Origin of the SPIRAL2 Project
From the very beginning of the SPIRAL project, an upgrade – SPIRAL 2 – was envisaged to increase both the range and the mass of exotic nuclei produced by SPIRAL.
The initial idea was to use a deuteron beam produced by GANIL to induce fission in an uranium target. This was the basis for the “SPIRAL Phase II” European research and development contract, coordinated by M.G. Saint-Laurent from 1998 to 2001 (see Report “SPIRAL Phase II, European RTT”, September 2001, GANIL R 01 03).
However, mainly for reasons of safety, the idea of using GANIL for production of the primary beam was soon abandoned in favour of a made-to-measure “driver”.
In the year 2000 photofission of an uranium target as a means of producing the desired fission fragments began to look like a possibility. This idea – an “electron driver” - compared to a room-temperature or superconducting cyclotron for production of a deuteron beam was examined in a Preliminary Design Study coordinated by D. Guillemaud-Mueller (see report “SPIRAL II: Preliminary Design Study”, November 2001, GANIL R 01 04).
At around the same time, an intermediate energy superconducting linear accelerator for very high intensity light and medium-heavy ion beams – LINAG – was proposed by G. Auger, W. Mittig, M.-H. Moscatello and A. Villari (see “High Intensity beams at GANIL and future opportunities : LINAG” Report, September 2001, GANIL R 01 02). In its first phase (LINAG I) the acceleration of deuterons by this “driver” would achieve the specifications fixed for SPIRAL 2 , namely 1013 fissions per second. The LINAG phase I study was coordinated by W. Mittig (“LINAG Phase I” Report, June 2002, GANIL). In parallel, the Electron Option Preliminary Design study was coordinated by F. Loyer (report "SPIRAL II Electron Option Preliminary Design Study", September 2002, GANIL R 02 03).
The choice between the “electron driver” option and LINAG I was discussed on numerous occasions within the community (GANIL Colloquium, Belgodère, September 2001; Discussion meeting in Paris, October 2001; ...) and by the Scientific Council of GANIL (December 2001 and June 2002).
At the end of 2001 two Preliminary Design Study groups set to work to study in detail both options. The two resulting reports were examined by an International Committee of Experts, then by the Scientific Council of June 2002.
LINAG is the solution chosen for the SPIRAL 2 driver, as it offers better technical options, as well as allowing for a future coordination of GANIL's long-term future in the context of EURISOL. Moreover, the possibility of accelerating both light and heavy-ions in the linear accelerator gave a unique and attractive aspect to LINAG allowing for alternative options related with a further extension of the linear accelerator up to intermediate energies,.
The detailed design study (APD) of the SPIRAL2 project from November 2002 to January 2005 was coordinated by A. Mosnier (APD Project leader) and R. Anne (APD Deputy Project Leader).
The White Book of the project based on the APD Intermediate Report (Livre Blanc SPIRAL 2, GANIL, Juin 2004) was submitted to the French Ministry of Research in July 2004. This document included a preliminary version of the SPIRAL 2 Physics Case.
The final SPIRAL 2 technical design study report defining the reference project, variety of options and further extensions was published in January 2005 (The SPIRAL 2 Project APD Report, GANIL, January 2005).
All the studies and reports mentioned above were elaborated in close collaboration with a large number of physicists and engineers from various laboratories in France and abroad.
On the basis of referee reports of international experts and Committees (NuPECC and ESFR), the positive evaluations by IN2P3/CNRS and DSM/CEA, and the support of the region of Basse-Normandie the French Minister of Research took the decision on the construction of SPIRAL 2 in May 2005.
The construction phase of SPIRAL2 is being coordinated since the 1st of July 2005 by M. Jacquemet (Project Leader) and M. Lewitowicz (Scientific Coordinator) within a consortium between CNRS, CEA and the region of Basse-Normandie and in collaboration with French, European and international institutions.