On Lensless Imaging of Organics with Neutrons, X-Rays, Helium Atoms and Low Energy Electrons: Damage and Iterative Phase Retrieval

2001 ◽  
Vol 7 (S2) ◽  
pp. 268-269
Author(s):  
J.C.H. Spence ◽  
U. Weierstall ◽  
J. Fries
Keyword(s):  
Phase Retrieval ◽  
Iterative Algorithms ◽  
High Energy ◽  
Low Energy ◽  
X Rays ◽  
Noise Sources ◽  
Helium Atoms ◽  
High Energy Electrons ◽  
Elastic Event ◽  
Low Energy Electrons

Recent experiments with X-rays and high energy electrons have shown that image recovery from diffracted intensities is possible for non-periodic objects using iterative algorithms. Application of these methods to biological molecules raises the crucial problem of radiation damage, which may be quantified by Q = ΔE σi/σe, the amount of energy deposited by inelastic events per elastic event. Neutrons, helium atoms and low energy electrons below most ionization thresholds produce the smallest values of Q (see for TMV imaged at 60 eV). For neutrons (λ = 10-2Å, and deuterated, 15N-abelled molecules) Q is ∼3000 times smaller (∼50 times for λ = 1.8Å) than for electrons (80- 500keV) and about 4x 106 times smaller than for soft X-rays (1.5Å). Since σe for neutrons is about 105 times smaller than for electrons (and about 10 times smaller than for soft X-rays), a 105 times higher neutron dose is required to obtain the same S/N in a phase contrast image compared with electrons, if other noise sources are absent.

scholarly journals Symmetric and triangle-shaped variability of blazars

2014 ◽  
Vol 10 (S313) ◽  
pp. 97-98
Author(s):  
Kenji Yoshida
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Low Energy ◽  
Light Curves ◽  
X Ray ◽  
High Energy Electrons ◽  
Flux Variability ◽  
Low Energy Electrons ◽  
Flux Increase ◽  
Rise Phase

AbstractSymmetric and triangle-shaped flux variability in X-ray and gamma-ray light curves is observed from many blazars. We derived the X-ray spectrum changing in time by using a kinetic equation of high energy electrons. Giving linearly changing the injection of low energy electrons into accelerating and emitting region, we obtained the preliminary results that represent the characteristic X-ray variability of the linear flux increase with hardening in the rise phase and the linear decrease with softening in the decay phase.

scholarly journals The Role of Low Energy Electrons in Radiobiology and Cancer Treatment

2021 ◽  
Author(s):  
Sasan Esmaili ◽  
Farzaneh Allaveisi
Keyword(s):  
Cancer Treatment ◽  
Anticancer Agents ◽  
High Energy ◽  
Low Energy ◽  
New Drugs ◽  
Particle Radiation ◽  
Energy Radiation ◽  
Regulatory Pathways ◽  
High Energy Electrons ◽  
Low Energy Electrons

Low energy radiation can be produced by all types of high energy radiation. Studies of low energy particle radiation help us to understand the chemistry induced by high energy radiations. Low energy electrons are capable of chemical selectivity in contrast to high energy electrons due to the large number of open dissociative channels in the former case and their resonant nature. Among different types of radiation, low energy electrons have a higher cross-section to DNA damage and they have an important role in the synergistic effect between radiation and chemotherapy anticancer agents in cancer treatment. Analysis of these combined records helps assign function of cells, identify metabolic and regulatory pathways and suggest targets for diagnostics and therapeutics identify animal models to develop new drugs, among other goals of biomedical interest.

scholarly journals Auger Spectroscopy and Surface Analysis

1997 ◽  
Vol 50 (4) ◽  
pp. 745 ◽  
Author(s):  
S. M. Thurgate
Keyword(s):  
Short Distance ◽  
Auger Spectroscopy ◽  
Low Energy ◽  
Simultaneous Occurrence ◽  
X Rays ◽  
Auger Process ◽  
Surface Layers ◽  
Auger Electrons ◽  
Low Energy Electrons ◽  
Auger Spectra

