ILC Positron TDR and R

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ILC Positron TDR and RD Meeting 1 OxfordILC
GDE Activities Updateand Undulator Scheme
Status

• J. C. Sheppard
• SLAC
• September 27, 2006

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Undulator Scheme
ILC GDE Activities Update, to date
December, 2005 Undulator Baseline Documentation
BCD March, 2006 RDR Configuration the
undulator scheme April, 2006 RDR Parts
Inventory to Technical Systems for Costing
July, 2006 RDR Preliminary Costing Results (the
Big Secret) August-September, 2006 Cost
comparisons between undulator and conventional
schemes central Injector layouts and initial
costing activities. September, 2006 GDE
Decision Undulator Scheme and Central Injector
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Undulator Scheme
ILC GDE Activities Update, thru end of calendar
2006
September, 2006 RDR Text Outlines (N. Phinney
editor) November, 2006 Valencia Meeting RDR
Text and Costs (???? rumors of short delay with
appropriate rescoping of RDR deliverables.)15
pages for undulator scheme not clear how
alternatives are being handled
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Layout of ILC Positron Source December, 2005
Undulator Scheme

• Photon production at 150 GeV electron energy
• K1, l1 cm, 100 m long helical undulator
• Two e production stations (1 as backup) KAS
• Pulsed OMD (shielded target)
• Keep alive auxiliary source is e side
• Timing Insert and Trombone in PML Extension

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Positron System Site Layout July 2006
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Positron System Site Layout Discussions
September, 2006
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Positron System Site Layout Discussions
September, 2006
Central Injector Discussions Electron dr and a
single positron dr in a single tunnel located at
the center of the ILC site Two 14 mrad crossing
angle IPs at a different elevation (10-20 m)
from drs Positron production still at 150 GeV
point in electron main linac e transport line
reduced from 18.7 km to about 5 km Removal of
timing insert (still need to do correct timing)
and 2nd IP trombone Looking at feasibility to use
e- source to make 500 MeV KAS drive electron
beam Cost reductions thru hardware reduction 30
km of low emittance, damped beam added to RTML
systems Ongoing discussions that have lives of
their own
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Positron System Site Layout Discussions
September, 2006
Impact to ongoing work for ILC Undulator
Scheme No real changes to the technical
challenges No parameter changes Reduction of
transport lines Rework of injection/extraction
schemes Still have same technical challenges
and cost drivers Work continues
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ILC Positron System Design and RD Goals in
Support of the TDR
Abstract Detailed positron systems designs and
documentation are required for the ILC TDR by the
end of FY09. The goal of the research and
development for the ILC positron systems is to
learn enough about the component and subsystem
technical requirements such that the scope of the
resource requests in the TDR are adequate and not
excessive. Included in the RD list are key
enabling technologies. Detailed systems
integration, design, and engineering for
manufacture are not considered herein.
Fabrication of production prototypes is to be
done as part of the construction phase of the
project.
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Undulator Scheme
RD Tasks Undulator OMD/Flux
Concentrator Target Station Remote
Handling Photon Collimation and
Stops Positron Stabilization Capture RF
Systems Fast Ion Instabilities Documentation
TDR
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Undulator Scheme
Tasks Undulator Demonstration of undulator
performance with a standard module Up to 200 m
of helical undulator with K1, l 1 cm, and
inner diameter gt 6 mm is required. The undulator
is a superconducting magnet design and is made
from modules which are 2-4 m in length. The goal
is this task is to select a technology (Nb-Ti or
Nb-Sn), specify the performance characteristics
(K value, aperture, length, tolerance), build and
measure the performance of a prototype magnet. A
beam test may not be required.
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Tasks OMD/Flux Concentrator A viable OMD
pulsed/shielded and or dc/immersed A strong
(7T), axial magnetic field at the exit of the
conversion target is required for efficient
capture of positrons. The device is called the
optical matching device (OMD) and serves
essentially as a point to parallel focusing
element. Two candidate technologies are presently
under consideration a pulsed flux concentrator
and a superconducting coil. In the former case,
the magnet filed rises rapidly (5mm) from zero
to full strength immediately downstream of the
target. In the latter case, the coil sits
upstream of the target and the field penetrates
the target. It is likely that a pulsed device can
be based on previous designs which need to be
improved for reliability. If the issues
associated with spinning the conversion target in
a strong magnet field can be successfully
handled, the immersion of the target in the field
offers an improvement in positron capture
efficiency by as much as 40 over that possible
with the field profile of the flux concentrator.
Because of the uncertainties in both candidates,
it is recommended that both technologies be
studies and developed.
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Tasks Target Station Rotating target assembly
compatible with OMD choice The positron
conversion target is a 1 m diameter annulus which
spins at about 2000 rpm. Approximately 30 kW of
average power deposited by the beam and perhaps a
similar amount of power due to eddy currents from
the OMD must be removed. The goal of this project
is to develop a prototype water cooled, spinning
target and to test the performance of the system
along with a functioning OMD as chosen in task 2.
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Tasks Remote Handling Remote handling strategy
and task descriptions The beam power in the ILC
positron vault is in the range of 350 kW. The
target and much of the downstream accelerator
components and ancillary infrastructure will
become activated. To facilitate maintenance and
repair, it is necessary to develop remote
handling techniques and systems for this area. It
is likely that much of what is required can be
adapted from facilities which have similar
issues, such as the SNS, ISIS, various hot cell
facilities, and perhaps reactor installations. It
is recommended that existing remote handling
facilities and techniques be studied for
application and unique needs for the ILC positron
vault be identified. A strategy for remote
handling must be developed and a design for this
capability needs to be developed and fully
integrated into the positron system. A simulation
of component and vault dose and activation is
required.
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Tasks Photon Stops and Collimation Photon stops
and photon collimation Positron polarization
can be enhanced by collimating the incident gamma
beam. Some designs call for cutting as much as
50 of the incident photons which corresponds to
an average power of up to 175 kW. As a separate
issue, it is necessary to collimate large angle
gammas along the length of the undulator to
prevent unwanted energy deposition along the
undulator. While the power levels are reduced
from that of the main photon collimator, the
spectrum of the photons is similar to those
absorbed by the main collimator. The goal of this
research is to develop the photon collimator and
photon stops, prototyping and testing as
necessary.
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Tasks Positron Stabilization Stabilization
schemes intensity control, fault recovery
Positron intensity fluctuations arise from
variations in the drive electron beam intensity
as well as due to drift and jitter in the
positron system itself. The goal of this task is
to identify all potential sources of intensity
jitter, invent solutions and work arounds, and to
develop hardware as necessary.
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Tasks NC RF Normal conducting structure
demonstration of achievable gradient and power
handling capability (separate presentation if
time permits or will add to meeting notes)
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Tasks Fast Ion Instability Fast ion instability
mitigation in undulator, as required (Expect
this to be resolved in FY07 presently have a
vacuum specification of 100 nTorr which is under
discussion)
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Tasks TDR Development Positron System Design
and Optimization Positron accelerator system
design and optimization studies. The goal of this
task is to produce the positron system
documentation required for the ILC TDR. This goal
includes complete specifications for all aspects
of the positron system and full integration with
the ILC.
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Challenge The foregoing need better definition
in terms of work packages need to do what is
required for the TDR, need to push off what can
not be accomplished into construction. Need to
avoid duplication if possible Need to run in
parallel as needed Important to develop and
implement a global entrerprise
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