SLAC NATIONAL ACCELERATOR LABORATORY
ACCELERATOR RESEARCH DIVISION
January, 2011
FY2011-Q1 Quarterly Report (Oct-Dec, 2010)
Table of Contents:
1. ARD Administration 2
2. Advanced Accelerator Research Department 3
AARD – Microwave 3
AARD – Plasma 5
AARD – Laser 5
AARD – Feedback & Dynamics 6
3. Beam Physics Department 7
Collective Effects 7
FEL Physics 9
Advanced Computation 10
Beam Optics & Non-Linear Dynamics 11
4. Accelerator Design Department 11
ILC 12
FNAL Project-X 13
X-Band 14
LARP 15
SuperB 16
5. Accelerator Physics & Engineering Department 16
ATF2 16
CTF3 16
FACET 17
LCLS 17
LCLS-II 18
LHC 18
6. Test Facilities Department 18
ASTA 19
NLCTA 19
FACET User Area 20
End Station A 20
End Station B 20
ECHO Experiments 20
7. FACET Construction 21
A U.S. Department of Energy Research Facility Operated Under Contract by Stanford University
Accelerator Research Division Quarterly Report – 2011/Q1
1. ARD Administration
The Accelerator Research Division (ARD) is a division within SLAC’s Accelerator Directorate. The
division is supported with an annual budget of roughly 40 M$ from the US Department of Energy,
Offices of Basic Energy Science and High Energy Physics. It consists of roughly 110 physicists,
engineers and technicians, including 5 Stanford faculty members, and is divided into five departments:
Advanced Accelerator Research
Beam Physics
Accelerator Design
Accelerator Physics and Engineering
Test Facilities
ARD’s mission is to develop accelerator science and technology that will enable new accelerators in
photon science and high energy physics as well as other fields of science, medicine and industry with
R&D aimed at near-term, mid-term, and long-term development. It has a world renowned research
program in advanced acceleration techniques and is engaged in R&D on some of the most advanced
accelerators in the world including the Large Hadron Collider at CERN and the Linac Coherent Light
Source at SLAC. The division operates three test facilities dedicated to accelerator research: the
Accelerator Structure Test Area, the NLC Test Accelerator and the FACET facility.
This report is intended to highlight ARD’s research program and describe progress and advances made in
the previous fiscal quarter. Its intended audience is the Directorate and Laboratory management. In
addition it is will help ARD staff understand the breadth and strength of the division research program
and work that their colleagues are engaged in.
General and more specific information about ARD can be found in:
slacportal.slac.stanford.edu/sites/ard_public/Pages/Default.aspx and the ARD organization chart is shown
in: slacportal.slac.stanford.edu/sites/ard_public/SiteCollectionDocuments/ARDOrgChart-feb-2011-
v2.pdf.
The first quarter of FY11 was a very busy time. In late September, the LCLS-II baseline was changed
from an expansion using the existing tunnel to a two-tunnel option. The two-tunnel option has greater
expansion capability. DOE endorsed this decision which was great news but then wanted a CDR by
March/April of 2011! Next, there was a one-day workshop organized by the DOE BES on Test Facilities
for Accelerator R&D and utilization of the user facilities such as SPEAR and LCLS for accelerator R&D.
This was then followed by a meeting of the OHEP advisory committee P5 to consider additional
operation of the Tevatron at Fermilab – it recommended, yes, provided additional operation funds could
be found. Then the CLIC/ILC workshop was held at CERN and then the SLAC AED review was held at
SLAC. That was October!
In November, Norbert Holtkamp joined the lab and started helping ARD develop a more focused, well
supported program. The primary challenge ahead is determining the direction of the linear collider
program and the future of the normal conducting rf R&D while strengthening the FEL R&D program to
enable SLAC to remain a leader in the field of x-ray FEL’s.
Norbert has set up a blog: https://slacspace.slac.stanford.edu/sites/ad/blog/default.aspx, an email inbox:
https://slacportal.slac.stanford.edu/sites/ad_public/suggestion/Pages/default.aspx and has an open door
policy for anybody with ideas on how to improve the accelerator operations or research programs at
SLAC.
