Radiation tolerant design - theory and practice for proximity sensing

International Nuclear Information System (INIS)

Sharp, R.E.; Pater, S.L.; Cook, J.

1999-01-01

This paper provides a description of the radiation tolerant design process used to develop a range of proximity detectors with guaranteed total dose lifetime. It also describes some of the applications in which the detectors are being used and the benefits gained by plant operators. (authors)

Mitigating gas emissions at signalised intersections using wireless vehicle detectors

Directory of Open Access Journals (Sweden)

Moses Kwasi Torkudzor

2015-09-01

Full Text Available Traffic congestion on roads wastes travel times and increases fuel consumption as well as gas emissions which are dangerous to human health. This has led to growing concern about environmental protection and energy conservation and a number of studies to increase fuel economy and reduce gas emissions. To increase travel times so as to reduce fuel consumption and gas emissions, traffic signals at intersections must be well implemented. It is therefore necessary to employ the current technology of wireless sensor networks to enhance the optimisation of the signalised intersections so as to address such a concern. In this study, a vehicular traffic control model was developed to optimise a signalised intersection, using wireless vehicle detectors. Real-time traffic volume gathered were analysed to obtain the peak hour traffic volume causing congestion. The intersection was modelled and simulated in Synchro7 as an actuated signalised model using results from the analysed data. The model for morning peak and evening peak periods gave optimal cycle lengths which result in the reduction of gas emissions, fuel consumption and delay at the intersection.

Positron emission mammography with tomographic acquisition using dual planar detectors: initial evaluations

International Nuclear Information System (INIS)

Smith, Mark F; Raylman, Raymond R; Majewski, Stan; Weisenberger, Andrew G

2004-01-01

Positron emission mammography (PEM) with tomographic acquisition using dual planar detectors rotating about the breast can obtain complete angular sampling and has the potential to improve activity estimation compared with PEM using stationary detectors. PEM tomography (PEMT) was compared with stationary PEM for point source and compressed breast phantom studies performed with a compact dual detector system. The acquisition geometries were appropriate for the target application of PEM guidance of stereotactic core biopsy. Images were reconstructed with a three-dimensional iterative maximum likelihood expectation maximization algorithm. PEMT eliminated blurring normal to the detectors seen with stationary PEM. Depth of interaction effects distorted the shape of the point spread functions for PEMT as the angular range from normal incidence of lines of response used in image reconstruction increased. Streak artefacts in PEMT for large detector rotation increments led to the development of an expression for the maximum rotation increment that maintains complete angular sampling. Studies with a compressed breast phantom were used to investigate contrast and signal-to-noise ratio (SNR) trade-offs for different sized spherical tumour models. PEMT and PEM both had advantages depending on lesion size and detector separation. The most appropriate acquisition method for specific detection or quantitation tasks requires additional investigation

Development of analog solid-state photo-detectors for Positron Emission Tomography

International Nuclear Information System (INIS)

Bisogni, Maria Giuseppina; Morrocchi, Matteo

2016-01-01

Solid-state photo-detectors are one of the main innovations of past century in the field of sensors. First produced in the early forties with the invention of the p–n junction in silicon and the study of its optical properties, photo-detectors received a major boost in the sixties when the p-i-n (PIN) photodiode was developed and successfully used in several applications. The development of devices with internal gain, avalanche photodiodes (APD) first and then Geiger-mode avalanche photodiodes, named single photon avalanche diode (SPAD), leads to a substantial improvement in sensitivity and allowed single photon detection. Later on, thousands of SPADs have been assembled in arrays of few millimeters squared (named SiPM, silicon photo-multiplier) with single photon resolution. The high internal gain of SiPMs, together with other features peculiar of the silicon technology like compactness, speed and compatibility with magnetic fields, promoted SiPMs as the principal photo-detector competitor of photomultipliers in many applications from radiation detection to medical imaging. This paper provides a review of the properties of analog solid-state photo-detectors. Particular emphasis is given to latest advances on Positron Emission Tomography instrumentation boosted by the adoption of the silicon photo-detectors as an alternative to photomultiplier tubes (PMTs). Special attention is dedicated to the SiPMs, which are playing a key role in the development of innovative scanners.

Development of analog solid-state photo-detectors for Positron Emission Tomography

Energy Technology Data Exchange (ETDEWEB)

Bisogni, Maria Giuseppina, E-mail: giuseppina.bisogni@pi.infn.it; Morrocchi, Matteo

2016-02-11

Solid-state photo-detectors are one of the main innovations of past century in the field of sensors. First produced in the early forties with the invention of the p–n junction in silicon and the study of its optical properties, photo-detectors received a major boost in the sixties when the p-i-n (PIN) photodiode was developed and successfully used in several applications. The development of devices with internal gain, avalanche photodiodes (APD) first and then Geiger-mode avalanche photodiodes, named single photon avalanche diode (SPAD), leads to a substantial improvement in sensitivity and allowed single photon detection. Later on, thousands of SPADs have been assembled in arrays of few millimeters squared (named SiPM, silicon photo-multiplier) with single photon resolution. The high internal gain of SiPMs, together with other features peculiar of the silicon technology like compactness, speed and compatibility with magnetic fields, promoted SiPMs as the principal photo-detector competitor of photomultipliers in many applications from radiation detection to medical imaging. This paper provides a review of the properties of analog solid-state photo-detectors. Particular emphasis is given to latest advances on Positron Emission Tomography instrumentation boosted by the adoption of the silicon photo-detectors as an alternative to photomultiplier tubes (PMTs). Special attention is dedicated to the SiPMs, which are playing a key role in the development of innovative scanners.

Detector response restoration in image reconstruction of high resolution positron emission tomography

International Nuclear Information System (INIS)

Liang, Z.

1994-01-01

A mathematical method was studied to model the detector response of high spatial-resolution positron emission tomography systems consisting of close-packed small crystals, and to restore the resolution deteriorated due to crystal penetration and/or nonuniform sampling across the field-of-view (FOV). The simulated detector system had 600 bismuth germanate crystals of 3.14 mm width and 30 mm length packed on a single ring of 60 cm diameter. The space between crystal was filled up with lead. Each crystal was in coincidence with 200 opposite crystals so that the FOV had a radius of 30 cm. The detector response was modeled based on the attenuating properties of the crystals and the septa, as well as the geometry of the detector system. The modeled detector-response function was used to restore the projections from the sinogram of the ring-detector system. The restored projections had a uniform sampling of 1.57 mm across the FOV. The crystal penetration and/or the nonuniform sampling were compensated in the projections. A penalized maximum-likelihood algorithm was employed to accomplish the restoration. The restored projections were then filtered and backprojected to reconstruct the image. A chest phantom with a few small circular ''cold'' objects located at the center and near the periphery of FOV was computer generated and used to test the restoration. The reconstructed images from the restored projections demonstrated resolution improvement off the FOV center, while preserving the resolution near the center

Development of a Cryogenic Radiation Detector for Mapping Radio Frequency Superconducting Cavity Field Emissions

CERN Document Server

Dotson, Danny W

2005-01-01

There is a relationship between field emissions in a Super Conducting RF cavity and the production of radiation (mostly X-rays). External (room temperature) detectors are shielded from the onset of low energy X-rays by the vacuum and cryogenic stainless steel module walls. An internal measuring system for mapping field emissions would assist scientists and engineers in perfecting surface deposition and acid washing module surfaces. Two measurement systems are undergoing cryogenic testing at JLab. One is an active CsI photodiode array and the second is an X-ray film camera. The CsI array has operated sucessfully in a cavity in liquid Helium but saturated at higher power due to scattering in the cavity. A shield with an aperature similar to the X-ray film detector is being designed for the next series of tests which will be completed before PAC-05.

Towards Quantum Experiments with Human Eyes as Detectors Based on Cloning via Stimulated Emission

Science.gov (United States)

Sekatski, Pavel; Brunner, Nicolas; Branciard, Cyril; Gisin, Nicolas; Simon, Christoph

2009-09-01

We show theoretically that a large Bell inequality violation can be obtained with human eyes as detectors, in a “micro-macro” experiment where one photon from an entangled pair is greatly amplified via stimulated emission. The violation is robust under photon loss. This leads to an apparent paradox, which we resolve by noting that the violation proves the existence of entanglement before the amplification. The same is true for the micro-macro experiments performed so far with conventional detectors. However, we also prove that there is genuine micro-macro entanglement even for high loss.

Evaluation of scintillators and semiconductor detectors to image three-photon positron annihilation for positron emission tomography

International Nuclear Information System (INIS)

Abuelhia, E.; Spyrou, N.M.; Kacperski, K.; College University, Middlesex Hospital, London

2008-01-01

Positron emission tomography (PET) is rapidly becoming the main nuclear imaging modality of the present century. The future of PET instrumentation relies on semiconductor detectors because of their excellent characteristics. Three-photon positron annihilation has been recently investigated as a novel imaging modality, which demands the crucial high energy resolution of semiconductor detector. In this work the evaluation of the NaI(Tl) scintillator and HPGe and CdZTe semiconductor detectors, to construct a simple three-photon positron annihilation scanner has been explored. The effect of detector and scanner size on spatial resolution (FWHM) is discussed. The characteristics: energy resolution versus count rate and point-spread function of the three-photon positron annihilation image profile from triple coincidence measurements were investigated. (author)

Finite-element modeling of spontaneous emission of a quantum emitter at nanoscale proximity to plasmonic waveguides

DEFF Research Database (Denmark)

Chen, Yuntian; Nielsen, Torben Roland; Gregersen, Niels

2010-01-01

of the plasmonic waveguide can be arbitrary. The fraction of the energy coupled to the plasmonic mode can be calculated exactly, which can be used to determine the efficiency with which single optical plasmons are generated. We apply our numerical method to calculate the coupling of a quantum emitter......We develop a self-consistent finite-element method to quantitatively study spontaneous emission from emitters in nanoscale proximity of plasmonic waveguides. In the model, it is assumed that only one guided mode is dominatingly excited by the quantum emitter, while the cross section...

Proximal methods for the resolution of inverse problems: application to positron emission tomography

International Nuclear Information System (INIS)

Pustelnik, N.

2010-12-01

The objective of this work is to propose reliable, efficient and fast methods for minimizing convex criteria, that are found in inverse problems for imagery. We focus on restoration/reconstruction problems when data is degraded with both a linear operator and noise, where the latter is not assumed to be necessarily additive.The reliability of the method is ensured through the use of proximal algorithms, the convergence of which is guaranteed when a convex criterion is considered. Efficiency is sought through the choice of criteria adapted to the noise characteristics, the linear operators and the image specificities. Of particular interest are regularization terms based on total variation and/or sparsity of signal frame coefficients. As a consequence of the use of frames, two approaches are investigated, depending on whether the analysis or the synthesis formulation is chosen. Fast processing requirements lead us to consider proximal algorithms with a parallel structure. Theoretical results are illustrated on several large size inverse problems arising in image restoration, stereoscopy, multi-spectral imagery and decomposition into texture and geometry components. We focus on a particular application, namely Positron Emission Tomography (PET), which is particularly difficult because of the presence of a projection operator combined with Poisson noise, leading to highly corrupted data. To optimize the quality of the reconstruction, we make use of the spatio-temporal characteristics of brain tissue activity. (author)

Radiation emitter-detector package

International Nuclear Information System (INIS)

O'Brien, J.T.; Limm, A.C.; Nyul, P.; Tassia, V.S. Jr.

1978-01-01

Mounted on the metallic base of a radiation emitter-detector is a mounting block is a first projection, and a second projection. A radiation detector is on the first projection and a semiconductor electroluminescent device, i.e., a radiation emitter, is on the second projection such that the plane of the recombination region of the electroluminescent device is perpendicular to the radiation incident surface of the radiation detector. The electroluminescent device has a primary emission and a secondary emission in a direction different from the primary emission. A radiation emitter-detector package as described is ideally suited to those applications wherein the secondary radiation of the electroluminescent device is fed into a feedback circuit regulating the biasing current of the electroluminescent device

Handheld emissions detector (HED): overview and development

Science.gov (United States)

Valentino, George J.; Schimmel, David

2009-05-01

Nova Engineering, Cincinnati OH, a division of L-3 Communications (L-3 Nova), under the sponsorship of Program Manager Soldier Warrior (PM-SWAR), Fort Belvoir, VA, has developed a Soldier portable, light-weight, hand-held, geolocation sensor and processing system called the Handheld Emissions Detector (HED). The HED is a broadband custom receiver and processor that allows the user to easily sense, direction find, and locate a broad range of emitters in the user's surrounding area. Now in its second design iteration, the HED incorporates a set of COTS components that are complemented with L-3 Nova custom RF, power, digital, and mechanical components, plus custom embedded and application software. The HED user interfaces are designed to provide complex information in a readily-understandable form, thereby providing actionable results for operators. This paper provides, where possible, the top-level characteristics of the HED as well as the rationale behind its design philosophy along with its applications in both DOD and Commercial markets.

Superiority of triple-detector single-photon emission tomography over single- and dual-detector systems in the minimization of motion artefacts

International Nuclear Information System (INIS)

Nakajima, Kenichi; Taki, Junichi; Michigishi, Takatoshi; Tonami, Norihisa

1998-01-01

A patient motion-related artefact is one of the most important artefacts in single-photon emission tomography (SPET) imaging. This study evaluated the effect of the number and configuration of SPET detectors on motion artefacts. The following acquisition conditions were simulated based on original 360 projection images: (1) single-detector 180 rotation (S180), (2) a dual-detector rectangular (L-shaped) 180 acquisition (D180L), (3) dual-detector cameras mounted opposite each other with 360 acquisition (D360) and (4) triple-detector 360 acquisition (T360). The motion artefacts were introduced using a syringe and a myocardial phantom. Clinical cases with technetium-99m methoxyisobutylisonitrile and thallium-201 studies were analysed to confirm the validity of this phantom simulation. The effect of continuous alternate rotation acquisition and summing the projections on the reduction of motion artefacts was investigated in each model. The effect of motion depended on the number and the configuration of the SPET detectors. A 1-pixel (6.4 mm) motion in the S180, D180L and D360 models generated only slight artefacts, and a 2-pixel motion led to an apparent decrease in activity or created hot areas in the myocardium. On the other hand, a T360 rotation created few artefacts even with a 2-pixel motion of the last quarter of the projections. Despite the difference in attenuation with 201 Tl and 99m Tc, similar artefact patterns were observed with both radionuclides in selected patient model studies. Continuous alternate rotation could reduce artefacts caused by less than a 2-pixel motion. In conclusion, calculating the average of the sum of the projections of triple-detector 360 rotations with alternate rotation is the best method to minimize motion artefacts. This ''averaging'' effect of motion artefacts is a key to this simulation. (orig.)

Limits on neutrino emission from gamma-ray bursts with the 40 string IceCube detector.

Science.gov (United States)

Abbasi, R; Abdou, Y; Abu-Zayyad, T; Adams, J; Aguilar, J A; Ahlers, M; Andeen, K; Auffenberg, J; Bai, X; Baker, M; Barwick, S W; Bay, R; Bazo Alba, J L; Beattie, K; Beatty, J J; Bechet, S; Becker, J K; Becker, K-H; Benabderrahmane, M L; BenZvi, S; Berdermann, J; Berghaus, P; Berley, D; Bernardini, E; Bertrand, D; Besson, D Z; Bindig, D; Bissok, M; Blaufuss, E; Blumenthal, J; Boersma, D J; Bohm, C; Bose, D; Böser, S; Botner, O; Braun, J; Brown, A M; Buitink, S; Carson, M; Chirkin, D; Christy, B; Clem, J; Clevermann, F; Cohen, S; Colnard, C; Cowen, D F; D'Agostino, M V; Danninger, M; Daughhetee, J; Davis, J C; De Clercq, C; Demirörs, L; Depaepe, O; Descamps, F; Desiati, P; de Vries-Uiterweerd, G; DeYoung, T; Díaz-Vélez, J C; Dierckxsens, M; Dreyer, J; Dumm, J P; Ehrlich, R; Eisch, J; Ellsworth, R W; Engdegård, O; Euler, S; Evenson, P A; Fadiran, O; Fazely, A R; Fedynitch, A; Feusels, T; Filimonov, K; Finley, C; Fischer-Wasels, T; Foerster, M M; Fox, B D; Franckowiak, A; Franke, R; Gaisser, T K; Gallagher, J; Geisler, M; Gerhardt, L; Gladstone, L; Glüsenkamp, T; Goldschmidt, A; Goodman, J A; Grant, D; Griesel, T; Gross, A; Grullon, S; Gurtner, M; Ha, C; Hallgren, A; Halzen, F; Han, K; Hanson, K; Heinen, D; Helbing, K; Herquet, P; Hickford, S; Hill, G C; Hoffman, K D; Homeier, A; Hoshina, K; Hubert, D; Huelsnitz, W; Hülss, J-P; Hulth, P O; Hultqvist, K; Hussain, S; Ishihara, A; Jacobsen, J; Japaridze, G S; Johansson, H; Joseph, J M; Kampert, K-H; Kappes, A; Karg, T; Karle, A; Kelley, J L; Kemming, N; Kenny, P; Kiryluk, J; Kislat, F; Klein, S R; Köhne, J-H; Kohnen, G; Kolanoski, H; Köpke, L; Kopper, S; Koskinen, D J; Kowalski, M; Kowarik, T; Krasberg, M; Krings, T; Kroll, G; Kuehn, K; Kuwabara, T; Labare, M; Lafebre, S; Laihem, K; Landsman, H; Larson, M J; Lauer, R; Lehmann, R; Lünemann, J; Madsen, J; Majumdar, P; Marotta, A; Maruyama, R; Mase, K; Matis, H S; Meagher, K; Merck, M; Mészáros, P; Meures, T; Middell, E; Milke, N; Miller, J; Montaruli, T; Morse, R; Movit, S M; Nahnhauer, R; Nam, J W; Naumann, U; Niessen, P; Nygren, D R; Odrowski, S; Olivas, A; Olivo, M; O'Murchadha, A; Ono, M; Panknin, S; Paul, L; Pérez de los Heros, C; Petrovic, J; Piegsa, A; Pieloth, D; Porrata, R; Posselt, J; Price, P B; Prikockis, M; Przybylski, G T; Rawlins, K; Redl, P; Resconi, E; Rhode, W; Ribordy, M; Rizzo, A; Rodrigues, J P; Roth, P; Rothmaier, F; Rott, C; Ruhe, T; Rutledge, D; Ruzybayev, B; Ryckbosch, D; Sander, H-G; Santander, M; Sarkar, S; Schatto, K; Schmidt, T; Schoenwald, A; Schukraft, A; Schultes, A; Schulz, O; Schunck, M; Seckel, D; Semburg, B; Seo, S H; Sestayo, Y; Seunarine, S; Silvestri, A; Slipak, A; Spiczak, G M; Spiering, C; Stamatikos, M; Stanev, T; Stephens, G; Stezelberger, T; Stokstad, R G; Stoyanov, S; Strahler, E A; Straszheim, T; Sullivan, G W; Swillens, Q; Taavola, H; Taboada, I; Tamburro, A; Tarasova, O; Tepe, A; Ter-Antonyan, S; Tilav, S; Toale, P A; Toscano, S; Tosi, D; Turčan, D; van Eijndhoven, N; Vandenbroucke, J; Van Overloop, A; van Santen, J; Vehring, M; Voge, M; Voigt, B; Walck, C; Waldenmaier, T; Wallraff, M; Walter, M; Weaver, C; Wendt, C; Westerhoff, S; Whitehorn, N; Wiebe, K; Wiebusch, C H; Williams, D R; Wischnewski, R; Wissing, H; Wolf, M; Woschnagg, K; Xu, C; Xu, X W; Yodh, G; Yoshida, S; Zarzhitsky, P

2011-04-08

IceCube has become the first neutrino telescope with a sensitivity below the TeV neutrino flux predicted from gamma-ray bursts if gamma-ray bursts are responsible for the observed cosmic-ray flux above 10(18)  eV. Two separate analyses using the half-complete IceCube detector, one a dedicated search for neutrinos from pγ interactions in the prompt phase of the gamma-ray burst fireball and the other a generic search for any neutrino emission from these sources over a wide range of energies and emission times, produced no evidence for neutrino emission, excluding prevailing models at 90% confidence.

Design and evaluation of a SiPM-based large-area detector module for positron emission imaging

Science.gov (United States)

Alva-Sánchez, H.; Murrieta-Rodríguez, T.; Calva-Coraza, E.; Martínez-Dávalos, A.; Rodríguez-Villafuerte, M.

2018-03-01

The design and evaluation of a large-area detector module for positron emission imaging applications, is presented. The module features a SensL ArrayC-60035-64P-PCB solid state detector (8×8 array of tileable silicon photomultipliers by SensL, 7.2 mm pitch) covering a total area of 57.4×57.4 mm2. The detector module was formed using a pixelated array of 40×40 lutetium-yttrium oxyorthosilicate (LYSO) scintillator crystal elements with 1.43 mm pitch. A 7 mm thick coupling light guide was used to allow light sharing between adjacent SiPM. A 16-channel symmetric charge division (SCD) readout board was designed to multiplex the number of signals from 64 to 16 (8 columns and 8 rows) and a center-of-gravity algorithm to identify the position. Data acquisition and digitization was accomplished using a custom-made system based on FPGAs boards. Crystal maps were obtained using 18F-positron sources and Voronoi diagrams were used to correct for geometric distortions and to generate a non-uniformity correction matrix. All measurements were taken at a controlled room temperature of 22oC. The crystal maps showed minor distortion, 90% of the 1600 total crystal elements could be identified, a mean peak-to-valley ratio of 4.3 was obtained and a 10.8% mean energy resolution for 511 keV annihilation photons was determined. The performance of the detector using our own readout board was compared to that using two different commercially readout boards using the same detector module arrangement. We show that these large-area SiPM arrays, combined with a 16-channel SCD readout board, can offer high spatial resolution, excellent energy resolution and detector uniformity and thus, can be used for positron emission imaging applications.

Silicon photomultiplier as a detector of Cherenkov photons

International Nuclear Information System (INIS)

Korpar, S.; Dolenec, R.; Hara, K.; Iijima, T.; Krizan, P.; Mazuka, Y.; Pestotnik, R.; Stanovnik, A.; Yamaoka, M.

2008-01-01

A novel photon detector-i.e. the silicon photomultiplier-whose main advantage over conventional photomultiplier tubes is the operation in high magnetic fields, has been tested as a photon detector in a proximity focusing RICH with aerogel radiator. This type of RICH counter is proposed for the upgrade of the Belle detector at the KEK B-factory. Recently produced silicon photomultipliers show less noise and have larger size, which are important issues for a large area photon detector. We measured the single photon pulse height distribution, the timing resolution and the position sensitivity for different silicon photomultipliers (Hamamatsu MPPC HC025, HC050, and HC100). The silicon photomultipliers were then used to detect Cherenkov photons emitted by cosmic ray particles in a proximity focusing aerogel RICH. Various light guides were investigated in order to increase the detection efficiency

Initial characterization of a BGO-photodiode detector for high resolution positron emission tomography

International Nuclear Information System (INIS)

Derenzo, S.E.

1983-11-01

Spatial resolution in positron emission tomography is currently limited by the resolution of the detectors. This work presents the initial characterization of a detector design using small bismuth germanate (BGO) crystals individually coupled to silicon photodiodes (SPDs) for crystal identification, and coupled in groups to phototubes (PMTs) for coincidence timing. A 3 mm x 3 mm x 3 mm BGO crystal coupled only to an SPD can achieve a 511 keV photopeak resolution of 8.7% FWHM at -150 0 C, using a pulse peaking time of 10 μs. When two 3 mm x 3 mm x 15 mm BGO crystals are coupled individually to SPDs and also coupled to a common 14 mm diam PMT, the SPDs detect the 511 keV photopeak with a resolution of 30% FWHM at -76 0 C. In coincidence with an opposing 3 mm wide BGO crystal, the SPDs are able to identify the crystal of interaction with good signal-to-noise ratio, and the detector pair resolution is 2 mm FWHM. 32 references, 7 figures, 3 tables

Noninvasive xenon-133 measurements of cerebral blood flow using stationary detectors compared with dynamic emission tomography

DEFF Research Database (Denmark)

Schroeder, T; Vorstrup, S; Lassen, N A

1986-01-01

the stationary detectors yielded somewhat lower CBF values than did emission tomography. Considering the side-to-side asymmetry, an excellent correlation was obtained. Using the initial slope index, the stationary detectors revealed quantitatively 83% of the interhemispheric asymmetry and 63% of the asymmetry...... in the middle cerebral artery territory shown with the tomograph. As illustrated by a case history, the nontomographic CBF unit used in this study may provide reliable and useful information in patients with occlusive cerebrovascular disease by performing repeated CBF studies and challenging the cerebral...

Coakial gamma ray detector and method therefor

International Nuclear Information System (INIS)

Harchol, M.

1977-01-01

A coaxial gamma ray detector is fabricated using intrinsic Ge semiconductor material in a geometry whereby full depletion of electrical carriers is prevented within a small region proximate the point of electrical contact thereby allowing greater biasing potentials across the detector and, consequently, providing reduced electronic noise and increased energy resolution

Positron emission tomography with additional γ-ray detectors for multiple-tracer imaging.

Science.gov (United States)

Fukuchi, Tomonori; Okauchi, Takashi; Shigeta, Mika; Yamamoto, Seiichi; Watanabe, Yasuyoshi; Enomoto, Shuichi

2017-06-01

Positron emission tomography (PET) is a useful imaging modality that quantifies the physiological distributions of radiolabeled tracers in vivo in humans and animals. However, this technique is unsuitable for multiple-tracer imaging because the annihilation photons used for PET imaging have a fixed energy regardless of the selection of the radionuclide tracer. This study developed a multi-isotope PET (MI-PET) system and evaluated its imaging performance. Our MI-PET system is composed of a PET system and additional γ-ray detectors. The PET system consists of pixelized gadolinium orthosilicate (GSO) scintillation detectors and has a ring geometry that is 95 mm in diameter with an axial field of view of 37.5 mm. The additional detectors are eight bismuth germanium oxide (BGO) scintillation detectors, each of which is 50 × 50 × 30 mm 3 , arranged into two rings mounted on each side of the PET ring with a 92-mm-inner diameter. This system can distinguish between different tracers using the additional γ-ray detectors to observe prompt γ-rays, which are emitted after positron emission and have an energy intrinsic to each radionuclide. Our system can simultaneously acquire double- (two annihilation photons) and triple- (two annihilation photons and a prompt γ-ray) coincidence events. The system's efficiency for detecting prompt de-excitation γ-rays was measured using a positron-γ emitter, 22 Na. Dual-radionuclide ( 18 F and 22 Na) imaging of a rod phantom and a mouse was performed to demonstrate the performance of the developed system. Our system's basic performance was evaluated by reconstructing two images, one containing both tracers and the other containing just the second tracer, from list-mode data sets that were categorized by the presence or absence of the prompt γ-ray. The maximum detection efficiency for 1275 keV γ-rays emitted from 22 Na was approximately 7% at the scanner's center, and the minimum detection efficiency was 5.1% at the edge of

Secondary emission detectors for fixed target experiments at Fermilab

International Nuclear Information System (INIS)

Drucker, R.; Ford, R.; Tassotto, G.

1998-02-01

A description of a Secondary Emission Electron Detector (SEED) is given. The SEEDs provide accurate profiles and positions at small wire spacing (125-500 mm) in a high energy, high rate environment that exceeds the capabilities of traditional segmented wire ion chambers (SWICs). This device has been designed and constructed to monitor beam position and profile of two fixed target beamlines, namely, KTeV (FNAL E-799, E-832) with an average beam sigma at target of 0.22 mm and NuTeV (FNAL E-815) with a sigma = 0.6 mm. KTeV took beam at an intensity of up to 5E12 800 GeV protons over a 20 sec spill and NuTeV received 1E13 800 GeV protons in five pings/spill

Data acquisition electronics for positron emission mammography (PEM) detectors

International Nuclear Information System (INIS)

Martinez, J.D.; Sebastia, A.; Cerda, J.; Esteve, R.; Mora, F.J.; Toledo, J.F.; Benlloch, J.M.; Gimenez, N.; Gimenez, M.; Lerche, Ch. W.; Pavon, N.; Sanchez, F.

2005-01-01

Positron emission mammography (PEM) is an innovative technique to increase sensitivity and overcome the main drawbacks of conventional X-ray screening. However, dedicated PET imaging systems demand specific hardware solutions for data acquisition and processing that can take advantage of the reduction in the number of channels. Data acquisition issues can affect PEM scanners performance and they should be exhaustively addressed in order to exploit the increment in the event count rate. This is crucial in order to reduce both the scanning time and the total injected dose. This paper presents the electronics for our PEM camera prototype that enables us to achieve very high-count rates and perform comprehensive online processing. Results about acquisition in our detector for a typical clinical setup are studied using Monte Carlo simulation of hot lesion phantoms

Novel Electro-Optical Coupling Technique for Magnetic Resonance-Compatible Positron Emission Tomography Detectors

Directory of Open Access Journals (Sweden)

Peter D. Olcott

2009-03-01

Full Text Available A new magnetic resonance imaging (MRI-compatible positron emission tomography (PET detector design is being developed that uses electro-optical coupling to bring the amplitude and arrival time information of high-speed PET detector scintillation pulses out of an MRI system. The electro-optical coupling technology consists of a magnetically insensitive photodetector output signal connected to a nonmagnetic vertical cavity surface emitting laser (VCSEL diode that is coupled to a multimode optical fiber. This scheme essentially acts as an optical wire with no influence on the MRI system. To test the feasibility of this approach, a lutetium-yttrium oxyorthosilicate crystal coupled to a single pixel of a solid-state photomultiplier array was placed in coincidence with a lutetium oxyorthosilicate crystal coupled to a fast photomultiplier tube with both the new nonmagnetic VCSEL coupling and the standard coaxial cable signal transmission scheme. No significant change was observed in 511 keV photopeak energy resolution and coincidence time resolution. This electro-optical coupling technology enables an MRI-compatible PET block detector to have a reduced electromagnetic footprint compared with the signal transmission schemes deployed in the current MRI/PET designs.

Novel electro-optical coupling technique for magnetic resonance-compatible positron emission tomography detectors.

Science.gov (United States)

Olcott, Peter D; Peng, Hao; Levin, Craig S

2009-01-01

A new magnetic resonance imaging (MRI)-compatible positron emission tomography (PET) detector design is being developed that uses electro-optical coupling to bring the amplitude and arrival time information of high-speed PET detector scintillation pulses out of an MRI system. The electro-optical coupling technology consists of a magnetically insensitive photodetector output signal connected to a nonmagnetic vertical cavity surface emitting laser (VCSEL) diode that is coupled to a multimode optical fiber. This scheme essentially acts as an optical wire with no influence on the MRI system. To test the feasibility of this approach, a lutetium-yttrium oxyorthosilicate crystal coupled to a single pixel of a solid-state photomultiplier array was placed in coincidence with a lutetium oxyorthosilicate crystal coupled to a fast photomultiplier tube with both the new nonmagnetic VCSEL coupling and the standard coaxial cable signal transmission scheme. No significant change was observed in 511 keV photopeak energy resolution and coincidence time resolution. This electro-optical coupling technology enables an MRI-compatible PET block detector to have a reduced electromagnetic footprint compared with the signal transmission schemes deployed in the current MRI/PET designs.

Contamination detector for inner surface of container

International Nuclear Information System (INIS)

Watanabe, Tadao.

1995-01-01

The present invention concerns a device for detecting contamination of radioactive materials on the inner surface of a vessel upon reutilizing the vessel for containing solidified radioactive wastes and transporting them. Namely, the detecting device has following functions. (1) A radiation detector detects the radioactive materials on the inner surface of the vessel. (2) A plurality of proximity switches measure the distance from the radiation detector to the wall surface of the vessel and are actuated if the distance is decreased to a predetermined value, (3) A vessel inner surface position calculation mechanism calculates the position of the inner surface of the vessel based on the information from a direction indicator and a height indicator. (4) A frontal limit detector detects the limit for allowing the radiation detector to proceed. (5) A vessel inner shape judging mechanism for judging the shape of the inner side of the vessel based on the signals from the proximity switches in a state where the frontal limit detector is operated and a vessel inner surface position signal outputted from the vessel inner surface position calculation mechanism. As a result, the shape of the inner side of the vessel can accurately be recognized, thereby improving accuracy of radiation measurement. (I.S.)

Basic Radiation Detectors. Chapter 6

Energy Technology Data Exchange (ETDEWEB)

Van Eijk, C. W.E. [Faculty of Applied Sciences, Delft University of Technology, Delft (Netherlands)

2014-12-15

Radiation detectors are of paramount importance in nuclear medicine. The detectors provide a wide range of information including the radiation dose of a laboratory worker and the positron emission tomography (PET) image of a patient. Consequently, detectors with strongly differing specifications are used. In this chapter, general aspects of detectors are discussed.

First delayed neutron emission measurements at ALTO with the neutron detector TETRA

International Nuclear Information System (INIS)

Testov, D.; Ancelin, S.; Bettane, J.; Ibrahim, F.; Kolos, K.; Mavilla, G.; Niikura, M.; Verney, D.; Wilson, J.; Kuznetsova, E.; Penionzhkevich, Yu.; Smirnov, V.; Sokol, E.

2013-01-01

Beta-decay properties are among the easiest and, therefore, the first ones to be measured to study new neutron-rich isotopes. Eventually, a very small number of nuclei could be sufficient to estimate their lifetime and neutron emission probability. With the new radioactive beam facilities which have been commissioned recently (or will be constructed shortly) new areas of neutron-rich isotopes will become reachable. To study beta-decay properties of such nuclei at IPN (Orsay) in the framework of collaboration with JINR (Dubna), a new experimental setup including the neutron detector of high efficiency TETRA was developed and commissioned

Proximal sensing for soil carbon accounting

Science.gov (United States)

England, Jacqueline R.; Viscarra Rossel, Raphael A.

2018-05-01

Maintaining or increasing soil organic carbon (C) is vital for securing food production and for mitigating greenhouse gas (GHG) emissions, climate change, and land degradation. Some land management practices in cropping, grazing, horticultural, and mixed farming systems can be used to increase organic C in soil, but to assess their effectiveness, we need accurate and cost-efficient methods for measuring and monitoring the change. To determine the stock of organic C in soil, one requires measurements of soil organic C concentration, bulk density, and gravel content, but using conventional laboratory-based analytical methods is expensive. Our aim here is to review the current state of proximal sensing for the development of new soil C accounting methods for emissions reporting and in emissions reduction schemes. We evaluated sensing techniques in terms of their rapidity, cost, accuracy, safety, readiness, and their state of development. The most suitable method for measuring soil organic C concentrations appears to be visible-near-infrared (vis-NIR) spectroscopy and, for bulk density, active gamma-ray attenuation. Sensors for measuring gravel have not been developed, but an interim solution with rapid wet sieving and automated measurement appears useful. Field-deployable, multi-sensor systems are needed for cost-efficient soil C accounting. Proximal sensing can be used for soil organic C accounting, but the methods need to be standardized and procedural guidelines need to be developed to ensure proficient measurement and accurate reporting and verification. These are particularly important if the schemes use financial incentives for landholders to adopt management practices to sequester soil organic C. We list and discuss requirements for developing new soil C accounting methods based on proximal sensing, including requirements for recording, verification, and auditing.

Simulation study of a depth-encoding positron emission tomography detector inserting horizontal-striped glass between crystal layers

Science.gov (United States)

Kim, Kyu Bom; Choi, Yong; Kang, Jihoon

2017-10-01

This study introduces a depth-encoding positron emission tomography (PET) detector inserting a horizontal-striped glass between the pixilated scintillation crystal layers. This design allows light spreading so that scintillation photons can travel only through the X direction and allows alteration in the light distribution so that it can generate a unique pattern diagram of the two-dimensional (2-D) flood histogram that identifies depth position as well as X-Y position of γ-ray interaction. A Monte Carlo simulation was conducted for the assessment of the depth of interaction (DOI)-PET detector. The traced light distribution for each event was converted into the 2-D flood histogram. Light loss caused by inserting the horizontal-striped glass between the crystal layers was estimated. Applicable weighting factors were examined for each DOI-PET detector. No considerable degradation of light loss was observed. The flood histogram, without overlapping of each crystal position, can be generated for the DOI detector based on each crystal block by inserting the horizontal-striped glass with a thickness of >1 mm and the modified resistive charge division networks with applicable weighting factors. This study demonstrated that the proposed DOI-PET detector can extract the three-dimensional γ-ray interaction position without considerable performance degradations of the PET detector from the 2-D flood histogram.

Multi-angle gas and Si detector particle telescope

International Nuclear Information System (INIS)

McDonald, R.J.; Sobotka, L.G.; Wozniak, G.J.

1984-01-01

A simple gas ΔE and multiple Si E detector telescope (called a WEDGE detector) has been constructed, which is particularly suitable for angular distribution studies of light ion emission from fragments following heavy ion reactions. This inexpensive detector was designed to have a low detection threshold, large dynamic range and constant ΔE path length. The detector has been used in studies of complex fragment emission (typically 2 < Z < 10) following compound nucleus and deep-inelastic heavy ion reactions

Silicon photomultipliers for positron emission tomography detectors with depth of interaction encoding capability

International Nuclear Information System (INIS)

Taghibakhsh, Farhad; Reznik, Alla; Rowlands, John A.

2011-01-01

Silicon photomultipliers (SiPMs) are receiving increasing attention in the field of positron emission tomography (PET) detectors. Compared to photomultiplier tubes, they offer novel detector configurations for the extraction of depth of interaction (DOI) information, or enable emerging medical imaging modalities such as simultaneous PET-magnetic resonant imaging (MRI). In this article, we used 2x2x20 mm 3 LYSO scintillator crystals coupled to SiPMs on both ends (dual-ended readout configuration) to evaluate the detector performance for DOI-PET applications. We investigated the effect of scintillator crystal surface finishing on sensitivity and resolution of DOI, as well as on energy and timing resolution. Measurements indicate DOI sensitivity and resolution of 7.1% mm -1 and 2.1±0.6 mm for saw-cut, and 1.3% mm -1 and 9.0±1.5 mm, for polished scintillator crystals, respectively. Energy resolution varies from 19% when DOI is in the center, to 15% with DOI at either end of the saw-cut crystal, while it remains constant at ∼14% for polished scintillators. Based on our results we conclude that 2x2x20 mm 3 saw-cut (without any special side wall polishing) LYSO crystals coupled to 2x2 mm 2 silicon photomultipliers are optimal for isotropic 2 mm resolution DOI-PET applications.

Evaluation Of Silicon Diodes As IN-SITU Cryogenic Field Emission Detectors For SRF Cavity Development

International Nuclear Information System (INIS)

Palczewski, Ari; Geng, Rongli

2012-01-01

We performed in-situ cryogenic testing of four silicon diodes as possible candidates for field emission (FE) monitors of superconducting radio frequency (SRF) cavities during qualification testing and in accelerator cryo-modules. We evaluated diodes from 2 companies - from Hamamatsu corporation model S1223-01; and from OSI Optoelectronics models OSD35-LR-A, XUV-50C, and FIL-UV20. The measurements were done by placing the diodes in superfluid liquid helium near the top of a field emitting 9-cell cavity during its vertical test. For each diode, we will discuss their viability as a 2K cryogenic detector for FE mapping of SRF cavities and the directionality of S1223-01 in such environments. We will also present calibration curves between the diodes and JLab's standard radiation detector placed above the Dewar's top plate.

Noble Gas Detectors

CERN Document Server

Aprile, Elena; Bolozdynya, Alexander I; Doke, Tadayoshi

2006-01-01

This book discusses the physical properties of noble fluids, operational principles of detectors based on these media, and the best technical solutions to the design of these detectors. Essential attention is given to detector technology: purification methods and monitoring of purity, information readout methods, electronics, detection of hard ultra-violet light emission, selection of materials, cryogenics etc.The book is mostly addressed to physicists and graduate students involved in the preparation of fundamental next generation experiments, nuclear engineers developing instrumentation

Development of an angled Si-PM-based detector unit for positron emission mammography (PEM) system

Energy Technology Data Exchange (ETDEWEB)

Nakanishi, Kouhei, E-mail: nakanishi.kouhei@c.mbox.nagoya-u.ac.jp; Yamamoto, Seiichi

2016-11-21

Positron emission mammography (PEM) systems have higher sensitivity than clinical whole body PET systems because they have a smaller ring diameter. However, the spatial resolution of PEM systems is not high enough to detect early stage breast cancer. To solve this problem, we developed a silicon photomultiplier (Si-PM) based detector unit for the development of a PEM system. Since a Si-PM's channel is small, Si-PM can resolve small scintillator pixels to improve the spatial resolution. Also Si-PM based detectors have inherently high timing resolution and are able to reduce the random coincidence events by reducing the time window. We used 1.5×1.9×15 mm LGSO scintillation pixels and arranged them in an 8×24 matrix to form scintillator blocks. Four scintillator blocks were optically coupled to Si-PM arrays with an angled light guide to form a detector unit. Since the light guide has angles of 5.625°, we can arrange 64 scintillator blocks in a nearly circular shape (a regular 64-sided polygon) using 16 detector units. We clearly resolved the pixels of the scintillator blocks in a 2-dimensional position histogram where the averages of the peak-to-valley ratios (P/Vs) were 3.7±0.3 and 5.7±0.8 in the transverse and axial directions, respectively. The average energy resolution was 14.2±2.1% full-width at half-maximum (FWHM). By including the temperature dependent gain control electronics, the photo-peak channel shifts were controlled within ±1.5% with the temperature from 23 °C to 28 °C. With these results, in addition to the potential high timing performance of Si-PM based detectors, our developed detector unit is promising for the development of a high-resolution PEM system.

Coplanar-grid CdZnTe detector with three-dimensional position sensitivity

International Nuclear Information System (INIS)

Luke, P.N.; Amman, M.; Lee, J.S.; Yaver, H.

1998-06-01

A 3-dimensional position-sensitive coplanar-grid detector design for use with compound semiconductors is described. This detector design maintains the advantage of a coplanar-grid detector in which good energy resolution can be obtained from materials with poor charge transport. Position readout in two dimensions is accomplished using proximity-sensing electrodes adjacent to the electron-collecting grid electrode of the detector. Additionally, depth information is obtained by taking the ratio of the amplitudes of the collecting grid signal and the cathode signal. Experimental results from a prototype CdZnTe detector are presented

Amorphous silicon detectors in positron emission tomography

Energy Technology Data Exchange (ETDEWEB)

Conti, M. (Istituto Nazionale di Fisica Nucleare, Pisa (Italy) Lawrence Berkeley Lab., CA (USA)); Perez-Mendez, V. (Lawrence Berkeley Lab., CA (USA))

1989-12-01

The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters {epsilon}{sup 2}{tau}'s are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs.

Amorphous silicon detectors in positron emission tomography

International Nuclear Information System (INIS)

Conti, M.; Perez-Mendez, V.

1989-12-01

The physics of the detection process is studied and the performances of different Positron Emission Tomography (PET) system are evaluated by theoretical calculation and/or Monte Carlo Simulation (using the EGS code) in this paper, whose table of contents can be summarized as follows: a brief introduction to amorphous silicon detectors and some useful equation is presented; a Tantalum/Amorphous Silicon PET project is studied and the efficiency of the systems is studied by Monte Carlo Simulation; two similar CsI/Amorphous Silicon PET projects are presented and their efficiency and spatial resolution are studied by Monte Carlo Simulation, light yield and time characteristics of the scintillation light are discussed for different scintillators; some experimental result on light yield measurements are presented; a Xenon/Amorphous Silicon PET is presented, the physical mechanism of scintillation in Xenon is explained, a theoretical estimation of total light yield in Xenon and the resulting efficiency is discussed altogether with some consideration of the time resolution of the system; the amorphous silicon integrated electronics is presented, total noise and time resolution are evaluated in each of our applications; the merit parameters ε 2 τ's are evaluated and compared with other PET systems and conclusions are drawn; and a complete reference list for Xenon scintillation light physics and its applications is presented altogether with the listing of the developed simulation programs

Semiconductor Thermal Neutron Detector

Directory of Open Access Journals (Sweden)

Toru Aoki

2014-02-01

Full Text Available The  CdTe  and  GaN  detector  with  a  Gd  converter  have  been developed  and  investigated  as  a  neutron  detector  for neutron  imaging.  The  fabricated  Gd/CdTe  detector  with  the  25  mm  thick  Gd  was  designed  on  the  basis  of  simulation results  of  thermal  neutron  detection  efficiency  and  spatial  resolution.  The  Gd/CdTe  detector  shows  the  detection  of neutron  capture  gamma  ray  emission  in  the  155Gd(n,  g156Gd,  157Gd(n,  g158Gd  and  113Cd(n,  g114Cd  reactions  and characteristic X-ray emissions due to conversion-electrons generated inside the Gd film. The observed efficient thermal neutron detection with the Gd/CdTe detector shows its promise in neutron radiography application. Moreover, a BGaN detector has also investigated to separate neutron signal from gamma-ray clearly. 

Design of startup neutron detector handling mechanism instrumentation

International Nuclear Information System (INIS)

Upadhyay, Chandra Kant; Sivaramakrishna, M.; Nagaraj, C.P.; Madhusoodanan, K.

2010-01-01

In PFBR, to monitor the reactor during first fuel loading and low power operation, special provision is made in the central fuel subassembly to accommodate the neutron detectors. During fuel handling operations, these detectors need to be lifted up to facilitate plug rotation. These detectors are also need to be lifted from the core to save their life, during intermediate and high power operations. Towards this, a mobile assembly containing these detectors is made with lowering and retracting provision. To control this operation, constant speed motor, torque limiter, proximity switch, wire drawn potentiometer, magnetic reed switches are provided. To ensure a smooth and safe handling of this assembly, control logic with necessary interlocks is developed. (author)

Very High Radiation Detector for the LHC BLM System Based on Secondary Electron Emission

CERN Document Server

Dehning, B; Holzer, EB; Kramer, D

2007-01-01

Beam Loss Monitoring (BLM) system plays a vital role in the active protection of the LHC accelerators elements. It should provide the number of particles lost from the primary hadron beam by measuring the radiation field induced by their interaction with matter surrounding the beam pipe. The LHC BLM system will use ionization chambers as standard detectors but in the areas where very high dose rates are expected, the Secondary Emission Monitor (SEM) chambers will be employed because of their high linearity, low sensitivity and fast response. The SEM needs a high vacuum for proper operation and has to be functional for up to 20 years, therefore all the components were designed according to the UHV requirements and a getter pump was included. The SEM electrodes are made of Ti because of its Secondary Emission Yield (SEY) stability. The sensitivity of the SEM was modeled in Geant4 via the Photo-Absorption Ionization module together with custom parameterization of the very low energy secondary electron production...

Radiation Damage Modeling for 3D Pixel Sensors in the ATLAS Detector

CERN Document Server

Wallangen, Veronica; The ATLAS collaboration

2017-01-01

Silicon Pixel detectors are at the core of the current and planned upgrade of the ATLAS detector. As the detector in closest proximity to the interaction point, these detectors will be subjected to a significant amount of radiation over their lifetime: prior to the HL-LHC, the innermost layers will receive a fluence in excess of 10^15 neq/cm2 and the HL-LHC detector upgrades must cope with an order of magnitude higher fluence integrated over their lifetimes. This poster presents the details of a new digitization model that includes radiation damage effects to the 3D Pixel sensors for the ATLAS Detector.

Long-range alpha detector

International Nuclear Information System (INIS)

MacArthur, D.W.; McAtee, J.L.

1991-01-01

Historically, alpha-particle and alpha-contamination detectors have been limited by the very short range of alpha particles in air and by relatively poor sensitivity even if the particles are intercepted. Alpha detectors have had to be operated in a vacuum or in close proximity to the source if reasonable efficiency is desired. Alpha particles interact with the ambient air, producing ionization in the air at the rate of ∼30,000 ion pairs per mega-electron-volt of alpha energy. These charges can be transported over significant distances (several meters) in a moving current of air generated by a small fan. An ion chamber located in front of the fan measures the current carried by the moving ions. The long-range alpha detector (LRAD) offers several advantages over more traditional alpha detectors. First and foremost, it can operate efficiently even if the contamination is not easily accessible. Second, ions generated by contamination in crevices and other unmonitorable locations can be detected if the airflow penetrates those areas. Third, all of the contamination on a large surface will generate ions that can be detected in a single detector; hence, the detector's sensitivity to distributed sources is not limited by the size of the probe. Finally, a simple ion chamber can detect very small electric currents, making this technique potentially quite sensitive

Detector array for measurement of high-frequency fluctuations in visible and near-UV emission from tokamaks

International Nuclear Information System (INIS)

Hurwitz, P.D.; Hall, B.F.; Rowan, W.L.

1992-01-01

We developed an imaging detector to measure high-frequency fluctuations in visible and near-UV emission from tokamaks. The detector is intended for the study of plasma turbulence, mhd phenomena, and edge-localized modes. Particularly in the first two applications, it will complement existing techniques by providing higher spatial resolution as well as measurement capability in otherwise inaccessible regions of the plasma. The device consists of an optical system, a linear array of 32 photodiodes, and an amplifier for each photodiode. The amplifiers have a transimpedance gain of 10 5 --10 6 and the frequency response is flat to 100 kHz. Experience with this device has shown that optical imaging systems can be easily designed and tailored to a specific measurement because of the small size and close spacing of the individual light-sensitive elements. The device has been successfully tested on TEXT-U in measurements of H α fluctuations

Test Results of the ALICE-HMPID Detector Commissioning

CERN Document Server

Volpe, G

2008-01-01

The ALICE High Momentum Particle Identification Detector (HMPID) consists of seven identical proximity focusing RICH counters. It covers in total 11 m2, exploiting large area CsI photocathodes for Cherenkov light imaging. The detector is installed in the ALICE solenoid, ready for the data acquisition. By means of the Detector Control System, the Front-end (FEE) and the Readout (R/O) electronics, the MWPC high voltages, the cooling and the gas system have been tested. The HMPID module gas pressure, temperature, current and voltage trends have been monitored and archived in the ORACLE database. In this paper a comprehensive review on the test results is presented.

A BGO detector for Positron Emission Profiling in catalysts

International Nuclear Information System (INIS)

Mangnus, A.V.G.; Cunningham, R.H.; Santen, R.A. van; Voigt, M.J.A. de

1995-01-01

As part of a project to study the reaction kinetics in catalysts, a detector system has been designed and built. The detector will measure in one dimension the activity distribution of positron emitters in catalyst reactors under operational conditions as a function of time. The detector consists of two arrays of ten BGO crystals each and has the flexibility to measure with high sensitivity the activity profile in various reactor sizes; the position resolution that can be reached is 3 mm. (orig.)

Electromagnetic radiation detector

Science.gov (United States)

Benson, Jay L.; Hansen, Gordon J.

1976-01-01

An electromagnetic radiation detector including a collimating window, a cathode member having a photoelectric emissive material surface angularly disposed to said window whereby radiation is impinged thereon at acute angles, an anode, separated from the cathode member by an evacuated space, for collecting photoelectrons emitted from the emissive cathode surface, and a negatively biased, high transmissive grid disposed between the cathode member and anode.

The system of the designing for PET detectors

International Nuclear Information System (INIS)

Fang Zongliang

2006-01-01

PET stands for Positron Emission Tomography, a new nuclear medicine imaging device. PET detector is the key of PET. This paper introduces a system of the designing for PET detector. The system can be used to design various PET detector. A PET detector BLOCK with 8 x 8 crystals has been designed and built by this system. (authors)

Possible overexposure of pregnant women to emissions from a walk through metal detector

International Nuclear Information System (INIS)

Wu Dagang; Qiang Rui; Chen Ji; Seidman, Seth; Witters, Donald; Kainz, Wolfgang

2007-01-01

This paper presents a systematic procedure to evaluate the induced current densities and electric fields due to walk-through metal detector (WTMD) exposure. This procedure is then used to assess the exposure of nine pregnant women models exposed to one WTMD model. First, we measured the magnetic field generated by the WTMD, then we extracted the equivalent current source to represent the WTMD emissions and finally we calculated the induced current densities and electric fields using the impedance method. The WTMD emissions and the induced fields in the pregnant women and fetus models are then compared to the ICNIRP Guidelines and the IEEE C95.6 exposure safety standard. The results prove the consistency between maximum permissible exposure (MPE) levels and basic restrictions for the ICNIRP Guidelines and IEEE C95.6. We also found that this particular WTMD complies with the ICNIRP basic restrictions for month 1-5 models, but leads to both fetus and pregnant women overexposure for month 6-9 models. The IEEE C95.6 restrictions (MPEs and basic restrictions) are not exceeded. The fetus overexposure of this particular WTMD calls for carefully conducted safety evaluations of security systems before they are deployed

Emissive computed tomography

International Nuclear Information System (INIS)

Franke, R.; Schoeppy, H.; Gambini, M.R.; Martone, R.J.; Kearns, D.S.; Enos, G.W.

1987-01-01

A medical diagnostic mechanism is described comprising: (a) an elongated structure defining a gantry travel path; (b) a gantry mounted on the structure for movement along the path of travel; (c) drive means connected to the gantry for driving the gantry along its path of travel; (d) a nuclear camera detector orbitally mounted on the gantry and positionable spaced from the gantry and proximate a patient for conducting nuclear medical diagnostic studies, and (e) means for facilitating rotation of at least a portion of the gantry and of the detector about an axis transverse to the travel path

Identification of the driving factors' influences on regional energy-related carbon emissions in China based on geographical detector method.

Science.gov (United States)

Zhang, Xinlin; Zhao, Yuan

2018-04-01

To investigate the influences of different factors on spatial heterogeneity of regional carbon emissions, we firstly studied the spatial-temporal dynamics of regional energy-related carbon emissions using global Moran's I and Getis-Ord Gi and applied geographical detector model to explain the spatial heterogeneity of regional carbon emissions. Some conclusions were drawn. Regional carbon emissions showed significant global and local spatial autocorrelation. The carbon emissions were greater in eastern and northern regions than in western and southern regions. Fixed assets investment and economic output had been the main contributing factors over the study period, and economic output had been decreasing its influence. Industrial structure's influence showed a decrease trend and became smaller in 2015. The results of the interaction detections in 2015 can be divided into two types: enhance and nonlinear, and enhance and bivariate. The interactive influences between technological level and fixed assets investment, economic output and technological level, population size and technological level, and economic output and economic development were greater than others. Some policy recommendations were proposed.

Modeling Radiation Damage Effects in 3D Pixel Digitization for the ATLAS Detector

CERN Document Server

Giugliarelli, Gilberto; The ATLAS collaboration

2017-01-01

Silicon Pixel detectors are at the core of the current and planned upgrade of the ATLAS detector. As the detector in closest proximity to the interaction point, these detectors will be subjected to a significant amount of radiation over their lifetime: prior to the HL-LHC, the innermost layers will receive a fluence in excess of 10^15 neq/cm2 and the HL-LHC detector upgrades must cope with an order of magnitude higher fluence integrated over their lifetimes. This poster presents the details of a new digitization model that includes radiation damage effects to the 3D Pixel sensors for the ATLAS Detector.

Modeling Radiation Damage Effects in 3D Pixel Digitization for the ATLAS Detector

CERN Document Server

Wallangen, Veronica; The ATLAS collaboration

2017-01-01

Silicon Pixel detectors are at the core of the current and planned upgrade of the ATLAS detector. As the detector in closest proximity to the interaction point, these detectors will be subjected to a significant amount of radiation over their lifetime: prior to the HL-LHC, the innermost layers will receive a fluence in excess of 10$^{15}$ n$_\\mathrm{eq}$/cm$^2$ and the HL-LHC detector upgrades must cope with an order of magnitude higher fluence integrated over their lifetimes. This work presents the details of a new digitization model that includes radiation damage effects to the 3D Pixel sensors for the ATLAS detector.

single photon emission tomography and positron emission tomography - Part 1 (October 2012), Part 2 (October 2010)

International Nuclear Information System (INIS)

Buvat, Irene

2010-10-01

The objective of this lecture is to present the single photon emission computed tomography (SPECT) and the positron emission tomography (PET) imaging techniques. Part 1 Content: 1 - Introduction: anatomic, functional and molecular imaging; 2 - Radiotracers: chemical and physical constraints, gamma photon emitters, positon emitters, radioisotopes production, emitters type and imaging techniques; 3 - Gamma cameras; 4 - Quantification in emission tomography: attenuation, scattering, un-stationary spatial resolution; 5 - Synthesis and conclusion. Part 2 content: 1 - Positon emitters; 2 - Positons detection: Coincidence detection (electronic collimation, PET detectors with gamma cameras, dedicated PET detectors, spectrometry); PET detectors type; time-of-flight PET; 2D PET; 3D PET; 3 - Quantification in emission tomography: detected events, attenuation, scattering, fortuitous coincidences, standardisation; 4 - Common SPECT and PET problems: partial volume effect, movement, tomographic reconstruction, calibration, dead time; 5 - Synthesis and conclusion

A single photon emission computed tomograph based on a limited dumber of detectors for fluid flow visualization

International Nuclear Information System (INIS)

Legoupil, S.

1999-01-01

We present in this work a method for fluid flow visualization in a system using radioactive tracers. The method is based on single photon emission computed tomography techniques, applied to a limited number of discrete detectors. We propose in this work a method for the estimation of the transport matrix of photons, associated to the acquisition system. This method is based on the modelization of profiles acquired for a set of point sources located in the imaged volume. Monte Carlo simulations allow to separate scattered photons from those directly collected by the system. The influence of the energy tracer is exposed. The reconstruction method is based on the maximum likelihood - expectation maximization algorithm. An experimental device, based on 36 detectors was realised for the visualization of water circulation in a vessel. A video monitoring allows to visualize the dye water tracer. Dye and radioactive tracers are injected simultaneously in a water flow circulating in the vessel. Reconstructed and video images are compared. Quantitative and qualitative analysis show that fluid flow visualization is feasible with a limited number of detectors. This method can be applied for system involving circulations of fluids. (author)

Earthquake prediction research with plastic nuclear track detectors

International Nuclear Information System (INIS)

Woith, H.; Enge, W.; Beaujean, R.; Oschlies, K.

1988-01-01

Since 1984 a German-Turkish project on earthquake prediction research has been operating at the North Anatolian fault zone in Turkey. Among many other parameters changes in Radon emission have also been investigated. Plastic nuclear track detectors (Kodak cellulose nitrate LR 115) are used to record alpha-particles emitted from Radon and Thoron atoms and their daughter isotopes. The detectors are replaced and analyzed every 3 weeks. Thus a quasi-continuous time sequence of the Radon soil gas emission is recorded. We present a comparison between measurements made with electronic counters and plastic track detectors. (author)

Biological detector and method

Science.gov (United States)

Sillerud, Laurel; Alam, Todd M; McDowell, Andrew F

2013-02-26

A biological detector includes a conduit for receiving a fluid containing one or more magnetic nanoparticle-labeled, biological objects to be detected and one or more permanent magnets or electromagnet for establishing a low magnetic field in which the conduit is disposed. A microcoil is disposed proximate the conduit for energization at a frequency that permits detection by NMR spectroscopy of whether the one or more magnetically-labeled biological objects is/are present in the fluid.

Detection of electron and hole traps in CdZnTe radiation detectors by thermoelectric emission spectroscopy and thermally stimulated conductivity

International Nuclear Information System (INIS)

Lee, E.Y.; Brunett, B.A.; Olsen, R.W.; Van Scyoc, J.M. III; Hermon, H.; James, R.B.

