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BT-4 Triple Axis Spectrometer

BT4 Startup Checklist

Changing over from FANS

  1. Make sure that the small shield is installed

  2. Power down the monitor
  3. Remove the snout (will need the crane/george’s group)
  4. Check collimation
  5. Reatach bt-4 tas x-rail
  6. Attach the bt-4 tas monitor to power
  7. Repower the monitor (note the monitor is at 499.5 Volts, the detector is at 1276V)


  1. Check that the correct monochromator is in:
  1. d1h=25. This is necessary to give the monochromator room inside the drum to move in the z-direction. On the instrument rack immediately above the instrument computer, you will find the “goniometer drive” panel. This panel controls the x,y, and z motions of the monochromator. You will also find a table of values for each motion taped to this panel. Once you have executed step (a):
    1. Turn the “goniometer drive” panel knob to the desired direction to be moved (in this case “Z”)
    2. Place the “Drive” toggle in the direction of motion (+/-)
    3. Use “Slew” switch to drive the monochromator to the desired position
    4. Use the “Bump” switch when approaching the desired position to avoid overshooting, which can damage the monochromator
  2. Change the software value for the monochromator d-spacing using either dm=PG or dm=Cu in icp.
  1. Verify xpeek is started
  2. Check the zero for the detector 2 theta
  3. Use fndlam to get the correct two theta for the monochromator and to find the wavelength
  4. Rock the monochromator at several energies that you plan to use:
  1. fm 1,2,-.1,-2
  2. set 1= <value found>
  3. pz
  4. record Z01 in the log book
  5. repeat for several energies and record E, Z1, a1
  6. exit ICP by typing “ex”
  7. cd /bt4/cfg
  8. vim ZCOEFFS.CFG
  9. change the values for “slope” and “intercept” (the numbers in front of !z1coeff1 and !z1coeff2)
  10. save the file
  11. set z1=-99 (which is flag to use a linear correction for the zero point vs theta)
  12. pz and verify that z1=-99
  1. Align the analyzer
  2. Start prepare and icp in your directory
  3. Start statline
  4. Check which motors are free
Created August 1, 2019, Updated June 2, 2021