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GCR Whole-Round Multisensor Logger (WRMS) User Guide

GCR Whole-Round Multisensor Logger (WRMS) User Guide

Table of Contents

 

 

 

IMS graphic user interface for WRMSL and STMSL.

 

I. Introduction

The Whole-Round Multisensor Logger (WRMSL - aft) and Special Task Multisensor Logger (STMSL - forward) can simultaneously measure several parameters (e.g., density by gamma ray attenuation (GRA), magnetic susceptibility (MS), and P-wave velocity [PWL]) on whole round core sections. These loggers are nondestructive to sediment fabric. The data generated can be used as proxies for other data. The data is used to facilitate core-core, core-log, and core-log-seismic integration and to construct composite sections. Optimal measurements require a completely filled core liner with minimal drilling disturbance.

Logger sensors currently included on these logger systems:

  • Gamma ray attenuation (GRA)

  • Magnetic susceptibility loop (MS)

  • P-Wave velocity logger (PWL)

The WRMSL and STMSL are the only two systems, which allow continuous core section measurements, one after another.
Note: Both tracks function the same way; however, WRMSL measures density, magnetic susceptibility and P wave velocity, whereas STMSL only measures density and magnetic susceptibility.

It is possible to set the WRMSL acting as the STMSL by changing the setup of the desired instrument. The screenshot below shows how to change the track type of the magnetic susceptibility loop used in the WRMSL to make it work as a STMSL.

How to switch from WRMSL to STMSL: Example for the magnetic susceptibility loop

II. Procedures

A. Preparing the Instrument

  1. Double-click the MUT icon on the desktop (Figure 1a) and login using ship credentials. For more information on data uploading see the "Uploading Data to LIMS" section below.

  2. Double-click the IMS icon (Figure 1b). IMS initializes the instrument. Once initialized, the logger is ready to measure the first section.

 

Figure 1. (a) MUT Icon. (b) IMS Icon.

At launch, IMS begins an initialization process:

  • Testing instrument communications

  • Reloading configuration values

  • Homing the pusher arm of the motion control system.

After successful initialization, the IMS Control and Instruments' windows appear (Figure 2).

Figure 2. IMS Control window (left) and Instrument' windows (right).

B. Instrument Calibration

To access an instrument's calibration procedure, click on the Instruments menu and select the instrument's calibration function. Good practice is to calibrate the instrument prior to receiving cores at each new site.

 

GRA: Standard Set Editor

The GRA standard is an aluminum bar inserted into a core liner, which is filled with DI water and sealed. The aluminum bar is machined into discrete steps that provide composite density values for creating a calibration curve of counts vs. density.

Before calibration, use the Standard Editor to enter offset and thickness of each step's center. Under the Instrument menu, select GRA: Edit Standards to view the GRA Standard Edit window (Figure 3).

NOTE: This only has to be done once, in order to add a new standard, as the values are retained in the configuration file. It is important to check the offset values against the standard because the standard can shift within the liner. 

 

Figure 3. GRA Standard Edits window.

 

Define two standard sets in the Standard Editor: Aluminum Steps (density) and Density Check (water).

  • Aluminum Steps : The offset (measured from liner top to center of step) and the thickness of each step are the values shown in the diagram above. Define the offsets in the order they are measured on the track.

  • Density Check: (1) Define an offset past the aluminum standard and (2) Enter water density (1 g/cm3) as the given value. The water measurement is used to validate the density calibration.

 

GRA Calibration Process

  1. In the Instruments menu, select GRA: Calibration.

  2. A window will pop-up asking to place the standard on the track (Figure 4).

Figure 4. First GRA Calibration window.

 

      3. Place the standard on the track with the Aluminum in the standard (Blue side) toward the GRA sensor. The bottom of the standard should be inserted into the slot of the arm plate. First loosen the plate to allow it to move. Click OK.

      4. The pusher moves the standard until it trips the top-of-section sensor, then moves the standard to all of the defined offsets, taking a measurement at each position. After measuring the last step, the pusher moves the standard to the offset for the water measurement.

      5. After the standard is measured, the calibration data displays in the graph along with the calibration line (Figure 5).

     6. Using the new calibration data, a density value for water is calculated and compared to the known value of 1 gm/cm3. The curve fit provides the coefficients used in the density calculations, ln I = B(μd) + C; where μ= Compton attenuation coefficient, d = sample diameter, I0 = gamma ray source intensity, and I = measured intensity of gamma rays passing through the sample. Allowing bulk density to calculated by using, ρ = 1/(μd) × ln (I0/I).

     7. Choose to apply the calibration to all future measurements by clicking Accept Calibration or click Cancel Calibration to restore the previous values.

