Background model of Phoswich X-ray detector on board small balloon

2021 ◽  
Author(s):  
Abhijit Roy ◽  
Ritabrata Sarkar ◽  
Sandip K. Chakrabarti
Keyword(s):  
Background Model ◽  
X Ray

scholarly journals Multifrequency Observations of the Jet of 3C 273

1994 ◽  
Vol 159 ◽  
pp. 333-334
Author(s):  
H.-J. Röser ◽  
K. Meisenheimer ◽  
M. Neumann ◽  
R.G. Conway
Keyword(s):  
Synchrotron Radiation ◽  
Lower Limit ◽  
Background Model ◽  
Integration Time ◽  
X Ray ◽  
Upper Limit ◽  
Radio Frequencies ◽  
Quasar 3C 273 ◽  
Good Agreement

Previously we have studied the jet of the quasar 3C 273 at optical and radio frequencies. In our first set of X-ray data with 17.2 ksec integration time obtained with the ROSAT HRI, the jet is easily visible extending out from the bright quasar core. The total number of counts in the jet lies in the range 200 to 300, depending on the details of the background model. This corresponds to an X-ray flux fv(2.9 × 1017 Hz) = 65 … 140 nJy (lower limit, synchrotron radiation α = −0.8 … upper limit, bremsstrahlung α = 0, NHI = 1.8 × 1020 cm−2), in good agreement with the value derived from the EINSTEIN observations.

scholarly journals Background modelling of diffraction data in the presence of ice rings

IUCrJ ◽  
2017 ◽  
Vol 4 (5) ◽  
pp. 626-638 ◽  
Author(s):  
James M. Parkhurst ◽  
Andrea Thorn ◽  
Melanie Vollmar ◽  
Graeme Winter ◽  
David G. Waterman ◽  
...  
Keyword(s):  
Diffraction Data ◽  
Bragg Reflection ◽  
Background Model ◽  
Data Sets ◽  
Systematic Bias ◽  
X Ray Diffraction ◽  
Data Set ◽  
X Ray ◽  
Local Background ◽  
Global Background

An algorithm for modelling the background for each Bragg reflection in a series of X-ray diffraction images containing Debye–Scherrer diffraction from ice in the sample is presented. The method involves the use of a global background model which is generated from the complete X-ray diffraction data set. Fitting of this model to the background pixels is then performed for each reflection independently. The algorithm uses a static background model that does not vary over the course of the scan. The greatest improvement can be expected for data where ice rings are present throughout the data set and the local background shape at the size of a spot on the detector does not exhibit large time-dependent variation. However, the algorithm has been applied to data sets whose background showed large pixel variations (variance/mean > 2) and has been shown to improve the results of processing for these data sets. It is shown that the use of a simple flat-background model as in traditional integration programs causes systematic bias in the background determination at ice-ring resolutions, resulting in an overestimation of reflection intensities at the peaks of the ice rings and an underestimation of reflection intensities either side of the ice ring. The new global background-model algorithm presented here corrects for this bias, resulting in a noticeable improvement inRfactors following refinement.

scholarly journals The background model of the medium energy X-ray telescope of Insight-HXMT

2020 ◽  
Vol 27 ◽  
pp. 44-50 ◽  
Author(s):  
Cheng-Cheng Guo ◽  
Jin-Yuan Liao ◽  
Shu Zhang ◽  
Juan Zhang ◽  
Ying Tan ◽  
...  
Keyword(s):  
Background Model ◽  
Medium Energy ◽  
X Ray

scholarly journals Adaptation of a clustered lumpy background model for task-based image quality assessment in x-ray phase-contrast mammography

2012 ◽  
Vol 39 (2) ◽  
pp. 906-911 ◽  
Author(s):  
Adam M. Zysk ◽  
Jovan G. Brankov ◽  
Miles N. Wernick ◽  
Mark A. Anastasio
Keyword(s):  
Image Quality ◽  
Quality Assessment ◽  
Phase Contrast ◽  
Image Quality Assessment ◽  
Background Model ◽  
X Ray

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Iron K-Line Emission from X-Ray Binaries

1988 ◽  
Vol 102 ◽  
pp. 47-50
Author(s):  
K. Masai ◽  
S. Hayakawa ◽  
F. Nagase
Keyword(s):  
Accretion Disk ◽  
Radiative Recombination ◽  
Characteristic Temperature ◽  
Line Emission ◽  
Ionization Front ◽  
Continuum Radiation ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

AbstractEmission mechanisms of the iron Kα-lines in X-ray binaries are discussed in relation with the characteristic temperature Txof continuum radiation thereof. The 6.7 keV line is ascribed to radiative recombination followed by cascades in a corona of ∼ 100 eV formed above the accretion disk. This mechanism is attained for Tx≲ 10 keV as observed for low mass X-ray binaries. The 6.4 keV line observed for binary X-ray pulsars with Tx> 10 keV is likely due to fluorescence outside the He II ionization front.

Diagnostics of Gold Laser Plasmas

1988 ◽  
Vol 102 ◽  
pp. 357-360
Author(s):  
J.C. Gauthier ◽  
J.P. Geindre ◽  
P. Monier ◽  
C. Chenais-Popovics ◽  
N. Tragin ◽  
...  
Keyword(s):  
Experimental Results ◽  
Pure Gold ◽  
Electronic Temperature ◽  
X Ray ◽  
Laser Plasmas ◽  
Collisional Radiative Model ◽  
Radiative Model

AbstractIn order to achieve a nickel-like X ray laser scheme we need a tool to determine the parameters which characterise the high-Z plasma. The aim of this work is to study gold laser plasmas and to compare experimental results to a collisional-radiative model which describes nickel-like ions. The electronic temperature and density are measured by the emission of an aluminium tracer. They are compared to the predictions of the nickel-like model for pure gold. The results show that the density and temperature can be estimated in a pure gold plasma.

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