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A method for reconstructing the direction of a fast neutron source using a segmented organic scintillator-based detector and deep learning model is proposed and analyzed. The model is based on recurrent neural network, which can be trained by a sequence of data obtained from an event recorded in the detector and suitably pre-processed. The performance of deep learning-based model is compared with the conventional double-scatter detection algorithm in reconstructing the direction of a fast neutron source. With the deep learning model, the uncertainty in source direction of 0.301 rad is achieved with 100 neutron detection events in a segmented cubic organic scintillator detector with a side length of 46 mm. To reconstruct the source direction with the same angular resolution as the double-scatter algorithm, the deep learning method requires 75% fewer events. Application of this method could augment the operation of segmented detectors operated in the neutron scatter camera configuration for applications such as special nuclear material detection., Comment: 15 pages. 9 figures. Preprint submitted to Elsevier August 2022

Tritium extraction from radioactively contaminated cement mortar samples was performed using heating and liquid scintillation counting methods. Tritiated water molecules (HTO) can be present in contaminated water along with water molecules (H2O). Water is one of the primary constituents of cement mortar dough. Therefore, if tritium is present in cement mortar, the buildings and structures using this cement mortar would be contaminated by tritium. The radioactivity level of the materials in the environment exposed to tritium contamination should be determined for their disposal in accordance with the criteria of low-level radioactive waste disposal facility. For our experiments, the cement mortar samples were heated at different temperature conditions using a high-temperature combustion furnace, and the extracted tritium was collected into a 0.1 M nitric acid solution, which was then mixed with a liquid scintillator to be analyzed in a liquid scintillation counter (LSC). The tritium extraction rate from the cement mortar sample was calculated to be 90.91% and 98.54% corresponding to 9 h of heating at temperatures of 200 °C and 400 °C, respectively. The tritium extraction rate was close to 100% at 400 °C, although the bulk of cement mortar sample was contaminated by tritium.

A beta ray scanner was proposed for in-situ discrimination of beta and gamma ray radioactivity. This scanner is based on the principle that gamma and beta rays experience different changes in detection efficiency in scintillators with different geometries, especially with regard to the scintillator thickness. The ratios of the counting rates of gamma rays (Rgamma), beta rays (Rbeta), and sample measurements (Rtotal) in a thick scintillator to those in a thin one are reported. The parameter Xthick, which represents the counting rate contributed by beta rays to the total counting rate in the thick scintillator, was derived as a function of those ratios. The values of Rgamma and Rbeta for 60Co and 90Sr sources were estimated as 3.2 ± 0.057 and 0.99 ± 0.0049, respectively. The estimated beta ray contributions had relative standard deviations of 2.05–4.96%. The estimated range of the beta rays emitted from 90Sr was 19 mm as per the Monte Carlo N-Particle simulation, and this value was experimentally verified. Homogeneous and surface contaminations of 60Co and 90Sr-90Y were simulated for application of the proposed method. The counting rate contributed by the beta rays was derived and found to be proportional to the concentration of 90Sr-90Y contamination.

Developing an online monitoring system becomes useful for continuously detection of tritium in water. A plastic scintillator chamber was used to tritium detection in hydrogen gas produced by a proton exchange membrane electrolysis cell. The fractionation factor (proton selectivity) was estimated as being of 5.41 ± 0.20, and detection efficiency of the plastic scintillator chamber was 4.25 ± 0.22%. For liquid samples, the minimum detectable activity of the developed system was estimated as 655 kBq L−1. Using this online technique for tritium monitoring based on electrolysis is expected to be useful for analysis of large tritiated water bearing samples.

The performance of a plastic scintillator for use in an in situ measurement system was analyzed using simulation and experimental methods. The experimental results of four major pure beta-emitting radionuclides, namely 3H, 14C, 32P, and 90Sr/90Y, were compared with those obtained using a Monte Carlo N-particle (MCNP) code simulation. The MCNP simulation and experimental results demonstrated good agreement for 32P and 90Sr/90Y, with a relative difference of 1.95% and 0.43% between experimental and simulation efficiencies for 32P and 90Sr/90Y, respectively. However, owing to the short range of beta particles in water, the efficiency for 14C was extremely low, and 3H could not be detected. To directly measure the low-energy beta radionuclides considering their short range, a system where the source could flow directly to the scintillator was developed. The optimal thickness of the plastic scintillator was determined based on the suggested diameter. Results showed that the detection efficiency decreases with an increase in the depth of the water. The detection efficiency decreased drastically to approximately 10 cm, and the tendency was gradually constant. Keywords: Plastic scintillator, In situ measurement system, MCNP code simulation, Beta-emitting radionuclides