1998-01-01

The electrical properties of CdZnTe radiation detectors are largely determined by electron and hole traps in this material. The traps, in addition to degrading the detector performance, can function as dopants and determine the resistivity of the material. Thermoelectric emission spectroscopy and thermally stimulated conductivity are used to detect these traps in a commercially available spectrometer-grade CdZnTe detector, and the electrical resistivity is measured as a function of temperature. A deep electron trap having an energy of 695 meV and cross section of 8 x 10 -16 cm 2 is detected and three hole traps having energies of 70 ± 20 meV, 105 ± 30 meV and 694 ± 162 meV are detected. A simple model based on these traps explains quantitatively all the data, including the electrical properties at room temperature and also their temperature dependence

Development of a cryogenic radiation detector for mapping radio frequency superconducting cavity field emissions

Energy Technology Data Exchange (ETDEWEB)

Danny Dotson; John Mammosser

2005-05-01

Field emissions in a super conducting helium cooled RF cavity and the production of radiation (mostly X-Rays) have been measured externally on cryomodules at Jefferson Lab since 1991. External measurements are limited to radiation energies above 100 keV due to shielding of the stainless steel cryogenic body. To measure the onset of and to map field emissions from a superconducting cavity requires the detecting instrument be inside the shield and within the liquid Helium. Two possible measurement systems are undergoing testing at JLab. A CsI detector array set on photodiodes and an X-Ray film camera with a fixed aperture. Several devices were tested in the cell with liquid Helium without success. The lone survivor, a CsI array, worked but saturated at high power levels due to backscatter. The array was encased in a lead shield with a slit opening set to measure the radiation emitted directly from the cell eliminating a large portion of the backscatter. This is a work in progress and te sting should be complete before the PAC 05. The second system being tested is passive. It is a shielded box with an aperture to expose radiation diagnostic film located inside to direct radiation from the cell. Developing a technique for mapping field emissions in cryogenic cells will assist scientists and engineers in pinpointing any surface imperfections for examination.

Modeling Radiation Damage to Pixel Sensors in the ATLAS Detector

CERN Document Server

Nachman, Benjamin Philip; The ATLAS collaboration

2017-01-01

Silicon Pixel detectors are at the core of the current and planned upgrade of the ATLAS detector. As the detector in closest proximity to the interaction point, these detectors will be subjected to a significant amount of radiation over their lifetime: prior to the HL-LHC, the innermost layers will receive a fluence in excess of $10^{15}$ 1 MeV $n_\\mathrm{eq}/\\mathrm{cm}^2$ and the HL-LHC detector upgrades must cope with an order of magnitude higher fluence integrated over their lifetimes. This talk presents a digitization model that includes radiation damage effects to the ATLAS Pixel sensors for the first time. After a thorough description of the setup, predictions for basic Pixel cluster properties are presented alongside first validation studies with Run 2 collision data.

Long-range alpha detector (LRAD)

International Nuclear Information System (INIS)

MacArthur, D.W.; McAtee, J.L.

1991-01-01

Historically, alpha detectors have been limited by the very short range of alpha particles in air and by relatively poor sensitivity, even if the particles are intercepted. Of necessity, these detectors are operated in a vacuum or in close proximity to the source if reasonable efficiency is desired. In our new long-range alpha detector (LRAD), alpha particles interact with the ambient air, producing ionization in the air at the rate of about 30,000 ion pairs per MeV of alpha energy. These charges can be transported over significant distances (several meters) in a moving current of air generated by a small fan. An ion chamber located in front of the fan measures the current carried by the moving ions. The LRAD-based monitor is more sensitive and more thorough than conventional monitors. We present current LRAD sensitivity limits and results, practical monitor designs, and proposed uses for LRAD monitors. 4 refs., 7 figs

Time-of-flight detector with KBr working medium

International Nuclear Information System (INIS)

Arvanov, A.N.; Gavalyan, V.G.; Lorikyan, M.P.

1983-01-01

A detector of controlled secondary electron emission as a 3-electrode focusing electrostatic system of the photomultiplier input chamber having a microchannel electron plate herringbone assembly with the total gain of approXimately 10 7 is described. A controlled secondary emission emitter based on MgO or KBr is installed as a cathode. The detector is designed for time-of-flight spectrometers. The time resolution is < or approximately equal to 0.5 ns. The time-of-flight system realized on the base of such two detectors has 100% detection efficiency and it is ''transparent'' for an identified particle. Its characteristics for α particle, deuteron and proton detection are estimated

Exploiting Proximity-Based Mobile Apps for Large-Scale Location Privacy Probing

Directory of Open Access Journals (Sweden)

Shuang Zhao

2018-01-01

Full Text Available Proximity-based apps have been changing the way people interact with each other in the physical world. To help people extend their social networks, proximity-based nearby-stranger (NS apps that encourage people to make friends with nearby strangers have gained popularity recently. As another typical type of proximity-based apps, some ridesharing (RS apps allowing drivers to search nearby passengers and get their ridesharing requests also become popular due to their contribution to economy and emission reduction. In this paper, we concentrate on the location privacy of proximity-based mobile apps. By analyzing the communication mechanism, we find that many apps of this type are vulnerable to large-scale location spoofing attack (LLSA. We accordingly propose three approaches to performing LLSA. To evaluate the threat of LLSA posed to proximity-based mobile apps, we perform real-world case studies against an NS app named Weibo and an RS app called Didi. The results show that our approaches can effectively and automatically collect a huge volume of users’ locations or travel records, thereby demonstrating the severity of LLSA. We apply the LLSA approaches against nine popular proximity-based apps with millions of installations to evaluate the defense strength. We finally suggest possible countermeasures for the proposed attacks.

Miniature Uncooled Infrared Sensitive Detectors for in Vivo Biomedical Imaging Applications

Energy Technology Data Exchange (ETDEWEB)

Datskos, P. G.; Demos, S. G.; Rajic, S.

1998-06-01

Broadband infrared (OR) radiation detectors have been developed using miniature, inexpensive, mass produced microcantilevers capable of detecting temperature differences as small as lea(-6) K. Microcantilevers made out of semiconductor materials can be used either as uncurled photon or thermal detectors. Mounted on a probe mm in diameter a number of microcantilevers can be accommodated in the working channel of existing endoscopes for in vivo proximity focus measurements inside the human body.

An edge-readout, multilayer detector for positron emission tomography.

Science.gov (United States)

Li, Xin; Ruiz-Gonzalez, Maria; Furenlid, Lars R

2018-04-10

We present a novel gamma-ray-detector design based on total internal reflection (TIR) of scintillation photons within a crystal that addresses many limitations of traditional PET detectors. Our approach has appealing features, including submillimeter lateral resolution, DOI positioning from layer thickness, and excellent energy resolution. The design places light sensors on the edges of a stack of scintillator slabs separated by small air gaps and exploits the phenomenon that more than 80% of scintillation light emitted during a gamma-ray event reaches the edges of a thin crystal with polished faces due to TIR. Gamma-ray stopping power is achieved by stacking multiple layers, and DOI is determined by which layer the gamma ray interacts in. The concept of edge readouts of a thin slab was verified by Monte Carlo simulation of scintillation light transport. An LYSO crystal of dimensions 50.8 mm × 50.8 mm × 3.0 mm was modeled with five rectangular SiPMs placed along each edge face. The mean-detector-response functions (MDRFs) were calculated by simulating signals from 511 keV gamma-ray interactions in a grid of locations. Simulations were carried out to study the influence of choice of scintillator material and dimensions, gamma-ray photon energies, introduction of laser or mechanically induced optical barriers (LIOBs, MIOBs), and refractive indices of optical-coupling media and SiPM windows. We also analyzed timing performance including influence of gamma-ray interaction position and presence of optical barriers. We also modeled and built a prototype detector, a 27.4 mm × 27.4 mm × 3.0 mm CsI(Tl) crystal with 4 SiPMs per edge to experimentally validate the results predicted by the simulations. The prototype detector used CsI(Tl) crystals from Proteus outfitted with 16 Hamamatsu model S13360-6050PE MPPCs read out by an AiT-16-channel readout. The MDRFs were measured by scanning the detector with a collimated beam of 662-keV photons from a 137 Cs

A Tissue Propagation Model for Validating Close-Proximity Biomedical Radiometer Measurements

Science.gov (United States)

Bonds, Q.; Herzig, P.; Weller, T.

2016-01-01

The propagation of thermally-generated electromagnetic emissions through stratified human tissue is studied herein using a non-coherent mathematical model. The model is developed to complement subsurface body temperature measurements performed using a close proximity microwave radiometer. The model takes into account losses and reflections as thermal emissions propagate through the body, before being emitted at the skin surface. The derivation is presented in four stages and applied to the human core phantom, a physical representation of a stomach volume of skin, muscle, and blood-fatty tissue. A drop in core body temperature is simulated via the human core phantom and the response of the propagation model is correlated to the radiometric measurement. The results are comparable, with differences on the order of 1.5 - 3%. Hence the plausibility of core body temperature extraction via close proximity radiometry is demonstrated, given that the electromagnetic characteristics of the stratified tissue layers are known.

Instrumentation for positron emission tomography

International Nuclear Information System (INIS)

Budinger, T.F.; Derenzo, S.E.; Huesman, R.H.

1984-01-01

Positron emission tomography with a spatial resolution of 2 mm full width at half maximum for quantitation in regions of interest 4 mm in diameter will become possible with the development of detectors that achieve ultrahigh resolution. Improved resolution will be possible using solid-state photodetectors for crystal identification or photomultiplier tubes with many small electron multipliers. Temporal resolution of 2 seconds and gating of cyclic events can be accomplished if statistical requirements are met. The major physical considerations in achieving high-resolution positron emission tomography are the degradation in resolution resulting from positron range, emission angle, parallax error, detector sampling density, the sensitivity of various detector materials and packing schemes, and the tradeoff between temporal resolution and statistical accuracy. The accuracy of data required for physiological models depends primarily on the fidelity of spatial sampling independent of statistical constraints

The nuclear reaction n + 3He -> 1H + 3H as proximity reaction

International Nuclear Information System (INIS)

Hilber, H.C.

1982-01-01

The present thesis tries to give by means of the nuclear reaction n + 3 He -> 1 H + 3 H as proximity reaction on the three-particle system 3 He + 9 Be -> 1 H + 3 H + 8 Be an experimental verification to the second term of a multiple scattering series. The study of these rescattering effects is of great interest for the present theory of the final-state interaction. At three incident energies (7.08 MeV, 8.98 MeV, and 6.37 MeV) to detector telescopes identify the exit channel of the three-particle system in list-mode coincidence experiments according to protons and tritons. Peaks on the kinematical curves occur. The detailed study of their kinematic behaviour allows to exclude the inconcurrence to the proximity reaction lying cascade decays via intermediate states in 4 He, 9 B, and 11 B. Regarding the Coulomb interaction the experimental results can be also explained in the sense of the classical kinematics by the proximity model. (orig.) [de

Emission computed tomography

International Nuclear Information System (INIS)

Ott, R.J.

1986-01-01

Emission Computed Tomography is a technique used for producing single or multiple cross-sectional images of the distribution of radionuclide labelled agents in vivo. The techniques of Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) are described with particular regard to the function of the detectors used to produce images and the computer techniques used to build up images. (UK)

Inter-crystal scatter identification for a depth-sensitive detector using support vector machine for small animal positron emission tomography

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Eiji [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)]. E-mail: rush@nirs.go.jp; Kitamura, Keishi [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Kimura, Yuichi [Tokyo Metropolitan Institute of Gerontology, Nakamachi 1-1 Itabashi-ku, Tokyo 173-0022 (Japan); Nishikido, Fumihiko [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Shibuya, Kengo [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Yamaya, Taiga [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan); Murayama, Hideo [National Institute of Radiological Sciences, Anagawa 4-9-1 Inage-ku, Chiba-shi, Chiba 263-8555 (Japan)

2007-02-01

In a conventional positron emission tomography (PET) detector, detected events are projected onto a 2D position histogram by an Anger calculation for crystal identification. However, the measured histogram is affected by inter-crystal scatterings (ICS) which occur in the entire detector. Peaks which are projected for each crystal in the histogram are blurred, and this causes ICS mispositioning. A depth-of-interaction (DOI) detector has been developed for the small animal PET scanner jPET-RD. This DOI detector uses 32x32 crystals with four layers and a 256-channel multi-anode flat panel photomultiplier tube (FP-PMT) which was developed by Hamamatsu Photonics K.K. Each crystal element is 1.45x1.45x4.5 mm{sup 3}. The FP-PMT has a large detective area (49x49 mm{sup 2}) and a small anode pitch (3.04 mm). Therefore, the FP-PMT can extensively trace the behavior of incident {gamma} rays in the crystals including ICS event. We, therefore, propose a novel method for ICS estimation using a statistical pattern recognition algorithm based on a support vector machine (SVM). In this study, we applied the SVM for discriminating photoelectric events from ICS events generated from multiple-anode outputs. The SVM was trained by uniform irradiation events generated from a detector simulator using a Monte Carlo calculation. The success rate for ICS event identification is about 78% for non-training data. The SVM can achieve a true subtraction of ICS events from measured events, and it is also useful for random correction in PET.

Inter-crystal scatter identification for a depth-sensitive detector using support vector machine for small animal positron emission tomography

International Nuclear Information System (INIS)

Yoshida, Eiji; Kitamura, Keishi; Kimura, Yuichi; Nishikido, Fumihiko; Shibuya, Kengo; Yamaya, Taiga; Murayama, Hideo

2007-01-01

In a conventional positron emission tomography (PET) detector, detected events are projected onto a 2D position histogram by an Anger calculation for crystal identification. However, the measured histogram is affected by inter-crystal scatterings (ICS) which occur in the entire detector. Peaks which are projected for each crystal in the histogram are blurred, and this causes ICS mispositioning. A depth-of-interaction (DOI) detector has been developed for the small animal PET scanner jPET-RD. This DOI detector uses 32x32 crystals with four layers and a 256-channel multi-anode flat panel photomultiplier tube (FP-PMT) which was developed by Hamamatsu Photonics K.K. Each crystal element is 1.45x1.45x4.5 mm 3 . The FP-PMT has a large detective area (49x49 mm 2 ) and a small anode pitch (3.04 mm). Therefore, the FP-PMT can extensively trace the behavior of incident γ rays in the crystals including ICS event. We, therefore, propose a novel method for ICS estimation using a statistical pattern recognition algorithm based on a support vector machine (SVM). In this study, we applied the SVM for discriminating photoelectric events from ICS events generated from multiple-anode outputs. The SVM was trained by uniform irradiation events generated from a detector simulator using a Monte Carlo calculation. The success rate for ICS event identification is about 78% for non-training data. The SVM can achieve a true subtraction of ICS events from measured events, and it is also useful for random correction in PET

Investigation of Electron Transport Across Vertically Grown CNTs Using Combination of Proximity Field Emission Microscopy and Scanning Probe Image Processing Techniques

KAUST Repository

Kolekar, Sadhu

2018-02-26

Field emission from nanostructured films is known to be dominated by only small number of localized spots which varies with the voltage, electric field and heat treatment. It is important to develop processing methods which will produce stable and uniform emitting sites. In this paper we report a novel approach which involves analysis of Proximity Field Emission Microscopic (PFEM) images using Scanning Probe Image Processing technique. Vertically aligned carbon nanotube emitters have been deposited on tungsten foil by water assisted chemical vapor deposition. Prior to the field electron emission studies, these films were characterized by scanning electron microscopy, transmission electron microscopy, and Atomic Force Microscopy (AFM). AFM images of the samples show bristle like structure, the size of bristle varying from 80 to 300 nm. The topography images were found to exhibit strong correlation with current images. Current–Voltage (I–V) measurements both from Scanning Tunneling Microscopy and Conducting-AFM mode suggest that electron transport mechanism in imaging vertically grown CNTs is ballistic rather than usual tunneling or field emission with a junction resistance of ~10 kΩ. It was found that I–V curves for field emission mode in PFEM geometry vary initially with number of I–V cycles until reproducible I–V curves are obtained. Even for reasonably stable I–V behavior the number of spots was found to increase with the voltage leading to a modified Fowler–Nordheim (F–N) behavior. A plot of ln(I/V3) versus 1/V was found to be linear. Current versus time data exhibit large fluctuation with the power spectral density obeying 1/f2 law. It is suggested that an analogue of F–N equation of the form ln(I/Vα) versus 1/V may be used for the analysis of field emission data, where α may depend on nanostructure configuration and can be determined from the dependence of emitting spots on the voltage.Graphical Abstract

Investigation of Electron Transport Across Vertically Grown CNTs Using Combination of Proximity Field Emission Microscopy and Scanning Probe Image Processing Techniques

Science.gov (United States)

Kolekar, Sadhu; Patole, Shashikant P.; Yoo, Ji-Beom; Dharmadhikari, Chandrakant V.

2018-03-01

Field emission from nanostructured films is known to be dominated by only small number of localized spots which varies with the voltage, electric field and heat treatment. It is important to develop processing methods which will produce stable and uniform emitting sites. In this paper we report a novel approach which involves analysis of Proximity Field Emission Microscopic (PFEM) images using Scanning Probe Image Processing technique. Vertically aligned carbon nanotube emitters have been deposited on tungsten foil by water assisted chemical vapor deposition. Prior to the field electron emission studies, these films were characterized by scanning electron microscopy, transmission electron microscopy, and Atomic Force Microscopy (AFM). AFM images of the samples show bristle like structure, the size of bristle varying from 80 to 300 nm. The topography images were found to exhibit strong correlation with current images. Current-Voltage (I-V) measurements both from Scanning Tunneling Microscopy and Conducting-AFM mode suggest that electron transport mechanism in imaging vertically grown CNTs is ballistic rather than usual tunneling or field emission with a junction resistance of 10 kΩ. It was found that I-V curves for field emission mode in PFEM geometry vary initially with number of I-V cycles until reproducible I-V curves are obtained. Even for reasonably stable I-V behavior the number of spots was found to increase with the voltage leading to a modified Fowler-Nordheim (F-N) behavior. A plot of ln(I/V3) versus 1/V was found to be linear. Current versus time data exhibit large fluctuation with the power spectral density obeying 1/f2 law. It is suggested that an analogue of F-N equation of the form ln(I/Vα) versus 1/V may be used for the analysis of field emission data, where α may depend on nanostructure configuration and can be determined from the dependence of emitting spots on the voltage.

Characterisation and commissioning of the LHCb VELO detector

CERN Document Server

AUTHOR|(CDS)2069345; Jans, E

2009-01-01

The LHCb detector is a one-armed spectrometer at the Large Hadron Collider. It has been designed to look for physics beyond the Standard Model through high precision measurements of CP-violation in the B-system and through the detection of rare B-decays. The success of LHCb relies heavily on its vertex detector, the VELO (VErtex LOcator), which will be used to trigger on B decay vertices and reconstruct them with micrometre accuracy. While small in size, comprising just 84 sensors, the VELO construction poses special challenges due to the high accuracy required and the proximity to the LHC beams. The detector will be required to operate under vacuum and will be exposed to high radiation levels. The first section of the thesis gives a brief introduction to the LHCb detector and the physics programme of the LHCb collaboration. The following sections review the VELO design and give and in-depth report on measurements of the detector performance based on data collected in beam tests. Topics covered are hit resolu...

Development of novel emission tomography system

Science.gov (United States)

Fu, Geng

In recent years, small animals, such as mice and rats, have been widely used as subjects of study in biomedical research while molecular biology and imaging techniques open new opportunities to investigate disease model. With the help of medical imaging techniques, researchers can investigate underlying mechanisms inside the small animal, which are useful for both early diagnosis and treatment monitoring. Based on tracer principle single photon emission computed tomography (SPECT) has increased popularity in small animal imaging due to its higher spatial resolution and variety of single-photon emitting radionuclides. Since the image quality strongly depends on the detector properties, both scintillation and semiconductor detectors are under active investigation for high resolution X-ray and gamma ray photon detection. The desired detector properties include high intrinsic spatial resolution, high energy resolution, and high detection efficiency. In this thesis study, we have made extensive efforts to develop novel emission tomography system, and evaluate the use of both semiconductor and ultra-high resolution scintillation detectors for small animal imaging. This thesis work includes the following three areas. Firstly, we have developed a novel energy-resolved photon counting (ERPC) detector. With the benefits of high energy resolution, high spatial resolution, flexible detection area, and a wide dynamic range of 27--200keV, ERPC detector is well-suited for small animal SPECT applications. For prototype ERPC detector excellent imaging (˜350microm) and spectroscopic performance (4keV Co-57 122keV) has been demonstrated in preliminary study. Secondly, to further improve spatial resolution to hundred-micron level, an ultra-high resolution Intensified EMCCD (I-EMCCD) detector has been designed and evaluated. This detector consists of the newly developed electron multiplying CCD (EMCCD) sensor, columnar CsI(Tl) scintillator, and an electrostatic de-magnifier (DM) tube

Method for optimizing side shielding in positron-emission tomographs and for comparing detector materials

International Nuclear Information System (INIS)

Derenzo, S.E.

1980-01-01

This report presents analytical formulas for the image-forming and background event rates seen by circular positron-emission tomographs with parallel side shielding. These formulas include deadtime losses, detector efficiency, coincidence resolving time, amount of activity, patient port diameter, shielding gap, and shielding depth. A figure of merit, defined in terms of these quantities, describes the signal-to-noise ratio in the reconstructed image of a 20-cm cylinder of water with uniformly dispersed activity. Results are presented for the scintillators NaI(TI), bismuth germanate (BGO), CsF, and plastic; and for Ge(Li) and wire chambers with converters. In these examples, BGO provided the best signal-to-noise for activity levels below 1000 μCi per cm, and CsF had the advantage for higher activity levels

Developments in Silicon Detectors and their impact on LHCb Physics Measurements

CERN Document Server

Gouldwell-Bates, A

2005-01-01

The LHCb experiment is a high energy physics detector at the Large Hadron Collider (LHC) which will probe the current understanding of the Standard Model through precise measurements of CP violation and rare decays. The LHCb detector heavily depends on the silicon vertexing (VELO) sub-detector for excellent vertex and proper decay time resolutions. The VELO detector sits at a position of only 7 mm from the LHC proton beams. However, the proximity of the silicon sensors to the proton beams results in the detectors suffering radiation damage. Radiation damage results in three changes in the macroscopic properties of the silicon detector: an increase of the leakage current, a decrease in the charge collection efficiency, and changes in the operation voltage required to fully deplete the silicon detector of the free charge carriers. Due to this radiation damage, it is expected that a replacement or upgrade of the LHCb vertex detector will be required by 2010, only 3 years after the turn-on of the LHC. This thesis...

A microfabricated, low dark current a-Se detector for measurement of microplasma optical emission in the UV for possible use on-site

Science.gov (United States)

Abbaszadeh, Shiva; Karim, Karim S.; Karanassios, Vassili

2013-05-01

Traditionally, samples are collected on-site (i.e., in the field) and are shipped to a lab for chemical analysis. An alternative is offered by using portable chemical analysis instruments that can be used on-site (i.e., in the field). Many analytical measurements by optical emission spectrometry require use of light-sources and of spectral lines that are in the Ultra-Violet (UV, ~200 nm - 400 nm wavelength) region of the spectrum. For such measurements, a portable, battery-operated, fiber-optic spectrometer equipped with an un-cooled, linear, solid-state detector may be used. To take full advantage of the advanced measurement capabilities offered by state-of-the-art solid-state detectors, cooling of the detector is required. But cooling and other thermal management hamper portability and use on-site because they add size and weight and they increase electrical power requirements. To address these considerations, an alternative was implemented, as described here. Specifically, a microfabricated solid-state detector for measurement of UV photons will be described. Unlike solid-state detectors developed on crystalline Silicon, this miniaturized and low-cost detector utilizes amorphous Selenium (a-Se) as its photosensitive material. Due to its low dark current, this detector does not require cooling, thus it is better suited for portable use and for chemical measurements on-site. In this paper, a microplasma will be used as a light-source of UV photons for the a-Se detector. For example, spectra acquired using a microplasma as a light-source will be compared with those obtained with a portable, fiber-optic spectrometer equipped with a Si-based 2080-element detector. And, analytical performance obtained by introducing ng-amounts of analytes into the microplasma will be described.

A study of cooling time reduction of interferometric cryogenic gravitational wave detectors using a high-emissivity coating

Energy Technology Data Exchange (ETDEWEB)

Sakakibara, Y.; Yamamoto, K.; Chen, D.; Tokoku, C.; Uchiyama, T.; Ohashi, M.; Kuroda, K. [Institute for Cosmic Ray Research (ICRR), University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582 (Japan); Kimura, N.; Suzuki, T.; Koike, S. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2014-01-29

In interferometric cryogenic gravitational wave detectors, there are plans to cool mirrors and their suspension systems (payloads) in order to reduce thermal noise, that is, one of the fundamental noise sources. Because of the large payload masses (several hundred kg in total) and their thermal isolation, a cooling time of several months is required. Our calculation shows that a high-emissivity coating (e.g. a diamond-like carbon (DLC) coating) can reduce the cooling time effectively by enhancing radiation heat transfer. Here, we have experimentally verified the effect of the DLC coating on the reduction of the cooling time.

The use of a Micromegas as a detector for gamma camera

International Nuclear Information System (INIS)

Barbouchi, Asma; Trabelsi, Adel

2008-01-01

The micromegas (Micro Mesh Gaseaous) is a gas detector; it was developed by I.Giomattaris and G.Charpak for application in the field of experimental particle physics. But the polyvalence of this detector makes it to be used in several areas such as medical imaging. This detector has an X-Y readout capability of resolution less than 100μm, an energy resolution down to 14% for energy range 1-10 keV and an overall efficiency of 70%. Monte carlo simulation is widely used in nuclear medicine. It allows predicting the behaviour of system. Gate (Geant4 for Application Tomography Emission) is a platform for monte carlo simulation. It is dedicated to PET/SPECT (Position Emission Tomography / single Photon Emission Tomography) applications. Our goal is to model a gamma camera that use a Micromegas as a detector and to compare their performances (energy resolution, point spread function...) with those of a scintillated gamma camera by using Gate

Multiple photon emission and b-quark asymmetries

International Nuclear Information System (INIS)

Jadach, S.; Ward, B.F.L.

1991-01-01

Recently the authors have introduced methods at the level of an event-by-event simulator, the effects of multiple photon emission in Z o physics scenarios relevant to the SLC and LEP. And, indeed, the respective Monte-Carlo Fortran programs for the processes e + e - → f bar f + n(γ), f ≠ e, and e + e - → e + e - + n(γ) are, in fact available from the authors, for example, for the interested reader. The authors have illustrated the respective multiple-photon effects in the case that f = μ and in the Bhabha scattering case (the latter case is dealt with only at the low-angle scattering regime relevant to luminosity simulations). Here, the authors focus on the case e + e - → b bar b + n(γ) in the high-precision regime. Such high-precision considerations may be relevant to a high-luminosity upgrade of the LEP collider, for example. Such a high-luminosity upgrade of the SLC appears more remote at this time, according to the lore. In this paper, the authors review the elements of the methods they shall employ in the next section. The authors then discuss in the third section, the multiple-photon emission effects on the b-quark asymmetries of interest to the authors here. The interplay of the radiative effects and the detector cuts is realized by applying Mark II-type detector cuts. Here, in order to make the comparison with their earlier work on μ bar μ + nγ final states immediate, the authors impose the same μ like cuts on their b-quark. The authors realize that, in doing this, some of what the authors gain in immediacy the authors may lose in the proximity to reality. In any event, we do not lose contact with the effects of interest to the authors. Finally, the authors conclude with some summary remarks

ALICE Transition Radiation Detector (TRD), test beam.

CERN Multimedia

2003-01-01

Electrons and positrons can be discriminated from other charged particles using the emission of transition radiation - X-rays emitted when the particles cross many layers of thin materials. To develop such a Transition Radiation Detector(TRD) for ALICE many detector prototypes were tested in mixed beams of pions and electrons, as in the example shown here.

Extensive tests of Hybrid Photon Detectors (HPD) used to collect Cherenkov light

International Nuclear Information System (INIS)

Borsato, E.; Buccheri, A.; DalCorso, F.; Ferroni, F.; Iacovella, F.; Mazzoni, M.A.; Morandin, M.; Morganti, S.; Piredda, G.; Posocco, M.; Santacesaria, R.; Stroili, R.; Torassa, E.; Voci, C.

1997-01-01

The principle of operation of a newly developed proximity focused Hybrid Photon Detector is described. The HPD characteristics, performance and calibration are reported. Results from beam tests of aerogel threshold counters read out by HPD and the particle identification performance are presented. (orig.)

47 CFR 15.35 - Measurement detector functions and bandwidths.

Science.gov (United States)

2010-10-01

... are based on the use of measurement instrumentation employing an average detector function. Unless... in terms of the average value of the emission, and pulsed operation is employed, the measurement... 47 Telecommunication 1 2010-10-01 2010-10-01 false Measurement detector functions and bandwidths...

Long-range alpha detector for contamination monitoring

International Nuclear Information System (INIS)

MacArthur, D.W.; Allander, K.S.; McAtee, J.L.

1991-01-01

Historically, alpha detectors have been limited by the very short range of alpha particles in air and by relatively poor sensitivity, even if the particles are intercepted. Of necessity, these detectors are operated in a vacuum or in close proximity to the source if reasonable efficiency is desired. In our new long-range alpha detector (LRAD), alpha particles interact with the ambient air, producing ionization in the air at the rate of about 30,000 ion pairs per MeV of alpha energy. These charges can be transported over significant distances (several meters) in a moving current of air generated by a small fan. An ion chamber located in front of the fan measures the current carried by the moving ions. The LRAD-based monitor is more sensitive and more thorough than conventional monitors. We present current LRAD sensitivity limits and results, practical monitor designs, and proposed uses for LRAD monitors. 4 refs., 6 figs

Design of an advanced positron emission tomography detector system and algorithms for imaging small animal models of human disease

Science.gov (United States)

Foudray, Angela Marie Klohs

Detecting, quantifying and visualizing biochemical mechanism in a living system without perturbing function is the goal of the instrument and algorithms designed in this thesis. Biochemical mechanisms of cells have long been known to be dependent on the signals they receive from their environment. Studying biological processes of cells in-vitro can vastly distort their function, since you are removing them from their natural chemical signaling environment. Mice have become the biological system of choice for various areas of biomedical research due to their genetic and physiological similarities with humans, the relatively low cost of their care, and their quick breeding cycle. Drug development and efficacy assessment along with disease detection, management, and mechanism research all have benefited from the use of small animal models of human disease. A high resolution, high sensitivity, three-dimensional (3D) positioning positron emission tomography (PET) detector system was designed through device characterization and Monte Carlo simulation. Position-sensitive avalanche photodiodes (PSAPDs) were characterized in various packaging configurations; coupled to various configurations of lutetium oxyorthosilicate (LSO) scintillation crystals. Forty novelly packaged final design devices were constructed and characterized, each providing characteristics superior to commercially available scintillation detectors used in small animal imaging systems: ˜1mm crystal identification, 14-15% of 511 keV energy resolution, and averaging 1.9 to 5.6 ns coincidence time resolution. A closed-cornered box-shaped detector configuration was found to provide optimal photon sensitivity (˜10.5% in the central plane) using dual LSO-PSAPD scintillation detector modules and Monte Carlo simulation. Standard figures of merit were used to determine optimal system acquisition parameters. A realistic model for constituent devices was developed for understanding the signals reported by the

Design and test results of the AMS RICH detector

CERN Document Server

Casadei, D.

2002-01-01

The AMS-02 detector will operate for at least 3 years on the International Space Station, measuring cosmic ray spectra at about 400 km above sea level over a wide range of geomagnetic latitude. The proximity focusing ring imaging \\v{C}erenkov counter of AMS-02 will measure the particle velocity $\\beta$ with $\\approx 0.1%$ uncertainty, making possible to discriminate Beryllium isotopes up to about 15 GeV/nucl. In addition its charge measurement will allow to study the elemental composition of cosmic rays up to Iron. A prototype of the RICH detector was tested with cosmic rays and on a ion beam accelerated by SPS, at CERN (October 2002).

Measurement of the secondary electron emission from CVD diamond films using phosphor screen detectors

Science.gov (United States)

Vaz, R.; May, P. W.; Fox, N. A.; Harwood, C. J.; Chatterjee, V.; Smith, J. A.; Horsfield, C. J.; Lapington, J. S.; Osbourne, S.

2015-03-01

Diamond-based photomultipliers have the potential to provide a significant improvement over existing devices due to diamond's high secondary electron yield and narrow energy distribution of secondary electrons which improves energy resolution creating extremely fast response times. In this paper we describe an experimental apparatus designed to study secondary electron emission from diamond membranes only 400 nm thick, observed in reflection and transmission configurations. The setup consists of a system of calibrated P22 green phosphor screens acting as radiation converters which are used in combination with photomultiplier tubes to acquire secondary emission yield data from the diamond samples. The superior signal voltage sampling of the phosphor screen setup compared with traditional Faraday Cup detection allows the variation in the secondary electron yield across the sample to be visualised, allowing spatial distributions to be obtained. Preliminary reflection and transmission yield data are presented as a function of primary electron energy for selected CVD diamond films and membranes. Reflection data were also obtained from the same sample set using a Faraday Cup detector setup. In general, the curves for secondary electron yield versus primary energy for both measurement setups were comparable. On average a 15-20% lower signal was recorded on our setup compared to the Faraday Cup, which was attributed to the lower photoluminescent efficiency of the P22 phosphor screens when operated at sub-kilovolt bias voltages.

Proximal Humerus

NARCIS (Netherlands)

Diercks, Ron L.; Bain, Gregory; Itoi, Eiji; Di Giacomo, Giovanni; Sugaya, Hiroyuki

2015-01-01

This chapter describes the bony structures of the proximal humerus. The proximal humerus is often regarded as consisting of four parts, which assists in understanding function and, more specially, describes the essential parts in reconstruction after fracture or in joint replacement. These are the

Simulation, image reconstruction and SiPM characterisation for a novel endoscopic positron emission tomography detector

Energy Technology Data Exchange (ETDEWEB)

Zvolsky, Milan

2017-12-15

In the scope of the EndoTOFPET-US project, a novel multimodal device for ultrasound (US) endoscopy and positron emission tomography (PET) is being developed. The project aims at detecting and quantifying morphologic and functional biomarkers and developing new biomarkers for pancreas and prostate oncology. The detector system comprises a small detector probe mounted on an ultrasound endoscope and an external detector plate. The detection of the gamma rays is realised by scintillator crystals with Silicon Photomultiplier (SiPM) read-out. For the characterisation of over 4000 SiPMs for the external plate, an automatised measurement and data analysis procedure is established. The key properties of the SiPMs like breakdown voltage and dark count rate (DCR) are extracted. This knowledge is needed both as a quality assurance as well as for the calibration of the detector. The spread between minimum and maximum breakdown voltage within a SiPM array of 4 x 4 is at maximum 0.43 V with a mean of 0.15 V and an RMS of 0.06 V. This assures the optimal biasing of each SiPM at its individual operating voltage. The mean DCR amounts to 1.49 MHz with an RMS of 0.54 MHz and is thus well below the acceptable threshold of 3 MHz. Two spare modules from the external plate are re-measured and analysed several years after the module assembly, revealing a potential alteration of the SiPM noise properties over time. For the characterisation of SiPMs from different vendors, a software framework for the automatic extraction of performance parameters from pulseheight spectra, including a t of the entire spectrum, is developed and tested. In order to facilitate the modelling of the response of the EndoTOFPET-US detector, a framework is developed which is built around the Geant4-based simulation toolkit GAMOS, to simulate and reconstruct realistic imaging scenarios with this asymmetric PET detector. The simulation studies are used to compare different possible detector designs, guide the

Simulation, image reconstruction and SiPM characterisation for a novel endoscopic positron emission tomography detector

International Nuclear Information System (INIS)

Zvolsky, Milan

2017-12-01

In the scope of the EndoTOFPET-US project, a novel multimodal device for ultrasound (US) endoscopy and positron emission tomography (PET) is being developed. The project aims at detecting and quantifying morphologic and functional biomarkers and developing new biomarkers for pancreas and prostate oncology. The detector system comprises a small detector probe mounted on an ultrasound endoscope and an external detector plate. The detection of the gamma rays is realised by scintillator crystals with Silicon Photomultiplier (SiPM) read-out. For the characterisation of over 4000 SiPMs for the external plate, an automatised measurement and data analysis procedure is established. The key properties of the SiPMs like breakdown voltage and dark count rate (DCR) are extracted. This knowledge is needed both as a quality assurance as well as for the calibration of the detector. The spread between minimum and maximum breakdown voltage within a SiPM array of 4 x 4 is at maximum 0.43 V with a mean of 0.15 V and an RMS of 0.06 V. This assures the optimal biasing of each SiPM at its individual operating voltage. The mean DCR amounts to 1.49 MHz with an RMS of 0.54 MHz and is thus well below the acceptable threshold of 3 MHz. Two spare modules from the external plate are re-measured and analysed several years after the module assembly, revealing a potential alteration of the SiPM noise properties over time. For the characterisation of SiPMs from different vendors, a software framework for the automatic extraction of performance parameters from pulseheight spectra, including a t of the entire spectrum, is developed and tested. In order to facilitate the modelling of the response of the EndoTOFPET-US detector, a framework is developed which is built around the Geant4-based simulation toolkit GAMOS, to simulate and reconstruct realistic imaging scenarios with this asymmetric PET detector. The simulation studies are used to compare different possible detector designs, guide the

Detectors for rare events

International Nuclear Information System (INIS)

Charpak, G.

1984-01-01

This chapter discusses the possibility of combining the advantages of photographic data retrieval with the flexibility of operation of conventional gaseous or liquid detectors operated with electronic data retrieval. Possible applications of the proposed detectors to such problems as nucleon decay, neutrinoelectron interaction, and the search for magnetic monopoles are examined. Topics considered include the photography of ionization patterns, the photography of ionization tracks with the multistep avalanche chambers, and exploiting the stimulated scintillation light. Two processes which give rise to the emission of light when ionizing electrons interact in gases under the influence of an electric field are described

The results of the irradiations of microstrip detectors for the ATLAS tracker (SCT)

International Nuclear Information System (INIS)

Dervan, P.J.

2003-01-01

The SemiConductor Tracker (SCT) of ATLAS will operate in the Large Hadron Collider (LHC) at CERN, which will reach luminosities of 10 34 cm 2 s -1 . Silicon single-sided microstrip detectors will be used for particle tracking. Due to the proximity to the beam, the silicon detectors need to withstand damage from ionising radiation (10 Mrad total dose) and from non-ionising radiation such as neutrons (2x10 14 1 MeV equivalent neutrons/cm 2 total fluence). The final characteristics of the silicon SCT detectors which are needed to operate under LHC conditions and the conclusions reached after various years of test irradiation studies will be reported. The integration and performance of these detectors in complete SCT modules is also discussed

Positron annihilation imaging device using multiple offset rings of detectors

International Nuclear Information System (INIS)

Thompson, C.J.

1982-01-01

A means is provided for recording more than one tomographic image simultaneously through different cross-sections of a patient, using positron emission tomography. Separate rings of detectors are used to construct every odd-numbered slice, and coincident events that occur between adjacent rings of detectors provide a center or even-numbered slice. Detector rings are offset with respect to one another by half the angular separation of the detectors, allowing an image to be reconstructed from the central slice without the necessity of physically rotating the detector array while accumulating data

Neutron detector using sol-gel absorber

Science.gov (United States)

Hiller, John M.; Wallace, Steven A.; Dai, Sheng

1999-01-01

An neutron detector composed of fissionable material having ions of lithium, uranium, thorium, plutonium, or neptunium, contained within a glass film fabricated using a sol-gel method combined with a particle detector is disclosed. When the glass film is bombarded with neutrons, the fissionable material emits fission particles and electrons. Prompt emitting activated elements yielding a high energy electron contained within a sol-gel glass film in combination with a particle detector is also disclosed. The emissions resulting from neutron bombardment can then be detected using standard UV and particle detection methods well known in the art, such as microchannel plates, channeltrons, and silicon avalanche photodiodes.

Autoradiography Imaging in Targeted Alpha Therapy with Timepix Detector

Directory of Open Access Journals (Sweden)

Ruqaya AL Darwish

2015-01-01

Full Text Available There is a lack of data related to activity uptake and particle track distribution in targeted alpha therapy. These data are required to estimate the absorbed dose on a cellular level as alpha particles have a limited range and traverse only a few cells. Tracking of individual alpha particles is possible using the Timepix semiconductor radiation detector. We investigated the feasibility of imaging alpha particle emissions in tumour sections from mice treated with Thorium-227 (using APOMAB, with and without prior chemotherapy and Timepix detector. Additionally, the sensitivity of the Timepix detector to monitor variations in tumour uptake based on the necrotic tissue volume was also studied. Compartmental analysis model was used, based on the obtained imaging data, to assess the Th-227 uptake. Results show that alpha particle, photon, electron, and muon tracks were detected and resolved by Timepix detector. The current study demonstrated that individual alpha particle emissions, resulting from targeted alpha therapy, can be visualised and quantified using Timepix detector. Furthermore, the variations in the uptake based on the tumour necrotic volume have been observed with four times higher uptake for tumours pretreated with chemotherapy than for those without chemotherapy.

Optically sensitive Medipix2 detector for adaptive optics wavefront sensing

CERN Document Server

Vallerga, John; Tremsina, Anton; Siegmund, Oswald; Mikulec, Bettina; Clark, Allan G; CERN. Geneva

2005-01-01

A new hybrid optical detector is described that has many of the attributes desired for the next generation adaptive optics (AO) wavefront sensors. The detector consists of a proximity focused microchannel plate (MCP) read out by multi-pixel application specific integrated circuit (ASIC) chips developed at CERN ("Medipix2") with individual pixels that amplify, discriminate and count input events. The detector has 256 x 256 pixels, zero readout noise (photon counting), can be read out at 1 kHz frame rates and is abutable on 3 sides. The Medipix2 readout chips can be electronically shuttered down to a temporal window of a few microseconds with an accuracy of 10 ns. When used in a Shack-Hartmann style wavefront sensor, a detector with 4 Medipix chips should be able to centroid approximately 5000 spots using 7 x 7 pixel sub-apertures resulting in very linear, off-null error correction terms. The quantum efficiency depends on the optical photocathode chosen for the bandpass of interest.

Optically sensitive Medipix2 detector for adaptive optics wavefront sensing

International Nuclear Information System (INIS)

Vallerga, John; McPhate, Jason; Tremsin, Anton; Siegmund, Oswald; Mikulec, Bettina; Clark, Allan

2005-01-01

A new hybrid optical detector is described that has many of the attributes desired for the next generation adaptive optics (AO) wavefront sensors. The detector consists of a proximity focused microchannel plate (MCP) read out by multi-pixel application specific integrated circuit (ASIC) chips developed at CERN ('Medipix2') with individual pixels that amplify, discriminate and count input events. The detector has 256x256 pixels, zero readout noise (photon counting), can be read out at 1 kHz frame rates and is abutable on 3 sides. The Medipix2 readout chips can be electronically shuttered down to a temporal window of a few microseconds with an accuracy of 10 ns. When used in a Shack-Hartmann style wavefront sensor, a detector with 4 Medipix chips should be able to centroid approximately 5000 spots using 7x7 pixel sub-apertures resulting in very linear, off-null error correction terms. The quantum efficiency depends on the optical photocathode chosen for the bandpass of interest

Positron emission tomography camera

International Nuclear Information System (INIS)

Anon.

1986-01-01

A positron emission tomography camera having a plurality of detector rings positioned side-by-side or offset by one-half of the detector cross section around a patient area to detect radiation therefrom. Each ring contains a plurality of scintillation detectors which are positioned around an inner circumference with a septum ring extending inwardly from the inner circumference along each outer edge of each ring. An additional septum ring is positioned in the middle of each ring of detectors and parallel to the other septa rings, whereby the inward extent of all the septa rings may be reduced by one-half and the number of detectors required in each ring is reduced. The additional septa reduces the costs of the positron camera and improves its performance

Preliminary evaluation of a method using an FID (flame ionization detector) for measurement of methanol in auto emissions. Final report

International Nuclear Information System (INIS)

Gabele, P.A.; Ray, W.D.; Duncan, J.; Burton, C.

1987-09-01

This report evaluates a simplified technique for estimating methanol emission rates in auto exhaust. The technique, referred to as the FID Bubbled Method or FBM, is based in principle on the fact that, while hydrocarbons are not readily absorbed in water, methanol is. Hence, by using a heated flame ionization detector to measure the organic mass in samples before and after bubbling them in water, the quantity of methanol originally present can be estimated by taking the difference between the measurements. Evaluation of the method was done by comparing methanol measurements using the FBM with measurements made using an established reference method. Results showed poor to fair agreement between the two methods. The FBM appeared better at estimating methanol emission rates from evaporative tests than from exhaust tests and also exhibited better accuracy for samples containing higher levels of methanol

Cerenkov radiation simulation in the Auger water ground detector

International Nuclear Information System (INIS)

Le Van Ngoc; Vo Van Thuan; Dang Quang Thieu

2003-01-01

The simulation of response of the Auger water Cerenkov ground detector to atmospheric shower muons in practically needed for the experimental research of cosmic rays at extreme energies. We consider here a simulation model for the process of emission and diffusion of Cerenkov photons concerned with muons moving through the detector volume with the velocity greater than the phase velocity of light in the water on purpose to define photons producing signal in the detector. (author)

Strategies for reducing the environmental impact of gaseous detector operation at the CERN LHC experiments

Energy Technology Data Exchange (ETDEWEB)

Capeans, M.; Guida, R.; Mandelli, B., E-mail: beatrice.mandelli@cern.ch

2017-02-11

A wide range of gas mixtures is used for the operation of different gaseous detectors at the Large Hadron Collider (LHC) experiments. Nowadays some of these gases, as C{sub 2}H{sub 2}F{sub 4}, CF{sub 4} and SF{sub 6}, are indicated as greenhouse gases (GHG) and dominate the overall GHG emission from particle detectors at the LHC experiments. The release of GHG is an important subject for the design of future particle detectors as well as for the operation of the current experiments. Different strategies have been adopted at CERN for reducing the GHG emissions. The standard approach is the recirculation of the gas mixture with complex gas systems where system stability and the possible accumulation of impurities need to be attentively evaluated for the good operation and safety of the detectors. A second approach is based on the recuperation of the gas mixture exiting the detectors and the separation of its gas components for re-use. At long-term, the use of less invasive gases is being investigated, especially for the Resistive Plate Chamber (RPC) systems. Operation of RPC with environmentally friendly gas mixtures is demonstrated for streamer mode while avalanche mode operation needs more complex gas mixtures. - Highlights: • Greenhouse gases (GHG) emission in the LHC experiments and detectors. • Strategies to reduce the GHG emissions: gas recirculation and recuperation systems. • GHG emission: achievements from LHC Run1 to Run2. • Resistive Plate Chambers operation with new environmentally friendly gases.

Apparatus for measuring radioactive emissions

International Nuclear Information System (INIS)

Bohme, R.C.; Lazerson, M.M.

1984-01-01

Apparatus for measuring radioactive emissions from moving radioactive material comprises at least one radiation detector in a housing serving as a first radiation shield and in which at least one groove is formed to expose at least a portion of a receptor surface of the detector. The groove extends transverse to the direction of movement of the material over the detector. A second radiation shield may be located between at least a portion of the first shield and the detector. The material of the second shield is inherently less contaminated and emits secondary excitation radiation of lower energy than the first material. (author)

Developing works to detect fatigue cracks (small sodium leak detector and acoustic emission

International Nuclear Information System (INIS)

Kikuchi, M.; Sakakibara, Y.; Nagata, T.

1980-01-01

Continuous monitoring of fatigue cracks was performed (using both sodium leak detector and AE measuring system) through the creep-fatigue test of 304 stainless steel long elbow as part of the test series to establish the structural reliability of the Prototype FBR primary heat transport piping system. The sodium leak detector was a system composed mainly of SID (Sodium Ionization Detector) and DPD (Deferential Pressure Detector), that was developed by HITACHI Ltd. under a contract with PNC. The AE system was Synthetic AE Measuring and Analyzing system that was developed at FBR Safety Section to measure and analyze AE at various piping component tests. The test was continued until a sodium leakage was detected by the contact-type sodium leak detector attached to the test assembly, after about 4 weeks operation under cyclic loading at 600 deg. C. The following conclusions were obtained: (1) The sodium leak detector, both SID and DPD, indicated sodium leakage clearly, some hours before the contact-type detector did, even under an environment of air that contains ordinary humidity (Leaked sodium was estimated to be less than 15 grams after completion of the test); (2) The AE method indicated location and seriousness of the fatigue cracks, apparently before the crack penetration occurred. (author)

Studies for the detector control system of the ATLAS pixel at the HL-LHC

International Nuclear Information System (INIS)

Püllen, L; Becker, K; Boek, J; Kersten, S; Kind, P; Mättig, P; Zeitnitz, C

2012-01-01

In the context of the LHC upgrade to the HL-LHC the inner detector of the ATLAS experiment will be replaced completely. As part of this redesign there will also be a new pixel detector. This new pixel detector requires a control system which meets the strict space requirements for electronics in the ATLAS experiment. To accomplish this goal we propose a DCS (Detector Control System) network with the smallest form factor currently available. This network consists of a DCS chip located in close proximity to the interaction point and a DCS controller located in the outer regions of the ATLAS detector. These two types of chips form a star shaped network with several DCS chips being controlled by one DCS controller. Both chips are manufactured in deep sub-micron technology. We present prototypes with emphasis on studies concerning single event upsets.

Performance of a proximity cryogenic system for the ATLAS central solenoid magnet

CERN Document Server

Doi, Y; Makida, Y; Kondo, Y; Kawai, M; Aoki, K; Haruyama, T; Kondo, T; Mizumaki, S; Wachi, Y; Mine, S; Haug, F; Delruelle, N; Passardi, Giorgio; ten Kate, H H J

2002-01-01

The ATLAS central solenoid magnet has been designed and constructed as a collaborative work between KEK and CERN for the ATLAS experiment in the LHC project The solenoid provides an axial magnetic field of 2 Tesla at the center of the tracking volume of the ATLAS detector. The solenoid is installed in a common cryostat of a liquid-argon calorimeter in order to minimize the mass of the cryostat wall. The coil is cooled indirectly by using two-phase helium flow in a pair of serpentine cooling line. The cryogen is supplied by the ATLAS cryogenic plant, which also supplies helium to the Toroid magnet systems. The proximity cryogenic system for the solenoid has two major components: a control dewar and a valve unit In addition, a programmable logic controller, PLC, was prepared for the automatic operation and solenoid test in Japan. This paper describes the design of the proximity cryogenic system and results of the performance test. (7 refs).

Association between proximity to major roads and sputum cell counts

Science.gov (United States)

Wallace, Julie; D’silva, Liesel; Brannan, John; Hargreave, Frederick E; Kanaroglou, Pavlos; Nair, Parameswaran

2011-01-01

BACKGROUND: Air pollution caused by motor vehicle emissions has been associated with exacerbations of obstructive airway diseases; however, the nature of the resulting bronchitis has not been quantified. OBJECTIVE: To examine whether proximity to major roads or highways is associated with an increase in sputum neutrophils or eosinophils, and to evaluate the effect of proximity to roads on spirometry and exacerbations in patients with asthma. METHODS: A retrospective study of 485 sputum cell counts from patients attending a tertiary chest clinic in Hamilton, Ontario, identified eosinophilic or neutrophilic bronchitis. Patients’ residences were geocoded to the street network of Hamilton using geographic information system software. Associations among bronchitis, lung function, and proximity to major roads and highways were examined using multinomial logistic and multivariate linear regression analyses adjusted for patient age, smoking status and corticosteroid medications. RESULTS: Patients living within 1000 m of highways showed an increased risk of bronchitis (OR 3.8 [95% CI 1.0 to 13.7]; Proad were at increased risk for an asthma exacerbation (OR 1.9 [95% CI 1.5 to 15.5]; Proad was associated with neutrophilic bronchitis, an increased risk of asthma diagnosis, asthma exacerbations and lower lung function. PMID:21369545

A zerotime detector for nuclear fragments using channel electron multiplier plates

International Nuclear Information System (INIS)

Sundqvist, B.

1975-01-01

The literature on zerotime detectors which use the emission of secondary electrons from a thin foil is reviewed. The construction of a zerotime detector using multiplication of the secondary electrons with two Mullard channel electron multiplier plates (CEMP) in tandem is described. Results of tests of such a detector with α particles from a natural α source are given. Total time resolutions of about 200 ps (FWHM) with a Si(Sb) detector as the stop detector has been achieved. The contribution from the zerotime detector is estimated to be less than 150 ps (FWHM). The application of this detector technique to the construction of a heavy-ion spectrometer and a 8 Be detector is described. (Auth)

Results from cosmics and first LHC beam with the ALICE HMPID detector

CERN Document Server

Volpe, Giacomo

2009-01-01

The ALICE HMPID (High Momentum Particle IDentification) detector has been designed to identify charged pions and kaons in the range 1 < p < 3 GeV/c and protons in the range 1.5 < p < 5 GeV/c. It consists of seven identical proximity focusing RICH (Ring Imaging Cherenkov) counters, covering in total 11 m2, which exploit large area MWPC equipped with CsI photocathodes for Cherenkov light imaging emitted in a liquid C6F14 radiator. The ALICE detector has been widely commissioned using cosmics and LHC beam from December 2007 until October 2008. During the cosmics data taking the HMPID detector collected a large set of data, using mainly the trigger provided by the TOF detector. We present here preliminary results of detector alignment using TPC tracking. The HMPID could be operated in a stable way, at a safe HV setting, also during LHC beam injection and circulation tests, when a very large occupancy (up to 50%) was achieved. Resulting gain mapping and overall detector performance will also be discuss...

Self-triggering detectors for recoil nuclei

International Nuclear Information System (INIS)

Aleksanyan, A.S.; Asatiani, T.I.; Gasparyan, A.O.

1975-01-01

Hybrid α-detectors consisting of wide gap spark chambers and signal α detectors are described. The investigations have been carried out with γ-beams of Yerevan Electron Synchrotron. The possibility of using such detectors in the experiments on particle photoproduction on gas helium with the determination of the interaction point, emission angle of the recoil nucleus and its energy by means of range measurement has been shown. It has been shown that self - triggering wide gap spark chamber allows to detect and measure the range of the recoil nuclei α-particles with energies Esub(α) > or approximately (1 - 2) Mev which correspond to momentum transfers apprxomation (10 -2 - 10 -3 ) (GeV/c) 2

Dual concentric crystal low energy photon detector

Science.gov (United States)

Guilmette, R.A.

A photon detector for biological samples includes a block of NaI(T1) having a hole containing a thin walled cylinder of CsI(T1). At least three photo multiplier tubes are evenly spaced around the parameter of the block. Biological samples are placed within the hole, and emissions which are sensed by at least two of the photo multipliers from only the NaI(T1) detector are counted.

Computation and measurement of a plasma temperature using the emission lines of copper

International Nuclear Information System (INIS)

Sassi, M.; Pierre, L.; Benard, J.; Cahen, C.

1994-01-01

The use of copper emission lines for temperature measurement in plasma environments is presented. The article features the problems encountered with such a measurement method when used in a stationary and a non-stationary plasma. In the first case, we were concerned with the temperature measurements in the jet of a 2 MW industrial plasma torche. The plasma was stationary and the measurement geometry allowed the use of the Abel inversion method to recover the temperature profiles in the plasma jet. The limitations of the measurement method on the jet boundaries as well as the cooling of the plasma by entrainement of cold air are discussed. In the second case, a non-stationary plasma in a 1.4 MW electric furnace was studied. This study allowed to feature the role of the detector dynamics as related to the dynamics of the observed medium. The obtained measurements show only a probable temperature in the immediate proximity of the arc. Finally, we conclude on the validity of copper as a tracer and the use of spontaneous emission spectroscopy, and easy method to implement, compared to other sophisticated temperature measurement methods. (orig.)

Image plane detector spectrophotometer - Application to O2 atmospheric band nightglow

Science.gov (United States)

Luo, Mingzhao; Yee, Jeng-Hwa; Hays, Paul B.

1988-01-01

A new variety of low resolution spectrometer is described. This device, an image plane detector spectrophotometer, has high sensitivity and modest resolution sufficient to determine the rotational temperature and brightness of molecular band emissions. It uses an interference filter as a dispersive element and a multichannel image plane detector as the photon collecting device. The data analysis technqiue used to recover the temperature of the emitter and the emission brightness is presented. The atmospheric band of molecular oxygen is used to illustrate the use of the device.

Comparative Measurements of the Photon Detection Efficiency of KETEK SiPM Detectors for the LHCb SciFi Upgrade Project

CERN Document Server

Joram, Christian

2014-01-01

The LHCb SciFi detector is conceived to employ arrays of SiPM detectors to detect scintillation light from ribbons of 2.5 m long scintillating fibres of 250 $\\mu$m diameter. The fibres of type Kuraray SCSF-78 are blue emitting with an emission maximum at 440 nm. However, as a consequence of the radiation damage mainly from charged hadrons in the LHCb experiments, the effective emission spectrum at the end of the fibre will shift to longer wavelengths. A simulation of the light absorption in the fibre, assuming an ionizing dose distribution along the fibre as predicted by the FLUKA code, is able to predict the emission spectrum. Fig. 1 shows the emission spectra (in arbitrary units) for 10 cm intervals along the fibre. At 250 cm, where the ionization dose is expected to reach over the full lifetime of the upgrade LHCb detector about 30 kGy, the average wavelength of emission is approximately 500 nm. The sensitivity spectrum of the SiPM detector should be tuned to match this emission spectrum, i.e. the PDE shou...

Integrated Force and Distance Sensing using Elastomer-Embedded Commodity Proximity Sensors.

Energy Technology Data Exchange (ETDEWEB)

Patel, Radhen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Cox, Rebecca E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Correll, Nikolaus [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-02-01

We describe a combined proximity, contact and force (PCF) sensor based on a commodity infrared distance sensor embedded in a transparent elastomer with applications in robotic manipulation. Prior to contact, the sensor works as a distance sensor (0{6 cm), whereas after contact the material doubles as a spring, with force proportional to the compression of the elastomer (0{5 N). We describe its principle of operation and design parameters, including polymer thickness, mixing ratio, and emitter current, and show that the sensor response has an in ection point at contact that is independent of an object's surface properties, making it a robust detector for contact events. We then demonstrate how arrays of sensors, custom made for a standard Baxter gripper as well as embedded in the nger of the Kinova hand, can be used to (1) improve gripper alignment during grasping, (2) determine contact points with objects, (3) obtain simple 3D models using both proximity and touch, and (4) register point clouds from touch and RGB-D data.

Reconstruction of extensive air showers using the MIDAS molecular Bremsstrahlung detector

International Nuclear Information System (INIS)

Castro, Andre Ramos de; Bonifazi, Carla; Santos, Edivaldo Moura; Soares, Elvis do Amaral; Mello Neto, Joao Ramos Torres de; Almeida, Rogerio Menezes de

2011-01-01

Full text: The weakly ionized plasma created in the atmosphere after the passage of an Extensive Air Shower (EAS) gives rise to the emission of continuous radiation known as Molecular Bremsstrahlung Radiation (MBR) as free electrons scatter off neutral nitrogen (and less frequently oxygen) molecules. The isotropic and unpolarized nature of MBR rises the possibility of an EAS detection similar to that using fluorescence telescopes to capture the ultraviolet light emitted by the ionized nitrogen molecules. The MBR emission, however, falls into the centimeter wavelength range, requiring the use of radio/microwave antennas instead of optical telescopes. In order to test the feasibility of the technique, the MIDAS (Microwave Detection of Air Showers) Collaboration has built a prototype detector where a parabolical reflector illuminates a multi-pixel camera of commercial TV satellite C-band (3.4-4.2 GHz) feeds. This work addresses the geometrical reconstruction of EAS induced by Ultra High Energy Cosmic Rays (UHECR) using the MIDAS detector. The reconstruction chain is similar to that currently applied to the Auger Fluorescence detector events. We have simulated the shower MBR emission assuming two different scenarios: coherent and incoherent emission, i.e., radiation intensity scaling quadratically and linearly with the energy of the primary particle. The MIDAS prototype detector's response is then simulated. Finally, given the simulated events in real data format, we reconstruct the shower's arrival direction, including direction uncertainties and estimate the expected rate of observed events. (author)

Low-background measurements of neutron emission from Ti metal in pressurized deuterium gas

International Nuclear Information System (INIS)

Menlove, H.O.; Paciotti, M.A.; Claytor, T.N.; Tuggle, D.G.

