[en] The purpose of this thesis is to study the kaon photoproduction off a proton (γp → K⁺Λ,γp → K⁺Σ⁰, γp → K⁰Σ⁺), with a photon energy between 0.9 and 2.1 GeV. We use an isobaric model where the amplitudes are computed with Feynman diagrams. The insertion of nucleonic resonances with spin 3/2 and 5/2 is necessary to improve the existing models beyond 1.5 GeV. This step is also necessary to extend the elementary process of photoproduction to electroproduction where the data have been taken with photon energies above 2.0 GeV. The parameters of our models are the coupling constants which appear at each Feynman diagram vertex. They are determined by fitting our models to the experimental data (cross sections, polarization asymmetries). Before performing the minimization we drew some informations about coupling constants from mesonic and electromagnetic decays, and from SU(3) and SU(6) symmetries. In conclusion, the models developed here reproduce the experimental data (E_γ ≤ 2.0 GeV) and the two main coupling constants are in good agreement with broken SU(3)-symmetry predictions. (author)

[en] The spallation reactions are a type of nuclear reaction which occur in space by interaction of the cosmic rays with interstellar bodies. The first spallation reactions induced with an accelerator took place in 1947 at the Berkeley cyclotron (University of California) with 200MeV deuterons and 400MeV alpha beams. They highlighted the multiple emission of neutrons and charged particles and the production of a large number of residual nuclei far different from the target nuclei. In the same year, R. Serber described the reaction in two steps: a first and fast one with high-energy particle emission leading to an excited remnant nucleus, and a second one, much slower, the de-excitation of the remnant. In 2010 IAEA organized a workshop to present the results of the most widely used spallation codes within a benchmark of spallation models. If one of the goals was to understand the deficiencies, if any, in each code, one remarkable outcome points out the overall high-quality level of some models and so the great improvements achieved since Serber. Particle transport codes can then rely on such spallation models to treat the reactions between a light particle and an atomic nucleus with energies spanning from few tens of MeV up to some GeV. An overview of the spallation reactions modeling is presented in order to point out the incomparable contribution of models based on basic physics to numerous applications where such reactions occur. Validations or benchmarks, which are necessary steps in the improvement process, are also addressed, as well as the potential future domains of development. Spallation reactions modeling is a representative case of continuous studies aiming at understanding a reaction mechanism and which end up in a powerful tool. (orig.)

[en] In this paper we have studied the He⁶ production in the two-stage system (neutron converter - ion production targets) for the EURISOL-DS needs. Following the baseline parameters, we have worked in more detail on thermal and neutron flux observables for a system composed of a Tungsten or Tantalum converter, surrounded by a BeO target. Incident proton beam has been fixed to 1 GeV with a 100 kW power. We have confirmed that this initial configuration does not allow reaching the desired He⁶ production rate in the target, i.e. we have obtained 2*10¹³ ions/s compared to 2*10¹⁴ ions/s. A number of geometry, material and incident beam parameters have been optimized with the goal to increase the production rate by a factor of 10. For this purpose we have used the MCNPX code. We have showed that a gain factor of 5 compared to the initial reference configuration can be obtained, i.e. the final He⁶ production rate is about 1*10¹⁴ He⁶/s. We add that further increase in production of He⁶ ions could be achieved 'simply' by increasing the external BeO target radius, i.e. by increasing the volume of production target. On the other hand, such a geometry modification would certainly induce He⁶ on-line extraction losses, i.e. the final increase in available He⁶ ion beam is not guaranteed. Additional studies on the extraction efficiency should be done shortly

[en] We have used MCNPX coupled to CINDER to estimate the production of radioactive nuclides in the EURISOL 4 MW liquid mercury target during a 40 years'lifetime of the installation. The calculations have been done with different intra-nuclear cascade and fission evaporation model combinations. A benchmark exercise has allowed a better understanding of differences seen between these models for the creation of tritium and fission products. To obtain a realistic production yield for tritium gas in proton induced spallation reactions, we recommend using the ISABEL-RAL model, while both CEM2k and BERTINI-RAL overestimate the production rate above 1 GeV incident proton. The best combinations of models to calculate the residual nuclei production are those using ABLA fission-evaporation model, CEM2k or combinations using RAL model are giving too broad mass distributions when compared to available data. An extensive list of radio-nuclides was obtained and is available on tabular format, we show that the 4 nuclei whose contributions to the total activity of the mercury target (after 40 years of irradiation) are the most important are the following: -) 1 day after shutdown: Y⁹¹ (15%), Y⁹⁰ (13%), Hg¹⁹⁷ (6%) and Sr⁸⁹ (5%); -) 1 year after shutdown: H³ (19%), Y⁹⁰ (17%), Sr⁹⁰ (17%) and Nb^93* (10%); -) 10 years after shutdown: Y⁹⁰ (22%), Sr⁹⁰ (22%), H³ (18%) and Nb^93* (14%); and -) 100 years after shutdown: Mo⁹³ (34%), Nb^93* (32%), Pt¹⁹³ (9%) and Y⁹⁰ (8%). (A.C.)

