Microscopes for the Physics at the Femtoscale: GANIL-SPIRAL2

Caen, in Normandy, France, is famous as the home of William the Conqueror. Equally well known in the field of nuclear physics is the Grand Accélérateur National d’Ions Lourds (GANIL) laboratory and its major upgrade of the existing infrastructure, Système de Production d’Ions RAdioactifs en Ligne de 2e génération (SPIRAL2) facility. GANIL is primarily focused on cutting edge research in fundamental nuclear physics using ion beams and is supplemented by strong programs in acceleratorbased atomic physics, condensed matter physics, radiobiology, and industrial applications. For many decades, GANIL has provided Highintensity stable beams (12C to 238U), beams of short-lived nuclei (Radioactive Ion Beams), produced both by in-flight separation (lifetimes ~ μs) and isotope separation on-line (ISOL) technique (lifetimes ~ ms). The five-cyclotron complex delivers stable beams from energies ~1 MeV to 95 MeV per mass unit with currents up to 10 μA, fragmentation beams up to ~ 50 MeV/A, and reaccelerated beams (SPIRAL1) from 1.2 MeV/A to 25 MeV/A (~40 isotopes). The intensities of the radioactive beams range from a few particles/s to ~107 p/s. The new superconducting linear accelerator (LINAC), in addition to very highintensity light beams, also provides a fourth type of beam, namely neutrons, to the already available arsenal of beams. These numerous types of beams are coupled to versatile detection facilities that allow the exploration of the behavior of nuclei in the phase space of excitation energy, angular momentum, and isospin. The first volume of Nuclear News (1991) portrayed the nuclear physics activities at GANIL, followed by the SPIRAL1 project (1995) and interdisciplinary physics (2000). In this article we present the evolution of the facility starting with the cyclotrons, the various associated detectors, and the current status of SPIRAL2. Figures 1 and 2 illustrate the cyclotron and LINAC complexes and their associated experimental halls. These complexes will be connected through a planned future project. GANIL, a multibeam facility, has been delivering a wide spectrum of stable and radioactive ion beams since 1983. Between 1983 and 1990, the facility relied on a cascade of three warm cyclotrons (KC0 = 30, KCSS1 = 380, KCSS2 = 380). Subsequently, a second injector was added. Various techniques were developed to increase the beam intensities, the number of isotopes, and the reliability of these beams. A major upgrade, in 2001, was the availability of reaccelerated radioactive ions from the SPIRAL1 facility. The cyclotrons serve as the driver for the production of radioactive atoms in a thick carbon target that can be reaccelerated by the new Cyclotron pour Ions de Moyenne Energie (CIME) (K = 265) up to a maximum energy of 25MeV/u (the highest in the world today). A review of the work done using SPIRAL1 beams till 2010 can be found in Ref. [1]. An upgrade, started in 2014, for increasing the number of reaccelerated beams using a Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source coupled with a charge breeder, extends those available with the existing Electron Cyclotron Resonance (ECR) ion source. This, added to the already available secondary beams by using the inflight method and stable beams, makes GANIL the only facility with this variety of beams. A continuous development of new and more intense stable beams, post-accelerated radioactive beams where GANIL has a niche, is ongoing. In parallel, there has been a continuous evolution in the detection systems, including the addition of various new detectors (discussed below). The functioning of the cyclotrons that has decreased in the last few years as a result of sharing the resources for construction of SPIRAL2, is being ramped up.