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Copyright of Journal of Isotopes is the property of Journal of Isotopes Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A prototype system based on a combination of 4π sensitive gamma imaging and simultaneous localization and mapping (SLAM) was developed to find unknown radiation source(s) rapidly. The system consisted of a spherical visible camera, a three-dimensional light detection and ranging, a CdTe pixel array detector for 4π gamma imaging, a portable battery, and a control laptop personal computer; these were mounted on an unmanned vehicle. In a search area of 16 × 16 m2 with a height of 3 m, the prototype system successfully demonstrated the finding of a 137Cs point source with an activity of 0.67 MBq in the surrounding thin walls. [ABSTRACT FROM AUTHOR]

The radiation shielding properties of lead fluoroborate glasses containing 30 mol% SiO2 have been examined using Phy-X software. The mass attenuation coefficient (MAC) results demonstrated that the tetsed glasses are good attenuator against the low energy radiation, and their attenuation performance diminishes as the energy of the radiation increases. The MAC increases with the addition of PbF2, and the difference in MAC between the glasses with different PbF2 contents is significantly high at lower energy region. At high energy, the difference in MAC between the glasses is small which suggested that as the energy of the photons increases, the MAC for these glasses tend to converge. The linear attenuation coefficient (LAC) for the glasses is investigated and we found that the LAC for the glass with 49 mol% of PbF2 is 58% bigger than that of the glass with 21 mol%. We investigated the average half value layer ( HVL ¯ ) for the tested glasses when exposed to 137Cs and 60Co and the results showed that the values of HVL ¯ for 60Co are about double those for 137Cs for all glasses, which suggests that the energies emitted by 60Co in general penetrate the glass sample more deeply in comparison with the photons emitted by 137Cs. The mean free path (MFP) of the glasses against the density shows the desirable properties of PbF2, as the MFP values decrease when the density increases. [ABSTRACT FROM AUTHOR]

In this paper, we focus on the detection and localization of radioactive sources by exploiting supervised machine learning. Machine learning is utilized in a wide variety of applications due to its effectiveness in prediction and autonomous decision-making. However, applying machine learning would only be effective when representative features for the application can be acquired, through which learning algorithms can be trained. Hence, first, we present a feature extraction technique for radioactive source localization, and then propose a parameter estimation method via machine learning. A distributed sensor network is employed to assist in estimating the radioactive source's location and intensity. We propose a feature extraction method that evaluates a feature vector using the reading and position of each sensor located in a region where a radiation source is detected. The feature extraction is based on a data fusion process, where a single feature value is provided to represent both the reading value and position coordinates corresponding to a given sensor. After the feature extraction, we apply the decision tree machine learning method for regression to localize a radioactive source. To examine the effectiveness of the proposed work, a performance comparison is carried out with recent existing methods in terms of the estimation accuracy and the execution time. Experimental results show that the proposed algorithm provides accurate source intensity estimation and achieves a good compromise between localization accuracy and execution time. [ABSTRACT FROM AUTHOR]

Nickel-63 radioactive sources used in micro nuclear batteries require high surface emissivity, thin coating and small substrate. The method for the preparation of nickel-63 radioactive sources by direct and constant current electrodeposition was established by using nickel-63 solution with small volume, high specific activity and low Ni2+ concentration as electrodeposition liquid.Using this method, under the conditions of copper substrate, Ni2+ concentration with 1 g/L, electrodeposition pH with 3.5-4.5 and sulphamic acid concentration with 0.1 g/L, the electrodeposition efficiency can reach to 95.8% after 1 h . The coating is compact and bright with the thickness from 0.3 μm to 1.6 μm. The surface emissivity of the prepared nickel-63 radio-source film is up to 2.40×107 s-1·(2πSr)-1 while the activity is up to 1.89×109 Bq, which can meet the application requirements of micro nuclear batteries. At the same time, by recovering the residual electrodeposition solution and adjusting its composition, the reuse of electrodeposition liquid is realized, reducing the waste of nickel-63 raw material.

