SNS Fast Beam Loss Monitors Final Design Review

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SNS Fast Beam Loss Monitors Final Design
Review

• David M. Gassner

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BLM System Design Features

• Ion Chambers
• Wide Dynamic Range (IC 6 Decades) (2 dn, 4 up)
• Gain adjustment (per channel)
• Beam intensities
• Detector shielding

• Response Time
• Ion Chamber
• Micro-second response. Data can be available for
  multi-turn, per cycle, and per second intervals.
• Order of 5-10 turns to generate Permit Link Fail
  (35 KHz BW 10us)
• FBLM, Liquid Cell/ PMT
• Fast (ns), within turn loss data
• Wide dynamic range

• FBLM Test
• LED mounted inside Scintillator/PMT assembly
• Can be pulsed remotely

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BLM Distribution
Total 18 FBLMs
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HEBT Loss Monitors
169 meters BLM Location Quantity Quads 37 Co
llimator 2 Cavities 2 Dump
2 BIG 1 Moveable 8 FBLM Location
Quantity Upstream 1 Bend 1 Dump 1
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Ring Loss Monitors
248 meter circumference BLM Location
Quantity Quad 44 Injection
7 Collimators 7 RF 5 Extraction
5 Moveable 7 FBLM Location
Quantity Injection 2 Straight Sec.
End 4 Bends 4 Extraction 2
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RTBT Loss Monitors
150 meters BLM Location Quantity Quads
27 Collimators 4 Dump
2 Target 3 Moveable 4 FBLM
Location Quantity Extraction 1 Collimators 1
Target area 1  
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Liquid Cell/Photo-Multiplier Loss Monitor

• Detector
• Available commercially from Bicron, Model MAB.
• BC-505 Liquid (1,2,4 Trimethybenzene)
• More Rad hard than plastics, (about 10Xs)
• Highest light output of any liquid (80
  anthracene)
• Excellent light transmission (2.5m, min 1/e
  attenuation)
• High Flash point (48oC, 118oF)
• PMT - Hamamatsu 2060, 10 stage.
• Sensitivity on order of 100uC/R, Relative to
  itself.

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Loss Signals

• Fast Loss Monitor Applications
• Fast instabilities
• Kicker errors
• Momentum errors
• Beam in Gap
• Ring wire scanner data
• Two Modes
• Integrated signal over bunch duration, read out
  via digitizer clocked revolution frequency.
• Losses within bunch. Signals buffered and sent
  through wideband mux to fast digitizer (1 GS/s).

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FBLM - Liquid Cell Photo Multiplier
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Data Acquisition Control

• Buffer Electronics
• Wideband amp, drives two outputs.
• Loss Data
• All channels digitized through standard 60 MS/s
  14 bit ADC.
• Selected channels at 1 GS/s via mux, (Example
  LeCroy 374 Scope)
• Data transferred to high level via Channel
  Access.
• Multiplexer for 1 GS/s
• Keithley
• 7001 High Density Switch system
• 7016A 50 Ohm, Dual 1X4, 2 GHz Mux cards
• LED Test Pulse
• Remote control
• Timing
• HV Bias Control
• EPICs Driver to ISEG VME based Bias Supply

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HV Bias

• ISEG HV Bias Supply
• VME High Voltage Power Supplies in 2 slot width
• 1 channel and 2 channel versions in same
  dimensions
• LCD display for voltage or current
• variable rate of change of output voltage
• switched polarity
• integrated protection and control circuits
• output overload and short circuit protected
• SHV connector on front side
• Full control via VMEbus
• EPICs drivers
• 1.2k/channel
• Model VHQ 202M, 0-2kV, 3mA