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The in-situ characterisation of strontium-90 contamination of groundwater at nuclear decommissioning sites would represent a novel and cost-saving technology for the nuclear industry. However, beta particles are emitted over a continuous spectrum and it is difficult identify radionuclides due to the overlap of their spectra and the lack of characteristic features. This can be resolved by using predictive modelling to perform a maximum-likelihood estimation of the radionuclides present in a beta spectrum obtained with a semiconductor detector. This is achieved using a linear least squares linear regression and relating experimental data with simulated detector response data. In this case, by simulating a groundwater borehole scenario and the deployment of a cadmium telluride detector within it, it is demonstrated that it is possible to identify the presence of
Graeme Turkington; Kelum A. A. Gamage; James Graham. The Simulation of In-Situ Groundwater Detector Response as a Means of Identifying Beta Emitting Radionuclides by Linear Regression Analysis. Sensors 2021, 21, 5732 .
AMA StyleGraeme Turkington, Kelum A. A. Gamage, James Graham. The Simulation of In-Situ Groundwater Detector Response as a Means of Identifying Beta Emitting Radionuclides by Linear Regression Analysis. Sensors. 2021; 21 (17):5732.
Chicago/Turabian StyleGraeme Turkington; Kelum A. A. Gamage; James Graham. 2021. "The Simulation of In-Situ Groundwater Detector Response as a Means of Identifying Beta Emitting Radionuclides by Linear Regression Analysis." Sensors 21, no. 17: 5732.
Many higher educational institutes are forced to the online mode of lecture delivery without fully understanding students’ perspectives of remote study during COVID-19, and the resource limitations of students to engage successfully in remote learning. The present study aimed to understand this gap and the students’ perspective. We collected and analysed the devices, which used by the students to connect to remote learning in a developing country. It was found that the majority of students are dependent on the laptop-smartphone combination to engage in remote learning, particularly the students in rural areas. The results highlighted the importance of smartphones in the online learning experience, considering their affordability, relatively long battery life, inbuilt internet capabilities, and portability. Although students indicated their willingness for remote learning, they clearly recognised the need for face-to-face teaching return to avoid some of the challenges and disadvantages they face as a part of remote learning.
Eranda Perera; Kelum Gamage. Learning Remotely during a Pandemic: Are Students in a Developing Country Fully Equipped with Tools for Swift Changes? Sustainability 2021, 13, 8635 .
AMA StyleEranda Perera, Kelum Gamage. Learning Remotely during a Pandemic: Are Students in a Developing Country Fully Equipped with Tools for Swift Changes? Sustainability. 2021; 13 (15):8635.
Chicago/Turabian StyleEranda Perera; Kelum Gamage. 2021. "Learning Remotely during a Pandemic: Are Students in a Developing Country Fully Equipped with Tools for Swift Changes?" Sustainability 13, no. 15: 8635.
The global higher education sector has been greatly affected by the COVID-19 pandemic, and the mode of delivery has transformed into a blended learning mode of delivery or fully remote mode. Online delivery significantly demands reliable and stable internet access and technology, at both the lecturer’s and students’ ends. This paper investigates the challenges and barriers to accessibility of technologies used for remote delivery of learning and teaching. The paper also investigates key digital skills students need to help them develop and enhance their technology literacy. A survey was also conducted among 555 university undergraduate students to identify their choice of device to connect to remote learning during the transition to online learning. It was revealed that students used laptops and smartphones considerably and least relied on desktop computers. The results indicate the significance of a device’s portability, built-in network hardware and cost. Further, it identifies the impacts of accessibility of educational technologies on students’ learning experience.
Kelum Gamage; Eranda Perera. Undergraduate Students’ Device Preferences in the Transition to Online Learning. Social Sciences 2021, 10, 288 .
AMA StyleKelum Gamage, Eranda Perera. Undergraduate Students’ Device Preferences in the Transition to Online Learning. Social Sciences. 2021; 10 (8):288.
Chicago/Turabian StyleKelum Gamage; Eranda Perera. 2021. "Undergraduate Students’ Device Preferences in the Transition to Online Learning." Social Sciences 10, no. 8: 288.