 

Figure 5. GRA Calibration window.

 

     8. Last accepted calibration could be reviewed under Instruments > GRA: Setup (Figure 6).

 

Figure 6. GRA Setup window.

 

PWL Calibration process

  1. In the Instrument menu, select PWAVE: Calibrate-Utility and the PWAVE Calibration Utility window will open (Figure 7).

  2. Follow the steps on the right side of the PWAVE Calibration Utility window. Note: Liner Delay correction is excluded when using the Aluminum standard.

  3. Place the aluminum standard between the transducers. Close the transducers. Aluminum standard width is 76.25 mm. Select Laser Offset Correction. Confirm that the Distance matches the standard's width.

  4. Enter the Aluminum Standard velocity. 6295.00 m/s. Select Determine System Delay. Verify that the Velocity matches the Aluminum Standard's velocity.

  5. Open transducers. Remove Aluminum Standard.

  6. Position the Water Standard between transducers. Close transducers. Turn on Liner Delay. Enter the water's temperature (Water at room Temperature) under Temperature. Select Auto H2O Velocity Update. Liner Thickness is 2.58 mm. Click Determine Liner Velocity.

  7. Accept Changes.

  8. Open transducers and remove the water standard.

Figure 7. P-Wave Calibration Utility. 

 

        9. Last accepted calibration could be reviewed under Instruments > PWAVE: Setup (Figure 8).

 

Figure 8. Pwave Setup window.

 

Adjusting Measurement Parameters for the Waveform

Use the Stack slider in the PWAVE CalibrationUtility window to adjust the measurement parameters to obtain a better waveform (Figure 7). These parameters may need to be adjusted if the section material has changed.

Stack: Sets the number of waveforms to average to increase the signal-to-noise ratio. Note: Stack should not be any lower than 50.

 

Correction for acoustic velocity through water

In the calibration process, the PWL uses the P-wave speed through water for deriving the velocity through the CAB core liner. The acoustic velocity through distilled water is based on the equation of Marczak (1997);

Vp_water = 1402.385 + 5.038813T - 5.799136E-02T^2 + 3.287156E-04T^3 - 1.398845E-06T^4 + 2.787860E-09T^5

The National Physical Laboratory (NPL) gives a brief summary of this and other equations. Marczak's equation fits a 5th order polynomial through 3 published sound-wave-speed-in-water datasets. There are other equations with many more coefficients and some that also account for variations in pressure (or depth) and salinity. Given that we operate at 1 atm and use distilled water, there is no need for more complex equations. Variations from one equation to another and to fits of the observations tend to have quoted differences and standard errors less than 0.02 m/s.  Even given errors of about 0.2°C in temperature measurements, we should still be good to better than 1 m/s.

References

W. Marczak (1997), Water as a standard in the measurements of speed of sound in liquids. J. Acoust. Soc. Am. 102, 2776-2779.

National Physical Laboratory links with information, references, and online Vp calculators for water:
http://resource.npl.co.uk/acoustics/techguides/soundpurewater/content.html#BILANIUK
http://resource.npl.co.uk/acoustics/techguides/soundpurewater/marczak.html  <- Calculator for Marczak’s equation

 

C. Set Measurement Parameters

The five buttons on the  IMS Control window provide access to utilities/editors via drop-down menus (Figure 9).

 

Figure 9. Five buttons from IMS Control window. Menus within each button.

 

Click on the Instruments menu to select each instrument's Setup Editor (Figure 10, 11, and 12). In general, the values shown in the Setup Editor rarely need to be changed. Regardless, check these values at the beginning of every expedition.

Note: Do not change these values without reading the vendor's documentation.

GRA: Setup

 

General Information (Figure 10)

Instrument X Offset: Offset along the X-axis (push direction) from the home switch to the center of the gamma ray source collimator. Set at 191.64 cm.
Sensor Width: Width along the core axis that influences the measured value; used in calculating edge clearance (if enabled).
Analysis Name: Defined JR_LIMS analysis.
Instrument Group: Defined JR_LIMS instrument group component.
Model: Instrument model number/name of the sensing component.
S/N: Instrument serial number of the sensing component.
Manufactor's Name: Name of the manufacturer of the sensing component of the instrument.
Menu Name: Name used in the IMS menus
Full Name: Name used in IMS Reports and displays.

