Survey and alignment concept for installation of the SPIRAL2 accelerator devices at GANIL

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Survey and alignment concept for the SPIRAL2 accelerator (status report)

International audienceThe SPIRAL2 project located at the GANIL facility (Caen, France) has been studied since the beginning of 2003, and is now under construction. This project aims at delivering rare (radioactive) isotope beams with intensities not yet available with presently running machines. An important aspect of this project is that it is foreseen to deliver up to five different beams in parallel to the users. This paper is a status report on the survey and alignment techniques selected for installation of the SPIRAL2 accelerator device

The initial geodetic survey for the SPIRAL2 process installation

International audienceThe SPIRAL2 project located at the Grand Accélérateur National d'Ions Lourds (GANIL facility - Caen, France) has been studied since the beginning of 2003, and is now under construction. This project aims at delivering rare (radioactive) isotope beams with intensities not yet available with presently running machines. An important aspect of this project is that it is foreseen to deliver up to five different beams in parallel to the users. This paper is focused mainly on the initial geodetic survey for the SPIRAL2 process installation. The positioning of the process and by extension of the buildings is subject to an important constraint due to the future connection of the radioactive beam line to the existing accelerator (see Fig.3). In order to reach the performances, a geodetic reference network (surface network) linked to the local survey network of the existing accelerator is designed [1]. The surface network will be transferred to the floor of the SPIRAL2 accelerator tunnel (9m under the ground), in order to define the underground reference network for the process setup. Final goal of the initial geodetic survey is to align process components of accelerator according to design within required tolerances

Overview on the preliminary geodetic network for SPIRAL2 process installations at GANIL

The SPIRAL2 project located at the Grand Accélérateur National d'Ions Lourds (GANIL facility - Caen, France) is now under construction. This project aims at delivering rare (radioactive) isotope beams with intensities not yet available with presently running machines. An important aspect of this project is that it is foreseen to deliver up to five different beams in parallel to the users. This paper is focused mainly on the preliminary geodetic network for the SPIRAL2 process installation. The positioning of the process and by extension of the buildings is subject to an important constraint due to future connection of the radioactive beam line to the existing accelerator complex. To reach the required accelerator performances, a geodetic surface network made up of concrete monuments around the construction is linked to the local network of the existing accelerator [1]. The surface network has been transferred to the slab of the accelerator tunnel at -2 level (-9.50 m) in order to define the underground reference network for the process setup. Final goal of the geodetic network is to allow the alignment of the process accelerator components [2] [3] [4] [5] [6] according to design within required tolerance. Various tolerances objectives will be given

A full quantal theory of one-neutron halo breakup reactions

We present a theory of one-neutron halo breakup reactions within the framework of post-form distorted wave Born approximation wherein pure Coulomb, pure nuclear and their interference terms are treated consistently in a single setup. This formalism is used to study the breakup of one-neutron halo nucleus 11Be on several targets of different masses. We investigate the role played by the pure Coulomb, pure nuclear and the Coulomb-nuclear interference terms by calculating several reaction observables. The Coulomb-nuclear interference terms are found to be important for more exclusive observables.Comment: 22 pages latex, 9 figures, submitted to Phy. Rev.

SPIRAL2 RFQ prototype - First results

JACoW web site MOPCH103International audienceThe SPIRAL2 RFQ is designed to accelerate either 5 mA deuteron beam (Q/A=1/2) or a 1 mA of q/A=1/3 particle up to 0.75 MeV/A at 88 MHz. It is a CW machine which has to show stable operation, provide the required availability and reduce losses to a minimum in order to minimize the activation constraints. Extensive modelisation was done to ensure a good vane position under RF. The prototype of this 4-vane RFQ was built and tested in INFN-LNS Catania and then in IN2P3-LPSC Grenoble. It allowed us to measure the vacuum quality, the RF field by X-ray measurements, the cavity displacement and the real vane displacement during the RF injection. Different techniques were used, including an innovative CCD measurement with a 0.8 μm precision. This paper outlines the different results

Coulomb-nuclear interference in the breakup of 11^{11}Be

Within a theory of breakup reactions formulated in the framework of the post form distorted wave Born approximation, we calculate contributions of the pure Coulomb and the pure nuclear breakup as well as those of their interference terms to a variety of cross sections in breakup reactions of the one-neutron halo nucleus $^{11}$Be on a number of target nuclei. In contrast to the assumption often made, the Coulomb-nuclear interference terms are found to be non-negligible in case of exclusive cross sections of the fragments emitted in this reaction on medium mass and heavy target nuclei. The consideration of the nuclear breakup leads to a better description of such data.Comment: 9 pages, latex, 2 figures, to be published in Phys. Rev. C (Rapid Communication

Spiral2 cryomodules B tests results

MOP010International audienceAssembly and tests of the SPIRAL2 superconducting linac's cryomodules at CEA/Saclay and IPN/Orsay have now reached cruising speed after having faced a series of problems, among them contamination. 19 cryomodules are composing the whole Linac and IPN Orsay is in charge of the 7 cryomodules B, housing two 88 MHz, beta 0.12 Quarter-Wave Resonators. Threecryomodules have been assembled and successfullytested up to the nominal gradient of 6.5 MV/m for all cavities with also cryogenic losses withinspecifications. Two of them are fully qualified and already delivered to GANIL. The thirdone showed misalignment ofone cavity which could lead to partial disassembly if needed. This paper presents the results of those cryomodules tests as well as the status of the remaining ones

The alignment strategy for the SPIRAL2 superconducting LINAC cryomodules

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Positionnement et alignement de l'accélérateur SPIRAL2

CDROMNational audienceLe projet SPIRAL2 étudié à partir de 2001, est maintenant dans sa phase de construction. Les premiers faisceaux stables sont prévus dès début 2012 tandis que les faisceaux radioactifs seront produits à partir de 2013. La présentation sera focalisée principalement sur les techniques d'alignement et de positionnement retenues pour l'installation des composants fonctionnels de l'accélérateur, tels que : - les éléments de conduite et de diagnostiques de faisceau de l'injecteur, - le Radio Fréquence Quadrupôle (RFQ), - les cryomodules du linac. Dans un tel projet, la stratégie d'alignement doit être étudiée très en amont du design définitif, c'est-à-dire dès la phase de l'Avant Projet Détaillé (APD). Il faut également établir les fondements de la géométrie très tôt, ce qui suppose de connaître la problématique, de se faire une opinion de la géométrie de l'objet et de bien connaître les différentes phases de montage et d'assemblage. Toute opération exige la mise en place d'une méthodologie exhaustive et appropriée. Pour déterminer la meilleure technique d'alignement, il est essentiel de connaître les exigences d'alignement, c'est-à-dire les erreurs maximums tolérées (σx, y, z et σθx, θy, θz). Un objet est positionné dans l'espace au moyen de ces marques fiducielles (repères). La haute qualité métrologique de ces fiducielles dans le référentiel objet est un paramètre important dans la précision finale. Dans cette présentation, l'instrumentation de mesures retenue sera présentée