125 results about "Gamma ray detection" patented technology

The present invention provides a gamma-neutron detector based on mixtures of thermal neutron absorbers that produce heavy-particle emission following thermal capture. The detector consists of one or more thin screens embedded in transparent hydrogenous light guides, which also serve as a neutron moderator. The emitted particles interact with the scintillator screen and produce a high light output, which is collected by the light guides into a photomultiplier tube and produces a signal from which the neutrons are counted. Simultaneous gamma-ray detection is provided by replacing the light guide material with a plastic scintillator. The plastic scintillator serves as the gamma-ray detector, moderator and light guide. The neutrons and gamma-ray events are separated employing Pulse-Shape Discrimination (PSD). The detector can be used in several scanning configurations including portal, drive-through, drive-by, handheld and backpack, etc.

A method of measuring characteristics of a geologic formation, using the time, energy and spatial spectra of gamma rays induced by an accelerator, which allows (i) the measurement of the photoelectric absorption (Pe) factor of the formation using a gamma-ray spectrum detected from gamma rays induced in the formation, (ii) the calculation of a neutron porosity of the formation using the gamma-ray spectrum, and (iii) the determination of a bulk density of the formation using the spectroscopic measurements. The Pe factor may be inferred by directly mapping the spectroscopic measurements. The porosity may be calculated by relating the gamma-ray spectrum to a hydrogen content of the formation. The density may be determined by computing a gamma diffusion length of the formation based on the gamma-ray spectrum. In addition to these measurements, the resistivity of the formation and its spontaneous potential may also be measured using an electromagnetic induction system.

The present invention provides a gamma-neutron detector based on mixtures of thermal neutron absorbers that produce heavy-particle emission following thermal capture. The detector consists of one or more thin screens embedded in transparent hydrogenous light guides, which also serve as a neutron moderator. The emitted particles interact with the scintillator screen and produce a high light output, which is collected by the light guides into a photomultiplier tube and produces a signal from which the neutrons are counted. Simultaneous gamma-ray detection is provided by replacing the light guide material with a plastic scintillator. The plastic scintillator serves as the gamma-ray detector, moderator and light guide. The neutrons and gamma-ray events are separated employing Pulse-Shape Discrimination (PSD). The detector can be used in several scanning configurations including portal, drive-through, drive-by, handheld and backpack, etc.

A gamma ray detector module includes at least one scintillation detector configured to operate in a dot-decoding mode, or at least two scintillation detectors configured to operate in a line-decoding mode, wherein the at least one scintillation detector is each coupled to a single photodetector, and wherein the at least two scintillation detectors are coupled to at least two photodetectors arranged substantially along a line; and at least four scintillation detectors configured to operate in a plane-decoding mode, wherein the at least four scintillation detectors are coupled to a plurality of photodetectors arranged in a two-dimensional array.

The invention discloses a neutron-gamma ray detection device which belongs to the detection technology field. The detector adopts a conventional plastic scintillator or an inorganic crystal to detect gamma rays in the environment and adopts a layer of neutron absorber on the surface of the plastic scintillator or the inorganic crystal to detect neutrons; the detector can be separately used as a neutron detector or be separately used as the gamma detector or be used as the detector for simultaneously detecting the neutrons and the gamma. The neutron-gamma ray detection device can simultaneously detect and monitor the neutrons and/or gamma (X rays) in the environment and the gamma detector can be used as a moderator of the neutron detector, thereby greatly improving the neutron detection efficiency. Working substances of the whole detector are all solids, thereby facilitating the production, the installation, the transportation and the long-term outdoor works.

In a combined scanner, a main magnet (20) and magnetic field gradient coils (28) housed in or on a scanner housing (12, 18) acquires spatially encoded magnetic resonances in an imaging region (14). Solid state radiation detectors (50, 50', 50'') disposed in or on the scanner housing are arranged to detect gamma rays emitted from the imaging region. Time-of- flight positron emission tomography (TOF-PET) processing (52, 54, 58, 60, 62) determines localized lines of response based on (i) locations of substantially simultaneous gamma ray detections output by the radiation detectors and (ii) a time interval between said substantially simultaneous gamma ray detections. TOF-PET reconstruction processing (64) reconstructs the localized lines of response to produce a TOF-PET image. Magnetic resonance imaging (MRI) reconstruction processing (44) reconstructs the acquired magnetic resonances to produce an MRI image.

The present invention is a radially symmetric imaging detector that measures an incident neutron's or gamma-ray's energy and identifies its source on an event-by-event basis.

