TheSPIRAL-2project aims at building at GANIL a new ISOL-type facility forthe production of high intensity rare isotope beams. Theproject has now entered the construction phase, for first beam production around 2012. The driver accelerator must accelerate a 5 mA CW deuteron beam up to 40 MeV, and a 1 mA CW ion beam with mass-to-charge ratio A/q=3 up to 14.5 A.MeV. It must also have the capability to accelerate protons (new requirement) and, in a future stage, to host a second injector to accelerate ions of mass-to-charge ratio A/q up to 6. Naturally, this driver accelerator is a linac with independently-phased superconducting cavities for high safety and maximum flexibility in the acceleration of different ion species with different charge-to-mass ratios at various final energies. The linac is divided into 3 main parts: injector, superconducting linac, and high-energy beam transport lines (HEBTs).
SPIRAL2 DRIVER ACCELERATOR
Beams to be accelerated
In order to fulfil the physics requirements, the SPIRAL2 driver accelerator must be able to accelerate high-intensity beams of protons, deuterons, ions with A/q<3, and optionally ions with A/q<6. As indicated in table 1, a maximum beam power of 200kW is required for deuterons in CW mode. In order to transport and accelerate these intense beams with a minimum of losses, many beamdynamics calculations have been performed all along the machine, by using realistic source particle distributions, real 3D magnetic fields, compensation space charge effects in various situations, and also with systematic errors studies. The whole driver accelerator will be controlled using the EPICS software coupled with the TRACEWIN/PARTRAN code in order to implement the notion of a “virtual machine”.
long drift 0.2
the beneficial effect of reduced overall transverse excursion during acceleration (which determines the horizontal op- tical aperture). Fig. 2 shows the corresponding evolution of magnetic field shape across the cell depending on en- ergy. Closed orbit dependence on energy, a specific prop- erty of FFAGs, shows a general behavior of outward spiral- ing from injection to top energy (Fig. 1).
REQUIREMENTS AND DESCRIPTION
The chopper will be used to progressively increase thebeam power during accelerator tuning, to avoid hitting the
wheel spokes of rotating targets and to rapidly remove thebeam in case of failure detection by the machine protection system (MPS). The tuning of the high power (200 kW) beam requires low repetition rates but a very
insertion of two additional high- β cryomodules should the
field gradient in operation be lower than expected.
Intensive beamdynamicsstudies and simulations have been carried out to ensure a robust design and a very low beam loss along the linac. Multiparticle simulations are performed from the Low Energy Beam Transport (LEBT) line to the target through the radio frequency quadrupole (RFQ), the Medium Energy Beam Transport (MEBT), the two superconducting sections (SC1, SC2) and the High Energy Beam Transport (HEBT) line. Several elements
Fig. 1: structure of an UCx target by Scanning Electron Microscopy. The graphite appears in black, the uranium carbide UC and UC 2 in white. The uranium carbide grain size is about 20 to 30 µm.
2. TheSpiral2 target
FortheSPIRAL2projectthe specification is to reach 10 13 fissions/s in the case of UCx target using a 40 MeV/5 mA deuteron beam with a rotating carbon converter . The production of a target irradiated by fast neutrons is estimated using the FICNER code . Thanks to this code one can see the effect of geometrical parameters onto the production. The figure 2 illustrates the importance to put the target as close as possible to the converter.
The high current driver accelerator of theSPIRAL2project uses independently phased SC resonators working at 88 MHz. Solid state power amplifiers equipped with circulators are foreseen to drive the cavities with widely ranging conditions of beam loading. These power devices are developed by industrial companies and a test bench has been studied and manufactured to test the prototypes, to commission all the units before their installation on the accelerator and to be used to test repaired modules. Even if designed to be used at 88 MHz, the test bench can be used at higher frequencies too. The poster describes the test bench as well as the results on the first amplifiers bought forthe cryomodule power tests.
