scholarly journals Linear Breit-Wheeler pair production by high-energy bremsstrahlung photons colliding with an intense x-ray laser pulse

2021 ◽  
Vol 103 (1) ◽  
Author(s):  
A. Golub ◽  
S. Villalba-Chávez ◽  
H. Ruhl ◽  
C. Müller
Keyword(s):  
Laser Pulse ◽  
Pair Production ◽  
High Energy ◽  
X Ray ◽  
Bremsstrahlung Photons

Science of High Energy, Single-Cycled Lasers

2019 ◽  
Vol 10 (01) ◽  
pp. 227-244
Author(s):  
Jonathan A. Wheeler ◽  
Gérard Mourou ◽  
Toshiki Tajima
Keyword(s):  
Laser Pulse ◽  
Laser Pulses ◽  
High Energy ◽  
New Developments ◽  
X Ray ◽  
Ion Accelerator ◽  
Laser Acceleration ◽  
High Field Science ◽  
New Applications ◽  
Wakefield Accelerator

With the advent of the Thin Film Compression, high energy single-cycled laser pulses have become an eminent path to the future of new high-field science. An existing CPA high power laser pulse such as a commercially available PW laser may be readily converted into a single-cycled laser pulse in the 10PW regime without losing much energy through the compression. We examine some of the scientific applications of this, such as laser ion accelerator called single-cycle laser acceleration (SCLA) and bow wake electron acceleration. Further, such a single-cycled laser pulse may be readily converted through relativistic compression into a single-cycled, X-ray laser pulse. We see that this is the quickest and very innovative way to ascend to the EW (exawatt) and zs (zeptosecond) science and technology. We suggest that such X-ray laser pulses have a broad and new horizon of applications. We have begun exploring the X-ray crystal (or nanostructured) wakefield accelerator and its broad and new applications into gamma rays. Here, we make a brief sketch of our survey of this vista of the new developments.

scholarly journals Resonant Ultrarelativistic Electron–Positron Pair Production by High-Energy Electrons in the Field of an X-ray Pulsar

Universe ◽  
2020 ◽  
Vol 6 (9) ◽  
pp. 132 ◽  
Author(s):  
Georgii K. Sizykh ◽  
Sergei P. Roshchupkin ◽  
Victor V. Dubov
Keyword(s):  
Pair Production ◽  
Threshold Energy ◽  
Structure Constant ◽  
High Energy ◽  
Differential Probability ◽  
X Ray ◽  
Initial Electron ◽  
Ultrarelativistic Electron ◽  
Electron Positron ◽  
Electron Positron Pair

The process of resonant high-energy electron–positron pair production by an ultrarelativistic electron colliding with the field of an X-ray pulsar is theoretically investigated. Resonant kinematics of the process is studied in detail. Under the resonance condition, the intermediate virtual photon in the X-ray pulsar field becomes a real particle. As a result, the initial process of the second order in the fine structure constant effectively reduces into two successive processes of the first order: X-ray-stimulated Compton effect and X-ray-stimulated Breit–Wheeler process. For a high-energy initial electron all the final ultrarelativistic particles propagate in a narrow cone along the direction of the initial electron momentum. The presence of threshold energy for the initial electron which is of order of 100 MeV for 1-KeV-frequency field is shown. At the same time, the energy spectrum of the final particles (two electrons and a positron) highly depends on their exit angles and on the initial electron energy. This result significantly distinguishes the resonant process from the non-resonant one. It is shown that the resonant differential probability significantly exceeds the non-resonant one.

The influence of pre-pulse plasma on ion and x-ray emission from Ta plasma produced by a high-energy laser pulse

2004 ◽  
Vol 54 (S3) ◽  
pp. C385-C390 ◽  
Author(s):  
J. Woŀowski ◽  
J. Badziak ◽  
P. Parys ◽  
M. Rosiński ◽  
L. Ryć ◽  
...  
Keyword(s):  
Laser Pulse ◽  
High Energy ◽  
Pulse Plasma ◽  
X Ray ◽  
Energy Laser ◽  
High Energy Laser

scholarly journals Wakefield acceleration

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
T. Tajima ◽  
X. Q. Yan ◽  
T. Ebisuzaki
Keyword(s):  
Laser Pulse ◽  
Phase Velocity ◽  
High Energy ◽  
Intense Laser ◽  
Ion Acceleration ◽  
Laser Wakefield Acceleration ◽  
X Ray ◽  
Wakefield Acceleration ◽  
Chirped Pulse Amplification ◽  
High Field Science

