US 6,295,508 B1 · Automatic pole-zero adjustment circuit for an ionizing radiation spectroscopy system and method

An automatic pole-zero adjustment circuit for an ionizing radiation spectroscopy system, said automatic pole-zero adjustment circuit comprising:

a high pass filter responsive to random analog pulses producing an output;
an analog-to-digital converter in electrical communication with said high pass filter, said analog-to-digital converter converting said high pass filter output to digital pulses;
a digital shaping filter in electrical communication with said analog-to-digital converter;
an amplitude histogram circuit in electrical communication with said digital shaping filter, said amplitude histogram circuit sorting and counting said digital pulses by amplitude and producing a histogram of the number of said digital pulses charted against the voltage of said digital pulses, said amplitude histogram containing at least one peak;
a processing device in electrical communication with said amplitude histogram circuit, said processing device for selecting one of said at least one peak from said amplitude histogram as a selected peak and measuring the shape of said selected peak;
a control circuit in electrical communication with said processing device for generating a control signal calculated to minimize distortion in said selected peak shape;
and
a pole-zero adjustment network in electrical communication with said control circuit and said high pass filter, said pole-zero adjustment network generating an analog control signal corresponding to said control signal and applying said analog control signal to said high pass filter output.

5 more elements

A method of automatically adjusting a pole-zero adjustment circuit of an ionizing radiation spectroscopy system to achieve a peak shape having a minimum distortion, said method comprising the steps of:

(a) detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation;
(b) processing said random sequence of analog pulses by passing said random sequence of analog pulses through a preamplifier and producing a sequence of preamplified analog pulses having a characteristic decay time constant;
(c) processing said sequence of preamplified analog pulses through a high pass filter incorporating a pole-zero cancellation network to produce a sequence of filtered pulses;
(d) digitizing said sequence of filtered pulses to produce a sequence of digitized pulses;
(e) histogramming said sequence of digitized pulses to produce a spectrum characteristic of said radiation source;
(f) selecting at least one peak from said spectrum suitable for determining the accuracy of an adjustment made by said pole-zero adjustment network;
(g) measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion, said step of measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion including the step of:
(1) measuring a width at at least one predetermined fraction of a full height of said at least one peak and calculating said correction;
wherein when each said width at at least one predetermined fraction of a full height is minimized it is determined that said peak shape has a minimum said distortion;
(h) applying said correction to said pole-zero cancellation network;
and
(i) repeating said step of detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation through said step of applying said correction to said pole-zero cancellation network until said distortion is minimized.

9 more elements

A method of automatically adjusting a pole-zero adjustment circuit of an ionizing radiation spectroscopy system to achieve a peak shape having a minimum distortion, said method comprising the steps of:

(a) detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation;
(b) processing said random sequence of analog pulses by passing said random sequence of analog pulses through a preamplifier and producing a sequence of preamplified analog pulses having a characteristic decay time constant;
(c) processing said sequence of preamplified analog pulses through a high pass filter incorporating a pole-zero cancellation network to produce a sequence of filtered pulses;
(d) digitizing said sequence of filtered pulses to produce a sequence of digitized pulses;
(e) histogramming said sequence of digitized pulses to produce a spectrum characteristic of said radiation source;
(f) selecting at least one peak from said spectrum suitable for determining the accuracy of an adjustment made by said pole-zero adjustment network;
(g) measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion, said step of measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion including the steps of:
(1) measuring a centroid of a reference peak from an amplitude histogram obtained at a low count rate;
(2) measuring a centroid of a peak from an amplitude histogram obtained at a high count rate;
and
(3) calculating said correction;
wherein when said high count rate peak centroid approximately coincides with said reference peak centroid it is determined that said peak shape has a minimum said distortion;
(h) applying said correction to said pole-zero cancellation network;
and
(i) repeating said step of detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation through said step of applying said correction to said pole-zero cancellation network until said distortion is minimized.

12 more elements

A method of automatically adjusting a pole-zero adjustment circuit of an ionizing radiation spectroscopy system to achieve a peak shape having a minimum distortion, said method comprising the steps of:

(a) detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation;
(b) processing said random sequence of analog pulses by passing said random sequence of analog pulses through a preamplifier and producing a sequence of preamplified analog pulses having a characteristic decay time constant;
(c) processing said sequence of preamplified analog pulses through a high pass filter incorporating a pole-zero cancellation network to produce a sequence of filtered pulses;
(d) digitizing said sequence of filtered pulses to produce a sequence of digitized pulses;
(e) histogramming said sequence of digitized pulses to produce a spectrum characteristic of said radiation source;
(f) selecting at least one peak from said spectrum suitable for determining the accuracy of an adjustment made by said pole-zero adjustment network;
(g) measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion, said step of measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion including the steps of:
(1) measuring a width of a reference peak from an amplitude histogram obtained at a low count rate;
and
(2) measuring a width of a peak from an amplitude histogram obtained at a high count rate and calculating said correction;
wherein when said high count rate peak width approximately equals said reference peak width it is determined that said peak shape has a minimum said distortion;
(h) applying said correction to said pole-zero cancellation network;
and
(i) repeating said step of detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation through said step of applying said correction to said pole-zero cancellation network until said distortion is minimized.

