Nuclear Security Applications Research Articles

Simultaneous Gamma-Neutron Vision device: a portable and versatile tool for nuclear inspections

This work presents GN-Vision, a novel dual γ-ray and neutron imaging system, which aims at simultaneously obtaining information about the spatial origin of γ-ray and neutron sources. The proposed device is based on two position sensitive detection planes and exploits the Compton imaging technique for the imaging of γ-rays. In addition, spatial distributions of slow- and thermal-neutron sources (<100 eV) are reconstructed by using a passive neutron pin-hole collimator attached to the first detection plane. The proposed gamma-neutron imaging device could be of prime interest for nuclear safety and security applications. The two main advantages of this imaging system are its high efficiency and portability, making it well suited for nuclear applications were compactness and real-time imaging is important. This work presents the working principle and conceptual design of the GN-Vision system and explores, on the basis of Monte Carlo simulations, its simultaneous γ-ray and neutron detection and imaging capabilities for a realistic scenario where a 252Cf source is hidden in a neutron moderating container.

Neutron sensing at spallation neutron sources by SERS

Neutron detectors are paramount in many applications from medical science to homeland security and aerospace. A miniaturized solid-state device based on a nanostructured-gold thin film grown by pulsed laser ablation under deposition-controlled conditions and functionalized with a monolayer of 4-mercaptophenyboronic acid (4-MPBA) was fabricated as a neutron dose detector. The device is tested with slow neutron detection in the thermal and epithermal energy range at ISIS spallation neutron source (UK). After the neutron irradiation, 4-MPBA is converted into thiophenol (TP), and the chemical modification is monitored by the intensity of related vibrational bands at 1586 cm−1 (4-MPBA) and 1574 cm−1 (TP). The latter are used as a vibrational signature of the absorbed dose by surface-enhanced Raman spectroscopy (SERS). The conversion of 4-MPBA to TP is due to the loss of the boron-containing group after the absorption of a slow neutron by 10B isotope. The I1574/I1586 ratio is used to estimate the ratio of 10B nuclei absorption reactions due to the thermal and epithermal contributions and it is proposed for the development of neutron dosimetry for nuclear medicine, aerospace, and security applications.

Investigation of the structural, mechanical, radiation and neutron shielding properties of the TeO2-B2O3-Li2O-MoO3-CuO glass system

In this study, the structural, mechanical, radiation and neutron shielding properties of (78-x)(0.4TeO2-0.6B2O3)− 20Li2O-xMoO3-2CuO glass system, were investigated. A variety of characterisation methods, including optical absorption spectroscopy, FTIR, EPR, and X-ray diffraction, were used to examine the structural characteristics. Molecular orbital coefficients were calculated from EPR and optical absorption measurements. EPR lines of both Cu2+ and Mo5+ ions were observed in the EPR spectra. The mechanical properties were assessed through experimental measurements, while the elastic properties were evaluated using the semi-empirical approaches of the Makishima and Mackenzie model, along with the bond compression model. The inclusion of 4% MoO3 led to noteworthy enhancements in both hardness and fracture toughness. Hardness increased from 4.364 to 4.664 GPa, and fracture toughness improved from 0.980 to 1.226 MPa.m1/2. The mass attenuation coefficients (MAC), mean free paths (MFP), half-value layers (HVL), and effective atomic numbers (Zeff) were measured in the energy range of 59.54–661.62 keV. The measurement of equivalent dose rates resulting from the absorption of fast neutrons was conducted utilizing a 241Am-Be fast neutron source with an activity of 10 mCi. The exposure buildup factor (EBF) and the fast neutron removal cross section (ΣR) were therotically calculated. The potential suitability of glasses for nuclear security applications was assessed by evaluating their proton and alpha shielding properties. The study found that glasses containing higher amounts of TeO2 and MoO3, within the TeO2-B2O3-Li2O-MoO3-CuO composition, demonstrated enhanced capabilities for shielding against radiation and neutrons.

