For a given area, the values of Ke and Ic will be constant along with Re.
determined once the ambient gamma spectrum is known.
Data from the manufacturer
indicates an error of as much as 6 to 10% could result if energy corrections are
me Oe
The value of Kj can be
not made to the gross readings.
ae
Since we measure Rt, the only unknown are Kj and Ij.
The RSS-1l1ls
used in this study were calibrated at the factory using radium
sources whose calibration is traceable to the National Bureau of Standards.
Cali-
bration of the instruments were also checked by EML (formerly HASL) prior to field
use.
Energy Dependence Corrections
In the 1977 surveys, BNL used a sodium iodide detector, whose output was
coupled to-a multichannel analyzer.
The purposewas to enable the BNL team to
acquire spectra of the terrestrial background radiation at one meter above the
surface,
This was done at the same height and in the same areas where the RSS-111
measurements were taken.
Consequently, energy dependence factors could be cal-
culated by examining the environmental gamma scan for the energies of those nuclides
most predominant in the terrestrial environment.
The equipment used to accomplish this part of the work was a computing Gamma
Spectrometer, Model LEA 74-008 #11 built by Lawrence Livermore Laboratory (2).
The system uses a Harshaw 5.08 cm diameter x 5.08 cm thick NaI(T1l) scintillation
detector.
The spectrometer can be operated from AC power or on internal batteries.
Spectra are visually displayed on a CRT, and transferred to magnetic tape for
storage.
Using the math package with the system, each spectrum was examined in
100 KeV increments, and folded into the RSS-111 energy response
curve to determine
the energy dependence factors.
The range of factors needed to compensate the RSS-111 response due to energy
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