RESUMO
Sources of enriched (240)Pu were prepared by vacuum evaporation on quartz substrates. High-resolution alpha-particle spectrometry of (240)Pu was performed with high statistical accuracy using silicon detectors and with low statistical accuracy using a bolometer. The alpha-particle emission probabilities of six transitions were derived from the spectra and compared with literature values. Additionally, some alpha-particle emission probabilities were derived from gamma-ray intensity measurements with a high-purity germanium detector. The alpha-particle emission probabilities of the three main transitions at 5168.1, 5123.6 and 5021.2 keV were derived from seven aggregate spectra analysed with five different fit functions and the results were compatible with evaluated data. Two additional weak peaks at 4863.5 and 4492.0 keV were fitted separately, using the exponential of a polynomial function to represent the underlying tailing of the larger peaks. The peak at 4655 keV could not be detected by alpha-particle spectrometry, while gamma-ray spectrometry confirms that its intensity is much lower than expected from literature.
RESUMO
This work presents a high performance procedure for the unfolding of alpha particle spectra based on genetically estimated initial parameters. The process starts with the search for a globally optimized set of fitting parameters from a population of randomly generated solutions. The solution found with the genetic algorithm is then transferred to a Levenberg-Marquardt procedure in order to calculate the covariance matrix for the fit. The proposed method provides the set of final parameters and their associated standard deviation. Several fitted spectra demonstrate the effectiveness of the proposed method in searching for and finding initial conditions in a fast and automated process.
