The generation of intense ion beams from high-intensity laser-generated plasmas has been the focus of research for the last decade. In the LIGHT collaboration the expertise of heavy ion accelerator scientists and laser and plasma physicists has been combined to investigate the prospect of merging these ion beams with conventional accelerator technology and exploring the possibilities of future applications. We report about the goals and first results of the LIGHT collaboration to generate, handle and transport laser driven ion beams. This effort constitutes an important step in research for next generation accelerator technologies.

After the successful commissioning of the radioactive beam experiment at ISOLDE (REXISOLDE) —an accelerator for exotic nuclei produced by ISOLDE— in 2002 and the promotion to a CERN user facility in 2003, first physics experiments using these beams were performed. Initial experiments focused on the region of deformation in the vicinity of the neutron-rich Na and Mg isotopes. Preliminary results on the neutron-rich Na and Mg isotopes show the high potential and physics opportunities offered by the exotic isotope accelerator REX in conjunction with the modern Germanium γ spectrometer MINIBALL.

After the successful commissioning of the Radioactive beam EXperiment (REX) at ISOLDE (CERN) in 2002, first physics experiments were performed in 2003 which focussed on the neutron-rich Mg isotopes in the vicinity of the “island of inversion”. After introducing the REX facility and the modern γ spectrometer MINIBALL first preliminary results will be presented showing the high potential and physics opportunities offered by this new radioactive beam facility.

Cooling of radioactive ion beams in a Penning trap is an essential component of the post-accelerator REX-ISOLDE at CERN. Prior to their charge-breeding and acceleration, ions from the on-line mass separator ISOLDE are accumulated, cooled and bunched with REXTRAP. This beam preparation provides short ion pulses with low emittance, key ingredient for a high efficiency of REX-ISOLDE. Two different cooling techniques have been investigated with REXTRAP. Both rely on the use of a buffer gas as the coolant but differ in the way the transversal compression of the stored ion cloud is achieved. Sideband cooling with a light buffer gas as coolant is the standard technique used at REXTRAP so far. With this technique an efficiency of about 45% for the injection, cooling, and extraction process has been obtained for stable and radioactive ions. For about 105 simultaneously stored ions the resulting emittance of the extracted ion pulses is about 10πmm mrad at 30 keV beam energy. For much larger numbers of ions shifts of the resonance frequency of the sideband excitation are observed together with an emittance growth. As an alternative to sideband cooling a “rotating wall” technique was tested. First results with rotating dipole as well as quadrupole fields are presented.

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy of 2.25 MeV/u together with a thin (nat)Ni target, Coulomb excitation of the first excited 2+ states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation gamma-ray yields the B(E2;0(+)gs-->2(+)1) value of 30Mg was determined to be 241(31)e2 fm4. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope 30Mg resides outside the "island of inversion."

We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg ions accelerated to an energy of 2.25 MeV/u together with a thin Ni target, Coulomb excitation of the first excited 2 states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative de-excitation γ ray yields the B(E2; 0gs → 2 + 1 ) value of Mg was determined to be 241(31) e2fm. Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the theoretical conjecture that the neutron-rich magnesium isotope Mg lies still outside the “island of inversion”. PACS numbers: 25.70.De, 27.30.+t, 21.10.Re

A new Penning‐Malmberg trap using a 5 tesla magnetic field and a cryogenic electrode structure (T∼10K) has been constructed with the goal of producing large (N ⩾ 1010), high‐density positron plasmas and cold positron beams (Δe ∼ 1 meV). With background pressures ⩽ 10−11 torr and rotating electric fields to counteract plasma expansion due to background asymmetries, this trap is designed to be a nearly ideal reservoir of positrons with very long confinement and annihilation times. This paper describes recent experiments using electron plasmas to optimize confinement and plasma compression, and minimizing the diameters of extracted beams. Further, it is shown that this trap will be an excellent device in which to study the physics issues associated with a recently proposed multi‐cell trap.

