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Secondary beams of radioactive heavy ions have been stored and cooled in a storage ring for the first time. Relativistic beams of bare l9 Ne and ,8 F ions were produced by fragmentation of 310 MeV/nucleon 20 Ne at the heavy-ion synchrotron at GSI. They were separated in flight with the highresolution forward spectrometer and injected into the storage-cooler ring. The feasibilities of in-flight lifetime and direct mass measurements for radioactive beams are demonstrated.PACS numbers: 29.20.Dh, 25.75.+r, 29.27.Eg Recently considerable progress has been made in the production and isotropic separation of secondary beams of exotic nuclei which are created by fragmentation of heavy ions in peripheral collisions [1-3]. The first experiments using relativistic secondary beams have demonstrated new possibilities for studying nuclear structure [4]. Another frontier has been opened with the advent of storage-cooler rings for heavy ions [5]. Both new experimental features are incorporated in the high-energy accelerator complex at GSI. The system consists of the synchrotron SIS [6] providing ions of all elements up to uranium with energies of up to 2 GeV/nucleon, and the experimental storage ring ESR [7] equipped with an electron-cooler facility [8]. Heavy-ion beams up to bismuth have been stored and cooled in the ESR. The cooled beams were characterized by a relative momentum spread of Ap/p < 10~5 and by a transverse emittance of £<0.1/r mmmrad [9]. The high-resolution forward spectrometer FRS [10] interconnects the synchrotron and the storage ring (see Fig. 1). It was demonstrated that the FRS efficiently separates isotopically pure fragment beams up to the heaviest projectiles extracted from the SIS.In the two pilot experiments presented here, the FRS and the ESR were combined for the first time. Secondary beams produced and separated with the FRS were injected and accumulated in the ESR. The experiments aimed at exploring two fields of research: (i) Production and accumulation of bare short-lived /3-unstable ions, followed by in-flight determination of their lifetime. This type of experiment was explored with ,9 Ne ions (half-life: T , i/2 == 17 s) as an example, (ii) Production, accumulation, and cooling of both stable and radioactive bare nuclei, followed by a precise direct mass measurement of the circulating beam. Fully ionized ,8 F ions (7^/2 = 1.8 h) were selected to demonstrate that the ESR can serve as a high-resolution spectrometer for direct mass measurements of secondary beams.In our experiments a 310 MeV/nucleon ^Ne 10 " 1 " beam was extracted from the SIS with a pulse length of about 1 s and focused onto a 4 g/cm 2 beryllium target placed at the entrance of the FRS (Fig. 1). In one SIS cycle about 2x 10 9 neon particles were extracted. As a result of reaction kinematics and the slowing-down processes in the production target, the selected fragments had a mean en-TARGET FRS PARTICLE IDENTIFICATION DETECTORS (TOF.AE) / START ESR: ELECTRON COOLER PARTICLE DETECTOR FIG. 1. Layout of the new high-energy facilit...

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A set of measurements with the CAPRICE ion source at the GSI test bench has been carried out to investigate its behavior in terms of intensity and shape of the extracted beam when the microwaves generating the plasma sweep in a narrow range of frequency (+/-40 MHz) around the klystron center frequency (14.5 GHz). Remarkable variations have been observed depending on the source and the beamline operating parameters, confirming that a frequency dependent electromagnetic distribution is preserved even in the presence of plasma inside the source. Moreover, these observations confirm that the frequency tuning is a powerful method to optimize the electron cyclotron resonance ion source performances. A description of the experimental setup and of the obtained results is given in the following.