Calibration of a compact ASIC-based data acquisition system for neutron/[formula omitted] discrimination and spectroscopy with organic scintillators

Segmented neutron detectors that use silicon photomultipliers (SiPMs) are receiving significant attention in nuclear security applications. Some of these detectors employ hundreds of channels and would therefore benefit from the use of high-channel-density and low-cost-per-channel data acquisition (DAQ) systems. Candidate DAQ systems that meet these requirements exist, but few perform full waveform digitization, which permits neutron and gamma-ray interaction discrimination via pulse shape. In this work, we study the performance of the TOFPET2 (PETsys Electronics), an ASIC-based DAQ designed for positron emission tomography, which has been adapted to provide sensitivity to pulse shape by the use of variable-period charge integration. We use a light-emitting diode to calibrate a combination of an ON Semiconductor (SensL) 60035-64P J-Series SiPM and TOPFET2 DAQ and evaluate the linearity of their response and dynamic range. The calibration curve was obtained by comparing the DAQ response to that measured with a photodiode interfaced with a traditional waveform digitizer. This calibration process was used for rudimentary spectroscopy of various neutron and γ sources.

Structural and radiation shielding parameters of heavy metal-based environment-friendly glass systems for nuclear radiation security applications

This work used theoretical and experimental approaches to examine the effects of the partial substitution of cadmium (II) oxide for boron trioxide on structural, optical, and physical characteristics. Using the melt quenching technique, we created a cadmium (Cd)-borate glass group with the following nominal composition: (60-X)B2O3 + 20Na2O + 5NiO + 15CaCO3 + xCdO system, where x = 0, 2.5, 5, 7.5 and 10 wt%. The amorphous structure of the Cd-borate glasses was determined using an experimental X-ray diffraction technique. Additionally, density and UV studies were used to investigate optical and material properties. To determine the effect of this substitution on the improvement of nuclear radiation shielding, the linear attenuation coefficients at 80, 356, 662, 1173, and 1333 keV were measured using a narrow beam geometry and an experimental gamma-ray transmission technique. When the CdO level was raised from 0 to 10% (by weight), both the molar volume and transmission decreased in value while hardness of the glass increased. In addition, adding 5% CdO to this glass in its current composition led to a greater absorption of neutrons. The absorption of gamma rays required the addition of 10% CdO. Thus, the best radiation filter was a Cd-borate glass that contained 10% CdO.

Calibration strategy of the PROSPECT-II detector with external and intrinsic sources

This paper presents an energy calibration scheme for an upgraded reactor antineutrino detector for the Precision Reactor Oscillation and Spectrum Experiment (PROSPECT). The PROSPECT collaboration is preparing an upgraded detector, PROSPECT-II (P-II), to advance capabilities for the investigation of fundamental neutrino physics, fission processes and associated reactor neutrino flux, and nuclear security applications. P-II will expand the statistical power of the original PROSPECT (P-I) dataset by at least an order of magnitude. The new design builds uponprevious P-I design and focuses on improving the detector robustness and long-term stability to enable multi-year operation at one or more sites. The new design optimizes the fiducial volume by elimination of dead space previously occupied by internal calibration channels, which in turn necessitates the external deployment. In this paper, we describe a calibration strategy for P-II. The expected performance of externally deployed calibration sources is evaluated using P-I data and a well-benchmarked simulation package by varying detector segmentation configurations in the analysis. The proposed external calibration scheme delivers a compatible energy scale model and achieves comparable performance with the inclusion of an additional AmBe neutron source, in comparison to the previous internal arrangement. Most importantly, the estimated uncertainty contribution from the external energy scale calibration model meets the precision requirements of the P-II experiment.

