CONTINUUM X RAYS IN HIGHLY CHARGED ION-ATOM COLLISIONS

1996 ◽  
Vol 06 (03n04) ◽  
pp. 441-445
Author(s):  
K. KAWATSURA ◽  
T. HASEGAWA ◽  
N. TERAZAWA ◽  
S. ARAI ◽  
M. SATAKA ◽  
...  
Keyword(s):  
Energy Region ◽  
Heavy Ion ◽  
X Rays ◽  
X Ray ◽  
Radiative Processes ◽  
Gas Target ◽  
Electron Bremsstrahlung ◽  
Low X ◽  
Atom Collision ◽  
The Continuum

Continuous X rays produced by highly charged heavy ion-atom collisions have been studied experimentally. 2–5.5 MeV/u F, Si, S and Cl ions with zero or one electron were bombarded with a thin gas target of H 2 and He. Emitted X-ray spectra were measured by using a Si(Li) X-ray detector at 90°. The characteristic X rays and radiative electron capture X rays were observed clearly, which were superimposed on the continuum X rays. The continuum X rays can be well explained by two types of radiative processes: mainly quasi-free electron bremsstrahlung (QFEB), and partly atomic bremsstrahlung (AB). It should be noticed that QFEB is predominant at low X-ray energy region and AB at high X-ray energy region in highly charged heavy ion-atom collision process.

CONTINUOUS BACKGROUNDS IN PIXE

1990 ◽  
Vol 01 (01) ◽  
pp. 1-29 ◽  
Author(s):  
KEIZO ISHII ◽  
SUSUMU MORITA
Keyword(s):  
Detection Limit ◽  
Heavy Ion ◽  
Projectile Energy ◽  
X Rays ◽  
Ion Energy ◽  
Electron Bremsstrahlung ◽  
Wide Range ◽  
Charge Dependence ◽  
Rutherford Scattering ◽  
Atom Collision

Continuous X rays produced by light-ion·atom collisions, which mainly form continuous backgrounds and determine the detection limit of PIXE, have been experimentally and theoretically studied, and it is shown that the experimental results over the wide range of projectile-ion energy from 0.5 MeV to 40 MeV can be well explained by three kinds of radiative process: atomic bremsstrahlung (AB), secondary-electron bremsstrahlung (SEB), and quasifree electron bremsstrahlung (QFEB). Results on the X-ray spectra, the projectile-energy dependence and the projectile-charge dependence, and on the angular distribution of these bremsstrahlungs will be summarized and the importance of AB in heavy-ion atom collision is presented. Discussions are also given on the other origins of continuous backgrounds such as the Compton scattering background, cosmic rays, the Rutherford scattering background, piling up of signals and response functions of detector, charge up effect of the target and natural backgrounds. On the basis of analyses of continuous backgrounds, the detection limit of PIXE is estimated.

scholarly journals X-ray spectra and light curves of cooling novae and a nova like

2020 ◽  
Vol 499 (2) ◽  
pp. 3006-3018
Author(s):  
Bangzheng Sun ◽  
Marina Orio ◽  
Andrej Dobrotka ◽  
Gerardo Juan Manuel Luna ◽  
Sergey Shugarov ◽  
...  
Keyword(s):  
Light Curve ◽  
Accretion Rate ◽  
High Energy ◽  
Gravitational Energy ◽  
Light Curves ◽  
Clear Correlation ◽  
X Rays ◽  
High State ◽  
X Ray ◽  
Low X

ABSTRACT We present X-ray observations of novae V2491 Cyg and KT Eri about 9 yr post-outburst of the dwarf nova and post-nova candidate EY Cyg, and of a VY Scl variable. The first three objects were observed with XMM–Newton, KT Eri also with the Chandra ACIS-S camera, V794 Aql with the Chandra ACIS-S camera and High Energy Transmission Gratings. The two recent novae, similar in outburst amplitude and light curve, appear very different at quiescence. Assuming half of the gravitational energy is irradiated in X-rays, V2491 Cyg is accreting at $\dot{m}=1.4\times 10^{-9}{\!-\!}10^{-8}\,{\rm M}_\odot \,{\rm yr}^{-1}$, while for KT Eri, $\dot{m}\lt 2\times 10^{-10}{\rm M}_\odot \,{\rm yr}$. V2491 Cyg shows signatures of a magnetized WD, specifically of an intermediate polar. A periodicity of  39 min, detected in outburst, was still measured and is likely due to WD rotation. EY Cyg is accreting at $\dot{m}\sim 1.8\times 10^{-11}{\rm M}_\odot \,{\rm yr}^{-1}$, one magnitude lower than KT Eri, consistently with its U Gem outburst behaviour and its quiescent UV flux. The X-rays are modulated with the orbital period, despite the system’s low inclination, probably due to the X-ray flux of the secondary. A period of  81 min is also detected, suggesting that it may also be an intermediate polar. V794 Aql had low X-ray luminosity during an optically high state, about the same level as in a recent optically low state. Thus, we find no clear correlation between optical and X-ray luminosity: the accretion rate seems unstable and variable. The very hard X-ray spectrum indicates a massive WD.

