On April 12, 2016 , the USPTO issued U.S. Patent Number 9,310,323 to RAPISCAN SYSTEMS, INC., which was successfully prosecuted by Novel IP.
The '323 patent is directed towards a second stage screening system configured to resolve a threat alarm detected in a cargo by a first stage screening system. The second stage screening system includes layers of first muon detectors placed above the cargo to detect a first coordinate and an angle of incidence of incoming muons and layers of second muon detectors placed below the cargo to detect an actual coordinate and an actual angle of exit of the incoming muons. The first and second detectors measure a momentum of the incoming muons. A processing unit receives threat sensitivity vectors determined from the first stage, operates a cargo positioning system that centers a high-Z threat within the cargo, relative to the first and second muon detectors, and analyzes the momentum and a distribution of deflection angles between the angles of incidence and exit to resolve the threat alarm.
Independent Claim 1 describes " A second stage screening system to resolve a threat alarm detected in a cargo by a first stage screening system, wherein said first stage screening system generates threat sensitivity vectors, said second stage system comprising: a first muon detector set placed above the cargo to generate first muon information comprising a first coordinate and an angle of incidence of incoming muons; a second muon detector set placed below the cargo to generate second muon information comprising an actual coordinate and an actual angle of exit of the incoming muons; a detector to measure a momentum of said incoming muons; and, a processing unit, wherein said processing unit: receives threat sensitivity vectors determined from the first stage; operates a positioning system that positions a high-Z threat within the cargo relative to said first and second muon detectors; employs said first and second muon information and threat sensitivity vectors to confirm a presence of high-Z materials; and uses an approximate Z distribution and density of a content of said cargo to compensate for a presence of cargo content in a vicinity of said high-Z threat. "