M. Re

The Production of Negative Lithium Beams by Charge Exchange in Cesium Vapours

These measurements were carried out at the Holifield Radioactive Ion Beam Facility of the Oak Ridge National Laboratory (ORNL-HRIBF) by researchers from the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), Catania, Italy and local staff. The Charge Exchange Cell (CEC) consisted of a vacuum chamber containing cesium vapours at a variable temperature T, in which positive ions accelerated from an ion source were transformed into negative ones by collisions with the Cs atoms. The main goal of this test was to measure the production efficiency for7Li-ions at different operating conditions, such as7Li+beam energy (5 to 55 keV) and Cs temperature (190 to 300 °C). Moreover, the efficiency measurements performed with a6Li+projectile beam gave clear indications about the isotopic shift effect. These results are useful to estimate the charge exchange efficiency for8, 9Li, which will be the first radioactive beams to be produced at the EXCYT facility (EXotics with CYclotron and Tandem). The data showed that the charge exchange efficiency at the minimum energy suitable for beam handling (20-25 keV) is around 1%.

Radioactive ion beam facilities at INFN LNS

Radioactive ion beams are produced at INFN- Laboratori Nazionali del Sud (LNS) by means of the two operating accelerators, the Tandem and the Superconducting Cyclotron (CS), originally designed to accelerate stable beams. Both the ISOL (Isotope Separation On Line) and the IFF (In-Flight Fragmentation) methods are exploited to produce RIBs in two different ways at different energies: in the first case, the Cyclotron is the primary accelerator and the Tandem accelerates the secondary beams, while in the second case radioactive fragments are produced by the Cyclotron beam in a thin target with energies comparable to the primary beam energy. The ISOL facility is named EXCYT (Exotics at the Cyclotron and Tandem) and was commissioned in 2006, when the first radioactive beam (8Li) has been produced. The IFF installation is named FRIBs (in Flight Radioactive Ion Beams), and it has started to produce radioactive beams in 2001, placing a thin target in the extraction beam line of the Cyclotron. The development of both facilities to produce and accelerate radioactive ion beams at LNS, is briefly described, with some details on the future prospects that are presently under consideration or realization.

Status Of The EXCYT Facility at INFN‐LNS

The EXCYT facility (EXotics with CYclotron and Tandem) at the INFN‐LNS is based on a K‐800 Superconducting Cyclotron injecting stable heavy‐ion beams (up to 80 MeV/amu, 1 eμA) into a target‐ion source assembly to produce the required nuclear species, and on a 15 MV Tandem for post‐accelerating the radioactive beams. Since December 1999 the Superconducting Cyclotron operates in a stand‐alone mode by means of the new axial injection beam line. The primary beam line has been already mounted and tested. The part of mass separator on the two high‐voltage platforms together with low intensity diagnostics is already installed while the ancillary items along with the part of mass separator at ground potential will be installed during the next stop of accelerator operations. The target‐ion source unit has been successfully tested on‐line at GANIL. The goal of such efforts will be represented by the test of the mass separator with stable beams planned at LNS by the end of the year. The commissioning of the EXCYT fa...

The SPES Direct Target Project at the Laboratori Nazionali di Legnaro

The construction of the Radioactive Ion Beam (RIB) Facility SPES‐DT, within the framework of the new European RIB panorama is under study at the Laboratori Nazionali di Legnaro. The present project will be devoted to the production of neutron rich exotic nuclei, by using the fission process induced by a 40 MeV proton beam, 200 μA current, on a multi‐sliced Uranium Carbide (UCx) target. The UCx multiple thin disks target, developed at LNL is designed so that the power released by the proton beam is mainly dissipated by irradiation. Following the idea of the existing HRIBF facility at Oak Ridge National Laboratory (USA) where a proton primary beam of 40 MeV is also used, our target configuration is an evolution which permits to sustain a higher power on target. A high number of fission products (up to 1013 fission/s) will be obtained, still keeping a low power density deposition inside the target. The whole facility, together with the details on the Direct Target configuration, will be described. Thermo‐mec...

The SiC Direct Target Prototype for SPES

A R&D study for the realization of a Direct Target is in progress within the SPES project for RIBs production at the Laboratori Nazionali of Legnaro. A proton beam (40 MeV energy, 0.2 mA current) is supposed to impinge directly on a UCx multiple thin disks target, the power released by the proton beam is dissipated mainly through irradiation. A SiC target prototype with a 1:5 scale has been developed and tested. Thermal, mechanical and release calculations have been performed to fully characterize the prototype. An online test has been performed at the HRIBF facility of the Oak Ridge National Laboratory (ORNL), showing that our SiC target can sustain a proton beam current considerably higher than the maximum beam current used with the standard HRIBF target configuration.

Production of Inorganic thin Scintillating Films for Ion Beam Monitoring Devices

In this work we present the development of beam monitoring devices consisting of thin CsI(Tl) films deposited on Aluminium support layers. The light emitted by the scintillating layer during the beam irradiation is measured by a CCD-camera. In a first prototype a thin Aluminium support layer of 6 micron allows the ion beam to easily pass through without significant energy loss and scattering effects. Therefore it turns out to be a non-destructive monitoring device to characterize on-line beam shape and beam position without interfering with the rest of the irradiation process. A second device consists of an Aluminium support layer which is thick enough to completely stop the impinging ions allowing to monitor at the same time the beam profile and the beam current intensity. Some samples have been coated by a 100 Å protective layer to prevent the film damage by atmosphere exposition. In this contribution we present our experimental results obtained by irradiating the samples with proton beams at 8.3 and 62 MeV. We also propose some innovative applications of these beam monitoring devices in different nuclear sectors such as cancer proton therapy and high intensity beam accelerators.

Electrostatic Deflectors: New Design for High Intensity Beam Extraction

During the last years big effort was devoted to increase the electrostatic deflectors’ reliability; this provided a better comprehension of the most significant effects concerning their working conditions. Deflectors were checked during the normal operation of the K800 Superconducting Cyclotron (CS) at LNS, at the operating pressure of 1 10-6mbar and a magnetic field of 3.5 T, the maximum cathodes voltage was – 60kV (120 kV/cm). The maximum extracted beam power was, up to now, 100 W; it is foreseen to extract up to 500 W. In this contribution we present the study, the tests and the design of a new water cooled electrostatic deflector. Particular effort was applied to optimise the beam extraction efficiency, the thermal dissipation, and the mechanical stability. In particularly we implemented new insulators, new anodised aluminium cathodes, new Ta septum, new voltage and water feedthroughs and a more efficient cooling system. All these improvements were performed to increase the mean time between failure and the beam current stability.