Profesorado de enseñanza básica: características socioprofesionales, formación TIC y efectos en su práctica (Algarbe-Portugal)

En las últimas décadas países como Portugal han realizado un esfuerzo económico importante para poder introducir las TIC en sus escuelas. El objetivo que nos proponemos con este trabajo es identificar las características socio-profesionales del profesorado del primer ciclo de enseñanza básica de la región del Algarbe (Portugal) y su relación con el tiempo de uso de las TIC en sus aulas, entre otros factores. La metodología utilizada es cuantitativa siendo el instrumento principal el cuestionario. La muestra quedó constituida por 156 docentes de la región. Entre los resultados encontramos que las docentes tienen una mayor frecuencia semanal de uso de las TIC que sus compañeros varones y que cuanta más formación se cursa más horas de implementación de las TIC en el aula se produce. finalmente, concluimos con una serie de reflexiones sobre la formación y la integración de las TIC que pueden servir a prácticos, teóricos e instituciones.info:eu-repo/semantics/publishedVersio

Design study for a new spallation target of the n_TOF facility at CERN

The n_TOF facility is a time of flight spectrometer dedicated to measuring neutron capture and fission cross sections. The neutron source consists on a lead target bombarded by a high energetic proton beam. After finishing a successful period of data taking by the end of 2004, it has been decided to upgrade the neutron spallation source with a cladded target. In this study, Monte Carlo simulations are reported for the assessment and comparison of the neutron and gamma fluxes from different target configurations. In addition, the plans for a second vertical measuring station with a flight path of 20 m above the spallation target have been considered in the simulations as well. Results for the energy deposition and the target heating are also presented

Ni-62(n,gamma) and Ni-63(n,gamma) cross sections measured at the n_TOF facility at CERN

The cross section of the Ni-62(n,gamma) reaction was measured with the time-of-flight technique at the neutron time-of-flight facility n_TOF at CERN. Capture kernels of 42 resonances were analyzed up to 200 keV neutron energy and Maxwellian averaged cross sections (MACS) from kT = 5-100 keV were calculated. With a total uncertainty of 4.5%, the stellar cross section is in excellent agreement with the the KADoNiS compilation at kT = 30 keV, while being systematically lower up to a factor of 1.6 at higher stellar temperatures. The cross section of the Ni-63(n,gamma) reaction was measured for the first time at n_TOF. We determined unresolved cross sections from 10 to 270 keV with a systematic uncertainty of 17%. These results provide fundamental constraints on s-process production of heavier species, especially the production of Cu in massive stars, which serve as the dominant source of Cu in the solar system.Peer reviewedFinal Accepted Versio

Measurement of the 12C(n,p)12B cross section at n-TOF at CERN by in-beam activation analysis

The integral cross section of the 12C(n,p)12B reaction has been determined for the first time in the neutron energy range from threshold to several GeV at the n-TOF facility at CERN. The measurement relies on the activation technique with the β decay of 12B measured over a period of four half-lives within the same neutron bunch in which the reaction occurs. The results indicate that model predictions, used in a variety of applications, are mostly inadequate. The value of the integral cross section reported here can be used as a benchmark for verifying or tuning model calculations.Peer reviewedFinal Accepted Versio

High accuracy 234U(n,f) cross section in the resonance energy region

New results are presented of the 234U neutron-induced fission cross section, obtained with high accuracy in the resonance region by means of two methods using the 235U(n,f) as reference. The recent evaluation of the 235U(n,f) obtained with SAMMY by L. C. Leal et al. (these Proceedings), based on previous n-TOF data [1], has been used to calculate the 234U(n,f) cross section through the 234U/235U ratio, being here compared with the results obtained by using the n-TOF neutron flux

Measurement of the neutron capture cross section of the s-only isotope 204Pb from 1 eV to 440 keV

