Strength of the EpE_{\text{p}}=1.842 MeV resonance in the 40^{40}Ca(p,γ\gamma)41^{41}Sc reaction revisited

The strength of the $E_{\rm p} = 1.842$ MeV resonance in the $^{40}$Ca(p,$\gamma$)$^{41}$Sc reaction is determined with two different methods: First, by an absolute strength measurement using calcium hydroxide targets, and second, relative to the well-determined strength of the resonance triplet at $E_\alpha$ = 4.5 MeV in the $^{40}$Ca($\alpha$,$\gamma$)$^{44}$Ti reaction. The present new value of $\omega\gamma=(0.192\pm0.017)$ eV is 37% (equivalent to $3.5\sigma$) higher than the evaluated literature value. In addition, the ratio of the strengths of the 1.842 MeV $^{40}$Ca(p,$\gamma$)$^{41}$Sc and 4.5 MeV $^{40}$Ca($\alpha$,$\gamma$)$^{44}$Ti resonances has been determined to be $0.0229\pm0.0018$. The newly corrected strength of the 1.842-MeV resonance can be used in the future as a normalization point for experiments with calcium targets.Comment: Submitted to Phys. Rev.

The resonance triplet at E_alpha = 4.5 MeV in the 40Ca(alpha,gamma)44Ti reaction

The 40Ca(alpha,gamma)44Ti reaction is believed to be the main production channel for the radioactive nuclide 44Ti in core-collapse supernovae. Radiation from decaying 44Ti has been observed so far for two supernova remnants, and a precise knowledge of the 44Ti production rate may help improve supernova models. The 40Ca(alpha,gamma)44Ti astrophysical reaction rate is determined by a number of narrow resonances. Here, the resonance triplet at E_alpha = 4497, 4510, and 4523 keV is studied both by activation, using an underground laboratory for the gamma counting, and by in-beam gamma spectrometry. The target properties are determined by elastic recoil detection analysis and by nuclear reactions. The strengths of the three resonances are determined to omega gamma = (0.92+-0.20), (6.2+-0.5), and (1.32+-0.24) eV, respectively, a factor of two more precise than before. The strengths of this resonance triplet may be used in future works as a point of reference. In addition, the present new data directly affect the astrophysical reaction rate at relatively high temperatures, above 3.5 GK.Comment: 12 pages, 11 figures; submitted to Phys. Rev.

Inelastic scattering of fast neutrons from 56

The inelastic scattering of fast neutrons on 56Fe was investigated in different manners at the neutron time-of-flight facility nELBE. The scattering cross section was determined via the measurement of the γ-ray production and by means of a kinematically complete double time-of-flight method. In a further measurement the γ-ray angular distribution was determined to correct the measured cross sections for anisotropy. The resulting inelastic scattering cross section determined from the photo production cross sections is in very good agreement with evaluations and previous measurements. In contrast, the result of the double time-of-flight measurement is about 10% lower than these data, giving a hint to neutron-γ-ray angular correlations in the process of inelastic neutron scattering

First Results of the 140^{140}Ce(n,γ)141^{141}Ce Cross-Section Measurement at n_TOF

An accurate measurement of the $^{140}$Ce(n,γ) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the $^{140}$Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in $^{140}$Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the $^{140}$Ce Maxwellian-averaged cross-section

First Results of the 140^{140}Ce(n,γ)141^{141}Ce Cross-Section Measurement at n_TOF

An accurate measurement of the $^{140}$Ce(n,γ) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the $^{140}$Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in $^{140}$Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the $^{140}$Ce Maxwellian-averaged cross-section

Discutindo a educação ambiental no cotidiano escolar: desenvolvimento de projetos na escola formação inicial e continuada de professores

A presente pesquisa buscou discutir como a Educação Ambiental (EA) vem sendo trabalhada, no Ensino Fundamental e como os docentes desta escola compreendem e vem inserindo a EA no cotidiano escolar., em uma escola estadual do município de Tangará da Serra/MT, Brasil. Para tanto, realizou-se entrevistas com os professores que fazem parte de um projeto interdisciplinar de EA na escola pesquisada. Verificou-se que o projeto da escola não vem conseguindo alcançar os objetivos propostos por: desconhecimento do mesmo, pelos professores; formação deficiente dos professores, não entendimento da EA como processo de ensino-aprendizagem, falta de recursos didáticos, planejamento inadequado das atividades. A partir dessa constatação, procurou-se debater a impossibilidade de tratar do tema fora do trabalho interdisciplinar, bem como, e principalmente, a importância de um estudo mais aprofundado de EA, vinculando teoria e prática, tanto na formação docente, como em projetos escolares, a fim de fugir do tradicional vínculo “EA e ecologia, lixo e horta”.Facultad de Humanidades y Ciencias de la Educació

Inelastic scattering of fast neutrons from

The inelastic scattering of fast neutrons on 56Fe was investigated in different manners at the neutron time-of-flight facility nELBE. The scattering cross section was determined via the measurement of the γ-ray production and by means of a kinematically complete double time-of-flight method. In a further measurement the γ-ray angular distribution was determined to correct the measured cross sections for anisotropy. The resulting inelastic scattering cross section determined from the photo production cross sections is in very good agreement with evaluations and previous measurements. In contrast, the result of the double time-of-flight measurement is about 10% lower than these data, giving a hint to neutron-γ-ray angular correlations in the process of inelastic neutron scattering