REX-ISOLDE [1] is a post-accelerator situated at the ISOLDE radioactive ion beam facility placed at CERN, Geneva. It’s main aim is to increase the energy of light (A < 50) radioactive ions from 60 keV to 0.8–2.2MeV/u. REX—ISOLDE uses a new concept of post-acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In a first step the radioactive ions are captured in a large gas-filled Penning trap. The task is to accumulate, cool and bunch the beam and prepare it for the injection into an electron beam ion source (EBIS). Cooling of the ions is achieved by collisions with a buffer gas and an efficient side band cooling mechanism by applying an rf field with a frequency equal to the cyclotron frequency of the desired ion species. The ions are then transported to an EBIS, where there charge state will be increased from 1+ to n+. For an efficient acceleration in the LINAC a charge to mass ratio of 1/4.5 is desired. After charge breeding the ions are extracted from the EBIS and re-accelerated to an energy of 5keV/u.

In 2001 the linear accelerator of the Radioactive beam EXperiment (REX-ISOLDE) delivered for the first time accelerated radioactive ion beams, at a beam energy of 2 MeV/u. REX-ISOLDE uses the method of charge-state breeding, in order to enhance the charge state of the ions before injection into the LINAC. Radioactive singly-charged ions from the on-line mass separator ISOLDE are first accumulated in a Penning trap, then charge bred to an A/q<4.5 in an electron beam ion source (EBIS) and finally accelerated in a LINAC from 5 keV/u to energies between 0.8 and 2.2 MeV/u. Dedicated measurements with REXTRAP, the transfer line and the EBIS have been carried out in conjunction with the first commissioning of the accelerator. Thus the properties of the different elements could be determined for further optimization of the system. In two test beam times in 2001 stable and radioactive Na isotopes (23Na–26Na) have been accelerated and transmitted to a preliminary target station. There 58Ni- and 9Be- and 2H-targets have been used to study exited states via Coulomb excitation and neutron transfer reactions. One MINIBALL triple cluster detector was used together with a double sided silicon strip detector to detect scattered particles in coincidence with γ-rays. The aim was to study the operation of the detector under realistic conditions with γ-background from the β-decay of the radioactive ions and from the cavities. Recently for efficient detection eight tripple Ge-detectors of MINIBALL and a double sided silicon strip detector have been installed. We will present the first results obtained in the commissioning experiments and will give an overview of realistic beam parameters for future experiments to be started in the spring 2002.

During the last two years, the performance of the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN (Geneva) has been considerably enhanced. Many technical improvements have been completed (i) to access nuclides that are produced in minute quantities of only 100 ions s−1, (ii) to increase the relative mass accuracy to ≤ 1 × 10−8 and (iii) to make accessible nuclei with a half-life of down to ≈ 5 ms. The major steps are presented, in particular the recent implementation of a magnetron phase locking mechanism which results in a significant reduction of the duration of ISOLTRAP's cyclotron measurements.

The post-accelerator REX-ISOLDE at ISOLDE/CERN will deliver radioactive ion beams with energies up to 2.2 MeV/u. For this purpose, a Penning trap and an electron-beam ion source are combined with a linear accelerator. REXTRAP-a large gas-Filled Penning trap-has started its commissioning phase. First tests have shown that REXTRAP is able to accumulate, cool and bunch stable ISOLDE ion beams covering a large mass range. Fulfilling the REX-ISOLDE demands, it can handle beam intensities from a few hundred up to 1 x 10(6) ions per pulse at repetition rates up to 50 Hz. (C) 2002 Published by Elsevier Science B.V.