scholarly journals Iron Line Emission from NGC1068

1989 ◽  
Vol 134 ◽  
pp. 167-172
Author(s):  
Katsuji Koyama
Keyword(s):  
Energy Range ◽  
Power Law ◽  
Equivalent Width ◽  
Line Emission ◽  
X Rays ◽  
Iron Line ◽  
X Ray ◽  
Central Engine ◽  
Photon Index ◽  
The Continuum

X-ray emission in the 2–10 keV energy range was observed with the Ginga satellite from the Seyfert 2 galaxy NGC1068. The continuum spectrum can be described by a power-law of photon index about 1.5. An intense iron line at 6.5 keV with an equivalent width of 1.3 keV was clearly noticed. The X-ray flux was about 6 × 10 −12 erg/sec/cm2 or 3 × 1041 erg/sec, assuming a distance of 22 Mpc. The observed spectrum is consistent with the scattering and reprocessing of X-rays by the gas surrounding the central engine. With this picture we estimate that the X-ray flux of the central engine is about 1043 - 1044 erg/sec, a typical value for a Seyfert 1 galaxy.

scholarly journals Soft X-ray absorption spectroscopy in the low-energy region explored using an argon gas window

2020 ◽  
Vol 27 (4) ◽  
pp. 959-962
Author(s):  
Masanari Nagasaka
Keyword(s):  
Absorption Spectroscopy ◽  
Energy Region ◽  
Low Energy ◽  
X Rays ◽  
Argon Gas ◽  
X Ray ◽  
First Order ◽  
Helium Gas ◽  
Transmission Window ◽  
X Ray Absorption

The soft X-ray region below 200 eV is important for investigating chemical and biological phenomena since it covers K-edges of Li and B and L-edges of Si, P, S and Cl. Helium gas is generally used as the soft X-ray transmission window for soft X-ray absorption spectroscopy (XAS) under atmospheric conditions. However, the helium gas window cannot be applied to XAS in the low-energy region since transmitted soft X-rays mostly consist of high-order X-rays due to the low transmission of first-order X-rays. In this study, the argon gas window is proposed as a new soft X-ray transmission window in the low-energy region. High-order X-rays are removed by the absorption of the Ar L-edge (240 eV), and first-order X-rays become the major contribution of transmitted soft X-rays in the low-energy region. Under atmospheric argon conditions, the double-excitation Rydberg series of helium gas (60 eV), Si L-edge XAS of an Si3N4 membrane (100 eV) and S L-edge XAS of dimethyl sulfoxide gas (170 eV) are successfully measured, indicating that the argon gas window is effective for soft X-ray transmission in the low-energy region from 60 eV to 240 eV.

scholarly journals Non-solar gamma and X-ray astronomy: optical observations: (Invited discourse)

1970 ◽  
Vol 37 ◽  
pp. 151-161
Author(s):  
Hugh M. Johnson
Keyword(s):  
Variable Stars ◽  
Optical Observations ◽  
X Rays ◽  
Spectral Measurements ◽  
Optical Identification ◽  
Stellar Spectrum ◽  
X Ray ◽  
General Catalogue ◽  
The Continuum

An optical astronomer enters this field only by courtesy of those X-ray astronomers who pay some attention to accurate positional measurements of X-ray sources. So my first and last words are to ask X-ray observers to give more time to establishing positions of X-ray sources. It appears that in fact most effort has been spent on spectral measurements of X-rays, and this has led just to the classification of sources according to either of two mechanisms for the production of the continuum. In one or two early instances the extrapolated X-ray spectrum has been useful for predicting the brightness of the optical counterpart to be found. A typical uncertainty of making optical identification is that of Vel XR-1 for which Gursky et al. (1968) have given a position with an error box of 3 square degrees. One candidate I can suggest for this is CU Vel, the only variable star of the 1958 General Catalogue of Variable Stars inside the error box. It is interesting because it is assigned to the U Gem class with a range of photographic magnitudes from 10.7 to 15.5. The stellar spectrum has not been observed.

