12 GeV Upgrade Swapan Chattopadhyay

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12 GeV UpgradeSwapan Chattopadhyay
Hall D Collaboration MeetingNovember 2,
2001Indiana University
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The Accelerator
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Operations Successes in FY2000/FY2001

• Available beam in use by experiments (sum of
  three Halls)
• 8,449 hours in FY 2000
• 7,957 hours in FY 2001
• Accelerator operating routinely at energies up to
  5.7 GeV (nearly 50 above the design value of 4
  GeV)
• Injector using a strained gallium arsenide
  cathode for all experiments
• produces up to 80 polarization (compared to 40
  in FY 1999)
• up to 140 ?A per Hall (compared to ?A in FY
  1999)
• weeks between re-Cesiations
• quality beams for parity violation experiments
  delivered
• Fast feedback maintains energy spread of 10-5
  for weeks to single Hall
• energy spread of second Hall 3 x 10-5

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Availability Comparison by System FY99-FY01

• Issues
• Reduced flat-flat budget led to reassignment of
  staff
• Operation at higher energy of 5.6/5.7 GeV
  (conscious decision by Physics Division staff to
  increase the science productivity in the three
  halls)
• Maintenance

Vigilant Task Force established to understand
and improve availability
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Evolution of CEBAF from 4 ? 6 GeV

• Increased energy capability has been driven by
  our Users desire for physics not accessible at
  4 GeV
• It was made possible by the superb performance of
  the installed SRF cavities (50 above design
  spec.)
• As we push the limits of the machines
  capabilities, we are knowingly trading increased
  energy (and hence broader physics reach) for
  reduced accelerator availability
• 6 GeV with high availability requires completion
  of our klystron upgrade and the new (RD)
  cryomodules

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12 GeV Upgrade

• 12 GeV beam is the basis of our long range NP
  research program
• The research program using 12 GeV beam has been
  endorsed by NSAC
• JLab has developed a preliminary plan that could
  have research beginning in FY09
• There are no technological show-stoppers for the
  accelerator
• Accelerator Division staff is ready to move
  forward
• (Note Talks by L. Cardman, L. Harwood, and C.
  Rode to follow)

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Motivation for Accelerator Science and
Technology at JLab
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Color Mapping in QCD
NUCLEAR PARTICLE PHYSICS
t ltlt 10-18 sec.
Strategic Simulation Lattice-gauge QCD Code
Possible at JLabs 12 GeV Upgrade of CEBAF.
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Whats the Point?

• The 12 GeV Upgrade at Jefferson Lab aims at
  answering two core questions
• 1) What is the nature of quark confinement?
• Differently put why are quarks (the most
  fundamental building blocks of matter that has
  been observed) the only particles known in nature
  that do not exist as individuals, but rather only
  in close company with other quarks. This
  question has been identified in a National
  Academy of Sciences report as one of the ten most
  important questions for physics in the 21st
  century.
• 2) What is the fundamental nature of the
  nuclear force in terms of quark and gluon
  interactions?
• Measurements made possible by the 12 GeV Upgrade
  will provide a major leap forward in the
  transition from the present phenomenological
  model of the nucleon-nucleon force to an
  analytical model based on QCD. This question
  includes investigation of whether quarks behave
  differently when bound in a nucleus vs when in
  the near-free condition explored by elementary
  particle investigators and explained so elegantly
  by QCD.

Quark Confinement
Hall D
Analytical model (based on QCD) of nuclei as
groups of quarks
Halls A, B, C
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Observation of exotic mesons

• Need a way to create the exotic mesons and
  distinguish them from the background of normal
  mesons.
• 8-9 GeV polarized photons will do it.
• Can use 12 GeV electrons to create the photons.

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High-level Parameters

• Beam energy 12 GeV
• Beam power 1 MW
• Beam current (Hall D) 5 µA
• Emittance 10 nm-rad
• Energy spread 0.02

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12
6 GeV CEBAF
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Beam Physics

• BBU HOM damping
• 4 GeV needed HOMs below Q 1x105
• 12 GeV needs 2x106 (easier than 4 GeV
  specification)

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SRF

• What is needed?
• Present 6 GeV / 5 passes 1.2 GeV/pass
  0.6 GeV/linac
• 12 GeV 12 GeV / 5.5 passes 2.2 GeV/pass 1.1
  GeV/linac
• Need to add 0.5 GV/linac

• Adding 0.5 GV/linac
• There are 5 empty zones at the end of each linac
• Were there if we install a 100 MV cryomodule
  in each zone.

Present cryomodules operate at 30 MV on
average. What can be done to achieve 100 MV?
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100 MV cryomodules

• Simplest change would be to add more cells.
• Present 8.5m-long cryomodules have 4.0m of active
  length.
• 7-cell cavities would use 5.6m - OK
• Gives 40 more voltage with the same gradient.