The RFQ must operate in cw mode. Its frequency has been chosen to be 88 MHz, a sub-harmonic of 352 MHz. This rather low value has been determined forthe following reasons: the RF power density is quite low at this frequency and allows a solution based on a formed- metal technology, leading to a cheap mechanical solution; at low frequencies, the inter-electrode distance is larger and permits a higher margin forthe mechanical tolerances; power sources are readily available. The RFQ output energy, 0.75 A.MeV, has been determined by the fact that the first cavities of the SC linac must permit a possible evolution of the machine to ions with q/A = 1/6, which means that their β -values have to remain quite low (~0.07). The main RFQ parameters are described in the following table. The maximum peak field value is kept at a conservative level of 1.65 Kilpatrick , lower than LEDA  which also works in cw mode. The transverse curvature of the pole, ρ , has been maintained constant to simplify the machining (with a 2D tool).
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, I-95123, Italy
In the DAEδALUS (Decay-At-rest Experiment for δ CP studies At the Laboratory for Underground Science) project, high power H + 2 cyclotron chains are proposed to efficiently provide proton beams with a kinetic energy of 800 MeV and an average power in the MW range. Space charge plays a pivotal role in both the injector and the ring cyclotrons. Large-scale particle simulations show that the injector cyclotron is a space charge dominated cyclotron and that a 5mA beam current can be extracted with tolerable beam losses on the septum. In contrast, in the ring cyclotron, no space charge induced beam loss is observed during acceleration and extraction.
The target and the ion source will be placed in a rectangular module (called plug) that is surrounded by 2 m of concrete for shielding of workers and equipment. The same principle has been applied on the ISAC facility at TRIUMF (Vancouver, Canada), forthe production of radioactive beams with a 500 MeV, 100 A primary beam. At this time, two solutions are under studies : the first one consists in sending the primary beam vertically while the second one prefers to send it horizontally. These two solutions will be studied in details during the next months and a final approach will be taken considering the advantages and the disadvantages of each one. Two turbo molecular pumps and the insulators are thereby located on the top of the plug where they are protected from radiations. This increases the life time of the different components and permits the manual disconnection of the electrical powers.
This package will forbid access to a room where the radiological conditions are not sure and, conversely, will forbid thebeam if there is a possibility of presence of a person. The study of the system is finished and the record of safety in preparation. At GANIL, the ions are accelerated by cyclotrons (C01 or C02, CSS1, CSS2, CIME) and are transported through beamlines towards the rooms of experiments (D1-D6, G1-G4). A first named extension SPIRAL was brought into service in 2000. It makes it possible to produce and post-accelerate, via the cyclotron CIME, the radioactive ion beams obtained by fragmentation of stable ions resulting from CSS2 in a carbon target. Theproject SPIRAL2 will arrive soon and has the same need in safety.
LAYOUT AND PERFORMANCES OF THESPIRAL2 FACILITY
TheSPIRAL2 facility (fig. 2) is based on a high-power, superconducting driver LINAC, which will deliver a high-intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass-to-charge ratio of 3 and energy up to 14.5 MeV/nucleon. Using a carbon converter, the 5 mA deuteron beam and a uranium carbide target, fast-neutron induced fission is expected to reach a rate of up to 10 14 fissions/s. The RNB intensities in the mass range from A=60 to A=140 will be of the order of 10 6 to 10 11 particles/s (pps) surpassing by one or two order of magnitude any existing facilities in the world. For example, the intensities should reach 10 9 pps for 132 Sn and 10 10 pps for 92 Kr. A direct irradiation of the UC
For phenomena that are restricted in space, i.e. to a small part of the computational domain, a wide range of methods has been developed. These approaches are always in progress and can be divided into exact (or direct) methods and iterative ones. The most popular exact approaches are the static condensation techniques and the exact structural reanalysis methods, such as used in Hirai , Hirai et al . Adaptive meshing techniques can be used for a local refinement of a 3D model, see for example Plaza et al . Volume patches such as Arlequin enable to superpose two different domains, e.g. a beam model and a 3D model. Applications examples can be found in Ben Dhia , Ben Dhia and Rateau , Cottereau et al , Ghanem et al . Beam to 3D connections or shell to 3D connections, enable to account accurately for local 3D phenomena, while the rest of the model is less computationally expensive thanks to thebeam or shell elements. Many applications in the literature exist such as the mixed beam-3D model used by Kettil and Wiberg  forthe simulation of a bridge deformation.