In recent years, with the current strong support for the application of civil nuclear technology, Chinese radioisotope products industry has ushered in unprecedented opportunities and development. However, the rapid expansion of the industry also brings the problem of market size and the development of the industry technical standard system mismatch. In view of the lack of research on technical standard system construction of radioactive isotope products industry in China, this paper discusses the current situation and existing problems in standard system construction of radioactive drugs and radioactive sources industry respectively from the market scale and standard system status. At present, the existing standard system framework can basically meet the quality control of listed products, but in the field of radiopharmaceutical, there is a lack of analytical testing technology, nuclide and quality control key equipment verification standards. In the field of radioactive sources, there are problems with outdated standards, low participation in the formulation of international standards and small coverage of standards exist. Aiming at these problems, upgrading and improving the radioactive isotope products standard system systematically, complementing the existing standard system of blank area and weak area, completing the standard cohesion at various levels shall strengthen the standard stable cross, promoting widespread promotion and application of standards in the industry and enhancing the level of standard internationalization and so on were put forward, which hope to provide a reference for the construction of the technical standard system for radioisotope products.

This experimental investigation focuses on the gamma-ray interaction parameters and the buildup factor in lanthanide compounds (CeO 2 , Ce(SO 4) 2 , Dy 2 (SO 4) 3 , C 3 O 9 Sm 2 , C 3 Gd 2 O 9 , Pr 2 O 3). These compounds were exposed to weak radioactive gamma sources with energies of 356, 511, 662, 1173, 1275, and 1332 keV by adopting narrow and broad beam geometry experimental arrangements. The incident and transmitted radiation intensities were measured using a NaI (Tl) detector. Experimentally measured values of mass attenuation coefficient and effective atomic number of lanthanide compounds were found to be in precise agreement with theoretical values obtained from NIST XCOM and Direct-Z eff database respectively. Additionally, the experimentally determined buildup factor values were compared with energy absorption buildup factor (EABF) and exposure buildup factor (EBF) values obtained from Phy-X/PSD software, providing insights into the gamma-ray penetration depth in terms of mean free path (MFP). At 356 keV, the EABF analysis showed that most compounds had a penetration depth of around 8 mean free paths. In contrast, the EBF analysis indicated penetration depths exceeding 10 mean free paths for all compounds except Ce (SO 4) 2. This new approach holds immense potential for transformative advancements in medical diagnostics, therapy, and the development of innovative technologies in nuclear sciences. • The gamma-ray interaction parameters and buildup factor of lanthanide compounds were experimentally determined. • The comparison of experimental buildup factor values with EABF and EBF provides insight into gamma-ray penetration depth (mfp). • The EABF showed that most compounds had a penetration depth of around 8 mean free path except Ce (SO 4) 2 at 356 keV. • The EBF indicated penetration depths exceeding 10 mean free path for all compounds except Ce (SO 4) 2 at 356 keV. [ABSTRACT FROM AUTHOR]

A new method for radionuclide labeling by the use of graphene thin films was previously presented. In this work, a comparison among low energy radioactive sources supported on carbonaceous thin films on polyvinyl chloride-polyvinyl acetate copolymer (VYNS), based on the use of aqueous solutions is investigated as a feasible alternative to the traditional metallized films avoiding the downside of the loss of many broken films. Graphene-based materials were prepared by both oxidation-exfoliation-reduction and direct graphite exfoliation routes. In addition, multiwalled carbon nanotubes (MWCNTs) thin films were also evaluated. The stability of both carbonaceous materials aqueous dispersions were studied by using ionic and non-ionic surfactants. Solid carbon-based materials were characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) whereas the colloidal nature of the aqueous dispersions was verified by the measurement of Tyndall effect and the morphology of thin films was evaluated by Scanning Electron Microscopy (SEM). 55Fe solutions were used to prepare the radioactive sources on the thin films by quantitative drop deposition. The quality of spectra was measured in a pressurized proportional counter. Results showed a resolution higher than 0.9 keV for all the tested sources. However, MWCNT-based along with non-surfactant sources presented non-adequate escape peaks and low energy tails. On the contrary, all the graphene-based sources prepared using surfactants to stabilize aqueous solutions presented an energy resolution comparable to that of the metallized source while offering notable advantages in terms of cost efficiency and reliability of the as-prepared supports. • Carbon-based thin films have been prepared as conductive support for radionuclide labeling. • Thin films were prepared by spin coating from aqueous solutions of rGO, deG and MWCNTs on VYNS films. • Sources prepared with graphene-based materials show spectra comparable to the metallized sources. [ABSTRACT FROM AUTHOR]

