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.
As many of you may remember, GEM requested our users’ help in completing a 10 minute survey designed to evaluate our users’ interests in upcoming technologies and communications offerings.
The results are now in and we are pleased to announce that Kamil Rozimant from the Department of Applied and Environmental Geophysics, Faculty of Science, Comenius University of Bratislava, Slovakia was our award winner.
Congratulations to our award winner, and our thanks to all whom participated. We are actively following up on your technology and communication preferences for upcoming product and newsletter releases.
GEM has recently reviewed its ground offerings and decided to upgrade its core geophysical data acquisition system, the GSM-19 Overhauser “Walking” magnetometer. Now, when you purchase a Walking magnetometer, 5 second sampling is now included as a valid survey setting. Previously, this was an option that was purchased separately.
This change means that the Overhauser magnetometer is directly comparable to optically pumped devices, with the exception of GEM’s K-Mag, which is the world’s most sensitive commercial ground magnetometer / gradiometer. The Overhauser magnetometer is also much less expensive than caesium devices, providing excellent value for our users.
However, GEM’s upgrades do not stop there:
As well, additional Version 7 upgrades are designed to make all of GEM’s magnetometers / gradiometers more efficient through enhanced data output. Now, data can be easily output to ASCII-format files that are compatible with industry-standard software packages from Encom, Geosoft and Intrepid. Moreover, output is programmable so the user has the choice of the final arrangement of data in the output file. This gives additional flexibility and convenience for data processing work.
As GEM moves forward into the future, we continue to listen to our users’ requests for new functionality and we are pleased that the new capabilities from GEM upgrades are receiving positive attention from all users of magnetometers and gradiometers.
Since its inception in 1980, GEM has provided proactive support to earth science groups through delivery of the latest magnetometers for ground and airborne applications. And our loyal customers have continued to support us throughout this period for a variety of reasons.
“Over the last 25 years, GEM has provided solutions that help earth science professionals address their challenges in many disciplines,” said Dr. Ivan Hrvoic, President of GEM. “Whether searching for minerals, researching earthquakes or helping academics meet their scientific and teaching goals, our focus is always on enhancing magnetic technologies. The widespread use of our technologies (more than 100 countries worldwide) is one of the best testimonials we can provide as to GEM’s success in meeting customer needs.”
The company’s offerings focus on Overhauser, Proton Precession and optically pumped Potassium instruments – the only company worldwide that provides such an extensive portfolio of total field magnetometers for mineral exploration, near surface geophysics, earthquake research and other applications.
Many professionals are using the Overhauser magnetometer – a GEM-developed technology that is now a global standard based on its data quality, efficiency and low power consumption. In addition, traditional Proton Precession technologies have found new life at GEM through a Research and Development program resulting in the highest sensitivity and robust Proton instrument today.
The Potassium magnetometer is another example of a novel technology that delivers the highest sensitivity and sampling rates for both airborne and ground work. In the air, the Potassium system is used for acquisition of very high-quality magnetic and gradient data in either fixed-wing or helicopter applications. On the ground, it serves as either a base station or a portable unit that can be towed behind a sled or all terrain vehicle (ATV), depending on project needs.
GEM Advanced Magnetometers delivers magnetometers and gradiometers with built-in GPS for high-sensitivity, accurately-positioned ground, airborne and stationary surveys. Each instrumentation system offers unique benefits in terms of acquisition of high-quality data. These core benefits are complemented by GPS navigation options with metre, sub-metre and centimetre positioning. In addition to a 25-year history of innovation in magnetometer design and manufacturing, GEM is known for its customer service and support.
As part of our program to stay in touch with our customers, we will be on hand at two upcoming conferences in the United States in the next few weeks. These include the Society of Exploration Geophysicists annual meeting in Houston, and the American Geophysical Union’s upcoming meeting in San Francisco.
Some of the technologies that GEM will be featuring include:
We cordially invite you to visit GEM’s booth and learn about these new technologies in person at SEG in Houston from October 6 to 9, 2005. GEM’s booth number is 2261 …. located conveniently across from the Internet cafe.
Or, if you prefer, drop in and see us at the AGU meeting from December 6 through 10 in San Francisco. We will be at booth 013 … again located conveniently across from the Internet cafe.
Our focus at the AGU will be similar to the SEG with the exception that we will also be featuring our Earthquake Research technologies. A poster describing these technologies and their implementation at a site in Mexico will be on display on Friday, December 9 on Level 2. The number of the poster is T51B – 1339.
The Tri-Directional Helicopter Gradiometer from GEM was the first three-axis gradiometer developed globally. Since its inception in the mid 1980s, the system has been outfitted with optically pumped Potassium sensors and has evolved into a reliable platform for different applications, including mineral exploration.
This special gradiometer consists of a three-armed towed bird configured with 4 sensors for calculation of magnetic gradients, including vertical and horizontal across and along track gradients. Additional components include GPS for accurate positioning of the bird during flight. Data capture is either to the GSMP-30A acquisition console or a 3rd party unit.
Currently, the gradiometer is being flown by a major airborne contracting company in Western Canada. As we hear more about the results and quality, we’ll be sure to keep our interested readers informed.
Several researchers from St. Petersburg are now in the works of preparing a book about the use of magnetic prospecting in archaeology – specifically with the GEM GSM-19 Overhauser magnetometer / gradiometer. As noted by the researchers, “We like your instrument, it was the main one for all our investigations since 1993. Now, we use two of them; one is recording the temporal changes of Earth’s magnetic field.”
The book will be in English and will be entitled, “Magnetic Prospecting in Archaeology.Ten Years of Using the Overhauser GSM-19WG Gradiometer.” It will be about 70 pages with many illustrations and photos (with some of them in colour). The objective is to provide a high quality, attractive volume for archaeologists planning to use magnetic prospecting for the investigation of their sites. Although the authors previously published a smaller booklet, they have decided for the new edition as there are many new examples to show.