Euler–Maruyama algorithm in estimating UGV path and location in nuclear emergency and security applications

Abstract Mobile Robots (MR) are currently used across a variety of different sectors and have military, nuclear and industrial applications among others. In unmanned systems, teleoperation sensors, navigation instruments, control systems and radiation sensors can be fixed on the MR to perform required tasks such as radiological scanning, identifying, and surveying the contaminated environment that has been exposed to radiation. In this work, an estimation of the mobile robot location and the optimum path for time-delay compensation for MR teleoperation are investigated. As the MR teleoperation has a stochastic nature, the kinematics equations are modeled using stochastic differential equations (SDEs). Afterwards, these SDEs are solved using Numerical algorithms such as Euler–Maruyama algorithm which is used to approximate SDEs solution with the aid of MATLAB. Additionally, the results are discussed and depicted in tables and figures. Finally, the simulated results for the solution are performed and are found to highly agree with the ideal path of the simulated MR. This result is of great importance to be used in the case of nuclear emergency response and mitigation.

A simple and low-cost directional detection technique for radiation source localization for nuclear security applications

One of the goals in the field of nuclear security is to prevent the misuse and loss of nuclear or other radiological materials. If lost or stolen, radioactive materials could be located and secured using radiation detectors like count rate meters or imaging systems. However, such detectors may not allow for the swift localization of lost sources or may be cost prohibitive in many measurement scenarios. A simple, low-cost, directional radiation detector that is capable of quickly “pointing” towards the nearest radiation source is sought for source search scenarios. Such a detector can be realized using a plastic scintillator couple on each end to photo-multiplier tubes, as shown in this work. The event-by-event position of scintillation in this study is approximated by averaging the amount of light arriving at each of the photomultiplier tubes during coincidence counting. The detector system is then rotated so that the approximated scintillation positions within the detector volume can be determined in other spatial dimensions. A guess vector generated by comparing light ratio skewness produced by the detector in orthogonal orientations points in the direction of a nearby radiation source. An MCNPX-PoliMi model was used to guide the design of such a detector and validate the guess-vector technique. A prototype system using a cube of an EJ-204 plastic scintillator and two photomultiplier tubes was constructed and a correlation between azimuthal source position and detector response was established. For measurements of tens of thousands of counts, the detector prototype generates guess vectors that can identify source position to within 5° uncertainty. The detector prototype can determine the general direction of a nearby source to within 45° uncertainty using 1000 total counts.

Nuclear fuel irradiation testbed for nuclear security applications

The nuclear security community has long been interested in the identification and quantification of nuclear material signatures to understand a material’s provenance, use, and ultimate application. New forensics signatures and methods intended for non-traditional or advanced nuclear fuel applications require fuel irradiation experiments to demonstrate viability and validity. Integral fuel irradiations have historically required significant costs and long timelines to design, irradiate, and characterize. This paper describes how a recently developed nuclear fuel irradiation testbed can be used to provide a low cost, rapid turnaround, modular test environment for irradiation and evaluation of nuclear fuel specimens for nuclear security applications. The irradiation testbed houses six small ‘MiniFuel’ samples within hermetically sealed capsules inside targets that can be removed in between each ∼25-day operating cycle of the High Flux Isotope Reactor (HFIR). As many as nine targets can be irradiated using a single irradiation position (reflector region) in HFIR, allowing for varying irradiation temperatures and burnups. A suite of hot cell capabilities have been established to perform post-irradiation examination for measuring performance (e.g., fuel swelling, fission gas release) and facilitating experiment disassembly for subsequent property measurements, microstructural analysis, or chemical assay. This new testbed allows fuel irradiations to be conducted on an accelerated timeframe to enable rapid proof of concept testing and to provide reference material for nuclear fuel security applications. Recent applications using this testbed include the testing of isotopic taggants in UO2 fuel (intentional forensics), testing of U-10Mo fuel for down-conversion of highly enriched uranium–fueled reactors, and the production of irradiated UO2 fuel material for signature analysis of its isotopic composition (plutonium, fission gases, etc.).

