Search results for "Cern"
showing 10 items of 318 documents
The Nuclear astrophysics program at n_TOF (CERN)
2017
An important experimental program on Nuclear Astrophysics is being carried out at the n_TOF since several years, in order to address the still open issues in stellar and primordial nucleosynthesis. Several neutron capture reactions relevant to s-process nucleosynthesis have been measured so far, some of which on important branching point radioisotopes. Furthermore, the construction of a second experimental area has recently opened the way to challenging measurements of (n, charged particle) reactions on isotopes of short half-life. The Nuclear Astrophysics program of the n_TOF Collaboration is here described, with emphasis on recent results relevant for stellar nucleosynthesis, stellar neut…
Measurement of the 241Am neutron capture cross section at the n-TOF facility at CERN
2016
New neutron cross section measurements of minor actinides have been performed recently in order to reduce the uncertainties in the evaluated data, which is important for the design of advanced nuclear reactors and, in particular, for determining their performance in the transmutation of nuclear waste. We have measured the 241 Am(n,γ) cross section at the n TOF facility between 0.2 eV and 10 keV with a BaF2 Total Absorption Calorimeter, and the analysis of the measurement has been recently concluded. Our results are in reasonable agreement below 20 eV with the ones published by C. Lampoudis et al. in 2013, who reported a 22% larger capture cross section up to 110 eV compared to experimental …
Nuclear data activities at the n_TOF facility at CERN
2016
International audience; Nuclear data in general, and neutron-induced reaction cross sections in particular, are important for a wide variety of research fields. They play a key role in the safety and criticality assessment of nuclear technology, not only for existing power reactors but also for radiation dosimetry, medical applications, the transmutation of nuclear waste, accelerator-driven systems, fuel cycle investigations and future reactor systems as in Generation IV. Applications of nuclear data are also related to research fields as the study of nuclear level densities and stellar nucleosynthesis. Simulations and calculations of nuclear technology applications largely rely on evaluate…
The 33S(n,α)30Si cross section measurement at n TOF-EAR2 (CERN): From 0.01 eV to the resonance region
2017
The 33S(n,α)30Si cross section measurement, using 10B(n,α) as reference, at the n TOF Experimental Area 2 (EAR2) facility at CERN is presented. Data from 0.01 eV to 100 keV are provided and, for the first time, the cross section is measured in the range from 0.01 eV to 10 keV. These data may be used for a future evaluation of the cross section because present evaluations exhibit large discrepancies. The 33S(n,α)30Si reaction is of interest in medical physics because of its possible use as a cooperative target to boron in Neutron Capture Therapy (NCT).
High precision measurement of the radiative capture cross section of 238U at the n_TOF CERN facility
2016
The importance of improving the accuracy on the capture cross-section of 238U has been addressed by the Nuclear Energy Agency, since its uncertainty significantly affects the uncertainties of key design parameters for both fast and thermal nuclear reactors. Within the 7th framework programme ANDES of the European Commission three different measurements have been carried out with the aim of providing the 238U(n,γ) cross-section with an accuracy which varies from 1 to 5%, depending on the energy range. Hereby the final results of the measurement performed at the n-TOF CERN facility in a wide energy range from 1 eV to 700 keV will be presented. © The Authors, published by EDP Sciences, 2017.
The 236U neutron capture cross-section measured at the n TOF CERN facility
2016
International audience; The $^{236}$U isotope plays an important role in nuclear systems, both for future and currently operating ones. The actual knowledge of the capture reaction of this isotope is satisfactory in the thermal region, but it is considered insufficient for Fast Reactor and ADS applications. For this reason the $^{236} \text{U}(n, \gamma)$ reaction cross-section has been measured for the first time in the whole energy region from thermal energy up to 1 MeV at the n_TOF facility with two different detection systems: an array of C$_6$D$_6$ detectors, employing the total energy deposited method, and a 4$\pi$ total absorption calorimeter (TAC), made of 40 BaF$_2$ crystals. The t…
New measurement of the 242Pu(n,γ) cross section at n-TOF-EAR1 for MOX fuels: Preliminary results in the RRR
2016
The spent fuel of current nuclear reactors contains fissile plutonium isotopes that can be combined with 238U to make mixed oxide (MOX) fuel. In this way the Pu from spent fuel is used in a new reactor cycle, contributing to the long-term sustainability of nuclear energy. The use of MOX fuels in thermal and fast reactors requires accurate capture and fission cross sections. For the particular case of 242Pu, the previous neutron capture cross section measurements were made in the 70’s, providing an uncertainty of about 35% in the keV region. In this context, the Nuclear Energy Agency recommends in its “High Priority Request List” and its report WPEC-26 that the capture cross section of 242Pu…
The taint of torture and the brazilian legal system
2019
In Brazil, the practice of torture intertwines deeply with its own history. The literature on the subject has had a greater intensification on its registers during the Dictatorial Regime (1964 to 1985). In spite of the Brazilian Constitution of 1988, Brazil only makes efforts to investigate the crimes of torture of this period to comply with the provisions of the United Nations in 2011. Within this scenario, the NationalTruth Commission (Law 12.528, of November 2011) was created with the purpose of clarifying the facts and circumstances of cases concerning human rights violations, as well as the Law on Access to Information (Law 12.527 of November 2011), which have regulated the constitutio…
Organizational downsizing – an ethical versus managerial viewpoint
1999
Since the 1980s downsizing has become popular in western companies. It is a pervasive and understudied phenomenon. Downsizing means a big change in the firm’s situation. Managing change has been much researched, but often only during a growth period. So, the question of management and leadership of downsizing is a relevant and an independent research issue. This article considers the experiences of four case‐ managers who have participated in managing staff reductions in big Finnish firms. As managing downsizing can be ethically demanding, even a problematic challenge for a manager, the managers’ experiences are described and interpreted from the ethical viewpoint. The study is designed to …
Zvaigžņotā Debess: 2017, Rudens (237)
2017
Contents: “ZVAIGŽŅOTĀ DEBESS” FORTY YEARS AGO: U.Dzērvītis. Dispute on Hubble’s Constant Value (abridged) ; E.Mūkins. Ten «Venera»’s: Devices, Journeys and Results (abridged) ; DEVELOPMENTS in SCIENCE: K.Schwartz. New Discoveries in the Orion Molecular Cloud Complex ; SPACE RESEARCH and EXPLORATION: J.Jaunbergs. Salty Emanations of Enceladus ; R.Misa. Voyager: the Longest and Farthest ; OBSERVATORIES and INSTRUMENTS: J.Kuzmanis. Dragon Looks at the Sky ; K.Salmiņš. On ILRS Technical Workshop 2017 in Riga ; CONFERENCES and MEETINGS: M.Sudārs. Trends of Space Infrastructure Development in Europe ; M.Gills. Congress of European Planetary Science 2017 in Riga ; FLASHBACK: N.Cimahoviča. On Whirl…