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• Select Axis: In the case of the NGR it is always X.
• Max Section Length: Maximum length of section that can be placed in the track. This value is set to 160 cm.
• Track Length: Distance in cm between the limit switches. Use the Motion Utility (Fig. 14) to determine this value by moving from limit switch to limit switch plus the length of the tray used.
• Load and Unload: For the SRM set to 0. This will always bring the tray back to the sample load end after a measurement sequence.
• Top-of-Section Switch?: Not used.
• Top-of-Section Switch Offset: Not used.
• Fast Offset: Not used.
• Run Out Switch?: Not used.
• Click the Open Utilities and Test button to open the Motion Utility window (Fig. 15) and test the settings. Click Close to exit this window.
• Click Done to save the settings. Click Cancel to return to previous values.
   
  Figure 15- SRM NGR Fixed Positions Window

Note, these values along with the positions set in the Degauss-Drift Location window and the SQUID offset set in the SRM setup window are necessary to fully define the track geometry. Take a lot of care in setting these values!

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• This panel is used to define the orientation of the track system, limit switches, and the home switch (Fig. 16). The MDrive M-Drive can be used with either a dedicated Home switch or a limit switch as a home switch. In the case of the NGR track we use only a limit switch. There is no home switch installed.
• Select Axis: In the case of the NGR it is always X.
• Select Track and Home Geometry: For the NGR, select CW limit.
• Click the Open Utilities and Test button to the Motion Utility to test the settings.
• Click Done to save the settings. Click Cancel to return to previous values.
   
  Figure 16- SRM NGR Limit and Home Switches Window

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• DAQ Move: This profile controls moves between measurement positions (leader and trailer measurements included) and the move to the drift 2 position. Set this to a reasonable speed with gradual acceleration and watch out for flux jumps. In addition, when you use the speed reduction feature to control flux jumps, this value is the base value for the reduction.
• Limit Seek: This profile is used for the following moves:
• This profile finds the limit switch location. Do not exceed 3 cm/sec.Do not use a large acceleration value, but always use a large deceleration value.
• Home Final: This profile finds the final location of the home switch. Do not exceed 3 cm/sec.Do not use a large acceleration value, but always use a large deceleration value.
• Load/Unload: This profile is used for moving the tray in and out of the NGR.
• Drift 1: This profile is used to move from the drift 1 position to the leader position and to move from the last trailer position to the drift 2 position
• Drift 2: Unused
• User Define: This profile is used for testing only in the Motion Utilities (Error! Reference source not found.) program.
  • Click the Open Utilities and Test button to open the Motion Utility (Error! Reference source not found.) window and test the settings.
  • Click Done to save the settings. Click Cancel to return to previous values.

Detector Settings

Background Measurement

Measure the background periodically, whenever the ship changes latitude by more than 1-2 degrees, and at least twice an expedition. A data file is generated for each NaI(Tl) detector and measurement position, utilizing the titanium boat with an empty core liner to create conditions as close as possible to core measurement. The background measurement is taken for a much longer period of time for a good statistical spectrum. Typical measurement time is 300 seconds; the background is normally done for 21,000 seconds (almost 6 hours per measurement position; 12 hours total).

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