Gamma-metrics

Andrew H Smith

Chris A Isaacson

Thomas L Atwell

Raymond J Proctor

Chaur-Ming Shyu

James P Stronski

Richard A Ackermann

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 another side of the activation region for detecting gamma-rays emitted from the bulk material, a primary neutron moderator is disposed about the neutron sources for reducing the velocity of the emitted neutrons; and a secondary neutron moderator is disposed about the primary neutron moderator for further reducing the velocity of the neutrons and is further disposed adjacent the lateral edges of the activation region for channeling and reflecting the neutrons into the activation region. The two gamma-ray detectors are disposed toward opposite lateral edges of the activation region, with each detector being skewed so that a portion of each detector that is closer to the edge of the activation region toward which the detector is disposed than to the lateral center of the activation region is disposed closer to a plane passing laterally through the center of the activation region than is another portion of each detector that is closer to the lateral center of the activation region than to the edge of the activation region toward which the detector is disposed. Spatial compensators are disposed adjacent the same side of the activation region as the detectors for reflecting neutrons toward the activation region at a greater density toward opposite lateral edges of the activation region than toward the center of the activation region. Bladders containing a liquid primary neutron moderating material that expands and contracts with temperature variations, such as heavy water, are tightly packed within a compartment for maintaining a substantial quantity of the liquid material between the neutron sources and the activation region notwithstanding thermal contraction of the liquid material; and a resilient compressible foam is disposed about the bladders for enabling the tight packing of the liquid material to be maintained notwithstanding expansion and contraction of the liquid material.

Enhancement of measurement accuracy in bulk material analyzer

A bulk material analyzer of the type in which the bulk material is transported through the material analyzer assembly on a conveyor belt between at least one radiation source and at least one radiation detector, includes a plurality of lower and upper modules that contain radiation shielding material and are so shaped as to define a passageway for the conveyor belt between the upper modules and the lower modules when the upper modules are placed on the lower modules. A primary centrally located lower module also includes the radiation sources and a primary centrally located upper module also includes the radiation detectors. Some of the outwardly located modules contain less radiation shielding material. The radiation shielding material includes a plurality of personally portable blocks. The conveyor belt is supported by compressed air passed through central upper wails in the outwardly located lower modules. The lower modules contain alignment members on upward facing surfaces thereof and the upper modules contain alignment members on downward facing surfaces thereof that are complementary to the alignment members on the upward facing surfaces in order to enable the upper modules to be accurately placed on the lower modules. The lower modules each include a central upper wall bounded by outwardly inclined inner side walls to define a trough for accommodating passage through the passageway of a conveyor belt having a contour corresponding to the trough. The container includes apertures disposed beneath at least part of the passageway, and includes conduits leading to the apertures from a port adapted to be connected to a source of compressed air so that the conveyor belt can be at least partially supported by compressed air while passing through the passageway.

Modularized assembly for bulk material analyzer

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Escondido, CA, United States of America

Andrew H Smith