3,123 resources related to Gamma-rays
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IEEE International Conference on Plasma Science (ICOPS) is an annual conference coordinated by the Plasma Science and Application Committee (PSAC) of the IEEE Nuclear & Plasma Sciences Society.
fusion engineering, physics and materials, plasma heating, vacuum technology, tritium processing, fueling, first walls, blankets and divertors
The conference covers all aspects of the technology associated with ultrasound generation and detection and their applications.
This conference is the annual premier meeting on the use of instrumentation in the Nuclear and Medical fields. The meeting has a very long history of providing an exciting venue for scientists to present their latest advances, exchange ideas, renew existing collaboration and form new ones. The NSS portion of the conference is an ideal forum for scientists and engineers in the field of Nuclear Science, radiation instrumentation, software engineering and data acquisition. The MIC is one of the most informative venues on the state-of-the art use of physics, engineering, and mathematics in Nuclear Medicine and related imaging modalities, such as CT and increasingly so MRI, through the development of hybrid devices
The IEEE Photonics Conference, previously known as the IEEE LEOS Annual Meeting, offers technical presentations by the world’s leading scientists and engineers in the areas of lasers, optoelectronics, optical fiber networks, and associated lightwave technologies and applications. It also features compelling plenary talks on the industry’s most important issues, weekend events aimed at students and young photonics professionals, and a manufacturer’s exhibition.
The IEEE Aerospace and Electronic Systems Magazine publishes articles concerned with the various aspects of systems for space, air, ocean, or ground environments.
The IEEE Transactions on Automation Sciences and Engineering (T-ASE) publishes fundamental papers on Automation, emphasizing scientific results that advance efficiency, quality, productivity, and reliability. T-ASE encourages interdisciplinary approaches from computer science, control systems, electrical engineering, mathematics, mechanical engineering, operations research, and other fields. We welcome results relevant to industries such as agriculture, biotechnology, healthcare, home automation, maintenance, manufacturing, pharmaceuticals, retail, ...
Electrical insulation common to the design and construction of components and equipment for use in electric and electronic circuits and distribution systems at all frequencies.
Publishes original and significant contributions relating to the theory, design, performance and reliability of electron devices, including optoelectronics devices, nanoscale devices, solid-state devices, integrated electronic devices, energy sources, power devices, displays, sensors, electro-mechanical devices, quantum devices and electron tubes.
Measurements and instrumentation utilizing electrical and electronic techniques.
2006 IEEE Nuclear Science Symposium Conference Record, 2006
We have developed a new Monte Carlo simulation based on SimSET to model spurious activity caused by cascade gamma (gamma) rays in PET imaging. A torso phantom including lungs, a spine and a lesion was simulated to mimic PET imaging of Y-86. Contributions from positrons (beta+) only, beta+-gamma and gamma-gamma cascade events were binned in separate 2D sinograms and analyzed ...
2010 Abstracts IEEE International Conference on Plasma Science, 2010
The detection of fissile material by passive and active techniques is an area of intense interest. Many active approaches detect the products of fission induced by photon and/or neutron irradiation.1One such approach has focused on using intense, pulsed, beam-target interactions to produce an irradiation source of 6.13-, 6.92-, and 7.13-MeV characteristic gamma rays from the19F(p, αγ)16O reaction.2,3Initially, work at NRL ...
2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC), 2009
In the present work, the Neural Networks (NNs) are used to reconstruct the interaction point of an event producing a signal shared among different photodetector in a conventional Anger Camera. The event is caused by the interaction of a medium-high energy gamma ray within a scintillator crystal coupled with Silicon Drift Detectors (SDDs). Two different energy ranges are considered for ...
2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD), 2016
This paper reports a feasibility study, performed by numerical simulation with MCNPX, of fissile mass characterization in dense, large volume, long-lived and medium activity radioactive waste packages, using photofission delayed gamma rays. High-energy photon interrogation with a 15 MeV LINAC has been modelled for a 1.18 m3cemented waste package, coupled to high resolution spectroscopy with a HP Ge detector. The ...
