GB1186347A - Improvements in or relating to Liquid Scintillation Counters - Google Patents

Abstract

1,186,347. Liquid scintillation counters. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. March 23, 1967 [April 29, 1966], No. 19060/66. Heading G1A. Liquid scintillation counter apparatus, having interlocking shutter devices to permit a bottle (containing the scintillator and isotope under investigation) to be changed without exposing the photo-multiplier to ambient light, is provided with a passageway through the external shielding of the apparatus into which the carrier of a sealed γ-source can be inserted for measurement of the counting efficiency of the apparatus by the "external standard" method. The external shielding comprises well member 1, enclosing the photo-multiplier 10 and defining part of a chamber 7, the top part of which is defined by shielding lid 2 hinged at 4. The shutter devices referred to above are a shutter 18, between the photo-multiplier 10 and the bottle carrier 11, and a cover 14, hinged at 15, which, when closed, excludes external light from the bottle located in the carrier 11. When the lid 2 is lifted, the plug 22 in the lid, is brought out of engagement with a plate 21 integral with stud member 20. The bottle carrier 11, biased upwardly by a spring 13, is now free to move upwards (to position of Fig. 2, not shown). To free cover 14 for lifting, a catch 16 is turned, which causes simultaneous movement of the shutter 18, through the interlocking pin 17, to cover the photomultiplier. The external source 24 used in determining counting efficiency may be moved into position down a bore in the plug 22, the source being carried in a tube 23 closed at is upper end 25. The source may be barium - 133, caesium - 137, cerium - 133, radium - 224 or strontium - 85.