The neutron capture cross section of 204Pb has been measured at the CERN n_TOF installation with high resolution in the energy range from 1 eV to 440 keV. An R-matrix analysis of the resolved resonance region, between 1 eV and 100 keV, was carried out using the SAMMY code. In the interval between 100 keV and 440 keV we report the average capture cross section. The background in the entire neutron energy range could be reliably determined from the measurement of a 208Pb sample. Other systematic effects in this measurement could be investigated and precisely corrected by means of detailed Monte Carlo simulations. We obtain a Maxwellian average capture cross section for 204Pb at kT=30 keV of 79(3) mb, in agreement with previous experiments. However our cross section at kT=5 keV is about 35% larger than the values reported so far. The implications of the new cross section for the s-process abundance contributions in the Pb/Bi region are discussed.Comment: 8 pages, 3 figures, article submitted to Phys. Rev.

Measurements of high-energy neutron-induced fission of (nat)Pb and (209)Bi

This is an Open Access article distributed under the terms of the Creative Commons Attribution-Noncommercial License 3.0, which permits unrestricted use, distribution, and reproduction in any noncommercial medium, provided the original work is properly citedThe CERN Neutron Time-Of-Flight (n_TOF) facility is well suited to measure low cross sections as those of neutron-induced fission in subactinides. The cross section ratios of (nat)Pb and (209)Bi relative to (235)U and (238)U were measured using PPAC detectors and a fragment coincidence method that allows us to identify the fission events. The present experiment provides first results for neutron-induced fission up to 1 GeV. Good agreement is found with previous experimental data below 200 MeV. The comparison with proton-induced fission indicates that the limiting regime where neutron-induced and proton-induced fission reach equal cross sections is close to 1 GeV

Neutron cross-sections for advanced nuclear systems : The n-TOF project at CERN

© Owned by the authors, published by EDP Sciences, 2014 This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedThe study of neutron-induced reactions is of high relevance in a wide variety of fields, ranging from stellar nucleosynthesis and fundamental nuclear physics to applications of nuclear technology. In nuclear energy, high accuracy neutron data are needed for the development of Generation IV fast reactors and accelerator driven systems, these last aimed specifically at nuclear waste incineration, as well as for research on innovative fuel cycles. In this context, a high luminosity Neutron Time Of Flight facility, n-TOF, is operating at CERN since more than a decade, with the aim of providing new, high accuracy and high resolution neutron cross-sections. Thanks to the features of the neutron beam, a rich experimental program relevant to nuclear technology has been carried out so far. The program will be further expanded in the near future, thanks in particular to a new high-flux experimental area, now under construction.Peer reviewedFinal Published versio

238U(n, γ) reaction cross section measurement with C 6D6 detectors at the n-TOF CERN facility

This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedThe radiative capture cross section of 238U is very important for the developing of new reactor technologies and the safety of existing ones. Here the preliminary results of the 238U(n,γ) cross section measurement performed at n-TOF with C6D6 scintillation detectors are presented, paying particular attention to data reduction and background subtraction.Peer reviewe

Measurement of the radiative neutron capture cross section of 206Pb and its astrophysical implications

The (n, gamma) cross section of 206Pb has been measured at the CERN n_TOF facility with high resolution in the energy range from 1 eV to 600 keV by using two optimized C6D6 detectors. In the investigated energy interval about 130 resonances could be observed, from which 61 had enough statistics to be reliably analyzed via the R-matrix analysis code SAMMY. Experimental uncertainties were minimized, in particular with respect to (i) angular distribution effects of the prompt capture gamma-rays, and to (ii) the TOF-dependent background due to sample-scattered neutrons. Other background components were addressed by background measurements with an enriched 208Pb sample. The effect of the lower energy cutoff in the pulse height spectra of the C6D6 detectors was carefully corrected via Monte Carlo simulations. Compared to previous 206Pb values, the Maxwellian averaged capture cross sections derived from these data are about 20% and 9% lower at thermal energies of 5 keV and 30 keV, respectively. These new results have a direct impact on the s-process abundance of 206Pb, which represents an important test for the interpretation of the cosmic clock based on the decay of 238U.Comment: 11 pages, 8 figures, paper to be submitted to Phys. Rev.