scholarly journals Geant4 simulations of STIX Caliste-SO detector's response to solar X-ray radiation

2015 ◽  
Vol 11 (S320) ◽  
pp. 439-441
Author(s):  
Jaromir Barylak ◽  
Aleksandra Barylak ◽  
Tomasz Mrozek ◽  
Marek Steślicki ◽  
Piotr Podgórski ◽  
...  
Keyword(s):  
Cosmic Ray ◽  
Detector Response ◽  
X Rays ◽  
Aging Effects ◽  
X Ray ◽  
Accuracy Comparison ◽  
Detailed Simulation ◽  
New Type ◽  
Complicated Geometry ◽  
Good Agreement

AbstractSpectrometer/Telescope for Imaging X-rays (STIX) is a part of Solar Orbiter (SO) science payload. SO will be launched in October 2018, and after three years of cruise phase, it will reach orbit with perihelion distance of 0.3 a.u. STIX is a Fourier imager equipped with pairs of grids that comprise the flare hard X-ray tomograph. Similar imager types were already used in the past (eq. RHESSI, Yohkoh/HXT), but STIX will incorporate Moiré modulation and a new type of pixelized detectors with CdTe sensor. We developed a method of modeling these detectors' response matrix (DRM) using the Geant4 simulations of X-ray photons interactions with CdTe crystals. Taking into account known detector effects (Fano noise, hole tailing etc.) we modeled the resulting spectra with high accuracy. Comparison of Caliste-SO laboratory measurements of 241Am decay spectrum with our results shows a very good agreement. The modeling based on the Geant4 simulations significantly improves our understanding of detector response to X-ray photons. Developed methodology gives opportunity for detailed simulation of whole instrument response with complicated geometry and secondary radiation from cosmic ray particles taken into account. Moreover, we are developing the Geant4 simulations of aging effects which decrease detector's performance.

Energy spectrum of diffuse primary X rays up to 180 keV

1968 ◽  
Vol 46 (10) ◽  
pp. S461-S465 ◽  
Author(s):  
J. A. M. Bleeker ◽  
J. J. Burger ◽  
A. J. M. Deerenberg ◽  
A. Scheepmaker ◽  
B. N. Swanenburg ◽  
...  
Keyword(s):  
Energy Spectrum ◽  
Power Law ◽  
Plastic Scintillator ◽  
Geomagnetic Latitude ◽  
Cosmic Ray ◽  
Rotating Disk ◽  
The Other ◽  
X Rays ◽  
X Ray ◽  
Good Agreement

Two balloon flights with identical X-ray detectors were carried out in the summer of 1966, one from De Bilt, the Netherlands (geomagnetic latitude 53 °N), and the other from Taiyomura, Japan (geomagnetic latitude 25 °N). The detector consists of a NaI(Tl) crystal, 12.5 mm thick and 50 mm in diameter, surrounded by an effective collimator-shield and a plastic scintillator guard counter. The rotating disk incorporated enables the separation of "forward" X rays from the cosmic-ray-induced background. The results of the flights are in very good agreement with each other. In view of the rather large difference in geomagnetic latitude in these two flights, this agreement supports the celestial origin of the primary X rays observed. The energy spectrum between 20 and 180 keV can be expressed by a power law:[Formula: see text]

Characterization and interpretation of the quantum efficiencies of multilayer semiconductor detectors using a new theory

1998 ◽  
Vol 5 (3) ◽  
pp. 877-879
Author(s):  
T. Cho ◽  
M. Hirata ◽  
J. Kohagura ◽  
Y. Sakamoto ◽  
T. Okamura ◽  
...  
Keyword(s):  
Heavy Particle ◽  
Current Mode ◽  
High Energy ◽  
Detector Response ◽  
Semiconductor Detectors ◽  
X Rays ◽  
Fusion Plasma ◽  
X Ray ◽  
New Type ◽  
High Bias

On the basis of a new theory of semiconductor X-ray detector response, a new type of multilayer semiconductor detector was designed and developed for convenient energy analyses of intense incident X-ray flux in a cumulative-current mode. Another anticipated useful property of the developed detector is a drastic improvement in high-energy X-ray response ranging over several hundred eV. The formula for the quantum efficiency of multilayer semiconductor detectors and its physical interpretations are proposed and have been successfully verified by synchrotron radiation experiments at the Photon Factory. These detectors are useful for data analyses under strong radiation-field conditions, including fusion-plasma-emitting X-rays and energetic heavy-particle beams, without the use of high-bias applications.

