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Measurement of the photoelectron-collection efficiency in noble gases and methane
Coelho, L. C. C.; Ferreira, H. M. N. B. L.; Lopes, J. A. M.; Dias, T. H. V. T.; Ferreira, L. F. R.; Santos, J. M. F. dos; Breskin, A.; Chechik, R.The photoelectron-collection efficiency from photocathodes in noble gases and methane is experimentally investigated. The ratio between the number of transmitted photoelectrons in the gas media and in vacuum is determined as a function of the applied reduced electric field E/p, where p is the gas pressure. Results are presented for He, Ne, Ar, Xe, Kr and CH4. ; http://www.sciencedirect.com/science/article/B6...
A simulation study of the effect of drift electric fields on the response of ra...
Távora, L. M. N.; Dias, T. H. V. T.; Conde, C. A. N.The effect of the presence of a drift electric field on the response of gaseous and semiconductor radiation detectors to energetic X-rays (energies from 20 to 200 keV) is investigated using the PENELOPE code to simulate the photo-absorption and the slow-down of the electrons produced in Si, Ge, and Xe gas at 1 atm. For typical drift fields, the energy deposited in the detection media is calculated taking into a...
Intrinsic limitations in the energy resolution of drift-field based radiation d...
Távora, L. M. N.; Conde, C. A. N.; Santos, F. P.; Dias, T. H. V. T.; Rachinhas, P. J. B. M.http://www.sciencedirect.com/science/article/B6TVT-4CJV8FD-4/1/9b1ae9691329367fa8f13902d8fd318d
A gas proportional-scintillation counter for x-ray spectrometry in the 0.1-3 ke...
Borges, F. I. G. M.; Santos, J. M. F. dos; Dias, T. H. V. T.; Santos, F. P.; Conde, C. A. N.Results for the energy resolution of a uniform-field gas proportional-scintillation counter are presented for the range 0.1-3 keV. A comparison with results from the literature shows that the detector is most suitable for this energy range. Examples of x-ray fluorescence pulse-height distributions from geological and industrial samples are presented. Copyright © 2004 John Wiley & Sons, Ltd. ; http://dx.doi.o...
Development of portable gas proportional scintillation counters for x-ray spect...
Santos, J. M. F. dos; Lopes, J. A. M.; Veloso, J. F. C. A.; Simões, P. C. P. S.; Dias, T. H. V. T.; Santos, F. P.; Rachinhas, P. J. B. M.A review on gas proportional scintillation counters (GPSCs) is presented. Recent achievements towards the portability of simple, inexpensive and compact GPSCs are discussed. Compensation of solid angle effects with the curved grid technique can be used to produce non-focused GPSCs with medium-sized radiation windows, at least up to 80% of the photosensor active diameter, without degradation of detector performa...
Simulation and experimental results for the detection of conversion electrons w...
Rachinhas, P. J. B. M.; Simões, P. C. P. S.; Lopes, J. A. M.; Dias, T. H. V. T.; Morgado, R. E.; Santos, J. M. F. dos; Stauffer, A. D.; Conde, C. A. N.The application of gas proportional scintillation counters (GPSC) to the detection and identification of conversion electrons in the medium energy range is investigated. Experimental and Monte Carlo results are presented for the response of a xenon GPSC, filled at atmospheric pressure, to the decay of a 109Cd source. This source emits 88.0 keV [gamma]-rays, eL=84.6 keV and eK=62.5 keV conversion electrons, as w...
Operation of gas proportional scintillation counters in a low charge multiplica...
Borges, F. I. G. M.; Santos, J. M. F. dos; Dias, T. H. V. T.; Santos, F. P.; Rachinhas, P. J. B. M.; Conde, C. A. N.The operation of a xenon filled gas proportional scintillation counter under low charge multiplication gains is discussed. It is shown that the best energy resolution for X-rays is obtained for a reduced electric field, E/p, of about 8 V cm-1 Torr-1, leading to a charge gain (for inter-grid distance of 5 mm) of about 1.05, as calculated by a Monte Carlo simulation method. A discussion is presented concerning th...
Energy resolution of xenon proportional counters: Monte Carlo simulation and ex...
Rachinhas, P. J. B. M.; Dias, T. H. V. T.; Stauffer, A. D.; Santos, F. P.; Conde, C. A. N.The gas multiplication factor M and energy resolution R of xenon gas cylindrical proportional counters are investigated experimentally and calculated theoretically using a Monte Carlo technique to simulate the growth of single-electron-initiated avalanches. A good agreement is found between calculated and experimental data. The experimental and the calculated results are presented as a function of the reduced v...
Pulse-height-spectrum distortion in xenon gaseous detectors for soft X-rays: ex...
Santos, F. P.; Santos, J. M. F. dos; Dias, T. H. V. T.; Conde, C. A. N.The results of an experimental determination of the pulse-height distortion in soft X-ray spectra in gaseous xenon detectors are presented. The study confirms previous Monte Carlo simulation results and emphasizes the importance of the electric field in the drift region in reducing spectral degradation while the effect of a strong magnetic field in the same region is shown to be negligible ; JNICT (Junta Nac...
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