Patent ID: 9562978
Date: 2017-02-07
CPC Classifications: G01T

Claim:
1. A portable detection apparatus, comprising: a) a housing; b) a first detector within the housing for detecting ionizing radiation comprising background radiation and secondary radiation; c) a second detector within the housing for the detecting the background radiation; d) a shield within the housing and surrounding the first and second detectors, the shield defining a shield aperture around the first and second detectors for the ionizing radiation to enter the housing; e) a radiation blocking member positioned between the shield aperture and the second detector so that a first portion of the ionizing radiation entering the housing through the shield aperture reaches the first detector without passing through the radiation blocking member and a second portion of the ionizing radiation entering the housing through the shield aperture passes through the radiation blocking member before reaching the second detector, whereby radiation detected by the second detector comprises substantially only the background radiation; and f) a processor module connected to the first and second detectors for determining the amount of ionizing radiation detected by the first detector attributable to the secondary radiation.