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Accelerator Research Division Quarterly Report – 2011/Q1
During the Fall of the academic year 2010-2011 one accelerator physics course was taught by Prof. Ron
Ruth entitled Introduction to Accelerator Physics (APP-324). This course is a broad introduction to
accelerator and beam physics and this year included a laboratory at SPEAR III near the end of the course.
The enrollment was very successful and included 9 registered students and several other regular auditors.
The laboratory was especially popular and the performance by the students was outstanding. This spring
the education committee will meet to discuss graduate student supervision policy and courses for next
year.
Finally, ARD is organizing Invited Accelerator Seminars again for the SLAC community:
https://slacportal.slac.stanford.edu/sites/ard_public/ardhq/seminars/Pages/default.aspx. The first two talks
in January will be by Michael Borland and then Claudio Pellegrini. Please send suggestions for future
seminars to Mike Litos: litos@slac.stanford.edu.
2. Advanced Accelerator Research Department
The Advanced Accelerator Research Department (AARD) is dedicated to basic and applied research in
accelerator science with the goals of advancing the state-of-the-art and educating accelerator scientists.
Our investigations lie at the forefront of accelerator physics, and incorporate a wide variety of fields
ranging from microwave engineering, plasma physics, electromagnetic theory, and ultra-fast lasers to
physical optics, materials science, formal control theory, ultrafast electronics, and nanofabrication
engineering and design. AARD efforts focus on understanding and extending the limits of accelerator
technology to expand capabilities in energy, luminosity, beam power, and timescale to extend the reach of
discovery science. Primarily developed for High Energy Physics and Basic Energy Science, these
accelerator technologies will also benefit medicine, food safety, biology, and homeland security.
The department consists of four groups focusing on the four main research directions:
Microwave : Development of normal conducting accelerators and power sources, with a focus on
understanding the limitations in high-gradient and high-frequency microwave structures.
Plasma: Use of short, intense pulses of electrons and positrons to create waves in a plasma
(ionized gas) capable of producing orders of magnitude higher accelerating gradients than
traditional accelerators
Laser: Investigation of techniques for accelerating electrons and positrons using lasers and
dielectric microstructures, with acceleration gradients orders of magnitude larger than traditional
accelerators
Feedback & Dynamics: Development of novel ultrafast and wide-bandwidth electronic circuits,
signal processing systems, and laboratory measurement techniques for particle accelerators
AARD—Microwave
High Gradient Research:
Structure Manufacturing Technology (Collaborative work with CERN & KEK)
o Coordinated the work for two TD24_VG1.8 structures. They are under construction.
After the completion, one with SLAC flanges will be tested at the NLCTA and one with
KEK flanges will be shipped to Japan.
o Organized and performed the chemical etching studies on the parts for high gradient
accelerator structures. Historical records for the structures in past years and SEM,
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Accelerator Research Division Quarterly Report – 2011/Q1
microscopic pictures taken before and after various etching times were analyzed in order
to make decision for the processing of future structures.
o Participated design and fabrication for three short deflectors: calculated all RF parameters
for T11 and T27 structures; submitted the job and worked on various fabrication related
issues.
o Worked to produce a T105 accelerator structure: collected available and usable parts;
arranged and monitored the QC procedures; prepared the work for coupler electrical
design and mechanical design integration.
Novel Structure Designs
o Designed structure for test of optimized shaped cavity (three cells – optimized cavity cell
and two coupling cells)
o Completed design study of accelerator cavity geometry to be used in parallel-fed standing
wave accelerator structure
o Generated concept for planar (2D) construction of parallel-fed standing wave accelerator
structure
o Cryogenic system to test normal-conducting accelerating structures at cryo-temperatures.
o Developed Structure made of stainless-steel plated with Cu.
