[en] Drift tubes filled with Ar/CF₄/CO₂ (74:20:6) were exposed to 26 MeV proton beams from the Munich Tandem accelerator to study the radiation effects and operation characteristics expected for the COMPASS experiment at CERN. Stable operation with no significant loss of gain and no significant Malter current was observed up to charge accumulations of 1.1 C/cm. For comparison, with Ar/CH₄ (90:10) the same detectors show a 23% loss of gain and large Malter currents under the same irradiation condition. For Ar/CF₄/CO₂ a thin (<0.1 μm) surface layer is observed by means of SEM on the anode wire in the irradiated detector section. As revealed by an ERDA study, the prominent components of this layer are C, O and Si

[en] At the future MAFF/FRM-II facility in Munich an ion trap system MAFFTRAP will be built. Its goal is to investigate the neutron-rich, in particular heavy, nuclei from thermal neutron fission and fusion of fission products with heavy target nuclei. Basic aims of these investigations are: radioactive beam cooling and purification for nuclear spectroscopy experiments, precise nuclear mass measurements and charged particle spectroscopy 'in-trap'

[en] The Penning-trap system MLLTRAP is designed to investigate medium-mass and heavy neutron-rich isotopes from fission, fusion and fission-fusion reactions. Foreseen as main experiments are high-precision mass measurements, as well as in-trap e- or α-spectroscopy. The set-up is presently in its construction and commissioning phase at the MLL in Garching. During on-line measurements at the Tandem accelerator reaction products will be thermalised by the MLL-IonCatcher and transfered to the traps via an RFQ cooler buncher. The MLL-Ioncatcher consists of a buffer-gas stopping cell and an RFQ-based extraction system. During on-line test using α-emitting reaction products the MLL-IonCatchers showed an overall efficiency of 10-16%. In the future it is planned to use highly charged ions, charge-bred in an EBIS, in order to obtain higher cyclotron frequencies in the Penning trap, thus improving the mass accuracy up to δm/m ≤ 10^-8. Since buffer-gas cooling is not applicable for highly charged ions the sympathetic cooling technique with Mg⁺ ions will be applied before the injection into the traps. The present status of the MLLTRAP will be presented in this poster. (orig.)

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[en] We are investigating a new concept of a buffer gas filled ion cooler built from single radio frequency (RF) ring electrodes. In such a ring electrode structure, the RF potential generates an average repelling short-range force perpendicular to the electrode surfaces. Due to the composition of single rings, the shape of the cooling channel can easily and smoothly be varied, and hence also the direction of the RF forces. As a result, the angular acceptance can be increased by a factor of two in comparison to the maximum acceptance for the present RF quadrupole coolers

[en] The MLL-IonCatcher is a new setup for the thermalization of fusion-evaporation reaction products in highly pure helium with subsequent extraction of the stopped, singly charged ions. The setup consists of a buffer-gas stopping cell and a radio frequency quadrupole (RFQ)-based extraction system and is placed at the Tandem accelerator facility of the MLL in Garching. Test experiments were performed using the α emitter ¹⁵²Er with total kinetic energies of around 180 keV/u, produced via the reaction ¹²¹Sb(³⁵Cl,4n). During the on-line measurements the number of ions entering the stopping chamber through the entrance window was determined via the detection of their specific α-decay energy. After being thermalized in the helium buffer gas at 40-140 mbar the ions were guided by a combination of electric rf and dc fields towards the extraction nozzle where the ion transport was taken over by the gas flow. Subsequent to the extraction by a supersonic gas jet the ions were separated from the buffer gas and guided by the extraction RFQ towards a Si detector, where the specific α-decay energy was detected. Depending on the electric field strength and the pressure of the buffer gas an overall efficiency including stopping and extraction between 10% and 16% has been achieved

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[en] Neutron-induced fission of uranium allows for the production of high-intensity neutron-rich radioactive ion beams. However, also large quantities of unwanted volatile radioactive species are produced that have to be hindered from contaminating the beamline and vacuum system of the facility. In the framework of radioprotection studies within the MAFF project at the FRM II in Garching with 10¹⁴ fiss/sec., the performance of a cryotrap system has been studied, designed to localize gaseous radioactivity close to its origin. These studies provide important radioprotection information for the planned EURISOL facility with 10¹⁵ fission events/sec. Design considerations, activity distribution calculations and a comparison to experimental prototype test results will be presented. (orig.)

[en] The SHIPTRAP facility at GSI will deliver cooled and purified ion bunches of heavy radionuclides produced at SHIP. A key element is the RFQ buncher. A buncher consists of four segmented rods to which rf voltages are applied to create a transversely focusing field. An electric DC field along the axis controls the longitudinal energy of the ions. The RFQ is filled with gas so that the energy of the ions entering into the linear trap will be reduced due to collisions with the gas and they will be confined at the end of the system. The ions can be extracted in a pulsed mode in bunches with high phase space density and can be delivered to a high vacuum region. (orig.)