1. Advanced and Future Accelerator Techniques Is There Life in HEP? E. Colby Stanford Linear Accelerator Center Accelerator Research Department B SLUO Annual Meeting July 7, 2000

2. Key Accelerator Technologies n Electron Colliders: NLC, N 2 LC,... –Polarized particle sources –Acceleration System –Final focus optics n Hadron Colliders: LHC, VLHC,... –Particle sources –Bending dipoles –Final focus optics

3. Key Accelerator Technologies n Muon Colliders: FMC,… –Very high intensity synchrotron (5e13 ppp) –High power conversion targets (5-7 MW) –Efficient capture optics (20-31 T Solenoid) –Rapid emittance damping systems (  <1  s) –Large aperture accelerator –Collider ring design (decay neutrino –Final focus optics

4. Other Required Technologies n General transport optics n Beam diagnosis n Feedback systems n Control systems n Active and passive alignment systems n Vacuum systems n...

5. Key Accelerator Technologies n Electron Colliders: NLC, N 2 LC,... –Polarized particle sources –Acceleration System –Final focus optics n Hadron Colliders: LHC, VLHC,... –Particle sources –Bending dipoles –Final focus optics

6. Acceleration n Couple power efficiently from an external source to the beam –Power Source –Power transmission system –Coupling structure

7. “Starting from the 1930s, the energy has increased-- by about a factor of 10 every six to eight years… this spectacular achievement has resulted from a succession of technologies rather than from construction of bigger and better machines of a given type.” W. K. H. Panofsky, 1997. Accelerator Progress of the Last 35 Years

8. Acceleration Methods n Traditional slow-wave acceleration –Normal-conducting –Super-conducting n Plasma-based acceleration n Laser-driven acceleration n Inverse radiative process n Negative resistivity (Čerenkov Amplifier)

9. Slow-wave Structure Based Acceleration F=e E o sin(  t-k z+  o ), choose  /k=V beam,  o =  /2 F=e E o sin(  t-k z+  o ), choose  /k=V beam,  o =  /2 V~ c

10. Normal Conducting Structure Performance n SLC: 2.856 GHz, 17 MeV/m, (N~1000, 86 cells) n NLC: 11.424 GHz, 67 MeV/m (N=1, (DDS1), 206 cells) n CLIC: 30.0 GHz, 125 MeV/m (N=1, (CTF1), 150 cells)

11. Future Normal Conducting Structures n Photonic Band Gap Structures n DDS 30 GHz n 91.392 GHz –“Zipper” Structure –“COMPACC” Structure –Muffin Tin –Klystrons

12. Superconducting Structure Performance TESLA: 1.3 GHz Niobium Cavities (9 cells, standing wave) n TTF Goal of 15MeV/m attained n TESLA-500 Goal of 25 MeV/m appears attainable

13. Plasma-Based Acceleration Schemes n Laser Beat-Wave Accelerator (LBWA) n Laser Wakefield Accelerator (LWFA) n Self-Modulated Laser Wakefield Accelerator (SMLWFA) qq 22 11   1-   2=  q ++ ++ ++ - - - qq ++ ++ ++ - - - qq ++ ++ ++ - - - <q<q   >>  q Raman Scattering ++ ++ ++ Accelerated Bunch - - -

14. Plasma-Based Acceleration Schemes n Beam-Driven Wakefield Accelerator (PBWA) n Crystal Channeling Accelerator qq ++ ++ ++ - - -  z <c  q ++ ++ ++ Drive Bunch Accelerated Bunch Ions form guiding channel; plasma waves induced in atomic electron clouds form accelerating potential 11

15. Experimental Demonstration of Self-Modulated Laser Wakefield Acceleration (1998) n RAL/UCLA: 160 GeV/m L=4 mm, 20 TW, 10 10 e - n NRL: 500 GeV/m L=1 mm, 2 TW, 10 8 e - n U of Mich.: 200 GeV/m L=1 mm, 4 TW, 10 10 e -

16. Plasma Wakefield Acceleration n Advantages: –Structure is already broken down! –Very high gradients possible E [GeV/cm] ~  n [cm -3 ] –Plasma densities of 10 18 -10 19 [cm -3 ] have been achieved n Disadvantages: –Short wavelength  short Rayleigh range  short interaction length (Laser guiding) –Accelerated particle bunch dimensions must be small compared to plasma wavelength to preserve beam quality –Shot-to-shot reproducibility of plasma density is critical –Synchronization of successive plasma accelerators is difficult (auto synchronization via single drive pulse)

17. Laser Acceleration Schemes n Crossed Gaussian Laser pulses (Stanford/SLAC/Nat’l Tsinghua Univ.) 1 GW, 850nm Ti:Sapphire pulses Expected Gradient: 150 MeV/m over 1 mm Reproduced from T. Plettner, “The LEAP Project”, DOE Review Slides, April 14, 2000.

18. n Capillary Guides –Propagating –Evanescent Laser Acceleration Schemes TM 010 -like mode driven by radially polarized laser Capillary mode (effectively a surface wave) driven by radially polarized laser

19. Inverse Radiative Process Accelerators n Inverse Smith-Purcell Radiation (BNL) n Inverse Cerenkov Radiation (STELLA, STI Optronics/BNL) n Inverse Free-Electron-Laser (STI/BNL) n Microwave IFEL (Yale) 350KeV/m n Inverse Transition Radiation Radially polarized laser pulse Axially polarized laser pulse Metal grating Axicon lens Different Permittivity Region

20. Active Medium Trigger bunch LASER MEDIA: Nd:YAG Accelerated bunch Cerenkov radiation from trigger bunch stimulates emission from laser media, causing amplification of the Cerenkov wakefield. At an appropriate distance behind the trigger bunch, large acceleration fields are present. L. Schächter, Technion, Israel

21. Is there a future for accelerator-based HEP?

22. Taken from the European Particle Accelerator Conference Proceedings, Stockholm, Sweden, 1998:

23. Beam Recombination