant-chlorophyll per each time unit is calculated. By adding up the CO2 concentration on the earth and the concentration of CO2 absorbed by the plant-chlorophyll, a CO2 concentration obtained provided that no plant-chlorophyll exist is calculated for a certain period. Thereafter, a mean concentration of CO2 that is absorbed according to changes in the distribution of plant-chlorophyll is calculated on the basis of a monthly mean solar radiation amount and plant-chlorophyll distribution information. By subtracting the CO2 concentration, which is a mean, from the total CO2 concentration, a CO2 concentration, which is a normal, is calculated.

Abstract: A shield for a well logging instrument includes an outer layer including a reinforcing fiber disposed in a matrix and an inner layer including a thermal neutron absorbing material disposed in a matrix. The thermal neutron absorbing material is selected to emit capture gamma rays having energy outside a selected energy range.

Abstract: A downhole tool for performing measurement of a formation. The tool comprising a housing surrounding a source for generating neutrons and a detector for detecting the neutrons. A shield is located outside of, or embedded in, the housing and focuses the neutrons.

Abstract: A radiation detector that includes a charge conversion layer, a substrate, an electrode layer, an intermediary layer and wiring is provided. The substrate includes a lower electrode portion that collects charge generated by the charge conversion layer. The electrode layer includes an upper electrode portion and an extended electrode portion. The upper electrode portion is laminated on the charge conversion layer. The extended electrode portion extends from the upper electrode portion down a side face of the charge conversion layer to a region on the substrate at which the charge conversion layer is not present. The intermediary layer is formed from between the charge conversion layer and the upper electrode portion to between the extended electrode portion and the substrate. The wiring is electrically connected with the extended electrode portion at the region on the substrate at which the charge conversion layer is not present.

Abstract: A device and a process for performing high temporal- and spatial-resolution MR imaging of the anatomy of a patient during intensity modulated radiation therapy (IMRT) to directly measure and control the highly conformal ionizing radiation dose delivered to the patient for the treatment of diseases caused by proliferative tissue disorders. This invention combines the technologies of open MRI, multileaf-collimator or compensating filter-based IMRT delivery, and cobalt teletherapy into a single co-registered and gantry mounted system.

Abstract: An apparatus for measuring radiation in a borehole penetrating the Earth, the apparatus includes: a downhole tool having a structure defining a cavity; and one or more radiation detection components integrated into the cavity and configured to measure the radiation. An apparatus conveyable through a borehole for measuring radiation downhole and a method of producing a downhole apparatus for measuring radiation are provided.

Abstract: An apparatus for estimating a property of an earth formation penetrated by a borehole, the apparatus includes: a carrier configured to be conveyed through the borehole; a neutron source disposed at the carrier and configured to irradiate the earth formation with neutrons; a neutron detector disposed at the carrier and configured to detect neutrons reflected by the earth formation to the detector; a neutron reflector disposed partially around the detector, an area of the detector not covered by the reflector being configured to admit the reflected neutrons; and a neutron absorber disposed at least around the reflector.

Abstract: A method and apparatus for determining the density and phase fractions of well services fluids is shown including an x-ray generator, a sample cell, and a radiation detector. Radiation is passed through the sample cell and fluid and the attenuated radiation signal is used to evaluate the fluid. In one embodiment, a reference radiation detector measures a filtered radiation signal and controls the acceleration voltage and/or beam current of the x-ray generator using this information. The apparatus may be permanently affixed for long term monitoring or temporarily clamped on to a pipe in production.

Abstract: It is described a logging tool 20 for underground formations surrounding a borehole 14, comprising an elongated body 21 along a major axis; a collar 22 disposed peripherally around said body 21 having a collar wall defined by an inner and an outer surface; a radiation emitting source 201 arranged to illuminate the earth formation 16 surrounding the borehole; at least one radiation detector 211 arranged to detect radiation reflected by the earth formation resulting from illumination by the source 201; at least one source collimation—window 202 and one detector collimation window 212 through which the earth formation is illuminated and radiation is detected; and characterized in that it further comprises at least one radiation shield 30 located between said inner collar surface and the outer surface of the tool, said radiation shield positioned so as to eliminate parasitic radiation that has not traversed the outer collar.