Personal values play a significant role when adopting learning approaches by individuals during their studies. Particularly in higher education, these values significantly influence the character that individuals play within their learning community and ultimately influence their academic achievements. The purpose of this paper is to investigate personal values in their choice of learning approaches and, subsequently, how it impacts one’s academic achievements. It also investigates the importance of developing an individual’s personal values as a part of their wider studies, while aligning these with graduate attributes and balancing them with knowledge and skills, to produce successful graduates in a society.
Kelum Gamage; D. Dehideniya; Sakunthala Ekanayake. The Role of Personal Values in Learning Approaches and Student Achievements. Behavioral Sciences 2021, 11, 102 .
AMA StyleKelum Gamage, D. Dehideniya, Sakunthala Ekanayake. The Role of Personal Values in Learning Approaches and Student Achievements. Behavioral Sciences. 2021; 11 (7):102.
Chicago/Turabian StyleKelum Gamage; D. Dehideniya; Sakunthala Ekanayake. 2021. "The Role of Personal Values in Learning Approaches and Student Achievements." Behavioral Sciences 11, no. 7: 102.
This paper presents a design of an in-situ detector for monitoring strontium 90 activity in groundwater at nuclear decommissioning sites. Current techniques for monitoring strontium 90 activity are lab-based and are time consuming, expensive and produce secondary waste. To alleviate these problems, a proof-of-concept detector has been developed which will be deployed in-situ, directly into groundwater boreholes. A compact detector was designed, housed in a waterproof casing and its initial performance as a strontium 90 detector in water was examined. A 10 x 10 x 1 mm cadmium telluride detector was paired with a appropriate charge sensitive amplifiers and readout systems to make a 118 x 83 x 40 mm sensor which was submersed in water. A 35.79 MBq collimated strontium 90 source was used to determine that the sensor was capable of counting beta particles from a range of 49.50 mm in water. The detector was held at a reverse bias of 80 V for 290 min, the average counts observed in 5 min intervals went from 1.32×106±1.14×103 to 1.28×106±1.13×103. However, the results presented have established a viable proof-of-concept for an in-situ detector for strontium 90 assay in groundwater.
Graeme Turkington; Kelum A.A. Gamage; James Graham. Characterisation and suitability of a CdTe detector for strontium 90 assay in groundwater. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 2021, 997, 165155 .
AMA StyleGraeme Turkington, Kelum A.A. Gamage, James Graham. Characterisation and suitability of a CdTe detector for strontium 90 assay in groundwater. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2021; 997 ():165155.
Chicago/Turabian StyleGraeme Turkington; Kelum A.A. Gamage; James Graham. 2021. "Characterisation and suitability of a CdTe detector for strontium 90 assay in groundwater." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 997, no. : 165155.
This paper examines the potential deployment of a 10 mm × 10 mm × 1 mm cadmium telluride detector for strontium-90 measurement in groundwater boreholes at nuclear decommissioning sites. Geant4 simulation was used to model the deployment of the detector in a borehole monitoring contaminated groundwater. It was found that the detector was sensitive to strontium-90, yttrium-90, caesium-137, and potassium-40 decay, some of the significant beta emitters found at Sellafield. However, the device showed no sensitivity to carbon-14 decay, due to the inability of the weak beta emission to penetrate both the groundwater and the detector shielding. The limit of detection for such a sensor when looking at solely strontium-90 decay was calculated as 323 BqL − 1 after a 1-h measurement and 66 BqL − 1 after a 24-h measurement. A gallium-arsenide (GaAs) sensor with twice the surface area, but 0.3% of the thickness was modelled for comparison. Using this sensor, sensitivity was increased, such that the limit of detection for strontium-90 was 91 BqL − 1 after 1 h and 18 BqL − 1 after 24 h. However, this sensor sacrifices the potential to identify the present radionuclides by their end-point energy. Additionally, the feasibility of using flexible detectors based on solar cell designs to maximise the surface area of detectors has been modelled.
Graeme Turkington; Kelum Gamage; James Graham. The Simulated Characterization and Suitability of Semiconductor Detectors for Strontium 90 Assay in Groundwater. Sensors 2021, 21, 984 .
AMA StyleGraeme Turkington, Kelum Gamage, James Graham. The Simulated Characterization and Suitability of Semiconductor Detectors for Strontium 90 Assay in Groundwater. Sensors. 2021; 21 (3):984.
Chicago/Turabian StyleGraeme Turkington; Kelum Gamage; James Graham. 2021. "The Simulated Characterization and Suitability of Semiconductor Detectors for Strontium 90 Assay in Groundwater." Sensors 21, no. 3: 984.
