Dr Lara Mikac - Smart device assembly for ionizing radiation sensor (WG5)
Host: Prof Attilio Converti, Universita degli Studi di Genova (DICCA), Italy [15 - 22nd of July 2019]
Figure 1: Assembled sensor for ionizing radiation connected with the PC
The purpose of this STSM was to assemble a small portable device for the detection of ionizing radiation from natural sources. The parts of the sensor that had to be assembled are the probe, Master, Geiger adapter and connecting cables. After successfully assembling smart device we have tested it by measuring samples. First, we have measured the background signal. Common background radiation goes from 0.040 to 0.100 μSv/h, depending on location. In our measurements the background radiation was from 8 to 14 nSv/h. In order to further test the radiation sensor we have used available samples and measured their radiation. In order to test the radiation sensor we used Americium extracted from a smoke detector. Am isotope form, Am-241, is used in smoke detectors in a very small amount (0.2 μg). In our case it showed significant signal enhancement compared to background levels of radiation. Another sample that showed substantial signal with direct contact with the probe, was dietary salt. The composition of the dietary salt was: KCl, NaCl (35%), potassium citrate, magnesium sulfate, magnesium carbonate and calcium carbonate. Low sodium or diet salt contains potassium chloride and accordingly the isotope potassium-40. Potassium chloride (Sigma Aldrich) also showed significant radiation but to a certain extent less than the dietary salt.
The further experiments were directed to find out the best conditions to obtain the most accurate measurement results and to remove background radiation. For this purpose, we have used lead tube, closed at one end and thickness of the walls of around 3 mm, and put our probe (and sample) inside the Pb tube. Lead shielding helps protect from radiation because of its high molecular density and it is effective at stopping gamma rays and x-rays. Our list of samples also included quartz and ceramics and it showed that they possess small values of radiation.
One of the purposes of this STSM was to establish the better connections between the research groups from Laboratory of molecular physics and synthesis of new materials at Rudjer Boskovic Institute and host group from Universita degli Studi di Genova, in order to jointly apply for some regional and European project calls.