High-Gradient Experiments
o Tested Hard-CuCr high-shunt-impedance 1C-SW-A3.75-T2.6-Clamped-CuCr-SLAC-#1.
o Tested Dual-feed-side-coupled high-shunt-impedance 1C-SW-A3.75-T2.6-2WR90-Cu-
SLAC-#2.
o Tested Hard-copper highest-shunt-impedance 1C-SW-A2.65-T2.0-Clamped-Cu-SLAC-
#1.
o Manufactured two accelerator structures for advanced in-situ diagnostics, Single-cell-sw-
structure with viewport 1C-SW-A3.75-T2.6-Ch-ViewPort-Cu.
o Manufactured New pulse-heating cavity with viewports for in situ diagnostics
o Tested CERN Power-Extraction and Transfer structure PETS2.
o Tested 10 Cell Traveling wave structure C10-VG0.7.5
Manufactured and delivered to collaborators:
o Hard-copper-cells for advanced coating to Yale.
o Mode launchers for Argonne National Lab.
RF Undulators
o Written a new set of Codes capable of optimizing the RF structure through generic
algorithms
o Designed the first RF undulator and cold tested a section to verify the results of the
optimized design
o Design novel Devices which is capable of producing K=1 at 1.35 cm undulator
wavelength with a reasonable RF power levels.
Superconducting Material Research
o Tested New stratified Media based on MgB2
o Tested Single crystal Nb
o Designed a new structure cavity for testing residual resistance.
Publications and Talks
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Accelerator Research Division Quarterly Report – 2011/Q1
o Invited Talk at ECLOUD 10 workshop “Control of Transverse Intra-Bunch Instabilities
using GHz Bandwidth Feedback Techniques” - Claudio Rivetta et al
o “RF system models for the CERN Large Hadron Collider with application to longitudinal
dynamics”. T. Mastorides, C. Rivetta, J.D. Fox, D.Van Winkle, (SLAC), P.
Baudrenghien, (CERN). Oct. 1, 2010. (Published Oct. 1, 2010). 11pp. Published in
Phys.Rev.ST Accel.Beams 13:102801, 2010.
o Multiple talks at the November 2010 LARP collaboration meeting, LLRF results
presented by CERN at the Evian LHC meeting.
AARD – Plasma
FACET
o Completed internal review of FACET proposals in advance of SAREC review (with other
TFD, S20, ARD staff)
o Developed solution to simultaneously deliver full beam rate in S0-19 for linac feedback
systems with reduced rate to FACET S20 IP – necessary for PWFA and all experiments
using notch collimator.
o Worked with RP to develop shielding solution for notch collimator area of S20 beamline
o Worked with controls department on ongoing integration of high-performance CMOS
cameras and plasma oven hardware into EPICS DAQ and control system
o Worked with Bill White’s group to identify and layout future experimenter laser room
and system in NW corner of LCLS laser building
o Improved particle tracking model of S20 beamline to quantify emittance growth due to
chromaticity, ISR and CSR.
Publications and Talks
o Two invited talks on PWFA: Super-Strong Fields in Plasmas and SciDAC Compass
AARD – Laser
NLCTA Beam Tests
o Record emittances 30fs (sometimes 100fs). This is being investigated and is
expected to be corrected next quarter along with the installation of further upgrades.
o An experiment at SXR demonstrated the use of a GaAs crystal to perform a direct X-ray /
Optical cross correlation with <60fs resolution, with the promise of considerably improved
performance in the future. This is being investigated as a general purpose timing diagnostic
for experiments.
o After a conceptual design was completed at SLAC, last quarter engineering responsibility for
the hard X-ray seeding system was transferred to ANL, though SLAC will likely remain
responsible for controls and commissioning.
o Short bunch (few-femtosecond) operation of the LCLS based on low charge (20-40pc) and
the slotted spoiler is regularly used by experimenters, however the existing diagnostics cannot
resolve bunches below 20 femtoseconds. Last quarter a conceptual and optical design of a
single shot broad-band (6-50um) infra-red spectrometer for bunch length measurement was
completed. This system will be constructed and initial testing is expected next quarter. An
upgrade to the slotted foil system is also under development.
o The assembly and vacuum testing of the thermal-acoustic X-ray energy monitor was
completed last quarter. Next quarter the system is planned to be installed and commissioned
to provide absolute X-ray flux measurements
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Accelerator Research Division Quarterly Report – 2011/Q1
o Last quarter the LCLS THz system was commissioned with THz energies up to 140 J. Initial
demonstration measurements showed non-linear absorption in GaAs, physics not accessible
with any other source.
o Last quarter materials testing in the X-ray diagnostics chamber allowed the selection of
several materials for use as X-ray attenuators. Next quarter the Be attenuators in the FEE are
expected to be replaced with diamond and sapphire to reduce X-ray beam distortions.
