Scintillation properties of N2 and CF4 and performances of a scintillating ionization chamber

International audienceIn this work, we studied the emission yields, decay times and coincidence resolving times (CRT) of two gases, nitrogen (N2) and tetrafluoromethane (CF4), used for particle detection in the context of fission products measurement. The setup was made of an ionization chamber and two photomul-tiplier tubes (PMTs) placed front-to-front on each side of the active zone of the chamber. Using the photomultiplier tubes, the number of photoelectrons (phe) converted at the photocathodes from the scintillation processes in each gas were quantified and the scintillation time spectra were recorded. An scintillation emission yield of 24 phe MeV −1 with a decay time of τ d = 2.5 ns in N2, and 225 phe MeV −1 with τ d = 6.2 ns for CF4, have been measured. With our setup , the coincidence resolving time (σ values) between the two PMTs have been measured at 1.4 ns and 0.34 ns for N2 and CF4 respectively, using alpha particles

12C nuclear reaction measurements for hadrontherapy

International audienceHadrontherapy treatments require a very high precision on the dose deposition ( 2.5% and 1-2mm) in order to keep the benefits of the precise ions' ballistic. The largest uncertainty on the physical dose deposition is due to ion fragmentation. Up to now, the simulation codes are not able to reproduce the fragmentation process with the required precision. To constraint the nuclear models and complete fragmentation cross sections databases; our collaboration has performed an experiment on May 2008 at GANIL with a 95 MeV/u 12C beam. We have measured the fluence, energy and angular distributions of charged fragments and neutrons coming from nuclear reactions of incident 12C on thick water-like PMMA targets. Preliminary comparisons between GEANT4 (G4BinaryLightIonReaction) simulations and experimental data show huge discrepancies

The GUINEVERE Project for Accelerator Driven System Physics

paper 9414International audienceThe GUINEVERE project is part of the EUROTRANS Integrated Project of the 6th EURATOM Framework Programme. It is mainly devoted to ADS on-line reactivity monitoring validation, sub-criticality determination and operational procedures (loading, start-up, shut-down, ...) as a follow-up of the MUSE experiments. The project consists in coupling a fast lead core, set-up in the VENUS reactor at SCK*CEN Mol (B), with a GENEPI neutron source under construction by CNRS. To accommodate the accelerator in a vertical coupling configuration, the VENUS building is being heightened. The fast core will be loaded with enriched Uranium and will be moderated and reflected with solid lead (zero power experiment). For the purpose of the experimental programme, the neutron source has to be operated not only in pulsed mode but also in continuous mode to investigate the current-to-flux reactivity indicator in representative conditions of a powerful ADS. In this latter mode it is also required to make short beam interruptions to have access to the neutron population decrease as a function of time: from this spectrum it will be possible to apply different analysis techniques such as "prompt decay" fitting techniques and "source jerk" techniques. Beam interruptions will be repeated at a programmable frequency to improve time spectra statistics. Different sub-criticality levels (keff=0.99, 0.97, 0.95, ...) will be investigated in order to obtain a full set of data points for the final overall validation of the methodology. This paper describes the status of the experimental facility assembling, and the foreseen experimental programme to be started

The GUINEVERE project at the VENUS facility

Proc. on CD Rom log315International audienceThe GUINEVERE project is an international project in the framework of IP-EUROTRANS, the FP6 program which aims at addressing the main issues for ADS development in the framework of partitioning and transmutation for nuclear waste volume and radiotoxicity reduction. The GUINEVERE project is carried out in the context of domain 2 of IP-EUROTRANS, ECATS, devoted to specific experiments for the coupling of an accelerator, a target and a subcritical core. These experiments should provide an answer to the questions of online reactivity monitoring, sub-criticality determination and operational procedures (loading, start-up, shutdown, …) in an ADS by 2009-2010. The project has the objective to couple a fast lead core, within the VENUS building operated by the SCK•CEN, with a neutron generator able to work in three different modes: pulsed, continuous and continuous with beam interruptions at the millisecond scale. In order to achieve this goal, the VENUS facility has to be adapted and a modified GENEPI-3C accelerator has to be designed and constructed. The paper describes the main modifications to the reactor core and facility and to the accelerator, which will be executed during the years 2008 and 2009, and the experimental programme which will start in 2009

Mesure de la température maximale des résidus chauds émis dans la réaction Ar + Au à 60 MeV/u

The work carried out in this thesis relates to the formation and decay by evaporating light particules of hot heavy residue produced in the 60 MeV per nucléon Ar + Au reaction. Using DéMoN facility has allowed to measure the initial temperature and the evaporated neutron multiplicity associated with heavy residue. Hotest observed residues sustain a 6 MeV temperature, have a 1.0 cm/ns recoil velocity, évapore about 22 neutrons and are produced with a non negligible cross section (50 mbarn). All the characteristics of this residue production are in good agreement with the predictions of a BNV calculation coupled with a statistical decay code.Le travail présenté dans cette thèse porte sur l'étude de la formation et de la désexcitation par evaporation de particules légères des noyaux chauds, les résidus, formés dans les réactions Ar + Au à 60 MeV par nucléon d'énergie de bombardement. L'utilisation du nouvel ensemble de détection DéMoN a permis d'estimer l'énergie d'excitation supportée par ces noyaux chauds à travers la mesure d'une part de leur température initiale, d'autre part de la multiplicité de neutrons évaporés qui leur est associée. Les noyaux les plus chauds observés ont une température de 6 MeV, une vitesse de recul de 1.0 cm/ns, évaporent en moyenne 22 neutrons et ont une section efficace de production d'environ 50 mbarn. La comparaison des résultats expérimentaux avec les prédictions d'un code de type B.N.V a permis d'associer la production de ces résidus à des collisions binaires dissipatives et des paramètres d'impact intermédiaires

Ligne de détection des neutrons issus du réacteur VENUS

Vue du haut de la ligne de détection des neutrons issus du réacteur VENUS du SCK-CEN de Mol en Belgique dans le cadre du projet GUINEVERE

A telescope for monitoring fast neutron sources

In the framework of nuclear waste management, highly radiotoxic long-lived fission products and minor actinides are planned to be transmuted in a sub-critical reactor coupled with an intense external neutron source. The latter source would be created by a high-energy proton beam hitting a high atomic number target. Such a new system, termed an accelerator-driven system (ADS), requires on-line and robust reactivity monitoring. The ratio between the beam current delivered by the accelerator and the reactor power level, or core neutron flux, is the basis of one method which could give access to a core reactivity change. In order to test reactivity measurement technique, some experimental programs use 14-MeV neutrons originating from the interaction of a deuteron beam with a tritium target as an external neutron source. In this case, the target tritium consumption over time precludes use of the beam current for reactivity monitoring and the external neutron source intensity must be monitored directly. A range telescope has been developed for this purpose, consisting of the assembly of a hydrogenous neutron converter and three silicon stages where the recoiling protons are detected. In this article, the pergormances of such a telescope are presented and compared to Monte-Carlo simulations