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https://www.readbyqxmd.com/read/28617497/flexible-hybrid-graphene-a-si-h-multispectral-photodetectors
#1
D S Schneider, A Bablich, M C Lemme
We report on the integration of large area CVD grown single- and bilayer graphene transparent conductive electrodes (TCEs) on amorphous silicon multispectral photodetectors. The broadband transmission of graphene results in 440% enhancement of the detectors' spectral response in the ultraviolet (UV) region at λ = 320 nm compared to reference devices with conventional aluminum doped zinc oxide (ZnO:Al) electrodes. The maximum responsivity of the multispectral photodetectors can be tuned in their wavelength from 320 nm to 510 nm by an external bias voltage, allowing single pixel detection of UV to visible light...
June 15, 2017: Nanoscale
https://www.readbyqxmd.com/read/28610696/use-of-ptw-microdiamond-for-relative-dosimetry-of-unflattened-photon-beams
#2
Giacomo Reggiori, Antonella Stravato, Maria Pimpinella, Francesca Lobefalo, Vanessa De Coste, Antonella Fogliata, Pietro Mancosu, Fiorenza De Rose, Valentina Palumbo, Marta Scorsetti, Stefano Tomatis
PURPOSE: The increasing interest in SBRT treatments encourages the use of flattening filter free (FFF) beams. Aim of this work was to evaluate the performance of the PTW60019 microDiamond detector under 6MV and 10MVFFF beams delivered with the EDGE accelerator (Varian Medical System, Palo Alto, USA). A flattened 6MV beam was also considered for comparison. METHODS: Short term stability, dose linearity and dose rate dependence were evaluated. Dose per pulse dependence was investigated in the range 0...
June 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28571430/note-coincidence-measurements-of-3-he-and-neutrons-from-a-compact-d-d-neutron-generator
#3
Q Ji, C-J Lin, C Tindall, M Garcia-Sciveres, T Schenkel, B A Ludewigt
Tagging of neutrons (2.45 MeV) with their associated (3)He particles from deuterium-deuterium (D-D) fusion reactions has been demonstrated in a compact neutron generator setup enabled by a high brightness, microwave-driven ion source with a high fraction of deuterons. Energy spectra with well separated peaks of the D-D fusion reaction products, (3)He, tritons, and protons, were measured with a silicon PIN diode. The neutrons were detected using a liquid scintillator detector with pulse shape discrimination...
May 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28571408/multipurpose-setup-for-low-temperature-conversion-electron-m%C3%A3-ssbauer-spectroscopy
#4
V Augustyns, M Trekels, H P Gunnlaugsson, H Masenda, K Temst, A Vantomme, L M C Pereira
We describe an experimental setup for conversion electron Mössbauer spectroscopy (CEMS) at low temperature. The setup is composed of a continuous flow cryostat (temperature range of 4.2-500 K), detector housing, three channel electron multipliers, and corresponding electronics. We demonstrate the capabilities of the setup with CEMS measurements performed on a sample consisting of a thin enriched (57)Fe film, with a thickness of 20 nm, deposited on a silicon substrate. We also describe exchangeable adaptations (lid and sample holder) which extend the applicability of the setup to emission Mössbauer spectroscopy as well as measurements under an applied magnetic field...
May 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/28560700/an-improved-design-of-optical-sensor-for-long-term-measurement-of-arterial-blood-flow-waveform
#5
Biljana Djurić, Slavica Suzić, Bojana Stojadinović, Zorica Nestorović, Marija Ivanović, Jelena Suzić-Lazić, Dejan Nešić, Sanja Mazić, Tamar Tenne, Dragoslav Zikich, Dejan Žikić
We present here the improved design and development of optical sensor for non-invasive measurements of arterial blood flow waveform. The sensor is based on a physical principle of reflective photoplethysmography (PPG). As the light source we used serially connected infrared diodes whereas NPN silicon phototransistors were used as light detectors. The electronic components were molded into square package and poured with silicone. Such preparation produced an elastic superficies that allowed excellent attachment of the sensor on the skin's surface...