[en] Gamma heating is an important issue in research reactor operation and fuel safety. Heat deposition in irradiation targets and temperature distribution in irradiation facility should be determined so as to obtain the optimal irradiation conditions. This paper presents a recently developed gamma heating calculation methodology and its application on the research reactors. Based on the TRIPOLI-4 Monte Carlo code under the continuous-energy option, this new calculation methodology was validated against calorimetric measurements realized within a large ex-core irradiation facility of the 70 MWth OSIRIS materials testing reactor (MTR). The contributions from prompt fission neutrons, prompt fission γ-rays, capture γ-rays and inelastic γ-rays to heat deposition were evaluated by a coupled (n, γ) transport calculation. The fission product decay γ-rays were also considered but the activation γ-rays were neglected in this study. (author)

[en] We have begun this benchmark study using mass distribution data of reaction products obtained at GSI in inverse kinematics. This step has allowed us to make a first selection among 10 spallation models; in this way the first assessment of the quality of the models was obtained. Then, in a second part, experimental mass distributions for some elements, which either are interesting as radioactive ion beams or important due to the safety and radioprotection issues (alpha or gamma emitters), will be also compared to model calculations. These data have been obtained for an equivalent 0.8 or 1.0 GeV proton beam, which is approximately the proposed projectile energy. We note that in realistic thick targets the proton beam will be slowed down and some secondary particles will be produced. Therefore, the residual nuclei production at lower energies is also important. For this reason, we also performed in the third part of this work some excitation function calculations and the associated data obtained with gamma-spectroscopy to test the models in a wide projectile energy range. We conclude that INCL4/Abla and Isabel/Abla are the best model combinations which we recommend. We also note that the agreement between model and data are better with 1 GeV protons than with 100-200 MeV protons

[en] The radioactive decay of ²⁰³Bi is studied. A level scheme is proposed for ²⁰³Pb on the basis of γ ray and electron spectra and γ-γ coincidence measurements. The experimental data are compared with theoretical results obtained in a three quasi-particle approximation

[en] Comparisons between the INCL4 cascade model, recently implemented in LAHET, and Bertini model are made in thin and thick lead targets. The impact of the cascade model used on the estimation of the target activity during its irradiation by a 1 GeV proton beam and its subsequent decay is discussed. (author)

[en] The EURISOL project is aimed at the design of the next generation European ISOL radioactive ion beam (RIB) facility able to deliver high intensity beams of 10¹³ pps at energy up to 150 MeV u^-1. The RIBs of 21 MeV u^-1 and 150 MeV u^-1 will be extracted to a number of experimental halls, where they interact with secondary targets. The purpose of this study is to configure the shielding and the management of the access to the controlled areas inside the beam experimental halls. In agreement with physics case of the project it was decided to investigate six target materials: CH₂, Be, C, Cu, Ni and Pb at two possible thicknesses of 1 mg cm^-2 and 10 mg cm². The experimental hall hosting the AGATA germanium array detector was selected as the conservative case. The conceptual model for the beam dump system to be placed at the end of the post-accelerator beam line, whose feasibility was previously demonstrated, was used here also to examine safe operation conditions inside the experimental hall. Therefore the geometry model used in simulations contains a) a simplified AGATA detector placed in the centre, b) a typical experimental target positioned inside AGATA, and c) a V-shaped beam dump configuration with a water-cooled graphite core and a subsequent iron block downstream of the beam line. A test case of ¹³²Sn²⁵⁺ RIB was used in simulations. Neutron production yields from the physics targets, dose rate estimates in the experimental area and behind the shielding walls and energy deposition on the beam dump were calculated and analysed in this study. Dedicated simulations were performed by means of the PHITS Monte Carlo computer code. In order to characterise the residual radiation environment inside the experimental halls the following procedure was developed. Induced radioactivity in the targets, AGATA equipment, concrete wall and the air inside were estimated using DCHAIN-SP-2001 code. Ambient dose equivalent rates due to the residual radiation were calculated with the MCNPX code using photon sources resulted from DCHAIN activation calculations. The lay-out of the experimental area was schematically configured by preliminary sizing of concrete shielding walls. The paper provides also the magnitude of the radioactive material inventory generated inside this zone and the associate dose rate estimates. (author)

[en] The EURISOL project is aimed at the design of the next generation European ISOL radioactive ion beam (RIB) facility able to deliver high intensity beams of 10¹³ pps at energy up to 150 MeV u^-1. The RIBs of 21 MeV u^-1 and 150 MeV u^-1 will be extracted to a number of experimental halls, 99 where they interact with secondary targets. The purpose of this study is to configure the shielding and the management of the access to the controlled areas inside the beam experimental halls. In agreement with physics case of the project it was decided to investigate six target materials: CH₂, Be, C, Cu, Ni and Pb at two possible thicknesses of 1 mg cm^-2 and 10 mg cm². The experimental hall hosting the AGATA germanium array detector was selected as the conservative case. The conceptual model for the beam dump system to be placed at the end of the post-accelerator beam line, whose feasibility was previously demonstrated, was used here also to examine safe operation conditions inside the experimental hall. Therefore the geometry model used in simulations contains: - a simplified AGATA detector placed in the centre; - a typical experimental target positioned inside AGATA, and; - a V-shaped beam dump configuration with a water-cooled graphite core and a subsequent iron block downstream of the beam line. A test case of ¹³²Sn²⁵+ RIB was used in simulations. Neutron production yields from the physics targets, dose rate estimates in the experimental area and behind the shielding walls and energy deposition on the beam dump were calculated and analysed in this study. Dedicated simulations were performed by means of the PHITS Monte Carlo computer code. In order to characterise the residual radiation environment inside the experimental halls the following procedure was developed. Induced radioactivity in the targets, AGATA equipment, concrete wall and the air inside were estimated using DCHAIN-SP-2001 code. Ambient dose equivalent rates due to the residual radiation were calculated with the MCNPX code using photon sources resulted from DCHAIN activation calculations. The lay-out of the experimental area was schematically configured by preliminary sizing of concrete shielding walls. The paper provides also the magnitude of the radioactive material inventory generated inside this zone and the associate dose rate estimates