This user guide provides an overview of the IMS-SRM version 10.2 software application for operating the 2G Cryogenic Magnetometer. The SRM software is capable of processing section halves and discrete samples.
Bill Mills, Katerina Petronotis
Supervisor Approval (Name, Title, Date):
November 26, 2018
The IMS-SRM software can be launched from the Windows Start menu or from a desktop icon (Figure 1).
Figure 1- SRM Desktop Icon
At launch, the program begins the following initialization process:
After successful initialization, the main IMS-SRM window will appear (Figure 2).
Figure 2- SRM IMS Main Window
A Quick Introduction to the IMS Program Structure
IMS is a modular program. Individual modules are as follows:
The SRM system, specifically, is built with one INST module (SRM), one MOTION module, and one DAQ Engine module.
The IMS Main User Interface (IMS-UI) calls these modules, instructs them to initialize, and provides a user interface to their functionality.
Each module manages a configuration file that opens the IMS program at the same state it was when previously closed and provides utilities for the user to edit or modify the configuration data and calibration routines.
The four buttons on the IMS-UI window provide access to utilities/editors via dropdown menus as shown in Figure 3.
Figure 3- IMS Control Panel Drop Down Menus
Configuration values should be set during initial setup and configuration by the paleomagnetics technician or scientist(s). There should be no need to change these values unless the configuration file is corrupted.
To open the SRM instrument setup window (Figure 4), select Instruments > SRM: Setup from the IMS panel menu (Figure 3).
1) Ensure the values in the window are set as shown in Figure 4.
2) Click OK to save the changes and write them to the configuration file. Click Cancel to revert to previous values.
Figure 4- SRM Parameters Window
1) Ensure the values in the window are set as shown in Figure 5.
Figure 5- Degauss and Drift Position Configuration Window
Defining Section Half and Discrete Tray Setups
At the beginning of an expedition, or any time the tray is replaced, the scientist(s) or technician must define the two active tray definitions. The program will have in memory the values for just one section half tray and one discrete tray at a time. To open either the Section Tray or Discrete Tray editors, select DAQ > Tray Section Editor or DAQ > Tray Discrete Editor from the IMS panel menu (Figure 3).
Making changes to the tray settings will invalidate the background measurement. The user will be given a warning when they try to start a measurement. A new background will be needed before a measurement can be completed.
Figure 6- Section Tray Editor Window
Figure 7- Discrete Tray Editor Window
Figure 8- Warning window when current tray settings and
last background measurement do not match
Prior to measuring section halves or discrete samples in the SRM the user must:
To open the Measurement Editor (Figure 9), select DAQ > Measurement Editor from the IMS panel menu (Figure 3).
This window allows the user to view and adjust the SRM DAQ Parameters. The current settings are shown in the bottom left hand corner of the window.
Measurement Speed: User selects slow or fast speed, which determines the settling time and data filter. Slow speed reduces noise while fast speed completes measurements more quickly. Slow speed is recommended.
FLUX Alarm Threshold: The flux count value above which the SRM program will trigger a Flux Jump Alarm. Flux counts between the positive and negative threshold value will not trigger the alarm.
Figure 9- Measurement Editor Window
The SRM software is designed to check if the current measurement interval matches the current background tray measurement interval. If the intervals differ, the user must complete a new background measurement. The software will not allow the user to begin a measurement if the values differ. If a change is made, the user may see a red indicator next to DAQ Valid, indicating a new background measurement is necessary (Figure 10).
Figure 10- DAQ Invalid Warning in Measurement Editor Window
Click ACCEPT to exit the Measurement Editor Window once the parameters are set. Select Revert to return to the previous values or select Cancel to leave the window without saving any changes.
1) Select Instruments > SRM: Section Background or Instruments > SRM: Discrete Background (depending on the tray type used)(Figure 11) from the IMS panel menu (Figure 3).
Figure 11- Section Tray and Discrete Tray Background Windows
2) Click START to begin the background measurement process.
3) When the process is complete the user will be prompted to ACCEPT and save background data (Figure 12). If the background data looks suspect (high values or peaks), select CANCEL.
If the data are saved, a new background tray file will be written. The most recent tray measured for each type (section or discrete) will be kept in memory.
These background data will be applied to all subsequent measurements of the same type.
Figure 12- Background Confirmation Window
Creating a Measurement Sequence
1) Open the Sequence Editor (Figure 13) by selecting DAQ > Sequence Editor from the IMS panel menu (Figure 3).
Figure 13- Sequence Editor Window
2) Select a sequence action on the left side of the window. In-line and off-line treatments are mutually exclusive. Once a treatment type is selected, the other treatment type will be disabled.
Figure 14- Offline Treatment Window
3) Users may copy an existing sequence from a file by clicking the Copy From File button.
Figure 15- Copy Sequence File Window
4) Click Add to List to place a new step into the sequence action list.
5) Once the list is completed, click Ok Save and name the sequence
The data calculations for the SRM are volume dependent and therefore it is necessary to assign the appropriate shape and volume to the sample prior to measurements. In the sample preset editor window the user can set the sample shape, section half, and the orientation of the sample. The volume used for each shape is displayed, and in some cases, may be edited.
