scholarly journals The XGIS instrument on-board THESEUS: the detection plane and on-board electronics

2020 ◽  
Author(s):  
Fabio Fuschino ◽  
Riccardo Campana ◽  
Claudio Labanti ◽  
Lorenzo Amati ◽  
Enrico Virgilli ◽  
...  
Keyword(s):  
Detection Plane

Influence of active control on STG-based generation of streamwise vortices in near-wall turbulence

2012 ◽  
Vol 710 ◽  
pp. 234-259 ◽  
Author(s):  
B.-Q. Deng ◽  
C.-X. Xu
Keyword(s):  
Drag Reduction ◽  
Turbulent Flows ◽  
Active Control ◽  
Phase Control ◽  
Transient Growth ◽  
Vortex Generation ◽  
Streamwise Vortices ◽  
Detection Plane ◽  
Near Wall ◽  
Opposition Control

AbstractNear-wall streamwise vortices are closely related to the generation of high skin friction in wall-bounded turbulent flows. A common feature of controlled, friction-reduced turbulent flows is weakened near-wall streamwise vortices. In the present study, the streak transient growth (STG) mechanism for generating near-wall streamwise vortices by Schoppa & Hussain (J. Fluid Mech., vol. 453, 2002, pp. 57–108) is employed, and the opposition control proposed by Choi, Moin & Kim (J. Fluid Mech., vol. 262, 1994, pp. 75–110) is imposed during the transient growth process of perturbations to determine how active control affects the generation of quasi-streamwise vortices. In the transient growth stage, when the detection plane is located near the wall (${ y}_{d}^{+ } = 15$), the control can suppress the production of streamwise vorticity by weakening the near-wall vertical velocity; when the detection plane moves away from the wall (${ y}_{d}^{+ } = 28$), the control has the opposite effect. In the vortex generation stage, the control cannot change the dominance of the stretching effect. Controls imposed at different stages reveal the importance of the STG stage in vortex generation. Strengthened out-of-phase control and lessened in-phase control are proposed as an extension of the original opposition-control scheme. Application in a fully developed turbulent channel flow shows that strengthened ${ y}_{d}^{+ } = 10$ control can yield an even higher drag reduction rate than the original ${ y}_{d}^{+ } = 15$ control. Moreover, lessened ${ y}_{d}^{+ } = 28$ control can also achieve drag reduction and turbulence suppression.

ECLAIRs detection plane: current state of development

2014 ◽  
Author(s):  
K. Lacombe ◽  
R. Pons ◽  
C. Amoros ◽  
J.-L. Atteia ◽  
D. Barret ◽  
...  
Keyword(s):  
Current State ◽  
Detection Plane

The use of Schottky CdTe detectors for high-energy astronomy: application to the detection plane of the instrument SVOM/ECLAIRs

2014 ◽  
Author(s):  
G. Nasser ◽  
O. Godet ◽  
J.-L. Atteia ◽  
C. Amoros ◽  
D. Barret ◽  
...  
Keyword(s):  
High Energy ◽  
Detection Plane

scholarly journals Prior Compensation Algorithm for Cerenkov Luminescence Tomography From Single-View Measurements

2021 ◽  
Vol 11 ◽  
Author(s):  
Lin Wang ◽  
Xiaowei He ◽  
Jingjing Yu
Keyword(s):  
Light Source ◽  
Imaging System ◽  
Three Dimensional ◽  
Light Flux ◽  
System Matrix ◽  
Full Account ◽  
Single View ◽  
Compensation Algorithm ◽  
Detection Plane ◽  
Calibration Matrix

Cerenkov luminescence tomography (CLT) has attracted much attention because of the wide clinically-used probes and three-dimensional (3D) quantification ability. However, due to the serious morbidity of 3D optical imaging, the reconstructed images of CLT are not appreciable, especially when single-view measurements are used. Single-view CLT improves the efficiency of data acquisition. It is much consistent with the actual imaging environment of using commercial imaging system, but bringing the problem that the reconstructed results will be closer to the animal surface on the side where the single-view image is collected. To avoid this problem to the greatest extent possible, we proposed a prior compensation algorithm for CLT reconstruction based on depth calibration strategy. This method takes full account of the fact that the attenuation of light in the tissue will depend heavily on the depth of the light source as well as the distance between the light source and the detection plane. Based on this consideration, a depth calibration matrix was designed to calibrate the attenuation between the surface light flux and the density of the internal light source. The feature of the algorithm was that the depth calibration matrix directly acts on the system matrix of CLT reconstruction, rather than modifying the regularization penalty items. The validity and effectiveness of the proposed algorithm were evaluated with a numerical simulation and a mouse-based experiment, whose results illustrated that it located the radiation sources accurately by using single-view measurements.

