Nuclear level detector radiation source

After the dismantled equipment had been trucked away, my boss said, "And where, Lieberman, is the nuclear level detector radiation source 1 imagine even you must realize that these radioactive sources are licensed. God help us if you have lost it."... 

Artificial sources of radiation are commonly used in industry, research, medicine, nuclear power plants (NPP), etc. Some workers are exposed to natural sources, for example, in mines and other conditions where the radon concentration in air might be higher than in normal cases. Relatively high dose rates are measured during air travel due to the elevated levels of cosmic rays at high altitudes. This means that many people are exposed in their work. Some of them are monitored individually, for example, by a small photographic film, thermoluminescent material, or portable electronic devices. These types of detectors on the body register the dose due to the external sources and yield an estimate of the dose received by the wearer. 

Generally, a-particle counters do not require shielding for nuclear forensic applications residual contamination in a low-level chemical fiaction and nuclides that recoiled into the detector from previous counting sources are always more important contributions to the detector background than the natural radiation environment. Shielding from cosmic rays and environmental radiation (i.e., photons from and the natural U and Th decay chains) is required in the operation of y- and X-ray counters. A thickness of 20 cm of Pb is sufficient for... 

Building blocks, isotopes, nuclear reactions (particularly neutron induced), neutron sources, radioactive decay, calculation of radiation level from radioisotope ionization of gases, and ionization in neutron detectors by secondary actions. 

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