MuCool Program

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MuCool Program

• Muon Cooling RD
• Alan Bross

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MuCool

• Mission
• Design, prototype and test all cooling channel
  components
• 201 MHz RF Cavities, LH2 absorbers, SC solenoids
• Support MICE (cooling demonstration experiment)
• Perform high beam-power engineering test of
  cooling section components

• Consists of 10 institutions from the US, UK and
  Japan

RF Development ANL Cockcroft Institute Fermilab II
T JLAB LBNL Mississippi
Absorber RD Fermilab IIT KEK NIU Mississippi Osak
a
Solenoids LBNL Mississippi
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MuCool Test Area

• Facility to test all components of cooling
  channel (not a test of ionization cooling)
• At high proton beam power
• Designed to accommodate full Linac Proton Beam
  Power
• 1.6 X 1013 p/pulse _at_15 Hz
• 2.4 X 1014 p/s
• 600 W into 35 cm LH2 absorber _at_ 400 MeV
• RF power from Linac (201 and 805 MHz test stands)
• Waveguides pipe power to MTA

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MTA Hall
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MTA

• The MTA is the focus of our Activities
• RF testing (805 and 201 MHz)
• High pressure H2 gas-filled RF
• LH2 Absorber tests
• High Intensity Proton Beam
• Will start with low intensity

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MTA Hall Instrumentation
Chipmunk
Plastic Scintillator
805
CsI
201
Magnet
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RF Cavity R and D

• ANL/FNAL/IIT/LBNL/UMiss

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RF RD Program

• Basic Questions
• Can we do anything to make MICE work better?
• How does magnetic field affect rf cavities
• What materials and material properties are
  desirable?
• What surface modification is possible?
• NF and Muon Colliders also require SCRF, Can we
  optimize this?
• Accomplishments
• Better understanding of conditioning with
  magnetic field in 805 cavity.
• Full gradient operation of 201 MHz cavity in
  solenoid fringe field
• Installation of Be windows and button test
  assembly.
• Better modeling of breakdown limits.
• Involvement with SCRF and material science
  community

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RF RD Program II

• Major papers
• X ray Spectra, Nucl. Instrum. Meth. Phys. Rev. A.
  472, 600 (2001)
• http//www-mucool.fnal.gov/mcnotes/public/pdf/muc0
  139/muc0139.pdf
• Measurements of x-rays from a single cell cavity
• Open Cell Cavity, Phys. Rev. STAB 6, 072001
  (2003)
• http//link.aps.org/doi/10.1103/PhysRevSTAB.6.0720
  01
• Measurements of 6 cell cavity, dark current
  measurements, w/wo B fields, comp. with other
  cavities, tensile stress
• Cluster emission, Phys. Rev. STAB 7, 122001
  (2004)
• http//link.aps.org/doi/10.1103/PhysRevSTAB.7.1220
  01
• Emission of clusters, thermal and field
  dependence,
• Breakdown mechanics, Nucl. Instrum. and Meth A
  537, 510, (2005)
• http//www-mucool.fnal.gov/mcnotes/public/pdf/muc0
  286/muc0286.pdf
• General theory of tensile stress triggered
  breakdown
• Magnetic fields, Phys. Rev. STAB 8, 072001 (2005)
• http//link.aps.org/doi/10.1103/PhysRevSTAB.8.0720
  01
• Measurements with 805 MHz pillbox, measurement of
  s2(b)
• Surface damage, Phys. Rev. STAB 9, 062001 (2006)
• http//link.aps.org/doi/10.1103/PhysRevSTAB.9.0620
  01
• Relationship between surface damage and maximum
  operating fields.

