Portal MV imaging with thin-film high-energy current X-ray detectors: A Monte Carlo study

2017 ◽  
Vol 44 (12) ◽  
pp. 6128-6137
Author(s):  
Bo Liu ◽  
Piotr Zygmanski ◽  
Erno Sajo
Keyword(s):  
Thin Film ◽  
Monte Carlo ◽  
Monte Carlo Study ◽  
High Energy ◽  
X Ray ◽  
Energy Current

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

scholarly journals Monte Carlo Modeling and Design of Photon Energy Attenuation Layers for >10× Quantum Yield Enhancement in Si-Based Hard X-ray Detectors

Instruments ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 17
Author(s):  
Eldred Lee ◽  
Kaitlin M. Anagnost ◽  
Zhehui Wang ◽  
Michael R. James ◽  
Eric R. Fossum ◽  
...  
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Quantum Yield ◽  
Photon Energy ◽  
High Efficiency ◽  
High Energy ◽  
Yield Enhancement ◽  
X Ray ◽  
Simulation Results ◽  
Conversion Efficiencies

High-energy (>20 keV) X-ray photon detection at high quantum yield, high spatial resolution, and short response time has long been an important area of study in physics. Scintillation is a prevalent method but limited in various ways. Directly detecting high-energy X-ray photons has been a challenge to this day, mainly due to low photon-to-photoelectron conversion efficiencies. Commercially available state-of-the-art Si direct detection products such as the Si charge-coupled device (CCD) are inefficient for >10 keV photons. Here, we present Monte Carlo simulation results and analyses to introduce a highly effective yet simple high-energy X-ray detection concept with significantly enhanced photon-to-electron conversion efficiencies composed of two layers: a top high-Z photon energy attenuation layer (PAL) and a bottom Si detector. We use the principle of photon energy down conversion, where high-energy X-ray photon energies are attenuated down to ≤10 keV via inelastic scattering suitable for efficient photoelectric absorption by Si. Our Monte Carlo simulation results demonstrate that a 10–30× increase in quantum yield can be achieved using PbTe PAL on Si, potentially advancing high-resolution, high-efficiency X-ray detection using PAL-enhanced Si CMOS image sensors.

Dose distribution from x-ray microbeam arrays applied to radiation therapy: An EGS4 Monte Carlo study

2005 ◽  
Vol 32 (8) ◽  
pp. 2455-2463 ◽  
Author(s):  
M. De Felici ◽  
R. Felici ◽  
M. Sanchez del Rio ◽  
C. Ferrero ◽  
T. Bacarian ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Radiation Therapy ◽  
Dose Distribution ◽  
Monte Carlo Study ◽  
X Ray

Dosimetric optimization of a truncated conical-shaped transmission target for electronic brachytherapy X-ray source: A Monte Carlo study

2017 ◽  
Vol 71 (3) ◽  
pp. 178-184
Author(s):  
Woo Sang Ahn ◽  
Wonsik Choi ◽  
Byungchul Cho ◽  
Jungwon Kwak ◽  
Seung Do Ahn ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
X Ray ◽  
Electronic Brachytherapy

scholarly journals Microfluidic electrochemical cell for in situ structural characterization of amorphous thin-film catalysts using high-energy X-ray scattering

2019 ◽  
Vol 26 (5) ◽  
pp. 1600-1611 ◽  
Author(s):  
Gihan Kwon ◽  
Yeong-Ho Cho ◽  
Ki-Bum Kim ◽  
Jonathan D. Emery ◽  
In Soo Kim ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrochemical Cell ◽  
Porous Electrode ◽  
High Energy ◽  
Porous Electrodes ◽  
X Ray ◽  
Pdf Analysis ◽  
Thin Film Catalysts

Porous, high-surface-area electrode architectures are described that allow structural characterization of interfacial amorphous thin films with high spatial resolution under device-relevant functional electrochemical conditions using high-energy X-ray (>50 keV) scattering and pair distribution function (PDF) analysis. Porous electrodes were fabricated from glass-capillary array membranes coated with conformal transparent conductive oxide layers, consisting of either a 40 nm–50 nm crystalline indium tin oxide or a 100 nm–150 nm-thick amorphous indium zinc oxide deposited by atomic layer deposition. These porous electrodes solve the problem of insufficient interaction volumes for catalyst thin films in two-dimensional working electrode designs and provide sufficiently low scattering backgrounds to enable high-resolution signal collection from interfacial thin-film catalysts. For example, PDF measurements were readily obtained with 0.2 Å spatial resolution for amorphous cobalt oxide films with thicknesses down to 60 nm when deposited on a porous electrode with 40 µm-diameter pores. This level of resolution resolves the cobaltate domain size and structure, the presence of defect sites assigned to the domain edges, and the changes in fine structure upon redox state change that are relevant to quantitative structure–function modeling. The results suggest the opportunity to leverage the porous, electrode architectures for PDF analysis of nanometre-scale surface-supported molecular catalysts. In addition, a compact 3D-printed electrochemical cell in a three-electrode configuration is described which is designed to allow for simultaneous X-ray transmission and electrolyte flow through the porous working electrode.

scholarly journals Flow Cell for Operando X-Ray Photon-in-Photon-out Studies on Photo-Electrochemical Thin Film Devices

2020 ◽  
Author(s):  
Philipp Jäker ◽  
Dino Aegerter ◽  
Till Kyburz ◽  
Roman Staedler ◽  
Rea Fonjallaz ◽  
...  
Keyword(s):  
Thin Film ◽  
Water Oxidation ◽  
High Energy ◽  
Operating Conditions ◽  
High Energy Resolution ◽  
X Ray ◽  
Long Term Stability ◽  
Operando Xas ◽  
Artificial Photosynthetic ◽  
Thin Film Devices

Photo-electro-chemical (PEC) water splitting represents a promising technology towards an artificial photosynthetic device but many fundamental electronic processes, which govern long-term stability and energetics are not well understood. X-ray absorption spectroscopy (XAS), particularly its high energy resolution fluorescence-detected (HERFD) mode, emerges as a powerful tool to study photo-excited charge carrier behavior under operating conditions. The established thin film device architecture of PEC cells provides a well-defined measurement geometry, but it puts many constraints on conducting operando XAS experiments. So far, operando cells have not been developed that enable to concurrently measure highly intense X-ray fluorescence and photo-electro-chemical current without experimental artifacts caused by O<sub>2</sub> and H<sub>2</sub> bubbles formation. Moreover, we are missing a standardized thin film exchange procedure. Here, we address and overcome the instrumental limitations for operando HERFD-XAS to investigate photo- and electrochemical thin film devices. Our cell establishes a measurement routine that will provide experimental access to a broader scientific community, particularly due to the ease of sample exchange. Our operando photo-electro-chemical cell is optimized for the HERFD-XAS geometry and we demonstrate its operation by collecting high-resolution Fe K-edge spectra of hematite (α-Fe<sub>2</sub>O<sub>3</sub>) and ferrite thin film (MFe<sub>2</sub>O<sub>4</sub>, M= Zn, Ni) photoelectrodes during water oxidation.<br>

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