The SPES laser ion source has been tested at ISOLDE Offline 2, CERN. A two-step single resonance photo-ionization scheme has been used to ionize gallium atoms in the SPES tantalum hot-cavity ion ...source. The ion beam time structure, laser enhancement of ion yield, and ionization efficiency are investigated in relation to the ion source temperature and ion load. From the time structures, it is inferred that a significant fraction of the extracted ions are generated in the transfer line rather than just in the hot cavity. The effect of the electrostatic axial field on the movement of ions inside the ion source is discussed. Generally, there is an inverse relationship between total ion load and the laser enhancement factor. This dependency is enhanced at lower operating temperature of the ion source. This is explained by the influence of thermionic electron emission and ion density on the transverse laser-ion confinement, and therefore the survival of ions as they drift towards the extraction region of the ion source. At 2200 °C, the nominal temperature for on-line operation of the ion source, the ratio of laser-ionized to surface-ionized gallium was stable around 55 during the measurement campaign, and independent of the total extracted ion current up to the measured value of 1.1 μA. A resonance laser ionization efficiency value of 27.2% for gallium has been measured.
Over the past decades many accelerator facilities have been built in order to produce radioactive nuclei. Among the falcility under construction, SPES (Selective Production of Exotic Species) is the ...Italian ISOL (Isotope Separation On Line) facility in the installation phase in these years in the Laboratori Nazionali di Legnaro. The innovative aspect of this facility is that the radioactive beam produced by fission induced by the proton beam, produced by a high power cyclotron, interact with a multi-disks uranium carbide target. The formed RIB will be sent directly to the low energy experimental area and, afterwards, to the post-acceleration complex. Currently the installation program concerning the SPES RIB source provides the set-up of the apparatus around the production bunker. The main objective of SPES project is to provide, in the next years, the first low-energy radioactive beams for beta decay experiments using the b-DS (beta Decay Station) set-up and for radiopharmaceutical applications by means of the IRIS (ISOLPHARM Radioactive Implantation Station) apparatus. In this work, all the specific issues related to the SPES RIB and the Low Energy beam lines will be reported. The main RIB systems, such as ion source systems, target-handling devices and the installation of low energy transport line, will be presented in detail.
Abstract A two-step resonance photo-ionization scheme has been used to ionize samarium atoms in the SPES tantalum hot-cavity ion source. The effect of the ion load on the ion beam time structure and ...the laser enhancement of the ion yield has been studied at different ion source temperatures. Generally, the introduction of more positive ions (ion load) affects negatively the overall confinement of the laser ions inside the volume of the ion source. Possible enhancement of the laser ion confinement through the introduction of neutrals is observed as well. The ion load is also observed to affect the confinement in the transfer line much more than in the hot cavity. Measurement of the time structure with inverted polarity of the cavity DC heating supply confirmed the significance of the longitudinal potential for ion extraction. The laser enhancements of the ion yield are found to be sensitive to the ion load at low operating temperature of the ion source i.e. 1800°C, whereas at 2050°C and 2200°C, they are relatively stable till an ion load value of 1.2 µA.
The next years will see the completion of the radioactive ion beam facility SPES (Selective Production of Exotic Species) and the upgrade of the accelerators complex at Istituto Nazionale di Fisica ...Nucleare – Legnaro National Laboratories (LNL) opening up new possibilities in the fields of nuclear structure, nuclear dynamics, nuclear astrophysics, and applications. The nuclear physics community has organised a workshop to discuss the new physics opportunities that will be possible in the near future by employing state-of-the-art detection systems. A detailed discussion of the outcome from the workshop is presented in this report.
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