Abstract In 1925 Pierre Auger reported on his observations of low energy electrons associated with core-ionised atoms in cloud chamber experiments. He was able to correctly identify the mechanism for their production, and such electrons are now known as Auger electrons. Typically Auger electrons have energies in the range 10 eV to 2 keV. The short distance that such low energy electrons travel in solids ensures that Auger electrons come from the surface layers. The data generated by the AES technique are complex. There are at least three electrons involved in the process, and there are many possible configurations for the atom. These possibilities led to spectra that are not readily interpreted in detail. Theory lags behind experiment in this area. In principle, it should be possible to find information about the chemical environment of atoms from Auger spectra. While there are clear changes in spectral lineshapes, there is no simple way to go from the spectra to an understanding of the chemical bonding of the atom. There are a number of experiments currently underway which aim to improve our understanding of the Auger process. Synchrotron experiments with tunable energy x-rays are providing new insight. Experiments that use positrons to excite Auger emission have also produced further recent understanding. Coincidence experiments between photoelectrons and Auger electrons have also made recent advances. Auger photoelectron coincidence spectroscopy reduces the complexity of Auger spectra by only counting those electrons that occur as a consequence of selected ionisations. The effect is to reduce the complexity of the spectra, and to isolate processes that are often clouded by the simultaneous occurrence of other effects.

Thermoluminescence of irradiated ammonium perchlorate crystals

1976 ◽  
Vol 54 (7) ◽  
pp. 766-770 ◽  
Author(s):  
S. Radhakrishna ◽  
M. Riggin ◽  
P. W. Whippey ◽  
P. W. M. Jacobs
Keyword(s):  
Absorption Spectrum ◽  
Single Crystals ◽  
Heating Rate ◽  
Ammonium Perchlorate ◽  
Uv Light ◽  
High Energy ◽  
X Rays ◽  
Spectroscopic Evidence ◽  
Additional Peak ◽  
High Energy Electrons

The thermoluminescence of single crystals of ammonium perchlorate irradiated with X rays, uv light, or high energy electrons has been measured between 80 and 420 K. With a heating rate of 5 K/min. prominent peaks occur at 95, 113, 134, 246, and 320 K; an additional peak is found at 347 K after longer irradiation times. The absorption spectrum of uv-irradiated ammonium perchlorate has also been measured and shows bands at 300, 360, and 610 nm. A comparison of these data with chemical and spectroscopic evidence obtained by other workers has permitted the probable identification of ClO3−, ClO−, ClO2, and F centres as radiation products. Three thermoluminescent peaks remain unassigned.

Deformation of cube-textured aluminum studied using laser-induced photoelectron emission

2007 ◽  
Vol 22 (9) ◽  
pp. 2582-2589 ◽  
Author(s):  
M. Cai ◽  
S.C. Langford ◽  
J.T. Dickinson ◽  
L.E. Levine
Keyword(s):  
Kinetic Energy ◽  
Energy Distribution ◽  
Tensile Deformation ◽  
High Energy ◽  
Field Energy ◽  
Electron Backscattered Diffraction ◽  
Grain Rotation ◽  
High Energy Electrons ◽  
Low Energy Electrons ◽  
Major Surface

The evolution of the kinetic energy distribution of photoelectrons from a cube-oriented aluminum sample during tensile deformation was probed with a retarding field energy analyzer. Because of the anisotropy of the aluminum work function, the electron-energy distribution is altered as the area fractions of the major surface planes change during deformation. In cube-textured aluminum, deformation reduces the {100} area fraction and the relatively low energy electrons from these surfaces. Conversely, the {110} and {111} area fractions and the relatively high energy electrons from these surfaces both increase. These changes are quantitatively consistent with texture analysis by electron backscattered diffraction (EBSD). They reflect deformation-induced production of {111} surfaces by slip and the exposure of {110} surfaces by grain rotation. Photoelectron kinetic energy measurements supplement EBSD measurements and are readily acquired in real-time.

scholarly journals Creation of High-Energy Electron Tails by the Lower-Hybrid Waves and its Relevance to Type II and III Bursts

1985 ◽  
Vol 107 ◽  
pp. 505-508
Author(s):  
Motohiko Tanaka ◽  
K. Papadopoulos
Keyword(s):  
High Energy ◽  
Lower Hybrid ◽  
X Rays ◽  
Type Ii ◽  
High Energy Electron ◽  
Acceleration Mechanism ◽  
High Energy Electrons ◽  
Wave Emission ◽  
Hybrid Waves ◽  
Lower Hybrid Waves

It is commonly anticipated that high-energy electrons play an important role for the wave emission in flare bursts. For instance, electrons with >100 KeV are considered to create microwave emissions through gyro-synchrotron process and hard x-rays may be due to bremstrahlung with >25 KeV electrons. However, electron acceleration mechanism itself is still in speculations.

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