scholarly journals Radio and X-ray connection in radio mini-halos: Implications for hadronic models

2020 ◽  
Vol 640 ◽  
pp. A37 ◽  
Author(s):  
A. Ignesti ◽  
G. Brunetti ◽  
M. Gitti ◽  
S. Giacintucci
Keyword(s):  
Magnetic Field ◽  
Large Fraction ◽  
Cosmic Ray ◽  
Physical Parameters ◽  
Model Parameters ◽  
Relativistic Electrons ◽  
X Rays ◽  
X Ray ◽  
Hadronic Model ◽  
Radio Halos

Context. A large fraction of cool-core clusters are known to host diffuse, steep-spectrum radio sources, called radio mini-halos, in their cores. Mini-halos reveal the presence of relativistic particles on scales of hundreds of kiloparsecs, beyond the scales directly influenced by the central active galactic nucleus (AGN), but the nature of the mechanism that produces such a population of radio-emitting, relativistic electrons is still debated. It is also unclear to what extent the AGN plays a role in the formation of mini-halos by providing the seeds of the relativistic population. Aims. In this work we explore the connection between thermal and non-thermal components of the intra-cluster medium in a sample of radio mini-halos and we study the implications within the framework of a hadronic model for the origin of the emitting electrons. Methods. For the first time, we studied the thermal and non-thermal connection by carrying out a point-to-point comparison of the radio and the X-ray surface brightness in a sample of radio mini-halos. We extended the method generally applied to giant radio halos by considering the effects of a grid randomly generated through a Monte Carlo chain. Then we used the radio and X-ray correlation to constrain the physical parameters of a hadronic model and we compared the model predictions with current observations. Results. Contrary to what is generally reported in the literature for giant radio halos, we find that the mini-halos in our sample have super-linear scaling between radio and X-rays, which suggests a peaked distribution of relativistic electrons and magnetic field. We explore the consequences of our findings on models of mini-halos. We use the four mini-halos in the sample that have a roundish brightness distribution to constrain model parameters in the case of a hadronic origin of the mini-halos. Specifically, we focus on a model where cosmic rays are injected by the central AGN and they generate secondaries in the intra-cluster medium, and we assume that the role of turbulent re-acceleration is negligible. This simple model allows us to constrain the AGN cosmic ray luminosity in the range ∼1044−46 erg s−1 and the central magnetic field in the range 10–40 μG. The resulting γ-ray fluxes calculated assuming these model parameters do not violate the upper limits on γ-ray diffuse emission set by the Fermi-LAT telescope. Further studies are now required to explore the consistency of these large magnetic fields with Faraday rotation studies and to study the interplay between the secondary electrons and the intra-cluster medium turbulence.

scholarly journals X-ray Dips in AGN and Microquasars – Collapse Timescales of Inner Accretion Disc

2020 ◽  
Author(s):  
Mayur B Shende ◽  
Prashali Chauhan ◽  
Prasad Subramanian
Keyword(s):  
Collisionless Plasma ◽  
Cosmic Ray ◽  
Outer Radius ◽  
Accretion Disc ◽  
Accretion Discs ◽  
X Rays ◽  
Temporal Behaviour ◽  
X Ray ◽  
Ray Diffusion ◽  
3C 120

Abstract The temporal behaviour of X-rays from some AGN and microquasars is thought to arise from the rapid collapse of the hot, inner parts of their accretion discs. The collapse can occur over the radial infall timescale of the inner accretion disc. However, estimates of this timescale are hindered by a lack of knowledge of the operative viscosity in the collisionless plasma comprising the inner disc. We use published simulation results for cosmic ray diffusion through turbulent magnetic fields to arrive at a viscosity prescription appropriate to hot accretion discs. We construct simplified disc models using this viscosity prescription and estimate disc collapse timescales for 3C 120, 3C 111, and GRS 1915+105. The Shakura-Sunyaev α parameter resulting from our model ranges from 0.02 to 0.08. Our inner disc collapse timescale estimates agree well with those of the observed X-ray dips. We find that the collapse timescale is most sensitive to the outer radius of the hot accretion disc.