For the problem of searching radioactive sources in a certain area, a search method combining Tsallis divergence strategy with a particle filtering algorithm is proposed. The method this paper proposes for searching for radioactive sources is carried out by using a mobile platform equipped with a NaI(Tl) scintillator detector. The estimation model of the parameters of the radioactive source is constructed and is based on the inverse square law and the fact that the count values of the NaI(Tl) detector in nuclear decay processes obeys the Poisson distribution. The Tsallis divergence strategy is used as a reward function to control the movement of the platform. The posterior distribution of the parameters of the radioactive source is continuously and iteratively updated by using the particle filtering algorithm. The results of Monte Carlo simulations and practical experiments verify the effectiveness of the algorithm. [ABSTRACT FROM AUTHOR]

Radiation measurement is vital in radiation physics as its possible hazardous effect on human health should be known. Although radiation may be measured using different kinds of detector types, the NaI(Tl) crystal is one of the most commonly used detector types. This is due to its advantages such as low cost, resistance to thermal effects, and weather conditions. In the use of a gamma spectrometer system, the performance of the detector system is very important in order to determine absolute radiation values as the variation of measurement may affect health due to the radiation. In this work, the performance of 3″ × 3″ NaI(Tl) detector has been determined by obtaining some parameters such as response function, resolution, energy spectrum, the figure of merit. Those parameters have been measured using 22Na, 137Cs, and 60Co radioactive sources. The system was also modeled by using FLUKA code. [ABSTRACT FROM AUTHOR]

Copyright of Nuclear Safety is the property of Nuclear & Radiation Safety Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Physical Protection System is based on the five basic security functions (deterrence, detection, delay, response, and security management), all of which are required to protect a radiological facility against malicious acts. Evaluating the performance of PPS, including the security procedures and their implementation, is a way to engage with staff, raise their awareness on the importance of security. This article presents a new effectiveness evaluation model of the PPS administrative structure through qualitative analysis, which is appropriate for the security management evaluation of low-consequence radiological facilities, to protect them against malicious acts. This model was developed in five stages to obtain a structured process for conducting the PPS administrative structure evaluation, based on the security management function, consisting of 11 topics and 89 qualitative questions to determine the Relative Robustness Index of this function. Model topics were classified with distinct relative weights based on their relevance to the PPS. For testing and validation of the model, 6 industrial radiological facilities classified in different security levels were selected. The results showed that the self-assessment model proposed in this article is viable, considering its simplicity, promptness, and applicability in identifying and analyzing the strengths and weaknesses of the PPS security management function. The new model made possible the effectiveness evaluation of the PPS globally and punctually, making it possible to identify which topics of security management are above, or below, the minimum required for the current security level.

• The collaborative search of radioactive sources by multiple robots is realized through the particle filtering method and the Gaussian distribution parameter fusion method based on cognitive consistency. • A distributed multi-robot cooperative navigation strategy is implemented through an Infotaxis II reward strategy based on deviation angle and distance. • The calculation of the robot's feasible decision set relies on the kinematic model and design constraints of the mobile robot. • Enhancing cognitive consistency among multiple robots by fusing Gaussian distribution parameters with cognitive difference variables. Accidental loss of radioactive sources can pose a significant threat to human health and the ecological environment. This paper proposes a distributed collaborative decision algorithm for multi-robot radioactive source search to solve this problem. The algorithm utilizes a Gaussian parameter fusion method based on cognitive consistency to estimate the posterior probability distribution of source parameters within a Bayesian framework. Also, the algorithm enhances the cognitive consistency of robots through the fusion of shared Gaussian distribution parameters and cognitive difference variables. Each robot calculates a reward function for its next action based on the deviation angle and distance. In addition, the proposed algorithm uses a distributed collaborative search strategy to guide the robot's search through the robot's behavioral decisions and behavioral decisions from neighboring robots. Experimental results show that the algorithm achieves a mean search time of only 1.74s and a 100% search success rate. Therefore, the algorithm not only guarantees accuracy but also shortens the search time and reduces the risk of losing radioactive sources. [ABSTRACT FROM AUTHOR]