 

Instrument-Specific Information (digiBase Detector)

Detector Address: Instrument unique addressing ID set with the MAESTRO software provided by the vendor.
High Voltage: High voltage value applied to the photomultiplier tube.
Fine Gain: Used in conjunction with coarse gain (jumper setting in the digiBase) to amplify the signal. Affects the peak's position and width in the reported channels.
Peak Quality: Used to determine the quality of the Gaussian peak fit over the Cs peak (empirically determined).
Start Channel: Start channel of the ROI (region-of-interest).
ROI Channel Width: Number of channels for the ROI.
Display Width: Width of display about the peak center during acquisition.

 

 

 

 

Figure 10. WRMSL (up) and STMSL (down) GRA Setup Editor.

 

 

MS2: Setup

 

General Information (Figure 11)

Instrument X Offset: Offset along the X-axis (push direction) from the home switch to the center of the MS loop. Set at 221.64 cm.
Contact Width: Width along the core axis that influences the measured value; used when calculating edge clearance (if enabled).
Units: Set to SI; must match the physical MS meter setting.
Range: Set to 1.0; must match the physical MS meter setting.
Analysis Name: Defined JR_LIMS analysis.
Instrument Group: Defined JR_LIMS instrument group component.
Meter Model: Instrument model number/name of the sensing component.
Meter S/N: Instrument serial number of the sensing component.

Sensor Model: Sensor's model numberof the active component

Sensor S/N: Sensor's serial number of the active component
Manufactor's Name: Name of the manufacturer of the sensing component of the instrument.
Menu Name: Name used in the IMS menus.
Full Name: Name used in IMS Reports and displays.

Check Loop: If ON, check for the presence of an object within the loop before zeroing the meter.

 

Standard Information

Correction Factor: The vendor provides this value.

  • For standard-frequency loops (80 and 90 mm, 565 Hz), this value is 1.000.

  • For 10% high loops (80 mm only, 621 Hz), this value is 0.908.

  • For 10% low loops (80 mm only, 513 Hz), this value is 1.099.

  • For 20% low loops (90 mm only, 452 Hz), this value is 1.174.

 

 

Figure 11. STMSL (right) and WRMSL (left) MS Parameters Setup window.

 

PWAVE: Setup

 

General Information (Figure 8)

Instrument X Offset: Offset along the X-axis (push direction) from the home switch to the center of the PWL transducers. Set at 251.64 cm.
Contact Width: Width along the core axis that influences the measured value used when calculating edge clearance (if enabled).
Analysis Name: Defined LIMS analysis value.
Instrument Group: Defined LIMS instrument group component.
Model: Instrument model number/name of the sensing component.
S/N: Instrument serial number of the sensing component.
Manufactor's Name: Name of the manufacturer of the sensing component of the instrument
Menu Name: Name used in the IMS menus.
Full Name: Name used in IMS Reports and displays.

 

Liner Correction

Liner Thickness: Thickness of the core liner (2.58 mm).
Liner Velocity: Acoustic velocity of the core liner (butyrate). Should be 2100 ± 40 m/s.
Liner Delay: Calculated value equivalent to the liner thickness divided by the liner velocity.

 

Velocity Filter

The filter purpose is to remove extremely low or high velocities.
Velocity Filter: Enable or disable filtering.
Min Velocity Filter: Velocities below this value are not reported.
Max Velocity Filter: Velocities above this value are not reported.

 

Stacking

Waveform Stack: The number of waveforms stacked and averaged. Minimum 50.

 

D. Preparing Sections

Core sections measured on the WRMSL and STMSL can be run either immediately after "Core on Deck" or after they have reached temperature equilibrium. Pwave velocity if affected by temperature and should be run at a constant temperature for each section. We suggest room temperature (~ 19°C). Reach temperature equilibrium takes approximately 4 hours.

E. Making a Measurement

 

The WRMSL and STMSL are push tracks; each section pushes the previous section(s) through a set of instruments. Although it is possible to continuously process cores without a break, some of the instruments require a periodic background measurement to check and correct, if necessary, sensor drift.

By convention, we break the sequence of sections for background measurement between succeeding cores. Therefore, the functional definition of a sequence starts with the launch of IMS or with the first section measured after the "pusher" (piece of core liner filled with DI water long enough to push the end of the last section through the last sensor on the track) and ends the next time the "pusher" is used. Generally, this corresponds to the first and last section of a core.

  1. Place the whole-round section on the track between the top-of-section sensor and the pusher arm (Figure 12).

Figure 12. Blue end cap near the top-of-section sensor, clear end (bottom of section) touching the pusher.

 

2. Orient the section with the blue endcap towards the top-of-section sensor with working label (W) UP.

3. Click START to open the Section Information window. 

4. When the Section Information window opens (Figure 13), the cursor should be in the SCAN input box. If not, click in the box. NOTE: Not having the cursor in this box will prevent the label from been scanned.

