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Energies below 100 keV (and into the X-ray portion of the spectrum) are not recorded, as the NGRL has not been designed to characterize the natural radioactivity below this level.

Apparatus, Reagents, & Materials

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Figure 8, below, shows the location of the main power switch and the two NIM 4001B crate power switches.

Figure 811. Power switch placement 

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• Make sure the core boat is at home position outside of the NGR.
• Start the iSEG High-Voltage Control software using the desktop icon (Fig. 9a 12a and 9b12b) or select Start > All Programs > iSEGHVwithCan > iSEGCANHVControl to open the iSEG Main window. This program controls the high-voltage power supply for the plastic scintillator MPTs through the iSEG power supply.
  

  Figure 9a12a. iSEG Hard ware Setup and Main screen

  

  Figure 9b12b. The controller cards may be the EHS or EHQ model and are labeled accordingly.
  
  
  

• Exit the iSEG program. When the program asks if you wish to ramp the power down on all channels, select Yes (Fig. 1013).

Figure 1013. Program termination query.

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• Click the iSEG High-Voltage Control Icon to open the Main window.
• Click on the EHQ00 and EHQ01 (or EHS00 and EHS01) modules. A window opens for each module (Fig. 11a 14a and 11b14b). Check the following items:
  • Vmeas values: verify the actual channel voltages have ramped to near zero (1–3 V is acceptable)
  • Current indicators (i.e., Imeas values) have decreased.
  • Status of all channels is OFF (i.e., no green color in the menu status bars).
• Close all iSEG windows after checking the channel voltages and current indicators.

Figure 11a14a. iSEG Multi-Channel High-Voltage Modules; Ch00.

Figure 11b14b. iSEG Multi-Channel High-Voltage Modules; Ch01.

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• Turn off the NaI(Tl) detector electronics (right-hand NIM rack next to iSEG crate; Fig. 1215). This will turn off the high-voltage supply to all 8 NaI(Tl) detectors. Do not turn off the left-hand NIM rack (marked with a circled X in Figure 12 below) or the main power (blue circle) at this time.
• Leave all other electronics and fans running to prevent additional condensation from forming.

Figure 1215. Electronics Crate: Shutdown.

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• Take your time. Let the electronics settle. This is not a race.
• Voltages across any given NaI(Tl) detector may be monitored with a volt-meter at the bias box with 8 red touch points and a white single ground point.
• Do not change the voltage at any NaI(Tl) detector at the junction box!!! Remember if you need to switch off the High Voltage you must switch off the whole right-hand NIM crate (right-hand NIM crate button in Fig. 1215), which will turn the high voltage off from all NaI(Tl) detectors simultaneously.
• Follow all steps in the Partial Shutdown procedure first.
• Turn off the power switch to the iSEG voltage control crate (behind iSEG unit).
• Turn off the fast signal processing electronics (Fig. 1316; leftmost NIM rack).
• Shut down the computer.
• Turn off the master power switch above the middle NIM rack (blue circle in Fig. 1316).
• The fans are connected to the uninterruptible power supply (UPS) and must be unplugged to turn off.

Figure 1316. Master Power Switch.

 Startup Procedure

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1. Ensure the fans are plugged in and working.
2. Turn on the master power button above the middle NIM rack (blue circle in Fig. 1315).
3. Turn on the computer.
4. Turn on the NaI(Tl) detector electronics (right-hand NIM rack next to iSEG crate, the right red circle in Fig. 1315), only after ensuring that the fan under it is working.
5. Turn on the fast signal processing electronics (left-hand NIM rack, the left red circle in Fig. 1315).
6. Turn on the iSEG voltage crate power found behind the unit near the power cord.
7. Launch the iSEG control software at the NGR computer (Fig. 14).
   
   
   
   

   Figure 1417. iSEG Hard ware Setup and Main screen. The controller cards may be the EHS or EHQ model and are labeled accordingly.

