SPES is the acronym for “Selective Production of Exotic Species”. The project is devoted to basic research in nuclear physics and astrophysics as well as to interdisciplinary applications, ranging from the production of radionuclide of medical interest to the generation of neutrons for material studies, nuclear technologies and medicine. The main goal of the proposed facility is therefore to provide an accelerator system to perform forefront research in Nuclear Physics by studying nuclei far from stability.

The SPES facility is mainly concentrating on the production of neutron-rich radioactive nuclei having mass in the range 80-160 based on the Isotope Separation On-Line technique (ISOL). SPES is one of the next generation ISOL facility with ISAC-TRIUMF (Canada), SPIRAL2 (France) and REX-ISOLDE (CERN).

In an ISOL facility a primary accelerator induces fission on a primary target. Those fission products are extracted from the primary target and, in a complicated multistep process, they are driven to the superconducting linear accelerator complex (PIAVE-ALPI) of the Laboratori Nazionali di Legnaro. In this complex, the exotic ions will be re-accelerated till a suitable energy for experimentation. We call them as Radioactive Ion Beams because they are unstable and will decay into stable elements in a relatively short time.

The products of the collisions of those Radioactive Ion Beams collision with stable targets, are rare neutron-rich nuclei similar to those generated in advanced stellar stages and  do not present on Earth due to their short lifetime. The investigation on such systems is a new frontier of physics for extending our knowledge of nuclei at extreme conditions and to give basic information for the study of nuclear structure, the formation of matter and stellar evolutions.

The combination of SPES with the present ALPI-Linac will allow to explore ever-more exotic regions of the nuclear chart, towards the limits of stability of nuclei.

A simplified layout sketch of SPES facility is shown in the picture.

SPES is a project of the INFN Road Map for the Nuclear Physics development.