1) To open the Sample Preset Editor (Figure 16), select DAQ > Sample Preset Editor from the IMS panel menu (Figure 3).
2) Select a sample shape from the left hand column.
Section Half-Piston and Discrete J-cube are the most commonly used presets.
3) Note the volume or area values.
4) Select the section half at the bottom of the window. In most cases this should be ARCHIVE for section halves.
Figure 16- Sample Preset Editor Window: Section Half View
5) For Discrete Specimens, Select a Discrete Cube shape and orientation (Figure 17).
The arrow in the diagrams indicates the arrow or hatch mark placed on the split face of the core section during sampling. The arrow points to the top of the core.
6) Select the face orientation and arrow orientation that the cube will be placed in the tray. Orientations are relative to the SRM when the user is looking from the load zone toward the SQUIDS.
Place the cube into the tray so that the cube arrow matches the preset display.
7) Select the section half at the bottom of the window. In most cases this should be WORKING for discrete samples.
Figure 17- Sample Preset Editor: Discrete Sample View
1) Check the white square box on the right side of the screen (Figure 16 and Figure 17).
2) Click on one of the six sample preset buttons and a window will appear (Figure 18).
Figure 18- Edit Preset Window. Name a new preset, update an existing preset, or disable a preset button.
3) Enter a name for the button in the NAME field.
4) Select UPDATE BUTTON to save the preset.
5) The preset name should be visible on the right hand side of the page. Figure 17 has two presets assigned: Archive_SHLF_Piston and Archive_SHLF-Rotary.
To review what has been assigned to a preset button, click the preset button once. The screen image will update to show the current preset.
1) From a single button:
2) For all six buttons:
Figure 19- Clear Presets Confirmation Window
3) Select OK to exit the preset editor.
Click START on the IMS panel (Figure 2) to open the sample information window (Figure 20–Figure 26). This is where the user enters the sample ID for a section or discrete sample and initiates the measurement.
There are four available tabs on the sample information screen. The first 3 tabs allow the user to enter sample identification information using 3 different methods. The fourth tab allows the user to select a measurement sequence.
The user can select a premade measurement sequence in the Measurement Sequence tab (Figure 20). The last used measurement sequence will remain in memory and is displayed at the bottom of the sample information window. If the sequence displayed is correct, the user does not need to utilize the measurement sequence tab.
Figure 20- Sample Information Window: Measurement Sequence Selection
The user can select a premade measurement sequence in the Measurement Sequence tab (Figure 20). The last used measurement sequence will remain in memory and is displayed at the bottom of the sample information window. If the sequence displayed is correct, the user does not need to utilize the measurement sequence tab.
Figure 21- Sample Information Window: Section Half Scanner Sample Entry
1) Select START on the IMS panel (Figure 2) to open the sample information window (Figure 21).
2) Select a measurement sequence in the Measurement Sequence tab (Figure 20). The sequence may already be selected and displayed in the lower portion of the window.
3) Select the appropriate sample type and orientation preset on the left side of the screen.
4) Enter the Sample ID Information
5) Check that the displayed length of the section matches the section length.
6) Click MEASURE.
Figure 22- Sample Information Window: Section Half
Figure 23- Sample Information Window: Section Half Manual Entry
Discrete Sample Entry
1) Click START on the IMS Control Window (Figure 2) to open the sample information window (Figure 21).
2) Select the appropriate discrete sample type and orientation preset on the left side of the screen.
3) Select a measurement sequence in the Measurement Sequence tab (Figure 20).
4) Enter the Sample ID Information:
5) Click MEASURE to begin measuring the discrete samples
Figure 24- Sample Information Window: Discrete Scanner Entry
Figure 25- Sample Information Window: Discrete LIMS Entry
Figure 26- Sample Information Window: Discrete Manual Entry
Figure 27- Entry fields on Discrete Sample Entry. Note the ID in the Tray Information window must not be
blank or no name will be assigned to the measurements during the saving process.
Figure 28- Discrete Sample Entry Error Message: Appears when the user
tries to assign one sample name to multiple tray positions.
Whenever there is a live network connection to the LIMS database, IDs entered with either the Scanner or LIMS tabs will be validated and values such as section length for sections halves or sample offset for discrete samples will be updated with the most current value. If the connection fails when either the LIMS tab is selected or when scanning a barcode, the user will see this error message (Figure 29). If you click Check Connection, the program will attempt to connect with the LIMS database, opening the window shown in Figure 30.
If Disable LIMS is clicked or the reconnection fails, the LIMS tab is disabled, the Network Status indicator turns red, and a button labled Connect to LIMS appears (Figure 31). Clicking this button will attempt a LIMS reconnection.
When the Network Status indicator is red, the program will use the information stored in the barcode. Generally, for sections this information is correct but if the core has been curated and the length changed, the length value may be wrong and there is a possiblity that measurment will not include all of the material. It is always good practice to check the length against the meter stick on the sample handler.
Figure 29- Web Services Connection Error
Figure 30- Checking LIMS-JR Web service Connection Window
Figure 31- Network Status Indicator
Figure 32- Invalid background measurement warning message
Figure 33- Mismatched label and preset warning message
Figure 34-SRM Display during Measurement
Figure 35-Degausser Internal Error Window
There are multiple features available in the IMS-SRM software and hardware for addressing SRM measurement emergencies. These features are:
The SRM Software Abort button is on the left side of the screen during measurements (Figure 34). Clicking this button brings up a window with three options (Figure 36).