11 more elements

A method of automatically adjusting a pole-zero adjustment circuit of an ionizing radiation spectroscopy system to achieve a peak shape having a minimum distortion, said method comprising the steps of:

(a) detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation;
(b) processing said random sequence of analog pulses by passing said random sequence of analog pulses through a preamplifier and producing a sequence of preamplified analog pulses having a characteristic decay time constant;
(c) processing said sequence of preamplified analog pulses through a high pass filter incorporating a pole-zero cancellation network to produce a sequence of filtered pulses;
(d) digitizing said sequence of filtered pulses to produce a sequence of digitized pulses;
(e) histogramming said sequence of digitized pulses to produce a spectrum characteristic of said radiation source;
(f) selecting at least one peak from said spectrum suitable for determining the accuracy of an adjustment made by said pole-zero adjustment network;
(g) measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion, said step of measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion including the steps of:
(1) measuring a centroid of a reference peak from an amplitude histogram obtained at a low count rate, measuring a width of a reference peak from an amplitude histogram obtained at a low count rate;
(2) measuring a centroid of a peak from an amplitude histogram obtained at a high count rate;
and
(3) measuring a width of a peak from an amplitude histogram obtained at a high count rate and calculating said correction;
wherein when said high count rate peak width approximately equals said reference peak width and said high count rate peak centroid approximately coincides with said reference peak centroid it is determined that said peak shape has a minimum said distortion;
(h) applying said correction to said pole-zero cancellation network;
and
(i) repeating said step of detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation through said step of applying said correction to said pole-zero cancellation network until said distortion is minimized.

12 more elements

A method of automatically adjusting of an ionizing radiation spectroscopy system to achieve a peak shape having a minimum distortion, said method comprising the steps of:

(a) detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation;
(b) processing said random sequence of analog pulses by passing said random sequence of analog pulses through a preamplifier and producing a sequence of preamplified analog pulses having a characteristic decay time constant;
(c) digitizing said sequence of preamplified analog pulses to produce a sequence of digitized pulses;
(d) processing said sequence of digital pulses through a digital filter to produce a sequence of filtered digital pulses;
(e) histogramming said sequence of filtered digital pulses to produce a spectrum characteristic of said radiation source;
(f) selecting at least one peak from said spectrum suitable for determining the accuracy of an adjustment made by said digital filter;
(g) measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion, said step of measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion including the steps of:
(1) measuring a centroid of a reference peak from an amplitude histogram obtained at a low count rate;
and
(2) measuring a centroid of a peak from an amplitude histogram obtained at a high count rate and calculating said correction;
wherein when said high count rate peak centroid approximately coincides with said reference peak centroid it is determined that said peak shape has a minimum said distortion;
(h) applying said correction to said digital filter;
and
(i) repeating said step of detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation through said step of applying said correction to said digital filter until said distortion is minimized.

11 more elements

A method of automatically adjusting of an ionizing radiation spectroscopy system to achieve a peak shape having a minimum distortion, said method comprising the steps of:

(a) detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation;
(b) processing said random sequence of analog pulses by passing said random sequence of analog pulses through a preamplifier and producing a sequence of preamplified analog pulses having a characteristic decay time constant;
(c) digitizing said sequence of pre amplified analog pulses to produce a sequence of digitized pulses;
(d) processing said sequence of digital pulses through a digital filter to produce a sequence of filtered digital pulses;
(e) histogramming said sequence of filtered digital pulses to produce a spectrum characteristic of said radiation source;
(f) selecting at least one peak from said spectrum suitable for determining the accuracy of an adjustment made by said digital filter;
(g) measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion, said step of measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion including the steps of:
(1) measuring a width of a reference peak from an amplitude histogram obtained at a low count rate;
and
(2) measuring a width of a peak from an amplitude histogram obtained at a high count rate and calculating said correction;
wherein when said high count rate peak width approximately equals said reference peak width it is determined that said peak shape has a minimum said distortion;
(h) applying said correction to said digital filter;
and
(i) repeating said step of detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation through said step of applying said correction to said digital filter until said distortion is minimized.

11 more elements

A method of automatically adjusting of an ionizing radiation spectroscopy system to achieve a peak shape having a minimum distortion, said method comprising the steps of:

(a) detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation;
(b) processing said random sequence of analog pulses by passing said random sequence of analog pulses through a preamplifier and producing a sequence of preamplified analog pulses having a characteristic decay time constant;
(c) digitizing said sequence of preamplified analog pulses to produce a sequence of digitized pulses;
(d) processing said sequence of digital pulses through a digital filter to produce a sequence of filtered digital pulses;
(e) histogramming said sequence of filtered digital pulses to produce a spectrum characteristic of said radiation source;
(f) selecting at least one peak from said spectrum suitable for determining the accuracy of an adjustment made by said digital filter;
(g) measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion, said step of measuring a distortion in said at least one peak to determine a correction calculated to minimize said distortion including the steps of:
(1) measuring a centroid of a reference peak from an amplitude histogram obtained at a low count rate;
(2) measuring a width of a reference peak from an amplitude histogram obtained at a low count rate;
(3) measuring a centroid of a peak from an amplitude histogram obtained at a high count rate;
and
(4) measuring a width of a peak from an amplitude histogram obtained at a high count rate and calculating said correction
wherein when said high count rate peak width approximately equals said reference peak width and said high count rate peak centroid approximately coincides with said reference peak centroid it is determined that said peak shape has a minimum said distortion;
(h) applying said correction to said digital filter;
and
(i) repeating said step of detecting radiation from a radiation source using a radiation detector and producing a random sequence of analog pulses representing said detected radiation through said step of applying said correction to said digital filter until said distortion is minimized.

13 more elements

Automatic pole-zero adjustment circuit for an ionizing radiation spectroscopy system and method

Life of this patent

Automatic pole-zero adjustment circuit for an ionizing radiation spectroscopy system and method

Life of this patent

Abstract

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