CREXRunPlan

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CREX Main THIS PAGE IS IN THE PROCESS OF BEING EDITED...

CREX Run Plan for Commissioning and Auxiliary Measurements

See also the Daily Run Plan and Previous Daily Run Plans and Auxiliary Measurements

PREX I - 2010 Run Plan PREX II - 2019 Run Plan

The experiment is approved for 45 PAC days including ? production days. There are 87 days on our calendar.

Below is a list of tasks in the approximate time order, with person(s) responsible, approximate amount of time required, and comments about the conditions or needs. The time will, in most cases, be broken up into manageable chunks if needed, but given the extensive preparations and experience from the PREX run, we hope to expedite most of these tasks. Differences could be when dealing with the target and higher beam currents, for example. After commissioning, we go into a regular production mode; we will provide an updated document webpage for shift worker instructions.

Total time: ?   Based on this list, each day we will come up with an adjustment to the Daily Run Plan. Some flexibility will be needed to accommodate problems and changes in plans.

Several of the early tasks, including some beam restoration and low current commissioning, can be accomplished starting Nov 25. During this time period, we expect to do Moller polarimetry measurements/commissioning with 1 pass and 5 pass beam.

Beam Restoration

  1. Basic beam setup 1 shift: Yves Roblin
    • establish tune beam and low current CW beam in the hall.
    1. Establish beam to dump, through Compton chicane
    2. Design match to hall expected as part of original configuration, if additional beam time is required will be necessary to coordinate with optics/production runplan
    3. ion chamber calibration (should be ready for this if not already done). We should have targets ready; neeed targets in (MASK ION CHAMBERS); Dustin will coordinate
  2. Source and Parity Quality Beam 0 shift (complete before 11/25): Caryn Palatchi, Amali Premathilake, Kent Paschke
    1. Source laser optics configuration and initial setpoints done
    2. Wein left/ Wein Right injector optics configuration not done yet
    3. Characterize injector optics configuration done

Low Current Commissioning

  • Basic beamline commissioning (may be 3 shifts total)
    • Establish low-current beam with spectrometer magnets on. Establish centering on collimator. BPM offset calibration. Commission target ladders.
    • Preparations:
      • Stripchart on ion chambers, with bpm4e and bpm4a positions
      • stripchart on collimator and beamline temps with bpm 4a and 4e positions
      • stripchart on compton rates (with beam current) no more 2x what is present in HACOMPTONLOG
  1. Verify Beamline setup 1 shift Yves Roblin, Bob
    • Tune mode. No target. Raster off. Ion chambers masked. ATLis 19326
    1. beam transport through Compton chicane up to 5uA CW.
      • Rates in finger scintillators no more 2x what is present in HACOMPTONLOG
      • ComptonUS1 ~ 30 Hz, ComptonDSbg1 ~ 870 Hz, ComptonDCbg2 ~ 1010 Hz
    2. spot size at target (harps) (nominal spec is 150 um x 150 um. Minimum is 80 um x 80 um)
      • Use 5uA CW, but keep eye on compton rate, ion chambers, temps.)
    3. Tune beam. Turn on septum and verify still on dump. Clean transport to dump for PREX set points
    4. 1 arm running (Q1 on) test to verify no beam motion.
    5. Turn on both Q1 spectrometers.
  2. Hall bullseye scan 0.5 shift Ye Tian, Bob (should be redone to check nothing changed during down)
    • harp scans at each of 5 points around nominal center, (0,0), (2,2), (2,-2), (-2,-2), (-2,2).
    1. Set prescale for high rate of clock triggers
    2. Watch beam on viewer, ion chamber and temperature stripcharts.
    3. use 2-5uA CW to find each corner position. 4A, 4E harp scan for one of the corner positions and verify EPICS readback of BPMs, check spectrometer BPM calibrations.
      1. If PREX expert is available, parasitically collect data for low current beam monitoring (cavities). If during day have RC inform J Musson before taking this data.
  3. Collimator checkout 0.5 shift Yves, (Ciprian G, Kent P ?), Dustin
    • Verify that we are cleanly going through the collimator and cross check power deposition calculations
    1. Target ion chamber setpoints can be set high to allow this test.
    2. setup ion chamber strip chart
    3. Establish 2-5uA tune mode, with empty target. Use 2x2 raster.
    4. move beam in 2mm steps as much as +/- 1 cm in both horizontal and vertical. Watch for rise the ion chamber signal. Record positions where edges of the collimator bore are found.
    5. set beam to center on colllimator based on those edges.
  4. Septum beam-steering check 0.5 shift Bob, Don, Dustin
    • Verify that energizing the septum does not steer the beam off the dump
    • Septum polarity check here as well?
  5. Warm target position 0.25 shift Dustin (Silviu, present or on call?)
    • Verify target alignment.
    1. insert warm ladder, carbon hole.
    2. Set raster for 8mmx8mm
    3. establish 2uA CW. Run spot++ to find carbon hole. log it.
    4. Adjust raster setting to establish 2x2 raster size. Log it.
    5. if carbon hole not in 2x2 raster view, need to reconsider. (move beam, or use off center?)
  6. Cold target position 0.25 shift Bob (Silviu, present or on call?)
    • Verify target alignment.
    • target and dump ion chamber set points will need to be raised to perform this commissioning
    1. insert cold ladder, carbon hole.
    2. Set raster nominal 8x8 (or what could be used.)
    3. establish 5uA CW. Run spot++ to find carbon hole. Log it.
    4. Set raster to 2x2 set point from before. Use spot++ to verify it.
    5. if carbon hole not in 2x2 raster view, need to reconsider. (move beam, or use off center?)
    6. compare to position of carbon hole on warm and cold ladders. Do we need to recheck target frames for targets? Do we need to change encoder positions?
    7. Move to Ca-40 target, location #(?)
    8. establish 5uA CW, 2x2 raster. Run spot++ to verify raster size, not hitting edges. Log it.
  7. Very low current commissioning Very low current not needed because 1 uA is only few kHz in detectors.

