1. Cluster-Jet Target Target TDR Alfons Khoukaz Institut für Kernphysik, WWU Münster, Germany PANDA Collaboration Meeting December 8-12, 2008

2. Targets for PANDA „Main“ Targets: Cluster-Jet-Target (H 2, D 2, N 2, Ne, Ar,...) Pellet Target (H 2, D 2, N 2, Ne, Ar,...) →common Target-TDR in preparation (final version in 2009) Further options for PANDA: Micro-Sphere Target (H 2, He) Fiber Target (C, CH 2 )

3. Requirements on the PANDA Target Areal density  ≤ 5∙10 15 H 2 atoms/cm 2 Cluster beam:8∙10 14 H-atoms/cm 2 (Münster current status) Pellet beam:5 ∙10 15 H-atoms/cm 2 (WASA-at-COSY) Continously adjustable target density Cluster beam: yes (0 –  max ) Pellet beam:hardly possible

4. Requirements on the PANDA Target Homogeneous spatial target density Cluster beam: yes Pellet beam:not possible  pellet ~ 10 19 H 2 atoms/cm 2 pellet distance ~ 5 mm (statistically distributed) → HESR beam must be blown up to mean pellet distance

5. Requirements on the PANDA Target Pointlike interaction zone Cluster beam: Ø ~ 15 mm (Münster) rectangular shape possible Pellet beam:Ø ~ 3 mm (WASA-at-COSY) to be developed Absence of time structure (detector/dead time!) Cluster beam: yes Pellet beam:no

6. Requirements on the PANDA Target ClusterPellet Maximum density Adjustable target density Homogeneous target density Pointlike interaction zone Time structure

7. Targets for PANDA Depending on the current experimental program either the Cluster-Jet Target or the Pellet Target will be the best choice high luminosity: Pellet beam high precision:Cluster beam → use of both target types for PANDA → shared usage of devices (beam dump, pumps, gas supply,...) → easy exchange of target generators desired

8. Targets for PANDA Proposal: Commissioning of PANDA with the Cluster-jet: adjustment of the accelerator beam cooling and commissioning of the detector components beginning with lowest energy losses (adjustable density) and interaction rates towards maximum values

9. Targets for PANDA Cluster-Jet Source Pellet- Source Target beam dump pbar PANDA Detector gas supply slow control pumping system vacuum pipe system pumping system gas regeneration

10. Contributions/Responsibilities Cluster-Jet Source WWU, GSI Pellet Source FZJ, ITEP, MPEI Pellet Tracking System UU, FZJ Target Beam Dump INFN, GSI, FZJ, WWU Vacuum Pipe System FZJ, GSI, WWU, INFN Gas Supply System SMI, WWU, GSI, FZJ Slow Control System SMI, INFN, GSI Mechanical Interface FAIR+GSI Safety System FAIR

11. Target TDR Target TDR currently in preparation Combined Cluster/Pellet TDR Expected to be ready in spring/summer 2009 Information on this meeting about Cluster-Jet Generator (this talk) Pellet Generator (talk by M. Büscher) Target beam dump and vacuum (talk by A. Gruber)

12. Production of Cluster-Jet Beams Expansion of compressed, pre-cooled gas through a fine nozzle (e.g. H 2, 20 K, 18 bar) → formation of a super- sonic cluster-jet beam CERN nozzle

13. Production of Cluster-Jet Beams Preparation of a cluster-jet beam by a set of two skimmers behind the nozzle Constant opening angle of the cluster-jet after the second skimmer cluster beam

14. Example for a Gas Supply System

15. Production of Cluster-Jet Beams nozzle exit maximum gas velocity given by gas temperature/pressure before entering the nozzle position of minimum diameter in the nozzle

16. Cluster Beam Velocities Velocity measurements in Münster: Single-cluster ionisation by a pulsed electron beam Detection of ionized clusters by a channeltron Velocity determination using by time-of- flight method (flight path ~ 3 m) Determination of cluster velocities as function of gas temperature/pressure

17. Cluster Beam Velocities Cluster velocities as function of T gas (p=const.) crossing of the vapour pressure curve

18. Highest Cluster Beams Densities „Speciality“ of the Münster-type targets: Operation in the fluid regime before entering the nozzle target particle flow in the scattering chamber

19. Adjustment of Cluster Beam Densities Easy density adjustment during operation by changing the nozzle temperature T gas (see below) or the gas pressure p gas 3 orders of magnitude cluster beam density

20. Cluster Beam Densities (Status) CELSIUS E835 FERMILAB Genova/GSI ANKE and COSY-11 Münster nozzle diameter 100 µm37 µm26 µm11-16 µm11-28 µm gas temperature 20-35 K20-32 K28-35 K22-35 K20-35 K gas pressure1,4 bar<10 bar10-20 bar18 bar>18 bar distance from nozzle 0,32 m0,26 m 0,65 m 2,1 m = PANDA geomety! target density1,3x10 14 cm -2 3x10 14 cm -2 >1x10 15 cm -2 >>1x10 14 cm -2 8x10 14 cm -2 even higher densities expected for the PANDA Cluster-Source Prototype

21. Cluster Beam Density Distribution Ø ~ 15 mm Homogeneous volume density Size of cluster beam adjustable (skimmer) beam profile measured at a distance of l ~ 2.1 m behind the nozzle (PANDA geometry) areal density distribution

22. Cluster Beam Density Distribution Cluster-Jet shape adjustable by skimmers →special beam geometries at the PANDA interaction point possible (e.g. 15 mm x 3 mm) microscopic view of the skimmer opening special skimmer (laser cut)

23. Cluster Beam Adjustment skimmer Adjustment of the target beam during beam operation by a set of movable skimmers used for adjustment of the cluster-jet after installation

24. The PANDA Cluster-Source Prototype

25. nozzle cooling Münster: horizontal cluster beam direction PANDA Cluster-Source Prototype (Münster)

26. The PANDA Cluster-Source Prototype roots pumps cluster-jet source

27. The Münster Cluster-Target scattering chamber vacuum beam pipe cluster beam dump detection system (velocity/mass) cluster source behind the wall

28. The Münster Cluster-Target: Beam Dump shutter cryopumps detection system (velocity/mass) cluster beam

29. Integration at PANDA roots pumps forepump cluster source anti-protons

30. top view anti-protons

31. side view shutter anti-protons

33. Next Activities Measurements towards highest Cluster-jet densities Studies on cluster beam properties (mass, velocity) Nozzel and skimmer developments TDR

34. Summary