IEC 61304:1994

FOREWORD
INTRODUCTION
Clause
1 Scope and object
2 Normative reference
3 Definitions and symbols
  3.1 Definitions
  3.2 Symbols
4 Sources and materials
  4.1 Radioactivity standard material
  4.2 Check sources
      4.2.1 Tritium check source
      4.2.2 Carbon-14 check source
      4.2.3 Background check source
      4.2.4 Background sources (unquenched blank)
4.3 Expiration date of check sources
4.4 Materials
      4.4.1 Organic-scintillator solutes
      4.4.2 Radioactive material
      4.4.3 Sample container
      4.4.4 Purging gas
5 Operations and tests
  5.1 General
  5.2 Test procedures
      5.2.1 Frequency of testing
      5.2.2 Initial performance tests
      5.2.3 Routine performance tests
6 Precautions
  6.1 Measurement of radioactivity
      6.1.1 Nuclear decay parameters
      6.1.2 Short half-life with respect to counting time
      6.1.3 Counting systems resolving time
  6.2 Abnormal check-source count rate
      6.2.1 Integrity of the check source
      6.2.2 Photomultiplier tube and amplifier performance
  6.3 Abnormal background check-source count rate
      6.3.1 Contamination
      6.3.2 High-activity sources
      6.3.3 Chemiluminescence, phosphorescence and static
            electricity
  6.4 Miscellaneous precautions
      6.4.1 Organic-scintillator solute purity
      6.4.2 Background activity from low-potassium glass
      6.4.3 Small-vial check sources
Annexes
A Statistical tests of reproducibility - The x2 test and
  other criteria
B Performance monitoring log for liquid-scintillation
  counter
C Physical properties of liquid scintillators and
  requirements for toluene acceptance