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We present results from the development towards the Time-of-Flight Laser Ion Source (ToF-LIS) aiming for the suppression of isobaric contaminants through fast beam gating. The capability to characterize high resistance ion sources has been successfully demonstrated. A ninefold selectivity gain has been achieved through suppression of surface ionized potassium, while maintaining >90% transmission for laser-ionized gallium using a thin wall graphite ionizer cavity combined with a fast beam gate. Initial results from the investigation of glassy carbon as a potential hot cavity ion source are presented. Power-cycle tests of a newly designed mount for fragile ion source cavities indicates its capability to survive the thermal stress expected during operation in an ISOLDE target unit. Finally, we introduce fast ion beam switching at a rate of 10 kHz using the ISOLDE ion beam switchyard as a new concept for ion beam distribution and conclude by highlighting the potential applications of this ion beam multiplexing technique. [ABSTRACT FROM AUTHOR]

ISOLDE’s high-resolution isotope separator was recomissioned in mid 2000, after a period out of service. Since then the separator has routinely run with a mass resolution of 3000–4500, and during 2001 it delivered 72% of ISOLDE’s radioactive output. A concerted effort has been made to understand the ion optics and optimise performance. In this paper we present an overview of the HRS, and investigate the factors which limit the attainable mass resolution: ion-source emittance, optical aberrations, beam instrumentation and magnet stability. [Copyright &y& Elsevier]

The production rates of neutron-rich fission products for the next-generation radioactive beam facility EURISOL [EU-RTD Project EURISOL (HPRI-CT-1999-50001)] are mainly limited by the maximum amount of power deposited by protons in the target. An alternative approach is to use neutron beams to induce fission in actinide targets. This has the advantage of reducing: the energy deposited by the proton beam in the target; contamination from neutron-deficient isobars that would be produced by spallation; and mechanical stress on the target. At ISOLDE CERN [E. Kugler, Hyperfine Interact. 129 (2000) 23], tests have been made on standard ISOLDE actinide targets using fast-neutron bunches produced by bombarding thick, high-Z metal converters with 1 and 1.4 GeV proton pulses.This paper reviews the first applications of converters used at ISOLDE. It highlights the different geometries and the techniques used to compare fission yields produced by the proton beam directly on the target with neutron-induced fission. Results from the six targets already tested, namely UC2/graphite and ThO2 targets with tungsten and tantalum converters, are presented.To gain further knowledge for the design of a dedicated target as required by the TARGISOL project [EU-RTD Project TARGISOL (HPRI-CT-2001-50033)], the results are compared to simulations, using the MARS [N.V. Mokhov, S.I. Striganov, A. Van Ginneken, S.G. Mashnik, A.J. Sierk, J. Ranft, MARS code developments, in: 4th Workshop on Simulating Accelerator Radiation Environments, SARE-4, Knoxville, USA, 14–15.9.1998, FERMILAB-PUB-98-379, nucl-th/9812038; N.V. Mokhov, The Mars Code System User’s Guide, Fermilab-FN-628, 1995; N.V. Mokhov, MARS Code Developments, Benchmarking and Applications, Fermilab-Conf-00-066, 2000; O.E. Krivosheev, N.V. Mokhov, A New MARS and its Applications, Fermilab-Conf-98/43, 1998] code interfaced with MCNP [J.S. Hendrics, MCNP4C LANL Memo X-5; JSH-2000-3; J.F. Briemesteir (Ed.), MCNP – A General Montecarlo N-Particle Transport Code, Version 4C, LA-13709-M] libraries, of the neutron flux from the converters interacting with the actinide targets. [Copyright &y& Elsevier]

For the first time, the laser resonance photo-ionization technique has been applied inside a FEBIAD-type ion source at an ISOL facility. This was achieved by combining the ISOLDE RILIS with the ISOLDE variant of the FEBIAD ion source (the VADIS) in a series of off-line and on-line tests at CERN. The immediate applications of these developments include the coupling of the RILIS with molten targets at ISOLDE and the introduction of two new modes of FEBIAD operation: an element selective RILIS mode and a RILIS + VADIS mode for increased efficiency compared to VADIS mode operation alone. This functionality has been demonstrated off-line for gallium and barium and on-line for mercury and cadmium. Following this work, the RILIS mode of operation was successfully applied on-line for the study of nuclear ground state and isomer properties of mercury isotopes by in-source resonance ionization laser spectroscopy. The results from the first studies of the new operational modes, of what has been termed the Versatile Arc Discharge and Laser Ion Source (VADLIS), are presented and possible directions for future developments are outlined. [ABSTRACT FROM AUTHOR]

Abstract: Isotope yields at ISOLDE are regularly measured online (with dedicated gamma and beta detectors) and off line by implantation and subsequent alpha-, beta- or gamma spectroscopy. The Java based measurement software, dedicated to tape station measurements, has been updated in order to automate yield measurements and provide possibilities to repeat existing measurements. A procedure supported by dedicated programs was established to analyze data. The results are centrally stored and provide an interface to the existing ISOLDE yield database. The present ISOLDE yield database has been recently created and updated with a large number of yields compiled from published data. The database developed on ORACLE guarantees reliability and security and provides a simple way of compiling new information. A user oriented interface has been programmed allowing accessing the information via a web browser. Several levels in the database structure provide selective access to different layers of technical information for advanced users and for technical R&D. The improvements in the yield measurement procedure, the data storage and accessibility, as well as the new database structure, the web application and the access interfaces, enhance the communication between technical information like yields and the users of the ISOLDE facility. [Copyright &y& Elsevier]

Abstract: At ISOLDE, target units are exposed to a driver beam from the CERN proton-synchrotron booster (PSB) with a highly pulsed structure. The instantaneous power during a bunch from the PSB is 12GW, more than six orders of magnitude higher than the average power on target of 3kW during a typical physics run in standard beam mode. Observable effects on early liquid metal target units exposed to the PSB pulsed beam included flow of liquid metal into the ion source, broken welds and corroded proton beam windows. To reduce the energy densities for liquid metal target units, the current practice is to spatially defocus the beam and apply a time-staggered extraction mode to the four PSB bunches. Hydrodynamic simulations to qualitatively assess proton-induced transient thermo-mechanical effects such as splashing were carried out with the aim to further improve ISOLDE liquid metal target release properties and lifetimes and to benchmark EURISOL. [Copyright &y& Elsevier]

Abstract: Among the multiple progresses in radioactive ion beam (RIB) manipulation for physics experiments, the beam cooling and bunching in gas-filled RF traps has become a widely used technique. It is particularly well adapted to precision experiments, such as Penning trap mass spectrometry or collinear laser spectroscopy. At ISOLDE, an rf quadrupole cooler and ion buncher (RFQCB) has been designed and developed to deliver radioactive beams of improved quality among most of the on-line experiments. The results of the first off-line tests have shown that high transmission efficiencies could be achieved with different RIBs of alkali metals, as it was expected. During the later tests that are presented here a special care was dedicated to the reproduction of the on-line experimental conditions of ISOLDE, with a wide range of different RIBs. This contribution will present the latest off-line tests. [Copyright &y& Elsevier]