ABORT Do Not Move: Leave the core exactly where it was when Abort was clicked and exit the measurement process. This feature is useful if a core is jammed and further action is needed before moving the tray to the load position. Motor power is shut off and the user is given a warning when this option is selected (Figure 37)
Continue: Continue the sequence from the exact point that Abort was clicked.
Figure 36- SRM User Abort Window
Figure 37 Motor Power Turned off Warning
If the user aborts during a degaussing step a dialogue box will appear and the system will automatically begin ramping down (Figure 38). In this status window, the user has multiple options:
Figure 38- Degauss Abort Warning Window
Figure 39- Degausser status window
Figure 40- Hardware Emergency Stop Button
The ship’s chill water is used to cool the Cryomech compressor, which keeps the helium lines under pressure and the SRM at superconducting temperatures. Without chill water the Cryomech compressor will shut down and the SRM will not be operational. See the compressor and the backup chill water system manuals for detailed instructions.
A few special features are available in the IMS-SRM software to help the user facilitate the measurement process on a variety of materials. These features include:
Typically, a user sets a measurement sequence and lets the program complete the sequence to the last step. But if a user decides they wish to monitor the data collection more closely, a feature called Pause and Confirm is available.
This feature can be turned on or off by selecting the button on the bottom right side of the screen (Figure 41). The button turns blue when pause and confirm is activated. If this feature is on, the IMS-SRM program will pause when it reaches the end of a measurement step and display the pause and confirm window (Figure 42).
There are 6 available actions for the user to select in the Pause and Confirm screen.
Select ACCEPT to initiate the IMS-SRM program to perform the actions selected in the Pause and Confirm window.
Figure 41- Pause and Confirm Button
Figure 42- Pause and Confirm Window
The Exclude Intervals feature is available in the Sample Information Window (Figure 21) and applies only to section halves, whole rounds, and U-channels. This feature is especially useful when measuring cores with sandy intervals or hard rock pieces that are surrounded by bins of rumble.
To turn Exclude Intervals ON:
1) Click Exclude Intervals to open the Exclude Intervals window (Figure 43).
2) Enter the top and bottom offset of the interval to exclude from measurement. Multiple intervals may be selected at a time.
3) Select OK once all intervals are set. The program returns to the Sample Information window.
The indicator next to the exclude intervals button on the sample information window should now be green (Figure 44).
The excluded intervals will be automatically cleared once the measurement sequence has completed.
Figure 43- Exclude Intervals Window
Figure 44- Exclude Intervals Indicator
To manually turn off or edit the excluded intervals:
1) Click Exclude Intervals to open the Exclude Intervals window
2) Select Clear All to remove all excluded intervals OR select the specific interval to be cleared and select the Clear Interval button. Click Exclude Intervals to open the Exclude Intervals window
3) Click Cancel to exit out of the window
The green indicator next to the exclude intervals button on the sample information window should now be gray.
Caution! The entire section will still be demagnetized! Only the measurement process is controlled by the Exclude feature.
MagSpy is opened by selecting Instruments > SRM: Display Plots from the IMS Panel menu (Figure 3), or it can be opened by double clicking the desktop icon (Figure 45).
Figure 45- MagSpy Desktop Icon
Move the red vertical bar along the intensity plot to scroll through each measurement point for a section or each discrete sample in a tray.Plots include: an equal area diagram, Zijderveld plot, demagnetization graph, and graphs of inclination, declination, intensity, and XYZ moments for each discrete sample or point measured on a section (Figure 46).
Figure 46- MagSpy Data Visualization Window
Flux Jump Alarm
This feature notifies the user if the remaining negative or positive flux counts during a measurement exceed a user-determined threshold value.
Two options are available for DAQ speed reduction (Figure 48).
The speed reduction control is available in the pause and confirm window (Figure 42) and in the sample information windows (Figure 21–Figure 26).
Caution! If you are receiving a large number of flux jumps, check for cell phones or laptops in the area around the load zone that may not be in airplane mode or may be connecting via the Wi-Fi.
Figure 47- Flux Jump Warning after a measurement
Figure 48- Reduce Speed Drop-down Menu
The LIMS filter on the sample information window (Figure 21) allows the user to reduce the number of samples they must search through when entering discrete specimens. This feature is not available for section halves.
Figure 49- LIMS filter setup window
There are six main utilities currently available within the IMS-SRM software. These can be found under the Instruments menu (Figure 3). The six utilities are:
1) Time Series Utility
2) DAFI Utility
3) Uturn Utility
4) USB 6008 Utility
5) Data Recovery
6) Degauss Utility
The Time Series Utility runs a background measurement over an extended period of time. During this measurement, the tray is not in the SRM. Open the Time Series Utility (Figure 50) selecting Instruments > SRM: Time Series Utility from the IMS Panel menu (Figure 3). The ship’s heading is recorded along with the X, Y, Z moments.
