Accelerator Research at SLAC

Tor Raubenheimer

Stanford Graduate Student Orientation September 20, 2012

What are accelerators?

Wikipedia: A

particle accelerator

is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams • • CRT’s  x-ray tubes  SRS  Large Hadron Collider Velocity = 0.999999999986 x speed of light at LEP2 ~26,000 accelerators worldwide • • • • • ~44% are for radiotherapy, ~41% for ion implantation, ~9% for industrial processing and research, ~4% for biomedical and other low-energy research, ~1% with energies > 1 GeV for discovery science and research Stanford Graduate Student Orientation, 9/20/2012 2

Particle Accelerators at SLAC

Accelerators at SLAC

FACET ASTA XTA

Stanford Graduate Student Orientation, 9/20/2012 3

Field of Accelerator Physics

LHC Tevatron HERA LEP-II SLC Broad field ranging from engineering some of the largest scientific instruments to plasma physics to materials science to nonlinear dynamics • Advances come from both conceptual research and directed R&D aimed at applications Field offers opportunity for ‘small-scale’ experiments at large science facilities • Small groups: Individuals can engage in theory, simulation, and experimental results 4

Advanced Accelerator Research @ SLAC

High energy particle accelerators are the ultimate microscopes • • Reveal fundamental particles and forces in the universe at the energy frontier Enable x-ray lasers to look at the smallest elements of life Goal is to shrink the size and cost by factors of 10-1000 Combine SLAC accelerators with lasers, plasmas, high-power microwaves, and lithography to develop new generation of particle accelerators and sources New designs and materials push metal accelerator structures to the limit Telecom and Semiconductor tools used to make an ‘accelerator on a chip’ Extremely high fields in 1,000 °C lithium plasmas have doubled the energy of the 3-km SLAC linac in just 1 meter

The E163 Test Facility and the Next Linear Collider Test Accelerator provide unmatched capabilities for testing laser accelerators. The small size of the group (<10) means that students can be involved in virtually all aspects of the experiment. Woodpile Structure Contact: Dr. Eric Colby, 926-3709; Dr. Joel England, 926-3706 6

Plasma Wakefield Acceleration

Acceleration gradients of ~50 GV/m (3000 x SLAC) • Doubled energy of 45 GeV beam in 1 meter plasma FACET brand-new 20 GeV test facility for PWFA Contact: Dr. Mark Hogan, 926-2951 Pa ge 7

Accelerator Beam Physics and Computing

Broad set of topics ranging from concepts for future high-energy physics and photon science facilities, to massively parallel simulations, to beam theory • Developed many of the innovative concepts of the field including: Linear collider designs Linac coherent light source (x-ray FEL) PEP-X and other future light sources Massively parallel electromagnetic calculations Faculty: Alex Chao, Ron Ruth Department heads: Yunhai Cai and Cho Ng 8

Compact accelerators

Developing new compact accelerator for Inverse Compton Scattering, FEL’s and Ultrafast e Diffraction Linac YAG, Laser Injection chamber Gun Cecile Limborg 926-8685 Chris Adolphsen 926-3560 9

Novel experimental beam dynamics

Stanford Graduate Student Orientation, 9/20/2012 10

Accelerator Technology Research

High Gradient Research: • • • •

Host for the US Collaboration on High Gradient Research for Future Colliders

RF Superconducting Material Characterization, Geometrical Effects, Frequency scaling,.

High Frequency RF Source Developments.

Novel Accelerator structures Novel FEL Technologies and Light Sources: RF undulators and bunch compression techniques for ultra-short pulses.

Advanced Accelerator Concepts: Practical design and implementation of Terahertz and far infrared accelerators and components Undulator Mechanical Structure For more info contact: Electric Field Distribution Prof. Sami Tantawi 650-926-4454

SPEAR3 accelerator research

Short pulses/THz beamline

• • • LDRD funding to design THz beamline Primary rotation research focus Beamline purpose: Characterize bunch shape Measure shielded CSR impedance THz for photon experiments Accelerator optics/Nonlinear dynamics PEP-X (future light source) Gun development Flux: R0= 2 m; 1.2 T, 3.0 GeV, 1.000 eV; I 100mA 5 4 3 -2 -3 -4 0 -1 2 1 -5 -5 -4 -3 -2 -1 0 x (mm)

Nonlinear dynamics: simulated & measured

1 2 3 4 Diagnostics development 5 James Safranek, 926-5438

Large Hadron Collider: Accelerator Research

Stanford Graduate Student Orientation, 9/20/2012 13

Advanced Instrumentation and Feedback

• Signal processing systems for beam instrumentation and feedback control systems. Develop DSP with 4-8 GHz processing bandwidth for SPS and LHC, participate in machine measurements. • System modeling and simulation of unstable systems under feedback control  stabilize jitter in LCLS • Machine physics studies and system dynamics characterization of the LHC RF ↔beam interaction The group comprises SLAC staff, Toohig Fellow and Stanford Ph.D. students.

Two APS Dissertation Prizes in Beam Physics have been awarded to past students.