Figure 13. Section Information scanning window.

5. Hold the scanner over the label and pull the trigger.

6. At the scanner beep, the Sample_ID and the LIMS_ID should correctly display on the screen. If not, re-scan.

7. If the top of the section is missing because a whole-round sample was removed, enter the length of the missing interval in the left hand area (Figure 13) so the sample position can be corrected. DO NOT place any type of spacer in front of the section to make up for the missing interval. Whole-rounds taken from the bottom of the section will not affect the measurement process.

8. Click Measure. The pusher arm moves forward and pushes the section until the blue endcap breaks the light beam of the sensor. The pusher then moves the section into the first measurement position and triggers the instruments to measure.

9. The move and measure process repeats until the pusher arm reaches its motion limits. The pusher retracts to the home position, ready to receive the next section. The Section Information window opens to repeat the process.

10. After the last section use the "water pusher". Click the PUSHER END SEQUENCE (Figure 14) button located in the Section Information window.

Figure 14. End of Sequence Pusher button.

 

11. Clicking Cancel button (and confirming) will cause loss of data for the sections which have not completed all of their measurements for a particular instrument. 

Note:  The label ID is used to query LIMS for the curated length. If not connected to the web servers, the length in the label bar code is used. Knowing the length is not critical, as the track will actually measure the length as part of its section handling process. 

 

F. Quality Assurance/Quality Control

 

Analytical Batch

The analytical batch is defined by the number of samples run between each sensor calibration. Calibrations and calibration timestamps are accessible through each sensor Instrument Interface screen.

 

Calibration

GRA

Calibration assumes a two-phase system model for sediments and rocks: minerals and interstitial water. Aluminum has an attenuation coefficient similar to common minerals and is used as the mineral phase standard. Pure water is used as the interstitial water phase standard. A piece of core liner containing a telescoping aluminum rod (5 varying thicknesses) and filled with distilled water is measured as a calibration standard. The largest diameter aluminum rod has a porosity of 0% and a bulk density of 2.7 g/cm3. Water has a porosity of 100% and density of 1.00 g/cm3. Intermediate elements verify the linearity of the log density relationship and the alignment of core and sensor. A linear least-squares fit through 3–5 calibration points yields the calibration coefficient. Total measured counts are divided by the counting time to normalize coefficients to counts per second.

MSL

Absolute susceptibility: Sample cubes are measured using the Kappabridge and results compared with corresponding readings from the Bartington instrument. Empirical correction factors have been calculated.

PWL

Pulse detection settings are checked by IODP technicians on a regular basis and do not require adjustments by the user. Pulse time is a constant which is included in the total time measured as a result of the threshold peak detection procedure used. This value changes depending on the wiring of the system. The user does not need to make adjustments to this factor. Transducer displacement and travel time delay calibrations are performed using an Aluminum standard of known velocity and thickness and distilled water at room temperature.

 

Accuracy

GRA

GRA accuracy is limited by the assumption that the measured material has the same attenuation coefficient as the calibration standards used. For general sediment-water mixtures, this should be the case and error should be <5%.

MSL

Accuracy of the susceptibility meter and sensor loop is 5% (according to Bartington).

PWL

PWL accuracy can be evaluated by measuring pure water at varying and exactly known temperatures. Past experience shows that for a properly calibrated system and good acoustic coupling, the disagreement with published sonic velocity values is less than ±20 m/s.

 

Precision

GRA

GRA precision is proportional to the square root of the counts measured, as gamma ray emission is subject to Poisson statistics. Measurements with the system have typical count rates of 10,000 (dense rock) to 20,000 (soft mud). If measured for 4 s, statistical error is <40,000 ± 200 cps, or 0.5%.

MSL

MSL precision is 2 x 10–6 SI. Susceptibility values in natural marine sediment samples over an interval of only a few meters (Milankovitch or millennial scale cyclicity) can range from a few tens to several thousands of 10–6 SI units. Typically, variations are 2–3 orders of magnitude greater than the precision, making magnetic susceptibility one of the most precise proxies for stratigraphic changes.

PWL

Measurements on standard materials such as water and calibration standards are repeatable within ±1 km/s.

III. Data File Formats

 

A. Data File Formats

The files generated by the whole round tracks (WRMSL and STMSL) include:

GRA Files

  • i_pi_gra.ini: A file containing the configuration information related to the GRA setup at the time of the measurement

  • .GRA: A data file containing all of the GRA raw measurements for a section of core.  Data include: offset, bulk density, total counts per second and a time stamp.

Magnetic Susceptibility Files

  • i_pi_ms.ini:  A file containing the configuration information related to the MS loop at the time of the measurement. 