Figure 50- Time Series Utility during Measurement
The DAFI utility collects and displays 3 channels of data from the National Instruments USB-6008 Multifunction I/O device (or any equivalent DAXmx compliant device) against track position. This means that the USB-6008 can be connected to the XYZ analog output of the 2G Applied Physics 520 Fluxgate or the single channel analog output of the LE Model 6010 Gauss/Teslameter (Hall Probe) and used to measure the field in the SQUID measurement region or to measure the field produced by the degauss coils.
This is best done as a two-person experiment so someone can monitor the cables as the instruments are run through the SRM.
The DAFI Utility (Figure 51) is opened by selecting Instruments > SRM: DAFI Utility from the IMS Panel menu (Figure 3).
1) Secure the Fluxgate or Hall probe in the section-half boat and note the position of the measurement sensor.
2) Enter the position of the measurement sensor into the ‘In Tray Offset’ field. Recommended position is 140 cm.
3) Set the measurement interval in the ‘DAQ Interval’ field and the number of measurements to average at each position in the ‘Average’ field.
4) If you are using the Fluxgate magnetometer, set the range of the probe in the ‘Range’ field. Recommended range is 10 mOe.
5) Set the Start and End offset for the measurements. The tray will move to place the sensor at the Start offset before any measurements are taken.
6) Click START and monitor cables as the tray moves into the SRM. The measurement window will open (Figure 2) and the measurements will begin.
7) Data will be saved automatically to C:\AUX_DATA\DAFI when measurements are successfully completed.
Figure 51- DAFI Utility Setup Window
The U-turn utility is used when a core has been put into the SRM with the top of the core nearest the SRM. The background data is applied incorrectly in this situation, and therefore the values need to be recalculated. This utility performs the recalculations and produces data files for upload.
The U-Turn Utility (Figure 52) is opened by selecting Instruments > SRM: U-Turn Utility from the IMS Panel menu (Figure 3).
The files are written directly to C:\Data\IN
Figure 52- U-Turn Utility Window
Figure 53- Close up of U-Turn Mode Selection Drop Down Menu
When a single file is processed the U-Turn utility will display the original file, the corrected file (Figure 54), and a sample comparison window (Figure 55). The user can page between each of these windows using the tabs. Nothing will be displayed if the Process Folder button is used.
Figure 54- U-Turn Utility Corrected File Display
Figure 55- U-Turn Utility Sample Comparison Window
The USB6008 Utility is a free-form utility designed to allow the user to hook up any instrument to the USB6008 (Figure 56). This can be particularly useful in locating the position of the SQUIDS and Degauss Coils when used with the Motion Widget control. During field trapping, the USB6008 can be attached and the signal of each SQUID can be monitored with this utility.
Open the Motion Widget window by selecting Motion > Motion Widget from the IMS front panel (Figure 3).
The USB6008 utility is opened by selecting Instruments > SRM: USB6008 Utility from the IMS front panel (Figure 3).
Figure 56- USB6008 Device
Figure 57- Motion Widget Window
Figure 58- USB6008 Utility Window
Data Recovery Utility
During normal and background data acquisitions, all pertinent data is recorded to a LabVIEW data log file in real-time as a means to recover data in case of a hardware/software crash or file corruption.
NOTE, this data is overwritten each time a new measurement starts (when the first drift measurement is taken). Recovery of previous data must be completed prior to the first drift measurement.
To recover data from the data log file select Instruments > SRM: Data Recovery from the IMS panel menu (Figure 3). Data from the data log is immediately written to both the SRM load (data upload file format) and the standard backup file (csv format). The data recovery window opens to confirm completion of operations (Figure 59).
Figure 59- Data Recovery Utility Window
Figure 60 Degauss Controller Utility. The status window displayed in the right side image appears when Get Status is pressed.
File Formats and File Uploading
Data upload files are text files used by the MUT application to load acquired data into LIMS. Files with the SRM extension contain section (whole round and U-channel) data, and files with the DSC extension contain discrete data. Either file is written to the C:\DATA\IN folder where MUT will process them and then move them to the C:\DATA\ARCHIVE folder. Any file that fails to upload is moved to the C:\DATA\ERROR folder.
SRM data files are written for each sequence step and in addition to the section data, include the leader, trailer, and the two drift measurement data points.
DSC data files are written for each sequence step and each discrete sample. These files include discrete specimen data and the two drift measurement data points (duplicated for each file). There is no leader or trailer data in this context.
Auxiliary files are csv formatted text files written for both section and discrete data types. These are “kitchen sink” files that contain both final and intermediate calculation data, rotational data, flux counts, process values (demag level) etc. One file of this type is referenced in the data upload file between the <FILE> tags and is archived in the ASMAN database.
In a section file, each row is a single measurement starting with the Drift #1, Leader, Section, Trailer, Drift #2. File names are Sample ID, Text ID, Time stamp, and Demag level; therefore there is only one file per section per sequence step.
Section data is saved in the folder: C:\AUX_DATA\SRM\SECTION.
In a discrete file, each row is a single measurement ordered as Drift #1, Sample, Drift #2. File names are Sample ID, Text ID, Time stamp, and Treatment; therefore there is only one file per discrete sample but it contains all of the sequence steps for that sample. Note, because of the format, repeated measurements for discrete samples will end up in the same file.
Discrete data is saved in the folder: C:\AUX_DATA\SRM\DISCRETE.