scholarly journals Experimentally obtained and computer-simulated X-ray non-coplanar 18-beam pinhole topographs for a silicon crystal

2019 ◽  
Vol 75 (3) ◽  
pp. 483-488 ◽  
Author(s):  
Kouhei Okitsu ◽  
Yasuhiko Imai ◽  
Yoshitaka Yoda
Keyword(s):  
Silicon Crystal ◽  
Dynamical Theory ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Good Agreement

Non-coplanar 18-beam X-ray pinhole topographs for a silicon crystal were computer simulated by fast Fourier transforming the X-ray rocking amplitudes that were obtained by solving the n-beam (n = 18) Ewald–Laue dynamical theory (E-L&FFT method). They were in good agreement with the experimentally obtained images captured using synchrotron X-rays. From this result and further consideration based on it, it has been clarified that the X-ray diffraction intensities when n X-ray waves are simultaneously strong in the crystal can be computed for any n by using the E-L&FFT method.

scholarly journals Destruction of tumor mass by gadolinium-loaded nanoparticles irradiated with monochromatic X-rays: Implications for the Auger therapy

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Kotaro Matsumoto ◽  
Hiroyuki Saitoh ◽  
Tan Le Hoang Doan ◽  
Ayumi Shiro ◽  
Keigo Nakai ◽  
...  
Keyword(s):  
Mesoporous Silica Nanoparticles ◽  
X Rays ◽  
Tumor Spheroids ◽  
Tumor Mass ◽  
X Ray ◽  
Complete Destruction ◽  
New Type ◽  
Efficient Uptake ◽  
A Site ◽  
Shell Energy

Abstract Synchrotron generated monochromatic X-rays can be precisely tuned to the K-shell energy of high Z materials resulting in the release of the Auger electrons. In this work, we have employed this mechanism to destruct tumor spheroids. We first loaded gadolinium onto the surface of mesoporous silica nanoparticles (MSNs) producing gadolinium-loaded MSN (Gd-MSN). When Gd-MSN was added to the tumor spheroids, we observed efficient uptake and uniform distribution of Gd-MSN. Gd-MSN also can be taken up into cancer cells and localize to a site just outside of the cell nucleus. Exposure of the Gd-MSN containing tumor spheroids to monochromatic X-ray beams resulted in almost complete destruction. Importantly, this effect was observed at an energy level of 50.25 keV, but not with 50.0 keV. These results suggest that it is possible to use precisely tuned monochromatic X-rays to destruct tumor mass loaded with high Z materials, while sparing other cells. Our experiments point to the importance of nanoparticles to facilitate loading of gadolinium to tumor spheroids and to localize at a site close to the nucleus. Because the nanoparticles can target to tumor, our study opens up the possibility of developing a new type of radiation therapy for cancer.

scholarly journals X-Ray Evidence for the Acceleration, Containment, and Emission of High Energy Flare Particles

1974 ◽  
Vol 57 ◽  
pp. 421-422 ◽  
Author(s):  
Kenneth J. Frost
Keyword(s):  
Cosmic Ray ◽  
High Energy ◽  
Solar Observatory ◽  
Time Structure ◽  
Radio Bursts ◽  
X Rays ◽  
Thermal Component ◽  
X Ray ◽  
Type Iii ◽  
Explosive Phase

An instrument aboard the Fifth Orbiting Solar Observatory has observed hard solar X-rays from January 1969 to May 1972. A large number of X-ray bursts generated by solar cosmic ray flares have been observed. The X-ray bursts consist, in general, of two non-thermal components. The earliest occurring non-thermal component, coincident with the explosive phase, consists of a group of one to about ten X-ray bursts that are, for each burst, approximately 10 s duration and symmetrical in rise and decay. The time structure and multiplicity of these bursts is remarkably similar to that found in type III radio bursts in the meterwave band. The spectra of these bursts steepens sharply at energies greater than 100 keV indicating a limit at this energy for electron acceleration during the explosive or flash phase of the flare. For several flares these multiple X-ray bursts have occurred in coincidence with a group of type III bursts.

scholarly journals Diffuse cosmic X-rays from non-thermal intergalactic bremsstrahlung