The present invention provides a nuclear medicine imaging apparatus and image data generation method that achieves restarting of the generation of projection data and at an early stage while monitoring a variation of count values for detecting an occurrence of non-permissible body movement of a patient. The image processing apparatus consistent with the present invention detects a pair of gamma-rays successively emitted from an object with a radioactive isotope through a pair of detector modules in a data detecting unit. A data processing unit and an incident direction calculating unit in the image processing apparatus respectively calculate a gamma-ray detection position and a gamma-ray incident direction based on the acquired detection signals. A projection data generating unit in the apparatus generates monitoring projection data based on each count value of the detection signals in correspondence to the gamma-ray detection position and the gamma-ray incident direction. A projection data monitoring unit calculates a body movement index of the object by comparing count values of the monitoring projection data that are generated in each of two preferably adjoining monitoring periods. A system control unit generates an alarm signal for performing repetition of the monitoring projection data when the body movement index exceeds a threshold value and displays the alarm signal on a display unit.

An apparatus and associated method for gamma ray detection that improves the timing resolution is provided. A crystal of interaction in a scintillation crystal array emits scintillation light in response to interaction with a gamma ray. The scintillation light is detected by one or more photomultiplier tubes. Each photomultiplier tube that detects the scintillation light detects the light at a different time. The apparatus determines the location of the gamma ray interaction and uses the location of the interaction to generate correction times for each waveform generated by the photomultiplier tubes. The waveforms are corrected with the correction timings and combined to extract a time of arrival estimate for the gamma ray. Noise thresholding is also used to select waveforms having low noise for combination to extract the time of arrival estimate.

Provided are a gamma ray detector and a gamma ray reconstruction method which can be used in SPECT and PET and which combine and reconstruct the information on “Compton-scattered” gamma rays, thereby remarkably increasing gamma ray detection sensitivity, decreasing the amount of a radioactive substance given to a subject, and remarkably reducing the concern about the amount of radiation exposure. The gamma ray detector comprises an absorber scintillator 12 made from an absorptive substance exhibiting a high rate of absorption with respect to gamma rays 1 in an energy region, emitted from a subject, a Compton scattering scintillator 14 made from a Compton scattering substance exhibiting a high probability of Compton scattering, and an energy detector 16 which combines the amounts of gamma ray energy absorption simultaneously measured by the two types of scintillators to reconstruct the gamma rays emitted from the subject. The two types of scintillators 12 and 14 are arranged in multiple layers so as to absorb or Compton-scatter the whole energy of the gamma rays 1.

The invention discloses an anti-Compton scattering detector, which comprises a main detector made of the sodium iodide material. The lower end of the main detector is connected with a photomultiplier. The main detector is nested into an auxiliary detector compounded of a plastic scintillator. The light guide material is arranged between the main detector and the auxiliary detector. The upper end of the auxiliary detector is connected with the photomultiplier. The lower end of the auxiliary detector is provided with a lead shielding ring. According to the invention, the background influence of natural gamma-ray scattered photons (Compton effect) is reduced to the maximum extent. Meanwhile, the accuracy of the in-situ environment gamma-ray detection result is improved. The structure unit of the detector is simplified and the power consumption of a complete machine is lowered.

The invention provides a positron emission computer tomography system and belongs to the field of medical devices. The system comprises three gamma-ray detection devices, three front-end electronics devices, three data acquisition devices, an electromechanical control device and three control devices, wherein three gamma-ray detection devices are used for generating gamma photons to hit crystals to produce visible light and converting the visible light into electric signals; three front-end electronics devices are used for determining single case information according to electric signals of corresponding gamma-ray detection devices; three data acquisition devices are used for acquiring the single case information obtained by corresponding front-end electronics devices and processing the single case information to obtain coincidence case information; the electromechanical control device is connected with data acquisition devices and is used for controlling movement of machine assemblies under the control of data acquisition devices; and three control devices which are correspondingly connected with data acquisition devices one by one are used for receiving the coincidence case information transmitted by corresponding data acquisition devices, and positron emission tomography (PET) images are obtained through processing. By the aid of the positron emission computer tomography system, the scanning speed can be accelerated, and the application range of PET can be broadened.

A method for making isolating plates for imaging array of crystal lattices, which comprises steps of: providing a substrate; coating a mirror film on the substrate by evaporation so as to form a mirror substrate; and, forming a comb-like isolating plate by the formation of a plurality of notches on the mirror substrate. By assembling a plurality of the comb-like isolating plates to form an array with a plurality of isolated spaces. After inserting a scintillator segment in each of those isolated spaces, an imaging array of crystal lattices for gamma ray detection in nuclear medicine can be manufactured. The imaging device of the invention is preferred since it is easy to assemble, inexpensive, and exhibits desirable imaging and light condensing effects.

