Transcript High-Power Targets H.G. Kirk Applications of High-Intensity Proton Accelerators FNAL October 20, 2009 Harold G. Kirk Brookhaven National Laboratory.

High-Power Targets
H.G. Kirk
Applications of High-Intensity
Proton Accelerators
FNAL
October 20, 2009
Harold G. Kirk
Brookhaven National Laboratory
Subject Matter Covered Here
WG1 High-Power Target Issues
WG2 Target Station Design and Requirements for
Muon Colliders and Neutrino Factories
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
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The Challenge: Convert to Secondaries
Intense Primary Beam
Intense Secondary Beam
Target
Secondary Beams for New Phyisics
Neutrons (e.g. for neutron sources)
π’s (e.g. for Super ν Beams)
μ’s (e.g. for Muon Colliders, Neutrino Factories)
Kaons (e.g. for rare physics processes)
γ’s (e.g. for positron production)
Ion Beams (e.g. RIA, EURISOL, β-Beams)
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
3
High-power Targetry Challenges
High-average power and high-peak power issues
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
Thermal management
 Target melting
 Target vaporization
Radiation
 Radiation protection
 Radioactivity inventory
 Remote handling
Thermal shock
 Beam-induced pressure waves
Material properties
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
4
Choices of Target Material
Solid
 Fixed
 Moving
 Particle Beds
 Liquid
 Hybrid
 Particle Beds in Liquids
 Pneumatically driven Particles

Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
5
High-Power Targetry R&D
Key Target Issues for high-power targets
What are the power limits for solid targets?
 Search for suitable target materials (solid and liquid) for
primary beams > 1MW
 Optimal configurations for solid and liquid targets
 Effects of radiation on material properties
 Target materials
 Target infrastructure
 Material limits due to fatigue
 Design of reliable remote control systems

Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
6
NF/MC Target System
Neutrino Factory Study 2 Target Concept
SC-2
SC-1
SC-3
SC-4
SC-5
Window
Nozzle
Tube
Mercury
Drains
Proton
Beam
Iron
Plug
Resistive
Magnets
Splash
Mitigator
Mercury
Jet
Water-cooled
Tungsten Shield
Mercury
Pool
ORNL/VG
Mar2009
Van Graves, ORNL
AHIPA, FNAL Oct. 19-21, 2009
Harold G. Kirk
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A 4MW Target Hall
Phil Spampanato, ORNL
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
8
High-peak Power Issues
When the energy deposition time frame is on the order off or
less than the energy deposition dimensions divided by the
speed of sound then pressure waves generation can be an
important issue.
Time frame = beam spot size/speed of sound
Illustration
Time frame = 1cm / 5x103 m/s = 2 µs
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
9
CERN ISOLDE Hg Target Tests
A. Fabich, J. Lettry
Proton
beam
5.5 Tp per
Bunch.
Bunch Separation [ns]
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
10
Pressure Wave Amplitude
Stress = Y αT U / CV
Where Y = Material modulus
αT = Coefficient of Thermal Expansion
U = Energy deposition
CV = Material heat capacity
When the pressure wave amplitude exceeds material tensile
strength then target rupture can occur. This limit is material
dependant.
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
11
Example: Graphite vs Carbon Composit
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
12
Strain Gauge Measurements
BNL E951: 24 GeV, 3 x 1012 protons/pulse
BNL E951 Target Experiment
24 GeV 3.0 e12 proton pulse on Carbon-Carbon and ATJ graphite targets
Recorded strain induced by proton pulse
Stress =
Y αT U / CV
ATJ Graphite
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C-C composite
ATJ Graphite
8
6
Microstrain
4
2
0
-2
-4
-6
-8
0
0.0002
0.0004
0.0006
0.0008
0.001
Time (sec)
Carbon-Carbon
Composite
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
13
Carbon-Carbon Composite
Average Proton Fluence
( 1020 protons/cm2)
0.76
{ 0.52 and 0.36
0.13
none
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
14
Super-Invar CTE measurements
BNL BLIP
Peak Proton fluence
1.3 x 1020 protons/cm2
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
15
Recovery of low αT
Carbon-Carbon anneals at ~3000C
Super-Invar anneals at ~6000C
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
16
The International Design Study Baseline
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
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The IDS Neutrino Factory Baseline
Mean beam power
Pulse repetition rate
Proton kinetic energy
Bunch duration at target
4 MW
50 Hz
5-10-15 GeV
1-3 ns rms
Number of bunches per pulse
1-3
Separated bunch extraction delay  17 µs
Pulse duration:
≤ 40 µs
The IDS Proton Driver Baseline Parameters
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
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The Neutrino Factory Bunch Structure
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
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Driver Beam Bunch Requirement
Proton beam bunch
length requirements
due to rf incorporated
in the downstream
phase rotation and
transverse cooling
sections.
Bunch length = 2± 1 ns
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
20
MARS15 Study of the Hg Jet Target Geometry
Previous results: Radius 5mm, θbeam =67mrad
Θcrossing = 33mrad
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
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Optimized Meson Production
X. Ding, UCLA
Beam/Jet Crossing Angle
Previous baseline 33mrad
Radius
Previous baseline 0.5cm
Beam Angle
Previous baseline 67 mrad
Production of soft pions is
most efficient for a Hg
target at
Ep ~ 6-8 GeV,
Comparison of low-energy
result with HARP data
ongoing
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
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Jim Strait – NUFACT09
s(p+-) /Ebeam, integrated over the measured phase space
(different for the two groups).
HARP (p + Pb -> p+- X)
s peaks in range 4~7 GeV
HARP-CDP (p + Ta -> p+- X)
=> no dramatic low E drop-off
Harold G. Kirk
NuFact ‘09
J. Strait - Fermilab
AHIPA, FNAL
Oct. 19-21, 2009
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23
HARP Cross-Sections x NF Capture Acceptance
HARP (p + Pb -> p+- X)
HARP-CDP (p + Ta -> p+- X)
HARP pion production cross-sections, weighted by the acceptance of the frontend channel, and normalized to equal incident beam power, are relatively
independent of beam energy.
Harold G. Kirk
NuFact ‘09
J. Strait - Fermilab
AHIPA, FNAL
Oct. 19-21, 2009
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24
Multiple Proton Beam Entry Points
p0
Proton Beam
Entry points
p12
p4
jet
Entry points
are
asymmetric
due to the
beam tilt in a
strong
magnetic field
p8
Harold G. Kirk
Brookhaven National Laboratory
Proton beam entry points upstream of jet/beam crossing
Trajectory of the Proton Beam
1.0
Vary z from -75cm to -37.5cm in steps of 2.5cm
0.8
p2, z=-75cm
0.6
Y(proton)-Y(jet), cm
0.4
p14, z=-75cm
0.2
0.0
z=-37.5cm
-0.2
-0.4
-0.6
-0.8
-1.0
p11, z=-75cm
Selected proton
beam
transverse
trajectories
relative to the
Hg Jet.
p5, z=-75cm
p8, z=-75cm
-1.2
-1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0
0.2
0.4
0.6
X(proton)-X(jet), cm
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
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Multiple Entry Entries
p11
A 10% swing
in meson
production
efficiency
p4
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
27
Influence of β* of the Proton Beam
β* = 10cm
β* = 300cm
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
28
Meson Production vs β*
Meson
Production
loss ≤ 1% for
β* ≥ 30cm
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
29
The MERIT Experiment at CERN
Solenoid
Secondary
Containment
Jet Chamber
Syringe Pump
Proton
Beam
4
Hg Jet
3
2
1
Beam
Window
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
30
Installed in the CERN TT2a Line
Before Mating
After Mating and Tilting
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
31
Optical Diagnostics
1 cm
Viewport 2
100μs/fras
Velocity Analysis
Viewport 3
500μs/fras
Disruption Analysis
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
32
Stabilization of Jet by High Magnet Field
0T
5T
10 T
15 T
Jet velocities: 15 m/s
Substantial surface perturbations mitigated by high-magnetic field.
MHD simulations (W. Bo, SUNYSB):
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
33
Disruption Analysis
14 GeV
24 GeV
Disruption lengths reduced with higher magnetic fields
Disruption thresholds increased with higher magnetic fields
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
34
Velocity of Splash: Measurements at 24GeV
10TP, 10T
t=0
20TP, 10T
V = 54 m/s
t=0.075 ms
t=0.175 ms
t=0.375 ms
V = 65 m/s
Harold G. Kirk
t=0
t=0.050
ms
t=0.1752009
ms
AHIPA,
FNAL
Oct. 19-21,
t=0.375 ms
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Filament Velocities
Max. Filament velocity (m/s)
180
Ejection
velocities are
suppressed
by magnetic
field
B=5T,24GeV
B=10T,24GeV
B=15T,24GeV
B=5T,14GeV
B=10T,14GeV
Fit,B=0T
Fit,B=5T
Fit,B=10T
Fit,B=15T
Fit,B=20T
Fit,B=25T
160
140
120
100
80
60
40
20
0
0
25
50
75
100
125
150
Peak energy deposition (J/g)
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
36
Pump-Probe Studies
Test pion production by trailing bunches after disruption of the
mercury jet due to earlier bunches
At 14 GeV, the CERN PS can extract several bunches during one turn
(pump), and then the remaining bunches at a later time (probe).
Pion production was monitored for both target-in and target-out events
by a set of diamond diode detectors.
PUMP: 12 bunches, 12
1012 protons
Proton Beam
PROBE: 4 bunches,
41012 protons
Hg Jet Target
Diamond Detectors
AHIPA, FNAL Oct. 19-21, 2009
Harold G. Kirk
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Pump-Probe Data Analysis
Production Efficiency:
Normalized Probe / Normalized Pump
No loss of pion production for bunch delays of 40 and 350 s,
A 5% loss (2.5-s effect) of pion production for bunches delayed by 700 s.
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
38
Study with 4 Tp + 4 Tp at 14 GeV, 10 T
Single-turn extraction
 0 delay, 8 Tp
PUMP: 8 bunches,
4 1012 protons
PROBE: 8 bunches,
41012 protons
4-Tp probe extracted on
subsequent turn
 3.2 μs delay
4-Tp probe extracted
after 2nd full turn
 5.8 μs Delay
Threshold of disruption is > 4 Tp at 14 Gev, 10 T.
Target supports a 14-GeV, 4-Tp beam at 172
kHz rep rate without disruption.
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
39
Key MERIT Results
Jet surface instabilities reduced by high-magnetic fields
 Hg jet disruption mitigated by magnetic field
 20 m/s operations allows for up to 70Hz operations
 115kJ pulse containment demonstrated
8 MW capability demonstrated
 Hg ejection velocities reduced by magnetic field
 Pion production remains stable up to 350μs after previous
beam impact
 170kHz operations possible for sub-disruption threshold
beam intensities

Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
40
The MERIT Bottom Line
The Neutrino Factory/Muon Collider
target concept has been validated for
4MW, 50Hz operations.
BUT
We must now develop a target system
which will support 4MW operations
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
41
MERIT and the IDS Baseline
NERIT
Mean beam power
Pulse repetition rate
Proton kinetic energy
Bunch duration at target
4 MW
50 Hz
5-10-15 GeV
1-3 ns rms
Number of bunches per pulse
1-3
Separated bunch extraction delay  17 µs
Pulse duration:
≤ 40 µs
OK
OK
 6 µs
≤ 350 µs
The IDS Proton Driver Baseline Parameters
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
42
IDS-NF Target Studies
Follow-up: Engineering study of a CW mercury
loop + 20-T capture magnet
 Splash mitigation in the mercury beam dump.
 Possible drain of mercury out upstream end of
magnets.
 Downstream beam window.
 Water-cooled tungsten-carbide shield of
superconducting magnets.
 HTS fabrication of the superconducting magnets.
 Improved nozzle for delivery of Hg jet
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
43
Summary
MERIT has successfully demonstrated the
Neutrino Factory/Muon Collider target concept
Target studies are continuing within IDS-NF
framework
 The infrastructure for a 4MW target system
needs to be designed/engineered

Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
44
Backup Slides
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
45
The MERIT Experiment at CERN
MERcury Intense Target
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
46
Profile of the Experiment
14 and 24 GeV proton beam
 Up to 30 x 1012 protons (TP) per 2.5s spill
 1cm diameter Hg Jet
 Hg Jet/proton beam off solenoid axis
 Hg Jet 33 mrad to solenoid axis
 Proton beam 67 mrad to solenoid axis
 Test 50 Hz operations
 20 m/s Hg Jet

Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
47
The Jet/Beam Dump Interaction
T. Davonne, RAL
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
48
Shielding the Superconducting Coils
MARS
Dose
Rate
calculations
Harold G. Kirk
AHIPA, FNAL Oct. 19-21, 2009
49