X-ray analyzing apparatus

Patent metadata

Field	Value
Publication number	US-9778214-B2
Application number	US-201715458326-A
Country	US
Kind code	B2
Filing date	Mar 14, 2017
Priority date	Sep 18, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

The X-ray analyzing apparatus according to the present invention includes, in combination: a first correcting unit ( 13 A, 13 B) to output a first gain to cause a pulse height of a target peak which is estimated on the basis of a sum of counting rates obtained in preliminary measurement, to match a predetermined expected pulse height; and a second correcting unit ( 14 A, 14 B) to output, in real time through feedback control, a second gain to be added to the first gain in order to cause the pulse height of the target peak detected within a predetermined energy range, to match the expected pulse height, and further includes a feedback control stopping unit ( 16 A, 16 B) to appropriately determine presence/absence of an interfering line with respect to the target peak, and to set, when determining that the interfering line exists, the gain to a fixed value including only the first gain.

First claim

What is claimed is:

1. An X-ray analyzing apparatus comprising:
a detector configured to generate a number of pulses having pulse heights corresponding to energy of incident X-rays, the number corresponding to intensity of the X-rays;
a high-speed AD converter configured to digitalize the pulses generated by the detector;
a pulse height stabilizer configured to stabilize, for pulses inputted from the high-speed AD converter, a pulse height of a target peak which is a peak in an X-ray energy spectrum to be analyzed; and
a counting unit configured to obtain, for pulses from the pulse height stabilizer, a counting rate within a set pulse height range, wherein
the pulse height stabilizer includes
an input pulse multiplier configured to multiply the pulses inputted from the high-speed AD converter with an inputted gain, and to output the pulses,
a first correcting unit configured to, in preliminary measurement before main measurement, obtain, for pulses from the input pulse multiplier, a sum of counting rates, to estimate the pulse height of the target peak on the basis of the obtained sum of counting rates, and to output a first gain which is a gain to cause the estimated pulse height of the target peak to match a predetermined expected pulse height,
a second correcting unit configured to detect the pulse height of the target peak within a predetermined energy range including the expected pulse height on the basis of the pulses from the input pulse multiplier, and to output, in real time through feedback control, a second gain which is a gain to be added to the first gain in order to cause the detected pulse height of the target peak to match the expected pulse height,
a gain adder configured to add the inputted first gain to the inputted second gain to obtain a gain, and to output the gain to the input pulse multiplier, and
a feedback control stopping unit configured to determine presence/absence of an interfering line with respect to the target peak, and, when determining that the interfering line exists, to stop the second correcting unit outputting the second gain, thereby to set the gain to be inputted to the input pulse multiplier, to a fixed value including only the first gain.

2. The X-ray analyzing apparatus as claimed in claim 1 , wherein
in the second correcting unit,
the predetermined energy range is a range from a low pulse height threshold which is lower than the expected pulse height by a half to two times of a half value width of the target peak, to a first high pulse height threshold which is higher than the expected pulse height, and the low pulse height threshold and the first high pulse height threshold are set such that, for the X-ray energy spectrum to be analyzed, a total counting rate within a range from the low pulse height threshold to the expected pulse height is equal to a total counting rate within a range from the expected pulse height to the first high pulse height threshold,
for the pulses from the input pulse multiplier, an average pulse height obtained by averaging, by an exponential smoothing method, pulse heights within the range from the low pulse height threshold to the first high pulse height threshold is detected as the pulse height of the target peak, and

in the feedback control stopping unit,
the low pulse height threshold and a second high pulse height threshold, which is equal to or greater than two times of the expected pulse height are set, and
in the preliminary measurement, for the pulses from the input pulse multiplier, when a difference between the pulse height of the target peak detected by the second correcting unit and an average pulse height obtained by averaging, by the exponential smoothing method, pulse heights within a range from the low pulse height threshold to the second high pulse height threshold is greater than a predetermined value, it is determined that the interfering line exists.

3. The X-ray analyzing apparatus as claimed in claim 1 , wherein
in the preliminary measurement, when a value obtained by adding the first gain to the second gain is outside a predetermined range, the feedback control stopping unit determines that the interfering line exists.

4. The X-ray analyzing apparatus as claimed in claim 1 , wherein, after a predetermined waiting time corresponding to the sum of counting rates obtained by the first correcting unit has elapsed since the feedback control stopping unit determines in the preliminary measurement that the interfering line exists, the feedback control stopping unit sets a gain to be inputted to the input pulse multiplier, to the fixed value including only the first gain, and the main measurement is started.

Assignees

• Rigaku Denki Co Ltd

Inventors

• Sako Yukio

Classifications

• G01N2223/303

  calibrating, standardising · CPC title

• G01N23/223 Primary

  by irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence · CPC title

• G01T1/17

  Circuit arrangements not adapted to a particular type of detector {(pulse-selection circuits H03K, G01R)} · CPC title

• G01N2223/076

  X-ray fluorescence · CPC title

• G01T1/40 Primary

  Stabilisation of spectrometers · CPC title