In 1979, the research team at SRI International conducted a single random number generator (RNG) experiment. The goal was to replicate and extend the findings from a substantial literature in several ways. Sequential analysis was used to provide a two-fold increase in statistical sensitivity; two fundamentally different physical random sources were used: β-decay of 147Pm and electronic noise from a well-understood silicon noise diode. Substantial engineering effort isolated these sources from environmental effects, and a quantum mechanical model accurately described the known properties of the electronic noise diode. An a priori definition of a successful outcome was more stringent than in the usual study; two participants out of seven must produce independently significant evidence of an effect. Seven participants who were screened for PK ability from a population of 17 candidates took part in the formal study. Two produced independently significant results (p ≤ 0.021 and p ≤ 0.039, respectively). While these results were consistent with those in the micro-PK literature, we report definitive evidence of no PK effects at all. Rather, the result appears to arise because of informational psi on part of the participant. [ABSTRACT FROM AUTHOR]

We present a detection problem where several spatially distributed sensors observe Poisson signals emitted from a single radioactive source of unknown position. The measurements at each sensor are modeled by independent inhomogeneous Poisson processes. A method based on Bayesian change-point estimation is proposed to identify the location of the source's coordinates. The asymptotic behavior of the Bayesian estimator is studied. In particular, the consistency and the asymptotic efficiency of the estimator are analyzed. The limit distribution and the convergence of the moments are also described. The similar statistical model could be used in GPS localization problems. [ABSTRACT FROM AUTHOR]

The K X-ray fluorescence (XRF) parameters, which are fluorescence cross-section, vacancy transfer probabilities and fluorescence yield, of some fourth-period elements were investigated in an external magnetic field (8000 Gauss). In order to determine the fluorescence parameters, the samples were irritated with 59.54 keV gamma rays from a 241-Americium radioactive source and the rays emitted from the samples were counted in a system consisting of a silicon – lithium drifted detector, multichannel analyzer, magnetic field implementer, and a suitable computer program. The results were studied theoretically and experimentally using the data that were obtained. It was determined that the experimental results were compatible with the theoretical results for measurements without a magnetic field and K XRF parameters changed with the magnetic field. [ABSTRACT FROM AUTHOR]

Radioactive 233U alpha recoil sources are being considered for the production of a thorium ion source to study the low-energy isomer in 229Th with high-resolution collinear laser spectroscopy at the IGISOL facility of the University of Jyväskylä. In this work two different 233U sources have been characterized via alpha and gamma spectroscopy of the decay radiation obtained directly from the sources and from alpha-recoils embedded in implantation foils. These measurements revealed rather low 229Th recoil efficiencies of only a few percent. Although the low efficiency of one of the two sources can be attributed to its inherent thickness, the low recoil efficiency of the second, thinner source, was unexpected. Rutherford backscattering spectrometry (RBS) was performed to investigate the elemental composition as a function of depth revealing a contamination layer on top of the thin source. The combination of spectroscopic methods proves to be a useful approach in the assessment of alpha recoil source performance in general. [ABSTRACT FROM AUTHOR]

In order to obtain the relationship between energy and channel, the suitable radionuclides are chosen to calibrate. The result shows a goodness of fitting. The Monte Carlo simulation about the detection efficiency of the high purity germanium (HPGe) gamma-spectrometry system was performed. The distance between radioactive source and the end cap is set 15, 20, 25 and 50 cm, respectively. The maximum absolute efficiency locates at around 80 keV. It can be concluded that the absolute efficiency is declining accompany with the increasing of distance. In the end, at the distance of 25 cm, the authors changed thickness of the dead layer and the source distribution to calculate. The maximum absolute efficiency is 8.56E−03, and the relative deviation is 0.0011. Then it was compared with the experimental result provided with the manufacturer. The result of simulation shows a certain agreement with the experimental results. This work will be helpful for calculating the efficiency of HPGe gamma-spectrometry. [ABSTRACT FROM AUTHOR]

Accurate detection of low-level radioactivity is critical in decommissioning. However, commercial sources used for calibration lack representativeness due to their flat surface. The objective of this work is to produce flexible and large area surface sources for alpha and beta emitters by functionalising aluminium foil. Functionalisation strategies were developed to provide these sources. The manganese oxide coated sample shows the highest fixation yield for 241Am: (70.0 ± 2.6)% and conforms to ISO 8769 for uniformity (92%). • Binding radionuclides chemically to a surface limits radiation self-absorption. • Flexible surface sources of Eu-152 and Am-241 were produced using aluminium foils. • Their surface activity is traceable, from 2 to 25 Bq. cm−2, and can be adjusted. • Their uniformity can reach 92% and conforms to ISO 8769. [ABSTRACT FROM AUTHOR]

