Investigation of the natural radioactivity of volcanic rock samples using a low background gamma-ray spectrometer

R. Wordel, D. Mouchel, V. A. Solé, J. Hoogewerff, J. Hertogen

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6 Citations (Scopus)


A low-level high-purity Ge detection system was used to investigate samples of volcanic rock from different locations. A lead shield surrounded the 100 cm3 germanium crystal and reduced the background radioactivity by a factor of 100 within the energy interval 70 to 3000 keV; an integrated count rate of (0.498 ± 0.001) s-1 was achieved over this inverval, which was mainly attributable to the influence of cosmic rays. Although sample volumes up to 2 litres can be measured, the volcanic samples were held in cylindrical containers and varied in volume from 16 to 20 cm3. A powdered solid source was prepared of similar chemical composition to the samples, and spiked with suitable radionuclides to calibrate the detector system. The resulting efficiency calibration was compared with a Monte Carlo simulation of the detector efficiency for extended sources. Corrections were made for the given geometry, self-absorption and absorption in calculating the full energy-peak efficiency (ε{lunate}γ). The concentrations of various radionuclides originating from the natural decay chains in the different samples were compared to a well known reference sample. A wide variation of the concentrations of the measured radionuclides and a breaking of secular equilibrium was observed.

Original languageEnglish
Pages (from-to)322-328
Number of pages7
JournalNuclear Inst. and Methods in Physics Research, A
Issue number1-2
Publication statusPublished - 22 Jan 1994
Externally publishedYes


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