An Algorithm for the Description of White and Characteristic Tube Spectra (11 ≤ Z ≤ 83, 10keV ≤ Eo ≤ 50keV)

1991 ◽  
Vol 35 (B) ◽  
pp. 721-726 ◽  
Author(s):  
H. Ebel ◽  
H. Wiederschwinger ◽  
J. Wernisch ◽  
P.A. Pella
Keyword(s):  
Kinetic Energy ◽  
Cross Section ◽  
Atomic Number ◽  
Solid Angle ◽  
Electron Interaction ◽  
X Rays ◽  
X Ray ◽  
The Cross ◽  
Spectral Responses ◽  
The Continuum

Kramers described the cross section of electron interaction with target atoms of atomic number Z bywhere Eo is the kinetic energy of impinging electrons, and E o S) the energy of x-ray photons of the continuum, Smith et al modified this equation, introducing an exponent x, so thatWe applied the cross-section σS, E to the evaluation of experimental results. The evaluation of the measured spectral responses of the x-ray signals nE was performed bywhere f(deff) describes the absorption of x-rays of energy E in the target, RE accounts for backscattering of electrons, DE quantifies the efficiency of x-ray detection within the solid angle Ω.

Heavy Ion-Induced Characteristic X-Ray Generation as an Analytical Probe

1970 ◽  
Vol 14 ◽  
pp. 173-183 ◽  
Author(s):  
J. A. Cairns ◽  
D. F. Holloway ◽  
R. S. Nelson
Keyword(s):  
Cross Sections ◽  
Heavy Ions ◽  
Proton Irradiation ◽  
Heavy Ion ◽  
X Rays ◽  
X Ray ◽  
The Past ◽  
Tracer Techniques ◽  
New Type ◽  
Gas Volume

AbstractIncreasing attention is currently focused on the generation of characteristic x-ray by proton irradiation. This has the advantage of yielding “clean” x-ray- i. e. free from background brerasstrahlung radiation, from even the lightest elements. The disadvantage is that the yields are naturally much lower than those produced by electrons of the same energy. A recent study has extended characteristic x-ray production to a variety of heavy ions and has shown that the cross- sections for the production of clean x-rays are often higher , by as much as several orders of magnitude, than those produced by protons of the same energy. In addition, there has emerged a further advantage, viz. the ability of specially chosen heavy ions to excite characteristic x-ray from a particular element in a selective manner. Since heavy ions penetrate only a few hundred Angstroms in to most solids, the phenomenon can be used as the basis of a technique for the examination of surface deposits, or to measure depth distributions of impurities. For example, Kr ions can be used t o determine the range distribution of antimony which had been implanted in to silicon at 100 keV. The antimony concentration was determined as a function of ∼ 150 Å steps, and was found to exhibit a maximum concentration of ∼ 1 part in 103 of silicon at 450 Å below the surface, falling to zero concentration at ∼2000 Å a depth. In the past, in order to obtain the required degree of sensitivity, such range determinations have relied on radio active tracer techniques.An entirely new type of proportional counter has been developed during the course of these studies. This instrument, because of its special construction, can be positioned very close to targets in non-dispersive studies, so as to collect the highest possible fraction of emitted x-ray. It incorporates a replaceable anode unit, together with a built- in miniature head amplifier, and exhibits extremely good performance, particularly for ultra-soft x-ray. In addition, rotation of a dial on the end of the counter body allows alteration of the active gas volume during operation, and so permits tuning into x-rays of a particular energy.

The Effects of Heavy Ion Particles on Human Megakaryocytopoiesis and Thrombopoiesis.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4156-4156
Author(s):  
Ikuo Kashiwakura ◽  
Kenji Takahashi ◽  
Satoru Monzen ◽  
Kiyomi Eguchi-Kasai ◽  
Tsutomu Toki ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Ion Beam ◽  
Heavy Ion ◽  
X Rays ◽  
Dna Double Strand Breaks ◽  
Nuclear Facilities ◽  
Plasma Clot ◽  
Carbon Ion ◽  
X Ray ◽  
Carbon Ion Beam

