Detection System Configuration Research Articles

Incoherent color holography lattice light-sheet for subcellular imaging of dynamic structures

The purpose of the article is to explore the need and advantages of using the incoherent color holography lattice light-sheet (ICHLLS) to provide multiwavelength quantitative monitoring of 3D cellular dynamics in live tissue to further understand complex functions of cells and cellular compartments. We have explored the use of incoherent color holography lattice light-sheet to investigate colocalization of fluorescent markers in live cells in intact tissue. Neuronal structures provide an attractive target for incoherent color holography lattice light-sheet. The cells show a complex architecture in 3D space in which signaling both between cells and within subcellular structures requires colocalization of proteins and lipids to function. During activity and over long periods it is important in understanding these signaling functions in Parkinson’s, Alzheimer’s and motoneuron diseases within live cells in intact tissue. As a proof of concept this article recalls the key aspects in lattice light-sheet imaging and provides a description of the incoherent detection system configuration to actively control dual diffractive lenses phase-shifting at multiple excitation wavelengths sequentially, and per each z-galvo scanning level, with extended field-of-view. The incoherent color holography lattice light-sheet system will allow simultaneous recording of multidimensional object waves that contain intensity in 3D space, phase, and wavelength information. We measure colocalization of fluorescence indicators introduced into live cells in intact neural tissue.

Low-activity gamma source direction detection system based on NaI scintillator detector

A system consisting of two NaI scintillators and 316L steel shield for low-activity gamma source directional detection is designed, and several calibration methods for different directional accuracy requirements are proposed. It is found that the direction parameter obtained by repeated simulation process under the same condition is equivalent to the sampling in a normal distribution. Thus, a neural network confidence evaluation method, which provides a new idea for the evaluation of low-activity gamma source directional detection system, is innovatively proposed. A quantitative analysis process of radiation background effect based on signal-to-noise ratio is introduced. Compared with previous results, it is found that the proposed detection system configuration has evident advantages.

Compton polarimetry with a multi-layer CdTe focal plane prototype

In high-energy astrophysics, polarimetry is a promising subject with a wide scientific potential that is relatively unexplored due to the complexity of the design and technical requirements of the sensors. Often gamma-ray telescope proposals are based on multi-layer spectro-imager instruments with polarimetric capabilities. Herein we study a new Compton polarimeter prototype based on a two-layer CdTe pixelized spectro-imager operated in coincidence. The two CdTe detectors are 2 mm thick anode 8×8 pixels’ segmented matrices with 2 mm pitch. This detection system configuration allows an assessment of the polarimetric potential of multi-layer solution focal planes as well as the polarimetric potential of a possible 3D spectro-imager by analysing the polarimetric performance when varying the distance between the two CdTe detection layers. The polarimetric modulation factors for single-layer (Q∼0.4) and two-layer (up to 0.13) double-events were measured for 6 mm and for 10 mm distance between planes. The measured polarization angle resolution was lower than 10°. The potential of CdTe spectro-imager focal plane solutions with polarimetric capabilities for the next generation space missions based on both Laue lenses and 3D segmented focal planes is also discussed.

Magnetic Particle Detection System Using Fluxgate Gradiometer on a Permalloy Shielding Disk

A new, fine-magnetic-particle detection system is proposed that uses a fundamental-mode orthogonal fluxgate (FM-OFG) gradiometer positioned on a Permalloy shielding disk. The Permalloy disk reduces the gradiometer sensitivity to magnetic field interference, thus enhancing the sensor resolution and measurement signal-to-noise ratio. The proposed detection system configuration offers an inexpensive and compact alternative to commercially available SQUID sensor magnetic contaminant detection systems. Numerical analysis was conducted to investigate the effective shielding area of the Permalloy disk. Experiments with a 10 cm diameter Permalloy disk showed that the FM-OFG gradiometer uniform magnetic field sensitivity was reduced by a factor of 0.25 at a 10 mm sensor baseline. Detection of a steel ball of 120 μm diameter was achievable under 10 Hz magnetic field interference, generating 150 nT/m signal peak-to-peak in the gradiometer output, where the noise peak-to-peak was reduced to 46.8 nT/m. The signal-to-noise ratio of the 120 μm steel ball detection signal was increased by a factor of 4.6 when using the Permalloy disk.

A theoretical comparison of position estimation methods for determining the interaction position of gamma rays in monolithic scintillators.

