US 5,124,554 AGranted

Explosives detector

AssigneeRolls-Royce and Associates Limited

InventorsPeter H. Fowler, Peter A. E. Stewart, John D. Rogers, Martin J. Allen

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Abstract

Apparatus for non-invasively inspecting an object, such as an item of luggage, for explosives material comprises a multi-channel thermal neutron inspection system having a plurality of neutron irradiation chambers. Simultaneous operation of several channels increases maximum system throughout several times. Each chamber has a lithium neutron source which is stimulated to neutron production by a proton beam. Beam switching magnets are energized by pulsing to divert a common proton beam to each source in turn. The initial beam is generated by a radio frequency quadrupole accelerator. The advantages of this system are very low residual source activity and controllable neutron production thereby minimizing safety hazards. The irradiation chamber may contain several different gamma ray detectors to identify the presence elements present in explosives material. In addition a neutron radiography imaging means may be employed to identify the presence of potential shielding materials.

Claims17

Dependent claims

Apparatus for detecting explosives material in an item by means of a thermal neutron activation process comprising:

a structure having walls defining an irradiation chamber for receiving the item,
neutron source means for producing a beam of mixed energy neutrons including:
a lithium target,
a source of protons,
a radio frequency quadropole accelerator (RFQ) means for accelerating the protons, the RFQ means being energized to accelerate the protons to an energy of 2.5 MeV in a direction of the lithium target whereby an endothermic reaction produces neutrons in a direction of an incident beam having a mean energy of 0.5 MeV and a peak energy of 0.77 MeV,
means within the irradiation chamber for moderating and reflecting neutrons to produce a uniform distribution of thermal neutrons within the item placed within the irradiation chamber,
gamma ray detecting means disposed adjacent the irradiation chamber to detect gamma rays emitted by contents of the item as a result of thermal neutron activation caused by said neutrons and to produce an output indicative of an energy spectrum of aid detected gamma rays, and
means for collating a plurality of said outputs to detect a resonance in a gamma ray energy spectrum indicative of a presence of at least one predetermined element in said item.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/656,942Filed 19 Feb 1991
Priority: GB 9003851.420 Feb 1990
Granted: 23 Jun 1992
Term ends: Not estimatedThe source records don’t support an estimate.

Classification18 codes

H05H 3/04
Production or acceleration of neutral particle beams, e.g. molecular or atomic beams: acceleration by electromagnetic wave pressure
B64F 1/368
Other airport installations: arrangements or installations for routing, distributing or loading baggage
G01N 23/222
By activation analysis: using neutron activation analysis [NAA]
G01V 5/20
Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity: detecting prohibited goods, e.g. weapons,…