scholarly journals A Two-accelerator Facility and Its Use for Radiation Damage Studies in Alkali Halides

1980 ◽  
Vol 33 (3) ◽  
pp. 549
Author(s):  
CS Newton ◽  
HJ Hay
Keyword(s):  
Radiation Damage ◽  
Simultaneous Detection ◽  
Experimental Studies ◽  
Target Material ◽  
Experimental System ◽  
Alkali Halides ◽  
Damage Mechanism ◽  
X Rays ◽  
Accelerator Facility ◽  
Light Ions

An experimental system is described in which heavy ions of energies 50-100 MeV, and light ions of energies 0�5-2 MeV, may be transported alternatively from different accelerators into a common scattering chamber. Details are given of the beam transport and ~ttering chamber, the latter being designed to make in-beam studies of different modes of radiation damage in the target material. An on-line experimental control and data acquisition system with an IBM 1800 computer is used. Experimental studies are described of simultaneous detection of backscattered helium ions, X-rays and optical absorption in single-crystal alkali halide samples, performed during continuous irradiation by a 1 MeV helium beam, as well as of backscattered protons following intermittent irradiation by a 60 MeV oxygen beam. Analysis of the relative damage by these two beams is discussed in relation to a damage mechanism due to Pooley.

Studies of metaphase chromosomes in the scanning transmission x-ray microscope: Image fidelity, radiation damage and specimen preparation

1992 ◽  
Vol 50 (2) ◽  
pp. 1038-1039
Author(s):  
Shawn Williams ◽  
Xiaodong Zhang ◽  
Susan Lamm ◽  
Jack Van’t Hof
Keyword(s):  
Visible Light ◽  
Radiation Damage ◽  
Cross Section ◽  
Imaging Techniques ◽  
Dose Range ◽  
Specimen Preparation ◽  
X Rays ◽  
Metaphase Chromosomes ◽  
X Ray ◽  
Scanning Transmission

The Scanning Transmission X-ray Microscope (STXM) is well suited for investigating metaphase chromosome structure. The absorption cross-section of soft x-rays having energies between the carbon and oxygen K edges (284 - 531 eV) is 6 - 9.5 times greater for organic specimens than for water, which permits one to examine unstained, wet biological specimens with resolution superior to that attainable using visible light. The attenuation length of the x-rays is suitable for imaging micron thick specimens without sectioning. This large difference in cross-section yields good specimen contrast, so that fewer soft x-rays than electrons are required to image wet biological specimens at a given resolution. But most imaging techniques delivering better resolution than visible light produce radiation damage. Soft x-rays are known to be very effective in damaging biological specimens. The STXM is constructed to minimize specimen dose, but it is important to measure the actual damage induced as a function of dose in order to determine the dose range within which radiation damage does not compromise image quality.

Contribution of x-ray total reflection to the background intensity in EPMA

1990 ◽  
Vol 48 (2) ◽  
pp. 202-203
Author(s):  
Werner P. Rehbach ◽  
Peter Karduck
Keyword(s):  
Atomic Number ◽  
Target Material ◽  
Total Reflection ◽  
Background Intensity ◽  
X Rays ◽  
Characteristic Radiation ◽  
X Ray

In the EPMA of soft x rays anomalies in the background are found for several elements. In the literature extremely high backgrounds in the region of the OKα line are reported for C, Al, Si, Mo, and Zr. We found the same effect also for Boron (Fig. 1). For small glancing angles θ, the background measured using a LdSte crystal is significantly higher for B compared with BN and C, although the latter are of higher atomic number. It would be expected, that , characteristic radiation missing, the background IB (bremsstrahlung) is proportional Zn by variation of the atomic number of the target material. According to Kramers n has the value of unity, whereas Rao-Sahib and Wittry proposed values between 1.12 and 1.38 , depending on Z, E and Eo. In all cases IB should increase with increasing atomic number Z. The measured values are in discrepancy with the expected ones.

Specimen Preparation of Near Surface Ion Irradiated Samples

1985 ◽  
Vol 43 ◽  
pp. 170-171
Author(s):  
K. F. Russell ◽  
L. L. Horton
Keyword(s):  
Radiation Damage ◽  
Heavy Ions ◽  
Target Material ◽  
Metal Alloys ◽  
Specimen Surface ◽  
Specimen Preparation ◽  
Particle Accelerators ◽  
Near Surface ◽  
Graaff Accelerator ◽  
Van De Graaff

Beams of heavy ions from particle accelerators are used to produce radiation damage in metal alloys. The damaged layer extends several microns below the surface of the specimen with the maximum damage and depth dependent upon the energy of the ions, type of ions, and target material. Using 4 MeV heavy ions from a Van de Graaff accelerator causes peak damage approximately 1 μm below the specimen surface. To study this area, it is necessary to remove a thickness of approximately 1 μm of damaged metal from the surface (referred to as “sectioning“) and to electropolish this region to electron transparency from the unirradiated surface (referred to as “backthinning“). We have developed electropolishing techniques to obtain electron transparent regions at any depth below the surface of a standard TEM disk. These techniques may be applied wherever TEM information is needed at a specific subsurface position.