We report the development of a mathematical model, based on the estimation theory, for the performance analysis of different gamma-ray interaction position estimation methods applied to gamma cameras based on monolithic scintillators. The gamma camera performance is expressed in terms of bias and spatial resolution. We propose a method to investigate performances of various detection system configurations, used in recent papers, when different image reconstruction algorithms are used. The results are obtained for the whole field of view, with a computational time five order of magnitude lower than a Monte Carlo simulation. We developed a mathematical model for four estimation methods: the classical Center of Gravity method (Anger Logic), an enhanced Center of Gravity method, a Mean Square Error fitting method and the Maximum Likelihood method. Moreover, those models can be used to investigate edge effects and performance of a detector with an arbitrary pattern of active elements and dead areas, in order to study systems with more multianode PMTs or SiPM array modules. The bias and spatial resolution results obtained with those mathematical model were compared with the ones obtained from Monte Carlo simulations, made with GEANT4, showing a very good agreement for all the methods.

The resolution estimation of wedge and strip anodes

A new resolution estimation method for wedge and strip anode based on the single photon imaging configuration is provided. The limiting resolution estimation equation is deduced theoretically according to the threshold principle. The relation between the charge cloud and the covered electrodes is discussed, and the equivalent diameter number is calculated. The resolution equation for the position deviation amplitude or FWHM is provided if noise exists. The relation between the position deviation amplitude and the total charge deviation amplitudes is discussed. The constancy of the position deviation amplitudes versus positions is provided. The results calculated from these equations are discussed. According to the equations, it is indicated that the spatial resolution is affected by the detection system configuration and noise. These conclusions may be useful for the designing and performance improvement of future photon imagers.

A Feasibility Study to Determine Cooling Time and Burnup of Advanced Test Reactor Fuel Using a Nondestructive Technique and Three Types of Gamma-ray Detectors

Abstract The goal of this work was to perform a feasibility study and establish measurement techniques to determine the burnup of the Advanced Test Reactor (ATR) fuels at the Idaho National Laboratory (INL). Three different detectors of high purity germanium (HPGe), lanthanum bromide (LaBr3), and high pressure xenon (HPXe) in two detection system configurations of below and above the water pool were used in this study. The last two detectors were used for the first time in fuel burnup measurements. The results showed that a better quality spectra can be achieved with the above the water pool configuration. Both short and long cooling time fuels were investigated in order to determine which measurement technique, absolute or fission product ratio, is better suited in each scenario and also to establish what type of detector should be used in each case for the best burnup measurement. The burnup and cooling time calibrations were established using experimental absolute activities or isotopic ratios and ORIGEN burnup calculations. A method was developed to do burnup and cooling time calibrations using fission isotopes activities without the need to know the exact geometry.

A cost-based analysis of intrusion detection system configuration under active or passive response

This paper studies the joint decisions of IDS configuration and alarm investigation capacity under active and passive responses. In active response, alarm events are blocked immediately, whereas alarm events are allowed to access the information assets in the passive response. Despite facilitating information flow, passive response exposes the assets to attacks while the security analysts investigate the alarms. On the other hand, active response may unnecessarily delay the benign traffic since alarm events are blocked. We find closed-form formulas for the optimal investigation capacity and show the optimal configuration under active response is smaller than under passive response. We also provide expressions that can be used to evaluate security costs and benefits under various configurations, capacities and responses. Numerical studies are done to illustrate the sensitivity of the optimal decisions.

Automatic analysis of firewall and network intrusion detection system configurations

Automatic analysis of firewall and network intrusion detection system configurations

A distributed optical fiber sensor for temperature detection in power cables

The power transfer capacity of an underground power cable is limited by high-temperature regions that occur along the cable. It is very difficult to determine and control these ‘hot spots’. Optimum use and temperature profile control of power cables before and during load transmission can be achieved with real-time processing of temperature data. There are various methods developed for this purpose such as conventional point temperature measurement method, where a large number of sensors and connectors are required, and methods based on mathematical models which can only approach real values by approximation. In this study, temperature detection in an XLPE insulated 154 kV power cable is performed using a distributed sensing method where the optical fiber itself behaves as a sensor. Therefore, there is no need for the devices of conventional method. Moreover, contrary to methods based on mathematical models, where it is difficult to predict environmental variations, this method considers the variations with a temperature resolution of ±1 °C. Distributed temperature sensing (DTS) method, detection system configuration and required system parameters are explained in the paper. Experimental results obtained for 126 and 412 m cables show a temperature resolution of ±1 °C and a spatial resolution of 1.22 m. Simulations for a 10 km cable are also given. Results show that DTS is a reliable method for both short and long range cable systems.