A high sensitivity, three-dimensional gamma ray detection and imaging system is provided. The system uses the Compton double scatter technique with recoil electron tracking. The system preferably includes two detector subassemblies; a silicon microstrip hodoscope and a calorimeter. In this system the incoming photon Compton scatters in the hodoscope. The second scatter layer is the calorimeter where the scattered gamma ray is totally absorbed. The recoil electron in the hodoscope is tracked through several detector planes until it stops. The x and y position signals from the first two planes of the electron track determine the direction of the recoil electron while the energy loss from all planes determines the energy of the recoil electron.

A radiation detector for neutrons and gamma-rays is described. The detector includes a conversion screen (4a) comprising a mixture of a neutron absorbing material, e.g. containing ⁶Li, and a phosphorescent material, e.g. ZnS(Ag) and a wavelength-shifting light-guide (8) arranged to receive photons emitted from the phosphorescent material and generate wavelength-shifted photons therefrom. The wavelength-shifting light-guide is doped so as to form a gamma-ray scintillator material operable to generate scintillation photons in response to a gamma-ray detection event therein. A photodetector (10) is optically coupled to the wavelength-shifting light-guide and arranged to detect the wavelength-shifted photons and the scintillation photons. Signals from the photodetector are processed to distinguish neutron detection events from gamma ray detection events.

This application relates to radiation detection, and more particularly, to a method and device for the remote detection and localization of nuclear materials in an unknown background. A method and apparatus for long range neutron and gamma ray detection and imaging is disclosed wherein a panel of thin walled tube detectors are rotated to enhance detection performance. The method and apparatus have particular applicability to portable monitoring and homeland security.

Disclosed herein is a prompt gamma-ray detection apparatus for analyzing chemical materials using femtosecond pulse laser-induced neutrons, which can be effectively used in the nondestructive inspection of various materials, such as metals, coal, cement, radioactive materials and the like as well as explosives and chemical materials, and which can provide better measurement results for the analysis of basic materials, and a method of measuring prompt gamma-rays using the apparatus. The prompt gamma-ray detection apparatus is advantageous because it can non-destructively analyze the elements in a chemical sample using a femtosecond pulse laser-induced neutron generator that solves the problems of an atomic reactor for research or a radioactive isotope as a neutron radiation source.

The special gamma spectrograph for moon exploration is provided with crystal scintillator connected to photomultiplier tube and data acquisition circuit successively and features that there are main detector and anticoincidence detector with scintillator connected to one other photomultiplier tube and that the photomultiplier tube of both the main detector and the anticoincidence detector are connected to the data acquisition circuit simultaneously. The data acquisition circuit has microprocessor. The novel gamma ray detection instrument has high sensitivity, low cost, optimal background radiation inhibiting effect and increased detector effective area. The optimal scheme has CsI (Ti) crystal in anticoincidence detector and crystal scintillator of several crystals adhered together.

The invention discloses an on-board radiation source positioning device, which belongs to the field of radioactivity detection. The device comprises gamma ray detection crystals arranged at the top part of a rotation shaft; each gamma ray detection crystal is composed of four plastic scintillators of the same size; the four plastic scintillators are correspondingly connected with four nuclear electronic signal processing units; the four nuclear electronic signal processing units are connected with a computer processing unit; and metal shading layers are arranged between the four plastic scintillators, between the plastic scintillators and the nuclear electronic signal processing units and between the plastic scintillators and the rotation shaft. Differences between deposited gamma rays of the four gamma ray detection crystals shaded by a lead plate are used, according to the dose rate ratio of the deposited gamma rays, a relation between the ratio and the distance between the radiation source and the device is obtained through calculation, and the radiation source can be quickly positioned. The invention also discloses a positioning method by using the above on-board radiation source positioning device.

The invention relates to a power spectrum analysis method. The method comprises the steps: converting particle energy into an initial pulse signal, processing the initial pulse signal into a step pulse signal, converting the step pulse signal into a rectangular pulse signal after pulse shaping of the step pulse signal, enabling the pulse amplitude of the rectangular pulse signal to be a set value, enabling a corresponding relation to be formed between the pulse width of the rectangular pulse signal and the pulse amplitude of the step pulse signal, measuring the pulse width of the rectangular pulse signal and corresponding pulse counting to obtain the pulse width spectrum of the rectangular pulse signal, converting the pulse width spectrum into a pulse amplitude spectrum according to the corresponding relation between the rectangular pulse width and the step pulse amplitude or directly converting the pulse width spectrum into a power spectrum of particles according to a corresponding relation between the rectangular pulse width and the energy of particles. The invention also relates to a power spectrum analysis system and a Gamma ray detection system. The invention helps to solve the problem of the prior art that a power spectrum analysis process contains a complicated A/D converting circuit and thus the integration level is difficult to improve.