A Wide Energy Range and 4π-View Gamma Camera with Interspaced Position-Sensitive Scintillator Array and Embedded Heavy Metal Bars.

(1) Background: Gamma cameras have wide applications in industry, including nuclear power plant monitoring, emergency response, and homeland security. The desirable properties of a gamma camera include small weight, good resolution, large field of view (FOV), and wide imageable source energy range. Compton cameras can have a 4π FOV but have limited sensitivity at low energy. Coded-aperture gamma cameras are operatable at a wide photon energy range but typically have a limited FOV and increased weight due to the thick heavy metal collimators and shielding. In our lab, we previously proposed a 4π-view gamma imaging approach with a 3D position-sensitive detector, with which each detector element acts as the collimator for other detector elements. We presented promising imaging performance for 99mTc, 18F, and 137Cs sources. However, the imaging performance for middle- and high-energy sources requires further improvement. (2) Methods: In this study, we present a new gamma camera design to achieve satisfactory imaging performance in a wide gamma energy range. The proposed gamma camera consists of interspaced bar-shaped GAGG (Ce) crystals and tungsten absorbers. The metal bars enhance collimation for high-energy gamma photons without sacrificing the FOV. We assembled a gamma camera prototype and conducted experiments to evaluate the gamma camera’s performance for imaging 57Co, 137Cs, and 60Co point sources. (3) Results: Results show that the proposed gamma camera achieves a positioning accuracy of <3° for all gamma energies. It can clearly resolve two 137Cs point sources with 10° separation, two 57Co and two 60Co point sources with 20° separation, as well as a 2 × 3 137Cs point-source array with 20° separation. (4) Conclusions: We conclude that the proposed gamma camera design has comprehensive merits, including portability, 4π-view FOV, and good angular resolution across a wide energy range. The presented approach has promising potential in nuclear security applications.

Radiation shielding capacity of Li2O-SiO2/GeO2 glasses doped with rare earth oxides: Nuclear security applications

In the present work, the ionizing radiation (namely, gamma-rays, charged particles, and neutrons) attenuation parameters of Li2O–SiO2 (denoted as LS) and Li2O–SiO2–GeO2 glasses doped with Y2O3 and In2O3 (LGY and LGI) glasses were estimated and analyzed with the aim of exploring their shielding potentials. The gamma-ray transmission attenuation coefficient was simulated by the FLUKA code and also estimated by XCOM. Also, the stopping powers and ranges of electrons, protons, α-particles, and carbon ions were estimated for particle kinetic energies within 15–15000 keV. The fast and thermal (25 meV) neutron cross-sections were estimated for the three glasses. At 15 MeV, the mass attenuation coefficient is 0.019, 0.021 and 0.022 cm2/g while the linear attenuation coefficient magnitude varied within the range of 0.047–11.564 cm−1, 0.061–32.008 cm−1 and 0.068–38.122 cm−1 for LS, LGY, and LGI, respectively. The effective atomic number varied from 8.21 to 12.00 for LS, 8.71–22.71 for LGY, and 8.78–26.37 for LGI. Likewise, the charged particle shielding ability of the glasses was in the order: LS < LGY < LGI. This trend was conserved for the neutrons’ cross-sections. Compared to conventional and recently researched shields, LS, LGY, and LGI present viable alternative glass shields in nuclear radiation applications.

Four-phases characterization of synthesised CeO2 thin films: Effect of molarity on structural, optical, physical properties and gamma-ray attenuation parameters