COVID-19, caused by a member of the coronavirus family of viruses, has spread to most countries around the world since it was first recorded in humans in China in late 2019. Closing universities and cancelling all face-to-face activities have become a COVID-19 inevitable reality in many parts of the world. Its impact on university programs, particularly to maintain academic standards and quality assurance procedures, has become significantly more challenging and complex. New ways of working digitally, to minimize disruption to daily operations, have also led to enormous anxiety and uncertainty within the student population, and meeting students’ expectations has also become significantly more difficult. This paper reviews actions taken by universities to safeguard high academic standards and quality assurance procedures during this time and appraise the challenges and impacts on students’ academic performance.
Kelum Gamage; Roshan Pradeep; Vesna Najdanovic-Visak; Nanda Gunawardhana. Academic Standards and Quality Assurance: The Impact of COVID-19 on University Degree Programs. Sustainability 2020, 12, 10032 .
AMA StyleKelum Gamage, Roshan Pradeep, Vesna Najdanovic-Visak, Nanda Gunawardhana. Academic Standards and Quality Assurance: The Impact of COVID-19 on University Degree Programs. Sustainability. 2020; 12 (23):10032.
Chicago/Turabian StyleKelum Gamage; Roshan Pradeep; Vesna Najdanovic-Visak; Nanda Gunawardhana. 2020. "Academic Standards and Quality Assurance: The Impact of COVID-19 on University Degree Programs." Sustainability 12, no. 23: 10032.
Globally, the number of COVID-19 cases continues to rise daily despite strict measures being adopted by many countries. Consequently, universities closed down to minimise the face-to-face contacts, and the majority of the universities are now conducting degree programmes through online delivery. Remote online delivery and assessment are novel experiences for many universities, which presents many challenges, particularly when safeguarding academic integrity. For example, invigilated assessments, often considered as more secure, are not an option given the current situation and detecting any cheating would be significantly challenging. This paper reviews assessment security in the digital domain and critically evaluates the practices from different universities in safeguarding academic integrity, including associated challenges.
Kelum A.A. Gamage; Erandika K. De Silva; Nanda Gunawardhana. Online Delivery and Assessment during COVID-19: Safeguarding Academic Integrity. Education Sciences 2020, 10, 301 .
AMA StyleKelum A.A. Gamage, Erandika K. De Silva, Nanda Gunawardhana. Online Delivery and Assessment during COVID-19: Safeguarding Academic Integrity. Education Sciences. 2020; 10 (11):301.
Chicago/Turabian StyleKelum A.A. Gamage; Erandika K. De Silva; Nanda Gunawardhana. 2020. "Online Delivery and Assessment during COVID-19: Safeguarding Academic Integrity." Education Sciences 10, no. 11: 301.
A great number of universities worldwide are having their education interrupted, partially or fully, by the spread of the novel coronavirus (COVID-19). Consequently, an increasing number of universities have taken the steps necessary to transform their teaching, including laboratory workshops into an online or blended mode of delivery. Irrespective of the measures taken, universities must continue to maintain their high academic standards and provide a high-quality student experience as required for delivery of learning outcomes associated with each degree programme. This has created a challenge across the higher education landscape, where academics had to switch to remote teaching and different approaches to achieving laboratory delivery. As a result, students have not been receiving face-to-face teaching, and access to laboratory facilities has been limited or nearly impossible. This paper reviews numerous approaches taken by universities to deliver teaching and laboratory practices remotely, in consideration of the COVID-19 pandemic, whilst also considering the potential impacts on the student learning experience. This review is primarily focused on the fields of engineering, science and technology, based on published literature including books, reviewing web-based provision of selected universities, institutional and national policy documents.
Kelum A. A. Gamage; Dilani I. Wijesuriya; Sakunthala Y. Ekanayake; Allan E. W. Rennie; Chris G. Lambert; Nanda Gunawardhana. Online Delivery of Teaching and Laboratory Practices: Continuity of University Programmes during COVID-19 Pandemic. Education Sciences 2020, 10, 291 .
AMA StyleKelum A. A. Gamage, Dilani I. Wijesuriya, Sakunthala Y. Ekanayake, Allan E. W. Rennie, Chris G. Lambert, Nanda Gunawardhana. Online Delivery of Teaching and Laboratory Practices: Continuity of University Programmes during COVID-19 Pandemic. Education Sciences. 2020; 10 (10):291.
