1 / 28

Optical Stochastic Cooling

Optical Stochastic Cooling. Fuhua Wang MIT-Bates Linear Accelerator Center. Outline. Introduction: history, concept Experiment with electron beams: proposal & research at MIT & MIT/Bates OSC for RHIC, Tevatron … Summary . History. A. Zholents,….

lexiss
Download Presentation

Optical Stochastic Cooling

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Optical Stochastic Cooling Fuhua Wang MIT-Bates Linear Accelerator Center 4Th Electron-Ion collider Workshop Hampton University

  2. Outline • Introduction: history, concept • Experiment with electron beams: proposal & research at MIT & MIT/Bates • OSC for RHIC, Tevatron … • Summary 4Th Electron-Ion collider Workshop Hampton University

  3. History A. Zholents,… 1968 - Stochastic Cooling proposed by S. van der Meer. It was proved to be a remarkably successful over next several decades. (For a detailed historic account see CERN report 87-03, 1987, by D. Möhl.) 1993 - Optical Stochastic Cooling (OSC) proposed by Mikhalichenko and Zolotorev 1994 - Transient time method of OSC proposed by Zolotorev and Zholents 1998 - Proposal for proof-of-principle experiment in the Duke Electron Storage Ring (potential application for Tevatron was in mind) 2000 - OSC of muons by Wan, Zholents, Zolotorev 2001 - Proposal for proof-of-principle experiment in the storage ring of the Indiana University 2001 - Quantum theory of OSC, by Charman and also by Heifets, Zolotorev 2004 - Babzien, Ben-Zvi, Pavlishin, Pogorelsky, Yakimenko, Zholents, Zolotorev, Optical Stochastic Cooling for RHIC Using Optical Parametric Amplification 2007 - Proposals for Optical amplifier development and OSC experiment at MIT-Bates. 4Th Electron-Ion collider Workshop Hampton University

  4. “bad” mixing “good” mixing kicker DL ~1/bandwidth=1/B g amplifier p pick-up number of particles in the sample Lb Stochastic Cooling S. van der Meer, 1968 D. Möhl, “Stochastic Cooling for Beginners”, CERN 4Th Electron-Ion collider Workshop Hampton University

  5. optical “slicing” microwave “slicing” sample length ~10 mm sample length ~10 cm OSC also allows transverse slicing Diffraction limited size of the radiation source resulting in further decrease of Ns: Towards Optical Stochastic Cooling OSC explores a superior bandwidth of optical amplifiers, BOSC~ 1014 Hz 4Th Electron-Ion collider Workshop Hampton University

  6. M. Zolotorev & A. Zholents, 1994 N S N S N Particle delayed Light pulse delayed and amplified Particle emits light pulse of length Nl Particle receives longitudinal kick from amplified light pulse • Particles in the second undulator see light emitted by themselves and neighboring particles within “coherent slice” Nul • Bypass delay Dℓ for particles on central orbit set such that it is on the zero crossing of the electric field in the 2nd undulator • “Off axis” particles receive a momentum kick • Notice: for =2m, /2 phase shift corresponding 1.7 fs : system stability ? Transit-time method of OSC 4Th Electron-Ion collider Workshop Hampton University

  7. OSC Formalism Phase between electron and light at U2: Light from U1 is amplified and provides momentum kick at U2: Sum of momentum kicks by amplified light from all Ns coherently radiating electrons produces a change of d2 for an individual electron: Average over all Ns electrons assumed to be normally distributed (Gaussian) in x, ,  with rms widths <x>, <>, <> to find: 4Th Electron-Ion collider Workshop Hampton University

  8. OSC Formalism, con’t Cooling rates per orbit: Find: 4Th Electron-Ion collider Workshop Hampton University

  9. Experiment with electron beams Significance: • OSC in low energy e-beam ring is ideal for demonstration & test experiment in high-energy hadron beam collider rings. • OSC cooling can be observed in seconds: short experiment time scale. • Optical amplifier is available. • Low cost beam bypass, undulators and ring interface, low experiment cost. OSC experiment at MIT-Bates SHR ring : 2007(BNL CAD review)- Motivation: • Proof-of-principle & OSC system study for high-energy colliders. • Concept developments: Cooling mechanism, OSC and ring lattice interface. • Technical system: optical amplifier, diagnostics & control. 4Th Electron-Ion collider Workshop Hampton University