AbstractThe fundamental idea of Laser Wakefield Acceleration (LWFA) is reviewed. An ultrafast intense laser pulse drives coherent wakefields of relativistic amplitude with the high phase velocity robustly supported by the plasma. The structures of wakes and sheaths in plasma are contrasted. While the large amplitude of wakefields involves collective resonant oscillations of the eigenmode of the entire plasma electrons, the wake phase velocity ~ c and ultrafastness of the laser pulse introduce the wake stability and rigidity. When the phase velocity gets smaller, wakefields turn into sheaths. When we deploy laser ion acceleration or high density LWFA in which the phase velocity of plasma excitation is low, we encounter the sheath dynamics. A large number of world-wide experiments show a rapid progress of this concept realization toward both the high energy accelerator prospect and broad applications. The strong interest in this has driven novel laser technologies, including the Chirped Pulse Amplification, the Thin Film Compression (TFC), the Coherent Amplification Network, and the Relativistic Compression (RC). These in turn have created a conglomerate of novel science and technology with LWFA to form a new genre of high field science with many parameters of merit in this field increasing exponentially lately. Applications such as ion acceleration, X-ray free electron laser, electron and ion cancer therapy are discussed. A new avenue of LWFA using nanomaterials is also emerging, adopting X-ray laser using the above TFC and RC. Meanwhile, we find evidence that the Mother Nature spontaneously created wakefields that accelerate electrons and ions to very high energies.

scholarly journals Pair production tomography imaging

2021 ◽  
Author(s):  
Qihui Lyu ◽  
Ryan Neph ◽  
Ke Sheng
Keyword(s):  
Pair Production ◽  
Time Resolution ◽  
Image Formation ◽  
Underlying Mechanism ◽  
High Energy ◽  
High Signal ◽  
X Rays ◽  
X Ray ◽  
Radiotherapy Treatment

Abstract X-ray Computed Tomography (CT) is an exceptionally versatile tool for diagnosis and detection. Despite numerous technological evolutions, the underlying mechanism for CT image formation has not changed. To markedly expand beyond the current capacity of X-ray CT based on a new image formation mechanism, we introduce pair production tomography (P2T) imaging. Unlike CT, whose signals arise from attenuation of the incident photons, P2T collects coincident annihilation photons originated from the pair production interaction with high energy X-rays for tomographic reconstruction. We studied three P2T acquisition methods, including filtered back projection (FBP), time-of-flight (TOF), and scanning pencil beam (SPB). Using Monte Carlo simulation on phantom and patient data, we demonstrate three distinctly new capabilities for P2T: high linearity with the material atomic number for element mapping and soft tissue differentiation, the ability to form tomography with as few as a single heavily truncated X-ray beam, and in vivo radiotherapy treatment dose verification and monitoring. Among the three P2T acquisition methods, FBP is the least technically demanding, but its utility is limited to high radiation dose procedures such as radiotherapy treatment monitoring. Both TOF and SPB result in high signal-to-noise ratio (SNR) P2T images with a typical imaging dose. The quality of TOF relies on the time resolution of detectors. In comparison, SPB suppresses localization errors based on the known excitation path, which significantly mitigates the detector time resolution requirement.

High-purity Ge x-ray detectors: Sensitivity factors and usefulness

1990 ◽  
Vol 48 (2) ◽  
pp. 548-548
Author(s):  
E. B. Steel
Keyword(s):  
High Purity ◽  
High Energy ◽  
Quantitative Chemical Analysis ◽  
Detector Performance ◽  
X Ray ◽  
Detector Sensitivity ◽  
Specimen Holder ◽  
Many Instruments ◽  
Charge Resolution ◽  
Sensitivity Factors