A group of novel CeO 2 thin films were synthesised using ultrasonic spray pyrolysis process. The composition ratios of these films were modified to investigate changes in their optical, surface, electrical, and structural characteristics. Absorbance spectra in the range 300–900 nm was acquired. Transmittance in the visible area was determined to be 50%. The optical band gap was reported to vary between 3.38 and 3.52eV using absorbance spectra. X-ray diffraction was used to analyse the films' structure, while atomic force microscopy was used to determine the surface roughness values. Spectroscopic ellipsometry and the Cauchy–Urbach model were used to calculate the thicknesses. Electrical resistivity values were determined using a four-probe system. CeO 2 thin film X-ray diffraction patterns validated the polycrystalline cubic fluorite structure. According to the data, the deposited films expand preferentially in the (2 0 0) direction. The films were found to have a high resistivity of 10 6 Ω cm. We also evaluated the nuclear radiation shielding properties of CeO 2 thin films in the 0.015–15 MeV photon energy range. The results indicated that CeO 2 thin film exhibits promising half value layers of 0.00169 cm, 0.14055 cm, 1.62665 cm, and 2.30273 cm, respectively, for 0.015 MeV, 0.15 MeV, 1 MeV, and 15 MeV CeO 2 films have been determined to be worth working on and may be promising materials for optoelectronic and nuclear security applications.

Semi-empirical simulation of in-motion radiation detection systems

The Replicative Assessment of Spectroscopic Equipment (RASE) is an open-source software that uses experimental data as the basis to simulate the response of commercial radiation detectors to sources in various situations, particularly in the context of nuclear security and safeguards applications. Dynamic RASE introduces the capability to simulate scenarios where sources and detector are in relative motion. Position-dependent experimentally acquired gamma spectra are ingested by Dynamic RASE to build maps that describe the detector response over all space. These response maps are used to replicate the time-dependent energy spectra collected as sources move on a path near the detector. A Gaussian process is used to build each map, incorporating a novel kernel adapted to the special case of radiation detection. The approach has been validated against experimental data acquired using a NaI-based detector for 137Cs and 54Mn sources. The capability to create accurate simulations using either long-dwell static measurements or dynamic pass-by measurements as source data has been demonstrated. Quantitative relative performance, benefits, and shortcomings are discussed.

PROSPECT-II physics opportunities

The precision reactor oscillation and spectrum experiment, PROSPECT, has made world-leading measurements of reactor antineutrinos at short baselines. In its first phase, conducted at the high flux isotope reactor (HFIR) at Oak Ridge National Laboratory, PROSPECT produced some of the strongest limits on eV-scale sterile neutrinos, made a precision measurement of the reactor antineutrino spectrum from 235U, and demonstrated the observation of reactor antineutrinos in an aboveground detector with good energy resolution and well-controlled backgrounds. The PROSPECT collaboration is now preparing an upgraded detector, PROSPECT-II, to probe yet unexplored parameter space for sterile neutrinos and contribute to a full resolution of the reactor antineutrino anomaly, a longstanding puzzle in neutrino physics. By pressing forward on the world’s most precise measurement of the 235U antineutrino spectrum and measuring the absolute flux of antineutrinos from 235U, PROSPECT-II will sharpen a tool with potential value for basic neutrino science, nuclear data validation, and nuclear security applications. Following a two-year deployment at HFIR, an additional PROSPECT-II deployment at a low enriched uranium reactor could make complementary measurements of the neutrino yield from other fission isotopes. PROSPECT-II provides a unique opportunity to continue the study of reactor antineutrinos at short baselines, taking advantage of demonstrated elements of the original PROSPECT design and close access to a highly enriched uranium reactor core.

Simulation and Modeling of Optical Properties of U, Th, Pb, and Co Nanoparticles of Interest to Nuclear Security Using Finite Element Analysis.

In this work, the optical characteristics of uranium (U), lead (Pb), cobalt (Co), and thorium (Th) nanoparticles are fashioned and simulated employing the finite element analysis (FEA) approach concerning multiple particle sizes. Applying finite element analysis, it was found that the simulated absorption peaks of electronic excitations of nuclear nanoparticles are red-shifted from 365 nm to 555 nm for U; from 355 nm to 550 nm for Pb; from 415 nm to 610 nm for Co; and from 350 nm to 540 nm for Th, comparing expanding particle sizes from 60 nm to 100 nm (except for Co, which varied from 70 nm to 100 nm). The FEA-simulated optical band gap energies and far-field radiation patterns were also obtained for nuclear materials. The simulation approach in this research enables the prediction of optical properties and design of nuclear materials before manufacture for nuclear security applications.

