International Ocean Discovery Program

An XRF core scanner provides non-destructive elemental identification (major and minor elements) from the surface of split core sections.

Elemental range

Aluminum (Al) through uranium (U).

Detection limits for some elements

Muddy sediment measured at 10 kV, no filter, and 20 s count time (Avaatech User Guide):

The core scanner is designed to measure (ideally flat) split core sections or slabs with lengths between 30-160 cm and widths 5–13 cm. It is also possible to measure U-channels, but please note that distortion at the edges (from pushing/thumping the U-channel into material) may affect data quality.

The best results are obtained from recently recovered material that is smooth and fine-grained. Coarse-grained, desiccated, crumbly, or fractured cored material is more challenging and may not be suitable for scanning.

Please see the instructions for how to prepare a core section for measurement.

It first depends on the spatial resolution, number of source energies, and count times per section.

1. The most commonly used resolutions are 10 cm, 5 cm, 2 cm, and 1 cm. The higher the resolution, the longer it takes to scan a section because the number of measurements per section is greater. Other resolutions are possible, but for sub-cm scale measurements, please contact the facility staff who can help with estimates.
2. The available source energies are: 10 kV (no filter), 30 kV (Pd filter) and 50 kV (Cu filter) – these are each separate measurement runs.
3. Count time is the length of time specified for each measurement at each energy. This is currently set to 6 s (10 and 30 kV) and 12 s (50 kV).

Briefly, scanning at 2 cm resolution for all three energies along a typical 1.5 m core section takes 90 min/section total. Increasing the resolution to 1 cm doubles the measurement time, while decreasing the resolution to 5 cm cuts the time by just over half.

The following table may help. It assumes a 1.5 m-long section and is approximate:

*We recommend adding 10%–20% contingency time to estimates to account for core preparation and instrument down time.

Second, scanning time overall is also affected by the hours a user can work at the XRF facility. If alone, a user is subject to Texas A&M University safety policy, which stipulates they cannot work alone in the building. This limits one to 8 a.m.–5 p.m. Monday–Friday. Additional users increase the daily (evenings and overnight) and weekly (Saturday/Sunday) hours available for operation.

If you need any assistance in figuring out how much machine time you need, please do not hesitate to contact us.

Shipboard measurements

Program measurements for an entire expedition’s science party should be identified as soon as possible (e.g., precruise stage) and communicated to facility staff by the expedition project manager. A maximum of eight weeks immediately after the cores arrive at the GCR are blocked off for these measurements. Please note that these measurements are considered shipboard data and, thus, are available to the entire science party during the moratorium and publicly available afterwards through LIMS Online Reports (LORE).

Individual users

1. Calculate how long you need the XRF core scanner.
2. Contact a member of the XRF facility staff for intervals when the machine is available.
3. Submit a request using the Sample and Data Request Form. Once approved and confirmed, the facility staff will provide information to prepare for your visit.
4. Make your travel arrangements.

Please note that all users will have to undergo safety training and all first time users will be given an orientation.

The hourly rate for all users, both internal and external, is $40. This cost covers consumables, instrument wear and tear, and basic staff support. Users are expected to do sample preparation and scanning themselves. The GCR does not currently offer scanning as a service.

Please see our Visitor Information page if you are traveling to College Station.