  10. Collaboration List W. Barletta, K. Dow, W. Franklin, J. Hays-Wehle, E. Ihloff, J. van der Laan, J. Kelsey, R. Milner, R. Redwine, S. Steadman, C. Tschalär, E. Tsentalovich, D. Wang and F. Wang, MIT Laboratory for Nuclear Science, Cambridge, MA 02139 & MIT-Bates Accelerator Center, Middleton, MA 01949 F. Kärtner, J. Moses, O.D. Mücke and A. Siddiqui MIT Research Laboratory of Electronics, Cambridge, MA 02139 T.Y. Fan, Lincoln Laboratory, Lexington, MA 02420 M. Babzien, M. Blaskiewicz, M. Brennan, W. Fischer, V. Litvinenko, T. Roser and V. Yakimenko, Brookhaven National Laboratory, Upton, NY 11973 S.Y. Lee Indiana University Cyclotron Facility, Bloomington, IN 47405 W. Wan, A. Zholents and M. Zolotorev Lawrence Berkeley National Laboratory, Berkeley, CA 94720 V. Lebedev,V. Shiltsev Fermilab, Batavia, IL 60510 4Th Electron-Ion collider Workshop Hampton University

  11. Small-angle bypass: Concept Based on Optical parametric amplifier: total signal delay ~20ps only! Then we can choose small-angle chicane with path length increase of 20 ps ~ 6 mm. 4 parallel-edge benders and one (split) weak field lens. Choose =65 mrad, L=6mm. First order optics: 4Th Electron-Ion collider Workshop Hampton University

  12. Small-angle bypass:Tolerances C. Tschalär, J. van der Laan Tolerances to conserve coherence are much relaxed for small-angle bypass. Absolute setting demands: R51, R52, R56 setting within ~±5% • magnet current setting ± 2 % • field lens current setting ± 5 % • magnet longitudinal positioning ± 10 mm • field lens transverse positioning ± 100 mm Stability (~1 hour) demands: Variation for central orbit length in chicane ≤ 0.1 m = 20°phase • magnet current 10-5 • lens current 3 * 10-3 • magnet longitudinal position 50 m • lens transverse position 250 m 4Th Electron-Ion collider Workshop Hampton University

  13. Bypass optics and ring lattice requirementsC. Tschalär Choose bypass (Rij) and ring(Twiss, dispersion) parameters to have a proper range of <2>(,<2>,..) for cooling. 4Th Electron-Ion collider Workshop Hampton University

  14. Bates Experiment Parameters Growth (damping) rates at equilibrium state: 4Th Electron-Ion collider Workshop Hampton University

  15. OSC Insertion SHR Lattice for OSC Experiment 4Th Electron-Ion collider Workshop Hampton University

  16. SHR OSC Simulation: x and <2> <2> decreases with x. Optimal cooling achieved by adjusting G. 4Th Electron-Ion collider Workshop Hampton University

  17. Particle Distribution with OSC: Gaussian C. Tschalär OSC tracking: 104 particles, 106 turns. Bates SHR, Nb=108. 4Th Electron-Ion collider Workshop Hampton University

  18. OSC tracking: 104 particles, 106 turns. Bates SHR, Nb=108. Particle Distribution with OSC: “BOX” 4Th Electron-Ion collider Workshop Hampton University

  19. OSC Tuning Diagnostics J. Hays-Wehle, W. Franklin • Interference signal maximal when light amplitudes same (low gain alignment) • E2 is maximal for f=0 (f=/2 for OSC) use in feedback system • Perform phase feedback in high gain operation ? (work on analysis and bench test, J Hays-Wehle) • Correlate with beam size measurements (sync. Light monitors, streak camera) 4Th Electron-Ion collider Workshop Hampton University