The electrolysis conditions in a proton exchange membrane (PEM) cell were optimized by varying the current supplied; the detection efficiency for gaseous tritium generated from the PEM cell under optimized electrolysis conditions was analyzed. The current was optimized to 7 A. Under the optimized current condition, the change in activity of the tritiated water before and after electrolysis was 200 ± 11 kBq. When tritiated water with tritium activity concentration of 2912 kBq/L was electrolyzed, the detection efficiency was 31.3 ± 1.3%. Moreover, the minimum detectable activity of gaseous tritium was 10.3 ± 0.8 kBq/m3 in 5 min.

The minimum detectable activity (MDA) value was derived according to the flow rate of the sample and degree of amplification of the device by sending the sample directly from the collection site to the detection part through a pump. This method can lead to reduction in time and cost compared to the existing measurement method that uses a pre-treatment process. In this study, experiments were conducted on 3H and 90Sr, which are the major pure beta-emitting radionuclides, by setting the sample flow rate and the amplification gain as factors. The MDA values were derived according to the flow rates, considering that the flow rate can affect the MDA values. There were no change in the MDA under different flow rates of 0, 600, 800, and 1000 mL/min. Therefore, it was confirmed that the flow rate may not be considered when collecting samples for monitoring in actual field. As the degree of amplification of the amplifier increased, the time required to reach the target MDA decreased. When the amplification was quadrupled, the detection efficiency increased by approximately 23.4 times, and the time to reach the MDA decreased to approximately 1/550 times. This method offers the advantage of real-time on-site monitoring. Keywords: Groundwater monitoring, Gross beta measurements, Tritium, On-site measurement, Minimum detectable activity

Radon is a natural radionuclide that can cause cancer of the lungs and stomach upon inhalation and ingestion, respectively; therefore, the radon content in groundwater needs to be continuously monitored. If the concentrations are high, it may take a long time to stabilize the detector contaminated with radon daughters. To overcome this problem, a radon in water measurement system based on the membrane-based air-water separation method is proposed to reduce the waiting time between measurements. The system consists of a water separation part, mixer, and radon measurement part, and it separates radon from water and controls the radon concentration. In this study, the behavior of radon was theoretically evaluated, and the separation and mixing of radon were tested. By analyzing the radioactivity of the water sample and the amount of radon separated within a certain period, it was determined that 86% of the radon was separated from the water and measured by the detector. The count rate of the air-mixing experiment was in good agreement with the theoretical model with coefficients of determination of 0.97, 0.91, and 0.95 for mixtures with ratios of air from water to external air as 1:0, 1:1, and 1:3, respectively.

An in situ detection method for beta-ray distribution was developed. The method uses the gamma-ray sensitivity difference between two scintillators: a cadmium–tungstate (CdWO4) scintillator and a plastic scintillator. The gamma-ray sensitivity ratios for several gamma-ray sources such as 137Cs, 60Co, 22Na, and 54Mn were experimentally characterized. The sensitivity ratio for 137Cs between the CdWO4 and plastic scintillators was 8 ± 0.32, while the sensitivity ratio for beta rays from 90Sr was 1.03 ± 0.006. The beta-ray contributions to the total counts can be evaluated using this characteristic. A combined beta-ray and gamma-ray source was prepared, and its beta-ray distribution was successfully obtained using the proposed method.

Our goal was to develop a mobile tritium monitor for continuous inflow system for water sample. The system is based on electrolysis and a plastic scintillator detection system. The minimum detectable activity (MDA) of the prototype system is 431 kBq L−1, while the MDA of a commercially available product is 740 kBq L−1. We expected to achieve a 5.73-times lower MDA by optimizing detection geometry using a multi-hydrogen-gas-channel. The system can be applied either as a mobile leakage surveying method or as a fixed-type monitor for detecting tritium in drinking water by adapting conventional background reduction technologies.

