A5076076696- Radiation Detection and Scintillator Technologies
- Nuclear Physics and Applications
- Atomic and Subatomic Physics Research
- Hate Speech and Cyberbullying Detection
- Advanced Malware Detection Techniques
- Terrorism, Counterterrorism, and Political Violence
- Nuclear physics research studies
- Misinformation and Its Impacts
- Middle East Politics and Society
- Politics and Conflicts in Afghanistan, Pakistan, and Middle East
- Luminescence Properties of Advanced Materials
- Digital Games and Media
- Radioactive element chemistry and processing
- Medical Imaging Techniques and Applications
- Political Conflict and Governance
- African studies and sociopolitical issues
- Advanced X-ray and CT Imaging
- Particle Detector Development and Performance
- Islamic Studies and History
- Nuclear reactor physics and engineering
University of Maryland, College Park
2019-2023
Passport Systems (United States)
2010-2017
Radiation Monitoring Devices (United States)
2008-2009
Europium-doped strontium and barium iodide are found to be readily growable by the Bridgman method produce high scintillation light yields. SrI2(Eu) emits into Eu2+ band, centered at 435nm, with a decay time of 1.2μs yield ∼90000photons∕MeV. It offers energy resolution better than 4% full width half maximum 662keV, exhibits excellent proportionality. BaI2(Eu) produces >30000photons∕MeV band 420nm (<1μs decay). An additional broad impurity-mediated recombination is present 550nm...
New scintillators for high-resolution gamma ray spectroscopy have been identified, grown and characterized. Our development efforts focused on two classes of high-light-yield materials: europium-doped alkaline earth halides cerium-doped garnets. Of the halide single crystals we by Bridgman method-SrI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , CaI SrBr BaI BaBr -SrI is most promising. SrI (Eu) emits into Eu <sup...
Single crystals of SrI <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> :Eu and :Ce/Na were grown from anhydrous iodides by the vertical Bridgman technique in evacuated silica ampoules. Growth rates order 5-30 mm/day. Radioluminescence spectra exhibit a broad band due to Eu <sup xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> Ce xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> emission, respectively. The maximum luminescence...
Recently SrI<sub>2</sub>, a scintillator patented by Hofstadter in 1968, has been rediscovered and shown to possess remarkable scintillation properties. The light output of SrI<sub>2</sub>:Eu<sup>2+</sup> measured be even higher than previously observed exceeds 120,000 photons/MeV, making it one the brightest scintillators existence. crystal also excellent energy resolution less 3% at 662 keV. response is highly linear over wide range gamma ray energies. emission...
Photofission is the process in which a nucleus disintegrates into two daughter products after absorbing photon. near threshold actinides very similar to spontaneous fission terms of number emitted decay neutrons and their energy distribution. Most are ~2 MeV range, can be efficiently detected with liquid scintillator detectors. Thus, Prompt Neutrons from (PNPF) used as an excellent tool for detection actinides. Since photofission cross section most fissionable materials drops zero incident...
Measurements of states excited by nuclear resonance fluorescence in $^{237}\mathrm{Np}$ were performed using a bremsstrahlung beam. Fifteen new observed the region 1.7 to 2.5 MeV. They can be used detect or assay nondestructively for applications security and safeguards. The are populated with similar strength as those found previously $^{235}\mathrm{U}$ $^{239}\mathrm{Pu}$ but spread out more energy.
Nuclear resonance fluorescence (NRF), a process by which nucleus is excited absorption of specific quantum energy and then deexcites via the emission one or more $\ensuremath{\gamma}$ rays, may be applied to nondestructively measure isotopic composition sample. NRF excitations in ${}^{240}$Pu were identified range 2.1 2.8 MeV using 3-MeV bremsstrahlung source. Utilizing high-purity germanium detectors at backward angles, nine resonances this range. The measured integrated cross sections from...
A x-ray inspection system utilizing a continuous-wave 9 MeV rhodotron source for scanning cargo containers is presented. This scans contraband, anomalies, stowaway passengers, and nuclear threats trucks towed containers. transmission image generated concurrently with 3D of the cargo, latter presenting material information in form atomic number density. Neutrons from photofission are also detected during each scan. In addition, resonance fluorescence detectors capable identifying specific...
Russian information operations (IOs) targeting the U.S. political system have generated a significant amount of attention in recent years. Yet recently published report that I co-authored argues this focus on single threat actor leaves West open to being blindsided by other, emerging threats. While analysts focused Russia, other actors like Iran, North Korea, and China were actively conducting their own IOs social media platforms such as Twitter. In fact, Twitter regularly makes...
This report builds upon the work done in part one (DOI:10.2139/ssrn.4389821) of this series by examining network structure three information operations (IOs) that were removed from Twitter 2021. The analysis follows uses social (SNA) to explore structure, key statistics, and measures centrality for graphs created mentions. Five data sets feature analysis, IO networks two control networks. Data came Twitter’s Transparency Center contained tweets a Russian, Chinese, Iranian IO, respectively....
In this paper we report on the synthesis and scintillation properties of ammonium rare-earth halo-elpasolites, Cs(NH <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> )MYX xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> :Ce <sup xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> (M = Li, Na; X F, Cl). Due to their high vapor pressure, crystal growth was not feasible. Instead, reactive-atmosphere sintering used obtain polycrystalline...
The so-called caliphate that was created by the Islamic State attracted female recruits at a level not previously seen other Salafi-Jihadist groups. This new phenomenon led to creation of many unfounded assumptions about role jihadists; however, subsequent theoretical research has emerged in recent years challenges these and provides valuable insight into why this may have actually taken place. What follows is an analysis some as well application concepts real world through examination...
Somalia is a country locked in complex conflict which has dragged on for almost three decades, displacing millions and leaving hundreds of thousands dead. The causes the are numerous interrelated. This makes resolving that much more complicated. situation made worse by policies aimed at addressing often unclear, uncoordinated, or contradictory. misalignment between drivers approaches left trapped state perpetual chaos. What follows an examination some major historical events led to modern...
Many studies have examined ISIS’ usage of Twitter and other Internet platforms to cultivate their “online caliphate.” Despite all this attention on the online sphere, relatively few how propaganda influences real-world behavior. Of those that exist, are a generalizable scale. The following aims provide early findings relationship between broader Global Jihadist Movement’s offline activity, particularly regarding membership violence. This mixed-methods study collected data membership,...