Transcript Targetry Program in the US
Recent Results from MERIT
NUFACT09
Illinois Institute of Technology July 22, 2009
Harold G. Kirk Brookhaven National Laboratory
The
MERIT Experiment MER cury I ntense T arget
Experiment ran Oct./Nov. 2007
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Secondary Containment
MERIT Experiment at CERN
Solenoid Jet Chamber Syringe Pump 3 2 1 4 Proton Beam Hg Jet Beam Window
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MARS Simulations of MERIT
Sergei Striganov, FNAL
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Energy depositions in Hg Jet
Total Energy Deposition Peak Energy Deposition Sergei Striganov, FNAL
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Stabilization of Jet by High Magnet Field
0T 5 T 10 T 15 T
Jet velocities: 15 m/s Substantial surface perturbations mitigated by high-magnetic field.
MHD simulations (R. Samulyak):
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Viewport 3: Disruption Analysis
1 cm
• • • •
Shot 16014 14 GeV 12x10 12 protons/pulse B-field 10 T 500μs/frame Disruption Length =16.5cm
View of Jet/Proton interaction aftermath
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Disruption Analysis
14 GeV 24 GeV Disruption lengths reduced with higher magnetic fields Disruption thresholds increased with higher magnetic fields
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Disruption vs Total Energy Deposition 0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0 B=0T, 24GeV B=5T, 24GeV B=10T, 24GeV B=15T, 24GeV B=5T, 14GeV B=7T, 14GeV B=10T, 14GeV B=15T, 14GeV Fit, B=0T Fit, B=5T Fit, B=10T Fit, B=15T Fit, B=20T Fit, B=25T 1 2 3 4 5 6 7 Total energy deposition (10 3 J) 8 9 14 and 24 GeV data fitted together
Clear threshold behavior
Magnetic field suppression observed
Extrpolation to 20T and 25T
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Study with 4 Tp + 4 Tp at 14 GeV, 10 T Single-turn extraction
0 delay, 8 Tp 4-Tp probe extracted on subsequent turn
3.2 μs delay PUMP
: 8 bunches, 4 10 12 protons
PROBE
: 8 bunches, 4 10 12 protons
Threshold of disruption is > 4 Tp at 14 Gev, 10 T.
4-Tp probe extracted after 2nd full turn
5.8 μs Delay Target supports a 14-GeV, 4-Tp beam at 172 kHz rep rate without disruption.
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Viewport 2: Velocity Analysis
15 Tp 14GeV Proton Beam Solenoid Field at 5T Beam 5016, Hg 15m/s, 100 μs/frame, Total 1.6ms
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Ejection Velocity Analysis
Slope
velocity t v = time at which filament is first visible Study velocity of filaments of ejected mercury using the highest speed camera, at viewport 2, at frame periods of 25, 100 or 500
s
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Ejection Velocity Analysis II
Shot 11019: 24-GeV, 10-Tp Beam, 10-T Field, 25µs/frame: Peak Velocity—60m/s Time delay ≥ 40μs (agrees with E-951)
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Peak Velocities
50 40 30 20 10 B=5T B=10T 80 60 40 20 0 180 160 140 120 100 B=0T B=5T B=10T B=15T 0 20 40 60 Peak energy deposition (J/g) 80 20 40 60 80 100 120 140 160 180 200 Peak energy deposition (J/g) Ejection velocities are suppressed by magnetic field
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180 160 140 120 100 80 60 40 20 0 0
Filament Velocities
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 25 50 75 100 125 Peak energy deposition (J/g) 150
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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 10 12 protons
PROBE
: 4 bunches, 4 10 12 protons
Proton Beam Hg Jet Target Diamond Detectors
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The Diamond Detector Reponses
These detectors showed effects of rapid depletion of the charge stored on the detector electrodes, followed by a slow RC recovery of the charge/voltage.
The beam-current transformer data was used to correct for fluctuations in the number of protons per bunch.
Pump followed by 40μs Probe delay
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Pump-Probe Data Analysis Both target-in and target-out data showed smaller signals, relative to the pump bunches, for probe bunches delayed by 40, 350 and 700
s.
We therefore report a corrected probe/pump ratio:
Ratio = Probe target in -Probe target out Pump target in -Pump target out Probe target out Pump target out
Results are consistent with no loss of pion production for bunch delays of 40 and 350
s, and a 5% loss (2.5-
effect) of pion production for bunches delayed by 700
s.
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Summary
MERIT experimental results
Jet surface instabilities reduced by high-magnetic fields
Proton beam induced Hg jet disruption confined to jet/beam overlap region
20 m/s operations allows for 70Hz operations 115kJ pulse containment demonstrated 8 MW operations demonstrated
Hg jet disruption mitigated by magnetic field
Hg ejection velocities reduced by magnetic field
Pion production remains viable upto 350μs after previous beam impact
170kHz operations possible for sub-disruption threshold beam intensities
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Post-MERIT
Follow-up: Engineering study of a mercury loop + 20-T capture magnet in the context of the International Design Study for a Neutrino Factory.
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
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