LCLS_II: The LCLS_II is a project to construct a new XFEL facility at SLAC to provide
additional capacity for more simultaneous user experiments.
o The layout of the LCLS_II undulators and X-ray system was completed last quarter. The
extended soft X-ray wavelength range of the LCLS_II introduces significant damage issues
for stoppers and mirrors resulting in complex design trade-offs.
o Conceptual designs for the LCLS_II gas attenuator and X-ray beam stopper systems were
also completed last quarter.
o Next quarter we expect the LCLS_II CDR to be completed.
LHC: Large Hadron Collider at CERN.
o The LHC synchrotron light monitor is used to measure beam profiles and to detect particles
in the abort gap. Last quarter this system was operated successfully with Lead ions. Work is
underway to upgrade the optical system to provide halo measurements, with initial results
expected next quarter.
o The forward proton detector system at LHC requires few-picosecond timing stability over
several hundred meters. Last quarter a copy of the coax distribution system developed for
LCLS demonstrated the required stability (scaled with cable length). Next quarter the system
will be tested with the full 500M cable length required for the LHC.
o Last quarter the DCCT used to measure average current showed fill-pattern sensitivity. This
was traced to saturation in the feedback gain chain as well as to inadequate high frequency
RF bypassing of the ceramic gap. These are being fixed in the present shutdown via a re-
partitioning of the gain profile and improvement of the RF bypass with an increase of
capacitance and (probably) the addition of a passive ferrite ring. A further potential problem
in the feedback gain/phase distribution has been identified and potential solutions
investigated. The LHC fast current transformer showed position sensitivity, the cause of
which has been identified, and solutions are being investigated.
6. Test Facilities
The mission of the Test Facilities Department (TFD) is to operate and support the test facilities at
SLAC that are utilized to develop and test near-term solutions for accelerator issues. RF
structures and power sources as well as beam optical, diagnostic and collimation systems are
tested in these facilities. The major test facilities are the Next Linear Collider Test Accelerator
(NLCTA), Accelerator Structure Test Area (ASTA), and L-band RF test facilities at End Station
B. TFD also supports the operation of FACET, End Station A (ESA), and the ATF/ATF2
program at KEK and works closely with the Klystron and the Power Conversion R&D groups.
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Accelerator Research Division Quarterly Report – 2011/Q1
ASTA report: The ASTA facility includes two s-band 50 MW klystrons who output can
be combined, a variable length pulse compressor with an output of up to 500 MW and an
extremely flexible RF system that is well suited for fast turnaround of experiments. The
ASTA bunker’s shielding is rated for up 100 MeV beam energies. At present is used
extensively for testing of all sorts of short RF structures and for testing materials that can
be used in RF structure manufacture. With a modest upgrade ASTA can be used to test
RF guns. The past quarter activities in ASTA were:
o Operations for the High Gradient structure tests (see also AARD-Microwave
report, PETS2 and C10-VG0.7.5).
o Planning for relocation of the cryogenic test stand into the ASTA vault.
o Planning for upgrading facility for 24/7 and for remote operations from the
NLCTA control room. 24/7 operation requires design and installation of a fire-
suppression system for the modulators. Remote operations require upgrading the
ASTA control system to EPICS and upgrading the monitoring systems for remote
readout and display. Parts for the remote operation of ASTA have been purchased
and are being installed. The fire suppression system is under design review by
SLAC.
o A design for a spectrometer magnet can be use to characterize dark current
coming out of an RF gun.
