Transcript Results of Optical Diagnostics of the MERIT Experiment H. Park, H.

Results of Optical Diagnostics of the MERIT Experiment
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H. Park, H. Kirk, T. Tsang, K. McDonald
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Brookhaven National Laboratory
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Princeton University
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State University of New York at Stony Brook
June 10, 2008
IDS Plenary Meeting, Fermi National Accelerator Laboratory
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Talk Outline
● Introduction
● Experimental Method
- Development of optical diagnostics
- Optics configuration with respect to beam, magnet, and Hg jet
- Viewports for optical diagnostics
- Image processing for data analysis
● Experimental Results
- Hg jet behavior in magnetic field: Jet height, Surface stabilization, Jet trajectory
- Hg jet interaction with proton beam :
Jet disruption length with beam intensity and energy,
B field effect to jet disruption
- Response of filamentation on jet surface in B field
B field effect to Hg jet break up, Filament velocity with beam intensity
and energy, Time delay of onset of filamentation and Transient response
● Conclusions
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Introduction
● The Mercury Intense Target experiment is a proof-of-principle demonstration of
a free mercury jet target, contained in a 15T solenoid for maximal collection of
secondary pions.
- Liquid type of High-Z material for higher particle production
- Avoid the destruction of target due to the beam induced thermal stress
- Can be recycled
● Issues are Hg jet disruption due to the energy deposition of proton beam
and Hg jet distortion in strong magnetic field.
● The Hg jet behavior in magnetic field and the Hg jet interaction with proton beam
needs to be investigated experimentally.
● The experimental results provide the Hg jet characteristics in magnetic field with
high energy of beam and it will be refered to the simulation code development.
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Mercury Intense Target Experiment : October 22, 2007 ~ November 11, 2007
Total 360 of beam shots performed and Images for 227 beam shots collected.
MERIT beam shot summary website,
http://www.hep.princeton.edu/~mcdonald/mumu/target/hkirk/MERIT_Beam_Program_110607.pdf
Building 272
TT2 Tunnel
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Installation of Optical Diagnostics at CERN Tunnel TT2/TT2A
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Key Components For An Intense Proton Target Experiment :
Proton Beam, 15T Solenoid Magnet, Hg Jet, and Optical Diagnostics
Schematics of configurations
of key components:
• Solenoid 67mrad, Jet 34mrad w.r.t Beam
• Beam enters at viewport 1 and leaves
at viewport 3
• Interaction length is 30cm
• Viewport 1 =30cm, Viewport 2=45cm,
Viewport 3=60, Viewport 4 =90cm apart
from nozzle.
• Solenoid length = 100cm
• Viewport 2 is at center of magnet
45cm from nozzle
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Four Viewports for Optical Diagnostics
Fiducial on Window Exterior
Viewport4
Viewport3
1cm x 0.5cm Fiducials on Front Top and Rear
Bottom Window, 0.75’’ Apart from Fiducial
Center to Center of Window, FOV = 5cm at
Midspan
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Viewport2
Viewport1
Optics Design and Components
Working Principle : Shadowgraph Method
Fiber Patch : Illumination Fiber,
10m, R=4cm Imaging Fiber, SMA
Pixelation From Imaging
Fiber To Camera CCD
50 x
One Module For Illumination And Imaging :
Grin objective lens, Ball lens, Fibers
800 x
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High Speed Cameras
Viewport 2
SMD 64KIM camera
CCD size:
13.4 x 13.4 mm
Pixels:
960x960
Single frame: 240x240 pixels
57,600 picture elements
Frame rate: 16 frames up to 1 µs/frame
Full well capacity: 220,000 eADC: 12-bit
Quantum Efficiency: 18%
Viewport 1 &3
FastVision (1,2)
CCD size:
15.4 x 12.3 mm
Pixels:
1280x1024
Single frame: FPGA programable
1.3 M picture elements
Frame rate: 500/s @ full resolution
500k/s @ 1x1280
Responsivity: ~1000 LSB/lux-sec
ADC: 10-bit
Quantum Efficiency: 10%
Used
0.025 ~ 0.25 ms frame rate
0.15 µs exposure
800nm pulsed laser
Used
0.5 ~ 2 ms frame rate
10~15 µs exposure
800nm CW laser
Used
0.5 ~ 2 ms frame rate
60 ~ 100 µs exposure
800nm CW laser
Viewport 1 &3
CERN Olympus Encore PCI 8000S
CCD size: 1/3 inch
Pixels: 650x500
4 kHz recording rate
25 us electronic shutter
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Magnetic Field Map
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Magnetic field, Tesla
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Longitudinal
Transverse, X10
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Distance from nozzle, cm
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90 100 110 120 130
Stabilization of Jet Surface by Magnetic Field
0.4T
Viewport 2,
V=15m/s
10T
5T
15T
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Image Processing Method For Data Analysis
Viewport 3, 15m/s, 0T
