Chopper wheel Rotates at 100 Hz and contains a timing photodiode to signal position on each turn. A slot cut in the disc passes a 130  s laser pulse train every turn. Stanford DG535 (Repetition Rate) This unit sets the macropulse repetition rate by inhibiting the 100 Hz timing signal from the chopper wheel Quantum Composer 8-Channel timing unit This unit is triggered by the Repetition Rate DG535, and takes a clock input from the MHz RF reference. On triggering, it waits for the next RF clock cycle, then cascades trigger signals to the Mechanical Shutter (selecting a specific macropulse), and to the Macropulse Length DG535 to set the macropulse length. Additional trigger signals are provided to the rack room and the TW laser. Mechanical Shutter The mechanical shutter selects specific macropulses from the 100 Hz macropulse train to define the 1, 2, 5, 10 or 20 Hz repetition rate Stanford DG535 (Macropulse Length) This unit provides trigger to the Pockels cell driver to define the macropulse length AΠBAΠB

Quantum Composers Timing Unit Settings Sync.ChannelWidthDelayPolOutputMode Wait PulsesDriving Alternative for ‘other’ chopper sensor location T0T0 'A'140 us20.31 ms Act highTTL/CMOSNormal0Main RF trigger (via roof feed-through channel #1) ‘A’'B'4 ms24.0 ms Act highTTL/CMOSNormal0Mechanical shutter4.5 ms / 4.0 ms T0T0 'C'150 us0 Act highTTL/CMOSNormal0Not used (suspected faulty) T0T0 'D'150 us26.37 ms * Act highTTL/CMOSNormal0Trigger to DG ms / 150  s T0T0 'E'100 us26.41 ms ** Act highTTL/CMOSNormal0Feed to rack room (via #7 on roof feed-thru box) T0T0 'F'100 us7.01 ms Act highTTL/CMOSNormal0EMMA RF System Trigger T0T0 'G'10 us20.00 ms Act highTTL/CMOSNormal0BPM Trigger (via roof feed-through channel #2) T0T0 'H'95 ms1.1 ms Act highTTL/CMOSNormal0Macropulse repetition rate (setting for 10 Hz) Gate: Mode (Chan Menu) – Level V Clock:Source Ext. w/PLL; Rate MHz; Level V; Ref. out - To pulse; Ext. Opt. - Force OFF; T 0 clock rate Trig: Mode – Triggered; Level – 1.00 V; Edge – Rising Edge * = Value changed from ms to ms on May 23 following shutdown work. ** = Value changed from ms to ms (noted on 28/8/12 – not sure when change was actually made) New timing settings established to drive EMMA RF correctly using timing sensor located on the left-hand side of the chopper wheel, set

DG535 Unit Settings: Macro Pulse Length (Pockels Cell) ChannelDelayDriving 'A'A = T Trigger onset delay 'B'B = A Macro Pulse length (example shows 10 ns) 'C'C = A – 'D'D = C Trigger to Pulse picker Pockels cell T0T0 Trigger to PC for PCO camera or streak camera Trig: Ext.; Threshold = V; Slope (+/-) = +; Trigger term = High Z Output: AB; AB & -AB Loads = High Z; AB: TTL Values correct, as of April 21 st, 2015 Channel ‘A’ adjusted slightly to capture beam following shutdown work

DG535 Unit Settings: Burst Generator Settings ChannelDelayDriving 'A'A = T 'B'B = A 'C'C = T 'D'D = C T0T0 Trig: Ext.; Threshold = V; Slope (+/-) = +; Trigger term = High Z Output: AB; AB & -AB Loads = High Z; AB: TTL Values correct, as of March 20 th, 2015