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Fundamental Focus Of RF RD

• Study the limits on Accelerating Gradient in NCRF
  cavities in magnetic field
• We believe that the behavior of RF systems in
  general can be accurately described (predicted)
  by universal curves
• This applies to all accelerating structures

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805 MHz

• Data seem to follow universal curve
• Max stable gradient degrades quickly with B field
• Remeasured
• Same results
• Does not condition

Gradient in MV/m
Peak Magnetic Field in T at the Window
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805 MHz Imaging
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Next 805 MHz study - Buttons

• Button test
• Evaluate various materials and coatings
• Quick Change over

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Field Profile Button Cell

• Button Insert has replaced one of the curved Be
  windows
• Second Be window still installed facing out

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First Set of Button Data TiN Coated Cu
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TiN Coated Cu After Running
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TiN Coated Cu After Running II
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2nd Round of Button Tests
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Simplified layout of the Vertical mounting
To Existing Waveguide
New vertical Mechanical support holder
Current position in the magnet
The cavity will be moved into magnet about
half-in and half-out.
Anchored to base
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High Pressure H2 Filled Cavity WorkMuons Inc

• High Pressure Test Cell
• Study breakdown properties of materials in H2
• Operation in B field
• No degradation in M.S.G. up to 3.5T

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RF RD 201 MHz Cavity Design

• The 201 MHz Cavity 19 MV/m Gradient Achieved
• In low (few hundred G) B field. Still no
  breakdown. Limited by available power

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Opening the 201

• Shiniest Copper I have ever seen Jim Norem
  circa 2007

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201 MHz Curved Be Window before Installation
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201 MHz Cavity Operation in B Field

• Initial 201 MHz operation in B Field
• Limited to few hundred Gauss
• Using Fringe Field of 4T magnet (in blue)

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• Need Coupling Coil (2.5T) MICE design
• Shown in green schematically
• THIS IS A CRUCIAL TEST FOR MICE AND FOR NF MC
  in general
• High Gradient RF operation in a magnetic field

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MICE Coupling Coil for MTA
Pro/E drawing by C.S.Liu
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Absorber R and D

• IIT/KEK/NIU/Osaka/UMiss

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Absorber Design Issues

• 2D Transverse Cooling
• and
• Figure of merit MLRdEm/ds
• M2 (4D cooling) for different absorbers

H2 is clearly Best - Neglecting Engineering
Issues Windows, Safety
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Absorber Engineering

• Two LH2 absorber designs are being studied
• Handle the power load differently

Forced-Convection-cooled. Has internal
heat exchanger (LHe) and heater KEK System
Forced-Flow with external cooling loop
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Convective Absorber Activities

• First Round of studies of the KEK absorber
  performed in the MTA
• GHe used to input power

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Convective Absorber Activities II
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Convective Absorber Activities

• KEK Convector Absorber upgrades
• Electrical Heater
• New Temperature sensors
• LH liquid level sensor
• Have now been installed and system has been
  tested
• Ready for LH2 run
• After safety approval

Absorber Body being modified in Lab 6 at Fermilab
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LiH Test Program

• Produce encapsulating cast (not pressed) samples
• Small disks (5-10 cm)
• Test casting procedures
• Examine mechanical properties
• Destructive tests for voids
• Large disk (30 cm) for detailed thermal
  conductivity studies
• External Cooling Internal Heating
• Potential absorber for MICE Phase I
• Non-instrumented, no cooling

NOT
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Engineering Design for Large Disks
3/8 nut
Handle
Cap for copper tube
Guiding lid
High temp glass ceramic
High temp low k gasket
1 copper tube
High temp low k gasket
12 SS 316L ring
High temp glass ceramic
Thermocouples K (900C)
Supports
SS base plate attached to vibrator
Thermocouple holders
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Production of LiH Disks

• Only 1 vendor was found that would cast LiH
• After some reflection (and some input from
  Chemists from Argonne Lab), the vendor decided
  casting LiH was too dangerous (production of H2
  gas)
• Made a Third Attempt to work with Y12 (Oakridge)
• Found the engineer in charge of their LiH work
  and he suggested that that press (Hot (150C,
  Isostatic (30,000 psi) a loaf and machine parts
  to our specification from the loaf
• They have achieved 98 theoretical density using
  this technique
• They are doing RD on casting LiH for their
  internal programs, but do not recommend it for
  our application.
• It is very tricky due to the high temperature
  (700C ) and the large (30) shrinkage on cooling
• We are in the process of setting up a contract
  with them to make a disk for temperature studies
  and 1 or 2 disks for MICE
• Note The Li in their LiH is 6Li
• For the mass we will receive, our parts will be
  considered Nuclear Material
• PAPERWORK!!!