Modeling and Simulation of Radioactive Nanomaterials of Pb-U, Pb-Th, and Pb-Co in Water-Filled Containers for Nuclear Security Applications

In this paper, the optical properties of lead-thorium (Pb-Th), lead-uranium (Pb-U), and lead-cobalt (Pb-Co) nuclear nanoparticles in a container filled with water are simulated and modeled employing finite element analysis (FEA) for diverse particle sizes. The simulated absorption maxima of electronic excitations of nuclear nanoparticles such as Pb-U are red-shifted from 375 to 380 nm for the first peak, from 595 to 600 nm for the second peak, and from 730 to 740 nm for the third peak with increasing particle sizes from core U: 7 nm and shell Pb: 2 nm to core U: 9 nm and shell Pb: 2 nm. Moreover, the absorption peak of the Pb-Th and Pb-Co nanoparticles is red-shifted by increasing the particle size. The FEA-simulated optical band gap energies of Pb-Th, Pb-U, and Pb-Co nanoparticles were also obtained, and the data decreased with increasing the particle size. FEA-based simulations have disclosed restrictions intended for Pb-Th and Pb-Co nanoparticles size greater than 9 nm and for Pb-U nanoparticles size larger than 11 nm. The simulation method in this research enables the prediction of optical properties and contributes to the understanding and design of Pb-Th, Pb-U, and Pb-Co nanoparticles in the water container before manufacturing and functionalizing them. The work here is of particular interest in the nuclear security domain and in the nondestructive, remote detection of special nuclear materials (SNM) in water-filled cargo containers, whose manual inspection imposes physical and financial challenges.

Simultaneous neutron and gamma imaging system for real time range and dose monitoring in Hadron Therapy and nuclear security applications

GN-Vision is a novel dual γ-ray and neutron imaging system, which aims at imaging, simultaneously to the prompt gammas, the spatial origin of the slow and thermal neutron dose (&lt;100 eV) generated during hadron therapy treatments. The proposed device can also be of interest for industrial applications as well as in nuclear security. The GN-Vision system has been designed following the technical developments of the iTED detector, an array of high efficiency Compton cameras intended for neutron-capture experiments, in which γ-ray energies span up to 5-6 MeV, similar to the energies encountered in hadron therapy. This manuscript presents the evolution of the i-TED detector towards the GN-Vision system and the first conceptual study of the simultaneous neutron and γ-ray imaging capability. Last, it reviews the status of the development and first results of the promising performance of this device for PG imaging in proton therapy, based on MC simulations.

Optical, structural, physical, and nuclear shielding properties, and albedo parameters of TeO2–BaO–B2O3–PbO–V2O5 glasses

In this study, glass systems were constructed according to the formula 34TeO2∙xBaO∙35B2O3∙(30-x)PbO∙1V2O5 (x=0, 5, 10, 15, 20, 30 mol%). The gamma, neutron, proton, and alpha shielding characteristics of the glasses were evaluated for nuclear security applications. The mass attenuation coefficient (MAC), half-value layer, mean free path, effective atomic number, and radiation protection efficiency (RPE) were experimentally measured in the energy range of 59.54–661.62 keV. In addition, the theoretical MAC values were determined. The exposure buildup factor, fast neutron removal cross section, mass stopping power, and projected range values for proton (H1) and alpha (He+2) particles were theoretically determined. Albedo parameters were measured for the prepared glasses at photon energy of 59.54 keV. The optical and structural properties were studied using X-ray diffraction, FT-IR Fourier transform infrared, ultraviolet–visible, and electron paramagnetic resonance spectroscopy. The glass samples comprised structural units such as TeO4, TeO3, BO3, and BO4. The spin Hamiltonian parameters, g∥, g⊥, A∥, A⊥, dipolar hyperfine coupling parameter, P, and Fermi contact parameter, κ, were calculated. The molecular orbital parameters, α2, β2, and γ2, were determined by optical absorption spectroscopy. The number of bonds per unit volume in the glasses ranged between 8.763 and 9.212×1028 m−3. The most reflective compound among the glasses investigated was BaO. Good agreement was found between the theoretical and experimental MAC values. TeBaBPbV1 glass was identified as a potential candidate for use in neutron, gamma, proton, and alpha shielding.

