“For detection is used high voltage (from 8000 to 15000 volts)
The presence of Alpha radiation is manifested by small sparks between the anode and the cathode.
This time I will show you how to make a very simple device that can detect Alpha radiation. The device is also called a Spark detector, because for detection is used high voltage (from 8000 to 15000 volts), and the presence of Alpha radiation is manifested by small sparks between the anode and the cathode.
In this type of detector, thin negatively-charged wires are strung through atmospheric air above a planar anode, and sparking occurs when strongly ionizing radiation like alpha particles passes through the high-field region near the wires.
The concept was first described by Chang and Rosenblum in 1945, and later it was made many times. Nowadays its making is extremely simple, thanks to these compact high voltage sources that can be purchased for a few dollars. This detector only responds to alpha particles and has no beta or gamma sensitivity at all. Alpha particles are the most ionizing, being much more massive than the beta particles, or X-ray and Gamma-ray photons, so they easily will ionize the air between the wires and the other electrode. The lower electrode (Anode) is desirable to have no sharp edges, as in this case, to avoid the so-called Leakage of electricity.”