It will start with a short introduction part on the principles of magnetic survey in archaeology, but the major focus will be on examples of the application of the instrument in archaeology in many countries, where we worked since we bought the first GEM instrument in 1993, and the second one in 2004. This includes Denmark, Norway, Greece, Egypt, Syria, Ukraine, Germany, Sweden, Estonia, and Russia.
The issue date is currently set for next April when the researchers’ colleague, Olfert Voss, archaeologist from the National Museum in Copenhagen, whom has contributed to magnetic prospecting in Denmark for the last 13th seasons, celebrates his 80th birthday. Olfert is considered to be the Danish “chief”; he is the main member of the geophysical team when work is in Denmark.
Interest continues to be expressed in GEM’s SuperGrad system for earthquake prediction monitoring and research. The latest interest is from Romania which recently hosted the Balkan Geophysical Congress in Bucharest.
During the Congress, GEM was pleased to make several presentations, including a Commercial Presentation on GEM’s Technologies, and a new scientific paper describing the latest work in installing a SuperGrad earthquake research system in Oaxaca, Mexico. To download the paper, click here.
Members of the Romanian scientific community are highly interested in SuperGrad for its ability to monitor larger earthquakes such as those encountered in Romania. During discussions, the scientists expressed a strong interest in having an installation in place soon.
Based on these discussions, GEM has decided to add a Romanian SuperGrad station to complement its existing stations in Israel and Mexico. (A second Israeli installation will also be set up in a region more tectonically active than the initial site.)
In Romania, installation is planned for the Romanian “hot” area in the province of Vrancea. Earthquakes happen at great depths in Vrancea … down to 200 km. However, the SuperGrad is proposed to have the ability to detect any “big” earthquake (M7 or more) at depths over 100 km and close to 200 km. Detection is by ULF (1 to 10 mHz) magnetic gradients and total magnetic fields.
Vrancea is some 300 km away from the capital, Bucharest, but a big earthquake in Vrancea could endanger the capital and cause many casualties. A precursor detected by the SuperGrad would be used to issue an early warning (few hours before the earthquake) and save many lives.
The Balkan Geophysical Congress held in Bucharest was an excellent forum for magnetics with three sessions, including a poster session. One of the highlights was a presentation from our Turkish colleague, Muzaffer Ozpu Arisoy, a researcher at Cumhuriyet University. The talk is entitled, “Evaluation of Different Receiver Orientations and Receiver Separations in Magnetic Gradiometer Method.”
Mr. Arisoy’s presentation reviews the role of differential gradiometer measurements, typically referred to as “gradients” in the working literature. It includes mathematical formulations for the various field values, a discussion of the roles of different “gradients” for resolving objects, and mathematical models for various sensor separations.
To download your copy, click here.
The Chinese Earthquake Administration is taking delivery on a substantial order for GSM-90 EUROMAG magnetometers. The systems will be employed across China as part of its earthquake monitoring program. CEA ordered the GSM-90 F1 model, so called because it samples up to one sample a second (standard monitoring period described by geomagnetic organizations and bodies, such as Intermagnet.
Before discussing the orientation guidelines for Potassium sensors, it is important to understand the concept of “dead zones”. Specifically, dead zones occur when the angle between the magnetic field and the sensor axis are such that no magnetic measurement can be obtained.
The presence of dead zones means that there is an optimal operating window for optically pumped magnetometers (i.e. in which optimal orientation can be obtained).
In all optically pumped magnetometers, there is an interplay of optical polarization and Radio Frequency (RF) depolarization of the two energy levels present (i.e. for alkali metals) … resulting in ampltitude modulation of the polarizing light.
Light polarization requires a colinear magnetic field whereas RF depolarization works with the magnetic field at a right angle. As a consequence, 0 and 90 degree directions of the magnetic field are forbidden; they fail in either polarization or depolarization.
The dead zone effect covers more than several degrees around each of the “forbidden” angles; hence angles close to 0 or 90 degrees are not very efficient and the spectral lines are weak. We recommend operation between 10 to15 and 75 to 80 degrees.
Potassium has 4 spectral lines and we only use one of them, at the lowest frequency in any field. This line is the strongest for angles up to 45 degrees. For angles above 45 degrees, line number 4 is strongest (but this is irrelevant since we do not use this line). Line number 1 is the strongest at about 30 to 35 degrees.
Say the inclination in your area was 65 degrees (i.e. 25 degrees off vertical). This is close enough for very good results if you install the magnetometer sensors vertically.
For inclination angles that are near horizontal, simple geometrical consideration will tell you that the horizontal installation of sensors will not work if the sensor axes are in the East-West direction. Even for North – South direction of the sensor axes, the angle would be some 65 degrees … which is less favourable than 25 degrees.
GEM is pleased to offer the longest warranty in the geophysical instrumentation industry as a demonstration of its confidence in the quality of its products. All GEM products are waranteed to the original purchaser against defective parts and workmanship for two (2) years from the date of original shipping. A summary document of the precise TERMS and CONDITIONS is provided at https://www.gemsys.ca/GEM_warranty_card.htm
As part of its customer service program, GEM recently implemented an Online Maintenance capability for all customers using its magnetometers. Click the link above and you will also see a series of entry fields at the bottom of the form. Simply complete the form and submit and your warranty will be forwarded directly to us.
Then, you will be all ready for any updates that GEM prepares – a timely way to acquire new and upgraded features via the Internet.
As usual, we leave the last word to our customers – our key focus in ensuring that we continue to serve the market effectively and to our customers’ satisfaction.
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Copyright 2005. 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.BACK