1991-01-01

A wide variety of neutron detector systems have been used at various research facilities to search for anomalous neutron emission from deuterated metals. Some of these detector systems are summarized here together with possible sources of spurious signals from electronic noise. During the past two years, we have performed experiments to measure neutron emission from pressurized D 2 gas mixed with various forms of titanium metal chips and sponge. Details concerning the neutron detectors, experimental procedures, and results have been reported previously. Our recent experiments have focused on increasing the low-level neutron emission and finding a way to trigger the emission. To improve our detection sensitivity, we have increased the shielding in our counting laboratory, changed to low-background 3 He tubes, and set up additional detector systems in deep underground counting stations. This report is an update on this experimental work. 7 refs., 5 figs., 4 tabs

A RICH detector for strangeness physics in Hall A at Jefferson Lab

International Nuclear Information System (INIS)

Cusanno, F.; Garibaldi, F.; Cisbani, E.; Colilli, S.; De Cataldo, G.; De Leo, R.; Giuliani, F.; Gricia, M.; Lagamba, L.; Lucentini, M.; Reitz, B.; Santavenere, F.; Urciuoli, G.M.

2004-01-01

The high-resolution hypernuclear spectroscopy experiment at Jefferson Lab, Hall A (E94-107), needs unambiguous kaon identification. Due to the huge pion and proton background, the standard Hall A hadron particle identification, based on a time of flight and two aerogel threshold Cherenkov detectors, is not sufficient. For this task a proximity focusing C 6 F 14 /CsI RICH has been built. Recently, after some improvements to the mechanical structure of its wire chamber and to its electronics rate capability, the RICH has been tested with cosmic rays. This paper represents a status report of the RICH detector

Triton burnup study using scintillating fiber detector on JT-60U

Energy Technology Data Exchange (ETDEWEB)

Harano, Hideki [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

1997-09-01

The DT fusion reactor cannot be realized without knowing how the fusion-produced 3.5 MeV {alpha} particles behave. The {alpha} particles` behavior can be simulated using the 1 MeV triton. To investigate the 1 MeV triton`s behavior, a new type of directional 14 MeV neutron detector, scintillating fiber (Sci-Fi) detector has been developed and installed on JT-60U in the cooperation with LANL as part of a US-Japan collaboration. The most remarkable feature of the Sci-Fi detector is that the plastic scintillating fibers are employed for the neutron sensor head. The Sci-Fi detector measures and extracts the DT neutrons from the fusion radiation field in high time resolution (10 ms) and wide dynamic range (3 decades). Triton burnup analysis code TBURN has been made in order to analyze the time evolution of DT neutron emission rate obtained by the Sci-Fi detector. The TBURN calculations reproduced the measurements fairly well, and the validity of the calculation model that the slowing down of the 1 MeV triton was classical was confirmed. The Sci-Fi detector`s directionality indicated the tendency that the DT neutron emission profile became more and more peaked with the time progress. In this study, in order to examine the effect of the toroidal field ripple on the triton burnup, R{sub p}-scan and n{sub e}-scan experiments have been performed. The R{sub p}-scan experiment indicates that the triton`s transport was increased as the ripple amplitude over the triton became larger. In the n{sub e}-scan experiment, the DT neutron emission showed the characteristic changes after the gas puffing injection. It was theoretically confirmed that the gas puffing was effective for the collisionality scan. (J.P.N.) 127 refs.

Long-term stability of the Clear-PEM detector modules

International Nuclear Information System (INIS)

Amaral, Pedro; Bruyndonckx, Peter; Carrico, Bruno; Ferreira, Miguel; Luyten, Joan; Moura, Rui; Ortigao, Catarina; Rodrigues, Pedro; Silva, Jose C. da; Trindade, Andreia; Varela, Joao

2007-01-01

Experimental evaluation of the imaging system Clear-PEM for positron emission mammography, under development within the framework of the crystal clear collaboration at CERN, is presented in terms of its long-term stability. The detector modules and experimental setup are described. Time evolution results of signal yield, energy resolution, depth-of-interaction and inter-channel crosstalk for a reference detector module are reported

Detector Position Estimation for PET Scanners.

Science.gov (United States)

Pierce, Larry; Miyaoka, Robert; Lewellen, Tom; Alessio, Adam; Kinahan, Paul

2012-06-11

Physical positioning of scintillation crystal detector blocks in Positron Emission Tomography (PET) scanners is not always exact. We test a proof of concept methodology for the determination of the six degrees of freedom for detector block positioning errors by utilizing a rotating point source over stepped axial intervals. To test our method, we created computer simulations of seven Micro Crystal Element Scanner (MiCES) PET systems with randomized positioning errors. The computer simulations show that our positioning algorithm can estimate the positions of the block detectors to an average of one-seventh of the crystal pitch tangentially, and one-third of the crystal pitch axially. Virtual acquisitions of a point source grid and a distributed phantom show that our algorithm improves both the quantitative and qualitative accuracy of the reconstructed objects. We believe this estimation algorithm is a practical and accurate method for determining the spatial positions of scintillation detector blocks.

Detector position estimation for PET scanners

International Nuclear Information System (INIS)

Pierce, Larry; Miyaoka, Robert; Lewellen, Tom; Alessio, Adam; Kinahan, Paul

2012-01-01

Physical positioning of scintillation crystal detector blocks in Positron Emission Tomography (PET) scanners is not always exact. We test a proof of concept methodology for the determination of the six degrees of freedom for detector block positioning errors by utilizing a rotating point source over stepped axial intervals. To test our method, we created computer simulations of seven Micro Crystal Element Scanner (MiCES) PET systems with randomized positioning errors. The computer simulations show that our positioning algorithm can estimate the positions of the block detectors to an average of one-seventh of the crystal pitch tangentially, and one-third of the crystal pitch axially. Virtual acquisitions of a point source grid and a distributed phantom show that our algorithm improves both the quantitative and qualitative accuracy of the reconstructed objects. We believe this estimation algorithm is a practical and accurate method for determining the spatial positions of scintillation detector blocks.

Radiation detectors based by polymer materials

International Nuclear Information System (INIS)

Cherestes, Margareta; Cherestes, Codrut; Constantinescu, Livia

2004-01-01

Scintillation counters make use of the property of certain chemical compounds to emit short light pulses after excitation produced by the passage of charged particles or photons of high energy. These flashes of light are detected by a photomultiplier tube that converts the photons into a voltage pulse. The light emitted from the detector also can be collected, focussed and dispersed by a CCD detector. The study of the evolution of the light emission and of the radiation damage under irradiation is a primary topic in the development of radiation hard polymer based scintillator. Polymer scintillator thin films are used in monitoring radiation beam intensities and simultaneous counting of different radiations. Radiation detectors have characteristics which depend on: the type of radiation, the energy of radiation, and the material of the detector. Three types of polymer thin films were studied: a polyvinyltoluene based scintillator, fluorinated polyimide and PMMA. (authors)

Emission computed tomograph

International Nuclear Information System (INIS)

Hirose, Y.; Kanno, I.; Koga, K.; Miura, S.; Uemura, K.

1981-01-01

Emission computed tomograph wherein a pluralty of detectors surround an object to be examined so as to detect x- or gamma radiation emitted by said object. In front of each of said detectors there is provided a collimator which comprises a pair of main plates and a subsidiary plate interposed therebetween. The plates are made of a material capable of blocking penetration of the radiation therethrough and so supported as to be swingable over an angle sufficient to cover the whole of said object. The plates of all the collimators are simultaneously swung to the same side and at the same angular speed thereby to change the direction of incidence of said radiation on each of said detectors

Assessment of coronary arteries in infants by 64-detector-row multislice spiral computed tomography

International Nuclear Information System (INIS)

Tahara, Masahiro; Waki, Chiaki; Komatsu, Hiroaki; Hayashi, Tomohiro; Sato, Tomoyasu

2008-01-01

Heart rate is one of the most important factors for optimal visualization of cardiac CT. We investigated the relation between heart rate and visibility of the coronary arteries with 64-detector row multislice spiral computed tomography (MSCT). Three simulated coronary artery stenosis models (3, 4, and 5 mm) were attached to a moving heart phantom and scanned using 64-detector row MSCT. The heart rate of the phantom was varied between 60 and 150 beats per minutes (bpm). The visibility of simulated coronary arteries was assessed in comparison between cardiac half reconstruction (CHR) and multi-sector reconstruction (MSR). Then contrast-enhanced 64-detector row MSCT was performed in 16 patients under 3 years of age with congenital heart disease and Kawasaki disease without heart rate control. The visibility of coronary artery segments was graded on a three-point scale. The simulated coronary artery patency was detected in the moving phantom at maximum heart rate (150 bpm) with MSR. Minimum lumen diameter was 0.75 mm. Electrocardiogram (ECG)-gated cardiac CT was performed in 9 patients, and non-ECG-gated cardiac CT was performed in 7 patients. The origin and proximal course of coronary arteries in all 9 patients with ECG-gated acquisition were visually evaluated. 64-detector row MSCT with ECG-gated acquisition is able to visualize the origin and proximal course of coronary arteries in infants under 3 years of age. (author)

Proximal Alternating Direction Method with Relaxed Proximal Parameters for the Least Squares Covariance Adjustment Problem

Directory of Open Access Journals (Sweden)

Minghua Xu

2014-01-01

Full Text Available We consider the problem of seeking a symmetric positive semidefinite matrix in a closed convex set to approximate a given matrix. This problem may arise in several areas of numerical linear algebra or come from finance industry or statistics and thus has many applications. For solving this class of matrix optimization problems, many methods have been proposed in the literature. The proximal alternating direction method is one of those methods which can be easily applied to solve these matrix optimization problems. Generally, the proximal parameters of the proximal alternating direction method are greater than zero. In this paper, we conclude that the restriction on the proximal parameters can be relaxed for solving this kind of matrix optimization problems. Numerical experiments also show that the proximal alternating direction method with the relaxed proximal parameters is convergent and generally has a better performance than the classical proximal alternating direction method.

Gamma-ray detectors for breast imaging

Science.gov (United States)

Williams, Mark B.; Goode, Allen R.; Majewski, Stan; Steinbach, Daniela; Weisenberger, Andrew G.; Wojcik, Randolph F.; Farzanpay, Farzin

1997-07-01

Breast cancer is the most common cancer of American women and is the leading cause of cancer-related death among women aged 15 - 54; however recent years have shown that early detection using x-ray mammography can lead to a high probability of cure. However, because of mammography's low positive predictive value, surgical or core biopsy is typically required for diagnosis. In addition, the low radiographic contrast of many nonpalpable breast masses, particularly among women with radiographically dense breasts, results in an overall rate of 10% to 25% for missed tumors. Nuclear imaging of the breast using single gamma emitters (scintimammography) such as (superscript 99m)Tc, or positron emitters such as F-18- fluorodeoxyglucose (FDG) for positron emission tomography (PET), can provide information on functional or metabolic tumor activity that is complementary to the structural information of x-ray mammography, thereby potentially reducing the number of unnecessary biopsies and missed cancers. This paper summarizes recent data on the efficacy of scintimammography using conventional gamma cameras, and describes the development of dedicated detectors for gamma emission breast imaging. The detectors use new, high density crystal scintillators and large area position sensitive photomultiplier tubes (PSPMTs). Detector design, imaging requirements, and preliminary measured imaging performance are discussed.

Study on response function of CdTe detector

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyunduk; Cho, Gyuseong [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon 305-701 (Korea, Republic of); Kang, Bo-Sun [Department of Radiological Science, Catholic University of Daegu, Kyoungsan, Kyoungbuk 712-702 (Korea, Republic of)], E-mail: bskang@cu.ac.kr

2009-10-21

So far the origin of the mechanism of light emission in the sonoluminescence has not elucidated whether it is due to blackbody radiation or bremsstrahlung. The final goal of our study is measuring X-ray energy spectrum using high-sensitivity cadmium telluride (CdTe) detector in order to obtain information for understanding sonoluminescence phenomena. However, the scope of this report is the measurement of X-ray spectrum using a high-resolution CdTe detector and determination of CdTe detector response function to obtain the corrected spectrum from measured soft X-ray source spectrum. In general, the measured spectrum was distorted by the characteristics of CdTe detector. Monte Carlo simulation code, MCNP, was used to obtain the reference response function of the CdTe detector. The X-ray spectra of {sup 57}Co, {sup 133}Ba, and {sup 241}Am were obtained by a 4x4x1.0(t) mm{sup 3} CdTe detector at room temperature.

Photon radiation damage simulations in CZT semiconducting detectors

International Nuclear Information System (INIS)

Leyva, A.; Pinnera, I.; Cruz, C.; Abreu, Y.; Dona, O.; Diaz, A.

2009-01-01

The use of semiconducting devices based on CZT as X and gamma rays detectors has been extended notably in the last decade thanks to their numerous advantages. The medical imagenology is one of the fields where these detectors have been successfully introduced, for example in positron emission tomography (PET). A typical CZT detector employed PET application was studied applying the Monte Carlo statistical method. All structural and geometric characteristics of the detector as well as the different photon energies usually used in the mentioned applications were considered in the simulations. Taking into account the Oen-Cahn-Holmes classical approach, the effective atomic displacement cross-sections and the number of displacements per atoms were calculated for all atom species and considered photon energies

A portable gas recirculation unit for gaseous detectors

Science.gov (United States)

Guida, R.; Mandelli, B.

2017-10-01

The use of greenhouse gases (usually C2H2F4, CF4 and SF6) is sometimes necessary to achieve the required performance for some gaseous detectors. The consumption of these gases in the LHC systems is reduced by recycling the gas mixture thanks to a complex gas recirculation system. Beyond greenhouse gas consumption due to LHC systems, a considerable contribution is generated by setups used for LHC detector upgrade projects, R&D activities, detector quality assurance or longevity tests. In order to minimise this emission, a new flexible and portable gas recirculation unit has been developed. Thanks to its low price, flexibility and user-friendly operation it can be easily adapted for the different types of detector systems and set-ups.

Statistical Detection of the He ii Transverse Proximity Effect: Evidence for Sustained Quasar Activity for >25 Million Years

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Tobias M. [Department of Physics, University of California, Santa Barbara, Santa Barbara, CA (United States); Max-Planck-Institut für Astronomie, Heidelberg (Germany); Worseck, Gabor [Max-Planck-Institut für Astronomie, Heidelberg (Germany); Hennawi, Joseph F. [Department of Physics, University of California, Santa Barbara, Santa Barbara, CA (United States); Max-Planck-Institut für Astronomie, Heidelberg (Germany); Prochaska, J. Xavier [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, Santa Cruz, Santa Cruz, CA (United States); Crighton, Neil H. M. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne, VIC (Australia); Lukić, Zarija [Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Oñorbe, Jose, E-mail: tschmidt@mpia.de [Max-Planck-Institut für Astronomie, Heidelberg (Germany)

2017-10-17

The reionization of helium at z ~ 3 is the final phase transition of the intergalactic medium and supposed to be driven purely by quasars. The He ii transverse proximity effect—enhanced He ii transmission in a background sightline caused by the ionizing radiation of a foreground quasar—therefore offers a unique opportunity to probe the morphology of He ii reionization and to investigate the emission properties of quasars, e.g., ionizing emissivity, lifetime and beaming geometry. We use the most-recent HST/COS far-UV dataset of 22 He ii absorption spectra and conduct our own dedicated optical spectroscopic survey to find foreground quasars around these He ii sightlines. Based on a set of 66 foreground quasars, we perform the first statistical analysis of the He ii transverse proximity effect. Despite a large object-to-object variance, our stacking analysis reveals an excess in the average He ii transmission near the foreground quasars at 3σ significance. This statistical evidence for the transverse proximity effect is corroborated by a clear dependence of the signal strength on the inferred He ii ionization rate at the background sightline. Our detection places, based on the transverse light crossing time, a geometrical limit on the quasar lifetime of t{sub Q} > 25 Myr. This evidence for sustained activity of luminous quasars is relevant for the morphology of H i and He ii reionization and helps to constrain AGN triggering mechanisms, accretion physics and models of black hole mass assembly. We show how future modeling of the transverse proximity effect can additionally constrain quasar emission geometries and e.g., clarify if the large observed object-to-object variance can be explained by current models of quasar obscuration.

Characterisation of the SmartPET planar Germanium detectors

Energy Technology Data Exchange (ETDEWEB)

Boston, H.C. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L69 7ZE (United Kingdom)], E-mail: H.C.Boston@liverpool.ac.uk; Boston, A.J.; Cooper, R.J.; Cresswell, J.; Grint, A.N.; Mather, A.R.; Nolan, P.J.; Scraggs, D.P.; Turk, G. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L69 7ZE (United Kingdom); Hall, C.J.; Lazarus, I. [CCLRC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom); Berry, A.; Beveridge, T.; Gillam, J.; Lewis, R. [School of Physics and Materials Engineering, Monash University, Melbourne (Australia)

2007-08-21

Small Animal Reconstruction PET (SmartPET) is a project funded by the UK medical research council (MRC) to demonstrate proof of principle that Germanium can be utilised in Positron Emission Tomography (PET). The SmartPET demonstrator consists of two orthogonal strip High Purity Germanium (HPGe) planar detectors manufactured by ORTEC. The aim of the project is to produce images of an internal source with sub mm{sup 3} spatial resolution. Before this image can be achieved the detectors have to be fully characterised to understand the response at any given location to a {gamma}-ray interaction. This has been achieved by probing the two detectors at a number of specified points with collimated sources of various energies and strengths. A 1 mm diameter collimated beam of photons was raster scanned in 1 mm steps across the detector. Digital pulse shape data were recorded from all the detector channels and the performance of the detector for energy and position determination has been assessed. Data will be presented for the first SmartPET detector.

Construction of a positron emission tomograph with 2.4 mm detectors

International Nuclear Information System (INIS)

McIntyre, J.A.; Sprosst, R.L.; Wang, K.

1986-01-01

One-quarter of one ring of a positron tomograph has been constructed. The positron annihilation gamma rays are detected by polished plastic scintillators which direct scintillation light by internal reflection to optical fibers for transmission to the photo-multiplier tubes. By viewing each scintillator with four sets of optical fibers, the number of photomultipliers required for an eight ring tomograph with 1024 detectors per ring (2.4 mm wide detectors) can be reduced from 8192 to 288, and the cost of the tomograph reduced accordingly

Characterization of detectors of neutrons from B+ZnS (Ag) as an alternative to 3He detectors

International Nuclear Information System (INIS)

Gonzalez, Juan A.; Suarez, Maria J.; Pujol, Luis; Lorente, Alfredo; Gallego, Eduardo

2013-01-01

The objective of this paper is to present the progress made in the design of prototypes for dynamic detection of neutron detectors based on scintillation of B + ZnS (Ag), which can replace existing 3 He detectors for the detection of illicit traffic of radioactive material and special nuclear material. These detectors B + ZnS (Ag) can be used, together with gamma detectors, PVT and NaI (Tl) also developed in the UPM. Two neutron detectors of different shapes and sizes were characterized using two neutron sources of 241 Am + Be. Were determined depth, overall efficiency, intrinsic efficiency and limit of detection. The results of these tests allow to verify that: 1) two cylindrical detectors B + ZnS (Ag) of 5x68 cm, or 4x15x132 cm rectangular detector can replace the cylindrical detector of 5x180 cm 3 He currently employed in the arcades. 2) the dynamic detection limit obtained is less than 20000 neutrons per second, when the sample becomes 2 m to 2m/s, with a probability of having no false positive or negative of the 99.99% 3) digital electronics eliminates interference from gamma emissions samples when their dose rate in the neutron detector is 65 μSv/h in less than factor 10 - 8, and keeps its detection limit and 4) two cylindrical detectors with two moderators of different thickness, of 25 to 50 mm of high density polyethylene, allow to measure the average energy of the neutrons

Proximity credentials: A survey

International Nuclear Information System (INIS)

Wright, L.J.

1987-04-01

Credentials as a means of identifying individuals have traditionally been a photo badge and more recently, the coded credential. Another type of badge, the proximity credential, is making inroads in the personnel identification field. This badge can be read from a distance instead of being veiewed by a guard or inserted into a reading device. This report reviews proximity credentials, identifies the companies marketing or developing proximity credentials, and describes their respective credentials. 3 tabs

Application of position-sensitive detectors to positron imaging

International Nuclear Information System (INIS)

Yamashita, Takaji; Uchida, Hiroshi; Watanabe, Mitsuo; Omura, Tomohide

1994-01-01

Positron imaging including positron emission tomography (PET) is expected to be a promising tool for basic and clinical research, because it makes possible the study of regional chemistry within multiple organs of the body in living human beings and experimental animals. New schemes of high resolution block detectors have been developed to improve the performance of positron imaging systems, which employ small segments of bismuth germanate (BGO) arrays and position-sensitive photomultiplier tubes (PS-PMT). The coincidence detector resolution of less than 2.0 mm in full width at half maximum was achieved with the detectors, which is very close to the theoretical resolution limit in positron imaging. (author)

X-ray Emission from Solar Flares

Indian Academy of Sciences (India)

2016-01-27

Jan 27, 2016 ... Solar flares; X-ray detectors; X-ray line emission and continuum; break energy; microflares. Abstract. Solar X-ray Spectrometer (SOXS), the first space-borne solar astronomy experiment of India was designed to improve our current understanding of X-ray emission from the Sun in general and solar flares in ...

Fabrication of silicon strip detectors using a step-and-repeat lithography system

International Nuclear Information System (INIS)

Holland, S.

1991-11-01

In this work we describe the use of a step-and-repeat lithography system (stepper) for the fabrication of silicon strip detectors. Although the field size of the stepper is only 20 mm in diameter, we have fabricated much larger detectors by printing a repetitive strip detector pattern in a step-and-repeat fashion. The basic unit cell is 7 mm in length. The stepper employs a laser interferometer for stage placement, and the resulting high precision allows one to accurately place the repetitive patterns on the wafer. A small overlap between the patterns ensures a continuous strip. A detector consisting of 512 strips on a 50 μm pitch has been fabricated using this technique. The dimensions of the detector are 6.3 cm by 2.56 cm. Yields of over 99% have been achieved, where yield is defined as the percentage of strips with reverse leakage current below 1 nA. In addition to the inherent advantages of a step-and-repeat system, this technique offers great flexibility in the fabrication of large-area strip detectors since the length and width of the detector can be changed by simply reprogramming the stepper computer. Hence various geometry strip detectors can be fabricated with only one set of masks, as opposed to a separate set of masks for each geometry as would be required with a contact or proximity aligner

New Type Far IR and THz Schottky Barrier Detectors for Scientific and Civil Application

Directory of Open Access Journals (Sweden)

V. G. Ivanov

2011-01-01

Full Text Available The results of an experimental investigation into a new type of VLWIR detector based on hot electron gas emission and architecture of the detector are presented and discussed. The detectors (further referred to as HEGED take advantage of the thermionic emission current change effect in a semiconductor diode with a Schottky barrier (SB as a result of the direct transfer of the absorbed radiation energy to the system of electronic gas in the quasimetallic layer of the barrier. The possibility of detecting radiation having the energy of quantums less than the height of the Schottky diode potential barrier and of obtaining a substantial improvement of a cutoff wavelength to VLWIR of the PtSi/Si detector has been demonstrated. The complementary contribution of two physical mechanisms of emanation detection—“quantum” and hot electrons gas emission—has allowed the creation of a superwideband IR detector using standard silicon technology.

Performance overview of the Euclid infrared focal plane detector subsystems

Science.gov (United States)

Waczynski, A.; Barbier, R.; Cagiano, S.; Chen, J.; Cheung, S.; Cho, H.; Cillis, A.; Clémens, J.-C.; Dawson, O.; Delo, G.; Farris, M.; Feizi, A.; Foltz, R.; Hickey, M.; Holmes, W.; Hwang, T.; Israelsson, U.; Jhabvala, M.; Kahle, D.; Kan, Em.; Kan, Er.; Loose, M.; Lotkin, G.; Miko, L.; Nguyen, L.; Piquette, E.; Powers, T.; Pravdo, S.; Runkle, A.; Seiffert, M.; Strada, P.; Tucker, C.; Turck, K.; Wang, F.; Weber, C.; Williams, J.

2016-07-01

In support of the European space agency (ESA) Euclid mission, NASA is responsible for the evaluation of the H2RG mercury cadmium telluride (MCT) detectors and electronics assemblies fabricated by Teledyne imaging systems. The detector evaluation is performed in the detector characterization laboratory (DCL) at the NASA Goddard space flight center (GSFC) in close collaboration with engineers and scientists from the jet propulsion laboratory (JPL) and the Euclid project. The Euclid near infrared spectrometer and imaging photometer (NISP) will perform large area optical and spectroscopic sky surveys in the 0.9-2.02 μm infrared (IR) region. The NISP instrument will contain sixteen detector arrays each coupled to a Teledyne SIDECAR application specific integrated circuit (ASIC). The focal plane will operate at 100K and the SIDECAR ASIC will be in close proximity operating at a slightly higher temperature of 137K. This paper will describe the test configuration, performance tests and results of the latest engineering run, also known as pilot run 3 (PR3), consisting of four H2RG detectors operating simultaneously. Performance data will be presented on; noise, spectral quantum efficiency, dark current, persistence, pixel yield, pixel to pixel uniformity, linearity, inter pixel crosstalk, full well and dynamic range, power dissipation, thermal response and unit cell input sensitivity.

Noiseless imaging detector for adaptive optics with kHz frame rates

CERN Document Server

Vallerga, J V; Mikulec, Bettina; Tremsin, A; Clark, Allan G; Siegmund, O H W; CERN. Geneva

2004-01-01

A new hybrid optical detector is described that has many of the attributes desired for the next generation AO wavefront sensors. The detector consists of a proximity focused MCP read out by four multi-pixel application specific integrated circuit (ASIC) chips developed at CERN (â€ﾜMedipix2”) with individual pixels that amplify, discriminate and count input events. The detector has 512 x 512 pixels, zero readout noise (photon counting) and can be read out at 1 kHz frame rates. The Medipix2 readout chips can be electronically shuttered down to a temporal window of a few microseconds with an accuracy of 10 nanoseconds. When used in a Shack-Hartman style wavefront sensor, it should be able to centroid approximately 5000 spots using 7 x 7 pixel sub-apertures resulting in very linear, off-null error correction terms. The quantum efficiency depends on the optical photocathode chosen for the bandpass of interest. A three year development effort for this detector technology has just been funded as part of the...

Triton burnup study using scintillating fiber detector on JT-60U

International Nuclear Information System (INIS)

Harano, Hideki

1997-09-01

The DT fusion reactor cannot be realized without knowing how the fusion-produced 3.5 MeV α particles behave. The α particles' behavior can be simulated using the 1 MeV triton. To investigate the 1 MeV triton's behavior, a new type of directional 14 MeV neutron detector, scintillating fiber (Sci-Fi) detector has been developed and installed on JT-60U in the cooperation with LANL as part of a US-Japan collaboration. The most remarkable feature of the Sci-Fi detector is that the plastic scintillating fibers are employed for the neutron sensor head. The Sci-Fi detector measures and extracts the DT neutrons from the fusion radiation field in high time resolution (10 ms) and wide dynamic range (3 decades). Triton burnup analysis code TBURN has been made in order to analyze the time evolution of DT neutron emission rate obtained by the Sci-Fi detector. The TBURN calculations reproduced the measurements fairly well, and the validity of the calculation model that the slowing down of the 1 MeV triton was classical was confirmed. The Sci-Fi detector's directionality indicated the tendency that the DT neutron emission profile became more and more peaked with the time progress. In this study, in order to examine the effect of the toroidal field ripple on the triton burnup, R p -scan and n e -scan experiments have been performed. The R p -scan experiment indicates that the triton's transport was increased as the ripple amplitude over the triton became larger. In the n e -scan experiment, the DT neutron emission showed the characteristic changes after the gas puffing injection. It was theoretically confirmed that the gas puffing was effective for the collisionality scan. (J.P.N.) 127 refs

Extraction of butyltins from sediments and their determination by liquid chromatography interfaced to inductively coupled plasma atomic emission detector

International Nuclear Information System (INIS)

Rivaro, P.; Frache, R.

2000-01-01

A liquid-liquid extraction of the butyltin compounds from sediment, suitable for their subsequent following determination by high performance liquid chromatography-hydride generation inductively coupled plasma atomic emission detector system, is proposed. Recoveries of 86%, 80% and 42% for tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) respectively were achieved. The relative detection limits of butyltin compounds by this method ranged from 27 to 62 ng of tin per gram of dry sediment. The method was applied to real sediment samples collected in the Venice lagoon (Italy). The results showed that, despite the restrictions on the use of butyltin contained in antifoulting paints, a considerable amount of organotin compounds is still present in Venice sediments [it

Development of a 144-channel Hybrid Avalanche Photo-Detector for Belle II ring-imaging Cherenkov counter with an aerogel radiator

Energy Technology Data Exchange (ETDEWEB)

Nishida, S., E-mail: shohei.nishida@kek.jp [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Adachi, I. [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Hamada, N. [Toho University, Funabashi (Japan); Hara, K. [High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Iijima, T. [Nagoya University, Nagoya (Japan); Iwata, S.; Kakuno, H. [Tokyo Metropolitan University, Hachioji (Japan); Kawai, H. [Chiba University, Chiba (Japan); Korpar, S.; Krizan, P. [Jozef Stefan Institute, Ljubljana (Slovenia); Ogawa, S. [Toho University, Funabashi (Japan); Pestotnik, R.; Ŝantelj, L.; Seljak, A. [Jozef Stefan Institute, Ljubljana (Slovenia); Sumiyoshi, T. [Tokyo Metropolitan University, Hachioji (Japan); Tabata, M. [Chiba University, Chiba (Japan); Tahirovic, E. [Jozef Stefan Institute, Ljubljana (Slovenia); Yoshida, K. [Tokyo Metropolitan University, Hachioji (Japan); Yusa, Y. [Niigata University, Niigata (Japan)

2015-07-01

The Belle II detector, a follow up of the very successful Belle experiment, is under construction at the SuperKEKB electron–positron collider at KEK in Japan. For the PID system in the forward region of the spectrometer, a proximity-focusing ring-imaging Cherenkov counter with an aerogel radiator is being developed. For the position sensitive photon sensor, a 144-channel Hybrid Avalanche Photo-Detector has been developed with Hamamatsu Photonics K.K. In this report, we describe the specification of the Hybrid Avalanche Photo-Detector and the status of the mass production.

Positron emission tomography camera

International Nuclear Information System (INIS)

Anon.

1987-01-01

A positron emission tomography camera having a plurality of detector rings positioned side-by-side or offset by one-half of the detector cross section around a patient area to detect radiation therefrom. Each detector ring or offset ring includes a plurality of photomultiplier tubes and a plurality of scintillation crystals are positioned relative to the photomultiplier tubes whereby each tube is responsive to more than one crystal. Each alternate crystal in the ring is offset by one-half or less of the thickness of the crystal such that the staggered crystals are seen by more than one photomultiplier tube. This sharing of crystals and photomultiplier tubes allows identification of the staggered crystal and the use of smaller detectors shared by larger photomultiplier tubes thereby requiring less photomultiplier tubes, creating more scanning slices, providing better data sampling, and reducing the cost of the camera. The offset detector ring geometry reduces the costs of the positron camera and improves its performance

Silicon carbide detectors for diagnostics of ion emission from laser plasmas

International Nuclear Information System (INIS)

Musumeci, Paolo; Zimbone, Massimo; Calcagno, Lucia; Cutroneo, Maria; Torrisi, Lorenzo; Velyhan, Andry

2014-01-01

Silicon carbide (SiC) detectors have been employed to analyze the multi-MeV ions generated from laser plasma. The irradiation was performed with the iodine laser of Prague Asterix Laser System Laboratory operating at 10 16  W cm −2 pulse intensity. Thin metallic and polymeric targets were irradiated and the produced plasmas were monitored in the forward direction. The use of SiC detectors ensures the cutting of the visible and soft UV radiation emitted from plasma, enhancing the sensitivity to protons and very fast heavy ions. The time-of-flight spectra obtained by irradiating polymeric films with high laser pulse energy produce protons with energy in the range 1.0–2.5 MeV and all the charge states of carbon ions. The metallic Al target allows achieving energy up to 3.0 MeV for protons and 40 MeV for Al ions. All the results reveal the high performances of these detectors in terms of resolution and response time. (paper)

Position sensitivity of the first SmartPET HPGe detector

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, University of Liverpool, Liverpool (United Kingdom)]. E-mail: rjc@ns.ph.liv.ac.uk; Turk, G. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Boston, A.J. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Boston, H.C. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Cresswell, J.R. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Mather, A.R. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Nolan, P.J. [Department of Physics, University of Liverpool, Liverpool (United Kingdom); Hall, C.J. [CCLRC Daresbury, Warrington, Cheshire (United Kingdom); Lazarus, I. [CCLRC Daresbury, Warrington, Cheshire (United Kingdom); Simpson, J. [CCLRC Daresbury, Warrington, Cheshire (United Kingdom); Berry, A. [School of Physics and materials Engineering, Monash University, Melbourne (Australia); Beveridge, T. [School of Physics and materials Engineering, Monash University, Melbourne (Australia); Gillam, J. [School of Physics and materials Engineering, Monash University, Melbourne (Australia); Lewis, R.A. [School of Physics and materials Engineering, Monash University, Melbourne (Australia)

2007-04-01

In this paper we discuss the Smart Positron Emission Tomography (PET) imaging system being developed by University of Liverpool in conjunction with CCLRC Daresbury Laboratory. We describe the motivation for the development of a semiconductor-based PET system and the advantages it will offer over current tomographs. Details of the detectors and associated electronics are discussed and results of high precision scans are presented. Analysis of this scan data has facilitated full characterization of the detector response function and calibration of the three-dimensional position sensitivity. This work presents the analysis of the depth sensitivity of the detector.

Measurement and Modeling of Blocking Contacts for Cadmium Telluride Gamma Ray Detectors

Energy Technology Data Exchange (ETDEWEB)

Beck, Patrick R. [California Polytechnic State Univ. (CalPoly), San Luis Obispo, CA (United States)

2010-01-07

Gamma ray detectors are important in national security applications, medicine, and astronomy. Semiconductor materials with high density and atomic number, such as Cadmium Telluride (CdTe), offer a small device footprint, but their performance is limited by noise at room temperature; however, improved device design can decrease detector noise by reducing leakage current. This thesis characterizes and models two unique Schottky devices: one with an argon ion sputter etch before Schottky contact deposition and one without. Analysis of current versus voltage characteristics shows that thermionic emission alone does not describe these devices. This analysis points to reverse bias generation current or leakage through an inhomogeneous barrier. Modeling the devices in reverse bias with thermionic field emission and a leaky Schottky barrier yields good agreement with measurements. Also numerical modeling with a finite-element physics-based simulator suggests that reverse bias current is a combination of thermionic emission and generation. This thesis proposes further experiments to determine the correct model for reverse bias conduction. Understanding conduction mechanisms in these devices will help develop more reproducible contacts, reduce leakage current, and ultimately improve detector performance.

NeuRad detector prototype pulse shape study

Science.gov (United States)

Muzalevsky, I.; Chudoba, V.; Belogurov, S.; Kiselev, O.; Bezbakh, A.; Fomichev, A.; Krupko, S.; Slepnev, R.; Kostyleva, D.; Gorshkov, A.; Ovcharenko, E.; Schetinin, V.

2018-04-01

The EXPERT setup located at the Super-FRS facility, the part of the FAIR complex in Darmstadt, Germany, is intended for investigation of properties of light exotic nuclei. One of its modules, the high granularity neutron detector NeuRad assembled from a large number of the scintillating fiber is intended for registration of neutrons emitted by investigated nuclei in low-energy decays. Feasibility of the detector strongly depends on its timing properties defined by the spatial distribution of ionization, light propagation inside the fibers, light emission kinetics and transition time jitter in the multi-anode photomultiplier tube. The first attempt of understanding the pulse formation in the prototype of the NeuRad detector by comparing experimental results and Monte Carlo (MC) simulations is reported in this paper.

An electrostatic detector for dust measurement on HT-7 tokamak

International Nuclear Information System (INIS)

Ling, B.L.; Zhang, X.D.; Ti, A.; Gao, X.

2007-01-01

An electrostatic dust detector has been successfully developed to measure dust event in situ and in real time on the HT-7 tokamak. For measuring dust near the edge plasmas and preventing interference of electrons and ions, the shielding plates were designed and installed around the dust detector. The electric signal of dust has been successfully measured during LHCD discharges on HT-7 tokamak. The measured dust signal was in good agreement with bursts appeared on multi-channel H α radiation and on multi-channel ECE diagnostics. Diagnostics of the spectrum and the measurement of impurity emission during dust bursts were studied in detail. It is interesting that there is a delay between dust bursts and CIII line emission. It is observed that the delay time between dust signal and measured CIII line emission is about 0.3 ms in the HT-7 tokamak

Recent developments in positron emission tomography (PET) instrumentation

Energy Technology Data Exchange (ETDEWEB)

Derenzo, S.E.; Budinger, T.F.

1986-04-01

This paper presents recent detector developments and perspectives for positron emission tomography (PET) instrumentation used for medical research, as well as the physical processes in positron annihilation, photon scattering and detection, tomograph design considerations, and the potentials for new advances in detectors. 117 refs., 4 figs., 4 tabs.

Recent developments in positron emission tomography (PET) instrumentation

International Nuclear Information System (INIS)

Derenzo, S.E.; Budinger, T.F.

1986-04-01

This paper presents recent detector developments and perspectives for positron emission tomography (PET) instrumentation used for medical research, as well as the physical processes in positron annihilation, photon scattering and detection, tomograph design considerations, and the potentials for new advances in detectors. 117 refs., 4 figs., 4 tabs

Molybdenum-gold proximity bilayers as transition edge sensors for microcalorimeters and bolometers

International Nuclear Information System (INIS)

Chen, T.C.; Bier, A.; DiCamillo, B.; Finkbeiner, F. M.

1999-01-01

Mo/Au proximity bilayers as transition edge sensors (TESs) are promising candidates for low-temperature thermometry. The transition temperature of the bilayers can be easily tuned between 50 and 600 mK, yielding sensors which can be used in a variety of calorimetric and bolometric applications. With phase transition widths of less than 1 mK, Mo/Au TESs show very high temperature sensitivity (d(logR)/d(logT)∼2500). Also, Mo/Au TESs show improved thermal and chemical stability compared to most other bilayer configurations. Fabrication issues and detector performance of Mo/Au TESs on Si 3 N 4 membranes are discussed. (author)

SPECT detector system design based on embedded system

International Nuclear Information System (INIS)

Zhang Weizheng; Zhao Shujun; Zhang Lei; Sun Yuanling

2007-01-01

A single-photon emission computed tomography detector system based on embedded Linux designed. This system is composed of detector module, data acquisition module, ARM MPU module, network interface communication module and human machine interface module. Its software uses multithreading technology based on embedded Linux. It can achieve high speed data acquisition, real-time data correction and network data communication. It can accelerate the data acquisition and decrease the dead time. The accuracy and the stability of the system can be improved. (authors)

A proximal point algorithm with generalized proximal distances to BEPs

OpenAIRE

Bento, G. C.; Neto, J. X. Cruz; Lopes, J. O.; Soares Jr, P. A.; Soubeyran, A.

2014-01-01

We consider a bilevel problem involving two monotone equilibrium bifunctions and we show that this problem can be solved by a proximal point method with generalized proximal distances. We propose a framework for the convergence analysis of the sequences generated by the algorithm. This class of problems is very interesting because it covers mathematical programs and optimization problems under equilibrium constraints. As an application, we consider the problem of the stability and change dyna...

A novel depth-of-interaction block detector for positron emission tomography using a dichotomous orthogonal symmetry decoding concept

International Nuclear Information System (INIS)

Zhang, Yuxuan; Yan, Han; Baghaei, Hossain; Wong, Wai-Hoi

2016-01-01

Conventionally, a dual-end depth-of-interaction (DOI) block detector readout requires two two-dimensional silicon photomultiplier (SiPM) arrays, one on top and one on the bottom, to define the XYZ positions. However, because both the top and bottom SiPM arrays are reading the same pixels, this creates information redundancy. We propose a dichotomous orthogonal symmetric (DOS) dual-end readout block detector design, which removes this redundancy by reducing the number of SiPMs and still achieves XY and DOI (Z) decoding for positron emission tomography (PET) block detector. Reflecting films are used within the block detector to channel photons going to the top of the block to go only in the X direction, and photons going to the bottom are channeled along the Y direction. Despite the unidirectional channeling on each end, the top readout provides both X and Y information using two one-dimensional SiPM arrays instead of a two-dimensional SiPM array; similarly, the bottom readout also provides both X and Y information with just two one-dimensional SiPM arrays. Thus, a total of four one-dimensional SiPM arrays (4  ×  N SiPMs) are used to decode the XYZ positions of the firing pixels instead of two two-dimensional SiPM arrays (2  ×  N  ×  N SiPMs), reducing the number of SiPM arrays per block from 2N 2 to 4 N for PET/MR or PET/CT systems. Moreover, the SiPM arrays on one end can be replaced by two regular photomultiplier tubes (PMTs), so that a block needs only 2 N SiPMs  +  2 half-PMTs; this hybrid-DOS DOI block detector can be used in PET/CT systems. Monte Carlo simulations were carried out to study the performance of our DOS DOI block detector design, including the XY-decoding quality, energy resolution, and DOI resolution. Both BGO and LSO scintillators were studied. We found that 4 mm pixels were well decoded for 5  ×  5 BGO and 9  ×  9 LSO arrays with 4 to 5 mm DOI resolution and 16–20% energy resolution

Well logging radioactive detector assembly

International Nuclear Information System (INIS)

Osburn, T.D.

1992-01-01

This patent describes a well logging instrument of the type having a radioactive logging sub having a sealed chamber and have a radioactive source for emitting radioactive energy into the well formation, the instrument having a radioactive energy detector for detecting gamma rays resulting from the emission of the radioactive energy into the well formation, and means for pressing the sub against the well of the well, an improved Dewar flask for the detector. It comprises: an inner housing formed of titanium and containing the detector; an outer housing formed of titanium, having a cylindrical side wall surrounding the inner housing and separated by a clearance which is evacuated, the outer housing being located within the sealed chamber in the sub of the instrument; a window section formed in the side wall of the outer housing adjacent the detector and on a side of the side wall closest to the wall of the well when the sub is pressed against the wall of the well; and wherein the inner housing has a cylindrical side wall that is of lesser wall thickness than the wall thickness of the side wall of the outer housing other than in the window section

Positron Emission Tomography imaging with the SmartPET system

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, University of Liverpool, Liverpool, Merseyside L69 7ZE (United Kingdom)], E-mail: cooperrj@ornl.gov; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Grint, A.N.; Harkness, L.J.; Nolan, P.J.; Oxley, D.C.; Scraggs, D.P.; Mather, A.R. [Department of Physics, University of Liverpool, Liverpool, Merseyside L69 7ZE (United Kingdom); Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD (United Kingdom)

2009-07-21

The Small Animal Reconstruction Tomograph for Positron Emission Tomography (SmartPET) project is the development of a small animal Positron Emission Tomography (PET) demonstrator based on the use of High-Purity Germanium (HPGe) detectors and state of the art digital electronics. The experimental results presented demonstrate the current performance of this unique system. By performing high precision measurements of one of the SmartPET HPGe detectors with a range of finely collimated gamma-ray beams the response of the detector as a function of gamma-ray interaction position has been quantified, facilitating the development of parametric Pulse Shape Analysis (PSA) techniques and algorithms for the correction of imperfections in detector performance. These algorithms have then been applied to data from PET imaging measurements using two such detectors in conjunction with a specially designed rotating gantry. In this paper we show how the use of parametric PSA approaches allows over 60% of coincident events to be processed and how the nature and complexity of an event has direct implications for the quality of the resulting image.

Evaluation of detector efficiency through GUPIXWIN H value

Science.gov (United States)

Fernandes, F.; Niekraszewicz, L. A. B.; Amaral, L.; Dias, J. F.

2018-02-01

In this work we explore the capabilities of the GUPIXWIN software to introduce a simple and straightforward way to obtain the efficiency of X-ray detectors commonly used in PIXE (Particle-Induced X-ray Emission) experiments. To that end, all geometrical parameters of the experimental setup including details of the detector used to detect X-rays must be well known in order to calculate the solid angle subtended by the detector's crystal. The solid angle is calculated through a Monte Carlo program developed by Taylor and co-workers which is included in the GUPIXWIN software package. The H values are obtained from a set of experiments using standards. The results for the intrinsic efficiency of a Si(Li) detector are in good agreement with those obtained from Monte Carlo calculations and are compatible with a simple exponential law.

Performance characterization of compressed sensing positron emission tomography detectors and data acquisition system

Science.gov (United States)

Chang, Chen-Ming; Grant, Alexander M.; Lee, Brian J.; Kim, Ealgoo; Hong, KeyJo; Levin, Craig S.

2015-08-01

In the field of information theory, compressed sensing (CS) had been developed to recover signals at a lower sampling rate than suggested by the Nyquist-Shannon theorem, provided the signals have a sparse representation with respect to some base. CS has recently emerged as a method to multiplex PET detector readouts thanks to the sparse nature of 511 keV photon interactions in a typical PET study. We have shown in our previous numerical studies that, at the same multiplexing ratio, CS achieves higher signal-to-noise ratio (SNR) compared to Anger and cross-strip multiplexing. In addition, unlike Anger logic, multiplexing by CS preserves the capability to resolve multi-hit events, in which multiple pixels are triggered within the resolving time of the detector. In this work, we characterized the time, energy and intrinsic spatial resolution of two CS detectors and a data acquisition system we have developed for a PET insert system for simultaneous PET/MRI. The CS detector comprises a 2× 4 mosaic of 4× 4 arrays of 3.2× 3.2× 20 mm3 lutetium-yttrium orthosilicate crystals coupled one-to-one to eight 4× 4 silicon photomultiplier arrays. The total number of 128 pixels is multiplexed down to 16 readout channels by CS. The energy, coincidence time and intrinsic spatial resolution achieved by two CS detectors were 15.4+/- 0.1 % FWHM at 511 keV, 4.5 ns FWHM and 2.3 mm FWHM, respectively. A series of experiments were conducted to measure the sources of time jitter that limit the time resolution of the current system, which provides guidance for potential system design improvements. These findings demonstrate the feasibility of compressed sensing as a promising multiplexing method for PET detectors.

Characteristics of NaI detector in positron imaging device HEADTOME employing circular ring array

International Nuclear Information System (INIS)

Miura, Shuichi; Kanno, Iwao; Aizawa, Yasuo; Murakami, Matsutaro; Uemura, Kazuo

1984-01-01

In positron emission computed tomographs employing circular ring arrays of detectors, the performance of the imaging device has been specified ultimately by the characteristics of the detector. The responses of NaI detector were studied when detecting positron annihilation photon (511 keV). The study was mainly by using the NaI detector used in hybrid emission computed tomography (CT) ''HEADTOME'' we had developed. A series of measurements were carried out positioning two detectors with 40 cm distance and scanning 22 Na point source in water. Both detectors was inclined from 0 0 through 30 0 to change incident angle of positron annihilation toward crystal face. Energy window was set from 100 to 700 keV. The results were presented as follows; 1 Shortening the crystal length from 7 to 5 cm made sensitivity decrease about 10% and resolution deteriorate about 1 mm (FWHM). 2 As the results of varying the width of the crystal, 20 mm width was optimal at any incident angle. 3 The lead septum between the detectors was the thickness of 4 mm enough to reject multiple detector interactions (crosstalk). 4 Beam mask which was made of lead in order to improve spatial resolution and placed on crystal face worked effectively for incident angles from 0 0 to 15 0 but degraded uniformity of spatial resolution from 0 0 to through 30 0 . (author)

ENC Measurement for ASIC Preamp Board as a Detector Module for PET System

Directory of Open Access Journals (Sweden)

N. Nagara

2016-08-01

Full Text Available We developed a gamma ray detector with an LuAG:Pr scintillator and an avalanche photodiode as a detector for a positron emission tomography (PET system. Studies have been performed on the influences of gamma irradiation on application-specific integrated circuit (ASIC preamp boards used as a detector module. As a device used in nuclear environments for substantial durations, the ASIC has to have a lifetime long enough to ensure that there will be a negligible failure rate during this period. These front-end systems must meet the requirements for standard positron emission tomography (PET systems. Therefore, an equivalent noise charge (ENC experiment is needed to measure the front-end system's characteristics. This study showed that minimum ENC conditions can be achieved if a shorter shaping time could be applied.

A Fiber-Optic Neutron Detector for a Drive-By Scenario

International Nuclear Information System (INIS)

Miley, H.S.

1999-01-01

The measurement scenario of a neutron source driving by a detector has been evaluated. It is possible to use PNNL lithium-loaded fiber optics to measure the source, even at reasonably high speeds. A detector sufficient to detect the neutrons from the source at a high confidence level can be produced in a compact and robust configuration for a reasonable cost. In addition, the PNNL solution measures gamma-ray signals and will effectively add the function of a proximity sensor, lower the false-alarm rate, and allow discrimination between certain neutron source scenarios. Finally, the need for definition of confidence levels (both the method of computation and the required false alarm probability), emplacement form-factor, and electronic interface is required of a potential user to revise or customize the design outlined in this paper

Medipix 2 detector applied to low energy electron microscopy

International Nuclear Information System (INIS)

Gastel, R. van; Sikharulidze, I.; Schramm, S.; Abrahams, J.P.; Poelsema, B.; Tromp, R.M.; Molen, S.J. van der

2009-01-01

Low energy electron microscopy (LEEM) and photo-emission electron microscopy (PEEM) traditionally use microchannel plates (MCPs), a phosphor screen and a CCD-camera to record images and diffraction patterns. In recent years, however, MCPs have become a limiting factor for these types of microscopy. Here, we report on a successful test series using a solid state hybrid pixel detector, Medipix 2, in LEEM and PEEM. Medipix 2 is a background-free detector with an infinite dynamic range, making it very promising for both real-space imaging and spectroscopy. We demonstrate a significant enhancement of both image contrast and resolution, as compared to MCPs. Since aging of the Medipix 2 detector is negligible for the electron energies used in LEEM/PEEM, we expect Medipix to become the detector of choice for a new generation of systems.

Medipix 2 detector applied to low energy electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Gastel, R. van, E-mail: R.vanGastel@utwente.nl [University of Twente, MESA Institute for Nanotechnology, P.O. Box 217, NL-7500 AE Enschede (Netherlands); Sikharulidze, I. [Leiden University, Leiden Institute of Chemistry, P.O. Box 9502, NL-2300 RA Leiden (Netherlands); Schramm, S. [Leiden University, Kamerlingh Onnes Laboratorium, P.O. Box 9504, NL-2300 RA Leiden (Netherlands); Abrahams, J.P. [Leiden University, Leiden Institute of Chemistry, P.O. Box 9502, NL-2300 RA Leiden (Netherlands); Poelsema, B. [University of Twente, MESA Institute for Nanotechnology, P.O. Box 217, NL-7500 AE Enschede (Netherlands); Tromp, R.M. [Leiden University, Kamerlingh Onnes Laboratorium, P.O. Box 9504, NL-2300 RA Leiden (Netherlands); IBM Research Division, T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Molen, S.J. van der [Leiden University, Kamerlingh Onnes Laboratorium, P.O. Box 9504, NL-2300 RA Leiden (Netherlands)

2009-12-15

Low energy electron microscopy (LEEM) and photo-emission electron microscopy (PEEM) traditionally use microchannel plates (MCPs), a phosphor screen and a CCD-camera to record images and diffraction patterns. In recent years, however, MCPs have become a limiting factor for these types of microscopy. Here, we report on a successful test series using a solid state hybrid pixel detector, Medipix 2, in LEEM and PEEM. Medipix 2 is a background-free detector with an infinite dynamic range, making it very promising for both real-space imaging and spectroscopy. We demonstrate a significant enhancement of both image contrast and resolution, as compared to MCPs. Since aging of the Medipix 2 detector is negligible for the electron energies used in LEEM/PEEM, we expect Medipix to become the detector of choice for a new generation of systems.

Exoelectron emission and its application for dosimetry

International Nuclear Information System (INIS)

Kawanishi, Masaharu

1975-01-01

The research on exoelectron emission has been recently very active in its fundamentals and applications. In the basic study, exoelectron emission and thermo-luminescence are explained by using energy band model. Physical and chemical properties of material surface, specifically surface adsorption phenomena, have been proven experimentally to give important effect on exoelectron emission by several people. It will be necessary in future that the identification of emitted particles and energy measurement become common in exoelectron physics. In spite of the difficulty to fabricate the uniformly stable materials emitting exoelectrons, much efforts are being made in the researches on the application to radiation dosimeters. The principal materials used to date are BeO, LiF, Al 2 O 3 , CaF 2 and CaSO 4 , the last one being most sensitive. On the other hand, the detectors for thermally stimulated exoelectron emission are important not only as dosimeters but for basic research promotion. The most convenient detector is a gas flow GM tube. Q gas or methane is used as flow gas. Though there remains many unknown fields in exoelectron emission mechanism, success in the application researches to effectively utilize their peculiarity and advantages is expected. (Wakatsuki, Y.)

Array Detector Modules for Spent Fuel Verification

Energy Technology Data Exchange (ETDEWEB)

Bolotnikov, Aleksey

2018-05-07

Brookhaven National Laboratory (BNL) proposes to evaluate the arrays of position-sensitive virtual Frisch-grid (VFG) detectors for passive gamma-ray emission tomography (ET) to verify the spent fuel in storage casks before storing them in geo-repositories. Our primary objective is to conduct a preliminary analysis of the arrays capabilities and to perform field measurements to validate the effectiveness of the proposed array modules. The outcome of this proposal will consist of baseline designs for the future ET system which can ultimately be used together with neutrons detectors. This will demonstrate the usage of this technology in spent fuel storage casks.

Positron transaxial emission tomograph with computerized image reconstruction

International Nuclear Information System (INIS)

Jatteau, Michel.

1981-01-01

This invention concerns a positron transaxial emission tomography apparatus with computerized image reconstruction, like those used in nuclear medicine for studying the metabolism of organs, in physiological examinations and as a diagnosis aid. The operation is based on the principle of the detection of photons emitted when the positrons are annihilated by impact with an electron. The appliance is mainly composed of: (a) - a set of gamma ray detectors distributed on a polygonal arrangement around the body area to be examined, (b) - circuits for amplifying the signals delivered by the gamma ray detectors, (c) - computers essentially comprising energy integration and discrimination circuits and provided at the output of the detectors for calculating and delivering, as from the amplified signals, information on the position and energy relative to each occurrence constituted by the detections of photons, (d) - time coincidence circuits for selecting by emission of detector validation signals, only those occurrences, among the ensemble of those detected, which effectively result from the annihilation of positrons inside the area examined, (e) - a data processing system [fr

Particle Detectors in the Theory of Quantum Fields on Curved Spacetimes

Science.gov (United States)

Cant, John Fraser

This work discusses aspects of a fundamental problem in the theory of quantum fields on curved spacetimes--that of giving physical meaning to the particle representations of the theory. In particular, the response of model particle detectors is analysed in detail. Unruh (1976) first introduced the idea of a model particle detector in order to give an operational definition to particles. He found that even in flat spacetime, the excitation of a particle detector does not necessarily correspond to the presence of an energy carrier--an accelerating detector will excite in response to the zero-energy state of the Minkowski vacuum. The central question I consider in this work is --where does the energy for the excitation of the accelerating detector come from? The accepted response has been that the accelerating force provides the energy. Evaluating the energy carried by the (conformally-invariant massless scalar) field after the interaction with the detector, however, I find that the detector excitation is compensated by an equal but opposite emission of negative energy. This result suggests that there may be states of lesser energy than that of the Minkowski vacuum. To resolve this paradox, I argue that the emission of a detector following a more realistic trajectory than that of constant acceleration--one that starts and finishes in inertial motion--will in total be positive, although during periods of constant acceleration the detector will still emit negative energy. The Minkowski vacuum retains its status as the field state of lowest energy. The second question I consider is the response of Unruh's detector in curved spacetime--is it possible to use such a detector to measure the energy carried by the field? In the particular case of a detector following a Killing trajectory, I find that there is a response to the energy of the field, but that there is also an inherent 'noise'. In a two dimensional model spacetime, I show that this 'noise' depends on the detector

Integration of a Fire Detector into a Spacecraft

Science.gov (United States)

Linford, R. M. F.

1972-01-01

A detector sensitive to only the ultraviolet radiation emitted by flames has been selected as the basic element of the NASA Skylab fire detection system. It is sensitive to approximately 10(exp -12)W of radiation and will detect small flames at distances in excess of 3m. The performance of the detector was verified by experiments in an aircraft flying zero-gravity parabolas to simulate the characteristics of a fire which the detector must sense. Extensive investigation and exacting design was necessary to exclude all possible sources of false alarms. Optical measurements were made on all the spacecraft windows to determine the amount of solar radiation transmitted. The lighting systems and the onboard experiments also were appraised for ultraviolet emissions. Proton-accelerator tests were performed to determine the interaction of the Earth's trapped radiation belts with the detectors and the design of the instrument was modified to negate these effects.

Methods for Attributing Land-Use Emissions to Products

Science.gov (United States)

Davis, S. J.; Burney, J. A.; Pongratz, J.; Caldeira, K.

2014-12-01

Roughly one-third of anthropogenic GHG emissions are caused by agricultural and forestry activities and land-use change (collectively, 'land-use emissions'). Understanding the ultimate drivers of these emissions requires attributing emissions to specific land-use activities and products. Although quantities of land-use emissions are matters of fact, the methodological choices and assumptions required to attribute those emissions to activities and products depend on research goals and data availability. We will demonstrate several possible accounting methods, highlighting the sensitivity of accounting to temporal distributions of emissions and the consequences of replacing spatially-explicit data with aggregate proxies such as production or harvested area data. Different accounting options emphasize different causes of land-use emissions (e.g., proximate or indirect drivers of deforestation). To support public policies that effectively balance competing objectives, analysts should carefully consider and communicate implications of accounting choices.

Correction of detector nonlinearity for the balloonborne Michelson Interferometer for Passive Atmospheric Sounding.

Science.gov (United States)

Kleinert, Anne

2006-01-20

The detectors used in the cryogenic limb-emission sounder MIPAS-B2 (Michelson Interferometer for Passive Atmospheric Sounding) show a nonlinear response, which leads to radiometric errors in the calibrated spectra if the nonlinearity is not taken into account. In the case of emission measurements, the dominant error that arises from the nonlinearity is the changing detector responsivity as the incident photon load changes. The effect of the distortion of a single interferogram can be neglected. A method to characterize the variable responsivity and to correct for this effect is proposed. Furthermore, a detailed error estimation is presented.

Emulation workbench for position sensitive gaseous scintillation detectors

International Nuclear Information System (INIS)

Pereira, L.; Margato, L.M.S.; Morozov, A.; Solovov, V.; Fraga, F. A. F.

2015-01-01

Position sensitive detectors based on gaseous scintillation proportional counters with Anger-type readout are being used in several research areas such as neutron detection, search for dark matter and neutrinoless double beta decay. Design and optimization of such detectors are complex and time consuming tasks. Simulations, while being a powerful tool, strongly depend on the light transfer models and demand accurate knowledge of many parameters, which are often not available. Here we describe an alternative approach based on the experimental evaluation of a detector using an isotropic point-like light source with precisely controllable light emission properties, installed on a 3D positioning system. The results obtained with the developed setup at validation conditions, when the scattered light is strongly suppressed show good agreement with simulations

LERFCM: a computer code for spatial reconstruction of volume emission from chord measurements in plasmas

International Nuclear Information System (INIS)

Navarro, A.P.; Pare, V.K.; Dunlap, J.L.