A method of separating beta spectra into each radionuclide spectrum was proposed in this study. Based on mathematical curve fits, the spectrum of each radionuclide was defined by using the maximum energy information and process to separate specific spectra from the whole spectrum. Information on 32P, 90Y, and 106Rh radionuclides from the International Commission on Radiation Units and Measurements was used for applying the proposed method. A relative error of less than 2% was achieved with the application of the method.

Background: The scattered photons cause reduction of the contrast of radiographic image and it results in the degradation of the quality of the image. In order to acquire better quality image, an anti-scattering x-ray gird should be equipped in radiography system. Materials and Methods: The X-ray anti-scattering grid of the inclined type based on the hybrid concept for that of parallel and focused type was tested by MCNP code. The MCNPX 2.7.0 was used for the simulation based test. The geometry for the test was based on the IEC 60627 which was an international standard for diagnostic X-ray imaging equipment-Characteristics of general purpose and mammographic anti-scatter grids. Results and Discussion: The performance of grids with four inclined shielding material types was compared with that of the parallel type. The grid with completely tapered type the best performance where there were little performance difference according to the degree of inclination. Conclusion: It was shown that the grid of inclined type had better performance than that of parallel one.

Cost-effective Display Driver IC architecture with an external memory is presented. Low-power and high-speed memory interface is proposed to minimize the increase of power consumption and the number of pins. The measured power consumption was less than 45mW with four 1.6Gbps data lanes, 1 clock lane and 1 command lane.

A design and performance test of an antiscattering X-ray grid that is based on photosensitive glass was conducted using MCNP simulation. The simulation was designed in three parts: source, scattere...

Radar is a powerful tool for detecting and tracking airborne targets by day and night. Nowadays, noncooperative target recognition (NCTR) is considered an important subject. NCTR means technologies provide high-resolution target signatures and use them to make some decisions about the type of target that has been detected. Clearly, this function is performed with no cooperation from the target concerned, and it may even not be aware that its signature is being measured for recognition purposes [1]. Jet engine modulation (JEM) [2]–[4] generated by the engine rotation in an aircraft has been used for radar-based NCTR purposes, along with high-resolution range profile and inverse synthetic aperture radar (ISAR) [5]–[7]. Recognition by JEM uses micro-Doppler features induced by a rotating jet engine compressor. The micro-Doppler is characterized by a time-dependent Doppler shift that is different from that caused by the target bulk motion.

One of the major issues in multifunction radar is the allocation of time resources to maximize the ability of the radar. If jet engine modulation (JEM) is analyzed correctly in an insufficient dwell time environment, the remaining time can be allocated for other tasks. This paper presents effective reconstruction of insufficient JEM signals based on compressed sensing (CS) method. The CS method was employed to extract a refined spectrum from insufficient JEM signals. In the process of applying the CS method to JEM signals, we utilized the modified linear programming (LP) standard form of an optimization method. The approach proposed in this paper is significant because it enables reliable estimation in spite of the insufficient JEM signal. Its application to insufficient JEM signals demonstrated that the reconstruction method presented in this paper improved the accuracy of JEM analysis and is expected to be effective from the perspective of radar resource management.

BACKGROUND Anti-scattering grid has been used to improve the image quality. However, applying a commonly used linear or parallel grid would cause image distortion, and focusing grid also requires a precise fabrication technology, which is expensive. OBJECTIVE To investigate and analyze whether using CO2 laser micromachining-based PMMA anti-scattering grid can improve the performance of the grid at a lower cost. Thus, improvement of grid performance would result in improvement of image quality. METHODS The cross-sectional shape of CO2 laser machined PMMA is similar to alphabet 'V'. The performance was characterized by contrast improvement factor (CIF) and Bucky. Four types of grid were tested, which include thin parallel, thick parallel, 'V'-type and 'inverse V'-type of grid. RESULTS For a Bucky factor of 2.1, the CIF of the grid with both the "V" and inverse "V" had a value of 1.53, while the thick and thick parallel types had values of 1.43 and 1.65, respectively. CONCLUSION The 'V' shape grid manufacture by CO2 laser micromachining showed higher CIF than parallel one, which had same shielding material channel width. It was thought that the 'V' shape grid would be replacement to the conventional parallel grid if it is hard to fabricate the high-aspect-ratio grid.