Chicago/Turabian StyleKelum A. A. Gamage; Dilani I. Wijesuriya; Sakunthala Y. Ekanayake; Allan E. W. Rennie; Chris G. Lambert; Nanda Gunawardhana. 2020. "Online Delivery of Teaching and Laboratory Practices: Continuity of University Programmes during COVID-19 Pandemic." Education Sciences 10, no. 10: 291.
It has been established that the UVTRON flame sensor (Hamamatsu) can detect alpha-induced radioluminescence, but that the presence of gamma and beta radiation both interfere with this detection. A UVTRON was placed inside a tungsten collimator and exposed to a range of radioisotopes, 210Po, 241Am, 137Cs, 90Sr and 60Co, to investigate the effect of shielding the UVTRON. The collimator is a cylinder with a hole in the curved wall to allow light and particles to access the interior, without providing a direct shine path to the UVTRON sensor. Ultraviolet C (wavelength 180–280 nm) radioluminescence is reflected onto the UVTRON sensor using a UVC reflecting mirror. It was found that the collimator does not affect the low background count of the UVTRON, but that it does greatly reduce the UVC signal reaching the UVTRON from an alpha source. For example, the collimator reduced the signal by 94% at 60 mm, and 78% at 120 mm, where the signals were still far greater than the background (88 and 84 times background respectively). Beta particles entering the collimator, although not directly impacting on the UVTRON, do increase the count, likely due to bremsstrahlung radiation. The collimator attenuates gamma radiation dependent on the gamma energy, but as expected, does not block it. When using more than one source, the count is cumulative and therefore it may be possible to determine the presence of UVC radioluminescence through subtraction of the gamma and beta element of the signal. The results and findings of the experiments carried out are presented herewithin.
Kelum A.A. Gamage; Anita J. Crompton; Alex Jenkins; Steven Bell; Divyesh Trivedi. Performance characteristics of a tungsten collimator and UVTRON flame sensor in the detection of alpha-induced radioluminescence. Radiation Physics and Chemistry 2020, 177, 109197 .
AMA StyleKelum A.A. Gamage, Anita J. Crompton, Alex Jenkins, Steven Bell, Divyesh Trivedi. Performance characteristics of a tungsten collimator and UVTRON flame sensor in the detection of alpha-induced radioluminescence. Radiation Physics and Chemistry. 2020; 177 ():109197.
Chicago/Turabian StyleKelum A.A. Gamage; Anita J. Crompton; Alex Jenkins; Steven Bell; Divyesh Trivedi. 2020. "Performance characteristics of a tungsten collimator and UVTRON flame sensor in the detection of alpha-induced radioluminescence." Radiation Physics and Chemistry 177, no. : 109197.
Today’s electricity grid is rapidly evolving, with increased penetration of renewable energy sources (RES). Conventional Optimal Power Flow (OPF) has non-linear constraints that make it a highly non-linear, non-convex optimisation problem. This complex problem escalates further with the integration of RES, which are generally intermittent in nature. In this article, an optimal power flow model combines three types of energy resources, including conventional thermal power generators, solar photovoltaic generators (SPGs) and wind power generators (WPGs). Uncertain power outputs from SPGs and WPGs are forecasted with the help of lognormal and Weibull probability distribution functions, respectively. The over and underestimation output power of RES are considered in the objective function i.e. as a reserve and penalty cost, respectively. Furthermore, to reduce carbon emissions, a carbon tax is imposed while formulating the objective function. A grey wolf optimisation technique (GWO) is employed to achieve optimisation in modified IEEE-30 and IEEE-57 bus test systems to demonstrate its feasibility. Hence, novel contributions of this work include the new objective functions and associated framework for optimising generation cost while considering RES; and, secondly, computational efficiency is improved by the use of GWO to address the non-convex OPF problem. To investigate the effectiveness of the proposed GWObased approach, it is compared in simulation to five other nature-inspired global optimisation algorithms and two well-established hybrid algorithms. For the simulation scenarios considered in this article, the GWO outperforms the other algorithms in terms of total cost minimisation and convergence time reduction.