1981-01-01

Local Emissivity Reconstruction from Chord Measurements (LERFCM) is a package of computer programs used to determine the two-dimensional spatial distribution of the emission intensity of radiation in a plasma from line integral data, which represents signals from arrays of collimated detectors looking through the plasma along different chords in a plane. The method requires data from only a few detector arrays and assumes that the emission distribution in the plane of observation has a smooth angular dependence that can be represented by a few low-order harmonics. The intended application is a reconstruction of plasma shape and MHD instabilities, using data from arrays of soft x-ray detectors on Impurity Study Experiment Tokamak

Fragment emission from modestly excited nuclear systems

Energy Technology Data Exchange (ETDEWEB)

Lou, Y. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Souza, R.T. de [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Chen, S.L. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Cornell, E.W. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Davin, B. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Fox, D. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Hamilton, T.M. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Mcdonald, K. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Tsang, M.B. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Glasmacher, T. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Dinius, J. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Gelbke, C.K. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Handzy, D.O. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility]|[Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Hsi, W.C.

1996-07-08

Fragment emission patterns occurring in nuclear systems of modest excitation are studied. Exclusive measurement of fragment emission in {sup 14}N+{sup 197}Au reactions at E/A=100, 130 and 156 MeV allows selection of central collisions where a single source dominates the decay. Low threshold measurement of IMF emission for these events allows investigation of the influence of detector threshold effects. The time scale of fragment emission is deduced using fragment-fragment velocity correlations. Comparisons are made to the predictions of a statistical decay model. (orig.).

Design of neutron detectors utilising luminescent glass

International Nuclear Information System (INIS)

Spowart, A.R.

1983-01-01

Impetus for the development of new neutron detector designs has derived from the worldwide commissioning of neutron spallation sources. The design concepts, and principal methods of utilisation of these major installations, have been recently reviewed. Their principal feature of interest is their broadband neutron emission allowing neutron investigations of all types of structure in materials from biological molecules to steels. Conventional neutron detectors are gas-filled devices, based on BF/sub 3/ or /sup 3/He gas. Their major advantage is their intrinsically low background count. Their principal disadvantage is their slow response time (10-100 μs), high cost and relative lack of flexibility in design to cope with large areas or complex geometry detection. They are, however, long established and the research facilities around the world have a heavy investment in the interpretative hardware for gas detectors

A single photon emission computed tomograph based on a limited dumber of detectors for fluid flow visualization; Tomographie d'emission gamma a partir d'un nombre limite de detecteurs appliquee a la visualisation d'ecoulements

Energy Technology Data Exchange (ETDEWEB)

Legoupil, S

1999-07-01

We present in this work a method for fluid flow visualization in a system using radioactive tracers. The method is based on single photon emission computed tomography techniques, applied to a limited number of discrete detectors. We propose in this work a method for the estimation of the transport matrix of photons, associated to the acquisition system.This method is based on the modelization of profiles acquired for a set of point sources located in the imaged volume. Monte Carlo simulations allow to separate scattered photons from those directly collected by the system. The influence of the energy tracer is exposed. The reconstruction method is based on the maximum likelihood - expectation maximization algorithm. An experimental device, based on 36 detectors was realised for the visualization of water circulation in a vessel. A video monitoring allows to visualize the dye water tracer. Dye and radioactive tracers are injected simultaneously in a water flow circulating in the vessel. Reconstructed and video images are compared. Quantitative and qualitative analysis show that fluid flow visualization is feasible with a limited number of detectors. This method can be applied for system involving circulations of fluids. (author)

Small area detectors at the European XFEL

Science.gov (United States)

Turcato, M.; Gessler, P.; Hauf, S.; Kuster, M.; Meyer, M.; Nordgren, J.; Sztuk-Dambietz, J.; Youngman, C.

2014-05-01

The detectors to be used at the European XFEL have to deal with the unique time structure of the machine, delivering up to 2700 pulses, with a repetition rate of 4.5 MHz, ten times per second, the very high photon flux and the need to combine single-photon sensitivity and a large dynamic range. This represents a challenge not only for the large-area 2D imaging detectors but also for the smaller-area detectors and makes the use of standard commercial devices impossible. Dedicated solutions are therefore envisaged for small imaging- or strip-detectors. In this contribution the focus is put on two particular small-area detector solutions which are planned to be used at the European XFEL, a strip detector for hard X-rays (with energy 3 < E < 25 keV) and an imaging detector for soft X-rays (0.25 < E < 3 keV). Hard X-rays photon-beam diagnostics as well as hard X-ray absorption and emission spectroscopy at the European XFEL make use of strip detectors as detectors for beam spectrometers or as energy-dispersive detectors in combination with an energy-dispersive element. The European XFEL is establishing cooperation with the Paul Scherrer Institute in Villigen to develop a new version of the Gotthard detector best suited to the European XFEL needs. The use case and the required detector specifications are illustrated. Starting from the present detector version, the modifications planned to adapt it to the European XFEL running conditions are described. These include the capability of running at an increased rate and to provide a veto signal to the large 2D imaging detectors, in order to be able to remove non-interesting images already at early stages of the DAQ system. In another particular application, resonant inelastic X-ray scattering, a Micro-Channel Plate detector matched to a delay-line readout is foreseen to be used. In this case the European XFEL is aiming for a highly customized solution provided by the German company Surface Concept. The use case is described

Thermally emissive sensing materials for chemical spectroscopy analysis

Science.gov (United States)

Poole, Zsolt; Ohodnicki, Paul R.

2018-05-08

A sensor using thermally emissive materials for chemical spectroscopy analysis includes an emissive material, wherein the emissive material includes the thermally emissive materials which emit electromagnetic radiation, wherein the electromagnetic radiation is modified due to chemical composition in an environment; and a detector adapted to detect the electromagnetic radiation, wherein the electromagnetic radiation is indicative of the chemical interaction changes and hence chemical composition and/or chemical composition changes of the environment. The emissive material can be utilized with an optical fiber sensor, with the optical fiber sensor operating without the emissive material probed with a light source external to the material.

Light particle emission measurements in heavy ion reactions. Final report, June 1, 1981-May 31, 1984

International Nuclear Information System (INIS)

Petitt, G.A.

1984-01-01

Progress in instrumentation development reported includes improvements in the design of position sensitive neutron detectors, design of a thin-walled, spherical, aluminum target chamber, and use of thin silicon detectors to detect and identify evaporation residues from fusion reactions. The problem of the short lifetime of evaporation residue detectors is addressed by using a pair of large area, multi-wire proportional counters followed by a thin sheet of plastic scintillator. Neutron emission associated with fission has been studied, as well as nonequilibrium emission associated with inelastic products and evaporation residue. An experiment was performed to study neutron emission associated with fission and fission-like events in the case of the Er composite system. Other work in progress includes neutron emissions from the C + Gd and Ne + Nd reactions. 9 refs

Emission tomography system

International Nuclear Information System (INIS)

Phelps, M.E.; Hoffman, E.J.; Williams, C.W.; Burgiss, S.G.

1983-01-01

In the present invention a positron emission tomographic system is provided in which the random photon coincidence background is determined for the lines of sight along which the positron annihiliations are located. The circuitry is arranged so that this background may be subtracted almost simultaneously from the total photon coincidence measurement, or may be stored in a temporary memory for latter subtraction. In this system, an appropriate coincidence resolution time is selected and coincidences of photons detected at 180 degree opposed detectors within the time resolution are recorded as the overall coincidence count. This total count includes a source(true events) count plus a background(random coincidences) count. The background count is determined by measuring photons detected at these same sets of photon detectors and employing the same coincidence resolution period, where the signals from one set of detectors are passed through a delay longer in time than this resolution period

Examining the Combined Saturn and Ring Exosphere/Ionosphere using Cassini's Proximal orbits

Science.gov (United States)

Tucker, O. J.; Tseng, W. L.; Johnson, R. E.; Perry, M. E.

2017-12-01

Neutral molecules that are emitted from Saturn's exobase (i.e., H2) and the main rings (i.e., H2, O2, H) are a source of material for both the Saturn and ring ionospheres as well as Saturn's magnetosphere (Tseng et al., 2013 [PSS 85 164 - 167]). However, the density gradient of H2 produced from the main rings is very different than that produced by Saturn's exospheric flux due to its emission from the ring plane and distance from Saturn. Cassini measurements obtained during the proximal orbits can likely be used to identify contributions from Saturn and the rings. Here we present results obtained from Monte Carlo models of the Saturn and ring exosphere used to analyze INMS data of neutrals and ions measured along the trajectories of the Proximal orbits. Understanding the sources of neutrals and the concomitant ions can help provide insight about the dynamics occurring in the Saturn system.

Soft x-ray emission from gamma-ray bursts observed with ginga

International Nuclear Information System (INIS)

Yoshida, Atsumasa; Murakami, Toshio; Itoh, Masayuki

1989-01-01

The soft X-ray emission of gamma-ray bursts below 10 keV provides information about size, location, and emission mechanism. The Gamma-ray Burst Detector (GBD) on board Ginga, which consists of a proportional counter and a scintillation detector, covers an energy range down to 1.5 keV with 63 cm 2 effective area. In several of the observed gamma-ray bursts, the intensity of the soft X-ray emission showed a longer decay time of 50 to 100s after the higher energy gamma-ray emission had ended. Although we cannot rule out other models, such as bremsstrahlung and thermal cyclotron types, due to poor statistics, the soft X-ray spectra are consistent with a blackbody of 1 to 2 keV in the late phase of the gamma-ray bursts. This enables us to estimate the size of the blackbody responsible for the X-ray emission. (author)

PROXIMITY MANAGEMENT IN CRISIS CONDITIONS

Directory of Open Access Journals (Sweden)

Ion Dorin BUMBENECI

2010-01-01

Full Text Available The purpose of this study is to evaluate the level of assimilation for the terms "Proximity Management" and "Proximity Manager", both in the specialized literature and in practice. The study has two parts: the theoretical research of the two terms, and an evaluation of the use of Proximity management in 32 companies in Gorj, Romania. The object of the evaluation resides in 27 companies with less than 50 employees and 5 companies with more than 50 employees.

Impact of implementing the Meyer-Neldel behavior of carrier emission pre-factors in solar cell and optical detector modeling

Energy Technology Data Exchange (ETDEWEB)

Rubinelli, Francisco A.; Ramirez, Helena [INTEC, Conicet, Universidad Nacional del Litoral, Güemes 3450, 3000 Santa Fe (Argentina)

2015-03-14

The Meyer-Neldel behavior reported for the emission probabilities of electrons and holes was included in our code, replacing the gap state capture cross sections of the Shockley-Read-Hall formalisms with capture cross sections containing an exponential function of the trap energy depth. The Meyer-Neldel energies for electrons and holes are the slopes of these exponentials. Our results indicate that emission probabilities of neutral states no deeper than approximately 0.45 eV and 0.37 eV from the conduction and valence band edges, respectively, can show a Meyer-Neldel behavior only, while on the other hand, its implementation in deeper gap states makes the replication of experimental J-V curves of p-i-n solar cells and detectors impossible. The Meyer-Neldel behavior can be included in all neutral capture cross sections of acceptor-like tail states without affecting the J-V characteristics, while it cannot be included in all capture cross sections of neutral donor-like tail states and/or defect states without predicting device performances below the experimental figures, that become even lower when it is also included in charged capture cross sections. The implementation of the anti Meyer-Neldel behavior at tail states gives rise to slightly better and reasonable device performances.

Comparison of acrylic polymer adhesive tapes and silicone optical grease in light sharing detectors for positron emission tomography

Science.gov (United States)

Van Elburg, Devin J.; Noble, Scott D.; Hagey, Simone; Goertzen, Andrew L.

2018-03-01

Optical coupling is an important factor in detector design as it improves optical photon transmission by mitigating internal reflections at light-sharing boundaries. In this work we compare optical coupling materials, namely double-sided acrylic polymer tapes and silicone optical grease (SiG), in the context of positron emission tomography. Four double-sided tapes from 3 M of varying thicknesses (0.229 mm-1.016 mm) and adhesive materials (‘100MP’, ‘A100’, and ‘GPA’) were characterized with spectrophotometer measurements as well as photopeak amplitude and energy resolution measurements using lutetium-yttrium oxy-orthosilicate (LYSO) coupled to photomultiplier tubes (PMT) or silicon photomultipliers (SiPMs). Transmission spectra from the spectrophotometer showed over 80% transmission for all tapes at 420 nm and above, with 89.6% and 88.8% transmission for the 0.508 mm and 1.016 mm thick GPA tapes, respectively, at 420 nm. Measurements with single-pixel LYSO-PMT and 4  ×  4 array (one-to-one coupled) LYSO-SiPM setups determined that SiG had the greatest photopeak amplitude, with tapes showing 2.1%-14.8% reduction in photopeak amplitude with respect to SiG. Energy resolution changed by less than 4% on a relative basis between tapes and SiG with PMT measurements, however for the SiPM array measurements the energy resolution improved from 15.6%  ±  2.7% full-width at half-maximum to 11.4%  ±  1.2% for SiG and 1 mm GPA respectively. Data acquired with dual-layer offset LYSO arrays (light sharing detector designs) demonstrated that a detector coupled with 1 mm thick GPA tape produced equivalent detector flood histograms to those from a design coupled with SiG and a 1 mm thick glass lightguide. No significant degradation in photopeak amplitude and energy resolution was observed over five months of measurements, indicating the tapes maintain their coupling integrity over several months. Though minimal photopeak amplitude

Comparison of acrylic polymer adhesive tapes and silicone optical grease in light sharing detectors for positron emission tomography.

Science.gov (United States)

Van Elburg, Devin J; Noble, Scott D; Hagey, Simone; Goertzen, Andrew L

2018-02-26

Optical coupling is an important factor in detector design as it improves optical photon transmission by mitigating internal reflections at light-sharing boundaries. In this work we compare optical coupling materials, namely double-sided acrylic polymer tapes and silicone optical grease (SiG), in the context of positron emission tomography. Four double-sided tapes from 3 M of varying thicknesses (0.229 mm-1.016 mm) and adhesive materials ('100MP', 'A100', and 'GPA') were characterized with spectrophotometer measurements as well as photopeak amplitude and energy resolution measurements using lutetium-yttrium oxy-orthosilicate (LYSO) coupled to photomultiplier tubes (PMT) or silicon photomultipliers (SiPMs). Transmission spectra from the spectrophotometer showed over 80% transmission for all tapes at 420 nm and above, with 89.6% and 88.8% transmission for the 0.508 mm and 1.016 mm thick GPA tapes, respectively, at 420 nm. Measurements with single-pixel LYSO-PMT and 4  ×  4 array (one-to-one coupled) LYSO-SiPM setups determined that SiG had the greatest photopeak amplitude, with tapes showing 2.1%-14.8% reduction in photopeak amplitude with respect to SiG. Energy resolution changed by less than 4% on a relative basis between tapes and SiG with PMT measurements, however for the SiPM array measurements the energy resolution improved from 15.6%  ±  2.7% full-width at half-maximum to 11.4%  ±  1.2% for SiG and 1 mm GPA respectively. Data acquired with dual-layer offset LYSO arrays (light sharing detector designs) demonstrated that a detector coupled with 1 mm thick GPA tape produced equivalent detector flood histograms to those from a design coupled with SiG and a 1 mm thick glass lightguide. No significant degradation in photopeak amplitude and energy resolution was observed over five months of measurements, indicating the tapes maintain their coupling integrity over several months. Though minimal photopeak amplitude degradation

Results from the AMANDA high-energy neutrino detector

International Nuclear Information System (INIS)

Biron, A.

2001-01-01

This paper briefly summarizes the search for astronomical sources of high-energy neutrinos using the AMANDA-B10 detector. The complete data set from 1997 was analyzed. For E μ > 10 TeV, the detector exceeds 10,000 m 2 in effective area between declinations of 25 and 90 degrees. Neutrinos generated in the atmosphere by cosmic ray interactions were used to verify the overall sensitivity of the coincident events between the SPASE air shower array and the AMANDA detector. Preliminary flux limits from point source candidates are presented. For declinations larger than +45 degrees, our results compare favourably to existing limits for sources in the Southern sky. We also present the current status of the searches for high-energy neutrino emission from diffusely distributed sources, GRBs, and WIMPs from the center of the Earth

SAT's infrared equipment using second-generation detectors

Science.gov (United States)

Siriex, Michel B.

1995-09-01

In 1982 SAT proposed for the first time a second generation detector in the design of FLIRs for the TRIGAT program, since then different types of IR equipment have been developed on the basis of this technology: (1) An infra-red seeker for the MICA missile. (2) Three types of IRST: VAMPIR MB for naval applications, SIRENE for the Army and OSF for the Rafale aircraft. (3) Three thermal imagers: Condor 1 for the mast mounted sight equipping the long range anti tank system, Tiger installed on the sight of the medium range antitank system, and Condor 2 for the pilot sight of the TRIGAT French-German helicopter. Infra-red detectors are MCT IR-CCD focal plane arrays developed by SOFRADIR with the objective of the best standardization possible in spite of different configurations and specifications for each program. In this paper, we intend to present the main features of this technology for these programs and the advantages obtained by comparison with the first generation in terms of performance. Industrialization of these products is starting now, and a specific effort has been made to standardize the components, especially the driving and read out electronics. A set of ASICs has been developed to make compact detection modules including a detector in his dewar, a cooling machine, and a proximity electronic.

Capillary-discharge-based portable detector for chemical vapor monitoring

International Nuclear Information System (INIS)

Duan Yixiang; Su Yongxuan; Jin Zhe

2003-01-01

Conventional portable instruments for sensing chemical vapors have certain limitations for on-site use. In this article, we develop a genuinely portable detector that is sensitive, powerful, rugged, of simple design, and with very low power needs. Such a detector is based on a dry-cell battery-powered, capillary-discharge-based, microplasma source with optical emission detection. The microscale plasma source has very special features such as low thermal temperature and very low power needs. These features make it possible for the plasma source to be powered with a small dry-cell battery. A specially designed discharge chamber with minielectrodes can be configured to enhance the plasma stability and the system performance. A very small amount of inert gas can be used as sample carrier and plasma supporting gas. Inert gases possess high excitation potentials and produce high-energy metastable particles in the plasma. These particles provide sufficient energy to excite chemical species through Penning ionization and/or energy transfer from metastable species. A molecular emission spectrum can be collected with a palm-sized spectrometer through a collimated optical fiber. The spectrum can be displayed on a notebook computer. With this design and arrangement, the new detector provides high sensitivity for organic chemical species. The advantages and features of the newly developed detector include high sensitivity, simple structure, low cost, universal response, very low power consumption, compact volume with field portable capability, and ease of operation

Spontaneous Emission and Energy Transfer Rates Near a Coated Metallic Cylinder

OpenAIRE

BRADLEY, LOUISE

2014-01-01

PUBLISHED The spontaneous emission and energy transfer rates of quantum systems in proximity to a dielectrically coated metallic cylinder are investigated using a Green's tensor formalism. The excitation of surface plasmon modes can significantly modify these rates. The spontaneous emission and energy transfer rates are investigated as a function of the material and dimensions of the core and coating, as well as the emission wavelength of the donor. For the material of the core we consider...

Preoperative assessment of the cancellous bone mineral density of the proximal humerus using CT data

International Nuclear Information System (INIS)

Krappinger, Dietmar; Roth, Tobias; Gschwentner, Martin; Suckert, Armin; Blauth, Michael; Hengg, Clemens; Kralinger, Franz

2012-01-01

Osteoporotic fractures of the proximal humerus show an increasing incidence. Osteoporosis not only influences the fracture risk after low-energy trauma, but also affects the mechanical stability of internal fixation. Preoperative assessment of the local bone quality may be useful in the surgical treatment of patients sustaining these injuries. The aim of the present study was to present a method for the preoperative assessment of the local cancellous bone mineral density (BMD) of the proximal humerus using CT data. In the first part of the study, CT scans of 30 patients with unilateral fractures of the proximal humerus after low-energy trauma were used. The local BMD was assessed on the contralateral uninjured side. All 30 patients additionally underwent dual-emission X-ray absorptiometry (DXA) of the lumbar spine, proximal femur, and forearm of the side of the uninjured proximal humerus within 6 weeks after trauma. Three independent trauma surgeons performed measurements on the uninjured proximal humerus twice with a time interval of 4 weeks in order to assess the inter- and intraobserver reliability of the method. In the second part of the study, the local BMD of 507 patients with either proximal humerus fractures or chronic shoulder instability was assessed by a single trauma surgeon. In both parts, the average HU values in standardized ROIs of the humeral head were automatically calculated after correcting for HU values below the water equivalent. A linear calibration equation was computed for the calculation from HU to BMD using a calibration device (EFP). The intra- and interobserver reliability was high (ICC > 0.95). Correlation coefficients between the local BMD of the proximal humerus and other anatomical sites were between 0.35 (lumbar spine) and 0.64 (forearm). We found a high correlation between the local BMD and age. The BMD in the fracture group was significantly lower than in the instability group. These patients were significantly older and more

Preoperative assessment of the cancellous bone mineral density of the proximal humerus using CT data

Energy Technology Data Exchange (ETDEWEB)

Krappinger, Dietmar; Roth, Tobias; Gschwentner, Martin; Suckert, Armin; Blauth, Michael; Hengg, Clemens; Kralinger, Franz [Innsbruck Medical University, Department of Trauma Surgery and Sports Medicine, Innsbruck (Austria)

2012-03-15

Osteoporotic fractures of the proximal humerus show an increasing incidence. Osteoporosis not only influences the fracture risk after low-energy trauma, but also affects the mechanical stability of internal fixation. Preoperative assessment of the local bone quality may be useful in the surgical treatment of patients sustaining these injuries. The aim of the present study was to present a method for the preoperative assessment of the local cancellous bone mineral density (BMD) of the proximal humerus using CT data. In the first part of the study, CT scans of 30 patients with unilateral fractures of the proximal humerus after low-energy trauma were used. The local BMD was assessed on the contralateral uninjured side. All 30 patients additionally underwent dual-emission X-ray absorptiometry (DXA) of the lumbar spine, proximal femur, and forearm of the side of the uninjured proximal humerus within 6 weeks after trauma. Three independent trauma surgeons performed measurements on the uninjured proximal humerus twice with a time interval of 4 weeks in order to assess the inter- and intraobserver reliability of the method. In the second part of the study, the local BMD of 507 patients with either proximal humerus fractures or chronic shoulder instability was assessed by a single trauma surgeon. In both parts, the average HU values in standardized ROIs of the humeral head were automatically calculated after correcting for HU values below the water equivalent. A linear calibration equation was computed for the calculation from HU to BMD using a calibration device (EFP). The intra- and interobserver reliability was high (ICC > 0.95). Correlation coefficients between the local BMD of the proximal humerus and other anatomical sites were between 0.35 (lumbar spine) and 0.64 (forearm). We found a high correlation between the local BMD and age. The BMD in the fracture group was significantly lower than in the instability group. These patients were significantly older and more

Design of a volume-imaging positron emission tomograph

International Nuclear Information System (INIS)

Harrop, R.; Rogers, J.G.; Coombes, G.H.; Wilkinson, N.A.; Pate, B.D.; Morrison, K.S.; Stazyk, M.; Dykstra, C.J.; Barney, J.S.; Atkins, M.S.; Doherty, P.W.; Saylor, D.P.

1988-11-01

Progress is reported in several areas of design of a positron volume imaging tomograph. As a means of increasing the volume imaged and the detector packing fraction, a lens system of detector light coupling is considered. A prototype layered scintillator detector demonstrates improved spatial resolution due to a unique Compton rejection capability. The conceptual design of a new mechanism for measuring scattered radiation during emission scans has been tested by Monte Carlo simulation. The problem of how to use effectively the resulting sampled scattered radiation projections is presented and discussed

Proximal tubular hypertrophy and enlarged glomerular and proximal tubular urinary space in obese subjects with proteinuria.

Directory of Open Access Journals (Sweden)

Ana Tobar

Full Text Available BACKGROUND: Obesity is associated with glomerular hyperfiltration, increased proximal tubular sodium reabsorption, glomerular enlargement and renal hypertrophy. A single experimental study reported an increased glomerular urinary space in obese dogs. Whether proximal tubular volume is increased in obese subjects and whether their glomerular and tubular urinary spaces are enlarged is unknown. OBJECTIVE: To determine whether proximal tubules and glomerular and tubular urinary space are enlarged in obese subjects with proteinuria and glomerular hyperfiltration. METHODS: Kidney biopsies from 11 non-diabetic obese with proteinuria and 14 non-diabetic lean patients with a creatinine clearance above 50 ml/min and with mild or no interstitial fibrosis were retrospectively analyzed using morphometric methods. The cross-sectional area of the proximal tubular epithelium and lumen, the volume of the glomerular tuft and of Bowman's space and the nuclei number per tubular profile were estimated. RESULTS: Creatinine clearance was higher in the obese than in the lean group (P=0.03. Proteinuria was similarly increased in both groups. Compared to the lean group, the obese group displayed a 104% higher glomerular tuft volume (P=0.001, a 94% higher Bowman's space volume (P=0.003, a 33% higher cross-sectional area of the proximal tubular epithelium (P=0.02 and a 54% higher cross-sectional area of the proximal tubular lumen (P=0.01. The nuclei number per proximal tubular profile was similar in both groups, suggesting that the increase in tubular volume is due to hypertrophy and not to hyperplasia. CONCLUSIONS: Obesity-related glomerular hyperfiltration is associated with proximal tubular epithelial hypertrophy and increased glomerular and tubular urinary space volume in subjects with proteinuria. The expanded glomerular and urinary space is probably a direct consequence of glomerular hyperfiltration. These effects may be involved in the pathogenesis of obesity

Fractures of the proximal humerus

DEFF Research Database (Denmark)

Brorson, Stig

2013-01-01

Fractures of the proximal humerus have been diagnosed and managed since the earliest known surgical texts. For more than four millennia the preferred treatment was forceful traction, closed reduction, and immobilization with linen soaked in combinations of oil, honey, alum, wine, or cerate......, classification of proximal humeral fractures remains a challenge for the conduct, reporting, and interpretation of clinical trials. The evidence for the benefits of surgery in complex fractures of the proximal humerus is weak. In three systematic reviews I studied the outcome after locking plate osteosynthesis...

Metal-enhanced fluorescence exciplex emission.

Science.gov (United States)

Zhang, Yongxia; Mali, Buddha L; Geddes, Chris D

2012-01-01

In this letter, we report the first observation of metal-enhanced exciplex fluorescence, observed from anthracene in the presence of diethylaniline. Anthracene in the presence of diethylaniline in close proximity to Silver Island Films (SIFs) shows enhanced monomer and exciplex emission as compared to a non-silvered control sample containing no silver nanoparticles. Our findings suggest two complementary methods for the enhancement: (i) surface plasmons can radiate coupled monomer and exciplex fluorescence efficiently, and (ii) enhanced absorption (enhanced electric near-field) further facilitates enhanced emission. Our exciplex studies help us to further understand the complex photophysics of the metal-enhanced fluorescence technology. Copyright © 2011 Elsevier B.V. All rights reserved.

Towards time-of-flight PET with a semiconductor detector

Science.gov (United States)

Ariño-Estrada, Gerard; Mitchell, Gregory S.; Kwon, Sun Il; Du, Junwei; Kim, Hadong; Cirignano, Leonard J.; Shah, Kanai S.; Cherry, Simon R.

2018-02-01

The feasibility of using Cerenkov light, generated by energetic electrons following 511 keV photon interactions in the semiconductor TlBr, to obtain fast timing information for positron emission tomography (PET) was evaluated. Due to its high refractive index, TlBr is a relatively good Cerenkov radiator and with its wide bandgap, has good optical transparency across most of the visible spectrum. Coupling an SiPM photodetector to a slab of TlBr (TlBr-SiPM) yielded a coincidence timing resolution of 620 ps FWHM between the TlBr-SiPM detector and a LFS reference detector. This value improved to 430 ps FWHM by applying a high pulse amplitude cut based on the TlBr-SiPM and reference detector signal amplitudes. These results are the best ever achieved with a semiconductor PET detector and already approach the performance required for time-of-flight. As TlBr has higher stopping power and better energy resolution than the conventional scintillation detectors currently used in PET scanners, a hybrid TlBr-SiPM detector with fast timing capability becomes an interesting option for further development.

Computer-aided proximal caries diagnosis: correlation with clinical examination and histology

International Nuclear Information System (INIS)

Kang, Byung Cheol; Scheetz, James P.; Aarman, Allan G.

2002-01-01

To evaluate the performance of the LOGICON Caries Detector using RVG-4 and RVG-ui sensors, by comparing results of each detector to the results of clinical and histological examinations. Pairs of extracted teeth were radiographed, and a total of 57 proximal surfaces, which included both carious and non-carious situations, were analyzed. The RVG-4 produced 8-bit images, while the RVG-ui unit produced 12-bit images, which were taken in the high sensitivity mode. The images produced by the LOGICON were evaluated by a trained observer using both automated and manual caries detection software modes. Ground sections of the teeth established the actual absence or existence of caries. LOGICON-aided caries detection and depth discrimination of the RVG-4 and RVG-ui sensors were equally inconsistent irrespective of whether the LOGICON software was set to the automated or manual mode. Sensitivity ranged from 50% to 57% for caries penetration of the enamel-dentin junction. Care needs to be taken when using LOGICON in conjunction with RVG images as an adjunct for treatment planning dental caries. Even when applied by a trained observer, substantial discrepancies exist between the results of the LOGICON software-guided evalutation using RVG images and histologic examination.

A look at some systemic properties of self-bioluminescent emission

Science.gov (United States)

Creath, Katherine

2008-08-01

Self-bioluminescent emission (SBE) is a type of biological chemiluminescence where photons are emitted as part of chemical reactions occurring during metabolic processes. This emission is also known as biophoton emission, ultraweak photon emission and ultraweak bioluminescence. This paper outlines research over the past century on some systemic properties of SBE as measured with biological detectors, photomultiplier detectors and ultra-sensitive imaging arrays. There is an apparent consensus in the literature that emission in the deep blue and ultraviolet (150-450nm) is related to DNA / RNA processes while emission in the red and near infrared (600-1000nm) is related to mitochondria and oxidative metabolisms involving reactive oxygen species, singlet oxygen and free radicals in plant, animal and human cells along with chlorophyll fluorescent decay in plants. Additionally, there are trends showing that healthy, unstressed and uninjured samples have less emission than samples that are unhealthy, stressed or injured. Mechanisms producing this emission can be narrowed down by isolating the wavelength region of interest and waiting for short-term fluorescence to decay leaving the ultraweak long-term metabolic emission. Examples of imaging this emission in healthy versus unhealthy, stressed versus unstressed, and injured versus uninjured plant parts are shown. Further discussion poses questions still to be answered related to properties such as coherence, photon statistics, and methodological means of isolating mechanisms.

First image from a combined positron emission tomography and field-cycled MRI system.

Science.gov (United States)

Bindseil, Geron A; Gilbert, Kyle M; Scholl, Timothy J; Handler, William B; Chronik, Blaine A

2011-07-01

Combining positron emission tomography and MRI modalities typically requires using either conventional MRI with a MR-compatible positron emission tomography system or a modified MR system with conventional positron emission tomography. A feature of field-cycled MRI is that all magnetic fields can be turned off rapidly, enabling the use of conventional positron emission tomography detectors based on photomultiplier tubes. In this demonstration, two photomultiplier tube-based positron emission tomography detectors were integrated with a field-cycled MRI system (0.3 T/4 MHz) by placing them into a 9-cm axial gap. A positron emission tomography-MRI phantom consisting of a triangular arrangement of positron-emitting point sources embedded in an onion was imaged in a repeating interleaved sequence of ∼1 sec MRI then 1 sec positron emission tomography. The first multimodality images from the combined positron emission tomography and field-cycled MRI system show no additional artifacts due to interaction between the systems and demonstrate the potential of this approach to combining positron emission tomography and MRI. Copyright © 2010 Wiley-Liss, Inc.

Gas chromatography of organic microcontaminants using atomic emission and mass spectrometric detection combined in one instrument (GC-AED/MS)

NARCIS (Netherlands)

Mol, H.G.J.; Hankemeier, T.; Brinkman, U.A.T.

1999-01-01

This study describes the coupling of an atomic-emission detector and mass-spectrometric detector to a single gas chromatograph. Splitting of the column effluent enables simultaneous detection by atomic-emission detection (AED) and mass spectrometry (MS) and yields a powerful system for the target

Single-photon emission tomography and cerebral blood flow

International Nuclear Information System (INIS)

Celsis, P.; Chan, M.; Marc-Vergnes, J.P.; Sveinsdottir, E.; Goldman, T.G.; Henriksen, L.; Paulson, O.B.; Stokely, E.M.; Lassen, N.A.

1982-01-01

This paper illustrates the capabilities of single-photon emission tomography in imaging local cerebral blood flows in man. The results purport the conclusion that a fairly good improvement has been achieved when compared to stationary detectors and that single-photon emission tomography is a well-suited tool for studying cerebral hemodynamics, especially within the framework of clinical studies [fr

A silicon nanomembrane detector for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of large proteins.

Science.gov (United States)

Park, Jonghoo; Blick, Robert H

2013-10-11

We describe a MALDI-TOF ion detector based on freestanding silicon nanomembrane technology. The detector is tested in a commercial MALDI-TOF mass spectrometer with equimolar mixtures of proteins. The operating principle of the nanomembrane detector is based on phonon-assisted field emission from these silicon nanomembranes, in which impinging ion packets excite electrons in the nanomembrane to higher energy states. Thereby the electrons can overcome the vacuum barrier and escape from the surface of the nanomembrane via field emission. Ion detection is demonstrated of apomyoglobin (16,952 Da), aldolase (39,212 Da), bovine serum albumin (66,430 Da), and their equimolar mixtures. In addition to the three intact ions, a large number of fragment ions are also revealed by the silicon nanomembrane detector, which are not observable with conventional detectors.

A Silicon Nanomembrane Detector for Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS of Large Proteins

Directory of Open Access Journals (Sweden)

Jonghoo Park

2013-10-01

Full Text Available We describe a MALDI-TOF ion detector based on freestanding silicon nanomembrane technology. The detector is tested in a commercial MALDI-TOF mass spectrometer with equimolar mixtures of proteins. The operating principle of the nanomembrane detector is based on phonon-assisted field emission from these silicon nanomembranes, in which impinging ion packets excite electrons in the nanomembrane to higher energy states. Thereby the electrons can overcome the vacuum barrier and escape from the surface of the nanomembrane via field emission. Ion detection is demonstrated of apomyoglobin (16,952 Da, aldolase (39,212 Da, bovine serum albumin (66,430 Da, and their equimolar mixtures. In addition to the three intact ions, a large number of fragment ions are also revealed by the silicon nanomembrane detector, which are not observable with conventional detectors.

Charge collection in Si detectors irradiated in situ at superfluid helium temperature

Science.gov (United States)

Verbitskaya, Elena; Eremin, Vladimir; Zabrodskii, Andrei; Dehning, Bernd; Kurfürst, Christoph; Sapinski, Mariusz; Bartosik, Marcin R.; Egorov, Nicolai; Härkönen, Jaakko

2015-10-01

Silicon and diamond detectors operated in a superfluid helium bath are currently being considered for the upgrade of the LHC beam loss monitoring system. The detectors would be installed in immediate proximity of the superconducting coils of the triplet magnets. We present here the results of the in situ irradiation test for silicon detectors using 23 GeV protons while keeping the detectors at a temperature of 1.9 K. Red laser (630 nm) Transient Current Technique and DC current measurements were used to study the pulse response and collected charge for silicon detectors irradiated to a maximum radiation fluence of 1×1016 p/cm2. The dependence between collected charge and irradiation fluence was parameterized using the Hecht equation and assumption of a uniform electric field distribution. The collected charge was found to degrade with particle fluence for both bias polarities. We observed that the main factor responsible for this degradation was related to trapping of holes on the donor-type radiation-induced defects. In contrast to expectations, along with formation of donors, acceptor-type defects (electron traps) are introduced into the silicon bulk. This suggests that the current models describing charge collection in irradiated silicon detectors require an extension for taking into account trapping at low temperatures with a contribution of shallow levels. New in situ irradiation tests are needed and planned now to extend statistics of the results and gain a deeper insight into the physics of low temperature detector operation in harsh radiation environment.

Initial outcome and efficacy of S3 proximal humerus locking plate in the treatment of proximal humerus fractures

International Nuclear Information System (INIS)

Zhang Zhiming; Zhu Xuesong; Bao Zhaohua; Yang Huilin

2012-01-01

Objective: to explore the initial outcome and efficacy of S 3 proximal humerus locking plate in the treatment of proximal humerus fractures. Methods: Twenty-two patients with proximal humerus fracture were treated with the S 3 proximal humerus locking plate. Most of the fractures were complex, two-part (n=4), three-part (n=11) and four-part (n=7) fractures according to the Neer classification of the proximal humerus fractures. Results: All patients were followed up for 3∼15 months. There were no complications related to the implant including loosening or breakage of the plate. Good and excellent results were documented in 17 patients fair results in 4 patients according the Neer scores of shoulder. Conclusion: New design concepts of S 3 proximal humerus plate provide the subchondral support and the internal fixation support. With the addition of the proper exercise of the shoulder joint, the outcomes would be satisfied. (authors)

Preliminary study on leadership proximity

Directory of Open Access Journals (Sweden)

Ghinea Valentina Mihaela

2017-07-01

Full Text Available In general, it is agreed that effective leadership requires a certain degree of proximity, either physical or mental, which enables leaders to maintain control over their followers and communicate their vision. Although we agree with the leadership proximity principles which states that leaders are able to efficiently serve only those people with whom they interact frequently, in this article we focus instead on the disadvantages of being too close and the way in which close proximity can actually hurt the effectiveness of leadership. The main effects that we discuss regard the way in which proximity and familiarity allow followers to see the weaknesses and faults of the leader much more easily and thus diminish the leader’s heroic aura, and the emotional bias that results from a leader being too familiar with his followers which will impede the process of rational decision making. As a result, we argue that there exists a functional proximity which allows the leader the necessary space in which to perform effective identity work and to hide the backstage aspects of leadership, while also allowing him an emotional buffer zone which will enable him to maintain the ability to see clearly and make rational decisions.

Cadmium-Zinc-Telluride photon detector for epithermal neutron spectroscopy--pulse height response characterisation

International Nuclear Information System (INIS)

Tardocchi, M.; Pietropaolo, A.; Andreani, C.; Bracco, A.; D'Angelo, A.; Gorini, G.; Imberti, S.; Senesi, R.; Rhodes, N.J.; Schooneveld, E.M.

2004-01-01

The Resonance Detector Spectrometer was recently revised for neutron spectroscopic studies in the eV energy region. In this technique one makes use of a photon detector to record the gamma emission from analyser foils used as neutron-gamma converters. The pulse-height response of a Cadmium-Zinc-Telluride photon detector to neutron capture emission from 238 U and 197 Au analyser foils was characterised in the neutron energy range 1-200 eV. The experiment was performed on the VESUVIO spectrometer at the ISIS neutron-pulsed source. A biparametric data acquisition, specifically developed for these measurements, allowed the simultaneous measurements of both the neutron time of flight and γ pulse-height spectra. Through the analysis of the γ pulse-height spectra the main components of the signal associated with resonant and non-resonant neutron absorption were identified. It was also shown that, in principle, energy discrimination can be used to improve the signal to background ratio of the neutron time-of-flight measurement

A new generation of small pixel pitch/SWaP cooled infrared detectors

Science.gov (United States)

Espuno, L.; Pacaud, O.; Reibel, Y.; Rubaldo, L.; Kerlain, A.; Péré-Laperne, N.; Dariel, A.; Roumegoux, J.; Brunner, A.; Kessler, A.; Gravrand, O.; Castelein, P.

2015-10-01

Following clear technological trends, the cooled IR detectors market is now in demand for smaller, more efficient and higher performance products. This demand pushes products developments towards constant innovations on detectors, read-out circuits, proximity electronics boards, and coolers. Sofradir was first to show a 10μm focal plane array (FPA) at DSS 2012, and announced the DAPHNIS 10μm product line back in 2014. This pixel pitch is a key enabler for infrared detectors with increased resolution. Sofradir recently achieved outstanding products demonstrations at this pixel pitch, which clearly demonstrate the benefits of adopting 10μm pixel pitch focal plane array-based detectors. Both HD and XGA Daphnis 10μm products also benefit from a global video datapath efficiency improvement by transitioning to digital video interfaces. Moreover, innovative smart pixels functionalities drastically increase product versatility. In addition to this strong push towards a higher pixels density, Sofradir acknowledges the need for smaller and lower power cooled infrared detector. Together with straightforward system interfaces and better overall performances, latest technological advances on SWAP-C (Size, Weight, Power and Cost) Sofradir products enable the advent of a new generation of high performance portable and agile systems (handheld thermal imagers, unmanned aerial vehicles, light gimbals etc...). This paper focuses on those features and performances that can make an actual difference in the field.

Basic principles of 18F-fluoro-deoxyglucose positron emission tomography

International Nuclear Information System (INIS)

Standke, R.

2002-01-01

Positron emission tomography uses photons to receive regional information about dynamic, physiologic, and biochemical processes in the living body. A positron decay is measured indirectly by the simultaneous registration of both gamma rays created by the annihilation. The event is counted, if two directly opposite located detectors register gamma rays in coincidence. Unfortunately the detectors of a positron emission tomography system do not register only true coincident events. There are also scattered and random coincidences. Different types of positron tomographs are presented and scintillation crystals, which are in use for positron emission tomography are discussed. The 2D- and 3D-acquisition methods are described as well as preprocessing methods, such as correction for attenuation, scatter and dead time. For quantification the relative parameter standard uptake value (SUV) is explained. Finally hybrid systems, such as combined positron emission tomography/computed tomography scanners and the use of computed tomography data for attenuation correction are introduced. (author)

Using Poisson-regularized inversion of Bremsstrahlung emission to extract full electron energy distribution functions from x-ray pulse-height detector data

Science.gov (United States)

Swanson, C.; Jandovitz, P.; Cohen, S. A.

2018-02-01

We measured Electron Energy Distribution Functions (EEDFs) from below 200 eV to over 8 keV and spanning five orders-of-magnitude in intensity, produced in a low-power, RF-heated, tandem mirror discharge in the PFRC-II apparatus. The EEDF was obtained from the x-ray energy distribution function (XEDF) using a novel Poisson-regularized spectrum inversion algorithm applied to pulse-height spectra that included both Bremsstrahlung and line emissions. The XEDF was measured using a specially calibrated Amptek Silicon Drift Detector (SDD) pulse-height system with 125 eV FWHM at 5.9 keV. The algorithm is found to out-perform current leading x-ray inversion algorithms when the error due to counting statistics is high.

ProxImaL: efficient image optimization using proximal algorithms

KAUST Repository

Heide, Felix; Diamond, Steven; Nieß ner, Matthias; Ragan-Kelley, Jonathan; Heidrich, Wolfgang; Wetzstein, Gordon

2016-01-01

domain-specific language and compiler for image optimization problems that makes it easy to experiment with different problem formulations and algorithm choices. The language uses proximal operators as the fundamental building blocks of a variety

Secondary electrons detectors for beam tracking: micromegas and wire chamber

International Nuclear Information System (INIS)

Pancin, J; Chaminade, T; Drouart, A; Kebbiri, M; Riallot, M; Fernandez, B; Naqvi, F

2009-01-01

SPIRAL2 or FAIR will be able to deliver beams of radioactive isotopes of low energy (less than 10 MeV/n). The emittance of these new beams will impose the use of beam tracking detectors to reconstruct the exact impact position of the nuclei on the experimental target. However, due to their thickness, the classical detectors will generate a lot of energy and angular straggling. A possible alternative is the SED principle (Secondary Electron Detector). It consists of an emissive foil placed in beam and a detector for the secondary electrons ejected by the passing of the nuclei through the foil. An R and D program has been initiated at CEA Saclay to study the possibility to use low pressure gaseous detectors as SED for beam tracking. Some SED have been already used on the VAMOS spectrometer at GANIL since 2004. We have constructed new detectors on this model to measure their performances in time and spatial resolution, and counting rate. Other detector types are also under study. For the first time, a test with different micromegas detectors at 4 Torr has been realized. A comparison on the time resolution has been performed between wire chamber and micromegas at very low pressure. The use of micromegas could be promising to improve the counting rate capability and the robustness of beam tracking detectors.

A novel, SiPM-array-based, monolithic scintillator detector for PET

International Nuclear Information System (INIS)

Schaart, Dennis R; Dam, Herman T van; Seifert, Stefan; Beekman, Freek J; Vinke, Ruud; Dendooven, Peter; Loehner, Herbert

2009-01-01

Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e.g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as avalanche photodiodes. Here we present a novel detector design with DOI correction, in which a position-sensitive SiPM array is used to read out a monolithic scintillator. Initial characterization of a prototype detector consisting of a 4 x 4 SiPM array coupled to either the front or back surface of a 13.2 mm x 13.2 mm x 10 mm LYSO:Ce 3+ crystal shows that front-side readout results in significantly better performance than conventional back-side readout. Spatial resolutions 2 detector, equals 960 ps FWHM.

Performance of A Compact Multi-crystal High-purity Germanium Detector Array for Measuring Coincident Gamma-ray Emissions

Energy Technology Data Exchange (ETDEWEB)

Howard, Chris [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Daigle, Stephen [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Buckner, Matt [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Erikson, Luke E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Runkle, Robert C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Stave, Sean C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Champagne, Art [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Cooper, Andrew [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Downen, Lori [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Glasgow, Brian D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kelly, Keegan [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States); Sallaska, Anne [Univ. of North Carolina, Chapel Hill, NC (United States); Triangle Univ. Nuclear Lab., Durham, NC (United States)

2015-02-18

The Multi-sensor Airborne Radiation Survey (MARS) detector is a 14-crystal array of high-purity germanium (HPGe) detectors housed in a single cryostat. The array was used to measure the astrophysical S-factor for the ¹⁴N(p,γ)¹⁵O* reaction for several transition energies at an effective center of mass energy of 163 keV. Owing to the segmented nature of the MARS detector, the effect of gamma-ray summing was greatly reduced in comparison to past experiments which utilized large, single-crystal detectors. The new S-factor values agree within the uncertainties with the past measurements. Details of the analysis and detector performance will be presented.

Performance of a compact multi-crystal high-purity germanium detector array for measuring coincident gamma-ray emissions

Energy Technology Data Exchange (ETDEWEB)

Howard, Chris; Daigle, Stephen; Buckner, Matt [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Erikson, Luke E.; Runkle, Robert C. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Stave, Sean C., E-mail: Sean.Stave@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Champagne, Arthur E.; Cooper, Andrew; Downen, Lori [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States); Glasgow, Brian D. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Kelly, Keegan; Sallaska, Anne [University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, NC 27708 (United States)

2015-05-21

The Multi-sensor Airborne Radiation Survey (MARS) detector is a 14-crystal array of high-purity germanium (HPGe) detectors housed in a single cryostat. The array was used to measure the astrophysical S-factor for the {sup 14}N(p,γ){sup 15}O{sup ⁎} reaction for several transition energies at an effective center-of-mass energy of 163 keV. Owing to the granular nature of the MARS detector, the effect of gamma-ray summing was greatly reduced in comparison to past experiments which utilized large, single-crystal detectors. The new S-factor values agree within their uncertainties with the past measurements. Details of the analysis and detector performance are presented.

Improved positron emission tomography camera

International Nuclear Information System (INIS)

Mullani, N.A.

1986-01-01

A positron emission tomography camera having a plurality of rings of detectors positioned side-by-side or offset by one-half of the detector cross section around a patient area to detect radiation therefrom, and a plurality of scintillation crystals positioned relative to the photomultiplier tubes whereby each tube is responsive to more than one crystal. Each alternate crystal in the ring may be offset by one-half or less of the thickness of the crystal such that the staggered crystals are seen by more than one photomultiplier tube. This sharing of crystals and photomultiplier tubes allows identification of the staggered crystal and the use of smaller detectors shared by larger photomultiplier tubes thereby requiring less photomultiplier tubes, creating more scanning slices, providing better data sampling, and reducing the cost of the camera. (author)

PROXIMAL DISABILITY AND SPINAL DEFORMITY INDEX IN PATIENTS WITH PROXIMAL FEMUR FRACTURES

Directory of Open Access Journals (Sweden)

Sylvio Mistro Neto

2015-12-01

Full Text Available Objective : To evaluate the quality of life related to the spine in patients with proximal femoral fractures. Methods : Study conducted in a tertiary public hospital in patients with proximal femoral fractures caused by low-energy trauma, through the Oswestry Disability Index questionnaire to asses complaints related to the spine at the time of life prior to the femoral fracture. The thoracic and lumbar spine of patients were also evaluated applying the radiographic index described by Gennant (Spinal Deformity Index, which assesses the number and severity of fractures. Results : Seventeen subjects completed the study. All had some degree of vertebral fracture. Patients were classified in the categories of severe and very severe disability in the questionnaire about quality of life. It was found that the higher SDI, the better the quality of life. Conclusion : There is a strong association of disability related to the spine in patients with proximal femoral fracture, and this complaint must be systematically evaluated in patients with appendicular fracture.

Fast infrared detectors for beam diagnostics with synchrotron radiation

International Nuclear Information System (INIS)

Bocci, A.; Marcelli, A.; Pace, E.; Drago, A.; Piccinini, M.; Cestelli Guidi, M.; De Sio, A.; Sali, D.; Morini, P.; Piotrowski, J.

2007-01-01

Beam diagnostic is a fundamental constituent of any particle accelerators either dedicated to high-energy physics or to synchrotron radiation experiments. All storage rings emit radiations. Actually they are high brilliant sources of radiation: the synchrotron radiation emission covers from the infrared range to the X-ray domain with a pulsed structure depending on the temporal characteristics of the stored beam. The time structure of the emitted radiation is extremely useful as a tool to perform time-resolved experiments. However, this radiation can be also used for beam diagnostic to determine the beam stability and to measure the dimensions of the e - or e + beam. Because of the temporal structure of the synchrotron radiation to perform diagnostic, we need very fast detectors. Indeed, the detectors required for the diagnostics of the stored particle bunches at third generation synchrotron radiation sources and FEL need response times in the sub-ns and even ps range. To resolve the bunch length and detect bunch instabilities, X-ray and visible photon detectors may be used achieving response times of a few picoseconds. Recently, photon uncooled infrared devices optimized for the mid-IR range realized with HgCdTe semiconductors allowed to obtain sub-nanosecond response times. These devices can be used for fast detection of intense IRSR sources and for beam diagnostic. We present here preliminary experimental data of the pulsed synchrotron radiation emission of DAΦNE, the electron positron collider of the LNF laboratory of the INFN, performed with new uncooled IR detectors with a time resolution of a few hundreds of picoseconds

Constraining Microwave Emission from Extensive Air Showers via the MIDAS Experiment

Science.gov (United States)

Richardson, Matthew; Privitera, Paolo

2017-01-01

Ultra high energy cosmic rays (UHECRs) are accelerated by the most energetic processes in the universe. Upon entering Earth’s atmosphere they produce particle showers known as extensive air showers (EASs). Observatories like the Pierre Auger Observatory sample the particles and light produced by the EASs through large particle detector arrays or nitrogen fluorescence detectors to ascertain the fundamental properties of UHECRs. The large sample of high quality data provided by the Pierre Auger Observatory can be attributed to the hybrid technique which utilizes the two aforementioned techniques simultaneously; however, the limitation of only being able to observe nitrogen fluorescence from EASs on clear moonless nights yields a limited 10% duty cycle for the hybrid technique. One proposal for providing high quality data at increased statistics is the observation of isotropic microwave emission from EASs, as such emission would be observed with a 100% duty cycle. Measurements of microwave emission from laboratory air plasmas conducted by Gorham et al. (2008) produced promising results indicating that the microwave emission should be observable using inexpensive detectors. The Microwave Detection of Air Showers (MIDAS) experiment was built at the University of Chicago to characterize the isotropic microwave emission from EASs and has collected 359 days of observational data at the location of the Pierre Auger experiment. We have performed a time coincidence analysis between this data and data from Pierre Auger and we report a null result. This result places stringent limits on microwave emission from EASs and demonstrates that the laboratory measurements of Gorham et al. (2008) are not applicable to EASs, thus diminishing the feasibility of using isotropic microwave emission to detect EASs.

Detector simulation needs for detector designers

International Nuclear Information System (INIS)

Hanson, G.G.

1987-11-01

Computer simulation of the components of SSC detectors and of the complete detectors will be very important for the designs of the detectors. The ratio of events from interesting physics to events from background processes is very low, so detailed understanding of detector response to the backgrounds is needed. Any large detector for the SSC will be very complex and expensive and every effort must be made to design detectors which will have excellent performance and will not have to undergo major rebuilding. Some areas in which computer simulation is particularly needed are pattern recognition in tracking detectors and development of shower simulation code which can be trusted as an aid in the design and optimization of calorimeters, including their electron identification performance. Existing codes require too much computer time to be practical and need to be compared with test beam data at energies of several hundred GeV. Computer simulation of the processing of the data, including electronics response to the signals from the detector components, processing of the data by microprocessors on the detector, the trigger, and data acquisition will be required. In this report we discuss the detector simulation needs for detector designers

ProxImaL: efficient image optimization using proximal algorithms

KAUST Repository

Heide, Felix

2016-07-11

Computational photography systems are becoming increasingly diverse, while computational resources-for example on mobile platforms-are rapidly increasing. As diverse as these camera systems may be, slightly different variants of the underlying image processing tasks, such as demosaicking, deconvolution, denoising, inpainting, image fusion, and alignment, are shared between all of these systems. Formal optimization methods have recently been demonstrated to achieve state-of-the-art quality for many of these applications. Unfortunately, different combinations of natural image priors and optimization algorithms may be optimal for different problems, and implementing and testing each combination is currently a time-consuming and error-prone process. ProxImaL is a domain-specific language and compiler for image optimization problems that makes it easy to experiment with different problem formulations and algorithm choices. The language uses proximal operators as the fundamental building blocks of a variety of linear and nonlinear image formation models and cost functions, advanced image priors, and noise models. The compiler intelligently chooses the best way to translate a problem formulation and choice of optimization algorithm into an efficient solver implementation. In applications to the image processing pipeline, deconvolution in the presence of Poisson-distributed shot noise, and burst denoising, we show that a few lines of ProxImaL code can generate highly efficient solvers that achieve state-of-the-art results. We also show applications to the nonlinear and nonconvex problem of phase retrieval.

The ALICE-HMPID Detector Control System: Its evolution towards an expert and adaptive system

Science.gov (United States)

De Cataldo, G.; Franco, A.; Pastore, C.; Sgura, I.; Volpe, G.

2011-05-01

The High Momentum Particle IDentification (HMPID) detector is a proximity focusing Ring Imaging Cherenkov (RICH) for charged hadron identification. The HMPID is based on liquid C 6F 14 as the radiator medium and on a 10 m 2 CsI coated, pad segmented photocathode of MWPCs for UV Cherenkov photon detection. To ensure full remote control, the HMPID is equipped with a detector control system (DCS) responding to industrial standards for robustness and reliability. It has been implemented using PVSS as Slow Control And Data Acquisition (SCADA) environment, Programmable Logic Controller as control devices and Finite State Machines for modular and automatic command execution. In the perspective of reducing human presence at the experiment site, this paper focuses on DCS evolution towards an expert and adaptive control system, providing, respectively, automatic error recovery and stable detector performance. HAL9000, the first prototype of the HMPID expert system, is then presented. Finally an analysis of the possible application of the adaptive features is provided.

The ALICE-HMPID Detector Control System: Its evolution towards an expert and adaptive system

International Nuclear Information System (INIS)

De Cataldo, G.; Franco, A.; Pastore, C.; Sgura, I.; Volpe, G.

2011-01-01

The High Momentum Particle IDentification (HMPID) detector is a proximity focusing Ring Imaging Cherenkov (RICH) for charged hadron identification. The HMPID is based on liquid C 6 F 14 as the radiator medium and on a 10 m 2 CsI coated, pad segmented photocathode of MWPCs for UV Cherenkov photon detection. To ensure full remote control, the HMPID is equipped with a detector control system (DCS) responding to industrial standards for robustness and reliability. It has been implemented using PVSS as Slow Control And Data Acquisition (SCADA) environment, Programmable Logic Controller as control devices and Finite State Machines for modular and automatic command execution. In the perspective of reducing human presence at the experiment site, this paper focuses on DCS evolution towards an expert and adaptive control system, providing, respectively, automatic error recovery and stable detector performance. HAL9000, the first prototype of the HMPID expert system, is then presented. Finally an analysis of the possible application of the adaptive features is provided.

Cryogenic gamma detectors enable direct detection of 236U and minor actinides for non-destructive assay

International Nuclear Information System (INIS)

Miguel Velazquez; Jonathan Dreyer; Drury, O.B.; Friedrich, Stephan; Saleem Salaymeh

2016-01-01

We demonstrate the utility of a superconducting transition edge sensor (TES) γ-ray detector with high energy resolution and low Compton background for nondestructive assay (NDA) of a uranium sample from reprocessed nuclear fuel. We show that TES γ-detectors can separate low-energy actinide γ-emissions from the background and nearby lines, even from minor isotopes whose signals are often obscured in NDA with conventional Ge detectors. Superconducting γ-detectors may therefore bridge the gap between high-accuracy destructive assay (DA) and easier-to-use NDA. (author)

Charge collection performance of a segmented planar high-purity germanium detector

Energy Technology Data Exchange (ETDEWEB)

Cooper, R.J. [Department of Physics, The University of Liverpool, Oliver Lodge Laboratory, Liverpool Merseyside L69 7ZE (United Kingdom)], E-mail: R.Cooper@liverpool.ac.uk; Boston, A.J.; Boston, H.C.; Cresswell, J.R.; Grint, A.N.; Harkness, L.J.; Nolan, P.J.; Oxley, D.C.; Scraggs, D.P. [Department of Physics, The University of Liverpool, Oliver Lodge Laboratory, Liverpool Merseyside L69 7ZE (United Kingdom); Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Warrington, Cheshire WA4 4AD (United Kingdom); Dobson, J. [Rosemere Cancer Centre, Royal Preston Hospital, Preston PR2 9HT (United Kingdom)

2008-10-01

High-precision scans of a segmented planar high-purity germanium (HPGe) detector have been performed with a range of finely collimated gamma ray beams allowing the response as a function of gamma ray interaction position to be quantified. This has allowed the development of parametric pulse shape analysis (PSA) techniques and algorithms for the correction of imperfections in performance. In this paper we report on the performance of this detector, designed for use in a positron emission tomography (PET) development system.

Thermal noise in mid-infrared broadband upconversion detectors

DEFF Research Database (Denmark)

Barh, Ajanta; Tidemand-Lichtenberg, Peter; Pedersen, Christian

2018-01-01

Low noise detection with state-of-the-art mid-infrared (MIR) detectors (e.g., PbS, PbSe, InSb, HgCdTe) is a primary challenge owing to the intrinsic thermal background radiation of the low bandgap detector material itself. However, researchers have employed frequency upconversion based detectors...... of the noise-equivalent power of an UCD system. In this article, we rigorously analyze the optical power generated by frequency upconversion of the intrinsic black-body radiation in the nonlinear material itself due to the crystals residual emissivity, i.e. absorption. The thermal radiation is particularly...... prominent at the optical absorption edge of the nonlinear material even at room temperature. We consider a conventional periodically poled lithium niobate (PPLN) based MIR-UCD for the investigation. The UCD is designed to cover a broad spectral range, overlapping with the entire absorption edge of the PPLN...

Convergence analysis of a relaxed EM algorithm with uses in emission tomography

International Nuclear Information System (INIS)

Iusem, A.N.

1989-01-01

This work describes the Position Emission tomography technique this technique consists of introducing in the organism a radioactive substance and determining its concentration in each part of the body by measuring its emission in a detectors ring. (A.C.A.S.)

