Abstract: In order to open the gamma ray spectrum experiment without radiation source, the ^40K within potassium chloride is used to replace the radiation sources, and the content of potassium chloride, the devices, and experimental content are designed. Moreover, the radiation damage is analyzed. The results show that potassium chloride can not only meet the requirement of the gamma spectrum measurement, but also increase the number of experiments. Furthermore, the calculated and measurement radiation dose below the standard of radiation source, so students can finish the experiment safely. Our experimental method is unrestricted by the rules of Environmental Protection Department, help students allay fears, and save the administration cost. Last but not least, the gamma spectrum experiment courses can be opened in some non-nuclear university.

Key words: non-damage, gamma spectrum measurement, potassium chloride sample, spectrum analyze, experimental devices