Development and application of simulation-based teaching equipment for radioactive experiments
[Objective]To meet the challenge of large-scale use of radioactive sources and radiation measuring devices in radiation experiment teaching,a simulation device for radiation experiments was developed,which serves as the foundation for establishing a simulation-based teaching platform for radioactivity experiments.Based on this platform,various types of experiments can be conducted in the teaching process of nuclear majors,thereby improving their quality of education.[Methods]The teaching platform includes four main components:a PC host computer,an embedded master controller,a laser diode(LD)-based nanosecond light source,and a digital pulse processor(DPP).The working process is as follows.First,the host computer calls different experimental models and simulates the particle transport process that models the interaction between radiation and the involved detector,thereby generating a particle data stream that matches the characteristics of the radioactive source and detector.Second,the embedded master controller converts this particle data stream containing the characteristics of the radioactive source into a digital signal stream and drives a high-speed digital-to-analog converter to output a current pulse signal with random amplitude and timing.Third,the LD outputs a nanosecond optical signal that corresponds to the detector signal waveform when driven by a current pulse;then,the optical signal is converted into the electrical signal by the photoelectric conversion device.Last,the DPP operates in the particle multiparameter measurement mode.It uses a digital trapezoidal shaper to achieve excellent filtering and noise reduction,thereby improving the accuracy of pulse amplitude extraction.In addition,a symmetrical zero-surface trapezoidal shaper is used to suppress low-frequency noise and improve the accuracy of pulse triggering.It can acquire the amplitude,timing,and detector position information of the incident particles in each channel,effectively replacing the need for multiple radiation measurement devices.[Results]Experimental teaching was conducted,i.e.,waveform output experiments were performed on simulated NaI(Tl)and LaBr3(Ce)detectors under different levels of radioactive source activity.The output waveform pulse width for the simulated NaI(Tl)detector was about 800 ns,while the signal pulse width for the simulated LaBr3(Ce)detector was about 200 ns.The characteristics of the output waveforms were found to be consistent with those of the actual detectors.In addition,energy spectral measurements for the radioactive sources 137Cs,60Co,and 152Eu were successfully completed,with the results agreeing well with the data obtained from actual detectors.[Conclusions]The experimental platform offers several advantages,such as safe use,easy operation,stable performance,and strong scalability.It can be used to conduct various cognitive,basic,and comprehensive radioactive experiments.This eliminates the risk of harm from ionizing radiation for both teachers and students and ensures the safety of experiments.In addition,it allows students to independently conduct experiments and thus improve their practical engineering skills.
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