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Environmental Alpha Radiation from the Soil at a Prehispanic Ancient Sacred Site in Lima, Perú

Díaz Félix, Liza Rafael, Rojas Jhonny, Pereyra Patrizia, Lopez Maria Elena, Palacios Daniel, Sajo-Bohus Laszlo, Benites Santiago

Ecological Engineering & Environmental Technology

2023

Vol. 24, iss. 9

291--299

In the present work, we investigate the concentration of radon and its alpha-emitting progeny at the archaeological site of Huaca 20 in Lima, Peru. The site holds significant cultural and historical importance as an ancient pre-Inca ruin, providing valuable insights into the lives and rituals of its former inhabitants. We quantified the radon levels accurately with passive CR-39TM detectors deployed within specially designed chambers at the site for 28 days. In a controlled laboratory environment, we processed the detectors afterward, examining and analyzing the resulting tracks using advanced microscopy and the ImageJ analysis software. The ground-level concentration of radon and its alpha-emitting progeny was determined, revealing elevated levels ranging from 2.4 ± 0.6 to 8.9 ± 0.9 (kBq/m3 ). These findings underscore the unique presence of radon at Huaca 20 and highlight the potential impact on microorganisms at ground level. Likewise, these results can contribute to studies on the radiological risks faced by visitors, excavators and archaeologists. Finally, we show the spatial distribution of radon concentrations within the site by creating an iso-concentration map. The iso-concentration map reveals a relation between areas with elevated radon levels and the good preservation of funerary contexts.

Investigation on polycarbonate nanomembrane production based on alpha particles irradiation

Ziaie F., Shadman M., Yeganegi S., Mollaie A., Majdabadi A.

Nukleonika

2009

Vol. 54, No. 3

157-161

Track-etched membranes were prepared in the Dosimetry Laboratory of Agricultural, Medical and Industrial Research School by exposing polycarbonate (PC) films with a thickness of about 20 μm to alpha particles emitted from 241Am followed by chemical etching in sodium hydroxide (NaOH) at different temperatures and solution concentrations. The PC films were prepared using the method of chemical solving, forming and drying in a vacuum oven. The etching rate of PC was related to the concentration of etching solution, etching temperature and time. Therefore, a series of track-etched membranes were produced using different etching parameters. The relation between the etching rate and the etching parameters were established from experimental data and can be used to control the average pore sizes of the PC track-etched membrane. The pore sizes and their structures were studied by an optical microscope (OM) and a scanning electron microscope (SEM) and the obtained results indicated that the pores across the PC films are cylindrically shaped.

Development of crystals based on cesium iodide for measurements of gamma radiation and alpha particles

Pereira M. C. C., Filho T. M., Hamada M. M.

Nukleonika

2009

Vol. 54, No. 3

151-155

During the past 50 years, scintillators have been among the most important nuclear radiation detectors. Inorganic scintillators are widely used in experimental nuclear physics, high energy physics, nuclear medicine, nuclear tomography, environmental studies and many other fields of use. Scintillation crystals based on cesium iodide (CsI) are matters of relatively low hygroscopy, high atomic number, easy handling and low cost, characteristics that favor their use as radiation detectors. In this work, the growth of pure CsI crystals, CsI:Br and CsI:Pb, using the Bridgman technique, is described. Ions of divalent lead (Pb2+) doped in the crystal structures are efficient emission centers and their application as scintillators is still the reason for intensive studies. Recently, promising results have been found for crystals of CsI doped by bromine (Br) for their use as radiation detectors. The concentration of the bromine doping element (Br) was studied in the range from 1.5 × 10–1 M to 10–2 M and the lead (Pb) in the range from 10–2 M to 5 × 10–4 M. To evaluate the scintillators developed, systematic measurements were carried out for luminescence emission and luminescence decay time for gamma radiation, Vickers microhardness assays, and analysis of crystals response to the gamma radiation, in the energy range from 350 keV to 1330 keV, and alpha particles from a 241Am source, with energy of 5.54 MeV. The obtained values for luminescence decay time for CsI:Br and CsI:Pb crystals, were from 13 to 19 ns.