Inam Ullah Khan; Nadeem Javaid; Kelum A. A. Gamage; C. James Taylor; Sobia Baig; Xiandong Ma. Heuristic Algorithm Based Optimal Power Flow Model Incorporating Stochastic Renewable Energy Sources. IEEE Access 2020, 8, 148622 -148643.
AMA StyleInam Ullah Khan, Nadeem Javaid, Kelum A. A. Gamage, C. James Taylor, Sobia Baig, Xiandong Ma. Heuristic Algorithm Based Optimal Power Flow Model Incorporating Stochastic Renewable Energy Sources. IEEE Access. 2020; 8 (99):148622-148643.
Chicago/Turabian StyleInam Ullah Khan; Nadeem Javaid; Kelum A. A. Gamage; C. James Taylor; Sobia Baig; Xiandong Ma. 2020. "Heuristic Algorithm Based Optimal Power Flow Model Incorporating Stochastic Renewable Energy Sources." IEEE Access 8, no. 99: 148622-148643.
The final year design project is one of the most important components of any undergraduate engineering program. Fair and efficient project allocation procedures can be vital in ensuring a great student experience and exceptional learning out of these projects, which then could contribute in shaping students’ future prospects. In this paper, we review a wide range of project allocation strategies used in various universities at undergraduate levels. We then focus on the project allocations in transnational education (TNE) contexts, which inherit additional allocation challenges. We highlight these challenges and provide recommendations to solve them. We present and compare project allocation strategies adopted at two of the largest TNE programs in China. We also present the factors that influence the project allocations, particularly regarding TNE provisions. Finally, we describe the challenges associated with the project allocations in the TNE scenario, along with proposing some feasible solutions to address these challenges.
Sajjad Hussain; Kelum A. A. Gamage; Hasanuzzaman Sagor; Faisal Tariq; Ling Ma; Muhammad Ali Imran; Ma. A Systematic Review of Project Allocation Methods in Undergraduate Transnational Engineering Education. Education Sciences 2019, 9, 258 .
AMA StyleSajjad Hussain, Kelum A. A. Gamage, Hasanuzzaman Sagor, Faisal Tariq, Ling Ma, Muhammad Ali Imran, Ma. A Systematic Review of Project Allocation Methods in Undergraduate Transnational Engineering Education. Education Sciences. 2019; 9 (4):258.
Chicago/Turabian StyleSajjad Hussain; Kelum A. A. Gamage; Hasanuzzaman Sagor; Faisal Tariq; Ling Ma; Muhammad Ali Imran; Ma. 2019. "A Systematic Review of Project Allocation Methods in Undergraduate Transnational Engineering Education." Education Sciences 9, no. 4: 258.
There exists an ongoing need to develop and improve methods of detecting radioactive materials. As each radioactive isotope leaves a unique mark in a form of the particles it emits, new materials capable of detecting and measuring these particles are constantly sought. Neutrons and their detectors play a significant role in areas such as nuclear power generation, nuclear decommissioning and decontamination, border security, nuclear proliferation and nuclear medicine. Owing to the complexity of their detection, as well as scarcity of 3He, which has historically been the preferred choice for neutron detection in many application fields, new sensitive materials are sought. Organic and inorganic scintillating crystals have been recognised as particularly good alternatives, and as such systems that utilise them are increasingly common. As they allow investigation of the neutron energy spectra, greater information about the radioactive source can be inferred. Therefore, in this article, an extensive review of scintillating crystals used for neutron detection is presented. By describing the history of scintillating crystals and discussing changes that occurred in their use and development of methods for radiation detection, the authors present a comprehensive overview of the current situation. Supported by a practical example, possible future directions of the research area are also presented.
Michał J. Cieślak; Kelum A. A. Gamage; Robert Glover. Critical Review of Scintillating Crystals for Neutron Detection. Crystals 2019, 9, 480 .
AMA StyleMichał J. Cieślak, Kelum A. A. Gamage, Robert Glover. Critical Review of Scintillating Crystals for Neutron Detection. Crystals. 2019; 9 (9):480.
Chicago/Turabian StyleMichał J. Cieślak; Kelum A. A. Gamage; Robert Glover. 2019. "Critical Review of Scintillating Crystals for Neutron Detection." Crystals 9, no. 9: 480.
