Gamma-metrics

Siaka Yusuf

Raymond J Proctor

Michael J Hurwitz

James P Stronski

Craig A Griebel

Kim-Chinh Tran

A modular assembly for a bulk material includes container modules defining at least one radiation source cavity, at least one radiation detector channel and a passageway disposed for enabling passage of the conveyor belt through an activation region; and radiation shielding material disposed within the container means. A lower primary module contains a first portion of the radiation shielding material and defines either the radiation source cavity or the radiation detector channel. An upper primary module contains a second portion of radiation shielding material and defines the other of either the radiation source cavity or the radiation detector channel. A set of replaceable side modules contain additional portions of the radiation shielding material. The lower primary module, the upper primary module and the replaceable side modules are so shaped that the passageway is delimited by placement of side modules upon the lower primary module and placement of the upper primary module upon side modules; and portions of the replaceable side modules are shaped for delimiting the sides of a trough that is contoured for accommodating passage of the conveyor belt through the activation region. Replaceable liners of neutron moderating and/or absorbing and/or reflecting material may be placed adjacent the passageway and adjacent the side modules and/or the lower module and/or the upper module for further delimiting the passageway and/or the sides of the trough. The assembly can be modified for use with large ranges of conveyor belt sizes and shapes by replacing the replaceable side modules and/or the replaceable liners.

Flexible multi-purpose modular assembly for a family of PGNAA bulk

In a bulk material analyzer in which bulk material is received in an activation region between a pair of neutron sources laterally disposed on one side of the activation region for emitting neutrons for bombarding the bulk material within the activation region to cause gamma-rays to be emitted from the bombarded bulk material and a pair of gamma-ray detectors laterally disposed on an opposite side of the activation region for detecting gamma-rays emitted from the bulk material, and in which a neutron moderator is disposed between the neutron sources and the activation region for reducing the velocity of the emitted neutrons such that the neutrons entering the activation region include thermal neutrons and faster neutrons, the uniformity of sensitivity of the bulk material analyzer to materials at different positions in a sample of the bulk material being analyzed is enhanced by controlling the proportions of thermal neutron at different positions within the sample being analyzed. A neutron absorber disposed close to the one side of the activation region reduces the proportion of thermal neutrons that enter the activation region from the one side of the activation region. A neutron reflector disposed on the opposite side of the activation region at least as close to the activation region as the gamma-ray detector(s) reflects neutrons into the activation region for bombarding bulk material within the activation region. In some embodiments, the neutron absorber and/or the neutron reflector are adjustable; and the disposition of the neutron sources also is adjustable for also adjusting the proportion of the thermal neutrons that enter the activation region from the one side of the activation region.

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San Diego, CA, United States of America

Siaka Yusuf