Performance comparison of scintillators for alpha particle detectors

Energy Technology Data Exchange (ETDEWEB)

Morishita, Yuki [Graduate School of Medicine, Nagoya University, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya, Aichi 461-8673 (Japan); Japan Atomic Energy Agency, Muramatsu 4-33, Tokai-mura, Ibaraki 319-1194 (Japan); Yamamoto, Seiichi [Graduate School of Medicine, Nagoya University, 1-1-20 Daiko-Minami, Higashi-ku, Nagoya, Aichi 461-8673 (Japan); Izaki, Kenji [Japan Atomic Energy Agency, Muramatsu 4-33, Tokai-mura, Ibaraki 319-1194 (Japan); Kaneko, Junichi H.; Toui, Kohei; Tsubota, Youichi; Higuchi, Mikio [Graduate School of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan)

2014-11-11

Scintillation detectors for alpha particles are often used in nuclear fuel facilities. Alpha particle detectors have also become important in the research field of radionuclide therapy using alpha emitters. ZnS(Ag) is the most often used scintillator for alpha particle detectors because its light output is high. However, the energy resolution of ZnS(Ag)-based scintillation detectors is poor because they are not transparent. A new ceramic sample, namely the cerium doped Gd{sub 2}Si{sub 2}O{sub 7} (GPS) scintillator, has been tested as alpha particle detector and its performances have been compared to that one of three different scintillating materials: ZnS(Ag), GAGG and a standard plastic scintillator. The different scintillating materials have been coupled to two different photodetectors, namely a photomultiplier tube (PMT) and a Silicon Photo-multiplier (Si-PM): the performances of each detection system have been compared. Promising results as far as the energy resolution performances (10% with PMT and 14% with Si-PM) have been obtained in the case of GPS and GAGG samples. Considering the quantum efficiencies of the photodetectors under test and their relation to the emission wavelength of the different scintillators, the best results were achieved coupling the GPS with the PMT and the GAGG with the Si-PM.

Proximal Probes Facility

Data.gov (United States)

Federal Laboratory Consortium — The Proximal Probes Facility consists of laboratories for microscopy, spectroscopy, and probing of nanostructured materials and their functional properties. At the...

Positron emission tomography now and in the future

International Nuclear Information System (INIS)

Vaalburg, W.

1987-01-01

A survey is given of positron emission tomography used in nuclear medicine. The production of positron emitting radionuclides is discussed. The development of positron detectors is described. The application of positron emission tomography in cardiology, oncology and neurology is treated. The authors conclude that PET is a unique method to examine metabolic processes, although the method is still in its infancy. 7 refs.; 1 table

Iterative image reconstruction for positron emission tomography based on a detector response function estimated from point source measurements

International Nuclear Information System (INIS)

Tohme, Michel S; Qi Jinyi

2009-01-01

The accuracy of the system model in an iterative reconstruction algorithm greatly affects the quality of reconstructed positron emission tomography (PET) images. For efficient computation in reconstruction, the system model in PET can be factored into a product of a geometric projection matrix and sinogram blurring matrix, where the former is often computed based on analytical calculation, and the latter is estimated using Monte Carlo simulations. Direct measurement of a sinogram blurring matrix is difficult in practice because of the requirement of a collimated source. In this work, we propose a method to estimate the 2D blurring kernels from uncollimated point source measurements. Since the resulting sinogram blurring matrix stems from actual measurements, it can take into account the physical effects in the photon detection process that are difficult or impossible to model in a Monte Carlo (MC) simulation, and hence provide a more accurate system model. Another advantage of the proposed method over MC simulation is that it can easily be applied to data that have undergone a transformation to reduce the data size (e.g., Fourier rebinning). Point source measurements were acquired with high count statistics in a relatively fine grid inside the microPET II scanner using a high-precision 2D motion stage. A monotonically convergent iterative algorithm has been derived to estimate the detector blurring matrix from the point source measurements. The algorithm takes advantage of the rotational symmetry of the PET scanner and explicitly models the detector block structure. The resulting sinogram blurring matrix is incorporated into a maximum a posteriori (MAP) image reconstruction algorithm. The proposed method has been validated using a 3 x 3 line phantom, an ultra-micro resolution phantom and a 22 Na point source superimposed on a warm background. The results of the proposed method show improvements in both resolution and contrast ratio when compared with the MAP

Dual germanium detector system for the routine assay of low level transuranics in soil

International Nuclear Information System (INIS)

Crowell, J.M.

1980-01-01

As an outgrowth of previous on soil radioassay, we have developed an automated assay system for determining the transuranic radionuclide content of soils, with particular interest in Pu. The system utilizes two commercial planar intrinsic germanium detectors in opposition. The large area of the detectors (2100 mm 2 ) and the thinness of the detector crystals (7 mm) permit sensitive analysis of the L x ray emission region of the transuranics (13 to 21 keV). With counting times of 5 hours, we obtain detection limits of 241 Am

Transverse and Longitudinal proximity effect

Science.gov (United States)

Jalan, Pryianka; Chand, Hum; Srianand, Raghunathan

2018-04-01

With close pairs (˜1.5arcmin) of quasars (QSOs), absorption in the spectra of a background quasar in the vicinity of a foreground quasar can be used to study the environment of the latter quasar at kpc-Mpc scales. For this we used a sample of 205 quasar pairs from the Sloan Digital Sky-Survey Data Release 12 (SDSS DR12) in the redshift range of 2.5 to 3.5 by studying their H I Ly-α absorption. We study the environment of QSOs both in the longitudinal as well as in the transverse direction by carrying out a statistical comparison of the Ly-α absorption lines in the quasar vicinity to that of the absorption lines caused by the inter-galactic medium (IGM). This comparison was done with IGM, matched in absorption redshift and signal-to-noise ratio (SNR) to that of the proximity region. In contrast to the measurements along the line-of-sight, the regions transverse to the quasars exhibit enhanced H I Ly-α absorption. This discrepancy can either be interpreted as due to an anisotropic emission from the quasars or as a consequence of their finite lifetime.

Neighborhoods and manageable proximity

Directory of Open Access Journals (Sweden)

Stavros Stavrides

2011-08-01

Full Text Available The theatricality of urban encounters is above all a theatricality of distances which allow for the encounter. The absolute “strangeness” of the crowd (Simmel 1997: 74 expressed, in its purest form, in the absolute proximity of a crowded subway train, does not generally allow for any movements of approach, but only for nervous hostile reactions and submissive hypnotic gestures. Neither forced intersections in the course of pedestrians or vehicles, nor the instantaneous crossing of distances by the technology of live broadcasting and remote control give birth to places of encounter. In the forced proximity of the metropolitan crowd which haunted the city of the 19th and 20th century, as well as in the forced proximity of the tele-presence which haunts the dystopic prospect of the future “omnipolis” (Virilio 1997: 74, the necessary distance, which is the stage of an encounter between different instances of otherness, is dissipated.

Digital contrast subtraction radiography for proximal caries diagnosis

International Nuclear Information System (INIS)

Kang, Byung Cheol; Yoon, Suk Ja

2002-01-01

To determine whether subtraction images utilizing contrast media can improve the diagnostic performance of proximal caries diagnosis compared to conventional periapical radiographic images. Thirty-six teeth with 57 proximal surfaces were radiographied using a size no.2 RVG-ui sensor (Trophy Radiology, Marne-la-Vallee, France). The teeth immersed in water-soluble contrast media and subtraction images were taken. Each tooth was then sectioned for histologic examination. The digital radiographic images and subtraction images were examined and interpreted by three dentists for proximal caries. The results of the proximal caries diagnosis were then verified with the results of the histologic examination. The proximal caries sensitivity using digital subtraction radiography was significantly higher than simply examining a single digital radiograph. The sensitivity of the proximal dentinal carious lesion when analyzed with the subtraction radiograph and the radiograph together was higher than with the subtraction radiograph or the radiograph alone. The use of subtraction radiography with contrast media may be useful for detecting proximal dentinal carious lesions.

Using convolutional neural networks to estimate time-of-flight from PET detector waveforms

Science.gov (United States)

Berg, Eric; Cherry, Simon R.

2018-01-01

Although there have been impressive strides in detector development for time-of-flight positron emission tomography, most detectors still make use of simple signal processing methods to extract the time-of-flight information from the detector signals. In most cases, the timing pick-off for each waveform is computed using leading edge discrimination or constant fraction discrimination, as these were historically easily implemented with analog pulse processing electronics. However, now with the availability of fast waveform digitizers, there is opportunity to make use of more of the timing information contained in the coincident detector waveforms with advanced signal processing techniques. Here we describe the application of deep convolutional neural networks (CNNs), a type of machine learning, to estimate time-of-flight directly from the pair of digitized detector waveforms for a coincident event. One of the key features of this approach is the simplicity in obtaining ground-truth-labeled data needed to train the CNN: the true time-of-flight is determined from the difference in path length between the positron emission and each of the coincident detectors, which can be easily controlled experimentally. The experimental setup used here made use of two photomultiplier tube-based scintillation detectors, and a point source, stepped in 5 mm increments over a 15 cm range between the two detectors. The detector waveforms were digitized at 10 GS s-1 using a bench-top oscilloscope. The results shown here demonstrate that CNN-based time-of-flight estimation improves timing resolution by 20% compared to leading edge discrimination (231 ps versus 185 ps), and 23% compared to constant fraction discrimination (242 ps versus 185 ps). By comparing several different CNN architectures, we also showed that CNN depth (number of convolutional and fully connected layers) had the largest impact on timing resolution, while the exact network parameters, such as convolutional

Competition between peripheral and central emission in incomplete fusion reactions

International Nuclear Information System (INIS)

Tricoire, H.

1984-01-01

In the frame of a classical model we show that the emission of fast particles in incomplete fusion reactions may occur either from a PEP emission which happens preferentially at low angular momenta or from an inertial emission with a maximum of the cross section located near the critical angular momentum for complete fusion. The competition of these mechanisms depends crucialy of the interaction between the particle to be emitted and the target nucleus. Numerical calculations are performed with various particle target potentials. Using a proximity potential, one gets results in good agreement with experimental data

Calculus Rules for V-Proximal Subdifferentials in Smooth Banach Spaces

Directory of Open Access Journals (Sweden)

Messaoud Bounkhel

2016-01-01

Full Text Available In 2010, Bounkhel et al. introduced new proximal concepts (analytic proximal subdifferential, geometric proximal subdifferential, and proximal normal cone in reflexive smooth Banach spaces. They proved, in p-uniformly convex and q-uniformly smooth Banach spaces, the density theorem for the new concepts of proximal subdifferential and various important properties for both proximal subdifferential concepts and the proximal normal cone concept. In this paper, we establish calculus rules (fuzzy sum rule and chain rule for both proximal subdifferentials and we prove the Bishop-Phelps theorem for the proximal normal cone. The limiting concept for both proximal subdifferentials and for the proximal normal cone is defined and studied. We prove that both limiting constructions coincide with the Mordukhovich constructions under some assumptions on the space. Applications to nonconvex minimisation problems and nonconvex variational inequalities are established.

The upgraded Pixel Detector of the ATLAS Experiment for Run-II at the Large Hadron Collider

CERN Document Server

AUTHOR|(INSPIRE)INSPIRE-00407702

2016-01-01

The Pixel Detector of the ATLAS experiment has shown excellent performance during the whole Run-1 of the LHC. Taking advantage of the detector development period 2013 – 2014, the detector was extracted from the experiment and brought to surface to equip it with new service panels and to repair modules furthermore this helped with the installation of the Insertable B-Layer (IBL), fourth layer of pixel, installed in between the existing Pixel Detector and a new beam-pipe at a radius of 3.3 cm. To cope with the high radiation and increased pixel occupancy due to the proximity to the interaction point, two different silicon sensor technologies (planar and 3D) have been used. A new readout chip has been designed with CMOS 130nm technology with larger area, smaller pixel size and faster readout capability. Dedicated design features in combination with a new composite material were considered and used in order to reduce the material budget of the support structure while keeping the optimal thermo-mechanical perfor...

ATLAS inner detector: the Run 1 to Run 2 transition, and first experience from Run 2

CERN Document Server

Dobos, Daniel; The ATLAS collaboration

2015-01-01

The ATLAS experiment is equipped with a tracking system, the Inner Detector, built using different technologies, silicon planar sensors (pixel and micro-strip) and gaseous drift- tubes, all embedded in a 2T solenoidal magnetic field. For the LHC Run II, the system has been upgraded; taking advantage of the long showdown, the Pixel Detector was extracted from the experiment and brought to surface, to equip it with new service quarter panels, to repair modules and to ease installation of the Insertable B-Layer (IBL), a fourth layer of pixel detectors, installed in May 2014 between the existing Pixel Detector and a new smaller radius beam-pipe at a radius of 3.3 cm from the beam axis. To cope with the high radiation and pixel occupancy due to the proximity to the interaction point and the increase of Luminosity that LHC will face in Run-2, a new read-out chip within CMOS 130nm and two different silicon sensor pixel technologies (planar and 3D) have been developed. SCT and TRT systems consolidation was also carri...

A prototype station for ARIANNA: A detector for cosmic neutrinos

International Nuclear Information System (INIS)

Gerhardt, Lisa; Klein, Spencer; Stezelberger, Thorsten; Barwick, Steve; Dookayka, Kamlesh; Hanson, Jordan; Nichol, Ryan

2010-01-01

The Antarctic Ross Ice Shelf Antenna Neutrino Array (ARIANNA) is a proposed detector for ultra-high energy astrophysical neutrinos. It will detect coherent radio Cherenkov emission from the particle showers produced by neutrinos with energies above about 10 17 eV. ARIANNA will be built on the Ross Ice Shelf just off the coast of Antarctica, where it will eventually cover about 900 km 2 in surface area. There, the ice-water interface below the shelf reflects radio waves, giving ARIANNA sensitivity to downward-going neutrinos and improving its sensitivity to horizontally incident neutrinos. ARIANNA detector stations each will contain 4-8 antennas, which search for pulses of 50 MHz to 1 GHz radio emission from neutrino interactions. We describe a prototype station for ARIANNA, which was deployed in Moore's Bay on the Ross Ice Shelf in December 2009, discuss the design and deployment, and present some initial figures on performance. The ice shelf thickness was measured to be 572±6 m at the deployment site.

Current status and requirements for position-sensitive detectors in medicine

CERN Document Server

Speller, R

2002-01-01

This review considers the current status of detector developments for medical imaging using ionising radiation. This field is divided into two major areas; the use of X-rays for transmission imaging and the use of radioactive tracers in emission imaging (nuclear medicine). Until recently, most detector developments were for applications in nuclear medicine. However, in the past 5 years new developments in large area, X-ray-sensitive detectors have meant that both application domains are equally served. In X-ray imaging, work in CT and mammography are chosen as examples of sensor developments. Photodiode arrays in multi-slice spiral CT acquisitions are described and for mammography the use of amorphous silicon flat panel arrays is considered. The latter is an excellent example where new detector developments have required a re-think of traditional imaging methods. In gamma-ray imaging the recent developments in small area, task-specific cameras are described. Their limitations and current proposals to overcome...

Development of Large Area CsI Photocathodes for the ALICE/HMPID RICH Detector

CERN Document Server

Hoedlmoser, H; Schyns, E

2005-01-01

The work carried out within the framework of this PhD deals with the measurement of the photoelectric properties of large area thin film Cesium Iodide (CsI) photocathodes (PCs) which are to be used as a photon converter in a proximity focusing RICH detector for High Momentum Particle Identification (HMPID) in the ALICE experiment at the LHC. The objective was to commission a VUV-scanner setup for in-situ measurements of the photoelectric response of the CsI PCs immediately after the thin film coating process and the use of this system to investigate the properties of these photon detectors. Prior to this work and prior to the finalization of the ALICE/HMPID detector design, R&D work investigating the properties of CsI PCs had been performed at CERN and at other laboratories in order to determine possible substrates and optimized thin film coating procedures. These R&D studies were usually carried out with small samples on different substrates and with various procedures with sometimes ambiguous result...

Super-Relaxed ( -Proximal Point Algorithms, Relaxed ( -Proximal Point Algorithms, Linear Convergence Analysis, and Nonlinear Variational Inclusions

Directory of Open Access Journals (Sweden)

Agarwal RaviP

2009-01-01

Full Text Available We glance at recent advances to the general theory of maximal (set-valued monotone mappings and their role demonstrated to examine the convex programming and closely related field of nonlinear variational inequalities. We focus mostly on applications of the super-relaxed ( -proximal point algorithm to the context of solving a class of nonlinear variational inclusion problems, based on the notion of maximal ( -monotonicity. Investigations highlighted in this communication are greatly influenced by the celebrated work of Rockafellar (1976, while others have played a significant part as well in generalizing the proximal point algorithm considered by Rockafellar (1976 to the case of the relaxed proximal point algorithm by Eckstein and Bertsekas (1992. Even for the linear convergence analysis for the overrelaxed (or super-relaxed ( -proximal point algorithm, the fundamental model for Rockafellar's case does the job. Furthermore, we attempt to explore possibilities of generalizing the Yosida regularization/approximation in light of maximal ( -monotonicity, and then applying to first-order evolution equations/inclusions.

Numerical investigation of steady-state thermal behavior of an infrared detector cryo chamber

Directory of Open Access Journals (Sweden)

Singhal Mayank

2017-01-01

Full Text Available An infrared (IR detector is simply a transducer of radiant energy, converting radiant energy into a measurable form. Since radiation does not rely on visible light, it offers the possibility of seeing in the dark or through obscured conditions, by detecting the IR energy emitted by objects. One of the prime applications of IR detector systems for military use is in target acquisition and tracking of projectile systems. The IR detectors also have great potential in commercial market. Typically, IR detectors perform best when cooled to cryogenic temperatures in the range of nearly 120 K. However, the necessity to operate in such cryogenic regimes makes the application of IR detectors extremely complex. Further, prior to proceeding on to a full blown transient thermal analysis it is worthwhile to perform a steady-state numerical analysis for ascertaining the effect of variation in viz., material, gas conduction coefficient, h, emissivity, ε, on the temperature profile along the cryo chamber length. This would enable understanding the interaction between the cryo chamber and its environment. Hence, the present work focuses on the development of steady-state numerical models for thermal analysis of IR cryo chamber using MATLAB. The numerical results show that gas conduction coefficient has marked influence on the temperature profile of the cryo chamber whereas the emissivity has a weak effect. The experimental validation of numerical results has also been presented.

Homotopic non-local regularized reconstruction from sparse positron emission tomography measurements

International Nuclear Information System (INIS)

Wong, Alexander; Liu, Chenyi; Wang, Xiao Yu; Fieguth, Paul; Bie, Hongxia

2015-01-01

Positron emission tomography scanners collect measurements of a patient’s in vivo radiotracer distribution. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide (tracer), which is introduced into the body on a biologically active molecule, and the tomograms must be reconstructed from projections. The reconstruction of tomograms from the acquired PET data is an inverse problem that requires regularization. The use of tightly packed discrete detector rings, although improves signal-to-noise ratio, are often associated with high costs of positron emission tomography systems. Thus a sparse reconstruction, which would be capable of overcoming the noise effect while allowing for a reduced number of detectors, would have a great deal to offer. In this study, we introduce and investigate the potential of a homotopic non-local regularization reconstruction framework for effectively reconstructing positron emission tomograms from such sparse measurements. Results obtained using the proposed approach are compared with traditional filtered back-projection as well as expectation maximization reconstruction with total variation regularization. A new reconstruction method was developed for the purpose of improving the quality of positron emission tomography reconstruction from sparse measurements. We illustrate that promising reconstruction performance can be achieved for the proposed approach even at low sampling fractions, which allows for the use of significantly fewer detectors and have the potential to reduce scanner costs

Monte Carlo based performance assessment of different animal PET architectures using pixellated CZT detectors

International Nuclear Information System (INIS)

Visvikis, D.; Lefevre, T.; Lamare, F.; Kontaxakis, G.; Santos, A.; Darambara, D.

2006-01-01

The majority of present position emission tomography (PET) animal systems are based on the coupling of high-density scintillators and light detectors. A disadvantage of these detector configurations is the compromise between image resolution, sensitivity and energy resolution. In addition, current combined imaging devices are based on simply placing back-to-back and in axial alignment different apparatus without any significant level of software or hardware integration. The use of semiconductor CdZnTe (CZT) detectors is a promising alternative to scintillators for gamma-ray imaging systems. At the same time CZT detectors have the potential properties necessary for the construction of a truly integrated imaging device (PET/SPECT/CT). The aims of this study was to assess the performance of different small animal PET scanner architectures based on CZT pixellated detectors and compare their performance with that of state of the art existing PET animal scanners. Different scanner architectures were modelled using GATE (Geant4 Application for Tomographic Emission). Particular scanner design characteristics included an overall cylindrical scanner format of 8 and 24 cm in axial and transaxial field of view, respectively, and a temporal coincidence window of 8 ns. Different individual detector modules were investigated, considering pixel pitch down to 0.625 mm and detector thickness from 1 to 5 mm. Modified NEMA NU2-2001 protocols were used in order to simulate performance based on mouse, rat and monkey imaging conditions. These protocols allowed us to directly compare the performance of the proposed geometries with the latest generation of current small animal systems. Results attained demonstrate the potential for higher NECR with CZT based scanners in comparison to scintillator based animal systems

Energy resolution of a four-layer depth of interaction detector block for small animal PET

International Nuclear Information System (INIS)

Tsuda, Tomoaki; Kawai, Hideyuki; Orita, Narimichi; Murayama, Hideo; Yoshida, Eiji; Inadama, Naoko; Yamaya, Taiga; Omura, Tomohide

2004-01-01

We are now planning to develop a positron emission tomograph dedicated to small animals such as rats and mice which meets the demand for higher sensitivity. We proposed a new depth of interaction (DOI) detector arrangement to obtain DOI information by using a four-layer detector with all the same crystal elements. In this DOI detector, we control the behavior of scintillation photons by inserting the reflectors between crystal elements so that the DOI information of four layers can be extracted from one two-dimensional (2D) position histogram made by Anger-type calculation. In this work, we evaluate the energy resolution of this four-layer DOI detector. (author)

Characteristics of Fabricated SiC Neutron Detectors for Neutron Flux Monitoring

Energy Technology Data Exchange (ETDEWEB)

Kim, Han Soo; Ha, Jang Ho; Park, Se Hwan; Lee, Kyu Hong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Cheol Ho [Hanyang University, Seoul (Korea, Republic of)

2011-05-15

An SPND (Self-powered Neutron Detector) is commonly used for neutron detection in NPP (Nuclear Power Plant) by virtue of un-reactivity for gamma-rays. But it has a drawback, which is that it cannot detect neutrons in real time due to beta emissions (about > 48 s) after reactions between neutrons and {sup 103}Rh in an SPND. And Generation IV reactors such as MSR (Molten-salt reactor), SFR (Sodium-cooled fast reactor), and GFR (Gas-cooled fast reactor) are designed to compact size and integration type. For GEN IV reactor, neutron monitor also must be compact-sized to apply such reactor easily and much more reliable. The wide band-gap semiconductors such as SiC, AlN, and diamond make them an attractive alternative in applications in harsh environments by virtue of the lower operating voltage, faster charge-collection times compared with gas-filled detectors, and compact size.1) In this study, two PIN-type SiC semiconductor neutron detectors, which are for fast neutron detection by elastic and inelastic scattering SiC atoms and for thermal neutron detection by charged particle emissions of 6LiF reaction, were designed and fabricated for NPP-related applications. Preliminary tests such as I-V and alpha response were performed and neutron responses at ENF in HANARO research reactor were also addressed. The application feasibility of the fabricated SiC neutron detector as an in-core neutron monitor was discussed

Biomechanical evaluation of straight antegrade nailing in proximal humeral fractures: the rationale of the "proximal anchoring point".

Science.gov (United States)

Euler, Simon A; Petri, Maximilian; Venderley, Melanie B; Dornan, Grant J; Schmoelz, Werner; Turnbull, Travis Lee; Plecko, Michael; Kralinger, Franz S; Millett, Peter J

2017-09-01

Varus failure is one of the most common failure modes following surgical treatment of proximal humeral fractures. Straight antegrade nails (SAN) theoretically provide increased stability by anchoring to the densest zone of the proximal humerus (subchondral zone) with the end of the nail. The aim of this study was to biomechanically investigate the characteristics of this "proximal anchoring point" (PAP). We hypothesized that the PAP would improve stability compared to the same construct without the PAP. Straight antegrade humeral nailing was performed in 20 matched pairs of human cadaveric humeri for a simulated unstable two-part fracture. Biomechanical testing, with stepwise increasing cyclic axial loading (50-N increments each 100 cycles) at an angle of 20° abduction revealed significantly higher median loads to failure for SAN constructs with the PAP (median, 450 N; range, 200-1.000 N) compared to those without the PAP (median, 325 N; range, 100-500 N; p = 0.009). SAN constructs with press-fit proximal extensions (endcaps) showed similar median loads to failure (median, 400 N; range, 200-650 N), when compared to the undersized, commercially available SAN endcaps (median, 450 N; range, 200-600 N; p = 0.240). The PAP provided significantly increased stability in SAN constructs compared to the same setup without this additional proximal anchoring point. Varus-displacing forces to the humeral head were superiorly reduced in this setting. This study provides biomechanical evidence for the "proximal anchoring point's" rationale. Straight antegrade humeral nailing may be beneficial for patients undergoing surgical treatment for unstable proximal humeral fractures to decrease secondary varus displacement and thus potentially reduce revision rates.

Neutron detector for detecting rare events of spontaneous fission

International Nuclear Information System (INIS)

Ter-Akop'yan, G.M.; Popeko, A.G.; Sokol, E.A.; Chelnokov, L.P.; Smirnov, V.I.; Gorshkov, V.A.

1981-01-01

The neutron detector for registering rare events of spontaneous fission by detecting multiple neutron emission is described. The detector represents a block of plexiglas of 550 mm diameter and 700 mm height in the centre of which there is a through 160 mm diameter channel for the sample under investigation. The detector comprises 56 3 He filled counters (up to 7 atm pressure) with 1% CO 2 addition. The counters have a 500 mm length and a 32 mm diameter. The sampling of fission events is realized by an electron system which allows determining the number of detected neutrons, numbers of operated counters, signal amplitude and time for fission event detecting. A block diagram of a neutron detector electron system is presented and its operation principle is considered. For protection against cosmic radiation the detector is surronded by a system of plastic scintillators and placed behind the concrete shield of 6 m thickness. The results of measurements of background radiation are given. It has been found that the background radiation of single neutron constitutes about 150 counts per hour, the detecting efficiency of single neutron equals 0.483 +- 0.005, for a 10l detector sensitive volume. By means of the detector described the parameters of multiplicity distribution of prompt neutrons for 256 Fm spontaneous fission are measured. The average multiplicity equals 3.59+-0.06 the dispersion being 2.30+-0.65

Evaluation of pulmonary nodules and lung cancer with one-inch crystal gamma coincidence positron emission tomography/CT versus dedicated positron emission tomography/CT

International Nuclear Information System (INIS)

Moodie, K.; Lau, E.; Hicks, R. J.; Cherk, M. H.; Turlakow, A.; Skinner, S.; Kelly, M. J.; Kalff, V.

2009-01-01

Full text: Dedicated positron emission tomography (PET)/CT scanners using BGO and related detectors (d-PET) have become standard imaging instruments in many malignancies. Hybrid gamma camera systems using Nal detectors in coincidence mode (g-PET) have been compared to d-PET but reported usefulness has been variable when gamma cameras with half-inch to three-fourth-inch thick crystals have been used without CT. Our aim was to compare g-PET with a 1-in.-thick crystal and inbuilt CT for lesion localization and attenuation correction (g-PET/CT) and d-PET/CT in patients presenting with potential and confirmed lung malignancies. One hour after 18F-fluorodeoxyglucose (FDG), patients underwent BGO d-PET/CT from jaw to proximal thigh. This was followed by one to two bed position g-PET/CT 194 + 27 min after FDG. Each study pair was independently analysed with concurrent CT. d-PET/CT was interpreted by a radiologist experienced in both PET and CT, and g-PET/CT by consensus reading of an experienced PET physician and an experienced CT radiologist, A TNM score was assigned and studies were then unblinded and compared. Fifty-seven patients underwent 58 scan pairs over 2 years. Eighty-nine percent concordance was shown between g-PET/CT and d-PET/CT for the assessment of I intrapulmonary lesions, with 100% concordance for intrapulmonary lesions I >10 mm (36 of 36). Eighty-eight per cent (51 of 58) concordance was shown between g-PET/CTand d-PET/CTforTNM staging. Coincidence imaging usingan optimized dual-head 1-in.-thick crystal gamma camera with inbuilt CT compares reasonably well with dedicated PET/CT for evaluation of indeterminate pulmonary lesions and staging of pulmonary malignancies and may be of some] value when d-PET/CT is not readily available.

High-spatial resolution and high-spectral resolution detector for use in the measurement of solar flare hard x rays

International Nuclear Information System (INIS)

Desai, U.D.; Orwig, L.E.

1988-01-01

In the areas of high spatial resolution, the evaluation of a hard X-ray detector with 65 micron spatial resolution for operation in the energy range from 30 to 400 keV is proposed. The basic detector is a thick large-area scintillator faceplate, composed of a matrix of high-density scintillating glass fibers, attached to a proximity type image intensifier tube with a resistive-anode digital readout system. Such a detector, combined with a coded-aperture mask, would be ideal for use as a modest-sized hard X-ray imaging instrument up to X-ray energies as high as several hundred keV. As an integral part of this study it was also proposed that several techniques be critically evaluated for X-ray image coding which could be used with this detector. In the area of high spectral resolution, it is proposed to evaluate two different types of detectors for use as X-ray spectrometers for solar flares: planar silicon detectors and high-purity germanium detectors (HPGe). Instruments utilizing these high-spatial-resolution detectors for hard X-ray imaging measurements from 30 to 400 keV and high-spectral-resolution detectors for measurements over a similar energy range would be ideally suited for making crucial solar flare observations during the upcoming maximum in the solar cycle

arXiv Performance of a full scale prototype detector at the BR2 reactor for the SoLid experiment

CERN Document Server

Abreu, Y.; Arnold, L.; Ban, G.; Beaumont, W.; Bongrand, M.; Boursette, D.; Castle, B.C.; Clark, K.; Coupé, B.; Cussans, D.; De Roeck, A.; D'Hondt, J.; Durand, D.; Fallot, M.; Ghys, L.; Giot, L.; Guillon, B.; Ihantola, S.; Janssen, X.; Kalcheva, S.; Kalousis, L.N.; Koonen, E.; Labare, M.; Lehaut, G.; Manzanillas, L.; Mermans, J.; Michiels, I.; Moortgat, C.; Newbold, D.; Park, J.; Pestel, V.; Petridis, K.; Piñera, I.; Pommery, G.; Popescu, L.; Pronost, G.; Rademacker, J.; Ryckbosch, D.; Ryder, N.; Saunders, D.; Schune, M.-H.; Simard, L.; Vacheret, A.; Van Dyck, S.; Van Mulders, P.; van Remortel, N.; Vercaemer, S.; Verstraeten, M.; Weber, A.; Yermia, F.

2018-05-03

The SoLid collaboration has developed a new detector technology to detect electron anti-neutrinos at close proximity to the Belgian BR2 reactor at surface level. A 288 kg prototype detector was deployed in 2015 and collected data during the operational period of the reactor and during reactor shut-down. Dedicated calibration campaigns were also performed with gamma and neutron sources. This paper describes the construction of the prototype detector with a high control on its proton content and the stability of its operation over a period of several months after deployment at the BR2 reactor site. All detector cells provide sufficient light yields to achieve a target energy resolution of better than 20%/√E(MeV). The capability of the detector to track muons is exploited to equalize the light response of a large number of channels to a precision of 3% and to demonstrate the stability of the energy scale over time. Particle identification based on pulse-shape discrimination is demonstrated with calibration so...

Optical scattering lengths in large liquid-scintillator neutrino detectors

Energy Technology Data Exchange (ETDEWEB)

Wurm, M.; Feilitzsch, F. von; Goeger-Neff, M.; Hofmann, M.; Lewke, T.; Meindl, Q.; Moellenberg, R.; Oberauer, L.; Potzel, W.; Tippmann, M.; Todor, S.; Winter, J. [Physik-Department E15, Technische Universitaet Muenchen, James-Franck-Str., D-85748 Garching (Germany); Lachenmaier, T.; Traunsteiner, C. [Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, D-85748 Garching (Germany); Undagoitia, T. Marrodan [Physik-Department E15, Technische Universitaet Muenchen, James-Franck-Str., D-85748 Garching (Germany); Physik-Institut, Universitaet Zuerich, Winterthurstr. 189, CH-8057 Zuerich (Switzerland)

2010-05-15

For liquid-scintillator neutrino detectors of kiloton scale, the transparency of the organic solvent is of central importance. The present paper reports on laboratory measurements of the optical scattering lengths of the organic solvents phenylxylylethane, linear alkylbenzene (LAB), and dodecane, which are under discussion for next-generation experiments such as SNO+ (Sudbury Neutrino Observatory), HanoHano, or LENA (Low Energy Neutrino Astronomy). Results comprise the wavelength range of 415-440 nm. The contributions from Rayleigh and Mie scattering as well as from absorption/re-emission processes are discussed. Based on the present results, LAB seems to be the preferred solvent for a large-volume detector.

Optical scattering lengths in large liquid-scintillator neutrino detectors.

Science.gov (United States)

Wurm, M; von Feilitzsch, F; Göger-Neff, M; Hofmann, M; Lachenmaier, T; Lewke, T; Marrodán Undagoitia, T; Meindl, Q; Möllenberg, R; Oberauer, L; Potzel, W; Tippmann, M; Todor, S; Traunsteiner, C; Winter, J

2010-05-01

For liquid-scintillator neutrino detectors of kiloton scale, the transparency of the organic solvent is of central importance. The present paper reports on laboratory measurements of the optical scattering lengths of the organic solvents phenylxylylethane, linear alkylbenzene (LAB), and dodecane, which are under discussion for next-generation experiments such as SNO+ (Sudbury Neutrino Observatory), HanoHano, or LENA (Low Energy Neutrino Astronomy). Results comprise the wavelength range of 415-440 nm. The contributions from Rayleigh and Mie scattering as well as from absorption/re-emission processes are discussed. Based on the present results, LAB seems to be the preferred solvent for a large-volume detector.

The performance of silicon detectors for the SiliPET project: A small animal PET scanner based on stacks of silicon detectors

International Nuclear Information System (INIS)

Auricchio, Natalia; Domenico, Giovanni di; Zavattini, Guido; Milano, Luciano; Malaguti, Roberto

2011-01-01

We propose a new scanner for small animal Positron Emission Tomography (PET) based on stacks of double sided silicon detectors. Each stack is made of 40 planar detectors with dimension 60x60x1 mm 3 and 128 orthogonal strips on both sides to read the two coordinates of interaction, the third being the detector number in the stack. Multiple interactions in a stack are discarded by an exclusive OR applied between each detector plane of a stack. In this way we achieve a precise determination of the interaction point of the two 511 keV photons. The reduced dimensions of the scanner also improve the solid angle coverage resulting in a high sensitivity. Preliminary results were obtained with MEGA prototype tracker (11 double sided Si detector layers), divided into two stacks 2 cm apart made of, respectively, 5 and 6 prototype layers, placing a small spherical 22 Na source in different positions. We report on the results, spatial resolution, imaging and timing performances obtained with double sided silicon detectors, manufactured by ITC-FBK, having an active area of 3x3 cm 2 , thickness of 1 mm and a strip pitch of 500μm. Two different strip widths of 300 and 200μm equipped with 64 orthogonal p and n strips on opposite sides were read out with the VATAGP2.5 ASIC, a 128-channel 'general purpose' charge sensitive amplifier.

Evaluation of Position Resolution for a Prototype Whole-Body PET Detector Based on Suppressing Backgrounds by Compton Scattering

Science.gov (United States)

Fujihara, Kento; Emoto, Yusaku; Ito, Hiroshi; Kaneko, Naomi; Kaneko, Hideyuki; Kawai, Hideyuki; Kobayashi, Atsushi; Mizuno, Takahiro

2018-01-01

Existing PET (Positron Emission Tomography) systems make clear images in demonstration (measuring small PET reagent in pure water), however images in real diagnosis become unclear. The authors suspected that this problem was caused by Compton scattering in a detector. When PET systems observe plural photomultiplier tube outputs, an original emission point is regarded as centroid of the outputs. However, even if plural emission in Compton scattering occur, these systems calculate original point in the same way as single emission. Therefore, the authors considered that rejecting Compton scattering events makes PET systems much better, and made prototype counter. Main components of the prototype counter are plate-like high-growth-rate (HGR) La-GPS scintillators and wavelength shifting fibers (WLSF). HGR crystals grow 10 times as fast as a mono-crystal (a normal mono-crystal grows at 2 - 3 mm an hour). Thus, it includes microbubble and its transparency get worth. Consequently, HGR crystals usually are not used in radiation measuring instruments. However, this time they are used on the purpose. Because of their low transparency, scintillation lights come out right above and right under of emission position. Therefore, Compton scattering events is rejected easily. The prototype detector has an effective area of 300 by 300 square mm. The detector consists of 24 layers. One layer consists of HGR La-GPS scintillator of 1 mm thickness. Top and bottom surface of scintillator were covered by dual sheets of WLSF with a diameter of 0.2 mm. Sheets of WLSF on top and bottom of the scintillator make a right angle with each other, and measure X- and Y-components. Z-component is measured by difference of WLSF outputs between top and bottom. If plural layers output signals, this counter regards the event as Compton scattering event, and reject the event. Even if only a layer output signals, the event is rejected when number output signals from WLSF is more than 1.5 times of single

Multi-parameter spectroscopy of fission fragments and related emission products

International Nuclear Information System (INIS)

Ruben, A.; Jahnke, U.

1993-01-01

An exclusive measurement of the 252 C f(sf) fragment distribution in mass and energy in coincidence with the related emission products by combining a twin ionization chamber with a 4π-neutron tank, a n-γ-detector, and a solid-state detector telescope is presented. The experimental set-up, data handling and acquisition is described followed by a discussion of the raw data evaluation. (orig.)

J-PET detector system for studies of the electron-positron annihilations

Directory of Open Access Journals (Sweden)

Pawlik-Niedźwiecka M.

2016-01-01

Full Text Available Jagiellonian Positron Emission Tomograph (J-PET has been recently constructed at the Jagiellonian University as a prototype of a cost-effective scanner for the metabolic imaging of the whole human body. J-PET detector is optimized for the measurement of momentum and polarization of photons from the electron-positron annihilations. It is built out of strips of plastic scintillators, forming three cylindrical layers. As detector of gamma quanta it will be used for studies of discrete symmetries and multiparticle entanglement of photons originating from the decays of ortho-positronium atoms.

Radiation detectors

International Nuclear Information System (INIS)

2013-01-01

This sixth chapter presents the operational principles of the radiation detectors; detection using photographic emulsions; thermoluminescent detectors; gas detectors; scintillation detectors; liquid scintillation detectors; detectors using semiconductor materials; calibration of detectors; Bragg-Gray theory; measurement chain and uncertainties associated to measurements

Sensitization by UV light of α-Al2O3:C polycrystalline detectors

International Nuclear Information System (INIS)

Meira B, L. C.; Rubio F, H.; Neres de A, E.; Santos, A.

2014-08-01

This paper describes an increase in sensitivity to gamma and beta radiation on α-Al 2 O 3 :C polycrystalline detector, which has been produced by a sol-gel process, following previous exposure to ultraviolet light. The increased sensitivity of the detector as a function of the exposure time and ultraviolet wavelength was studied. Since the main luminescent centers have emission peaks at different wavelengths, selective measurements of thermoluminescent emission intensity were done, in order to investigate the possible conversion of centers as a result of the exposition to ultraviolet light. Experimental results indicate that the nature and parameters of the luminescent centers in α-Al 2 O 3 :C sol-gel material can be very different of those in α-Al 2 O 3 :C single crystal. (author)

MCNPX calculations for electron irradiated semiconductor detectors

International Nuclear Information System (INIS)

Sedlackova, K.; Necas, V.; Sagatova, A.; Zatko, B.

2014-01-01

This study aimed to treat some practical problems of (not only) semiconductor material irradiation by high energy electron beam using MCNPX simulation code. The relation between the absorbed dose and the fluency was found and the energy distribution of electron flux density was simulated on the top and back side of 270 μm thick GaAs, SiC and Si detectors. Furthermore, the dose depth profiles were calculated for GaAs, SiC and Si materials irradiated by 4 and 5 MeV electron beams. For the GaAs detector, a very good agreement with the experiment was shown. To match the absolute values of the absorbed dose with experimentally obtained values, the electron source emissivity has to be determined in relation to the electron beam setting parameters. (authors)

A novel, SiPM-array-based, monolithic scintillator detector for PET

NARCIS (Netherlands)

Schaart, Dennis R.; van Dam, Herman T.; Seifert, Stefan; Vinke, Ruud; Dendooven, Peter; Beekman, Freek J.; Löhner, H.

2009-01-01

Silicon photomultipliers (SiPMs) are of great interest to positron emission tomography (PET), as they enable new detector geometries, for e. g., depth-of-interaction (DOI) determination, are MR compatible, and offer faster response and higher gain than other solid-state photosensors such as

Dose ratio proton radiography using the proximal side of the Bragg peak

Energy Technology Data Exchange (ETDEWEB)

Doolan, P. J., E-mail: paul.doolan.09@ucl.ac.uk; Royle, G.; Gibson, A. [Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT (United Kingdom); Lu, H.-M. [Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Prieels, D.; Bentefour, E. H. [Ion Beam Applications (IBA), 3 Chemin du Cyclotron, Louvain la Neuve B-1348 (Belgium)

2015-04-15

Purpose: In recent years, there has been a movement toward single-detector proton radiography, due to its potential ease of implementation within the clinical environment. One such single-detector technique is the dose ratio method in which the dose maps from two pristine Bragg peaks are recorded beyond the patient. To date, this has only been investigated on the distal side of the lower energy Bragg peak, due to the sharp falloff. The authors investigate the limits and applicability of the dose ratio method on the proximal side of the lower energy Bragg peak, which has the potential to allow a much wider range of water-equivalent thicknesses (WET) to be imaged. Comparisons are made with the use of the distal side of the Bragg peak. Methods: Using the analytical approximation for the Bragg peak, the authors generated theoretical dose ratio curves for a range of energy pairs, and then determined how an uncertainty in the dose ratio would translate to a spread in the WET estimate. By defining this spread as the accuracy one could achieve in the WET estimate, the authors were able to generate lookup graphs of the range on the proximal side of the Bragg peak that one could reliably use. These were dependent on the energy pair, noise level in the dose ratio image and the required accuracy in the WET. Using these lookup graphs, the authors investigated the applicability of the technique for a range of patient treatment sites. The authors validated the theoretical approach with experimental measurements using a complementary metal oxide semiconductor active pixel sensor (CMOS APS), by imaging a small sapphire sphere in a high energy proton beam. Results: Provided the noise level in the dose ratio image was 1% or less, a larger spread of WETs could be imaged using the proximal side of the Bragg peak (max 5.31 cm) compared to the distal side (max 2.42 cm). In simulation, it was found that, for a pediatric brain, it is possible to use the technique to image a region with a

Spontaneous light emission from fibers in MINOS

International Nuclear Information System (INIS)

Avvakumov, S.; Barrett, W.L.; Belias, T.; Bower, C.; Erwin, A.; Kordosky, M.; Lang, K.; Lee, R.; Liu, J.; Miller, W.; Mualem, L.; Nichol, R.; Nelson, J.; Pearce, G.; Proga, M.; Rebel, B.; Ruddick, K.; Smith, C.; Thomas, J.; Vahle, P.; Webb, R.

2005-01-01

We report on the observation and measurements of unexpected background rates in the MINOS Far Detector. The noise level at the Far Detector is significantly greater than that expected from natural radioactivity and intrinsic photomultiplier dark current. We have conducted a series of additional tests which demonstrate that the excess rate is caused by spontaneous light emission in the wavelength-shifting fibers, which are used to read out signals from scintillator strips. This noise due to fibers exhibits an exponential fall off with time with a decay time constant of the order of 100 days

Giant proximity effect in ferromagnetic bilayers

Science.gov (United States)

Ramos, Silvia; Charlton, Tim; Quintanilla, Jorge; Suter, Andreas; Moodera, Jagadeesh; Prokscha, Thomas; Salman, Zaher; Forgan, Ted

2013-03-01

The proximity effect is a phenomenon where an ordered state leaks from a material into an adjacent one over some finite distance, ξ. For superconductors, this distance is ~ the coherence length. Nevertheless much longer-range, ``giant'' proximity effects have been observed in cuprate junctions. This surprising effect can be understood as a consequence of critical opalescence. Since this occurs near all second order phase transitions, giant proximity effects should be very general and, in particular, they should be present in magnetic systems. The ferromagnetic proximity effect has the advantage that its order parameter (magnetization) can be observed directly. We investigate the above phenomenon in Co/EuS bilayer films, where both materials undergo ferromagnetic transitions but at rather different temperatures (bulk TC of 1400K for Co and 16.6K for EuS). A dramatic increase in the range of the proximity effect is expected near the TC of EuS. We present the results of our measurements of the magnetization profiles as a function of temperature, carried out using the complementary techniques of low energy muon rotation and polarized neutron reflectivity. Work supported by EPSRC, STFC and ONR grant N00014-09-1-0177 and NSF grant DMR 0504158.

Characterization of a diamond detector to be used as neutron yield monitor during the in-vessel calibration of JET neutron detectors in preparation of the DT experiment

International Nuclear Information System (INIS)

Pillon, Mario; Angelone, Maurizio; Batistoni, Paola; Loreti, Stefano; Milocco, Alberto

2016-01-01

Highlights: • A diamond detector has been characterized for use as neutron yield monitor of a portable 14 MeV neutron generator. • The system will be used for the 14 MeV calibration of JET neutron detector. • The results and the performances of the monitor are very satisfactory in term of accuracy and reliability. - Abstract: A new Deuterium-Tritium (DT) campaign is planned at JET. An accurate calibration for the 14 MeV neutron yield monitors is necessary. In order to perform the calibration a 14 MeV Neutron Generator with suitable intensity (∼10 8 n/s) will be used. Due to the intensity change during the Neutron Generator lifetime it would be necessary to monitor continuously the neutron emission intensity during the calibration using a compact detector attached to it. A high quality diamond detector has been chosen as one of the monitors. This detector has been fully characterized at the 14 MeV Frascati Neutron Generator facility. The characterization procedure and the resulting 14 MeV neutron response of the detector are described in this paper together with the obtained uncertainties.

The application of an ultraviolet sensitive fire detector in a manned space vehicle.

Science.gov (United States)

Linford, R. M. F.

1971-01-01

Description of a detector which is sensitive to the ultraviolet molecular emissions of flames and has been selected as the basic element of the NASA Skylab fire-detection system. This detector is sensitive to approximately 10 to the minus 12th watts of ultraviolet radiation and will detect small flames at distances in excess of three meters. Its response to a variety of burning spacecraft materials has been investigated both in one-gravity and zero-gravity. The results of experiments conducted in an aircraft flying zero-gravity parabolas in an attempt to simulate the characteristics of a fire which the detector must sense are cited.

Performance of low-cost X-ray area detectors with consumer digital cameras

International Nuclear Information System (INIS)

Panna, A.; Gomella, A.A.; Harmon, K.J.; Chen, P.; Miao, H.; Bennett, E.E.; Wen, H.

2015-01-01

We constructed X-ray detectors using consumer-grade digital cameras coupled to commercial X-ray phosphors. Several detector configurations were tested against the Varian PaxScan 3024M (Varian 3024M) digital flat panel detector. These include consumer cameras (Nikon D800, Nikon D700, and Nikon D3X) coupled to a green emission phosphor in a back-lit, normal incidence geometry, and in a front-lit, oblique incidence geometry. We used the photon transfer method to evaluate detector sensitivity and dark noise, and the edge test method to evaluate their spatial resolution. The essential specifications provided by our evaluation include discrete charge events captured per mm 2 per unit exposure surface dose, dark noise in equivalents of charge events per pixel, and spatial resolution in terms of the full width at half maximum (FWHM) of the detector's line spread function (LSF). Measurements were performed using a tungsten anode X-ray tube at 50 kVp. The results show that the home-built detectors provide better sensitivity and lower noise than the commercial flat panel detector, and some have better spatial resolution. The trade-off is substantially smaller imaging areas. Given their much lower costs, these home-built detectors are attractive options for prototype development of low-dose imaging applications

A study of the radiative K{sub L}{yields}{pi}{sup {+-}}e{sup -+}{nu}{gamma} decay and search for direct photon emission with the KLOE detector

Energy Technology Data Exchange (ETDEWEB)

Ambrosino, F.; Chiefari, G.; Massarotti, P.; Meola, S.; Napolitano, M.; Perfetto, F.; Saracino, G. [Univ. ' Federico II' , Dipt. di Scienze Fisiche, Napoli (Italy)]|[INFN Sezione di Napoli, Napoli (Italy); Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bertolucci, S.; Bloise, C.; Bossi, F.; Campana, P.; Capon, G.; Capussela, T.; Chi, S.; Ciambrone, P.; De Lucia, E.; De Simone, P.; Dreucci, M.; Felici, G.; Ferrari, A.; Ferrer, M.L.; Forti, C.; Gatti, C.; Giovannella, S.; Lanfranchi, G.; Mei, W.; Miscetti, S.; Moulson, M.; Mueller, S.; Murtas, F.; Palutan, M.; Santangelo, P.; Sciascia, B.; Sibidanov, A.; Spadaro, T.; Venanzoni, G. [Lab. Nazionali di Frascati dell' INFN, Frascati (Roma) (Italy); Archilli, F. [Univ. ' Tor Vergata' , Dipt. di Fisica, Roma (Italy)]|[INFN Sezione di Roma Tor Vergata, Roma (Italy); Bacci, C.; Bocchetta, S.; Ceradini, F.; Cesario, F.; Di Micco, B.; Nguyen, F. [Univ. ' Roma Tre' , Dipt. di Fisica, Roma (Italy)]|[INFN Sezione di Roma Tre, Roma (Italy); Beltrame, P.; Denig, A.; Kluge, W.; Leone, D. [Univ. et Karlsruhe, Inst. fuer Experimentelle Kernphysik, Karlsruhe (Germany); Bini, C.; Caloi, R.; De Santis, A.; De Zorzi, G.; Di Domenico, A.; Fiore, S.; Franzini, P.; Gauzzi, P.; Lacava, F.; Testa, M. [Univ. ' La Sapienza' , Dipt. di Fisica, Roma (Italy)]|[INFN Sezione di Roma, Roma (Italy); Branchini, P.; Graziani, E.; Passeri, A.; Tortora, L. [INFN Sezione di Roma Tre, Roma (Italy); Crucianelli, F. [Univ. ' La Sapienza' , Dipt. di Fisica, Roma (Italy); Di Donato, C.; Doria, A. [INFN Sezione di Napoli, Napoli (Italy); Gorini, E. [Univ. Lecce, Dipt. di Fisica, Lecce (Italy)]|[INFN Sezione di Lecce, Lecce (Italy); Kulikov, V. [Inst. for Theoretical and Experimental Physics, Moscow (Russian Federation); Lee-Franzini, J. [Lab. Nazionali di Frascati dell' INFN, Frascati (Roma) (Italy)]|[State Univ. of New York, Physics Dept., Stony Brook (United States)] [and others

2008-06-15

We present a measurement of the ratio R={gamma}(K{sup 0}{sub e3{gamma}};E{sup *}{sub {gamma}}>30 MeV, {theta}{sup *}{sub {gamma}}>20 )/{gamma}(K{sup 0}{sub e3}) and a first measurement of the direct emission contribution in semileptonic K{sub L} decays. The measurement was performed at the DA{phi}NE{phi} factory by selecting {phi}{yields}K{sub L}K{sub S} decays with the KLOE detector. We use 328 pb{sup -1} of data, corresponding to about 3.5 million K{sup 0}{sub e3} events and about 9000 K{sup 0}{sub e3{gamma}} radiative events. Our result is R=(924{+-}23{sub stat}{+-}16{sub syst}) x 10{sup -5} for the branching ratio and left angle X right angle =-2.3{+-}1.3{sub stat}{+-}1.4{sub syst} for the effective strength parameter describing direct emission. (orig.)

Ultrasonic Detectors Safely Identify Dangerous, Costly Leaks

Science.gov (United States)

2013-01-01

In 1990, NASA grounded its space shuttle fleet. The reason: leaks detected in the hydrogen fuel systems of the Space Shuttles Atlantis and Columbia. Unless the sources of the leaks could be identified and fixed, the shuttles would not be safe to fly. To help locate the existing leaks and check for others, Kennedy Space Center engineers used portable ultrasonic detectors to scan the fuel systems. As a gas or liquid escapes from a leak, the resulting turbulence creates ultrasonic noise, explains Gary Mohr, president of Elmsford, New York-based UE Systems Inc., a long-time leader in ultrasonic detector technologies. "In lay terms, the leak is like a dog whistle, and the detector is like the dog ear." Because the ultrasound emissions from a leak are highly localized, they can be used not only to identify the presence of a leak but also to help pinpoint a leak s location. The NASA engineers employed UE s detectors to examine the shuttle fuel tanks and solid rocket boosters, but encountered difficulty with the devices limited range-certain areas of the shuttle proved difficult or unsafe to scan up close. To remedy the problem, the engineers created a long-range attachment for the detectors, similar to "a zoom lens on a camera," Mohr says. "If you are on the ground, and the leak is 50 feet away, the detector would now give you the same impression as if you were only 25 feet away." The enhancement also had the effect of reducing background noise, allowing for a clearer, more precise detection of a leak s location.

Development of a fragment detector system for the study of peripheral collisions at high beam energies

International Nuclear Information System (INIS)

Spies, H.

1992-06-01

In the framework of the experimental program at the accelerator facilities SIS/ESR of the Society for Heavy-Ion research in Darmstadt one of the essential research aims of the LAND collaboration is the study of high-lying collective states after electromagnetic excitation in heavy-ion collisions at nearly relativistic beam energies. By the exchange of virtual photons with high energy giant resonances are excited with high probabilities. The main decay channel of giant resonances in heavy nuclei is the emission of neutrons as well as below the particle threshold the emission of γ radiation. For the study of these states a detector system was developed, which makes the kinematically complete measurement of all reaction partners possible. For the determination of the neutron energy serves the Large Area Neutron Detector LAND, a time-of-flight spectrometer for high-energetic neutrons. For the measurement of the γ radiation emitted by the excited projectile the target is surrounded by an array of 48 BaF 2 crystals. A radiation detector system consisting of 6 single detectors and further 5 help detectors allows together with the magnetic spectrometer ALADIN the identification of the heavy projectile fragments by charge, momentum, and mass. Four position-sensitive plastic scintillators serve for the measurement of the trajectory of the projectile respectively the projectile fragments in front and behind the deviating magnet. Additionally with these detectors the velocity is measured. For the determination of the nuclear charge of the projectile fragments serve a multiple-ionization chamber and a Cherenkov detector. In this thesis the development and taking into operation of the LAND radiation detector system is described. (orig./HSI) [de

Prototype of high resolution PET using resistive electrode position sensitive CdTe detectors

International Nuclear Information System (INIS)

Kikuchi, Yohei; Ishii, Keizo; Matsuyama, Shigeo; Yamazaki, Hiromichi

2008-01-01

Downsizing detector elements makes it possible that spatial resolutions of positron emission tomography (PET) cameras are improved very much. From this point of view, semiconductor detectors are preferable. To obtain high resolution, the pixel type or the multi strip type of semiconductor detectors can be used. However, in this case, there is a low packing ratio problem, because a dead area between detector arrays cannot be neglected. Here, we propose the use of position sensitive semiconductor detectors with resistive electrode. The CdTe detector is promising as a detector for PET camera because of its high sensitivity. In this paper, we report development of prototype of high resolution PET using resistive electrode position sensitive CdTe detectors. We made 1-dimensional position sensitive CdTe detectors experimentally by changing the electrode thickness. We obtained 750 A as an appropriate thickness of position sensitive detectors, and evaluated the performance of the detector using a collimated 241 Am source. A good position resolution of 1.2 mm full width half maximum (FWHM) was obtained. On the basis of the fundamental development of resistive electrode position sensitive detectors, we constructed a prototype of high resolution PET which was a dual head type and was consisted of thirty-two 1-dimensional position sensitive detectors. In conclusion, we obtained high resolutions which are 0.75 mm (FWHM) in transaxial, and 1.5 mm (FWHM) in axial. (author)

Quantum Proximity Resonances

International Nuclear Information System (INIS)

Heller, E.J.

1996-01-01

It is well known that at long wavelengths λ an s-wave scatterer can have a scattering cross section σ on the order of λ 2 , much larger than its physical size, as measured by the range of its potential. Very interesting phenomena can arise when two or more identical scatterers are placed close together, well within one wavelength. We show that, for a pair of identical scatterers, an extremely narrow p-wave open-quote open-quote proximity close-quote close-quote resonance develops from a broader s-wave resonance of the individual scatterers. A new s-wave resonance of the pair also appears. The relation of these proximity resonances (so called because they appear when the scatterers are close together) to the Thomas and Efimov effects is discussed. copyright 1996 The American Physical Society

Early results for treatment of two- and three-part fractures of the proximal humerus using Contours PHP (proximal humeral plate).

Science.gov (United States)

Biazzo, Alessio; Cardile, Carlo; Brunelli, Luca; Ragni, Paolo; Clementi, Daniele

2017-04-28

The management of displaced 2- and 3-part fractures of the proximal humerus is controversial, both in younger and in elderly patients. The purpose of this paper is to evaluate the functional results of the Contours Proximal Humerus Plate (OrthofixR, Bussolengo,Verona, Italy), for the treatment of displaced 2- and 3-part fractures of the proximal humerus. We retrospectively reviewed 55 patients with proximal humerus fractures, who underwent osteosynthesis with Contours Proximal Humerus Plate from December 2011 to March 2015. We had 21 patients with 2-part fractures and with an average age of 67.1 years and 34 patients with 3-part fractures, with average age of 63.6 years. The average union time was 3 months. The mean Constant score was 67 for 2-part fracture group and 64.9 for 3-part fracture group. The difference was not statistically significant (p = 0.18). The overall complication rate was 14.5 %. Six patients underwent additional surgery (10.9%). The most frequent major complication was secondary loss of reduction following varus collapse of the fracture (2 cases). In these patients, there was loss of medial hinge integrity due to impaction and osteoporosis. The placement of the main locking screw in the calcar area to provide inferomedial support is the rational of the Contours Proximal Humerus Plate. Osteosynthesis with Contours Proximal Humerus Plate is a safe system for treating displaced 2- and 3-part fractures of the proximal humerus, with good functional results and complication rates comparable to those reported in the literature.

Detectors for high resolution dynamic positron emission tomography

International Nuclear Information System (INIS)

Derenzo, S.E.; Budinger, T.F.; Huesman, R.H.

1985-01-01

Tomography is the technique of producing a photographic image of an opaque specimen by transmitting a beam of x-rays or gamma rays through the specimen onto an adjacent photographic film. The image results from variations in thickness, density, and chemical composition, of the specimen. This technique is used to study the metabolism of the human brain. This article examines the design of equipment used for high resolution dynamic positron emission tomography. 27 references, 5 figures, 3 tables

The Contribution of SPECT/CT in the Diagnosis of Stress Fracture of the Proximal Tibia.

Science.gov (United States)

Okudan, Berna; Coşkun, Nazım; Arıcan, Pelin

2018-02-01

Stress fractures are injuries most commonly seen in the lower limbs and are usually caused by repetitive stress. While the distal and middle third of the tibia is the most frequent site for stress fractures (almost 50%), stress fractures of the proximal tibia is relatively rare and could be confused with other types of tibial fractures, thus altering management plans for the clinician. Early diagnosis of stress fractures is also important to avoid complications. Imaging plays an important role in the diagnosis of stress fractures, especially bone scan. Combined with single-photon emission computed tomography/computed tomography (SPECT/CT) it is an important imaging technique for stress fractures in both upper and lower extremities, and is widely preferred over other imaging techniques. In this case, we present the case of a 39-year-old male patient diagnosed with stress fracture of the proximal tibia and demonstrate the contribution of CT scan fused with SPECT imaging in the early diagnosis of stress fracture prior to other imaging modalities.

Ionization detector

International Nuclear Information System (INIS)

Steele, D.S.