NLCTA report: The NLCTA facility is housed in End Station B (ESB). At its heart is a
former 320 MeV x-band linac (from the NLC project) with an s-band injector and an
output beam line and dump. The accelerator components are in their own enclosure inside
the ESB hall. The past quarter activities using NLCTA were:
o Provide beam for E163 and the ECHO experiments (see also AARD-Laser for
more E163 information).
o An experiment to generate THz radiation was conducted, but was unsuccessful.
o A CSR experiment (in collaboration with UCLA) had its first run.
o Provide a home for testing x-band RF.
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Accelerator Research Division Quarterly Report – 2011/Q1
o Revived the x-band two-pack for plasma switch testing and for future use in the
NLCTA accelerator.
o Start upgrading the NLCTA beam line with addition of two transverse cavities for
improved slice emittance measurement for the ECHO-7 experiment.
o Start the design of a new x-band test station in the beam dump area. This station
will have an x-band gun and some beam acceleration capability.
FACET User Area report: In anticipation of FACET construction completion, planning
on the experimental user area and the purchase of a trailer for FACET users is proceeding.
End Station A: It is planned to have a new electron test beam in ESA (End Station Test
Beam, ESTB). First operation of the ESTB is expected in summer of 2011. This test
beam will provide the full range of electron energies up to 13.6 GeV, and intensities from
single particles to .25 nC/ bunch. It will be used primarily for detector R&D and machine
developments. The designs for kicker magnets and ceramic beam pipes to extract and
transport beam from the LCLS linac to ESA have been completed and are being
fabricated. The design for the PPS system for ESA and procurement of PPS parts has
been started. A one day workshop will be held on March 17, 2011 to disseminate
information about ESTB capabilities and progress and to ascertain user interest.
End Station B: In addition to housing the NLCTA, ESB also supports a range of high
power RF source development activities (in collaboration with the Accelerator Design
Department and others).
o MARX modulator testing. The failure of the MARX modulator capacitors under
full load has led to a study to measure capacitor aging. In the meanwhile the
MARX modulator is being run at reduced pulse width but with same power.
o The Cluster-Klystron concept prototype was installed on the NLCTA enclosure
roof and tested. Planning for a full scale test (160 meter big pipe) installed in the
ESB has started.
o The two-pack system LLRF has been upgraded and modulator mods have been
made to facilitate design testing by AED’s Power Conversion Department. A fire
suppression system for the two-pack system has been installed.
o TTF3 coupler testing.
ECHO Experiment: Echo-7 is a proof-of-principle echo-enabled harmonic generation
(EEHG) experiment which is being performed at the NLCTA at SLAC. The experiment
aims to test the physics of the EEHG concept and demonstrate scaling. The 3rd, 4th, 5th,
7th, and possibly 15th harmonic of a 1590nm seed laser will be generated through the
EEHG scheme. In contrast to other schemes for generating harmonic bunching (e.g.
HGHG), higher harmonics can potentially be reached with EEHG; in fact, due to the
remarkable up-conversion efficiency, soft x-rays may be reached directly from a UV seed
laser.
o After a successful summer run which provided a qualitative confirmation of the
ECHO theory, planning for an experiment aimed at making quantitative
measurements by summer of 2011 are underway
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Accelerator Research Division Quarterly Report – 2011/Q1
7. FACET Construction
The FACET project received CD2/3 approval in July, 2010 and established a baseline as of the
end of September. In that baseline, the project was 59% complete and held 2.1M$ of
management reserve on an estimated cost to complete of $5M. During Q1 FY2011, installation
began on cable plant, support stands and vacuum infrastructure. Controls and power supply racks
were pre-assembled in the rack factory, transported out to klystron gallery and installed, leaving
only final connections to be made. Two additions to the project scope were approved, the
personnel protection system modifications needed for FACET and the experimental users trailer,
for a total of about $500K. At the end of the quarter, the project was 80% complete and held
1.3M$ of management reserve on an estimated cost to complete of 2.6M$. The FACET
installation in Sector 20 is expected to complete in April, 2011.
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