Background files are text files written in a standard csv format. They contain the acquisition parameters, tray definition, and include both the raw and drift correct values for the SQUID’s XYZ values. Either the section or the discrete file is referenced in the data upload file between the <FILE> tags and is archived in the ASMAN database.
The filename contains the type of tray, time stamp, and treatment.
File is saved in the folder: C:\AUX_DATA\SRM\SECTION-BKGND.
The filename contains the type of tray, time stamp, and treatment.
File is saved in the folder: C:\AUX_DATA\SRM\DISCRETE-BKGND.
The sequence file is a text file written in a standard ini format and contains the data that describes each sequence step (process values). This file is referenced in the data upload file between the <FILE> tags and is archived in the ASMAN database.
File is saved in the folder: C:\IMS\SRM CONFIG\Measurement Sequence\User.
The configuration file is a text file written in a standard ini format. There is only one current configuration file that contains a snapshot of all the pertinent data that was used during acquisition. This file is referenced in the data upload file between the <FILE> tags and is archived in the ASMAN database.
File is saved in the folder: C:\IMS\CONFIG\CURRENT.
The M-Drive Motion Setup control panel will open (Figure 61).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 (Figure 3).
Figure 61- M-Drive Motion Setup
Once these values have been properly set, they should not change. This panel is only for initial setup.
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.User should be familiar with the M-Drive motor system prior to adjusting these settings.
Click Done to save the values or Cancel to return to previous values.
Figure 62- SRM Motor and Track Options Setup Window
Figure 63- Motion Utilities Window
In this window the user may define fixed track locations used by IMS motion control. For the SRM make sure to use these value unless there has been a physical change to the system (Figure 64).
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!
Figure 64- SRM Fixed Positions Window
Limit and Home Switches Window
Once these values have been properly set, they should not change. This panel is only for initial setup.
Figure 65- SRM Limit and Home Switches Window
The motion profiles window can be used to adjust the speed and acceleration profiles used by the track (Figure 66) 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 66- Motion Profiles Window
Data communication and control is USB based and managed via National Instrument’s Measurement & Automation Explorer (NI-MAX). When you open NI-MAX and expand the Device and Interface section it should appear as seen in Figure 67. On the following pages is an edited version of the NI-MAX report. Text in italics are additional comments for context. To have a pain free experience use these parameters and follow the advice.
The technican should fully understand how to use this information and setup the hardware.
Figure 67- NI Max Device and Interface Menu
4/10/2018 3:39:21 AM
This is a four port USB to RS-232 serial device. With this device we connect the serial port cables from the three SQUID meters and the Degauss Controller.
It is extremely important that the alias names shown here be used. This is how the IMS software knows which instrument it is connected to. So, make sure that the alias named “X-SQUID” is actually connected to the SQUID meter and that the meter is connected to the X-axis output of the SRM. The other two axis should be treated in the same manner.
Also, be aware that if you change hardware, NI-MAX will know. You will have to delete any previously set alias names and reassign them to the correct serial ports. You must also reset the serial port communication parameters.
This is a single port USB to RS-485 serial device. With this device we connect to the M-Drive interface board.
It is extremely important that the alias name “X-AXIS” is used. This is the means by which IMS knows which USB is connected to the M-Drive that moves the X-axis (sample handler).
Also, be aware that if you change the USB to 485 cable NI-MAX will know. Each cable has a serial number. You will have to delete any previous alias names and reassign them to the correct serial ports. You must also reset the serial port communication parameters.
This is an optional device and only needs to be connected should these utilities be used.
This device is connected to the Cryomech Compressor to enable monitoring of the system.
The following section includes instructions on how to:
When magnetically strong materials are passed through the SQUID measurement region it is possible to trap flux within the SRM. This is particularly a problem after hard rock expeditions. The best way to recognize trapped flux is by monitoring the SQUID readouts for extra noise and drift. Trapped flux cannot be measured with the Fluxgate magnetometer.
Each SQUID has a unique response length based on the geometry of the system and the SQUID orientation. To measure the response lengths of each SQUID you may use a point source. The point source must be moved through the sensor region of the SRM over a distance longer than the length of the response functions. The measurements must be made 3 times, once for each axis. The point source will need to be adjusted between each measurement so that the axis of the source is aligned along each of the axis of the magnetometer. The point source should be centered in the bore of the SRM. Using the discrete boat, but running the system as a section half can help facilitate this. Recommended point sources for these measurements are the AGICO JR6 standard (Do not demagnetize this standard!), black plastic cube with a metal pin, or the Applied Physics Calibration coil. The recommended method is using a cube with a point source. Using the calibration coil for these measurements is time consuming and labor intensive.
Figure 69- Example graph of normalized moments vs offset.
Figure 70- Prompt window allowing user to select data to use for the integrate area function.
Figure 71- Prompt window allowing user to select the area of the curve to use for the integrate function.
Figure 72- Integrate Area Results window.
8. Compare the results obtained in these response length measurements with the response length values stored in the SRM setup window (Figure 4). Make sure you are confident in the values you calculate before considering changing the values used in the SRM software.
The function of the degauss coils should be checked periodically to ensure the desired fields are being produced. For this procedure, you will need the axial and transverse Hall probes and the model 6010 Gauss meter. Each coil will require a separate measurement. The Z coils is measured using the axial probe. The X and Y axes are measured using the transverse probe.