A Review of Nanomaterial Based Scintillators

Recently, nanomaterial-based scintillators are newly emerging technologies for many research fields, including medical imaging, nuclear security, nuclear decommissioning, and astronomical applications, among others. To date, scintillators have played pivotal roles in the development of modern science and technology. Among them, plastic scintillators have a low atomic number and are mainly used for beta-ray measurements owing to their low density, but these types of scintillators can be manufactured not in large sizes but also in various forms with distinct properties and characteristics. However, the plastic scintillator is mainly composed of C, H, O and N, implying that the probability of a photoelectric effect is low. In a gamma-ray nuclide analysis, they are used for time-related measurements given their short luminescence decay times. Generally, inorganic scintillators have relatively good scintillation efficiency rates and resolutions. And there are thus widely used in gamma-ray spectroscopy. Therefore, developing a plastic scintillator with performance capabilities similar to those of an inorganic scintillator would mean that it could be used for detection and monitoring at radiological sites. Many studies have reported improved performance outcomes of plastic scintillators based on nanomaterials, exhibiting high-performance plastic scintillators or flexible film scintillators using graphene, perovskite, and 2D materials. Furthermore, numerous fabrication methods that improve the performance through the doping of nanomaterials on the surface have been introduced. Herein, we provide an in-depth review of the findings pertaining to nanomaterial-based scintillators to gain a better understanding of radiological detection technological applications.

Design and performance evaluation of a 4[formula omitted]-view gamma camera with mosaic-patterned 3D position-sensitive scintillators

Gamma hotspots imaging is of dramatic demand in nuclear-related industrial and homeland security activities such as nuclear facilities monitoring, nuclear emergency response and border inspection. Gamma cameras with mechanical collimation (i.e., coded-aperture) have reduced sensitivity, limited FOV and are typically heavy-weighted. Compton cameras with electrical collimation can achieve higher sensitivity as well as being capable of performing portable 4π-view imaging. However, imageable isotopes of Compton cameras are limited to middle- or high-energy ones. We have previously proposed the concept to image gamma hotspots with a 3-D position-sensitive scintillation detector. This approach achieves high sensitivity, 4π-view FOV and is effective in a wide energy range. In this work, we present a novel gamma camera design aiming for high-resolution gamma imaging. The proposed detector consists of interspaced GAGG(Ce) scintillators that form a mosaic pattern, which is coupled to SiPM arrays on both ends. 3-D photon interaction position information is measured with a dual-end-readout technique. The measured interaction positions for detected photon events are rebinned into the projection data, and the gamma image is reconstructed using a maximum likelihood expectation maximization (MLEM) algorithm. We perform Monte Carlo simulations and experiments to evaluate the performance of the proposed gamma camera design for imaging 99mTc and 137Cs sources. Results show that the proposed gamma camera achieves a positioning accuracy of less than 1° for a 99mTc source and 3° for a 137Cs source. It can clearly resolve two 99mTc sources with 10° separation and two 137Cs point sources with 23° separation, as well as a 2 × 6 99mTc point-source-array with 20° separation clearly. We conclude that the proposed gamma camera design is profitable in portability, FOV, sensitivity, image resolution and energy range. It has promising application potential in fast and accurate radiation monitoring tasks in nuclear security applications.