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Method of surface surveying for radioactive sources

  • US 5,585,628 A
  • Filed: 06/30/1995
  • Issued: 12/17/1996
  • Est. Priority Date: 06/30/1995
  • Status: Expired due to Term
First Claim
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1. A method of surveying a surface to detect a source of radioactivity, said survey being performed with a detector having predetermined characteristics, comprising:

  • determining a background count rate for said detector;

    determining an expected source count rate from passing said detector over said source;

    selecting a first detector scan velocity, and determining a first distribution of counts probability for said detector as a function of said background count rate at said first velocity, and a second distribution of counts probability for said detector as a function of the combination of expected source and background count rates at said first velocity;

    obtaining from said first probability distribution a background decision probability distribution as a function of counts, and obtaining from said second probability distribution a combination decision probability distribution as a function of counts;

    presenting said decision probability distributions, and determining from them whether the source activity can be identified with a predetermined degree of confidence;

    iteratively selecting one or more detector scan velocities, and for each selected velocity repeating the above steps of determining distributions of counts probability and decision probability distributions and determining therefrom the degree of confidence of identifying source activity corresponding to each selected velocity,selecting, based on said determinations of degree of confidence, an optimum scan velocity at which source activity can be found with about said predetermined degree of confidence; and

    surveying said surface at about said optimum detector velocity.

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