Th-nat

Spectrum:

Figure 1: Energy histogram of the γ-radiation from a thorium source. It is a complex spectrum to which many daughter isotopes in the long thorium decay chain contribute.

Figure 2: Energy histograms around the 2614.5 keV γ-ray line from ²⁰⁸Tl, which is a member of the thorium decay chain.

We define the peak-to-Compton (P/C) ratio of the 2614.5 keV line as the ratio of intensities at 2614.5 keV and 2250 keV. As can be seen the 2-inch NaI(Tl) detector has the least stopping power and its P/C ratio is 2.2. The 2-inch CsI(Na) and the 3-inch NaI(Tl) detectors are similar in stopping power and energy resolution, and in this particular case the spectra overlap. Their P/C ratio is 2.7. The 3-inch CsI(Na) achieves a P/C ratio of 4.2