How to Take a Moller Run

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Hall C Moller Step-By-Step Guide: How to take a Moller Run

Abstract
A step-by-step guide for shift personnel to follow in order to take a Møller run. It is assumed that the polarimeter has already been set up and tuned for the present beam energy by an expert.

HOW TO TAKE A Møller RUN
This document describes the steps to be taken by a Hall-C experimenter performing a Møller beam polarization measurement during NPS running. There is a complimentary procedure which the MCC operators will follow, [1]

  • Record Injector Parameters: during some period of "normal" NPS running, record the conditions of the polarized source and the state of the beam to the other halls. This will allow us to verify that we are taking Møller data in a state as close as possible to NPS production data-taking conditions.
  1. Login: ssh cdaq@cdaql2. Standard cdaq password.
  2. cd moller/anal/nps/moller_gfortran
  3. ./GetEpics.pl
  4. Capture this screen or transcribe its contents to the hclog
  • Møller GUIs: Start the Møller GUIs
  1. ssh cdaq@cdaql1
  2. jmenu
  3. Type "moller" in the jmenu search bar and select "Hall C Moller Combo"
  4. You should now see the main Møller control screen. Under the "Related Displays" button, open:
    1. HC Collimator/Target Ladder Controls
    2. Solenoid Power Supply
    3. Solenoid Temperatures
    4. Solenoid Compressor
  5. Open the Moller BPM gui:
    1. ssh cvxwrks@cdaql1
    2. cd MEDM/moller
    3. medm -x BPMs_for_moller 2019.adl
  6. HV: The Moller HV is available on the HMS HV GUI
  • More Møller BPMs: Open up this nifty PAW script
  1. ssh cdaq@cdaql1
  2. cd moller/BPM/
  3. python3 moller_bpm.py
  • Verify the target magnet status: Check that the Møller solenoid is cold and ready.
  • Call MCC: tell them that you are getting ready for a Møller run. They will take a "zero pos" of the Hall C line and call you back when they are ready for you to retract the target.
  • Setting Up: At this point, MCC should start loading in the Møller optics. While they are doing that you can:
  1. Ask MCC to turn off the fast raster.
  2. Do we have to turn off any NPS or HMS HV's???
  3. Check BCM 2 Range: Carefully note the current status of the gain setting for BCM 2 and then change it to gain setting 5. The selector switch is on the left-hand side of a chassis in rack CH03B11 in the electronics room. Make sure to record in the hclog that you have done this carefully noting the original gain setting and the new one.
  4. Check BCM 17 gain. This can be checked via JMenu.
  • Ramp Up the Solenoid: MCC will call when they are ready for this. It will take about 40(?) minutes to ramp the solenoid up to 3.5T. In the past, we have ramped directly to 3.5T. The new procedure is to ramp incrementally. On the solenoid power supply screen:
  1. If the "Persistence Heater Control: is OFF, turn it ON.
  2. Enter 38.54 A in the "Current Target" field to get 2.0 Tesla (0.0519 T/Amp).
  3. Press the "Ramp" button under "Ramp Control".
  4. After reaching 2T, call MCC and tell them. They will send tune beam for a rough steer.
  5. When MCC is done, ramp to 3.5T (67.44 Amps). Let MCC know when finished.
  6. Later, to ramp field down, set the current to 0.0, and, when field is down,

press OFF to turn off heater.

  • Beam Tune: The beam requires beam steering into and after the polarimeter.
  1. The Møller expert should have made a log entry with a screen snapshot of the tuned settings for the system. Locate that log entry for reference.
  2. Verify that the quad currents agree with those from the reference log entry.
  3. Inform MCC when the solenoid field stabilizes. They will then continue with the Møller setup procedure.
  4. MCC will establish beam and center it to within 0.5 mm of zero at 3C20 and 3C21, with the positions on these three BPMs within 0.5 mm of one-another. The beam at 3H02, 3H04, and 3H07A should be within 1 mm of center (a very loose requirement).
  5. MCC should contact you when this is completed.
  6. Verify the final BPM positions:
    (3C20 ±0.5 mm) = (3C21 ±0.5)
    |3C20| 
    &le
    0.5 mm |3C21| <math>\leq</math> 0.5 mm
    |3H02|, |3H04|, |3H07a| all <math>leq></math> 1.0mm.
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