  20. 10 µJ, or 20 W 2nJ, or 40mW bunch length: 20 ps, 1 nsrepetition rate: 20 MHz, ~2 MHz Tevatron: 1 pJ Bates: 0.2 pJ Dispersion free 40-70 dB Amplification • High broadband amplification: G~104 (107), 10% bandwidth (undulator) • Dispersion free: group delay variation less than 0.1 optical cycles • Short overall delay to enable short chicane bypass to maintain • interferometric stability and reduce cost •  Broadband Optical Parametric Amplification (OPA) with low conversion • Ultra-broadband optical amplifiers suitable for OSC at Bates can be built using commercial picosecond lasers, PPLN based OPA at 2 microns Optical amplifier requirements for OSC: Bates & TevatronF. Kärtner, A. Siddiqui 4Th Electron-Ion collider Workshop Hampton University 20

  21. 50 ps, 1030 nm Laser 20 MHz, 20 W, 1 mJ 2 nJ 40 mW Undulator Radiation BaF2 wedges 1mm Beam radius: f = 12 cm w = 0.5 mm 2 mm PPLN n=2 0.2 pJ 4 µW f = 380 cm f = 380 cm 24cm 103cm 270cm 103cm 270cm Lenses and wedges, 1mm, n=1.5 Total optical delay is only 5.5 mm ~ 20 ps Amplifier layout for Bates OSC F. Kärtner, A. Siddiqui PPLN: Periodically Poled Lithium Niobate 4Th Electron-Ion collider Workshop Hampton University 21

  22. OSC for RHIC 4Th Electron-Ion collider Workshop Hampton University

  23. Integrated luminosity gain (slow down emittance growth) estimates for proton beams: 60% to 100%. MIT/Bates proposal review 2/12/2007W. Fischer 4Th Electron-Ion collider Workshop Hampton University

  24. OSC for Tevatron: Layout OSC location 4Th Electron-Ion collider Workshop Hampton University

  25. Tevatron: protons Undulators:10 periods of 2.7m = 27 m long B=8Tesla; K=1.1;=0.38; =2; k=•106/m Amplifier: OSC Chicane: choose Cooling time : Current luminosity lifetime ~ 10 hours Numerical Example for Tevatron OSCC. Tschalär 4Th Electron-Ion collider Workshop Hampton University

  26. Original Long Straight 32.5 mrad 72m OSC Insertion 19.7 mrad Optical line 89.4m Dipole 4.4T, 25.6m Bending angle and drift space set to have: Path delay : L=10mm=30 ps x=55.7cm Eased magnet tolerances Dipole 8.0T Undulator 8T, 27m Dipole 8.2 T, 8m Quadrupole 2m , g 400T/m, aperture 2cm. Small-Angle Magnetic Bypass Chicane (conceptual design) 4Th Electron-Ion collider Workshop Hampton University

  27. High-Power Optical Amplifier for Tevatron: Development Plan J. Gopinath et al., MIT-LL, A. Siddiqui et al.,MIT-RLE • OSC at the Tevatron needs >20 W output power and linear gain => 1 kW pump power with 2% conversion. OPA needs “perfect” beam (M2<1.2) • High-Power pump Laser: • Cryogenically cooled Yb:YAG lasers (Demo: 500-W, 2007) • T. Y. Fan, MIT Lincoln Laboratory • MIT-LL ATILL Program (5kW laser) • High-power OPA design and demonstration: • Trade study to evaluate NLO crystal candidates for average-power performance and designs for high-power OPA • Measure key engineering parameters needed for high-power OPA (thermal conductivity, optical absorption, dn/dT) • Demonstration of 20-W OPA with phase control • Successful OSC at the Tevatron needs forward looking development now if it needs to be available in 2 years. 4Th Electron-Ion collider Workshop Hampton University 27

  28. Summary • OSC concept, based mostly on current technology, is a viable solution to high-energy hadron beam cooling. • Important development tasks include: high average output power optical amplifier (including pump laser), OSC interface with collider rings and cooling diagnostics & control. • Experiment with electron beam can advance OSC concepts and technical systems in a short time period and with minimal funding support. It is an essential step prior to a full-scale implementation of OSC systems in high-energy hadron beam colliders. 4Th Electron-Ion collider Workshop Hampton University

More Related