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New materials for (High Energy) Physics
Harry Weerts HEP division
How expertise from one field needs from others
fields result in new approaches and enable basic
research ( in materials) to be directly applied
in HEP and beyond.
Material Science Nuclear Physics High Energy
Physics Photon Science (APS)
BES NP HEP BES
Involved
A strength and a focus at Argonne exploit this
to benefit all
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Plan for today

• Arise from a need in accelerators ( HEP NP)
• Reduce cost of large detectors, improve
  resolution and capabilities of sensors (HEP ?
  BES, HS)
• Apply cutting edge material science techniques to
  new cavities and sensors.. instead of older
  technology

Describe/outline two projects
All of the above needs, desire, expertise and
collaboration met within Argonne
Work plans proposals put together in 2008
Involves other institutions
(LDRD help)
Funding and set up to do work in progress
Initial ARRA funding from HEP
Two projects

1. Development of large area, flat panel, picosecond
   resolution, cheap photo detectors
2. Development of new layered superconducting RF
   cavities with high acceleration gradients and
   better performance.

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Large area photo detectors
Current
Future
From sensors like this
Something like this
TO

• Use modern material science techniques
• Fast timing , order of psec
• Large area coverage i.e. reduce price
• (Re)establish knowledge base within labs
• Transfer technology to companies

Large H2O Cherenkov detectors planned 200M in
photo tubes reduce cost
Major goals
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Cartoon of a frugal MCP

• Put all ingredients together- flat glass case
  (think TVs), capillary/ALD amplification,
  transmission line anodes, waveform sampling

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Photo detector RD area overview 1
Main areas of RD
Photo cathode Start with conventional Bialkali
photo-cathodes and values of working parameters
and evolve into innovative solutions.

• Optimization of surface morphology use nano
  technology
• Optimize Work-function dielectric properties
  tailor accel. field

Develop Highly Efficient Photon Emitters
Micro Channel Plate (MCP) RD using advances
in materials science and nano-technology. Use
Atomic Layer Deposition(ALD) for emissive
materials (amplification) passive substrates.
Passive Glass Capillary substrate
New technology- use ALD to functionalize an
inert substrate- cheaper, more robust, and can
even stripe to make dynode structures
Passive Substrates-1

• Self-assembled material- AAO (Anodic Aluminum
  Oxide)

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Photo detector RD area overview 2
Main areas of RD
Readout Transmission lines, waveform sampling
Anode 50 Ohm stripline, long readout 2
ends CMOS sampling onto capacitors- fast, cheap,
low-power Sampling ASICs demonstrated and widely
used

• Transmission Line- simulation shows 3.5GHz
  bandwidth 100 psec rise (well-matched to MCP)

Simulation of EVERYTHING as basis for
design Modern computing tools plus experts allow
simulation - validate with data.
Transit Time Spread simulation
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Plans to Implement This
Have formed a collaboration to do this in 3
years. 4 National Labs, 5 Divisions at Argonne, 3
companies, electronics expertise at UChicago and
Hawaii RD- not for sure, but we see no
show-stoppers. Two paths lower risk, with
advantages high risk with high payoff
Funding just arrived work has barely started,
but team in place
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New layered SC cavities development
Quite a bit of history in SC cavities at Argonne
in PHY division
Niobium Superconducting RF Cavity Performance
Worldwide

• ANL is the world leader for low- and medium-
  velocity SRF niobium cavities
• We are approaching the limits of what can be done
  with niobium

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SC Cavities New Processing New Layered Surfaces
blt1
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Driven by nuclear physics
Four Decades of SRF Experience at Argonne
National Laboratory

• Worlds first superconducting linac for ions,
  ATLAS (1978-present)
• 68 superconducting niobium cavities
• The leader in development of new high-performance
  cavities for ion-linacs
• A dedicated full-time cavity cold test capability
• An experienced SRF team
• with over 70 man-years direct SRF experience
• A large state-of-the-art cavity rf surface
  processing facility
• Jointly operated by ANL and FNAL at Argonne

Continue in upgrades, ATLAS, CARIBU, high
intensity proton and ion sources. HEP Project-X
Coordinated by Argonne Accelerator Institute (AAI)
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Cavity Surface Processing Electropolishing/Clean
Assembly
Quarter-wave electropolishing, May 07
A Doublespoke cavity for high power SC linac
Joint ANL/FNAL electropolishing, June 08
Spoke cavity electropolishing, Jan 05