Figure 73 Hall probe in the Z axis orientation
2. Set the Degausser System Controller to Manual mode. And set the axis selector to Z (Figure 74).
Figure 74 Degausser Control unit. Red box indicates the toggle switch for switching to manual mode.
Green box indicates the dial for setting the alternating field in Gauss. Blue box indicates the axis selector control.
3. Connect probe to Gauss Meter and turn the meter on.
4. Set the units to mT and select AC mode on the Gauss Meter. Make sure the meter is in automatic range mode.
5. Select Motion> Motion Widget from the IMS menu.
6. Move the tray into the SRM so that the Hall probe is positioned within the Z degauss coil region.
a. For the Z axis with the probe near 140 cm in the tray, the peak field should be found near 261 cm from the home switch.
7. Set the maximum field value on the Degausser controller.
a. The controller is operated in Gauss, so a value of 200 on the dial is equal to 20 mT. Do not set a high field. The coils will be on for an extended time during the tests and may heat up.
8. Press the Ramp Up command on the degausser controller.
9. Once the Tracking light turns on adjust the position of the Hall probe using the motion widget until the peak value is found.
a. Using the HOLD (Max) features of the meter may help to identify the actual peak value as the meter is moved through the degauss coil region.
10. Record the peak value.
a. The value displayed on the Guass meter in AC mode is a true RMS value of the waveform with the dc component removed. To correct the read out value to mT multiply by the RMS correction factor of 1.414.
b. Example: Degauss unit set at 20 mT. Read out on Guass meter is 15.81 mT. Actual produced field is 22 mT.
11. Press the Ramp Down button on the degausser controller.
12. Move the tray to the Home position using the motion widget.
13. Remove the axial probe from the tray and place the transverse probe in the tray. Position the probe to read the X coil (Figure 75).
Figure 75 Hall probe in the X axis orientation
14. Set the axis selector on the degausser controller to X.
15. Use the motion widget to move the probe into the X degauss region and repeat steps 8 to 12.
a. If the probe is positioned at 140 cm in the tray, then the peak field should be found near 243 cm from the home switch.
16. Reposition the probe to read the Y coil output (Figure 76).
Figure 76 Hall probe in the Y axis orientation
17. Set the axis selector on the degausser controller to Y.
18. Use the motion widget to move the probe into the Y degauss coil region and repeat steps 8 to 12.
a. If the probe is positioned at 140 cm in the tray, then the peak field should be found near 277 cm from the home switch.
19. When finished with testing, set the degausser controller back to computer mode. The IMS software may need to be restarted after the mode has been changed back.
At the start of each expedition, the field profile within the SRM should be measured using the Fluxgate magnetometer and the DAFI utility in the IMS-SRM software. This data is retained in IODP Share> Pmag Documents: SRM: Field Profiles as .xlsx files. The field within the SQUIDS should be in the 0 to 20 nT range. If the field within the SRM is determined to be high, the field trapping procedure outlined in Appendix B should be followed.
a. These are the track positions between which the measurements will be taken with the DAFI program. The Fluxgate will be moved to the start position before any measurements are taken.
b. Recommended offsets if Fluxgate is positioned at 140 cm in the tray are:
i. Start offset: 150 cm.
ii. End Offset: 400 cm.
7. Select Start and monitor the cable of the fluxgate as the tray moves through the SRM.
8. A .csv file will be written to C: AUX_Data\DAFI.
a. These files contain the X, Y, and Z meter values in mOe as they would be read from the Fluxgate magnetometer displays and the meter values converted to nT.
9. Save the file as an .xslx file in the IODP Share> Pmag Documents: SRM: Field Profiles folder
a. It is recommended that a plot of the field along each axis vs offset be created.
b. Monitor for significant changes in the field or areas of leakage in the shielding.
It may be necessary to conduct multiple measurements using different ranges of the fluxgate, depending on what information is desired. The field around the shield joints will be too high for the 10 mOe range, but the 1000 mOe will not be sensitive enough for the measurement region of the SRM.
Applied Physics provided calibration factors for the SQUIDS upon delivering the SRM. This procedure is done using a speciality calibration coil which is used for each system they produce. Applied Physics also provided a calibration coil to IODP, but it is not identical to the original coil.
The Applied Physics coil calibration constant is:
C= 3.252 emu/A
The calibration factors should not be altered in the SRM software without serious consideration. The IODP coil can be used to check the calibration factors if the user wants to verify the systems function.
The calibration coil uses a small power supply box that reduces issues with RFI while using the coil. The power supply use two 9 volt batteries. The values produced are usually 1-3 percent different than the values supplied by the Applied Physics coil due to manufacturing differences. The calibration coil can be repositioned on the rod to measure the axial and transverse signals (Figure 77). A multimeter is used to read the output voltages from the coil and the calibration factor is calculated based on these values.
Figure 77 Calibration coil orientations. A) Z axis, B) Y axis, and C ) X axis.
D and E illustrate how to reposition the coil on the wand.
Be aware that proper experiment setup is critical to obtaining valid results. If the coil is not centered in the SQUIDs, the SQUID signal and voltages measured will be inaccurate. It is best to do these measurements when the ship is stable.
