SLAC UED/UEM Initiative and UED@ASTA Accelerator Directorate Review on UED@ASTA X.J. Wang- May 20, 2014

Fundamental Probes in the BES Parameter Electron Neutron Photon Charge ✔ Magnetic Moment Mass Spin Polarization Force Electrostatic Nuclear Electromagnetic Samples Thin Thick Medium _ Users desire to use different probes to obtain complementary info on samples Electrons & x-rays see electrons and proton, while neutrons can see nuclei

SLAC UED/UEM ini Is also well aligned with the DOE mission – that is to develop state of art intrumentation

DOE BES Future Electron Scattering and Diffraction Workshop A – Multidimensional Visualization of Real Materials B – Atomic Scale Molecular Processes C - Photonic Control of Emergence in Quantum Materials D - Evolving Interfaces, Nucleation, and Mass Transport Ultrafast Electron Diffraction and Microscopy Facility B.1 – Source (MeV) and Electron Optics: B.2 - Pump Technology

The UED-UEM initiative at SLAC/Stanford Vision: The SLAC UED/UEM facility will be the world leading electron scattering instrumentation facility, complementary to the LCLS X-ray FEL. The UED/UEM facility will possess unique capabilities that enable Grand Challenge science in chemistry, material science, physics and biology. The availability of intense THz, X- ray and optical laser pumping in conjunction with UED/UEM probes will open new scientific opportunities. THz electron beam

SLAC Lab Agenda (2014) X-Ray THz What is make the UED/UEM uniques Two things. One is uniques capble. And other is the broad user community.

SLAC UED/UEM Summary 18 months (2015) ~48 months (2019) 2016 *base design - upgrade - blue sky R&D

Ultrafast (< 10 ps) imaging only possible at higher voltages Point Spread Function at 200 keV, 1 ns 50 nm 100 nm -50 nm -100 nm Point Spread Function at 5 MeV, 10 ps For picosecond resolution imaging, relativistic energies may be the only way to obtain high spatial resolution. M. R. Armstrong, B. W. Reed, B. R. Torralva, and N. D. Browning, Appl. Phys. Lett. 90, 114101 (2007).

Large Scattering Signal R.Valle et al, Ultramicroscopy 27, 67 (1989)

Pump-probe Velocity Mismatch 60keV UED ΔtVM > 1ps Ve= 0.446c 𝑒 − ℎ𝜈 3MeV UED ΔtVM < 10fs Ve= 0.989c ℎ𝜈 𝑒 −

Knock on Pulse radiolysis Charging Sample Damage R.F. Egerton et al. Micron 35，399 （2004)

Ultrafast Electron Diffraction (UED) La0.5Sr1.5MnO4: Orbit & Charge Orders MeV-UED BNL TEM Laser OPA / THZ Syn Axicon UV Optics RF RF Gun Lens Sample Detector

Ultrafast Electron Diffraction (UED) & Nano-UED Laser OPA / THZ Syn Axicon UV Optics RF RF Gun Lens Condenser Sample Detector

Ultrafast Electron Imaging (UEM) Laser OPA / THZ Syn Axicon UV Optics RF Projector RF Gun Lens Condenser Objective Sample Detector

UED @ ASTA? ASTA the most favorable site for fast impact experiments, There are three potential sites at SLAC could be considered for the first phase of UED. Those three sites are ASTA, NLCTA and LCLS II injector. ASTA the most favorable site for fast impact experiments, Existing RF gun and infrastructure. Laser system. Synergy with LCLS cathode R&D – thermal emittance reduction. X-band for beam diagnostics Concerns: Impact to existing program: LCLS cathode R&D, semi-conductor cathode, and X-band testing program Space and environment (temperature and vibration) safety (laser and radiation), budget and resource (manpower). Others

The Accelerator Structure Test Area (ASTA)

UED@ ASTA Objectives FY14 First 100 Femto-second MeV UED at high rep rate Order of magnitude improvement (120 Hz vs 10 Hz) MeV UED Ultrafast Science FY14 FePt 2nm heat sink Goal: understand & control materials processes related to heat-assisted magnetic recording Understand and quantum control of chemical reactions. Structure of intermediate states

Early Physics: UED@ ASTA (FY14)

Early Physics: UED@ ASTA (FY14)

Challenges in UED @ ASTA Time and resource Infrastructure upgrade – ASTA bunker space and laser room air conditioning Technical challenges: Electron beam line ( diagnostic, sample chamber and detector) Laser RF synchronization Low level RF Klystron modulator Laser transport and pump-probe optics

Challenges in MeV-UED - Timing Jitter Laser RF Oscillator RF Gun RF Drive Cathode Sample Δtjitter =

ALD Review on UED@ASTA Agenda Start End Time Title Speaker ​​​8:00 ​​8:30 ​​0:30 Executive session ​ ​​​8:30 ​8:40 ​0:10 ​Welcome and charge to the committee ​ Bob Hettel ​​​8:40 ​9:10 ​0:30 SLAC UED/UEM Initiative and UED@ASTA ​XJ Wang ​​​​9:10 ​​9:30 ​0:20 ​Science enabled by the UED/UEM and early science at ASTA ​Hermann Durr ​​​​9:30 ​​9:50 ​0:20 UED@ASTA project plan and ES&H ​Carsten Hast ​​​​9:50 ​​10:05 ​0:15 ​​UED@ASTA beam line and mechanical layout ​Eric Bong ​10:05 ​​10:20 ​0:15 ​Coffee break ​ ​​10:20 ​​​10:50 ​0:20 ​Beam Dynamics study ​ Juhao Wu ​​10:40 ​11:00 ​0:20 ​RF power stability ​ Minh Nguyen ​​​11:00 ​11:20 ​0:20 ​LLRF and timing triggers ​Stephen Weathersby ​​11:20 ​​11:40 ​0:20 ​Laser-RF timing and synchronization ​Joe Frisch ​11:40 ​12:00 ​0:20 UED laser transport and pump-probe optics ​Ryan Coffee ​12:00 ​12:20 ​0:20 UED commissioning ​ Renkai Li ​12:20 ​01:15 ​0:45 ​Lunch and discussion ​ ​01:00 ​01:45 ​0:45 ​ASTA tour ​Bldg. 44 ​01:45 ​03:30 ​2:00 ​Executive session, report preparation + additional questions ​ ​03:00 ​ Coffee ​ ​03:30 ​​04:30 ​0:30 ​Close-out

Summary The SLAC UED/UEM facility will be the world leading electron scattering instrumentation facility, complementary to the LCLS X-ray FEL. The UED/UEM facility will possess unique capabilities that enable Grand Challenge science in chemistry, material science, physics and biology. The availability of intense THz, X-ray and optical laser pumping in conjunction with UED/UEM probes will open new scientific opportunities. UED@ASTA will be the first step toward SLAC UED/UEM facility, it will be the first UED breaking 100 fs barrier and enable some exciting science. We have a realistic plan to realize the first experimental in FY 2014.