Spectrometer Commissioning

Detailed Optics Plan Name and time assignments needs to be worked out by optics crew

  1. Tracking checkout 1 shift: Bob M, Ryan R, Chandan G
    1. Sieve In, raster off. Tune P. 45 deg C target. 1 uA.
    2. Septum 789 A = 2144*1.05*333/950 (or, use correct momentum here)
    3. Check rates with scalars.
    4. Set prescales for S0 triggers.
    5. VDC checkout; look at tracks, VDC spectra
    6. Some short run for GEM: noise, pulse-heights, tracks, etc. After this GEMS out of DAQ to improve efficiency.
  2. Sieve reconstruction verification 0.25 shift:Bob or Dustin, Ryan
    1. Sieve In, raster off. Tune P. 45 deg C target. 1 uA.
    2. Septum 789 A
    3. 500k events
  3. Tune septum to central ray 1 shift: Bob or Dustin, Ryan
    1. Sieve In, raster off. Tune P. 45 deg C target. 1 uA.
    2. Beam centered on axis
    3. Start septum at 789 A
    4. 500k events per run
    5. Adjust Q1 fields by 10% low (one run) and high (one run)
      1. Identify the invariant position in the phitarg-thetaTarg space and adjust septum to move the central ray to expected location
    6. Repeat 10% low (one run) and high (one run) to verify central hole in correct location
    7. Verify for Q2 and Q3 that central hole does not move under field changes (1 run each, 10% low). (optional)
      • Expected: the hole will be invariant under all quad changes. This location is about 2mm toward beam from central hole.
    8. Last step: CYCLE QUADS to get back to precise Tune P optics
  4. Inner Edge Identification 0.5 shift: Bob or Dustin, Ryan
    1. Sieve In, raster off. Tune P. 45 deg C target. 1 uA.
    2. Beam centered on axis
    3. Start septum at central tune
    4. 500 k events per run
    5. Take 9 points over septum current from +10% to -10% (use maximum high current setting, +15% if possible)
      1. The expected inner edge of the acceptance should match simulation
      2. If there is a small-angle obstruction for currents at or above the central tune current, identify the lower septum current where there is no inner obstruction for both arms. Use this as new production septum current.
    6. Last step: Cycle Septum
  5. Quartz spot width minimization (minimum chase) 1 shift: Dustin, Ryan, Devi, Bob?
    1. Sieve IN (If this is last step of optics configuration, take an access to pull sieve OUT)
    2. raster ON (2x2 raster)
    3. Start with central tune
    4. 45 deg C target. 1 uA.
    5. Beam centered on axis
    6. Optics at central tune
    7. 500 k events per run
    8. Move Q1/Q3 in tandem, steps of +/- 1%.
      • Analyze for Left/Right x and y width.
      • Look at septum hole pattern, check no missing holes (if sieve is in)
    9. Check eigenvector quads steps of +/- 1% on Q1?
      • Analyze for Left/Right x and y width.
    10. Expected: width should be minimized
      • Tune that minimizes width at detectors is new central tune.
  6. Quartz detector checkout 1 shift: Dustin, Devi, VDC expert
    1. Sieve OUT
    2. raster ON (2x2 raster)
    3. Start with central tune
    4. thin C target. 0.5uA - 1 uA (want quartz scaler rates below 1MHz but need beam position monitoring)
    5. Beam centered on axis
    6. Optics at (new) central tune
    7. verify small spot at quartz (thin C, low current, sieve out, raster on?)
    8. thin C, low current, raster on, Sieve OUT: positions Plan
    9. PMT spectra: Examine pulse height distributions to get RMS/mean and PEyields
