Which radioactive sources are used for Spectrum Analyzers?

The use of Cobalt 57 and Cadmium 109 as radioactive sources for spectrum analyzers is primarily due to their specific gamma radiation characteristics, which are suitable for the energy range that spectrum analyzers need to detect.

Cobalt 57 emits gamma radiation at an energy level of approximately 122 keV, which is commonly used in gamma spectroscopy. This energy level facilitates the identification of various materials and the analysis of their spectra. Cobalt 57 is especially useful because it's often employed in calibration and as a standard for measuring equipment.

Cadmium 109 also emits gamma radiation, including a notable peak at around 88 keV. This property makes it advantageous in that it can be used to calibrate devices and is effective in various applications requiring precise measurements in the lower energy range of gamma rays.

These isotopes provide the necessary stability and energy emissions needed for effective measurement and analysis in laboratory settings, making them ideal choices for spectrum analyzers in research and various industry applications.

In contrast, the other options listed do not provide the same optimal gamma ray energies for spectrum analysis or may not be as widely utilized in that specific context.