Morphological and structural evolution of WS2 nanosheets irradiated with an electron beam

2015 ◽  
Vol 17 (4) ◽  
pp. 2678-2685 ◽  
Author(s):  
Yuqing Wang ◽  
Yi Feng ◽  
Yangming Chen ◽  
Fei Mo ◽  
Gang Qian ◽  
...  
Keyword(s):  
Electron Beam ◽  
Radiation Damage ◽  
Structural Evolution ◽  
Damage Mechanism ◽  
P Movement ◽  
Ws2 Nanosheets

Movement of atoms and the radiation damage mechanism in irradiated WS2 nanosheets.

scholarly journals A comprehensive Monte Carlo study to design a novel multi-nanoparticle loaded nanocomposites for augmentation of attenuation coefficient in the energy range of diagnostic X-rays

2021 ◽  
Vol 27 (4) ◽  
pp. 279-289
Author(s):  
Elahe Sayyadi ◽  
Asghar Mesbahi ◽  
Reza Eghdam Zamiri ◽  
Farshad Seyyed Nejad
Keyword(s):  
Monte Carlo ◽  
Energy Range ◽  
Radiation Protection ◽  
Experimental Studies ◽  
Rubber Matrix ◽  
Photon Flux ◽  
Monte Carlo Code ◽  
X Rays ◽  
Wide Range ◽  
Shielding Properties

Abstract Introduction: The present study aimed to investigate the radiation protection properties of silicon-based composites doped with nano-sized Bi2O3, PbO, Sm2O3, Gd2O3, WO3, and IrO2 particles. Radiation shielding properties of Sm2O3 and IrO2 nanoparticles were investigated for the first time in the current study. Material and methods: The MCNPX (2.7.0) Monte Carlo code was utilized to calculate the linear attenuation coefficients of single and multi-nano structured composites over the X-ray energy range of 10–140 keV. Homogenous distribution of spherical nanoparticles with a diameter of 100 nm in a silicon rubber matrix was simulated. The narrow beam geometry was used to calculate the photon flux after attenuation by designed nanocomposites. Results: Based on results obtained for single nanoparticle composites, three combinations of different nano-sized fillers Sm2O3+WO3+Bi2O3, Gd2O3+WO3+Bi2O3, and Sm2O3+WO3+PbO were selected, and their shielding properties were estimated. In the energy range of 20-60 keV Sm2O3 and Gd2O3 nanoparticles, in 70-100 keV energy range WO3 and for photons energy higher than 90 keV, PbO and Bi2O3 nanoparticles showed higher attenuation. Despite its higher density, IrO2 had lower attenuation compared to other nanocomposites. The results showed that the nanocomposite containing Sm2O3, WO3, and Bi2O3 nanoparticles provided better shielding among the studied samples. Conclusions: All studied multi-nanoparticle nanocomposites provided optimum shielding properties and almost 8% higher attenuation relative to single nano-based composites over a wide range of photon energy used in diagnostic radiology. Application of these new composites is recommended in radiation protection. Further experimental studies are suggested to validate our findings.

scholarly journals A STUDY ON RADIATION DAMAGE MECHANISM IN PbWO4 SCITILLATING CRYSTALS

1999 ◽  
Vol 48 (7) ◽  
pp. 1282
Author(s):  
FENG XI-QI ◽  
HAN BAO-GUO ◽  
HU GUAN-QIN ◽  
ZHANG YAN-XING
Keyword(s):  
Radiation Damage ◽  
Damage Mechanism

Detection of a metallic glass layer by x-ray diffraction

1986 ◽  
Vol 1 (5) ◽  
pp. 629-634 ◽  
Author(s):  
J.W. McCamy ◽  
M.J. Godbole ◽  
A.J. Pedraza ◽  
D.H. Lowndes
Keyword(s):  
Target Material ◽  
Amorphous Layer ◽  
Glass Layer ◽  
X Rays ◽  
Average Thickness ◽  
X Ray Diffraction ◽  
Near Surface ◽  
X Ray ◽  
Integrated Intensity ◽  
Thickness Measurements

