42 results about "Neutron pulse" patented technology

A method and associated apparatus for detecting concealed fissile, fissionable or special nuclear material in an article, such as a shipping container, is provided. The article is irradiated with a source of fast neutrons, and fast neutrons released by the fissile or fissionable material, if present, are detected between source neutron pulses. The method uses a neutron detector that can detect and discriminate fast neutrons in the presence of thermal neutrons and gamma radiation. The detector is able to process high count rates and is resistant to radiation damage, and is preferably a solid state neutron detector comprised of silicon carbide.

A multi-stage process utilizing one or more radiation sensors on a distributed network for the detection and identification of radiation, explosives, and special materials within a shipping container. The sensors are configured as nodes on the network. The system collects radiation data from one or more nodes and compares the collected data to one or more stored spectral images representing one or more isotopes to identify one or more isotopes present. The identified one or more isotopes present are corresponded to possible materials or goods that they represent. The possible materials or goods are compared with the manifest relating to the container to confirm the identity of materials or goods contained in the container or to detect and / or identify unauthorized materials or goods in the container. For shielded materials, explosives and other types of material detection, a neutron pulse device could be incorporated into the system.

Apparatus and methods for measuring radiation in a borehole environment using a YAlO3:Ce (YAP) scintillation crystal. Borehole instruments are disclosed which employ a gamma ray detector comprising a YAP scintillator coupled to a light sensing means such as a photomultiplier tube. One instrument embodiment combines a YAP scintillation detector and a source of pulsed neutrons. Borehole environs are irradiated with neutrons, and induced gamma radiation is measured using a YAP scintillation detector. Response of the detector is used to determine characteristics of the borehole environs. Mechanical and physical properties of YAP are utilized to obtain improved measurements. The relatively short light decay constant of YAP minimized pulse pile-up in the detector when measurements require that the detector be operated during a neutron pulse.

A scintillator system is provided to detect the presence of fissile material and radioactive material. One or more neutron detectors include scintillator material, and are optically coupled to one or more wavelength shifting fiber optic light guide media that extend from the scintillator material to guide light from the scintillator material to a photosensor. An electrical output of the photosensor is connected to an input of a pre-amp circuit designed to provide an optimum pulse shape for each of neutron pulses and gamma pulses in the detector signals. Scintillator material as neutron detector elements can be spatially distributed with interposed moderator material. Individual neutron detectors can be spatially distributed with interposed moderator material. Detectors and moderators can be arranged in a V-shape or a corrugated configuration.

A multi-stage process utilizing one or more radiation sensors on a distributed network for the detection and identification of radiation, explosives, and special materials within a shipping container. The sensors are configured as nodes on the network. The system supports extended time options at each node and the ability to combine data from multiple nodes for the data acquisition and analysis of shipping containers. The system collects radiation data from one or more nodes and compares the collected data to one or more stored spectral images representing one or more isotopes to identify one or more isotopes present. The identified one or more isotopes present are corresponded to possible materials or goods that they represent. The possible materials or goods are compared with the manifest relating to the container to confirm the identity of materials or goods contained in the container or to detect and / or identify unauthorized materials or goods in the container. The containers are monitored and tracked as they are moved between the nodes. A central monitoring station monitors the radiological sensors, the information from the nodes and the tracking of the shipping containers. For shielded materials, explosives and other types of material detection, a neutron pulse device could be incorporated into the spreader bar position, the secondary position or both.

The invention discloses a comprehensive on-line measuring method of prompt neutron attenuation constant. The method mainly comprises the following stages: 1) collecting neutron pulse to obtain the time distribution of neutron pulse generated by neutron source and detecting body excited by the neutron source; 2) partitioning the collected data pack according to a given length, calculating the correlation function and power spectrum density of each block of neutron signal; 3) adopting the correlated fitting method to treat the correlation function so as to calculate the prompt neutron attenuation constant, adopting the break frequency method to treat the power spectrum density so as to calculate the prompt neutron attenuation constant; and 4) performing a comprehensive treatment to the results of the two different methods to obtain the final measuring result. The method can be used to estimate the prompt neutron attenuation constant both in time domain and frequency domain and perform measurement at the same time, thus as the operating precision of measurement increases gradually, the aim of on-line measurement is finally realized.

