[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] Exclusive ω electroproduction off the proton was measured at the highest possible four-momentum transfer with the (close to) 6 GeV beam now available at CEBAF. Cross sections are presented, together with an analysis of the ω spin density matrix elements. Indications are that π⁰ exchange in the t-channel (or rather the exchange of the corresponding saturating Regge trajectory) seems to dominate the process γ*p → ωp, even for photon virtuality Q² as large as 5 GeV². Contributions of the handbag type, related to Generalized Parton Distributions in the nucleon, are therefore difficult to extract from this particular process

[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 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

[en] A previous analysis of the charge (Z) correlations in the ΔZ-< Z> plane for ¹²⁹Xe+^natSn central collisions at 32 MeV/n has shown an enhancement in the production of equally sized fragments (low ΔZ) which was interpreted as an evidence for spinodal decomposition. However, the signal is weak and rises the question of the estimation of the uncorrelated yield. After a critical analysis of its robustness, we propose in this paper a new technique to build the uncorrelated yield in the charge correlation function. The application of this method to ¹²⁹Xe+^natSn central collision data at 32, 39, 45 and 50 MeV/n does not show any particular enhancement of the correlation function in any ΔZ bin

[en] The new type of charged particle detector described comprises a thin layer of plastic scintillator over a much thicker CsI(Tl) crystal, an optical guide, and a photomultiplier. Results obtained at Chalk River Laboratories for the identification of particles with Z = 1-6 from the ¹²C + ¹⁹⁷Au reaction are shown. 12 refs., 4 figs

[en] Fission fragment distributions and delayed neutron yields for 235U and 238U are provided by a complete modelization of the photofission process below 25 MeV. The absorption cross-section parameterization and the fission fragment distributions are given and compared to experimental data. The delayed neutron yields and the half-lives in terms of six groups are presented and compared to data obtained with a bremsstrahlung spectrum of 15 MeV

[en] Quasi-complete events from collisions between ³⁶Ar and ⁵⁸Ni corresponding to vaporized sources have been detected with the multidetector INDRA over the excitation energy range 10 - 28 AMeV. For the first time complete information concerning kinematical properties of emitted particles and chemical composition (mean values but also variances) are derived. Despite the very extreme conditions in which such sources are produced (binary collisions with short reaction times and source life-times), their properties are in agreement with the results of a statistical model including a final state excluded volume interaction and describing a gas of fermions and bosons in thermodynamical equilibrium. (authors)