GEM Advanced Magnetometer and Gradiometer - Quantum E-News, Summer 2004.

Welcome to Quantum, a periodic e-newsletter for professionals working with magnetic technologies. Quantum is designed to keep you up to speed on applications, case histories, and evolutions of quantum magnetometers in a variety of disciplines.

The organizers of the Student Essay Awards in Magnetics are very pleased to report the results of the competition. As noted by the judges, the overall quality and comprehensiveness of the essays submitted was impressive and all participants are to be congratulated for the time and effort that went in to producing some excellent technical papers.

1. Jozsef Garai - $US 1,250 and Profile Analyst software license for 1 year

2. Hernan Ugalde - $US 1,000 and Profile Analyst software license for 1 year

3. Chris Clark - $US 500 and Profile Analyst software license for 1 year

We would also like to thank Richard Blakely of the United States Geological Survey for providing 3 copies of "Potential Theory in Gravity and Magnetic Applications" -- a textbook that describes potential field theory while emphasizing applications in geophysics -- to 3 runner-up candidates as follows:

A summary of award-winning papers is available at http://www.gemsys.ca/magnetic_essay_entries.htm. Again, we would like to thank all participants for your efforts.

Observatories – Replacing Fluxgates with Suspended dIdD Vector Systems (Top)

Increasingly, magnetic observatories are seeking to replace aging fluxgate magnetometer systems with newer technologies that are easy to operate yet provide very high stability for performing long-term measurements. These measurements are relied on for a number of reasons, including studies of the earth's interior, upper atmosphere and solar storms.

One of the popular systems today is the new Suspended delta Inclination delta Declination (dIdD) system from GEM. This system offers a number of significant advantages over fluxgate instruments. For details, click here.

With the discovery of many world class deposits in the last 40 years, today's explorationist faces the challenge of succeeding in an environment where targets are tougher and geologically more complex.

With these challenging targets in mind, we have put together a short technical note on the optimal field procedures to use in order to maximize results from ground magnetic surveys.

While many of the suggested procedures may be known, we still receive calls on our support lines as to the optimal procedures to use. To access the technical note, click here.

About 6 years ago, a resident was digging a trench from his backyard on the beach in Southampton between Morpeth and Palmerston. He was trying to get some water for his lawn. Down about 5 feet, he came across what looked like the deck of a very large ship. He covered it up and left it for the winter.

The winter of 2001 was very severe and the ice gouged out the beach just south of the discovery revealing the ribs and possible railings of a very large ship. A teaching assistant at the University of Waterloo, James Mickle, subsequently performed a detailed magnetic survey of the site for a thesis project. His results, including comparisons of several sampling intervals, are available at http://www.chantryisland.com/Thesis%20Writeup.pdf.

Affectionately known as the "grandfather" of magnetic methods, Proton precession magnetometers continue to be used in a variety of applications. This use is despite a number of disadvantages such as slower operation, low sensitivity and high power consumption. Their use is often based on pricing and the desire to have at least some magnetic results for regional reconnaissance or as a targeting method for employing other surveys.

When selecting a Proton magnetometer, it is important to keep in mind that there are real differences in manufacturers. No where is this more evident than in GEM's GSM-19T which features the latest technology of all major manufacturers some of whom have not updated their technology in 20 years and who may not have digital data acquisition.

Together these benefits place GEM's GSM-19T at the forefront of modern systems -- an ideal entry-level system for many users, or for users who do not require the sensitivity, low power consumption or higher sampling of an Overhauser magnetometer or the sensitivity and higher sampling of a Potassium (K-Mag) geophysical instrument.

GEM recently announced the release of its Version 7.0 “Efficiency and GPS” release for its portable magnetometers and gradiometers. This release has been implemented for greater efficiency in handling input and output from GEM’s magnetic instruments as well as for implementation of additional GPS capabilities.

In developing this release, GEM President, Dr. Hrvoic noted that, “A standard issue in geophysical surveys is the expenditure of significant time on non-essential data manipulation tasks. This release streamlines data manipulation in a variety of ways. In addition, it enhances our GPS offering, providing, for example, GPS elevation data which is a key parameter for professionals working with today’s advanced magnetic modeling software.”

Version 7.0 is designed to provide enhancements (through software and accessories -- such as Multi-Sensor Boards) that streamline data acquisition and post-processing tasks). Capabilities, benefits and capabilities delivered through the “Efficiency” release, include:

For those of you who are unfamiliar with BLOGs, a BLOG is essentially a journal or diary that is available via the Internet. GEM has been developing its own journal of magnetic case histories and news for the past several months and the entries are starting to accumulate.

“Blogging is becoming increasingly popular as a means of communicating with customers and web site visitors," stated Greg Hollyer, GEM's Communication Manager. "We're here to act as a resource for our customers and this emerging media is an exciting one. We anticipate that our customers and web visitors will learn about new approaches in magnetics from the daily experiences of other professionals.”

GEM’s Blog can be accessed at http://gem-advanced-magnetometers.blogspot.com/. The Blog is described as a regular posting of information and resources for the professional interested in magnetometer, gradiometer and associated magnetic technologies, and is wholly sponsored by GEM Advanced Magnetometers. Note that as this posting is of general nature, topics may or may not represent GEM technologies.