    10. rates: These will come from scalers. We can't do a rate "check" without going to integrate mode. This will be done during Width study
  7. Q1 acceptance scan 0.25 shift:Ye T WANT GOOD QUARTZ ALIGNMENT FOR THIS (and small spot on quartz)
    1. Sieve In, raster off. Tune P. 45 deg C target. 1 uA.
    2. Beam centered on axis
    3. Optics at central tune
    4. 500 k events per run
    5. Take a run for Q1 filed +/-10% over 5 points (cycle, then scan top to bottom)
      • Expected: later analysis should show out of plane acceptance compares to simulation.
      • Central ray at lower angle than central sieve hole.
  8. Optics calibration data 0.5 shift Nilanga, Siyu
    1. Sieve In, raster off. Tune P. 1 uA.
    2. 45deg Tungsten target
    3. Beam centered on axis
    4. Optics at central tune
    5. 500 k events per run
    6. spectrometer momentum scan (details in run plan still)
  9. Water cell pointing 1 shift Nilanga, Siyu
    1. Sieve IN: pointing measurement
    2. Sieve OUT: pointing measurement
    3. (details in run plan still)
  10. Y target reconstruction on warm and cold ladders
    1. Raster off.
    2. 45 deg carbon
    3. 90 deg carbon
  11. Q2 measurement 0.5 shift Chandan, Siyu, Bob
    1. Production target
  12. Quartz detector rate estimate 0.5 shift KK, Dustin, Devi, Tao
    1. controlled access to change UpStream quartz detector (in each arm) to integrating mode
    2. draft plan
  13. Position At detectors : Dustin, Ryan

High current checkout

REMEMBER: Remove the beamdump difusor before going to high current!

  1. Ion Chamber calibration - thick Target 0.25 shift Dustin, Caryn will coordinate with Nick Gauthier
    • Procedure discussed with Eric Forman: thick target calibration procedure (ramp 2-10uA) for ALL ion chambers (including the dump)
    • Must keep rates in compton finger scintillators; no more 2x what is present in [https://logbooks.jlab.org/entry/3687977
    1. Establish beam, 5uA beam, 2x2 raster, on Ca-40 target.
    2. move beam to x=+1mm (relative to collimator center)
    3. target and dump ion chamber setpoints can be set high this configuration
    4. Execute thick target Ion Chamber calibration, From Atlis 19326. This calibration will be used to set ion chamber setpoints.
      1. Dump and Near-target ICs: set for 45 degree targets by projecting ion chamber setpoints for 20uA current or 90 degree targets by projecting to 70uA current.
    • parasitic: first check of SAMs at low current (call Devi? or Dustin? before starting)

detailed plan

  1. Basic setup 0.5 shift Yves R, Ciprian G:
    • No target.
    • 150uA beam current, through Compton (backgrounds on fingers and Compton photon detector).
  2. High current with target 0.5 shift Ciprian G, Dustin M:
    1. Establish 2x2 raster. Insert Calcium target.
    2. Detector and SAM voltages (Dustin M)
  3. Beamline instrumentation calibration 0.5 shift Caryn P,
    1. Current ramp for BPM/BCM calibrations and detector pedestals detailed plan
  4. Initial production condition test 0.25 shift Caryn P, detailed plan
    1. detector and SAM widths
    2. regression sensitivities
    3. beam noise and asymmetry check
    4. collimator water and thermocouple temperatures,
    5. radiation monitors and ion chamber stability
  5. Width studies 0.5 shift KK,
    1. detector and SAM widths, targets, shutters, etc
    2. deinstall shutters at conclusion of test

Beam Monitor calibration

REMEMBER: Remove the beamdump difusor before going to high current!