A simple, precise method for obtaining the average thickness of an amorphous layer formed by any surface treatment has been developed. The technique uses an x-ray diffractoeter to measure the reduction in the integrated intensity of several diffracted x-ray lines due to the near surface amorphous layer. The target material for generation of x rays is selected so that the emitted x rays are strongly absorbed by the specimen. This method permits thickness measurements down to ∼ 100 nm. It has been tested on a specimen of Fe80B20 on which an amorphous layer was produced by pulsed XeCl (308 nm) laser irradiation; the amorphous layer thickness was found to be 1.34 (∼0.1) um.

scholarly journals The sensitivity of atomic analysis by X-rays

1932 ◽  
Vol 135 (828) ◽  
pp. 637-656 ◽  
Keyword(s):  
Atomic Number ◽  
Target Material ◽  
High Sensitivity ◽  
Major Constituent ◽  
X Rays ◽  
Depth Of Penetration ◽  
X Ray ◽  
Constituent Element ◽  
The Difference ◽  
Atomic Analysis

In a previous paper it was shown that 0·0007 per cent, of 29 Cu and 0·0003 per cent, of 26 Fe could be detected in 30 Zn by atomic analysis by X-ray spectroscopy. This sensitivity is greater than that which was claimed by Noddack, Tacke, and Berg, who set the limit at about 0·1 per cent, for non-metals, and by Hevesy, who stated it to be about 0·01 per cent, for an element present in an alloy. It was later suggested by Hevesy that the high value of the sensitivity which we found might result from the fact that some of the alloys we had used were composed of elements of almost equal atomic number, and that the sensitivity would be smaller for a constituent of low atomic number mixed with a major constituent of high atomic number. To elucidate these disagreements we have made further observations of the sensitivity with elements of different atomic number and have investigated the conditions which can influence the sensitivity. The Factors Determining Sensitivity . The detection of one element in a mixture of elements depends upon the identification of its K or L lines in the general spectrum emitted by the mixture under examination. The intensity with which these lines are excited in the target (“excited intensity”) is proportional to the number of atoms of the constituent element excited, i. e ., to its concentration and to the volume of the target in which the cathode ray energy is absorbed. The depth of penetration of the cathode rays is determined by the density of the target material and by their velocity ( i. e ., by the voltage applied to the X-ray tube). Schonland has shown that the range of homogeneous cathode rays in different elements, expressed as a mass per unit area, is approximately constant and is independent of the atomic number of the absorbing element. When their velocity is increased, the cathode rays will penetrate to a greater depth, and therefore a greater number of atoms of all constituents will be ionised. This will increase the “excited intensity” of the lines due to the particular constituent sought equally with those lines of the other elements present. The intensity of a line further depends upon the difference between the voltage applied to the X-ray tube and that necessary to excite the series. For these reasons, a high applied voltage is required for a high sensitivity.

THE IMMEDIATE EFFECTS OF SEVERE LOCAL X IRRADIATION ON THE LIVER OF THE HAMSTER

1952 ◽  
Vol 30 (6) ◽  
pp. 571-577
Author(s):  
Katherine E. Livingstone ◽  
David J. McCallion
Keyword(s):  
Experimental Studies ◽  
Liver Parenchyma ◽  
Liver Cells ◽  
The Body ◽  
Field Size ◽  
Cyclic Variation ◽  
X Rays ◽  
X Irradiation ◽  
Parenchymal Cells ◽  
Cyclic Fluctuation

Opinions regarding the radiosensitivity of the liver, based on clinical and experimental studies, differ widely. No comprehensive study of the immediate effects of severe local X irradiation upon the cytology of the liver parenchyma has been previously undertaken. In the present investigation cytological studies were made upon the livers of hamsters at 4-hr. intervals over a 24-hr. period. It was demonstrated that the amounts of cytoplasmic basophilia, glycogen, and sudanophilic fat show a cyclic variation over the 24-hr. period studied. Adult hamsters were exposed to X rays at the rate of 495 r. per minute with a total dosage of 2000 r. The field size over the liver was 4 cm. by 2 cm. with the rest of the body protected by a lead shield. Following irradiation the animals were sacrificed, two at a time, at 4 hr. intervals over a 24-hr. period. The amounts of basophilic material in the cytoplasm of the parenchymal cells of the liver were considerably decreased at 8 hr. and at 16 hr. after irradiation. At other times the cytoplasmic basophilia of the irradiated liver cells was approximately as dense as that of the control animals. The density of cytoplasmic basophilia showed a cyclic variation approximating that of the controls. The amount of glycogen in the irradiated livers was very much decreased, but still showed a cyclic fluctuation. There was a striking decrease in the amount of sudanophilic fat in the liver cells following irradiation. The results indicate that severe local X irradiation of the liver of the hamster has immediate effects directly upon that organ, resulting in a disturbance of its normal physiological activities.

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