Paul Scherrer Institut

Transcription

1 Wir schaffen Wissen heute für morgen Paul Scherrer Institut Rafael Abela The SwissFEL X-ray Laser Project at PSI: Challenges and Opportunities

2 SwissFEL a forefront research infrastructure for CH 3 rd gen. synchrotron fine, slow optical lasers fast, coarse SwissFEL fine and fast at extreme high intensity 2017 new direct insights into chemical, physical, biological mechanisms governing our daily-life

3 MOTIVATION 1. Short wavelength (0.1nm): atomic resolution 2. Short pulses (<20 fs 2 fs): time-resolved measurements, avoid radiation damage 3. Coherence: lensless imaging 4. High brilliance: short (single-pulse shot by shot ) measurements

4 FEL Basic Design undulator electron beam Gap laser-pulse accelerator accelerator bunch compressor u photo cathode XFEL: fine and fast = 0.1 nm, = 10 fs

5 2 U 2 1 K 2 2 N 4 N

6 The SwissFEL h : Mg L-edge (50 ev) - 57 Fe Mössbauer resonance (14.4 kev) Soft X-rays: circular polarization, transform-limited (seeding) Hard X-rays: 5-20 fs (low-charge mode) Synchronized THz pump source 100 Hz repetition rate condensed matter applications

7 Photocathode Laser Requirements for SwissFEL Gun Laser specifications Maximum pulse energy on cathode Central wavelength Bandwidth (FWHM) Pulse repetition rate Double-pulse operation Delay between double pulses Laser spot size on cathode (rms) (10 pc / 200 pc) Minimum pulse rise-time Pulse duration (FWHM) Longitudinal intensity profile Transverse intensity profile Laser-to-RF phase jitter on cathode (rms) UV pulse energy fluctuation Pointing stability on cathode up to 30 J nm 1-2 nm 100 Hz yes 50 ns 0.1 / 0.27 mm < 0.7 ps 3-10 ps flattop flattop <10 fs < 0.5% rms <3 m Ti:sapphire amplifier system BB0 non linear crystal plane Transfer Line F 1 F 1 F 2 In vacuum In vacuum Aperture plane UHV mirror In vacuum Cathode plane 4-f Imaging Imaging (12 meters)

8 Photocathode Laser Requirements for SwissFEL temporal flattop transverse flattop Trisorio et al. Appl. Phys. B 105, 255 (2011) low intrinsic emittance On the cathode... a challenge for deep UV radiation Hauri et al., PRL 104, (2010)

9 SwissFEL Synchronisation System FEL Subsysteme benötigen Referenzsignal mit extrem stabiler Phase beamlines electron beam electron gun experiment sync frontend gun laser sync frontend sync frontend timing system RF station sync frontend master reference oscillator RF station sync frontend BAM, BPM sync frontend BAM, BPM sync frontend lasers (E/O, seeding ) sync frontend reference signal (can be optical or electrical) experiment sync frontend

10 Hybrid-Layout für SwissFEL Unterverteilungen für weniger krit. Klienten electron gun electron beam beamlines clients: crit. uncrit. uncrit. laser optical sync front-end pulsed laser multiple fibers distrib. electrical subdistribution optical sync front-end (pulsed) pulsed optical reference signals (pulsed and cw) Laser, BAM pulsed cw electrical subdistribution optical sync front-end (cw) gepulstes optisches Referenzsignal RF master oscillator mod. cw cw lasers RF BPM, optisches cw Referenzsignal optisches cw Referenzsignal an zentrale Punkte + Unterverteilung

11 Pump and Probe Measurements

12 Pump and Probe Measurements

13 X-Ray Arrival Time and Pulse Length Measurement Concepts Detector X-Ray Beam IR/THz Some Substance The X-ray beam causes a change in the substance properties or dynamics. The measurement of this change can give us the arrival time or pulse length. PSI Seite 13

14 Pulse Arrival Time and Pulse Length Use a THz streak camera concept to measure the arrival time and length of the photon pulse. X-ray Beam Electron Electrons electron TOF Atom IR Beam/THz Field KE electron = E photon Binding Energy ±W PSI Seite 14

15 W W Pulse Arrival Time and Pulse Length Measurements XUV Pulse 1: XUV Pulse 2: THz Pulse THz Pulse W 1 W 2 XUV T 1 XUV T2 time time W 2 -W 1 T 2 -T 1 PSI Seite 15

