Browsing by Author "Ngwadla Xolisani Enkosi"

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    Investigation of factors influencing radon release from different materials
    (University of the Western Cape, 2024) Ngwadla Xolisani Enkosi
    Neutrinoless double beta decays are an exotic decay process that are possible in only a few nuclei. The observation of such decays would establish the Majorana nature of neutrinos (i.e. neutrinos are their own antiparticles). Such experimental validation would indicate new physics, beyond the standard model of electroweak interactions. One promising candidate to observe such decays is the double beta transformation from 136Xe to 136Ba. This is because single beta decays to 136Cs are energetically forbidden. A potential challenge in such experiments are low-activity background from natural radioactivity. Radon is a radioactive, colorless, odorless, and tasteless gas that forms naturally from the radioactive decay of radium, and Thoron is a radioactive isotope of radon with the chemical symbol 220Rn. One such primary background is from the decays of 222Rn and 220Rn in the naturally occurring 238U and 232Th decay chains as shown in Fig. 3.4. This project aims to study the effects of Radon background in a 136Xe double beta decay experiment, with the eventual goal of obtaining solutions to suppress such background to less than 600 radon atoms. We use the Electrostatic Counter (ESC) method to measure the exhalation of 222Rn and 220Rn from the getters, specifically Pure Zirconium R-164 and Scientific and Analytical Equipment Support (SAES) pellets R-159.1. The decay of Radon produces charged Po ions, which are then directed by an electric field onto a solid-state α counter. The presence of Radium (Ra), the parent of radon, in the getters is determined by analyzing the measured decay rates of isotopes 212Po, 214Po, 216Po, and 218Po. In this work, our results show a net 222Rn emanation assay for getters, specifically Pure Zr pellets R-164 and SAES pellets R-159.1, with specific rates of Rnet = (82±23) atoms day.kg , and Rnet = (71±34) atoms day.kg , respectively. The presence of radon in mines (e.g. the Steenkampskraal mine in the Western Cape Province in South Africa) is an important indicator of the health dangers to miners of radon, a known cause of lung cancer. This thesis aims to test the exhalation of radon from rock samples from the mine. The laboratory at UWC contains a vacuum chamber that can be linked to a Radon detector (RAD7) that measures the radon exhalation in a similar way to the ESC, but in this case the radon exhalation is huge compared to the low activity measurements. The radon exhalation was studied using this setup. The Steenkampskraal mine has high natural thorium levels, resulting in high concentrations of thoron activity in the air. At a monazite seam, thoron activity concentrations are larger than 2×104 Bq m−3, with thorium exhalation aligning with these levels. While ventilation can lower thoron concentrations, it cannot completely eliminate them due to the short halflife of thoron.