Assessment and feedback (A&F) are two major components of any educational program and must be properly in place to ensure student learning and quality of experience. However, these important components come under severe challenges of meeting student expectations in the large class size context. When the program delivery relates to a transnational educational (TNE) scenario, the additional constraints on staff–student physical interaction, regional time differences and cultural background gaps introduce additional challenges: Conducting proper assessments and provide timely and constructive feedback to the students. In this paper, the authors propose a novel assessment and feedback framework which exploits having a large student number as a positive factor by introducing staff–student partnership to implement efficient assessment and feedback strategies. Authors propose to use students for peer-review, assessment design, evaluation rubric design and tutorial-based feedback. The students also take part in preparing feedback clusters based on which the instructor provides pseudo-personalised video feedback. Through feedback clusters, authors introduce the trade-off between individual feedback and generic feedback. The results of the study are particularly promising in terms of student satisfaction and learning enhancement.
Sajjad Hussain; Kelum A. A. Gamage; Wasim Ahmad; Muhammad Ali Imran. Assessment and Feedback for Large Classes in Transnational Engineering Education: Student–Staff Partnership-Based Innovative Approach. Education Sciences 2019, 9, 221 .
AMA StyleSajjad Hussain, Kelum A. A. Gamage, Wasim Ahmad, Muhammad Ali Imran. Assessment and Feedback for Large Classes in Transnational Engineering Education: Student–Staff Partnership-Based Innovative Approach. Education Sciences. 2019; 9 (3):221.
Chicago/Turabian StyleSajjad Hussain; Kelum A. A. Gamage; Wasim Ahmad; Muhammad Ali Imran. 2019. "Assessment and Feedback for Large Classes in Transnational Engineering Education: Student–Staff Partnership-Based Innovative Approach." Education Sciences 9, no. 3: 221.
The pulse shape discrimination performance of a pixelated organic plastic scintillator has been investigated. The scintillator has been built using 169 plastic scintillator blocks (arranged into a 13 × 13 square array) of 2.8 × 2.8 × 15 mm3 each. The scintillator was coupled with a single-channel photomultiplier tube. The scintillator was exposed to a mixed-field environment provided by 252Cf and its pulse shape discrimination capabilities are presented in this paper. Initial results revealed that a 150 MS/s digitising system was insufficient to separate neutrons from gamma-ray photons. Therefore, the experiment was repeated with a 500 MS/s system, which provided improved pulse shape discrimination performance. In order to validate the performance of the pixelated plastic scintillator, it was compared to that of a cylindrical plastic sample. Tests were also carried out in moderated neutron and gamma-ray fields of 252Cf. The results indicate that acceptable levels of pulse shape discrimination are obtained for the case of a pixelated scintillator, when the higher sampling rate digitiser was used.
M.J. Cieślak; Kelum Akurugoda Gamage; R. Glover; C. James Taylor. Pulse shape discrimination performance of a pixelated plastic scintillator (EJ-299-34) for a coded-aperture based dual particle imaging system. Journal of Instrumentation 2019, 14, P07017 -P07017.
AMA StyleM.J. Cieślak, Kelum Akurugoda Gamage, R. Glover, C. James Taylor. Pulse shape discrimination performance of a pixelated plastic scintillator (EJ-299-34) for a coded-aperture based dual particle imaging system. Journal of Instrumentation. 2019; 14 (7):P07017-P07017.
Chicago/Turabian StyleM.J. Cieślak; Kelum Akurugoda Gamage; R. Glover; C. James Taylor. 2019. "Pulse shape discrimination performance of a pixelated plastic scintillator (EJ-299-34) for a coded-aperture based dual particle imaging system." Journal of Instrumentation 14, no. 7: P07017-P07017.
The characterisation of buried radioactive wastes is challenging because they are not readily accessible. Therefore, this study reports on the development of a method for integrating ground-penetrating radar (GPR) and gamma-ray detector measurements for nonintrusive characterisation of buried radioactive objects. The method makes use of the density relationship between soil permittivity models and the flux measured by gamma ray detectors to estimate the soil density, depth and radius of a disk-shaped buried radioactive object simultaneously. The method was validated using numerical simulations with experimentally-validated gamma-ray detector and GPR antenna models. The results showed that the method can simultaneously retrieve the soil density, depth and radius of disk-shaped radioactive objects buried in soil of varying conditions with a relative error of less than 10%. This result will enable the development of an integrated GPR and gamma ray detector tool for rapid characterisation of buried radioactive objects encountered during monitoring and decontamination of nuclear sites and facilities.