Abstract: The invention relates to a method of and a device for forming an image which is composed of a plurality of sub-areas, a read-out unit being associated with each sub-area and image data of adjoining image areas of neighboring sub-areas being evaluated in order to mitigate differences in amplification, which device includes a detector with a plurality of sensor elements for forming image data, read-out units which are associated with the sub-areas of the image, an analysis unit which is arranged to evaluate image data from adjoining image areas of neighboring sub-areas and to generate correction data, a correction unit which is arranged to correct incorrect image data by means of correction data, thus enabling a regular and accurate recalibration or correction of non-linear amplifier behavior to be performed without necessitating an additional X-ray dose or interventions by the user.

Abstract: The invention relates to a method of and a device for forming an image which is composed of a plurality of sub-areas, a read-out unit being associated with each sub-area and image data of adjoining image areas of neighboring sub-areas being evaluated in order to mitigate differences in amplification, which device includes a detector with a plurality of sensor elements for forming image data, read-out units which are associated with the sub-areas of the image, an analysis unit which is arranged to evaluate image data from adjoining image areas of neighboring sub-areas and to generate correction data, a correction unit which is arranged to correct incorrect image data by means of correction data, thus enabling a regular and accurate recalibration or correction of non-linear amplifier behavior to be performed without necessitating an additional X-ray dose or interventions by the user.

Abstract: We disclose density measurement methods that are accurate over an extended range of standoff distances. One method embodiment includes: a) obtaining a standoff distance, a near detector count rate, and a far detector count rate; b) determining a formation density measurement using near and far detector count rates when the standoff distance is less than a predetermined value; and c) determining the formation density measurement using just the far detector count rate and the standoff distance measurement when the standoff distance is greater than the predetermined value. The method may further include calculating a calibration parameter when the standoff distance is less than the predetermined value. The calibration parameter serves to calibrate a standoff-based correction to the far detector count rate, enabling accurate formation density measurements at large standoff distances. The measurements are made with a rotating logging tool, causing the standoff distance to cycle between large and small values.

Abstract: An electromagnetic detector includes an insulating substrate, whereon a charge storage capacitor, a charge collection electrode connected to the charge storage capacitor, and a semiconductor film having electromagnetic conductivity are laminated in this order. The charge collection electrode has an uneven section composed of at least a concave or convex part, dedicated for use in reinforcing a bonding strength between the semiconductor film and the charge collection electrode. With this structure, a peeling of the semiconductor film can be prevented.

Abstract: The invention relates to a DFB fiber laser sensor (1). A measurement quantity makes it possible to induce a linear birefringence between mode pairs of the laser-amplifying fiber (2) and to measure an associated beat frequency (&Dgr;&ngr;1, &Dgr;&ngr;2, &Dgr;&ngr;3). According to the invention, the laser-amplifying fiber (2) has a nonrotationally symmetrical structure, so that it is possible to detect isotropic pressures p, acoustic waves or chemical substances that can be added radially to the laser-amplifying fiber (2). In a second aspect of the invention, an emission wavelength range and parameters (a, b, &Dgr;N) of the laser-amplifying fiber (2) and also a grating period L of the fiber Bragg grating resonator (3) are coordinated with one another such that at least two different spatial modes (LP01, LP11even, LP11odd, LP21even) are propagatable and it is possible to measure beat frequencies (&Dgr;&ngr;1, &Dgr;&ngr;2, &Dgr;&ngr;3) between oscillatory longitudinal laser modes assigned to them.

Abstract: An angular time-synchronized directional radiation sensor is provided to indicate the direction, or distribution of directions, of incident gamma radiation, and consequently, to locate sources of radioactivity emitting these photons. The angular time-synchronized directional radiation sensor comprises a rotating radiation sensing means, interacting with the incident radiation to produce light flashes, together with a stationary photomultiplier tube that converts the light flashes to electrical pulses that are counted by a data collection means. A synchronous motor enables the radiation sensing means to complete a 360.degree. scan within 1 second to reduce the time needed for measuring from hours to only a few minutes. The data collection means calculates an angle of rotation at a corresponding fraction of the 360.degree. scan to rapidly indicate the direction of a radiation source. In one embodiment, the data collection means is a computer. The radiation sensing means can be a scintillator assembly.