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Machined Lithium Hydride Disc

• Produced by Hot Isostatic Pressing
• Produced using existing mold design provided by
  vendor
• Tested by chemistry
• X-Rayed by Radiography to ensure no voids
• Machined to size as specified by FermiLab
• Dimensional inspected against final customer
  supplied specification
• Packaged in drum type container
• Shipped by Fed-X

12 Blind holes for housing thermo-couples
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1 thick foam board
1 copper tube with heater inside
High temp glass ceramic
The Set Up of the Thermal Test
High temp low k gasket
Machined LiH disc
12 dia steel ring
Thermocouples
Flexible cooling tube
Stainless steel base structure
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The Set Up Ready for the Thermal Test
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MuCool Phase II

• Cryo-Infrastructure Installation
• Beam Line Installation

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MTA Cryo-Infrastructure

• We are making good progress with completion of
  the cryo-plant and transfer-line system.
• Transfer line system parts complete
• Our goal is to install/commission the system this
  FY (well our goal was to install last FY)
• Before the shutdown (August) in we can start by
  June
• We define the beginning of the window to be when
  the cryo-plant is up and running (producing LHe)
• After the shutdown otherwise
• Our current operating costs (LHe) for the MTA
  magnet are 3-5k/week
• Fermilab is providing 100k of support for MTA
  operations
• Will allow us to run the magnet off LHe dewars
  for the remainder of FY07 if required

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Existing Dewar-Fed Cryogen System

• All of this is removed
• New (simpler) shield wall
• Will allow for easier pit access to hall
• More shielding needed for beam operations in MTA
  Hall

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MTA Refrigerator RoomArtists Conception
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Storage Area
GHe, LN2 Storage Heat Exch.
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Compressor Room
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Refrigerator Room
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Transfer Line System
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Transfer Line System
Valve Box Piping
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Completed Valve Box
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Refrig Room Valve Can
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Xfer Line
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MTA Beam Line Group
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MTA Beam Line

• 400 MeV beamline for the MTA has been designed
• Under Craig Moore/Carol Johnstone
• External Beams Department
• Engineering Design mature
• Cost
• Safety Analysis
• Linac Area and Beamline
• Shielding Assessment for MTA
• First Phase will be low-intensity
• Funded by Fermilab NFMCC
• Installation group now formed
• F. Garcia (Proton source group)

MTA
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MTA Beam Line
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First Beam Experiments

• Currently 5T magnet and 201 cavity on floor
  (below beam ht.)
• First experiments will pitch beam down to center
  of magnet
• Allows for early tests of gas filled cavity
  operation in intense beam
• Very-low integrated intensity
• Few full-intensity linac pulses

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• Beam Line commissioning begins in early 2008,
  first tests with beam in June
• Designed to accommodate full Linac Beam
• 1.6 X 1013 p/pulse _at_15 Hz
• 2.4 X 1014 p/s
• 600 W into 35 cm LH2 absorber _at_ 400 MeV
• Will start at low intensity
• Need Shielding upgrade (over-burden) for
  high-intensity

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Phase II

• Raise equipment to beam height
• Install cryo-infrastructure
• Valve box
• Transfer lines
• Weld system
• Connect to cryo-plant
• Expect 2-3 month duration with appropriate
  technical resources

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• Addition of Coupling Coil (B field studies of 201
  operation) requires the 201 MHz cavity to be
  rotated 180 degree

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MuCool Plans for the Coming Year

• 805 MHz RF studies Buttons (with and without B
  field)
• Materials tests
• Surface treatment
• E X B study
• 201 MHz RF
• Move cavity close to magnet and repeat studies _at_
  high (1T) B
• Begin thermal and mechanical tests on HIP LiH
  absorber prototypes
• Complete MTA cryo infrastructure installation and
  commission system
• Commission Beam Line
• First tests with Beam
• Test of HP H2 RF test cell with beam