• 40 helps but is not enough -- Need more
  gradient

• How much gradient is needed?
• 100 MV / 5.6 m 17.5 MV/m
• Add 10 for cavities that might be off-line

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100 MV cryomodules Q0

• Will use one 5 kW cryo plant per linac (details
  to come)
• Each plant must support
• Present needs of each linac
• 5 new cryomodules (static and dynamic loads)
• 250 W available at 2.05K for each new cryomodule

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Cavity Performance (01)
Ran out of RF power
KEK/JLab/DESY collaboration
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Cryomodule prototyping
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Cryogenics

• Existing plant is at full capacity with 6 GeV
  configuration.
• New load means we must build a new plant.
• We have the major components for a second 5 kW
  plant.
• Spare 2k cold-box
• MFTF-B 4K plant
• Need to
• Add compressors and oil skids
• Add 80K cold-box
• Put it all together in a building
• Make it all work together

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RF Power requirements
RF power requirement is set by Beam loading,
gradient, R/Q, Qloaded , and cavitys frequency
error.

• Gradient (affects beam power and detuning power)
• Cavity performance goal is 19.2 MV/m
• Some cavities will be better, some will be worse.
• Should be able to use the full potential of the
  best ones
• Plan for 19.2 MV/m 10 21.2 MV/m

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RF Power requirements (contd)

• Beam power per cavity 6.8 kW at 21 MV/m

13 kW klystrons
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Operating envelope with a 13 kW klystron

• Presentgoal

Allowance for tuner
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RF control

• Overall performance requirements are the same as
  6 GeV
• Amplitude 1x10-4
• Phase 0.1º

• Technology choice
• Existing systems at JLab are analog (ca. 1990)
• Standard technology now is digital
  (flexibility)
• May do an analog/digital hybrid (need to review
  bandwidth)
• Algorithm choice
• Large Lorentz forces
• Narrow bandwidth
• Detuning curve is VERY different.

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Lorentz Detuning Effects
Tuner must run ? slow
Is there an alternative?
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RF control (contd)

• Self-excited-loop (SEL) solves the problem.
• SEL drives the cavity at its resonant frequency
  if the external frequency reference is
  disconnected.
• Permits quick recovery if a cavity trips off.
• SELs are already in use for SRF applications,
  e.g. ATLAS.

• International workshop on rf control was held at
  JLab (April, 2001)
• Examined the needs of many machines
• Endorsed our plan to use SELs.
• Also recommended SELs for RIA and ERLs.

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RF control (contd)

• Plans
• Conceptual design for rf control module in FY02
• Prototype and debug in FY03
• Pilot run (for testing on full cryomodule) in
  FY04-05

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Beam Transport

• Existing recirculation and transport to halls
• 367 Dipoles
• 730 Quads
• Power supplies
• Arc 10
• Transport to Hall D

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Dipoles

• Need more field
• Simplest solution is to turn up the current

• There is a simple and cheap way to add return
  iron.

Greatly Reduced
C?Hdipole
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Dipole Magnet Power Supplies

• The system will use 32 large supplies of varying
  sizes up to 750kW
• 23 can be re-used from the present inventory
• 9 new ones must be added

• Will use a modular approach

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East spreader layout
2.0m 1.5m 1.0m 0.5m 0.0m

0m 5m 10m 15m
20m 25m
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S/R dipoles

• Problem Saturation worse than in arcs (return
  pole)

• Solution
• Add iron where possible
• Add turns
• Use BIG shunts to deal with lack of tracking
  between arc and S/R.

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Pathlength - Doglegs
Deal with spread using doglegs and orbit shifts
Deal with centroid by shifting MO frequency
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IC Network, Diagnostics, Safety

• No new development required.
• Add stuff for Arc 10 and Hall D line

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Civil - Power, Water, Space

• AC power additional loads
• RF system 2 MVA
• Magnet power supplies 10 MVA
• Second 5 kW cryogenics plant 6 MVA
• ICW/LCW additional loads
• Magnet RF systems 12 MW
• Cryogenics plant 6 MW
• Space
• Building for CHL-2
• Tunnel to Hall D

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Proposed Schedule

CHL
Magnets, RF, Cryomodules
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Cost Profile
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Open questions

• Lots of details
• Finalized optics and magnets
• New klystron
• New rf control module
• CHL-2 control algorithm
• etc, etc, etc

