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
LEP-II
HERA
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
Electric Field Distribution
For more info contact:
Prof. Sami Tantawi
650-926-4454
Measured
SPEAR
bunch
SPEAR3 accelerator research
Short pulses/THz beamline
Accelerator optics/Nonlinear dynamics
PEP-X (future light source)
Gun development
Diagnostics development
James Safranek,
926-5438
4
3
2
1
y (mm)
- Characterize bunch shape
- Measure shielded CSR impedance
- THz for photon experiments
Flux: R0= 2 m; 1.2 T, 3.0 GeV, 1.000 eV; I 100mA
5
Calculated THz
• LDRD funding to design THz beamline
• Primary rotation research focus
• Beamline purpose:
0
-1
-2
-3
-4
-5
-5
-4
-3
-2
-1
0
x (mm)
Nonlinear dynamics:
simulated & measured
1
2
3
4
5
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)
2010: April2011: October2012: March2012: August2013: June2018: Sept.
2019: Sept.
Bypass LCLS Linac
In PEP Line
(extended)
New Beam Transport
Hall
Critical Decision 0 approved
Critical Decision 1 approved
Critical Decision 3a approved
Critical Decision 2
Critical Decision 3b
First FEL Light
Critical Decision 4
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
SLAC FEL R&D roadmap
LCLS-II injector
X-ray seeding
& brightness
2011-12
2013-14
HXRSS
TWFEL
LCLS-II completion
2015-16
2017-18
Soft X-Ray Self-Seeding
ECHO-7
ECHO-75, laser phase error
error
HHG efficiency and control
E-beam
brightness &
manipulation
ASTA (Cathode, Gun)
Ultrafast
techniques
Temporal diagnostics & timing
Injector R&D
S0 ITF: advanced beam generation, high-energy
compression and laser seeding
Attosecond x-ray generation
THz &
Polarization
THz
Polarization control
Technology
development
2019-20
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