development of non-intersecting transverse and longitudinal profile monitors
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Development of non-intersecting transverse and longitudinal Profile Monitors P. Forck, A. Bank, W. Barth, C. Dorn, A. Peters, H. Reeg Gesellschaft f ür Schwerionenforschung, Darmstadt HIPPI Meeting 2005, Oxford Non intersecting methods for: - PowerPoint PPT PresentationTRANSCRIPT
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Development of non-intersecting
transverse and longitudinal Profile Monitors
P. Forck, A. Bank, W. Barth, C. Dorn, A. Peters, H. Reeg
Gesellschaft für Schwerionenforschung, Darmstadt
HIPPI Meeting 2005, Oxford Non intersecting methods for:
• Preventing destruction of intersecting material• Parallel observation at different locations• Monitoring of possible time-varying processes
• Goal: Same precision as intersecting methods
Outline:• Transverse profile monitor by Beam Induced Fluorescence BIF
• Bunch Structure Monitor BSM based on residual gas electron spectroscopy
• Transmission control by transformers
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
High Current Injector (RFQ&IH) Alvarez DTLSingle Gap Resonators
The UNILAC Facility at GSI
Achieved current for U-beam (tpulse = 200 μs)
U4+: 16 emA U28+: 5 emA U73+: 2 emA
1.4 MeV/u11.4 MeV/u
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Basics of Beam Induced Fluorescence
Physics of fluorescence for N2 residual gas: p + N2 p + (N2+)*+ e- p + N2
+ + + e- • Excitation of residual gas molecules by beam’s energy loss• Decay of N2
+ levels generate light, blue light 390 nm < < 470 nm, lifetime = 60 ns.
Realizations at Los Alamos, CERN, Orsay/Saclay, Uni-Frankfurt, GSI, COSY ….Fluorescence of 200 keV p in N2 (1961)
Spectrum confirmed at CERN-PS/SPS from 1 to 450 GeV.
LANL (D. Gilpatrick et al.)
p at MeV in 5*10-5 mbar N2
-20
20
60
100
140
180
320 360 400 440 480
Wavelength (nm)
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Image Intensifier used at GSI-LINAC
Technical realization of image intensifier at GSI:
• Photo cathode S20 UV: γ-e- conversion, 15 to 25 % efficiency, 200 nm < λ < 650 nm
• Two step MCP (25 mm diameter): 106 fold amplification
• P 46 phosphor: e- -γ conversion, 300 ns decay, 500 nm < λ < 600 nm
• Minifying taper coupling to CCD chip (1/2’’): 7% transmission• Digital camera (Basler A311f): Firewire interface
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Test Setup at GSI-LINAC
Compact chamber with 150 mm insertion:
Installation behind Alvarez at 11 MeV/u
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Typical Result at GSI-LINAC
Features:
• Single photon counting
• High resolution (here 0.3 mm/pixel),
can easily be matched to application
• Low background (sometime larger
contribution by neutrons and )
Beam parameters at GSI-LINAC:4.7 MeV/u Ar10+ beam
I=2.5 mA equals to 1011 particles
One single macro pulse of 200 s
Vacuum pressure: p=10-5 mbar (N2)
bump restricted ~1 m,
no influence to beam detected
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Application of Beam Induced Fluorescence
Special application
Variation during the macro pulse detectable:
Switching of image intensifier
Exposure window during macro-pulse
Signal treatment
Statistics offers ‘offline’ optimization
statistics integration time resolution
Beam parameter:
Ar10+ at 11 MeV/u with 8 mA
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
In Preparation: Digital Interface for Firewire
Digital camera offers: no loss of data-quality, versatile trigger, variable exposure timeCCD-camera: Basler A311f featuring 649x494 pixels, 12 bit, 50 frames/s, IEEE 1394bIris/MCP-gain variation: Remote controlled iris by local, ethernet based DACReadout: HUB optical fiber real-time controller running RT-LabVIEW (NI)Status: DAQ in preliminary design phase
LabVIEW Software:
DAQ System:
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Novel Device for non-intersecting Bunch Shape Measurement
Bunch-Shape seldom measured !
Scheme for novel device:
• Secondary electrons for residual gas
• Acceleration by electric field
• Target localization by apertures
and electro-static analyzer
(Δy = 0.2 to 2 mm, Δz=0.2 to 1 mm)
• rf-resonator as ‘time-to-space’ converter
same as intersecting method (INR-Moscow)
• Readout Ø70 mm MCP + Phosphor + CCD
• Measurement done within one macro-pulse
(not yet achieved due to back-ground)
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Realization for Bunch Shape Monitor at UNILAC
E-field and the energy-analyzer:Installation for beam based tests:
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
First Results from Bunch Shape Measurement at UNILAC
Features:
Single electron detection
Recorded within few
macro-pulses
Resolution better
50 ps = 20@108MHz
Pressure bump required
• Back-ground should be
suppressed
Beam parameters:
Ni14+ at 11.4 MeV/u
I=1.5 mA, 200 μs macro pulse
Average: 8 macro pulses
Pressure p=2*10-6 mbar
Deflector power P=15 W
Time information carried by the residual gas e- is transferred to spatial differences:
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
First Application from Bunch Shape Measurement
Variation of buncher:
• Bunch shape was determined,
influeneced by buncher
• Pick-up: No measurable influence
• Emittance determination possible
Beam parameters:
Ni14+ at 11.4 MeV/u
I=2 emA, 200 μs macro pulse
Average: 4 macro pulses
Pressure p=10-5 mbar
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Beam Space Charge Contribution
Simulation method:
e- trajectory calc. inside beam pipe
& linear optics for energy analyzer
Simulation parameter:
Ekin= 11.4 MeV/u
Parabolic bunch shape
∓0.5 ns longitudinal root points
∓5 mm transversal root points
Variation of current (as for Ni14+ )
Simulation result: stronger influence as for
standard method,
but still acceptable
The residual gas e- are influenced by beam’s E-field in addition to the monitor E-field Simulation of influence for different currents:
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Dynamic Transmission control at UNILAC
ACCT clamping
Integration window
ACCT signal
40 μs/div
Variation of maximal loss
via software input:
8 different input thresholds
8 different macro-pulse duration
by electric chopper in front of RFQ
Save protection of equipment.FPGA-electronics:ACCT V/f-converter Up/down-counter: 1st ACCT ↑, 2nd ↓
Digital comparator chopper
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Conclusion and Outlook
Beam Induced Fluorescence BIF: First prototype in operation for ‘single photon counting’, usable during UNILAC operation
Data acquisition in design phase (responsible engineer just hired)
More investigation with high current required
possible problems: broadening by space charge field, two-step excitation….