   
   
8. Make sure the voltages (Vset) for ESQ00/EHS00 and EHQ01/EHS01 are set (Fig. 1518). Modify the Vset fields as follows:
   
   • Channel 0 = 0 (unused and available for spare channel)
   • Channels 1 and 7 = 1100 V (plastic scintillators in the doors)
   • All other channels = 1300 V (shell-shaped plastic scintillators)
   • If one of the channels on the EHS/EHQ modules has failed, Channel 0 may be in use—be sure you understand which scintillators are connected to which channels, because the door and hoop PMTs require different operating voltages! 
     
     
   
   Figure 1518. EHS/EHQ 00 and 01 iSEG Multi-Channel HIgh-Voltage Modules Screens; VRamp and IRamp fields are circled in red.
   
   
   
9. Make sure voltage ramp (VRamp) is 5% or lower and the current ramp (IRamp) is 50% or lower. The iSEG software does not remember these values between sessions!
10. Click on the Module access menu and click Instructions for all channels > On (ctrl+o) to start ramping up the voltage.
11. Wait until ramp-up completes (1–2 minutes if proper values are used).
12. Exit the iSEG program.
13. Answer No to the prompt when asked to ramp voltages back down. If you answered Yes inadvertently, start again at Step 8.

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To open the NGR instrument setup window (Fig. 1119), select Instruments > NGR: Setup from the IMS panel menu (Fig. 10).

1. Ensure the values in the window are set as shown in the detector values given are constants and measured from the front door to each detector.
            Once the offset to the detectors are determined, these values should not change.
2. Click OK to save the changes and write them to the configuration file. Click Cancel to revert to previous values.

 Image Modified 

Figure

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19. NGR Parameters Window

Motion Control Setup:

Motion control should be set during initial setup and further changes should not be necessary. Motion control setup can be accessed by selecting Motion > Setup from the IMS panel menu (Fig. 1210).

Image Modified

Figure

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20. M-Drive Motion Setup

• The M-Drive Motion Setup control panel will open (Error! Reference source not found.Fig. 20).
• The user may select between four setup panels from this window.
• Motor and Track Options
• Fixed Positions
• Limit and Home Switches
• Motion Profiles

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• Make sure to use the values shown for the NGR (Fig. 1321).
• User should be familiar with the M-Drive motor system prior to adjusting these settings.
• The relationship between motor revolutions and linear motion of the track is defined in this window and is critical to both safe and accurate operation.
• Select Axis: In the case of the NGR it is always X.
• Encoder Pulses/rev: Defined by the manufacturer of the M-Drive as 2048.
• Screw Pitch: Set to 0.0627 (the ratio of 2048 steps per revolution and chain displacement (cm) as a function of the drive gears diameter).
• Gear Ratio: There is not a reduction gear so this value is set to 1.
• Direction: Clockwise rotation moves the tray in a positive direction (from home to end of track).
• Click the Open Utilities and Test button to open the Motion Utility window (Fig. 1422) and test the settings. Click Close to exit this window.
• Click Done to save the values or Cancel to return to previous values.
  Image Modified 
  Figure 13- 21. NGR Motor and Track Options Setup Window
  
  

Image Modified

Figure 14- 22. Motion Utilities Window

Fixed Positions menu

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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. 1422) to determine this value by moving from limit switch to limit switch plus the length of the tray used.
• Load and Unload: For the NGR 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. 1523) 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- 23. NGR Fixed Positions Window

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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 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- 23. NGR Limit and Home Switches Window

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The motion profiles window can be used to adjust the speed and acceleration profiles used by the track (Fig. 17) for various types of movements.
Setting the correct values for the motion profile takes a little experimentation to make the track run efficiently and safely. It is not unusual to modify these values as the lithology changes to balance the need for speed without inducing flux jumps.

 Figure 17- 25. Motion Profiles Window

• 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.

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