T. Giles

On-line yields obtained with the ISOLDE RILIS

The ISOLDE resonance ionization laser ion source (RILIS) allows to ionize efficiently and selectively many metallic elements. In recent yield surveys and on-line experiments with the ISOLDE RILIS we observed 23–34 Mg, 26–34 Al, 98–132 Cd, 149 Tb, 155–177 Yb, 179–200 Tl, 183–215 Pb and 188–218 Bi. The obtained yields are presented together with measured release parameters which allow to extrapolate the release efficiency towards more exotic (short-lived) nuclides of the same elements. 2002 Elsevier Science B.V. All rights reserved.

Oxide fiber targets at ISOLDE

Abstract Many elements are rapidly released from oxide matrices. Some oxide powder targets show a fast sintering, thus losing their favorable release characteristics. Loosely packed oxide fiber targets are less critical since they may maintain their open structure even when starting to fuse together at some contact points. The experience with various oxide fiber targets (titania, zirconia, ceria and thoria) used in the last years at ISOLDE is reviewed. For short-lived isotopes of Cu, Ga and Xe the zirconia and ceria targets respectively provided significantly higher yields than any other target (metal foils, oxide powders, etc.) tested before. Titania fibers, which were not commercially available, were produced in a relic process by impregnation of a rayon felt in a titanium chloride solution and subsequent calcination by heating the dried felt in air. Thoria fibers were obtained either by the same process or by burning commercial gas lantern mantle cloth. In the future a beryllia fiber target could be used to produce very intense 6He beams (order of 1013 ions per second) via the 9Be(n,α) reaction using spallation neutrons.

Production yields of noble-gas isotopes from ISOLDE UCx/graphite targets

Yields of He, Ne, Ar, Kr and Xe isotopic chains were measured from UCx/graphite and ThCx/graphite targets at the PSB-ISOLDE facility at CERN using isobaric selectivity achieved by the combination of a plasma-discharge ion source with a water-cooled transfer line. The delay times measured for a UCx/graphite target allow for an extrapolation to the expected yields of very neutron-rich noble gas isotopes, in particular for the NuPECC reference elements Ar and Kr, at the next-generation radioactive ion-beam facility EURISOL. (C)2003 Elsevier Science B.V. All rights reserved.

ISOLDE beams of neutron‐rich zinc isotopes: yields, release, decay spectroscopy

Intense radioactive ion beams of the neutron‐rich zinc isotopes 69–81Zn have been produced at the isotope separation on‐line facility ISOLDE at CERN. The combined use of spallation‐neutron induced fission of 238UCx targets and resonant laser ionization provided sufficient suppression of disturbing isobars (mainly gallium and rubidium) to perform decay spectroscopy up to 81Zn.

The high resolution spectrometer at ISOLDE

Abstract 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.

11Be(beta-p), a quasi-free neutron decay?

We have observed beta(-)-delayed proton emission from the neutron-rich nucleus Be-11 by analyzing a sample collected at the ISOLDE facility at CERN with accelerator mass spectrometry (AMS). With a branching ratio of (8.3 +/- 0.9). 10(-6) the strength of this decay mode, as measured by the B-GT-value, is unexpectedly high. The result is discussed within a simple single-particle model and could be interpreted as a quasi-free decay of the Be-11 halo neutron into a single-proton state.

Radioactive ion beams at ISOLDE/CERN recent developments and perspectives

Since the move of ISOLDE from CERN’s synchrocyclotron (SC) to the Proton Synchrotron Booster (PSB) in 1992 extensive work has been devoted to the development of new beams, i.e. the production of new isotopes, beams of higher intensity and the ionization of further elements. Most of these developments were driven by the particular needs of the physics community proposing new experiments. The main achievements were the adaption of liquid metal targets to the pulsed proton beam to prevent shockwaves and splashing inside the target container and systematic studies on the time structure of the release of the isotopes from the target. Furthermore the work on laser ion-sources already started at ISOLDE-2 was continued, the so-called RIST target was developed, and most recently first tests on the isotope production while increasing the proton energy from 1 GeV to 1.4 GeV were done. The latter topics are discussed in this paper.

RIB production test at ISOLDE with 600 MeV protons

The energy dependence of production yields for Kr and Cs isotopes has been investigated with 600 MeV, 1 GeV and 1.4 GeV protons.

Measurement of the production cross-sections of neutron-rich Kr and Xe isotopes

Several scientific committees, such as NUPECC [1], have established that neutron-rich beams will provide a wealth of new opportunities for nuclear physics studies. The proton-induced fission of actinide material is a proven mechanism for the production of neutron-rich nuclei, but, within the Eurisol project [2], new innovations are being tested with the goal of increasing current fission rates by three orders of magnitude.