1. Accelerator Design: the nuts and bolts…and gaskets and resistors Elvin Harms Beams Division/Fermilab Harms@fnal.govHarms@fnal.govcosmo.fnal.gov

2. USPAS - Winter 20012 Introduction “Scratch the surface’ overview What goes into making an accelerator work Perspective of ‘big’ machines Principles applicable to all types of accelerators Interactive

3. USPAS - Winter 20013 What makes up a synchrotron? Two primary components –Radiofrequency system Impart energy to the particle beam Acceleration Maintain beam’s energy (synchrotron light) Maintain structure (Colliding beams) –Magnet system Keep the beam focused Keep the beam on course

4. USPAS - Winter 20014 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 Coil placement critical to field –Permanent

5. USPAS - Winter 20015 Magnets Gradient –“Combined” function

6. USPAS - Winter 20016 Magnets Separated function –Focusing and bending are done by separate magnets

7. USPAS - Winter 20017 Magnets Flavors –Dipoles –Quadrupoles –Correctors ‘trim’ dipoles (skew) quadrupoles Sextupoles even higher order Special purpose –Injection/Extraction –Light sources

8. USPAS - Winter 20018 Magnets Flavors Quadrupole Sextupole

9. USPAS - Winter 20019 Radiofrequency systems Low level –Frequency –Amplitude (voltage) –feedback High level –Accelerating cavities –Amplification

10. USPAS - Winter 200110 Piecing the machine together Cascade of accelerators –Different technologies are more efficient in different energy regimes Ion sources Injectors Collectors Transfer lines End accelerator

11. USPAS - Winter 200111 Piecing the machine together

12. USPAS - Winter 200112 Piecing the machine together Power –Accelerators require lots of it! –Stable and reliable source

13. USPAS - Winter 200113 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…)

14. USPAS - Winter 200114 Piecing the machine together Contain the beam in a pipe Vacuum –Particles travel large distances through a machine –Scattering by air can lead to reduced beam quality emittance growth energy loss

15. USPAS - Winter 200115 Piecing the machine together Vacuum –Quality: 10 -7 mbar and lower –Distributed pumping –Ion pumps, TSP’s, cryo pumping –Pick the correct materials and seals –Meticulous cleaning beforehand –UHV: bake the chamber in place

16. USPAS - Winter 200116 Piecing the machine together Cooling –Virtually every component requires some sort of external cooling –Water is most common medium –Superconducting components require cryogens –Coolant should be in as direct contact with heat load as possible (best thermal transfer)

17. USPAS - Winter 200117 Piecing the machine together Water Cooling –Conventional magnet coils typically have coolant hole through middle of conductor –Water must be low conductivity (deionized) since water current flow together –Minimze particulates – small orifices –Remove the free oxygen –Regulate the temperature

18. USPAS - Winter 200118 Piecing the machine together Cryogenic Cooling –Superconducting coils bathed in liquid helium at 4.6K –Lots of refrigeration (significant power use) –Low heat loss –Magnets are super “thermos” bottles

19. USPAS - Winter 200119 Piecing the machine together Enclosure –Electrical and Radiation hazards when operating –Personnel protection

20. USPAS - Winter 200120 Piecing the machine together Equipment housing –Want power supplies and other interface equipment as close as possible, but accessible

21. USPAS - Winter 200121 Keeping it all together / Making it work Controls system –Monitor and Control –Timing –Fast response –Beam removal –Coordination –Human interface

22. USPAS - Winter 200122 Keeping it all together / Making it work Alignment –Keep it in line! –Tevatron 150 to 800 GeV in 30 seconds –  0 = 21  s –C ~4 miles –> 1.4 million miles traveled during acceleration alone

23. USPAS - Winter 200123 Keeping it all together / Making it work Alignment –Where is it? Position of components with respect to each other Macro-positioning

24. USPAS - Winter 200124 Keeping it all together / Making it work Alignment –Move it Reference system Fixturing Component stands Remote positioning

25. USPAS - Winter 200125 Keeping it all together / Making it work Diagnostics – Arden’s talk tomorrow

26. USPAS - Winter 200126 Where does the beam go? Experiments / End Users –Internal to machine Interaction regions Beam quality/size –External Rate, energy, size, and location to deliver beam –Single-turn –Resonant extraction

27. USPAS - Winter 200127 Resources People are the most important component Other resources –Books –Schools, Workshops, conferences –Web