• Argonne has developed the technology for the next
  generation of high-intensity particle accelerators

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• Presently performing ATLAS upgrade using all of
  todays state-of-the-art techniques (CARIBU
  upgrade) world leading performance for this
  class of cavities

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SC Cavities New Processing New Layered Surfaces
A somewhat personal view
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Recently driven by future HEP ILC
blt1
HEP needs a linear electron collider in range
0.5-1 TeV
Driven by nuclear physics
Only available buildable option is cavity based
linear collider
? Need reliable, reproducible SC RF cavities
with gt 50MV/m
Four Decades of SRF Experience at Argonne
National Laboratory
Building cavities not easy Reproducibility of
performance difficult Processing, chemical
surface treatments Close to limit of performance ?

• Worlds first superconducting linac for ions,
  ATLAS (1978-present)
• 68 superconducting niobium cavities
• The leader in development of new high-performance
  cavities for ion-linacs
• A dedicated full-time cavity cold test capability
• An experienced SRF team
• with over 70 man-years direct SRF experience
• A large state-of-the-art cavity rf surface
  processing facility
• Jointly operated by ANL and FNAL at Argonne

Continue in upgrades, ATLAS, CARIBU, high
intensity proton and ion sources. HEP Project-X
It has been and is a struggle
?Need to continue current efforts ( at many
places) also need new approaches
_at_Argonne
Go back to basic science of materials
superconductors at RF AND use a unique tool
Coordinated by Argonne Accelerator Institute (AAI)
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Niobium surfaces are complex, important, and
currently poorly controlled at the nm level
Inclusions, Hydride precipitates
Surface oxide Nb2O5 5-10 nm
Residue from chemical processing
45 nm RF depth
Interface sub oxides NbO, NbO2 often not
crystalline (niobium-oxygen slush)
Interstitials dissolved in niobium (mainly O,
some C, N, H)
e- flow only in the top 45 nm of the
superconductor in SRF cavities!!!
Clean niobium
Grain boundaries
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Argonne brings experience and unique expertise

• NP has driven SRF research for 4 decades
• 1st system 1978
• Cold test facilities
• RF Cavity processing facility
• HEP
• New SRF technology is required for next
  generation machines
• Nb is now at materials limits
• HEP has significant expertise in new high
  gradient cavity designs
• MSD
• World leader in superconducting materials (Nobel,
  Academy, etc)
• Important synthetic expertise (ideally suited for
  large area cavities.)

The collaboration is already succeeding!
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ALD Can Produce Layered SRF Structures with
significantly higher Hc1 than Nb

• Build nanolaminates of superconducting
  materials
• 50- 150 nm layer thicknesses with 10 nm Alumina
  Between.
• Hc1 Enhancement Scales with Tc,laminate/Tc,base
• For 2 NbN laminate layer -gt 1.5 HC1 enhancement
• 50 MV/m -gt 75 MV/m

B 1 T
B 0.15 T
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Summary cavities

• Our short term goal is 30 improvement in SRF
  performance.
• Cavity design Processing
• Atomic Layer Deposition for thin films
• So far ( with LDRD funds) we have
• Identified lossy magnetic oxides in Nb that can
  explain Q drop.
• Nb coupon tests show lower SC losses after
  baking.
• Demonstrated improved performance in an ALD
  treated SRF cavity.
• Fabricated a new full-time 2 Kelvin SRF test
  cryostat.
• Long term goals
• Continue to advance the state-of-the-art
  (ATLAS, Project-X)
• for SC linacs, ions protons
• Optimize Eacc and Q in layered superconductors
  (improve ILC, ERL designs)
• Explore new materials
  (possible big breakthroughs)

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Summary
Two examples of a new direction at Argonne
Based on available expertise, basic material
science capability to design new materials
desire to improve accelerator detector
capabilities.
Apply modern materials science capabilities to
problems/ needs/desires of other sciences.
Improve performance and availability of new
photo detectors of accelerators. Everybody
involves benefits Convert basic science
immediately to application and benefit another
science. Future extend this theme to other
areas ( photon science involve nanoscale
materials, biology sensors, etc.)
Argonne Accelerator Institute (AAI) coordinates
accelerator RD activities. Detector/Sensor
center is being planned.
Initially this will benefit HEP, but ultimately
it will benefit many fields of science and many
other applications ( photon science, medical,
homeland security, etc).
Now something real tour of cavity processing
facility
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Backup slides
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Nano-structured Photocathode Development

