Browsing by Author "Neves, P. N. B."
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- Experimental measurement of the mobilities of atomic and dimer Ar, Kr, and Xe ions in their parent gasesPublication . Neves, P. N. B.; Conde, C. A. N.; Távora, L. M. N.A new experimental technique for measuring the mobilities of positive ions in their parent gases is presented. The technique was applied to the rare gases, Ar, Kr, and Xe, and, for pressures typically below 10 Torr, two different types of positive ions were observed. The reduced mobilities of these ions in their parent gases were measured as a function of E/N, the ratio of the electric field strength to the gas number density, at a temperature of 300±1 K. The results were compared with others available in the literature and the two ions were identified as being the atomic and the dimer rare gas ions. The results are in good agreement with those from other authors. Space charge and impurities effects are discussed.
- Experimental measurement of the mobilities of atomic, Ne+, and dimer, Ne2+, ions in NePublication . Garcia, A. N. C.; Trindade, A. M. F.; Oliveira, T. D. P.; Neves, P. N. B.; Barata, J. A. S.; Távora, L. M. N.; Dias, T. H. V. T.; Borges, F. I. G. M.; Conde, C. A. N.We measured the reduced mobilities of the atomic, Ne+, and dimer, Ne2+, ions in Ne, under different pressures and reduced electric fields, at 300 K. The value obtained for the atomic ion, 4.1 cm2V1 s1, is in good agreement with other values published in the scientific literature. The value obtained for the mobility of the dimer ion, 7.3 cm2 V1 s1, is not in accordance with other published data. We discuss the most probable sources of error.
- Measuring the mobilities of the ions formed in P-10 mixturesPublication . Neves, P. N. B.; Trindade, A. M. F.; Barata, J. A. S.; de Oliveira Pegado de Noronha E Távora, Luís Miguel; Conde, C. A. N.We measured the reduced mobilities (k0 in cm2V -1s-1) of the ions that are formed in P-10 mixtures under different pressures and various reduced electric fields. Two types of ions were identified. We then used the extrapolated values of k0 when E/N→0 (2.41 and 2.76 cm2V-1s-1), the Langevin formula and the Blanc's law, to calculate the masses of these ions. Calculations indicate that the two ions have masses of 41 a.u. and 25 a.u., respectively. We propose hypothesis to explain the nature and origin of those ions.
- Photopeak shift effects due to the drift electric field in high pressure xenon detectorsPublication . Neves, P. N. B.; Barata, J. A. S.; Távora, L. M. N.; Dias, T. H. V. T.; Borges, F. I. G. M.; Conde, C. A. N.The photopeak shift in High Pressure Xe (HPXe) gamma ray detectors due to the energy acquired/lost by the photoelectric and Compton electrons, from the electric field applied in the drift region, is calculated using the PENELOPE code for gamma rays from several radioactive sources. The implications of this effect in HPXe detectors are discussed, namely for TPCs for double beta decay of 136 Xe studies.
- The X++2X→X2++X reaction rate constant for Ar, Kr and Xe, at 300 KPublication . Neves, P. N. B.; Conde, C. A. N.; Távora, L. M. N.The X++2X → X+2X- reaction rate constants were measured for Ar, Kr and Xe, at 300 K, using a new experimental technique. The results for Ar, kAr=(1.2 ± 0.2) × 10 -31 cm6 Kr, kKr=(2.1 ± 0.9) × 10-31 cm and Xe, kxe=(1.48 ± 0.18) x 10 -31 cm6S-1 are discussed and compared with those of other authors using different techniques.