Method and apparatus for transmission of fluorescence X-ray radiation using a multilayer X-ray target
The present invention pertains to a method and apparatus for generating a beam of charged particles, accelerating the charged particles toward a first side of a layer of X-ray target material configured to emit Bremsstrahlung radiation through a second side, receiving the Bremsstrahlung radiation on a first face of an additional layer of a different X-ray target material configured to emit characteristic fluorescence X-rays with energy above 20 keV through a second face, wherein the additional layer of X-ray target material is located within 3 mm of the second side of the first layer of material. The first X-ray target material can have an atomic number greater than 21.
1. An X-ray source comprising:
a particle gun configured to emit a beam of charged particles along a predetermined path;
a first target layer of a first material positioned in said path, wherein said first material has an atomic number greater than 21;
a second target layer of a second material positioned within 3 mm from said first target layer on opposite side of said first target layer than said path,
wherein said second material has at least one characteristic X-ray fluorescence energy above 20 keV; and
an X-ray collimator configured for selective transmission of X-rays emitted by said second target layer at a predetermined non-zero angle from an axis of travel of said beam.
2. The X-ray source of claim 1 wherein said second material is uranium.
3. The X-ray source of claim 1 wherein said predetermined non-zero angle is greater than 50 degrees.
4. The X-ray source of claim 1 wherein said predetermined non-zero angle is between 65 degrees and 87 degrees, inclusive.
5. The X-ray source of claim 1 wherein said first target layer and said second target layer are in contact with one another.
6. An X-ray source comprising:
a particle gun configured to emit a beam of charged particles along a predetermined path;
a first target layer of a first material positioned in said path, wherein said first material has an atomic number greater than 21;
a second target layer of a second material positioned within 3 mm from said first target layer on opposite side of said first target layer than said path,
wherein said second material has at least one characteristic X-ray fluorescence energy above 20 keV; and
a layer of a thermally conductive material between said first target layer and said second target layer.
7. The X-ray source of claim 6 wherein said thermally conductive material is a cooling fluid.
8. The X-ray source of claim 6 wherein said characteristic X-ray fluorescence energy is above 80 keV.
9. An X-ray transmission target comprising:
a first layer of a first material configured to receive a beam of charged particles on a first side and emit Bremsstrahlung radiation in response to said beam from a second side; and
a second layer of a second material positioned within 3 mm of said second side configured to receive said Bremsstrahlung radiation on a first face and emit X-ray fluorescence radiation in response to said Bremsstrahlung radiation from a second face, wherein said second face is non-parallel to said first face.
10. The transmission target of claim 9 wherein said second material is uranium.
11. The transmission target of claim 9 wherein said second material is bismuth.
12. The transmission target of claim 9 wherein said first material is tungsten.
13. The transmission target of claim 9 wherein said first material is molybdenum.
14. The transmission target of claim 9 wherein thickness of said second layer is between 100 μm and 500 μm.
15. The transmission target of claim 9 wherein thickness of said first target layer is between 1 μm and 50 μm.
16. The transmission target of claim 9 wherein thickness of said first target layer is between 200 μm and 800 μm.
17. A method for generating an X-ray beam comprising:
generating a beam of charged particles;
accelerating said charged particles toward a first side of a first layer of a first material;
emitting Bremsstrahlung radiation from a second side of said first layer;
receiving said Bremsstrahlung radiation on a first face of a second layer of a second material, wherein said first face is located within 3 mm of said second side;
emitting fluorescent X-rays from a second face of said second layer; and
selectively transmitting said fluorescent X-rays emitted at angles greater than 50 degrees from an axis of travel of said beam of charged particles through an X-ray collimator.