IRRADIATION CONTROL OF THE “SPIRAL” TARGET BY MEASURING THE ION BEAM INTENSITY VIA A FAST CURRENT TRANSFORMER
P. Anger, C. Doutressoulles, C. Jamet, T. André, W. Le Coz, E. Swartvagher, M. Ozille Grand Accélérateur National d’Ions Lourds (GANIL), Caen, France
• Relatively small number of lattice cells was assumed (8, 10) in order to avoid fringe field dominated magnet design. On the other hand small number of lattice cells do not allow large field index values, which dictates rather large orbit excursion and increases the magnet weight. The cell number of 10 is a compromise between the minimization of the magnet cost and the need for straight section length mainly for cavity placement and injection/extraction systems.
Basic parameters of SPIRAL-2
A huge number of high energy neutrons (in the range between 1 and 40 MeV), produced in the carbon converter via C(d,xn) reaction, will be present at theSPIRAL-2project at GANIL (Caen, France) aiming to produce neutron-rich fission fragments . The main goal of this study is to provide quantitative estimates on the possibility of using a 40 MeV (5mA) linear deuteron accelerator in a combination with a rotating carbon target, as projected at SPIRAL-2, for material irradiation purposes. It is also aimed to give a direct comparison with the ITER irradiation environment as well as the IFMIF project, introduced briefly below, in terms of available neutron fluxes, energy spectra, material damage rates and irradiation volumes.
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Chapitre 2 Développement d’un ECS dédié aux faisceaux d’ions alcalins 109
Fig. 52 _ Schéma de principe du système d’acquisition des mesures de temps de réponse et d’efficacité.
En sortie du tube ioniseur, l’énergie des ions dans la ligne après l’électrode d’extraction peut atteindre 20 keV. Elle est fixée par la tension de la plate-forme de l’ensemble de production. Une seconde plateforme, référencée par rapport à la première, fixe l’énergie des ions injectés dans la cavité à 1 keV. Des lectures de courant sont placées sur tous les éléments d’optique du canon à ions (voir le schéma électrique Fig. 60). Elles permettent de connaître le courant récolté sur chacun de ces éléments. Leur bilan permet de déduire précisément le courant d’ions injecté dans la cavité. Les lectures de courants sont effectuées à la haute tension. Leur acquisition est réalisée sur un oscilloscope référencé à la masse 0 V à l’aide de convertisseurs électrique-optique-électrique (EOE). L’injection d’impulsions d’ions par le canon déclenche simultanément l’acquisition sur l’oscilloscope. Le schéma de principe (Fig. 52) présente le système d’acquisition des mesures de temps de réponse et d’efficacité. L’allure de plusieurs signaux est présentée : U c l’impulsion de commande envoyée au canon à ions, I inj le courant
C. Hypothesis tests
Hypothesis tests for two animals were conducted to examine the statistical significance of the difference in mean breathing rate before and after the injection of the dopamine agonist. Under the null hypothesis, the means before and after the injection would be the same, and therefore, the difference between the two would equal zero. For each animal, three versions of this hypothesis test were performed. The first, which we call the naive test, was done without accounting forthe serial correlation between observations. The second, called the modified test, accounted for serial correlation and used the conditional maximum likelihood estimates and the Fisher information matrix to calculate the z-statistic. The third test also used the conditional maximum likelihood estimates of the parameters, but parametric bootstrap methods were used to estimate the variance of μ̂ instead of the Fisher information