1. FP6 Design study "DIRAC secondary beams" Project "NUSTAR":Experiments with stored radioactive beams Super-FRS high-power production target has to cover two totally different regimes: 1.Slow extraction: ≈ 1 second spills, P = 12 kW 2.Fast extraction: ≈ 50 ns spills, P = 12 kJ/50 ns = 240 GW! Task 6: High-power production targets for fast-extracted beams K.Sümmerer (GSI)

2. FP6 Design study "DIRACsecondary beams" Project "NUSTAR":Experiments with stored radioactive beams Task 6: High-power production targets for fast-extracted beams Delivrables: Conceptual design Target Wheel (month 24) Conceptual design Liquid-Metall Target (month 36) Prototype Liquid-Metall Target (month 36) Goals of Task 6: "Research and development to handle the energy deposition of high- intensity primary beams in the production target" "Design and prototype construction of a rotating target wheel" "Feasibility study and prototype construction of a liquid-metal target"

3. Super-FRS target for slow extraction FacilityBeamTotal Beam Energy E [kJ] Target Thickness [g cm -2 ] Deposited Energy ΔE [kJ] Specific Energy ΔE/M [kJ/g] PSIprotons 1x10 16 /s 100010.8540.18 Super-FRS*all ions 1x10 12 /s  40 1.0 – 8.0  12  0.17 * beam energy 1 A GeV, beam spot radius of 1 mm, target (r t = 15 cm) rotates with 60 rpm, beam hits target at r b = 14 cm. PSI rotating graphite wheel is a suitable model for Super-FRS target for slow extraction! Key parameters: radiation cooled (T = 1430 C) 1 year continuous reliable operation (since 1990) proven safe handling concepts (plug system, vertical access)

4. PSI target for slow extraction (G.Heidenreich, PSI) PSI Target E Vertical plug handling concept at Super-FRS

5. Work plan for NUSTAR1 / Task 6 Rotating graphite wheel target:  Explore theoretical concepts of energy deposition/transport  Engineering design  Calculate temperature response of realistic geometry  Prototype for long-term/beam testing  Radiation damage/annealing  Media connection, shielding, handling, repairs GSI

6. Super-FRS targets for fast extraction Key parameters: pulse length 50 ns (  beam interaction with nominal target thickness) instantaneous power: 12 kJ/50 ns  240 GW small beam spot & high power density  solids not (always) feasible Possible solutions: 1.graphite wheel as fall-back solution for low beam powers/larger beam spots 2.investigate windowless liquid-metal jet target (like ANL/RIA, ν-factories) Liquid Li seems to be the most favorable metal! Open questions:  damage due to shock waves?  Li contamination of beam tube, diagnostic detectors etc.  constancy of jet  safety issues

7. Response of liquid-Li jet to fast SIS pulses 2-dim. BIG-2 calculations by N. Tahir:  T max on beam trajectory: 13 000 K  evaporated Li is ejected in/against beam direction with v 0 = 10 km/s  shock front travels with 1.5 km/s perpendicular to beam direction  shock pressure still 2 GPa after 1 μs t o = 50 nst 1 = 1 μs

8. Work plan for NUSTAR1 / Task 6 Liquid-metal jet target:  3-dim. hydro-dynamical calculations; comparison to 2-dim. calculations  Define beam spot size where Li does not vaporize  Feasibility study (water model, Na model)  Prototype Li loop  Technical (safety and vacuum) concept (incl. handling) FZK

9. Task 6 "NUSTAR1" Cost Table NUSTAR1 GSIFZK totalEC Contr.totalEC Contr. Personnel48 PM24 PM48 PM24 PM Consumables140 k€70 k€ Total462 k€231 k€492 k€246 k€