16 Past Results for Pulse Length at FLASH U. Fruehling et al., Nature Photonics 3, 523 (2009) PSI Seite 16

17 ARAMIS Undulator M=23 t 12 x für ARAMIS First prototype: Dec. 2012

18 Laser-based THz source at PSI R&D for SwissFEL THz gap CO 2 laser Ti:Sa Frequency THz Wavelength um uj THz pulse energy produced in DAST at 2.5 THz up to 2 MV/cm (or 0.6 Tesla) carrier-envelope phase stable electromagnetic fields good THz pulse energy stability (0.8% rms) Hauri et al. APL 99, (2011)

19 Detector Development PIXEL Detector for European XFEL AGIPD SwissFEL PIXEL Detector at the SLS

20 Proposed location on PSI - east site

21 SUMMARY

22 Photochemistry: Fundamental Steps Iron tris-bipyridine photocycle Model system for Biology: hemoglobin Geochemistry Solar Chemistry Catalytic systems

23 Strong correlated electron systems

24 What is W? Start off with the final velocity of the just-photoionized electron in the THz electric field: v f e v0 A( t) me Where Ethz da dt Knowing that Ethz E0cos( t ) A being the vector potential of the electric field. We get for the final kinetic energy of the electron: 0 K f 2 K 0 2U psin ( t ) K 0Up sin( t ) =W Where Up 2 e E 4me PSI Seite 24

25 Micro-bunching and coherent emission Micro-bunches radiate coherently. Initially uniform e - distribution (blue) evolves into microbunches (red). XFEL undulator P incoh NP 1 E NE 1 P coh N 2 E 1 2 N 10 9!! NP incoh Self-amplifying spontaneous emission (SASE)

26 The SwissFEL Scientific Case

27 Scientific Challenges

28 Pump-probe surface catalysis e.g., Haber-Bosch Process N 2 +3H 2 2NH 3 XANES (static) J. van Bokhoven (ETH)

29 Delay Fluence

30 Crystallography??????????

31 SwissFEL Phasing MeV Injector facility Gun laser 2014 Building completed Gun laser 2.1 GeV 3.4 GeV 5.8 GeV ARAMIS FEL 1-7 Å Exp SwissFEL Phase I Accelerator and hard X ray FEL Laser pump Gun laser 2.1 GeV 3.4 GeV 5.8 GeV ARAMIS FEL 1-7 Å Exp SwissFEL Phase II Soft X-ray FEL Seed laser ATHOS FEL 7-70 Å Exp2 Laser pump THz pump

32 Budget Quelle Betrag Anmerkungen ETH Bereich 20 MCHF Zugesagt für 2012 EDI Department 9 MCHF Zugesagt für 2012 Kanton Aargau (Lotterie Font) CH Bundesmittel PSI budget Total 30 MCHF Zugesagt 6 MCHF/y MCH 60 MCHF 276 MCHF Parlamentsentscheid 2012 Zeitraum MCHF/y MCHF/y PSI Mitarbeiter

33 SwissFEL Site Evaluation

34 Selected site

35 SwissFEL Milestones 4 MeV gun: in operation Scientific Case: September 2009 Local community: January 2010 ETH Board: March 2010 Start Bewilligungsverfahren : March MeV injector: First beam March 2010 Inauguration 250 MeV inj. August 24th 2010 Parliament decision: 2012 Start of construction: 2013 Aramis operation: 2017 Athos operation:

36 SwissFEL technical R&D for key items with Industry Item RF structures Pulsed High voltage for RF sources Undulator magnet systems Real time data analysis and compression Key technologies Ultra precision machining Ultra clean, ultra precision bonding High current, high voltage switching technology Precision voltage measurement & control Heavy load precision positioning Precision machining of large support structures FPGA electronic design and programming Fast algorithms Status Industry study for a production line with ultra precision machining and brazing furnace Collaboration agreement. Engineering studies Contracts for functional model partly placed Design study completed Contract for prototype placed

37 THz source, two prone approach High field pump source for experiments (see Bruce s talk) Bend radiation from compact e - accelerator THz radiation with B > 1 T Collaboration with KIT Karlsruhe for FLUTE THz source Key diagnostic tool for X-ray timing and pulse length diagnostic (pioneered at FLASH/DESY, Nature Photonics 3 (2009), 523 ) Laser generated THz avoids synchronization problem for pump probe experiments. THz is produced from same laser beam as laser pump pulse BS L SHG Filter PM WP 1 Pol. ZnTe WP 2 PBS BPD Beam splitter R=2% Lens f=75mm-500mm BBO* crystal for SHG Teflon low pass filter Off axis parabolic mirror half wave plate Polarizer sampling crystal 2mm quarter wave plate polarizing beam splitter Balanced photo detector