1. Photon Collimator and Conversion Target Status I. Bailey University of Liverpool / Cockcroft Institiute Cockcroft Institiute

2. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Collaborators EuroTeV WP4 – Photon Conversion Target and Collimator Design task (PTCD) EuroTeV WP4 – Photon Conversion Target and Collimator Design task (PTCD) heLiCal heLiCal I.R. Bailey, J.B. Dainton, P. Cooke, T. Greenshaw, L.I. Malysheva, P. Sutcliffe (University of Liverpool ) I.R. Bailey, J.B. Dainton, P. Cooke, T. Greenshaw, L.I. Malysheva, P. Sutcliffe (University of Liverpool ) D.P. Barber (DESY/Hamburg) D.P. Barber (DESY/Hamburg) G.A. Moortgat-Pick (University of Durham/CERN) G.A. Moortgat-Pick (University of Durham/CERN) J.A. Clarke, O.B. Malyshev, R.J. Reid, D.J. Scott, B. Todd (CCLRC ASTeC Daresbury Laboratory) J.A. Clarke, O.B. Malyshev, R.J. Reid, D.J. Scott, B. Todd (CCLRC ASTeC Daresbury Laboratory) Y. Ivanyushenkov, E. Baynham, T. Bradshaw, S. Carr, J. Rochford (CCLRC Rutherford Appleton Laboratory) Y. Ivanyushenkov, E. Baynham, T. Bradshaw, S. Carr, J. Rochford (CCLRC Rutherford Appleton Laboratory) DESY, SLAC, LLNL DESY, SLAC, LLNL

3. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Overview Require efficient conversion of circularly- polarised photons to longitudinally polarised positrons Require efficient conversion of circularly- polarised photons to longitudinally polarised positrons Collimate ~200kW photon beam Collimate ~200kW photon beam Collide with a thin, low Z target Collide with a thin, low Z target Produce ~10 14 positrons / second Produce ~10 14 positrons / second Positrons must then be captured and accelerated Positrons must then be captured and accelerated Require design that can be safely and economically maintained over ILC lifetime Require design that can be safely and economically maintained over ILC lifetime

4. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Collimator Issues and Tasks Start with concept developed for TESLA at DESY (N. Golubeva, V. Balandin) Start with concept developed for TESLA at DESY (N. Golubeva, V. Balandin) Determine thermal load / stresses Determine thermal load / stresses Radiation modelling (activation) Radiation modelling (activation) Effect on polarisation Effect on polarisation Engineering design Engineering design

5. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Traditional Collimator Schematic Spoiler – high Z material A simple view!

6. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute High-energy photon collimator At high energies At high energies Scattering angles become large Scattering angles become large  No need for B field  Need to cool absorber  Need to cool spoiler?  Aperture not adjustable  Several interchangeable collimators needed  Cylindrical geometry?

7. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute DESY photon collimator design (I) EGS4 Simulation – two concentric tubes connected by heat sinks Spoiler – Niobium, Absorber – Copper, Target – Titanium N. Golubeva, V. Balandin - DESY

8. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute DESY photon collimator design (II) EGS4 Simulation - Inner tube divided into discs (cones) N. Golubeva, V. Balandin - DESY

9. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute DESY photon collimator design (III) EGS4 simulation – spoiler cones disconnected from absorber (needs own water cooling system?) N. Golubeva, V. Balandin - DESY

10. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Photon Collimator Status Report on DESY collimator simulations requested Report on DESY collimator simulations requested Complete before Snowmass? Complete before Snowmass? Model thermal load Model thermal load Expertise exists at DESY (EGS4) Expertise exists at DESY (EGS4) Personnel? Personnel? Complete mid 2006? Complete mid 2006? Radiation (activation) modelling Radiation (activation) modelling Expertise exists at DESY (FLUKA) Expertise exists at DESY (FLUKA) Expertise exists at RAL (MCNPX, CINDER90) Expertise exists at RAL (MCNPX, CINDER90) Work beginning at Liverpool / Cockcroft Work beginning at Liverpool / Cockcroft Complete mid 2006 Complete mid 2006 Engineering design Engineering design Liverpool start 2006 Liverpool start 2006 Complete end 2007 Complete end 2007

11. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Target Issues and Tasks  Develop functional specification Source Performance Modelling (separate EUROTeV task) Source Performance Modelling (separate EUROTeV task) Radiation modelling Radiation modelling Thermal and mechanical stress analysis Thermal and mechanical stress analysis Engineering design Engineering design

12. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Preliminary target parameters (NLC note LCC-0133) Average Photon Energy 16.9 MeV Photon Beam Pulse Energy 41 kJ Photon Beam Repetition Rate 5 Hz Incident Spot Size (rms) 1 mm Target Material Titanium alloy Target Thickness 1.49 cm Target Tangential Velocity 50 m/s ΔE peak 191 J/g ΔT peak 361˚C Target absorption 8.1 %

13. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Target Output Parameters Average positron energy ~5 MeV Positron Polarisation > 60 % Yield (positrons/photon) ~1.5

14. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute GEANT4 simulation (I) Duncan Scott, CCLRC Daresbury Laboratory

15. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute GEANT4 Simulation (II) Duncan Scott, CCLRC Daresbury Laboratory

16. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Radiation Modelling Issues Assess amount of work involved Assess amount of work involved DESY DESY Liverpool / Cockcroft Liverpool / Cockcroft Transport and neutron production Transport and neutron production Activation Activation Relating displacements per atom (d.p.a.) to bulk properties Relating displacements per atom (d.p.a.) to bulk properties Plan visit to PSI Plan visit to PSI ITER ITER

17. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute ( ,n) cross-sections Vinod Bharadwaj SLAC

18. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Engineering Design Issues Start from LLNL / SLAC design Start from LLNL / SLAC design Study existing rotating targets Study existing rotating targets Vacuum requirements Vacuum requirements Effect of capture optics B field (~5T ?) Effect of capture optics B field (~5T ?) Source components Source components Remote-handling Remote-handling Failure modes Failure modes Design is determined by component reliability Design is determined by component reliability Necessary prototyping Necessary prototyping

19. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute LLNL Target Design(I) Werner Stein, LLNL

20. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Component Considerations Motor Motor Reliability Reliability Distance from target Distance from target Right-angle drive? Right-angle drive? Vacuum feedthroughs Vacuum feedthroughs Ferro-fluidic? Ferro-fluidic? Effect of B field? Effect of B field? Water-cooling Water-cooling Reliable seals Reliable seals Acceptable water losses Acceptable water losses Remote-handling Remote-handling …

21. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Remote Handling Concept Tim Broome, CCLRC RAL

22. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Target Status  Develop functional specification  Ongoing iteration between Liverpool and SLAC / LLNL  Source Performance Modelling  Studies at DESY, Daresbury, SLAC / LLNL Radiation modelling Radiation modelling Consulting with RAL (also remote-handling) Consulting with RAL (also remote-handling) Thermal and mechanical stresses Thermal and mechanical stresses Calculations carried out by LLNL Calculations carried out by LLNL Cross-check to be carried out by Liverpool Cross-check to be carried out by Liverpool Engineering design Engineering design Ongoing iteration between Liverpool and SLAC / LLNL Ongoing iteration between Liverpool and SLAC / LLNL Studying existing rotating targets (PSI, KEK-B) Studying existing rotating targets (PSI, KEK-B) Developing a list of critical components Developing a list of critical components Contacting manufacturers for specifications Contacting manufacturers for specifications Design will be determined by component reliability Design will be determined by component reliability

23. 22nd June 2005 I. Bailey, University of Liverpool / Cockcroft Institute Summary Gathering information and expertise Gathering information and expertise Liverpool engineers working on target task Liverpool engineers working on target task Computer modelling needs to be shared sensibly with source performance modelling task at DESY and LC- ABD WP2 (see talk by L. Malysheva) Computer modelling needs to be shared sensibly with source performance modelling task at DESY and LC- ABD WP2 (see talk by L. Malysheva) Regular meetings with SLAC / LLNL Regular meetings with SLAC / LLNL Joint target concept to put forward to Snowmass Joint target concept to put forward to Snowmass Messages for Snowmass Messages for Snowmass Undulator positron source is not only about polarisation Undulator positron source is not only about polarisation Reliability Reliability