1987-01-01

An ionization detector having an array of detectors has, for example, grounding pads positioned in the spaces between some detectors (data detectors) and other detectors (reference detectors). The grounding pads are kept at zero electric potential, i.e. grounded. The grounding serves to drain away electrons and thereby prevent an unwanted accumulation of charge in the spaces, and cause the electric field lines to be more perpendicular to the detectors in regions near the grounding pads. Alternatively, no empty space is provided there being additional, grounded, detectors provided between the data and reference detectors. (author)

Gamma emission tomosynthesis based on an automated slant hole collimation system

Science.gov (United States)

Pellegrini, R.; Pani, R.; Cinti, M. N.; Longo, M.; Lo Meo, S.; Viviano, M.

2015-03-01

The imaging capabilities of radioisotope molecular imaging systems are limited by their ring geometry and by the object-to-detector distance, which impairs spatial resolution, efficiency and image quality. These detection capabilities could be enhanced by performing acquisitions with dedicated gamma cameras placed in close proximity to the object that has to be examined. The main aim of this work is to develop a compact camera suitable for detecting small and low-contrast lesions, with a higher detection efficiency than conventional SPECT, through a gamma emission tomosynthesis method. In this contribution a prototype of a new automated slant hole collimator, coupled to a small Field of View (FoV) gamma camera, is presented. The proposed device is able to acquire planar projection images at different angles without rotating around the patient body; these projection images are then three-dimensional reconstructed. Therefore, in order to perform the volumetric reconstruction of the studied object, the traditional Back Projection (BP) reconstruction is compared with the Shift And Add (SAA) method. In order to verify the effectiveness of the technique and to test the image reconstruction algorithms, a Monte Carlo simulation, based on the GEANT4 code, was implemented. The method was also validated by a set of experimental measurements. The discussed device is designed to work in patient proximity for detecting lesions placed at a distances ranged from 0 to 8 cm, thus allowing few millimeters planar resolutions and sagittal resolution of about 2 cm. The new collimation method implies high-resolution capabilities demonstrated by reconstructing the projection images through the BP and the SAA methods. The latter is simpler than BP and produces comparable spatial resolutions with respect to the traditional tomographic method, while preserving the image counts.

Proximal Hamstring Tendinosis and Partial Ruptures.

Science.gov (United States)

Startzman, Ashley N; Fowler, Oliver; Carreira, Dominic

2017-07-01

Proximal hamstring tendinosis and partial hamstring origin ruptures are painful conditions of the proximal thigh and hip that may occur in the acute, chronic, or acute on chronic setting. Few publications exist related to their diagnosis and management. This systematic review discusses the incidence, treatment, and prognosis of proximal hamstring tendinosis and partial hamstring ruptures. Conservative treatment measures include nonsteroidal anti-inflammatory drugs, physical therapy, rest, and ice. If these measures fail, platelet-rich plasma or shockwave therapy may be considered. When refractory to conservative management, these injuries may be treated with surgical debridement and hamstring reattachment. [Orthopedics. 2017; 40(4):e574-e582.]. Copyright 2017, SLACK Incorporated.

The future of the SIRAD SEE facility Ion-Electron Emission Microscopy

CERN Document Server

Wyss, J; Kaminski, A; Magalini, A; Nigro, M; Pantano, D; Sedhykh, S

2002-01-01

The SIRAD facility is dedicated to radiation damage studies on semiconductor detectors, electronic devices and systems, using proton and ion beams delivered by a 15 MV tandem accelerator. It is routinely used by groups involved in detector development for elementary particle physics, electronic device physics and space applications. In particular, Single Event Effect studies are very important to the latter two activities. Presently, the facility can only characterize the global sensitivity of a device or system to single ion impacts. To map out the sensitivity of a device with micrometric resolution, following an idea developed at SANDIA, we will implement an Ion-Electron Emission Microscope (IEEM) to reconstruct the X,Y and time coordinates of an impacting energetic ion by imaging the secondary electrons emitted by the sample using a standard emission electron microscope and position sensitive detector system. After describing typical Single Event Effect activities at SIRAD we will discuss the basic princip...

Proximal Participation: A Pathway into Work

Science.gov (United States)

Chan, Selena

2013-01-01

In a longitudinal case study of apprentices, the term proximal participation was coined to describe the entry process of young people, with unclear career destinations, into the trade of baking. This article unravels the significance of proximal participation in the decision-making processes of young people who enter a trade through initial…

Luminiscent emission of molecular levels excited by ionizant radiations

International Nuclear Information System (INIS)

Ortiz Ramis, M.

1977-01-01

The emission spectra and the time dependence of scintillations produced by alpha particles, gamma rays and ultraviolet light in some organic compounds crystals and liquids solutions normally used as radiation detectors has been studied. (author) [es

Charge collection in Si detectors irradiated in situ at superfluid helium temperature

Energy Technology Data Exchange (ETDEWEB)

Verbitskaya, Elena, E-mail: elena.verbitskaya@cern.ch [Ioffe Institute, 26 Politekhnicheskaya str., St. Petersburg 194021 (Russian Federation); Eremin, Vladimir; Zabrodskii, Andrei [Ioffe Institute, 26 Politekhnicheskaya str., St. Petersburg 194021 (Russian Federation); Dehning, Bernd; Kurfürst, Christoph; Sapinski, Mariusz; Bartosik, Marcin R. [CERN, CH-1211, Geneva 23 (Switzerland); Egorov, Nicolai [Research Institute of Material Science and Technology, 4 Passage 4806, Moscow, Zelenograd 124460 (Russian Federation); Härkönen, Jaakko [Helsinki Institute of Physics, P.O.Box 64 (Gustaf Hallströmin katu 2) FI-00014 University of Helsinki (Finland)

2015-10-01

Silicon and diamond detectors operated in a superfluid helium bath are currently being considered for the upgrade of the LHC beam loss monitoring system. The detectors would be installed in immediate proximity of the superconducting coils of the triplet magnets. We present here the results of the in situ irradiation test for silicon detectors using 23 GeV protons while keeping the detectors at a temperature of 1.9 K. Red laser (630 nm) Transient Current Technique and DC current measurements were used to study the pulse response and collected charge for silicon detectors irradiated to a maximum radiation fluence of 1×10{sup 16} p/cm{sup 2}. The dependence between collected charge and irradiation fluence was parameterized using the Hecht equation and assumption of a uniform electric field distribution. The collected charge was found to degrade with particle fluence for both bias polarities. We observed that the main factor responsible for this degradation was related to trapping of holes on the donor-type radiation-induced defects. In contrast to expectations, along with formation of donors, acceptor-type defects (electron traps) are introduced into the silicon bulk. This suggests that the current models describing charge collection in irradiated silicon detectors require an extension for taking into account trapping at low temperatures with a contribution of shallow levels. New in situ irradiation tests are needed and planned now to extend statistics of the results and gain a deeper insight into the physics of low temperature detector operation in harsh radiation environment. - Highlights: • Si detectors irradiated in situ at 1.9 K by 23 GeV protons are further studied. • Trapping parameters are derived from the fits of collected charge vs. fluence data. • Acceptor-type defects are likely to be induced along with donor-type ones. • Trapping of holes has a dominating effect on the collected charge degradation. • New tests are planned to gain deeper insight

Ultimate and proximate explanations of strong reciprocity.

Science.gov (United States)

Vromen, Jack

2017-08-23

Strong reciprocity (SR) has recently been subject to heated debate. In this debate, the "West camp" (West et al. in Evol Hum Behav 32(4):231-262, 2011), which is critical of the case for SR, and the "Laland camp" (Laland et al. in Science, 334(6062):1512-1516, 2011, Biol Philos 28(5):719-745, 2013), which is sympathetic to the case of SR, seem to take diametrically opposed positions. The West camp criticizes advocates of SR for conflating proximate and ultimate causation. SR is said to be a proximate mechanism that is put forward by its advocates as an ultimate explanation of human cooperation. The West camp thus accuses advocates of SR for not heeding Mayr's original distinction between ultimate and proximate causation. The Laland camp praises advocates of SR for revising Mayr's distinction. Advocates of SR are said to replace Mayr's uni-directional view on the relation between ultimate and proximate causes by the bi-directional one of reciprocal causation. The paper argues that both the West camp and the Laland camp misrepresent what advocates of SR are up to. The West camp is right that SR is a proximate cause of human cooperation. But rather than putting forward SR as an ultimate explanation, as the West camp argues, advocates of SR believe that SR itself is in need of ultimate explanation. Advocates of SR tend to take gene-culture co-evolutionary theory as the correct meta-theoretical framework for advancing ultimate explanations of SR. Appearances notwithstanding, gene-culture coevolutionary theory does not imply Laland et al.'s notion of reciprocal causation. "Reciprocal causation" suggests that proximate and ultimate causes interact simultaneously, while advocates of SR assume that they interact sequentially. I end by arguing that the best way to understand the debate is by disambiguating Mayr's ultimate-proximate distinction. I propose to reserve "ultimate" and "proximate" for different sorts of explanations, and to use other terms for distinguishing

SiC detectors to monitor ionizing radiations emitted from nuclear events and plasmas

Science.gov (United States)

Torrisi, L.; Cannavò, A.

2016-09-01

Silicon Carbide (SiC) semiconductor detectors are increasingly employed in Nuclear Physics for their advantages with respect to traditional silicon (Si). Such detectors show an energy resolution, charge mobility, response velocity and detection efficiency similar to Si detectors. However, the higher band gap (3.26 eV), the lower leakage current (∼10 pA) maintained also at room temperature, the higher radiation hardness and the higher density with respect to Si represent some indisputable advantages characterizing such detectors. The devices can be employed at high temperatures, at high absorbed doses and in the case of high visible light intensities, for example, in plasma, for limited exposition times without damage. Generally SiC Schottky diodes are employed in reverse polarization with an active region depth of the order of 100 µm, purity below 1014 cm-3 and an active area lower than 1 cm2. Measurements in the regime of proportionality with the radiation energy released in the active region and measurements in time-of-flight configuration are employed for nuclear emission events produced at both low and high fluences. Alpha spectra demonstrated an energy resolution of about 1.3% at 5.8 MeV. Radiation emission from laser-generated plasma can be monitored in terms of detected photons, electrons and ions, using the laser pulse as a start signal and the radiation detection as a stop signal, enabling to measure the ion velocity by knowing the target-detector flight distance. SiC spectra acquired in the Messina University laboratories using radioactive ion sources and at the PALS laboratory facility in Prague (Czech Republic) are presented. A preliminary study of the use of SiC detectors, embedded in a water equivalent polymer, as a dosimeter is presented and discussed.

The resonant detector and its application to epithermal neutron spectroscopy

International Nuclear Information System (INIS)

Gorini, G.; Perelli-Cippo, E.; Tardocchi, M.; Andreani, C.; D'Angelo, A.; Pietropaolo, A.; Senesi, R.; Imberti, S.; Bracco, A.; Previtali, E.; Pessina, G.; Rhodes, N.J.; Schooneveld, E.M.

2004-01-01

New perspectives for epithermal neutron spectroscopy are being opened by the development of the resonant detector (RD) and its use on inverse geometry time of flight spectrometers at spallation sources. The RD was first proposed in the 1980s and was recently brought to a performance level exceeding conventional neutron-sensitive Li-glass scintillator detectors. It features a photon counter coupled to a neutron analyzer foil. Resonant neutron absorption in the foil results in the emission of prompt gamma rays that are detected in the photon counter. The dimensions of the RD set the spatial resolution that can be achieved, ranging from a fraction of a cm to several cm. It can thus be tailored to the construction of detector arrays of different geometry. The main results of the research on this kind of detector are reported leading to the present optimized RD design based on a combination of YAP scintillation photon counter and uranium or gold analyzer foils. This detector has already been selected for application in the upgrade of the VESUVIO spectrometer on ISIS. A special application is the Very Low Angle Detector (VLAD) bank, which will extend the kinematical region for neutron scattering to low momentum transfer ( -1 ) whilst still keeping energy transfer >1 eV, thus allowing new experimental studies in condensed matter systems. The first results of tests made with prototype VLAD detectors are presented, confirming the usefulness of the RD for measurements at scattering angles as low as 2-5 deg

Absolute luminosity measurements with the LHCb detector at the LHC

CERN Document Server

Aaij, R; Adinolfi, M; Adrover, C; Affolder, A; Ajaltouni, Z; Albrecht, J; Alessio, F; Alexander, M; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amhis, Y; Anderson, J; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Arrabito, L; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Bachmann, S; Back, J J; Bailey, D S; Balagura, V; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Bates, A; Bauer, C; Bauer, Th; Bay, A; Bediaga, I; Belous, K; Belyaev, I; Ben-Haim, E; Benayoun, M; Bencivenni, G; Benson, S; Benton, J; Bernet, R; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bizzeti, A; Bjørnstad, P M; Blake, T; Blanc, F; Blanks, C; Blouw, J; Blusk, S; Bobrov, A; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borgia, A; Bowcock, T J V; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Brisbane, S; Britsch, M; Britton, T; Brook, N H; Brown, H; Büchler-Germann, A; Burducea, I; Bursche, A; Buytaert, J; Cadeddu, S; Caicedo Carvajal, J M; Callot, O; Calvi, M; Calvo Gomez, M; Camboni, A; Campana, P; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carson, L; Carvalho Akiba, K; Casse, G; Cattaneo, M; Charles, M; Charpentier, Ph; Chiapolini, N; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coca, C; Coco, V; Cogan, J; Collins, P; Constantin, F; Conti, G; Contu, A; Cook, A; Coombes, M; Corti, G; Cowan, G A; Currie, R; D'Almagne, B; D'Ambrosio, C; David, P; De Bonis, I; De Capua, S; De Cian, M; De Lorenzi, F; De Miranda, J M; De Paula, L; De Simone, P; Decamp, D; Deckenhoff, M; Degaudenzi, H; Deissenroth, M; Del Buono, L; Deplano, C; Deschamps, O; Dettori, F; Dickens, J; Dijkstra, H; Diniz Batista, P; Donleavy, S; Dordei, F; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dupertuis, F; Dzhelyadin, R; Eames, C; Easo, S; Egede, U; Egorychev, V; Eidelman, S; van Eijk, D; Eisele, F; Eisenhardt, S; Ekelhof, R; Eklund, L; Elsasser, Ch; d'Enterria, D G; Esperante Pereira, D; Estève, L; Falabella, A; Fanchini, E; Färber, C; Fardell, G; Farinelli, C; Farry, S; Fave, V; Fernandez Albor, V; Ferro-Luzzi, M; Filippov, S; Fitzpatrick, C; Fontana, M; Fontanelli, F; Forty, R; Frank, M; Frei, C; Frosini, M; Furcas, S; Gallas Torreira, A; Galli, D; Gandelman, M; Gandini, P; Gao, Y; Garnier, J-C; Garofoli, J; Garra Tico, J; Garrido, L; Gaspar, C; Gauvin, N; Gersabeck, M; Gershon, T; Ghez, Ph; Gibson, V; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gordon, H; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graziani, G; Grecu, A; Gregson, S; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Haefeli, G; Haen, C; Haines, S C; Hampson, T; Hansmann-Menzemer, S; Harji, R; Harnew, N; Harrison, J; Harrison, P F; He, J; Heijne, V; Hennessy, K; Henrard, P; Hernando Morata, J A; van Herwijnen, E; Hicks, E; Hofmann, W; Holubyev, K; Hopchev, P; Hulsbergen, W; Hunt, P; Huse, T; Huston, R S; Hutchcroft, D; Hynds, D; Iakovenko, V; Ilten, P; Imong, J; Jacobsson, R; Jaeger, A; Jahjah Hussein, M; Jans, E; Jansen, F; Jaton, P; Jean-Marie, B; Jing, F; John, M; Johnson, D; Jones, C R; Jost, B; Kandybei, S; Karacson, M; Karbach, T M; Keaveney, J; Kerzel, U; Ketel, T; Keune, A; Khanji, B; Kim, Y M; Knecht, M; Koblitz, S; Koppenburg, P; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kruzelecki, K; Kucharczyk, M; Kukulak, S; Kumar, R; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanciotti, E; Lanfranchi, G; Langenbruch, C; Latham, T; Le Gac, R; van Leerdam, J; Lees, J-P; Lefèvre, R; Leflat, A; Lefrançois, J; Leroy, O; Lesiak, T; Li, L; Li Gioi, L; Lieng, M; Liles, M; Lindner, R; Linn, C; Liu, B; Liu, G; Lopes, J H; Lopez Asamar, E; Lopez-March, N; Luisier, J; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Magnin, J; Malde, S; Mamunur, R M D; Manca, G; Mancinelli, G; Mangiafave, N; Marconi, U; Märki, R; Marks, J; Martellotti, G; Martens, A; Martin, L; Martín Sánchez, A; Martinez Santos, D; Massafferri, A; Matev, R; Mathe, Z; Matteuzzi, C; Matveev, M; Maurice, E; Maynard, B; Mazurov, A; McGregor, G; McNulty, R; Mclean, C; Meissner, M; Merk, M; Merkel, J; Messi, R; Miglioranzi, S; Milanes, D A; Minard, M-N; Monteil, S; Moran, D; Morawski, P; Mountain, R; Mous, I; Muheim, F; Müller, K; Muresan, R; Muryn, B; Musy, M; Mylroie-Smith, J; Naik, P; Nakada, T; Nandakumar, R; Nardulli, J; Nasteva, I; Nedos, M; Needham, M; Neufeld, N; Nguyen-Mau, C; Nicol, M; Nies, S; Niess, V; Nikitin, N; Oblakowska-Mucha, A; Obraztsov, V; Oggero, S; Ogilvy, S; Okhrimenko, O; Oldeman, R; Orlandea, M; Otalora Goicochea, J M; Owen, P; Pal, B; Palacios, J; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Parkes, C; Parkinson, C J; Passaleva, G; Patel, G D; Patel, M; Paterson, S K; Patrick, G N; Patrignani, C; Pavel-Nicorescu, C; Pazos Alvarez, A; Pellegrino, A; Penso, G; Pepe Altarelli, M; Perazzini, S; Perego, D L; Perez Trigo, E; Pérez-Calero Yzquierdo, A; Perret, P; Perrin-Terrin, M; Pessina, G; Petrella, A; Petrolini, A; Pie Valls, B; Pietrzyk, B; Pilar, T; Pinci, D; Plackett, R; Playfer, S; Plo Casasus, M; Polok, G; Poluektov, A; Polycarpo, E; Popov, D; Popovici, B; Potterat, C; Powell, A; du Pree, T; Prisciandaro, J; Pugatch, V; Puig Navarro, A; Qian, W; Rademacker, J H; Rakotomiaramanana, B; Rangel, M S; Raniuk, I; Raven, G; Redford, S; Reid, M M; dos Reis, A C; Ricciardi, S; Rinnert, K; Roa Romero, D A; Robbe, P; Rodrigues, E; Rodrigues, F; Rodriguez Perez, P; Rogers, G J; Roiser, S; Romanovsky, V; Rouvinet, J; Ruf, T; Ruiz, H; Sabatino, G; Saborido Silva, J J; Sagidova, N; Sail, P; Saitta, B; Salzmann, C; Sannino, M; Santacesaria, R; Santamarina Rios, C; Santinelli, R; Santovetti, E; Sapunov, M; Sarti, A; Satriano, C; Satta, A; Savrie, M; Savrina, D; Schaack, P; Schiller, M; Schleich, S; Schmelling, M; Schmidt, B; Schneider, O; Schopper, A; Schune, M -H; Schwemmer, R; Sciubba, A; Seco, M; Semennikov, A; Senderowska, K; Sepp, I; Serra, N; Serrano, J; Seyfert, P; Shao, B; Shapkin, M; Shapoval, I; Shatalov, P; Shcheglov, Y; Shears, T; Shekhtman, L; Shevchenko, O; Shevchenko, V; Shires, A; Silva Coutinho, R; Skottowe, H P; Skwarnicki, T; Smith, A C; Smith, N A; Sobczak, K; Soler, F J P; Solomin, A; Soomro, F; Souza De Paula, B; Spaan, B; Sparkes, A; Spradlin, P; Stagni, F; Stahl, S; Steinkamp, O; Stoica, S; Stone, S; Storaci, B; Straticiuc, M; Straumann, U; Styles, N; Subbiah, V K; Swientek, S; Szczekowski, M; Szczypka, P; Szumlak, T; T'Jampens, S; Teodorescu, E; Teubert, F; Thomas, C; Thomas, E; van Tilburg, J; Tisserand, V; Tobin, M; Topp-Joergensen, S; Tran, M T; Tsaregorodtsev, A; Tuning, N; Ubeda Garcia, M; Ukleja, A; Urquijo, P; Uwer, U; Vagnoni, V; Valenti, G; Vazquez Gomez, R; Vazquez Regueiro, P; Vecchi, S; Velthuis, J J; Veltri, M; Vervink, K; Viaud, B; Videau, I; Vilasis-Cardona, X; Visniakov, J; Vollhardt, A; Voong, D; Vorobyev, A; Voss, H; Wacker, K; Wandernoth, S; Wang, J; Ward, D R; Webber, A D; Websdale, D; Whitehead, M; Wiedner, D; Wiggers, L; Wilkinson, G; Williams, M P; Williams, M; Wilson, F F; Wishahi, J; Witek, M; Witzeling, W; Wotton, S A; Wyllie, K; Xie, Y; Xing, F; Yang, Z; Young, R; Yushchenko, O; Zavertyaev, M; Zhang, F; Zhang, L; Zhang, W C; Zhang, Y; Zhelezov, A; Zhong, L; Zverev, E; Zvyagin, A

2012-01-01

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic ``van der Meer scan'' method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5\\% in the absolute lumi...

Low energy electron microscopy imaging using Medipix2 detector

International Nuclear Information System (INIS)

Sikharulidze, I.; Gastel, R. van; Schramm, S.; Abrahams, J.P.; Poelsema, B.; Tromp, R.M.; Molen, S.J. van der

2011-01-01

Low Energy Electron Microscopy (LEEM) and Photo-Emission Electron Microscopy (PEEM) predominantly use a combination of microchannel plate (MCP), phosphor screen and optical camera to record images formed by 10-20 keV electrons. We have tested the performance of a LEEM/PEEM instrument with a Medipix2 hybrid pixel detector using an Ir(1 1 1) sample with graphene flakes grown on its surface. We find that Medipix2 offers a number of advantages over the MCP. The adjustable threshold settings allow Medipix2 to operate as a noiseless detector, offering an improved signal-to-noise ratio for the same amount of signal compared to the MCP. At the same magnification Medipix2 images exhibit superior resolution and can handle significantly higher electron current densities than an MCP, offering the prospect of substantially higher frame rates in LEEM imaging. These factors make Medipix2 an excellent candidate to become the detector of choice for LEEM/PEEM applications.

Low energy electron microscopy imaging using Medipix2 detector

Energy Technology Data Exchange (ETDEWEB)

Sikharulidze, I., E-mail: irakli@chem.leidenuniv.nl [Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300RA Leiden (Netherlands); Gastel, R. van [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Schramm, S. [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands); Abrahams, J.P. [Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300RA Leiden (Netherlands); Poelsema, B. [MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500AE Enschede (Netherlands); Tromp, R.M. [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands); IBM Research Division, T. J. Watson Research Center, P.O. Box 218, Yorktown Heights, NY 10598 (United States); Molen, S.J. van der [Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300RA Leiden (Netherlands)

2011-05-15

Low Energy Electron Microscopy (LEEM) and Photo-Emission Electron Microscopy (PEEM) predominantly use a combination of microchannel plate (MCP), phosphor screen and optical camera to record images formed by 10-20 keV electrons. We have tested the performance of a LEEM/PEEM instrument with a Medipix2 hybrid pixel detector using an Ir(1 1 1) sample with graphene flakes grown on its surface. We find that Medipix2 offers a number of advantages over the MCP. The adjustable threshold settings allow Medipix2 to operate as a noiseless detector, offering an improved signal-to-noise ratio for the same amount of signal compared to the MCP. At the same magnification Medipix2 images exhibit superior resolution and can handle significantly higher electron current densities than an MCP, offering the prospect of substantially higher frame rates in LEEM imaging. These factors make Medipix2 an excellent candidate to become the detector of choice for LEEM/PEEM applications.

Tracking brachytherapy sources using emission imaging with one flat panel detector

International Nuclear Information System (INIS)

Song Haijun; Bowsher, James; Das, Shiva; Yin Fangfang

2009-01-01

This work proposes to use the radiation from brachytherapy sources to track their dwell positions in three-dimensional (3D) space. The prototype device uses a single flat panel detector and a BB tray. The BBs are arranged in a defined pattern. The shadow of the BBs on the flat panel is analyzed to derive the 3D coordinates of the illumination source, i.e., the dwell position of the brachytherapy source. A kilovoltage x-ray source located 3.3 m away was used to align the center BB with the center pixel on the flat panel detector. For a test plan of 11 dwell positions, with an Ir-192 high dose rate unit, one projection was taken for each dwell point, and locations of the BB shadows were manually identified on the projection images. The 3D coordinates for the 11 dwell positions were reconstructed based on two BBs. The distances between dwell points were compared with the expected values. The average difference was 0.07 cm with a standard deviation of 0.15 cm. With automated BB shadow recognition in the future, this technique possesses the potential of tracking the 3D trajectory and the dwell times of a brachytherapy source in real time, enabling real time source position verification.

A combined time-of-flight and depth-of-interaction detector for total-body positron emission tomography

Energy Technology Data Exchange (ETDEWEB)

Berg, Eric, E-mail: eberg@ucdavis.edu; Roncali, Emilie; Du, Junwei; Cherry, Simon R. [Department of Biomedical Engineering, University of California, Davis, One Shields Avenue, Davis, California 95616 (United States); Kapusta, Maciej [Molecular Imaging, Siemens Healthcare, Knoxville, Tennessee 37932 (United States)

2016-02-15

Purpose: In support of a project to build a total-body PET scanner with an axial field-of-view of 2 m, the authors are developing simple, cost-effective block detectors with combined time-of-flight (TOF) and depth-of-interaction (DOI) capabilities. Methods: This work focuses on investigating the potential of phosphor-coated crystals with conventional PMT-based block detector readout to provide DOI information while preserving timing resolution. The authors explored a variety of phosphor-coating configurations with single crystals and crystal arrays. Several pulse shape discrimination techniques were investigated, including decay time, delayed charge integration (DCI), and average signal shapes. Results: Pulse shape discrimination based on DCI provided the lowest DOI positioning error: 2 mm DOI positioning error was obtained with single phosphor-coated crystals while 3–3.5 mm DOI error was measured with the block detector module. Minimal timing resolution degradation was observed with single phosphor-coated crystals compared to uncoated crystals, and a timing resolution of 442 ps was obtained with phosphor-coated crystals in the block detector compared to 404 ps without phosphor coating. Flood maps showed a slight degradation in crystal resolvability with phosphor-coated crystals; however, all crystals could be resolved. Energy resolution was degraded by 3%–7% with phosphor-coated crystals compared to uncoated crystals. Conclusions: These results demonstrate the feasibility of obtaining TOF–DOI capabilities with simple block detector readout using phosphor-coated crystals.

A combined time-of-flight and depth-of-interaction detector for total-body positron emission tomography

International Nuclear Information System (INIS)

Berg, Eric; Roncali, Emilie; Du, Junwei; Cherry, Simon R.; Kapusta, Maciej

2016-01-01

Purpose: In support of a project to build a total-body PET scanner with an axial field-of-view of 2 m, the authors are developing simple, cost-effective block detectors with combined time-of-flight (TOF) and depth-of-interaction (DOI) capabilities. Methods: This work focuses on investigating the potential of phosphor-coated crystals with conventional PMT-based block detector readout to provide DOI information while preserving timing resolution. The authors explored a variety of phosphor-coating configurations with single crystals and crystal arrays. Several pulse shape discrimination techniques were investigated, including decay time, delayed charge integration (DCI), and average signal shapes. Results: Pulse shape discrimination based on DCI provided the lowest DOI positioning error: 2 mm DOI positioning error was obtained with single phosphor-coated crystals while 3–3.5 mm DOI error was measured with the block detector module. Minimal timing resolution degradation was observed with single phosphor-coated crystals compared to uncoated crystals, and a timing resolution of 442 ps was obtained with phosphor-coated crystals in the block detector compared to 404 ps without phosphor coating. Flood maps showed a slight degradation in crystal resolvability with phosphor-coated crystals; however, all crystals could be resolved. Energy resolution was degraded by 3%–7% with phosphor-coated crystals compared to uncoated crystals. Conclusions: These results demonstrate the feasibility of obtaining TOF–DOI capabilities with simple block detector readout using phosphor-coated crystals

Prosthetic replacement for proximal humeral fractures.

Science.gov (United States)

Kontakis, George; Tosounidis, Theodoros; Galanakis, Ioannis; Megas, Panagiotis

2008-12-01

The ideal management of complex proximal humeral fractures continues to be debatable. Evolution of proximal humeral fracture management, during the past decade, led to the implementation of many innovations in surgical treatment. Even though the pendulum of treatment seems to swing towards new trends such as locked plating, hemiarthroplasty remains a valid and reliable option that serves the patient's needs well. Hemiarthroplasty is indicated for complex proximal humeral fractures in elderly patients with poor bone stock and when internal fixation is difficult or unreliable. Hemiarthroplasty provides a better result when it is performed early post-injury. Stem height, retroversion and tuberosity positioning are technical aspects of utmost importance. Additionally reverse total shoulder arthroplasty is an alternative new modality that can be used as a primary solution in selected patients with proximal humeral fracture treatment. Failed hemiarthroplasty and fracture sequelae can be successfully managed with reverse total shoulder arthroplasty. Individual decision-making and tailored treatment that takes into consideration the personality of the fracture and the patient's characteristics should be used.

Comparison of rectangular and dual-planar positron emission mammography scanners

International Nuclear Information System (INIS)

Qi, Jinyi; Kuo, Chaincy; Huesman, Ronald H.; Klein, Gregory J.; Moses, William W.; Reutter, Bryan W.

2002-01-01

Breast imaging using dedicated positron emission tomography (PEM) has gained much interest in the medical imaging field. In this paper, we compare the performance between a rectangular geometry and a parallel dual-planar geometry. Both geometries are studied with depth of interaction (DOI) detectors and non- DOI detectors. We compare the Fisher-information matrix, lesion detection, and quantitation of the four systems. The lesion detectability is measured by the signal-to-noise ratio (SNR) of a prewhitening numerical observer for detecting a known hot spot on a uniform background. Results show that the rectangular system with DOI has the highest SNR for the detection task and the lowest bias at any given noise level for the quantitation task. They also show that for small simulated lesions the parallel dual-planar system with DOI detectors outperforms the rectangular system with non-DOI detectors, while the rectangular system with non-DOI detectors can outperform the parallel dual-planar system with DOI detectors for large simulated lesions

Fast rise time IR detectors for lepton colliders

International Nuclear Information System (INIS)

Drago, A.; Bini, S.; Guidi, M. Cestelli; Marcelli, A.; Pace, E.

2016-01-01

Diagnostics is a fundamental issue for accelerators whose demands are continuously increasing. In particular bunch-by-bunch diagnostics is a key challenge for the latest generation of lepton colliders and storage rings. The Frascati Φ-factory, DAΦNE, colliding at 1.02 GeV in the centre of mass, hosts in the main rings few synchrotron radiation beamlines and two of them collect the synchrotron radiation infrared emission: SINBAD from the electron ring and 3+L from the positron ring. At DAΦNE each bucket is 2.7 ns long and particles are gathered in bunches emitting pulsed IR radiation, whose intensity in the long wavelength regime is directly proportional to the accumulated particles. Compact uncooled photoconductive HgCdTe detectors have been tested in both beamlines using dedicated optical layouts. Actually, the fast rise time of HgCdTe semiconductors give us the chance to test bunch-by-bunch devices for both longitudinal and transverse diagnostics. For the longitudinal case, single pixel detectors have been used, while for the transverse diagnostics, multi-pixel array detectors, with special custom design, are under test. This contribution will briefly describe the status of the research on fast IR detectors at DAΦNE, the results obtained and possible foreseen developments.

Industrial Computed Tomography using Proximal Algorithm

KAUST Repository

Zang, Guangming

2016-04-14

In this thesis, we present ProxiSART, a flexible proximal framework for robust 3D cone beam tomographic reconstruction based on the Simultaneous Algebraic Reconstruction Technique (SART). We derive the proximal operator for the SART algorithm and use it for minimizing the data term in a proximal algorithm. We show the flexibility of the framework by plugging in different powerful regularizers, and show its robustness in achieving better reconstruction results in the presence of noise and using fewer projections. We compare our framework to state-of-the-art methods and existing popular software tomography reconstruction packages, on both synthetic and real datasets, and show superior reconstruction quality, especially from noisy data and a small number of projections.

CdZnTe detectors for gamma-ray Burst ArcSecond Imaging and Spectroscopy (BASIS)

International Nuclear Information System (INIS)

Stahle, C.M.; Palmer, D.; Bartlett, L.M.; Parsons, A.; Shi Zhiqing; Lisse, C.M.; Sappington, C.; Cao, N.; Shu, P.; Gehrels, N.; Teegarden, B.; Birsa, F.; Singh, S.; Odom, J.; Hanchak, C.; Tueller, J.; Barthelmy, S.; Krizmanic, J.; Barbier, L.

1996-01-01

A CdZnTe detector array is being developed for the proposed gamma-ray Burst ArcSecond Imaging and Spectroscopy (BASIS) spaceflight mission to accurately locate gamma-ray bursts, determine their distance scale, and measure the physical characteristics of the emission region. Two-dimensional strip detectors with 100 μm pitch have been fabricated and wire bonded to readout electronics to demonstrate the ability to localize 60 and 122 keV gamma-rays to less than 100 μm. Radiation damage studies on a CdZnTe detector exposed to MeV neutrons showed a small amount of activation but no detector performance degradation for fluences up to 10 10 neutrons/cm 2 . A 1 x 1 in. CdZnTe detector has also been flown on a balloon payload at 115 000 ft in order to measure the CdZnTe background rates. (orig.)

Study of method of efficiency transference using detectors NaI(Ti)

International Nuclear Information System (INIS)

Ramos, Thiago L.; Salgado, César M.

2017-01-01

The use of NaI (Tl) scintillation detectors for measurements implies the determination of the detection efficiency as a function of the energy of the incident photons. The efficiency curve can be obtained experimentally with the use of several mono-energy sources calibrated with emission energies covering the whole range of interest or using the Monte Carlo method. The Institute of Nuclear Engineering develops several methodologies using these detectors as they are robust, inexpensive and do not need cooling for their use. The assembly of an experimental arrangement is usually complex, since several factors influence the result affecting reproducibility in measurements, such as: parallelism between source and detector, alignment between source and detector, and accuracy of source-detector distance. In view of such difficulties, an automated positioning system was developed for the source-detector set controlled by a micro controller based on the ARDUINO language in order to guarantee the reproducibility in the experimental arrangements. In the initial phase of this study, a mathematical model was developed in the MCNP-X code using a NaI (Tl) detector. A theoretical validation using the Efficiency Transfer Method was performed at three different positions on the detector's axial axis (10.6 cm, 11.3 cm and 12.0 cm). This method is based on the ratio of effective solid angles. The experimental validation presented maximum relative errors of 7.74% for the position 11.3 cm

A Very High Spatial Resolution Detector for Small Animal PET

International Nuclear Information System (INIS)

Kanai Shah, M.S.

2007-01-01

Positron Emission Tomography (PET) is an in vivo analog of autoradiography and has the potential to become a powerful new tool in imaging biological processes in small laboratory animals. PET imaging of small animals can provide unique information that can help in advancement of human disease models as well as drug development. Clinical PET scanners used for human imaging are bulky, expensive and do not have adequate spatial resolution for small animal studies. Hence, dedicated, low cost instruments are required for conducting small animal studies with higher spatial resolution than what is currently achieved with clinical as well as dedicated small animal PET scanners. The goal of the proposed project is to investigate a new all solid-state detector design for small animal PET imaging. Exceptionally high spatial resolution, good timing resolution, and excellent energy resolution are expected from the proposed detector design. The Phase I project was aimed at demonstrating the feasibility of producing high performance solid-state detectors that provide high sensitivity, spatial resolution, and timing characteristics. Energy resolution characteristics of the new detector were also investigated. The goal of the Phase II project is to advance the promising solid-state detector technology for small animal PET and determine its full potential. Detectors modules will be built and characterized and finally, a bench-top small animal PET system will be assembled and evaluated

An investigation of the performance of a coaxial HPGe detector operating in a magnetic resonance imaging field

Energy Technology Data Exchange (ETDEWEB)

Harkness, L.J., E-mail: ljh@ns.ph.liv.ac.u [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Boston, A.J.; Boston, H.C.; Cole, P.; Cresswell, J.R.; Filmer, F.; Jones, M.; Judson, D.S.; Nolan, P.J.; Oxley, D.C.; Sampson, J.A.; Scraggs, D.P.; Slee, M.J. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom); Bimson, W.E.; Kemp, G.J. [MARIARC, University of Liverpool, Liverpool L69 3GE (United Kingdom); Groves, J.; Headspith, J.; Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom); Cooper, R.J. [Joint Institute for Heavy Ion Research, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6371 (United States)

2011-05-11

Nuclear medical imaging modalities such as positron emission tomography and single photon emission computed tomography are used to probe physiological functions of the body by detecting gamma rays emitted from biologically targeted radiopharmaceuticals. A system which is capable of simultaneous data acquisition for nuclear medical imaging and magnetic resonance imaging is highly sought after by the medical imaging community. Such a device could provide a more complete medical insight into the functions of the body within a well-defined structural context. However, acquiring simultaneous nuclear/MRI sequences are technically challenging due to the conventional photomultiplier tube readout employed by most existing scintillator detector systems. A promising solution is a nuclear imaging device composed of semiconductor detectors that can be operated with a standard MRI scanner. However, the influence of placing a semiconductor detector such as high purity germanium (HPGe) within or close to the bore of an MRI scanner, where high magnetic fields are present, is not well understood. In this paper, the performance of a HPGe detector operating in a high strength static (B{sub S}) MRI field along with fast switching gradient fields and radiofrequency from the MRI system has been assessed. The influence of the B{sub S} field on the energy resolution of the detector has been investigated for various positions and orientations of the detector within the magnetic field. The results have then been interpreted in terms of the influence of the B{sub S} field on the charge collection properties. MRI images have been acquired with the detector situated at the entrance of the MRI bore to investigate the effects of simultaneous data acquisition on detector performance and MRI imaging.

A statistical analysis of count normalization methods used in positron-emission tomography

International Nuclear Information System (INIS)

Holmes, T.J.; Ficke, D.C.; Snyder, D.L.

1984-01-01

As part of the Positron-Emission Tomography (PET) reconstruction process, annihilation counts are normalized for photon absorption, detector efficiency and detector-pair duty-cycle. Several normalization methods of time-of-flight and conventional systems are analyzed mathematically for count bias and variance. The results of the study have some implications on hardware and software complexity and on image noise and distortion

Time-resolved triton burnup measurement using the scintillating fiber detector in the Large Helical Device

Science.gov (United States)

Ogawa, K.; Isobe, M.; Nishitani, T.; Murakami, S.; Seki, R.; Nakata, M.; Takada, E.; Kawase, H.; Pu, N.; LHD Experiment Group

2018-03-01

Time-resolved measurement of triton burnup is performed with a scintillating fiber detector system in the deuterium operation of the large helical device. The scintillating fiber detector system is composed of the detector head consisting of 109 scintillating fibers having a diameter of 1 mm and a length of 100 mm embedded in the aluminum substrate, the magnetic registrant photomultiplier tube, and the data acquisition system equipped with 1 GHz sampling rate analogies to digital converter and the field programmable gate array. The discrimination level of 150 mV was set to extract the pulse signal induced by 14 MeV neutrons according to the pulse height spectra obtained in the experiment. The decay time of 14 MeV neutron emission rate after neutral beam is turned off measured by the scintillating fiber detector. The decay time is consistent with the decay time of total neutron emission rate corresponding to the 14 MeV neutrons measured by the neutron flux monitor as expected. Evaluation of the diffusion coefficient is conducted using a simple classical slowing-down model FBURN code. It is found that the diffusion coefficient of triton is evaluated to be less than 0.2 m2 s-1.

The Road to the Common PET/CT Detector

Science.gov (United States)

Nassalski, Antoni; Moszynski, Marek; Szczesniak, Tomasz; Wolski, Dariusz; Batsch, Tadeusz

2007-10-01

Growing interest in the development of dual modality positron emission/X-rays tomography (PET/CT) systems prompts researchers to face a new challenge: to acquire both the anatomical and functional information in the same measurement, simultaneously using the same detection system and electronics. The aim of this work was to study a detector consisting of LaBr3, LSO or LYSO pixel crystals coupled to an avalanche photodiode (APD). The measurements covered tests of the detectors in PET and CT modes, respectively. The measurements included the determination of light output, energy resolution, the non-proportionality of the light yield and the time resolution for 511 keV annihilation quanta; analysis also included characterizing the PET detector, and determining the dependence of counting rate versus mean current of the APD in the X-ray detection. In the present experiment, the use of counting and current modes in the CT detection increases the dynamic range of the measured dose of X-rays by a factor of 20, compared to the counting mode alone.

Peak reading detector circuit

International Nuclear Information System (INIS)

Courtin, E.; Grund, K.; Traub, S.; Zeeb, H.

1975-01-01

The peak reading detector circuit serves for picking up the instants during which peaks of a given polarity occur in sequences of signals in which the extreme values, their time intervals, and the curve shape of the signals vary. The signal sequences appear in measuring the foetal heart beat frequence from amplitude-modulated ultrasonic, electrocardiagram, and blood pressure signals. In order to prevent undesired emission of output signals from, e. g., disturbing intermediate extreme values, the circuit consists of the series connections of a circuit to simulate an ideal diode, a strong unit, a discriminator for the direction of charging current, a time-delay circuit, and an electronic switch lying in the decharging circuit of the storage unit. The time-delay circuit thereby causes storing of a preliminary maximum value being used only after a certain time delay for the emission of the output signal. If a larger extreme value occurs during the delay time the preliminary maximum value is cleared and the delay time starts running anew. (DG/PB) [de

Mini-lidar sensor for the remote stand-off sensing of chemical/biological substances and method for sensing same

Science.gov (United States)

Ray, Mark D.; Sedlacek, Arthur J.

2003-08-19

A method and apparatus for remote, stand-off, and high efficiency spectroscopic detection of biological and chemical substances. The apparatus including an optical beam transmitter which transmits a beam having an axis of transmission to a target, the beam comprising at least a laser emission. An optical detector having an optical detection path to the target is provided for gathering optical information. The optical detection path has an axis of optical detection. A beam alignment device fixes the transmitter proximal to the detector and directs the beam to the target along the optical detection path such that the axis of transmission is within the optical detection path. Optical information gathered by the optical detector is analyzed by an analyzer which is operatively connected to the detector.

Study of method of efficiency transference using detectors NaI(Ti); Estudo de método de transferência de eficiência usando detectores NaI(Tl)

Energy Technology Data Exchange (ETDEWEB)

Ramos, Thiago L.; Salgado, César M., E-mail: thiago_lins-ramos@hotmail.com, E-mail: otero@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2017-07-01

The use of NaI (Tl) scintillation detectors for measurements implies the determination of the detection efficiency as a function of the energy of the incident photons. The efficiency curve can be obtained experimentally with the use of several mono-energy sources calibrated with emission energies covering the whole range of interest or using the Monte Carlo method. The Institute of Nuclear Engineering develops several methodologies using these detectors as they are robust, inexpensive and do not need cooling for their use. The assembly of an experimental arrangement is usually complex, since several factors influence the result affecting reproducibility in measurements, such as: parallelism between source and detector, alignment between source and detector, and accuracy of source-detector distance. In view of such difficulties, an automated positioning system was developed for the source-detector set controlled by a micro controller based on the ARDUINO language in order to guarantee the reproducibility in the experimental arrangements. In the initial phase of this study, a mathematical model was developed in the MCNP-X code using a NaI (Tl) detector. A theoretical validation using the Efficiency Transfer Method was performed at three different positions on the detector's axial axis (10.6 cm, 11.3 cm and 12.0 cm). This method is based on the ratio of effective solid angles. The experimental validation presented maximum relative errors of 7.74% for the position 11.3 cm.

Proximity sensor system development. CRADA final report

Energy Technology Data Exchange (ETDEWEB)

Haley, D.C. [Oak Ridge National Lab., TN (United States); Pigoski, T.M. [Merrit Systems, Inc. (United States)

1998-01-01

Lockheed Martin Energy Research Corporation (LMERC) and Merritt Systems, Inc. (MSI) entered into a Cooperative Research and Development Agreement (CRADA) for the development and demonstration of a compact, modular proximity sensing system suitable for application to a wide class of manipulator systems operated in support of environmental restoration and waste management activities. In teleoperated modes, proximity sensing provides the manipulator operator continuous information regarding the proximity of the manipulator to objects in the workspace. In teleoperated and robotic modes, proximity sensing provides added safety through the implementation of active whole arm collision avoidance capabilities. Oak Ridge National Laboratory (ORNL), managed by LMERC for the United States Department of Energy (DOE), has developed an application specific integrated circuit (ASIC) design for the electronics required to support a modular whole arm proximity sensing system based on the use of capacitive sensors developed at Sandia National Laboratories. The use of ASIC technology greatly reduces the size of the electronics required to support the selected sensor types allowing deployment of many small sensor nodes over a large area of the manipulator surface to provide maximum sensor coverage. The ASIC design also provides a communication interface to support sensor commands from and sensor data transmission to a distributed processing system which allows modular implementation and operation of the sensor system. MSI is a commercial small business specializing in proximity sensing systems based upon infrared and acoustic sensors.

Proximity sensor system development. CRADA final report

International Nuclear Information System (INIS)

Haley, D.C.; Pigoski, T.M.

1998-01-01

Lockheed Martin Energy Research Corporation (LMERC) and Merritt Systems, Inc. (MSI) entered into a Cooperative Research and Development Agreement (CRADA) for the development and demonstration of a compact, modular proximity sensing system suitable for application to a wide class of manipulator systems operated in support of environmental restoration and waste management activities. In teleoperated modes, proximity sensing provides the manipulator operator continuous information regarding the proximity of the manipulator to objects in the workspace. In teleoperated and robotic modes, proximity sensing provides added safety through the implementation of active whole arm collision avoidance capabilities. Oak Ridge National Laboratory (ORNL), managed by LMERC for the United States Department of Energy (DOE), has developed an application specific integrated circuit (ASIC) design for the electronics required to support a modular whole arm proximity sensing system based on the use of capacitive sensors developed at Sandia National Laboratories. The use of ASIC technology greatly reduces the size of the electronics required to support the selected sensor types allowing deployment of many small sensor nodes over a large area of the manipulator surface to provide maximum sensor coverage. The ASIC design also provides a communication interface to support sensor commands from and sensor data transmission to a distributed processing system which allows modular implementation and operation of the sensor system. MSI is a commercial small business specializing in proximity sensing systems based upon infrared and acoustic sensors

Locking plate fixation for proximal humerus fractures.

LENUS (Irish Health Repository)

Burke, Neil G

2012-02-01

Locking plates are increasingly used to surgically treat proximal humerus fractures. Knowledge of the bone quality of the proximal humerus is important. Studies have shown the medial and dorsal aspects of the proximal humeral head to have the highest bone strength, and this should be exploited by fixation techniques, particularly in elderly patients with osteoporosis. The goals of surgery for proximal humeral fractures should involve minimal soft tissue dissection and achieve anatomic reduction of the head complex with sufficient stability to allow for early shoulder mobilization. This article reviews various treatment options, in particular locking plate fixation. Locking plate fixation is associated with a high complication rate, such as avascular necrosis (7.9%), screw cutout (11.6%), and revision surgery (13.7%). These complications are frequently due to the varus deformation of the humeral head. Strategic screw placement in the humeral head would minimize the possibility of loss of fracture reduction and potential hardware complications. Locking plate fixation is a good surgical option for the management of proximal humerus fractures. Complications can be avoided by using better bone stock and by careful screw placement in the humeral head.

Detectors for proton counting. Si-APD and scintillation detectors

International Nuclear Information System (INIS)

Kishimoto, Shunji

2008-01-01

Increased intensity of synchrotron radiation requests users to prepare photon pulse detectors having higher counting rates. As detectors for photon counting, silicon-avalanche photodiode (Si-APD) and scintillation detectors were chosen for the fifth series of detectors. Principle of photon detection by pulse and need of amplification function of the detector were described. Structure and working principle, high counting rate measurement system, bunch of electrons vs. counting rate, application example of NMR time spectroscopy measurement and comments for users were described for the Si-APD detector. Structure of scintillator and photomultiplier tube, characteristics of scintillator and performance of detector were shown for the NaI detector. Future development of photon pulse detectors was discussed. (T. Tanaka)

Evaluation of signal energy calculation methods for a light-sharing SiPM-based PET detector

Energy Technology Data Exchange (ETDEWEB)

Wei, Qingyang [School of Automation and Electrical Engineering, University of Science & Technology Beijing, Beijing 100083 (China); Beijing Engineering Research Center of Industrial Spectrum Imaging, University of Science and Technology Beijing, Beijing 100083 (China); Ma, Tianyu; Xu, Tianpeng; Liu, Yaqiang; Wang, Shi [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Gu, Yu, E-mail: guyu@ustb.edu.cn [School of Automation and Electrical Engineering, University of Science & Technology Beijing, Beijing 100083 (China)

2017-03-11

Signals of a light-sharing positron emission tomography (PET) detector are commonly multiplexed to three analog pulses (E, X, and Y) and then digitally sampled. From this procedure, the signal energy that are critical to detector performance are obtained. In this paper, different signal energy calculation strategies for a self-developed SiPM-based PET detector, including pulse height and different integration methods, are evaluated in terms of energy resolution and spread of the crystal response in the flood histogram using a root-mean-squared (RMS) index. Results show that integrations outperform the pulse height. Integration using the maximum derivative value of the pulse E as the landmark point and 28 integrated points (448 ns) has the best performance in these evaluated methods for our detector. Detector performance in terms of energy and position is improved with this integration method. The proposed methodology is expected to be applicable for other light-sharing PET detectors.

Proximal collagenous gastroenteritides:

DEFF Research Database (Denmark)

Nielsen, Ole Haagen; Riis, Lene Buhl; Danese, Silvio

2014-01-01

AIM: While collagenous colitis represents the most common form of the collagenous gastroenteritides, the collagenous entities affecting the proximal part of the gastrointestinal tract are much less recognized and possibly overlooked. The aim was to summarize the latest information through a syste...

Promoting proximal formative assessment with relational discourse

Science.gov (United States)

Scherr, Rachel E.; Close, Hunter G.; McKagan, Sarah B.

2012-02-01

The practice of proximal formative assessment - the continual, responsive attention to students' developing understanding as it is expressed in real time - depends on students' sharing their ideas with instructors and on teachers' attending to them. Rogerian psychology presents an account of the conditions under which proximal formative assessment may be promoted or inhibited: (1) Normal classroom conditions, characterized by evaluation and attention to learning targets, may present threats to students' sense of their own competence and value, causing them to conceal their ideas and reducing the potential for proximal formative assessment. (2) In contrast, discourse patterns characterized by positive anticipation and attention to learner ideas increase the potential for proximal formative assessment and promote self-directed learning. We present an analysis methodology based on these principles and demonstrate its utility for understanding episodes of university physics instruction.

Psychological responses to the proximity of climate change

Science.gov (United States)

Brügger, Adrian; Dessai, Suraje; Devine-Wright, Patrick; Morton, Thomas A.; Pidgeon, Nicholas F.

2015-12-01

A frequent suggestion to increase individuals' willingness to take action on climate change and to support relevant policies is to highlight its proximal consequences, that is, those that are close in space and time. But previous studies that have tested this proximizing approach have not revealed the expected positive effects on individual action and support for addressing climate change. We present three lines of psychological reasoning that provide compelling arguments as to why highlighting proximal impacts of climate change might not be as effective a way to increase individual mitigation and adaptation efforts as is often assumed. Our contextualization of the proximizing approach within established psychological research suggests that, depending on the particular theoretical perspective one takes on this issue, and on specific individual characteristics suggested by these perspectives, proximizing can bring about the intended positive effects, can have no (visible) effect or can even backfire. Thus, the effects of proximizing are much more complex than is commonly assumed. Revealing this complexity contributes to a refined theoretical understanding of the role that psychological distance plays in the context of climate change and opens up further avenues for future research and for interventions.

Critical Proximity as a Methodological Move in Techno-Anthropology

DEFF Research Database (Denmark)

Birkbak, Andreas; Petersen, Morten Krogh; Elgaard Jensen, Torben

2015-01-01

proximity.’ Critical proximity offers an alternative to critical distance, especially with respect to avoiding premature references to abstract panoramas such as democratization and capitalist exploitation in the quest to conduct ‘critical’ analysis. Critical proximity implies, instead, granting the beings...

Detector technology challenges for nuclear medicine and PET

International Nuclear Information System (INIS)

Marsden, P.K.

2003-01-01

The challenges facing the development of new detector technology for single photon imaging and positron emission tomography (PET) are considered. There is currently great interest in functional imaging with radionuclides, particularly PET, triggered by new clinical applications and developments in molecular and cell biology. Multi-modality systems that combine radionuclide imaging with CT present new challenges, as do very high resolution systems for imaging small animals. Whilst for PET there are some fairly well defined routes to improving performance, the basic design of single photon systems has remained unchanged for many years. This review outlines the challenges that must be addressed by detector physicists in order to obtain significant advances in performance, and indicates some of the approaches currently being adopted. Emphasis is given to PET which is where the greatest opportunities appear to lie

Detection of secondary electrons with pixelated hybrid semiconductor detectors

International Nuclear Information System (INIS)

Gebert, Ulrike Sonja

2011-01-01

Within the scope of this thesis, secondary electrons were detected with a pixelated semiconductor detector named Timepix. The Timepix detector consists of electronics and a sensor made from a semiconductor material. The connection of sensor and electronics is done for each pixel individually using bump bonds. Electrons with energies above 3 keV can be detected with the sensor. One electron produces a certain amount of electron-hole pairs according to its energy. The charge then drifts along an electric field to the pixel electronics, where it induces an electric signal. Even without a sensor it is possible to detect an electric signal from approximately 1000 electrons directly in the pixel electronics. Two different detector systems to detect secondary electrons using the Timepix detector were investigated during this thesis. First of all, a hybrid photon detector (HPD) was used to detect single photoelectrons. The HPD consists of a vacuum vessel with an entrance window and a cesium iodine photocathode at the inner surface of the window. Photoelectrons are released from the photocathode by incident light and are accelerated in an electric field towards the Timepix detector, where the point of interaction and the arrival time of the electron is determined. With a proximity focusing setup, a time resolution of 12 ns (with an acceleration voltage of 20 kV between photocathode and Timepix detector) was obtained. The HPD examined in this thesis showed a strong dependence of the dark rate form the acceleration voltage and the pressure in the vacuum vessel. At a pressure of few 10 -5 mbar and an acceleration voltage of 20 kV, the dark rate was about 800 Hz per mm 2 area of the read out photocathode. One possibility to reduce the dark rate is to identify ion feedback events. With a slightly modified setup it was possible to reduce the dark rate to 0.5 Hz/mm 2 . To achieve this, a new photocathode was mounted in a shorter distance to the detector. The measurements where

Temperature dependence of fluorescence decay time and emission spectrum of bismuth germanate

International Nuclear Information System (INIS)

Melcher, C.L.; Liberman, A.; Schweitzer, J.S.; Simonetti, J.

1985-01-01

Bismuth germanate has become an increasingly popular replacement for NaI(Tl) scintillators in recent years, mainly due to its higher detection efficiency. However, its scintillation efficiency and fluorescence decay time are strongly temperature dependent. Optimum performance of detector systems which employ BGO crystals depends on knowledge of the BGO pulse shape and intensity and its emission spectrum at the operating temperature of the detector. Measurements of these quantities are presented over the temperature range -47 0 C to +111 0 C. Although the emission spectrum shifts only slightly over this temperature range, the scintillation efficiency and fluorescence decay time are strongly temperature dependent. In addition to the usefulness of these data for optimizing detector design, the results imply that luminescence quenching in BGO cannot be characterized by a single thermal activation to a radiationless transition but that a more complex model is required to characterize the light output from BGO crystals

Impact of the layout of the ITER Radial Neutron Camera in-port system on the measurement of the neutron emissivity profile

International Nuclear Information System (INIS)

Marocco, D.; Moro, F.; Esposito, B.; Brolatti, G.; Villari, R.; Salasca, S.; Cantone, B.

2013-01-01

Highlights: ► MCNP ITER model ‘Alite-4′ has been updated with the new Port Plug structure (three vertical drawers). ► Two different layouts for the Radial Neutron Camera (RNC) in-vessel system have been considered. ► The impact of both layouts on the RNC diagnostic performance has been assessed. ► The analysis provides useful information for a proper integration of the RNC in the EPP1. -- Abstract: The Radial Neutron Camera (RNC), located in the ITER Equatorial Port Plug 1 (EPP1), is designed to provide the neutron emissivity profile through the measurement of the neutron flux along several collimated channels. The present design of the RNC is based on collimating structures: an ex-port system viewing the plasma core and an in-port system composed by two detector cassettes viewing the upper and lower plasma edges. A design of the EPP1 in which the diagnostics are installed in three completely independent vertical drawers is under study. In this frame, space optimization and integration issues suggest two possible solutions for the layout of the in-port RNC cassettes: the first one in which both cassettes are located in a side drawer; the second one in which the two cassettes lie in the central drawer, on opposite sides of the ex-port RNC cut-out. This paper describes the work performed to assess the impact of the two different in-port system layouts on the capability of the RNC to measure the neutron emissivity profile by means of MCNP and diagnostic performance calculations. The results of the analysis provide guidelines for the integration of the RNC into the EPP1 showing that the proximity of the in-port cassettes to the ex-port cut-out strongly increases the amount of uncollimated and scattered neutrons at the detector positions, thus reducing the diagnostic measurement capability

Infiltrating/sealing proximal caries lesions

DEFF Research Database (Denmark)

Martignon, S; Ekstrand, K R; Gomez, J

2012-01-01

This randomized split-mouth controlled clinical trial aimed at assessing the therapeutic effects of infiltration vs. sealing for controlling caries progression on proximal surfaces. Out of 90 adult students/patients assessed at university clinics and agreeing to participate, 39, each with 3...... differences in lesion progression between infiltration and placebo (P = 0.0012) and between sealing and placebo (P = 0.0269). The study showed that infiltration and sealing are significantly better than placebo treatment for controlling caries progression on proximal lesions. No significant difference...

A New Virtual Point Detector Concept for a HPGe detector

International Nuclear Information System (INIS)

Byun, Jong In; Yun, Ju Yong

2009-01-01

For last several decades, the radiation measurement and radioactivity analysis techniques using gamma detectors have been well established. Especially , the study about the detection efficiency has been done as an important part of gamma spectrometry. The detection efficiency depends strongly on source-to-detector distance. The detection efficiency with source-to-detector distance can be expressed by a complex function of geometry and physical characteristics of gamma detectors. In order to simplify the relation, a virtual point detector concept was introduced by Notea. Recently, further studies concerning the virtual point detector have been performed. In previous other works the virtual point detector has been considered as a fictitious point existing behind the detector end cap. However the virtual point detector position for the front and side of voluminous detectors might be different due to different effective central axis of them. In order to more accurately define the relation, therefore, we should consider the virtual point detector for the front as well as side and off-center of the detector. The aim of this study is to accurately define the relation between the detection efficiency and source-to-detector distance with the virtual point detector. This paper demonstrates the method to situate the virtual point detectors for a HPGe detector. The new virtual point detector concept was introduced for three area of the detector and its characteristics also were demonstrated by using Monte Carlo Simulation method. We found that the detector has three virtual point detectors except for its rear area. This shows that we should consider the virtual point detectors for each area when applying the concept to radiation measurement. This concept can be applied to the accurate geometric simplification for the detector and radioactive sources.

