Dynamique de la désintégration pour trois types de processus nucléaires

Afin d'étudier le comportement dynamique de trois modes de désintégration nucléaire (fission froide, désintégration alpha et radioactivité par émission d'ions lourd), nous utilisons une méthode numérique basée sur les équations d'Euler-Lagrange pour obtenir la trajectoire dynamique optimale dans un espace de configuration à trois dimensions. Les degrés de liberté du système retenus sont l'élongation, la taille du col et l'assymétrie de masse. Pour le calcul de l'intégrale d'action par la méthode WKB, l'inertie du système est déterminée dans l'approximation Werner-Wheeler, et l'énergie de déformation est calculée dans le cadre du modèle de la goutte liquide pour une interaction nucléaire de type Yukawa-plus-exponentielle, étendu aux systèmes binaires avec des densités de charge différentes. Cette méthode est appliquée à l'étude de trois modes de désintégration du Pu-238 : désintégration alpha, radioactivité par émission du Si-32 et fission froide avec, pour fragment léger, le Mo-104

The ALTO project at IPN Orsay

In order to probe neutron rich radioactive noble gases produced by photo-fission, a PARRNe1 experiment (Production d'Atomes Radioactifs Riches en Neutrons) has been carried out at CERN. The incident electron beam of 50 MeV was delivered by the LIL machine: LEP Injector Linac. The experiment allowed to compare under the same conditions two production methods of radioactive noble gases: fission induced by fast neutrons and photo-fission. The obtained results show that the use of the electrons is a promising mode to get intense neutron rich ion beams. Thereafter, the success of this photo-fission experiment, a conceptual design for the installation at IPN Orsay of a 50 MeV electron accelerator close to the PARRNe-2 device has been worked out: ALTO Project. This work has started within a collaboration between IPNO, LAL and CERN groups.Comment: 14 pages, pdf file, International School-Seminar on Heavy-Ion Physics 7 (2002

Carbon nanotube forests as top electrode in electroacoustic resonators

We grow carbon nanotube forests on piezoelectric AlN films and fabricate and characterize nanotube-based solidly mounted bulk acoustic wave resonators employing the forests as the top electrode material. The devices show values for quality factor at anti-resonance of ∼430, and at resonance of ∼100. The effective coupling coefficient is of ∼6%, and the resonant frequencies are up to ∼800 MHz above those observed with metallic top electrodes. AlN promotes a strong catalyst-support interaction, which reduces Fe catalyst mobility, and thus enforces the growth of forests by the base growth mechanism.This work was partially supported by the European Commission through the project GRAFOL and the COST action IC1208 and by the Ministerio de Economía y Competitividad del Gobierno de España through project MAT2013-45957.This is the accepted manuscript. The final version is available at http://scitation.aip.org/content/aip/journal/apl/107/13/10.1063/1.4932197

Gravimetric and biological sensors based on SAW and FBAR technologies

This presentation will describe the development of Gravimetric and Biological Sensors based on SAW and FBAR Technologies. The SAW devices were fabricated on polycrystalline ZnO thin films deposited using both standard R.F. sputtering techniques and a novel High Target Utilisation Sputtering System (HiTUS). This system ensures that we can produce the low stress films at the high deposition rates necessary for such structures to operate efficiently. However in order to further improve the sensitivity of our sensors we have also investigated the use of Thin Film Bulk Acoustic Resonators (FBARs) . We will describe standard gravimetric sensors based on such material and also gravimetric sensors for use in liquid environments through the use of inclined c-axis ZnO material. The talk will conclude with a discussion of dual mode thin film FBARs for parallel sensing of both mass loading and temperature

Present Status and Future Programs of the n_TOF Experiment

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 neutron time-of-flight facility n_TOF at CERN, Switzerland, operational since 2001, delivers neutrons using the Proton Synchrotron (PS) 20 GeV/c proton beam impinging on a lead spallation target. The facility combines a very high instantaneous neutron flux, an excellent time of flight resolution due to the distance between the experimental area and the production target (185 meters), a low intrinsic background and a wide range of neutron energies, from thermal to GeV neutrons. These characteristics provide a unique possibility to perform neutron-induced capture and fission cross-section measurements for applications in nuclear astrophysics and in nuclear reactor technology.The most relevant measurements performed up to now and foreseen for the future will be presented in this contribution. The overall efficiency of the experimental program and the range of possible measurements achievable with the construction of a second experimental area (EAR-2), vertically located 20 m on top of the n_TOF spallation target, might offer a substantial improvement in measurement sensitivities. A feasibility study of the possible realisation of the installation extension will be also presented

The 33S(n,α)30Si cross section measurement at n-TOF-EAR2 (CERN) : From 0.01 eV to the resonance region

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)

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

Measurement of 73 Ge(n,γ) cross sections and implications for stellar nucleosynthesis

© 2019 The Author(s). Published by Elsevier B.V.73 Ge(n,γ) cross sections were measured at the neutron time-of-flight facility n_TOF at CERN up to neutron energies of 300 keV, providing for the first time experimental data above 8 keV. Results indicate that the stellar cross section at kT=30 keV is 1.5 to 1.7 times higher than most theoretical predictions. The new cross sections result in a substantial decrease of 73 Ge produced in stars, which would explain the low isotopic abundance of 73 Ge in the solar system.Peer reviewe

Characterization of the n-TOF EAR-2 neutron beam

The experimental area 2 (EAR-2) at CERNs neutron time-of-flight facility (n-TOF), which is operational since 2014, is designed and built as a short-distance complement to the experimental area 1 (EAR-1). The Parallel Plate Avalanche Counter (PPAC) monitor experiment was performed to characterize the beam prole and the shape of the neutron 'ux at EAR-2. The prompt γ-flash which is used for calibrating the time-of-flight at EAR-1 is not seen by PPAC at EAR-2, shedding light on the physical origin of this γ-flash