DESIGN OF THE BNL SUPER NEUTRINO BEAM FACILITY

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DESIGN OF THE BNL SUPERNEUTRINO BEAM FACILITY
W. T. Weng Brookhaven National Laboratory Neutrin
o Super Beam, Detectors and Proton
Decay BNL/UCLA/APS Workshop March 3-5, 2004, BNL
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OUTLINE

• AGS Operation with protons
• Accelerator Upgrade (1MW)
• Target and Horn System
• RD Plan
• Further Upgrade Paths
• Conclusion

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AGS Intensity History
1 MW AGS
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Total Accelerated Protons at the AGS
Slow extracted beam (Kaon decay) Fast
extracted beam (g-2) Note Lower total
accelerated protons in later years due
to much shorter running time
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Transition Time to Restore HEP
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AGS Upgrade to 1 MW

• 1.2 GeV superconducting linac extension for
  direct injection of 1 ? 1014 protons low beam
  loss at injection high repetition rate
  possible further upgrade to 1.5 GeV and 2 ? 1014
  protons per pulse possible (x 2)
• 2.5 Hz AGS repetition rate triple existing
  main magnet power supply and magnet current
  feeds double rf power and accelerating
  gradient further upgrade to 5 Hz possible (x 2)

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AGS Upgrade
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AGS Proton Driver Parameters

• present AGS 1 MW AGS 4 MW AGS J-PARC
• Total beam power MW 0.14 1.00 4.00 0.75
• Injector Energy GeV 1.5 1.2 1.5 0.4
• Beam energy GeV 24 28 28 50
• Average current mA 6 36 144 15
• Cycle time s 2 0.4 0.2 3.4
• No. of protons per fill 0.7 ? 1014 0.9 ? 1014 1.8
  ? 1014 3.3 ? 1014
• Average circulating current A 4.2 5.0 10 12
• No. of bunches at extraction 6 24 24 8
• No. of protons per bunch 1 ? 1013 0.4 ? 1013 0.8
  ? 1013 4 ? 1013
• No. of protons per 107 sec. 3.5 ? 1020 23 ?
  1020 90 ? 1020 10 ? 1020

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1.2 GeV Superconducting Linac

• Beam energy 0.2 ? 0.4 GeV 0.4 ? 0.8 GeV 0.8 ?
  1.2 GeV
• Rf frequency 805 MHz 1610 MHz 1610 MHz
• Accelerating gradient 10.8 MeV/m 23.5 MeV/m 23.4
  MeV/m
• Length 37.8 m 41.4 m 38.3 m
• Beam power, linac exit 17 kW 34 kW 50 kW

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Layout of the 1.2 GeV SCL
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Beam Loss at H- Injection Energy

• AGS Booster PSR LANL SNS 1 MW AGS
• Beam power, Linac exit, kW 3 80 1000 50
• Kinetic Energy, MeV 200 800 1000 1200
• Number of Protons NP, 1012 15 31 100 100
• Vertical Acceptance A, p mm 89 140 480 55
• b2g3 0.57 4.50 6.75 9.56
• NP / (b2g3 A), 1012 / p mm 0.296 0.049 0.031 0.190
  
• Total Beam Losses, 5 0.3 0.1 3
• Total Loss Power, W 150 240 1000 1440
• Circumference, m 202 90 248 807
• Loss Power per Meter, W/m 0.8 2.7 4.0 1.8

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AGS Injection Simulation

• Injection parameters
• Injection turns 360
• Repetition rate 2.5 Hz
• Pulse length 1.08 ms
• Chopping rate 0.65
• Linac average/peak current 20 / 30 mA
• Momentum spread ? 0.15
• Inj. beam emittance (95 ) 12 p mm
• RF voltage 450 kV
• Bunch length 85 ns
• Longitudinal emittance 1.2 eVs
• Momentum spread ? 0.48
• Circ. beam emittance (95 ) 100 p mm

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Halo in AGS as Function of Linac Emittance
For acceptable operation, the linac emittance has
to be less than 1.5p
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Linac Emittance Improvement
Emittance at source 0.4 pi mm mr (rms,nor)
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Options Layout
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New AGS Main Magnet Power Supply

• presently
• Repetition rate 2.5 Hz 1 Hz
• Peak power 110 MW 50 MW
• Average power 4 MW 4 MW
• Peak current 5 kA 5 kA
• Peak total voltage ? 25 kV ? 10 kV
• Number of power converters / feeds 6 2

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Eddy Current Losses in AGS Magnets
For 2.5 (5.0) Hz In pipe 65 (260) W/m In coil
225 (900) W/m
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AGS RF System Upgrade

• Use present cavities with upgraded power supplies
• Upgrade Present
• Rf voltage/turn 0.8 MV 0.4 MV
• RF voltage/gap 20 KV
  10 KV
• Harmonic number 24 6 (12)
• Rf frequency 9 MHz 3 (4.5) MHz
• Rf peak power 2 MW 0.75 MW
• Rf magnetic field 18 mT 18 mT
• 300 kW tetrodes/cavity 2
  1

