Figure 2. Background Spectra at different positions
In figure 2, due to the statistical fluctuation, the total counts of each spectrum were fluctuating. Except for outliers, the range of the counts of each spectrum were about 30-62.
Spectrum investigation of signals containing radioactive sources
For further investigation, we carried out the research of the spectra containing radioactive sources. In the study, a Cs-137 source with activity of 25kBq was employed.
According to the activity of the source, we set up several test positions. The distances between source and test positions were 10cm,15cm,20cm,25cm,30cm and 35cm respectively. The dose rate generated by the source at the test positions were 0.213μGy/h,0.095μGy/h,0.053μGy/h,0.034μGy/h,0.024μGy/h,and 0.017μGy/h. 100 sets of 1-s spectra were collected at each position. The mean spectra at different test position and the total count of each spectrum were shown in figure 3 and figure 4 respectively.