• Bernhard Adams, Klaus Attenkofer (APS) Mike
  Pellin, Thomas Prolier, Igor Veryovkin, Alex
  Zinovev (MSD) Jeff Elam (ES)

Develop Highly Efficient Photon Emitters

• Optimization of surface morphology
• Optimize Work-function dielectriv properties
  tailor accel. Field
• Photon-trap geometry reduce refelection losses

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MCP RD using advances in materials science and
nano-technology
Argonne has unique world-class resources in MSD,
APS, ES, and MCS Divisions.
Passive Substrates-1
Functionalization ALD

• Self-assembled material- AAO (Anodic Aluminum
  Oxide)- Hau Wang (MSD)

• New technology- use Atomic Layer Deposition to
  functionalize an inert substrate- cheaper, more
  robust, and can even stripe to make dynode
  structures (?)

Passive Substrates-II Incom Glass Capillary
substrate
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Readout Anode structure
Couple 1024 pads to strip-lines with
silver-loaded epoxy
Anode Design and Simulation

• Transmission Line- readout both endsgt pos and
  time
• Cover large areas with much reduced channel
  account.

Measurements in ANL laser test-stand
Comparison of measurements and simulation

• Transmission Line- simulation shows 3.5GHz
  bandwidth 100 psec rise (well-matched to MCP)
• Measurements match velocity and time/space
  resolution very well.

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MCP Simulation
Transit Time Spread

• Zeke Insepov (MCSD) and Valentin Ivanov
  (Muons,Inc)

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Recent Test Results for 1.3 GHz Single cell
cavities processed at ANL and tested at FNAL
High-pressure rinsing
Ultrasonic Cleaning
Electropolishing
Quality factor
 Cavity Eacc MV/m
NR-1 26.5
TE1AES004 39.2
TE1AES005 36.3
TE1ACC002 37.1
TE1ACC001 41.3
TE1ACC003 42.1
Accelerating Gradient (MV/m)
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Introduction ANL Approach For Next Generation
New
Back to basic understanding of materials
compatibility
Understand SC material at coupon scale (layered
materials)
Argonne approach
Guided by theory experience
Use Atomic Layer Deposition (ALD)
Apply what learned from coupons ? cavities
ALD allows same treatment of coupons cavities
Use SRF cavity expertise processing (JLAB ANL)
Test cavity performance (JLAB and .ANL)
Argonne is the unique place where this is possible
Multi division effort driven by expertise,
available infrastructure/tools desire for
improving accelerators
Done Started small scale Future New cavity
construction and structures
Proof ALD layers work ----------------------- Imp
rove existing Nb cavities ---------------- Develo
p best layers for NB based cavities -- New
layered structures, new materials ----- ????
Steps
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J Lab Cavity After ALD Synthesis (10 nm Al2O3
3 nm Nb2O5)

• Only last point shows detectable field emission.
• Emax increased by 40, Q increased by 3x at high
  field, suppress field emission

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Point Contact , XPS Understanding Cavity Eacc
and Q
Cavity-grade niobium single crystal
(110)-electropolished
2?
Baked Niobium 120C-24h
Ideal BCS, T1.7K
Unbaked Niobium
Average ZBC ratio 1.6
Qo improvement ? 1.6
Best fit Magnetic impurities -gt cause
dissipation on the surface -gt explain mild baking
improvement
ILC-Single crystal cavities P.Kneisel
T.Proslier, J.Zasadzinski, M.Pellin et al. APL
92, 212505 (2008)
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Mike Pellin
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Improve performance by Atomic layer deposition
of Al2O3 Annealing in UHV
2?
ALD coated Baking gt 500C-20h
Best Mild baked (120oC-20h)

• Use Atomic Layer Deposition (ALD) to synthesize a
  dielectric diffusion barrier on the Nb surface
• Bake cavity to dissolve the O associated with
  the Nb layer into the bulk
• It works !

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Mike Pellin