Proceedings of the 22nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (Cat. No.00CH37143), 2000
Some biological effects of gamma-rays have been evaluated in cells of the bacteria Escherichia coli, through the comparison of the number of colonies formed by a unitary cell (CFU) proceeded from an unirradiated control suspension and from an irradiated suspension, and through the visualization of possible damage in the microorganism enzymatic system due to irradiation with high energy photons (/sup ...
We have developed a new Monte Carlo simulation based on SimSET to model spurious activity caused by cascade gamma (gamma) rays in PET imaging. A torso phantom including lungs, a spine and a lesion was simulated to mimic PET imaging of Y-86. Contributions from positrons (beta+) only, beta+-gamma and gamma-gamma cascade events were binned in separate 2D sinograms and analyzed in the reconstructed images. The total abundances for beta+only, beta+-gamma and gamma-gamma cascades events modeled are 2.5%, 30.5% and 60.9%, respectively. The phantom was first simulated without attenuation (in air). Image intensities were estimated in Regions of Interest (ROIs) drawn in the reconstructed volumes for each cascade type as well as for their combination. Both cascade components contributed to an increase in spurious coincidences uniformly distributed throughout the image. A more realistic phantom (filled with water) was then simulated with or without modeling cascades. When cascade gamma rays are modeled, there is a slight increase of spurious activity in cold regions and a slight decrease of intensity in high-activity regions. While there is no significant change in LBR with or without cascade gamma events, the total counts increased greatly in the detector. To track the same number of beta+, the total photon number is 4.4 times higher for Y-86 when modeling cascade events, causing a significant increase in detector dead time due to the increase of singles rate. The scatter fraction also increased, which was 18.95% without modeling cascades, and 26.75% when cascades were modeled. The simulation results are being validated with phantom experiments. Characterizing the spurious activity caused by cascade gamma rays in Y-86 PET imaging is crucial for the development of quantitative PET imaging of gamma ray emitting isotopes.
The detection of fissile material by passive and active techniques is an area of intense interest. Many active approaches detect the products of fission induced by photon and/or neutron irradiation.1One such approach has focused on using intense, pulsed, beam-target interactions to produce an irradiation source of 6.13-, 6.92-, and 7.13-MeV characteristic gamma rays from the19F(p, αγ)16O reaction.2,3Initially, work at NRL utilized the Gamble-II, 3-Ω, water- line generator with a pinch-reflex ion diode that accelerates ions to 2 MeV at ~ 0.5-TW peak ion power.3This pulsed source also simultaneously produces neutrons from: (1) a collective ion-acceleration mechanism associated with the diode and (2) the reactions resulting from the isotopic abundance of deuterons in the ion beam, e.g.,12C(d, n)13N and19F(d, n)20Ne. In this presentation, we review progress toward characterizing a similar mixed source using the Mercury inductive voltage adder operated in positive polarity producing ~ 4-MeV4ion energy and ~ 0.3-TW peak ion power. An array of diagnostics is used to determine the number of gamma rays and neutrons produced by the source, including a shielded scintillator-photomultiplier for the gamma-ray time history and a rhodium-activation counter to measure the total number of neutrons produced. In addition, the gamma and neutron source strengths are inferred from delayed neutrons that result from fissions in depleted uranium and that are measured using3He and6Li neutron detectors.
In the present work, the Neural Networks (NNs) are used to reconstruct the interaction point of an event producing a signal shared among different photodetector in a conventional Anger Camera. The event is caused by the interaction of a medium-high energy gamma ray within a scintillator crystal coupled with Silicon Drift Detectors (SDDs). Two different energy ranges are considered for the incident gamma ray: 122-140 keV and 1.1 MeV. In the first one (122-140 keV), the Photoelectric Effect is dominant over the Compton Effect, while in the second one (1.1 MeV) the situation is the opposite and the Pair Production Effect may still be ignored. At low energies, it is shown that the NNs obtain results in simulations and with experimental data comparable or better than other methods, like the Centroid (CM) and the Maximum Likelihood (ML) ones, and a precision lower than 1 mm at low noise levels (for an Equivalent Noise Charge -ENC- less than 20e<sup>-</sup>). At high energies, the NNs maintain a good precision, even in the occurrence of Compton interactions, with a spatial resolution of approximately 2.1 mm. Finally, the possibility to obtain the second interaction point position when a Compton Scattering occurs is examined and first simulations are presented.