After 24 or more hours in transit, you finally step off the plane and realize that you are in China … interior China, and specifically Wuhan – one of the 3 hottest cities in China, located in the mid-East portion of this huge and impressive country. For the next 4 days, you will be immersed in earth science technology and strategies for effective deployment of technologies for various earth science problems.

The event is the International Conference on Environmental and Engineering Geophysics (ICEEG) – a topic close to your own heart and to those of many Chinese as judged by the attendance of nearly 150 international and Chinese delegates … a respectable showing for the first ever conference of this type in China.

For more details on a unique scientific and cultural experience, click here.

One of the challenges faced by health and other governmental organizations is detecting abandoned wells, such as those drilled for water. The main issue with abandoned wells is that they can act as conduits for contaminants that migrate through the vertical "highway" along the well path. The ultimate danger is contamination of ground water. The wells can also act as conduits for gas to migrate into dwellings where the consequences (ex. explosions) can be quite severe. This latter case is documented in various scientific publications.

One GEM customer is working in an environment where there are 1.5 million wells of which 12,000 are sealed every year under the mandate of an aggressive environmental program. This program requires every property transfer to be accompanied by a well disclosure form - a challenging task since there are more than 700 property transfers per month plus there are another 12,000 new wells drilled every year.

Magnetics is one of the optimal techniques to use for well-finding based on the presence of a steel collar or cap usually found with these types of targets. A proton magnetometer, "does an impressive job leading well inspectors to lost wells, especially in open fields but they also work in towns with magnetic clutter nearby".

In this example, the target jurisdiction is in a high magnetic latitude with vertical, steel-cased wells so that the large anomalies (300 to 1,300 nT) can be easily detected from 15 to 25 metres (or more). Inspectors who were formerly using fluxgates were amazed by the performance of the proton magnetometers, especially since they cut the time to find a well from one day to minutes or an hour (basically the time required to walk around the property).

Once magnetic methods are employed, the well can then be put back into use or filled with concrete or other suitable material to prevent migration of hazardous materials into watersheds, or into homes and other facilities.

GEM is seeking case histories from our users regarding magnetometers and their applications to real-world earth science challenges or research projects. Submissions can be very short (two to three paragraphs), preferably with an image of data acquired in the field.

Now is your chance to contribute and inform your fellow earth science professionals about the creative work that you are conducting or interesting projects in which you have been involved.

GEM will enter you in a drawing for a GEM Golf Shirt (1 shirt per newsletter issue). Odds of winning are good, so please consider contacting us at info@gemsys.ca with your submission!

The Last Word - Our Users Ask About Prospecting in Low Magnetic Latitudes (Top)

"We are using the GSM 19 Overhauser magnetometer for archaeological work in Boliva. The automatic cycling does not appear to be functioning properly; for instance, when data is collected in the walkgrad mode or similar automatic cycling modes. Several of the readings are invalid, and the quality reading seems to indicate that the magnetometer does not have the opportunity to cycle properly. We have been successful getting valid readings, but only in manual modes with a minimum three-second cycle time. If you have any suggestions as to how we could trouble-shoot and be able to use the continuous cycle modes, they would be greatly appreciated."

Firstly, please note that you are working in an area of low magnetic latitudes and field intensities. This has certain implications:

1) Typically an omni-directional sensor is recommended

2) If you are using a standard sensor, it must be oriented in a strictly East-West direction to pick up the magnetic field.

Also note that since your system is operating in slow mode, it shows that all internal mechanics are operating. The first corrective action you could try is to orient your sensor E-W and see if this makes a difference. You can also check the overall variability in E-W direction by rotating the sensor about its axis which should give you an idea of the sensitivity of the sensor to orientation.

Otherwise, there are several trouble-shooting techniques:

1) Turn the tune intiatialize and automatic cycling to OFF and set the field to the local value -- a solution that will work as long as your local gradients are not too high. This may enable you to continue. We recommend first testing the system as a walking system but only in a single location
to see whether the data is reading and is repeatable. Also check the signal strength during this test. Then try in walking mode on a real line of data.

2) If changing the cycling does not work, check the magnetometer in stationary mode. First, place it in Base mode and try measuring with different (i.e. slow and fast cycle times). This will give you an idea of the sensitivity to walking mode -- a mode that naturally increases the noise of any magnetometer system.

The GSM-19 is very well suited for prospecting in low magnetic latitudes especially in comparison with proton systems based on the high signal-to-noise ratio related to the Overhauser physics and we anticipate that these checks should solve your issues. However, if not, it may be a systematic problem that needs to be evaluated in our manufacturing facility. There may be a problem with the sensor or Radio Frequency generator that is difficult to trouble-shoot remotely.

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Copyright 2004. GEM Systems, Inc. Advanced Magnetometers. All rights reserved with the exception of organizations that have contributed links to this issue. Our thanks to the contributors who have made this edition possible, and who are identified in the text of related articles or through their company websites. Note that some quotes relating to industry-specific trends may have been obtained from public-domain sources, and are not intended to promote GEM Systems, Inc. Other examples may not necessarily reflect GEM products; rather these examples are intended to illustrate the use of magnetics and magnetometry for selected applications.