Binary,
1 bit
Number of events
X: 1011 Y: 231
Index: 55
RGB: 0.22, 0.22, 0.22
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100
50
0
Original,
8 bit
0
100
200
450
500
300
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Jet thickness, pixels
500
600
-200
-300
-400
-500
-600
-700
-800
-900
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-1000
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550
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650
700
750
Hg Jet Height vs. Magnetic Field and Distance from Nozzle
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Jet height, mm
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Nozzle
Diameter
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Distance from nozzle, 30cm
Distance from nozzle, 45cm
Distance from nozzle, 60cm
V=15m/s
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Magnetic field, T
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Influence of Magnetic Field and Gravity to Jet Trajectory
Elevation of jet axis from magnet axis, mm
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V=15m/s
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Simulation
B=0T
B=5T
B=10T
B=15T
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Distance from nozzle, cm
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Interaction of Hg Jet With 14 GeV Beam
B  0 Tesla, 8 1012 protons B  5 Tesla, 161012 protons B  10 Tesla, 121012 protons
B  0 Tesla, 4 1012 protons B  5 Tesla, 161012 protons B  10 Tesla, 201012 protons
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Images Showing Typical Beam/Hg Jet Interaction, B=5T, Protons=16TP,
E=14GeV, 2000 FPS, Viewport3
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continuing at next page
Filament Ends at Top Surface Where Beam Leaves and Filament Begins at
Bottom Surface Where Beam Enters
Hg Jet Break Up Center
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continuing at next page
Jet Breakup at Center of Jet Where Maximum Energy Deposition Occurs
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Disruption Length Increases with Beam Intensity
0.35
E=14GeV
0.30
Disruption length, m
0.25
0.20
0.15
0.10
B=5T
B=10T
B=15T
0.05
0.00
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Beam intensity, m
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Threshold beam intensity for disruption increases with magnetic field
0.40
B=0T
B=5T
B=10T
B=15T
0.35
Disruption length, m
0.30
0.25
0.20
0.15
0.10
Less than 25cm at high field
0.05
0.00
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Beam intensity, TP
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Harmonic 16, E=24GeV
Filamentation Velocity Measurement
10TP, 10T
t=0
20TP, 10T
t=0
V = 51 m/s
Filaments
t=0.075 ms
t=0.175 ms
t=0.375 ms
t=0.175 ms
t=0.375 ms
V = 95 m/s
t=0.050 ms
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Time Delay of Onset of Filamentation
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Filament velocity, m/s
E=24GeV, 10TP
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B=0T
B=10T
B=15T
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Time, microsec
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Filamentation Velocity Increases with Beam Intensity
and Suppressed By Magnetic Field
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E=14GeV
Filament velocity, m/s
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B=5T
B=10T
B=15T
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Beam intensity, TP
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Conclusions
1. An optical imaging system was employed to diagnose the Hg jet in a high power target experiment.
2. Experiment ran in the Fall 2007.
3. Hg jet properties are influenced by the magnetic field.
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The fluctuations on the jet surface decrease as the magnetic field increases.
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Hg jet height increases slightly with magnetic field.
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The deflection of the jet by gravity is reduced at higher magnetic field.
4. Disruption of Hg jet by the proton beam begins at the bottom of jet and ends at the top of jet,
which is consistent with the beam trajectory across the jet.
5. Hg jet breakup is influenced by the magnetic field.
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The filamentation velocity increases as the beam intensity increases.
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The magnetic field reduces the filamentation velocity.
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Disruption length is suppressed by the magnetic field.
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Onset of filamentation occurs later at higher magnetic field.
6. Hg jet breakup is influenced by beam energy and intensity.
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Disruption length increases with both beam energy and intensity.
• The intensity threshold for breakup is lower at higher energy.
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