Contact: John Fox, 926-2789 Stanford Graduate Student Orientation, 9/20/2012 14

LHC Projects

A number of potential thesis projects on LHC • • • • Crystal collimation  with Uli Weinands HiLum LHC design  Yunhai Cai LLRF, feedback and Electron cloud instability and control  with John Fox Faculty members: • John Fox, x2789 Senior Staff: • • • Tom Markiewicz, x2668 Uli Wienands, x3817 Yunhai Cai, x2935 Stanford Graduate Student Orientation, 9/20/2012 15

Linac Coherent Light Source (LCLS)

• World’s first x-ray laser – a Free Electron Laser • Commissioned in 2009 and constantly advancing new concepts April 10, 2009 Stanford Graduate Student Orientation, 9/20/2012 16

LCLS Undulator Hall

Stanford Graduate Student Orientation, 9/20/2012 17

Linac Coherent Light Source II

Injector @ 1-km point Sectors 10-20 of Linac (1 km)

(with modifications) Bypass LCLS Linac In PEP Line (extended) New Beam Transport Hall

2010: April 2011: October 2012: March 2012: August 2013: June Critical Decision 0 approved Critical Decision 1 Critical Decision 3a Critical Decision 2 Critical Decision 3b 2018: Sept. First FEL Light 2019: Sept. Critical Decision 4 approved approved SXR, HXR Undulators X-ray Transport Optics/Diagnostics

Linac'12, Tel Aviv, Sept. 2012 New Underground Experiment Hall Slide 18

FEL R&D opportunities @ SLAC

• LCLS is the world’s brightest x-ray source. You have the opportunity to make it even brighter!

SASE spectrum Seeded spectrum

• • Seeding improves spectral brightness Tapered undulator increases FEL power to Terawatt level Many challenging theoretical, computational, and experimental topics to pursue in the coming years (see next slide)

Seeding + taper

X-ray seeding & brightness 2011-12

SLAC FEL R&D roadmap

LCLS-II injector 2013-14 2015-16 LCLS-II completion 2017-18 2019-20 HXRSS TWFEL Soft X-Ray Self-Seeding ECHO-7 ECHO-75, laser phase error E-beam brightness & manipulation Ultrafast techniques THz & Polarization Technology development ASTA (Cathode, Gun) Injector R&D S0 ITF: advanced beam generation, high-energy compression and laser seeding Temporal diagnostics & timing Attosecond x-ray generation THz Polarization control HXRSS X-ray sharing Multi bunches, detectors, novel undulators, high-rep. rate Completed Ongoing Under development

SLAC Facilities

Phenomenal accelerator R&D facilities:

Accelerator Structure Test Area NLC Test Accelerator X-band Test Accelerator End Station Test Beam FACET SPEAR-3 Linac Coherent Light Source

DOE Computing Resources:

NERSC at LBNL Franklin Cray XT4: 38,642 compute cores, 77 TBytes memory, 355 Tflops NCCS at ORNL Jaguar Cray XT5: 224,256 compute cores, 300 TBytes memory, 2331 Tflops, 600 TBytes disk space Local clusters and GPU machines plus Shops and engineering staff to build what you need Stanford Graduate Student Orientation, 9/20/2012 21

Examples of Recent PhD Theses

• Dan Ratner, “Much Ado about Microbunching: Coherent Bunching in High Brightness Electron Beams,” Advisor: Axel Chao, 2011, Present position: Staff Scientist, SLAC • Ian Blumenfeld, "Scaling of the Longitudial Electric Fields and Transformer Ratio in a Non Linear Plasma Wakefield Accelerator,“ Advisor: Alex Chao, 2009, Present position: Scientist, Modeling Group, Archimedes Inc.

• Neil Kirby, "Properties of Trapped Electron Bunches in a Plasma Wakefield Accelerator," Advisor: Alex Chao, 2009, Present position: Postdoc, Radiation Oncology Department, UC San Francisco.

• Chris Sears, "Production, Characterization, and Acceleration of Optical Microbunches," Advisor: Robert Siemann, 2008, Present position: MPI Munich.

Stanford Graduate Student Orientation, 9/20/2012 22

Summary

Accelerator R&D is a major effort at SLAC and there are a very broad range of potential thesis topics • • Theoretical, simulation, and experimental Many problems require effort all three SLAC as a national lab has fantastic R&D facilities and a strong faculty and staff and one of the best PhD programs 8 of the 20 American Physical Society Division of Particle Beam Thesis Award recipients to date completed their graduate research at SLAC: • • • • • • • • Dan Ratner , a student of Alex Chao’s (2012) Ian Blumenfeld , a student of Alex Chao’s (2011) Dmitry Teytelman , a student of John Fox (2004) David Pritzkau , a student of Bob Siemann (2003) Boris Podobedov , a student of Bob Siemann (2002) Shyam Prabhakar , a student of John Fox (2001) Zhirong Huang , a student of Ron Ruth (1999) Tor Raubenheimer , a student of Ewan Paterson (1994) Come talk to us and don’t forget the tour: 1:30 pm from ROB parking lot Stanford Graduate Student Orientation, 9/20/2012 23