The invention relates to the technical field of neutron source equipment, specifically to a neutron generator tube, and aims to overcome the problem that waveform of the pulse neutrons generated by bombardment of a target has delay of several or dozens of microseconds and cannot realize sharp cut-off in the prior art. According to a provided technical scheme, the neutron generator tube comprises an ion source, a shell, a gate, an accelerated pole and a target; in a vacuum cavity in the shell, the sheet-like gate is arranged between the ion source and the accelerated pole; the gate is preparedfrom a metal molybdenum material and net-shaped grids are arranged on the gate; the gate is equivalent to ''door'' for controlling an ion beam; in a started state, the ion beam is led from the ion source and is accelerated to bomb the target surface to generate neutrons; and in a closed state, the ion beam is not led from the ion source, and the neutron tube does not generate neutrons. The waveform delay of the neutron pulse generated by the neutron generator tube can be shortened to be within 5[mu]s, so that sharp cut-off can be realized.

The invention relates to a device for preparing a high-quality high-depth-diameter-ratio micro hole by using a light ray obtained through femtosecond laser time domain / space shaping, and belongs to the field of transparent material micro-machining. According to the technical scheme, pulse time domain shaping equipment is used for generating a femtosecond laser pulse sequence; the position of a to-be-machined sample is adjusted to enable the light rays to generate micro holes with the maximum depths in the sample; the neutron pulse time delay of the pulse sequence is optimized so as to improvethe micro hole quality; a half-wave plate and a polarizing plate are combined for use to adjust the energy of lasers focused by two lenses correspondingly so as to enable the diameters of the micro holes formed by the lasers after being focused by the two lenses in the to-be-machined sample to be equal; the two focusing lenses are adjusted to enable the two independent light rays to be collinear in space and to be overlapped in an end-to-end mode to form an extended uniform light ray; and the position of the sample is moved to enable the light ray which is overlapped in the end-to-end mode togenerate a micro hole with the maximum depth-diameter ratio on the sample. According to the device, the quality and the depth-diameter ratio of the machined micro hole can be remarkably improved, themicro hole diameter adjusting range is wide, the machining environment is free of special requirements, the machining efficiency is high, and the machining cost is low.

An apparatus for estimating porosities of a formation includes: a borehole conveyable pulsed neutron generator to emit a pulse of high energy neutrons; a short spaced neutron detector to provide a count rate as a function of time; a long spaced neutron detector to provide a count rate as a function of time; a timing gate to synchronize a timing of neutrons detected by the detectors with respect to the neutron pulse; and a processor. The processor is configured to determine epithermal count rates and thermal count rates for the detectors based on timing of detection of neutrons with respect to the neutron pulse and calculate a first ratio of short to long spaced detector epithermal count rates and a second ratio of short to long spaced detector thermal count rates. The processor estimates an epithermal porosity using the first ratio and a thermal porosity using the second ratio.

A method for detecting the presence of a chemical element in an object by emission of neutrons onto the object, characterized in that the emission of neutrons onto the object is constituted, firstly, by a continuous emission of neutrons originating from an associated particle neutron generator (G1) and, secondly, by an emission of neutron pulses which are superimposed on the continuous emission of neutrons, where the neutron pulses originate from a pulsed neutron generator (G2) which generates neutron pulses of pulse duration T2, where two successive neutron pulses are separated by a duration T4, and where the continuous and pulsed emissions of neutrons on to the object produce a gamma capture radiation and an inelastic gamma radiation.

The present invention relates to a neutron pulse timing mode for pulse neutron whole spectrum saturation logging tool, emitting rapid neutron continuously by broad pulse design, and adding the neutron emitting time corresponding, resolves technique problem that great fluctuation error of Sigma parameter in present neutron pulse timing mode cause Sigma detecting well data can't be used, enhances the gate counting rate of monitoring Sigma and reduces the fluctuation error of Sigma parameter, reaches the similar effect near to result by special Sigma measuring apparatus.

The invention provides an inelastic scattering gamma-ray spectrometry analysis method and device. The method comprises the steps as follows: inelastic mixed spectrum and capture spectrum are measuredin a neutron pulse cycle and subjected to normalization processing; the normalized capture spectrum is added to an element first inelastic standard spectrum matrix obtained in advance, and an elementsecond standard spectrum matrix corresponding to the capture spectrum is obtained; the inelastic mixed spectrum is analyzed through the element second standard spectrum matrix, and contribution ratesof elements and the normalized capture spectrum for the inelastic mixed spectrum are obtained; the contribution rates of all the elements for the inelastic mixed spectrum are normalized, and inelasticspectrum relative yields of all the elements are obtained. Pure inelastic spectrum is not required to be obtained firstly during measurement of inelastic spectrum relative yields of all the elements,so that the defect of inaccurate underground stratum oil saturation due to defects of a fixed pure spectrum coefficient method which is mainly adopted at present can be overcome.