SLAC Aerial View

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SLAC Aerial View
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SLAC ESD looking anew at timing

• The short-term (3 year) LCLS needs
• A long-term revamping of Klystron control
• A new look at the prototype NLC ideas
• Provide input to this meeting
• How do we join SLC timing to EPICS timing to run
  the LCLS injector and Argonne-supplied Undulator?

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SLAC Timing System Specifications

• Blue Book
• (1968)
• Resolution 50 nSec
• - Jitter 15 nSec
• - Main Trigger Line
• Waveform
• / - 400 Volts

PEP II (1998) - Resolution 2.1 nSec -
Jitter 20 pSec - NIM Level Waveform 0
to 0.7 V into 50 Ohms
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Trigger Generation, simplified
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Waveforms 119 MHz and NIM Pulse
FIDO Output
PDU Output
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PDU SLC Style
Sixteen channels per PDU One channel shown
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PDU, Backplane, and STB
Counters
Drivers
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Some Triggered Devices

• Kickers
• Single Beam Dumper Logic
• Beam Position Monitors
• PAU pulsed analog read or write

• Toroid Charge Monitors
• Trigger Gate and Synchronizer
• Klystron Controls
• Gated ADC readout

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Software aspects

• PDU is loaded with tables of delays (TMAT)
• These tables are indexed by beam code
• Beam code information is sent separately at 360
  Hz (PNET)
• This information was once 16 bits, now is 128
  bits, plan is for at least 1024 bits.
• 16 STB outputs are delayed as a function of beam
  code

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Software aspects - 2

• PNET broadcast includes base beam code (lt32),
  high-order bits of pulse ID, modes, and beam code
  information as a function of mode.
• Code can intervene to create more complex
  scenarios (beam code gt31)
• PNET includes information for current pulse,
  next, and/or next1
• Since 128 bits is not nearly enough, much
  information is a function of modes (near front of
  buffer)
• This complexity is referred to as Regional Beam
  Codes

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What is included in timing?

• Stable phase reference
• Per-pulse digital information
• Preset timed data acquisition
• Preprogramming of complex scenarios
• Collecting beam-based acquisitions SLAC speak
  BPM Buffered Acquisition
• Data do not pass through any database
• Correlation done on host machine using Pulse ID
• Can all this be digital at 1GHz (or faster)?