Abstract: A method/apparatus for determining the density of a formation traversed by a borehole having irregularities along the borehole wall preferably employs/includes a housing, a photon source, and a detector. The source preferably includes an irradiation path extending from the source to a side of the housing. Similarly, the detector preferably includes a detection path extending from the detector to the side of the housing. A stylus may be mounted onto the housing for penetrating through a layer of mudcake. Such stylus preferably includes a base and a substantially small contact head having a window fixedly attached thereto. A second irradiation path may extend from the base to the contact head. A second detection path may also extend from the base to the contact head. The irradiation and detection paths in the stylus are preferably substantially aligned with respective irradiation and detection paths in the housing.

Abstract: The method comprises using a transmitting unit and at least two receiving units (8,10) arranged in two different places along well equipment (2). Each receiving unit forms an image or signature of wall portions which pass it. The signatures of wall portions formed by the lower receiving unit (8) when the well equipment is being lowered into the well are stored and the upper receiving unit (10) stores signatures coming from the wall portions which were previously stored by the lower receiving unit. A comparison (for example a correlation) of the signatures respectively coming from the two receiving units allows a common wall portion which has produced two substantially identical compared signatures to be identified. The time interval between the formation of the two substantially identical signatures is measured and the rate of penetration is calculated. As application of the invention is for the measurement of the true rate of penetration of a well tool or of a measuring sonde.

Abstract: Apparatus for measuring the volume of gas present in a multiphase flow regime in a cased oil or gas well borehole and the amount, if any, of stratification thereof at a particular borehole depth. The apparatus includes a low energy gamma ray source and a sodium iodide detector located a very short distance from the source and separated by shielding material. Low energy gamma rays, unable to leave the well casing and return, are emitted from the source and scattered back from the multiphase production fluid to a detector comprising a sodium iodide crystal and photomultiplier tube. Both the source and detector are surrounded by rotatable slit collimators to provide sensitivity to azimuthal variations in gas volume percentage in the flow.

Abstract: A radioactive energy detector for well logging utilizes a Dewar flask. The Dewar flask has an inner housing containing a gamma ray detector. An outer housing surrounds the inner housing, with the annular clearance being evacuated. A window section is integrally formed in the side wall of the outer housing. The window section has a wall thickness that is less than the wall thickness of the side wall of the outer housing. The outer housing is constructed of a material of relatively low atomic number.

Abstract: A nuclear spectroscopic method and apparatus for determining hydrocarbon saturation or water saturation of a formation adjacent a well bore is disclosed. Near and far inelastic gamma ray spectra are detected in response to pulses of fast neutrons irradiating the formation and materials in the borehole. Near and far carbon/oxygen (C/O) ratios are extracted from each spectra using predetermined spectra of postulated elements. The near and far C/O ratios are combined to determine a representation of formation hydrocarbon saturation substantially corrected for borehole gamma rays produced by inelastic reaction of fast neutrons and hydrocarbons in the well bore. Shielding of near and far detectors is provided to make the near detector more sensitive to gamma rays emanating from borehole gamma rays and to make the far detector less sensitive to borehole gamma rays and more sensitive to formation gamma rays.

Abstract: This disclosure is directed to a scintillation crystal surrounded by a sleeve and having a window formed therein. The scintillation crystal has end located first and second photomultiplier tubes which provide output signals. A scintillation event observed in the crystal is seen by both photomultiplier tubes and both form output signals. The output signals have a relationship determining the point of impingement along the length of crystal of the photon gamma radiation; in turn, that photon is located relative to a surrounding shield having a helical window formed therein so that the relative angle of impingement can be determined. The relative angle is then converted into the absolute angle relative to the well borehole by referencing a north seeking gyroscope supported by the sonde. The output signals are also used to determine the energy of the impinging gamma radiation using well known pulse height analysis spectroscopy techniques.