This study presents a real-time measurement-based rapid radiation distribution visualization system for radionuclide recognition, which can quickly scan a contaminated environment. The system combines a portable detector with a digital map and a program for quick data treatment. Radiation information at the measurement location is transferred between a detector and a laptop. It includes environmental and artificial components, specific radionuclides, and total radionuclides. After scanning the area, the radiation distributions are comprehensively displayed in 2D and 3D maps corresponding to the measured area, all in a few tens of seconds. The proposed method was verified using the standard 137Cs and 60Co sources. The gamma radiation distribution of the areas measured in Ulsan city, which included non-destructive testing and radioisotope treatment facilities, hospitals, transportation spots, and residential and commercial areas, showed that Ulsan city has maintained safe levels of radiation. The system performed well. In addition, it was found that this system could detect unexpected hot spots quickly in affected environments.

This study presents a method for extracting the jet engine modulation (JEM) component weakly present in the radar received signal. First, the analytic form of the complicated measured signal is decomposed into intrinsic mode functions (IMFs) via complex empirical mode decomposition (CEMD). Then, the extracted IMFs are combined to reconstruct the JEM component based on the signal eccentricity, which serves as assessing the JEM micro-Doppler contribution to the signal. Applying these techniques to the measured raw signals demonstrate that the proposed extraction method significantly improves the clarity of the JEM analysis and is expected to be useful for enhanced radar target recognition.

A 3-D surveillance radar is a pulsed-doppler radar to provide various target information, such as range, doppler and angle by performing TWS. This paper introduces HW/SW architecture of radar signal processing board to process in real-time using high-speed multiple DSP(Digital Signal Processor) based on COTS. Moreover, we introduced a implemented algorithm consisted of clutter map creation/renewal, FIR(Finite Impulse Response) filter for rejection of zero velocity components, doppler filter, hybrid CFAR and finally presented computational burden of each algorithm by performing operational test using a beacon.

This paper has proposed a multi-channel and wide gain-range baseband circuit blocks for the IEEE 802.15.4g MR-OFDM SUN systems. The proposed baseband circuit blocks consist of two negative-feedback VGAs, an active-RC 5th-order chebyshev low-pass-filter, and a DC-offset cancellation circuit. The proposed baseband circuit blocks provide 1 dB cut-off frequencies of 100 kHz, 200 kHz, 400 kHz, and 600 kHz respectively, and achieve a wide gain-range of +7 dB～+84 dB with 1 dB step. In addition, a DC-offset cancellation circuit has been adopted to mitigate DC-offset problems in direct-conversion receiver. Simulation results show a maximum input differential voltage of 1.5 V pp and noise figure of 42 dB and 37.6 dB at 5 kHz and 500 kHz, respectively. The proposed I-and Q-path baseband circuits have been implemented in 0.18-µm CMOS technology and consume 17 mW from a 1.8 V supply voltage.

In this paper, high resolution range proflle-jet engine mod- ulation (HRRP-JEM) analysis is extended by including quantitative estimation of the jet engine location and extraction of the JEM micro- Doppler component. Based on a parametric model of the range cell data, signal eccentricity was introduced for the purpose of determining the jet engine location. Then, complex empirical mode decomposition (CEMD) was employed to extract the embedded JEM component. The signal eccentricity also served as an auxiliary means of CEMD-based micro-Doppler extraction. Application to the simulated HRRP-JEM data demonstrated that the analysis results described in this paper could be useful for advanced radar target recognition with HRRP- JEM.

HRR(High Resolution Range) profiles show one-dimensional radar images including electromagnetic scattering phenomena of a target. Thus, they are not only robust to noise, but also easily obtainable in a real-time. However, in order to construct a training database for the success of radar target identification, a huge amount of HRR profiles are needed because HRR profiles are highly dependent on the relative angle between the radar and the target. In order to alleviate this difficulty, a database construction method based on the scenarios of target`s movement is proposed. The proposed method is able to provide a reliable target identification performance even with a small amount of training database.

In this paper, we present extraction of vibration components embedded in signatures from rotating propellers. In order to deal with complex-valued signatures, complex empirical mode decomposition (CEMD), an extended version of EMD, is employed to extract the vibration components. With FEKO simulation, we obtain composite signatures induced by both rotation and vibration of the simply modeled propeller for two different cases. Then CEMD is applied to these signatures and the reconstructed vibration components are analyzed in the joint time-frequency domain. The estimated vibration-related parameters showed reasonable agreement with actual motion parameters. This paper shows good possibility of predicting new characteristics from rotating propellers.