Measurement arrangement for X-ray fluoresence analysis
A portable measurement apparatus is presented for inducing and measuring fluorescent X-ray radiation. It comprises an X-ray source ( 303, 902, 1005, 1105 ) adapted to controllably irradiate a sample ( 301, 803 ) with X-rays, and a detector ( 305, 406, 1006, 1106 ) adapted to detect fluorescent radiation emitted by said sample ( 301, 803 ). The X-ray source ( 303, 902, 1005, 1105 ) is an X-ray tube, an anode of which comprises at least one of silver, rhodium and molybdenium. Consequently said X-ray tube is adapted to controllably emit L-line radiation of at least one of silver, rhodium and molybdenium.
1. A measurement apparatus for inducing and measuring X-ray radiation, comprising:
an X-ray tube adapted to controllably irradiate a sample with X-rays,
a detector adapted to detect radiation from said sample,
a measurement head defining a sample receiving surface,
next to said sample receiving surface, support structures defining a space for a removable separate enclosure, and
a gas-filled separate enclosure removably fitted into said measurement head between the detector and said sample receiving surface,
wherein the measurement apparatus is a portable measurement apparatus adapted to induce and measure fluorescent X-ray radiation, and wherein said X-ray tube comprises an anode which comprises at least one of silver, rhodium and molybdenum, and wherein said X-ray tube is adapted to controllably emit L-line radiation of at least one of silver, rhodium and molybdenum.
2. A measurement apparatus according to claim 1 , wherein:
the X-ray tube is of an end window type,
an end window of said X-ray tube is made of beryllium, has a thickness between 50 and 200 micrometers and comprises an anode layer of a thickness between 0.5 and 2 micrometers, and
said anode layer comprises at least one of silver, rhodium and molybdenum.
3. A measurement apparatus according to claim 1 , wherein the X-ray tube is of a side window type.
4. A measurement apparatus according to claim 1 , comprising a collimator adapted to collimate X-rays emitted by the X-ray tube in the direction of the sample.
5. A measurement apparatus according to claim 1 , comprising:
a measurement head adapted to define a sample receiving surface, and
a gas-filled separate enclosure between the detector and said sample receiving surface, said separate enclosure being limited by a sample side window at said sample receiving surface and a detector side window next to the detector, which sample side window and detector side window are permeable to X-rays.
6. A measurement apparatus according to claim 1 , wherein:
said separate enclosure is limited by a sample side window at a side that coincides with said sample receiving surface when said separate enclosure is within said measurement head,
said separate enclosure is limited by a detector side window at a side that is next to the detector when said separate enclosure is within said measurement head; and
said sample side window and detector side window are permeable to X-rays.
7. A measurement apparatus according to claim 6 , wherein:
said sample side window is made of beryllium of a thickness between 8 and 25 micrometers; or polyimide or polycarbonate of a thickness between 0.3 and 5 micrometers; and
said detector side window is made of beryllium of a thickness between 8 and 25 micrometers.
8. A measurement apparatus according to claim 6 , wherein said separate enclosure is additionally limited by an exciting radiation input window at a side that is towards the X-ray source, when said separate enclosure is within said measurement head.
9. A measurement apparatus according to claim 8 , wherein said exciting radiation input window is a collimator side window at a side that is next to a collimator when said separate enclosure is within said measurement head.
10. A measurement apparatus according to claim 8 , wherein said exciting radiation input window is made of beryllium of a thickness between 8 and 50 micrometers.
11. A measurement apparatus according to claim 6 , wherein said separate enclosure contains gas having a pressure that is higher than ambient pressure around said measurement head.
12. A measurement apparatus according to claim 11 , wherein said separate enclosure comprises a filling valve for enabling controlling the pressure of said gas.
13. A measurement apparatus according to claim 1 , wherein the portable measurement apparatus also comprises a sample cap for holding volatile liquid as a sample, which sample cup has a window at a bottom of said sample cup, which window is adapted to be supported by a part of said separate enclosure when said sample cup is placed on top of a measurement head having said separate enclosure installed therein.
14. A measurement apparatus according to claim 1 , comprising a protective window adapted to cover an opening in said sample receiving surface, when said measurement head does not have said separate enclosure installed therein.
15. A measurement apparatus according to claim 1 , wherein:
the measurement apparatus comprises a measurement head adapted to define a sample receiving surface;
a direction of exciting X-rays passing between the X-ray source and a sample placed against said sample receiving surface is at an oblique angle against said sample receiving surface, and
a direction of fluorescent X-rays passing between a sample placed against said sample receiving surface and the detector is at an oblique angle against said sample receiving surface.
16. A measurement apparatus according to claim 1 , wherein:
the measurement apparatus comprises a measurement head adapted to define a sample receiving surface,
a direction of exciting X-rays passing between the X-ray source and a sample placed against said sample receiving surface is at an oblique angle against said sample receiving surface, and
a direction of fluorescent X-rays passing between a sample placed against said sample receiving surface and the detector is at a right angle against said sample receiving surface.
17. A measurement apparatus according to claim 1 , wherein the detector is a detector adapted to detect fluorescent radiation of at least one of aluminum, chlorine, magnesium, silicon, and sulphur.
18. An interface cassette for setting up an interface between parts in an X-ray fluorescence measurement apparatus, comprising:
a body part, which defines a cavity therein and an outside form for removably attaching the interface cassette to the X-ray fluorescence measurement apparatus,
a sample side window between said cavity and the outside of the interface cassette and
a detector side window between said cavity and the outside of the interface cassette, wherein said sample side window and said detector side window are permeable to X-rays.
19. An interface cassette according to claim 18 , wherein:
said sample side window is made of berrylium of a thickness between 8 and 25 micrometers; or polyimide or polycarbonate of a thickness between 0.3 and 5 micrometers; and
said detector side window is made of beryllium of a thickness between 8 and 25 micrometers.
20. An interface cassette according to claim 18 , comprising an exciting radiation input window at a side that is towards an X-ray source, when said interface cassette is within a measurement head of the X-ray fluorescence measurement apparatus.
21. An interface cassette according to claim 18 , wherein said exciting radiation input window is made of berrylium of a thickness between 8 and 50 micrometers.
22. An interface cassette according to claim 18 , wherein the interface cassette contains gas in said cavity, said gas having a pressure that is higher than ambient pressure around said interface cassette.
23. An interface cassette according to claim 22 , comprising a filling valve to control the pressure of said gas.