A twin Frisch-grid ionization chamber as a selective detector for the delayed gamma-spectroscopy of fission fragments

Energy Technology Data Exchange (ETDEWEB)

Gaudefroy, L., E-mail: laurent.gaudefroy@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Roger, T., E-mail: roger@ganil.fr [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Pancin, J., E-mail: pancin@ganil.fr [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Spitaels, C. [GANIL, CEA/DSM-CNRS/IN2P3, BP 55027, F-14076 Caen (France); Aupiais, J. [CEA, DAM, DIF, F-91297 Arpajon (France); Mottier, J. [Institut de Physique Nucléaire, Université Paris-Sud-11-CNRS-IN2P3, F-91406 Orsay (France)

2017-05-21

We present a twin Frisch-grid ionization chamber. The detector is meant to provide high selective power for the study of delayed gamma-ray spectroscopy of fission fragments produced via {sup 252}Cf spontaneous fission. A mean energy resolution on the kinetic energy of fission fragments of 675 keV (FWHM) is achieved and allows us to resolve masses of fragments for fission events where neutron emission is not energetically possible. The mean mass resolution measured for these particular events amounts to 0.54 mass units (FWHM). For fission events with neutron emission a resolution of 4 mass units (FWHM) is reported. Information on fragment emission angle is measured with a resolution of 0.1 on the difference of the cosines determined for both halves of the detector. A charge resolution of 4.5 charge units (FWHM) is also demonstrated.

Proximal femoral fractures

DEFF Research Database (Denmark)

Palm, Henrik; Teixidor, Jordi

2015-01-01

searched the homepages of the national heath authorities and national orthopedic societies in West Europe and found 11 national or regional (in case of no national) guidelines including any type of proximal femoral fracture surgery. RESULTS: Pathway consensus is outspread (internal fixation for un...

Design and Implementation of a Detector for High Flux Mixed Radiation Fields

CERN Document Server

Kramer, Daniel; Sulc, Miroslav

2008-01-01

The main purpose of the LHC Beam Loss Monitoring (BLM) system is the active protection of the LHC accelerators' elements against the quench of superconducting magnets and the damage of equipment caused by the loss of circulating protons. The lost protons initiate a shower of secondary particles, which deposit their energy in the equipment and partly in a radiation detector. If thresholds in the BLM system are exceeded, the circulating LHC beam is directed towards a dump to stop the energy deposition in the fragile equipment. The LHC BLM system will use ionization chambers as standard detectors, and in the areas with very high dose rates Secondary Emission Monitor (SEM) chambers will be employed to increase the dynamic range. The SEM is characterized by a high linearity and accuracy, low sensitivity, fast response and a good radiation tolerance. The emission of electrons from the surface layer of metals by the passage of charged particles is only measurable in a vacuum environment. This requirement leads toget...

Transmutation detectors

Energy Technology Data Exchange (ETDEWEB)

Viererbl, L., E-mail: vie@ujv.c [Research Centre Rez Ltd. (Czech Republic); Nuclear Research Institute Rez plc (Czech Republic); Lahodova, Z. [Research Centre Rez Ltd. (Czech Republic); Nuclear Research Institute Rez plc (Czech Republic); Klupak, V. [Nuclear Research Institute Rez plc (Czech Republic); Sus, F. [Research Centre Rez Ltd. (Czech Republic); Nuclear Research Institute Rez plc (Czech Republic); Kucera, J. [Research Centre Rez Ltd. (Czech Republic); Nuclear Physics Institute, Academy of Sciences of the Czech Republic (Czech Republic); Kus, P.; Marek, M. [Research Centre Rez Ltd. (Czech Republic); Nuclear Research Institute Rez plc (Czech Republic)

2011-03-11

We have designed a new type of detectors, called transmutation detectors, which can be used primarily for neutron fluence measurement. The transmutation detector method differs from the commonly used activation detector method in evaluation of detector response after irradiation. Instead of radionuclide activity measurement using radiometric methods, the concentration of stable non-gaseous nuclides generated by transmutation in the detector is measured using analytical methods like mass spectrometry. Prospective elements and nuclear reactions for transmutation detectors are listed and initial experimental results are given. The transmutation detector method could be used primarily for long-term measurement of neutron fluence in fission nuclear reactors, but in principle it could be used for any type of radiation that can cause transmutation of nuclides in detectors. This method could also be used for measurement in accelerators or fusion reactors.

Transmutation detectors

International Nuclear Information System (INIS)

Viererbl, L.; Lahodova, Z.; Klupak, V.; Sus, F.; Kucera, J.; Kus, P.; Marek, M.

2011-01-01

We have designed a new type of detectors, called transmutation detectors, which can be used primarily for neutron fluence measurement. The transmutation detector method differs from the commonly used activation detector method in evaluation of detector response after irradiation. Instead of radionuclide activity measurement using radiometric methods, the concentration of stable non-gaseous nuclides generated by transmutation in the detector is measured using analytical methods like mass spectrometry. Prospective elements and nuclear reactions for transmutation detectors are listed and initial experimental results are given. The transmutation detector method could be used primarily for long-term measurement of neutron fluence in fission nuclear reactors, but in principle it could be used for any type of radiation that can cause transmutation of nuclides in detectors. This method could also be used for measurement in accelerators or fusion reactors.

Gaining efficiency and resolution in soft X-ray emission spectrometers thanks to directly illuminated CCD detectors

International Nuclear Information System (INIS)

Dinardo, M.E.; Piazzalunga, A.; Braicovich, L.; Bisogni, V.; Dallera, C.; Giarda, K.; Marcon, M.; Tagliaferri, A.; Ghiringhelli, G.

2007-01-01

The back-illuminated charge coupled devices (CCD) are suitable for soft X-ray photon detection. Their nominal performances suggest that they can boost both efficiency and resolving power of X-ray spectrometers based on diffraction gratings and two-dimensional position sensitive detectors. We tested the performances of two commercially available CCDs, intended to replace a more traditional microchannel plate (MCP) detector. Our tests show that the devices have excellent performances in terms of dark current, response linearity, detection efficiency and spatial resolution. We observed that the CCDs have better efficiency (more than 10 times) and better resolution (∼3 times) than the MCP. Moreover we found an intrinsic limit for the spatial resolution, which is almost independent of the detector pixel size and is estimated around 25 μm

Cerium doped GSO scintillators and its application to position sensitive detectors

International Nuclear Information System (INIS)

Ishibashi, H.; Shimizu, K.; Susa, K.; Kubota, S.

1989-01-01

The dependence of the light output and the decay times of Ce doped Gd/sub 2/SiO/sub 5/ on Ce concentration is measured. By using the difference in decay times on Ce concentration for GSO(Ce), the combination of different concentration of GSO(Ce) scintillators is shown to be useful as position sensitive detectors. A Ce doped Gd/sub 2/SiO/sub 5/ (GSO(Ce)) single crystal is an excellent scintillator featuring, a large light output, a short decay time and a high absorption coefficient. Further investigation aimed at its implementation to scintillators has been carried out previously. An application of the GSO(Ce) scintillators to the gamma-ray detectors of positron emission computed tomography has also been shown. The authors have investigated the dependence of its scintillation properties on the Ce concentration and its application to position sensitive detectors

Asymmetric Data Acquisition System for an Endoscopic PET-US Detector

Science.gov (United States)

Zorraquino, Carlos; Bugalho, Ricardo; Rolo, Manuel; Silva, Jose C.; Vecklans, Viesturs; Silva, Rui; Ortigão, Catarina; Neves, Jorge A.; Tavernier, Stefaan; Guerra, Pedro; Santos, Andres; Varela, João

2016-02-01

According to current prognosis studies of pancreatic cancer, survival rate nowadays is still as low as 6% mainly due to late detections. Taking into account the location of the disease within the body and making use of the level of miniaturization in radiation detectors that can be achieved at the present time, EndoTOFPET-US collaboration aims at the development of a multimodal imaging technique for endoscopic pancreas exams that combines the benefits of high resolution metabolic information from time-of- flight (TOF) positron emission tomography (PET) with anatomical information from ultrasound (US). A system with such capabilities calls for an application-specific high-performance data acquisition system (DAQ) able to control and readout data from different detectors. The system is composed of two novel detectors: a PET head extension for a commercial US endoscope placed internally close to the region-of-interest (ROI) and a PET plate placed over the patient's abdomen in coincidence with the PET head. These two detectors will send asymmetric data streams that need to be handled by the DAQ system. The approach chosen to cope with these needs goes through the implementation of a DAQ capable of performing multi-level triggering and which is distributed across two different on-detector electronics and the off-detector electronics placed inside the reconstruction workstation. This manuscript provides an overview on the design of this innovative DAQ system and, based on results obtained by means of final prototypes of the two detectors and DAQ, we conclude that a distributed multi-level triggering DAQ system is suitable for endoscopic PET detectors and it shows potential for its application in different scenarios with asymmetric sources of data.

Proximity correction of high-dosed frame with PROXECCO

Science.gov (United States)

Eisenmann, Hans; Waas, Thomas; Hartmann, Hans

1994-05-01

Usefulness of electron beam lithography is strongly related to the efficiency and quality of methods used for proximity correction. This paper addresses the above issue by proposing an extension to the new proximity correction program PROXECCO. The combination of a framing step with PROXECCO produces a pattern with a very high edge accuracy and still allows usage of the fast correction procedure. Making a frame with a higher dose imitates a fine resolution correction where the coarse part is disregarded. So after handling the high resolution effect by means of framing, an additional coarse correction is still needed. Higher doses have a higher contribution to the proximity effect. This additional proximity effect is taken into account with the help of the multi-dose input of PROXECCO. The dose of the frame is variable, depending on the deposited energy coming from backscattering of the proximity. Simulation proves the very high edge accuracy of the applied method.

Photon detector composed of metal and semiconductor nanoparticles

International Nuclear Information System (INIS)

Takahashi, Atsuo; Minoura, Norihiko; Karube, Isao

2005-01-01

Applying the function of the single electron transistor, a novel photon detector consisting of a self-assembled structure of metal and semiconductor nanoparticles and an organic insulating layer was developed. It showed coulomb blockade behavior under dark conditions and remarkable increase in current corresponding to light intensity under light irradiation. Ultraweak photon emission of about 600 counts per second in the ultraviolet region could be detected at room temperature by this photon counter

Probing Sub-GeV Dark Matter with Conventional Detectors

DEFF Research Database (Denmark)

Kouvaris, Chris; Pradler, Josef

2017-01-01

The direct detection of dark matter particles with mass below the GeV scale is hampered by soft nuclear recoil energies and finite detector thresholds. For a given maximum relative velocity, the kinematics of elastic dark matter nucleus scattering sets a principal limit on detectability. Here, we...... propose to bypass the kinematic limitations by considering the inelastic channel of photon emission from bremsstrahlung in the nuclear recoil. Our proposed method allows us to set the first limits on dark matter below 500 MeV in the plane of dark matter mass and cross section with nucleons. In situations...... where a dark-matter-electron coupling is suppressed, bremsstrahlung may constitute the only path to probe low-mass dark matter awaiting new detector technologies with lowered recoil energy thresholds....

A simulation to model position encoding multicrystal PET detectors

Energy Technology Data Exchange (ETDEWEB)

Tsang, G; Moisan, C; Rogers, J G

1995-05-01

We have developed a simulation to model position encoding multicrystal detectors for positron emission tomography. The simulation is designed to treat the interactions of energetic photons in a scintillator, the geometry of the multicrystal array, as well as the propagation and detection of individual scintillation photons. The simulation is tested with a model of the EXACT HR PLUS block detector manufactured by Siemens-CTI. Position and energy responses derived from the simulation are compared to measured ones. Line-spread-functions, for four columns of crystals, are reproduced with an accuracy of {+-}0.5 mm. The crystal-by-crystal photopeak pulse heights and FWHMs are also predicted within a range of {+-}14%, and {sub -6}{sup +9}% respectively. (author). 21 refs., 2 tabs., 7 figs.

Detector Control System for the ATLAS Forward Proton detector

CERN Document Server

Czekierda, Sabina; The ATLAS collaboration

2017-01-01

The ATLAS Forward Proton (AFP) is a forward detector using a Roman Pot technique, recently installed in the LHC tunnel. It is aiming at registering protons that were diffractively or electromagnetically scattered in soft and hard processes. Infrastructure of the detector consists of hardware placed both in the tunnel and in the control room USA15 (about 330 meters from the Roman Pots). AFP detector, like the other detectors of the ATLAS experiment, uses the Detector Control System (DCS) to supervise the detector and to ensure its safe and coherent operation, since the incorrect detector performance may influence the physics results. The DCS continuously monitors the detector parameters, subset of which is stored in data bases. Crucial parameters are guarded by alarm system. A detector representation as a hierarchical tree-like structure of well-defined subsystems built with the use of the Finite State Machine (FSM) toolkit allows for overall detector operation and visualization. Every node in the hierarchy is...

Dual pathology proximal median nerve compression of the forearm.

LENUS (Irish Health Repository)

Murphy, Siun M

2013-12-01

We report an unusual case of synchronous pathology in the forearm- the coexistence of a large lipoma of the median nerve together with an osteochondroma of the proximal ulna, giving rise to a dual proximal median nerve compression. Proximal median nerve compression neuropathies in the forearm are uncommon compared to the prevalence of distal compression neuropathies (eg Carpal Tunnel Syndrome). Both neural fibrolipomas (Refs. 1,2) and osteochondromas of the proximal ulna (Ref. 3) in isolation are rare but well documented. Unlike that of a distal compression, a proximal compression of the median nerve will often have a definite cause. Neural fibrolipoma, also called fibrolipomatous hamartoma are rare, slow-growing, benign tumours of peripheral nerves, most often occurring in the median nerve of younger patients. To our knowledge, this is the first report of such dual pathology in the same forearm, giving rise to a severe proximal compression of the median nerve. In this case, the nerve was being pushed anteriorly by the osteochondroma, and was being compressed from within by the intraneural lipoma. This unusual case highlights the advantage of preoperative imaging as part of the workup of proximal median nerve compression.

Giant proximity effect and critical opalescence in EuS

Science.gov (United States)

Charlton, Timothy; Ramos, Silvia; Quintanilla, Jorge; Suter, Andreas; Moodera, Jagadeesh

2015-03-01

The proximity effect is a type of wetting phenomenon where an ordered state, usually magnetism or superconductivity, ``leaks'' from one material into an adjacent one over some finite distance. For superconductors, the characteristic range is of the order of the coherence length, usually hundreds of nm. Nevertheless much longer, ``giant'' proximity effects have been observed in cuprate perovskite junctions. Such giant proximity effects can be understood by taking into account the divergence of the pairing susceptibility in the non-superconducting material when it is itself close to a superconducting instability: a superconducting version of critical opalescence. Since critical opalescence occurs in all second order phase transitions, giant proximity effects are expected to be general, therefor there must be a giant ferromagnetic proximity effect. Compared to its superconducting counterpart, the giant ferromagnetic proximity effect has the advantage that the order parameter (magnetization) can be observed directly. We have fabricated Co/EuS thin films and measured the magnetization profiles as a function of temperature using the complementary techniques of low energy muon relaxation and polarized neutron reflectivity. Details of the proximity effect near TCEuS will be presented.

Strong Proximities on Smooth Manifolds and Vorono\\" i Diagrams

OpenAIRE

Peters, J. F.; Guadagni, C.

2015-01-01

This article introduces strongly near smooth manifolds. The main results are (i) second countability of the strongly hit and far-miss topology on a family $\\mathcal{B}$ of subsets on the Lodato proximity space of regular open sets to which singletons are added, (ii) manifold strong proximity, (iii) strong proximity of charts in manifold atlases implies that the charts have nonempty intersection. The application of these results is given in terms of the nearness of atlases and charts of proxim...

Gamma ray spectrum of Am 241 in a backscattering geometry using a high purity germanium detector

International Nuclear Information System (INIS)

Chong Chon Sing; Ibrahim Salih Elyaseery; Ahmad Shukri Mustapa Kamal; Abdul Aziz Tajuddin

1997-01-01

In back scattering geometry using an annular Am-241 source and a HPGE detector has been set up to study both the coherent and incoherent scattering of photon emissions of Am-241 from medium-Z and high-Z elements. Besides the coherent and incoherent scattered peaks of the emissions from the source, the gamma ray spectrum from the different target elements obtained using a microcomputer based multichannel analyser showed the presence of several other peaks. These peaks have been identified to arise from the fluorescence of the targets, the fluorescence of the shielding material Pb, and also as fluorescence sum peaks and X-ray escape peaks of the detector material Ge. The spectra are presented for three target elements viz. Mo, Zn and W

75 FR 5009 - Proximity Detection Systems for Underground Mines

Science.gov (United States)

2010-02-01

... Proximity Detection Systems for Underground Mines AGENCY: Mine Safety and Health Administration, Labor... information regarding whether the use of proximity detection systems would reduce the risk of accidents where... . Information on MSHA-approved proximity detection systems is available on the Internet at http://www.msha.gov...

Bimalleolar ankle fracture with proximal fibular fracture

NARCIS (Netherlands)

Colenbrander, R. J.; Struijs, P. A. A.; Ultee, J. M.

2005-01-01

A 56-year-old female patient suffered a bimalleolar ankle fracture with an additional proximal fibular fracture. This is an unusual fracture type, seldom reported in literature. It was operatively treated by open reduction and internal fixation of the lateral malleolar fracture. The proximal fibular

[Partial replantation following proximal limb injury].

Science.gov (United States)

Dubert, T; Malikov, S A; Dinh, A; Kupatadze, D D; Oberlin, C; Alnot, J Y; Nabokov, B B

2000-11-01

Proximal replantation is a technically feasible but life-threatening procedure. Indications must be restricted to patients in good condition with a good functional prognosis. The goal of replantation must be focused not only on reimplanting the amputated limb but also on achieving a good functional outcome. For the lower limb, simple terminalization remains the best choice in many cases. When a proximal amputation is not suitable for replantation, the main aim of the surgical procedure must be to reconstruct a stump long enough to permit fitting a prosthesis preserving the function of the adjacent joint. If the proximal stump beyond the last joint is very short, it may be possible to restore some length by partial replantation of spared tissues from the amputated part. We present here the results we obtained following this policy. This series included 16 cases of partial replantations, 14 involving the lower limb and 2 the upper limb. All were osteocutaneous microsurgical transfers. For the lower limb, all transfers recovered protective sensitivity following tibial nerve repair. The functional calcaeoplantar unit was used in 13 cases. The transfer of this specialized weight bearing tissue provided a stable distal surface making higher support unnecessary. In one case, we raised a 13-cm vascularized tibial segment covered with foot skin for additional length. For the upper limb, the osteocutaneous transfer, based on the radial artery, was not reinnervated, but this lack of sensitivity did not impair prosthesis fitting. One vascular failure was finally amputated. This was the only unsuccessful result. For all other patients, the surgical procedure facilitated prosthesis fitting and preserved the proximal joint function despite an initially very proximal amputation. The advantages of partial replantation are obvious compared with simple terminalization or secondary reconstruction. There is no secondary donor site and, because there is no major muscle mass in the

Sensitization by UV light of α-Al{sub 2}O{sub 3}:C polycrystalline detectors

Energy Technology Data Exchange (ETDEWEB)

Meira B, L. C.; Rubio F, H.; Neres de A, E. [Centro de Desenvolvimento da Tecnologia Nuclear - CNEN, Laboratorio de Dosimetria Termoluminicente, Av. Antonio Carlos 6627, Campus UFMG, CEP 31270-901, Belo Horizonte (Brazil); Santos, A., E-mail: hrf@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear - CNEN, Laboratorio de Microesferas Gel, Av. Antonio Carlos 6627, Campus UFMG, CEP 31270-901, Belo Horizonte (Brazil)

2014-08-15

This paper describes an increase in sensitivity to gamma and beta radiation on α-Al{sub 2}O{sub 3}:C polycrystalline detector, which has been produced by a sol-gel process, following previous exposure to ultraviolet light. The increased sensitivity of the detector as a function of the exposure time and ultraviolet wavelength was studied. Since the main luminescent centers have emission peaks at different wavelengths, selective measurements of thermoluminescent emission intensity were done, in order to investigate the possible conversion of centers as a result of the exposition to ultraviolet light. Experimental results indicate that the nature and parameters of the luminescent centers in α-Al{sub 2}O{sub 3}:C sol-gel material can be very different of those in α-Al{sub 2}O{sub 3}:C single crystal. (author)

Investigation of neutron emission in a cold fusion experiment in palladium

International Nuclear Information System (INIS)

Szustakowski, M.; Farny, J.; Muniak, M.; Nowak, A.; Parys, P.; Skrzeczanowski, W.; Socha, R.; Teter, J.; Wolski, J.; Wolowski, J.; Woryna, E.

1989-01-01

This paper reports on the experiments dealing with performance of nuclear fusion at room temperature actually which create a great sensation and are carried out in various laboratories. This interest arises from the results achieved by Fleischmann and Pons, and it results from their paper that there exists a possibility of obtaining an ignition owing to nuclear fusion reactions during usual electrochemical process--namely the electrolysis of D O with use of the system of Pd-Pt electrodes. From this reason the measurements of the yield and behavior of neutron emission give the information about processes of interest. At the IPPLM the cold fusion experiments have been conducted from the beginning of April 1989. In the first experiment the reliable evidence of neutron emission was obtained. A number of irregularly repeated neutron pulses of the level of 10 5 per pulse was recorded. The measurements of the neutron emission, in this experiment, were performed with the use of three independent methods employing the 2.5 MeV neutron spectrometer, the scintillation neutron detector as well as the nuclear track detector. neutron emission had been first recorded after 106 hours of the electrolysis process of D 2 O

Evaluation of PET Imaging Resolution Using 350 mu{m} Pixelated CZT as a VP-PET Insert Detector

Science.gov (United States)

Yin, Yongzhi; Chen, Ximeng; Li, Chongzheng; Wu, Heyu; Komarov, Sergey; Guo, Qingzhen; Krawczynski, Henric; Meng, Ling-Jian; Tai, Yuan-Chuan

2014-02-01

A cadmium-zinc-telluride (CZT) detector with 350 μm pitch pixels was studied in high-resolution positron emission tomography (PET) imaging applications. The PET imaging system was based on coincidence detection between a CZT detector and a lutetium oxyorthosilicate (LSO)-based Inveon PET detector in virtual-pinhole PET geometry. The LSO detector is a 20 ×20 array, with 1.6 mm pitches, and 10 mm thickness. The CZT detector uses ac 20 ×20 ×5 mm substrate, with 350 μm pitch pixelated anodes and a coplanar cathode. A NEMA NU4 Na-22 point source of 250 μm in diameter was imaged by this system. Experiments show that the image resolution of single-pixel photopeak events was 590 μm FWHM while the image resolution of double-pixel photopeak events was 640 μm FWHM. The inclusion of double-pixel full-energy events increased the sensitivity of the imaging system. To validate the imaging experiment, we conducted a Monte Carlo (MC) simulation for the same PET system in Geant4 Application for Emission Tomography. We defined LSO detectors as a scanner ring and 350 μm pixelated CZT detectors as an insert ring. GATE simulated coincidence data were sorted into an insert-scanner sinogram and reconstructed. The image resolution of MC-simulated data (which did not factor in positron range and acolinearity effect) was 460 μm at FWHM for single-pixel events. The image resolutions of experimental data, MC simulated data, and theoretical calculation are all close to 500 μm FWHM when the proposed 350 μm pixelated CZT detector is used as a PET insert. The interpolation algorithm for the charge sharing events was also investigated. The PET image that was reconstructed using the interpolation algorithm shows improved image resolution compared with the image resolution without interpolation algorithm.

Detector block based on arrays of 144 SiPMs and monolithic scintillators: A performance study

International Nuclear Information System (INIS)

González, A.J.; Conde, P.; Iborra, A.; Aguilar, A.; Bellido, P.; García-Olcina, R.; Hernández, L.; Moliner, L.; Rigla, J.P.; Rodríguez-Álvarez, M.J.; Sánchez, F.; Seimetz, M.; Soriano, A.; Torres, J.; Vidal, L.F.; Benlloch, J.M.

2015-01-01

We have developed a detector block composed by a monolithic LYSO scintillator coupled to a custom made 12×12 SiPMs array. The design is mainly focused to applications such as Positron Emission Tomography. The readout electronics is based on 3 identical and scalable Application Specific Integrated Circuits (ASIC). We have determined the main performance of the detector block namely spatial, energy, and time resolution but also the system capability to determine the photon depth of interaction, for different crystal surface treatments. Intrinsic detector spatial resolution values as good as 1.7 mm FWHM and energies of 15% for black painted crystals were measured

Proximity functions for general right cylinders

International Nuclear Information System (INIS)

Kellerer, A.M.

1981-01-01

Distributions of distances between pairs of points within geometrical objects, or the closely related proximity functions and geometric reduction factors, have applications to dosimetric and microdosimetric calculations. For convex bodies these functions are linked to the chord-length distributions that result from random intersections by straight lines. A synopsis of the most important relations is given. The proximity functions and related functions are derived for right cylinders with arbitrary cross sections. The solution utilizes the fact that the squares of the distances between two random points are sums of independently distributed squares of distances parallel and perpendicular to the axis of the cylinder. Analogous formulas are derived for the proximity functions or geometric reduction factors for a cylinder relative to a point. This requires only a minor modification of the solution

Design and development of 1 mm resolution PET detectors with position-sensitive PMTs

CERN Document Server

Shao, Y; Chatziioannou, A F

2002-01-01

We report our investigation of a positron emission tomography (PET) detector with 1 m spatial resolution. The prototype detector consists of a 9x9 array of 1x1x10 mm sup 3 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to Hamamatsu R5900-M64 or R5900-C12 position sensitive PMT by either optical fibers or an optical fiber bundle. With a 511 eV gamma source, the intrinsic spatial resolution of this detector was measured to be 0.92 mm. All crystals were well resolved in the flood source histogram. The measured energy and coincidence timing resolutions were around 26% and 4 ns, respectively, demonstrating that sufficient light can be extracted from these small crystals for PET applications.

Development of continuous detectors for a high resolution animal PET system

International Nuclear Information System (INIS)

Siegel, S.; Cherry, S.R.; Ricci, A.R.; Shao, Y.; Phelps, M.E.

1995-01-01

The authors propose a design for a high resolution, gamma-camera style detector that is suitable for use in a positron emission tomograph dedicated to small animal research. Through Monte Carlo simulation the authors modeled the performance of a detector composed of one 76.2 x 76.2 x 8 mm thick LSO crystal coupled to a 3 in. square position sensitive photomultiplier tube (PS-PMT). The authors investigated the effect of optical coupling compounds, surface treatment and dept of interaction on the quantity (efficiency) and distribution (spread) of scintillation photons reaching the photocathode. They also investigated linearization of the position response. The authors propose a PET system consisting of fourteen of these detectors in 2 rings, yielding a 16 cm diameter by 15 cm long tomograph. It would operate in 3-D mode subtending a 68% solid angle to the center. The expected spatial resolution is (≤2 mm), with a system efficiency of ∼ 10% at the center (200 keV lower threshold) and a singles count rate capability of approximately 10 6 cps per detector

Analysis of Burst Observations by GLAST's LAT Detector

International Nuclear Information System (INIS)

Band, David L.; Digel, Seth W.

2004-01-01

Analyzing data from GLAST's Large Area Telescope (LAT) will require sophisticated techniques. The PSF and effective area are functions of both photon energy and the position in the field-of-view. During most of the mission the observatory will survey the sky continuously, and thus, the LAT will detect each count from a source at a different detector orientation; each count requires its own response function! The likelihood as a function of celestial position and photon energy will be the foundation of the standard analysis techniques. However, the 20 MeV-300 GeV emission at the time of the ∼ 100 keV burst emission (timescale of ∼ 10 s) can be isolated and analyzed because essentially no non-burst counts are expected within a PSF radius of the burst location during the burst. Both binned and unbinned (in energy) spectral fitting will be possible. Longer timescale afterglow emission will require the likelihood analysis that will be used for persistent sources

Position-Sensitive Detector with Depth-of-Interaction Determination for Small Animal PET

CERN Document Server

Fedorov, A; Kholmetsky, A L; Korzhik, M V; Lecoq, P; Lobko, A S; Missevitch, O V; Tkatchev, A

2002-01-01

Crystal arrays made of LSO and LuAP crystals 2x2x10 mm pixels were manufactured for evaluation of detector with depth-of-interaction (DOI) determination capability intended for small animal positron emission tomograph. Position-sensitive LSO/LuAP phoswich DOI detector based on crystal 8x8 arrays and HAMAMATSU R5900-00-M64 position-sensitive multi-anode photomultiplier tube was developed and evaluated. Time resolution was found to be not worse than 1.0 ns FWHM for both layers, and spatial resolution mean value was 1.5 mm FWHM for the center of field-of-view.

Early warning for VHE gamma-ray flares with the ARGO-YBJ detector

Energy Technology Data Exchange (ETDEWEB)

Bartoli, B. [Dipartimento di Fisica dell' Universita di Napoli ' Federico II' , Complesso Universitario di Monte Sant' Angelo, via Cinthia, 80126 Napoli (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Complesso Universitario di Monte Sant' Angelo, via Cinthia, 80126 Napoli (Italy); Bernardini, P. [Dipartimento di Fisica dell' Universita del Salento, via per Arnesano, 73100 Lecce (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Lecce, via per Arnesano, 73100 Lecce (Italy); Bi, X.J. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918, 100049 Beijing (China); Bleve, C. [Dipartimento di Fisica dell' Universita del Salento, via per Arnesano, 73100 Lecce (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Lecce, via per Arnesano, 73100 Lecce (Italy); Bolognino, I. [Dipartimento di Fisica Nucleare e Teorica dell' Universita di Pavia, via Bassi 6, 27100 Pavia (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, via Bassi 6, 27100 Pavia (Italy); Branchini, P.; Budano, A. [Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tre, via della Vasca Navale 84, 00146 Roma (Italy); Calabrese Melcarne, A.K. [Istituto Nazionale di Fisica Nucleare - CNAF, Viale Berti-Pichat 6/2, 40127 Bologna (Italy); Camarri, P. [Dipartimento di Fisica dell' Universita di Roma ' Tor Vergata' , via della Ricerca Scientifica 1, 00133 Roma (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Roma Tor Vergata, via della Ricerca Scientifica 1, 00133 Roma (Italy); Cao, Z. [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, P.O. Box 918, 100049 Beijing (China); and others

2011-12-11

Detecting and monitoring emissions from flaring gamma-ray sources in the very-high-energy (VHE, > 100 GeV) band is a very important topic in gamma-ray astronomy. The ARGO-YBJ detector is characterized by a high duty cycle and a wide field of view. Therefore, it is particularly capable of detecting flares from extragalactic objects. Based on fast reconstruction and analysis, real-time monitoring of 33 selected VHE extragalactic sources is implemented. Flares exceeding a specific threshold are reported timely, hence enabling the follow-up observation of these objects using more sensitive detectors, such as Cherenkov telescopes.

MCNP modelling of scintillation-detector gamma-ray spectra from natural radionuclides

NARCIS (Netherlands)

Hendriks, Peter; Maucec, M; de Meijer, RJ

gamma-ray spectra of natural radionuclides are simulated for a BGO detector in a borehole geometry using the Monte Carlo code MCNP. All gamma-ray emissions of the decay of K-40 and the series of Th-232 and U-238 are used to describe the source. A procedure is proposed which excludes the

NOx and SO2 emission factors for Serbian lignite Kolubara

Directory of Open Access Journals (Sweden)

Jovanović Vladimir V.

2012-01-01

Full Text Available Emission factors are widely accepted tool for estimation of various pollutants emissions in USA and EU. Validity of emission factors is strongly related to experimental data on which they are based. This paper is a result of an effort to establish reliable NOx and SO2 emission factors for Serbian coals. The results of NOx and SO2 emissions estimations based on USA and EU emission factors from thermal power plants Nikola Tesla Obrenovac A and B utilizing the Serbian lignite Kolubara are compared with experimental data obtained during almost one decade (2000-2008 of emissions measurements. Experimental data are provided from regular annual emissions measurement along with operational parameters of the boiler and coal (lignite Kolubara ultimate and proximate analysis. Significant deviations of estimated from experimental data were observed for NOx, while the results for SO2 were satisfactory. Afterwards, the estimated and experimental data were plotted and linear regression between them established. Single parameter optimization was performed targeting the ideal slope of the regression line. Results of this optimization provided original NOx and SO2 emission factors for Kolubara lignite.

Calibration of detector efficiency of neutron detector

International Nuclear Information System (INIS)

Guo Hongsheng; He Xijun; Xu Rongkun; Peng Taiping

2001-01-01

BF 3 neutron detector has been set up. Detector efficiency is calibrated by associated particle technique. It is about 3.17 x 10 -4 (1 +- 18%). Neutron yield of neutron generator per pulse (10 7 /pulse) is measured by using the detector

Proximity effect at Millikelvin temperatures

International Nuclear Information System (INIS)

Mota, A.C.

1986-01-01

Proximity effects have been studied extensively for the past 25 years. Typically, they are in films several thousand angstroms thick at temperatures not so far below T/sub CNS/, the transition temperature of the NS system. Interesting is, however, the proximity effect at temperatures much lower than T/sub CNS/. In this case, the Cooper-pair amplitudes are not small and very long pair penetration lengths into the normal metal can be expected. Thus, we have observed pair penetration lengths. For these investigations very suitable specimens are commercial wires of one filament of NbTi or Nb embedded in a copper matrix. The reasons are the high transmission coefficient at the interface between the copper and the superconductor and the fact that the copper in these commercial wires is rather clean with electron free paths between 5 to 10 μm long. In this paper, the magnetic properties of thick proximity systems in the range of temperatures between T/sub CNS/ and 5 x 10/sup -4/ T/sub CNS/ in both low and high magnetic fields are discussed

The Contribution of SPECT/CT in the Diagnosis of Stress Fracture of the Proximal Tibia

Directory of Open Access Journals (Sweden)

Berna Okudan

2018-02-01

Full Text Available Stress fractures are injuries most commonly seen in the lower limbs and are usually caused by repetitive stress. While the distal and middle third of the tibia is the most frequent site for stress fractures (almost 50%, stress fractures of the proximal tibia is relatively rare and could be confused with other types of tibial fractures, thus altering management plans for the clinician. Early diagnosis of stress fractures is also important to avoid complications. Imaging plays an important role in the diagnosis of stress fractures, especially bone scan. Combined with single-photon emission computed tomography/computed tomography (SPECT/CT it is an important imaging technique for stress fractures in both upper and lower extremities, and is widely preferred over other imaging techniques. In this case, we present the case of a 39-year-old male patient diagnosed with stress fracture of the proximal tibia and demonstrate the contribution of CT scan fused with SPECT imaging in the early diagnosis of stress fracture prior to other imaging modalities.

Advanced Instrumentation for Positron Emission Tomography [PET

Science.gov (United States)

Derenzo, S. E.; Budinger, T. F.

1985-04-01

This paper summarizes the physical processes and medical science goals that underlay modern instrumentation design for Positron Emission Tomography. The paper discusses design factors such as detector material, crystalphototube coupling, shielding geometry, sampling motion, electronics design, time-of-flight, and the interrelationships with quantitative accuracy, spatial resolution, temporal resolution, maximum data rates, and cost.

A segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics for a PET scanner

CERN Document Server

Chesi, Enrico Guido; Joram, C; Mathot, S; Séguinot, Jacques; Weilhammer, P; Ciocia, F; De Leo, R; Nappi, E; Vilardi, I; Argentieri, A; Corsi, F; Dragone, A; Pasqua, D

2006-01-01

We describe the design, fabrication and test results of a segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics. Both the photodetector and its VLSI readout electronics are custom designed and have been tailored to the requirements of a recently proposed novel geometrical concept of a Positron Emission Tomograph. Emphasis is put on the PET specific features of the device. The detector has been fabricated in the photocathode facility at CERN.

A region segmentation based algorithm for building a crystal position lookup table in a scintillation detector

International Nuclear Information System (INIS)

Wang Haipeng; Fan Xin; Yun Mingkai; Liu Shuangquan; Cao Xuexiang; Chai Pei; Shan Baoci

2015-01-01

In a scintillation detector, scintillation crystals are typically made into a 2-dimensional modular array. The location of incident gamma-ray needs be calibrated due to spatial response nonlinearity. Generally, position histograms-the characteristic flood response of scintillation detectors-are used for position calibration. In this paper, a position calibration method based on a crystal position lookup table which maps the inaccurate location calculated by Anger logic to the exact hitting crystal position has been proposed. Firstly, the position histogram is preprocessed, such as noise reduction and image enhancement. Then the processed position histogram is segmented into disconnected regions, and crystal marking points are labeled by finding the centroids of regions. Finally, crystal boundaries are determined and the crystal position lookup table is generated. The scheme is evaluated by the whole-body positron emission tomography (PET) scanner and breast dedicated single photon emission computed tomography scanner developed by the Institute of High Energy Physics, Chinese Academy of Sciences. The results demonstrate that the algorithm is accurate, efficient, robust and applicable to any configurations of scintillation detector. (authors)

Dual pathology proximal median nerve compression of the forearm.

Science.gov (United States)

Murphy, Siun M; Browne, Katherine; Tuite, David J; O'Shaughnessy, Michael

2013-12-01

We report an unusual case of synchronous pathology in the forearm- the coexistence of a large lipoma of the median nerve together with an osteochondroma of the proximal ulna, giving rise to a dual proximal median nerve compression. Proximal median nerve compression neuropathies in the forearm are uncommon compared to the prevalence of distal compression neuropathies (eg Carpal Tunnel Syndrome). Both neural fibrolipomas (Refs. 1,2) and osteochondromas of the proximal ulna (Ref. 3) in isolation are rare but well documented. Unlike that of a distal compression, a proximal compression of the median nerve will often have a definite cause. Neural fibrolipoma, also called fibrolipomatous hamartoma are rare, slow-growing, benign tumours of peripheral nerves, most often occurring in the median nerve of younger patients. To our knowledge, this is the first report of such dual pathology in the same forearm, giving rise to a severe proximal compression of the median nerve. In this case, the nerve was being pushed anteriorly by the osteochondroma, and was being compressed from within by the intraneural lipoma. This unusual case highlights the advantage of preoperative imaging as part of the workup of proximal median nerve compression. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

An in-vitro evaluation of Kodak Insight and Ektaspeed Plus film with a CMOS detector for natural proximal caries: ROC analysis.

Science.gov (United States)

Nair, M K; Nair, U P

2001-01-01

This study compared the diagnostic efficacy of Kodak Ektaspeed Plus film, Kodak Insight film, a newly introduced E/F-speed film, and Schick CMOS-APS digital sensor, with respect to caries detection in 92 proximal surfaces of extracted unrestored teeth, 51 of which were carious. Ground truth was evaluated histologically and the lesions classified as enamel or dentinal. Eight observers read the radiographs using a five-point confidence rating scale to record their diagnoses. Analyses using receiver operating characteristic curves revealed the areas under each curve that indicated the diagnostic accuracy (Ektaspeed Plus - 0.760, Insight - 0.778 and CMOS-APS sensor - 0.732). ANOVA revealed significant differences with respect to caries depth (p<0.031) and observers (p<0.0001). Weighted kappa analyses indicated moderate to substantial inter- and intra-observer agreement (0.42 and 0.66, respectively). The results suggest that none of the imaging modalities evaluated in this study differed in their diagnostic capabilities with respect to proximal decay detection and that the Insight film which was used with 20% less radiation exposure than Ektaspeed Plus film was as good as the other two sensors for this purpose.

A Silicon Nanomembrane Detector for Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) of Large Proteins

OpenAIRE

Park, Jonghoo; Blick, Robert

2013-01-01

We describe a MALDI-TOF ion detector based on freestanding silicon nanomembrane technology. The detector is tested in a commercial MALDI-TOF mass spectrometer with equimolar mixtures of proteins. The operating principle of the nanomembrane detector is based on phonon-assisted field emission from these silicon nanomembranes, in which impinging ion packets excite electrons in the nanomembrane to higher energy states. Thereby the electrons can overcome the vacuum barrier and escape from the surf...

Optimization of detector size and collimator for PG-SPECT

International Nuclear Information System (INIS)

Ishikawa, M.; Kobayashi, T.; Kanda, K.

2000-01-01

A current absorbed dose evaluation method in a Boron Neutron Capture Therapy demands boron reaction rate from a boron concentration of an affected part supposed from a neutron flux and a boron concentration in blood measured by an activation method of a gold wire indirectly and converts it into an absorbed dose. So we devised a PG-SEPCT (Prompt Gamma-ray Single Photon Emission Computed Tomography) system to evaluate an absorbed dose directly by measuring prompt gamma-rays. Ordinary SPECT system uses a big NaI scintillator for detector so that measurement is done in low background gamma-ray environment. However, a conventional detector and collimator system cannot be just applied to PG-SPECT system because a background radiation coexists abundantly (PG-SPECT system is set in irradiation room). Accordingly PG-SPECT system requires a dedicated detector and collimator system. In order to reduce efficiency for background gamma-rays, we arranged detectors in a collimator to shield from background gamma-rays. We examined the most suitable collimator shape. The optimization condition of a dedicated collimator system is as follows: 1) the smallest particle size that can be distinguished is 1 cm. 2) necessary counts at measurement target center is not less than 10,000. (author)

Long-wave, infrared laser-induced breakdown (LIBS) spectroscopy emissions from energetic materials.

Science.gov (United States)

Yang, Clayton S-C; Brown, Ei E; Hommerich, Uwe; Jin, Feng; Trivedi, Sudhir B; Samuels, Alan C; Snyder, A Peter

2012-12-01

Laser-induced breakdown spectroscopy (LIBS) has shown great promise for applications in chemical, biological, and explosives sensing and has significant potential for real-time standoff detection and analysis. In this study, LIBS emissions were obtained in the mid-infrared (MIR) and long-wave infrared (LWIR) spectral regions for potential applications in explosive material sensing. The IR spectroscopy region revealed vibrational and rotational signatures of functional groups in molecules and fragments thereof. The silicon-based detector for conventional ultraviolet-visible LIBS operations was replaced with a mercury-cadmium-telluride detector for MIR-LWIR spectral detection. The IR spectral signature region between 4 and 12 μm was mined for the appearance of MIR and LWIR-LIBS emissions directly indicative of oxygenated breakdown products as well as dissociated, and/or recombined sample molecular fragments. Distinct LWIR-LIBS emission signatures from dissociated-recombination sample molecular fragments between 4 and 12 μm are observed for the first time.

Prospects of diffractive physics with the ATLAS forward detectors

CERN Document Server

Lopez Paz, Ivan; The ATLAS collaboration

2017-01-01

The ATLAS Forward Proton (AFP) detector provides measurements of the momentum and emission angle of very forward protons. This enables the observation and measurement of a range of processes where one or both protons remain intact. Such processes are associated with elastic and diffractive scattering. In this talk, we give on overview of the technical details of the AFP, its current status as well as its associated physics program.

Emission probabilities of KX- and γ rays following 51CR and 67Ga Decay

International Nuclear Information System (INIS)

Yalcin, P.

2004-01-01

Emission probabilities of KX- and γ-rays following the decay of 5 ICr and 6 7Ga were precisely measured with a calibrated Si(Li) detector. The photopeak efficiency Si(Li) semiconductor detector was determined experimentally for about 4-400 keV energy range by using standard sources. Results of this study have been compared with the theoretical values and other available experimental results in the literature. Good agreement was observed among our results, other available experimental results and theoretically calculated values. The standard deviations for each emission probability were calculated from the quadratic sum of the variances of the various contributions the total uncertainty

Time-of-Flight Positron Emission Tomography with Radiofrequency Phototube

International Nuclear Information System (INIS)

Margaryan, A.; Kakoyan, V.; Knyazyan, S.

2011-01-01

In this paper γ-detector, based on the radiofrequency (RF) phototube and recently developed fast and ultrafast scintillators, is considered for Time-of-Flight positron emission tomography applications. Timing characteristics of such a device has been investigated by means of a dedicated Monte Carlo code based on the single photon counting concept. Biexponential timing model for scintillators have been used. The calculations have shown that such a timing model is in a good agreement with recently measured data. The timing resolution of -detectors can be significantly improved by using the RF phototube. (authors)

Radiation detectors laboratory; Laboratorio de detectores de radiacion

Energy Technology Data Exchange (ETDEWEB)

Ramirez J, F.J. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

1997-07-01

The Radiation detectors laboratory was established with the assistance of the International Atomic Energy Agency which gave this the responsibility to provide its services at National and regional level for Latin America and it is located at the ININ. The more expensive and delicate radiation detectors are those made of semiconductor, so it has been put emphasis in the use and repairing of these detectors type. The supplied services by this laboratory are: selection consultant, detectors installation and handling and associated systems. Installation training, preventive and corrective maintenance of detectors and detection systems calibration. (Author)

Three-dimensional cross point readout detector design for including depth information

Science.gov (United States)

Lee, Seung-Jae; Baek, Cheol-Ha

2018-04-01

We designed a depth-encoding positron emission tomography (PET) detector using a cross point readout method with wavelength-shifting (WLS) fibers. To evaluate the characteristics of the novel detector module and the PET system, we used the DETECT2000 to perform optical photon transport in the crystal array. The GATE was also used. The detector module is made up of four layers of scintillator arrays, the five layers of WLS fiber arrays, and two sensor arrays. The WLS fiber arrays in each layer cross each other to transport light to each sensor array. The two sensor arrays are coupled to the forward and left sides of the WLS fiber array, respectively. The identification of three-dimensional pixels was determined using a digital positioning algorithm. All pixels were well decoded, with the system resolution ranging from 2.11 mm to 2.29 mm at full width at half maximum (FWHM).

Design and implementation of a simple on-line time-activity curve detector for [O-15] water PET studies

International Nuclear Information System (INIS)

Wollenweber, S.D.; Hichwa, R.D.; Ponto, L.L.B.

1996-01-01

A simple, automated on-line detector system has been fabricated and implemented to detect the arterial time-activity curve (TAC) for water PET studies. This system offers two significant improvements over existing systems: a pump mechanism is not required to control arterial blood flow through the detector and dispersion correction of the time-activity curve is unnecessary. The positrons emanating from a thin-walled, 0.134 cm inner-diameter plastic tube are detected by a 0.5 cm wide by 1.0 cm long by 0.1 cm thick plastic scintillator mounted to a miniature PMT. Photon background is shielded by a 2.0 cm thick cylindrical lead shield. Mean cerebral blood flow (mCBF) calculated from the TAC determined by 1-second automated sampling was compared to that calculated from every 5-second integrated manual samples. Improvements in timing resolution (1-sec vs. 5-sec) cause small but significant differences between the two sampling methods. Dispersion is minimized due to small tubing diameters, short lengths of tubing between the radial arterial sampling site and the detector and the presence of a 3-way valve 10 cm proximal to the detector

Detector and System Developments for LHC Detector Upgrades

CERN Document Server

Mandelli, Beatrice; Guida, Roberto; Rohne, Ole; Stapnes, Steinar

2015-05-12

The future Large Hadron Collider (LHC) Physics program and the consequent improvement of the LHC accelerator performance set important challenges to all detector systems. This PhD thesis delineates the studies and strategies adopted to improve two different types of detectors: the replacement of precision trackers with ever increasingly performing silicon detectors, and the improvement of large gaseous detector systems by optimizing their gas mixtures and operation modes. Within the LHC tracker upgrade programs, the ATLAS Insertable B-layer (IBL) is the first major upgrade of a silicon-pixel detector. Indeed the overall ATLAS Pixel Detector performance is expected to degrade with the increase of luminosity and the IBL will recover the performance by adding a fourth innermost layer. The IBL Detector makes use of new pixel and front-end electronics technologies as well as a novel thermal management approach and light support and service structures. These innovations required complex developments and Quality Ass...

Detector Unit

CERN Multimedia

1960-01-01

Original detector unit of the Instituut voor Kernfysisch Onderzoek (IKO) BOL project. This detector unit shows that silicon detectors for nuclear physics particle detection were already developed and in use in the 1960's in Amsterdam. Also the idea of putting 'strips' onto the silicon for high spatial resolution of a particle's impact on the detector were implemented in the BOL project which used 64 of these detector units. The IKO BOL project with its silicon particle detectors was designed, built and operated from 1965 to roughly 1977. Detector Unit of the BOL project: These detectors, notably the ‘checkerboard detector’, were developed during the years 1964-1968 in Amsterdam, The Netherlands, by the Natuurkundig Laboratorium of the N.V. Philips Gloeilampen Fabrieken. This was done in close collaboration with the Instituut voor Kernfysisch Onderzoek (IKO) where the read-out electronics for their use in the BOL Project was developed and produced.

Applications for X-ray detectors in astrophysics

International Nuclear Information System (INIS)

Remillard, R.A.

2003-01-01

Full text: Position-sensitive X-Ray detectors continue to playa central role in high-energy astrophysics. The current science goals are reviewed with emphasis on requirements in terms of camera performance. Wide-field imaging techniques, including coded mask cameras, are an essential part of space programs because of the transient nature of high-priority targets, e.g. eruptions from black-hole binaries and cosmic explosions such as gamma ray bursts. Pointing X-ray telescopes are being planned with a wide range of photon energies and with collection designs that include both mirrors and coded masks. Requirements for high spectral resolution and high time resolution are driven by diverse types of X-ray sources such as msec pulsars, quasars with emission-line profiles shaped by general relativity, and X-ray binaries that exhibit quasi-periodic oscillations in the range of 40-1300 Hz. Many laboratories and universities are involved in space-qualification of new detector technologies, e.g. CZT cameras, X-ray calorimeters, new types of CCDs, and GEM detectors. Even X-ray interferometry is on the horizon of NASA's science roadmap. The difficulties in advancing new technologies for space science applications require careful coordinations between industry and science groups in order to solve science problems while minimizing risk

Characterization of 1.2×1.2 mm2 silicon photomultipliers with Ce:LYSO, Ce:GAGG, and Pr:LuAG scintillation crystals as detector modules for positron emission tomography

Science.gov (United States)

Omidvari, N.; Sharma, R.; Ganka, T. R.; Schneider, F. R.; Paul, S.; Ziegler, S. I.

2017-04-01

The design of a positron emission tomography (PET) scanner is specially challenging since it should not compromise high spatial resolution, high sensitivity, high count-rate capability, and good energy and time resolution. The geometrical design of the system alongside the characteristics of the individual PET detector modules contributes to the overall performance of the scanner. The detector performance is mainly influenced by the characteristics of the photo-detector and the scintillation crystal. Although silicon photomultipliers (SiPMs) have already proven to be promising photo-detectors for PET, their performance is highly influenced by micro-cell structure and production technology. Therefore, five types of SiPMs produced by KETEK with an active area size of 1.2 × 1.2 mm2 were characterized in this study. The SiPMs differed in the production technology and had micro-cell sizes of 25, 50, 75, and 100 μm. Performance of the SiPMs was evaluated in terms of their breakdown voltage, temperature sensitivity, dark count rate, and correlated noise probability. Subsequently, energy resolution and coincidence time resolution (CTR) of the SiPMs were measured with five types of crystals, including two Ce:LYSO, two Ce:GAGG, and one Pr:LuAG. Two crystals with a geometry of 1.5 × 1.5 × 6 mm3 were available from each type. The best CTR achieved was ~ 240 ps, which was obtained with the Ce:LYSO crystals coupled to the 50 μm SiPM produced with the trench technology. The best energy resolution for the 511 keV photo-peak was ~ 11% and was obtained with the same SiPM coupled to the Ce:GAGG crystals.

Probing Sub-GeV Dark Matter with Conventional Detectors.

Science.gov (United States)

Kouvaris, Chris; Pradler, Josef

2017-01-20

The direct detection of dark matter particles with mass below the GeV scale is hampered by soft nuclear recoil energies and finite detector thresholds. For a given maximum relative velocity, the kinematics of elastic dark matter nucleus scattering sets a principal limit on detectability. Here, we propose to bypass the kinematic limitations by considering the inelastic channel of photon emission from bremsstrahlung in the nuclear recoil. Our proposed method allows us to set the first limits on dark matter below 500 MeV in the plane of dark matter mass and cross section with nucleons. In situations where a dark-matter-electron coupling is suppressed, bremsstrahlung may constitute the only path to probe low-mass dark matter awaiting new detector technologies with lowered recoil energy thresholds.

Effect of age on proximal esophageal response to swallowing

Directory of Open Access Journals (Sweden)

Roberto Oliveira Dantas

2010-12-01

Full Text Available CONTEXT: It has been demonstrated that the ageing process affects esophageal motility. OBJECTIVES: To evaluate the effect of the age on the proximal esophageal response to wet swallows. METHOD: We measured the proximal esophageal response to swallows of a 5 mL bolus of water in 69 healthy volunteers, 20 of them aged 18-30 years (group I, 27 aged 31-50 years (group II, and 22 aged 51-74 years (group III. We used the manometric method with continuous perfusion. The proximal esophageal contractions were recorded 5 cm from a pharyngeal recording site located 1 cm above the upper esophageal sphincter. The time between the onset of the pharyngeal and of the proximal esophageal recording (pharyngeal-esophageal time and the amplitude, duration and area under the curve of the proximal esophageal contraction were measured. RESULTS: The pharyngeal-esophageal time was shorter in group I subjects than in group II and III subjects (P<0.05. The duration of proximal esophageal contractions was longer in group I than in groups II and III (P<0.001. There was no differences between groups in the amplitude or area under the curve of contractions. There were no differences between groups II and III for any of the measurements. CONCLUSION: We conclude that the age may affects the response of the proximal esophagus to wet swallows.

Gamma detector for use with luggage X-ray systems

International Nuclear Information System (INIS)

McHugh, H.; Quam, W.

1998-01-01

A new gamma radiation sensor has been designed for installation on several types of luggage x-ray machines and mobile x-ray vans operated by the U.S. Customs Service and the U.S. Department of State. The use of gamma detectors on x-ray machines imposed difficulties not usually encountered in the design of gamma detectors because the spectrum of scattered x-rays, which varied from machine to machine, extended to energies significantly higher than those of the low-energy isotopic emissions. In the original design, the lower level discriminator was raised above the x-ray end point energy resulting in the loss of the americium line associated with plutonium. This reduced the overall sensitivity to unshielded plutonium by a factor of approximately 100. An improved method was subsequently developed wherein collimation was utilized in conjunction with a variable counting threshold to permit accommodation of differing conditions of x-ray scattering. This design has been shown to eliminate most of the problems due to x-ray scattering while still capturing the americium emissions. The overall sensitivity has remained quite high, though varying slightly from one model of x-ray machine to another, depending upon the x-ray scattering characteristics of each model. (author)

Fiber optic fluid detector

Science.gov (United States)

Angel, S.M.

1987-02-27

Particular gases or liquids are detected with a fiber optic element having a cladding or coating of a material which absorbs the fluid or fluids and which exhibits a change of an optical property, such as index of refraction, light transmissiveness or fluoresence emission, for example, in response to absorption of the fluid. The fluid is sensed by directing light into the fiber optic element and detecting changes in the light, such as exit angle changes for example, that result from the changed optical property of the coating material. The fluid detector may be used for such purposes as sensing toxic or explosive gases in the atmosphere, measuring ground water contamination or monitoring fluid flows in industrial processes, among other uses. 10 figs.

High Resolution PET with 250 micrometer LSO Detectors and Adaptive Zoom

International Nuclear Information System (INIS)

Cherry, Simon R.; Qi, Jinyi

2012-01-01

There have been impressive improvements in the performance of small-animal positron emission tomography (PET) systems since their first development in the mid 1990s, both in terms of spatial resolution and sensitivity, which have directly contributed to the increasing adoption of this technology for a wide range of biomedical applications. Nonetheless, current systems still are largely dominated by the size of the scintillator elements used in the detector. Our research predicts that developing scintillator arrays with an element size of 250 (micro)m or smaller will lead to an image resolution of 500 (micro)m when using 18F- or 64Cu-labeled radiotracers, giving a factor of 4-8 improvement in volumetric resolution over the highest resolution research systems currently in existence. This proposal had two main objectives: (i) To develop and evaluate much higher resolution and efficiency scintillator arrays that can be used in the future as the basis for detectors in a small-animal PET scanner where the spatial resolution is dominated by decay and interaction physics rather than detector size. (ii) To optimize one such high resolution, high sensitivity detector and adaptively integrate it into the existing microPET II small animal PET scanner as a 'zoom-in' detector that provides higher spatial resolution and sensitivity in a limited region close to the detector face. The knowledge gained from this project will provide valuable information for building future PET systems with a complete ring of very high-resolution detector arrays and also lay the foundations for utilizing high-resolution detectors in combination with existing PET systems for localized high-resolution imaging.

Autoradiographic measurement of low concentrations of alpha-active nuclides using CR-39 track detectors

International Nuclear Information System (INIS)

Freyer, K.; Dietze, K.; Weisse, S.; Kummer, G.

1991-01-01

An autoradiographic method for the determination of alpha emission rates from plastic packaging materials for VLSI silicon memory devices based on long-time exposure of the samples on CR-39 detectors has been tested. The lower limit of detection will be strongly influenced by the background of the detector material and amounts at times to 0.002 alpha particles cm -2 h -1 after 200 days exposure. A mathematical method for the interpretation of very low track densities is discussed. The first results of its application are presented. (author)

PROXIMAL: a method for Prediction of Xenobiotic Metabolism.

Science.gov (United States)

Yousofshahi, Mona; Manteiga, Sara; Wu, Charmian; Lee, Kyongbum; Hassoun, Soha

2015-12-22

Contamination of the environment with bioactive chemicals has emerged as a potential public health risk. These substances that may cause distress or disease in humans can be found in air, water and food supplies. An open question is whether these chemicals transform into potentially more active or toxic derivatives via xenobiotic metabolizing enzymes expressed in the body. We present a new prediction tool, which we call PROXIMAL (Prediction of Xenobiotic Metabolism) for identifying possible transformation products of xenobiotic chemicals in the liver. Using reaction data from DrugBank and KEGG, PROXIMAL builds look-up tables that catalog the sites and types of structural modifications performed by Phase I and Phase II enzymes. Given a compound of interest, PROXIMAL searches for substructures that match the sites cataloged in the look-up tables, applies the corresponding modifications to generate a panel of possible transformation products, and ranks the products based on the activity and abundance of the enzymes involved. PROXIMAL generates transformations that are specific for the chemical of interest by analyzing the chemical's substructures. We evaluate the accuracy of PROXIMAL's predictions through case studies on two environmental chemicals with suspected endocrine disrupting activity, bisphenol A (BPA) and 4-chlorobiphenyl (PCB3). Comparisons with published reports confirm 5 out of 7 and 17 out of 26 of the predicted derivatives for BPA and PCB3, respectively. We also compare biotransformation predictions generated by PROXIMAL with those generated by METEOR and Metaprint2D-react, two other prediction tools. PROXIMAL can predict transformations of chemicals that contain substructures recognizable by human liver enzymes. It also has the ability to rank the predicted metabolites based on the activity and abundance of enzymes involved in xenobiotic transformation.

Measuring ionizing radiation in the atmosphere with a new balloon-borne detector

Science.gov (United States)

Aplin, K. L.; Briggs, A. A.; Harrison, R. G.; Marlton, G. J.

2017-05-01

Increasing interest in energetic particle effects on weather and climate has motivated development of a miniature scintillator-based detector intended for deployment on meteorological radiosondes or unmanned airborne vehicles. The detector was calibrated with laboratory gamma sources up to 1.3 MeV and known gamma peaks from natural radioactivity of up to 2.6 MeV. The specifications of our device in combination with the performance of similar devices suggest that it will respond to up to 17 MeV gamma rays. Laboratory tests show that the detector can measure muons at the surface, and it is also expected to respond to other ionizing radiation including, for example, protons, electrons (>100 keV), and energetic helium nuclei from cosmic rays or during space weather events. Its estimated counting error is ±10%. Recent tests, when the detector was integrated with a meteorological radiosonde system and carried on a balloon to 25 km altitude, identified the transition region between energetic particles near the surface, which are dominated by terrestrial gamma emissions, to higher-energy particles in the free troposphere.