September 2017: Biomedical Microdevices
https://www.readbyqxmd.com/read/28556261/technical-note-angular-dependence-of-a-2d-monolithic-silicon-diode-array-for-small-field-dosimetry
#6
Nauljun Stansook, Kananan Utitsarn, Marco Petasecca, Matthew K Newall, Mitchell Duncan, Kym Nitschke, Martin Carolan, Peter Metcalfe, Michael L F Lerch, Vladimir L Perevertaylo, Wolfgang A Tomé, Anatoly B Rosenfeld
PURPOSE: This study aims to investigate the 2D monolithic silicon diode array size of 52x52 mm(2) (MP512) angular response. An angular correction method has been developed that improves the accuracy of dose measurement in a small field. METHODS: The MP512 was placed at the center of a cylindrical phantom, irradiated using 6MV and 10MV photons and incrementing the incidence of the beam angle in 15° steps from 0° to 180°, and then in 1° steps between 85° to 95°...
May 27, 2017: Medical Physics
https://www.readbyqxmd.com/read/28534848/development-and-design-of-next-generation-head-mounted-ambulatory-microdose-positron-emission-tomography-am-pet-system
#7
Samantha Melroy, Christopher Bauer, Matthew McHugh, Garret Carden, Alexander Stolin, Stan Majewski, Julie Brefczynski-Lewis, Thorsten Wuest
Several applications exist for a whole brain positron-emission tomography (PET) brain imager designed as a portable unit that can be worn on a patient's head. Enabled by improvements in detector technology, a lightweight, high performance device would allow PET brain imaging in different environments and during behavioral tasks. Such a wearable system that allows the subjects to move their heads and walk-the Ambulatory Microdose PET (AM-PET)-is currently under development. This imager will be helpful for testing subjects performing selected activities such as gestures, virtual reality activities and walking...
May 19, 2017: Sensors
https://www.readbyqxmd.com/read/28531089/au-nanoparticle-decorated-silicon-pyramids-for-plasmon-enhanced-hot-electron-near-infrared-photodetection
#8
Zhiyang Qi, Yusheng Zhai, Long Wen, Qilong Wang, Qin Chen, Sami Iqbal, Guangdian Chen, Ji Xu, Yan Tu
The heterojunction between metal and silicon (Si) is an attractive route to extend the response of Si-based photodiodes into the near-infrared (NIR) region, so-called Schottky barrier diodes. Photons absorbed into a metallic nanostructure excite the surface plasmon resonances (SPRs), which can be damped non-radiatively through the creation of hot electrons. Unfortunately, the quantum efficiency of hot electron detectors remains low due to low optical absorption and poor electron injection efficiency. In this study, we propose an efficient and low-cost plasmonic hot electron NIR photodetector based on a Au nanoparticle (Au NP)-decorated Si pyramid Schottky junction...
May 22, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28508428/characterization-and-quantitation-of-pvp-content-in-a-silicone-hydrogel-contact-lens-produced-by-dual-phase-polymerization-processing
#9
Andrew J Hoteling, William F Nichols, Patricia S Harmon, Shawn M Conlon, Ivan M Nuñez, Joseph Hoff, Orlando M Cabarcos, Robert B Steffen, Daniel J Hook
Polyvinylpyrrolidone (PVP) has been incorporated over the years into numerous hydrogel contact lenses as both a primary matrix component and an internal wetting agent to increase lens wettability. In this study, complementary analytical techniques were used to characterize the PVP wetting agent component of senofilcon A and samfilcon A contact lenses, both in terms of chemical composition and amount present. Photo-differential scanning calorimetry (photo-DSC), gas chromatography with a flame ionization detector (GC-FID), and high-resolution/accurate mass (HR/AM) liquid chromatography-mass spectrometry (LC-MS) techniques confirmed dual phase reaction and curing of the samfilcon A silicone hydrogel material...
