Neutron Detection and Measurement

Proportional counters filled with BFs or He are used for integral measurement of thermal and epithermal neutrons. Fluxes and spectra of neutrons of intermediate or high energy can be measured with proportional counters filled with He or Hi. Instead of Hi, solid hydrogen-containing compounds such as polyethylene can be used. 

Instead of direct counting, neutron fluxes can also be determined by activation methods. Activation by (n, y) reactions (chapter 8) and subsequent measurement of the induced activity is a widely used technique. Au, In and Co are frequently applied as flux monitors. The presence of epithermal neutrons makes corrections necessary. Epithermal neutrons may be measured independently by wrapping the flux monitors in Cd or Gd which absorb the thermal neutrons. Fluxes of high-energy (fast) neu- 

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