Abstract: The porosity of an earth formation is derived in a plused neutron logging tool by use of a directionalized and borehole-shielded eptithermal neutron detector array and by processing detector count rate measurements of the epithermal neutron die-away curve in accordance with a multi-parameter fit to obtain as one parameter the epithermal neutron decay time of the formation and as a second parameter an indication of detector standoff (environmental) effects. The multi-parameter fitting procedure separates the formation and standoff effects on the measured count vs time curve, and yields a decay time measurement that is primarily representative of formation porosity and substantially free of environmental effects. To enhance count rate statistics, the neutron source and one or more of the epithermal neutron detector may be located at the same depth in the borehole. The neutron burst centroid is monitored an used to define a fiducial window for processing the die-way curve data.

Abstract: The present invention is a density meter which includes a well logging sonde that is inserted into a borehole traversing an earthen formation. The sonde includes within it a source which emits gamma rays into the borehole fluid and a detector assembly which detects gamma rays from the borehole fluid and provides a count signal corresponding to a count of the detected gamma rays. A caliper is also located in the sonde and it continually measures the diameter of the borehole as the sonde moves through the borehole and provides a caliper signal corresponding to the diameter measurement. A cable connected to the detector assembly and to the caliper conveys the count signal and a caliper signal to the surface where surface electronics includes apparatus which processes the count signal and the caliper signal to provide a signal corresponding to the density of the fluid in the borehole.

Abstract: A nuclear spectroscopic method and apparatus for determining hydrocarbon saturation or water saturation of a formation adjacent a well bore is disclosed. Near and far inelastic gamma ray spectra are detected in response to pulses of fast neutrons irradiating the formation and materials in the borehole. Near and far carbon/oxygen (C/O) ratios are extracted from each spectra using predetermined spectra of postulated elements. The near and far C/O ratios are combined to determine a representation of formation hydrocarbon saturation substantially corrected for borehole gamma rays produced by inelastic reaction of fast neutrons and hydrocarbons in the well bore. Shielding of near and far detectors is provided to make the near detector more sensitive to gamma rays emanating from borehole gamma rays and to make the far detector less sensitive to borehole gamma rays and more sensitive to formation gamma rays.

Abstract: A method for monitoring a hidden coal-rock interface, comprising the steps of irradiating the medium (M) being monitored from a gamma-ray source (1) and registering by a detector (2) the intensity of backward scattered radiation at a distance (A) from the surface of the medium (M) and at a distance (B) from the radiation source (B). Two zones (Z.sub.1 and Z.sub.2) are formed at the detector (2) for reception of backward scattered radiation, differently spaced from the source (1), so that the intensity of backward scattered radiation received by the zone (Z.sub.1) closer to the source (1) diminished with the distance (A) from the detector (2) to the medium (M), and grows when received by the zone (Z.sub.2) far from the source (1). The intensities of backward scattered radiation of both zones (Z.sub.1 and Z.sub.2) are summed up to obtain total intensity invariant with respect to variations of the distance (A) between the detector (2) and the medium (M).

Abstract: A solid state track recording type dosimeter is disclosed to measure the time dependence of the absolute fission rates of nuclides or neutron fluence over a period of time. In a primary species an inner recording drum is rotatably contained within an exterior housing drum that defines a series of collimating slit apertures overlying windows defined in the stationary drum through which radiation can enter. Film type solid state track recorders are positioned circumferentially about the surface of the internal recording drum to record such radiation or its secondary products during relative rotation of the two elements. In another species both the recording element and the aperture element assume the configuration of adjacent disks. Based on slit size of apertures and relative rotational velocity of the inner drum, radiation parameters within a test area may be measured as a function of time and spectra deduced therefrom.

