Heavy ion guide: beam transport and diagnostics

Our present plans for a heavy-ion guide system are based on developments at Argonne National Laboratory (ANL) [1]. For the heavy-ion guide, preselection of ions will be done using a superconducting solenoid similar to that being used now in the BigSol spectrometer. Earlier tests with a 1 m long gas cell at low input intensities (below 10 ion/sec) have been carried out at ANL with beams up to 4 MeV/A and at GSI with initial beams of 280 MeV/A to check the stopping efficiency. Consistent results with stopping and extraction efficiencies close to 40% have been obtained in both tests with realistic pressures of 100 to 200 mbar and helium pumping speeds less than 3000 m/hr. Similar results, but with significantly higher load, up to 10 ion/sec, were obtained on a modified ANL gas catcher (RIA gas catcher prototype) [2]. This is very important result, since using deep inelastic collisions, we expect high production rates for a large range of secondary ions [3]. Currently complete set of parts for two similar gas catchers are being manufactured for ANL and TAMU. After extraction from the gas cell 1+ ions will be delivered to the charge breeding ECR source where they will be stripped to a high charge state and then the highly charged ions will be injected into and accelerated by the K500 cyclotron. Starting from the original production of radioactive species and after, including collection, extraction and transport to the injection point, we need to control the efficiencies of each stage.