High Purity Germanium (HPGe) x-ray detectors are now commercially available for the analytical electron microscope (AEM). The detectors have superior efficiency at high x-ray energies and superior resolution compared to traditional lithium-drifted silicon [Si(Li)] detectors. However, just as for the Si(Li), the use of the HPGe detectors requires the determination of sensitivity factors for the quantitative chemical analysis of specimens in the AEM. Detector performance, including incomplete charge, resolution, and durability has been compared to a first generation detector. Sensitivity factors for many elements with atomic numbers 10 through 92 have been determined at 100, 200, and 300 keV. This data is compared to Si(Li) detector sensitivity factors.The overall sensitivity and utility of high energy K-lines are reviewed and discussed. Many instruments have one or more high energy K-line backgrounds that will affect specific analytes. One detector-instrument-specimen holder combination had a consistent Pb K-line background while another had a W K-line background.

Designing high-resolution slow scan CCD-based TEM camera systems

1992 ◽  
Vol 50 (2) ◽  
pp. 946-947
Author(s):  
James F. Mancuso ◽  
William B. Maxwell ◽  
Russell E. Camp ◽  
Mark H. Ellisman
Keyword(s):  
Fiber Optics ◽  
Ccd Camera ◽  
High Energy ◽  
Phosphor Layer ◽  
X Ray ◽  
Light Production ◽  
Camera Systems ◽  
X Ray Imaging ◽  
Electron Image ◽  
Scintillating Fiber

The imaging requirements for 1000 line CCD camera systems include resolution, sensitivity, and field of view. In electronic camera systems these characteristics are determined primarily by the performance of the electro-optic interface. This component converts the electron image into a light image which is ultimately received by a camera sensor.Light production in the interface occurs when high energy electrons strike a phosphor or scintillator. Resolution is limited by electron scattering and absorption. For a constant resolution, more energy deposition occurs in denser phosphors (Figure 1). In this respect, high density x-ray phosphors such as Gd2O2S are better than ZnS based cathode ray tube phosphors. Scintillating fiber optics can be used instead of a discrete phosphor layer. The resolution of scintillating fiber optics that are used in x-ray imaging exceed 20 1p/mm and can be made very large. An example of a digital TEM image using a scintillating fiber optic plate is shown in Figure 2.

The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis

1985 ◽  
Vol 43 ◽  
pp. 154-157
Author(s):  
A.J. Tousimis
Keyword(s):  
Ion Beam ◽  
Depth Resolution ◽  
Sample Surface ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Electrons And Ions ◽  
Spatial Depth ◽  
Minimum Surface Area ◽  
Physical Principles

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.

Utilisation of High-Energy Heat Sources in Magnesium Alloy Surface Layer Treatment

2013 ◽  
Vol 58 (2) ◽  
pp. 619-624 ◽  
Author(s):  
M. Szafarska ◽  
J. Iwaszko ◽  
K. Kudła ◽  
I. Łegowik
Keyword(s):  
Surface Layer ◽  
Magnesium Alloy ◽  
Physicochemical Properties ◽  
Treatment Effectiveness ◽  
High Energy ◽  
Alloy Surface ◽  
Heat Sources ◽  
X Ray ◽  
Additional Equipment ◽  
Alloy Surface Layer

The main aim of the study was the evaluation of magnesium alloy surface treatment effectiveness using high-energy heat sources, i.e. a Yb-YAG Disk Laser and the GTAW method. The AZ91 and AM60 commercial magnesium alloys were subject to surface layer modification. Because of the physicochemical properties of the materials studied in case of the GTAW method, it was necessary to provide the welding stand with additional equipment. A novel two-torch set with torches operating in tandem was developed within the experiment. The effectiveness of specimen remelting using a laser and the GTAW method was verified based on macro- and microscopic examinations as well as in X-ray phase analysis and hardness measurements. In addition, the remelting parameters were optimised. The proposed treatment methodology enabled the achieving of the intended result and effective modification of a magnesium alloy surface layer.

Mesoscale structural characterization within bulk materials by high-energy X-ray microdiffraction

AIAA Journal ◽  
2001 ◽  
Vol 39 ◽  
pp. 919-923
Author(s):  
U. Lienert ◽  
H. F. Poulsen ◽  
A. Kvick
Keyword(s):  
Structural Characterization ◽  
High Energy ◽  
Bulk Materials ◽  
X Ray
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