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Neutrino Beam Production

• 1 MW He gas-cooled Carbon-carbon target
• New horn design
• Target on down-hill slope forlong baseline
  experiment
• Beam dump well above ground water table to avoid
  activation

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Super Neutrino Beam Geographical Layout
? BNL can provide a 1 MW capable Super
Neutrino Beam for 104M FY03 (TEC) dollars ?
the neutrino beam can aim at any site in the
western U.S. the Homestake Mine is shown
here) ? there will be no environmental issues
if the beam is produced atop the hill
illustrated here and the beam dumped well
above the local water table ? construction of
the Super Neutrino Beam is essentially
de-coupled from AGS and RHIC operations
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Preliminary Cost Estimate of the BNL - SNBF

• A) Accelerator Systems
  B) Neutrino Production Systems

Total Direct Cost 218.5 M
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Preliminary Cost Estimate Continued

• Total Direct Cost 218.5 M
• Add EDI, 15
• Contingency, 30
• BNL Project Overhead, 13
• Total Estimated Cost 369 M

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D. RD Plan

• Beam Dynamics in the AGS
• AGS Magnet Test
• New Power Supply Design
• AGS RF Cavity/Ferrite Test
• SCL Accelerating Cavity
• 1MW Target Design and Testing

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TARGET-HORN RD

• MATERIAL STUDIES FOR PULSED HIGH-INTENSITY
• PROTON BEAMS

Nicholas Simos, Harold Kirk, Hans Ludewig, Peter
Thieberger, W-T Weng BNL Kirk McDonald,
Princeton U K. Yoshimura, KEK J. Shepard, SLAC J.
Hylen, FNAL
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• CHALLENGES FOR THE INTEGRATED TARGET SYSTEMS
• AS WE GET TO 1 MW SYSTEM
• Heat generation and removal from the target
  system, including HORN
• Target thermo-mechanical response and degradation
• Irradiation and corrosion effects on materials,
  horn especially
• Beam window survivability

SOLUTION Look for new materials that are
continuously being developed for other
applications but seem to fit the bill as targets
There is a catch ! These materials have not been
tested for their resilience to radiation exposure
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PHASE I Graphite Carbon-Carbon Targets
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E951 Results ATJ Graphite vs. Carbon-Carbon
CompositeThe results demonstrate the superiority
of CC in responding to Beam SHOCK.The question
is Will it maintain this key feature under
irradiation ???We will find out in the course of
this irradiation phase
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Super-Invar Irradiation Study CTE assessment
Super-Invar
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PHASE-II TARGET MATERIAL STUDY
WHATS NEXT ? PERFORM irradiation and assess
mechanical property changes for a host of
baseline materials. Perform more sophisticated
assessment
Carbon-Carbon composite This low-Z
composite gives the indication that it can
minimize the thermal shock and survive high
intensity pulses. Because of its
premise it is the baseline target material for
the BNL neutrino superbeam initiative.
The way its key properties (such as CTE or
strength) degrade with radiation is unknown.
Titanium Ti-6Al-4V alloy The evaluation of the
fracture toughness changes due to irradiation is
of interest regarding this alloy that combines
good tensile strength and relatively low
CTE         Toyota Gum Metal
This alloy with the ultra-low elastic modulus,
high strength , super-elastic like nature and
near-zero linear expansion
coefficient for the temperature range -200 oC to
250 oC to be assessed for irradiation effects on
these properties.   VASCOMAX
This very high strength alloy that can serve as
high-Z target to be evaluated for effects of
irradiation on CTE, fracture
toughness and ductility loss
AlBeMet A low-Z composite that
combines good properties of Be and Al. Effects of
irradiation on CTE and mechanical
properties need to be assessed TG-43
Graphite Possibly Nickel-plated Aluminum T6061
(Horn material) for visible irradiation/corrosion
effects, loss of electrical conductivity,
delamination, etc.
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WHAT IS OF INTEREST TO US IN POST-IRRADIATION
PHASE

• Resilience in terms of strength/shock absorption
• CTE evaluation
• Stress-strain
• Fatigue
• Fracture Toughness and crack development/propagat
  ion
• Corrosion Resistance
• De-lamination (if a composite such as CC or
  plated HORN conductor) Use of ultrasonic
  technology to assess changes
• Resistivity changes
• All of the above can/will be done in Hot Cell.
• Other tests are also in the planning for scrutiny
  of the successful candidates (laser induced shock
  and property measurements)

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Conclusions

• The feasibility has been demonstrated for a 1MW
  upgrade for the AGS
• It is possible to further upgrade the AGS to
  24MW
• Active RD efforts are in progress to improve on
  the design and reduce cost.
• Such a high power proton driver is essential for
  very long base line neutrino experiment and
  also for the neutrino factory.