UITF Meeting - "schedule" commissioning plan through HDIce tests

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UITF “schedule” for Feb, March, April and May

Poelker, February 7, 2020

Try to lock up “every day” at noon…..

HV condition the gun, eliminate field emission to prolong operating lifetime

  • Feb 10 and 11, lockup at noon
  • With krypton, goal is no detectable field emission at 200 kV (400 cps now, i.e., small but would like to be zero)

Buncher commissioning: find zero crossing and crest phases, determine gradient that provides desired bunchlength at the 2-cell capture cavity inside Booster. In addition Commission the Yao time of flight system

  • Heat and activate the bulk GaAs photocathode, no mask (Tuesday/Wednesday next week). Hope to get > 2% QE. We have ~ 30mW power, together this should provide > 300 uA.
  • There are three methods to explore:

200 keV spectrometer (no current limitation):

  • Step 1: buncher at some nominal gradient, find zero crossing, beam center position on viewer does not change, buncher ON/OFF. Record phase for both zero crossings, one will bunch, one will debunch
  • Step 2: Add/subtract 90 degrees to buncher phase, this is one crest phase.
  • Step 3: buncher OFF note dipole setting and beam position on viewer.
  • Step 4: fill in the table, dipole setting to reposition the beam center at desired location versus buncher gradient.
  • Step 5: Now we know Efield vs buncher setpoint, I assume a particle tracking code tells us what the Efield should be to put longitudinal waist at 2-cell

Brock cavity, harmonically resonant cavity (want up to 100uA current):

  • Step 1: buncher at zero crossing, for bunching
  • Step 2: record the o-scope waveform spanning at least 668 ps versus buncher gradient. Buncher power should vary from 0 to ~ 100 Watts (so pick 10 W increments)
  • Step 3: Download the saved scope files and send them to Brock for post processing (to make them look like bunches)
  • Step 4: Plot the results using excel or something like that: bunchlength vs buncher gradient and peak to peak voltage of bunch versus gradient. Looking for gradient that provide shortest bunch, or the biggest peak to peak voltage, the gradient that sets longitudinal waist at brock cavity.
  • Step 5: use ratio of distances (buncher to brock cavity/buncher to two-cell) to determine buncher gradient that puts longitudinal waist at 2-cell

Yao bunchlength monitor, time of flight system (tune mode OK, or CW < 10uA)

  • I don’t really know how this works

Step 6 of commissioning plan: Break Point. Work with RadCon to measure radiation at Faraday Cup 3 at 10uA CW current, work with SSG to calibrate two BLMs

Resonant polarimeter test with Electrodynamic

  • Monday – Wednesday, February 24-26
  • Good beam, 100uA through Brock polarimeter cavity in 200 keV spectrometer line
  • Brock brings receiver and we measure signal versus pockel cell voltage (i.e., we vary the e-beam polarization by varying the laser polarization)
  • Beam from bulk GaAs and SSL (which we need to (re)activate both photocathodes before his arrival)
  • Do this for 100 kV, 150 kV and 200 kV, if it makes sense
  • We need remote control of PC voltage
  • We need helicity information delivered to Brock receiver that lives inside the cave near the dump, there’s a spare fiber at the laser table? We need to convert fiber to electrical information
  • Need 1497 MHz reference to receiver
  • Need Cat5 cable from receiver to the control room, via trench
  • Need the laser to pulse at 1497 MHz

Rogowski coil tests with coil#2

  • After buncher commissioning, after Brock polarimeter tests, time to test Kevin’s low current beam position monitor, aka Rogowski coil
  • Vent the short region between Faraday Cup 3 and the manual valve at dif pump station, install it there
  • Need labview to spit out information via epics, or remote desktop to Kevin’s computer inside the cave
  • Move beam left/right/up/down in tune mode, and record the beam position from the nearest BPM, compare values to what Rogowski coil provides
  • Then reduce the current until Rogowski coil no longer provides a signal. Assign a beam current to this min value using intensity of YAG image calibrated against Faraday Cup at current > few nA

Improve operating lifetime of the photogun

  • Vent prep chamber and install the mask at right location
  • Bias the anode
  • Make a load lock to install new photocathodes

Booster Commissioning, Run 0

  • April 26 – May 9
  • Good orbit at 500 keV, 1 MeV and 10 MeV
  • 2-cell and 7-cell phases and gradients
  • Measure energy spread, optics, emittance, etc.,
  • Determine beam stability via long runs, what to expect for HDIce tests
  • Between now and then, try to throw 200 keV beam as far as it will go, to find anything not working

HDIce run1

  • No target, only aperture inside IBC
  • Obtain DOE Site Office Permission. Need to satisfy Steve Smith, close out three CATS items: training modules, procedures, start up procedure
  • Elevated beamline stuff: Verify functionality of BPMs, faraday cup, viewers, magnets, valves – all the stuff on elevated beamline upstream of HDIce, and chicane
  • Optics of elevated beamline: set the chicane dipoles, and all the quads to provide desired beam size, compare to Elegant model.
  • Go CW to upstream cup and verify Machine Protection
  • HDIce related stuff: Verify halo monitors, viewer functionality, dump current readback, etc.
  • Commission Rogowski coil using nearby bpms, YAG screen and Faraday Cup
  • Pencil beam, measure beam sizes vs IBC magnet settings, compare to GEANT predictions
  • Calibrate the dump YAG screen as realtime current monitor: YAG intensity vs Cup Current, extrapolate to pA current values. Note halo monitor readings
  • Commission the raster
  • Repeat calibration of YAG screen as realtime current monitor with rastered beam
  • Measure beamsize of rastered beam, determine aperture hole sizes

HDIce run2

  • Unpolarized target

HDIce run3