This paper reports a feasibility study, performed by numerical simulation with MCNPX, of fissile mass characterization in dense, large volume, long-lived and medium activity radioactive waste packages, using photofission delayed gamma rays. High-energy photon interrogation with a 15 MeV LINAC has been modelled for a 1.18 m3cemented waste package, coupled to high resolution spectroscopy with a HP Ge detector. The study was carried out by assessing the passive and active backgrounds respectively due to the waste package gamma emission, and to material activation during irradiation, in view to determine the detection limits for the main delayed gamma rays of interest. The obtained detection limits are lower than the expected uranium mass in the waste package. On the other hand, as the photofission signal results from both fissile235U and fertile238U isotopes, a method for uranium isotopes discrimination based on gamma-ray ratios has been evaluated, showing that photofission delayed gamma rays could be used to assess the fissile mass as well as the total uranium mass.
Some biological effects of gamma-rays have been evaluated in cells of the bacteria Escherichia coli, through the comparison of the number of colonies formed by a unitary cell (CFU) proceeded from an unirradiated control suspension and from an irradiated suspension, and through the visualization of possible damage in the microorganism enzymatic system due to irradiation with high energy photons (/sup 60/Co /spl gamma/-rays). For this purpose, for absorbed doses at up to 280 Gy, the methods of successive dilutions and sowing in Petri plates containing simple agar and MacConkey agar, were used. It was verified that the irradiated suspension presented a growth of up to 10 times lesser than the growth of the suspension that had been controlled, but it was not possible to visualize damage in Escherichia coli enzymatic system, due to irradiation with the absorbed dose values tested.
It is important to detect low energy gamma rays precisely for the purpose of diagnosis in nuclear medicine, gravitational wave research and detection of underground nuclear test. Since a silicon sensor has an advantage of fast response, good intrinsic energy resolution and providing high signal yield in a small active volume, it can be used to detect low energy gamma rays without the help of a scintillator. We developed silicon PIN diodes and photodiodes on high resistivity, n+ doped, and 6-in. double-side polished silicon wafers. We present measurements of responses, such as signal pulse heights, signal-to- noise ratios and energy resolutions, of these detectors to low energy gamma rays from <sup>241</sup>Am, <sup>133</sup>Ba and <sup>57</sup>Co radioactive sources which provide gamma rays between 14.4 keV and 136.5 keV of energy. We also compare the measurement results depending on the diode thickness.
A small desktop prototype of the Tracking and Imaging Gamma-Ray Experiment (TIGRE) has been assembled and tested at 511 keV and 900 keV. TIGRE was designed to observe cosmic gamma ray sources at energies of 0.3 to 100 MeV. Its major feature is its use of multi-layer silicon strip detectors to track Compton recoil electrons and positron-electron pairs. Our small prototype consists of 7 double sided silicon strip detectors 3.2 cm/spl times/3.2 cm/spl times/300 micron with 1 mm pitch in both the x and y directions. The direction and energy of the Compton scattered gamma ray is measured with small CsI(Tl) photodiode detectors. Knowing the energy and momentum of the scattered electron and scattered photon allows us to determine the incident direction uniquely. In the small prototype 36 CsI(Tl) crystals of 1 cm/spl times/1 cm/spl times/1.7 cm were used. Non-tracked events, those interacting in only a single silicon plane, can only be determined to within the Compton scatter ring. The silicon strips were calibrated using the 60 keV photons from Am/sup 241/ and the Landau peak obtained from a Sr/sup 90/ beta source. The energy resolution of the silicon was measured to be 8 keV (1/spl sigma/) at 60 keV and 7.8% FWHM for CsI at 900 keV. Total energy resolutions at 511 and 900 keV were measured to be 11% and 8.9% FWHM respectively. An important requirement of TIGRE will be its ability to separate the upward moving gamma rays produced by cosmic ray interactions in the atmosphere from the downward moving gamma rays. For tracked events this is done by defining a direction of motion (DOM) parameter for the electron by its energy deposition and multiple scattering in the silicon layers. Measurements at 511 and 900 keV show that the DOM parameter is correctly predicted at 70% and 75% for tracked events which constitute 9% and 20% of the data. Monte Carlo simulations show similar results and show the percentage increasing to 98% at 6 MeV in which nearly all of the events are tracked.<<ETX>>