Calculations and experimental observations of shadow images from multilayers

1990 ◽  
Vol 48 (4) ◽  
pp. 440-441
Author(s):  
Shiyao Wang ◽  
M. Gajdardziska-Josifovska ◽  
J.M. Cowley
Keyword(s):  
Spherical Aberration ◽  
High Sensitivity ◽  
Objective Lens ◽  
Interference Effects ◽  
Probe Position ◽  
Cross Sectional ◽  
Detection Plane ◽  
Resolution Imaging ◽  
Convergent Beam ◽  
Established Technique

The properties of multilayer thin film materials are strongly influenced by the structure of their interfaces. The numerous applications for these materials motivate electron microscopy studies of cross sectional samples in which the interfaces are observed edge on. High resolution imaging is the most established technique, but other techniques, such as Fresnel fringe method and refraction at interfaces, have also been employed to characterize the structure and abruptness of amorphous/polycrystalline multilayers. The aim of this work is to explore the applicability of shadow images from coherent sources to the studies of multilayers.Coherent interference effects are readily observable in the diffraction plane of a VG HB-5 STEM which is equipped with a cold field emission gun. The shadow image of the studied Si/Mo multilayer is obtained on the detection plane when the specimen is illuminated by a stationary convergent beam. This beam is formed with a very large or no objective aperture. Low magnification images are produced at large values of defocus (Fig. 1a), while for lower defocus the magnification increases and the shadow images become more and more distorted because of the objective lens aberration (Fig. 1b and 1c). In addition to the high sensitivity to the defocus. spherical aberration and probe position, the shadow images also appear to be dependent on the interface abruptness.

PICsIT: the high-energy detection plane of the IBIS instrument onboard INTEGRAL

1996 ◽  
Author(s):  
Claudio Labanti ◽  
Guido Di Cocco ◽  
Giuseppe Malaguti ◽  
Alessandro Mauri ◽  
Elio Rossi ◽  
...  
Keyword(s):  
Energy Detection ◽  
High Energy ◽  
Detection Plane

scholarly journals Performance studies of resistive Micromegas chambers for the upgrade of the ATLAS Muon Spectrometer

2018 ◽  
Vol 174 ◽  
pp. 01014
Author(s):  
Konstantinos Ntekas
Keyword(s):  
Performance Studies ◽  
Incidence Angle ◽  
Atlas Collaboration ◽  
Test Beam ◽  
Position Resolution ◽  
Timing Resolution ◽  
Detection Plane ◽  
Novel Method ◽  
Time Projection ◽  
Better Than

The ATLAS collaboration at LHC has endorsed the resistive Micromegas technology (MM), along with the small-strip Thin Gap Chambers (sTGC), for the high luminosity upgrade of the first muon station in the high-rapidity region, the so called New Small Wheel (NSW) project. The NSW requires fully efficient MM chambers, up to a particle rate of ∼ 15 kHz/cm2, with spatial resolution better than 100 μm independent of the track incidence angle and the magnetic field (B ≤ 0.3 T). Along with the precise tracking the MM should be able to provide a trigger signal, complementary to the sTGC, thus a decent timing resolution is required. Several tests have been performed on small (10 × 10 cm2) MM chambers using medium (10 GeV/c) and high (150 GeV/c) momentum hadron beams at CERN. Results on the efficiency and position resolution measured during these tests are presented demonstrating the excellent characteristics of the MM that fulfil the NSW requirements. Exploiting the ability of the MM to work as a Time Projection Chamber a novel method, called the μTPC, has been developed for the case of inclined tracks, allowing for a precise segment reconstruction using a single detection plane. A detailed description of the method along with thorough studies towards refining the method’s performance are shown. Finally, during 2014 the first MM quadruplet (MMSW) following the NSW design scheme, comprising four detection planes in a stereo readout configuration, has been realised at CERN. Test-beam results of this prototype are discussed and compared to theoretical expectations.

scholarly journals A demonstration of extracting the strength and wavelength of the magnetic field generated by the Weibel instability from proton radiography

2019 ◽  
Vol 7 ◽  
Author(s):  
Bao Du ◽  
Hong-Bo Cai ◽  
Wen-Shuai Zhang ◽  
Shi-Yang Zou ◽  
Jing Chen ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Inertial Confinement Fusion ◽  
Inertial Confinement ◽  
Induced Magnetic Field ◽  
Proton Radiography ◽  
Weibel Instability ◽  
Detection Plane ◽  
Key Characteristics ◽  
Confinement Fusion ◽  
The Magnetic Field

The Weibel instability and the induced magnetic field are of great importance for both astrophysics and inertial confinement fusion. Because of the stochasticity of this magnetic field, its main wavelength and mean strength, which are key characteristics of the Weibel instability, are still unobtainable experimentally. In this paper, a theoretical model based on the autocorrelation tensor shows that in proton radiography of the Weibel-instability-induced magnetic field, the proton flux density on the detection plane can be related to the energy spectrum of the magnetic field. It allows us to extract the main wavelength and mean strength of the two-dimensionally isotropic and stochastic magnetic field directly from proton radiography for the first time. Numerical calculations are conducted to verify our theory and show good consistency between pre-set values and the results extracted from proton radiography.

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