Investigation of an alternating current plasma as an element selective atomic emission detector for high-resolution capillary gas chromatography and as a source for atomic absorption and atomic emission spectrometry

Science.gov (United States)

Ombaba, Jackson M.

This thesis deals with the construction and evaluation of an alternating current plasma (ACP) as an element-selective detector for high resolution capillary gas chromatography (GC) and as an excitation source for atomic absorption spectrometry (AAS) and atomic emission spectrometry (AES). The plasma, constrained in a quartz discharge tube at atmospheric pressure, is generated between two copper electrodes and utilizes helium as the plasma supporting gas. The alternating current plasma power source consists of a step-up transformer with a secondary output voltage of 14,000 V at a current of 23 mA. The device exhibits a stable signal because the plasma is self-seeding and reignites itself every half cycle. A tesla coil is not required to commence generation of the plasma if the ac voltage applied is greater than the breakdown voltage of the plasma-supporting gas. The chromatographic applications studied included the following: (1) the separation and selective detection of the organotin species, tributyltin chloride (TBT) and tetrabutyltin (TEBT), in environmental matrices including mussels (Mvutilus edullus) and sediment from Boston Harbor, industrial waste water and industrial sludge, and (2) the detection of methylcyclopentadienyl manganesetricarbonyl (MMT) and similar compounds used as gasoline additives. An ultrasonic nebulizer (common room humidifier) was utilized as a sample introduction device for aqueous solutions when the ACP was employed as an atomization source for atomic absorption spectrometry and as an excitation source for atomic emission spectrometry. Plasma diagnostic parameters studied include spatial electron number density across the discharge tube, electronic, excitation and ionization temperatures. Interference studies both in absorption and emission modes were also considered. Figures of merits of selected elements both in absorption and emission modes are reported. The evaluation of a computer-aided optimization program, Drylab GC, using

Time response characteristics of X-ray detector system on Silex-Ⅰ laser facility

International Nuclear Information System (INIS)

Yi Rongqing; He Xiao'an; Li Hang; Du Huabing; Zhang Haiying; Cao Zhurong

2013-01-01

On the Silex-Ⅰ laser facility, the time response characteristics of XRD detector were studied. A laser with a pulse of 32 fs and a wavelength of 800 nm was used to irradiate a plane Au target. X-ray calibrated method of time of exposure X-ray framing camera and time resolution of X-ray streak camera was explored. The time response characteristics of XRD detector and time process of X-ray emission were obtained from experiment. We obtained X-ray calibration method of time of exposure X-ray framing camera and time resolution of X-ray streak camera. (authors)

The developmental spectrum of proximal radioulnar synostosis

Energy Technology Data Exchange (ETDEWEB)

Elliott, Alison M. [University of Manitoba, Winnipeg Regional Health Association Program of Genetics and Metabolism, Winnipeg, MB (Canada); University of Manitoba, Department of Paediatrics and Child Health, Winnipeg, MB (Canada); University of Manitoba, Department of Biochemistry and Medical Genetics, Winnipeg, MB (Canada); University of Manitoba, WRHA Program of Genetics and Metabolism, Departments of Paediatrics and Child Health, Biochemistry and Medical Genetics, Winnipeg, MB (Canada); Kibria, Lisa [University of Manitoba, Department of School of Medical Rehabilitation, Winnipeg, MB (Canada); Reed, Martin H. [University of Manitoba, Department of Paediatrics and Child Health, Winnipeg, MB (Canada); University of Manitoba, Department of Biochemistry and Medical Genetics, Winnipeg, MB (Canada); University of Manitoba, Department of Diagnostic Imaging, Winnipeg, MB (Canada)

2010-01-15

Proximal radioulnar synostosis is a rare upper limb malformation. The elbow is first identifiable at 35 days (after conception), at which stage the cartilaginous anlagen of the humerus, radius and ulna are continuous. Subsequently, longitudinal segmentation produces separation of the distal radius and ulna. However, temporarily, the proximal ends are united and continue to share a common perichondrium. We investigated the hypothesis that posterior congenital dislocation of the radial head and proximal radioulnar fusion are different clinical manifestations of the same primary developmental abnormality. Records were searched for ''proximal radioulnar fusion/posterior radial head dislocation'' in patients followed at the local Children's Hospital and Rehabilitation Centre for Children. Relevant radiographic, demographic and clinical data were recorded. Ethics approval was obtained through the University Research Ethics Board. In total, 28 patients met the inclusion criteria. The majority of patients (16) had bilateral involvement; eight with posterior dislocation of the radial head only; five had posterior radial head dislocation with radioulnar fusion and two had radioulnar fusion without dislocation. One patient had bilateral proximal radioulnar fusion and posterior dislocation of the left radial head. Nine patients had only left-sided involvement, and three had only right-sided involvement.The degree of proximal fusion varied, with some patients showing 'complete' proximal fusion and others showing fusion that occurred slightly distal to the radial head: 'partially separated.' Associated disorders in our cohort included Poland syndrome (two patients), Cornelia de Lange syndrome, chromosome anomalies (including tetrasomy X) and Cenani Lenz syndactyly. The suggestion of a developmental relationship between posterior dislocation of the radial head and proximal radioulnar fusion is supported by the fact that both anomalies

Highly accurate determination of relative gamma-ray detection efficiency for Ge detector and its application

International Nuclear Information System (INIS)

Miyahara, H.; Mori, C.; Fleming, R.F.; Dewaraja, Y.K.

1997-01-01

When quantitative measurements of γ-rays using High-Purity Ge (HPGe) detectors are made for a variety of applications, accurate knowledge of oy-ray detection efficiency is required. The emission rates of γ-rays from sources can be determined quickly in the case that the absolute peak efficiency is calibrated. On the other hand, the relative peak efficiencies can be used for determination of intensity ratios for plural samples and for comparison to the standard source. Thus, both absolute and relative detection efficiencies are important in use of γ-ray detector. The objective of this work is to determine the relative gamma-ray peak detection efficiency for an HPGe detector with the uncertainty approaching 0.1% . We used some nuclides which emit at least two gamma-rays with energies from 700 to 2400 keV for which the relative emission probabilities are known with uncertainties much smaller than 0.1%. The relative peak detection efficiencies were calculated from the measurements of the nuclides, 46 Sc, 48 Sc, 60 Co and 94 Nb, emitting two γ- rays with the emission probabilities of almost unity. It is important that various corrections for the emission probabilities, the cascade summing effect, and the self-absorption are small. A third order polynomial function on both logarithmic scales of energy and efficiency was fitted to the data, and the peak efficiency predicted at certain energy from covariance matrix showed the uncertainty less than 0.5% except for near 700 keV. As an application, the emission probabilities of the 1037.5 and 1212.9 keV γ-rays for 48 Sc were determined using the function of the highly precise relative peak efficiency. Those were 0.9777+0,.00079 and 0.02345+0.00017 for the 1037.5 and 1212.9 keV γ-rays, respectively. The sum of these probabilities is close to unity within the uncertainty which means that the certainties of the results are high and the accuracy has been improved considerably

Calibration of a detector by activation with a continuous neutron source used as a transfer standard for measuring pulsed neutron beams

International Nuclear Information System (INIS)

Moreno, Jose; Silva, Patricio; Birstein, Lipo; Soto, Leopoldo

2002-01-01

This paper presents a method for calibrating activation detectors. These detectors will be used as transfer standard in measuring neutron fluxes produced by pulsed plasma sources. A standard neutron source is used as a secondary standard. The activation detector is being shielded in order to substantially reduce detection of gamma emission coming from the source. The detector's calibration factor is obtained by considering also the standard neutron source as a free source of gamma radiation so that the measurements can be done without quickly withdrawing the neutron source as it is usually done. This will substantially simplify the traditionally established method (JM)

Performance Study of an aSi Flat Panel Detector for Fast Neutron Imaging of Nuclear Waste

Energy Technology Data Exchange (ETDEWEB)

Schumann, M.; Mauerhofer, E. [Institute of Energy and Climate Research - Nuclear Waste Management and Reactor Safety, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Engels, R.; Kemmerling, G. [Central Institute for Engineering, Electronics and Analytics - Electronic Systems, Forschungszentrum Juelich GmbH, 52425 Juelich (Germany); Frank, M. [MATHCCES - Department of Mathematics, RWTH Aachen University, 52062 Aachen (Germany); Havenith, A.; Kettler, J.; Klapdor-Kleingrothaus, T. [Institute of Nuclear Engineering and Technology Transfer, RWTH Aachen University, 52062 Aachen (Germany); Schitthelm, O. [Corporate Technology, Siemens AG, 91058 Erlangen (Germany)

2015-07-01

Radioactive waste must be characterized to check its conformance for intermediate storage and final disposal according to national regulations. For the determination of radio-toxic and chemo-toxic contents of radioactive waste packages non-destructive analytical techniques are preferentially used. Fast neutron imaging is a promising technique to assay large and dense items providing, in complementarity to photon imaging, additional information on the presence of structures in radioactive waste packages. Therefore the feasibility of a compact Neutron Imaging System for Radioactive waste Analysis (NISRA) using 14 MeV neutrons is studied in a cooperation framework of Forschungszentrum Juelich GmbH, RWTH Aachen University and Siemens AG. However due to the low neutron emission of neutron generators in comparison to research reactors the challenging task resides in the development of an imaging detector with a high efficiency, a low sensitivity to gamma radiation and a resolution sufficient for the purpose. The setup is composed of a commercial D-T neutron generator (Genie16GT, Sodern) with a surrounding shielding made of polyethylene, which acts as a collimator and an amorphous silicon flat panel detector (aSi, 40 x 40 cm{sup 2}, XRD-1642, Perkin Elmer). Neutron detection is achieved using a general propose plastic scintillator (EJ-260, Eljen Technology) linked to the detector. The thermal noise of the photodiodes is reduced by employing an entrance window made of aluminium. Optimal gain and integration time for data acquisition are set by measuring the response of the detector to the radiation of a 500 MBq {sup 241}Am-source. Detector performance was studied by recording neutron radiography images of materials with various, but well known, chemical compositions, densities and dimensions (Al, C, Fe, Pb, W, concrete, polyethylene, 5 x 8 x 10 cm{sup 3}). To simulate gamma-ray emitting waste radiographs in presence of a gamma-ray sources ({sup 60}Co, {sup 137}Cs, {sup 241

Pin Diode Detector For Radiation Field Monitoring In A Current Mode

International Nuclear Information System (INIS)

Beck, A.; Wengrowicz, U.; Kadmon, Y.; Tirosh, D.; Osovizky, A.; Vulasky, E.; Tal, N.

1999-01-01

Thus paper presents calculations and tests made for a detector based on a bare Pin diode and a Pin diode coupled to a plastic scintillator. These configurations have a variety of applications in radiation field monitoring. For example, the Positron Emission Tomography (PET) technology which becomes an established diagnostic imaging modality. Flour-18 is one of the major isotopes being used by PET imaging. The PET method utilizes short half life β + radioisotopes which, by annihilation, produce a pair of high energy photons (511 keV). Fluoro-deoxyglucose producers are required to meet federal regulations and licensing requirements. Some of the regulations are related to the production in chemistry modules regarding measuring the Start Of Synthesis (SOS) activity and verifying the process repeatability. Locating a radiation detector based on Pin diode inside the chemistry modules is suitable for this purpose. The dimensions of a Pin diode based detector can be small, with expected linearity over several scale decades

An anatomical study of the proximal aspect of the medial femoral condyle to define the proximal-distal condylar length

Directory of Open Access Journals (Sweden)

Chia-Ming Chang

2017-01-01

Full Text Available Objective: Despite its possible role in knee arthroplasty, the proximal-distal condylar length (PDCL of the femur has never been reported in the literature. We conducted an anatomic study of the proximal aspect of the medial femoral condyle to propose a method for measuring the PDCL. Materials and Methods: Inspection of dried bone specimens was carried out to assure the most proximal condylar margin (MPCM as the eligible starting point to measure the PDCL. Simulation surgery was performed on seven pairs of cadaveric knees to verify the clinical application of measuring the PDCL after locating the MPCM. Interobserver reliability of this procedure was also analyzed. Results: Observation of the bone specimens showed that the MPCM is a concavity formed by the junction of the distal end of the supracondylar ridge and the proximal margin of the medial condyle. This anatomically distinctive structure made the MPCM an unambiguous landmark. The cadaveric simulation surgical dissection demonstrated that the MPCM is easily accessed in a surgical setting, making the measurement of the PDCL plausible. The intraclass correlation coefficient was 0.78, indicating good interobserver reliability for this technique. Conclusion: This study has suggested that the PDCL can be measured based on the MPCM in a surgical setting. PDCL measurement might be useful in joint line position management, selection of femoral component sizes, and other applications related to the proximal-distal dimension of the knee. Further investigation is required.

Evaluation and Management of Proximal Humerus Fractures

Directory of Open Access Journals (Sweden)

Ekaterina Khmelnitskaya

2012-01-01

Full Text Available Proximal humerus fractures are common injuries, especially among older osteoporotic women. Restoration of function requires a thorough understanding of the neurovascular, musculotendinous, and bony anatomy. This paper addresses the relevant anatomy and highlights various management options, including indication for arthroplasty. In the vast majority of cases, proximal humerus fractures may be treated nonoperatively. In the case of displaced fractures, when surgical intervention may be pursued, numerous constructs have been investigated. Of these, the proximal humerus locking plate is the most widely used. Arthroplasty is generally reserved for comminuted 4-part fractures, head-split fractures, or fractures with significant underlying arthritic changes. Reverse total shoulder arthroplasty is reserved for patients with a deficient rotator cuff, or highly comminuted tuberosities.

The Life Saving Effects of Hospital Proximity

DEFF Research Database (Denmark)

Bertoli, Paola; Grembi, Veronica

We assess the lifesaving effect of hospital proximity using data on fatality rates of road-traffic accidents. While most of the literature on this topic is based on changes in distance to the nearest hospital triggered by hospital closures and use OLS estimates, our identification comes from......) increases the fatality rate by 13.84% on the sample average. This is equal to a 0.92 additional death per every 100 accidents. We show that OLS estimates provide a downward biased measure of the real effect of hospital proximity because they do not fully solve spatial sorting problems. Proximity matters...... more when the road safety is low; the emergency service is not properly organized, and the nearest hospital has lower quality standards....

Silicon detectors

International Nuclear Information System (INIS)

Klanner, R.

1984-08-01

The status and recent progress of silicon detectors for high energy physics is reviewed. Emphasis is put on detectors with high spatial resolution and the use of silicon detectors in calorimeters. (orig.)

Dissociative electron attachment negative ion mass spectrometry: a chlorine-specific detector for gas chromatography

Science.gov (United States)

Curtis, Jonathan M.; Boyd, Robert K.

1997-11-01

This work describes the application of negative ion chemical ionization, optimized for dissociative electron attachment (DEA), to location of unknown trace chlorinated compounds in complex gas chromatograms by selected ion recording (SIR) of m / z 35 and 37. The DEA-SIR technique is compared with other GC detectors, including the electron capture detector, electrolytic conductivity detector, the atomic emission detector and the chemical reaction interface mass spectrometry method, with respect to selectivity for chlorine, sensitivity, linear dynamic range, and general robustness and ease of use. When applied to quantitative analysis of target analytes such as polychlorobiphenyls, the DEA-SIR method has potential problems arising from the possibility of suppression effects due to abundant co-eluting components, and possible alleviating measures are discussed. In addition to these practical investigations, literature information on the fundamental physical and chemical phenomena underlying the DEA process is summarized in order to guide future work on extension to other compound types and on general improvements to the technique.

Comparison of CdZnTe neutron detector models using MCNP6 and Geant4

Science.gov (United States)

Wilson, Emma; Anderson, Mike; Prendergasty, David; Cheneler, David

2018-01-01

The production of accurate detector models is of high importance in the development and use of detectors. Initially, MCNP and Geant were developed to specialise in neutral particle models and accelerator models, respectively; there is now a greater overlap of the capabilities of both, and it is therefore useful to produce comparative models to evaluate detector characteristics. In a collaboration between Lancaster University, UK, and Innovative Physics Ltd., UK, models have been developed in both MCNP6 and Geant4 of Cadmium Zinc Telluride (CdZnTe) detectors developed by Innovative Physics Ltd. Herein, a comparison is made of the relative strengths of MCNP6 and Geant4 for modelling neutron flux and secondary γ-ray emission. Given the increasing overlap of the modelling capabilities of MCNP6 and Geant4, it is worthwhile to comment on differences in results for simulations which have similarities in terms of geometries and source configurations.

Proximal Focal Femoral Deficiency in Ibadan a Developing ...

African Journals Online (AJOL)

The cultural aversion to amputation in our environment makes it difficult to employ that option of treatment. Proximal focal femoral deficiency in Ibadan a developing country's perspective and a review of the literature. Keywords: Proximal focal femoral deficiency , congenital malformations , limb malformations , lower limb ...

[Avulsion of the Proximal Hamstring Insertion. Case Reports].

Science.gov (United States)

Mizera, R; Harcuba, R; Kratochvíl, J

2016-01-01

Proximal hamstring avulsion is an uncommon muscle injury with a lack of consensus on indications and the timing and technique of surgery. Poor clinical symptoms and difficulties in the diagnostic process can lead to a false diagnosis. The authors present three cases of proximal hamstring avulsion, two complete and one partial ruptures of the biceps femoris muscle. MRI and ultrasound scans were used for optimal treatment alignment. Acute surgery reconstruction (hamstring strength. Two interesting systematic reviews published on the treatment of proximal hamstring avulsion are discussed in the final part of the paper. Key words: hamstring, rupture, avulsion.

A dual-mode proximity sensor with integrated capacitive and temperature sensing units

International Nuclear Information System (INIS)

Qiu, Shihua; Huang, Ying; He, Xiaoyue; Sun, Zhiguang; Liu, Ping; Liu, Caixia

2015-01-01

The proximity sensor is one of the most important devices in the field of robot application. It can accurately provide the proximity information to assistant robots to interact with human beings and the external environment safely. In this paper, we have proposed and demonstrated a dual-mode proximity sensor composed of capacitive and resistive sensing units. We defined the capacitive type proximity sensor perceiving the proximity information as C-mode and the resistive type proximity sensor detecting as R-mode. Graphene nanoplatelets (GNPs) were chosen as the R-mode sensing material because of its high performance. The dual-mode proximity sensor presents the following features: (1) the sensing distance of the dual-mode proximity sensor has been enlarged compared with the single capacitive proximity sensor in the same geometrical pattern; (2) experiments have verified that the proposed sensor can sense the proximity information of different materials; (3) the proximity sensing capability of the sensor has been improved by two modes perceive collaboratively, for a plastic block at a temperature of 60 °C: the R-mode will perceive the proximity information when the distance d between the sensor and object is 6.0–17.0 mm and the C-mode will do that when their interval is 0–2.0 mm; additionally two modes will work together when the distance is 2.0–6.0 mm. These features indicate our transducer is very valuable in skin-like sensing applications. (paper)

Characterization of 1.2×1.2 mm2 silicon photomultipliers with Ce:LYSO, Ce:GAGG, and Pr:LuAG scintillation crystals as detector modules for positron emission tomography

International Nuclear Information System (INIS)

Omidvari, N.; Sharma, R.; Schneider, F.R.; Ziegler, S.I.; Ganka, T.R.; Paul, S.

2017-01-01

The design of a positron emission tomography (PET) scanner is specially challenging since it should not compromise high spatial resolution, high sensitivity, high count-rate capability, and good energy and time resolution. The geometrical design of the system alongside the characteristics of the individual PET detector modules contributes to the overall performance of the scanner. The detector performance is mainly influenced by the characteristics of the photo-detector and the scintillation crystal. Although silicon photomultipliers (SiPMs) have already proven to be promising photo-detectors for PET, their performance is highly influenced by micro-cell structure and production technology. Therefore, five types of SiPMs produced by KETEK with an active area size of 1.2 × 1.2 mm 2 were characterized in this study. The SiPMs differed in the production technology and had micro-cell sizes of 25, 50, 75, and 100 μm. Performance of the SiPMs was evaluated in terms of their breakdown voltage, temperature sensitivity, dark count rate, and correlated noise probability. Subsequently, energy resolution and coincidence time resolution (CTR) of the SiPMs were measured with five types of crystals, including two Ce:LYSO, two Ce:GAGG, and one Pr:LuAG. Two crystals with a geometry of 1.5 × 1.5 × 6 mm 3 were available from each type. The best CTR achieved was ∼ 240 ps, which was obtained with the Ce:LYSO crystals coupled to the 50 μm SiPM produced with the trench technology. The best energy resolution for the 511 keV photo-peak was ∼ 11% and was obtained with the same SiPM coupled to the Ce:GAGG crystals.

Mobility and powering of large detectors. Moving large detectors

International Nuclear Information System (INIS)

Thompson, J.

1977-01-01

The possibility is considered of moving large lepton detectors at ISABELLE for readying new experiments, detector modifications, and detector repair. A large annex (approximately 25 m x 25 m) would be built adjacent to the Lepton Hall separated from the Lepton Hall by a wall of concrete 11 m high x 12 m wide (for clearance of the detector) and approximately 3 m thick (for radiation shielding). A large pad would support the detector, the door, the cryogenic support system and the counting house. In removing the detector from the beam hall, one would push the pad into the annex, add a dummy beam pipe, bake out the beam pipe, and restack and position the wall on a small pad at the door. The beam could then operate again while experimenters could work on the large detector in the annex. A consideration and rough price estimate of various questions and proposed solutions are given

Study of microwave emission from a dense plasma focus

International Nuclear Information System (INIS)

Gerdin, G.; Venneri, F.; Tanisi, M.

1985-01-01

Microwave emission was detected in a 12.5 kJ dense plasma focus, using microwave horns and detectors placed in various locations outside the device. The results show that the parallel plates connecting the focus to its capacitor banks act as antennas and transmission lines, rather than wave guides. Subsequent measurements were performed with a microwave detector (R-band) attached to the focus anode, directly looking into the coaxial gun region, allowing to restrict the microwave emitting region to the muzzle end of the focus. The microwave frequency spectrum, determined with a time of flight detection system, strongly suggests the lower hybrid instability as the driving mechanism of the emissions. Comparing the time sequence of the emissions with those of other observable phenomena in the focus, a model was developed, to explain the possible relationship between the generation of microwave radiation and turbulence induced resistivity in the focus pinch. According to the model, microwaves and enhanced resistivity are caused by current driven instabilities occurring in the current sheath produced at the outer boundary of the pinch during the initial compression phase. Comparisons of the model predictions with observed experimental results are presented, including time resolved measurements of the pinch resistivity

Analysis of changes in environmental radiation, and three types of environmental radiation detector performance comparisons

International Nuclear Information System (INIS)

Park, J.H; Seo, J.H; Park, S.M; Yu, B.N; Park, J.H; Joo, K.S

2013-06-01

High-pressure ion chamber (GE Reuter-Stokes, HPIC), accuracy is high but the high price and do not have the ability nuclide analysis is a disadvantage. NaI(Tl) and PMT scintillation detector of radioactive materials can be divided. Environmental radiation measurements using a semiconductor with SiPM detector PMT to replace the value of the results were compared. SiPM detector using radiation environment were measured in the field to verify the accuracy and energy resolution. SiPMs performance as environmental radiation measurement equipment and radioactive material distinction as a personal dosimeter based technology, using the above results were prepared. The interest on the environmental radiation due to the Fukushima power plant crisis in Japan has been growing concern about the radiation environment of the relatively close proximity Korea is a very heightened state. Could be confirmed in the radiation environment of nuclear power plants around the analysis and performance of the next generation of environmental radiation meter. Fukushima power plants accident after 2 years, the equipment installed by this analysis meets the performance as a radiation detector could be confirmed as follows. CANA Inc. developed by radionuclides classification of using man-made and natural radionuclides and man-made radionuclides separated, ensure the value of the results were analyzed. Could be and alternative to the conventional detector energy resolution ( 137 CS<15%) and linearity (<15%) to satisfy the performance requirements of the measurement result of environmental radiation detector is considered. SiPM radiation environment changes and HPIC and NaI(TI) scintillation detector installed in Korea of the Fukushima power plant after the accident, radiation environment using a small alternative was to verify the accuracy of the measuring equipment. A big difference in performance as invisible by comparison with the large detector Assay miniaturization rough as a personal

A Regularized Algorithm for the Proximal Split Feasibility Problem

Directory of Open Access Journals (Sweden)

Zhangsong Yao

2014-01-01

Full Text Available The proximal split feasibility problem has been studied. A regularized method has been presented for solving the proximal split feasibility problem. Strong convergence theorem is given.

Cancer rates after the Three Mile Island nuclear accident and proximity of residence to the plant.

Science.gov (United States)

Hatch, M C; Wallenstein, S; Beyea, J; Nieves, J W; Susser, M

1991-06-01

In the light of a possible link between stress and cancer promotion or progression, and of previously reported distress in residents near the Three Mile Island (TMI) nuclear power plant, we attempted to evaluate the impact of the March 1979 accident on community cancer rates. Proximity of residence to the plant, which related to distress in previous studies, was taken as a possible indicator of accident stress; the postaccident pattern in cancer rates was examined in 69 "study tracts" within a 10-mile radius of TMI, in relation to residential proximity. A modest association was found between postaccident cancer rates and proximity (OR = 1.4; 95% CI = 1.3, 1.6). After adjusting for a gradient in cancer risk prior to the accident, the odds ratio contrasting those closest to the plant with those living farther out was 1.2 (95% CI = 1.0, 1.4). A postaccident increase in cancer rates near the Three Mile Island plant was notable in 1982, persisted for another year, and then declined. Radiation emissions, as modeled mathematically, did not account for the observed increase. Interpretation in terms of accident stress is limited by the lack of an individual measure of stress and by uncertainty about whether stress has a biological effect on cancer in humans. An alternative mechanism for the cancer increase near the plant is through changes in care-seeking and diagnostic practice arising from postaccident concern.

Positron emission tomography camera

International Nuclear Information System (INIS)

Anon.

1987-01-01

A positron emission tomography camera having a plurality of detector planes positioned side-by-side around a patient area to detect radiation. Each plane includes a plurality of photomultiplier tubes and at least two rows of scintillation crystals on each photomultiplier tube extend across to adjacent photomultiplier tubes for detecting radiation from the patient area. Each row of crystals on each photomultiplier tube is offset from the other rows of crystals, and the area of each crystal on each tube in each row is different than the area of the crystals on the tube in other rows for detecting which crystal is actuated and allowing the detector to detect more inter-plane slides. The crystals are offset by an amount equal to the length of the crystal divided by the number of rows. The rows of crystals on opposite sides of the patient may be rotated 90 degrees relative to each other

Proximity approach to problems in topology and analysis

CERN Document Server

Naimpally, Somashekhar

2009-01-01

Dieses Buch konzentriert das aktuelle Gesamtwissen zum Proximity-Konzept und stellt es dem Leser in gut strukturierter Form dar. Hauptaugenmerk liegt auf den vielfältigen Möglichkeiten, die sich aus dem Proximity-Konzept der räumlichen Nähe und seiner Verallgemeinerung im Nearness-Konzept ergeben.

New design of a quasi-monolithic detector module with DOI capability for small animal pet

International Nuclear Information System (INIS)

Chung, Yong Hyun; Lee, Seung-Jae; Baek, Cheol-Ha; Choi, Yong

2008-01-01

We report a new design of a detector module with depth of interaction (DOI) based on a quasi-monolithic LSO crystal, a multi-channel sensor, and maximum-likelihood position-estimation (MLPE) algorithm. Light transport and detection were modeled in a quasi-monolithic crystal using DETECT2000 code, with lookup tables (LUTs) built by simulation. Events were well separated by applying the MLPE method within 2.0 mm spatial resolution in both trans-axial and DOI directions. These results demonstrate that the proposed detector provides dependable positioning capability for small animal positron emission tomography (PET)

Recent Results with a segmented Hybrid Photon Detector for a novel parallax-free PET Scanner for Brain Imaging

CERN Document Server

Braem, André; Joram, Christian; Mathot, Serge; Séguinot, Jacques; Weilhammer, Peter; Ciocia, F; De Leo, R; Nappi, E; Vilardi, I; Argentieri, A; Corsi, F; Dragone, A; Pasqua, D

2007-01-01

We describe the design, fabrication and test results of a segmented Hybrid Photon Detector with integrated auto-triggering front-end electronics. Both the photodetector and its VLSI readout electronics are custom designed and have been tailored to the requirements of a recently proposed novel geometrical concept of a Positron Emission Tomograph. Emphasis is laid on the PET specific features of the device. The detector has been fabricated in the photocathode facility at CERN.

Proximity effects in ferromagnet/superconductor structures

International Nuclear Information System (INIS)

Yu, H.L.; Sun, G.Y.; Yang, L.Y.; Xing, D.Y.

2004-01-01

The Nambu spinor Green's function approach is applied to study proximity effects in ferromagnet/superconductor (FM/SC) structures. They include the induced superconducting order parameter and density of states (DOS) with superconducting feature on the FM side, and spin-dependent DOS within the energy gap on the SC side. The latter indicates an appearance of gapless superconductivity and a coexistence of ferromagnetism and superconductivity in a small regime near the interface. The influence of exchange energy in FM and barrier strength at interface on the proximity effects is discussed

Potential applications of electron emission membranes in medicine

Energy Technology Data Exchange (ETDEWEB)

Bilevych, Yevgen [Fraunhofer Institute for Reliability and Microintegration (IZM), Berlin (Germany); University of Bonn, Bonn (Germany); Brunner, Stefan E. [Delft University of Technology, Delft (Netherlands); Stefan Meyer Institute for Subatomic Physics, Austrian Academy of Sciences, Vienna (Austria); Chan, Hong Wah; Charbon, Edoardo [Delft University of Technology, Delft (Netherlands); Graaf, Harry van der, E-mail: vdgraaf@nikhef.nl [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Hagen, Cornelis W. [Delft University of Technology, Delft (Netherlands); Nützel, Gert; Pinto, Serge D. [Photonis, Roden (Netherlands); Prodanović, Violeta [Delft University of Technology, Delft (Netherlands); Rotman, Daan [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); University of Amsterdam, Amsterdam (Netherlands); Santagata, Fabio [State Key Lab for Solid State Lighti Changzhou base, F7 R& D HUB 1, Science and Education Town, Changzhou 213161, Jangsu Province (China); Sarro, Lina; Schaart, Dennis R. [Delft University of Technology, Delft (Netherlands); Sinsheimer, John; Smedley, John [Brookhaven National Laboratory, Upton, NY (United States); Tao, Shuxia; Theulings, Anne M.M.G. [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands)

2016-02-11

With a miniaturised stack of transmission dynodes, a noise free amplifier is being developed for the detection of single free electrons, with excellent time- and 2D spatial resolution and efficiency. With this generic technology, a new family of detectors for individual elementary particles may become possible. Potential applications of such electron emission membranes in medicine are discussed.

Cherenkov angle and charge reconstruction with the RICH detector of the AMS experiment

CERN Document Server

Barão, F; Borges, J; Gonçalves, P; Pimenta, M; Pérez, I

2003-01-01

The Alpha Magnetic Spectrometer experiment to be installed on the International Space Station will be equipped with a proximity focusing Ring Imaging Cherenkov (RICH) detector, for measurements of particle electric charge and velocity. In this note, two possible methods for reconstructing the Cherenkov angle and the electric charge with the RICH are discussed. A Likelihood method for the Cherenkov angle reconstruction was applied leading to a velocity determination for protons with a resolution of around 0.1%. The existence of a large fraction of background photons which can vary from event to event implied a charge reconstruction method based on an overall efficiency estimation on an event-by-event basis.

2011 ATLAS Detector Performance - ID and Forward detectors

CERN Document Server

Davies‎, E; The ATLAS collaboration; Abdel Khalek, S

2012-01-01

This poster describes the performance of 2 parts of ATLAS: - The Inner Detector which consists of 3 subdetectors: the Pixel detector, the SemiConductor Tracker (or SCT) and the Transition Radiation Tracker (or TRT). Here, we report on Pixel detector and SCT performance over 2011. - ALFA detector which will determine the absolute luminosity of the CERN LHC at the ATLAS Interaction Point (IP), and the total proton-proton cross section, by tracking elastically scattered protons at very small angles in the limit of the Coulomb Nuclear interference region.

Radiographic and Computed Tomographic Configuration of Incomplete Proximal Fractures of the Proximal Phalanx in Horses Not Used for Racing.

Science.gov (United States)

Brünisholz, Hervé P; Hagen, Regine; Fürst, Anton E; Kuemmerle, Jan M

2015-10-01

To characterize the configuration of incomplete proximal fractures of the proximal phalanx (P1) in horses not used for racing and compare radiographic with computed tomography (CT) findings. Historical cohort. Twenty-four horses with incomplete fractures of P1. Medical records of horses not used for racing diagnosed with an incomplete proximal fracture of P1 based on clinical and radiographic examination and confirmed by CT between 2008 and 2013 were retrieved. Radiographs and CT studies of these horses were analyzed using a subjective grading system and by measuring variables that characterized fracture configuration. Twenty-four horses were included (20 Warmbloods) with a mean age of 9.5 years and mean body weight of 574 kg. Fourteen forelimbs and 10 hind limbs were affected. Mean duration of lameness was 8.7 weeks. Computed tomography was superior to radiography in both identifying the fracture and determining fracture size and location. On CT, 92% of fractures were located in the mid-sagittal plane. Mean proximodistal length of the fracture was 13 mm. Fractures were frequently not bicortical. Fractures in forelimbs were located significantly more dorsally than fractures in hind limbs. A distinct fracture pattern with 2 subchondral lines running parallel in close proximity to each other was identified in 54% of cases. Incomplete proximal fractures of P1 have significant variation in their configurations, especially their dorsopalmar/-plantar location. Computed tomography examination allowed clear identification of the fracture configurations and was superior to radiography. © Copyright 2015 by The American College of Veterinary Surgeons.

Infrared detectors

CERN Document Server

Rogalski, Antonio

2010-01-01

This second edition is fully revised and reorganized, with new chapters concerning third generation and quantum dot detectors, THz detectors, cantilever and antenna coupled detectors, and information on radiometry and IR optics materials. Part IV concerning focal plane arrays is significantly expanded. This book, resembling an encyclopedia of IR detectors, is well illustrated and contains many original references … a really comprehensive book.-F. Sizov, Institute of Semiconductor Physics, National Academy of Sciences, Kiev, Ukraine

Characterization of Multianode Photomultiplier Tubes for a Cherenkov Detector

Science.gov (United States)

Benninghoff, Morgen; Turisini, Matteo; Kim, Andrey; Benmokhtar, Fatiha; Kubarovsky, Valery; Duquesne University Collaboration; Jefferson Lab Collaboration

2017-09-01

In the Fall of 2017, Jefferson Lab's CLAS12 (CEBAF Large Acceptance Spectrometer) detector is expecting the addition of a RICH (ring imaging Cherenkov) detector which will allow enhanced particle identification in the momentum range of 3 to 8 GeV/c. RICH detectors measure the velocity of charged particles through the detection of produced Cherenkov radiation and the reconstruction of the angle of emission. The emitted Cherenkov photons are detected by a triangular-shaped grid of 391 multianode photomultiplier tubes (MAPMTs) made by Hamamatsu. The custom readout electronics consist of MAROC (multianode read out chip) boards controlled by FPGA (Field Programmable Gate Array) boards, and adapters used to connect the MAROC boards and MAPMTs. The focus of this project is the characterization of the MAPMTs with the new front end electronics. To perform these tests, a black box setup with a picosecond diode laser was constructed with low and high voltage supplies. A highly automated procedure was developed to acquire data at different combinations of high voltage values, light intensities and readout electronics settings. Future work involves using the collected data in calibration procedures and analyzing that data to resolve the best location for each MAPMT. SULI, NSF.

The development of an innovative, real-time monitor for airborne alpha emissions

International Nuclear Information System (INIS)

Gritzo, R.; Fowler, M.; Wouters, J.

1994-01-01

Los Alamos National Laboratory (LANL) is developing a technology for on-line, real-time monitoring of incinerator stacks for low levels of airborne alpha activity. Referred to as the Large-Volume Flow Thru Detector System (LVFTDS), this technology uses a unique design for sensitive, real-time measurements of alpha particle emissions. Scintillating plates are stacked close together so that alpha-particle emissions in the flowing gas stream strike a plate. The light pulses produced when the alpha particle strikes the plate are registered by photomultiplier tubes and processed to determine the concentration of alpha emitting radionuclides present in the air. This technology directly addresses the public's demand for fast responding, high sensitivity effluent monitoring systems. With Department of Energy (DOE) EM-50 funding LANL has fabricated a beach-top proof of concept detector system and is conducting tests to evaluate its performance. A second generation prototype is being designed, based on requirements driven by potential field test sites. An industrial partner is being solicited to license the technology. Field trials of a full-scale detector system are planned for fiscal year 1995. In this paper the LVFTDS technology is explained, including the measured performance of a prototype detector. The advantages, disadvantages, and other ramifications of applying this technology to incinerator effluent monitoring are also discussed. An overview of the development effort is also provided

Regionalization of municipal solid waste management in Japan: balancing the proximity principle with economic efficiency.

Science.gov (United States)

Okuda, Itaru; Thomson, Vivian E

2007-07-01

The proximity principle - disposing of waste close to its origin - has been a central value in municipal solid waste (MSW) management in Japan for the last 30 years and its widespread adoption has helped resolve numerous "Not in My Backyard" issues related to MSW management. However, MSW management costs have soared, in large part because of aggressive recycling efforts and because most MSW is incinerated in a country that has scarce landfill capacity. In addition, smaller, less sophisticated incinerators have been closed because of high dioxin emissions. Rising costs combined with the closure of smaller incinerators have shifted MSW management policy toward regionalization, which is the sharing of waste management facilities across municipalities. Despite the increased use of regionalized MSW facilities, the proximity principle remains the central value in Japanese MSW management. Municipal solid waste management has become increasingly regionalized in the United States, too, but different driving forces are at work in these two countries. The transition to regionalized MSW management in Japan results from strong governmental control at all levels, with the central government providing funds and policy direction and prefectures and municipalities being the primary implementing authorities. By contrast, market forces are a much stronger force with US MSW management, where local governments - with state government oversight - have primary responsibility for MSW management. We describe recent changes in Japan's MSW programs. We examine the connections between MSW facility regionalization, on the one hand, and, on the other hand, the proximity principle, coordination among local governments, central government control, and financing mechanisms.

A Prototype Large Area Detector Module for Muon Scattering Tomography

Energy Technology Data Exchange (ETDEWEB)

Steer, C.A.; Boakes, J.; Burns, J.; Snow, S.; Stapleton, M.; Thompson, L.F.; Quillin, S. [AWE Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

2015-07-01

Abstract-Shielded special nuclear materials (SNM) are of concern as some fissile isotopes have low gamma and neutron emission rates. These materials are also easily shielded to the point where their passive emissions are comparable to background. Consequently, shielded SNM is very challenging for passive radiation detection portals which scan cargo containers. One potential solution for this is to utilise the natural cosmic ray muon background and examine how these muons scatter from materials inside the container volume, terms; the muon scattering tomography (MST) technique measures the three-dimensional localised scattering at all points within a cargo container, providing a degree of material discrimination. There is the additional benefit that the MST signal increases with the presence of more high density shielding materials, in contrast to passive radiation detection. Simulations and calculations suggest that the effectiveness of the technique is sensitive to the tracking accuracy amongst other parameters, motivating the need to develop practical detector systems that are capable of tracking cosmic ray muons. To this end, we have constructed and tested a 2 m by 2 m demonstration module based on gaseous drift chambers and triggered by a large area scintillator-based detector, which is readout by wavelength shifting fibres. We discuss its design, construction, characterisation and operational challenges. (authors)

SU-G-JeP1-13: Innovative Tracking Detector for Dose Monitoring in Hadron Therapy: Realization and Monte Carlo Simulations

Energy Technology Data Exchange (ETDEWEB)

Rucinski, A; Mancini-Terracciano, C; Paramatti, R; Pinci, D; Russomando, A; Voena, C; Rucinski, A [Istituto Nazionale di Fisica Nucleare - Sezione di Roma, Rome, Rome (Italy); Battistoni, G; Muraro, S [Istituto Nazionale di Fisica Nucleare - Sezione di Milano, Milano, Milano (Italy); Collamati, F; Faccini, R; Camillocci, E Solfaroli [Istituto Nazionale di Fisica Nucleare - Sezione di Roma, Italy, Dipartiment, Rome, Rome (Italy); Collini, F [Istituto Nazionale di Fisica Nucleare - Sezione di Pisa, Pisa, Pisa (Italy); De Lucia, E; Piersanti, L; Toppi, M [Laboratori Nazionali di Frascati, Frascati (rome), Rome (Italy); Frallicciardi, P [Museo Storico della Fisica e Centro Studi e Ricerche E. Fermi, Rome, Rome (Italy); Marafini, M [Istituto Nazionale di Fisica Nucleare - Sezione di Roma, Museo Storico dell, Rome, Rome (Italy); Patera, V; Sciubba, A [Istituto Nazionale di Fisica Nucleare - Sezione di Roma, Dipartimento di Sc, Rome, Rome (Italy); and others

2016-06-15

Purpose: Development of strategies to monitor range uncertainties is necessary to improve treatment planning in Charged Particle Therapy (CPT) and fully exploit the advantages of ion beams. Our group developed (within the framework of the INSIDE project funded by the Italian research ministry) and is currently building a compact detector Dose Profiler (DP) able to backtrack charged secondary particles produced in the patient during the irradiation. Furthermore we are studying monitoring strategy exploiting charged secondary emission profiles to control the range of the ion beam. Methods: This contribution reports on the DP detector design and construction status. The detector consists of a charged secondary tracker composed of scintillating fiber layers and a LYSO calorimeter for particles energy measurement.The detector layout has been optimized using the FLUKA Monte Carlo (MC) simulation software. The simulation of a 220 MeV Carbon beam impinging on a PMMA target has been performed to study the detector response, exploiting previous secondary radiation measurements performed by our group. The emission profile of charged secondary particles was reconstructed backtracking the particles to their generation point to benchmark the DP performances. Results: The DP construction status, including the technological details will be presented. The feasibility of range monitoring with DP will be demonstrated by means of MC studies. The correlation of the charged secondary particles emission shape with the position of the Bragg peak (BP) will be shown, as well as the spatial resolution achievable on the BP position estimation (less than 3 mm) in the clinical like conditions. Conclusion: The simulation studies supported the feasibility of an accurate range monitoring technique exploiting the use of charged secondary fragments emitted during the particle therapy treatment. The DP experimental tests are foreseen in 2016, at CNAO particle therapy center in Pavia.

SU-G-JeP1-13: Innovative Tracking Detector for Dose Monitoring in Hadron Therapy: Realization and Monte Carlo Simulations

International Nuclear Information System (INIS)

Rucinski, A; Mancini-Terracciano, C; Paramatti, R; Pinci, D; Russomando, A; Voena, C; Rucinski, A; Battistoni, G; Muraro, S; Collamati, F; Faccini, R; Camillocci, E Solfaroli; Collini, F; De Lucia, E; Piersanti, L; Toppi, M; Frallicciardi, P; Marafini, M; Patera, V; Sciubba, A

2016-01-01

Purpose: Development of strategies to monitor range uncertainties is necessary to improve treatment planning in Charged Particle Therapy (CPT) and fully exploit the advantages of ion beams. Our group developed (within the framework of the INSIDE project funded by the Italian research ministry) and is currently building a compact detector Dose Profiler (DP) able to backtrack charged secondary particles produced in the patient during the irradiation. Furthermore we are studying monitoring strategy exploiting charged secondary emission profiles to control the range of the ion beam. Methods: This contribution reports on the DP detector design and construction status. The detector consists of a charged secondary tracker composed of scintillating fiber layers and a LYSO calorimeter for particles energy measurement.The detector layout has been optimized using the FLUKA Monte Carlo (MC) simulation software. The simulation of a 220 MeV Carbon beam impinging on a PMMA target has been performed to study the detector response, exploiting previous secondary radiation measurements performed by our group. The emission profile of charged secondary particles was reconstructed backtracking the particles to their generation point to benchmark the DP performances. Results: The DP construction status, including the technological details will be presented. The feasibility of range monitoring with DP will be demonstrated by means of MC studies. The correlation of the charged secondary particles emission shape with the position of the Bragg peak (BP) will be shown, as well as the spatial resolution achievable on the BP position estimation (less than 3 mm) in the clinical like conditions. Conclusion: The simulation studies supported the feasibility of an accurate range monitoring technique exploiting the use of charged secondary fragments emitted during the particle therapy treatment. The DP experimental tests are foreseen in 2016, at CNAO particle therapy center in Pavia.

A High Resolution Monolithic Crystal, DOI, MR Compatible, PET Detector. Final-Report

International Nuclear Information System (INIS)

Miyaoka, Robert S.

2012-01-01

The principle objective of this proposal is to develop a positron emission tomography (PET) detector with depth-of-interaction (DOI) positioning capability that will achieve state of the art spatial resolution and sensitivity performance for small animal PET imaging. When arranged in a ring or box detector geometry, the proposed detector module will support 15% absolute detection efficiency. The detector will also be compatible with operation in a MR scanner to support simultaneous multi-modality imaging. The detector design will utilize a thick, monolithic crystal scintillator readout by a two-dimensional array of silicon photomultiplier (SiPM) devices using a novel sensor on the entrance surface (SES) design. Our hypothesis is that our single-ended readout SES design will provide an effective DOI positioning performance equivalent to more expensive dual-ended readout techniques and at a significantly lower cost. Our monolithic crystal design will also lead to a significantly lower cost system. It is our goal to design a detector with state of the art performance but at a price point that is affordable so the technology can be disseminated to many laboratories. A second hypothesis is that using SiPM arrays, the detector will be able to operate in a MR scanner without any degradation in performance to support simultaneous PET/MR imaging. Having a co-registered MR image will assist in radiotracer localization and may also be used for partial volume corrections to improve radiotracer uptake quantitation. The far reaching goal of this research is to develop technology for medical research that will lead to improvements in human health care.

The application of photoconductive detectors to the measurement of x-ray production in laser produced plasmas

International Nuclear Information System (INIS)

Kania, D.R.; Bell, P.; Trebes, J.

1987-08-01

Photoconductive detectors (PCDs) offer an attractive alternative for the measurement of pulsed x-rays from laser produced plasmas. These devices are fast (FWHM ∼100 ps), sensitive and simple to use. We have used InP, GaAs, and Type IIa diamond as PCDs to measure x-rays emission from 100 eV to 100 keV. Specifically, we have used these detectors to measure total radiation yields, corona temperatures, and hot electron generated x-rays from laser produced plasmas. 5 refs., 4 figs

Isotropic gates and large gamma detector arrays versus angular distributions

International Nuclear Information System (INIS)

Iacob, V.E.; Duchene, G.

1997-01-01

Angular information extracted from in-beam γ ray measurements are of great importance for γ ray multipolarity and nuclear spin assignments. In our days large Ge detector arrays became available allowing the measurements of extremely weak γ rays in almost 4π sr solid angle (e.g., EUROGAM detector array). Given the high detector efficiency it is common for the mean suppressed coincidence multiplicity to reach values as high as 4 to 6. Thus, it is possible to gate on particular γ rays in order to enhance the relative statistics of a definite reaction channel and/or a definite decaying path in the level scheme of the selected residual nucleus. As compared to angular correlations, the conditioned angular distribution spectra exhibit larger statistics because in the latter the gate-setting γ ray may be observed by all the detectors in the array, relaxing somehow the geometrical restrictions of the angular correlations. Since the in-beam γ ray emission is anisotropic one could inquire that gate setting as mentioned above, based on anisotropic γ ray which would perturb the angular distributions in the unfolded events. As our work proved, there is no reason to worry about this if the energy gate runs over the whole solid angle in an ideal 4π sr detector, i.e., if the gate is isotropic. In real quasi 4π sr detector arrays the corresponding quasi isotropic gate preserves the angular properties of the unfolded data, too. However extraction of precise angular distribution coefficient especially a 4 , requires the consideration of the deviation of the quasi isotropic gate relative to the (ideal) isotropic gate

Time-Resolved Emission Spectroscopic Study of Laser-Induced Steel Plasmas

International Nuclear Information System (INIS)

Shah, M. L.; Pulhani, A. K.; Suri, B. M.; Gupta, G. P.

2013-01-01

Laser-induced steel plasma is generated by focusing a Q-switched Nd:YAG visible laser (532 nm wavelength) with an irradiance of ∼ 1 × 10 9 W/cm 2 on a steel sample in air at atmospheric pressure. An Echelle spectrograph coupled with a gateable intensified charge-coupled detector is used to record the plasma emissions. Using time-resolved spectroscopic measurements of the plasma emissions, the temperature and electron number density of the steel plasma are determined for many times of the detector delay. The validity of the assumption by the spectroscopic methods that the laser-induced plasma (LIP) is optically thin and is also in local thermodynamic equilibrium (LTE) has been evaluated for many delay times. From the temporal evolution of the intensity ratio of two Fe I lines and matching it with its theoretical value, the delay times where the plasma is optically thin and is also in LTE are found to be 800 ns, 900 ns and 1000 ns.

A fast method for optical simulation of flood maps of light-sharing detector modules

International Nuclear Information System (INIS)

Shi, Han; Du, Dong; Xu, JianFeng; Moses, William W.; Peng, Qiyu

2015-01-01

Optical simulation of the detector module level is highly desired for Position Emission Tomography (PET) system design. Commonly used simulation toolkits such as GATE are not efficient in the optical simulation of detector modules with complicated light-sharing configurations, where a vast amount of photons need to be tracked. We present a fast approach based on a simplified specular reflectance model and a structured light-tracking algorithm to speed up the photon tracking in detector modules constructed with polished finish and specular reflector materials. We simulated conventional block detector designs with different slotted light guide patterns using the new approach and compared the outcomes with those from GATE simulations. While the two approaches generated comparable flood maps, the new approach was more than 200–600 times faster. The new approach has also been validated by constructing a prototype detector and comparing the simulated flood map with the experimental flood map. The experimental flood map has nearly uniformly distributed spots similar to those in the simulated flood map. In conclusion, the new approach provides a fast and reliable simulation tool for assisting in the development of light-sharing-based detector modules with a polished surface finish and using specular reflector materials.

Silicon Drift Detectors - A Novel Technology for Vertex Detectors

Science.gov (United States)

Lynn, D.

1996-10-01

Silicon Drift Detectors (SDD) are novel position sensing silicon detectors which operate in a manner analogous to gas drift detectors. Single SDD's were shown in the CERN NA45 experiment to permit excellent spatial resolution (pseudo-rapidity. Over the last three years we undertook a concentrated R+D effort to optimize the performance of the detector by minimizing the inactive area, the operating voltage and the data volume. We will present test results from several wafer prototypes. The charge produced by the passage of ionizing particles through the bulk of the detectors is collected on segmented anodes, with a pitch of 250 μm, on the far edges of the detector. The anodes are wire-bonded to a thick film multi-chip module which contains preamplifier/shaper chips and CMOS based switched capacitor arrays used as an analog memory pipeline. The ADC is located off-detector. The complete readout chain from the wafer to the DAQ will be presented. Finally we will show physics performance simulations based on the resolution achieved by the SVT prototypes.

Two-Step Proximal Gradient Algorithm for Low-Rank Matrix Completion

Directory of Open Access Journals (Sweden)

Qiuyu Wang

2016-06-01

Full Text Available In this paper, we  propose a two-step proximal gradient algorithm to solve nuclear norm regularized least squares for the purpose of recovering low-rank data matrix from sampling of its entries. Each iteration generated by the proposed algorithm is a combination of the latest three points, namely, the previous point, the current iterate, and its proximal gradient point. This algorithm preserves the computational simplicity of classical proximal gradient algorithm where a singular value decomposition in proximal operator is involved. Global convergence is followed directly in the literature. Numerical results are reported to show the efficiency of the algorithm.

Simultaneous CT and SPECT tomography using CZT detectors

Science.gov (United States)

Paulus, Michael J.; Sari-Sarraf, Hamed; Simpson, Michael L.; Britton, Jr., Charles L.

2002-01-01

A method for simultaneous transmission x-ray computed tomography (CT) and single photon emission tomography (SPECT) comprises the steps of: injecting a subject with a tracer compound tagged with a .gamma.-ray emitting nuclide; directing an x-ray source toward the subject; rotating the x-ray source around the subject; emitting x-rays during the rotating step; rotating a cadmium zinc telluride (CZT) two-sided detector on an opposite side of the subject from the source; simultaneously detecting the position and energy of each pulsed x-ray and each emitted .gamma.-ray captured by the CZT detector; recording data for each position and each energy of each the captured x-ray and .gamma.-ray; and, creating CT and SPECT images from the recorded data. The transmitted energy levels of the x-rays lower are biased lower than energy levels of the .gamma.-rays. The x-ray source is operated in a continuous mode. The method can be implemented at ambient temperatures.

Emission polarization study on quartz and calcite.

Science.gov (United States)

Vincent, R. K.

1972-01-01

Calculation of the spectral emission polarization of quartz and calcite polished plates for observation angles of 20 and 70 deg by the substitution of complex index of refraction values for each mineral into Fresnel's equations. The emission polarization is shown to be quite wavelength-dependent, demonstrating that selected narrow or medium-width spectral bands exhibit a significantly higher percentage of polarization than a broad spectral band for these two minerals. Field measurements with a broadband infrared radiometer yield polarizations on the order of 2% for a coarse-grained granite rock and beach sand (both quartz-rich). This implies that a more sensitive detector with a selected medium-width filter may be capable of measuring emission polarization accurately enough to make this parameter useful as a remote sensing tool for discrimination among rocks on the basis of texture.

Electromagnetic properties of proximity systems

Science.gov (United States)

Kresin, Vladimir Z.

1985-07-01

Magnetic screening in the proximity system Sα-Mβ, where Mβ is a normal metal N, semiconductor (semimetal), or a superconductor, is studied. Main attention is paid to the low-temperature region where nonlocality plays an important role. The thermodynamic Green's-function method is employed in order to describe the behavior of the proximity system in an external field. The temperature and thickness dependences of the penetration depth λ are obtained. The dependence λ(T) differs in a striking way from the dependence in usual superconductors. The strong-coupling effect is taken into account. A special case of screening in a superconducting film backed by a size-quantizing semimetal film is considered. The results obtained are in good agreement with experimental data.

Electromagnetic properties of proximity systems

International Nuclear Information System (INIS)

Kresin, V.Z.

1985-01-01

Magnetic screening in the proximity system S/sub α/-M/sub β/, where M/sub β/ is a normal metal N, semiconductor (semimetal), or a superconductor, is studied. Main attention is paid to the low-temperature region where nonlocality plays an important role. The thermodynamic Green's-function method is employed in order to describe the behavior of the proximity system in an external field. The temperature and thickness dependences of the penetration depth lambda are obtained. The dependence lambda(T) differs in a striking way from the dependence in usual superconductors. The strong-coupling effect is taken into account. A special case of screening in a superconducting film backed by a size-quantizing semimetal film is considered. The results obtained are in good agreement with experimental data

Proximity operations concept design study, task 6

Science.gov (United States)

Williams, A. N.

1990-01-01

The feasibility of using optical technology to perform the mission of the proximity operations communications subsystem on Space Station Freedom was determined. Proximity operations mission requirements are determined and the relationship to the overall operational environment of the space station is defined. From this information, the design requirements of the communication subsystem are derived. Based on these requirements, a preliminary design is developed and the feasibility of implementation determined. To support the Orbital Maneuvering Vehicle and National Space Transportation System, the optical system development is straightforward. The requirements on extra-vehicular activity are such as to allow large fields of uncertainty, thus exacerbating the acquisition problem; however, an approach is given that could mitigate this problem. In general, it is found that such a system could indeed perform the proximity operations mission requirement, with some development required to support extra-vehicular activity.

Development of large area CsI photocathodes for the Alice/Humped Rich detector

International Nuclear Information System (INIS)

Hoedlmoser, H.

2005-03-01

The work carried out within the framework of this PhD deals with the measurement of the photoelectric properties of large area thin film cesium iodide photocathodes (PCs) which are to be used as a photon converter in a proximity focusing RICH detector for High Momentum Particle Identification (HMPID) in the ALICE experiment at the LHC. The objective was to commission a VUV-scanner setup for in-situ measurements of the photoelectric response of the CsI PCs and the use of this system to investigate the properties of these photon detectors. Among the investigated phenomena the most important ones were: - Post deposition treatment: from R and D studies it was known, that the PC response can be increased by heating the PC after the coating process. Within this thesis it was shown that the enhancement effect is mandatory to achieve the photon conversion efficiency required by the detector design and that any difference in PC quality is due to differences in this enhancement effect. - Ageing effects: CsI PCs age under exposure to humidity due to the hygroscopicity of CsI and under high photon flux and ion bombardment inside the Multi Wire Proportional Chamber (MWPC) of the detector. All three effects have been investigated with the VUV scanner. The first effect requires a careful treatment of the CsI PCs to avoid exposure to humid air. Furthermore this effect was found to be reversible if the PC is heated. High photon fluxes are irrelevant in a Cherenkov detector dealing with single photons, however, the problem needed to be investigated to verify that the measurement process itself does not damage the PCs. The third mechanism is very important as it occurs during normal detector operation and depends only on the radiation environment of the experiment. For a dose corresponding to 20 years of operation inside ALICE an accelerated test showed a clear degradation of up to 40 % of the PC response. With the results of these studies the first 17 PCs (of 42) for the detector

Proximate analysis of Lentinus squarrosulus (Mont.) Singer and ...

African Journals Online (AJOL)

Each of the mushroom species was separated into its stipe and pileus and used for proximate analysis. There was a highly significant difference (p<0.01) in the proximate composition of the two species. P. atroumbonata had significantly higher crude protein, crude fibre and moisture content than L. squarrosulus while the ...

Genetics Home Reference: proximal 18q deletion syndrome

Science.gov (United States)

... characteristic features. Most cases of proximal 18q deletion syndrome are the result of a new (de novo) deletion and are not inherited from a ... J, Fox PT, Stratton RF, Perry B, Hale DE. Recurrent interstitial deletions of proximal 18q: a new syndrome involving expressive speech delay. Am J Med Genet ...

Superconducting proximity effect in topological materials

Science.gov (United States)

Reeg, Christopher R.

In recent years, there has been a renewed interest in the proximity effect due to its role in the realization of topological superconductivity. In this dissertation, we discuss several results that have been obtained in the field of proximity-induced superconductivity and relate the results to the search for Majorana fermions. First, we show that repulsive electron-electron interactions can induce a non-Majorana zero-energy bound state at the interface between a conventional superconductor and a normal metal. We show that this state is very sensitive to disorder, owing to its lack of topological protection. Second, we show that Rashba spin-orbit coupling, which is one of the key ingredients in engineering a topological superconductor, induces triplet pairing in the proximity effect. When the spin-orbit coupling is strong (i.e., when the characteristic energy scale for spin-orbit coupling is comparable to the Fermi energy), the induced singlet and triplet pairing amplitudes can be comparable in magnitude. Finally, we discuss how the size of the proximity-induced gap, which appears in a low-dimensional material coupled to a superconductor, evolves as the thickness of the (quasi-)low-dimensional material is increased. We show that the induced gap can be comparable to the bulk energy gap of the underlying superconductor in materials that are much thicker than the Fermi wavelength, even in the presence of an interfacial barrier and strong Fermi surface mismatch. This result has important experimental consequences for topological superconductivity, as a sizable gap is required to isolate and detect the Majorana modes.

VLF emissions in the Venus foreshock - Comparison with terrestrial observations

Science.gov (United States)

Crawford, G. K.; Strangeway, R. J.; Russell, C. T.

1993-01-01

An examination is conducted of ELF/VLF emissions observed in the solar wind upstream of the Venus shock, for the 100 Hz-30 kHz range, using data from the Pioneer Venus Orbiter's electric field detector and magnetometer instruments. Detailed comparisons are made with terrestrial measurements for both the electron and ion foreshocks. The results obtained support the Crawford et al. (1990) identification of the Venus electron foreshock emissions as electron plasma oscillations, whose waves are generated in situ and act to isotropize the electron distributions.