May 15, 2017: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
https://www.readbyqxmd.com/read/28504748/terahertz-multilevel-phase-fresnel-lenses-fabricated-by-laser-patterning-of-silicon
#10
L Minkevičius, S Indrišiūnas, R Šniaukas, B Voisiat, V Janonis, V Tamošiūnas, I Kašalynas, G Račiukaitis, G Valušis
Multilevel phase Fresnel lenses (MPFLs) with a high numerical aperture for 0.58 THz frequencies were developed. The components based on a monocrystalline silicon wafer are prepared by patterning by a high-speed industrial-scale laser direct writing (LDW) system. Two consistent series of the terahertz-MPFLs with phase quantization levels varying between 2 and the continuous kinoform shape for the focal lengths of 5 and 10 mm were produced employing inherent flexibility of the LDW fabrication process. The focusing performance was studied at the optimal 0...
May 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/28504244/mid-infrared-coincidence-measurements-on-twin-photons-at-room-temperature
#11
M Mancinelli, A Trenti, S Piccione, G Fontana, J S Dam, P Tidemand-Lichtenberg, C Pedersen, L Pavesi
Quantum measurements using single-photon detectors are opening interesting new perspectives in diverse fields such as remote sensing, quantum cryptography and quantum computing. A particularly demanding class of applications relies on the simultaneous detection of correlated single photons. In the visible and near infrared wavelength ranges suitable single-photon detectors do exist. However, low detector quantum efficiency or excessive noise has hampered their mid-infrared (MIR) counterpart. Fast and highly efficient single-photon detectors are thus highly sought after for MIR applications...
May 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28475491/open-field-mouse-brain-pet-design-optimisation-and-detector-characterisation
#12
Andre Z Kyme, Martin Judenhofer, Kuang Gong, Julien Bec, Aaron Selfridge, Junwei Du, Jinyi Qi, Simon Cherry, Steven Meikle
'Open-field' PET, where an animal can move freely during imaging, enables functional changes in the brain to be correlated with an animal's behavioural response to environmental or pharmacologic stimuli. Previously we showed the feasibility of this technique for rats by applying motion compensation techniques to a commercially available scanner. However, this approach is limited by the scanner's inherent geometric and performance constraints. The goal of this project is to develop a purpose-built open-field PET system, based on an innovative sliding tomograph concept, optimised for imaging the mouse brain...
May 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28473719/device-performance-enhancement-via-a-si-rich-silicon-oxynitride-buffer-layer-for-the-organic-photodetecting-device
#13
Sung Heo, Jooho Lee, Seong Heon Kim, Dong-Jin Yun, Jong-Bong Park, Kihong Kim, NamJeong Kim, Yongsung Kim, Dongwook Lee, Kyu-Sik Kim, Hee Jae Kang
An advanced organic photodetector (OPD) with a butter layer of Si-rich silicon oxynitride (SiOxNy) was fabricated. The detector structure is as follows: Indium tin oxide (ITO) coated glass substrate/SiOxNy(10 nm)/naphthalene-based donor:C60(1:1)/ITO. Values of x and y in SiOxNy were carefully controlled and the detector performances such as dark current and thermal stability were investigated. When the values of x and y are 0.16 and 0.66, the detector illustrates low dark current as well as excellent thermal stability...
May 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28450566/studies-of-a-next-generation-silicon-photomultiplier-based-time-of-flight-pet-ct-system
#14
David Fc Hsu, Ezgi Ilan, William T Peterson, Jorge Uribe, Mark Lubberink, Craig S Levin
This article presents system performance studies of the Discovery MI PET/CT system, a new time-of-flight (TOF) system based on silicon photomultipliers. System performance and clinical imaging comparisons were made between this next-generation system and other commercially available PET/CT and PET/MR systems, as well as between different reconstruction algorithms. Methods: Spatial resolution, sensitivity, NECR, scatter fraction, count rate accuracy, and image quality were characterized with the NEMA NU-2 2012 standards...
April 27, 2017: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
https://www.readbyqxmd.com/read/28447975/measurement-of-quantum-interference-in-a-silicon-ring-resonator-photon-source
#15
Jeffrey A Steidle, Michael L Fanto, Stefan F Preble, Christopher C Tison, Gregory A Howland, Zihao Wang, Paul M Alsing
Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit manipulation, and integrated single-photon detectors. Here, we present the key aspects of preparing and testing a silicon photonic quantum chip with an integrated photon source and two-photon interferometer. The most important aspect of an integrated quantum circuit is minimizing loss so that all of the generated photons are detected with the highest possible fidelity...
