J.I. Golzarri

Angular distribution of fusion products and x rays emitted by a small dense plasma focus machine

Time integrated measurements of the angular distributions of fusion products and x rays in a small dense plasma focus machine are made inside the discharge chamber, using passive detectors. The machine is operated at 37kV with a stored energy of 4.8kJ and a deuterium filling pressure of 2.75torr. Distributions of protons and neutrons are measured with CR-39 Lantrack® nuclear track detectors, on 1.8×0.9cm2 chips, 500μm thick. A set of detectors was placed on a semicircular Teflon® holder, 13cm away from the plasma column, and covered with 15μm Al filters, thus eliminating tritium and helium-3 ions, but not protons and neutrons. A second set was placed on the opposite side of the holder, eliminating protons. The angular distribution of x rays is also studied within the chamber with TLD-200 dosimeters. While the neutron angular distributions can be fitted by Gaussian curves mounted on constant pedestals and the proton distributions are strongly peaked, falling rapidly after ±40°, the x-ray distributions show...

Establishment of a radioactive contamination index in seawater from the Gulf and Pacific coasts in Mexico

This paper intends to establish one radioactive contamination index in seawater based on the relation A1/A2, where A1 is the radioactivity due to the contaminant radioisotope 137Cs and A2 is the radioactivity due to the natural radioisotope 40K, both expressed either as Bq/l in seawater or Bq/g in sea salt. At a second step, the same volumes of marine sediments were detected, but in this case results were expressed as Bq/g (dry basis) in order to find an index of radioactive contamination which remains more or less unchanged in seabed. The first results obtained show the adopted units are suitable for proposed contamination index, which might be useful to measure the extent and importance of radioactive contamination in every sea region of the planet. Therefore, it is a proposal for a direct measurement at greater range, which could be compared with punctual results all over the world to avoid the panic.

Measurements of radon levels inside Mexican caves

Abstract Living animal species on earth have been exposed to environmental radon from the very beginning of time. The effects of radiation, combined with other natural parameters such as temperature, humidity, salt contents, etc., have most likely influenced the evaluation of different species. Thus, it is important to know and to evaluate the radon levels, among other radioactive elements present in enclosed environments such as caves (Gammage, 1990; Hunyadi et al, 1991), especially since those caves were also the dwellings and refuge of the predecessor of man. In this work we present radon level measurements inside some caves with vestiges of ancient inhabitats and some recently discovered natural caves, using Nuclear Track Detectors.

Radioactivity in Marine Salts and Sediments

Radioactivity is a natural phenomenon always taking place in our planet and in the whole universe. In the very beginning of matter, which it is evolving till now, some radioactive isotopes were created, among others, to form either in a mixture or as a single one, the ninety material units known as elements, which combined in a huge number of ways represent what is called matter, nature and universe. This sort of radioisotopes are, for example, 40K, 50V and 87Rb, as well as every radioisotope found from bismuth to uranium, all of them radioactive, classified by Mendeleieff according their atomic number and weight in the Periodic Chart. These natural radioisotopes are called Primordial and are shown in Table 1.

Nuclear track pseudocoloring by illumination wavefront angle variation

Abstract A real time pseudocoloring technique for nuclear tracks on CR-39 detectors is proposed. The technique basis is track illumination from different directions with different colors. The track themselves diffusely reflect the colored light, giving color images that, when seen simultaneously, allow easy identification and measurements.

The radiochemical and chemical characterization of marine sediments taken up from Cuba's northern and southern littoral

Radioactive contamination factor (RCF) has been proposed as a suitable unit to measure the magnitude of radioactive contamination at global scale, caused mainly by more than 2000 nuclear explosion tests performed during the 1945–1965 period. It is obtained as percentage of contaminant radioactivity (137Cs) compared to natural radioactivity (40K), both expressed in Bq/g of marine sediments conditioned in Marinelli containers and detected in both NaI(Tl) and HPGe detectors. Till now, some results have been obtained from samples taken up in Pacific and Gulf of Mexico coast. At present, additional results were obtained in samples from Cuba North and South coast, including nuclear tracks from α particles. Also, the total oxides content and trace metal content were determined by WD-XRF and ICP-MS respectively These results have been as clear and consistent that previous ones, and it seems to confirm that proposed method is simple and suitable to be enlarged to some other areas of the planet.

URANIUM DETERMINATION IN WATER USING SOLID STATE NUCLEAR TRACK DETECTORS

ABSTRACT A method for detecting low concentrations of Uranium in water is presented in this work. A CR-39 is used as detector, and as a process a consecutive preetching and an electrochemical etching. Concentration measurement of 1 p.p.m. are obtained with out the requirement of a neutron flux. The results show high sensitivity and reproducibility, with a linear response as a function of uranium contents in the water. Therefore, this technique results suitable for measuring of uranium concentrations in rivers lakes, water springs, etc.

A Preliminary Study of the Radon and Thoron Concentration Distribution inside a Cellar Using Nuclear Track Detectors (NTDs)

In this paper we present the preliminary results of a study of the radon and thoron (222Rn and 220Rn) and their progeny, concentration distribution inside the cellar as recorded by a 200×200 cm mesh of CR-39 bare detectors. The mesh comprised one hundred and sixty two 1.9×0.9 cm CR-39 (Lantrack®) polycarbonate chips. The distribution of radon and thoron shows a complex pattern. Both sides of the mesh displayed a significant concentration gradient of radon and thoron levels, with a maximum near to the top and bottom of the detection grid, and minimum around the center. This spatially inhomogeneous distribution recorded by the detectors could be the result of the distance from the walls, gas kinematics, diffusion coefficient, room geometrical configuration, aerosol behaviors, and objects inside the room, among others. It suggests that the analysis of these complex distribution patterns may be applicable for the estimation and evaluation of indoor radon concentration levels, considering each particular location and characteristics of the place.

Comparative studies of polymer materials as radon protection coating

Abstract The control of indoor radon levels has become a public health issue (Espinosa et al, 1991; Hakl et al, 1991). New regulations and architectural designs are being developed for residential areas, homes and public buildings. Radon concentration is directly related to the ratio between energy conservation and open-window ventilation. A large percentage of the accumulated radon comes via its infiltration through walls and floors (Cohtern et al, 1987). Some possible solutions to the problem involve: 1) The use of thermally-insulated boards which still allow the passage of radon to the outside; and 2) the use of coatings to reduce the infiltration through the wall and floors.

Analysis of different Mexican polymers as solid state nuclear track detectors

Abstract The present importance, the multiple applications and the future expansions of the SSNTDs, inspired us to start with this research. A study of different types of commercial Mexican polymers is presented. The response to fission fragments and alpha radiation were analysed, looking for their possible applications as dosimeters. The technical conditions for chemical etching were determined as well.