Abstract: In the illustrative embodiments of the invention disclosed, a neutron porosity well logging tool includes a D-T neutron accelerator, a fast-neutron monitor for monitoring accelerator output, near and far epithermal neutron detectors for deriving a primary porosity measurement, a neutron detector array intermediate to the near and far epithermal detectors for providing enhanced spatial resolution, and a far-spaced thermal neutron detector. The epithermal neutron detectors are shielded and spaced relative to the accelerator to optimize tool response to formation porosity, whereby the tool affords accurate porosity sensitivity over the entire range of porosities of interest. The source monitor may additionally be employed to measure capture gamma ray intensity vs. time between neutron bursts for deriving formation sigma. Also, the detector array may include both epithermal and thermal neutron detectors to afford an epithermal/thermal comparison measurement.

Abstract: A well logging sonde is disclosed which includes a collimating window design for the accurate detection of gamma rays of low and high energy which are back-scattered from a region near a source of gamma rays emitted into the formation. The sonde includes a tungsten support inner tube or shell surrounded by a length of "U" shaped steel. A conduit is formed in the wall of the shell at an angle with respect to its axis and is oriented symmetrically toward the opening of the "U" shaped steel support member. A closing member of a thin layer of titanium is welded to the open ends of the "U" shaped steel member. An arcuate tungsten pad is secured about the titanium closing member and partially about the exterior of the open ends of the "U" shaped steel support member. A conduit in the pad is aligned with the conduit of the inner shell to form a collimating window. A gamma ray detector of a length shorter than the "U" shaped steel section is mounted within the inner tube in the path of the collimating window.

Abstract: For use in a sonde adapted to be lowered in a well bore, the present apparatus sets forth an improved nuclear event detector. The detector is sized and shaped monotonically increasing in cross section or diameter with increasing distance from the radiation source to thereby bias the detector; this bias counteracts the bias arising from geometry altering the pattern in which nuclear events impinge on the detector, thereby altering the distribution of such events.

Abstract: Apparatus for insulating enclosed electronic devices against damaging temperatures when used in deep, hot well bores. Includes a first vacuum chamber insulating means defined by outer casing of well-logging tool and inner casing. First vacuum chamber defines a components chamber to shield contents against the temperature in a well bore. A second vacuum chamber mounted within components chamber is defined by an outer tube and an inner tube. Outer tube has a thickened wall and is of material suited to serve as heat sink within components chamber. Second vacuum chamber defines detection chamber to shield contents against the temperature within components chamber. Thickened wall is undercut to define a thin wall adapted to function as a window for radiation to pass from an earth formation outside said logging tool into a radiation detector disposed within said detection chamber.

Abstract: A borehole logging tool includes a pulsed source of fast neutrons and a neutron sensitive counter. A neutron filter encases the counter and has a thickness to permit the longest possible delay time following each burst of fast neutrons before epithermal neutrons from the irradiated formation are detected by the neutron counter while at the same time minimizing thermal neutron effects.

Abstract: A cylindrical probe for insertion into a drill hole for detecting the presence of mineral deposits. A source of radioactive irradiation and a detector are mounted concentrically within the housing of the probe, the detector being shielded from direct radiation by a wall having an upper conical surface which directs fluorescent radiation reflected from the wall of the drill hole to the detector. A disc-shaped slot concentrates the rays from the radioactive source on an area of the drill hole wall which is in the shape of a ring surrounding the probe. The concentration and close proximity of the radiation source and the detector permit precise scanning and analyzing, simply, cheaply and quickly.

Abstract: A radioactive borehole logging tool employs an epithermal neutron detector having a neutron counter surrounded by an inner thermal neutron filter and an outer thermal neutron filter. Located between the inner and outer thermal neutron filters is a neutron moderating material for extending the lifetime of epithermal neutrons to enhance the counting rate of such epithermal neutrons by the neutron counter.

Abstract: A device for providing both thermal protection and radiation shielding for components within a well logging instrument. A thermally insulative flash contains a mass of eutectic material which undergoes a change of state at a temperature which will provide an acceptable thermal environment for such components for extended time periods. The eutectic material has a density facilitating its use as a radiation shield and is distributed around the component so as to selectively impede the impinging of the component by radiation.