System for determining a compositon of radionuclides

• US 5,744,804 A
• Filed: 12/02/1996
• Issued: 04/28/1998
• Est. Priority Date: 04/05/1994
• Status: Expired due to Term

• Current Assignee: Medusa Explorations BV
• Original Assignee: Rijksuniversiteit Groningen
• Inventors: Meijer, Robert Johan, Stapel, Cornelis
• Primary Examiner(s): WONG, DON KITSUN
• Application Number:
  US08/722,264
• Time in Patent Office: 512 Days
• Field of Search: 250/256, 250/262, 250/369, 250/370.01, 378/45, 378/83
• US Class Current: 250/369
• CPC Class Codes: G01V 5/06 for detecting naturally radioactive minerals

Abstract

The system relates to a system for determining a composition of radionuclides in, for instance, a mineral-containing material by detecting gamma and/or X-ray radiation emitted by the nuclides. To that end, the system comprises a detector unit (2,6, 10) which supplies an electrical signal containing information about the intensity and energy of the emitted radiation and a signal processing system by which these electrical signals are further processed for determining the composition mentioned. According to the invention, the signal processing system further comprises an A/D converter (14) to which the electrical signals are applied and a first computer unit (26) which further processes signals supplied by the A/D converter for the purpose of determining the composition mentioned.

Claims

1. A system for determining a composition of a mineral-containing material by detecting gamma and/or x-ray radiation emitted by radionuclides in the material, comprising a detector unit which supplies an electrical signal containing information about the intensity and energy of the emitted radiation and a signal processing system by which these electrical signals are further processed for determining said composition of radionuclides, wherein the signal processing system comprises an A/D converter to which said electrical signals are applied and a first computer unit which further processes signals supplied by the A/D converter for the purpose of determining said composition of radionuclides;

the first computer unit composes an energy spectrum of the detected radiation from the signals supplied by the A/D converter; and

wherein the first computer unit determines the concentrations C(U), C(Th) and C(K) of the radionuclides uranium, thorium and potassium respectively according to the first algorithm and the relative masses m_j (_j =a, b, c or d) of respective mineral groups which are designated a, b, c and d according to the second algorithm said second algorithm m_j (_j =a, b, c or d) is determined from the equation;

space="preserve" listing-type="equation">C.sub.p m=C

wherein ##EQU3## and wherein every mineral group a, b, c or d is characterized by its three known concentrations C_j (U), C_j (Th) and C_j (K) with _j =a, b, c or d.

2. A system according to claim 1, characterized in that the detector unit comprises a scintillation detector and a photomultiplier which converts the light pulses supplied by the scintillation detector into an electrical pulse of an amplitude which is a measure for the energy of the radiation received by the scintillation detector.

3. A system according to claim 2, characterized in that the detector unit further comprises a pulse height analyzer for obtaining said electrical signals.

4. A system according to claim 2, characterized in that the scintillation detector comprises a BGO crystal.

5. A system according to claim 1, characterized in that the detector unit comprises a semiconductor crystal to which a bias voltage is applied and means for detecting a variation in the bias voltage for obtaining said electrical signals.

6. A system according to claim 1, characterized in that the first computer unit determines said concentrations on the basis of the complete determined spectrum.

7. A system according to claim 1, characterized in that the first computer unit determines said concentrations on the basis of predetermined energy ranges of the spectrum which correspond to spectra of individual radionuclides whose concentration is being determined.

8. A system according to claim 1, characterized in that the first computer unit comprises a memory in which energy spectra of radiation emitted by radionuclides are stored.

9. A system according to claim 8, characterized in that the spectra stored in the memory are used in the predetermined first algorithm.

10. A system according to claim 8, characterized in that data of minerals which are known per se and the corresponding concentrations of radionuclides in said minerals are stored in the memory of the first computer unit.

11. A system according to claim 10, characterized in that the second algorithm utilizes the information about said minerals which is stored in the memory.

12. A system according to claim 1, characterized in that the detector unit comprises sensors by which sound, temperature, magnetism and/or other physical phenomena in the environment of the radionuclides to be detected can be detected and converted into an electrical sensor signal.

13. A system according to claim 12, characterized in that the sensor signal is applied via the A/D converter to the first computer unit for the purpose of performing corrections in determining said compositions.

14. A system according to claim 13, characterized in that said corrections are performed through software.

15. A system according to claim 12, characterized in that the sensor signal is applied to a second computer unit for correcting and/or stabilizing the detector unit.

16. A system according to claim 15, characterized in that the second computer unit is also accommodated in said housing.

17. A system according to claim 1, characterized in that the system further comprises a transmitter unit to which output signals of the A/D converter are applied and a receiver unit which feeds received signals to the first computer unit.

18. A system according to claim 1, characterized in that the output signals of the A/D converter are fed to the first computer unit via a cable.

19. A system according to claim 1, characterized in that the detector unit and the A/D converter are accommodated in a probe-forming housing.

20. A system for determining a composition of mineral-containing material by detecting gamma and/or x-ray radiation emitted by radionuclides in the material, comprising a detector unit which supplies an electrical signal containing information about the intensity and energy of the emitted radiation and a signal processing system by which these electrical signals are further processed for determining said composition of radionuclides, wherein the signal processing system comprises an A/D converter to which said electrical signals are applied and a first computer unit with a memory for storing energy spectrum of radiation emitted by radionuclides and which further processes signals supplied by the A/D converter for the purpose of determining said composition of radionuclides;

the first computer unit composes an energy spectrum of the detected radiation from the signals supplied by the A/D converter; and

wherein the first computer unit determines the concentration of the radionuclides on the basis of the spectrum according to a prescribed first algorithm, wherein the first computer unit determines, according to a second algorithm, what amounts of predetermined groups of minerals are present in the material on the basis of the determined concentrations of the radionuclides in the material wherein each predetermined group of minerals comprises a group of minerals whose spectra are similar.

21. A system according to claim 20, wherein the first computer unit determines the concentrations C(U), C(Th) and C(K) of he radionuclides uranium, thorium and potassium, respectively, according to the first algorithm and that the first computer unit determines the relative masses m_j (_j =a, b, c or d) of respective mineral groups which are designated a, b, c and d according to the second algorithm.

22. A system according to claim 21, wherein, according to the second algorithm, m_j (_j =a, b, c or d) is determined from the equation:

space="preserve" listing-type="equation">C.sub.p m=C

wherein ##EQU4## and wherein every mineral group a, b, c or d is characterized by its three known concentrations C_j (U), C_j (Th) and C_j (K) with _j =a, b, c or d.

23. A system according to claim 20, wherein the detector unit comprises a scintillation detector and a photomultiplier which converts the light pulses supplied by the scintillation detector into an electrical pulse of an amplitude which is a measure for the energy of the radiation received by the scintillation detector.

24. A system according to claim 23, wherein the detector unit further comprises a pulse height analyzer for obtaining said electrical signals.

25. A system according to claim 20, wherein the detector unit comprises a semiconductor crystal to which a bias voltage is applied and means for detecting a variation in the bias voltage for obtaining said electrical signals.

26. A system according to claim 20, wherein the first computer unit determines said concentrations on the basis of the complete determined spectrum.

27. A system according to claim 20, wherein the first computer unit determines said concentrations on the basis of predetermined energy ranges of the spectrum which correspond to spectra of individual radionuclides whose concentration is being determined.

28. A system according to claim 27, wherein data of known minerals and the concentrations of radionuclides in said minerals are stored in the memory of the first computer unit.

29. A system according to claim 20, wherein the spectra stored in the memory are used in the predetermined first algorithm.