Ikechukwu K. Ukaegbu; Kelum A. A. Gamage; Michael D. Aspinall. Integration of Ground- Penetrating Radar and Gamma-Ray Detectors for Nonintrusive Characterisation of Buried Radioactive Objects. Sensors 2019, 19, 2743 .
AMA StyleIkechukwu K. Ukaegbu, Kelum A. A. Gamage, Michael D. Aspinall. Integration of Ground- Penetrating Radar and Gamma-Ray Detectors for Nonintrusive Characterisation of Buried Radioactive Objects. Sensors. 2019; 19 (12):2743.
Chicago/Turabian StyleIkechukwu K. Ukaegbu; Kelum A. A. Gamage; Michael D. Aspinall. 2019. "Integration of Ground- Penetrating Radar and Gamma-Ray Detectors for Nonintrusive Characterisation of Buried Radioactive Objects." Sensors 19, no. 12: 2743.
An investigation into the gamma-ray modulation properties of a tungsten coded aperture, whose design is based on the mathematical principles of Modified Uniformly Redundant Arrays (MURA), has been performed. Due to the small size of the individual cells, the aperture was built using additive manufacturing methods. The gamma-ray field was produced by a 137Cs radioactive isotope at Lancaster University, U.K. An organic plastic scintillator sample, which is capable of pulse shape discrimination, has been used to detect the gamma-ray field modulated by a tungsten aperture. Prior to the investigation of the aperture modulation properties, energy calibration of the scintillator was performed. Its pulse shape discrimination capabilities were verified using a 252Cf fission source. In this study, each of 169 coded aperture cells was investigated by collimating the modulated gamma-ray field of 137Cs through a 25.4 mm thick lead supporting plate. The supporting plate has one opening in the centre, of the same dimensions as the single aperture cell, i.e. 2.5 mm × 2.5 mm. The number of pulses detected for every aperture location were recorded in an array. The array was subsequently used to create a two-dimensional image of the source, which was encoded through the coded aperture pattern. Finally, the image was decoded using deconvolution techniques to reveal the actual source location. The new results obtained in this study indicate that sufficient gamma-ray modulation properties of the aperture can be determined, despite the relatively small footprint and thickness of the coded aperture.
M.J. Cieślak; K.A.A. Gamage; R. Glover; C.J. Taylor. Gamma-ray modulation properties of tungsten coded apertures for a novel mixed-field imaging system. Journal of Instrumentation 2019, 14, P02007 -P02007.
AMA StyleM.J. Cieślak, K.A.A. Gamage, R. Glover, C.J. Taylor. Gamma-ray modulation properties of tungsten coded apertures for a novel mixed-field imaging system. Journal of Instrumentation. 2019; 14 (2):P02007-P02007.
Chicago/Turabian StyleM.J. Cieślak; K.A.A. Gamage; R. Glover; C.J. Taylor. 2019. "Gamma-ray modulation properties of tungsten coded apertures for a novel mixed-field imaging system." Journal of Instrumentation 14, no. 2: P02007-P02007.
This study reports on the combination of data from a ground penetrating radar (GPR) and a gamma ray detector for nonintrusive depth estimation of buried radioactive sources. The use of the GPR was to enable the estimation of the material density required for the calculation of the depth of the source from the radiation data. Four different models for bulk density estimation were analysed using three materials, namely: sand, gravel and soil. The results showed that the GPR was able to estimate the bulk density of the three materials with an average error of 4.5%. The density estimates were then used together with gamma ray measurements to successfully estimate the depth of a 658 kBq ceasium-137 radioactive source buried in each of the three materials investigated. However, a linear correction factor needs to be applied to the depth estimates due to the deviation of the estimated depth from the measured depth as the depth increases. This new application of GPR will further extend the possible fields of application of this ubiquitous geophysical tool.
Ikechukwu K. Ukaegbu; Kelum A. A. Gamage; Michael D. Aspinall. Nonintrusive Depth Estimation of Buried Radioactive Wastes Using Ground Penetrating Radar and a Gamma Ray Detector. Remote Sensing 2019, 11, 141 .
AMA StyleIkechukwu K. Ukaegbu, Kelum A. A. Gamage, Michael D. Aspinall. Nonintrusive Depth Estimation of Buried Radioactive Wastes Using Ground Penetrating Radar and a Gamma Ray Detector. Remote Sensing. 2019; 11 (2):141.
