Patent GB-1038885-A (GB)
Title: Improvements relating to gamma ray guns
IPC: G21F5/02
Filed: 1963-10-18
Abstract: 1,038,885. Gamma ray guns. K. SAUERWEIN. Oct. 18, 1963 [Oct. 30, 1962; Dec. 7, 1962], No. 41272/63. Heading H5R. A gamma ray gun, for testing workpieces, comprises a protective shield of ionizing radiation absorbent material surrounding a capsule 11 (Fig. 4) containing the radiation source, the shield being in two parts 2, 3, the first of which is mounted within a cylindrical casing 1. The part 3 is in the form of a cap 3 which fits partially within the casing 1, but which can be displaced longitudinally away from it to form a discshaped gap (Fig. 2, not shown) into which the capsule 11 is pushed. A pneumatic or hydraulic drive is used to move both cap and capsule. To displace the cap, fluid is introduced into a chamber 9 through a pipe connection 23 and forces the piston 21 to move against the spring 5, also causing the sleeve 4, attached to the piston 21, to move. The sleeve 4 is attached by means of a sleeve 4a to a thrust-piece 7 which is arranged to couple with a rotary slide 16, 16a to cause a cap guide extension 6 to slide out from the casing 1, carrying with it the cap 3, until the sleeve 4 abuts against the surface 2a. When the gap is formed the outside faces of the extensions 6, which are painted to become luminous when exposed to ionizing radiation, are revealed, indicating that the parts 2 and 3 are separated. The capsule 11 is pushed into the centre of the gap after the cap 3 has been displaced from the part 2, since the area of the piston 22 exposed to fluid is less than that of piston 21. Further, it is retracted into the shield 2 before the gap closes again. A stop-pin 13 ensures that the capsule source is located in the centre of the gap. The guide 6 around the gap stops the penetration of dust &c. which could prevent reclosing of the gap, but is not thick enough to absorb the gamma rays. Besides obtaining an annular beam of radiation (Fig. 2), the cap 3 is provide with means for obtaining a conical beam axially of the casing 1 (Fig. 3, not shown). This consists of a uranium plug 14 mounted on an arm 15 so that it can swing out of a conical bore in the cap 3. The arm is pivoted between side-plates 31 and carries a pinion 18 which can be coupled with the thrust-piece 7 to be actuated under fluid pressure. To couple the pinion 19 with the thrust-piece 7 the rotary slide 16, 16a is turned through about 90 degrees from the position shown in Fig. 4, is pushed forward so that the rack 17 is level with the pinion and is rotated so that the rack engages the pinion. On application of fluid pressure the thrust-piece is driven forward to move the arm 15 out; outward movement of the cap being prevented by the locking of the cap guide 6 by the engagement of projections on the slide 16, 16a with shoulders on the block 2, as a result of the rotation of the slide. The angle of the conical beam from the capsule 11 can be increased by pushing the capsule further out from the shield part 2. An area in the outside of the cap may be painted, but is covered by a hood 33 when the plug is in position within the cap. A locking bolt 19 secures the plug 14, being coupled to the cap by a bayonet connection. A safety locking device involving a spring-loaded locking-pin 34 and lever 35 may also be provided. A safety device to override the application of fluid pressure may be provided and consists of a locking member 20 which engages an extension 7b of the thrust-piece 7 and prevents movement of the cap away from the casing 1. Contacts 37a, 37b in a switch-box 38 are provided for operation of the gun from a remote place. The capsule 11 (Figs. 8, 10, not shown) comprises two parts, enclosing a cavity for the radio-active source, and joined together by soldering or welding. The capsule has at one end flat outer faces for its withdrawal from the bore by pliers &c., and at the other, a screw thread by which it is attached to the push-rod 12.