  • .MS: A data file containing all of the magnetic susceptibility measurements for a section of core.  Data include offset, magnetic susceptibility, and a time stamp.  The file also includes the range and units and serial number of the magnetic susceptibility meter used.

  • *_MS.csv: A .csv file, saved in C:/Aux_Data, containing the mean magnetic susceptibility values for each measurement along a section as well as the range and units used at the time of measurement.

P-Wave Files

  • i_pi_pwave.ini: A file containing the configuration information related to the PWAVE instrument at the time of the given measurement

  • .PWAVE_L: A data file containing the pwave logger measurements for a section of core.  Data include: offset, distance in the caliper, travel time, and the velocity.

  • *_PWAVE-L.csv: A .csv file containing the raw waveform data for a section of core as well as the offset, velocity, travel time, distance between calipers, liner thickness, system delay, a time stamp, and laser distance.

    • System Delay is the sum of delays and includes: Travel time across the transducer caps, and electronic delays in the pulser and the digitizer.

 

B. Data Available in LORE From Past Expeditions

Each data set from the Whole Round Logger tracks (WRMSL/STMSL) is written to a file by section.  The data for the GRA, MS Loop, and P-wave are each displayed under a different report in LORE.  These reports are found under the Physical Properties heading and include Gamma Ray Attenuation Bulk Density (GRA). Magnetic Susceptibility Pass-through (MS), and P-wave Velocity Logger System (PWL). The expanded reports include the linked original data files and more detailed information regarding the measurement.

 

GRA Standard Report

  • Exp: Expedition number

  • Site: Site number

  • Hole: Hole number

  • Core: Core number

  • Type: Type indicates the coring tool used to recover the core (typical types are F, H, R, X).

  • Sect: Section number

  • A/W: Archive (A) or working (W) section half.

  • Offset (cm): Position of the observation made, measured relative to the top of a section.

  • Depth CSF-A (m): Location of the observation expressed relative to the top of a hole.

  • Depth [other] (m): Location of the observation expressed relative to the top of a hole. The location is presented in a scale selected by the science party or the report user.

  • Bulk density (GRA) (g/cm3): Computed bulk density of sample.

  • Timestamp (UTC): Point in time at which an observation or set of observations was made on the logger.

  • Instrument: Abbreviation or mnemonic for the GRA sensing device used to make this observation (GRA1 or GRA2).

  • Instrument group: Abbreviation or mnemonic for the data collection device (logger) used to acquire this observation (WRMSL or STMSL).

  • Text ID: Automatically generated unique database identifier for a sample, visible on printed labels.

  • Test No: Unique number associated with the instrument measurement steps that produced these data.

  • Comments: Observer's notes about a measurement, the sample, or the measurement process.

 

Magnetic Susceptibility Standard Report

  • Exp: Expedition number

  • Site: Site number

  • Hole: Hole number

  • Core: Core number

  • Type: Type indicates the coring tool used to recover the core (typical types are F, H, R, X).

  • Sect: Section number

  • A/W: Archive (A) or working (W) section half.

  • Offset (cm): Position of the observation made, measured relative to the top of a section or section half.

  • Depth CSF-A (m): Location of the observation expressed relative to the top of a hole.

  • Depth [other] (m): Location of the observation expressed relative to the top of a hole. The location is presented in a scale selected by the science party or the report user.

  • Magnetic susceptibility (instr. units): Magnetic susceptibility of the sample, not volume corrected.

  • Timestamp (UTC): Point in time at which an observation or set of observations was made on the logger.

  • Instrument: An abbreviation or mnemonic for the MS sensing device used to make this observation (MSLP_477 or MSLP_476).

  • Instrument group: Abbreviation or mnemonic for the data collection device (logger) used to acquire this observation (WRMSL or STMSL).

  • Text ID: Automatically generated unique database identifier for a sample, visible on printed labels.

  • Test No: Unique number associated with the instrument measurement steps that produced these data.

  • Comments: Observer's notes about a measurement, the sample, or the measurement process.

 

P-Wave Standard Report

  • Exp: Expedition number

  • Site: Site number

  • Hole: Hole number

  • Core: Core number

  • Type: Type indicates the coring tool used to recover the core (typical types are F, H, R, X).

  • Sect: Section number

  • A/W: Archive (A) or working (W) section half.

  • Offset (cm): Position of the observation made, measured relative to the top of a section or section half.

  • Depth CSF-A (m): Location of the observation expressed relative to the top of a hole.

  • Depth [other] (m): Location of the observation expressed relative to the top of a hole. The location is presented in a scale selected by the science party or the report user.