Applied Physics calibration constants for the SQUIDS:
CX= 8.1036 E -5 emu/Φ0
CY= -8.2590 E -5 emu/Φ0
CZ= 3.8825 E -5 emu/Φ0
Measuring and Determining the SQUID Calibration factors:
*Once measurements are complete, make sure to LOCK the SQUIDs.
Calculating the SQUID Calibration Constants
Using the formulas and Cx,y,z= C x I, calculate the coil calibration factor,
V= Voltage measured
R = 500,000 Φ0=Resistance
C=3.252 emu/A =Coil Calibration Constant
Cx,y,z=Coil calibration factor (emu/Φ0)
Example Calculation of SQUID calibration constant:
If the measured voltage is 12.27 V,
Multiply this value by the coil calibration constant to get the Calibration Constant for the SQUID:
The resultant values should be similar to those provided by Applied Physics.
IODP measured calibration constants for the SQUIDS during Exp 372:
CX= 8.66 E -5 emu/Φ0
CY= -8.19 E -5 emu/Φ0
CZ= 3.56 E -5 emu/Φ0
This guide is intended to assist technical staff with trapping a low magnetic field inside of the SQUID response region. This procedure will need to be done any time the SRM warms to temperatures above superconducting (7 K) or if a large trapped field is suspected within the SQUID response region.
Prior to beginning this process, check the fluxgate zeros in a mu-metal shield. Zero the fluxgate if necessary. Measure the field trapped inside the SRM prior to heating and retrapping a field to obtain a baseline measurement. For further instructions on measuring the trapped field, see the the DAFI utility instructions.
Figure A1: Fluxgate magnetometer probe and control box
Figure A2: SRM nulling coil
Figure A3: Model 202 Control Monitor for SRM
Figure A4: Model 581 DC SQUID System box
a. It is recommended to center the fluxgate coils around 150 cm in the boat.
b. Put the fluxgate control box in range 10 mOe for measurements within the SRM shielding.
Figure A5: Fluxgate Magnetometer probe positioned in the section half boat. Center the probe in the bore.
Position the coil center of the probe to be at 150 cm.
2. Connect the oscilloscope Aux IN to the SYNC on the Z axis SQUID box and connect oscilloscope Channel 1 to the AC Out on the back of the Z axis SQUID box. (Figure A6)
a. The axial field (along the Z axis) is the highest due to the orientation along the opening of the shielding, which makes the Z axis the best signal to monitor.
Figure A6: Back of the Z axis 581 DC SQUID Box. Connect AC Out (Blue box) to Channel 1 on the oscilloscope.
Connect SYNC (Red Box) to AUX IN on the oscilloscope.
3. Connect the nulling cable to the back of the Model 202 Control Monitor and to the ports near the junction between the measurement region and the degauss region (Figures A7 and A8)
Figure A7: Back of the Model 202 Control Monitor. Note the Nulling Coils Connector in the red box.
The rock mag port (green box) is used to connect the control box to the cold head and read the shield and SQUID temperatures. T
his cable is always connected to the control monitor, but must be left disconnected from the cold head when not in use.
Connect the RS232 cable to the cold head when temperature readings are taken.
Figure A8: Nulling cable connection ports near the junction between the SQUID measurement region and the degaussing region of the SRM.
Connect the red plugs to the red terminals, black plugs to black terminals, matching the X, Y, and Z labels. The cables labeled “coil” will not be used.
4. Connect the Model 202 Control Monitor Rock Mag port to the RS232 port on the cold head (Figure A9).
Figure A9: RS232 port on the Cryomech Cold head (yellow box).
Connecting this cable to the cold head and Model 202 Control montior allows a user to monitor temperatures within the SRM.
5. Turn on the power to the Model 202 Control Monitor. The display should include the current temperature of the shield (TSH) and the SQUIDS (TSQ). T2S will be open. No heaters should be on at this time (Figure A10).
Figure A10: Model 202 Control Monitor Display
6. Move the Fluxgate into the SRM using the motion utility or motion widget in the IMS SRM software.
a. If you want to watch the trapped field during warming, move the Fluxgate magnetometer probe to a position 20 cm from the center of the SQUIDS. As the system warms, it will be possible to see the SQUID signal disappear on the oscilloscope.
b. If the fluxgate is centered in the SQUIDs, the SQUID signal will not be visible on the oscilloscope. The oscilloscope will only show noise.
7. Turn on the heaters by pressing the black buttons on the front of the Control Monitor (Figure A11).
a. The SQUID and STRIPLINE heaters will stay on once they are pressed until they are manually shut off.
b. To turn on the SHIELD heater, press and hold the black button until the light illuminates. The heater will shut off periodically.
c. If you are monitoring the signal on the oscilloscope, the signal should become noisy/disappear after the temperatures reach 7 -8 K. Once the signal is gone, move the fluxgate magnetometer to the center of the SQUID response region.
d. To speed up the heating process, you may shut down the SRM Cryomech Compressor during heating. If the compressor is shut down, reduce the chill water flow to the compressor to prevent over cooling the oil in the compressor.
Figure A11: Model 202 Control Monitor with heaters on. The heater temperatures are now visible on the display.
