Gwyn P. Williams Jefferson Lab

1. How to Make Light Gwyn P. Williams Jefferson Lab 12000 Jefferson Avenue - MS 7ANewport News, VA 23606 gwyn@mailaps.org Jefferson Lab Summer Lecture July 21, 2008

2. Outline of Talk • 1. Motivation – why do we need bright light? • How do we make ultrabright light sources? • ……what is brightness anyway?

3. Need to understand small things Very small is different than big Typical thermodynamic system - heat moves from hot (boiler) to cold (condenser) and work is extracted. Small is different. Small things such as pollen grains in a water solution are endlessly buffeted by the random motion of the water molecules. (This is termed Brownian motion). Macroscopic machines – like steam engines – are far too massive to be affected by these small fluctuations. We cannot calculate the power/efficiency trade-off for a nanomachine or derive design rules. Neither thermodynamics nor stationary-state quantum mechanics helps. Molecular junction. A nanosytem - Brownian motion.

4. Molecular junction. What are some examples of small systems? Modern nanotechnology will require an understanding of small, isolated systems A powerful molecular motor (yellow) translocates the twisted strands of DNA (right) of a virus into a protein capsid. By using optical tweezers to pull on the DNA while it is being packed, it was determined that the motor can pack DNA to a pressure of about 60 atmospheres, 10x that of a champagne bottle. Electron transport has been observed across molecules with only a few monomers (a few Angstrom). Charge transfer through single molecular devices is presently one the most fascinating and fastest developing fields in the range between mesoscopic physics and chemistry.

5. Fast Cameras (a) Freeze motion (b) Study “dynamics” in time domain

6. t = 10-14 secs (10fs) 0.1 nanometer Sizes and Time-scales……“seeing atoms” Area of atom is 10-20 m2 Area of focus of 0.1 nm beam of light is 10-20 m2 Need 1012 photons/sec to get good data, into this area - which means a: desired BRIGHTNESS of 1026 photons/sec/mm2/mrad2 Brightness is photon flux/(area x angle) – or photons on target!

7. Development of Brightness of Light Sources

8. Development of Brightness of Light Sources

9. Back to lasers - conventional types of lasers 1. Solid State 2. Gas 3. Excimer 4. Dye 5. Semiconductor 6. Fiber All work with a medium in a cavity.

14. LASER LIGHT

16. Conventional lasers have limitations… • Not tunable • Limited availability of different wavelengths from catalogs • Output typically limited to a few watts • No short wavelengths – x-rays

17. Accelerator-based light sources have no limitations….. Synchrotrons, Free Electron Lasers • Tunable • Short wavelengths (x-rays) • High power and brightness

18. How do these accelerator-based light sources work? electric field electron

19. light e- Maxwell’s equation Accelerator-based Light Sources – physics e is charge on electron a is acceleration c is speed of light  is relativistic mass increase

20. J/cm-1/electron How do we make light sources more powerful? 2e- light e is charge on electron a is acceleration c is speed of light  is relativistic mass increase 4 times the power!!!

21. Schematic of next generation light source laser “seed” optional LASER from Richard Sheffield LANL

22. Principle of Jefferson Lab’s Energy Recovered Linac / FEL

23. JLab’s Existing 4th Generation Light Source E = 150 MeV 135 pC pulses up to 75 MHz (20)/120/1 microJ/pulse in (UV)/IR/THz 250 nm – 14 microns, 0.1 – 5 THz All sources are simultaneously produced for pump-probe studies

24. Light Sources – “The World Stage”

25. 21st. Century Light Source LCLS…. FLASH JLAB FEL JLAB THz Light Sources – “The World Stage”

26. 30 1x10 28 10 /sr 26 1x10 24 10 2 22 10 $ 250M 4th. Generation 20 10 18 10 Photons/sec/0.1%BW/mm 16 Average Brightness 10 14 10 3rd. Generation $ 120M 12 10 10 2nd. Generation 10 8 10 $ 60M 6 10 4 10 1E-4 1E-3 0.01 0.1 1 10 100 1000 10000 Gwyn Williams - file brt_1.bas Photon Energy (eV) Nov. 2007 So why haven't they been built? Shorter wavelengths isky and expensive using present technology! $ 500M SRF Linac cost

