Normalization technique for photon-counting luminometer
First Claim
1. A method for normalizing two or more photodetectors in a single-photon counting system for measuring the luminescence of multiple samples, said photodetectors comprising a reference detector and one or more other photodetectors, said method comprising:
- successively counting the photon emissions of a standard by two or more photodetectors, at least one of said photodetectors being the reference detector;
computing a counting ratio for each of said one or more other photodetectors, said counting ratio being defined as the ratio of counts from the corresponding one or more other photodetectors to the counts from the reference detector; and
in subsequent use of the photodetection system, multiplying the counts of a luminescent sample measured by a particular photodetector by the inverse of said counting ratio computed for that particular photodetector.
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Abstract
A normalization system for multi-photodetector single photon counting luminescent measuring systems and a standard for use in the same. The method comprises calculating one or more counting ratios for each photodetector in the single photon counting system and multiplying counts of unknown samples by the inverse of the appropriate counting ratio. A counting ratio for a particular photodetector is calculated by dividing the count of a standard measured by the photodetector by the count of the same standard measured by a reference photodetector. The particular standard developed employs calcium tungstate:lead as a scintillator and tritium or carbon-14 thymidine as a means of exciting the scintillator. This standard has the advantages of providing a good model of typical luminescence chemistry and producing an emission pattern which is susceptible to single photon counting.
36 Citations
31 Claims
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1. A method for normalizing two or more photodetectors in a single-photon counting system for measuring the luminescence of multiple samples, said photodetectors comprising a reference detector and one or more other photodetectors, said method comprising:
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successively counting the photon emissions of a standard by two or more photodetectors, at least one of said photodetectors being the reference detector; computing a counting ratio for each of said one or more other photodetectors, said counting ratio being defined as the ratio of counts from the corresponding one or more other photodetectors to the counts from the reference detector; and in subsequent use of the photodetection system, multiplying the counts of a luminescent sample measured by a particular photodetector by the inverse of said counting ratio computed for that particular photodetector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for normalizing two or more photodetectors in a single-photon counting system for measuring the luminescence of multiple samples, said method comprising:
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successively counting the photons emitted by a standard by each of said photodetectors; computing a ratio of the count produced by each of said photodetectors and the count produced by one of said photodetectors selected as a reference, so that multiplying any subsequent measurement of luminescence by the inverse of the counting ratios computed for the respective photodetectors makes the measurement independent of the photodetector performing the counting.
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15. A method for normalizing two or more photodetectors in a single-photon counting system for measuring the luminescence of multiple samples, said photodetectors comprising a reference detector and one or more other photodetectors, said method comprising:
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successively counting the photon emissions of two or more standards with varying activity levels by two or more photodetectors, at least one of said photodetectors being the reference detector; computing one or more counting ratios for each of said one or more other photodetectors, said one or more counting ratios being defined as the ratio of counts from the corresponding one or more other photodetectors of a standard to the counts from the reference detector of the same standard; and in subsequent use of the photodetection system, multiplying the counts of a luminescent sample measured by a particular photodetector by the inverse of one of said one or more counting ratios computed for that particular photodetector, said one of said one or more counting ratios constituting a photodetector'"'"'s corresponding counting ratio. - View Dependent Claims (16, 17, 18, 19)
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20. An apparatus for normalizing two or more photodetectors in a single-photon counting system for measuring the luminescence of multiple samples, said photodetectors comprising a reference detector and one or more other photodetectors, said apparatus comprising:
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means for successively counting the photon emissions of a standard by two or more photodetectors, at least one of said photodetectors being the reference detector; means for computing a counting ratio for each of said one or more other photodetectors, said counting ratio being defined as the ratio of counts from the corresponding one or more other photodetectors to the counts from the reference detector; and means for multiplying the counts of a luminescent sample subsequently measured by a particular photodetector by the inverse of said counting ratio computed for that particular photodetector. - View Dependent Claims (21, 22, 23)
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24. A standard for normalizing two or more photodetectors in a single-photon counting system used to measure the luminescence of samples, said standard comprising:
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a scintillator whose photon emission has a peak wavelength of about 433 nanometers, a radioactive material whose radioactive decay excites photon emission from the scintillator, and containment means. - View Dependent Claims (25)
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26. A standard for normalizing two or more photodetectors in a single-photon counting system used to measure the luminescence of samples, said standard comprising:
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a scintillator whose photon emission has a peak wavelength of about 433 nanometers, means for exciting said scintillator, and a microplate.
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27. A standard for normalizing two or more photodetectors in a single-photon counting system used to measure the luminescence of samples, said standard comprising:
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a scintillator whose photon emission has a peak wavelength of about 433 nanometers, means for exciting said scintillator, containment means, and means for maintaining said scintillator in said containment means, said maintaining means including a binding material composed of carboxy methyl cellulose.
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28. A standard for normalizing two or more photodetectors in a single-photon counting system used to measure the luminescence of samples, said standard comprising:
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a scintillator whose photon emission has a peak wavelength of about 433 nanometers, means for exciting said scintillator, containment means, and means for maintaining said scintillator and said means for exciting said scintillator in said containment means, said maintaining means including a potting material. - View Dependent Claims (29, 30)
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31. A standard for normalizing two or more photodetectors in a single-photon counting system used to measure the luminescence of samples, said standard comprising:
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a scintillator whose photon emission has a peak wavelength of about 433 nanometers, said scintillator comprising calcium tungstate;
lead,means for exciting said scintillator, said exciting means being either tritium or carbon-14 thymidine, a microplate, means for maintaining said scintillator in said microplate, said means for maintaining said scintillator in said microplate comprising carboxy methyl cellulose, and means for maintaining said scintillator and said means for exciting said scintillator in said microplate, said means for maintaining said scintillator and said means for exciting said scintillator in said microplate comprising an epoxy,
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Specification