The SQUID and Stripline heaters (yellow box) will stay on until the switch is pressed again. The Shield heater (red box) needs to be held until the light above the switch illuminates.
The shield heater will shut off periodically and light will turn off. Press the switch again to continue heating the system. The nulling coil potentiometers (purple box) are used to null the field.
8. Keep turning on the Shield heater while monitoring the TSH and TSQ temperatures. When TSH and TSQ are approximately 11-12 K, turn off all of the heaters.
9. Center the fluxgate magnetometer in the SQUIDS using the Motion Widget utility. The SQUIDS are 295.7 cm from the home switch.
10. If the compressor is off, turn it on and increase the water flow rate.
11. While monitoring the readouts on the fluxgate, use a small screw driver to turn the nulling coil potentiometer on the control monitor box (Figure A11 and A12). Adjust the fluxgate readouts to as close to zero mOe as possible.
a. The nulling coil potentiometers do not correspond to the fluxgate axis. The X nulling pot adjusts the Y axis, the Y nulling pot adjusts the X axis, and the Z nulling pot adjusts the Z axis.
b. The values are in mOe so a value of 2.14 on the fluxgate in range 10 mOe is equal to 214 nT.
c. The X, Y, and Z readouts correspond to the fluxgate magnetometer axes, not the SRM axes.
d. The Z axis readout is missing its decimal point. The decimal should be in the same position on each readout.
Figure A12: Fluxgate Magnetometer display during field nulling. This display currently reads 0.04, 0.00, and -0.02 mOe
on the X, Y, and Z fluxgate axis respectively. These values are equal to 4, 0, and -2 nT.
12. Continue monitoring the fields and the TSH and TSQ temperatures as the system cools down. Superconducting temperatures are around 7 K.
a. It is possible to continue adjusting the fields until the shield goes superconducting. It will be evident that the shield has gone superconducting when the adjustment of the nulling currents no longer has an effect on the field.
13. Once the system is superconducting, move the fluxgate 20 cm towards home. A clean signal should be visible on the oscilloscope.
You will notice some fluctuation on all axes, but the Z axis may show significant drift after trapping a new field. Allow the system to settle before taking any measurements. Use the fluxgate magnetometer and DAFI utility in the IMS SRM software to measure the trapped field across the SQUID centers once the system has settled.
This document is intended as a brief explanation of the mathematical calculations done in the IMS-SRM program beginning with the initial SQUID meter readings and ending with the inclination, declination, and intensity values.
The values displayed and recorded directly from the SQUID meters are in units of f0. The SQUID meters have two display options, analog or DVM, and counts. The combination of these two outputs results in the total signal, Sf0.
To convert Sf0 to magnetic moment units,Sf0 is multiplied by the system calibration constant in emu per flux quanta (emu/f). The calibration constant is specific to the axis on which the measurement was taken. To convert the magnetic moment from emu to Am2, use the conversion factor of 10-3.
The calibration constants for the IODP SRM are:
This magnetic moment value is written to the .csv file as the Meter value.
To account for the initial offset in the SQUID readings at the time of the first measurement, the first drift value is subtracted from each measurement. This value is then recorded as the raw moment value.
The IODP and SRM instruments coordinates differ. To correct the data from instrument coordinates to the IODP coordinate system the sign of the Z axis is flipped immediately after the raw magnetic moment value is calculated. The correction for working vs. archive half or any related rotations for cubes are then applied to the raw moments. This is accomplished through matrix rotations.
The raw magnetic moment values are then corrected for response length of the individual SQUID axis and for the sample volume. The resulting value is the volume corrected magnetization, Mv.
*Note that the division by 1003 is a conversion from cm3 to m3.
The Inclination, Declination, and Intensity values are calculated from the volume corrected magnetization values. The inclination and declination values are given in degrees while the intensity values are reported in A/m.
Each of these values is reported as the raw values in the data files. IODP also reports inclination, declination, and intensity values corrected for drift, background, and for both background and drift.
Drift Correction Process:
This section describes the steps taken to correct the magnetic data for instrument drift.
First, the rate of drift over the measurement time is calculated using the moments and measurement times for the drift 1 and drift 2 measurements. The drift 1 measurement is taken when the top of the tray it at 326 cm from the home position and drift 2 is taken when the top of the tray is 106 cm from the home position.
Next, the amount of drift between the first drift measurement and the individual sample measurement is calculated. Linear drift is assumed.
Finally, the amount of drift is removed from the raw moment value, resulting in the drift corrected moment, MDC.
Background Correction Process:
This section covers the process for correcting the volume corrected magnetic moment data for the instrument background. The background measurement is an empty tray measurement taken prior to sample measurements. The same background data will be applied until a new measurement is initiated by the user.
The moments measured along the empty sample tray (Momentbkgd) are subtracted from the measured moments along the core at the same position, resulting in the background corrected moment, MBC.
Background and Drift Correction Process:
This section describes the process for correcting the magnetic moment data for both instrument background and drift.
The background moments, Momentbkgd are removed from the previously calculated drift corrected moments, resulting in the background and drift corrected moment, MBDC.
The corrected moments are then input into formulas 5, 6, and 7 to calculate the corrected directions and intensities for each measurement. These values are then output to the data files (.srm and .csv).