The properties of radioactive ion beams produced by the present on-line target ion source technology are often not suitable for direct post acceleration. For that purpose pulsed and cooled beams of higher charged ions are required. In the case of REX-ISOLDE, the post accelerator at the CERN-ISOLDE radioactive beam facility, a unique system for beam preparation is used. it consists of a gas-filled cylindrical Penning trap (REXTRAP) for bunching and cooling followed by an electron beam ion source for charge state breeding. The Penning trap has been successfully operated with an efficiency of up to 40% and a total number of up to 10(7) ions stored. Buffer-gas sideband cooling at the ions' cyclotron frequency is employed for centering of the ions in the trap. Space charge effects have been observed if more than 10(5) ions are stored. The main effects are frequency shifts for the centering frequency. They can not be explained by simple single ion trap theory, but can be reproduced in simulations.

The WITCH (Weak Interaction Trap for CHarged particles) experiment is a retardation spectrometer coupled to a Penning trap and measures the beta-neutrino angular correlation via the shape of the recoil energy spectrum. The present form of the Standard Model describes weak processes in terms of vector and axial-vector type interactions, but the possible presence of scalar and tensor interactions is not yet ruled out. The main aim of this experiment is a test of the Standard Model for possible admixture of scalar and tensor currents.

The beam quality of radioactive ion beams produced by present target ion source technology is often not sufficient for direct post-acceleration. Furthermore, pulsed beams insure a more efficient use of an accelerator. In the case of REX-ISOLDE, the post accelerator at the CERN ISOLDE facility, a gas-filled Penning trap (REXTRAP) has been chosen for accumulation of the radioactive ions and conversion into cooled bunches. Radial centering of the ions is achieved by applying an rf field with a frequency equal to the cyclotron frequency of the desired ion species. The efficiency achieved in the first tests with different isotopes covering nearly the entire mass range was already >20%. Going to total numbers of >105 stored ions in the trap a shift of the centering frequency could be observed, which is most likely due to space charge effects. Despite this, it was possible to accumulate up to 107 ions and deliver them as cooled bunches.

Mass selective buffer gas cooling is a technique used for ions that are stored in a Penning trap. The technique can be applied to all elements and the mass resolving power achieved has proven to be sufficient to resolve isobars. When not only a few but 106 and more ions are stored at the same time, space charge starts to play a dominant role for the spatial distribution. In addition, the observed cyclotron frequency is shifted. This work investigates these effects by numerical calculations.

The experiment described here Rill search for deviations from the V-A structure of the standard electroweak model. It is based on measuring the recoil energy spectrum in nuclear beta decay which is determined by the electron-neutrino angular correlation. For pure Fermi decays this is exactly known in the standard model and any deviation will point to additional scalar interaction. The experiment consists of a Penning trap coupled to a retardation spectrometer to measure the energy of the recoiling daughter nuclei. The current status will be presented.

The Radioactive Beam Experiment REX-ISOLDE [1–3] is a pilot experiment at ISOLDE (CERN) testing the new concept of post acceleration of radioactive ion beams by using charge breeding of the ions in a high charge state ion source and the efficient acceleration of the highly charged ions in a short LINAC using modern ion accelerator structures. In order to prepare the ions for the experiments singly charged radioactive ions from the on-line mass separator ISOLDE will be cooled and bunched in a Penning trap, charge bred in an electron beam ion source (EBIS) and finally accelerated in the LINAC. The LINAC consists of a radiofrequency quadrupole (RFQ) accelerator, which accelerates the ions up to 0.3 MeV/u, an interdigital H-type (IH) structure with a final energy between 1.1 and 1.2 MeV/u and three seven gap resonators, which allow the variation of the final energy. With an energy of the radioactive beams between 0.8 MeV/u and 2.2 MeV/u a wide range of experiments in the field of nuclear spectroscopy, astrophysics and solid state physics will be addressed by REX-ISOLDE.

Accelerating radioactive ions to several MeV/u opens up new interesting experimental fields in nuclear physics. To produce such beams at the ISOLDE facility at CERN REX-ISOLDE will post-accelerate the existing radioactive ion beams from 60 keV to up to 2.2 MeV/u. For an efficient use of the continuous ISOLDE beam an ion buncher system has been set up. It consists of a large gas filled Penning trap for accumulation and a pulsed release of the ions, allowing cooling and purification of the beam as well.