Non-intersecting Bunch Shape Monitor:
Prove-of-principle performed, resolution lower than 50 ps = 20 @ 108 MHz
Improvements for back-ground suppression in preparation beam test necessary
Calculations and measurements of signal deformation due to beam space charge required
Device in experimental condition engineering design for operation required
Dynamic Transmission control: System design finished
Hardware in operation
Improvements of operation control required
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Comparison for different Gases at p Source (Saclay)
Choice of fluorescence gas:
• High fluorescence yield at optical wave-length
• Short lifetime of excited level
• Good vacuum pumping
Results:
Profile is independent of gas
Care:
• Long lifetime (N2+: 60 ns)
broadening by beam space charge
• Light emitted by primary ions
e.g. p + N2 H* + N2+
(only important for Ekin<1 MeV)
• At large N2 density (p>10-3 mbar): Two-step processes e.g. N2 + e- N2* + e- possible
Profiles from different gasses
Example: Ion source 100 keV, 100 mA protonsP. Ausset et al. (Orsay/Saclay)
N2, Ne
Ar, Kr
Xe
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Non-intercepting Profile Measurement based on Energy Loss
Target e--density ~ 1/Ekin (for Ekin> 1GeV nearly constant)Strong dependence on projectile charge
Profile determination from ionization and excitation of residual gas.
M. Plum et al.:
p in N2 at CERN-PS
Standard monitors: SEM-Grid, Wire-Scanner, Scintillation Screen, OTR-Screen… Disadvantage: intercepting, problems for time-varying processes
Non-intercepting profile measurement:
• Large beam power can destroy the material
• Synchrotron: Monitoring during full cycle • LINAC: Monitoring at different locations,
variation during the macro-pulse
Physics: electronic stopping power
Bethe-Bloch formula:
- dE/dx = const · Zt ρt /At · Zp
2 · 1/β2 · [ ln(const ·γ2β2/I) –
β2]
cr
oss
sect
ion
α dE
/dx
pc [GeV]
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Technical Realization Possibilities for BIF
Double MCP: + single photon, 106-fold amp.
- resolution limited (MCP-channels)
Example: GSI-LINAC (300 μm/pixel)
Single MCP: - lower 103-fold amp.
+ higher resolution
Example: CERN-SPS (160 μm/pix), R. Jung
et al.
Photo-cathode: Only for required wavelength interval to avoid dark currents, e.g.
S20UV: 200<λ<650 nm dark rate 500 e-/cm2/s, S25red: 300<λ<900 nm 30000 e-/cm2/s
Phosphor: Fast decay ↔ lower sensitivity e.g. P47: τ = 0.1 μs, P43: τ = 1000 μs IP43 ~ 4 · IP47
Problem: Radiation hardness of CCD camera
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
BIF at Synchrotrons
Example: CERN SPS and PSB,PS (R. Jung, M. Plum et al.)
Photon yield scales like Bethe-Bloch energy loss ΔE
d for p with 100 MeV < E kin < 450 GeV
Comparison to wire scanner at SPS
Gas N 2 Xe
ΔE /photon 3.6 keV 46 keV
lifetime 58 ± 0.3 ns 59 ± 1 nsMethod: fluorescence decay by ~5 ns long bunches
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Realization of Bunch Shape Monitor at UNILAC
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Standard Bunch Shape Determination
Standard intersecting method developed by INR-Moscow (A. Feschenko, P. Ostrumov et al.):
Insertion of a 0. 1 mm wire at 10 kV
Emission of e- within < 0.1 ps
Acceleration toward 1mm slit
Rf-deflector as time-to-space converter
Detection with Slit+Cup or MCP
Resolution better 1o or 10 ps
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
Dynamic Transmission control at UNILAC
40 μs/div
Verification for transmission control:
Artificial beam loss by
quadrupole variation
chopper window decrease
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L. Groening, Sept. 15th, 2003GSI-Palaver, Dec. 10th, 2003, A dedicated proton accelerator for p-physics at the future GSI facilities
Peter Forck (GSI), HIPPI meeting, Oxford Non-intersecting transverse and longitudinal Profile Monitors
High Current Transmission control at UNILAC
FPGA