Point-Source Gamma Ray Standards

Radiology ◽  
1960 ◽  
Vol 74 (1) ◽  
pp. 120-121
Keyword(s):  
Point Source ◽  
Gamma Ray

scholarly journals Determination of Gamma-ray Efficiency Curves for Volume Samples by the Combination of Monte Carlo Simulations and Point Source Calibration

2000 ◽  
Vol 37 (12) ◽  
pp. 1075-1081 ◽  
Author(s):  
Jun SAEGUSA ◽  
Tetsuya OISHI ◽  
Katsuya KAWASAKI ◽  
Michio YOSHIZAWA ◽  
Makoto YOSHIDA ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Point Source ◽  
Monte Carlo Simulations ◽  
Gamma Ray

scholarly journals Searching for Gamma-Ray Millisecond Pulsars: Selection of Candidates Revisited

Galaxies ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 31
Author(s):  
Xuejie Dai ◽  
Zhongxiang Wang ◽  
Jithesh Vadakkumthani
Keyword(s):  
Point Source ◽  
Gamma Ray ◽  
Previous Analysis ◽  
Test Statistic ◽  
Large Area ◽  
Millisecond Pulsars ◽  
Multi Wavelength ◽  
Γ Ray ◽  
Available Information ◽  
Selection Of

We are starting a project to find γ -ray millisecond pulsars (MSPs) among the unidentified sources detected by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope (Fermi), by radio observations. The selection of good candidates from analysis of the LAT data is an important part of the project. Given that there is more than 10 years worth of LAT data and the advent of the newly released LAT 8-year point source list (FL8Y), we have conducted a selection analysis, on the basis of our previous analysis, and report the results here. Setting the requirements for the unidentified sources in FL8Y of Galactic latitudes | b | > 5 ∘ and curvature significances >3 σ , there are 202 sources with detection signficances >6 σ . We select 57 relatively bright ones (detection significances >15 σ ) and analyze their 10.2 years of LAT data. Their variability is checked to exclude variable sources (likely blazars), test statistic maps are constructed to avoid contaminated sources, and curvature significances are re-obtained and compared to their γ -ray spectra to exclude non-significant sources. In the end, 48 candidates are found. Based on the available information, mostly from multi-wavelength studies, we discuss the possible nature of several of the candidates. Most of these candidates are currently being observed with the 65-meter Shanghai Tian Ma Radio Telescope.

scholarly journals Millisecond Pulsars in the Galactic Bulge? An Extended Discussion on the Wavelet Analysis of the Fermi-LAT data

2016 ◽  
Vol 11 (S322) ◽  
pp. 193-196
Author(s):  
Richard Bartels ◽  
Christoph Weniger
Keyword(s):  
Dark Matter ◽  
Spectral Analysis ◽  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Point Source ◽  
Gamma Ray ◽  
Detection Threshold ◽  
Supportive Evidence ◽  
Millisecond Pulsars ◽  
Extended Discussion

AbstractA clear excess in the Fermi-LAT data is present at energies around a few GeV. The spectrum of this so-called ’GeV excess’ is remarkably similar to the expected annihilation signal of WIMP dark matter. However, a large bulge population of millisecond pulsars living below the Fermi–LAT detection threshold could also explain the excess spectrum. In a recent work we optimized the search for sub-threshold sources, by applying a wavelet transform to the Fermi–LAT gamma-ray data. In the Inner-Galaxy the wavelet signal is significantly enhanced, providing supportive evidence for the point source interpretation of the excess. In these proceedings we will extent our previous work with a spectral analysis and elaborate on the potential contamination from substructures in the gas.

Guaranteed Unresolved Point Source Emission and the Gamma-ray Background

2007 ◽  
Author(s):  
Vasiliki Pavlidou ◽  
Jennifer M. Siegal-Gaskins ◽  
Brian D. Fields ◽  
Angela V. Olinto ◽  
Carolyn Brown
Keyword(s):  
Point Source ◽  
Gamma Ray ◽  
Source Emission

scholarly journals Improved Gamma-Ray Point Source Quantification in Three Dimensions by Modeling Attenuation in the Scene

2021 ◽  
pp. 1-1 ◽  
Author(s):  
M. S. Bandstra ◽  
D. Hellfeld ◽  
J. R. Vavrek ◽  
B. J. Quiter ◽  
K. Meehan ◽  
...  
Keyword(s):  
Point Source ◽  
Gamma Ray ◽  
Three Dimensions

Point Source Technique for Gamma Ray Absorption Studies.

1962 ◽  
Vol 34 (4) ◽  
pp. 585-586 ◽  
Author(s):  
Joseph Bubernak ◽  
M. S. Lew ◽  
G. M. Matlack
Keyword(s):  
Point Source ◽  
Gamma Ray ◽  
Absorption Studies

URANIUM MEASUREMENT BY AIRBORNE GAMMA‐RAY SPECTROMETRY

Geophysics ◽  
1975 ◽  
Vol 40 (3) ◽  
pp. 503-519 ◽  
Author(s):  
R. L. Grasty
Keyword(s):  
Point Source ◽  
Gamma Ray ◽  
Radioactive Decay ◽  
High Energy ◽  
Gamma Ray Spectrometry ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Airborne Measurement ◽  
Decay Series ◽  
Different Depths

In the airborne measurement of uranium, window type gamma‐ray spectrometers are used and it is necessary to correct for scattered high energy radiation from thallium 208 in the thorium decay series. This radiation can be scattered in the crystal, in the ground, and in the air. A theory, analogous to the theory of radioactive decay, is developed; it can adequately explain the spectrum buildup in the uranium window for a point source of thorium oxide immersed to different depths in water and for a detector above the water. The theory is extended to predict the buildup as a function of altitude for detectors of different sizes and shows that errors in the airborne measurement of uranium can be, significant if no allowance is made for radiation scattered in the ground and in the air.

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