X-ray detection system for wavelength dispersive and energy dispersive spectroscopy and electron beam applications
First Claim
1. Apparatus for detecting X-rays incident thereon, comprising:
- an avalanche photodiode detector having a slab of semiconductor material with a first face on which incident X-rays impinge and a second face on the opposite side of the slab from the first face, a conductive entrance window electrode with a thickness less than ten nanometers covering the first face and a conductive collection electrode covering the second face; and
a voltage source that applies a reverse bias voltage across the entrance window electrode and the collection electrode.
1 Assignment
0 Petitions
Accused Products
Abstract
A detection system for wavelength-dispersive and energy-dispersive spectrometry comprises an X-ray detector formed from a solid-state avalanche photodiode with a thin entrance window electrode that permits the efficient detection of X-rays scattered from “light” elements. The detector can be tilted relative to the incident X-rays in order to increase the detection efficiency for X-rays scattered from “heavy” elements. The entrance window may be continuous conductive layer with a thickness in the range of 5 to 10 nanometers or may be a pattern of conductive lines with “windowless” areas between the lines. A signal processing circuit for the avalanche photodiode detector includes an ultra-low noise amplifier, a dual channel discriminator, a scaler and a digital counter. A linear array of avalanche photodiode detectors is used to increase the count rate of the detection system.
29 Citations
25 Claims
-
1. Apparatus for detecting X-rays incident thereon, comprising:
-
an avalanche photodiode detector having a slab of semiconductor material with a first face on which incident X-rays impinge and a second face on the opposite side of the slab from the first face, a conductive entrance window electrode with a thickness less than ten nanometers covering the first face and a conductive collection electrode covering the second face; and a voltage source that applies a reverse bias voltage across the entrance window electrode and the collection electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. Apparatus for detecting X-rays incident thereon, comprising:
-
an avalanche photodiode detector having a slab of semiconductor material with a first face on which incident X-rays impinge and a second face on the opposite side of the slab from the first face, a conductive entrance window electrode with a thickness less than ten nanometers covering the first face and a conductive collection electrode covering the second face; a voltage source that applies a reverse bias voltage across the entrance window electrode and the collection electrode; a mechanism that tilts the detector so that the entrance window electrode is at an angle relative to the incident X-rays in order to increase a detection efficiency for X-rays scattered from “
heavy”
elements; anda signal processing circuit connected to the avalanche photodiode detector including an ultra-low noise amplifier, a dual channel discriminator, a scaler and a digital counter. - View Dependent Claims (11, 12, 13, 14)
-
-
15. A wavelength-dispersive spectrometer for measuring X-rays generated when an electron beam strikes a sample, the spectrometer comprising:
-
an X-ray detector; a crystal; and a spectrometer mechanism that positions the crystal relative to the generated X-rays so that X-rays with a selected wavelength are incident on the X-ray detector, wherein the X-ray detector is an avalanche photodiode detector having a slab of semiconductor material with a first face on which incident X-rays impinge and a second face on the opposite side of the slab from the first face, a conductive entrance window electrode with a thickness less than ten nanometers covering the first face and a conductive collection electrode covering the second face. - View Dependent Claims (16, 17, 18, 19)
-
-
20. An energy-dispersive spectrometer for measuring X-rays generated when an electron beam strikes a sample, the spectrometer comprising:
-
an avalanche photodiode detector having a slab of semiconductor material with a first face on which incident X-rays impinge and a second face on the opposite side of the slab from the first face, a conductive entrance window electrode with a thickness less than ten nanometers covering the first face and a conductive collection electrode covering the second face; and a counter circuit for processing a signal generated by the detector to generate an X-ray spectrum. - View Dependent Claims (21, 22, 23, 24, 25)
-
Specification