Multichannel models for the estimation of radon background in airborne gamma‐ray spectrometry

Geophysics ◽  
1998 ◽  
Vol 63 (6) ◽  
pp. 1986-1996 ◽  
Author(s):  
Brian R. S. Minty
Keyword(s):  
Gamma Ray ◽  
Weighted Least Squares ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Gamma Ray Spectrometry ◽  
Minimization Method ◽  
Full Spectrum ◽  
Spectrometric Data ◽  
Spectral Ratio Method ◽  
Atmospheric Radon

Adequate background correction is a crucial step in processing airborne gamma‐ray spectrometric data because any errors are amplified during subsequent processing procedures. Two multichannel models for the estimation of atmospheric radon background are proposed. The spectral‐ratio method uses the relative heights of uranium (U) series photopeaks to estimate the contribution of atmospheric radon to observed spectra. The full‐spectrum method estimates the atmospheric radon contribution through the weighted least‐squares fitting of potassium (K), U, thorium (Th), and radon component spectra to the observed spectra. Both the spectral‐ratio and full‐spectrum methods are adequately calibrated through the estimation of component spectra from calibration experiments on the ground using radioactive calibration sources and wood to simulate the attenuation of gamma rays by air. The simulated heights used in these calibrations must be mapped onto real heights through calibration flights over an airborne calibration range. The spectral‐ratio method is also adequately calibrated using a heuristic calibration procedure. An iterative minimization method is used to find the optimum values of the calibration constants such that the radon background over suitable calibration lines is best removed.

scholarly journals Event couple spectral ratio Q method for earthquake clusters: application to North-West Bohemia

2018 ◽  
Author(s):  
Marius Kriegerowski ◽  
Simone Cesca ◽  
Matthias Ohrnberger ◽  
Torsten Dahm ◽  
Frank Krüger
Keyword(s):  
Wave Attenuation ◽  
Attenuation Factor ◽  
Source Region ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Earthquake Swarms ◽  
North West ◽  
High Attenuation ◽  
West Bohemia ◽  
Spectral Ratio Method

Abstract. We develop an amplitude spectral ratio method for event couples from clustered earthquakes to estimate seismic wave attenuation (Q−1) in the source volume. The method allows to study attenuation within the source region of earthquake swarms or aftershocks at depth, independent of wave path and attenuation between source region and surface station. We exploit the high frequency slope of phase spectra using multitaper spectral estimates. The method is tested using simulated full wavefield seismograms affected by recorded noise and finite source rupture. The synthetic tests verify the approach and show that solutions are independent of focal mechanisms, but also show that seismic noise may broaden the scatter of results. We apply the event couple spectral ratio method to North-West Bohemia, Czech Republic, a region characterized by the persistent occurrence of earthquake swarms in a confined source region at mid-crustal depth. Our method indicates a strong anomaly of high attenuation in the source region of the swarm with an averaged attenuation factor of Qp 

Advanced Spectral-Ratio Radon Background Estimate in Airborne Gamma-Ray Spectrometry and Calibration Technology

2020 ◽  
Vol 76 (5) ◽  
pp. 392-400
Author(s):  
Yi Gu ◽  
Heng Lu ◽  
Meng Wang ◽  
Liangquan Ge ◽  
Qingxian Zhang
Keyword(s):  
Gamma Ray ◽  
Spectral Ratio ◽  
Gamma Ray Spectrometry

Airborne gamma‐ray spectrometric background estimation using full spectrum analysis

Geophysics ◽  
1992 ◽  
Vol 57 (2) ◽  
pp. 279-287 ◽  
Author(s):  
B. R. S. Minty
Keyword(s):  
Gamma Ray ◽  
Atmospheric Radiation ◽  
Compton Continuum ◽  
Full Spectrum ◽  
Background Estimation ◽  
Potassium Sources ◽  
Energy Formula ◽  
A New Technique ◽  
The Vertical Distribution ◽  
Atmospheric Radon

We have developed a new technique for estimating airborne gamma‐ray spectrometric backgrounds. The background comes from three sources, namely aircraft, cosmic and atmospheric (radon) radiation. The aircraft and cosmic components are independently estimated by suitable calibration and the monitoring of a 3–6 MeV “cosmic” channel. Multichannel observations of the spectra are used to estimate the atmospheric background directly based on the observation that for gamma‐ray counts above the Compton continuum, the low energy [Formula: see text] photopeak at 0.609 MeV for atmospheric radiation suffers far less attenuation relative to the [Formula: see text] peak at 1.76 MeV than is the case for radiation from uranium in the ground. Since thorium and potassium sources do not contribute appreciably to these peak countrates, they can be used to calculate the contributions of radon and uranium to the observed spectrum. The technique appears to be less susceptible to errors due to the effects of variations in the vertical distribution of airborne radon and its daughters than upward‐looking detector techniques.

Measuring the sediment thickness in urban areas using revised H/V spectral ratio method

2019 ◽  
Vol 260 ◽  
pp. 105223 ◽  
Author(s):  
Baoqing Tian ◽  
Yanan Du ◽  
Zhiwei You ◽  
Ruohan Zhang
Keyword(s):  
Urban Areas ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Sediment Thickness ◽  
Spectral Ratio Method

Damping-ratio measurements by the spectral-ratio method

2006 ◽  
Vol 43 (11) ◽  
pp. 1180-1194 ◽  
Author(s):  
Yu-Hsing Wang ◽  
Wai Man Yan ◽  
Kai Fung Lo
Keyword(s):  
Damping Ratio ◽  
Near Field ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Bender Elements ◽  
True Triaxial ◽  
Triaxial Apparatus ◽  
True Triaxial Apparatus ◽  
Spectral Ratio Method ◽  
Near Field Effect

In this paper, bender elements are used as sensors to measure the damping ratio of soil by the spectral-ratio method. The results of numerical and physical experiments suggest that adequate measurement precision can be achieved by reducing the two types of inherent biases arising from (i) the near-field effect and (ii) the different transfer functions of the two receiver bender elements. The first bias can be avoided by setting sensors to r1/λ ≥ 2.0 and r1/r2 ≥ 2.0, where r1 and r2 are the distances between the source and the first and second receivers, respectively; and λ is the wavelength. The second bias can be minimized by modifying the original spectral-ratio method to accommodate the self-healing technique. The damping ratios, measured by this modified method, obtained from the experiment conducted in a tailor-made, true-triaxial apparatus are very similar to those obtained from resonant column tests under the same state of stress.Key words: bender element, damping ratio, spectral-ratio method, near-field effect, true-triaxial apparatus.

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