PRA is a smart software that transforms your PC sound card into a powerful multi channel analyser for gamma spectrometry. PRA was developed by Marek Dolleiser at Sydney University as an aid to teach physics students about atomic theory.
The sound card in your PC can digitise the audio signal from your scintillation detector at 48Khz or in some cases 96 Khz which is even better. The software then processes the signal by calculating the RMS value of the signal and filtering out any badly formed pulses. the result is amazing!
The data can now be presented in a number of ways as follows;
a) Count rate vs. Time, this function simply records the counts at set intervals, and is useful for recording decay rates etc.
b) Interval Histogram, this function creates a histogram of the intervals between gamma pulses, and may be of use in the nuclear research lab.
c) Pulse Width Histogram, this function creates a histogram of the pulse width, not commonly used, but may be useful when testing different types of scintillators and pre amplifiers.
d) Pulse Height Histogram, this is the most used funktion, and the one that creates the gamma spectrum, the program calculates the pulse height and automatically bins it in up to 32,000 bins. The bin size can be changed in the settings panel. Individual peaks can be selected and highlighted, to reveal more information obut the peak, such as net counts, standard deviation etc.
e) Listen to Gamma Radiation, Action >> Sound On/Off – switches on and off playing in real time sound representing arriving pulses. Larger pulses are played with higher pitch. This new in PRA version seven feature is primarily implemented for visually impaired people, but also can be quite entertaining for others. It is absolutely possible recognise many of the simple radioactive sources by listening to the sound. I can recognise 54Mn, 57Co, 60Co, 133Ba, 109Cd, and 137Cs using NaI detector.
The data from all PRA histograms can be exported as text files and impoted into other programs such as Excel, for a better presentation. PRA can be downloaded free from Marek Dolleiser's web site.