April 4, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28437926/demonstration-of-a-dual-mode-si-detector-as-a-self-calibrating-device-at-room-temperature
#16
Marit Ulset Nordsveen, Chi Kwong Tang, Jarle Gran
We demonstrate the use of a dual-mode detector for determining the internal quantum deficiency of a silicon photodiode without the use of an external reference. This is achieved by combining two different principles for measuring optical power in one device, where the photodiode is used as absorber for both thermal and photon detection. Thermal detection is obtained by the same principle as for an electrical substitution radiometer (ESR), with a type A measurement uncertainty of 0.34 % in unstabilized room temperature...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28430253/nanoscale-schottky-contact-surface-plasmon-point-detectors-for-optical-beam-scanning-applications
#17
Naema Othman, Pierre Berini
We propose and investigate a Schottky contact detector where the contact metal is a nanoscale metal stripe waveguide supporting surface plasmons with strong localization along the Schottky contact. We consider Au for the metal stripe, p-doped silicon for the semiconductor, operation in the infrared (at λ<sub>0</sub>=1550  nm), and internal photoemission as the sub-bandgap detection mechanism. We find that the main surface plasmon mode of operation of the Au stripe exhibits diverging real and imaginary parts of n<sub>eff</sub> with decreasing stripe dimensions, commensurate with increasing confinement...
April 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/28421602/the-qualitative-f-ratio-method-applied-to-electron-channelling-induced-x-ray-imaging-with-an-annular-silicon-drift-detector-in-a-scanning-electron-microscope-in-the-transmission-mode
#18
Nicolas Brodusch, Raynald Gauvin
Electron channelling is known to affect the x-ray production when an accelerated electron beam is applied to a crystalline material and is highly dependent on the local crystal orientation. This effect, unless very long counting time are used, is barely noticeable on x-ray energy spectra recorded with conventional silicon drift detectors (SDD) located at a small elevation angle. However, the very high count rates provided by the new commercially available annular SDDs permit now to observe this effect routinely and may, in some circumstances, hide the true elemental x-ray variations due to the local true specimen composition...
April 18, 2017: Journal of Microscopy
https://www.readbyqxmd.com/read/28406795/prototype-pre-clinical-pet-scanner-with-depth-of-interaction-measurements-using-single-layer-crystal-array-and-single-ended-readout
#19
Min Sun Lee, Kyeong Yun Kim, Guen Bae Ko, Jae Sung Lee
In this study, we developed a proof-of-concept prototype PET system using a pair of depth-of-interaction (DOI) PET detectors based on the proposed DOI-encoding method and digital silicon photomultiplier (dSiPM). Our novel cost-effective DOI measurement method is based on a triangular-shaped reflector that requires only a single-layer pixelated crystal and single-ended signal readout. The DOI detector consisted of an 18  ×  18 array of unpolished LYSO crystal (1.47  ×  1.47  ×  15 mm(3)) wrapped with triangular-shaped reflectors...
May 21, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28382312/highly-multiplexed-signal-readout-for-a-time-of-flight-positron-emission-tomography-detector-based-on-silicon-photomultipliers
#20
Joshua W Cates, Matthew F Bieniosek, Craig S Levin
Maintaining excellent timing resolution in the generation of silicon photomultiplier (SiPM)-based time-of-flight positron emission tomography (TOF-PET) systems requires a large number of high-speed, high-bandwidth electronic channels and components. To minimize the cost and complexity of a system's back-end architecture and data acquisition, many analog signals are often multiplexed to fewer channels using techniques that encode timing, energy, and position information. With progress in the development SiPMs having lower dark noise, after pulsing, and cross talk along with higher photodetection efficiency, a coincidence timing resolution (CTR) well below 200 ps FWHM is now easily achievable in single pixel, bench-top setups using 20-mm length, lutetium-based inorganic scintillators...
January 2017: Journal of Medical Imaging
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