In this paper it is shown experimentally that single alpha particles emitted from radioactive sources can produce Single Event Burnout failures in silicon and silicon carbide power devices at blocking bias levels below 90 % of the breakdown voltage. Silicon carbide devices have been shown to be more susceptible than Si devices because of the enhanced strength of the electric field and of the thinner depletion layer. TCAD simulation is used to model the initiation of the streamers and the subsequent thermal runaway. [ABSTRACT FROM AUTHOR]

Nuclear logging is one of major areas of logging development. This paper presents an empirical investigation to bring the drilling and completion of wells from an ill-defined art to a refined sci-ence by using radioactive source to “look and measure” such as formation type, formation dip, porosity, fluid type and numerous other important factors. The initial nuclear logging tools rec-ords the radiation emitted by formation as they were crossed by boreholes. Gamma radiation is used in well logging as it is powerful enough to penetrate the formation and steel casing. The ra-dioactive source is reusable so that after engineer finished the job the radioactive source is sent back to bunker. In this case inventory level of radioactive source is relatively high compared with monthly movement and the company must spend large amount of cost just for inventory. After calculating and averaging the monthly movement in 2014 and 2015, we detected a big pos-sibility to cut the inventory level to reduce the inventory cost.

In order to obtain the relationship between energy and channel, the suitable radionuclides are chosen to calibrate. The result shows a goodness of fitting. The Monte Carlo simulation about the detection efficiency of the high purity germanium (HPGe) gamma-spectrometry system was performed. The distance between radioactive source and the end cap is set 15, 20, 25 and 50 cm, respectively. The maximum absolute efficiency locates at around 80 keV. It can be concluded that the absolute efficiency is declining accompany with the increasing of distance. In the end, at the distance of 25 cm, the authors changed thickness of the dead layer and the source distribution to calculate. The maximum absolute efficiency is 8.56E−03, and the relative deviation is 0.0011. Then it was compared with the experimental result provided with the manufacturer. The result of simulation shows a certain agreement with the experimental results. This work will be helpful for calculating the efficiency of HPGe gamma-spectrometry.

Copyright of Nuclear Safety is the property of Nuclear & Radiation Safety Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract In this study, we manufactured silicon PIN photodiodes coupled with a scintillator for X-ray detection in cargo inspections. The classification of photodiodes is made based on their depletion characteristics into two categories: fully depleted (FD) sensor and non-fully depleted (NFD) sensor. We manufactured the photodiodes on an n-type silicon wafer of diameter 6-in., a high resistivity (> 5 k Ω cm) and low resistivity (> 100 Ω cm) for the FD and NFD sensors, respectively. The light entrance windows for the scintillation light were designed on the ohmic and junction sides of the FD and NFD sensors, respectively. Since the NFD sensor is not fully depleted, it can be operated at a lower bias voltage, and therefore has a lower leakage current. We measured the electrical characteristics, quantum efficiencies, and energy resolutions of the fabricated FD and NFD photodiodes coupled with or without a CsI(Tl) crystal using alpha particles from a 241Am radioactive source. We present results of the comparison between the FD and NFD sensors. Highlights • Fully depleted and non-fully depleted photodiodes were designed and fabricated. • The FD sensor has the advantage of a large active volume and low capacitance. • The NFD sensor has a lower power consumption and is cost effective. • The fabricated photodiodes can be used for x-ray detector in cargo system. • Electrical characteristics, quantum efficiencies and energy resolutions are measured. [ABSTRACT FROM AUTHOR]

This work proposes a solution to identify the number of sources of radiation, as well as their respective intensities and locations based on data acquired by Global Positioning System (GPS) receivers and affordable radiological sensors, such as Geiger-M¨uller counters (GMC). An optimization algorithm is required to minimize the estimation error in terms of location, intensity and number of sources of radiation given all the intensity measurements acquired in different locations, taking into account the sensors’ models, background radiation intensity values and noise. Experimental results were achieved in a laboratory with controlled sources of radiation. The solution was also tested with real data gathered by a GMC connected to a mobile phone with a software application developed by the authors to synchronize the sensor readings with GPS data. The sensor and the mobile phone are attached to a quadcopter flying over the scenario with sources of radiation.