1970 ◽  
Vol 37 ◽  
pp. 392-401
Author(s):  
Joseph Silk
Keyword(s):  
Cosmic Rays ◽  
Intergalactic Medium ◽  
Energy Requirement ◽  
Cosmic Ray ◽  
X Rays ◽  
Degree Of Ionization ◽  
X Ray ◽  
Normal Galaxies ◽  
X Ray Background ◽  
High Degree

The diffuse X-ray background between 1 keV and 1 MeV is interpreted as non-thermal bremsstrahlung in the intergalactic medium. The observed break in the X-ray spectrum at ∼40 keV yields the heat input to the intergalactic medium, the break being produced by ionization losses of sub-cosmic rays. Proton bremsstrahlung is found not to yield as satisfactory an agreement with observations as electron bremsstrahlung: excessive heating tends to occur. Two alternative models of cosmic ray injection are discussed, one involving continuous injection by evolving sources out to a redshift of about 3, and the other model involving injection by a burst of cosmic rays at a redshift of order 10. The energy density of intergalactic electrons required to produce the observed X-rays is ∼ 10−4 eV/cm3. Assuming a high density (∼ 10−5 cm−3) intergalactic medium, the energy requirement for cosmic ray injection by normal galaxies is ∼ 1058–59ergs/galaxy in sub-cosmic rays. The temperature evolution of the intergalactic medium is discussed, and we find that a similar energy input is also required to explain the observed high degree of ionization (if 3C9 is at a cosmological distance).

scholarly journals Face-on SS 433 Stars as a Possible New Type of Extragalactic X-Ray Sources

2001 ◽  
Vol 205 ◽  
pp. 268-269 ◽  
Author(s):  
S. Fabrika ◽  
A. Mescheryakov
Keyword(s):  
X Rays ◽  
Relativistic Jets ◽  
Expected Frequency ◽  
X Ray ◽  
Ss 433 ◽  
Sky Survey ◽  
Supercritical Accretion ◽  
The Face ◽  
New Type ◽  
Positive Correlations

The object SS433 is a well-known source of relativistic jets, which are formed in supercritical accretion disk. It is very probable that the disk has polar channels and their radiation is collimated (the photo-cones). A face-on SS433 object can appear as ultra-bright and highly variable X-ray source, Lx ˜ 1040 − 1042 erg/s. We discuss the properties of these hypothetical objects and their frequency expected in galaxies. We describe a search for such objects using the ROSAT All Sky Survey and RC3 catalog of galaxies. Among the total 418 positive correlations we find that 142 sources in S and Irr galaxies are unknown as AGNs. Nuclear sources among them still contain many AGNs. Non-nuclear (offset) sources are rather hard, their X-ray luminosities are 1039 − 1041 erg/s. Their observed frequency is about 4–5% per galaxy, that is in agreement with expected frequency of the face-on SS 433 stars. The only way to recognize such stars is their expected violent variability in X rays.

First results from the XMCD facility at the Energy-Dispersive EXAFS beamline of the Indus-2 synchrotron source

2019 ◽  
Vol 26 (2) ◽  
pp. 445-449
Author(s):  
N. Patra ◽  
U. G. P. S. Sachan ◽  
S. SundarRajan ◽  
Sanjay Malhotra ◽  
Vijay Harad ◽  
...  
Keyword(s):  
Magnetic Circular Dichroism ◽  
Energy Dispersive ◽  
X Rays ◽  
Beam Direction ◽  
Synchrotron Source ◽  
X Ray ◽  
Synchrotron Beam ◽  
First Results ◽  
Set Up ◽  
Good Agreement

Setting up of the X-ray Magnetic Circular Dichroism (XMCD) measurement facility with hard X-rays at the Energy-Dispersive EXAFS beamline (BL-08) at the Indus-2 synchrotron source is reported. This includes the design and development of a water-cooled electromagnet having a highest magnetic field of 2 T in a good field volume of 125 mm3 and having a 10 mm hole throughout for passage of the synchrotron beam. This also includes the development of an (X–Z–θ) motion stage for the heavy electromagnet for aligning its axis and the beam hole along the synchrotron beam direction. Along with the above developments, also reported is the first XMCD signal measured on a thick Gd film in the above set-up which shows good agreement with the reported results. This is the first facility to carry out XMCD measurement with hard X-rays in India.

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