Abstract Heavy ion particles provide unique properties in radiotherapy. However, they have also been shown to pose high risks for both work at nuclear facilities and astronauts participating in space missions. In a previous study, we demonstrated that in radio-sensitive megakaryocyte progenitor cells, namely colony-forming unit megakaryocytes (CFU-Meg), a degree of X-ray-induced damage was prevented by post-treatment with several cytokines. In this study, we analyzed the effects of heavy ion particles on megakaryocytopoiesis and thrombopoiesis. The CD34+ CFU-Meg were isolated from human placental and umbilical cord blood using a magnetic isolation kit and then were exposed to a carbon ion beam (LET=50 KeV/mm). They were cultured in a serum free medium supplemented with a thrombopoietin (TPO) alone or a combination of TPO plus other cytokines including stem cell factor, interleukin-3 (IL-3) and Flt3-ligand. The number of CFU-Meg was calculated by a plasma clot technique. The differentiation into megakaryocytes (CD41+) and the release of platelets (CD42a+) in a liquid culture were both analyzed by flow cytometry. The increase of gamma-H2AX, a marker of DNA double-strand breaks (DSBs) was also detected by flow cytometry. The sensitivity of CFU-Meg to a carbon ion beam was found to be extremely high and could not be lowered by any type of cytokines unlike X-rays. However, treatment with TPO plus IL-3 potentially induced megakaryocytopoiesis and thrombopoiesis at 14 days after the exposure to a carbon ion beam at 2 Gy. The cytokine treatment enhanced the induction of gamma-H2AX in X-ray-irradiated CD34+ CFU-Meg but not in a carbon ion beam-irradiated one. These results show that not only the downregulation of death signals, but also the repair of DSBs was less strongly promoted by cytokines in CFU-Meg exposed to a carbon ion beam than X-rays. Different treatments therefore are required to protect against megakaryocytopoiesis and thrombopoiesis damage by heavy ion particles.

OBSERVATION OF INTERFERENCE BETWEEN ATOMIC BREMSSTRAHLUNG AND NUCLEAR BREMSSTRAHLUNG

1999 ◽  
Vol 09 (01n02) ◽  
pp. 1-10 ◽  
Author(s):  
K. ISHII ◽  
T. SATOH ◽  
S. MATSUYAMA ◽  
H. YAMAZAKI ◽  
Y. TOKAI ◽  
...  
Keyword(s):  
Cross Sections ◽  
Energy Region ◽  
Production Cross ◽  
Angular Distributions ◽  
X Rays ◽  
Beam Direction ◽  
Aluminum Target ◽  
X Ray ◽  
Wide Range ◽  
Mev Protons

An aluminum target was bombarded with 1.5 MeV protons and continuous x-rays were measured at the angles of 45°, 90° and 135° with respect to the beam direction. By investigating the shape of the x-ray energy spectrum, it was recognized that, the continuous x-rays below 12 keV are atomic bremsstrahlung (AB) and those of above 12 keV are nuclear bremsstrahlung (NB), and AB and NB are mingled in the energy region of around 12 keV The x-ray energy dependence of angular distributions presented well a change from the process of AB to that of NB in the continuous x-ray spectrum. Interference between AB and NB were discussed on the basis of PWBA theory. Continuous x-ray production cross sections were calculated on the basis of PWBA BEA and a semi-classical theory and compared with the experimental results. The theoretical prediction reproduced well the experimental cross sections over the wide range of 6 orders in magnitude and of 2 keV – 35 keV in the energy except for the energy region mingled with AB and NB. The ratio of the theoretical cross sections to the experimental ones showed an interference effect between AB and NB in their mingled region.

${\rm{MeV}}\mbox{-}\left( {\rm{C}} \right)_{\rm{2}}^{\rm{ + }} $-ION-INDUCED Cu K X-RAY EMISSION

1995 ◽  
Vol 05 (01) ◽  
pp. 21-25
Author(s):  
Xia Zonghuang ◽  
Wang Qian ◽  
Shen Dingyu ◽  
Li Shuozhong
Keyword(s):  
Energy Region ◽  
Ion Beams ◽  
Low Energy ◽  
Broad Peak ◽  
X Rays ◽  
Experimental Uncertainty ◽  
X Ray ◽  
Copper Target ◽  
Ionization Effect

Cu K X-ray spectra for a copper target bombarded with ion beams of 1.4 [Formula: see text] ions, 2. 8 [Formula: see text] ions, and 3.0 MeV-Si+ ions have been measured with a Si(Li) detector. It is found that the Cu K X-ray spectrum for [Formula: see text] ion bombardments is almost same as that for C+ ion bombardments, whereas the spectrum for Si+ ion bombardments has a broad peak of MO X-rays in the low-energy region. The values of Kα/Kα+β for the Cu K X-rays are very close each other within the experimental uncertainty in these three cases. Thus, no multi-ionization effect is observed in the K X-ray emission by [Formula: see text] beam bombardments.

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