Real Accelerators: a facility overview the nuts and bolts…and gaskets and resistors

1. Real Accelerators: a facility overviewthe nuts and bolts…and gaskets and resistors United States Particle Accelerator School – Accelerator Fundamentals Indiana University/Baton Rouge 6 – 17 January 2003 Elvin Harms Beams Division/Fermilab Harms@fnal.gov

2. Introduction • ‘Scratch the surface’ overview • What goes into making a real working accelerator • Perspective of ‘big’ machines • Principles applicable to all types of accelerators • Interactive USPAS - Winter 2003

3. Scale E. O. Lawrence early cyclotron ‘dees’ Berkley, California USA • Table top USPAS - Winter 2003

4. Scale • Big machine LHC – 27 kilometers (under construction) CERN Geneva, Switzerland USPAS - Winter 2003

5. What makes up an Accelerator? • Two primary components • Magnet system • Keep the beam focused • Keep the beam on course • Radiofrequency system • Impart energy to the particle beam Acceleration Maintain beam’s energy (synchrotron light) Maintain structure (colliding beams) USPAS - Winter 2003

6. Magnets • Electromagnets • Conventional • Water or air-cooled • Copper or aluminum coils • Iron shapes and contains the field • Superconducting • Liquid helium cooled • Higher fields > higher energies • Ramp slowly • Coil placement critical to field • Permanent USPAS - Winter 2003

7. Magnets • Gradient or ‘Combined function’ • Steering and focusing by a single element USPAS - Winter 2003

8. Magnets • Separated function • Focusing and bending are done by separate magnets • Quadrupole for focusing • Dipole for bending USPAS - Winter 2003

9. Magnets • Flavors • Dipoles • Quadrupoles • Correctors • ‘trim’ dipoles • (skew) quadrupoles • sextupoles • even higher order • Special purpose • Injection/Extraction • Light sources USPAS - Winter 2003

10. Magnets • Flavors Sextupole Quadrupole USPAS - Winter 2003

11. Magnets • Flavors • Undulator/Wiggler USPAS - Winter 2003

12. Magnets • Superconducting USPAS - Winter 2003

13. Radiofrequency systems • Low level • Frequency • Amplitude (voltage) • feedback USPAS - Winter 2003

14. Radiofrequency systems • High level • Amplification • Accelerating cavities USPAS - Winter 2003

15. Piecing the machine together • A true complex, not just a machine USPAS - Winter 2003

16. Piecing the machine together • Cascade of accelerators • Different technologies are more efficient in different energy regimes • Ion sources • Injectors • Collectors • Transfer lines • End accelerator USPAS - Winter 2003

17. Piecing the machine together USPAS - Winter 2003

18. Piecing the machine together • Power • Accelerators require lots of it! • Stable and reliable source USPAS - Winter 2003

19. Piecing the machine together • Power • Magnets connected in series • Distribution • Regulation/feedback loops • Current changes through a component leads to changes in beam behavior (never better…) USPAS - Winter 2003

20. Piecing the machine together • Contain the beam in a pipe • Vacuum • Particles travel a long way while being accelerated/in storage • Scattering by air can lead to reduced beam quality • emittance growth • energy loss USPAS - Winter 2003

21. Piecing the machine together • Vacuum • Quality: 10-7 mbar and lower for circular machines • Distributed pumping • Ion pumps, TSP’s, cryo pumping • Pick the correct materials and seals • Meticulous cleaning beforehand • UHV: bake the chamber in place USPAS - Winter 2003

22. Piecing the machine together • Cooling • Virtually every component requires some sort of external cooling, electronics, too • Water is most common medium • Superconducting components require cryogens • Coolant should be in as direct contact with heat load as possible (best thermal transfer) USPAS - Winter 2003

23. Piecing the machine together • Water Cooling • Conventional magnet coils typically have a coolant hole through middle of conductor • Control the chemistry • Water must be low conductivity (deionized) since water & current flow together • Remove the dissolved oxygen • Minimize particulates – small orifices • Regulate the temperature USPAS - Winter 2003

24. Piecing the machine together • Cryogenic Cooling • Superconducting coils bathed in liquid helium at 4.6K or less • Lots of refrigeration (significant power use) • Low heat loss • Magnets are super “thermos” bottles USPAS - Winter 2003

25. Piecing the machine together • Enclosure • Electrical and Radiation hazards when operating • Personnel protection USPAS - Winter 2003

26. Piecing the machine together • Equipment housing • Want power supplies and other interface equipment as close as possible, but accessible USPAS - Winter 2003

27. Keeping it all together / Making it work • Alignment • Keep it in line! • Tevatron 150 to 800 GeV in 30 seconds • t0 = 21ms • C ~4 miles • > 1.4 million miles traveled during acceleration alone USPAS - Winter 2003

28. Keeping it all together / Making it work • Alignment • Where is it? • Position of components with respect to each other • Macro-positioning USPAS - Winter 2003

29. Keeping it all together / Making it work • Alignment • Move it • Reference system • Fixturing • Component stands • Remote positioning USPAS - Winter 2003

30. Keeping it all together / Making it work • Diagnostics • Where’s the beam, what does it look like, how many particles? • Beam Position Monitor • Beam Loss Monitor • Profile Monitor/Wire scanner • Schottky detector • Toroid • Resistive Wall Monitor • Damper • … USPAS - Winter 2003

31. Keeping it all together / Making it work • Diagnostics USPAS - Winter 2003

32. Keeping it all together / Making it work • Diagnostics USPAS - Winter 2003

33. Keeping it all together / Making it work • Controls system • Monitor and Control • Timing • Fast response • Beam removal • Coordination • Human interface USPAS - Winter 2003

34. Where does the beam go? • Experiments / End Users • Internal to machine • Interaction regions • Beam quality/size USPAS - Winter 2003

35. Where does the beam go? • Experiments / End Users • External • Rate, energy, size, and location to deliver beam • Single-turn • Resonant extraction • Synchrotron light USPAS - Winter 2003

36. Resources • People are the most important component • Other resources • Books • Schools, Workshops, conferences • Web USPAS - Winter 2003