Chicago/Turabian StyleIkechukwu K. Ukaegbu; Kelum A. A. Gamage; Michael D. Aspinall. 2019. "Nonintrusive Depth Estimation of Buried Radioactive Wastes Using Ground Penetrating Radar and a Gamma Ray Detector." Remote Sensing 11, no. 2: 141.
Due to the short path length of alpha particles in air, a detector that can be used at a distance from any potential radiological contamination reduces the time and hazard that traditional alpha detection methods incur. This would reduce costs and protect personnel in nuclear power generation and decommissioning activities, where alpha detection is crucial to full characterisation and contamination detection. Stand-off alpha detection could potentially be achieved by the detection of alpha-induced radioluminescence, especially in the ultraviolet C (UVC) wavelength range (180–280 nm) where natural and artificial background lighting is less likely to interfere with detection. However, such a detector would also have to be effective in the field, potentially in the presence of other radiation sources that could mask the UVC signal. This work exposed a UVC sensor, the UVTRON (Hamamatsu, Japan) and associated electronics (driver circuit, microprocessor) to sources of beta and gamma radiation in order to assess its response to both of these types of radiation, as may be found in the field where a mixed radiation environment is likely. It has been found that the UVTRON is affected by both gamma and beta radiation of a magnitude that would mask any UVC signal being detected. 152Eu generated 0.01 pulses per second per Bq through beta and gamma interactions, compared to 210Po, which generates 4.72 × 10−8 cps per Bq from UVC radioluminescence, at 20 mm separation. This work showed that UVTRON itself is more susceptible to this radiation than the associated electronics. The results of this work have implications for the use of the UVTRON as a sensor in a stand-off detection system, highlighting the necessity for shielding from both potential gamma and beta radiation in any detector design.
Anita J. Crompton; Kelum A. A. Gamage; Divyesh Trivedi; Alex Jenkins. The Effect of Gamma and Beta Radiation on a UVTRON Flame Sensor: Assessment of the Impact on Implementation in a Mixed Radiation Field. Sensors 2018, 18, 4394 .
AMA StyleAnita J. Crompton, Kelum A. A. Gamage, Divyesh Trivedi, Alex Jenkins. The Effect of Gamma and Beta Radiation on a UVTRON Flame Sensor: Assessment of the Impact on Implementation in a Mixed Radiation Field. Sensors. 2018; 18 (12):4394.
Chicago/Turabian StyleAnita J. Crompton; Kelum A. A. Gamage; Divyesh Trivedi; Alex Jenkins. 2018. "The Effect of Gamma and Beta Radiation on a UVTRON Flame Sensor: Assessment of the Impact on Implementation in a Mixed Radiation Field." Sensors 18, no. 12: 4394.
Strontium-90 is one of the primary beta-emitting radionuclides found at nuclear decommissioning sites. Monitoring its activity in the environment is of utmost importance given its radiotoxicity. Current procedures for the beta detection of strontium-90 are time consuming, produce secondary waste and expensive. There is a demand for real-time in situ radiostrontium monitoring in groundwater at nuclear decommissioning sites. This paper presents a review of existing techniques for strontium-90 monitoring and examines a novel approach through direct beta detection with a gallium arsenide photodiode based detector. A proof of concept detector was modelled in the physics simulation software, Geant4, and evaluated as candidate for in situ detection of beta emitting radionuclides. The simulation results indicate that the detector is physically capable of counting 89.86% of incident 0.546 MeV electrons from a 1 mm range in water. This validation will provide the basis for further development of an in situ beta detector.
Graeme Turkington; Kelum A.A. Gamage; James Graham. Beta detection of strontium-90 and the potential for direct in situ beta detection for nuclear decommissioning applications. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 2018, 911, 55 -65.
AMA StyleGraeme Turkington, Kelum A.A. Gamage, James Graham. Beta detection of strontium-90 and the potential for direct in situ beta detection for nuclear decommissioning applications. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2018; 911 ():55-65.
Chicago/Turabian StyleGraeme Turkington; Kelum A.A. Gamage; James Graham. 2018. "Beta detection of strontium-90 and the potential for direct in situ beta detection for nuclear decommissioning applications." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 911, no. : 55-65.