scholarly journals Efficiency enhancement of THz radiation from an electron bunch in a waveguide due to low-frequency stabilization

2020 ◽  
Vol 1697 ◽  
pp. 012058
Author(s):  
Yu S Oparina ◽  
V L Bratman ◽  
Yu Lurie ◽  
A V Savilov
Keyword(s):  
Electron Bunch ◽  
Low Frequency ◽  
Frequency Stabilization ◽  
Thz Radiation ◽  
Efficiency Enhancement

scholarly journals Clustering of atomic displacement parameters in bovine trypsin reveals a distributed lattice of atoms with shared chemical properties

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Viktor Ahlberg Gagnér ◽  
Ida Lundholm ◽  
Maria-Jose Garcia-Bonete ◽  
Helena Rodilla ◽  
Ran Friedman ◽  
...  
Keyword(s):  
Protein Dynamics ◽  
Structural Information ◽  
Low Frequency ◽  
Chemical Properties ◽  
Atomic Displacement ◽  
Thz Radiation ◽  
X Ray Crystallography ◽  
Bovine Trypsin ◽  
Main Challenge ◽  
Atomic Displacement Parameters

AbstractLow-frequency vibrations are crucial for protein structure and function, but only a few experimental techniques can shine light on them. The main challenge when addressing protein dynamics in the terahertz domain is the ubiquitous water that exhibit strong absorption. In this paper, we observe the protein atoms directly using X-ray crystallography in bovine trypsin at 100 K while irradiating the crystals with 0.5 THz radiation alternating on and off states. We observed that the anisotropy of atomic displacements increased upon terahertz irradiation. Atomic displacement similarities developed between chemically related atoms and between atoms of the catalytic machinery. This pattern likely arises from delocalized polar vibrational modes rather than delocalized elastic deformations or rigid-body displacements. The displacement correlation between these atoms were detected by a hierarchical clustering method, which can assist the analysis of other ultra-high resolution crystal structures. These experimental and analytical tools provide a detailed description of protein dynamics to complement the structural information from static diffraction experiments.

scholarly journals A distributed lattice of aligned atoms exists in a protein structure: A hierarchical clustering study of displacement parameters in bovine trypsin

2018 ◽  
Author(s):  
Viktor Ahlberg Gagnér ◽  
Ida Lundholm ◽  
Maria-Jose Garcia-Bonete ◽  
Helena Rodilla ◽  
Ran Friedman ◽  
...  
Keyword(s):  
Protein Structure ◽  
Low Frequency ◽  
Atomic Displacement ◽  
Thz Radiation ◽  
Vibrational Dynamics ◽  
X Ray Crystallography ◽  
Atomic Displacements ◽  
Bovine Trypsin ◽  
Main Challenge ◽  
And Function

AbstractLow-frequency vibrations are crucial for protein structure and function, but only a few experimental techniques can shine light on them. The main challenge when addressing protein dynamics in the terahertz domain is the ubiquitous water that exhibit strong absorption. In this paper, we observe the protein atoms directly using X-ray crystallography in bovine trypsin at 100 K while irradiating the crystals with 0.5 THz radiation alternating on and off states. We observed that the anisotropy of atomic displacements increases upon terahertz irradiation. Atomic displacement similarities develop between chemically related atoms and between atoms of the catalytic machinery. This pattern likely arise from delocalized polar vibrational modes rather than delocalized elastic deformations or rigid-body displacements. This method can ultimately reveal how the alignment of chemically related atoms and the underlying polar vibrational dynamics make a protein structure stable.

Dynamical effects on superradiant THz emission from an undulator

2019 ◽  
Vol 26 (3) ◽  
pp. 737-749 ◽  
Author(s):  
Gianluca Geloni ◽  
Takanori Tanikawa ◽  
Sergey Tomin
Keyword(s):  
Magnetic Field ◽  
Phase Space ◽  
Electron Bunch ◽  
Field Amplitude ◽  
Thz Radiation ◽  
Frequency Range ◽  
Output Intensity ◽  
Electron Bunches ◽  
The Impact ◽  
Longitudinal Phase

Superradiant emission occurs when ultra-relativistic electron bunches are compressed to a duration shorter than the wavelength of the light emitted by them. In this case the different electron contributions to the emitted field sum up in phase and the output intensity scales as the square of the number of electrons in the bunch. In this work the particular case of superradiant emission from an undulator in the THz frequency range is considered. An electron bunch at the entrance of a THz undulator setup has typically an energy chirp because of the necessity to compress it in magnetic chicanes. Then, the chirped electron bunch evolves passing through a highly dispersive THz undulator with a large magnetic field amplitude, and the shape of its longitudinal phase space changes. Here the impact of this evolution on the emission of superradiant THz radiation is studied, both by means of an analytical model and by simulations.

scholarly journals Investigation of Bunch Compressor and Compressed Electron Beam Characteristics by Coherent Transition Radiation

Particles ◽  
2018 ◽  
Vol 2 (1) ◽  
pp. 32-43
Author(s):  
Sikharin Suphakul ◽  
Heishun Zen ◽  
Toshiteru Kii ◽  
Hideaki Ohgaki
Keyword(s):  
Electron Bunch ◽  
Transition Radiation ◽  
Michelson Interferometer ◽  
Bunch Length ◽  
Thz Radiation ◽  
Compaction Factor ◽  
Rf Gun ◽  
Coherent Transition Radiation ◽  
Beam Characteristics ◽  
Injection Phase

A magnetic chicane bunch compressor for a new compact accelerator-based terahertz (THz) radiation source at the Institute of Advanced Energy, Kyoto University, was completely installed in March 2016. The chicane is employed to compress an electron bunch with an energy of 4.6 MeV generated by a 1.6-cell photocathode radio frequency (RF)-gun. The compressed bunch is injected into a short planar undulator for THz generation by coherent undulator radiation (CUR). The characteristics of the bunch compressor and the compressed bunch were investigated by observing the coherent transition radiation (CTR). The CTR spectra, which were analyzed by using a Michelson interferometer, and the compressed bunch length were also estimated. The results were that the chicane could compress the electron bunch at a laser injection phase less than 45 degrees, and the maximum CTR intensity was observed at a laser injection phase around 24 degrees. The optimum value of the first momentum compaction factor was around −45 mm, which provided an estimated rms bunch length less than 1 ps.

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