Schedule
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MISSION NEED STATEMENT FOR   12 GeV Upgrade of
Jefferson Lab Accelerator   Office of High Energy
and Nuclear Physics Office of Science   SYSTEM
POTENTIAL Non-Major System           DOE
Planning Guidance Element The mission of the
Nuclear Physics program is to advance our
knowledge of the properties and interactions of
atomic nuclei and nuclear matter in terms of the
fundamental forces and particles of nature. The
Nuclear Science Advisory Committee (NSAC)
provides official advice to DOE and the National
Science Foundation (NSF) on the national program
for basic nuclear science research, identifying
compelling scientific opportunities and
priorities through a Long Range Planning Process
that incorporates input from the entire
community.   The objectives of the DOE Nuclear
Physics program are to understand how the
fundamental building blocks of matter, quarks and
gluons, formed the hot, dense state of nuclear
matter (known as the quark-gluon plasma) that
existed shortly after the Big Bang to understand
how the nucleons are formed from these quarks and
gluons and how they are bound together to form
nuclei to understand how the elements that
compose our earth and the nuclear reactions that
fuel the stars and to perform the DOE role as
national steward of nuclear physics in the United
States. DOE currently provides 90 of the
federal funding for Nuclear Science in the US,
supporting a world-leading scientific program and
world-class facilities that serve researchers at
universities and national laboratories and
contribute to the knowledge, technological
advances and trained scientists that underpin
DOEs energy, environmental quality, national
security, and basic science missions.   The
Continuous Electron Beam Accelerator Facility
(CEBAF) at the Thomas Jefferson National
Accelerator Facility (Jefferson Lab) is the
world-leading facility in the experimental study
of hadronic matter. The 12 GeV upgrade of CEBAF
directly supports Nuclear Physics scientific
thrusts as identified by NSAC. In its 1996 Long
Range Plan NSAC stated that the community looks
forward to future increases in CEBAFs energy,
and to the scientific opportunities that would
bring. In its most recent (2001) Long Range
Plan, NSAC recommends the 12 GeV upgrade as one
of its highest priorities for the Nuclear Physics
program We strongly recommend the upgrade of
CEBAF at Jefferson Laboratory to 12 GeV as soon
as possible. The 12 GeV upgrade of the unique
CEBAF facility is critical for our continued
leadership in the experimental study of hadronic
matter. This upgrade will provide new insights
into the structure of the nucleon, the transition
between the hadronic and quark/gluon description
of matter, and the nature of quark confinement.  
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Addendum The 12 GeV Upgrade in the context of
National Security   The 12 GeV Upgrade at
Jefferson Lab does not contribute immediately to
the national security. It does contribute in the
longer term and in indirect ways by addressing
the national vulnerabilities identified by the
report Road Map for National Security
Imperative for Change issues by the United
States Commission on National Security in the
21st Century (need to check the title). First,
it guarantees the nations world leadership and
uniqueness in a specific line of inquiry, i.e.
the structure of nuclear matter. Furthermore, it
allows the US to have the first look through a
new window into the inner working of nuclei and
to do it without dependence on foreign
governments. These points go to the heart of the
one of the committees concerns Americas
international reputation, and therefore a
significant aspect of its global influence,
depends on its reputation for excellence in
(science and technology). US performance is not
keeping up with its reputation...In a knowledge
based future, only an America that remains at the
cutting edge of science and technology will
sustain it current leadership." The report goes
on to state The internationalization of both
scientific research and its commercial
development is having a significant effect on the
capacity of the U.S. government to harness
science in the service of national security and
to attract qualified scientific and technical
personnel...The harsh fact is that the US need
for the highest quality human capital in science,
mathematics and engineering is not being net.
In light of this, it should be noted that the 12
GeV Upgrade is exactly the type of intellectually
captivating endeavor that attracts bright young
people and motivates them to enter technically
challenging fields. It thus stands to reason
that the 12 GeV Upgrade will serve to expand the
number of US nationals who are graduate students
in high-tech fields and of potential service to
the nation even if they do not remain in basic
research.   In addition to the intellectual and
human capital to be gained from the 12 GeV
Upgrade project, there are areas of technology
that will be advanced by the project. The Rudman
committees report states Our systems of basic
scientific research and education are in serious
crisis, while other countries are redoubling
their efforts. In the next quarter centry, we
will likely see ourselves surpassed, and in
relative decline, unless we make a conscious
national commitment to maintain our edge. This
is already true for superconducting
radio-frequency accelerating structures. These
structures have applications in high-volume
irradiation facilities, in reducing our stockpile
of nuclear waste, in the production of tritium
without the use of reactors, and in new
energy-production systems that use particle beams
to drive otherwise sub-critical nuclear reactors
(and thereby are less of a threat to the public
than the present designs). Ten years ago, the US
held the undisputed world lead in superconducting
radio-frequency accelerating structures. That is
no longer the case. The 12 GeV Upgrade is an
opportunity to regain our international
leadership in this area of technology. In
addition, the experiments that are needed to
answer the nuclear physics questions at 12 GeV
will establish a new state-of-the-art for high
event rate experiments. Such high-rate
experiments lead to extensions in the nations
capabilities for sorting, correlating, and
integrating information. (Note I couldnt get
this stuff on data-rates to flow. Leave it
out, maybe?)