27. Operating ERLs ERL Test Facilities ERL Conceptual designs Operating and Future ERLs

28. Next Generation Light Sources USA Programs • Jefferson Lab, IR/THz ERL, operational • LCLS, Stanford, USA, hard x-ray, DOE-BES under construction • Cornell University, hard x-ray ERL, proposal to NSF, initial funding • Florida State University, IR/THz ERL, proposal to NSF, initial funding • WiFEL, Stoughton, Wisconsin, soft x-ray, proposal to NSF • Advanced Light Source, Berkeley, soft x-ray, proposal to DOE • Advanced Photon Source, Argonne, hard x-ray ERL, proposal to DOE • LSU, THz – soft x-ray, white paper preparation to State and DOE • The Light Source of the Future (LSF), DOE-BES, TBD

29. Next Generation Light Sources – non USA Programs • FZR-Dresden, IR/THz, operational • Budker Institute, Novisibirsk, Russia, THz ERL operational • FLASH, Hamburg, Germany, soft x-ray, operational • Daresbury & Rutherford UK, THz-x-ray, proposal in process • STAR, Berlin, Germany, soft x-ray, proposal • Paul Scherrer Inst. Switzerland, hard x-ray, proposal • Maxlab, Lund, Sweden, soft x-ray, proposal • XFEL, Hamburg Germany, hard x-ray, European proposal • XFEL, Spring-8, Japan

30. Undulator and linear accelerator at Jefferson Lab • Wavelength 20 cm • Number of periods 12 ea. • Gap 26 mm

31. Superconducting Radio-Freq. Linac

32. Cryomodule Injector Gun Beam Stop Wiggler Schematic of JLab 4th. Gen. Light Source Operation Niobium SRF Cavity with Oscillating Electromagnetic Field Electron Beam Drive Laser Light Output Total Reflector Output Mirror Periodic Magnetic Field Electron Beam Laser Wavelength ~ Wiggler wavelength/(2Energy)2

33. Jefferson Lab facility unique spectroscopic range JLab FEL JLab THz FEL proof of principle: Neil et al. Phys. Rev.Letts 84, 662 (2000) Table-top sub-ps lasers Synchrotrons Globar THz proof of principle: Carr, Martin, McKinney, Neil, Jordan & Williams Nature 420, 153 (2002)

34. One of the first areas of impact of next generation light source technology – Terahertz

35. What is Terahertz Light?

36. Why is Terahertz Light new? Photonics – light bulbs Electronics - radios Frequency THz Tom Crowe, UVa

37. High Power THz Light is New - Nature March 2007 JLab THz Photonics - light sources Electronics - radios Tonouchi Nature Photonics 1, 97 (2007)

39. What is Unique about Terahertz Light? • THz light passes through many materials, such as • packaging material, clothing, carpet, walls. • THz light is non-ionizing – unlike x-rays. • THz light can “recognize” and distinguish materials that • x-rays cannot, such as plastics & proteins. • THz light allows high speed & safe communications. • - Tera is 1000 times faster than Giga… • THz does not pass through metal and water, and will always • be complimentary to x-rays.

40. Why make Terahertz Light? • Many applications, new discoveries every month. • Security • Medical screening (skin cancer) • Pharmaceuticals (drug verification and testing) • Non-destructive evaluation • Environmental monitoring • High speed communication

41. Security – hidden weapons 30 GHz NOT THz Clery, Science 297 763 (2002)

42. Security – hidden non-metallic weapons David Zimdars SPIE 5070 (2003)

43. Security – hidden weapons, explosives THz Visible Explosive “fingerprints”

44. Security – fingerprint of anthrax proxy

45. Security – hidden bio-agents, explosives David Zimdars, John Federici

46. Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U.S. Department of Energy Medical – cancer screening Basal cell carcinoma shows malignancy in red. Teraview Ltd. 1 mW source images 1 cm2 in 1 minute 100 W source images whole body (50 x 200cm) in few seconds

47. Medical – improved dental imaging A tooth cavity shows up clearly in red. Teraview Ltd.

50. Conclusion Bright Light has a Bright Future. Quest is now on to shorten wavelength.