  1. Establish 150 uA in hall (Expect 1/3 the power in the collimator compared to PREX-II)
  2. Run current scan, local around 100uA, using Unser to calibrate beam charge monitor readout in parity DAQ.
    1. Run the Compton DAQ concurrently, for calibration
    2. Go to FixedGain when at 150 uA on bpms (list of crates???) and repeat local current scan to set bpm pedestals.

Establish Production Conditions

  1. Beam modulation 0.5 shiftVictoria O., Ye T,: (Detectors needed for BeamMod commissioning)
    1. turn on
      1. In integrating mode
      2. check HV of Main Detector
      3. Lumis on
    2. set Amplitudes
      1. start with .100 A set amplitude. Run (at least) 2 supercycles. Check online gui plots for response.
      2. increase amplitudes by .50 A, to see response (if needed).
    3. test orthogonality
      1. after minimum 2 good supercycles (more is better) ready to examine sensitivities
      2. if orthogonality is bad, need additional time to discuss with experts about retuning beam.
    4. turn off
      1. restore conditions for Moller commissioning
  2. Detector checkout 1 shift Dustin M:
    1. quartz detector position: verify no inelastic event acceptance (plan needed)
    2. width study (plan needed)
    3. raster sync (plan needed)
  3. Spin Dance 1 shift: Simona Malace, Sanghwa Park
    1. Moller polarimeter commissioning (establish beam) (plan needed)
    2. Short spin dance (run plan needed, established optimal spin angle for this Wien state) (plan needed)
  4. Hall PQB 1 shift Caryn P,:
    1. Check asymmetries in the hall
    2. Adiabatic dampening / Matching (plan needed)
      1. Use helicity magnets to tune phase trombone
    3. Establish feedback (if Hall C is not on schedule their feedback for later)
  5. Production: 0.5-3 shift? All
  6. AT measurement: 1.5 shift? All (plan needed)
    1. Do we need to verify zero longitudinal using Moller polarimeter?
    2. Carbon
    3. Lead
    4. Calcium
  7. Initial Moller commissioning 1 shift Simona M, Sanghwa P,
    1. minimal set for first absolute measurements
  8. Initial Compton commissioning 1 shift Dave G, Juan Carlos C,
    1. minimal set for measurement conditions
  9. Beam Modulation phase advance (if needed)
    1. preserve spot size while improving phase advance
    2. to be done after some time early running and after compton tune established
  10. FFB commissioning
    1. if FFB is not functioning after compton tune established, beam study is needed to tune this system. NEEDED FOR ENERGY STABILITY

Start Production

Important Activities After First Few Days

  1. Linearity Studies --
  2. Background Studies --
    1. Scans of Septum Magnet and HRS Dipole
    2. Thin Lead Target to check for inelastics at high-resolution
    3. Thin C12 to measure diamond background
  3. Possible scan of Q1 to optimize acceptance and verify that collimator defines acceptance. (old idea, still relevant?)
  4. We will start with the Wein in Spin-Right. Once we switch to Spin-Left we need to do another spin-dance.

Polarimetry Studies

  1. Compton Commissioning --   Gaskell, et.al.
    1. Beam Tune, Background reduction -- Bteam,
    2. Compton Cavity Checkout --
    3. Photon Detector Checkout -- CMU group
  2. Moller Commissioning -- Simona Malace, Don Jones, et.al.
    1. Magnet Alignment -- 1 shift (swing)
    2. Raster size and pulse-mode -- 1 shift (day)
    3. Target commissioning - 3 shifts
    4. Pulse-mode target commissioning - 2 shifts
    5. DAQ checkout -- 1 shift


Important Activities During run

  1. Linearity Studies --
  2. Background Studies --
  3. Repeat Q2 and pointing measurements
  4. Arc Energy Measurement