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The commissioning of the EXCYT facility has been recently completed by delivering a post-accelerated radioactive beam to the users. Extensive tests of the whole installation have been accomplished over the last year. At the beginning the source and the mass separator were tested by producing a stable 7Li beam, then the charge exchange cell was tested with the same stable beam, and finally a 8Li beam was produced and transported through the mass separator to the Tandem for the post-acceleration. Acceleration tests at the Tandem have started and will be completed in the next few months. In the last year the upgrading programme of the Superconducting Cyclotron has also gone ahead: significant improvements have been introduced to the electrostatic deflector, in order to increase the extracted current of 13C, 45 AMeV beam, since it was chosen as a primary beam for the 8Li production. The project status is given here, along with a detailed description of the commissioning tests performed and the results obtained.

The EXCYT facility at the INFN-LNS is based on a K-800 superconducting cyclotron delivering stable ion beams on a Target Ion Source (TIS) assembly to produce the required nuclear species, and on a 15 MV Tandem for post-accelerating the radioactive beams. For some ion beams such as for Li, the extraction efficiency from the TIS is higher when obtained by positive ionisation, while the injection into the Tandem is possible only after a charge exchange to obtain negative ions. In this work we present the procedures together with the results of the production of 6,7,8,9Li beams extracted at EXCYT during the last year. The production of the radioactive elements was performed by sending a 13C4+primary beam of 45 MeV/u on a graphite target. The ionisation of the production species was achieved by a tungsten positive surface ioniser. The Li+has been extracted from TIS at different energies to cross-check the transmission and the charge exchange efficiency. To perform the conversion from positive to negative ions we employed a Charge Exchange Cell (CEC) containing Cs vapours. The Li beam interacts with the latter in a two-step reaction, thus converting its charge from +1 to –1. The CEC was already characterised during off-line tests; the results obtained at EXCYT confirmed both the isotopic shift effect and the efficiency values at several given extraction energies. Future improvements of the TIS and the CEC are discussed.

By bombarding a target with stable ion beams it is possible to produce nuclear radioactive species. The EXCYT facility at the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud (INFN-LNS), in Catania, is based on a K-800 superconducting cyclotron injecting high intensity beam (up to 500 W) in a Target Ion Source (TIS) assembly, and on a 15 MV Tandem for post-accelerating the Radioactive Ion Beams (RIB). Radioactive species are produced in a solid porous target where, by diffusion, they will reach the target surface. After effusion through the target container, radioactive atoms are ionized, extracted at low energy, and changed in charge (if needed). Two stages of isobaric mass separators will clean the resulting radioactive beam from contaminants, thus the RIB is injected into the Tandem for the post-acceleration. TIS is operating at high temperature (up to 2700 K) under vacuum (10-4 mbar). The production of 8Li radioactive beam was performed by injecting a 13C4+ primary beam of 45 MeV/u on a porous graphite target. In this work we present a study to optimize the target geometry in order to increase the production of the RIB. Our first RIB was 8Li which mean life time is 1.212 s. The generation density of 8Li inside the solid target is calculated by EPAX II code. A simple diffusion model which takes into account either the nuclei generation and their decay, was computer simulated to estimate the efficacious diffusion coefficient of 8Li in porous graphite which resulted to be in the range of 10-6 - 10-5 cm2/s. Since the porous nature of the target, many diffusion mechanisms are active, our assumption, supported by experimental evidence, is that at such high temperature multi-grain diffusion prevails. Diffusion length inside the target of 8Li, before its decay, resulted to be sensible smaller than the target size, therefore we modified its geometry enhancing the RIB production by a factor of 3-4.

Abstract.: The EXCYT facility at the INFN-LNS is based on a K-800 superconducting cyclotron delivering stable ion beams on a Target Ion Source (TIS) assembly to produce the required nuclear species, and on a 15 MV Tandem for post-accelerating the radioactive beams. For some ion beams such as for Li, the extraction efficiency from the TIS is higher when obtained by positive ionisation, while the injection into the Tandem is possible only after a charge exchange to obtain negative ions. In this work we present the procedures together with the results of the production of 6,7,8,9Li beams extracted at EXCYT during the last year. The production of the radioactive elements was performed by sending a 13C4+ primary beam of 45 MeV/u on a graphite target. The ionisation of the production species was achieved by a tungsten positive surface ioniser. The Li+ has been extracted from TIS at different energies to cross-check the transmission and the charge exchange efficiency. To perform the conversion from positive to negative ions we employed a Charge Exchange Cell (CEC) containing Cs vapours. The Li beam interacts with the latter in a two-step reaction, thus converting its charge from +1 to –1. The CEC was already characterised during off-line tests; the results obtained at EXCYT confirmed both the isotopic shift effect and the efficiency values at several given extraction energies. Future improvements of the TIS and the CEC are discussed.

Abstract.: The commissioning of the EXCYT facility has been recently completed by delivering a post-accelerated radioactive beam to the users. Extensive tests of the whole installation have been accomplished over the last year. At the beginning the source and the mass separator were tested by producing a stable 7Li beam, then the charge exchange cell was tested with the same stable beam, and finally a 8Li beam was produced and transported through the mass separator to the Tandem for the post-acceleration. Acceleration tests at the Tandem have started and will be completed in the next few months. In the last year the upgrading programme of the Superconducting Cyclotron has also gone ahead: significant improvements have been introduced to the electrostatic deflector, in order to increase the extracted current of 13C, 45 AMeV beam, since it was chosen as a primary beam for the 8Li production. The project status is given here, along with a detailed description of the commissioning tests performed and the results obtained.

The commissioning of the EXCYT facility has been recently completed by delivering a post-accelerated radioactive beam to the users. Extensive tests of the whole installation have been accomplished over the last year. At the beginning the source and the mass separator were tested by producing a stable 7Li beam, then the charge exchange cell was tested with the same stable beam, and finally a 8Li beam was produced and transported through the mass separator to the Tandem for the post-acceleration. Acceleration tests at the Tandem have started and will be completed in the next few months. In the last year the upgrading programme of the Superconducting Cyclotron has also gone ahead: significant improvements have been introduced to the electrostatic deflector, in order to increase the extracted current of 13C, 45?AMeV beam, since it was chosen as a primary beam for the 8Li production. The project status is given here, along with a detailed description of the commissioning tests performed and the results obtained.

The EXCYT facility at the INFN-LNS is based on a K-800 superconducting cyclotron delivering stable ion beams on a Target Ion Source (TIS) assembly to produce the required nuclear species, and on a 15?MV Tandem for post-accelerating the radioactive beams. For some ion beams such as for Li, the extraction efficiency from the TIS is higher when obtained by positive ionisation, while the injection into the Tandem is possible only after a charge exchange to obtain negative ions. In this work we present the procedures together with the results of the production of 6,7,8,9Li beams extracted at EXCYT during the last year. The production of the radioactive elements was performed by sending a 13C4+primary beam of 45?MeV/u on a graphite target. The ionisation of the production species was achieved by a tungsten positive surface ioniser. The Li+has been extracted from TIS at different energies to cross-check the transmission and the charge exchange efficiency. To perform the conversion from positive to negative ions we employed a Charge Exchange Cell (CEC) containing Cs vapours. The Li beam interacts with the latter in a two-step reaction, thus converting its charge from +1 to ?1. The CEC was already characterised during off-line tests; the results obtained at EXCYT confirmed both the isotopic shift effect and the efficiency values at several given extraction energies. Future improvements of the TIS and the CEC are discussed.