Summary form only given, as follows. At the Nova Laser Facility, a high-speed neutron detector records the fusion reaction rate for inertial-confinement fusion (ICF) experiments with a resolution of 30 ps. It is unlikely that the current measurement technique can provide similar resolution at the future National Ignition Facility (NIF). The larger target-to-detector distance and higher plasma ion temperature will limit temporal resolution between 125 and 600 ps for direct neutron measurements. We are investigating a measurement technique based on the 16.7-MeV gamma rays that are released in deuterium- tritium fusion. Temporal resolution is independent of the target-to-detector distance since no temporal dispersion occurs for gamma rays. Detector design must, however, account for the small branching ratio of <10/sup -4/ for gamma ray production and a large burst of 14-MeV neutrons. Our concept is to convert gamma-ray energy into a fast burst of Cerenkov light that can be recorded with a high-speed optical detector. Fusion gamma rays interact with a thin, high-z converter primarily by pair production to produce electron-positron pairs with energies of 8 MeV. Cerenkov light is produced when the electrons and positrons pass through a thin layer of material whose index of refraction is slightly greater than 1. An optical telescope relays the Cerenkov light to the detector. We have detected 16.7-MeV fusion gamma rays in preliminary experiments conducted at Nova. We used a tungsten/aerogel converter to generate Cerenkov light and recorded the signal with an optical streak camera.
Chemically cross-linked polyethylene irradiated by γ-rays to certain designated doses from 100 to 800 kGy at 100 °C in air was analyzed by X-ray diffraction, infrared spectroscopy and terahertz spectroscopy. It was found by infrared spectroscopy that the degree of oxidation increased when the sample was irradiated. By the terahertz spectroscopy, a peak appears at around 44 cm-1(≃1.3 THz) when the sample was irradiated by γ-rays. By carrying out the Cole-Cole analysis on the complex permittivity spectra associated with the peak at 44 cm-1, the dipolar relaxation was found to exhibit a nearly single relaxation process. This suggests that the terahertz spectroscopy has a potential to detect the oxidative degradation of cross-linked polyethylene.
We present a novel concept of the SNM imaging system based on cosmic-ray muon tracking in coincidence with neutron/gamma detection. The cosmic-ray flux at sea level is about 1 muon/sq. cm/minute. It is composed of nearly equal numbers of μ+ and μ-. In previous work, we have demonstrated that these muons can be used to image nuclear threats in relatively short times by measuring their multiple scattering through objects. Here we propose to image nuclear objects by combining tracking of the muons into a scene with measurements of the secondary particles produced when the muons stop in dense potentially fissile materials. We use multiple drift tube planes to trace incoming cosmic rays. Plastic scintillator serves as a detector of outgoing neutrons and gamma-rays. Additionally, the same plastic scintillator is used to estimate the energy of incoming cosmic-rays. We use a coincidence of n/gamma detection with the initial cosmic-ray trigger to suppress the background. The fissions produced by the stopped μ-generate fission chains that die away after several (~5) fissions. Each fission produces ~10 energetic gamma rays and ~2.5 neutrons. Although a self-shielding needs to be considered, it is likely that tens of neutrons and gamma rays will escape from the object of typical configuration. The efficiency of detecting at least one of the products within ~100 ns could be close to 100% for a detector of reasonably large solid angle (~2 ster). Ten minutes of data should produce 50 trajectories from μ-stopped in 20 kg of U. These numbers can be scaled for other size objects. Our approach has no active source, and therefore it is safe for humans and has no effect on the object under inspection. The detectors are scalable and portable. The drift tubes of the detectors are sealed and do not need the gas replenishment. Detection and localization of SNM is achieved with automatic reconstruction algorithm, which can be run at a standard computer.
Nuclear Science - Postdoctoral Researcher
Lawrence Livermore National Laboratory
Nuclear nonproliferation, Threat detection - Postdoctoral Researcher
Lawrence Livermore National Laboratory