Patent Number: 050531859
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENT In a preferred embodiment of the present invention, as shown in FIGS. 1, 2, 3 and 4, the material analyzer includes a container 10, a radiation source 12, a detector 14, a carousel 16, radiation shielding material 18 and a computer 20. The radiation source 12, the detector 14, the carousel 16 and the radiation shielding material 18 are disposed at least partially within the container 10. The radiation source 12 includes neutron soruces 12 secured to the ends of three rods 22, which are fastened to brackets 24 attached to an exterior wall of the container 10. The rods 22 are not radioactive. The brackets 24 are covered by a locked cover 26 that may be unlocked and removed when the rods 22 and the neutron sources 12 secured thereto are removed from or inserted within the container 10. The detector 14 is disposed above the radiation source 12. An activation region 28 is located between the radiation source 12 and the detector 14. The detector 14 is disposed for detecting radiation that is secondarily emitted by a material sample 30 within the activation region 28 when the material sample 30 is bombarded by radiation from the radiation source 12. The detector 14 produces signals in response to said secondarily emitted radiation; and the computer 20 processes said signals to determine the content of the material sample 30. The results of said processing by the computer 20 are displayed by a monitor (not shown) and printed by a printer (not shown). The radiation shielding material 18 is disposed within the container 10 for shielding the outside of the container 10 from radiation derived from the radiation source 12, including both direct radiation from the radiation source 12 and secondarily emitted radiation derived in the activation region 28 from the material sample 30. The carousel 16 is disposed for rotation about an axle 32. The carousel 16 is rotated by a motor 34 and a rubber wheel 36 mounted on the shaft of the motor 34 (as shown in FIG. 3), with the motor 34 and rubber wheel 36 being located beneath the carousel 16 so that the rubber wheel 36 continuously contacts an under surface 38 of the carousel 16. The axle 32 defines an axis of rotation which is located between the activation region 28 and a receiving region 40 located outside the container 10. In alternative embodiments (not shown), the carousel is mounted on the carousel 16 to the axle 32 and rotated by driving the axle; or is rotated by driving the perimeter of the carousel 16. The carousel 16 includes two sample containment chambers 42, 44 located on opposite sides of the carousel 16 such that the carousel 16 can be rotated to position one sample containment chamber 42 within the activation region 28 and at the same time position the other sample containment chamber 44 within the receiving region 40 outside the container 10. The carousel 16 also includes a radiation shield 46 disposed laterally around each sample containment chamber 42, 44 in order to prevent the material sample 30 and/or the detector 14 from being bombarded by secondarily emitted radiation from materials within the carousel 16 that are disposed at the sides of the sample containment chambers 42, 44. The width of the carousel 16 is approximately four feet (1.2 m), which is considerably more than the width of a typical doorway, which is about thirty inches (75 cm). Therefore, in order to enable the carousel 16, which is quite heavy, to be moved through a doorway without having to be severely tipped from a horizontal orientation, outside portions 47 of the carousel 16 on two opposite sides of the carousel 16 that do not contain the sample containment chambers 42, 44 are readily removable from a center portion 48 of the carousel that does not exceed thirty inches in width. See FIG. 2. When the sampled material is fluid material, such as granular material, the material sample 30 is placed in a bucket 49, which is placed in one of the sample containment chambers 42, 44. Typically a plurality of buckets 49 are loaded with material samples 30 prior to beginning analysis of a series of samples. Typically the buckets 49 are quite heavy and need to be lifted with a handle 50 to lessen the chance of the material sample 30 being spilled during handling of the bucket 49. Providing the buckets with handles also allows one person to carry two buckets simultaneously. Referring to FIG. 5, each bucket 49 includes a perimetric side wall 52 having a predominant surface area that is contoured on opposite sides of the side wall to contain exterior indentations 54 in said predominant surface area. In the preferred emboidment, the bucket 49 is made of plastic material. When the bucket 49 is placed in the sample containment chamber 42, 44, the bucket 49 does not extend beyond the sample containment chamber; and the predominant side wall area of the bucket fits closely within the sample containment chamber. The handle 50 includes a pair of tongs 56 that aare shaped and disposed for insertion into the side wall indentations 54. The handle 50 includes two telescopic sections 58, 59 that join the tongs 56 so that the tongs 56 can be moved toward each other to fit within the side wall indentations 54 in order to grip the bucket 49 and thereby enable the bucket 49 to be transported by using the handle 50, and so that the tongs 56 can be moved away from each other to enable the handle 50 to be removed from the bucket 49 after the bucket has been transported and placed in one of the sample containment chambers 42, 44. Referring to FIG. 6, a sample mixer 60 is provided for use in throughly mixing granular material samples. The sample mixer 60 includes a Y-shaped container 62 having a hollow leg 64 and two hollow arms 66 that open into the leg 64. Each arm 66 has an extended end 70 that is closed. The leg 64 has an extended end 72 that is open and dimensioned to fit precisely against a rim 73 at the open end of the bucket 49. The open end 72 of the leg 64 thus also fits within an open end of each sample containment chamber 42, 44. In the preferred embodiment, the container 62 is made of plastic material. A knife blade shutter 74 is attached to the extended end 72 of the leg 64 for movement between open and closed positions. When the shutter 74 is in the open position, granular material may flow into or from the container 62 through the extended end 72 of the leg 64. When the shutter 74 is in the closed position, the shutter 74 prevent granular material from flowing out of the container 62 from the extended end 72 of the leg 64. The container 62 is disposed on an axle 76 for rotation about an axis that is normal to the leg 64 so that sample material within the container 62 can be thoroughly mixed by rotating the container 62 about the axle when the shutter 74 is in the closed position. After a material sample 30 is thoroughly mixed by the sample mixer 60, the container is positioned over a bucket 49, with the extended end 72 of the leg 64 fitted against the rim 73 of the bucket 49; and the shutter 74 is opened to allow the sample material 30 to flow into the bucket 49. When the bucket 49 is filled to the rim 73, the knife blade shutter 74 is closed to provide a thoroughly mixed material sample that is measured to exactly fill the bucket 49 to its rim. Excess material remains in the container 62. The present invention is also useful for analyzing material samples that are not fluid or granular, such as parcels or luggage. In an embodiment of the present invention (not shown) in which the sample containment chambers are adapted to accommodate luggage, the apparatus of the present invention may be used at airports for analyzing luggage for explosive materials.