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Target and Production MUTAC 21 July 1999 C.D. Johnson CERN

Target and Production MUTAC 21 July 1999 C.D. Johnson CERN. Physics aspects Pion production versus proton energy and material Production beam Capture Engineering aspects Target damage - thermal, mechanical. chemical, dynamical Target options and choice of material

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Target and Production MUTAC 21 July 1999 C.D. Johnson CERN

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  1. Target and ProductionMUTAC 21 July 1999 C.D. Johnson CERN Physics aspects Pion production versus proton energy and material Production beam Capture Engineering aspects Target damage - thermal, mechanical. chemical, dynamical Target options and choice of material Beam dump Activation and shielding Containment

  2. Target and ProductionMUTAC 21 July 1999 cdj We aim to collect and deliver to the first phase rotation channel 0.6 pions of each sign per proton of 16 GeV/c. In the region of low kinetic energy shown opposite this can be achieved by immersing the production target in a 20 T solenoid field of 75 mm radius. Pions of both signs having transverse momentum of up to 225 GeV/c are focused into the decay channel via the matching channel. Note that the pion velocity varies from 0.68 to 0.98 16 GeV/c protons on tungsten dN/dT per GeV per interacting proton Collect from this region Pion kinetic energy, T, in GeV From: H. Kirk

  3. Target and ProductionMUTAC 21 July 1999 cdj Meson yield ( + ) from different in a solenoid field, B of aperture, Ra as calculated by the MARS code Atomic mass A Solenoid field B, (T) Target radius (cm) Tilt angle  (mrad)

  4. Target and ProductionMUTAC 21 July 1999 cdj

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  6. Target and ProductionMUTAC 21 July 1999 cdj FLUKA98 pion production J. Collot, ISN Grenoble

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  8. Target and ProductionMUTAC 21 July 1999 cdj Preliminary - H. Kirk

  9. Target and ProductionMUTAC 21 July 1999 cdj H. Kirk

  10. Target and ProductionMUTAC 21 July 1999 cdj H. Kirk

  11. Target and ProductionMUTAC 21 July 1999 cdj Production beam: Fast cycling synchrotron Pulse repetition rate:15 Hz Bunch length: z = 1 ns(to preserve polarization) Intensity: 5 1013 p/ bunch(two bunches per pulse) Beam momentum:16 GeV/c( production vs machine issues) Beam size at target: r = 4 mm Power in Beam: 4 MW Power absorbed in target: 400 kW Energy deposited in target: 27 kJ per pulse Peak energy density in beam: 5kJ mm-2 per pulse (ACOL beam was: 12 x greater)

  12. Target and ProductionMUTAC 21 July 1999 cdj Schematic of target station - liquid metal jet is injected in beam direction and is collected in a reservoir that also absorbs a large fraction of the dumped beam power

  13. pions mercury dump

  14. Target and ProductionMUTAC 21 July 1999 cdj CERN High power targetry for pbar production - solid target CERN and Fermilab gained considerable experience in coping with target damage A liquid mercury jet target was built but never used

  15. Target and ProductionMUTAC 21 July 1999 cdj proton beam B= 20 T Hg jet Schematic of beam/target interaction region. Hg jet radius: 7.5 mm, velocity 6 to 10 ms-1 * *Question: is this high enough to penetrate the solenoid field?

  16. Target and ProductionMUTAC 21 July 1999 cdj Optional target scheme devised by B. King using a rotating Cu/Ni band

  17. Target and ProductionMUTAC 21 July 1999 cdj The interaction of a liquid-metal jet with a magnetic field This has been studied by: K. McDonald, R. Palmer and R. Weggel For a conducting jet in a strong magnetic field, eddy currents cause reaction forces that may disrupt its flow. The forces are proportional to the square of the jet radius (see opposite). This places an upper limit on the jet radius and a lower limit on the jet velocity needed to penetrate the solenoid end-field. The analysis of a jet crossing the solenoid axis (as desired) is complex. This. and the computer simulations. will be tested by experiment. ANSYS simulation of magnetohydrodynamics Changguo Lu, Princeton

  18. Target and ProductionMUTAC 21 July 1999 cdj 1 kJ of beam energy deposited at time zero. Target length: 50 mm Beam radius (uniform density) 0.5 mm REXCO simulations of contained and free-jet mercury targets - CERN ACOL project. Simulation predicts unreasonable negative density (pressure) waves and this leads us to doubt the predicted expansion of the free jet at ~103 ms-1.

