scholarly journals Gamma-gamma absorption in gamma-ray binaries

2021 ◽  
Author(s):  
Brian van Soelen ◽  
Drikus du Plooy
Keyword(s):  
2019 ◽  
Vol 15 (S356) ◽  
pp. 364-364
Author(s):  
Hassan Abdalla

AbstractAt energies approaching the Planck energy scale 1019GeV, several quantum-gravity theories predict that familiar concepts such as Lorentz (LIV) symmetry can be broken. Such extreme energies are currently unreachable by experiments on Earth, but for photons traveling over cosmological distances the accumulated deviations from the Lorentz symmetry may be measurable using the Cherenkov Telescope Array (CTA). To study the spectral hardening feature observed in some VHE gamma-ray blazars, we calculate the reduction of the EBL gamma-gamma opacity due to the existence of underdense regions along the line of sight to VHE -gamma ray sources and we compared with the possibility of a LIV signature. Considering the LIV effect, we found that the cosmic opacity for VHE-gamma rays with energy more than 10 TeV can be strongly reduced. I will further discuss the impact of LIV on the Compton scattering process, and how future CTA observations may open an exciting window on studies of the fundamental physics.


2020 ◽  
Author(s):  
Drikus du Ploy ◽  
Brian van Soelen

2010 ◽  
Vol 77 (5) ◽  
Author(s):  
J. J. Lawrie ◽  
F. J. Mostert ◽  
P. J. König ◽  
K. D. Werneyer

The use of the gamma-ray absorption technique as a tool in evaluating the quality of manufactured powder metal liners was investigated. With powder metal liners, it is not only of interest to know whether the liner conforms geometrically to the required specifications but it is also important to know whether there is radial symmetry in the density. Powder metal liners manufactured via compaction methods were subjected to a gamma absorption proof of principle experiment and it was concluded that the technique can serve as an effective quality control method in the manufacturing process of powder metal shaped charge liners.


1967 ◽  
Vol 31 ◽  
pp. 469-471
Author(s):  
J. G. Duthie ◽  
M. P. Savedoff ◽  
R. Cobb
Keyword(s):  

A source of gamma rays has been found at right ascension 20h15m, declination +35°, with an uncertainty of 6° in each coordinate. Its flux is (1·5 ± 0·8) x 10-4photons cm-2sec-1at 100 MeV. Possible identifications are reviewed, but no conclusion is reached. The mechanism producing the radiation is also uncertain.


1994 ◽  
Vol 144 ◽  
pp. 635-639
Author(s):  
J. Baláž ◽  
A. V. Dmitriev ◽  
M. A. Kovalevskaya ◽  
K. Kudela ◽  
S. N. Kuznetsov ◽  
...  

AbstractThe experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.


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