Regularity Analysis of Airborne Natural Gamma Ray Data Measured in the Hoggar Area (Algeria) - Advances in Data, Methods, Models and Their Applications in Geoscience - page 96

TC TC BC
KK

 

corr obs TC

  C

corr obs K

(1)

UU   C

corr obs U

Th  Th  BC

corr obs Th

where all these values are expressed in counts per second (cps).
TC corr , K corr , U corr and Th corr : Values of the corrected count rates in the four channels,
TC obs , K obs , U obs and Th obs : Values of the observed count rates in the four channels,
BC TC , BC K , BC U and BC Th : Values of the background correction in the four channels. In this
case, the estimated values are (Groune, 2009): BC TC = 250 cps, BC K = 72 cps, BC U = 17 cps and
BC Th = 5 cps.
Stripping correction
This correction, also known as the channel interaction correction, consists of removing
('strips') count rates from each of the K, U and Th for gamma rays not originating from the
radioelement or decay series being monitored. For example, Th series gamma rays appear in
both the U and K channels, and U series gamma rays appear in the K channel. The
corrections are given by:

UU   h

corr obs obs

(2)

KK   h   U

corr obs obs obs

K corr and U corr : Values of the corrected count rates in the K and U channels respectively.
K obs , U obs and Th obs : Values of the observed count rates in the K, U and Th channels
respectively.
and   : Stripping coefficients. The used coefficients in this application are (Aeroservice,

1975):  0 45 . ,  059 . and   094 . .

Height correction
This correction is applied only on airborne gamma spectrometric measurements. The
gamma radiation decreases exponentially with the elevation. Since the height of the aircraft
changes continuously, the airborne Gamma Ray spectrometric data need to be corrected to a
nominal survey height above the ground.

 

TC  TC exp

exp

  h  h 

 

corr obs TC 0

 

KK    h  h 

  corr obs K 0

(3)

 

UU  exp

exp

  h  h 

 

corr obs U 0

 

Th  Th   h  h 

 

corr obs Th 0

TC corr , K corr , U corr and Th corr : Values of the corrected count rates in the four channels,
TC obs , K obs , U obs and Th obs : Values of the observed count rates in the four channels,
h : Real survey height ,
h 0 : Nominal survey height ( h 0 =150 m),
μ TC , μ K , μ U and μ Th : Linear attenuation coefficients in the four channels. The estimated
values of these coefficients are (Groune, 2009) : μ K = 6.8617 10 -3 m -1 , μ U = 6.3726 10 -3 m -1 , and
μ Th = 5.2247 10 -3 m -1 . The μ TC is calculated as the approximate average of the three
coefficients: μ TC = 6.56 10 -3 m -1 .