  19. Target and ProductionMUTAC 21 July 1999 cdj Recent simulations of pressure waves inside Gallium and Mercury jets made by Ahmed Hassanein, ANL, (HEIGHTS code) Cylindrical jet, radius 10 mm Gaussian proton beam, 2.5 1013 protons, r=4 mm Jet edge velocity - mercury jet Radial oscillations inside Gallium and Mercury jets

  20. Target and ProductionMUTAC 21 July 1999 cdj Recent simulations of pressure waves inside Gallium and Mercury jets made by Ahmed Hassanein, ANL, (HEIGHTS code) Cylindrical jet, radius 10 mm Gaussian proton beam, 2.5 1013 protons, r=4 mm The HEIGHTS code predicts that the jet will not break up when the beam passes - needs benchmarks. Note on target heating Temperature rise along the jet axis for protons of 16 GeV/c is estimated to be be in the region of 300º C. Protons of 2 GeV/c would raise the axial region to ~750º C, i.e. well above the boiling point of mercury (357º C)

  21. Target and ProductionMUTAC 21 July 1999 cdj ACTIVATION Proton flux: 3 1015 protons cm-2 s-1 Siold units After 1 month of use the specific activity of a heavy metal fixed target (3 ) would be: =  3 1013 Bq g-1 And the total activity: =  5 1015 Bq 1.3 105 Ci This value for the total activity would apply to the band-saw target and to the Hg jet. The dose rate at I m from a fixed target or the compressed band saw (1 day decay time) =  100 Sv h104rem h-1 The total activity of volatile spallation products (e.g. xenon, iodine) would be: =  1013 Bq 270 Ci These would be captured in filters of the target enclosure vacuum system. The extremely high induced activity levels may well provide the overriding reason for the use of a mercury jet target. Mercury has no long half-life isotopes. So mercury could be distilled to remove most non-volatile spallation products. There is a wealth of experimental experience in the use of mercury - cite:G Bauer ESS. Multiply by 9 for the dump

  22. Target and ProductionMUTAC 21 July 1999 cdj Radiation downstream from the target - the beam dump must extend at least 1 m into the matching section

  23. Target and ProductionMUTAC 21 July 1999 cdj G. Bauer gave an account of the ESS studies on liquid-metal spallation source targets (Hg chosen) at the recent -Fact99 meeting in Lyon, France. http://lyoinfo.in2p3.fr/nufact99/talks/bau1.jpg While these studies concern enclosed liquid cooled targets, much of the technology overlaps with our target requirements

  24. Target and ProductionMUTAC 21 July 1999 cdj G. Bauer ESS

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  27. Target and ProductionMUTAC 21 July 1999 cdj G. Bauer ESS

  28. Target and ProductionMUTAC 21 July 1999 cdj Air line - 8 bar Pressure reducer to vacuum pump trigger Air actuator Electro-pneumatic valve Observation chamber 10-1 Torr V1 Pneumatic valve - 5 mm Piston pump Single Continuous shotpulsed jet 15 Hz V1 triggered open Model liquid-metal jet target CERN 1999

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  30. Target and ProductionMUTAC 21 July 1999 cdj

  31. Target and ProductionMUTAC 21 July 1999 cdj This topic is one of the priority items for experimental R&D This will be reported by Kirk McDonald A target station engineering study is also needed. Graham Stevenson, CERN and Helge Ravn with Jacques Lettry ISOLDE/CERN are interested in participating.

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